Optical recording/reproducing apparatus including both automatic

Details Optical recording/reproducing apparatus including both automatic Optical recording/reproducing apparatus including both automatic

1991-11-04

1993-08-03

Dzierzynski, Paul M.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369121, 369122, G11B 7125

Patent

active

052335968

ABSTRACT:
An optical recording/reproducing apparatus comprises a semiconductor laser, and a drive circuit for supplying a drive current to the semiconductor laser. A light beam from the semiconductor laser is converged on a recording medium through an objective lens. A photodiode for receiving the light beam is provided within the semiconductor laser. A monitor output from the photodiode is input to an APC circuit. The APC circuit includes a reference value generator and an error detector circuit. The error detector circuit detects a difference between the monitor output and a reference value, and outputs a control signal for controlling the drive circuit so as to keep the monitor output constant. The APC circuit is turned on/off by a controller. With the APC circuit turned on, the controller detects the temperature or temperature variance of the on the basis of the drive current monitor signal from the drive circuit and the pre-stored data of the semiconductor laser with respect to temperatures. With the APC circuit turned off, the semiconductor laser is supplied with a constant drive current from the drive circuit. The value of the drive current is set by the controller on the basis of the temperature detected just before the APC circuit is turned off and the pre-stored data on the characteristic of the semiconductor laser with respect to temperatures.

REFERENCES:
patent: 4843604 (1989-06-01), Fujiwara et al.
patent: 4858220 (1989-08-01), Funada
patent: 4935915 (1990-06-01), Fujiwara et al.

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