JPH10247327A - Optical head device - Google Patents

Abstract

(57) [Summary] It is possible to obtain weight reduction, miniaturization, and ease of manufacturing. One end of an arm is fixed to an outer surface of a lens holder, and the other end extends along a tracking control direction (X-axis direction) orthogonal to an optical axis direction (Z-axis direction) of the objective lens. Exist. Arms 103, 104
Is supported by a support beam, and supports the lens holder 101 so as to be controlled to move in the X-axis direction and the Z-axis direction. Then, the permanent magnets 121, 1
A coil and yoke parts 123 and 124 are provided opposite to 22, and can be driven in a focus and tracking control direction by giving a magnetic effect. Here the permanent magnet 1
An escape portion 30 and a cutout portion 31 are formed in the component 21 and the notch 31 to secure an optical path of a light beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used for reading recorded information on a recording surface of an information recording medium such as an optical disk or for recording information on an optical disk.

[0002]

2. Description of the Related Art Conventionally, compact disks (CD) and laser disks (LD) exclusively for music have been used as optical disks.
Is being developed. On the other hand, recently, moving picture video data, audio data, and sub-picture data (for example, subtitle data) are compressed and recorded at high density on a compact compact disc (a disc having the same radius as the CD). Regarding audio and subtitles, a system has been developed in which a plurality of different languages are recorded, and at the time of reproduction, audio of a desired language and subtitles of a desired language can be freely selected and reproduced. This type of optical disk is tentatively referred to as a DVD (digital versatile disk). As for DVDs, DVD-ROMs and DVD-RAMs are being developed.

A reproducing apparatus for reproducing such an optical disk includes a rotary servo unit for controlling the rotation of the disk,
An optical head device that reads a modulation signal recorded by irradiating a laser beam onto a recording surface of a disk and detecting light reflected from the recording surface is provided. The modulated signal output from the optical head device is first input to a waveform equalization circuit, where the waveform is equalized. Next, the waveform-equalized signal is guided to the demodulation circuit.

Further, the optical head device is provided with a focus servo system and a tracking servo system. Here, when the disc is mounted on the reproducing apparatus and the disc is rotated, first, a focus servo operation is performed. When the focus state is reached by the focus servo, the tracking servo is also turned on and the apparatus enters the tracking control state.

[0005]

In order to realize the above-described focus servo and tracking servo, the objective lens in the optical head device is finely controlled in the direction of its optical axis and in the tracking direction (the direction of traversing the track of the disk). A mechanism to do this is needed. When designing the mechanism of this type of optical head device, it is desirable that the optical head device be as small and lightweight as possible in order to improve the driving performance with low power. In order to further reduce the size and weight, a reduction in thickness is also required.

Here, if the thickness is reduced, interference between a driving mechanism for driving the above-mentioned objective lens and a beam irradiated on the disk via the objective lens becomes a problem. Therefore, an object of the present invention is to provide an optical head device capable of preventing interference between a driving mechanism for driving an objective lens and a beam irradiating a disk via the objective lens, thereby achieving a thinner device. To provide.

[0007]

In order to achieve the above object, the present invention provides a lens holder for holding an objective lens, one end of which is fixed to the lens holder, and the other end of which is in the optical axis direction of the objective lens. First arm means including a first arm extending along a tracking control direction (X-axis direction) orthogonal to the Z-axis direction); one end fixed to the lens holder; The tracking control direction (X-axis direction) orthogonal to the optical axis direction (Z-axis direction)
A second arm extending along the first arm and extending in a direction opposite to the direction in which the first arm extends, and the other of the first and second arms One end is connected to the end via a connecting member, and the other end of each end is extended in a direction substantially perpendicular to the extending direction of the first and second arm means, and the lens holder is provided with the tracking. A support beam for supporting the lens holder to move in the control direction and the focus control direction; first and second permanent magnets attached to respective side surfaces of the lens holder formed in parallel with the X-axis direction; The first and second permanent magnets have first and second coils and a yoke component which are arranged at an interval from each other, and the support beam is provided in a Y-axis direction orthogonal to the X-axis direction and the Z-axis direction. Lower side of the first permanent magnet on the opposite side A notch is formed in a part, and the coil and the yoke component facing the permanent magnet also form a notch having a substantially similar shape at the position facing the notch. Is provided with an optical path.

