Stable driving scheme for active matrix displays

• US 9,633,597 B2
• Filed: 04/28/2014
• Issued: 04/25/2017
• Est. Priority Date: 04/19/2006
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza
• Primary Examiner(s): Pervan, Michael
• Application Number:
  US14/263,628
• Publication Number:
  US 20140266994A1
• Time in Patent Office: 1,093 Days
• Field of Search: 3151691-1694, 345 76- 84, 345 87-104, 345204, 345208-210
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element

Abstract

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.

Claims

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.