JPH09212909A - Storage element and optical pickup device - Google Patents

Abstract

(57) Abstract: A memory element that is small, high-density, and large-capacity and that can be handled like an electronic component is provided. A storage element (1) includes an optical disk (10) for carrying information reproduced by using light, a turntable (15) that supports the central portion of the optical disk (10), and a spindle motor that rotates the turntable (15). , An optical pickup device 3 for recording information on the optical disc 10 and reproducing information from the optical disc 10 using light
0, a package 50 that seals them, and a plurality of connection pins 56 that are provided on the sides of the package 50 and that connect the circuit in the package 50 to an external circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage element for storing information using an optical disk as a storage medium and an optical pickup device suitable for use in this storage element.

[0002]

2. Description of the Related Art In recent years, in the field of memory, the capacity has remarkably increased. On the other hand, in PDA (Personal Digital Assistance) represented by Newton, Magic Link, Zaurus (all are trade names) and the like, there are some that achieve extremely high performance by using MPU (microprocessor unit).

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
There is no optimum storage device to be built into a small portable terminal such as, in terms of external size, capacity and recording density. For example, in the field of semiconductor memory, there is no high density memory. DVDs (digital video disks), which are expected to be used in the field of mass storage devices,
It is too large for a 3.5-inch MO (magneto-optical) disk drive. Further, the MD (mini disc) device is too large and the access speed is too slow. On the other hand, a small stamp size flash memory card has been developed and commercialized, but it has too small a capacity and is too expensive.

Therefore, in a small portable terminal such as a conventional PDA, although the MPU is used to achieve extremely high performance, the memory capacity is extremely smaller than that of a notebook personal computer. Therefore, it lacks an important part of multimedia, such as not being able to handle moving images.

By the way, a disk type storage device is suitable as a high density and large capacity storage device. However, it is necessary to have an external dimension of less than 1 inch in order to be built in the small portable terminal as described above.
There is no disk type storage device whose external dimensions are less than 1 inch.

Further, in the field of optical memory, research on ultra-high density has been actively conducted, but there is a limit to shortening the wavelength of laser and increasing NA (numerical aperture) as a means for increasing the recording density. there are, 20G bit / inch ² levels are not yet likely realized. Further, in recent years, a solid immersion lens (hereinafter, also referred to as SIL).
A technique for achieving ultra-high density by using is also reported. SI
L is a lens that applies the principle of a liquid immersion objective lens of a microscope to an optical memory.
Can be increased to reduce the spot size. However, since the conventional research on the SIL technology has been applied to the existing removable optical disk device, there is a possibility that the removable property of the optical disk may be lost in order to reduce the air gap between the SIL and the optical disk. That said, there were extremely technical difficulties.

On the other hand, there are many fields in which the recording medium does not need to be removable. In such a field, a storage device that is built in the device and does not require an interface such as SCSI is required, but a storage device having a large capacity and having random accessibility is required. Furthermore, from now on, a storage device which can be handled like an electronic component and can be put in all devices other than a computer and which gives intelligence to the device is required. In that case, in the process of the manufacturing line, it is desired to pass the reflow solder through the storage device like a semiconductor memory, but this is not possible with a plastic substrate.

The present invention has been made in view of the above problems, and a first object thereof is to provide a memory element which is small in size, high in density and large in capacity, and which can be handled in the same manner as an electronic component. is there.

A second object of the present invention is to provide an optical pickup device suitable for use in the above storage element.

[0010]

According to another aspect of the present invention, there is provided a storage element, which comprises an optical disk for carrying information reproduced by light, and a rotation driving means for rotating the optical disk.
An optical pickup device for performing at least reproduction of information on the optical disc and reproduction of information from the optical disc by using light, a package for encapsulating the optical disc, the rotation driving means and the optical pickup device, and provided on this package, And a terminal for connecting a circuit in the package to an external circuit.

The optical pickup device according to claim 18 is
An optical pickup device for performing at least one of recording information on an optical disc for carrying information reproduced using light and reproducing the information from the optical disc, wherein the optical pickup device emits light for irradiating the optical disc. Means, a light receiving means for receiving return light from the optical disc, and an optical system for irradiating the optical disc with the light emitted from the light emitting means and for guiding the return light from the optical disc to the light receiving means. Including a solid immersion lens disposed opposite to each other, the solid immersion lens is set to have optical characteristics in consideration of the thickness of the transparent substrate of the optical disc existing between the solid immersion lens and the recording layer of the optical disc. There is something.

An optical pickup apparatus according to a twenty-first aspect is
An optical pickup device for performing at least one of recording information on an optical disc for carrying information reproduced using light and reproducing the information from the optical disc, wherein the optical pickup device emits light for irradiating the optical disc. Means, a light receiving means for receiving the return light from the optical disc, and an optical system for irradiating the optical disc with the light emitted from the light emitting means and for guiding the return light from the optical disc to the light receiving means. A first entrance / exit portion, which is arranged so as to face each other, receives light from the light emitting means and emits return light from the optical disc, and emits light from the light emitting means and receives return light from the optical disc. Second
Of the light emitting means, which is incident on the first light emitting and receiving section, reflects the light from the light emitting means on the convex spherical surface, and the light emitting means reflected by the first reflecting section. The optical block includes a second reflecting portion that reflects light on the concave spherical surface so that the light is emitted from the second incident and emitting portion and converges on the outside of the second incident and emitting portion. The optical characteristics are set in consideration of the thickness of the transparent substrate of the optical disc existing between the optical block and the recording layer of the optical disc.

In the storage element according to the first aspect, since the optical disk, the rotation driving means and the optical pickup device are sealed by the package, the structure is simple although the optical disk is not removable, and the high density of the optical disk is obtained. ， In combination with the property of large capacity, it becomes possible to make a storage element of small size, high density, and large capacity.
It can be handled like electronic parts.

In the optical pickup device according to claim 18, the solid immersion lens included in the optical system is
Since the optical characteristics are set in consideration of the thickness of the transparent substrate of the optical disc existing between the solid immersion lens and the recording layer of the optical disc, it is possible to increase the numerical aperture without being adversely affected by the transparent substrate. As a result, higher density is possible.

In the optical pickup device according to the twenty-first aspect, the optical block included in the optical system has optical characteristics in consideration of the thickness of the transparent substrate of the optical disc existing between the optical block and the recording layer of the optical disc. Since it is set, the numerical aperture can be increased without being adversely affected by the transparent substrate, and as a result, high density can be achieved.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the storage element according to the embodiment of the present invention, and FIG. 2 is a partially cutaway bottom view showing the storage element shown in FIG. Note that FIG. 1 shows a cross section taken along the line AA ′ in FIG.

As shown in these figures, the storage element 1 according to the present embodiment has an optical disk 10 for carrying information reproduced by light, and a turn for supporting the central portion of the optical disk 10. A table 15, a spindle motor described later for rotating the turntable 15, and an optical pickup device 3 for recording information on the optical disc 10 and reproducing information from the optical disc 10 using light.
0, a package 50 that seals them, and connection pins 56 that are provided on the sides of the package 50 and serve as a plurality of terminals for connecting the circuit in the package 50 to external circuits.

The package 50 has a box-shaped container portion 51 having an opened bottom portion and a lid portion 52 for closing the bottom portion of the container portion 51. The container portion 51 and the lid portion 52 are
For example, it is made of ceramic. A shaft extending in a direction perpendicular to the surface of the lid 52 is fixed on the lid 52 in the package 50, and the turntable 15 is rotatably attached to the shaft.

The optical disc 10 comprises a transparent substrate 11 and a magneto-optical recording layer 12 formed on one surface of the substrate 11, and the magneto-optical recording layer 12 is arranged on the lower side of the turntable 15. It is fixed in contrast. Board 11
For example, the thickness unevenness can be suppressed to 1 μm or less by using glass or the like. The magneto-optical recording layer 12 is an area where information is recorded and reproduced by the magneto-optical recording method.

The optical pickup device 30 includes the package 5
A shaft 31 fixed to the upper surface of the container 51 in 0 and extending in a direction perpendicular to the surface of the upper surface, and a cylindrical rotating body 3 rotatably mounted on the shaft 31.
2, a magnetic head arm 33 disposed below the optical disk 10 and having a base side fixed to the rotating body 32,
The magnetic head arm 33 is provided with a magnetic head 34 for magnetic field modulation attached to the tip of the arm 33, and an optical head arm 35 disposed above the optical disk 10 and having a base side fixed to the rotating body 32. There is. The magnetic head arm 33 and the optical head arm 35 are arranged so that their tip portions face each other with the optical disk 10 interposed therebetween.

A solid immersion lens 37 held by a lens holder 36 is attached to the optical disk 10 side at the tip of the optical head arm 35. The solid immersion lens 37 has a lower surface formed into a flat surface and an upper surface formed into an aspherical curved surface (for example, a parabolic surface). At the tip of the optical head arm 35, at a position above the solid immersion lens 37,
A reflection prism 38 having a reflection surface of 45 ° with respect to the surface of the optical disc 10 is provided. A laser coupler 40 is provided on the base side of the optical head arm 35, and between the reflection prism 38 and the laser coupler 40 in the optical head arm 35, a polarization hologram 41 and a two-divided optical rotation are sequentially provided from the laser coupler 40 side. A plate 42 is provided.

Magnetic head 34 and lens holder 36
Are both the optical disc 1 as the optical disc 10 rotates.
The flying head is configured to float so as to face 0 with a predetermined gap (air gap).

For focus servo and tracking servo, the laser coupler 40 is movable around the laser coupler 40 in the front-back direction of the laser coupler 40, that is, the focus direction and the direction perpendicular to the paper surface of FIG. 1, that is, the direction corresponding to the radial direction of the optical disk 10. An actuator 43 is provided. As the actuator 43, for example, a piezoelectric element is used.

The memory element 1 according to the present embodiment further includes
Magnetic head arm 33 and optical head arm 35
Is provided with an arm driving motor 44 for rotating around the shaft 31 to perform a seek. The arm driving motor 44 is provided with a container portion 51 in the package 50.
Has a yoke 45 fixed to the upper surface of the.
The yoke 45 has an upper portion 45a and a lower portion 45 which face each other.
b, and a connecting portion that connects between both ends of the upper portion 45a and the lower portion 45b. Arm drive motor 4
Reference numeral 4 denotes a magnet 46 fixed to the lower surface of the upper portion 45 a of the yoke 45, and the magnet 46 and the yoke 45.
And the coil 47 fixed to the rotating body 32.

The memory element 1 according to the present embodiment further includes
A circuit board 55, which is fixed to the upper surface of the container portion 51 in the package 50 and constitutes a circuit in the package 50, is provided. The circuit board 55 is connected to the connection pins 56.

FIG. 3 is a plan view showing an example of the outer shape of the memory element 1 according to this embodiment, and FIG. 4 is a side view of the memory element 1 shown in FIG. In the storage element 1 in the example shown in these figures, the package 50 has both a vertical length and a horizontal length of 2
4.20 mm (TYP (standard value)), the entire length and width of the storage element 1 including the connection pins 56 are both 25.15.
It has a square shape of ± 0.13mm and a thickness of 4.50.
mm (MAX (maximum value)). Package 5
The length of one side of the bottom portion of 0 is 23.12 ± 0.5 mm. 1 on each of the four sides of the package 50
Seven connection pins 56 are provided. Each connection pin 56
Have a total length of 2.28 mm (MIN (minimum value)), and the length of the small diameter portion on the tip side is 0.5 mm (MIN (minimum value)). The width of each connecting pin 56 on the base side is 0.75 ± 0.2 mm, and the width of the small diameter part on the tip side is 0.42.
It is ± 0.13 mm. The distance between the connecting pins 56 is
It is 1.27 mm (TYP). The optical disc 10 built in the storage element 1 shown in FIGS.
Has a thickness of 0.3 mm and a diameter of 0.7 inch (17.78 mm), for example.

FIG. 5 is a plan view of the spindle motor, and FIG. 6 is a sectional view of the spindle motor shown in FIG. As shown in these figures, the lid 52 of the package 50 includes
The shaft 14 extending in a direction perpendicular to the surface of the lid 52 is fixed via the pedestal 13. Turntable 15
Is rotatably attached to the shaft 14 via a bearing 16. The optical disk 10 is sandwiched between the turntable 15 and the disk pressing member 17,
It is fixed to the turntable 15. A spindle motor 20 for rotating the turntable 15 is arranged around the turntable 15 and fixed to a lid portion 52, a coil 22 attached to the yoke 21, and an outer peripheral portion of the turntable 15. And a rotor magnet 22 that is attached to the inner surface of the yoke 21 and faces the inner peripheral portion of the yoke 21. The yoke 21 is a disk having a substantially circular hole into which the turntable 15 and the rotor magnet 22 are inserted, and the yoke 21 is a magnetic head arm 3 of the disk.
3 and a portion corresponding to the magnetic head 34 are cut out. The yoke 21 is further formed with seven notches at a predetermined angular interval from the inner circumference side to the outer circumference side, and the coil mounting portion 21 is provided between the notches.
a is formed. The coil 22 is wound in a rectangular parallelepiped shape in advance and is externally fitted to the coil mounting portion 21a. Note that FIG. 5 shows a state in which the optical disc 10 and the disc pressing member 17 in FIG. 6 are removed.

