JPH1027369A - Optical recording medium playback device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable high-speed access and achieve high-speed access in an optical recording medium reproducing apparatus that is compatible with a plurality of types of optical recording media having different formats. The heat radiation performance is improved without hindering the response to the problem. A mechanical deck and a plurality of optical systems having various optical components for irradiating an optical recording medium with laser light and receiving laser light reflected by the optical recording medium are provided. A part of the optical system was fixed to the mechanical deck and provided as a fixed part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium reproducing apparatus. More specifically, in an optical recording medium reproducing apparatus that is compatible with a plurality of types of optical recording media having different formats, high-speed access can be supported and high-speed access can not be supported. The technology relates to a technology that enhances the heat dissipation performance without using heat.

[0002]

2. Description of the Related Art Optical recording media include, for example, CDs (compact discs), DVDs (digital video discs), and CD-Rs (compact disc recordables), each of which has a different format. .

[0003] Therefore, there has been an increasing demand for the development of compatible devices capable of performing highly reliable reproduction of recorded signals recorded on optical recording media having the above-mentioned different formats. With the spread of recording media, the necessity thereof has become even higher.

[0005] As such compatible devices, devices shown in FIGS. 5 to 7 have been proposed.

[0005] A mechanical deck a is provided in the apparatus, and the mechanical deck a is configured so that its front end moves substantially up and down with its rear end serving as a rotation fulcrum b (see Figs. 5 and 6).

Guide shafts c and d are provided on the mechanical deck a, and a base body e is supported on the guide shafts c and d so as to be movable in a radial direction of an optical recording medium (not shown). Thereby, the movable section h including the base body e and the two pickup sections f and g provided on the base body e is moved in the radial direction of the optical recording medium (see FIG. 7). ).

The pickup unit f has a two-axis actuator i
And an optical block j.

A biaxial actuator i is provided on a base k provided on a base body e, and an objective lens l
Is supported. The optical block j includes a collimator lens m, a beam splitter n, a semiconductor laser o, and a detector p.

The pick-up unit g is a two-axis actuator q
And an optical block r.

A two-axis actuator q is provided on a base s provided on a base body d, and an objective lens t
Is supported. The optical block r is a so-called laser coupler, in which various optical components such as a beam splitter (not shown), a semiconductor laser, and a detector are integrated.

The pickup f corresponds to the format of the DVD and relates to the reproduction thereof. The pickup g corresponds to the format of the CD and relates to the reproduction. The pickups f and g are mounted on the apparatus. Is selectively driven in accordance with the selected DVD or CD.

[0012]

However, in the above-described apparatus, all of the two pickup units f and g, that is, the optical blocks j and r and the two-axis actuators i and q respectively corresponding thereto are all provided. It is provided on the base body e. Therefore, the base body e, the pickup unit f,
The movable part h provided with g becomes large and heavy, and it is difficult to cope with high-speed access.

In recent years, as a means for achieving high-density recording of an optical recording medium, it has been common practice to shorten the wavelength of laser light emitted from a light source (semiconductor laser). Therefore, the necessity of providing the device with sufficient heat radiation performance is increasing.

However, in the above-described apparatus, in order to secure a sufficient heat radiation area necessary for enhancing the heat radiation performance, the base body e must be enlarged.
The movable part h becomes large, which hinders the response to high-speed access.

An optical recording medium reproducing apparatus according to the present invention overcomes the above-mentioned problems and provides a high-speed optical recording medium reproducing apparatus which is compatible with a plurality of types of optical recording media having different formats. It is an object of the present invention to make it possible to cope with access and to enhance heat radiation performance without hindering correspondence to high-speed access.

[0016]

In order to solve the above-mentioned problems, an optical recording medium reproducing apparatus according to the present invention comprises a mechanical deck, a method of irradiating a laser beam to an optical recording medium, or a method of reflecting a laser beam on an optical recording medium. And a plurality of optical systems having various optical components for receiving the received laser light and the like, and a part of the optical systems is fixed to a mechanical deck and provided as a fixing portion.

