JP2000357340A - Optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and small-sized optical head device in which a laser unit has excellent adjustment precision and adjustment degree of freedom while ensuring satisfactory heat radiation property. SOLUTION: A graphite sheet 102 of flexible material of which only both end parts are contact-fixed on an optical case 111 is allowed to have deflection in the parts other than the part which is crimped and fixed by a thermal conductive member 103. Thereby, while the graphite sheet 102 is fixed on the optical case 111 in both end parts thereof, the part thereof which is crimped and fixed with a thermal conductive member 103 is integrated with the laser unit 101 to become smoothly movable without load. Furthermore, the graphite sheet makes it possible to perform the position adjustment in the X-Y plane of the laser unit 101 with excellent adjustment precision and, because of the large adjustment degree of freedom, the adjustment of rotation, etc., in directions θX, θY and θZ is easily performed.

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 for optically recording or reading information on an information recording medium using a laser light source.

[0002]

2. Description of the Related Art FIG. 3 is a schematic view of a conventional optical head device. 301 is a laser light source, 302 is a collimating lens,
303 is a polarization beam splitter, 304 is a quarter-wave plate, 305 is a reflection mirror, 306 is an objective lens, and 307
Denotes an optical disk, 308 denotes a condenser lens, 309 denotes a photodetector, and 310 denotes an optical case. In this optical system, light traveling in the Z direction emitted from a laser light source 301 is converted into parallel light by a collimator lens 302 and enters a polarization beam splitter 303. Here, the light emitted from the laser light source 301 is linearly polarized light, and the light is transmitted with high efficiency in the polarization direction of the emitted light, and the light has a polarization direction perpendicular to the direction. In addition, a polarizing film having a characteristic of reflecting light with high efficiency is
3, the parallel light is transmitted through the polarizing beam splitter 303, passes through the quarter-wave plate 304, and is converted into circularly polarized light. The circularly polarized light is bent in the Y direction by the reflection mirror 305, condensed by the objective lens 306, and irradiated on the optical disc 307. The light reflected by the optical disk 307 passes through the objective lens 306 and is again reflected by the reflection mirror 305.
, And is converted from circularly polarized light to linearly polarized light by passing through the 波長 wavelength plate 304. At this time, since the polarization direction is a direction perpendicular to the polarization direction of the linearly polarized light from the laser light source, this reflected light is reflected by the polarizing film of the beam splitter 303 and bent in the X direction,
The light is condensed by the condenser lens 308 and enters the photodetector 309.

At present, there is an increasing demand for downsizing and cost reduction of an optical head device, and for that purpose, downsizing of an optical system is required. As a countermeasure, a method using a laser unit 400 as shown in FIG. 4 has been proposed. 401 is a laser light source, 402 is a photodetector, 403
Is a substrate of Si or the like, 404 is a resin package, 405 is a cover glass of the laser unit, 406 is an electrode on the substrate side, 407 is a terminal of the laser unit, and 407 is a terminal of the laser unit.
The laser light source 401 and the photodetector 402 are electrically connected to each other by a conductor 408. In addition, 40
Reference numeral 9 denotes a laser radiator for radiating heat generated by the laser light source and conducted from the electrode 406 to the outside.

