Patent ID: 7995029

Claim:
A display apparatus for displaying an image, the display apparatus comprising: a matrix display device comprising a plurality of pixels having electrodes, an optical state of each pixel being defined by particles moving in a fluid between the electrodes dependent on parameters selected from at least one of a value of a drive voltage, a polarity of the drive voltage, or a duration of a drive period during which the drive voltage is present across the electrodes of the pixel; a driver for supplying a sequence of the drive voltages across the electrodes of the pixel during corresponding successive drive periods, each sequence of the drive voltages being applied according to input image data that produces the displayed image; and a DC-balancing circuit comprising a controller for: adjusting at least one of the parameters to determine a time-average value of the drive voltages for the pixel, the time-average value being a sum of products of the drive voltage values with corresponding polarities and drive period durations, and adjusting the time-average value substantially to zero while the pixel is being driven according to the input image data, and a memory for storing the sum, wherein the controller is adapted for comparing an absolute value of the sum with a threshold number; and controlling the driver to supply a reset pulse to the pixel when the absolute value of the sum surpasses the threshold number.