Therefore, the movable portion that moves in the radial direction of the optical recording medium is reduced in size and weight, and a sufficient heat radiation area required for enhancing heat radiation performance can be secured in the mechanical deck. is there.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical recording medium reproducing apparatus of the present invention will be described below with reference to the embodiments shown in the accompanying drawings.

In each of the illustrated embodiments, the present invention is applied to a DVD.
This is applied to a device that is compatible with a CD and a CD.

In the following description, the downward direction in FIGS. 1 and 2 is referred to as forward, the upward direction as backward, the leftward direction as leftward, and the rightward direction as rightward. Give an explanation.

First, the first embodiment shown in FIG. 1 will be described.

A mechanical deck 2 is provided in a housing (not shown) of an optical recording medium reproducing apparatus (hereinafter simply referred to as an "apparatus") 1.
The mechanical deck 2 is rotated so that the front end moves up and down with the rear end as a fulcrum for chucking an optical recording medium described later.

In the apparatus 1, various optical components such as an objective lens, a semiconductor laser, a beam splitter, a collimator lens, and a detector, which will be described later, are provided as an optical system.

The mechanical deck 2 has a substantially rectangular shape that is slightly longer in the front-rear direction when viewed in a plane, and has a large moving space 2a formed in the center thereof for moving a movable portion described later.

A spindle motor 3 is arranged at the front end of the mechanical deck 2, and a spindle 3 a rotated by the rotation of the spindle motor 3 is provided above the spindle motor 3. Then, the optical recording medium (DV
D or CD) 4 is held by a spindle 3a and a chucking member (not shown) provided above the spindle 3a, and is rotated while being chucked.

The apparatus 1 has two pickup units 5, 6
The pickup unit 5 includes an optical block 7 and a biaxial actuator 9 supporting an objective lens 8, and the pickup unit 6 includes an optical block 10 and a biaxial actuator 12 supporting an objective lens 11. The pickup unit 5 corresponds to the DVD format and relates to the reproduction thereof. The pickup unit 6 corresponds to the CD format and relates to the reproduction. The pickup units 5 and 6 are mounted on the apparatus 1. The optical recording medium 4 is selectively driven in response to a DVD or a CD.

An optical block 7 for reproducing a DVD is fixed to an optical block arranging portion 2b provided so as to protrude downward substantially at the center of the rear end of the mechanical deck 2, and includes a semiconductor laser 13, a beam splitter 14, a detector, and the like. 15 and a collimator lens 16. The optical block 10 for reproducing a CD is a so-called laser coupler, which is provided on a base body to be described later, and includes a beam splitter (not shown),
Optical components such as a semiconductor laser and a detector are integrated.

The biaxial actuators 9 and 12 are fixed members 9a and 12a, respectively, and the movable members 9 supported by the fixed members 9a and 12a via link members 9b and 12b, respectively.
c, 12c, and the movable members 9c, 12c are movable in the focusing direction and the tracking direction with respect to the fixed members 9a, 12a. The movable members 9c and 12c are attached to the objective lenses 8 and 1 respectively.
1 is supported.

The guide shafts 17a and 17b are provided between the front end and the rear end of the mechanical deck 2 so as to be separated from each other.

The base body 18 is composed of a plate-shaped main portion 18a which is oblong in a plan view, and guided portions 18b and 18c provided at both right and left ends of the main portion 18a.

The base body 18 has guided portions 18b and 18c slidably supported by the guide shafts 17a and 17b, respectively, and is movable in the front-rear direction within the moving space 2a of the mechanical deck 2, that is,
The optical recording medium 4 is movable in the radial direction.
A long rack 19 in the front-rear direction is provided on the outer surface of the guided portion 18c located on the right side.

