JPH08287499A - Objective lens driving device - Google Patents

Abstract

PURPOSE: To provide a device provided with a cooling means of a semiconductor laser (LD) for improving deterioration in the life due to the heat of the LD in an objective lens driving device utilizing a whole optical system driving method, and also provided with an improved wiring structure. CONSTITUTION: The optical system consisting of the LD 1, photodetector(PD) 2, holographic optical element 3, λ/4 plate 4, deflecting prism 5 and objective lens 6, is provided in a bobbin 10 of a movable part, and the information of a recording medium 20 is recorded and reproduced by driving the movable part with a signal from the PD 2 and controlling the objective lens 6. The heat generated in the LD 1 is radiated from a radiating plate 11 which is molded integrally with the bobbin 10 of movable part, thereby the life of the LD is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens drive device for enabling focus and tracking control of an objective lens which is an element of an optical pickup of an optical disc drive device such as a CD player or a magneto-optical disc drive.

[0002]

2. Description of the Related Art As a conventional technique relating to focus and tracking of an optical pickup of an optical disc drive device, "Jpn. J. Appl. Phys. Vol.31 (1992) Pt.1, N.
o.2B ”pp.542-543 are known.
Here, after a light beam from a semiconductor laser is made to act on a hologram, a minute spot is made into a minute spot by an objective lens and irradiated onto an optical disk, and reflected light from the spot is again made to the objective lens,
A pickup optical system that enters the split light receiving element through the hologram and the optical system are provided in a bobbin of the movable portion of the driving device, and the movable portion of the driving device is driven by using a difference signal obtained by the split light receiving element. However, an overall optical system type objective lens driving device for performing focus and tracking control of the objective lens is shown.

[0003]

In recent years, in an optical disk drive device, high-speed recording / reproduction is required, and high output of a semiconductor laser (LD) is required. However, when the output of the LD is increased, the amount of heat generated by the LD increases. When the LD is mounted in the movable portion bobbin as disclosed in the above-mentioned document as a conventional technique, the heat generated from the LD is less likely to be released from the bobbin, and the temperature of the LD rises. It is predicted that the LD has a very short life when the environmental temperature is high, and the reliability of the drive is significantly lowered. In addition, since the coils for focusing and tracking provided in the optical system housing are also compatible with the speedup, heat generation is considerably increased as compared with the conventional case. Therefore, the temperature of the optical system housing becomes considerably high, and the environmental temperature of the LD becomes even more severe.

An object of the present invention is to provide a means for effectively cooling an LD in order to improve the above-mentioned short life of the LD, which is a problem in the objective lens driving device for driving the entire optical system. Further, it is an object of the present invention to make the power supply of the lens driving device and the wiring of the signal line have a structure suitable for the operation of the device so as to improve the efficiency of the wiring work.

[0005]

In order to solve the above-mentioned problems, the present invention narrows a light beam from a light source such as a semiconductor laser into a minute spot with an objective lens and irradiates the recording medium with reflected light from the recording medium. Has a pickup optical system component which is incident on a divided light receiving element in a movable portion of a drive device of an optical information recording / reproducing device, and drives the driving device by using a difference signal obtained by the divided light receiving element, and the objective lens In the objective lens drive device for driving the optical system as a whole, which performs the focus control and the tracking control of (1), the movable part has a bobbin accommodating the optical system and a heat dissipation plate integrally formed with the bobbin, The semiconductor laser and the divided light receiving element are integrally provided on the heat dissipation plate, or (2) the movable part has a cooling duct, and the duct is the upper surface of the movable part. Open Oite air inlet is opposite to the rotational direction of said recording medium, and the air passage is disposed in the vicinity of the semiconductor laser, or,
(3) The movable part has a hole vertically passing through the movable part, and the hole is formed of a member having a heat dissipation effect and has a spiral fin inside, and the member having the heat dissipation effect is a semiconductor. It is provided integrally with a laser, and further, in (1) above, (4) has an objective lens driving device base member below the movable part, and the radiator plate of the movable part and the objective lens driving device. The base member is connected with a film or a linear member having high heat transfer efficiency, and a damper member is integrally formed with the film or the linear member, or (5) the movable portion bobbin is held. A plurality of elastic support members, each elastic support member having at least two conductive wire members in close proximity and in parallel as one set; these conductive wire members are integrally molded by an insulating damper member; Consists of the above Of wire materials, several were the feed line to the focusing and tracking coils, and the other semiconductor laser,
It is characterized in that a signal line and a ground line to the light receiving element are used.