According to the above-mentioned means, when the optical path of the light beam is turned by a prism or a mirror below the objective lens, an optical path can be obtained through the escape portion and the cutout portion, and the overall device can be made thinner. It can be obtained and can contribute to miniaturization.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the mechanical appearance of an optical head device according to the present invention. This device is
It has a lens holder 101 for holding the objective lens, and a lens holder support mechanism for supporting the lens holder 101 so that it can move in the illustrated Z-axis direction (focus control direction) and the illustrated X-axis direction (tracking control direction).

[0010] The lens holder support mechanism is configured as follows. First, the objective lens 102 is held by a lens holder 101 having a hollow in the vertical direction (Z-axis direction). On the outer surface of the lens holder 101, one ends of elongated arms 103 and 104 (a thin plate-shaped member having a thickness of about 1 mm) extending left and right in the Z-axis direction are integrated. Each of the arms 103 and 104 is a thin plate having a flat surface in the optical axis direction.

That is, the elongated arm 103 has one end fixed to one outer surface of the lens holder 101 and the other end extending along one of the tracking control directions (X-axis direction) orthogonal to the Z-axis direction. The arm 104 has one end fixed to the other outer surface of the lens holder 100 and the other end extending along the other in the X-axis direction orthogonal to the Z-axis direction.

At the other end of each of the elongated arms 103 and 104,
One ends of wire-shaped support beams 107 and 108 as elastic support members are connected via connection members 105 and 106. The other ends of the support beams 107 and 108 are held by a holder 109.

That is, the wire-like support beams 107, 108
Extends in a direction perpendicular to the direction in which the arms 103 and 104 extend, and is supported so that the lens holder 101 can be controlled to move in the tracking control direction and the focus control direction.

Specifically, the wire-like support beam 107 is
The upper and lower wires 107A and 107B are provided in parallel, and the wire-like support beam 108 is connected to the upper and lower wires 108A and 108B.
Are provided in parallel. Each of the upper and lower wires has, for example, a rectangular cross section. The supporting beams 107 and 108 are also made of a nonmagnetic resin (for example, polyphenylene sulphite), an alloy of stainless steel, copper, or a phosphor blue body. The connecting member 10
The connection portions between the support members 5 and 106 and the support beams 107 and 108 and the holder 109 are made of a non-magnetic material such as polyphenylene sulfide or a liquid crystal polymer.

In the above configuration, the upper and lower wires 107
A, 107B and upper and lower wires 108A, 108B are connected to the arms 103, 104.
04 has a width in the vertical direction (focus direction)
That is, the support width of the beam is expanded. In other words, by making the arm thinner and wider in the Z direction, the support is stabilized without increasing the weight. Further, by connecting the lens holder 101 to the support beam via the arms 103 and 104, the support width in the X direction is also increased. In addition, rigidity is exhibited in the driving direction. Thereby, the rigidity is large with respect to the moment about the Y axis due to the driving, and the occurrence of tilt can be suppressed. In addition, since the rigidity is high in the driving direction of the lens holder 101, the resonance frequency caused by the driving force can be shifted to a higher frequency range, and the occurrence of resonance in a practical vibration range can be eliminated. In addition, it is of course possible to reduce the weight and to improve the driving performance.

The holder 109 is a holder attached to the chassis, and is formed of, for example, a hard non-magnetic resin (for example, polyphenylene sulphite). The above-mentioned lens holder, thin plate-like arm, fixing member, and support beam may be made of the same material, and the fixing direction may be bonding, integral molding, or another method.

Although not shown, the mechanism 109 has a holding body 109 disposed on a sub-chassis, and the sub-chassis is supported by a guide rail, and is movable in a radial direction of the optical disk. The movement control for this is performed by a pickup drive motor (not shown).

