The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 15, 1989
Filed:
Oct. 14, 1987
Saburo Funada, Tokyo, JP;
Olympus Optical Co., Ltd., Tokyo, JP;
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.