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. 18, 2003
Filed:
Dec. 20, 2000
Fumihiko Kato, Yamagata, JP;
NEC Electronics Corporation, Kanagawa, JP;
Abstract
A liquid crystal drive circuit for AC-driving a liquid crystal panel, the liquid crystal drive circuit being constituted of a switched capacitor type D/A converter having a sample period and a hold period, the liquid crystal drive circuit comprising a differential operational amplifier , a first reference voltage input terminal connected to one input terminal of the differential operational amplifier, a first capacitor group connected to the other input terminal of the differential operational amplifier, for dividing second and third reference voltages and , a second capacitor group connected between an output terminal and the other input terminal of the differential operational amplifier, and switch means to for changing a connection condition of the first capacitor group and the second capacitor group to the differential operational amplifier, the switch means being on-off controlled at every predetermined periods for changing the connection condition, so that a color unevenness is minimized when the liquid crystal panel is displayed. In a liquid crystal drive circuit for generating a drive voltage for a graduation display realized by applying a predetermined voltage to a liquid crystal panel, an output voltage error appearing at the time of an AC drive can be compensated in units of frames.