Next, a driving means for driving the above-mentioned lens holder 101 in the Z-axis direction and the X-axis direction will be described. In this apparatus, the basic concept of the driving means for driving the lens holder 101 in the Z-axis direction and the X-axis direction is as follows. That is, when the light beam is guided to the lower part of the lens holder and guided to the objective lens 102 by a reflection mirror or a prism, an obstacle is not present in the middle of the optical path, and the degree of freedom in selecting the optical path is increased. As a result, the device can be downsized,
The object is to realize simplicity of design, to obtain improved performance and reduced cost.

As shown in FIG. 2A, substantially rectangular permanent magnets 121 and 122 are provided on the side surface of the lens holder 101 as a driving force generating source, for example, as shown in FIG. Here, the shape of the permanent magnet 121 is such that the lower region is partially cut away and the escape portion 30 is formed. That is, in the rectangular vertical side z1 and the horizontal side x1, a part of the region has a reduced length in the vertical direction, and the shortened part is folded into an L shape toward the holder. ing. As a result, a decrease in magnetic flux can be suppressed. The length of the L-shaped portion may be increased, or a permanent magnet 121 'having a thicker magnet member may be used instead of the L-shape (see FIG. 3D).

The other permanent magnet 122 has a rectangular shape.
Next, the coil and the yoke component 1 are respectively set at fixed positions so as to face the permanent magnets 121 and 122 with a gap therebetween.
23 and 124 are arranged.

Here, the coil and the yoke component 123 facing the permanent magnet 121 have a notch 31 at a portion facing the escape portion 30 in a substantially similar shape. The coil wound around the notch 31 has a small diameter and has a large number of turns.

When the permanent magnet 121, the coil and the yoke part 123 are configured as described above, even if the whole is made thin,
As shown in FIG. 2B, when a light beam is guided to a lower portion of the lens 102 of the lens holder 101, the direction of the light path is changed by a mirror or a prism, and the light beam is emitted from the lens 102, a free path for selecting the light path is provided. High degree. That is, it can be freely selected within the range of the angle θ formed by the optical path W1 and the optical path W2. This is because both the permanent magnet 121 and the coil and yoke component 123 have the escape portion 30 and the notch portion 31 so as not to interfere with the optical path. As a result, a reduction in thickness can be obtained, and a degree of freedom in design can be obtained.

Here, points to keep in mind when designing the above device will be described. As shown in FIG. 2B, suppose that an X axis and a Y axis pass through the center of the lens 102 in a plane.
A first quadrant, a second quadrant, a third quadrant, and a fourth quadrant are set.
Here, the number of turns of the coil is adjusted such that the force Fi acting between the permanent magnet and the coil and the yoke component is equally constant in each quadrant. That is, Fi is I × φ × Ni
(Φ is the magnetic flux, N is the number of turns of the coil, I is the current, i is 1 to 4 and is a quadrant), so that the number of turns N is adjusted in each quadrant, and F
Are made to be equal. In the case of this example, for example, the number of turns of the coil in the third quadrant is increased. Further, a coil having a small diameter is used in this portion.

FIG. 2C shows the coil and yoke component 12.
3 is taken out and shown. The component 123 has a coil LF for focus control and a coil LT for tracking control wound around the yoke 125.

The present invention is not limited to the above embodiment. FIG. 3 shows another embodiment of the main part of the present invention. The drive means shown in FIG. 2 has a structure in which the coil and the yoke parts 123 and 124 respectively wind both a focus control coil and a tracking control coil. On the other hand, in the embodiment of FIG.
31 and 132 and a coil and yoke components 133 and 134 for tracking control are divided. That is, the permanent magnets 135 and 136 are integrated on the side surface of the lens holder 101, as in the previous embodiment. And, as for the shape of the permanent magnet 135, the escape portion 30 is formed as described above. Then, coils and yoke components 133 and 134 are arranged facing the permanent magnets 135 and 136. The shape of the coil and yoke component 133 is
A notch 31 corresponding to 0 is provided. next,
The arcs 103, 134 are magnetized arms. The U-shaped coil and yoke components 131 and 132 act on the arms 103 and 104, and the components are arranged so that the arms 103 and 104 are positioned between their legs.

