Adaptive feedback system for compensating for aging pixel areas with enhanced estimation speed

• US 9,466,240 B2
• Filed: 11/08/2011
• Issued: 10/11/2016
• Est. Priority Date: 05/26/2011
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Jaffari, Javid, Chaji, Gholamreza, Heidari, Abdorreza
• Primary Examiner(s): POLO, GUSTAVO D
• Application Number:
  US13/291,486
• Publication Number:
  US 20120299973A1
• Time in Patent Office: 1,799 Days
• Field of Search: 345/690
• US Class Current: 1/1
• 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 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 2320/043 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 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• 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
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• 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

Abstract

A local priority-based scanning scheme that focuses scanning to areas of a display panel whose measured characteristics are under continuous change (e.g., aging or relaxation). The algorithm identifies areas or regions needing compensation, using a current measurement from a single pixel in an area as a candidate to determine whether the rest of the region needs further compensation. The algorithm thus detects newly changed areas quickly, focusing time-consuming measurements on those areas that need high attention. Optionally, neighboring pixels sharing the same state (e.g., aging or overcompensated) as the measured pixel can be adjusted automatically given the likelihood that the neighboring pixels will also require compensation if the measured pixel needs compensation.

Claims

1. A method of discriminating areas that are deviating from a previous state or from a previously measured reference value, the areas being areas of a display panel of pixels organized into clusters of pixels, the method comprising:

scanning each of a plurality of pixels in a first cluster until a first criterion is satisfied, the scanning including, for each of the plurality of pixels;

measuring a respective characteristic of a target one of the plurality of scanned pixels in the first cluster;

comparing the respective measured characteristic with a reference characteristic to determine a respective state of the target pixel; and

if the respective state of the target pixel has changed relative to a prior measurement of the target pixel, determining that the first criterion is satisfied; and

responsive to the first criterion being satisfied, automatically compensating for deviations of the respective measured characteristic of each of the plurality of scanned pixels in the first cluster based at least on the respective state of the scanned pixel to shift the respective measured characteristic toward the reference characteristic.

2. The method of claim 1, wherein the pixels of the display are further organized into a plurality of regions, each of at least some of the regions having a plurality of clusters of pixels, wherein the scanning is carried out in at least one cluster in each of the regions, wherein the first criterion is satisfied responsive to the state of at least one of the pixels in each of the regions changing relative to a prior measurement of the at least one pixel, wherein the state indicates at least whether the target pixel is in an aging state indicating that the target pixel is aging, and wherein the automatically compensating compensates for an aging or an overcompensation of at least one of the pixels in the first cluster.

3. The method of claim 1, wherein the measured characteristic is a current used to drive a light emitting device in the target pixel, wherein the scanning is carried out according to a scan order starting at a top-right pixel and ending at a bottom-left pixel in the first cluster.

4. The method of claim 1, wherein the measuring is carried out on only some of the pixels in the first cluster prior to carrying out the automatically compensating.

5. The method of claim 1, further comprising:

prioritizing the first cluster as a function of the respective states of each of the measured pixels in the first cluster to produce a priority value.

6. The method of claim 5, wherein the state further indicates whether the target pixel is in an overcompensated state, wherein the function includes determining an absolute difference of the number of measured pixels in the first cluster that are in the overcompensated state versus the number of measured pixels in the first cluster that are in an aging state.

7. The method of claim 5, further comprising:

determining a number of additional pixels to be measured in the first cluster based on the priority value such that a higher priority value indicates more additional pixels to be measured in the first cluster; and

measuring a characteristic of each of the additional pixels to determine the state of each of the additional pixels.

8. The method of claim 7, wherein the state further indicates whether the target pixel is in an overcompensated state, wherein the function includes determining an absolute difference of the number of measured pixels in the first cluster that are in the overcompensated state versus the number of measured pixels in the first cluster that are in an aging state, and wherein the number of additional pixels is zero responsive to the absolute difference not exceeding a minimum threshold indicative of whether additional pixels are to be measured in the first cluster.

9. The method of claim 7, further comprising:

responsive to the priority value exceeding a threshold, adjusting a corresponding absolute aging value associated with those of neighboring pixels to the measured pixel that share the same state as the measured pixel, the absolute aging value being indicative of an extent to which the measured pixel is aged or overcompensated.

