Liquid crystal display device and video processing method thereof

• US 8,259,050 B2
• Filed: 08/10/2010
• Issued: 09/04/2012
• Est. Priority Date: 12/21/2009
• Status: Expired due to Fees

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Yun, Jae-Kyeong
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Trandai, Scott
• Application Number:
  US12/853,888
• Publication Number:
  US 20110149146A1
• Time in Patent Office: 756 Days
• Field of Search: 345 87-104, 345204-215, 345690-699, 348/790
• US Class Current: 345/89
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display device and a video processing method of the same are disclosed. A video processing method of a liquid crystal display device includes a first step determining whether a current frame is a motion picture by comparing data of a current frame with data of a previous frame; a second step converting and outputting a number of bits of a white gradation data of the current frame and outputting data of the other gradations without the bit conversion, if it is determined in the first step that the current frame is the motion picture; a third step outputting the data of the current frame without the bit-conversion if it is determined in the first step that the current frame is a still image; and a fourth step comparing the data of the current frame outputted in the second or third step with data of a previous frame and outputting overdriving control (ODC) data converted based on the result of the comparison.

Claims

1. A video processing method of a liquid crystal display device comprising:

a) determining whether a current frame is a motion picture by comparing data of a current frame with data of a previous frame;

b) converting and outputting a number of bits of a white gradation data of the current frame and outputting data of the other gradations without the bit-conversion, when it is determined in the first step that the current frame is the motion picture;

c) outputting the data of the current frame without the bit-conversion when it is determined in the first step that the current frame is a still image; and

d) comparing the output data from the second or third step with data of a previous frame and performing a conversion process to generate overdriving control (ODC) data when the compared data are not identical.

2. The video processing method of claim 1, wherein the a) determines that the current frame is the still image when the data of the current frame is identical to data of the previous frame and the first step determines that it is the motion picture when the data of the current frame is not identical to the data of the previous frame.

3. The video processing method of claim 1, wherein d) outputs the input data of the current frame not converted into the ODC data when it is determined in a) step that the current frame is the still image.

4. The video processing method of claim 1, further comprising:

e) step generating a plurality of reference gamma voltages by dividing an input voltage;

f) generating a plurality of gamma voltage by specifying the plurality of the reference gamma voltages; and

i) supplying an analog signal to data lines of a liquid crystal panel, the analog signal converted from the data outputted in d) by using the plurality of the gamma voltages.

5. The video processing method of claim 4, wherein the e) generates and outputs a reference gamma voltage of a top level gradation and a reference gamma voltage of a second top level gradation independently, and the top level reference gamma voltage and the second top level reference gamma voltage have a voltage difference in a range of at least 0.2˜

1 V, respectively.

6. The video processing method of claim 5, wherein b) decreases 1 bit of the white data detected from the motion picture and b) outputs the white data having the decreased 1 bit;

and

when random gradation data of the previous frame is converted into the white data having the decreased 1 bit, the white data having the decreased 1 bit is converted into ODC white data.

7. The video processing method of claim 6, wherein i),

selects and outputs the top level gamma voltage for the ODC white data of the motion picture;

and

selects and outputs the top level gamma voltage for white data of the still image.

8. The video processing method of claim 1, wherein d),

converts input data of the current frame into the ODC data decreased to be smaller than the data of the current frame, when the data of the current frame is smaller than the data of the previous frame;

converts input data of the current frame into the ODC data increased to be larger than the data of the current frame, when the data of the current frame is larger than the data of the previous frame; and

output the data of the current frame, when the data of the current frame is identical to the data of the previous frame.

9. A liquid crystal display device comprising:

a liquid crystal panel;

an video processor that converts and outputs a number of bits of a white gradation data of a current frame determined as motion picture based on determination whether data of a current frame is a motion picture or still image by comparing data of a current frame with data of a previous frame, and outputs data of the other gradations and data of a still image without the bit-conversion, and the video processor converts and outputs input data of the current frame into ODC data based on the result of comparison between the data of the current frame having the converted bit or not and the data of the previous frame;

a reference gamma voltage generator that generates a plurality of reference gamma voltages by dividing an input voltage; and

a data driver that generates a plurality of gamma voltages by specifying the plurality of the reference gamma voltages, the data driver supplies an analog signal converted from the data outputted from the video processor by using the plurality of the gamma voltages.

10. The liquid crystal display device of claim 9, wherein the video processor comprises,

a frame memory that delays data of the current frame and supplies the delayed data to the data of the previous frame;

a motion picture determiner that determines that the current frame is the still image when the data of the previous frame is identical to the data of the current frame and determines that it is the motion picture when not identical based on the result of comparison, after comparing the data of the previous frame with the data of the current frame;

a white converter that converts and outputs the number of bits of the white data of the current frame and outputs data of the other gradations without the bit-conversion, when it is determined by the motion picture determiner that the current frame is the motion picture, and the white converter outputs the data of the current frame without the bit-conversion, when it is determined by the motion picture determiner that it is the still image; and

an ODC circuit that compares the data of the current frame from the white converter and the data of the previous frame from the frame memory and outputs the ODC data converted based on the result of the comparison.

11. The liquid crystal display device of claim 10, wherein the ODC circuit outputs input data of the current frame without converting the input data into the ODC data, when it is determined by the motion picture determiner that the input data of the current frame is the still image.

12. The video processing method liquid crystal display device of claim 9, wherein the reference gamma voltage generator generates and outputs a reference voltage of a top level gradation and a reference gamma voltage of a second top gradation independently;

and

the top level reference gamma voltage and the second top level reference gamma voltage have a voltage difference in a range of at least 0.2˜

1 V, respectively.

13. The liquid crystal display device of claim 10, wherein the white converter decreases 1 bit of the white data detected from the motion picture and the white converter outputs the white data having the decreased 1 bit;

and the ODC circuit converts the white data having the decreased 1 bit into ODC white data, when data of a random gradation composing the previous frame is converted into the white data having the decreased 1 bit of the current frame.

14. The liquid crystal display device of claim 13, wherein the data driver selects and outputs the top level gamma voltage when the ODC white data is supplied from the video processor;

and

the data driver selects and outputs the top level gamma voltage when the white data of the still image is supplied from the video processor.

15. The liquid crystal display device of claim 13, wherein the ODC circuit converts the data of the current frame into the ODC data decreased to be smaller than the data of the current frame, when the data of the current frame is smaller than the data of the previous frame;

the ODC circuit converts the data of the current frame into the ODC data increased to be larger than the data of the current frame, when the data of the current frame is larger than the data of the previous data; and

the ODC circuit outputs the data of the current frame, when the data of the current frame is identical to the data of the previous frame.