Next, the structure and operation of the optical system of the optical pickup device 30 will be described in detail with reference to FIGS. 7 and 8. FIG. 7 is an equivalent view of the optical system in the optical pickup device 30 with the reflection prism 38 in FIG. 1 omitted. FIG. 8 is a perspective view showing the upper side of the two-part optical rotation plate 42 in FIG. 7. In these figures, for convenience, the diffraction angle of the diffracted light by the polarization hologram 41 and the laser coupler 40 are shown larger than they actually are. The laser coupler 40 includes a single semiconductor substrate 6
On top of the semiconductor laser 61 and a plurality of photodetectors 6
2a to 62j are formed and configured. The semiconductor laser 61 emits, for example, P-polarized light (left-right direction in FIG. 7, linearly-polarized light in the direction perpendicular to the paper surface of FIG. 1). The polarization hologram 41 diffracts only S-polarized light (linear polarized light whose polarization direction is orthogonal to P-polarized light). The two-part split optical rotation plate 42 includes a right optical rotation plate 42R that rotates the incident light by a predetermined angle in the right rotation direction, for example, 22.5 °, and emits the light, and an incident light in the left rotation direction by a predetermined angle, for example, 22 °. Left rotatory plate 4 that rotates and emits only 5 °
It is composed of 2L. Right rotatory plate 42R and left rotatory plate 4
The dividing line with 2L is arranged so as to be parallel to the direction corresponding to the radial direction of the optical disc 10.

The solid immersion lens 37 collects the light emitted from the semiconductor laser 61 and passing through the polarization hologram 41 and the two-divided optical rotation plate 42, and spots it on the magneto-optical recording layer 12 through the substrate 11 of the optical disk 10. It is designed to irradiate. Here, the solid immersion lens 37 is set so as to have optical characteristics in consideration of the thickness of the substrate 11. That is, the solid immersion lens 37 is set so as to obtain desired optical characteristics as a lens only when it is combined with the substrate 11. This will be described in detail in the description of the fourth embodiment. Further, the refractive index of the solid immersion lens 37 is equal to the refractive index of the substrate 11, and is, for example, 1.57. Further, the solid immersion lens 37 has a lower surface formed into a flat surface and an upper surface formed into an aspherical curved surface (specifically, a shape close to a parabolic surface of a finite system), which is a solid having a spherical surface. This is because it has both the functions of the immersion lens and the convex lens.

As shown in FIG. 7, the P-polarized light emitted from the semiconductor laser 61 passes through the polarization hologram 41 as it is and enters the two-divided optical rotation plate 42, where it passes through the right optical rotation plate 42R. The emitted light is rotated by 22.5 ° in the right rotation direction, and the light that has passed through the left optical rotation plate 42L is emitted by being rotated by 22.5 ° in the left rotation direction. Two-part optical rotation plate 42
The light that has passed through enters the solid immersion lens 37, and by this solid immersion lens 37,
The light is focused on the magneto-optical recording layer 12 of the optical disc 10. The solid immersion lens 37 has an effect of increasing the numerical aperture (NA) and decreasing the spot diameter, which will be described in detail in the description of the fourth embodiment. In the memory element 1 according to the present embodiment, by using the solid immersion lens 37 or the like, 20 Gbit /
Ultra high density recording of about ² inches has been realized, and a storage capacity of about 200 to 500 Mbytes has been realized by using the optical disk 10 having a diameter of about 0.7 inch.

The light applied to the optical disk 10 is reflected by the magneto-optical recording layer 12 and is reflected by the solid immersion lens 3
Return to side 7. Here, when the magneto-optical recording data is recorded in the magneto-optical recording layer 12, the magneto-optical recording layer 1
The reflected light at 2 has its polarization direction rotated by + θ _k or −θ _k (θ _k is the Kerr rotation angle) depending on the magnetization direction in the magneto-optical recording layer 12. It should be noted that the reference signs are + for right rotation and − for left rotation. This return light is condensed by the solid immersion lens 37 and passes through the two-part optical rotation plate 42. Here, the light that has passed through the right optical rotation plate 42R on the outward path passes through the left optical rotation plate 42L on the return path, and the light that has passed through the left optical rotation plate 42L on the outward path.
The light passing through L passes through the right optical rotation plate 42R on the return path.
As a result, the light passing through the left optical rotation plate 42L on the return path is further rotated by 22.5 ° in the right rotation direction and is rotated by + 45 ° in total in the two-division optical rotation plate 42. On the other hand, the light passing through the right optical rotation plate 42R in the return path is further rotated by 22.5 ° in the left rotation direction, and is rotated by a total of −45 ° in the two-part optical rotation plate 42. In this way, the two-divided optical rotation plate 42 on the return path.
The light that has passed through will have an S-polarized component. The light that has passed through the two-divided optical rotation plate 42 on the return path is incident on the polarization hologram 41, and the P-polarized component is not diffracted but is incident on the photodetectors 62e and 62f arranged near the emission position of the laser light in the laser coupler 40. . on the other hand,
The S-polarized component is diffracted by the polarization hologram 41. Here, as shown in FIG.
Are formed so as to have a lens action, and the + 1st-order diffracted light 65 is once converged on the way and is then diffused to be photodetectors 62a to 62d on the laser coupler 40.
The first-order diffracted light 66 is incident on the photodetectors 62g to 62j on the laser coupler 40 as converged light.

FIG. 9 is a plan view of the laser coupler 40, and FIG.
FIG. 4 is a side view of the laser coupler 40. As shown in FIG. 9, the laser coupler 40 includes a semiconductor laser 61 formed on a semiconductor substrate 60 and a plurality of photodetectors 62a to 62a.
62j. As shown in FIG. 10, on the semiconductor substrate 60, a reflection mirror portion 63 for reflecting the emitted light of the semiconductor laser 61 upward is formed at a position facing the laser light emitting portion of the semiconductor laser 61. There is. The photo detectors 62e and 62f are arranged side by side in the vicinity of the laser light emission position on the semiconductor substrate 60. Each of the photodetectors 62e and 62f is formed in a fan shape with an angle of 90 °, and the two are combined to form a semicircular shape. The dividing lines of the photodetectors 62e and 62f are arranged so as to be parallel to the direction corresponding to the track direction on the optical disc 10. The photo detectors 62a to 62d are arranged at the positions for receiving the + 1st order diffracted light 65 shown in FIG. 7, and the photo detectors 62g to 6g.
2j is arranged at a position where the −1st order diffracted light 66 shown in FIG. 7 is received. A group of photo detectors 62a-6
Of 2d, the photodetectors 62b and 62c are formed in a narrow band shape and are arranged side by side on the center side, and the photodetectors 62a and 62d are formed in a wide band shape and are arranged outside the photodetectors 62b and 62c, respectively. It is arranged. Photodetector 62a-
The dividing line between 62d is arranged so as to be parallel to the direction corresponding to the radial direction of the optical disc 10. Similarly, among the group of photodetectors 62g to 62j, the photodetectors 62h and 62i are formed in a narrow strip shape and are arranged side by side on the center side.
2g and 62j are formed in a wide band shape and are arranged side by side outside the photodetectors 62h and 62i, respectively. The dividing line between the photodetectors 62g to 62j is arranged so as to be parallel to the direction corresponding to the radial direction of the optical disc 10. Each photo detector 6
Each of 2a to 62j outputs a signal corresponding to the amount of received light.

Next, with reference to FIG. 11, the principle of detection of the magneto-optical reproduction signal in the memory device 1 according to this embodiment will be described. First, FIG. 11A shows the polarization direction of the P-polarized light emitted from the semiconductor laser 61. The P-polarized light passes through the polarization hologram 41 as it is and enters the two-divided optical rotation plate 42. Here, the light that has passed through the right optical rotation plate 42R is α (for example, 22.
The light that has been rotated by 5 °) and that has passed through the left optical rotation plate 42L is emitted after being rotated by α in the left rotation direction. FIG. 11 (b),
In (c), the right rotation direction is + and the left rotation direction is −, and the polarization direction of the light passing through the right optical rotation plate 42R and the left optical rotation plate 42.
And the polarization direction of the light passing through L. The light that has passed through the two-part optical rotation plate 42 is passed through the solid immersion lens 37 to the magneto-optical recording layer 12 of the optical disc 10.
Focused on top.

The light applied to the optical disk 10 is reflected by the magneto-optical recording layer 12, and at that time, the polarization direction is rotated by + θ _k or −θ _k depending on the magnetization direction in the magneto-optical recording layer 12, and solid immersion is performed. It returns to the lens 37 side. In the description below, it is assumed that the polarization direction is rotated by + θ _k . The return light from the optical disc 10 is condensed by the solid immersion lens 37,
It passes through the divided optical rotation plate 42. Here, since the light passing through the left optical rotation plate 42L in the return path is rotated by a total of + 2α (= + 45 °) in the two-part optical rotation plate 42, as shown in FIG. 11D, together with the Kerr rotation angle. + 2α
The polarization direction is rotated by (= + 45 °) + θ _k .
On the other hand, the light passing through the right optical rotation plate 42R on the return path is 2
Since the light is rotated by a total of −2α (= −45 °) in the split optical rotation plate 42, the polarization direction is changed by −2α (= −45 °) + θ _k together with the Kerr rotation angle as shown in FIG. It is being rotated.

As a result, the light that has passed through the left rotatory plate 42L and the right rotatory plate 42R in the return path both have S-polarized components, but the sizes of the S-polarized components are different from each other.
That is, the magnitude of the S-polarized component of the light that has passed through the left optical rotation plate 42L on the return path is as shown in FIG.
Is a size corresponding to | sin (+ 2α + θ _k ) |
As shown in FIG. 11G, the magnitude of the S-polarized component of the light that has passed through the right optical rotation plate 42R on the return path is | sin.
(−2α + θ _k ) |
Due to the relationship of (+ 2α + θ _k ) |> | sin (−2α + θ _k ) | . The magnitude relationship of the magnitude of the S-polarized component is reversed according to the magnetization direction in the magneto-optical recording layer 12. Therefore, the magneto-optical reproduction signal can be detected based on the magnitude relationship between the S-polarized components of the light that has passed through the left rotatory plate 42L and the light that has passed through the right rotatory plate 42R in the return path.

The S-polarized component of the light passing through the two-division optical rotation plate 42 on the return path is diffracted by the polarization hologram 41, and the + 1st-order diffracted light 65 is converged on the way and then enters the photodetectors 62a to 62d as light to be diffused. Then, the −1st-order diffracted light 66 enters the photodetectors 62g to 62j as the converged light. Therefore, the S-polarized component of the light that has passed through the left optical rotation plate 42L on the return path is the photodetectors 62a, 62b, 62i, 62 in FIG.
The S-polarized component of the light that has entered j and has passed through the right optical rotation plate 42R in the return path is the photodetector 62 in FIG.
It is incident on c, 62d, 62g and 62h. From the above, assuming that the output signals of the photodetectors 62a to 62j are a to j, the magneto-optical reproduction signal MO is obtained by the following equation (1).

MO = (a + b + i + j)-(c + d + g + h) (1)

Next, referring to FIG. 12, the principle of detection of the focus error signal, the tracking error signal and the pre-pit reproduction signal in the memory device 1 according to the present embodiment will be described. First, the principle of detecting the focus error signal will be described. In the in-focus state, the diameter of the light incident on the photodetectors 62a to 62d and the diameter of the light incident on the photodetectors 62g to 62j are set to be equal. Optical disc 1 than in focus
When 0 is close to the solid immersion lens 37,
As shown in FIG. 12A, the photo detector 62a
The diameter of the light incident on ˜62d becomes small, and the diameter of the light incident on the photodetectors 62g˜62j becomes large. On the contrary, when the optical disc 10 is farther from the solid immersion lens 37 than in the focused state, the diameter of the light incident on the photodetectors 62a to 62d becomes large as shown in FIG. 12B, and the photodetectors 62g to 62j.
The diameter of the light incident on is small. Therefore, from the size relation between the diameter of the light incident on the photodetectors 62a to 62d and the diameter of the light incident on the photodetectors 62g to 62j,
The focus error signal can be detected. Therefore, the focus error signal FE is obtained by the following equation (2).

