Abstract text

Sub-pixel current in an OLED display is forced to converge to a desired level regardless of the source of pixel current error. By using a feedback loop, the pixel transistor current is forced to be equal to a predetermined target current that is established by an analog control circuit. The predetermined target current is selected to generate the desired pixel transistor current through the sub-pixel, and can be set by setting a target voltage. The sub-pixels have a 3T cell structure including 3 TFTs, one TFT for connecting the data line to the storage capacitor, another TFT for driving the sub-pixel current, and still another TFT for connecting the OLED diode anode to the data line of the AMOLED panel. Thus, the feedback loop of the present invention (comprising Taps M and N of a resistor string, and an amplifier, a comparator, and digital logic) senses the pixel transistor current via the data lines of the AMOLED panel to compensate for Mura