FIG. 5 is a schematic view of an optical head device using a laser unit 400. As shown in FIG. As shown in FIG. 4, a laser light source 400 and a photodetector 402 are integrated and enclosed in a package such as resin. 504 is a collimating lens, 505 is a reflection mirror, 506 is an objective lens, 507 is an optical disk, and 509 is an optical case.
Reference numeral 508a denotes a polarization hologram, which is a １ ／ wavelength plate 508.
b. In this optical system, the light emitted from the laser light source 401 in the laser unit 400 in the Z direction enters the polarization hologram 508a. Here, the light emitted from the laser light source 401 and traveling in the Z direction is linearly polarized. Light is transmitted with high efficiency with respect to the polarization direction of the emitted light, has a polarization direction perpendicular to the direction, and diffracts and condenses with high efficiency with respect to light traveling in the -Z direction. Since the polarizing hologram 508a is provided with a polarizing film having such characteristics, light emitted from the laser light source 401 and traveling in the Z direction passes through the polarizing hologram 508a, passes through the quarter-wave plate 508b, and is converted into circularly polarized light. .
The circularly polarized light is converted into parallel light by a collimating lens 504, bent in the Y direction by a reflecting mirror 505, condensed by an objective lens 506, and irradiated on an optical disk 507. Further, the light reflected by the optical disk 507 passes through the objective lens 506, and is reflected by the reflecting mirror 505 in the -Z direction.
Direction, passing through the collimating lens 504,
The light is converted into linearly polarized light by passing through the 波長 wavelength plate 508b. At this time, since the polarization direction is a direction perpendicular to the polarization direction of the linearly polarized light from the laser light source 401, the light is diffracted and condensed by the polarization hologram 508 b and enters the photodetector 402. The optical system until the light emitted from the laser light source reaches the optical disk (forward path) and the optical system until the light reflected from the optical disk is guided to the photodetector provided adjacent to the laser light source (return path). The size of the optical system is reduced by sharing the same.

FIG. 6 shows the configuration of an optical head device having a laser radiation mechanism using a laser unit 400. FIG.
10 shows a cross-sectional view of the laser unit 400 along the XZ plane. Elements common to the drawings are denoted by the same reference numerals. Reference numeral 400 denotes a laser unit, 602 denotes a fin-shaped heat radiator made of a material having excellent thermal conductivity such as copper or aluminum, and 603 denotes a printed circuit board on which the laser unit 400 is mounted, and is mainly formed of resin. The printed circuit board 603 is fixed to the optical case 509 by a fixing screw 604.
Contact fixed. The radiator 602 is fixedly contacted with the laser radiator 602 provided in the laser unit 400 and is thermally coupled. At this time, according to FIG. 7, the heat generated by the laser light source 401 is
6. The structure is conducted to the heat radiator 602 through the laser heat radiator 409 and is radiated from the heat radiator 602 to the atmosphere.

[0006]

The life of a semiconductor laser, which is often used as a laser light source for an optical head device, is generally closely related to the junction temperature during use. As the temperature increases, the life exponentially decreases. Is known to be. Therefore, heat dissipation of the laser is a very important issue,
In the optical head device, a laser radiation mechanism is indispensable.

In an optical head device using the optical system shown in FIG. 3, a CAN type laser light source sealed in a metal package is generally used as the laser light source 301. Since the metal has excellent thermal conductivity, the heat generated by the laser light source 301 is radiated to the optical case 310 having a large heat capacity through the metal package by fixing the laser light source 301 to the optical case 310 in a contact manner. With this configuration, sufficient heat radiation is possible.

However, the laser unit 400 shown in FIG.
In the optical head device having the configuration shown in FIG. 5 by using the laser unit 400, the laser unit 400 is formed of resin.
Generally, resin has poor thermal conductivity, so that the laser unit 4
00 is directly contacted and fixed to the optical case 509 so that heat generated by the laser
A configuration in which heat is directly dissipated to the optical case 509 via the optical module 04 cannot be adopted. Therefore, as shown in FIG. 4, a laser radiator 409 is provided as a component of the laser unit 400 to radiate heat generated by the laser light source 401,
Further, by providing a fin-shaped heat radiator 602 on the back surface of the laser radiator 409 as shown in FIG. 7, the heat generated by the laser light source 401 is transmitted to the heat radiator 602 via the laser radiator 409, and It has a structure that dissipates heat more into the atmosphere. However, in order to increase the heat capacity of the heat radiator 602, its size must be made larger, and since the heat radiator 602 is configured to radiate heat to the atmosphere, there is a problem that heat radiation efficiency is low. In particular, when a high-power laser for recording is used, more efficient heat radiation is required, and the heat radiation structure as described above is not sufficient.