Bases 20 and 21 are provided on the base body 18, the biaxial actuator 9 for reproducing the DVD is disposed on the base 20 located on the right side, and on the base 21 located on the left side. Is a two-axis actuator 12 for reproducing the CD.
Is arranged. The biaxial actuators 9 and 12 are arranged on the bases 20 and 21 such that the objective lenses 8 and 11 supported by the actuators come close to each other.
Further, the optical block 10 for reproducing the CD, that is, the laser coupler is disposed at a position near the left end of the front end of the base body 18, and a start-up (not shown) is provided at a position directly below the objective lenses 8 and 11 on the base body 18. The mirror is located.

Then, the optical block 10 and the base 2
0, 21; two-axis actuators 9 and 12 arranged on the bases 20 and 21; two rising mirrors located below the objective lenses 8 and 11; and a base 18 which supports them. The unit 22 is configured.

A driving unit 23 is provided at the rear half of the right end of the mechanical deck 2, and the driving unit 23 is constituted by a motor 23a and a gear group 23b.

The motor 23a is arranged at the rear end of the mechanical deck 2, and the foremost gear of the gear group 23b arranged at the front of the motor 23a and the guided portion 18 of the base body 18 are arranged.
c is engaged with a rack 19 provided in the rack. A feed mechanism 24 is constituted by the guide shafts 17a and 17b, the guided portions 18b and 18c of the base body 18 supported by the guide shafts 17a and 17b, the rack 19, and the drive unit 23. The optical recording medium 4 is moved in the front-back direction, that is, in the radial direction of the optical recording medium 4.

When the optical recording medium 4, ie, DVD or CD, is mounted on the apparatus 1, for example, a read result of the ID (identification label) of the DVD or CD is obtained, and the reading is performed by a discriminating means (not shown). Optical recording medium 4 is DV
D or CD is determined, and the DVD playback pickup unit 5 or CD playback pickup unit 6 is selectively driven based on the determination signal generated by the determination.

At the time of reproducing a DVD, the pickup unit 5 for reproducing the DVD is driven as follows.

Laser light is emitted from the semiconductor laser 13 of the optical block 7 toward the beam splitter 14, and the laser light is reflected by the beam splitter 14 toward the collimator lens 16. The reflected laser light is converted into a parallel light beam by the collimator lens 16, and travels toward the objective lens 8 via a rising mirror positioned below the objective lens 8 of the biaxial actuator 9. The laser beam directed to the objective lens 8 is given a condensing property by the objective lens 8 and is located above the optical recording medium 4, that is, a DVD.
Recording surface.

At this time, the movable section 22 is moved from the front to the rear by the feed mechanism 24, whereby the biaxial actuator 9 is fed from the inner circumference to the outer circumference of the DVD.

At the same time, the movable member 9c of the biaxial actuator 9 is moved in the focusing direction and the tracking direction with respect to the fixed member 9a, so that the focus position of the laser beam and the spot position on the recording surface are determined. Adjustment,
That is, focusing adjustment and tracking adjustment are performed.

The laser beam applied to the recording surface of the DVD is reflected by the recording surface, passes through the objective lens 8 and the rising mirror again to the beam splitter 14, passes through the beam splitter 14, and is guided to the detector 15. A recording signal recorded on the DVD is read, and a reproduction signal corresponding to the recording signal is output to a reproduction circuit (not shown).
Is played.

At the same time, the detector 15 also reads a focusing error signal and a tracking error signal contained in the return light.

At the time of reproducing a CD, the pickup section 6 for reproducing the CD is driven as follows.

Laser light is emitted from the optical block 10, that is, the semiconductor laser of the laser coupler, and the laser light passes through a beam splitter or the like provided in the optical block 10 and further passes below the objective lens 11 of the biaxial actuator 12. Objective lens 1 via the rising mirror located on the side
Go to 1. The laser light directed to the objective lens 11 is given a condensing property by the objective lens 11 and reaches the optical recording medium 4 located above it, that is, the recording surface of the CD.