FE = (a + d + h + i)-(b + c + g + j) (2)

The tracking error signal is obtained by the following equation (3) using the push-pull method.

TE = ef (3)

The pre-pit reproduction signal RF is the optical disc 1
It is a signal corresponding to the total amount of return light from 0, and is calculated by the following equation (4).

RF = e + f or = a + b + c + d + e + f + g + h + i + j (4)

The pre-pit reproduction signal RF is, for example, a ROM (read only) area where the optical disk 10 is capable of recording and reproducing information by a magneto-optical system and a ROM (pre-pit information) in which information is recorded by pre-pits. In the case of a so-called hybrid disc in which a memory) region (reproduction-only region) is mixed, or the optical disc 10 is
In the case of a so-called sample servo type magneto-optical disk in which servo information or the like is recorded by prepits at predetermined intervals, it is detected as a reproduction signal of information recorded by prepits.

FIG. 13 shows a memory device 1 according to this embodiment.
FIG. 3 is a block diagram showing a configuration of an internal circuit. As shown in this figure, the storage element 1 includes a spindle driver 71 that drives the spindle motor 20, and an optical pickup device 3.
Laser driver 72 for driving the semiconductor laser 61 in 0
And a servo driver 73 for driving an actuator 43 for focus and tracking servo and an arm drive motor 44 for seek in the optical pickup device 30,
And a magnetic head driver 74 for driving the magnetic head 34. The spindle driver 71 and the servo driver 73 are connected to predetermined connection pins 56a and 56b, respectively.

The storage element 1 further receives the output signals of the photodetectors 62a to 62j in the optical pickup device 30 and calculates the signals MO, FE, TE, and A signal detection unit 75 is provided for detecting RF and detecting a light amount signal APC used for automatically adjusting the output of the semiconductor laser 61. In addition,
As the light amount signal APC, for example, a signal corresponding to the total light amount of the return light may be used. Although not shown, a photodetector for receiving a part of the front emission light of the semiconductor laser 61 or the rear emission light is provided, and this photodetector is provided. You may use the output of.

The storage element 1 further includes a magneto-optical reproduction signal MO and a pre-pit reproduction signal R output from the signal detector 75.
A selector / clamp unit 76 for inputting F, selecting one of them, and for clamping and outputting, and an output signal of the selector / clamp unit 76 from an analog-digital (hereinafter referred to as A
/ D. ) A / D converter 77 for converting and outputting,
The output signal of the A / D converter 77 is demodulated and the storage element 1
And a read / write controller 78 that modulates recording data that is output to the outside of the storage element 1 or that is input from the outside of the storage element 1 and controls the laser driver 72 and the magnetic head driver 74 based on the modulated data. I have it. The read / write controller 78 is connected to a plurality of predetermined connection pins 56c.

The storage element 1 further receives a focus error signal FE, a tracking error signal TE and a light amount signal APC output from the signal detecting section 75 and selectively outputs them, and a multiplexer 79 of this multiplexer 79. An A / D converter 80 for A / D converting and outputting the output is provided. The output end of the A / D converter 80 is
It is connected to a predetermined connection pin 56d. Storage element 1
Is a digital-analog (hereinafter, referred to as light amount control data inputted from the outside through a predetermined connection pin 56e).
It is written as D / A. ) A D / A converter 81 that converts the data and sends it to the laser driver 72 and, for example, predetermined four connection pins 56.
A mode setting unit 82 which is connected to f, sets the mode of the storage element 1 according to the state of these connection pins 56f, and sends information on the set mode to the read / write control unit 78. The power supply voltage _Vcc or the ground voltage GND is selectively applied to the four connection pins 56f connected to the mode setting unit 82, and the mode setting unit 82 changes the connection pin 56f according to the state of each connection pin 56f. Accidental erasure prevention mode (R
A mode such as an OM mode), a write-once (additional write) mode, or an erasable mode is selected. The storage element 1 further includes connection pins 56g, 5 for supplying the power supply voltage _Vcc and the ground voltage GND to the circuits in the storage element 1.
It has 6h.

A host controller or a CPU (central processing unit) (hereinafter, referred to as a host controller) 90 for controlling the storage element 1 is connected to the connection pins 56a to 56e of the storage element 1. Has become.

Most of the circuits shown in FIG. 13 are, for example,
It is realized in the form of a bare chip IC (integrated circuit), and this bare chip IC is flip-chip mounted on the circuit board 55. Further, in the storage element 1, as the necessary clock, the system clock is supplied from the host controller 90 and used.

Next, the operation of the memory device 1 according to this embodiment will be described. First, the operation during servo will be described. During the servo, the spindle driver 71 is controlled based on the command from the host controller 90,
Spindle mode 20 by the spindle driver 71
Is driven, and the optical disc 10 is rotationally driven at a constant angular velocity (CAV) or a constant linear velocity (CLV). When the optical disc 10 rotates, the magnetic head 34 and the lens holder 36, which are flying heads, float so as to face the optical disc 10 with a predetermined air gap therebetween. Solid immersion lens 37 and optical disc 1
If the air gap between 0 and 0 is too large, it will hinder the improvement of the numerical aperture. For example, when a semiconductor laser 61 provided in the laser coupler 40 that emits red laser light having a wavelength of 680 nm is used, the air gap between the solid immersion lens 37 and the optical disc 10 is equal to the laser wavelength. 0.34 μm or less, which is 1/2 or less,
For example, the distance is adjusted to be 0.15 μm.

During servo operation, the host controller 90 controls the read / write controller 78, and the read / write controller 78 controls the laser driver 7.
2 is controlled, the semiconductor laser 61 is driven by the laser driver 72, and a low-output laser beam for reproduction is emitted from the semiconductor laser 61. The laser light passes through the polarization hologram 41 and the split optical rotation plate 42, is reflected by the reflection prism 38, is condensed by the solid immersion lens 37, and is collected by the magneto-optical recording layer 12 of the optical disc 10.
It is irradiated in spots on the top.

When the optical disk 10 is a sample servo type magneto-optical disk, the magneto-optical recording layer 12 is provided with servo areas in which servo information and address information are prerecorded by prepits at predetermined intervals.
The light applied to the optical disc 10 is modulated by the prepits in this servo area and returns to the solid immersion lens 37 side. The return light is condensed by the solid immersion lens 37, reflected by the reflection prism 38, passes through the two-divided optical rotation plate 42, and then enters the polarization hologram 41. Here, the P-polarized component is not diffracted and the photodetector 62 on the laser coupler 40 is
e, 62f, and the S-polarized component is diffracted and enters the photodetectors 62a to 62d and the photodetectors 62g to 62j on the laser coupler 40. Then, based on the output signals of these photo detectors 62a to 62j, the signal detection unit 75 causes the focus error signal F to be detected.
E, a tracking error signal TE and a prepit reproduction signal RF are generated.

The focus error signal FE and the tracking error signal TE are sent to the host controller 90 via the multiplexer 79 and the A / D converter 80.
The pre-pit reproduction signal RF is supplied to the selector / clamp unit 7
6, read / write control unit 78 via A / D converter 77
Is input to, and the address is discriminated. Information on the determined address is sent to the host controller 90. The host controller 90 controls the servo driver 73 based on each information sent from the storage element 1 to perform focus servo and tracking servo, and
Seek to the desired track. After that, the recording or reproducing operation described below is performed.

Next, the recording operation will be described. During recording, the host controller 90 controls the read / write control unit 78 to perform a recording operation, and the host controller 90 sends recording data to the read / write control unit 78 to read / write control unit 78. Modulates this data and controls the laser driver 72 and the magnetic head driver 74 based on the modulated data. As a result, the semiconductor laser 61 emits a high-power laser beam for recording, and the magnetic head 34 generates a modulation magnetic field that is modulated according to the recording data. Laser light is
It passes through the polarization holograms 41 and 2 split optical rotation plate 42, is reflected by the reflection prism 38, is condensed by the solid immersion lens 37, and is irradiated onto the magneto-optical recording layer 12 of the optical disc 10 in a spot shape. In the magneto-optical recording layer 12 of the optical disc 10, the portion irradiated with the laser beam is heated to the Curie temperature or higher to weaken the coercive force, and the modulation magnetic field is applied to the portion to record the recording data. At this time, since the old record data is erased, overwriting is performed.

Next, the operation at the time of reproduction will be described. At the time of reproduction, the host controller 90 controls the read / write control unit 78 to perform a reproduction operation. During reproduction, the semiconductor laser 61 emits a low-output laser beam for reproduction. This laser light is generated by the polarization hologram 4
The light passes through the one-and-two-divided optical rotation plate 42, is reflected by the reflection prism 38, is condensed by the solid immersion lens 37, and is irradiated onto the magneto-optical recording layer 12 of the optical disc 10 in a spot shape. This light is reflected by the magneto-optical recording layer 12, and at that time, the polarization direction is rotated by + θ _k or −θ _k according to the magnetization direction in the magneto-optical recording layer 12 and returns to the solid immersion lens 37 side. This return light is condensed by the solid immersion lens 37, reflected by the reflection prism 38, passes through the two-divided optical rotation plate 42, enters the polarization hologram 41, and the S-polarized component is diffracted to be on the laser coupler 40. Photo detector 6
2a-62d and photodetectors 62g-62j. Then, these photo detectors 62a to 62
The magneto-optical reproduction signal MO is generated by the signal detection unit 75 based on the output signals of d and 62g to 62j. The magneto-optical reproduction signal MO is input to the read / write control unit 78 via the selector / clamp unit 76 and the A / D converter 77,
Here, it is demodulated and sent to the host controller 90.

In the case of the sample servo system, the focus error signal FE and the tracking error signal T obtained at the time of passing through the servo area at the time of recording and reproducing.
Focus servo and tracking servo are performed based on E.

As described above, according to the storage element 1 of the present embodiment, by using the optical disk 10 having a diameter of about 0.7 inch, the solid immersion lens 37, etc., the storage capacity of about 20 Gbit / inch ² can be obtained. By using the optical pickup device 30 capable of ultra-high density recording, the thickness is about 5 mm and the size is about 1 inch × 1 inch, and the size of the IC is about the same as that of the IC.
A large storage capacity of about 100 to 500 Mbytes can be realized.

Further, the memory element 1 according to this embodiment is
The optical disk 10, the spindle mode 20, the optical pickup device 30, the circuit shown in FIG. 13 and the like are sealed by a package 50 made of ceramic or the like, and the connection pins 56 similar to those of the IC are provided. Other circuits,
No special connector or attachment jig is needed to connect to devices, etc., and soldering is possible, and it can be handled in the same way as electronic parts. For example, glass is used for the optical disk 10 and optical parts. This makes it possible to pass reflow solder in the process of the manufacturing line. In addition, the size of the package 50, the number and arrangement of the connection pins 56, etc.
By conforming to the standard of, it becomes possible to handle the memory element 1 exactly like an IC.

Due to such characteristics, the storage element 1 according to the present embodiment can be said to be very useful as a memory in a small portable terminal such as a PDA.

Further, in the memory element 1 according to the present embodiment, the solid immersion lens 37 is set so as to have the optical characteristics in consideration of the thickness of the substrate 11, so that the numerical aperture is not affected by the substrate 11. It is possible to improve, high density recording is possible, and
The beam quality can be improved, and the wavefront aberration can be easily managed.

Further, in the storage element 1 according to the present embodiment, the removable of the optical disc 10 is eliminated, and the unevenness of the thickness of the substrate 11 of the optical disc 10 is suppressed to 1 μm or less by using glass or the like, so that focus servo and tracking can be performed. Servo is excellent in mechanical characteristics as it has almost no dynamic range. Therefore, focus servo and tracking servo, such as driving the laser coupler 40 in two directions, can be realized in a simple form.

Further, in the memory element 1 according to the present embodiment, the solid immersion lens 37 having the lower surface formed in the flat surface and the upper surface formed in the aspherical curved surface is used as the solid immersion lens 37. The number of points can be reduced and the thickness of the memory element 1 can be reduced.

Further, in the memory element 1 according to the present embodiment, by using the solid immersion lens 37 to reduce the spot diameter of light, the energy density of the light spot can be made extremely high even with a low power laser. Becomes Therefore, the storage element 1 according to the present embodiment can be operated with low power consumption, and a low threshold laser can be used for recording.

