Liquid crystal display and driving method thereof

• US 7,880,703 B2
• Filed: 04/30/2007
• Issued: 02/01/2011
• Est. Priority Date: 05/01/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Jin, Hyun Suk, Park, Joon Kyu, Jang, Hyun Seok, You, Sook Kyung
• Primary Examiner(s): Dharia; Prabodh M
• Application Number:
  US11/797,083
• Publication Number:
  US 20070252801A1
• Time in Patent Office: 1,373 Days
• Field of Search: 345/72, 345/84, 345 87- 89, 345/96, 345/204, 345/597, 345/690, 345/691, 349/65, 349/106, 349110-114, 349/129, 349/145, 349/78, 349/179, 349/180
• US Class Current: 345/87
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2300/0491 Use of a bi-refringent liquid crystal, optically controlled bi-refringence [OCB] with bend and splay states, or electrically controlled bi-refringence [ECB] for controlling the color
• 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 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/068 for control of viewing angle adjustment
• CPC Class Codes: G09G 2320/0686 with two or more screen areas displaying information with different brightness or colours
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display for automatically adjusting brightness of interference image displayed at ECB sub pixels of quad type cells of a liquid crystal display panel in accordance with brightness of a background screen is disclosed. The liquid crystal display includes first to n-th look-up tables each holding a mapping of one first to n-th mappings of ECB brightness data to cell location information for the quad cells of the liquid crystal display panel; an image processor that calculates a brightness data distribution of an image; and a viewing angle controller that selects one of the first to the n-th look-up tables depending on the calculated brightness data distribution.

Claims

1. A liquid crystal display, comprising:

a liquid crystal display panel having quad cells each including a R sub pixel, a G sub pixel, a B sub pixel, and an ECB sub pixel;

a storage means that stores first to n-th look-up tables each holding a mapping of one of first to n-th mappings of ECB brightness data to cell location information for the quad cells of the liquid crystal display panel;

an image processor that calculates a brightness data distribution of an image to be displayed using the liquid crystal display panel using input RGB data for one frame period;

a viewing angle controller that selects one of the first to the n-th look-up tables, the selected look-up table depending on the calculated brightness data distribution; and

a data aligner that combines ECB brightness data received from a look-up table selected by the viewing angle controller with the input RGB data, and then aligns the combined RGB data and ECB brightness data for display in accordance with a quad cell structure.

2. The liquid crystal display as claimed in claim 1, wherein, the first to the n-th look-up tables are selectively selected by viewing angle controller to output ECB brightness data set to thereof to the data aligner.

3. The liquid crystal display as claimed in claim 1, wherein the image processor detects brightness data of an entire image to be displayed for one frame from the input RGB data and calculates a brightness data distribution of the entire image using the detected brightness data, and outputs the calculated brightness data distribution to the viewing angle controller.

4. The liquid crystal display as claimed in claim 1, wherein the image processor samples input RGB data for a specific area of an entire image to be displayed one frame to detect a brightness data of the sampled image and calculates a brightness data distribution of an image to be displayed at a specific area using the detected brightness data and outputs the brightness data distribution to the viewing angle controller.

5. The liquid crystal display as claimed 1, claim 1, wherein the viewing angle controller stores predetermined first to n-th reference brightness data having the same brightness value as the first to the n-th ECB brightness data.

6. The liquid crystal display as claimed in claim 5, wherein the viewing angle controller compares the calculated brightness data distribution with the predetermined first to n-th reference brightness data to detect a reference brightness data having the same value or the approximate value as the calculated brightness data distribution.

7. The liquid crystal display as claimed in claim 6, wherein the viewing angle controller selects a look-up table that the same ECB brightness data as the reference brightness data detected from the first to n-th look-up tables are set.

8. The liquid crystal display as claimed in claim 1, wherein the data aligner includes:

a mixer that mixing ECB brightness data output from a look-up table selected by the viewing angle controller using the input RGB data from the first to n-th look-up tables; and

a data aligner that aligns RGB data and ECB brightness data mixed by the mixer in accordance with the cell structure of quad cell to output aligned RGB data and ECB brightness data.

9. A liquid crystal display, comprising:

a liquid crystal display panel having quad cells each including a R sub pixel, a G sub pixel, a B sub pixel, and an ECB sub pixel;

a timing controller that calculates a brightness data distribution of an image using input RGB data, and that selects any one of first to n-the ECB data, the selected ECB data chosen with reference to the calculated brightness data distribution, and that aligns and outputs the selected ECB data brightness and the input RGB data in accordance with a cell structure of a quad cell;

a data driver that converts digital RGB data and ECB data output from the timing controller into an analog data to supply the analog data to the liquid crystal display panel in response to a control signal from the timing controller; and

a gate driver that selects and drives a quad cell using RGB data and ECB data output from the data driver in response to a control signal from the timing controller.