At this time, the movable section 22 is moved from the front to the rear by the feed mechanism 24, whereby the biaxial actuator 12 is fed from the inner circumference to the outer circumference of the CD.

At the same time, when the movable member 12c of the biaxial actuator 12 is moved in the focusing direction and the tracking direction with respect to the fixed member 12a, the focus position of the laser beam and the spot position on the recording surface are determined. Adjustment, that is, focusing adjustment and tracking adjustment are performed.

The laser light applied to the recording surface of the CD is reflected by the recording surface, passes through the objective lens 11 and the rising mirror again, goes to the beam splitter provided in the optical block 10, and passes through the beam splitter. The recording signal recorded on the CD is read by the detector, and a reproduction signal corresponding to the recording signal is output to a reproduction circuit (not shown) to reproduce the CD.

At the same time, the detector provided in the optical block 10 also reads a focusing error signal and a tracking error signal contained in the return light.

In the first embodiment, the pickup unit 5 and the pickup unit 6 for ensuring compatibility between DVD and CD are provided, and the optical block 7 of the pickup unit 5 for DVD reproduction is provided. Are fixed to the optical block arrangement portion 2b of the mechanical deck 2.

Therefore, the optical block 7 is not included in the movable section 22 constituted by the base body 18 and the like, and the movable section 22 is reduced in size and weight by that much, and the movable section 2
2 can be moved at high speed, and high-speed access can be handled.

The semiconductor laser 13 of the optical block 7
Even if the amount of heat generated from the semiconductor laser 13 is increased due to the shortening of the wavelength of the laser light emitted from the semiconductor laser 13 or the like, it is necessary to secure a sufficient heat radiation area necessary for enhancing the heat radiation performance. This may be performed by increasing the size of the optical block arrangement section 2b.

Therefore, it is possible to secure a sufficient heat radiation area without increasing the size of the movable section 22, and to improve the heat radiation performance without hindering the response to high-speed access.

In the first embodiment, the optical block 7 for reproducing a DVD is fixed to the optical block arranging portion of the mechanical deck 2. However, in addition to the optical block 7, the optical block 7 for reproducing a CD is shown. Optical block 10 is mounted on mechanical deck 2
May be fixed. In this case, the size and weight of the movable portion can be further reduced, and the movable portion can be moved at a higher speed.

Next, a second embodiment shown in FIG. 2 will be described.

The second embodiment differs from the first embodiment in that the DVD playback pickup unit and the CD playback pickup unit are shared, and the numerical aperture of the objective lens is different. Only the point that a correction mechanism for correcting the difference is provided is provided. Therefore, in the following description, only the differences between the second embodiment and the first embodiment will be described, and the first embodiment will be described. The same parts as those described in the example are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

A mechanical deck 2A is provided in the apparatus 1A. The mechanical deck 2A is rotated so that the front end moves up and down with the rear end serving as a fulcrum for chucking the optical recording medium 4. It has become.

The mechanical deck 2A is provided with one pickup unit 25. The pickup unit 25 is a two-axis actuator 2 supporting an optical block 26 and an objective lens 27.
8 is provided. The pickup unit 25 is driven at the time of reproducing any of the DVD and the CD mounted on the apparatus 1A.

The optical block 26 is fixed to an optical block arrangement portion 2d provided so as to protrude downward at a part slightly leftward from the center of the rear end of the mechanical deck 2A.
It comprises a semiconductor laser 29, a beam splitter 30, a detector 31, and a collimator lens 32, and a correction mechanism 33 for correcting the numerical aperture of the objective lens is provided in the optical block arrangement section 2d.

As a correction mechanism 33 for correcting the numerical aperture of the objective lens, an aperture switching mechanism has recently been proposed, and such a mechanism is adapted to the numerical aperture of the objective lens according to the type of the optical recording medium mounted. Is to be corrected.

The two-axis actuator 28 includes a fixed member 28
a and a movable side member 28c supported by the fixed side member 28a via a link member 28b.
c is movable in the focusing direction and the tracking direction with respect to the fixed side member 28a. The objective lens 27 is supported by the movable member 28c.

