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:
Mar. 13, 2001
Filed:
Dec. 21, 1998
Richard Alexander Erhart, Chandler, AZ (US);
Gerald T. Harder, Gilbert, AZ (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A power-saving column driver integrated circuit, and a power-saving method for driving a liquid crystal display, include a series of multiplexers coupled to the columns of the display. The multiplexers selectively couple each of the columns to a common external storage capacitor during a portion of each row drive period for discharging each of the pixels in the selected row of the liquid crystal display to a median bias voltage. During the remaining portion of each row drive period, the multiplexers selectively couple voltage drivers to the columns of the LCD pixel array for applying a desired driving voltage to each column of the array. The polarity of the driving voltages applied to each column alternates on succeeding row drive periods, and the resulting voltage that is summed on the storage capacitor averages to the median bias voltage. For active matrix liquid crystal display panels, a multiplexer selectively couples the backplane of the display panel to either an external storage capacitor or to an alternating-polarity backplane driving voltage during each row drive period.