10. The method of claim 9, further comprising reducing, for each of the neighboring pixels whose absolute aging value has been adjusted, a coefficient of an average filter associated with each of the neighboring pixels whose absolute aging value has been adjusted.

11. The method of claim 9, wherein the adjusting includes incrementing by one the absolute aging value responsive to the state of the measured pixel being in the aging state and decrementing by one the absolute aging value responsive to the state of the measured pixel being in the overcompensated state.

12. The method of claim 9, wherein the absolute aging value is adjusted by a constant value or as a function of the priority value such that the absolute aging value is adjusted by a larger amount for higher priority values relative to lower priority values.

13. The method of claim 2, further comprising:

prioritizing the at least one cluster in each of the regions as a function of the respective states of each of the measured pixels in the corresponding ones of the measured clusters to produce for each of the regions a corresponding priority value.

14. The method of claim 13, wherein the state includes whether the target pixel is in an overcompensated state, wherein the function includes determining an absolute difference of the number of measured pixels in each of the at least one cluster in each of the regions that are in the overcompensated state versus the number of measured pixels in each of the at least one cluster in each of the regions that are in an aging state, the absolute difference corresponding to the priority value.

15. The method of claim 14, further comprising, for each of the regions, determining a number of additional pixels to be measured in the corresponding at least one cluster based on the priority value such that a higher priority value indicates more additional pixels to be measured in the corresponding at least one cluster.

16. The method of claim 1, wherein the target pixel in the first cluster is on a first row in the first cluster, the scanning further including, during a frame, measuring a characteristic of a second target one of the pixels in the first cluster, the second target pixel being present on a second row distinct from the first row in the first cluster.

17. The method of claim 7, wherein each of the additional pixels are on different consecutive or non-consecutive rows within the first cluster, the measuring the characteristic of each of the additional pixels being carried out on at least two of the additional pixels on the different rows during a frame.

18. The method of claim 1, wherein the state further indicate whether the target pixel is in an aging or overcompensated state.

19. The method of claim 1, wherein the measured characteristic is a current drawn by a light emitting device in the target pixel and the reference characteristic is a reference current.

20. The method of claim 19, wherein the reference current is a current drawn by a reference pixel in the display panel.

21. A method of prioritizing areas of high probability of deviations from a previously measured value or a reference value of a characteristic of areas of pixels of a display panel of pixels, comprising:

measuring a characteristic of at least some of the pixels of the display panel;

comparing the measured characteristic for each of the measured pixels with a corresponding reference characteristic to determine a corresponding state of each of the measured pixels;

prioritizing the areas of the display panel as a function of the state of the measured pixels in each of the areas to produce a priority order; and

automatically compensating for a deviation by the measured characteristic from the reference characteristic in the areas according to the priority order,

wherein each of the measured pixels has a respective measured characteristic and a respective state, and further wherein each of the measured pixels is automatically compensated for deviations of the respective measured characteristic of the measured pixel based at least on the respective state of the measured pixel.

22. The method of claim 21, further comprising:

scanning each of the at least some of the pixels in a first cluster until a first criterion is satisfied, the scanning including;

comparing the measured characteristic with a reference characteristic to determine a state of a target pixel in the first cluster, the state indicating at least whether the target pixel is in an aging state indicating that the target pixel is aging; and

if the state of the target pixel has changed relative to a prior measurement of the target pixel, determining that the first criterion is satisfied, wherein

the automatically compensating is based at least on the state of the scanned pixels and compensates for an aging or an overcompensation of the areas.

23. The method of claim 22, wherein the pixels of the display are further organized into a plurality of regions, each of at least some of the regions having a plurality of clusters of pixels, wherein the scanning is carried out in at least one cluster in each of the regions, and wherein the first criterion is satisfied responsive to the state of at least one of the pixels in each of the regions changing relative to a prior measurement of the at least one pixel.

24. The method of claim 22, wherein the measured characteristic is a current used to drive a light emitting device in the target pixel and the reference characteristic is a reference current, wherein the scanning is carried out according to a scan order starting at a top-right pixel and ending at a bottom-left pixel in the first cluster.

25. The method of claim 22, wherein the state indicates whether the target pixel is in an aging or an overcompensated state, wherein the function includes determining an absolute difference of the number of measured pixels in the first cluster that are in the overcompensated state versus the number of measured pixels in the first cluster that are in the aging state.

