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. 04, 1997
Filed:
Mar. 10, 1995
Alan G Knapp, Crawley, GB;
John M Shannon, Whyteleafe, GB;
Alexander D Annis, Haywards Heath, GB;
Jeremy N Sandoe, Horsham, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
In an active matrix display device having an army of electro-optic, e.g. liquid crystal, display elements (12) which are each connected in series with a two-terminal non-linear device (15), such as a MIM type thin film diode, between associated row and column address conductors (16,17), and are driven by a circuit, (20,22) to produce a display effect by applying a selection signal to each row address conductor in turn and data signals to the column address conductors, a selection signal comprising a voltage pulse signal whose magnitude is increased gradually and in a controlled fashion to a maximum selection voltage amplitude is used so as to reduce the extent of ageing in the non-linear devices and differential ageing effects on display elements driven to different levels over a period of use by reducing peak currents flowing through the non-linear devices. The rising edge of the selection pulse signal is suitably shaped, for example by ramping or stepping, for this purpose. When using a five level row drive waveform comprising positive and negative selection signals and a reset signal, the reset selection signal can be shaped in this way, preferably together with the selection signal of opposite polarity.