In FIG. 5, in order to obtain a desired reproduction signal from an information recording medium such as an optical disk, the signal is emitted from a laser light source 401, irradiated on an information recording medium 507, and reflected by the information recording medium 507. In addition, it is necessary to align the light that is diffracted and condensed by the polarization hologram 508 and enters the photodetector 402 with the photodetector 402, and that the precision thereof must be strictly controlled. In this case, it is necessary to adjust the positions of the laser light source 401 and the photodetector 402 while achieving sufficient adjustment accuracy on the XY plane. As described above, in the optical head device having the optical system shown in FIG.
Since the optical system 01 and the photodetector 402 are integrated and the optical system for the forward path and the return path are shared, the adjustment accuracy for the laser unit 400 is more strictly required.

However, according to FIG. 6, the laser unit 400 is formed integrally with a rigid printed circuit board 603 which is mainly made of resin and is fixed to the optical case 509 with fixing screws 604. , XY
When position adjustment on a plane is performed, the fixing screw 604 is loosely tightened to adjust in a semi-fixed state movable by an external force. At this time, the movable range of the laser unit 400 is narrow because it is integrated with the rigid printed board 603 and is fixed by the fixing screw 604.
Also, it is difficult to make fine adjustments due to the influence of frictional force. Therefore, in an optical head device having such a configuration,
It is necessary to increase the adjustment accuracy of polarization holograms other than the laser unit, and the number of adjustment points and components increases, which hinders miniaturization and cost reduction.

Further, with respect to these points, in order to increase the recording density of a recording information medium in the future, it is necessary to adjust the laser unit more strictly in order to obtain a high-quality reproduction signal. Further, in order to increase the output of a recording laser in the future, an improvement in laser radiation efficiency is required for an optical head device, and it is considered that requirements for adjustment accuracy and heat radiation of the laser unit will become more severe.

The present invention has been made in view of the above-mentioned problems, and has a configuration in which the laser unit can be easily adjusted with excellent accuracy, heat radiation can be secured, and the present invention is inexpensive. And to provide a smaller optical head device.

[0013]

In order to solve this problem, an optical head device according to the present invention comprises a laser light source, a photodetector, and a laser radiator for radiating heat generated by the laser light source. In the laser unit, a flexible material is used as a heat conductor for transmitting heat generated by the laser light source to the optical case.

[0014]

FIG. 1 is a schematic diagram of an optical head device using an example of an embodiment of the present invention. FIG. 2A is a cross-sectional view along the XZ plane of the laser unit in the first embodiment of the laser radiating mechanism having this configuration. 1 in FIG.
Reference numeral 01 denotes a laser unit, which is a laser light source 201, a photodetector 202, and a substrate 203 of Si or the like in FIG.
A resin package 204, a cover glass 205 of a laser unit, an electrode 206 on the substrate side, a terminal 207 of the laser unit, and a conductive wire 20 for electrically connecting the terminal 207 to the laser light source 201 or the photodetector 202.
8 and a laser radiator 209 for radiating heat generated by the laser light source and conducted from the electrode 206 to the outside. Reference numeral 102 denotes a heat conductive sheet made of a flexible material, particularly a graphite sheet. Reference numeral 103 denotes a member made of two or more members that sandwiches the graphite sheet 102 and is in contact with the laser radiator 209 provided in the laser unit, and is a heat conductive member made of a metal having excellent heat conductivity. , 103a, 10a of FIG.
3b. The graphite sheet 102 is fixed in contact with the optical case 111 by fixing screws 104. At this time, in order to increase the contact area between the graphite sheet 102 and the optical case 111, the fixing screws 10 are used.
4 between the graphite sheet 102 and the washer 21
0 may be pinched. 105 is a printed circuit board on which the laser unit is mounted. 106 is a collimating lens, 107 is a reflecting mirror, 108 is an objective lens, 109
Denotes an optical disk, and 111 denotes an optical case. Reference numeral 110a denotes a polarization hologram, which is integrated with the quarter-wave plate 110b. In this optical system, light emitted from the laser light source 201 in the laser unit 101 in the Z direction is
The light enters the polarization hologram 110a.
The light emitted from 01 is linearly polarized light, the light is transmitted with high efficiency in the polarization direction of the emitted light, has a polarization direction perpendicular to the direction, and travels in the -Z direction. Since the polarizing hologram 110a is provided with a polarizing film having a characteristic of diffracting and condensing light with high efficiency, light emitted from the laser light source 401 and traveling in the Z direction passes through the polarizing hologram 110a and / 4 wavelength plate 110
b and is converted into circularly polarized light. The circularly polarized light is converted into parallel light by a collimating lens 106,
The light is bent in the Y direction at 7, condensed by the objective lens 108, and irradiated on the optical disc 109. Further, the light reflected by the optical disk 109 passes through the objective lens 108,
The light is bent in the −Z direction by the reflection mirror 107, passes through the collimator lens 106, and is converted into linearly polarized light by passing through the 波長 wavelength plate 110 b. At this time, since the polarization direction is a direction perpendicular to the polarization direction of the linearly polarized light from the laser light source 201, the light is diffracted and condensed by the polarization hologram 110 a and is incident on the photodetector 202 of the laser unit 101.