The base body 34 has a plate-shaped main portion 34a and guided portions 34b, 34 provided at both left and right ends of the main portion 34a.
The main portion 34a is made smaller than the main portion 18a of the base body 18 in the first embodiment described above.
8a is about half the size.

The base body 34 has guided portions 34b and 34c slidably supported by the guide shafts 17a and 17b, respectively, and is movable in the front-rear direction within the moving space 2a of the mechanical deck 2A. And the guided part 3 located on the right side
A rack 19 that is long in the front-rear direction is provided on the outer surface of 4c.

A base 35 is provided on the base body 34,
The biaxial actuator 28 is disposed on the base 35. Then, the objective lens 27 in the base body 34
A rising mirror (not shown) is arranged at a position directly below the mirror.

The optical block 26 and the base 35
The movable part 36 is constituted by the two-axis actuator 28 disposed on the base 35, the rising mirror positioned below the objective lens 27, and the base body 34 supporting these.

The guide shafts 17a and 17b, the guide shaft 1
Guided portion 34 of base body 34 supported by 7a, 17b
The feed mechanism 37 is constituted by b, 34c, the rack 19 and the drive unit 23, and the movable unit 36 is moved in the radial direction of the optical recording medium 4 by the feed mechanism 37.

When the DVD or CD is mounted on the apparatus 1A, the pickup unit 2 for reproducing the DVD and CD is read.
5 is driven as follows.

When a DVD or CD is mounted on the apparatus 1, for example, a read result of the ID of the DVD or CD is obtained.
Optical recording medium 4 mounted by discrimination means (not shown)
Is a DVD or a CD. And DV
Based on the discrimination signal generated by discriminating that the disc is D or CD, the above-described correction mechanism 33 corrects the numerical aperture of the objective lens 27 so as to correspond to DVD or CD.

A laser beam is emitted from the semiconductor laser 29 of the optical block 26 toward the beam splitter 30, and the laser beam is emitted from the beam splitter 30-collimator lens 32-start-up mirror-objective lens as in the first embodiment. 27, the optical recording medium 4, ie,
It reaches the recording surface of DVD or CD.

Then, at this time, the movable portion 36 is moved by the feed mechanism 37, whereby the biaxial actuator 2 is moved.
8 is sent from the inner peripheral side to the outer peripheral side of the optical recording medium 4, and at the same time, focusing adjustment and tracking adjustment by the two-axis actuator 28 are performed.

The laser light applied to the recording surface of the DVD or CD is reflected by the recording surface and is guided to the detector 31 through the path of the objective lens 27, the rising mirror, the collimator lens 32, and the beam splitter 30, and is guided to the DVD or CD.
The recording signal recorded in D is read, and a reproduction signal corresponding to the recording signal is output to a reproduction circuit (not shown) and
VD or CD reproduction is performed.

At the same time, the detector 31 also reads a focusing error signal and a tracking error signal contained in the return light.

In the second embodiment, the correction mechanism 33 for correcting the numerical aperture of the objective lens is provided, so that the pickup unit 25 for DVD and CD reproduction is shared, and the pickup unit 25 is used. The optical block 26 is fixed to the optical block arrangement portion 2d of the mechanical deck 2A.

Accordingly, the size and weight of the movable portion 36 can be further reduced as compared with the first embodiment, and the movable portion 36 can be moved at a high speed, thereby making it possible to cope with high-speed access.

As in the case of the first embodiment, a sufficient heat radiation area necessary for enhancing the heat radiation performance can be obtained by enlarging the optical block arrangement portion 2d of the mechanical deck 2A. A sufficient heat radiation area can be ensured without increasing the size of 36, and the heat radiation performance can be improved without hindering the response to high-speed access.

