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:
Aug. 01, 2000
Filed:
Feb. 24, 1999
Takayuki Mogi, Kanagawa, JP;
Takashi Nishimura, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A drive circuit of a light emitting element capable of setting a desired constant current and capable of operating stably at a high speed while holding a forward direction voltage required for the emission of light even under a low power supply voltage, wherein there is provided an input circuit which receives differential drive signals and outputs differential signals of levels in accordance with the level of a supplied drive voltage, a differential output circuit in which an emitter-connection portion of transistors is grounded via a resistor, the differential signals and are supplied to bases, and a laser diode is connected to a collector of the transistor, a reference voltage generation circuit which generates a reference voltage, a comparison circuit which compares the voltage of the emitter-connection portion with the reference voltage and outputs a signal of the level in accordance with the result of comparison, and a variable voltage supply circuit which generates a voltage in accordance with the input level of the output signal and supplies the same as the drive voltage of the input circuit.