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:
Jan. 06, 2015
Filed:
May. 09, 2012
Satoshi Kikuchi, Shizuoka, JP;
Fuminori Shiotsu, Shizuoka, JP;
Takanori Namba, Shizuoka, JP;
Masayasu Ito, Shizuoka, JP;
Satoshi Kikuchi, Shizuoka, JP;
Fuminori Shiotsu, Shizuoka, JP;
Takanori Namba, Shizuoka, JP;
Masayasu Ito, Shizuoka, JP;
Koito Manufacturing Co., Ltd., Tokyo, JP;
Abstract
A semiconductor light source lighting circuit includes a switching regulator that produces a drive current Iwith a switching element, and a control circuit that controls turning on and off of the switching element so that the magnitude of the drive current Iapproaches a target value. The control circuit includes an error comparator that compares the drive current Iand the target value, an up/down counter that performs a counting operation, in which the control digital value is incremented or decremented based on the result of the comparison, a D/A converter that converts the control digital value into an analog duty ratio setting signal S, and a drive circuit that controls the turning on and off of the switching element based on the signal S. The up/down counter stops the counting operation when the switching regulator is brought into the inactive state.