The optical block 7 shown in the first embodiment and the optical block 26 shown in the second embodiment are both a rear end of the mechanical deck 2 or 2A,
That is, it is fixed to the optical block arrangement portion 2b or 2d provided at a position close to the rotation fulcrum 2c of the mechanical deck 2 or 2A (see FIGS. 3 and 4).

Here, in the case where the optical blocks j and r are included in the movable part h located at a position distant from the rotation fulcrum b as in the conventional apparatus shown in FIGS. 5 and 6,
The movable part h must be enlarged accordingly, and in order to prevent the movable part h from contacting the circuit board u positioned below when the mechanical deck a rotates, the mechanical deck a and the circuit board u
(H2 shown in FIG. 5) must be increased.

However, in the optical recording medium reproducing apparatus of the present invention, as described above, the optical block 7 or 26 is provided at a position close to the rotation fulcrum 2c of the mechanical deck 2 or 2A. 22 or 36 is miniaturized, and the circuit board 38 located below and the mechanical deck 2 or 2
The interval between the two devices (A, H1 shown in FIG. 3) can be made smaller than that of the conventional device.

Therefore, the height of the device 1 or 1A can be reduced, which contributes to the thinning of the device 1 or 1A.

In each of the above-described embodiments, the present invention is applied to a DV.
The case where the present invention is applied to an apparatus having compatibility with D and CD is shown, but the present invention is not limited to this. It can also be applied to a device in which the performance is ensured.

[0080]

As is apparent from the above description, the optical recording medium reproducing apparatus of the present invention comprises a mechanical deck,
A plurality of optical systems having various optical components for irradiating the optical recording medium with laser light and receiving laser light reflected by the optical recording medium, and fixing a part of the optical system to a mechanical deck Since the movable portion moving in the radial direction of the optical recording medium is reduced in size and weight,
The movable part can be moved at high speed, and it is possible to cope with high-speed access.

Further, it is sufficient to secure a sufficient heat radiation area necessary for enhancing the heat radiation performance in the mechanical deck, and it is possible to secure a sufficient heat radiation area without increasing the size of the movable portion, and to achieve high-speed access. The heat radiation performance can be improved without hindering the response to the above.

According to a fifth aspect of the present invention, there is provided a mechanical deck, a semiconductor laser for emitting a laser beam toward an optical recording medium, and a laser beam for reflecting the laser beam emitted from the semiconductor laser. An optical block including a beam splitter that transmits the laser light reflected by the optical disc, a collimator lens that converts the emitted laser light into a parallel light beam, and a detector that receives return light transmitted through the beam splitter, and an objective lens. A two-axis actuator, a base body for supporting the two-axis actuator, and a feed mechanism for moving the base body in the radial direction of the optical recording medium, and the optical block is fixed to a mechanical deck and provided as a fixing part. The fixing unit corrects the numerical aperture of the objective lens according to the type of the optical recording medium mounted on the apparatus. Is provided with the structure, further miniaturization of the movable unit, a small weight is attained, it is possible to move the movable unit at a high speed, it is possible to respond to high-speed access.

Further, claim 3, claim 4, and claim 6
According to the invention described in the above, since the other end of the mechanical deck moves substantially up and down with one end of the mechanical deck serving as a rotation fulcrum, and a fixed portion, which is an optical block fixed to the mechanical deck, is provided at one end of the mechanical deck. Height can be reduced, which contributes to making the device thinner.

The shape and structure of each part shown in each of the above-described embodiments are merely examples of the embodiment of the present invention, and the technical scope of the present invention is not limited thereto. Should not be construed as limiting.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an optical recording medium reproducing apparatus of the present invention, and is a schematic plan view of the apparatus.

FIG. 2 shows a second embodiment of the optical recording medium reproducing apparatus of the present invention, and is a schematic plan view of the apparatus.

3 shows the distance between the mechanical deck and the circuit board required for the optical recording medium reproducing apparatus of the present invention together with FIG. 4, and shows a state where the mechanical deck is located at the upper moving end. It is a side view which shows notionally.

