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:
Dec. 09, 2008
Filed:
Mar. 29, 2005
Shuhei Kawai, Gunma, JP;
Takashige Ogata, Gunma, JP;
Tatsuya Suzuki, Kumagaya, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Abstract
A driver circuit to obtain a current to drive a light emitting device is reduced in a patterning area and improved in efficiency. A positive power supply voltage Vdd is applied to an anode of a white LED, while a voltage −0.5 Vdd from a −0.5 Vdd generation circuit is applied to a cathode of the white LED through an N-channel type MOS transistor. The −0.5 Vdd generation circuit generates the voltage −0.5 Vdd according to a clock Φ from a clock generation circuit. A voltage of 1.5 Vdd is applied between the anode and the cathode of the white LED, as equivalent to a prior art. Since N-channel type MOS transistors are heavily used in the −0.5 Vdd generation circuit, the driver circuit requires less patterning area to obtain the same amount of current to drive the LED as in the prior art. In addition, a parasitic capacitance is reduced to improve efficiency of the driver circuit.