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:
Sep. 14, 1999
Filed:
Mar. 11, 1997
Kenichiro Nishi, Tokyo, JP;
Satoshi Nagai, Tokyo, JP;
Kentaro Eguchi, Tokyo, JP;
Takeshi Arai, Tokyo, JP;
Jun Bunya, Tokyo, JP;
Kazutaka Shimizu, Tokyo, JP;
Koji Shibata, Tokyo, JP;
Isamu Ogawa, Kanagawa, JP;
Mitsubishi Denki Kabushiki Kaisha, Chiyoda-ku, JP;
Mitsubishi Lighting Fixture Co., Ltd., Kamakura, JP;
Abstract
A current flowing through a discharge lamp 4 is detected by a current detecting circuit 5, and the detected current is outputted as a lamp current signal A to a feedback control circuit 7 where a difference between the lamp current signal A and the dimming control signal B is obtained and amplified, and then a simplified signal D is outputted to an adder 12 which adds the amplified signal D to the dimming control signal B to constitute a control signal E. The control signal is fed back to a high frequency power supply 2. When a comparing circuit 15 detects that the light level of the dimming control signal B with respect to the full light becomes higher than or equal to 40% to 60%, the feedback circuit is disconnected by operating a switch 13 provided between an error amplifying circuit 9 and an adder 12 to stop the feedback control.