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. 19, 2009
Filed:
Apr. 27, 2007
Walter P. M. Gurr, Seattle, WA (US);
Walter P. M. Gurr, Seattle, WA (US);
Korry Electronics Co., Seattle, WA (US);
Abstract
A hybrid power supply provides powers to a load, such as a light emitting diode (LED) backlight display, using pulse wave modulation (PWM) enable signal to control activation of a linear power supply and a switching power supply. During an initial part of an active portion of a duty cycle of the PWM enable signal, the linear power supply is activated to supply the load with constant current. During the remainder of the active portion of the duty cycle of the PWM enable signal, the linear power supply is deactivated and the switching power supply is activated to provide current to the load. A bias current and voltage may be provided to the LED during an inactive portion of the duty cycle of the PWM enable signal. The hybrid power supply combines the high efficiency of the switching power supply with smooth dimming control at low luminance of the linear power supply.