Liquid crystal display device using different methods according to type of image signals and method of driving the same

• US 8,749,467 B2
• Filed: 07/19/2010
• Issued: 06/10/2014
• Est. Priority Date: 12/11/2009
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd., LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Young-Ho, Lee, Song-Jae
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): STONE, ROBERT M
• Application Number:
  US12/838,651
• Publication Number:
  US 20110141153A1
• Time in Patent Office: 1,422 Days
• Field of Search: 345/99, 345/96
• US Class Current: 345/99
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0613 The adjustment depending on the type of the information to be displayed
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display device includes: a liquid crystal panel that displays images using a plurality of pixels each including red, green and blue sub-pixels; a gate driving portion that supplies a gate signal to the liquid crystal panel; a data driving portion that supplies a data signal to the liquid crystal panel; and a timing control portion that compares difference of gray level between image signals corresponding to the red, green and blue sub-pixels with a first threshold value and compares difference of gray level between the image signals corresponding to the red, green and blue sub-pixels of neighboring pixels of the plurality of pixels in order to judge type of the image signals, and drives the data driving portion in different methods according to the type of the image signals.

Claims

1. A liquid crystal display device, comprising:

a liquid crystal panel that displays images using a plurality of pixels each pixel including red, green, and blue sub-pixels;

a gate driving portion that supplies a gate signal to the liquid crystal panel;

a data driving portion that supplies a data signal to the liquid crystal panel; and

a timing control portion that compares differences of gray levels between image signals corresponding to the red, green, and blue sub-pixels with a first threshold value and compares differences of gray levels between the image signals corresponding to the red, green, and blue sub-pixels of neighboring pixels of the plurality of pixels with a second threshold value in order to judge a type of the image signals, and drives the data driving portion in different methods according to the type of the image signals,

wherein the timing control portion includes;

a pattern recognition portion that judges that the type of the image signals is a first or a second pattern; and

a driving method determination portion that drives the data driving portion in a first or a second method according to a judgment result of the pattern recognition portion, and

wherein when the red, green, and blue sub-pixels of the neighboring pixels are Rn−

1, Gn−

1, and Bn−

1, and Rn, Gn, and Bn, respectively, and

wherein the pattern recognition portion judges as the first pattern the type of the image signals that meet a first condition ([|gray level of (Rn)−

gray level of (Gn)|≦

first threshold value] &

[|gray level of (Gn)−

gray level of (Bn)|≦

first threshold value] &

[|gray level of (Bn)−

gray level of (Rn)|≦

first threshold value]), and a second condition ([|gray level of (Rn−

1)−

gray level of (Rn)|≧

second threshold value] &

[|gray level of (Gn−

1)−

gray level of (Gn)|≧

second threshold value] &

[|gray level of (Bn−

1)−

gray level of (Bn)|≧

second threshold value]), and judges as the second pattern the type of the image signals that do not meet the first and the second conditions.

2. The device according to claim 1, wherein the image signal is represented in 8 or 10-bit digital code, and the timing control portion compares the differences of gray level with respect to upper 6 or 8 bits of the image signal with the respective first and second threshold values.

3. The device according to claim 1, wherein the first pattern is a gray pattern in which different grays are arranged in stripe form, wherein the first method is a horizontal or vertical line inversion method, and the second driving method is a dot inversion method, and wherein whether or not a charge sharing is performed is determined according to the judgment result of the pattern recognition portion.

4. The device according to claim 3, further comprising:

a system portion that includes an image signal supply portion that supplies the image signals, and a video modulation portion that modulates the image signals for 60 Hz into the image signals for 120 Hz or 240 Hz; and

a storing portion that stores the first method.

5. A method of driving a liquid crystal display device, comprising:

comparing differences of gray levels between image signals corresponding to red, green, and blue sub-pixels of a pixel with a first threshold value through a timing control portion;

comparing differences of gray levels between the image signals corresponding to the red, green, and blue sub-pixels of the pixel and a neighboring pixel with a second threshold value through the timing control portion;

judging a type of the image signals through the timing control portion according to a comparison result;

supplying from the timing control portion a data control signal and RGB data signals to a data driving portion and a gate control signal to a gate driving portion according to the type of the image signals;

supplying from the gate and the data driving portions gate and data signals, respectively, to a liquid crystal panel; and

displaying an image using the gate and the data signals through the liquid crystal panel,

wherein the timing control portion judges that the type of the image signals is a first or a second pattern, and determines to display the first or the second pattern in a first or a second driving method, and

wherein when the red, green and blue sub-pixels of the neighboring pixels are Rn−

1, Gn−

1, and Bn−

1, and Rn, Gn, and Bn, respectively, the pattern recognition portion judges as the first pattern the type of the image signals that meet a first condition ([|gray level of (Rn)−

gray level of (Gn)|≦

first threshold value] &

[|gray level of (Gn)−

gray level of (Bn)|≦

first threshold value] &

[|gray level of (Bn)−

gray level of (Rn)|≦

first threshold value]), and a second condition ([|gray level of (Rn−

1)−

gray level of (Rn)|≧

second threshold value] &

[|gray level of (Gn−

1)−

gray level of (Gn)|≧

second threshold value] &

[|gray level of (Bn−

1)−

gray level of (Bn)|≧

second threshold value]), and judges as the second pattern the type of the image signals that do not meet the first and the second conditions.

6. The method according to claim 5, wherein the image signal is represented in 8 or 10-bit digital code, and the timing control portion compares the differences of gray level with respect to upper 6 or 8 bits of the image signal with the respective first and second threshold values.