Patent ID: 7733318

Claim:
A display device comprising: a display panel having pixels arranged in a matrix form; a driving circuit for outputting an analog voltage according to a video signal to said pixels through signal lines; a plurality of measuring circuits each for detecting the amount of transmitted light; a single totalizing circuit for totalizing the results of measurements made by said respective measuring circuits; and a control circuit for adjusting a potential on a common electrode of said display panel in accordance with the result of the totalization from said totalizing circuit, wherein the control circuit comprises: a) at least one sample and hold unit for: sampling and holding the result of totalization when a positive signal voltage is applied to a pixel for which the amount of light should be controlled, and sampling/holding the result of totalization when a negative signal voltage is applied to a pixel for which the amount of light should be controlled; b) a comparator for comparing the result of totalization when the positive signal voltage is applied with the result of totalization when the negative signal voltage is applied; and c) a controller for: controlling a voltage to be applied to the common electrode in accordance with the comparison result, transitioning the voltage to be applied to the common electrode in steps when the voltage to be applied to the common electrode is controlled, and adjusting the voltage applied to the common electrode to a predetermined value at a timing at which a result of the comparison by the comparator reverses in sign.