Apparatus for driving liquid crystal display device and driving method using the same

• US 7,782,335 B2
• Filed: 12/15/2005
• Issued: 08/24/2010
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Baek, Heume Il
• Primary Examiner(s): Lefkowitz; Sumati
• Assistant Examiner(s): Xiao; Ke
• Application Number:
  US11/300,345
• Publication Number:
  US 20060256053A1
• Time in Patent Office: 1,713 Days
• Field of Search: 345/72, 345/83, 345/88, 345589-605
• US Class Current: 345/586
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• 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

Abstract

An apparatus for driving a liquid crystal display (LCD) device includes a liquid crystal panel including 4-color sub-pixels, a data driver to provide video data signals to each sub-pixel, a gate driver to provide a scan pulse to each sub-pixel, a data conversion part to generate a gain value by analyzing a ratio of an achromatic color signal to a chromatic color signal of 3-color source data inputted from an external source and convert the 3-color source data into 4-color data using the generated gain value, and a timing controller to provide the 4-color data received from the data conversion part to the data driver and control the gate driver and the data driver.

Claims

1. An apparatus for driving a liquid crystal display (LCD) device, comprising:

a liquid crystal panel including 4-color sub-pixels;

a data driver to provide video data signals to each sub-pixel;

a gate driver to provide a scan pulse to each sub-pixel;

a data conversion part to generate a gain value by analyzing a ratio of an achromatic color signal or a chromatic color signal of 3-color source data inputted from an external source in a unit frame and convert the 3-color source data into 4-color data using the generated gain value, wherein the data conversion detects a maximum brightness value and a minimum brightness value of the 3-color source data and analyzis the ratio of the achromatic color signal or the chromatic color signal in the unit frame using the detected maximum and minimum brightness values; and

a timing controller to provide the 4-color data received from the data conversion part to the data driver and control the gate driver and the data driver,

wherein a data conversion part includes the gain value generation part including;

a brightness detection part to detect the maximum brightness value and the minimum brightness value of the 3-color input data and output the detected maximum brightness value and a calculated maximum brightness value acquired by multiplying the minimum brightness value by a C value (C value being a positive real number);

a comparator to compare the calculated maximum brightness value with the detected maximum brightness value and output a comparison result signal;

a counter to count the comparison result signal in a unit frame and generate a count signal; and

a gain value setting part to set the gain value according to the count signal.

2. The apparatus as set forth in claim 1, wherein the data conversion part further includes:

a reverse gamma correction part to reverse gamma correct the 3-color source data to generate 3-color input data;

a multiplication part to multiply the 3-color input data by the gain value to generate 3-color amplification data;

a first 4-color data generation part to abstract first white data from a common component of the 3-color amplification data, generate first 3-color output data using the first white data, and output the first 3-color output data and the first white data; and

a gamma correction part to gamma correct the first white data and the first 3-color output data to generate the 4-color data.

3. The apparatus as set forth in claim 2, wherein the comparator outputs the comparison signal with a first logical value corresponding to the achromatic color signal when the calculated maximum brightness value is greater than or equal to the detected maximum brightness value, and the comparator outputs the comparison signal with a second logical value corresponding to the chromatic color signal when the calculated maximum brightness value is less than the detected maximum brightness value.

4. The apparatus as set forth in claim 2, wherein the gain value setting part sets the gain value to a number between 1 and 1+α

(α

value being a positive real number) according to the count signal.

5. The apparatus as set forth in claim 4, wherein the gain value setting part divides the count signal by a predetermined number of pixels of the liquid crystal panel to produce the α

value and sets the gain value by adding a constant of 1 to the α

value.

6. The apparatus as set forth in claim 2, wherein the first 4-color data generation part generates the first 3-color output data by subtracting the abstracted first white data from the 3-color amplification data.

7. The apparatus as set forth in claim 6, wherein the first 4-color data generation part removes the abstracted first white data from the 3-color amplification data by a 3-color α

value representing a relative size that the abstracted first white data respectively contributes to a brightness of the first 3-color output data.

