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. 26, 2017
Filed:
Apr. 28, 2017
Rohm Co., Ltd., Kyoto, JP;
Yoshiyuki Nakatani, Kyoto, JP;
Shinsuke Takagimoto, Kyoto, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
A light emitting device includes a series connection unit constituted of N light emitting elements, a light emitting element driving circuit having an output terminal connected to an anode of the series connection unit, N short-circuit switches respectively connected in parallel to the light emitting elements, and a switch control unit arranged to control on and off of the short-circuit switches. A ground fault detection circuit, which detects a ground fault of the light emitting device, includes a reference voltage source arranged to generate a reference voltage, and a comparator arranged to compare the anode voltage of the series connection unit with the reference voltage. The reference voltage has a value smaller than the product of an on-resistance of one of the short-circuit switches and output current of the light emitting element driving circuit.