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:
Aug. 20, 2002
Filed:
Jan. 18, 2000
Takeshi Kamoi, Kyoto, JP;
Naoki Komatsu, Osaka, JP;
Tsutomu Shiomi, Nara, JP;
Hiroichi Shinbori, Hyogo, JP;
Takeshi Goriki, Burlington, MA (US);
Yiyoung Sun, Beverly, MA (US);
Matsushita Electric Works, Ltd., Osaka, JP;
Abstract
A discharge lamp lighting device which comprises a D.C. power supply, a load resonance circuit including an inductor, a capacitor and a discharge lamp; a polarity inverting circuit including at least a series circuit of first and second switching elements connected in parallel to the D.C. power supply for converting a D.C. power received from the D.C. power supply into an A.C. power to supply it to the load resonance circuit; and a control circuit for turning ON and OFF the switching elements alternately at a high frequency to alternately generate a first period during which an ON duration of the second switching element is longer than that of the first switching element and a second period during which the ON duration of the second switching element is shorter than that of the first switching element, to thereby apply a rectangular-shaped low frequency voltage to the discharge lamp. The control circuit superimposes a D.C. component in an output of the polarity inverting circuit upon a resonance pulse signal from the load resonance circuit to continuously change a switching frequency of the switching elements for the predetermined time from the start time point of one of the first and second periods, and supplies to the discharge lamp a first energy necessary for starting and lighting the discharge lamp with a high pulse voltage obtained through LC resonance and also for smoothly shifting the lamp to an arc discharge state.