Further, in the storage element 1 according to the present embodiment, since the optical disc 10 is small, the inertial force is small, so that the rotation can be started immediately when necessary and the rotation can be stopped immediately when it is unnecessary, so that the consumption is reduced. It is possible to reduce power consumption and access time. In addition,
In the storage element 1 according to the present embodiment, since the diameter of the optical disc 10 is small, the number of rotations required to obtain a desired linear velocity is larger than that of a large-diameter optical disc. In some cases, the number of rotations of the optical disk 10 cannot be increased so much depending on the performance or the like. In such a case, the transfer rate is limited, but if a higher transfer rate is desired, a plurality of storage elements 1 can be used in parallel.

Further, the memory element 1 according to the present embodiment is
It is also possible to mount multiple IC cards, and in this case, RAID (redundant arra
It is also possible to realize y of inexpensive disks).

Further, the memory element 1 according to the present embodiment is
The circuit configuration is simple, such as having no controller inside and not requiring a power supply circuit. Further, the storage element 1 does not have the removable property of the optical disc 10, and
The mechanical structure is simple, such as no loading mechanism is required. Therefore, the storage element 1 has high recording / reproduction tolerance and mechanical accuracy, and also has a high impact resistance due to the light weight of the components such as the optical disk 10. Further, the memory element 1 can be manufactured at low cost because of its simple structure.

If the storage element 1 generates a large amount of heat, a heat sink may be attached to the package 50.

FIG. 14 is a sectional view of a memory element according to the second embodiment of the present invention. The storage element 100 according to the present embodiment is configured to perform seek, focus servo, and tracking servo by moving the optical disc 10. In this storage element 100, the package 5
A sealed container 1 for sealing an optical disk 10 and the like in
01 is provided. The hermetically-sealed container 101 includes a box-shaped container portion 102 having an open top surface, and the container portion 102.
Has a lid portion 103 that closes the upper surface portion thereof. An ultrasonic linear motor 104 is provided at the center of the bottom of the container 102 in the sealed container 101. This ultrasonic linear motor 104 has a stator 105 fixed to the bottom of the container 102, and a slider (rotor) 106 that moves the stator 105 in the left-right direction in FIG. An actuator 107 using a piezoelectric element that can expand and contract in the vertical direction is mounted on the slider 106, and a spindle motor 20 that rotationally drives the optical disk 10 is fixed on the actuator 107.

At the bottom of the container 102, the optical disk 10
A magnetic head 108 for applying a magnetic field in the magnetic field modulation method is arranged at a position facing the magneto-optical recording layer 12. A circular opening 109 is formed in the lid 103 at a position facing the magnetic head 108.
09 is closed by the solid immersion lens 110. The optical system storage container 11 is provided on the upper surface of the lid 103.
1 is fixed, and in the optical system container 111, a laser coupler 40 and a polarization hologram 41 arranged in order from the laser coupler 40 side on the optical path of light emitted from the semiconductor laser 61 in the laser coupler 40, A two-part optical rotation plate 42, a convex lens 112, and a reflection prism 38 are provided. In the present embodiment, the solid immersion lens 110 has a lower surface formed into a flat surface and an upper surface formed into a spherical surface.
The convex lens 112 and the convex lens 112 function as the solid immersion lens 37 in the first embodiment. Light emitted from the semiconductor lens 61 in the laser coupler 40 is generated by the polarization hologram 41 and the two-divided optical rotation plate 42.
Through the convex lens 112, is reflected by the reflection prism 38, and is further passed through the solid immersion lens 1
The light is condensed by 10 and is irradiated onto the magneto-optical recording layer 12 in a spot shape through the substrate 11 of the optical disk 10. Here, the solid immersion lens 110 is
Similar to the first embodiment, the optical characteristics are set in consideration of the thickness of the substrate 11. That is, the solid immersion lens 110 is set so as to obtain desired optical characteristics as a lens only when combined with the substrate 11. In addition, solid immersion lens 1
The refractive index of 10 is equal to the refractive index of the substrate 11, and is 1.57, for example.

The sealed container 101 is filled with a fluid 113 having a refractive index higher than that of air. This fluid 113
The refractive index of is preferably close to that of the substrate 11 of the optical disc 10 and the solid immersion lens 110. By interposing such a fluid 113 between the solid immersion lens 110 and the substrate 11, reflection at each boundary surface when air is present between the solid immersion lens 110 and the substrate 11 is reduced.
In addition to this, in the storage element 100 according to the present embodiment, by driving the optical disk 10 without moving the optical system to perform seek or the like, it is possible to prevent a decrease in margin due to tilting of the optical axis or the like. It is possible to improve the optical performance. Further, as the fluid 113, a fluid that has good lubricity with respect to the optical disk 10 and that has a function of extending the life of the optical disk 10 or cooling it is used. Alternative substances and oils are used.

Here, an example of a method of sealing the sealed container 101 will be briefly described. In this method, first, the ultrasonic linear motor 10 is placed in the container portion 102 of the sealed container 101.
4, components such as the spindle motor 20 and the optical disk 10 are attached, and then the upper surface of the container 102 is covered with the lid 103.
Then, the sealed container 101 is filled with the fluid 113 through the opening 109. Next, a groove formed in an annular shape around the opening 109 in the lid 103 is filled with an ultraviolet curable resin, a solid immersion lens 110 is arranged on the opening 109, and pressure is applied from above to solid immersion. The ultraviolet curable resin is flattened by the peripheral edge of the lens 110, and in this state, the ultraviolet curable resin is irradiated with ultraviolet rays to cure the ultraviolet curable resin, and the peripheral edge of the solid immersion lens 110 is fixed to the lid 103. The solid immersion lens 110 closes the opening 109.

The storage element 100 according to the present embodiment.
However, the actuator 43 for focus and tracking servo and the arm drive motor 44 for seek are not provided. In the circuit configuration in the storage element 100 according to the present embodiment, the servo driver 73 in FIG. 13 has the ultrasonic linear motor 104 and the actuator 107 instead of the actuator 43 and the arm driving motor 44.
The magnetic head driver 74 is changed to drive the magnetic head 108 instead of the magnetic head 34.

In the memory element 100 according to this embodiment,
Spindle motor 1 by ultrasonic linear motor 104
5 and the optical disc 10 are moved in the horizontal direction to perform seek and tracking servo, and the actuator 107 is used to move the spindle motor 15 and the optical disc 10 in the vertical direction.
Focus servo is performed.

According to the storage element 100 of the present embodiment, the optical disk 10 is hermetically sealed with the fluid 113 having a refractive index larger than that of the air filled therein, so that the optical performance can be improved. The life of the optical disc 10 can be extended and the optical disc 10 can be cooled.

In this embodiment, the seek and tracking servo are performed by the ultrasonic linear motor 104, but only the seek is performed by the ultrasonic linear motor 104, and the tracking servo is the same as in the first embodiment. Alternatively, the actuator 43 may be used. Also, the focus servo may be performed by using the actuator 43 as in the first embodiment without using the actuator 107.

Further, the means for moving the spindle motor 20 and the optical disk 10 in the horizontal direction is not limited to the one using the ultrasonic linear motor 104, but the optical pickup device 30 in the first embodiment is used as the arm driving motor 44. The spindle motor 20 and the optical disk 10 may be attached to the tip of the arm and the arm may be rotated in the same manner as when the arm is rotated by.

Other configurations, operations and effects in this embodiment are the same as those in the first embodiment.

FIG. 15 is a sectional view of a memory element according to the third embodiment of the present invention. The storage element 120 according to the present embodiment is similar to the second embodiment in that the optical disk 10
Etc. are sealed by a hermetically sealed container, but seek, focus servo and tracking servo are performed on the side of the optical pickup device as in the first embodiment. In this storage element 120, in the package 51,
A sealed container 121 for sealing the optical disk 10 and the like is provided. The hermetically sealed container 121 has a box-shaped container part 122 having an open top surface and a lid part 123 for closing the top surface part of the container part 122. A spindle 20 for rotating the optical disc 10 is fixed to the center of the bottom of the container 122 in the sealed container 121.

At the bottom of the container 122, the optical disk 10
A magnetic head 124 for applying a magnetic field in the optical modulation system is arranged at a position facing the magneto-optical recording layer 12.
An opening 125 is formed in the lid 123 above the magnetic head 124 from a position near the center of the optical disc 10 to a position outside the outer periphery of the optical disc 10.

On the other hand, in the package 50, as in the first embodiment, an optical head arm 35 having a base side fixed to the rotating body 32 (see FIG. 1) is provided. In this optical head arm 35, a laser coupler 40, a polarization hologram 41, a split optical rotation plate 42, a convex lens 112, a reflection prism 38, and a solid immersion lens 110 are provided in the same arrangement as in the second embodiment. ing. The solid immersion lens 110 is
It is arranged inside the opening 125. The peripheral portion of the solid immersion lens 110 has a bellows-shaped holding member 12
6 is connected to the peripheral portion of the opening 125. As a result, the solid immersion lens 110 and the holding member 126 close the opening 125, and the solid immersion lens 110 can move in the radial direction of the optical disc 10 in the opening 125. The sealed container 121 is filled with a fluid 113 having a refractive index higher than that of air.

The storage element 120 according to the present embodiment.
Then, similarly to the first embodiment, an actuator 43 for focus and tracking servo and an arm drive motor 44 for seek are provided. In the circuit configuration in the storage element 120 according to this embodiment, the magnetic head driver 74 in FIG. 13 is modified to drive the magnetic head 124 instead of the magnetic head 34. Further, in the present embodiment, since the optical modulation method is used for recording information, the intensity of the emitted light from the semiconductor laser 61 is modulated based on the recording data during recording.

Other configurations, operations and effects in this embodiment are the same as those in the first or second embodiment.

FIG. 16 is an explanatory diagram showing a schematic structure of an optical pickup device in a memory element according to the fourth embodiment of the present invention. In this optical pickup device 200, a polarization hologram 203, a two-divided optical rotation plate 204, a reflection prism 209, an objective lens 205, and a solid immersion lens 206 are provided between the optical disc 10 and the laser coupler 202 with their optical axes aligned. ing. Further, the optical pickup device 200 includes a magnetic head 34 that applies a modulation magnetic field that is modulated according to the recording data to a portion of the optical disc 10 where the laser light is irradiated during the recording of the data.

The polarization hologram 203 is divided into two and has a right region 203R and a left region 203L.
The right region 203R and the left region 203L are the laser coupler 20.
The P-polarized light emitted from 2 is not diffracted, but only the S-polarized light is diffracted in different directions.

The two-divided rotatory plate 204 includes a right rotatory plate 204R which rotatively rotates incident light by a predetermined angle in the right rotation direction, for example, 22.5 ° and emits it, and incident light by a predetermined angle in the left rotation direction. , A left optical rotatory plate 204L that rotates and emits light by 22.5 °, for example. The dividing line between the right optical rotation plate 204R and the left optical rotation plate 204L is arranged so as to be parallel to the direction corresponding to the radial direction of the optical disc 10.
The direction of the dividing line between the right region 203R and the left region 203L in the polarization hologram 203 is the right optical rotation plate 204R.
And the direction of the dividing line between the left optical rotation plate 204L and the right region 203R and the left region 203 in the polarization hologram 203.
The positions of L are the right rotatory plate 204R and the left rotatory plate 20 respectively.
It corresponds to the 4L position.

The solid immersion lens 206 has a flying head structure, and its thickness is determined in consideration of the thickness of the substrate 11 of the optical disk 10. That is, the solid immersion lens 206 is
It is set so that the desired optical characteristics as a lens can be obtained only when combined with the substrate 11. The refractive index of the solid immersion lens 206 is equal to the refractive index of the substrate 11, and is 1.57, for example.

In this embodiment, the objective lens 2 is used as means for performing focus servo and tracking servo.
There is provided an actuator 208 capable of moving 05 in the radial direction (the direction perpendicular to the paper surface in FIG. 16) of the optical disc 10 and in the vertical direction. This actuator 2
A piezoelectric element, a voice coil motor, or the like is used as 08. The actuator 208 is the laser coupler 202.
It is driven based on the focus error signal and the tracking error signal detected based on the output of the photodetector provided in.

As shown in FIG. 20, the laser coupler 202 comprises a semiconductor laser 61 and a plurality of photodetectors 210A to 210J formed on a single semiconductor substrate. The semiconductor laser 61 emits P-polarized light, for example. The semiconductor laser 61 emits laser light parallel to the surface of the semiconductor substrate. The semiconductor laser 61 emits laser light at a position facing the laser light emitting portion of the semiconductor laser 61. A reflection mirror portion 63 that reflects upward is formed.

