OLED luminance degradation compensation

• US 8,581,809 B2
• Filed: 10/01/2012
• Issued: 11/12/2013
• Est. Priority Date: 08/15/2006
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Marinelli, Patrick F
• Application Number:
  US13/632,691
• Publication Number:
  US 20130057595A1
• Time in Patent Office: 407 Days
• Field of Search: 345 76- 83, 345204-215, 345690-699, 3151691-1694
• US Class Current: 345/78
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• 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 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H05B 45/60 Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]

Abstract

A system and method are disclosed for determining a pixel capacitance. The pixel capacitance is correlated to a pixel age to determine a current correction factor used for compensating the pixel drive current to account for luminance degradation of the pixel that results from the pixel aging.

Claims

1. A control block for compensating for luminance degradation of a pixel having an electroluminescent device, the control block being configured to:

determine a capacitance of the electroluminescent device;

correlate the determined capacitance of the electroluminescent device to a current correction factor for the electroluminescent device;

compensate a drive current for the electroluminescent device according to the correlated current correction factor; and

drive the electroluminescent device with the compensated drive current.

2. The control block as claimed in claim 1, wherein the pixel is one of a plurality of pixels arranged in an array to form a display.