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:
Nov. 26, 2002
Filed:
Feb. 22, 2001
Masayasu Ito, Shizuoka, JP;
Hitoshi Takeda, Shizuoka, JP;
Koito Manufacturing, Tokyo, JP;
Abstract
A discharge lamp lighting circuit has a DC power supply circuit for outputting a DC voltage, a DC-AC conversion circuit for converting the output voltage of the DC power supply circuit into an AC voltage and then supplying the AC voltage to a discharge lamp and a current detection circuit for detecting an electric current flowing into the discharge lamp. Just after the discharge lamp is lighted, the output frequency of the DC-AC conversion circuit is temporarily changed for defining the lighting frequency of the discharge lamp as a low frequency, to perform DC lighting over a predetermined time. A control circuit determines the duration of the DC lighting by the time it takes for the product of the time and the value of current flowing into the discharge lamp to equal a predetermined value.