The photo detectors 210I and 210J are
Each of them is formed in a rectangular shape and arranged side by side in the vicinity of the laser beam emission position on the semiconductor substrate. The dividing line of the photo detectors 210I and 210J is the optical disc 10
Are arranged so as to be parallel to the direction corresponding to the track direction. Photodetectors 210A to 210
D is a photodetector 210I and a semiconductor laser 6
1 is arranged in a square shape at a lateral position in the direction corresponding to the radial direction of the optical disc 10. The photodetectors 210E to 210H are arranged in a square shape at positions lateral to the photodetector 210J and the semiconductor laser 61 in the direction corresponding to the radial direction of the optical disc 10.

The optical system shown in FIG. 16 is provided in the optical head arm 35 in FIG. 1 as in the first embodiment. The magnetic head 34 is attached to the magnetic head arm 33 in FIG. Other configurations in the present embodiment are similar to those in the first embodiment.

Next, the operation of the optical pickup device 200 in this embodiment will be described. At the time of recording or reproducing data, the spindle motor 20 rotationally drives the optical disk 10 at a constant angular velocity (CAV) or a constant linear velocity (CLV), and at the same time, the laser coupler 20.
The semiconductor laser 61 provided in No. 2 is driven to emit laser light. The flying head is the optical disc 10
The air gap between the solid immersion lens 206 and the optical disk 10 is too large, which hinders the improvement of the numerical aperture. Must be: For example, when the semiconductor laser 61 provided in the laser coupler 202 is one that emits red laser light having a wavelength of 680 nm, the air gap between the solid immersion lens 206 and the optical disc 10 is equal to the laser wavelength. 0.34 μm, which is less than 1/2
Hereinafter, for example, the distance is adjusted to be 0.15 μm.

The P-polarized laser light emitted from the semiconductor laser 61 is reflected by the reflection mirror section 63, passes through the polarization hologram 203 as it is, and is divided into two rotatory plates 20.
4 is incident. Here, the light that has passed through the right rotatory plate 204R is rotated by 22.5 ° in the right rotation direction, and the left rotatory plate 20R
The light passing through 4L is rotated by 22.5 ° in the counterclockwise rotation direction and emitted. The light that has passed through the two-divided optical rotation plate 209 is reflected by the reflection prism 209, condensed by the objective lens 205, and incident on the solid immersion lens 206. Is focused on.

The optical characteristics of the solid immersion lens 206 are adjusted so that the optical characteristics of the solid immersion lens 206 and the optical characteristics of the substrate 11 of the optical disk 10 are added to form desired optical characteristics. Therefore, the numerical aperture can be improved without being adversely affected by the substrate 11 of the optical disc 10, and the diameter of the laser spot can be reduced. About this later,
explain in detail.

On the other hand, when the optical disk 10 is irradiated with the laser beam, a return light is generated. However, when the magneto-optical recording data is recorded on the magneto-optical recording layer 12, the reflected light on the magneto-optical recording layer 12 is reflected. Has its polarization direction rotated by + θ _k or −θ _k depending on the magnetization direction in the magneto-optical recording layer 12.

This return light is condensed by the solid immersion lens 206 and the objective lens 205, reflected by the reflection prism 209, and then divided into two rotatory plates 204.
Incident on. Here, the light passing through the right rotatory plate 204R on the outward path passes through the left rotatory plate 204L on the return path, and the light passing through the left optical rotatory plate 204L on the outward path returns to the right rotatory plate 204R.
Pass through. As a result, the left optical rotation plate 204L on the return path
The light passing through is further rotated by 22.5 ° in the right rotation direction, and is rotated by + 45 ° in total in the two-divided optical rotation plate 204. On the other hand, on the return path, the right optical rotation plate 20
The light passing through 4R is further rotated by 22.5 ° in the counterclockwise rotation direction, and is rotated by a total of −45 ° in the two-part split optical rotation plate 204. In this way, the light that has passed through the two-divided optical rotation plate 204 on the return path has the S-polarized component. The light that has passed through the two-divided optical rotation plate 204 on the return path enters the polarization hologram 203, and the P-polarized component is emitted without being diffracted. On the other hand, the S-polarized component is diffracted by the polarization hologram 203. Here, the polarization hologram 203 includes a right region 203R and a left region 203L.
The S-polarized light component incident on the right region 203R is diffracted in a direction corresponding to the outer side in the radial direction of the optical disc 10, and the S-polarized component incident on the left region 203L is directed to the inner side in the radial direction of the optical disc 10. It is diffracted in the corresponding direction.

Therefore, the return light from the optical disk 10 is
At the stage of passing through the polarization hologram 203, it is separated into a return light that does not include the magneto-optical reproduction signal component and a return light that includes the magneto-optical reproduction signal component. The return light that has passed through the right optical rotation plate 204R of the two-part optical rotation plate 204 and the return light that has passed through the left optical rotation plate 204L are separated.

The return light that does not include the magneto-optical reproduction signal component (return light of the P-polarized component) that has passed through the polarization hologram 203 without being diffracted is emitted as a circular beam spot, of which approximately half (half) The circular portion) is incident on the photodetectors 210I and 210J as shown in FIG. The return light that has passed through the right region 203R of the polarization hologram 203 and is diffracted in the direction corresponding to the radial outside of the optical disk 10 (the return light of the S-polarized component that has passed through the right optical rotation plate 204R) is a semi-circular beam spot. Then, the light enters the photodetectors 210A to 210D in the laser coupler 202. The return light that has passed through the left region 203L of the polarization hologram 203 and is diffracted in the direction corresponding to the radial inside of the optical disc 10 (the return light of the S-polarized component that has passed through the right rotatory plate 204L) is a semi-circular beam spot. And photodetectors 210E to 210H in the laser coupler 202.
Incident on.

As shown in FIG. 20 (a), the photo detectors 210A to 210D are arranged in the shape of a square, and when focusing, the right area 2 of the polarization hologram 203 is detected.
The semicircular return light from 03R is reflected by the photodetectors 210B and 210C arranged on the lower side in FIG.
It receives light evenly. Further, the photo detectors 210E to 210H are arranged in the shape of a square, and when focusing, the left region 2 of the polarization hologram 203 is detected.
The semicircular return light from 03L is reflected by the photodetectors 210E and 210H arranged on the upper side in FIG.
It receives light evenly. The photodetectors 210I and 210J are configured to evenly receive the upper half return light in FIG. 20A of the circular return light from the polarization hologram 203 during focusing. Each of the photo detectors 210A to 210J outputs a signal according to the amount of light received. And
The signal detection unit 75 in FIG. 13 detects each signal as follows based on the output signal of each photodetector 210A to 210J.

Assuming that the output signals of the photo detectors 210A to 210J are A to J, the focus error signal FE is obtained by the following equation (5).

FE = (A + D + F + G)-(B + C + E + H) (5)

This is because the light amount detection signals of the upper half of the group of photodetectors 210A to 210D on the right side in FIG. 20A and the lower half of the group of photodetectors 210E to 210H on the left side in FIG. From the addition signal obtained by adding the light amount detection signal, the light amount detection signal of the lower half of the group of photodetectors 210A to 210D and the group of photodetectors 210E to 210H.
It represents that the addition signal obtained by the addition processing of the light amount detection signal of the upper half of the above is subjected to the subtraction processing.

As shown in FIG. 20A, at the time of focusing, the semicircular return light from the right region 203R of the polarization hologram 203 is incident on the photodetectors 210B and 210C, and from the left region 203L of the polarization hologram 203. The semicircular return light of is incident on the photodetectors 210E and 210H.

However, when the focus is deviated to the side opposite to the disc (when the optical disc 10 is farther from the solid immersion lens 206 than in the focused state), FIG.
As shown in (b), the return light from the right region 203R and the return light from the left region 203L of the polarization hologram 203 are once converged and then become diffused lights, which are photodetectors 210A and 210D, respectively. , And enters the photodetectors 210F and 210G.

On the other hand, when the focus is shifted to the disc side (when the optical disc 10 is closer to the solid immersion lens 206 than in the focused state), FIG.
As shown in FIG.
The semicircular return light from R is the photodetector 210B,
210 C, and the left area 20 of the polarization hologram 203.
The semicircular return light from 3L is the photodetector 210.
E, 210H is incident, but in both cases, the diameter becomes larger than that at the time of focusing.

Therefore, when the calculation as shown in the equation (5) is performed, the calculation result has a negative value at the time of focusing, and the calculation result has a positive value when the focus is deviated to the side opposite to the disc side. When is shifted to the disc side, the calculation result becomes a negative value having a larger absolute value than that at the time of focusing. Therefore, the servo control system uses the calculation result of the equation (5) at the time of focusing as a threshold value, and when the level of the calculation result is lower than this threshold value, determines that the focus time is shifted to the disc side. A focus control signal for correcting the above can be supplied to the actuator 208 shown in FIG. As a result, the objective lens 205 can be controlled to move to the laser coupler 202 side and can be brought into a focused state. Further, the servo control system is expressed by the formula (5)
When the level of the calculation result of is higher than the threshold value, it is determined that the focus is deviated to the disc side, and a focus control signal for correcting this is supplied to the actuator 208. As a result, the objective lens 205 is moved to the optical disc 1
The movement can be controlled to the 0 side, and the in-focus state can be achieved.

Next, when the focus state is controlled to the in-focus state in this way, the flying head moves to the optical disc 1
The movement is controlled (seeked) to the designated address on 0. Then, the tracking error signal TE is obtained by the push-pull method by the following equation (6).

TE = (A + B + E + F) − (C + D + G + H) (6)

This is because the light amount detection signals of the right half of the group of photodetectors 210A to 210D on the right side in FIG. 20A and the right half of the group of photodetectors 210E to 210H on the left side in FIG. From the addition signals obtained by adding the light amount detection signals, the left half light amount detection signals of the group of photodetectors 210A to 210D and the group of photodetectors 210E to 210H are detected.
It is shown that the addition signal obtained by adding the left half light amount detection signal of the above is subtracted. Since the right and left halves of the photo detectors 210A to 210D and 210E to 210H are divided by the dividing line in the direction corresponding to the track direction on the optical disc 10, the formula (6) is used.
The difference between the light amount of the laser light emitted from the center of the recording track to the outer circumference of the disc and the light amount of the laser light emitted to the inner circumference of the disc from the center of the recording track is detected by performing the calculation shown in The tracking error signal TE can be detected by the so-called push-pull method.

When the tracking error signal TE is obtained by the equation (6), the servo control system supplies a tracking control signal for correcting this to the actuator 208 shown in FIG. As a result, the objective lens 205
Can be controlled to move the beam spot to the outer peripheral side or the inner peripheral side of the disc, and the tracking state can be set to the just track.

Next, when the designated address on the optical disc 10 is irradiated with the laser beam, the semiconductor laser 61 is driven to emit the laser beam having the recording intensity and the optical disc 10 is driven. A modulating magnetic field modulated according to the recording data is applied from the magnetic head 34 to the portion irradiated with the laser beam above. The portion irradiated with the laser light is heated to the Curie temperature, and the coercive force is weakened by this, so that by applying the modulation magnetic field here, the portion irradiated with the laser light is magnetized according to the modulation magnetic field, The record data is recorded.

In this embodiment, the optical characteristics of the solid immersion lens 206 are set to the substrate 11 of the optical disk 10.
Since the beam spot diameter is adjusted to 0.25 μm, the conventional recording density (1.31 Gbit / inch ² )
Recording density of 6.2 times that of 8.06 Gbit / inch
A recording density of ² can be realized.

Next, at the time of reproducing the record data recorded as described above, the optical disk 10 is rotationally driven by the CAV or CLV by the spindle motor 20, and the semiconductor laser 61 provided in the laser coupler 202 is reproduced. The light emission is driven so as to emit a laser beam having an intensity for use. Then, the return light generated by irradiating the optical disk 10 with the laser light is the two-divided optical rotation plate 2.
04 and the polarization hologram 203, the photo detectors 210A to 21A provided on the laser coupler 202.
It is incident on 0J.

The signal detection section 75 in FIG. 13 detects the magneto-optical reproduction signal MO based on the arithmetic expression of the following expression (7).

MO = (A + B + C + D)-(E + F + G + H) (7)

This is the right rotatory plate 2 of the two-part rotatory plate 204.
04R represents that the light amount detection signal of the return light including the magneto-optical reproduction signal component that has passed through 04R is subtracted from the light amount detection signal of the return light that includes the magneto-optical reproduction signal component that has passed through the left optical rotation plate 204L. Modality). As a result, it is possible to detect only the pure magneto-optical reproduction signal component while removing the in-phase component.

Further, the pre-pit reproduction signal RF is detected based on the arithmetic expression of the following expression (8).

