Method and system for programming, calibrating and/or compensating, and driving an LED display

• US 10,013,907 B2
• Filed: 08/03/2015
• Issued: 07/03/2018
• Est. Priority Date: 12/15/2004
• 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
• Primary Examiner(s): Allgood, Alesa
• Application Number:
  US14/816,817
• Publication Number:
  US 20160104411A1
• Time in Patent Office: 1,065 Days
• Field of Search: 345 76, 345 77, 3151693, 313504, 257E27111, 32475607, 32476209
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• 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 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• 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 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/3225 using an active matrix
• 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: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A method and system for programming, calibrating and driving a light emitting device display, and for operating a display at a constant luminance even as some of the pixels in the display are degraded over time. The system may include extracting a time dependent parameter of a pixel for calibration. Each pixel in the display is configured to emit light when a voltage is supplied to the pixel'"'"'s driving circuit, which causes a current to flow through a light emitting element. Degraded pixels are compensated by supplying their respective driving circuits with greater voltages. The display data is scaled by a compression factor less than one to reserve some voltage levels for compensating degraded pixels. As pixels become more degraded, and require additional compensation, the compression factor is decreased to reserve additional voltage levels for use in compensation.

Claims

1. A method of operating a display having a plurality of pixels to compensate for a degradation of the plurality of pixels, wherein the plurality of pixels have driving circuits for driving currents through light emitting devices based on inputs, the method comprising:

receiving a video signal having a set of grayscale values for the plurality of pixels;

dynamically adjusting a grayscale compression factor according to at least one input received after usage of the display, the grayscale compression factor greater than zero and less than one;

compressing the video signal using the grayscale compression factor to produce compressed grayscale values so as to use fewer luminance values than in the original video signal and reserving a remaining amount of grayscale values for future adjustments associated with aging;

compensating said compressed grayscale values for degradation of said display, using at least a portion of said reserved grayscale values; and

outputting the compensated compressed grayscale values to a display driver for programming the driving circuits of the plurality of pixels.

2. The method of claim 1, wherein the set of grayscale values is eight-bit data, and wherein the compressing is carried out according to a grayscale compression algorithm that translates the set of compressed grayscale values having a range of 200 values.

3. The method of claim 1, wherein the remaining amount of grayscale values are reserved at a high end of the available range to provide adjustments that increase the luminosity of adjusted pixels.

4. The method of claim 1, wherein the remaining amount of grayscale values are reserved at a low end of the available range to provide adjustments that decrease the luminosity of adjusted pixels.

5. The method of claim 1, further comprising:

adjusting a value in the set of grayscale values corresponding to at least one of the plurality of pixels according to a decreasing brightness algorithm.

6. The method of claim 1, further comprising:

adjusting a value in the set of grayscale values corresponding to at least one of the plurality of pixels according to a constant brightness algorithm.

7. The method of claim 1, wherein said compensating said compressed grayscale values for degradation of said display includes compensating at least one of said compressed grayscale values for degradation of at least one of the plurality of pixels of the display, each one of the at least one of said compressed grayscale values compensated for degradation of an associated respective one of the at least one of the plurality of pixels of the display.