SYSTEM AND METHOD FOR COMPENSATION OF NON-UNIFORMITIES IN LIGHT EMITTING DEVICE DISPLAYS

• US 20150002378A1
• Filed: 09/18/2014
• Published: 01/01/2015
• Est. Priority Date: 04/12/2005
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza, Alexander, Stefan, Servati, Peyman, Huang, Richard I-Heng, Church, Corbin
• Granted Patent: US 10,235,933 B2
• Time in Patent Office: Days
• US Class Current: 345/77
• 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 2320/0285 using tables for spatial correction of display data
• 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 2320/043 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 2320/0666 for control of colour parameters, e.g. colour temperature
• 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

Abstract

A display degradation compensation system and method for adjusting the operating conditions for pixels in an OLED display to compensate for non-uniformity or aging of the display. The system or method sets an initial value for at least one of peak luminance and an operating condition, calculates compensation values for the pixels in the display, determines the number of pixels having compensation values larger than a predetermined threshold compensation value, and if the determined number of pixels having compensation values larger than said predetermined threshold value is greater than a predetermined threshold number, adjusts the set value until said determined number of pixels is less than said predetermined threshold number.

Claims

1-30. -30. (canceled)

31. A display system comprising:

an array of pixel circuits;

a measurement circuit for measuring data from one of the pixel circuits;

a TFT-to-Pixel conversion algorithm module manipulating the measured data with at least one additional input to calculate luminance degradation; and

a compensation module for compensating for non-uniformity in the display system based on the calculated luminance degradation.

32. The display system of claim 31, wherein the TFT-to-Pixel conversion algorithm module allows for improved display parameters and wherein the compensation module further compensates for changes in the display system due to the at least one additional input.

33. The display system of claim 31, wherein the at least one additional input includes a temperature reading, a mechanical stress reading, an environmental stress reading, and feedback from a test structure in the display system.

34. The display of claim 31, wherein the TFT-to-Pixel conversion algorithm module further manipulates the measured data with one or more empirical parameters.

35. The display of claim 34, wherein the one or more empirical parameters include brightness loss in an organic light emitting device (OLED) of the one of the pixel circuits due to decreasing efficiency (Δ

L), shift in the OLED'"'"'s voltage over time (Δ

Voled), dynamic effects of Vt shift, parameters related to TFT performance including Vt, Δ

Vt, mobility (μ

), inter-pixel non-uniformity, DC bias voltages in the one of the pixel circuits, changing gain of current-mirror based pixel circuits, short-term and long-term based shifts in pixel circuit performance, pixel-circuit operating voltage variation due to IR-drop and ground bounce, or any combination thereof

36. The display of claim 31, wherein the non-uniformity in the display system includes a brightness non-uniformity or a color non-uniformity.

37. The display of claim 31, wherein the measured data includes TFT degradation data, OLED degradation data, or both.

38. The display system of claim 32, wherein the improved display parameters include brightness uniformity and color uniformity.