Method and device for compensating luminance deviation

Patent metadata

Field	Value
Publication number	US-11373573-B2
Application number	US-202117220790-A
Country	US
Kind code	B2
Filing date	Apr 1, 2021
Priority date	Apr 1, 2020
Publication date	Jun 28, 2022
Grant date	Jun 28, 2022

Abstract

The present disclosure relates to a method and a device for compensating for a luminance deviation, in which test pixel data is written to pixels disposed on a screen of a display panel and an image of the screen is captured, a luminance deviation is determined by analyzing luminance characteristics based on a measured luminance value of each of the pixels, which is obtained from data of the image of the screen captured by an imaging device, and a defective pixel is detected, and compensation data for reducing the luminance deviation between the pixels is derived for each pixel, so that a measured luminance value or compensation data of the defective pixel can be removed.

First claim

What is claimed is:

1. A luminance deviation compensation method comprising:
writing test pixel data to pixels on a screen of a display panel and capturing an image of the screen;
measuring parameters for defining a gamma curve of luminance characteristics of each of the pixels based on a measured luminance value of each of the pixels;
comparing a measurement value of each of the parameters with an allowable range for each parameter to determine whether the measurement value of each of the parameters exists within a corresponding preset allowable range;
detecting the pixel including luminance characteristics that are distinct from the luminance characteristics of normal pixels as a defective pixel based on the parameters that are outside the allowable range;
deriving compensation data for reducing the luminance deviation between the pixels for each pixel; and
removing the measured luminance value or the compensation data of the defective pixel.

2. The luminance deviation compensation method of claim 1 , wherein the luminance characteristics include parameters of an offset defined as x-axis segments of the gamma curve, a gain defined as y-axis segments of the gamma curve, and a curvature of the gamma curve, and
wherein the detecting the pixel including luminance characteristics that are distinct from the luminance characteristics of normal pixels as a defective pixel based on the parameters that are outside the allowable range includes:
determining the pixel in which each of the gain, the offset, and the curvature is within a corresponding allowable range, the pixel in which the curvature is within an allowable curvature range and the gain and the offset are respectively outside an allowable gain range and an allowable offset range, and the pixel in which the curvature and the gain are respectively within the allowable curvature range and the allowable gain range and the offset is outside the allowable offset range as the normal pixels; and
separating the defective pixel into a contaminated pixel and a failed pixel based on the parameters that are outside the allowable range.

3. The luminance deviation compensation method of claim 2 , further comprising setting the allowable gain range to be compared with the measurement value of the gain, the allowable offset range to be compared with the measurement value of the offset, and the allowable curvature range to be compared with the measurement value of the curvature,
wherein the detecting the pixel including luminance characteristics that are distinct from the luminance characteristics of normal pixels as a defective pixel based on the parameters that are outside the allowable range includes:
determining the pixel in which, among the gain, the offset, and the curvature, the gain is outside the allowable gain range and the offset and the curvature are respectively within the allowable offset range and the allowable curvature range as the contaminated pixel; and
determining the pixel in which the curvature is outside the allowable curvature range and at least one of the gain and the offset is outside the corresponding allowable range as the failed pixel,
wherein the failed pixel includes a dark spot pixel and a bright spot pixel, in which luminance is fixed regardless of gradation of the test pixel data.

4. The luminance deviation compensation method of claim 3 , wherein the removing measured luminance value or compensation data of the defective pixel further includes:
calculating compensation data of the contaminated pixel by an interpolation method using compensation data of each of neighboring pixels of the contaminated pixel; and
calculating compensation data of the failed pixel by an interpolation method using compensation data of each of neighboring pixels of the failed pixel or replacing the compensation data with zero.

5. The luminance deviation compensation method of claim 1 , further comprising:
deriving the compensation data for each pixel for compensating for a luminance value of the defective pixel, which is calculated by an interpolation method, and the measured luminance value of each of other pixels except for the defective pixel; and
storing the compensation data in a memory of a pixel driving circuit.

6. The luminance deviation compensation method of claim 5 , wherein in the removing measured luminance value or compensation data of the defective pixel, the luminance value of the defective pixel is interpolated by removing the measured luminance value of the defective pixel and calculating the luminance value of the defective pixel by an interpolation method using a measured luminance value of each of neighboring pixels of the defective pixel, or replacing the measured luminance value of the defective pixel with a preset specific value.

7. The luminance deviation compensation method of claim 5 , further comprising:
determining the luminance deviation between the pixels based on image data of the screen, which is obtained by capturing an image of the screen to which the compensation data is applied, and re-capturing an image of the screen by adjusting the compensation data at least one time until the luminance deviation is reduced within a preset allowable range; and
updating the compensation data stored in the memory when the compensation data is adjusted.

8. The luminance deviation compensation method of claim 1 , further comprising:
deriving compensation data for compensating for the measured luminance value of each of the pixels by pixel; and
storing the compensation data in a memory of a pixel driving circuit,
wherein in the removing measured luminance value or compensation data of the defective pixel, the compensation data of the defective pixel is interpolated by removing the compensation data of the defective pixel and calculating the compensation data of the defective pixel by an interpolation method using compensation data of each of neighboring pixels of the defective pixel, or replacing the compensation data of the defective pixel with a preset specific value.

9. A luminance deviation compensation device including a compensation device configured to write test pixel data to pixels disposed on a screen of a display panel and capture an image of the screen using an imaging device, wherein the compensation device comprises:
a defective pixel detection unit configured to determine a luminance deviation by analyzing luminance characteristics based on a measured luminance value of each of the pixels, which is obtained from image data of the screen, and detect defective pixels; and
a compensation unit configured to derive compensation data for each pixel for reducing the luminance deviation between the pixels and remove a measured luminance value or compensation data of the defective pixel,
wherein the luminance characteristics include parameters of an offset defined as x-axis segments of a gamma curve, a gain defined as y-axis segments of the gamma curve, and a curvature of the gamma curve, and
wherein the compensation unit is configured to:
determine each of the pixel in which each of the gain, the offset, and the curvature is within a corresponding allowable range, the pixel in which the curvature is within an allowable curvature range and the gain and the offset are respectively outside an allowable gain range and an allowable offset range, and the pixel in which the curvature and the gain are respectively within the allowable curvature range and the allowable gain range and the offset is outside the allowable offset range as a normal pixel; and
separate the defective pixel into a contaminated pixel and a failed pixel based on the parameters that are outside the allowable range.

10. The luminance deviation compensation

Assignees

• Lg Display Co Ltd

Inventors

• Park Ji Hoon

Classifications

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2360/16

  Calculation or use of calculated indices related to luminance levels in display data · CPC title

• G06T2207/30121

  CRT, LCD or plasma display · CPC title

• G09G3/20 Primary

  for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters} · CPC title

• G09G2320/0276

  for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction · CPC title