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:
Aug. 03, 1993
Filed:
Oct. 01, 1991
Lee A Newman, Dayton, OH (US);
Dusty L Lutz, Miamisburg, OH (US);
Theodore Heske, III, Centerville, OH (US);
NCR Corporation, Dayton, OH (US);
Abstract
A method and circuit for controlling the contrast of a liquid crystal display (LCD). The circuit includes a switching regulator circuit which generates a negative voltage at the output thereof, with the switching regulator circuit having a feedback node therein and also having a voltage regulator with a control input therein. An injected current coupled to the feedback node and the control input to the voltage regulator is used to provide a changed negative voltage at the output of the regulator circuit. Control values stored in the memory of a controller are used to select the injected current. The changed negative voltage at the output of the regulator circuit is used to control the contrast of the LCD.