According to FIG. 1, graphite sheet 102
Are fixed to the optical case 111 only at both end portions by a fixing screw 104, but the other portions except for the portion fixed and held by the heat conductive member 103 are bent. Since the graphite sheet 102 is a flexible material and has a flexure, both ends of the graphite sheet 102
While being fixed to the heat conductive member 103, the part is integrated with the laser unit 101 and smoothly moves without a load, and the position of the laser unit 101 on the XY plane can be adjusted with excellent adjustment accuracy. it can.

Further, referring to FIG.
The heat generated in the substrate electrode 204 and the laser radiator 20
9, through the heat conducting member 103, which is fixed in contact with the laser radiator 209,
From the graphite sheet 102 to the optical case 111. At this time, heat is radiated to the optical case having a large heat capacity, so that high heat radiation efficiency can be realized.

Next, a second embodiment of the laser radiation mechanism is shown in FIG.
b. This embodiment shows a laser radiation mechanism having a rotation adjusting function in the optical head device shown in FIG. 2B, the spherical member 200a has a convex curved surface, and is integrated with the laser unit 101 and the printed circuit board 105 on which the laser unit 101 is mounted.
It enables adjustment in the X, θY, and θZ directions. A hole 200 through which light emitted from the laser light source 201 passes.
b. At the time of adjustment, the laser unit 101 integrated with the spherical member 200a is pressed against the optical case 111 by a pressing spring or the like, together with the heat conductive member 103 and the heat conductive member made of the graphite sheet 102 fixed thereto. The adjustment is performed in a state of being pressed in the direction of arrow 20.

According to FIG. 2B, the heat generated by the laser light source 102 is transmitted through the substrate electrode 204 and the laser radiator 209 to the heat conductive member 103 fixedly in contact with the laser radiator 209, and further to the heat conductive member 103. From the graphite sheet 102 to the optical case 111. At this time, heat is radiated to the optical case having a large heat capacity, so that high heat radiation efficiency can be realized.

The graphite sheet 102 is fixed to the optical case 111 only at both ends by contacting the optical case 111 with fixing screws 104, but the other portions except for the portion held and fixed by the heat conducting member 103 have a bend. It is. The deflection causes the graphite sheet 102
Are the portions θX, θY, and θ of the portions that are fixedly held to the heat conducting member 103 while both end portions are fixed to the optical case 111.
The degree of freedom for rotation in the Z direction is extremely large. Here, in the portion of the optical case 111 having a concave curved surface,
The laser unit 101 integrated with the curved surface member 200a having a convex curved surface is combined with the laser unit 101 and the heat conductive member 1.
03. By pressing with a pressing spring or the like together with the heat conductor made of the graphite sheet 102, the laser unit 101 becomes movable integrally with the heat conductor. At this time, since the convex curved surface of the rotating member 200a is a convex curved surface centered on the emission point of the laser light source 201, in such a configuration, the emission point of the laser light source 201 is changed by tilting in the θX and θY directions. It is possible to change only the emission angle without moving the laser unit.
In FIG. 1, since the relative position between the laser emission point and the photodetector is substantially constant, the laser unit 101 rotates around the center of rotation of the laser unit 101, that is, around its optical axis.
Can be rotated in the θZ direction, so that the rotation adjustment makes it possible to adjust only the return optical system without affecting the outward optical system in the optical system as shown in FIG. . With the above configuration, the θX, θ of the laser unit 101, which was impossible with the conventional configuration,
Adjustment such as rotation in the Y and θZ directions is facilitated, and a large degree of freedom in adjustment can be realized.

