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. 18, 2014
Filed:
Jul. 22, 2011
Takayuki Shimizu, Osaka, JP;
Atsushi Kanamori, Osaka, JP;
Hirohisa Warita, Osaka, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An LED drive circuit is provided that can be connected to an alternating current power source via a phase-control light controller and drives an LED load. The LED drive circuit includes: a switching power source portion having a switching element, a switching current detection portion that detects a switching current, and an LED current detection portion that detects an LED current; a first subtraction portion that subtracts a given value from an output of the switching current detection portion; a first determination portion that determines, through computation on a plurality of externally inputted voltages, a target value to which the switching current is limited; a second subtraction portion that subtracts a given value from an output of the LED current detection portion; a second determination portion that determines, through computation on a plurality of externally inputted voltages, a target value of the LED current; a switching current limitation portion that, if a result of the subtraction by the first subtraction portion exceeds a result of the determination by the first determination portion, switches off the switching element so as to limit the switching current; and an LED current control portion that drives the switching element to control the LED current so that a result of the subtraction by the second subtraction portion coincides with a result of the determination by the second determination portion.