FIG. 4 is a side view conceptually showing a state where the mechanical deck is located at a lower moving end.

FIG. 5 shows the distance between the mechanical deck and the circuit board required for the conventional apparatus together with FIG. 6, and FIG. 5 is a side view conceptually showing a state where the mechanical deck is located at the upper moving end. FIG.

FIG. 6 is a side view conceptually showing a state where the mechanical deck is located at a lower moving end.

FIG. 7 is an enlarged schematic plan view showing a part of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical recording medium reproducing apparatus, 1A ... Optical recording medium reproducing apparatus, 2 ... Mechanical deck, 2A ... Mechanical deck, 2c ... Rotating fulcrum, 4 ... Optical recording medium, 7 ... Optical block, 8 ...
Objective lens, 9: biaxial actuator, 10: optical block, 11: objective lens, 12: biaxial actuator,
13 ... semiconductor laser, 14 ... beam splitter, 15 ...
Detector, 16: Collimator lens, 18: Base body, 24: Feed mechanism, 26: Optical block, 27: Objective lens, 28: Biaxial actuator, 29: Semiconductor laser, 30: Beam splitter, 31: Detector, 32
... Collimator lens, 33 ... Correction mechanism, 34 ... Base body, 37 ... Feed mechanism

Claims (6)

[Claims] 1. An optical recording medium reproducing apparatus capable of reproducing a plurality of types of optical recording media having different formats, comprising: a mechanical deck; irradiating a laser beam onto the optical recording medium; A plurality of optical systems having various optical components for receiving a laser beam reflected by the medium, etc., and a part of the optical system is fixed to a mechanical deck and provided as a fixing portion. Recording medium playback device. 2. The optical system includes an objective lens and an optical block. The optical block reflects a semiconductor laser that emits laser light toward an optical recording medium, and reflects the laser light emitted from the semiconductor laser. A beam splitter that transmits the laser light reflected by the optical recording medium, and a collimator lens that converts the emitted laser light into a parallel light beam,
A plurality of biaxial actuators each having a detector for receiving return light transmitted through the beam splitter, supporting an objective lens, and respectively corresponding to a plurality of optical blocks; and a base supporting the plurality of biaxial actuators The optical system according to claim 1, further comprising a body, and a feed mechanism for moving the base body in a radial direction of the optical recording medium, wherein at least one of the optical blocks is provided as a fixed part. Recording medium playback device. 3. The mechanical deck according to claim 1, wherein the other end of the mechanical deck moves substantially up and down with one end of the mechanical deck serving as a rotation fulcrum, and the fixed portion is provided on one end of the mechanical deck. Optical recording medium playback device. 4. The mechanical deck according to claim 2, wherein the other end of the mechanical deck moves substantially up and down with one end of the mechanical deck serving as a pivot point, and the fixed portion is provided at one end of the mechanical deck. Optical recording medium playback device. 5. An optical recording medium reproducing apparatus capable of reproducing a plurality of types of optical recording media having different formats, comprising: a mechanical deck; and a semiconductor laser for emitting a laser beam toward the optical recording medium. A beam splitter that reflects the laser light emitted from the semiconductor laser and transmits the laser light reflected by the optical recording medium, a collimator lens that converts the emitted laser light into a parallel light beam, and a beam splitter. An optical block having a detector for receiving the transmitted return light; a biaxial actuator for supporting the objective lens; a base for supporting the biaxial actuator; and moving the base in a radial direction of the optical recording medium. A feed mechanism, and the optical block is fixed to a mechanical deck and provided as a fixed portion, and the fixed portion is attached to the device. Optical recording medium reproducing apparatus characterized in that a correction mechanism for correcting the numerical aperture of the objective lens according to the type of the optical recording medium. 6. The mechanical deck according to claim 5, wherein the other end of the mechanical deck moves substantially up and down with one end of the mechanical deck serving as a rotation fulcrum, and the fixed portion is provided at one end of the mechanical deck. Optical recording medium playback device.