FIG. 3B shows a structural example of the arms 103 and 104, for example, in which a yoke Yo is insert-molded on a plastic magnet Mg. This example is an example in which a yoke is insert-molded inside. However, the present invention is not limited to this. An arm may be formed by mixing magnetic powder into a plastic material, and the arm may be magnetized by a strong magnetic field. Of course.

According to the driving device for focus and tracking control configured as described above, each of the focus control coil and the yoke component only needs to wind a single target coil. Therefore, the size of the component itself can be reduced, which is advantageous for miniaturization. In addition, together with the effect of the escape portion 30 and the notch portion 31,
The entire device can be reduced in size and thickness.

Furthermore, the thickness can be reduced and the degree of design freedom can be increased. This is the escape part 30, the notch part 3
This is because the drive mechanism such as the coil 1 and the yoke component does not interfere with the optical path.
As for the focus control, a U-shaped yoke is used, and its legs can be lengthened, so that there is an advantage that a sufficient focus control stroke can be obtained. This means that the linear region of the drive sensitivity (the range in which the drive force changes in proportion to the increase in drive current) can be expanded, and stable focus drive can be realized. Furthermore, the longer legs do not interfere with the light in the optical path.

In each of the above-described embodiments, the coil and the yoke component are mounted at fixed positions. However, the coil and the yoke component are stably mounted on the substrate or the housing of the head device by mounting means (not shown). Various embodiments are possible as the attachment means. In addition, a yoke may be attached to the inner (lens side) surface of the permanent magnets 135 and 136 in order to effectively use the magnetic field.

FIG. 4 shows an example of an optical path guided to the objective lens 102 described above. Reference numeral 611 denotes a first light source that outputs a semiconductor laser light (wavelength 650 nm). The laser light output from the first light source 611 travels straight through the focus error detecting element 612, travels straight through the cube beam splitter 613, and passes through the collimator lens 614.

The focus error detector 612 is for diffracting the light on the return path that has been returned from the beam splitter 613 side and guides it to the photodetector 617. The beam splitter 613 guides and outputs the laser light from the first light source 611 and the laser light from the second light source 621 described later in the same output direction on the outward path (to the collimating lens 614). is there. Also, this beam splitter 613
The first and second light sources 611 and 62 emitting the reflected light on the return path, which are backwards from the same output direction.
It branches to one side and leads. Further, the collimating lens 614 has a characteristic of converting laser light, which is diffused light, into parallel light.

The light emitted from the collimating lens 614 is raised by a prism (or a mirror) 615, and the dichroic filter 619 and the objective lens 10
2, a beam spot is formed on the information recording surface of the optical disk. The reflected light reflected from the information recording surface of the optical disk passes through the objective lens 102, the dichroic filter 619, the prism 615, and the collimating lens 614, and enters the beam splitter 613. The beam splitter 613 generates the first and second light sources 611 and 62 that output the reflected light on the return path that has returned in the reverse direction.
It leads to one side. Therefore, when the first light source 611 is used, the beam splitter 613 guides the reflected light to the focus error detection element 612 side, and when the light source 621 is used, the beam splitter 613 detects the reflected light for the focus error detection. It is led to the element 622 side. The focus error detection element 612 utilizes the diffraction effect of the hologram,
The incident light can go straight or be refracted according to the polarization direction. The light output from the focus error detection element 612 is guided to the photodetector 617. Further, when the light source 621 is used, the light output from the focus error detecting element 622 is guided to the light detector 627.

The above-mentioned first light source 611 and photodetector 617
Are integrated as a unit 618. Also the second
The light source 621 and the photodetector 627 are integrated as a unit 628. This has been devised to contribute to miniaturization.

A dichroic filter 619 is provided close to the objective lens 102, and the filter 619 can restrict the numerical aperture (small for a CD and large for a DVD). The dichroic filter 619 changes its physical position integrally with the objective lens 616 in accordance with focus servo and tracking servo.

That is, although not shown, the objective lens 1
02 is the position control in the tracking direction indicated by the arrow Tr and the focus direction indicated by the arrow Fo by supplying control signals from the respective servo circuits to the focus control coil and the tracking control coil as described above. Is done.