[0006]

According to the invention of claim 1, the amount of heat generated by the semiconductor laser is radiated by the heat radiating plate provided integrally with the semiconductor laser, so that the life of the semiconductor laser can be extended, and further, Since the heat dissipation plate is integrally molded with the bobbin mold so as not to reduce the rigidity of the bobbin,
It does not adversely affect the control operation of the movable part.

According to the second aspect of the present invention, the duct from which heat from the semiconductor laser generated in the movable portion bobbin takes in the air flow generated by the rotation of the recording medium and which has an air flow passage near the semiconductor laser. Since the heat is radiated through the semiconductor laser, the temperature of the semiconductor laser does not rise.

According to the third aspect of the present invention, the heat generated from the semiconductor laser in the movable portion bobbin is radiated through the air flow generated in the heat radiation hole vertically penetrating the movable portion. The laser never heats up.

According to the invention of claim 4, the heat generated from the semiconductor laser in the movable portion bobbin is radiated to the drive device base member having a large heat capacity through the member having a high heat conduction efficiency, which is more effective. Since heat is dissipated in the film, and the member having high heat conduction efficiency is formed into a film or a linear shape, and the damper member is formed integrally with this,
The movable part is isolated from vibration.

Further, according to the invention of claim 5, it is possible to supply power to the movable part by using the elastic supporting member, which facilitates the work of wiring the power supply line, the signal line and the ground line to the movable part. Since there is no wiring from the movable portion, resonance that causes an unnecessary effect on drive control of the movable portion does not occur.

[0011]

EXAMPLE FIG. 1 is a sectional view of a movable part for explaining an example of the objective lens driving device according to claim 1.
In the bobbin 10 of the movable portion, recording / reproducing optical system parts, that is, a semiconductor laser (LD) 1 and a light receiving element (PD).
2, an optical system including a HOE (holographic optical element) 3, a λ / 4 plate 4, a deflecting prism 5, an objective lens 6 and the like is housed. Here, in order to increase the recording / reproducing speed, the number of rotations of the recording medium 20 is increased, but with this, it is necessary to increase the output of the semiconductor laser (LD) 1. Therefore, the heat generated from the LD 1 is also high. Become. Further, for high-speed recording and reproduction, by increasing the number of rotations of the recording medium 20, the surface runout acceleration and the eccentric acceleration of the recording medium 20 also increase, and accordingly, the amount of heat generated from the coil 7 that drives the movable portion. Therefore, the heat applied to the LD1 is further increased. Therefore, the heat dissipation plate 11 for cooling the LD 1 is provided. The cooling radiation plate 11 is directly provided with the light receiving element (PD) 2 together with the LD 1. The heat dissipation plate 11 is formed integrally with the mold of the bobbin 10 of the movable part. With such a structure, the heat radiation effect of the LD 1 can be improved. Further, since the bobbin 10 and the heat dissipation plate 11 are integrally molded, the bobbin 10 and the heat dissipation plate 11 have high adhesion, and the rigidity of the bobbin 10 does not decrease. In addition, the heat sink 11
Since the LD1 and PD3 are directly provided in the above, these fixing members are not required, the weight of the movable portion can be reduced, and heat generation from the movable portion driving coil 7 can be reduced.

FIG. 2 is a modified block diagram of the embodiment shown in FIG. 1, in which the heat dissipation plate 11 is provided with fins 11a. During recording and reproduction, the recording medium 20 rotates, but this rotation causes an air flow on the surface of the recording medium 20. Therefore, the heat generated from the LD 1 can be effectively cooled by the fins 11 a provided on the heat dissipation plate 11.

FIG. 3 is a sectional view (a) of a movable part and a top view (b) of a main part for explaining an embodiment of the objective lens driving device according to the second aspect, which is different from the embodiment shown in FIG. Similarly, an optical system component for recording / reproducing is provided in the bobbin 10. The present invention utilizes the airflow generated by the rotation of the recording medium 20, and therefore the duct 12 is provided. The duct 12 is composed of a member having a high heat transfer coefficient (aluminum or the like), and the air intake 12a is opposed to the rotation direction of the recording medium 20 on the upper surface of the movable portion so that the air flow passage passes near the semiconductor laser 1. The LD 1 is cooled by radiating the heat from the semiconductor laser 1 to the airflow flowing through the flow passage. With such a configuration, the weight of the movable portion can be reduced and the airflow can be more efficiently guided to the vicinity of the LD 1 as compared with the case where the heat dissipation plate 11 of FIGS. 1 and 2 is used. It is possible to increase the cooling efficiency. Further, the weight of the movable portion can be reduced and the load on the coil can be reduced, so that the amount of heat generated can be reduced.

