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:
Mar. 31, 1992
Filed:
Sep. 28, 1990
Ryoji Takeuchi, Yokohama, JP;
Akihiko Doi, Tokyo, JP;
Kabushiki Kaisha Toshiba, , JP;
Abstract
In an information recording system, a semiconductor laser is energized in response to a drive current which is modulated in accordance with a recording signal in a recording mode so that a modulated laser beam is generated from the semiconductor laser. The modulated laser beam is focused on an optical disk and is reflected from the optical disk and the reflected laser beam is detected by an photo-detector. A detection signal from the detector is compared with a predetermined threshold level which is set in accordance with the peak intensity by a binary circuit and a relationship between the recording signal and an output signal from the binary circuit is detected by a detection circuit. In an overwrite mode in which the laser beam is focused on pit or pits on the optical disk, an overwrite detection signal is generated from the detection circuit and the overwrite detection signal is mounted by a counter circuit. When the counter circuit counts a predetermined count value, the counter citcuit generates a recording inhibition signal for preventing the semiconductor laser from generating the modulated laser beam.