System and driving method for active matrix light emitting device display

A pixel circuit comprising:

• a light emitting device;
• a capacitor having a first terminal and a second terminal;
• a first switch transistor having a gate terminal, a first terminal and a second terminal, the gate terminal of the first switch transistor being connected to a first select line, one of the first and second terminals of the first switch transistor being connected to a signal line, the other terminal being connected to the first terminal of the capacitor, the signal line providing a bias voltage and a programming voltage dependent on a programming data for said pixel circuit during a programming cycle when the first switch transistor is enabled;
• a second switch transistor having a gate terminal, a first terminal and a second terminal, the gate terminal of the second switch transistor being connected to a second select line, one of the first and second terminals of the second switch transistor being connected to the second terminal of the capacitor and the light emitting device, the other terminal being connected to a bias line that provides a controllable bias current, independent of said programming data for said pixel circuit, when the second switch transistor is enabled;
• a driving transistor for driving the light emitting device, the driving terminal having a gate terminal connected to the first terminal of the capacitor;
• wherein the bias voltage and the programming voltage provided by the first switch transistor and the bias current provided by the second switch transistor accelerate the programming of the pixel circuit and compensate for a time dependent parameter of the pixel circuit.

A method of driving a pixel circuit, the pixel circuit comprising a light emitting device, a capacitor, a first switch transistor, a second switch transistor, and a driving transistor for driving the light emitting device, each transistor having a gate terminal, a first terminal and a second terminal, the capacitor having a first terminal and a second terminal, the gate terminal of the first switch transistor being connected to a first select line, one of the first and second terminals of the first switch transistor being connected to a signal line, the other terminal of the first switch transistor being connected to the first terminal of the capacitor, the gate terminal of the second switch transistor being connected to a second select line, one of the first and second terminals of the second switch transistor being connected to the second terminal of the capacitor and the light emitting device, the other terminal of the second switch transistor being connected to a bias line, the gate terminal of the driving transistor being connected to the first terminal of the capacitor, the method comprising the steps of:

• at a first operation of a programming cycle, providing a bias voltage on the signal line and providing a controllable bias current, independent of said programming data for said pixel circuit, on the bias line;
• and
• at a second operation of the programming cycle, providing a programming voltage dependent on a programming data for said pixel circuit on the signal line,
• wherein said bias voltage and said programming voltage and said bias current accelerate the programming of the pixel circuit and compensate for a time dependent parameter of the pixel circuit.

A method of driving a display, the display comprising pixel circuits and driver circuitry for programming and driving the pixel circuit, each pixel circuit having a light emitting device, a capacitor, a first switch transistor, a second switch transistor and a driving transistor for driving the light emitting device, each transistor having a gate terminal, a first terminal and a second terminal, the capacitor having a first terminal and a second terminal, the gate terminal of the first switch transistor being connected to a first select line, one of the first and second terminals of the first switch transistor being connected to a signal line, the other terminal of the first switch transistor being connected to the first terminal of the capacitor, the gate terminal of the second switch transistor being connected to a second select line, one of the first and second terminals of the second switch transistor being connected to the second terminal of the capacitor and the light emitting device, the other terminal of the second switch transistor being connected to a bias line, the gate terminal of the driving transistor being connected to the first terminal of the capacitor;

• the method comprising:
• at a first operation of a programming cycle, the driver circuitry providing a bias voltage on the signal line and providing a controllable bias current, independent of said programming data for said pixel circuit, on the bias line;
• at a second operation of the programming cycle, the driver circuitry providing a programming voltage dependent on a programming data for said pixel circuit on the signal line,
• wherein said bias voltage and said programming voltage and said bias current accelerate the programming of the pixel circuit and compensate for a time dependent parameter of the pixel circuit.