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1. (WO2018047915) LIGHTING CIRCUIT, VEHICLE LAMP, AND DRIVING METHOD FOR LIGHT SOURCE

Pub. No.:    WO/2018/047915    International Application No.:    PCT/JP2017/032341
Publication Date: Fri Mar 16 00:59:59 CET 2018 International Filing Date: Fri Sep 08 01:59:59 CEST 2017
IPC: H05B 37/02
B60Q 1/04
Applicants: KOITO MANUFACTURING CO.,LTD.
株式会社小糸製作所
Inventors: MARUYAMA Yuta
丸山 雄太
MURAKAMI Kentarou
村上 健太郎
MURAMATSU Takao
村松 隆雄
Title: LIGHTING CIRCUIT, VEHICLE LAMP, AND DRIVING METHOD FOR LIGHT SOURCE
Abstract:
A lighting circuit (400) drives a light source (310) that contains a plurality of N (N is an integer of two or more) light-emitting elements (312) connected in series. A bypass switch circuit (450) contains a plurality of N bypass switches (452), and each bypass switch (452) is connected in parallel to a single corresponding light-emitting element from among the plurality of light-emitting elements (312). A constant current drive circuit (440) supplies a drive current that has been stabilized to a target current to the light source (310). A light distribution controller (470) controls the bypass switch circuit (450). A certain light distribution pattern defines the duty cycle Di (%) of each of the plurality of N light-emitting elements. The plurality of light-emitting elements having a duty cycle sum that is 100% or less constitutes a unit of control. The light distribution controller (470) controls the plurality of bypass switches (452) such that the plurality of light-emitting elements contained in the same unit of control do not light up at the same time.