Patent ID: 9013383
Filing Date: 2015-04-21
Classification: G09G

Abstract:
1. A method of compensating for gate kickback in an electrooptic display, the display comprising an electrooptic display medium having a plurality of pixels and being mounted on a backplane, said backplane bearing a plurality of pixel driver circuits for said plurality of pixels, each said pixel driver circuit comprising a transistor having drain, source and gate connections, one of said drain and source connections being electrically coupled to a pixel electrode of a respective pixel, said gate electrode being electrically coupled to a gate drive line of said electrooptic display, said pixel driver circuit further having a common electrode, said common electrode being coupled to provide a common electrode connection for a plurality of said pixels, wherein, in use, a gate voltage on said gate drive line is controlled between a positive gate voltage with respect to a common voltage (Vcom) on said common pixel electrode and a negative gate voltage with respect to said common voltage (Vcom) on said common electrode to control information displayed by a pixel of said electrooptic display, the method comprising: inputting said positive gate voltage into a differential amplifier; inputting said negative gate voltage into the differential amplifier; outputting a signal from the differential amplifier and providing the signal to a digital-to-analogue converter; controlling a reference level of said digital-to-analogue converter in response to the signal from said differential amplifier; and in response to the reference level, offsetting a value of said common voltage (Vcom) on said common electrode by an offset value (Voffset), said offset value (Voffset) dependent on a gate voltage swing (Vgswing) equal to a difference between said positive gate voltage and said negative gate voltage, wherein said offset value (Voffset) is determined using Voffset=K×Vgswing, where K is a constant of proportionality for said display, and wherein said digital-to-analogue converter performs said multiplication, wherein a gate kickback voltage is minimized when driving said display, said gate kickback voltage comprising a change in voltage across a said pixel electrode and said common electrode arising from capacitive coupling in said electrooptic display between a said gate drive line and a said pixel electrode.