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:
May. 06, 2008
Filed:
Apr. 26, 2005
Akinori Hayafuji, Yonezawa, JP;
Akinori Hayafuji, Yonezawa, JP;
Tohoku Pioneer Corporation, Yamagata, JP;
Abstract
A clock signal synchronized with a data write signal for each scan line supplied from a light emission control circuitto a scan driveris supplied to an oscillatorgenerating a reference switching signal of a DC-DC converterby a PWM method via a frequency divider. Thus, even when a ripple component by a switching operation of the converter has been superimposed on a drive voltage Va, constantly the same gate-to-source voltage Vgs is supplied to a light emission drive transistor Trfor each scan line, whereby a problem that a state in which light emission intensities differ for each scan line is brought about can be resolved. Further, the duty ratio of a switching signal from a PWM circuitis detected by a detection circuitto grasp the load condition of the converter, and when the load is light, the division ratio of the frequency divideris increased to execute the switching operation at a low frequency. In this manner, the cycle (boost cycle) of the switching operation in the converter is made greater, so that a useless power loss by the switching operation in the converter can be reduced, whereby the power utilization rate of a light load time can be improved.