Patent ID: 7321348

Claim:
An organic light-emitting diode (OLED) display system having addressable pixels on a substrate, the pixels having performance attributes, and a control circuit for controlling the pixels of the display device, comprising: a) an array of OLED pixels forming a display device; b) an additional OLED reference pixel external to the display device and located on a common substrate with the display device, and connected to the control circuit, the additional OLED reference pixel having the same performance attributes as the OLED pixels, the additional OLED reference pixel having a voltage sensing circuit including a transistor connected to one of the terminals of the additional OLED reference pixel for sensing the voltage across the additional OLED reference pixel to produce a voltage signal representing the voltage across the additional OLED reference pixel; c) a measurement circuit connected to the voltage signal that represents the voltage across the additional OLED reference pixel to produce an output signal representative of the performance attributes of the additional OLED reference pixel; d) an analysis circuit connected to the measurement circuit to receive the output signal, compare the performance attributes with predetermined performance attributes, and produce a feedback signal in response thereto; and e) the control circuit being responsive to the feedback signal to compensate for changes in the output of the array of OLED pixels.