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:
Feb. 20, 2007
Filed:
Aug. 22, 2003
Yasuo Kurusu, Kyoto, JP;
Yasuo Kurusu, Kyoto, JP;
Dainippon Screen Mfg. Co., Ltd., Kyoto, JP;
Abstract
The present invention provides a light emitting device drive circuit which does not require complicated feedback control for shortening a rising response delay time in the transition from an extinction state of a light emitting device to a light emitting state so as not to increase a bias current, and for eliminating harmful effects due to the influence of a droop phenomenon. A circuit including a series of a coiland a resistoris connected in parallel with an LD. In this configuration, the LDis subjected to supply of an overshoot drive current ILD for a time period determined by a time constant of the coiland the resistor, i.e., a time period in which a high-frequency current is supplied in the transition from the extinction state to the light emitting state. Thus, a delay in rise time until light emission of the LDcan be decreased. The drive current ILD supplied to the LDis increased in proportion to a decrease of a forward voltage Vsupplied to the LDdue to temperature rise. Thus, even if the light emitting state continues for a long period of time, the intensity of light emission from the LDcan be kept constant.