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:
Mar. 19, 2013
Filed:
Feb. 24, 2010
Junichi Hasegawa, Kashiwara, JP;
Nobutoshi Matsuzaki, Neyagawa, JP;
Junichi Hasegawa, Kashiwara, JP;
Nobutoshi Matsuzaki, Neyagawa, JP;
Panasonic Corporation, Osaka, JP;
Abstract
A discharge lamp ballast is provided for powering a discharge lamp with feedback filament heating control. A startup circuit is coupled between output terminals of a DC-AC power converter together with a discharge lamp. A lamp current detection circuit and a lamp voltage detection circuit detect output signals to the lamp. A control circuit controls the switching elements and generates an operating frequency in accordance with a startup operation to generate a high voltage output from the startup circuit and ignite the discharge lamp, a filament heating operation wherein the operating frequency is controlled so as to set the amplitude of the output current detected by the lamp current detection circuit to a target current amplitude based on the amplitude of the output voltage detected by the lamp voltage detection circuit, and a steady-state operation wherein the operating frequency is decreased to maintain a stable light output from the discharge lamp.