Patent ID: 8681135

Claim:
An organic light emitting display, comprising: a pixel unit disposed on a transparent substrate and configured to display an image in response to scan signals and data signals; a scan driver configured to generate the scan signals and to transmit the scan signals to the pixel unit; a data driver configured to generate the data signals and to transmit the data signals to the pixel unit; a photo sensor comprising a sensing unit disposed on the transparent substrate and configured to sense brightness of ambient light and to output a sensing signal, and a control unit configured to receive the sensing signal and to output a brightness control signal for controlling brightness of the image, wherein the sensing unit comprises: a first photo diode configured to receive a first driving power source to generate optical current so that a magnitude of the optical current is controlled in response to the brightness of the ambient light; a first capacitor configured to store a voltage corresponding to the optical current; and a first switch coupled between the first driving power source and the first photo diode to perform a switching operation according to a switch control signal, wherein the first switch and the first capacitor are connected to different electrodes of the first photo diode, and wherein the control unit comprises: an amplifier configured to receive the sensing signal output from the sensing unit coupled to a first input end of the amplifier to amplify the received sensing signal and to transmit the amplified sensing signal to an A/D converter; the analog to digital (A/D) converter configured to receive the amplified sensing signal to convert the received amplified sensing signal into a digital signal; and a controller configured to receive the digital signal from the A/D converter to generate the brightness control signal; and a compensating unit configured to transmit a compensating signal to the amplifier, wherein the compensating unit is coupled to a second input end of the amplifier.