Patent ID: 7388571
Filing Date: 2008-06-17
Classification: G02F,G06F

Abstract:
1. A touchscreen liquid crystal display comprising: a liquid crystal display including a viewing surface, a liquid crystal area containing liquid crystal located behind the viewing surface, a plurality of spaced apart elongate first electrodes located on a viewing surface side of the liquid crystal area and a plurality of spaced apart elongate second electrodes located on an opposite side of the liquid crystal area, the first and second electrodes overlapping to form an array of liquid crystal pixel elements, at least some of the first electrodes being displaceable towards the second electrodes in response to external pressure applied to the viewing surface; and a control circuit connected to the first and second electrodes for controlling the operation of the liquid crystal display and including: (i) a driver circuit for driving the electrodes for selectively controlling a display state of the pixel elements; and (ii) a measurement circuit for measuring voltages across at least some of the pixel elements and detecting displacement of the at least some of the first electrodes in response to external pressure applied to the viewing surface based on the measured voltages; and a reference electrode in the liquid crystal display overlapping with the first or second electrodes to form reference pixel elements, the measurement circuit comprising a comparison circuit for comparing the measured voltages to reference voltages measured from the reference pixel elements, wherein the reference pixel elements are located outside of a viewable area of the liquid crystal display a sufficient distance so as not to be substantially affected by external pressure applied to the viewing surface.