Method of driving display panel and display apparatus performing the same

Patent metadata

Field	Value
Publication number	US-2016104408-A1
Application number	US-201514678091-A
Country	US
Kind code	A1
Filing date	Apr 3, 2015
Priority date	Oct 14, 2014
Publication date	Apr 14, 2016
Grant date	—

Abstract

A method for driving a display panel includes obtaining a first grayscale histogram based on input image data, generating a gamma curve by selectively changing an initial gamma curve based on at least one of the first grayscale histogram or a predetermined power mode, and generating output image data based on the input image data and the gamma curve. When the gamma curve is different from the initial gamma curve, the method includes changing an operating frequency of the display panel from a first frequency to a second frequency. The second frequency is lower than the first frequency. The operating frequency is changed to display an image frame corresponding to the output image data based on the second frequency.

First claim

What is claimed is:

1 . A method for driving a display panel, the method comprising:
obtaining a first grayscale histogram based on input image data; generating a gamma curve by selectively changing an initial gamma curve based on at least one of the first grayscale histogram or a predetermined power mode; generating output image data based on the input image data and the gamma curve; and when the gamma curve is different from the initial gamma curve, changing an operating frequency of the display panel from a first frequency to a second frequency, wherein the second frequency is lower than the first frequency and wherein the operating frequency is changed to display an image frame corresponding to the output image data based on the second frequency.

2 . The method as claimed in claim 1 , wherein generating the gamma curve includes:
selecting a first gamma lookup table, among a plurality of gamma lookup tables, based on a number of first pixels in the first grayscale histogram, the first pixels having grayscale values in a first range that is between second and third ranges of grayscale values; and mapping the initial gamma curve into the gamma curve based on the first gamma lookup table.

3 . The method as claimed in claim 2 , wherein:
when the number of the first pixels in the first grayscale histogram is greater than a reference number, the gamma curve is different from the initial gamma curve after mapping, and when the number of the first pixels in the first grayscale histogram is equal to or less than the reference number, the gamma curve is substantially equal to the initial gamma curve after mapping.

4 . The method as claimed in claim 3 , wherein:
when the gamma curve is different from the initial gamma curve after mapping, a number of second pixels in a second grayscale histogram is less than the number of the first pixels, the second grayscale histogram is based on the output image data, and the second pixels have grayscale values in the first range.

5 . The method as claimed in claim 3 , wherein:
when the gamma curve is different from the initial gamma curve after mapping, a difference between the initial gamma curve and the gamma curve increases based on a lapse of time.

6 . The method as claimed in claim 3 , wherein:
when the gamma curve is different from the initial gamma curve after mapping, and when the operating frequency of the display panel is changed from the first frequency to the second frequency, the second frequency decreases based on a lapse of time.

7 . The method as claimed in claim 1 , wherein generating the gamma curve includes:
selecting a first gamma lookup table, among a plurality of gamma lookup tables, based on whether the predetermined power mode is enabled; and mapping the initial gamma curve to the gamma curve based on the first gamma lookup table.

8 . The method as claimed in claim 7 , wherein:
when at least one of a plurality of power mode selection signals corresponding to the predetermined power mode is activated, the gamma curve is different from the initial gamma curve after mapping, and when all of the plurality of power mode selection signals are deactivated, the gamma curve is substantially equal to the initial gamma curve after mapping.

9 . The method as claimed in claim 1 , further comprising:
determining the operating frequency of the display panel as the first frequency based on the input image data and the first grayscale histogram.

10 . The method as claimed in claim 9 , wherein determining the operating frequency of the display panel includes:
when the input image data corresponds to a first type for a first predetermined frequency operation, setting the first frequency to be lower than a reference frequency; and when the input image data corresponds to a second type for a second predetermined frequency operation, setting the first frequency to be higher than the reference frequency.

11 . The method as claimed in claim 1 , further comprising:
when the gamma curve is substantially equal to the initial gamma curve, maintaining the operating frequency of the display panel as the first frequency to display the image frame corresponding to the output image data on the display panel based on the first frequency.

12 . A display apparatus, comprising:
a display panel; and a timing controller to control an operation of the display panel, wherein the timing controller includes: an image analyzer to obtain a first grayscale histogram based on the input image data; a gamma compensator to generate a gamma curve by selectively changing an initial gamma curve based on at least one selected from the first grayscale histogram and a predetermined power mode; an image processor to generate output image data based on the input image data and the gamma curve; and an operating frequency selector to change an operating frequency of the display panel from a first frequency to a second frequency lower than the first frequency when the gamma curve is different from the initial gamma curve, wherein, when the gamma curve is different from the initial gamma curve, an image frame corresponding to the output image data is displayed on the display panel based on the second frequency.

13 . The display apparatus as claimed in claim 12 , wherein the gamma compensator includes:
a gamma storage area to store the first grayscale histogram; a gamma selector to select a first gamma lookup table among a plurality of gamma lookup tables; and a gamma mapper to map the initial gamma curve into the gamma curve based on the first gamma lookup table.

14 . The display apparatus as claimed in claim 13 , wherein the gamma compensator includes:
a histogram analyzer to detect a number of first pixels in the first grayscale histogram, the first pixels having grayscale values in a first range between second and third ranges of grayscale values, wherein the gamma selector is to select the first gamma lookup table based on the number of the first pixels in the first grayscale histogram.

15 . The display apparatus as claimed in claim 14 , wherein:
when the number of the first pixels in the first grayscale histogram is greater than a reference number, the gamma curve is different from the initial gamma curve after mapping, and when the number of the first pixels in the first grayscale histogram is equal to or less than the reference number, the gamma curve is substantially equal the initial gamma curve after mapping.

16 . The display apparatus as claimed in claim 15 , wherein:
when the gamma curve is different from the initial gamma curve after mapping, a number of second pixels in a second grayscale histogram is less than the number of the first pixels, the second grayscale histogram is obtained based on the output image data, and the second pixels have grayscale values in the first range.

17 . The display apparatus as claimed in claim 13 , wherein the gamma selector is to receive a plurality of power mode selection signals corresponding to the predetermined power mode and is to select the first gamma lookup table based on whether the predetermined power mode is enabled.

18 . The display apparatus as claimed in claim 17 , wherein:
when at least one of the plurality of power mode selection signals is activated, the gamma curve is different from the initial gamma curve after mapping, and when all of the plurality of power mode selection signals are deactivated, the gamma curve is substantially equal to the initial gamma curve after mapping.

1

Assignees

• Samsung Display Co Ltd

Inventors

• Kim Gi-Geun
• Park Geun-Jeong
• Choi Nam-Gon

Classifications

• G09G2320/0673

  for control of gamma adjustment, e.g. selecting another gamma curve · CPC title

• G09G3/2003 Primary

  Display of colours (specific for liquid crystal displays G09G3/3607) · CPC title

• G09G3/36 Primary

  using liquid crystals · CPC title

• G09G2340/0435

  Change or adaptation of the frame rate of the video stream · CPC title

• G09G2330/022

  in absence of operation, e.g. no data being entered during a predetermined time · CPC title