System and methods for aging compensation in AMOLED displays
Methods and systems to provide baseline measurements for aging compensation for a display device are disclosed. An example display system has a plurality of active pixels and a reference pixel. Common input signals are provided to the reference pixel and the plurality of active pixels. The outputs of the reference pixel is measured and compared to the output of the active pixels to determine aging effects. The display system may also be tested applying a first known reference current to a current comparator with a second variable reference current and the output of a device under test such as one of the pixels. The variable reference current is adjusted until the second current and the output of the device under test is equivalent of the first current. The resulting current of the device under test is stored in a look up table for a baseline for aging measurements during the display system operation. The display system may also be tested to determine production flaws by determining anomalies such as short circuits in pixel components such as OLEDs and drive transistors.
1. A method of display device production for display devices each having a plurality of pixels, each pixel of the plurality of pixels comprising a drive transistor and a light emitting device, the method comprising:
applying test signals to each of the plurality of pixels, the test signals applied to each pixel including a first control signal which turns off one of the drive transistor and the light emitting device of the pixel;
electrically measuring, for each of the pixels, voltage and current characteristics of the other one of the drive transistor and the light emitting device which is not turned off by said first control signal, while said one of the drive transistor and the light emitting device is off; and
varying at least one process of the display device production based on the measurements of said voltage and current characteristics.
2. The method of claim 1 , wherein the measurements of said voltage and current characteristics are indicative of at least one of a shorted organic light emitting device and a shorted drive transistor.
3. The method of claim 1 , wherein said test signals further include a second control signal for controlling a decoupling of a supply voltage from the one of the drive transistor and the light emitting device which is turned off by said first control signal.