FIG. 4 is a sectional view of a movable portion for explaining an embodiment of the objective lens driving device according to the third aspect of the present invention. Like the above-described embodiment, the bobbin 10 of the movable portion has an optical element for recording and reproducing. System parts are provided. Here, a hole 13a is provided which vertically penetrates the bobbin 10 of the movable part. This hole 13a is formed by a member 13 having a heat dissipation effect,
Moreover, a spiral fin 13b is formed in the hole 13a, and the LD 1 is provided integrally with the heat dissipation member 13. In such a configuration, when the recording medium 20 causes surface wobbling in the vertical direction (focus direction) due to rotation, the movable portion of the objective lens driving device is also driven in the vertical direction in synchronization with the surface wobbling. Therefore, the spiral fin 13b in the hole 13a causes a flow of air to cool the LD 1.
Moreover, on the upper surface of the movable portion, a negative pressure is generated by the air flow due to the rotation of the recording medium 20, so that the air flow is generated in the hole 13a and the LD1
Can be cooled. Further, as in the above-described embodiment, the size and weight of the movable portion can be reduced, so that the load on the coil can be reduced and the heat generated from the coil can be reduced.
It is possible to extend the life of the.

FIG. 5 is a sectional view for explaining an embodiment of the objective lens driving device according to the present invention. In this embodiment, a pick-up is made in a bobbin 10 in which a heat dissipation plate 11 provided with an LD 1 is integrally molded. While providing optical system parts,
A film-shaped or linear (a bundle of wire rods) heat-dissipating member 14 is provided in contact with the heat-dissipating plate 11 on the lower surface of the movable portion, and a damper member 15 is integrally provided on the heat-dissipating member 14, and one end thereof is an objective lens driving device It is locked to the base 30. With such a configuration, the heat generated in the LD 1 can be radiated to the objective lens driving device base 30 part, so that it is not necessary to provide a heat radiating member in many parts of the movable part as in the above-described embodiment, and the weight of the movable part is reduced. The weight can be further reduced, and the amount of heat generated from the LD 1 can be reduced. In addition, the objective lens driving device base 3
Since the volume of 0 is large, it is possible to enhance the heat dissipation effect. A damper 15 is provided on the film-shaped or linear heat-dissipating member 14, and it is possible to reduce the resonance peak amount of the focus and track systems.

FIG. 6 is a sectional view (b) and a top view of a main part (a) for explaining an embodiment of the objective lens driving device according to the fifth aspect of the present invention. The bobbin 10 has a system component and is supported by a plurality of elastic support members 16. Each of the elastic supporting members 16 has at least two conductive wire rods 1 in close proximity to each other.
6a and 16b are provided in parallel, and these are set as one set and integrally molded by an insulating damper member 16. Some of the conductive wire members are used as power supply lines to the focus and track coils, and others are used as semiconductor lasers, signal lines to the light receiving element, and ground lines. With such a configuration, the elastic support member 16 can be used to supply power to the drive coil 7 of the movable portion, and the elastic support member 16 can be used as the signal line and the ground line of the LD1 and PD2. Wiring from the moving part is not required, improving the workability of assembly. Further, since there is no wiring from the movable portion, unnecessary resonance does not occur when the movable portion is driven, so stable servo control is possible and drive reliability can be improved.

[0017]

Since the present invention is constructed as described above, the following effects are brought about. Effect corresponding to claim 1: In the objective lens driving device of the whole optical system driving type, by increasing the heat radiation effect of the LD, L
The life of D can be extended. In addition, the reliability of the drive can be improved because the weight of the movable portion can be reduced as compared with the conventional device without lowering the rigidity of the bobbin of the movable portion. Effect corresponding to claim 2: The airflow generated by the rotation of the recording medium can be taken into the duct to forcibly dissipate the heat, so that the semiconductor laser can be effectively cooled, and the movable part can be made smaller and lighter. By reducing the heat generation of the drive coil, the life of the semiconductor laser can be extended. Effect corresponding to claim 3: Since the movable part of the objective lens driving device moves in the focus direction in synchronization with the surface wobbling due to the rotation of the recording medium, an air flow is generated in the hole for heat dissipation,
The semiconductor laser can be effectively cooled by radiating heat forcibly. Further, since the heat generation of the drive coil is reduced by reducing the size and weight of the movable portion, the life of the semiconductor laser can be extended. Effect corresponding to claim 4: The cooling capacity in the heat radiating portion can be increased, and more effective cooling can be achieved. Further, as compared with the inventions according to claims 1 to 3, the number of heat radiating members in the movable part is small and the weight can be reduced, and the heat generation of the drive coil can be reduced.
Therefore, the life of the semiconductor laser can be extended. Further, since the damper is provided, the vibration damping effect can be enhanced, and the reliability of the drive against disturbance vibration can be enhanced. Effect corresponding to claim 5: Like the invention of claim 1, L
The life of D can be extended. Further, since there is no wiring from the movable portion, unnecessary resonance does not occur when the movable portion is driven, so stable servo control is possible and drive reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a movable part of an embodiment of an objective lens driving device according to the present invention.

