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:
Sep. 12, 2000
Filed:
Feb. 10, 1998
Franklin S Ho, San Carlos, CA (US);
William E Miller, Los Gatos, CA (US);
Ying Quan Zhong, Fremont, CA (US);
Richard E Crippen, Mountain View, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A voltage supply circuit for an LCD driver employs two voltage dividers. A low current voltage divider includes resistive elements having a high resistance, thus providing a bias voltage with a low current. A high current voltage divider includes resistive elements having low resistances, thus providing a bias voltage with a high current. The high current voltage divider provides bias voltage levels with high current at the beginning of each time phase change. Thus, the liquid crystal display receives a high current when updating the bias voltage levels on the LCD, thereby producing a fast settling time. When the bias voltage levels are held constant, however, only the low current voltage divider provides the bias voltage levels to reduce power consumption. A halt mode prevents the liquid crystal display and driver from consuming any power by disconnecting both voltage dividers from the voltage source when in sleep mode. A voltage drop mode produces a reduction in the bias voltage levels by placing another voltage drop in series with the voltage dividers.