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:
Nov. 10, 1992
Filed:
Feb. 04, 1991
Yukio Yoshikawa, Tokyo, JP;
Takeshi Ishii, Tokyo, JP;
Yoshihiro Oyama, Tokyo, JP;
Tatsuo Sasaki, Tokyo, JP;
Tamotsu Takahashi, Tokyo, JP;
Shinichi Sato, Kawasaki, JP;
Kazumasa Moriya, Kawasaki, JP;
Ichiro Shinoda, Kawasaki, JP;
Motohiko Itoh, Kawasaki, JP;
Tomoyuki Kashiwazaki, Kawasaki, JP;
Hiroaki Kawai, Kawasaki, JP;
Mitsuo Watanabe, Kawasaki, JP;
Copal Co., Ltd., both of, JP;
Fujitsu Limited, both of, JP;
Abstract
A semiconductor laser driving circuit has a semiconductor laser for emitting a laser beam according to a drive power. A photodetector is provided for effecting photo-electric conversion of the laser beam to output a corresponding electric signal. A monitoring circuit is connected for monitoring the electric signal to output a monitor signal indicative of variation in intensity of the laser beam. A controlling circuit is connected for comparing the monitor signal with a given reference signal to output a control signal according to difference therebetween. A powering circuit is operative according to the control signal to apply to the semiconductor laser a drive power effective to eliminate the difference. An abnormality detecting circuit is provided for comparing the monitor signal with a given limit signal which is set different from the reference signal to detect abnormality to output an abnormality signal.