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. 28, 1989
Filed:
Sep. 23, 1988
Osamu Kinoshita, Kawasaki, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In a laser driving device for stabilizing the optical output level of a semiconductor laser, a drive circuit supplies a drive current signal to the laser. A monitoring photodiode is provided for partially receiving the optical laser output to produce an electrical monitor signal indicative of the actual output level of the laser. A differential amplifier is connected to the photodiode to serve as a comparator for receiving a reference signal indicative of a reference output level of the laser, and for detecting a difference between values of the monitor signal and the reference signal to produce a comparison signal indicative of a change in the actual optical output level of the laser. An abnormal current eliminator is connected to the comparator, for, when the laser is disenergized or just after it is driven to become operative, controlling the comparator so that the comparison signal has a limited amplitude, whereby a current component undesirably supplied as the driven current to the laser is forcibly decreased to eliminate abnormal current from flowing in the laser.