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. 22, 1988
Filed:
Sep. 30, 1986
Taro Shibagaki, Tokyo, JP;
Osamu Kinoshita, Kawasaki, JP;
Kabushiki Kaisha Tohsiba, Kawasaki, JP;
Abstract
A drive circuit supplies a semiconductor laser with current pulses corresponding to an input pulse signal. A current supply feeds a d.c. bias current to the laser. A monitoring photodiode produces a light detection signal indicative of the actual laser output level. The detection signal is supplied to a subtraction device, to which the pulse signal is also supplied via a low-pass filter. The subtraction device detects the difference between the two signals to produce an error signal. Integration devices produce average value signals, which are compared by comparators with reference voltages to obtain control signals. The current supply and the current drive circuit are responsive to these control signals to independently modulate the d.c. bias current and the amplitude of the drive pulses applied to the laser, whereby the laser output level can be stabilized to remain at a constant level.