Stable driving scheme for active matrix displays
A method and system for operating a pixel array having at least one pixel circuit is provided. The method includes repeating an operation cycle defining a frame period for a pixel circuit, including at each frame period, programming the pixel circuit, driving the pixel circuit, and relaxing a stress effect on the pixel circuit, prior to a next frame period. The system includes a pixel array including a plurality of pixel circuits and a plurality of lines for operation of the plurality of pixel circuits. Each of the pixel circuits includes a light emitting device, a storage capacitor, and a drive circuit connected to the light emitting device and the storage capacitor. The system includes a drive for operating the plurality of lines to repeat an operation cycle having a frame period so that each of the operation cycle comprises a programming cycle, a driving cycle and a relaxing cycle for relaxing a stress on a pixel circuit, prior to a next frame period.
1. A method of operating a pixel array having pixel circuits arranged in rows, comprising the step of repeating an operation cycle defining a frame period for the pixel circuits, including at each frame period:
programming a first of the pixel circuits in a first row of the rows of pixel circuits by activating a select line a first time to select the first pixel for programming;
responsive to the select line being deactivated, driving the first pixel circuit while the select line remains deactivated; and
activating the select line a second time, prior to the next frame period, to cause the first pixel circuit to be turned off to relax the first pixel circuit and to simultaneously reset a second pixel circuit in an other row of the rows for a programming operation to program the second pixel circuit,
wherein the select line is deactivated between the first time it is activated and the second time it is activated, and
wherein a period between the second time the select line is activated and an end of the frame period is fixed.
2. The method of claim 1 , wherein the programming is a voltage programming such that a programming voltage is transferred to a storage device of the first pixel circuit, the programming voltage being related to a brightness at which a light emitting device of the first pixel circuit emits light during the driving.
3. The method of claim 1 , wherein the first pixel circuit includes a storage device, the storage device being utilized in the programming and not being involved with causing the first pixel circuit to turn off.
4. The method of claim 1 , wherein the first pixel circuit is programmed using a signal that has a type that is a voltage signal or a current signal, and wherein the first pixel circuit is turned off using the same type of signal used to program the first pixel circuit.
5. The method of claim 1 , wherein the programming uses a signal that is in a form of a voltage signal or a current signal, and wherein the first pixel circuit is turned off using the same form of signal used to program the first pixel circuit.