As described above, the laser beam enters from the lower part of the objective lens 102, and the reflected light travels to the lower part of the objective lens 102 and is reflected and changes its direction. In order to reduce the thickness of the entire apparatus, it is necessary to design the light incident on the prism 615 so as not to be obstructed by a coil or the like near the objective lens 102. The above-described embodiment has a configuration suitable for reducing the thickness.

FIG. 5 shows how the above-described head device is arranged with respect to the outer casing 800 of the disk device. That is, reference numeral 701 denotes a housing of the head device. The components shown in FIG. 6 are mounted in the head housing 701. Then, the movement of the head housing 701 in the directions of the arrows a1-a2 is controlled by a guide mechanism (not shown).

In this arrangement, the direction in which the first light source 611 and the beam splitter 613 are connected is a direction substantially parallel to one of the side walls 802 forming the corner portion 801 of the outer casing 800, and the second light source 621 The direction in which the beam splitter 613 is connected to the beam splitter 613 is a direction substantially orthogonal to one of the side walls 802 forming the corner 801 of the exterior housing 800. And the second
The light source 621 is disposed inside the focal position as viewed from the collimating lens 614. Due to such an arrangement relationship, the head housing 701 is provided at the corner 8 inside the exterior housing 800.
It is guided in a reciprocable manner in the radial direction between the vicinity of the disk drive 01 and the vicinity of the spindle (rotation drive unit) 901 and facing the information recording surface of the loaded disk.

[0039]

As described above, according to the present invention,
Interference between the drive mechanism for driving the objective lens and the beam irradiating the disk via the objective lens can be prevented, the thickness can be reduced, the weight can be reduced, and the ease of manufacture can be reduced. Obtainable.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a main part of one embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a main part of another embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining an example of an optical path of the device of the present invention.

FIG. 5 is an explanatory diagram showing a state in which the apparatus of the present invention is arranged in a disk reproducing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Lens holder 102 ... Objective lens 103, 104 ... Arm 105, 106 ... Connecting member 107, 108 ... Support beam 109 ... Holding member 221-224 ... Coil and yoke parts 230 ... Yoke 281, 291 ... Yoke 282-284, 292 294: coil.

Claims (4)

[Claims] 1. A lens holder for holding an objective lens, one end of which is fixed to the lens holder, and the other end of which is in a tracking control direction (X-axis direction) orthogonal to the optical axis direction (Z-axis direction) of the objective lens. A first arm means constituted by a first arm extending along the first and second arms; one end of which is fixed to the lens holder, and the other end of which is perpendicular to the optical axis direction (Z-axis direction) of the objective lens; A second arm means extending along the X-axis direction) and in a direction opposite to the direction in which the first arm means extends; and the first and second arm means. The other end of the lens is connected to the other end of the lens via a connecting member, and the other end of the one end is extended in a direction substantially orthogonal to the extending direction of the first and second arm means. The holder controls the tracking control direction and A support beam that supports the lens holder to move in the focus control direction; first and second permanent magnets attached to respective side surfaces of the lens holder that are formed in parallel with the X-axis direction; First and second coils and a yoke component which are respectively arranged at intervals on the two permanent magnets, and which is opposite to the support beam in a Y-axis direction orthogonal to the X-axis direction and the Z-axis direction. A cutout is formed in a part of the lower side of the first permanent magnet, and the coil and the yoke component facing the permanent magnet have cutouts having substantially similar shapes at positions facing the cutout. An optical head device, wherein a notch is formed, and an optical path is provided in the notch. 2. The optical head device according to claim 1, wherein the coil and the yoke component drive the lens holder in a focus direction (Z-axis direction). 3. The optical head device according to claim 1, wherein the coil and the yoke component drive the lens holder in a focus direction and a tracking direction. 4. An escape portion below the first permanent magnet for guiding a light beam to a lens provided in the holder, and for guiding reflected light returning through the lens. 2. The optical path of claim 1, wherein
The optical head device as described in the above.