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. 12, 2002
Filed:
Oct. 04, 1999
Tomobumi Nakayama, late of Tokyo, JP;
Michiharu Masuda, Numazu, JP;
Hisatsugu Tahara, Kawasaki, JP;
Akio Ito, Machida, JP;
Yukio Yokoyama, Mishima, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An image forming apparatus is arranged to form an image with laser light emitted from a semiconductor laser source, and is constructed so as to protect the laser source from a breakdown, by regulating electric current flowing to the laser source no matter when an adjusting circuit for adjusting the light amount of the semiconductor laser source is apt to supply the electric current that could break the laser source, to the laser source. The apparatus is constructed in such structure that during an automatic light amount control period the laser light amount emitted from the semiconductor laser source is detected and a current source circuit is made inactive when the light amount detected is over a set light amount and that during periods other than the control period the electric current flowing to the semiconductor laser is detected and the current source circuit is made inactive when the light amount detected becomes over a fixed ratio times the current detected during the automatic light amount control period. In this way, the protection circuit can operate effectively anytime of emission of the laser source, so as to protect the laser source from the breakdown.