Patent ID: 8228267
Filing Date: 2012-07-24
Classification: G09G

Abstract:
1. A method of providing a drive signal to a gate electrode of a drive transistor in an electroluminescent (EL) subpixel, the method comprising: (a) providing the EL subpixel comprising the drive transistor, an EL emitter, and a readout transistor, the drive transistor comprising: a first electrode, a second electrode, and the gate electrode; (b) providing a first voltage source and a first switch for selectively connecting the first voltage source to the first electrode of the drive transistor; (c) connecting the EL emitter to the second electrode of the drive transistor; (d) providing a second voltage source connected to the EL emitter; (e) connecting the first electrode of the readout transistor to the second electrode of the drive transistor; (f) providing a current source and a third switch for selectively connecting the current source to the second electrode of the readout transistor; (g) providing a voltage measurement circuit connected to the second electrode of the readout transistor; (h) opening the first switch, closing the third switch, and using the voltage measurement circuit to measure the voltage at the second electrode of the readout transistor to provide a first emitter-voltage signal; (i) using the first emitter-voltage signal to provide an aging signal representative of the efficiency of the EL emitter; (j) receiving an input signal; (k) using the aging signal and the input signal to produce a compensated drive signal; (l) providing the compensated drive signal to the gate electrode of the drive transistor to compensate for changes in efficiency of the EL emitter; and providing a second switch for selectively connecting the EL emitter to the second voltage source, wherein step (h) includes closing the second switch.