Patent ID: 8633877

Claim:
An organic light emitting display comprising: a display unit comprising a plurality of organic light emitting diodes (OLEDs) each comprising a cathode electrode and configured to emit light in response to a current flowing through the display unit from a first power supply to a ground power supply connected to the cathode electrode, said current corresponding to a data signal supplied in accordance with a scan signal; a data driver for generating the data signal by receiving a video signal and transferring the data signal to the display unit; a scan driver for providing the scan signal to the display unit; a power supply unit having a first output terminal for outputting a fixed voltage first power of the first power supply and a second output terminal for outputting a frame-by-frame variable voltage ground power of the ground power supply, the power supply unit being configured to output the first power to the display unit and the ground power to the cathode electrode of each of the OLEDs; and a driving voltage calculation unit for calculating a voltage at the cathode electrode of all of the OLEDs, said voltage corresponding to a maximum current from among said current of each of the OLEDs, the driving voltage calculation unit being configured to receive a plurality of video signals of an image frame, to determine a maximum red video signal, a maximum green video signal, and a maximum blue video signal from among red, green, and blue video signals, respectively, of the plurality of video signals, and to determine the maximum current for the image frame by using the maximum red video signal, the maximum green video signal, and the maximum blue video signal, wherein said voltage is output through the second output terminal.