Patent ID: 8194063

Claim:
Apparatus for providing drive transistor control signals to the gate electrodes of drive transistors in a plurality of EL subpixels in an EL panel, comprising a first voltage supply, a second voltage supply, and a plurality of EL subpixels in the EL panel, each EL subpixel comprising a drive transistor for applying current to an EL emitter in each EL subpixel, each drive transistor comprising a first supply electrode electrically connected to the first voltage supply and a second supply electrode electrically connected to a first electrode of the EL emitter; and each EL emitter comprising a second electrode electrically connected to the second voltage supply, the improvement comprising: a sequence controller for selecting one or more of the plurality of EL subpixels; a test voltage source electrically connected to the gate electrodes of the drive transistors of the one or more selected EL subpixels; a voltage controller for controlling voltages of the first voltage supply, second voltage supply, and test voltage source to operate the drive transistors of the one or more selected EL subpixels in a linear region; a measuring circuit for measuring the current passing through the first and second voltage supplies to provide respective status signals for each of the one or more selected EL subpixels representing the characteristics of the drive transistor and EL emitter of those subpixels, the current being measured while the drive transistors of the one or more selected EL subpixels are operated in the linear region; means for providing a linear code value for each subpixel; a compensator for changing the linear code values in response to the status signals to compensate for variations in the characteristics of the drive transistor and EL emitter in each subpixel; and a source driver for producing the drive transistor control signals in response to the changed linear code values for driving the gate electrodes of the drive transistors.