RF = (A + B + C + D) + (E + F + G + H) (8)

This is the photo detector 210A-21.
0D light amount detection signal and photodetectors 210E-2
It is shown that all the light intensity detection signals of 10H are added. The pre-pit reproduction signal RF is, for example, a so-called hybrid disc in which the optical disc 10 includes a RAM region in which information can be recorded and reproduced by a magneto-optical system and a ROM region (reproduction-only region) in which information is recorded by pre-pits. In the case, for example, when the optical disk 10 is a so-called sample servo type magneto-optical disk in which servo information and the like are recorded by pre-pits at predetermined intervals, it is detected as a reproduction signal of the information recorded by the pre-pits. .

Even during this reproduction, the focus error signal and the tracking error signal are detected, and the just focus (focus) and the reproduction on the just track are performed.

In the laser coupler 202, the photo detectors 210A to 210D and the photo detector 210 are
E-210H only provides all necessary signals F
E, TE, MO, and RF can be detected, and the photo detectors 210I and 210J can be omitted. However, the tracking error signal TE and the pre-pit reproduction signal RF are detected by using the light amount detection signals from the photo detectors 210I and 210J. By doing so, the effects described below can be obtained.

That is, the photo detectors 210A to 210A-2
When the tracking error signal is detected based on the respective light amount detection signals of the 10D and the photodetectors 210E to 210H, the tracking error signal is detected by the light amount detection signal on which the magneto-optical reproduction signal component is superposed. There is a disadvantage that the DC offset component is superimposed on the error signal. To prevent this, as shown in FIG. 20A, the photo detectors 210I and 210J divided by the dividing line in the recording track direction are used.
It is preferable to detect the tracking error signal TE by performing an arithmetic process as shown in the following formula (9) based on each light amount detection signal of.

TE = I-J (9)

As a result, the tracking error signal TE can be detected by the push-pull method. Further, according to the equation (9), since the tracking error signal TE is detected by the light amount difference of the return light from which the magneto-optical reproduction signal component is removed, the tracking error signal TE is removed in the form in which the DC offset component is removed. Can be detected.

When the pre-pit reproduction signal RF is detected by the arithmetic expression shown in the equation (8), the photo detector 210
A to 210D and photo detectors 210E to 210
The pre-pit reproduction signal RF is detected only based on the return light of the S-polarized component detected at H, and the pre-pit reproduction signal RF is detected with a light amount of about 1/2. Therefore, the detected pre-pit reproduction signal RF is detected. MTF (Modula
A slight dip occurs in the option transfer function).
To prevent this, as shown in equation (10) below,
It is advisable to add all the light amount detection signals of the photo detectors 210A to 210J and detect the pre-pit reproduction signal RF.

RF = A + B + C + D + E + F + G + H + I + J (10)

As a result, the return light of the S-polarized component and the return light of the P-polarized component separated by the polarization hologram 203 and the two-divided optical rotation plate 204 can be added together to detect the pre-pit reproduction signal RF. Good MT
The F pre-pit reproduction signal RF can be detected.

In this embodiment, each signal is detected by the same method as in the first embodiment, using the polarization hologram 41 and the laser coupler 40 similar to those in the first embodiment. Is also possible.

FIG. 17 shows a modification of the optical pickup device 200 shown in FIG. This modification is configured such that the laser light from the two-divided optical rotation plate 204 directly enters the objective lens 205 except for the reflection prism 209 in FIG. Note that the configuration shown in FIG. 16 can increase the degree of freedom in designing the optical path.

Here, in order to compare with the action and effect of the solid immersion lens in the present embodiment, FIG.
With reference to FIG. 8, problems of the technique using the conventional solid immersion lens will be described. In order to increase the recording density of the data recorded on the optical disc, it is necessary to reduce the diameter of the beam spot of the laser light with which the optical disc is irradiated. Here, when the wavelength of the laser light is λ and the numerical aperture of the objective lens is NA, the diameter d of the beam spot is expressed by the following equation (11).

D = K (λ / NA) (11) where K is a proportional constant (≈1).

As can be seen from this equation (11), the diameter of the beam spot is proportional to the wavelength of the laser light. Therefore, in order to reduce the diameter of the beam spot, a short wavelength semiconductor laser may be used. Currently 300n
There is a so-called blue laser capable of emitting a laser beam having a short wavelength of m. However, since this blue laser is very expensive, it is difficult to use not only in consumer equipment but also in professional equipment. Therefore, at present, there is no choice but to use a so-called red laser that emits a laser beam having a wavelength of 680 nm.

On the other hand, as can be seen from the equation (11), the diameter of the beam spot can be reduced by using an objective lens having a large numerical aperture. However, in order to increase the numerical aperture of the objective lens, it is necessary to use an objective lens having a large diameter. When the diameter of the objective lens is increased, the optical pickup device itself provided with the objective lens is inevitably increased in size and its own weight is increased, which impedes high-speed access. Therefore, there is a limit in providing an objective lens having a large numerical aperture.

For this reason, conventionally, there was a limit in reducing the beam spot diameter of the laser beam, and it was not possible to improve the recording density. Therefore, in recent years, an optical pickup device using a solid immersion lens has been proposed. As shown in FIG. 18A, an optical pickup device using this solid immersion lens integrally includes an objective lens 501 and a solid immersion lens 502 having a substantially hemispherical entrance surface and a planar exit surface. The recording head and the optical disk 503 are controlled to have a constant distance between the flying head and the optical disk 503, and data is recorded and reproduced.

In such an optical pickup device,
The solid immersion lens 502 includes an objective lens 5
The laser beam focused at 01 is incident through the hemispherical incident surface. Since the entrance surface of the solid immersion lens 502 is hemispherical, if the center of the exit surface of the solid immersion lens 502 is aligned with the focus position of the objective lens 501, the solid immersion lens 50
The incident angles of the laser beams incident on the laser beam 2 are all vertical, and the laser beams are solid immersion lens 502.
Focus on the center of the exit surface of. Thereby, when the refractive index of the solid immersion lens 502 is n, the numerical aperture of the objective lens 501 can be substantially n times.
It is possible to improve the recording density by reducing the diameter of the beam spot of the laser beam.

Further, the diameter of the beam spot can be reduced to 1 / n ² by using a solid immersion lens. As shown in FIG. 18 (b), it is a super spherical solid immersion lens 5 having a head larger than a hemisphere.
_No. 04, the laser beam is incident on the incident surface of the solid immersion lens 504 at an angle θ ₁ with respect to the normal direction of the optical disc 503, and when the incident angle with respect to the optical disc 503 is θ ₂ , sin θ ₂ = nsin θ ₁
Therefore, the beam spot diameter is λ / (2n ² sin
This is because θ ₁ ).

However, the recording layer of an actual optical disc must be at a certain distance from the bottom surface of the solid immersion lens. For example, as shown in FIG. 18C, an optical disk 505 having a magneto-optical recording layer 507 formed on one surface of a transparent substrate 506 having a thickness of about 1.2 mm.
In this case, since the magnetic head for applying the magnetic field is desired to be close to the recording layer 507, the recording layer 507 needs to be arranged not on the solid immersion lens side but on the magnetic head side. By doing so, the working distance (working distance;
Even if the objective lens 511 and the super spherical solid immersion lens 512 are used to increase the numerical aperture by setting the distance (the distance from the surface of the optical disk to the lens surface) to 0.32 μm or less, the solid immersion lens 5
Since the substrate 506 having a thickness of about 1.2 mm is interposed between the recording layer 12 and the recording layer 507, the incident angle θ ₂ ′ with respect to the actual recording layer 507 becomes small.

Therefore, in this embodiment, as shown in FIG. 19, the solid immersion lens 206 is mounted on the substrate 1.
The optical characteristics are set in consideration of the thickness of 1. That is, the solid immersion lens 206 is
It is set so that the desired optical characteristics as a lens can be obtained only when combined with the substrate 11. More specifically, if the refractive index of the solid immersion lens 206 is equal to the refractive index of the substrate 11, the shape of the solid immersion lens 206 according to the present embodiment is designed so as to be condensed at the center of the emission surface. From the shape of the solid immersion lens, the thickness of the substrate 11 is cut from the lower side. As a result, the numerical aperture can be improved and the diameter of the laser spot can be reduced without being adversely affected by the substrate 11 of the optical disc 10.

Specifically, the substantial numerical aperture of the optical pickup device 200 can be 1.0 or more, for example 1.36. Further, as shown in FIG. 19, the laser light from the objective lens 205 is emitted from the solid immersion lens 2
When the incident angle formed by being incident on 06 is θ ₁ , the laser wavelength is λ, the refractive index of the solid immersion lens 206 is n, and the refractive index of the substrate 11 is n, the diameter φ of the beam spot is φ = λ / (2n ² sin θ ₁ )
The diameter can be 0.25 μm. Incidentally, when the incident angle of the laser beam is refracted by the solid immersion lens 206 and the substrate 11 and theta _2, the relationship between theta ₁ and theta ₂ is a sinθ ₂ = nsinθ _1. This is the same effect as when using a so-called blue laser having a laser wavelength of 300 nm. Therefore, while using an inexpensive red laser, the same effect as when using a blue laser can be obtained, so that a high-performance and inexpensive optical pickup device can be provided. Further, the film thickness structure of the optical disk does not have to be changed depending on the wavelength of the laser. Further, since the substrate 11 is not adversely affected, it is possible to improve the beam quality and
It is possible to easily manage the wavefront aberration.

Other operations and effects in this embodiment are the same as those in the first embodiment.

FIG. 21 is an explanatory diagram showing a schematic structure of the optical pickup device in the memory device according to the fifth embodiment of the present invention. In this optical pickup device 300, an optical block 302 that collects and irradiates the optical disc 10 with laser light, a bare chip 303 provided on the optical block 302, and the bare chip 303.
An actuator 309 that is movable in the radial direction (the direction perpendicular to the paper surface in FIG. 21) and in the vertical direction of the optical disc 10, and a magnetic head 34 that applies a modulation magnetic field according to the recording data to a portion of the optical disc 10 where laser light is irradiated. Is equipped with. As the actuator 309, for example, a piezoelectric element is used. Actuator 30
9 is driven based on the focus error signal and the tracking error signal detected based on the output of the photodetector provided on the bare chip 303.

The optical block 302, the bare chip 303 and the actuator 309 are provided on an optical head arm 310 similar to the optical head arm 35 in FIG. The magnetic head 34 is attached to the magnetic head arm 33 in FIG. The optical head arm 310 and the magnetic head arm 33 are adapted to be rotated by the arm driving motor 44, as in the first embodiment. The tip of the optical head arm 310 and the magnetic head 34 have a flying head configuration.

The optical block 302 has a substantially hemispherical shape in appearance, and has an entrance hole 305 into which the laser light is made incident at its apex. The optical block 302 is further provided in a portion facing the entrance hole 305, and has a convex spherical first reflecting mirror 306 that reflects the laser light emitted through the entrance hole 305, and the first reflecting mirror 306. The second reflecting mirror 307 having a concave spherical surface that reflects the laser light reflected by the first reflecting mirror 306 again so as to converge on the rear side (lower side) of the reflecting mirror 306, and the second reflecting mirror 30.
The plane emission surface 3 from which the laser light reflected by 7 is emitted
08. The refractive index of the optical block 302 is
It is equal to the refractive index of the substrate 11, and is 1.57, for example.

The optical characteristics of the optical block 302 as described above are adjusted so that the thickness of the substrate 11 of the optical disk 10 is taken into consideration, and the first reflection mirror 30 is adjusted.
The converging point P connected at the rear side (lower side) of 6 is the optical disc 1
It is adjusted to be positioned on the magneto-optical recording layer 12 of 0. Here, the optical block 302 is set so as to have optical characteristics in consideration of the thickness of the substrate 11. That is, the optical block 302 is set so that desired optical characteristics can be obtained only when it is combined with the substrate 11. More specifically, when the refractive index of the optical block 302 is equal to the refractive index of the substrate 11, the shape of the optical block 302 is based on the shape of the optical block designed to collect light at the center of the emission surface. The thickness of the substrate 11 is cut from the lower side.

The bare chip 303 has a semiconductor laser that emits a laser beam for irradiating the optical disk 10 and an entrance hole 305 of the optical block 302 on a single semiconductor substrate.
And a photodetector for receiving the return light from the optical disc 10 which is emitted through the above.

Here, an example of dimensions of each part in the optical pickup device 300 will be given. The total thickness of the optical block 302 and the bare chip 303 is 2.0 m.
m, the thickness of the substrate 11 of the optical disk 10 is 0.3 mm, the thickness from the magneto-optical recording layer 12 to the lower surface of the magnetic head 34 is 1.0 mm, and the optical block 302 during recording and reproduction is
The air gap between the optical disk 10 and the optical disk 10 is 0.15 μm. Therefore, the thickness of the entire optical pickup device 300 excluding the optical head arm 310 is 3.3 mm because the air gap is substantially zero.

