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:
Dec. 22, 2009
Filed:
Oct. 16, 2006
Hitoshi Takeda, Shizuoka, JP;
Toru Nakayama, Shizuoka, JP;
Masayasu Ito, Shizuoka, JP;
Koito Manufacturing Co., Ltd., Tokyo, JP;
Abstract
In a process in which a current is supplied from a switching regulator to multi-chip LEDs, the forward voltages of the LEDs are respectively detected in forward detecting circuits. The detected values are sent to a microcomputer. In the microcomputer, detected values when the multi-chip LEDs are initially turned on are stored as initial values. A first abnormality deciding value is set from the initial value. The detected values are sequentially stored as updated values. Second abnormality deciding values having conditions stricter than those of the first abnormality deciding value are sequentially set in accordance with the stored updated value. A read value is compared with the first abnormality deciding value or the read value is compared with the second abnormality deciding value to decide whether or not the abnormality of the LEDs is present. When it is decided that the LEDs are abnormal, an LED is turned on to inform a driver of the presence of the abnormality.