26. The method of claim 22, wherein the prioritizing includes prioritizing the first cluster as a function of the respective states of each of the measured pixels in the first cluster to produce a priority value, the method further comprising:

determining a number of additional pixels to be measured in the first cluster based on the priority value such that a higher priority value indicates more additional pixels to be measured in the first cluster; and

measuring a characteristic of each of the additional pixels to determine the state of each of the additional pixels.

27. The method of claim 26, wherein the state indicates whether the target pixel is in an aging or an overcompensated state, wherein the function includes determining an absolute difference of the number of measured pixels in the first cluster that are in the overcompensated state versus the number of measured pixels in the first cluster that are in the aging state, and wherein the number of additional pixels is zero responsive to the absolute difference not exceeding a minimum threshold indicative of whether additional pixels are to be measured in the first cluster.

28. The method of claim 26, wherein the state indicates whether the target pixel is in an aging or an overcompensated state, the method further comprising:

responsive to the priority value exceeding a threshold, adjusting a corresponding absolute aging value associated with those of neighboring pixels to the measured pixel that share the same state as the measured pixel, the absolute aging value corresponding to a value indicating an extent to which a pixel is aging or overcompensated.

29. The method of claim 28, further comprising reducing, for each of the neighboring pixels whose absolute aging value has been adjusted, a coefficient of an average filter associated with each of the neighboring pixels whose absolute aging value has been adjusted.

30. The method of claim 28, wherein the adjusting includes incrementing by one the absolute aging value responsive to the state of the measured pixel being in the aging state and decrementing by one the absolute aging value responsive to the state of the measured pixel being in the overcompensated state.

31. The method of claim 28, wherein the absolute aging value is adjusted by a constant value or as a function of the priority value such that the absolute aging value is adjusted by a larger amount for higher priority values relative to lower priority values.

32. A method of updating an estimated aging of neighboring pixels of a display panel using a known measurement of a pixel, the display panel being organized into clusters of pixels, the method comprising:

measuring a characteristic of each pixel in a first cluster of the clusters of the display panel;

for each pixel in the cluster, comparing the measured characteristic of the pixel with a reference characteristic to determine a state of the pixel, the state indicating whether the pixel is in an aging state, an overcompensated state, or neither;

if the state of a selected pixel in the cluster is unchanged relative to a prior measurement of the selected pixel and the state of the selected pixel is the same as the state of the majority of other pixels in the cluster, adjusting corresponding aging values associated with neighboring pixels to the selected pixel, each of the aging values representing an aging or a relaxation state of a pixel and stored in a memory coupled to the display panel; and

automatically compensating for an aging or relaxation of the display panel based at least in part on the aging values of the neighboring pixels.

33. The method of claim 32, further comprising reducing, for each of the neighboring pixels whose aging value has been adjusted, a coefficient of an average filter associated with each of the neighboring pixels whose aging value has been adjusted.

34. The method of claim 32, wherein the neighboring pixels are immediately adjacent to the selected pixel.

35. A method of selectively scanning areas of a display panel having pixels and divided into a plurality of clusters of pixels, the method comprising:

scanning at least some of the clusters in a first phase until a first criterion is satisfied, the scanning including;

measuring a characteristic of a target pixel in the cluster being scanned according to a pixel scanning order;

comparing the measured characteristic with a reference characteristic to produce a state of the target pixel, the state indicating whether the target pixel is in an aging state, a relaxation state, or neither;

responsive to the state for the target pixel differing from a previous state for the target pixel, determining that the first criterion is satisfied; and

responsive to a predetermined number of target pixels in the cluster being scanned, determining that the first criterion is satisfied; and

responsive to the first criterion being satisfied, further scanning at least one of the clusters, the further scanning including;

determining a priority for scanning additional pixels as a function of the extent of aging or relaxation of the cluster being scanned;

measuring the characteristic of a number of additional target pixels in the cluster being scanned, wherein the number of additional target pixels is a function of the priority; and

adjusting corresponding aging values associated with neighboring pixels to the target pixel, each of the aging values representing an aging or a relaxation state of a pixel and stored in a memory, responsive to the state of the target pixel being the same as the state of a majority of the other pixels in the cluster being scanned,

wherein the at least one of the clusters that that is further scanned includes at least one of the at least some of the clusters in the first phase.