10. The liquid crystal display as claimed in claim 9, wherein the timing controller includes:

a storage means storing a first to a n-th look-up tables provided such that any one of first to n-th ECB brightness data and cell location information of the quid crystal display panel are correspondingly mapped;

an image processor that calculates a brightness data distribution of an image to be displayed at the liquid crystal display panel using the input RGB data for one frame period;

a viewing angle controller that selects any one of the first to the n-th look-up tables with reference calculated brightness data distribution; and

a data aligner that mixes ECB brightness data retrieved from a look-up table selected by the viewing angle controller and the input RGB data, and then aligns the mixed RGB and ECB data for output in accordance with a cell structure of a quad cell.

11. The liquid crystal display as claimed in claim 10, wherein the first to the n-th look-up tables are selectively selected by the viewing angle controller to output ECB brightness data stored therein to the data aligner.

12. The liquid crystal display as claimed in claim 10, wherein the image processor detects a brightness data of a whole image to be displayed for one frame from the input RGB data calculates a brightness data distribution of a whole image using the detected bright less data to output it to the viewing angle controller.

13. The liquid crystal display as claimed in claim 10, wherein the image processor samples an image of a specific area of a whole image to be displayed by the input RGB input data for one frame to detect a brightness data of the sampled image and calculates a brightness data distribution of an image to be displayed at a specific area using the detected brightness data to output it to the viewing angle controller.

14. The liquid crystal display as claimed in claim 10, wherein the viewing angle controller stores a predetermined first to n-th reference brightness data having the same brightness value as the first to the n-th ECB brightness data.

15. The liquid crystal display as claimed in claim 14, wherein the viewing angle controller compares the calculated brightness data distribution with the predetermined first to n-th reference brightness data to detect a reference brightness data having the same value or the approximate value as the calculated brightness data distribution.

16. The liquid crystal display as claimed in claim 15, wherein the viewing angle controller selects a look-up table that the same ECB brightness data as tote reference brightness data detected from the first to n-th look-up tables are set.

17. The liquid crystal display as claimed in claim 10, wherein the data aligner includes a mixer that mixes ECB brightness data retrieved from a look-up table selected by the viewing angle controller using the input RGB data from the first to n-th look-up tables;

and a data aligner part that aligns and outputs RGB data and ECB brightness data mixed by the mixer in accordance with the cell structure of a quad cell.

18. A method of driving a liquid crystal display, including a liquid crystal display panel having quad cells each including a R sub pixel, a G sub pixel, a B sub pixel, and an ECB sub pixel, the method comprising:

calculating a brightness data distribution of an image to be displayed at the liquid crystal display panel using input RGB data for one frame;

selecting any one of first to n-th ECB brightness data that are preset to correspond to a predetermined first to n-th look-up tables in accordance with the calculated brightness data distribution; and

mixing the selected ECB brightness data and the input RGB data to align and output the mixed RGB data and the ECB data in accordance with the cell structure of a quad cell.

19. The method of driving the liquid crystal display as claimed in claim 18, wherein calculating a brightness data distribution of an image includes:

detecting a brightness data of a whole image to be displayed for one frame from the input RGB data; and

calculating a brightness data distribution of an entire image using the detected brightness data.

20. The method of driving the liquid crystal display as claimed in claim 18, wherein calculating a brightness data distribution of an image includes:

sampling a specific area of an entire image to be displayed using input RGB for a frame;

detecting a brightness data of the sampled image; and

calculating a brightness data distribution of the specific area of the entire image to be displayed using the detected brightness data.

21. The method of driving the liquid crystal display as claimed in claim 18, wherein selecting any one of first to n-th ECB brightness data includes:

comparing the calculated brightness data distribution with a predetermined first to n-th reference brightness data to detect a reference brightness data corresponding to one of the same value and the approximate value as the calculated brightness data distribution; and

selecting an ECB brightness data of the first to n-th ECB brightness data having the same brightness value as the detected reference brightness data.

22. The method of driving the liquid crystal display as claimed in claim 18, wherein aligning and outputting the mixed RGB data and the ECB data includes:

mixing the input RGB data and the selected ECB brightness data; and

aligning the mixed RGB data and the ECB brightness data in accordance with the cell structure of a quad cell of the liquid crystal display.