Laser control circuit for optical data recording/reproduction ap

Details Laser control circuit for optical data recording/reproduction ap Laser control circuit for optical data recording/reproduction ap

1987-10-14

1989-08-15

McElheny, Jr., Donald

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

G11B 7125

Patent

active

048582204

ABSTRACT:
A laser controller for an optical data recording/reproducing apparatus includes a detector for detecting an intensity of a laser beam emitted from a laser, a servo controller for comparing the detected value with a reference value and generating a feedback signal in accordance with the difference between the two values, and a drive circuit for supplying a drive signal corresponding to the feedback signal to the laser, and a modulator for modulating the drive signal during recording. Furthermore, the laser controller includes a controller connected to the servo controller, a RAM, a timer, and a temperature sensor which are connected to the controller. When reproduction and erasing are to be performed, the operation of the modulator is stopped, and the drive signal is obtained by feedback control. When erasing is to be performed, a level of the feedback signal is stored in the RAM. When recording is to be performed, the operation of the servo controller is stopped, while the level of the stored feedback signal read out from the RAM is supplied to the drive circuit. As a result, the intensity of the laser beam is not controlled by feedback control, but by open loop control based on the readout feedback signal, while the intensity of the laser beam is modulated in accordance with the data to be recorded.

REFERENCES:
patent: 4051329 (1977-09-01), Blondet et al.
patent: 4150402 (1979-04-01), Tietze et al.
patent: 4507767 (1985-03-01), Takasugi
patent: 4509156 (1985-04-01), Ohara et al.
patent: 4685097 (1987-08-01), van der Put
patent: 4698797 (1987-10-01), Komatsu
patent: 4747091 (1988-05-01), Doi

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