Optical head

Details Optical head Optical head

1995-04-28

1997-02-04

Ben, Loha

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369 4412, 359820, 250216, G11B 700

Patent

active

056006195

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a small-sized and lightweight optical head (or optical pickup) of the type, in which a semiconductor laser, a light receiving device, an objective lens and so on are driven integrally, and more particularly to a structure for radiating heat generated by a semiconductor laser of an optical head, or to a cooling structure thereof. Incidentally, it is assumed that an optical head of the present invention is primarily of the type, in which information is recorded on or reproduced from an optical disk.


BACKGROUND ART

There has been a conventional optical head of such a type, in which a package of a semiconductor laser is exposed and is cooled by the wind pressure of wind due to the rotation of an optical disk as disclosed in Japanese Patent Public Disclosure No. 2-240839/1994 Official Gazette.
However, such a heat radiation technique employed in the conventional optical head is not effective for the following reasons. Namely, there is a limit to the area of the exposed package. Further, the semiconductor laser is very likely to collide with the optical disk, because it is necessary for utilizing the wind pressure of wind caused by the rotation of the optical disk to bring the semiconductor laser very close to the optical disk. Moreover, the wind caused by the rotation of the optical disk is weak in itself and thus has little effect on the heat radiation in the case of using a low revolution optical disk. Consequently, the conventional optical head has a problem in that the characteristics of a signal is degraded owing to heat produced in the semiconductor laser and a laser optical system. Furthermore, an optical head equipped with a high output semiconductor laser for the purpose of recording and reproducing information can not be developed. Additionally, practical uses of the conventional optical head have been limited to a read-only compact disk (CD) player.
The present invention is accomplished to eliminate the drawbacks of the conventional optical head.
Accordingly, a main object of the present invention is to obtain a heat-radiating and/or cooling structure which is more efficient by far than that of the conventional optical head, to avoid increase in weight of a movable part involved in such a heat radiation structure and to improve the control characteristics of an actuator.


DISCLOSURE OF THE INVENTION

1. An optical head of the present invention is an integrally-driven type optical head in which a laser optical system provided with a semiconductor laser and a light receiving device is mounted in a moving part of an actuator, and is characterized in that the moving part is constituted by uniting a heat radiator made of a high heat conductivity material with a heat insulator made of a low heat conductivity material, that the heat conduction bonding of the heat radiator to the semiconductor laser is performed and that a coil of the actuator is securely fixed to this heat radiator through the heat insulator. Thereby, heat generated from the semiconductor laser is transferred to the heat radiator and is then radiated from the surface of the heat radiator to the external space of the optical head. Further, in case where heat is generated by the coil when the actuator operates, the laser optical system can be prevented from being heated, because of the fact that the heat conductivity between the coil and the laser optical system is low.
2. In the optical head of the item 1, the heat radiator is a holder for holding the laser optical system. Thereby, the entire holder can be used as a heat radiator. This optical head excels in volumetric efficiency and can be miniaturized.
3. In the optical head of the item 1, the heat radiator is made of a lightweight metal such as a magnesium alloy or an aluminum alloy. Thereby, the moving part can be prevented from being increased.
4. In the optical head of the item 1, the heat insulator is made of a resin such as a plastic. Thereby, the coil is insulated from the heat radiator. Thus the laser optical system is never heated. Mo

REFERENCES:
patent: 5005162 (1991-04-01), Mitsumori et al.
patent: 5313333 (1994-05-01), O'Brien et al.
patent: 5396061 (1995-03-01), Taniguchi

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