8. The apparatus as set forth in claim 1, wherein the data conversion part further includes:

a reverse gamma correction part to reverse gamma correct the 3-color source data to generate 3-color input data;

a multiplication part to multiply the 3-color input data by the gain value to generate 3-color amplification data;

a first 4-color data generation part to abstract first white data from a common component of the 3-color amplification data, generate first 3-color output data using the first white data, and output the first 3-color output data and the first white data;

a second 4-color data generation part to correct the first white data and the first 3-color output data, and generate second white data and second 3-color output data; and

a gamma correction part to gamma correct the second white data and the second 3-color output data to generate the 4-color data.

9. The apparatus as set forth in claim 8, wherein the comparator outputs the comparison signal with a first logical value corresponding to the achromatic color signal when the calculated maximum brightness value is greater than or equal to the detected maximum brightness value, and the comparator outputs the comparison signal with a second logical value corresponding to the chromatic color signal when the calculated maximum brightness value is less than the detected maximum brightness value.

10. The apparatus as set forth in claim 8, wherein the gain value setting part sets the gain value to a number between 1 and 1+α

(a value being a positive real number) according to the count signal.

11. The apparatus as set forth in claim 10, wherein the gain value setting part divides the count signal by a predetermined number of pixels of the liquid crystal panel to produce the α

value and sets the gain value by adding a constant of 1 to the α

value.

12. The apparatus as set forth in claim 8, wherein the first 4-color data generation part generates the first 3-color output data by subtracting the abstracted first white data from the 3-color amplification data.

13. The apparatus as set forth in claim 12, wherein the first 4-color data generation part removes the abstracted first white data from the 3-color amplification data by a 3-color α

value representing a relative size that the abstracted first white data respectively contributes to a brightness of the first 3-color output data.

14. The apparatus as set forth in claim 8, wherein the second 4-color data generation part includes:

a maximum value detection part to detect a maximum brightness value of the first 3-color output data;

an error component detection part to detect an error component using the maximum brightness value;

a 3-color data correction part to generate 3-color correction data using the first 3-color output data and the error component;

a white correction data generation part to generate white correction data using the 3-color correction data;

a 3-color data generation part to generate the second 3-color output data using the first 3-color output data and the 3-color correction data; and

a white data generation part to generate the second white data using the white correction data and the first white data.

15. The apparatus as set forth in claim 14, wherein the error component detection part subtracts a constant of 1 from the maximum brightness value.

16. The apparatus as set forth in claim 14, wherein the 3-color data correction part generates the 3-color correction data by multiplying the error component with a resultant value obtained by dividing the first 3-color output data by the maximum brightness value.

17. The apparatus as set forth in claim 14, wherein the white correction data generation part multiplies each characteristic parameter of the 3-color source data with the 3-color correction data and generates the white correction data by summing together each multiplication result value.

18. The apparatus as set forth in claim 14, wherein the 3-color data generation part generates the second 3-color output data by subtracting the 3-color correction data from the first 3-color output data.

19. The apparatus as set forth in claim 14, wherein the white data generation part generates the second white data by adding the white correction data to the first white data.

20. A method for controlling a liquid crystal display (LCD) device which includes a liquid crystal panel including 4-color sub-pixels, a data driver for providing video data signals to each sub-pixel, and a gate driver for providing a scan pulse to the sub-pixels, comprising:

detecting a maximum brightness value and a minimum brightness value of the 3-color source data inputted from an external source;

generating a gain value by analyzing a ratio of an achromatic color signal or a chromatic color signal of the 3-color source data in a unit frame using the detected maximum and minimum brightness values;

converting the 3-color source data into 4-color video data using the generated gain value;

generating the scan pulse; and

applying the 4-color video data to each sub-pixel in synchronization with the scan pulse,

wherein the step of generating the gain value includes;

generating a calculated maximum brightness value by multiplying the minimum brightness value with a C value (C value being a positive real number);

comparing the calculated maximum brightness value with the detected maximum brightness value and generating a comparison result signal;

counting the comparison result signal in a unit frame and generating a count signal; and

setting the gain value according to the count signal.