The other structure in this embodiment is the same as that in the first embodiment.

Next, the operation of the optical pickup device 300 having such a configuration will be described. At the time of recording or reproducing data, the optical disk 10 is rotationally driven by the spindle motor 20 at a constant angular velocity (CAV) or a constant linear velocity (CLV), and the bare chip 3 is used.
The semiconductor laser provided in No. 03 is driven to emit laser light. The flying head is levitated by the rotational force of the optical disc 10 to form a predetermined air gap. If the air gap between the optical block 302 and the optical disk 10 is too large, it will hinder the improvement of the numerical aperture. For example, when the semiconductor laser provided on the bare chip 303 emits red laser light having a wavelength of 680 nm, the optical block 302 and the optical disk 10 are used.
The air gap between and is adjusted to be 0.34 μm or less, which is ½ or less of the laser wavelength, for example, 0.15 μm.

Next, the laser light emitted from the semiconductor laser provided on the bare chip 303 enters the optical block 302 through the entrance hole 305, and the bare chip 30
Optical block 30 provided to face 3
The second first reflection mirror 306 is irradiated. The first reflection mirror 306 has a substantially convex hemispherical shape and reflects the light from the semiconductor laser to the second reflection mirror 307 side. The second reflecting mirror 307 has a concave, substantially hemispherical shape, and converges the laser light reflected by the first reflecting mirror 307 at a point P behind (lower side) the first reflecting mirror 307. And is emitted via the emission surface 308. The light emitted from the optical block 302 passes through the substrate 11 of the optical disc 10 and is focused on the magneto-optical recording layer 12.

Here, the second reflecting mirror 307 of the optical block 302 reflects the laser light so that it converges at a point P behind (lower side) the first reflecting mirror 306. The optical characteristics of the optical block 302 are adjusted so that they converge at the point P on the magneto-optical recording layer 12 of the optical disk 10 only in consideration of the optical characteristics of the substrate 11 of the optical disk 10. Specifically, as described above, the thickness of the substrate 11 of the optical disc 10 is, for example, 0.3 mm,
The refractive index n is 1.57, for example. Therefore, the optical block 302 forms one optical characteristic only by adding the thickness in consideration of the thickness of the optical block 302 and the thickness of the substrate 11, in other words, the thickness of the optical block 302 and the thickness of the substrate 11. Is adjusted.

In many cases, the optical block 302 does not have optimum optical characteristics due to the occurrence of aberration due to the influence of the substrate 11 of the optical disk 10. However, unlike the optical pickup device 300 in this embodiment, the thickness of the optical block 302 is different. By designing the optical block 302 so that the optical characteristics of one optical block are formed only after the thickness of the substrate 11 is added, it is possible to prevent the aberration due to the transparent substrate 11 from occurring. Since the thickness of the transparent substrate 11 is known in advance before designing the optical block 302, the design of the optical block 302 may be performed in consideration of this and can be easily performed.

Since the optical pickup device 300 has the flying head structure, the working distance can be set to 0.1 μm, for example. Therefore, the optical path in the optical pickup device 300 can be significantly shortened, and the optical pickup device 300 itself can be significantly downsized.

Next, the magneto-optical recording layer 12 of the optical disk 10
When the laser beam is irradiated on the magnetic field, a magnetic field modulated by the magnetic head 34 according to the recording data is applied to the position irradiated with the laser beam. The magneto-optical recording layer 12 irradiated with the laser light is heated to the Curie temperature, and the coercive force is weakened by the Curie temperature. The data is magnetized accordingly, and the recording data is recorded.

On the other hand, the magneto-optical recording layer 11 of the optical disk 10
When the laser light is irradiated onto the laser beam, return light from the magneto-optical recording layer 11 is generated. This return light is the substrate 1 of the optical disc 10.
The light is irradiated onto the second reflection mirror 307 of the optical block 302 through the emission surface 308 of the optical block 302.
The second reflection mirror 307 reflects the return light to the first reflection mirror 306 side. The first reflection mirror 306 reflects this return light and emits it to the bare chip 305 side via the incident hole 305. The bare chip 305 is provided with a photodetector at a position where the return light emitted through the incident hole 305 is irradiated. This photodetector receives the return light, and the focus error signal, the tracking error signal, and the prepit reproduction signal are detected based on the received light amount. The focus error signal and the tracking error signal are supplied to the servo control system. The servo control system responds to the focus error signal and the tracking error signal by the optical pickup device 30.
The actuator 309 of 0 is driven to perform focus servo and tracking servo. As a result, data can be accurately recorded with just focus and just track.

When the inventor of the present application made a trial test of such an optical pickup device 300, the numerical aperture (NA) can be set to 1.36 which is 1 or more, and the beam of the laser light with which the optical disk 10 is irradiated. The spot diameter is 0.25μ
m. Then, the land recording can realize a recording density of 3.5 Gbit / inch ² which is about three times the conventional recording density. This has a numerical aperture of 0.6,
The effect is the same as when a blue semiconductor laser with a laser wavelength of 300 nm is used. As a result of using land recording and groove recording together, a recording density of 8 Gbit / inch ² could be realized.

Next, at the time of reproducing the data recorded in this way, the optical disk 10 is rotationally driven by CAV or CLV, and the optical block 302 having the flying head structure is controlled to move (seek) to a desired recording track. ) Will be done. Then, the semiconductor laser provided on the bare chip 303 is driven to emit light to emit laser light. The laser light is sequentially reflected by the first reflection mirror 306 and the second reflection mirror 307 of the optical block 302, and is irradiated onto the magneto-optical recording layer 12 via the substrate 11 of the optical disc 10. This produces a return light that is modulated by the recorded data. This return light is
The light enters the optical block 302 through the substrate 11 and
Are sequentially reflected by the reflection mirror 307 and the first reflection mirror 306, and the photodetector provided on the bare chip 303 is irradiated through the incident hole 305. The photo detector receives the return light emitted through the entrance hole 305 of the optical block 302, and detects the magneto-optical reproduction signal, the focus error signal, the tracking error signal, and the pre-pit reproduction signal based on the amount of the returned light. .
The focus error signal and the tracking error signal are supplied to the servo control system. The servo control system performs focus servo and tracking servo of the optical pickup device 300 based on the focus error signal and the tracking error signal. As a result, the recording and reproducing of the record data can always be performed accurately with the just focus and the just track.

The memory element including the optical pickup device 300 according to the present embodiment can be formed in the size shown in FIGS. 3 and 4, for example. In this case, the optical characteristics of the optical block 302 are adjusted in consideration of the thickness of the substrate 11 of the optical disc 10, and as a result, the laser light can be converged to a diameter of 0.25 μm, for example. Therefore, the storage element according to the present embodiment can realize a storage capacity of, for example, 230 Mbytes using the 0.7-inch optical disc 10.

Other configurations, operations and effects of the present invention are similar to those of the first embodiment.

FIG. 22 is a sectional view of a memory element according to the sixth embodiment of the present invention. The storage element 400 according to the present embodiment has an optical disc and an optical pickup device,
This is an example of a rewritable type that utilizes phase change, a read-only type, or a write-once type. In this storage element 400, the magneto-optical recording type optical disc 1 according to the first embodiment is used.
Instead of 0, a rewritable type, a read-only type, or a write-once type optical disc 401 using phase change is used. In addition, in this memory element 400, a rewritable type, a read-only type, or a write-once type optical pickup device 410 utilizing a phase change is used instead of the magneto-optical recording type optical pickup device 30 in the first embodiment. To be In this optical pickup device 410, a laser coupler 411 is provided instead of the laser coupler 40 in the first embodiment, and a 1/4 quarter is used instead of the two-part split optical rotation plate 42.
A wave plate 412 is provided. In addition, the storage element 400
Then, the magnetic head arm 3 in the first embodiment
3 and the magnetic head 34 are not provided.

FIG. 23 is a plan view of the laser coupler 411. The laser coupler 411 has a semiconductor laser 61 formed on a single semiconductor substrate 60 and a plurality of photodetectors 413a to 413l. Similar to the first embodiment, on the semiconductor substrate 60, a reflection mirror portion 63 that reflects the emitted light of the semiconductor laser 61 upward is formed at a position facing the laser light emitting portion of the semiconductor laser 61. Has been done.

The photodetectors 413a and 413d are
The region of the photodetector 62a in FIG. 9 is formed at a position and a shape obtained by dividing the region of the photodetector 62a by a dividing line in a direction corresponding to the track direction on the optical disc 401. The photodetectors 413b and 413e are formed at positions and shapes obtained by dividing the combined area of the photodetectors 62b and 62c in FIG. 9 by a dividing line in a direction corresponding to the track direction on the optical disc 401. The photodetectors 413c and 413f are formed at positions and shapes obtained by dividing the area of the photodetector 62d in FIG. 9 by a dividing line in a direction corresponding to the track direction on the optical disc 401. Note that among these photodetectors, the photodetectors 413d to 413
f is arranged at a position on the semiconductor laser 61 side.

Similarly, the photodetectors 413g, 41
3j is formed at a position and a shape obtained by dividing the area of the photodetector 62g in FIG. 9 by a dividing line in a direction corresponding to the track direction on the optical disc 401. The photodetectors 413h and 413k are formed at positions and shapes obtained by dividing the combined area of the photodetectors 62h and 62i in FIG. 9 by a dividing line in a direction corresponding to the track direction on the optical disc 401. The photodetectors 413i and 413l are arranged so that the area of the photodetector 62j in FIG.
2 at the dividing line in the direction corresponding to the track direction at 01
It is formed in divided positions and shapes. Among these photo detectors, the photo detector 413
g to 413i are arranged on the semiconductor laser 61 side.

In the optical pickup device 410 according to the present embodiment, the P-polarized laser light emitted from the semiconductor laser 61 passes through the polarization hologram 41 as it is, and
The circularly polarized light passes through the / 4 wavelength plate 412, is reflected by the reflecting prism 38, is condensed by the solid immersion lens 37, and is irradiated onto the recording layer of the optical disc 401. The return light from the optical disc 401 is condensed by the solid immersion lens 37, reflected by the reflection prism 38, passes through the quarter-wave plate 412, becomes S-polarized light, enters the polarization hologram 41, and is diffracted. It Here, the + 1st-order diffracted light is once converged on the way and is then diffused to be a photodetector 41 on the laser coupler 411.
The −1st-order diffracted light which is incident on 3a to 413f is converged light as it is, and the photodetector 413 on a laser coupler 411
It is incident on g ~ 413l.

When the output signals of the photo detectors 413a to 413l are a to l, respectively, the focus error signal FE, the track error signal TE and the reproduction signal RF are shown.
Are respectively calculated by the following equations (12) to (14).

FE = (a + c + d + f + h + k)-(b + e + g + i + j + l) ... (12) TE = (a + b + c + j + k + l)-(d + e + f + g + h + i).

At the time of reproduction, the output of the semiconductor laser 61 is set to a low output for reproduction. Further, at the time of recording in the case of the rewritable type or the write-once type utilizing the phase change, the output of the semiconductor laser 61 is intermittently set to a high output for recording according to the recording data, and the data is recorded.

According to the storage element 400 of the present embodiment, since there is no magnetic head, the structure becomes simpler, and further miniaturization and cost reduction can be achieved. Other configurations, operations and effects in the present embodiment are the same as those in the first embodiment.

Now, referring to FIGS. 24 and 25,
A preferable size in the memory element of the present invention will be described. Since the memory element of the present invention is extremely small, it can be considered that one or more memory elements are mounted on the IC card as a usage example. As an IC card, PCMCI
A (Personal Computer Memory Card International As
There is a PC card that conforms to the standards of sociation). PCM
CIA standards include Type I, Type II, and Type III. The memory element of the present invention is a type II with a maximum thickness of 5 mm.
If so, two per PC card, maximum thickness is 10.5
With the mm type III, it is possible to mount four (two on each of the front side and the back side) on one PC card. As shown in FIG. 24, when mounted on a PC card 421, the size of the storage element 420 of the present invention is 20 mm or less in length, 38 mm or less in width, and 3.8 m in thickness.
m or less is preferable. In particular, when the planar shape of the memory element is a square shape, it is preferable that one side has a length of 20 mm or less and a thickness of 3.8 mm or less. Also, a PC card 421
As shown in FIG. 25, the memory element mounted on
Storage element 4 in which two optical disks 431 and components necessary for each optical disk 431 are housed in one package
You may create 30. The memory element 430 has a size of 40 mm or less in length, 38 mm or less in width, and a thickness of 3.8.
mm or less is preferable.

