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US 2003/0112211 A1Published application
Active matrix liquid crystal display devices
AssigneeKoninklijke Philips Electronics N. V.
InventorJason R. Hector
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AssigneeKoninklijke Philips Electronics N. V.
InventorJason R. Hector
Estimating the term…
An active matrix liquid crystal display device, comprising an array of liquid crystal display elements (12) having associated switching devices (11) and driven via sets of selection and data address conductors (14,16) by a peripheral control and driving circuit (25), is arranged to undergo a power down procedure when being turned off, in which the control and driving circuit, in response to a power down induction signal (PD) being received thereby, drives the display element electrodes (17) to a predetermined, low, voltage level such that the voltage across the LC material is below the threshold level. Thereafter, electrical power to the control and driving circuit is terminated. In this way, undesirable residual images which can otherwise be produced when turning the display device off are avoided.
An active matrix liquid crystal display device comprising a row and column array of pixels, each pixel comprising a liquid crystal display element having first and second opposing electrodes with liquid crystal material disposed therebetween and a switching device connected to the first electrode, sets of selection and data address conductors connected to the pixels, and a control and driving circuit connected to the sets of address conductors for driving the pixels, wherein the control and driving circuit is operable in response the supply of a power down indicative signal to an input thereof to drive at least the first of the first and second electrodes of the display elements to a similar and predetermined low voltage level such that the voltage across the liquid crystal material at the display elements is below the threshold voltage level of the liquid crystal material.
A display device according to any one of the preceding claims, wherein each pixel further includes a storage capacitor connected between its display element first electrode and a selection address conductor associated with an adjacent row of pixels.
A display device according to any one of the preceding claims, wherein the predetermined low voltage level is around zero volts.
A method of powering down an active matrix liquid crystal display device having an array of pixels comprising liquid crystal display elements and associated switching devices, each display element comprising first and second electrodes with liquid crystal display material therebetween, and a control and drive circuit for driving the display elements to produce a display output, wherein the method comprises driving at least the first electrodes of the display element first and second electrodes to a similar and predetermined low voltage level at which the voltage across the liquid crystal material at the display elements is below the threshold voltage level of the liquid crystal material prior to electrical power to the control and driving circuit being switched off.
Dependencies are inferred from the claim text.