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. 10, 2019
Filed:
Jan. 25, 2019
Seiko Epson Corporation, Tokyo, JP;
Atsushi Yamada, Suwa, JP;
SEIKO EPSON CORPORATION, Tokyo, JP;
Abstract
A light source device includes: a semiconductor light source; a switching element connected in series to the semiconductor light source; a drive circuit that turns on the switching element when a first control signal based on a PWM signal is in a first logic state; a switching power supply circuit that supplies a current to the semiconductor light source; a current detection element that detects a current flowing through the semiconductor light source and generates a current detection signal; a current detection circuit that sample-holds a current detection signal for a period shorter than an activation period of the PWM signal; an error amplifier that generates an error signal by amplifying the difference between a current control signal and an output signal of the current detection circuit; and a control circuit that generates a second control signal for controlling the switching power supply circuit based on the error signal.