Since the memory element of the present invention can be handled as an electronic component like an IC, it can be used in place of a semiconductor memory in a computer, for example, or a plurality of memory elements can be provided in parallel to increase the operation speed. Can contribute to. For example, about 100 × 100 pieces can be provided inside the computer device and used as a substitute for the internal memory. Further, since the memory element of the present invention enables high-density recording, it can be used as a built-in memory of a mobile phone, for example. As a result, the mobile phone can record the image data transmitted together with the voice data, and by providing the mobile phone with display means such as a liquid crystal monitor, it becomes possible to realize an answering machine videophone.

The present invention is not limited to each of the above-described embodiments. For example, in the description of each of the above-described embodiments, an optical disc has a recording layer on one side of a transparent substrate, and the recording layer is changed from the substrate side to the recording layer. While an example of an optical disc that is used by irradiating light with respect to it has been given, the present invention can also be applied to an optical disc that is used by irradiating light to a recording layer without using a substrate. When using such an optical disc, oil may be provided on the recording layer of the optical disc. The oil on the optical disk is evenly spin-coated by rotating the optical disk. In this case, by adjusting the optical characteristics of the solid immersion lens and the optical block so that the optical characteristics of the oil to be spin-coated are taken into consideration, the same effects as those described in the respective embodiments are obtained. be able to.

Further, the specific numerical values given in the above-mentioned respective embodiments are merely examples, and the present invention is not limited to these numerical values. Therefore, it goes without saying that these numerical values can be variously changed according to the design and the like as long as they do not deviate from the technical idea of the present invention.

The present invention can also be applied to the case where a method other than the method (such as the magneto-optical recording method) mentioned in each of the above-mentioned embodiments is used as the recording / reproducing method.

Further, the optical pickup device shown in each of the above-mentioned embodiments is suitable for use in a storage element whose constituent elements are sealed in a package, but it is not limited to such a storage element, and a conventional optical disk is used. It can also be applied to an optical pickup device in the device.

[0174]

As described above, the first to seventeenth aspects of the present invention can be realized.
According to any one of the storage elements described above, since the optical disc, the rotation driving means, and the optical pickup device are sealed in a package, the configuration is simplified, and the optical disc has a high density and a large capacity. In addition, it is possible to realize a memory element that is small, has high density, and has a large capacity and can be handled in the same manner as an electronic component.

According to the storage element of the fifth aspect,
Since the package has a sealing means for sealing the optical disk in a state where the inside of the package is filled with a fluid having a refractive index higher than that of air, the optical performance can be improved in addition to the effect of the storage element according to claim 1. It is possible to extend the life of the optical disc and cool the optical disc.

According to the memory element of claim 7,
Since the optical system of the optical pickup device is configured to include a solid immersion lens arranged to face the optical disc, in addition to the effect of the storage element according to claim 1,
The diameter of the light irradiated onto the optical disc can be reduced, and high density recording can be achieved.

According to the storage element of claim 8,
Since the solid immersion lens is an aspherical lens, in addition to the effect of the memory element according to the seventh aspect, there is an effect that the thickness of the memory element can be reduced.

According to the storage element of the ninth aspect,
The effect of the storage element according to claim 7, wherein the solid immersion lens is set so as to have optical characteristics in consideration of the thickness of the transparent substrate of the optical disc existing between the solid immersion lens and the recording layer of the optical disc. In addition, the numerical aperture can be improved without being adversely affected by the substrate, high-density recording can be achieved, the beam quality can be improved, and the wavefront aberration can be easily managed. There is an effect that can be.

According to the optical pickup device of any one of claims 18 to 20, the solid immersion lens arranged to face the optical disc is present between the solid immersion lens and the recording layer of the optical disc. Since the optical characteristics are set in consideration of the thickness of the transparent substrate of the optical disc, the numerical aperture can be improved without being adversely affected by the substrate, and high-density recording can be achieved. The beam quality can be improved, and the wavefront aberration can be easily managed.
It is possible to realize an optical pickup device that has a large capacity and is suitable for use in a storage element that can be handled like electronic parts.

According to the optical pickup device of any one of claims 21 to 24, the optical system is arranged so as to face the optical disc, the light from the light emitting means is incident, and the return light from the optical disc is received. From the first incident / emission part that emits light, the second incident / emission part that emits the light from the light emitting means and the return light from the optical disc enters, and the light emitting means that enters the first incident / emission part. Of the light from the light emitting means reflected by the first reflecting portion and the second reflecting portion which reflects the light of the above with the convex spherical surface, and is emitted from the second entrance / exit portion to the second entrance / exit portion. Of the transparent substrate of the optical disc existing between the optical block and the recording layer of the optical disc. To have optical characteristics that take thickness into consideration Since it is set, the numerical aperture can be improved without being adversely affected by the substrate, high-density recording can be achieved, the beam quality can be improved, and further, the wavefront aberration can be improved. An effect that the management can be facilitated, and further, an optical pickup device that is small, high-density, and large-capacity and that is suitable for use as a storage element that can be handled like electronic parts can be realized. Play.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a memory element according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway bottom view showing a bottom portion of the memory element shown in FIG.

FIG. 3 is a plan view showing an example of the outer shape of the memory element according to the first embodiment of the present invention.

FIG. 4 is a side view of the memory element shown in FIG.

FIG. 5 is a plan view of the spindle motor in the storage element according to the first embodiment of the present invention.

6 is a cross-sectional view of the spindle motor shown in FIG.

7 is an explanatory diagram equivalently showing an optical system in the optical pickup device in FIG. 1. FIG.

8 is a perspective view showing the upper side of the two-part optical rotation plate in FIG.

FIG. 9 is a plan view of the laser coupler in FIG.

10 is a side view of the laser coupler in FIG. 1. FIG.

FIG. 11 is an explanatory diagram for explaining the principle of detection of a magneto-optical reproduction signal in the memory element according to the first embodiment of the present invention.

FIG. 12 is an explanatory diagram for explaining a principle of detection of a focus error signal, a tracking error signal, and a prepit reproduction signal in the memory element according to the first embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a circuit in the memory element according to the first embodiment of the present invention.

FIG. 14 is a cross-sectional view of a memory element according to a second embodiment of the present invention.

FIG. 15 is a cross-sectional view of a memory element according to a third embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a schematic configuration of an optical pickup device in a storage element according to a fourth embodiment of the present invention.

17 is an explanatory diagram showing a modified example of the optical pickup device shown in FIG.

FIG. 18 is an explanatory diagram for explaining a problem of a technique using a conventional solid immersion lens.

FIG. 19 is an explanatory diagram for explaining the effect of the solid immersion lens according to the fourth embodiment of the present invention.

FIG. 20 is an explanatory diagram showing a laser coupler according to a fourth embodiment of the present invention.

FIG. 21 is an explanatory diagram showing a schematic configuration of an optical pickup device in a storage element according to a fifth embodiment of the present invention.

FIG. 22 is a sectional view of a memory element according to a sixth embodiment of the present invention.

FIG. 23 is a plan view of a laser coupler according to a sixth embodiment of the present invention.

FIG. 24 is an explanatory diagram for explaining a preferable size in the memory element of the present invention.

FIG. 25 is an explanatory diagram for explaining a preferable size in the storage element of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Storage element, 10 ... Optical disk, 20 ... Spindle motor, 30 ... Optical pickup device, 34 ... Magnetic head,
37 ... Solid immersion lens, 50 ... PA

Claims (24)

[Claims] 1. An optical disk for carrying information reproduced by using light, a rotation driving means for rotating the optical disk, recording of information on the optical disk and reproduction of information from the optical disk by using light. An optical pickup device for reproducing at least one of them, a package for encapsulating the optical disc, the rotation driving means and the optical pickup device, and a terminal provided in the package for connecting a circuit in the package to an external circuit. A storage element characterized by being provided. 2. The storage element according to claim 1, wherein the optical disc is a rewritable type, and the optical pickup device performs both recording and reproduction. 3. The storage element according to claim 1, wherein the optical disc is a read-only type, and the optical pickup device only performs reproduction. 4. The storage element according to claim 1, wherein the optical disk is a write-once type, and the optical pickup device performs both recording and reproduction. 5. The storage element according to claim 1, further comprising a sealing unit that seals the optical disk inside the package with a fluid having a refractive index larger than that of air filled therein. 6. The optical pickup device emits light for irradiating an optical disc, a light receiving unit for receiving return light from the optical disc, and irradiates the optical disc with the light emitted from the light emitting unit. The storage element according to claim 1, further comprising an optical system that guides return light from the optical disk to the light receiving means. 7. The storage element according to claim 6, wherein the optical system includes a solid immersion lens arranged to face the optical disc. 8. The storage element according to claim 7, wherein the solid immersion lens is an aspherical lens. 9. The solid immersion lens is set to have optical characteristics in consideration of the thickness of a transparent substrate of an optical disk existing between the solid immersion lens and a recording layer of the optical disk. The storage element according to claim 7. 10. The storage element according to claim 7, wherein at least a part of the optical system has a flying head configuration. 11. The optical disk is a magneto-optical disk, and the optical system receives linearly polarized light from the light emitting means and allows the light from the light emitting means to pass without being diffracted, and the light emitting means. Diffraction means for diffracting light in a polarization direction orthogonal to the polarization direction of the light from the optical disc and a part of the light obtained by passing the return light from the optical disc, which is arranged on the optical disc side of the diffractive means. The light incident on the magneto-optical disk is diffracted by the means so that the intensity of the diffracted light changes in accordance with the information on the magneto-optical disk. 7. The storage element according to claim 6, further comprising: an optical rotation unit that rotates the light at an angle of. 12. The storage element according to claim 6, further comprising drive means for moving at least a part of the optical system for positioning light irradiated on the optical disk. 13. The storage element according to claim 1, further comprising drive means for moving the optical disk for positioning the light applied to the optical disk. 14. The light emitting means and the light receiving means are formed on the same substrate, and a driving means for moving the substrate for positioning the light irradiated on the optical disk is provided. Memory element. 15. The storage element according to claim 1, further comprising seek means for performing seek by moving at least a part of the optical pickup device. 16. The storage element according to claim 1, further comprising seek means for moving the optical disk to perform seek. 17. The package has a length and width of 20 mm or less and 38 mm or less, respectively, and a thickness of 3.8 m.
The storage element according to claim 1, wherein the storage element is m or less. 18. An optical pickup device for carrying out at least one of recording information on an optical disc for carrying information reproduced using light and reproducing information from the optical disc, for irradiating the optical disc. Light emitting means for emitting the light of
The optical system includes a light receiving unit that receives the return light from the optical disc, and an optical system that irradiates the optical disc with the light emitted from the light emitting unit and guides the return light from the optical disc to the light receiving unit. Including a solid immersion lens arranged opposite to each other, this solid immersion lens is set to have optical characteristics in consideration of the thickness of the transparent substrate of the optical disc existing between the solid immersion lens and the recording layer of the optical disc. An optical pickup device characterized in that 19. The optical pickup device according to claim 18, wherein the refractive index of the solid immersion lens is set to be the same as the refractive index of the transparent substrate of the optical disc. 20. The optical pickup device according to claim 18, wherein the optical system has a flying head configuration. 21. An optical pickup device for carrying out at least one of recording information on an optical disc for carrying information reproduced using light and reproducing information from the optical disc, for irradiating the optical disc. Light emitting means for emitting the light of
The optical system includes a light receiving unit that receives the return light from the optical disc, and an optical system that irradiates the optical disc with the light emitted from the light emitting unit and guides the return light from the optical disc to the light receiving unit. A first entrance / exit portion, which is arranged so as to face each other, receives light from the light emitting means and emits return light from the optical disk, and emits light from the light emitting means and receives return light from the optical disk. Second
From the light emitting and receiving portion, the first reflecting portion that reflects the light from the light emitting means that is incident on the first light emitting and receiving portion on the convex spherical surface, and the light emitting means that is reflected by the first reflecting portion. The light of the second
And an optical block including a second reflecting portion that is reflected by a concave spherical surface so as to be emitted from the incident / emission portion and converge on the outside of the second incident / emission portion. The optical pickup device is characterized in that the optical characteristics are set in consideration of the thickness of the transparent substrate of the optical disc existing between the recording layer and the recording layer. 22. The optical pickup device according to claim 21, wherein the refractive index of the optical block is set to be the same as the refractive index of the transparent substrate of the optical disc. 23. The optical pickup device according to claim 21, wherein the optical system has a flying head structure. 24. The light emitting means and the light receiving means are formed on the same substrate, and the substrate is arranged so as to face the first entrance / exit portion of the optical block. Optical pickup device.