21. The method as set forth in claim 20, wherein the step of generating the gain value further includes:

reverse gamma correcting the 3-color source data to generate 3-color input data prior to detecting the maximum and minimum brightness values.

22. The method as set forth in claim 21, wherein the step of generating the comparison result signal includes outputting a first logical value corresponding to the achromatic color signal when the calculated maximum brightness value is greater than or equal to the detected maximum brightness value or a second logical value corresponding to the chromatic color signal when the calculated maximum brightness value is less than the detected maximum brightness value.

23. The method as set forth in claim 21, wherein the gain value is set to a number between 1 and 1+α

(α

value being a positive real number) according to the count signal.

24. The method as set forth in claim 23, wherein the step of setting the gain value includes:

dividing the count signal by a predetermined number of pixels of the liquid crystal panel to producing the α

value; and

setting the gain value by adding a constant of 1 to the α

value.

25. The method as set forth in claim 20, wherein the step of converting the 3-color source data into the 4-color video data includes:

multiplying the 3-color input data by the gain value to generate 3-color amplification data;

abstracting first white data from a common component of the 3-color amplification data;

generating first 3-color output data using the first white data; and

gamma-correcting the first white data and the first 3-color output data to generate the 4-color video data.

26. The method as set forth in claim 25, wherein the step of generating the first 3-color output data includes subtracting the abstracted first white data from the 3-color amplification data.

27. The method as set forth in claim 26, wherein the step of subtracting the first white data includes removing the abstracted first white data from the 3-color amplification data by a 3-color α

value representing a relative size that the abstracted first white data respectively contributes to a brightness of the first 3-color output data.

28. The method as set forth in claim 20, wherein the step of converting the 3-color source data into the 4-color video data include:

multiplying the 3-color input data by the gain value to generate 3-color amplification data;

abstracting first white data from a common component of the 3-color amplification data;

generating first 3-color output data using the first white data;

generating second white data and second 3-color output data using the first white data and the first 3-color output data; and

gamma-correcting the second white data and the second 3-color output data to generate the 4-color video data.

29. The method as set forth in claim 28, wherein the step of generating the first 3-color output data includes subtracting the abstracted first white data from the 3-color amplification data.

30. The method as set forth in claim 29, wherein the step of subtracting the first white data includes removing the abstracted first white data from the 3-color amplification data by a 3-color α

value representing a relative size that the abstracted first white data respectively contributes to a brightness of the first 3-color output data.

31. The method as set forth in claim 28, wherein the step of generating the second white data and the second 3-color output data includes:

detecting a maximum brightness value of the first 3-color output data;

detecting an error component using the maximum brightness value;

generating 3-color correction data using the first 3-color output data and the error component;

generating white correction data using the 3-color correction data;

generating the second 3-color output data using the first 3-color output data and the 3-color correction data; and

generating the second white data using the white correction data and the first white data.

32. The method as set forth in claim 31, wherein the step of detecting the error component includes subtracting a constant of 1 from the maximum brightness value.

33. The method as set forth in claim 31, wherein the step of generating the 3-color correction data includes:

dividing the first 3-color output data by the maximum brightness value; and

generating the 3-color correction data by multiplying the error component with a division result value.

34. The method as set forth in claim 31, wherein the step of generating the white correction data includes:

multiplying each characteristic parameter of the 3-color source data by the 3-color correction data; and

generating the white correction data by summing together the multiplication result values.

35. The method as set forth in claim 31, wherein the second 3-color output data is generated by subtracting the 3-color correction data from the first 3-color output data.

36. The method as set forth in claim 31, wherein the second white data is generated by adding the white correction data to the first white data.