Digitally driven gray scale operation of active matrix OLED displays

Disclosed is a pixel circuit consisting of MOS field-effect transistors (or of thin-film transistors), a capacitor, and an organic light-emitting diode that stores a voltage signal that is used to control the amount of light emitted from the pixel. This pixel circuit is used in a two-dimensional array to form an active-matrix OLED display. The amount of light emitted at each pixel during a frame time is controlled by dividing the frame time into many sub-frames and changing the stored voltage at the beginning of each sub-frame in such a way that the integrated time a voltage is stored during a frame time determines the total amount of light emitted.