Here, when the laser radiator 209 has a function as an electrode such as a laser or a photodetector or is electrically connected as shown in FIGS. 2A and 2B, the heat conductive sheet 102 and the laser radiator Since the substrate electrode 204 and the optical case 111 have the same potential via the body 209 and the heat conducting member 103, the function as an electrode cannot be realized. Therefore, as shown in FIGS. 2A and 2B, by laminating the insulating film 103c on the surface of the heat conductive member 103a on the side in contact with the surface of the laser heat radiator 209, the laser radiator 209 and the heat conductive member 103 are electrically connected. It becomes possible to separate. At this time, the heat conduction member 1
03 may be an insulating material.

[0021]

As described above, according to the present invention, by using a flexible material, the laser unit can be configured to have excellent adjustment accuracy and freedom of adjustment, and heat radiation can be ensured. It is possible to realize an optical head device corresponding to a higher density of a recording medium and a higher output of a laser.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical system and a laser radiation mechanism according to an embodiment of the present invention.

FIG. 2A is a cross-sectional view illustrating a laser radiating mechanism according to an embodiment of the present invention. FIG. 2B is a cross-sectional view illustrating a laser radiating mechanism according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a conventional optical system.

FIG. 4 is a cross-sectional view of a conventional laser unit.

FIG. 5 is a perspective view showing an example of a conventional optical system.

FIG. 6 is a perspective view showing an example of a conventional optical system.

FIG. 7 is a cross-sectional view showing an example of a conventional laser radiation mechanism.

[Explanation of symbols]

 Reference Signs List 101 laser unit 102 graphite sheet 103 heat conducting member 104 fixing screw 105 printed board 106 collimating lens 107 reflecting mirror 108 objective lens 109 optical disk 110a polarization hologram 110b quarter-wave plate 111 optical case 20 arrow indicating pressing direction 200a curved member 200b laser Light transmission hole 201 Laser light source 202 Photodetector 203 Substrate 204 Resin package 205 Cover glass 206 Electrode 207 Laser unit terminal 208 Conductor 209 Laser radiator 210 Washer 301 Laser light source 302 Collimating lens 303 Polarizing beam splitter 304 Quarter wave plate 305 Reflecting mirror 306 Objective lens 307 Optical disk 308 Condensing lens 309 Photodetector 310 Optical case 400 Laser unit 401 Laser light source 402 Photodetector 403 Substrate 404 Resin package 405 Cover glass 406 Electrode 407 Laser unit terminal 408 Conductor 409 Laser radiator 504 Collimating lens 505 Reflecting mirror 506 Objective lens 507 Optical disk 508a Polarization hologram 508b Quarter-wave plate 509 Optical case 602 Heat radiator 603 Printed circuit board 604 Fixing screw

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Asada 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoichi Saito 1006 Okadoma Kadoma City, Osaka Prefecture Matsushita Electric Industrial F Terms (reference) 5D119 AA01 AA33 AA40 FA02 FA31 MA09 5F073 AB21 AB25 AB27 AB29 BA05 FA02 FA13 FA24 FA30

Claims (3)

[Claims] 1. A laser unit comprising a laser light source, a photodetector, and a laser radiator for radiating heat generated by the laser light source, and condensing light from the laser light source on an information recording medium. An optical head device having an optical system that guides light reflected from the information recording medium to the photodetector, and an optical case in which the optical system is housed, wherein the optical head device contacts the laser radiator, An optical head device, wherein a heat conductor that conducts heat to the optical case is made of a flexible material. 2. The optical head device according to claim 1, wherein a graphite sheet is used as the flexible material. 3. The optical head according to claim 1, wherein, of the members constituting the heat conductor, a member or a surface of the member that contacts the surface of the laser radiator of the laser unit is made of an insulating material. apparatus.