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:
Jan. 04, 1994
Filed:
May. 11, 1992
Akira Minami, Kawasaki, JP;
Shigeyoshi Tanaka, Kawasaki, JP;
Fujitsu Limited, , JP;
Abstract
A laser diode having a cathode connected to the ground side of a positive power source and an anode connected to the plus voltage side of the power source through a control circuit. A maximum current to drive the laser diode is supplied to the laser diode by a disgorging type constant current source. In a reading mode operated at a frequency one or more digit higher than a frequency for writing data, a differential current between the write current and a read current is sucked from the disgorging type constant current source by a sucking type constant current source, thereby allowing the read current to flow into the diode. In a writing mode, a current switch connects the sucking type current source according to write data. The disgorging type current source and the sucking type current source are connected to a photodiode by a current switch. An APC responds to the photodiode which detects a read power, thereby reducing a laser fluctuation created from temperature change.