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:
Apr. 17, 2007
Filed:
Jun. 21, 2004
Shinichi Nakatsuka, Hino, JP;
Jyunshin Sakamoto, Mito, JP;
Hiroshi Inenaga, Hitachi, JP;
Susumu Saito, Hachioji, JP;
Shinichi Nakatsuka, Hino, JP;
Jyunshin Sakamoto, Mito, JP;
Hiroshi Inenaga, Hitachi, JP;
Susumu Saito, Hachioji, JP;
Ricoh Printing Systems Co., Ltd., Tokyo, JP;
Abstract
When a semiconductor laser is energized, a virtual junction temperature rises to reduce a threshold current, which fluctuates a light output by the unit of a several microseconds, thereby causing printing irregularity. An object of the invention is to prevent the fluctuation in light output occurring due to the temperature change caused by the energization of the semiconductor laser with a simple circuit structure and under the driving condition of a small bias current. A constant voltage driving is performed with a circuit or device having negative resistance characteristics being arranged in series with the semiconductor laser. Thus, the reduction in light output of the semiconductor laser due to the temperature rise is compensated for by an increase in driving current thanks to a reduction in rising voltage of current/voltage characteristics.