FIG. 2 is a sectional view of a movable part of another embodiment of the objective lens driving device according to the present invention.

FIG. 3 is a sectional view of a movable part and a top view of a main part of another embodiment of the objective lens driving device according to the present invention.

FIG. 4 is a sectional view of a movable part of another embodiment of the objective lens driving device according to the present invention.

FIG. 5 is a sectional view of another embodiment of the objective lens driving device according to the present invention.

6A and 6B are a sectional view and a top view of a main part of another embodiment of the objective lens driving device according to the present invention.

[Explanation of symbols]

1 ... Semiconductor laser (LD), 2 ... Light receiving element (PD), 3
... HOE, 4 ... λ / 4 plate, 5 ... Prism, 6 ... Objective lens, 10 ... Bobbin, 11 ... Heat sink, 12 ... Duct, 13
... Hole member, 14 ... Heat dissipation member, 15 ... Damper member, 16
... elastic support member, 20 recording medium, 30 objective lens drive device base.

Claims (5)

[Claims] 1. A pickup optical system component for optical information recording, wherein a light beam from a light source such as a semiconductor laser is focused into a minute spot by an objective lens to irradiate the recording medium, and reflected light from the recording medium is incident on a divided light receiving element. The whole optical system drive type objective lens drive which has a movable part of the drive device of the reproducing device, drives the drive device by using a difference signal obtained by the divided light receiving element, and performs focus control and tracking control of the objective lens In the apparatus, the movable part has a bobbin that accommodates the optical system, a heat dissipation plate integrally formed with the bobbin, and the semiconductor laser and the split light receiving element are integrally provided on the heat dissipation plate. Characteristic objective lens drive device. 2. A pickup optical system part for recording a light beam from a light source such as a semiconductor laser into a minute spot by an objective lens to irradiate the recording medium, and reflecting light from the recording medium to split light receiving elements. The whole optical system drive type objective lens drive which has a movable part of the drive device of the reproducing device, drives the drive device by using a difference signal obtained by the divided light receiving element, and performs focus control and tracking control of the objective lens In the apparatus, the movable part has a cooling duct, and the duct has an air intake opening on the upper surface of the movable part facing in the direction of rotation of the recording medium, and an air flow path of the semiconductor laser. An objective lens driving device, which is arranged in the vicinity. 3. A pickup optical system part for recording a light beam from a light source such as a semiconductor laser into a minute spot by an objective lens to irradiate the recording medium, and reflecting light from the recording medium to a split light receiving element for optical information recording. The whole optical system drive type objective lens drive which has a movable part of the drive device of the reproducing device, drives the drive device by using a difference signal obtained by the divided light receiving element, and performs focus control and tracking control of the objective lens In the device, the movable part has a hole vertically passing through the movable part, the hole is formed of a member having a heat dissipation effect, and has a spiral fin inside, and the member having the heat dissipation effect is a semiconductor. An objective lens driving device characterized by being provided integrally with a laser. 4. The film according to claim 1, further comprising an objective lens driving device base member below the movable portion, wherein the heat dissipation plate of the movable portion and the objective lens driving device base member have high heat transfer efficiency. An objective lens driving device characterized in that a damper member is integrally formed with the film or the linear member, the damper member being connected with the linear member. 5. The elastic support member according to claim 1, further comprising a plurality of elastic supporting members for holding the movable portion bobbin, wherein each of the elastic supporting members is a set of at least two conductive wires closely arranged in parallel. These conductive wire members are integrally molded with an insulating damper member, some of the conductive wire members are power supply lines to the focus and track coils, and the others are semiconductor lasers and signal lines to the light receiving element. Also, an objective lens driving device characterized by using a ground wire.