Color correction liquid crystal display and method of driving same

• US 7,030,846 B2
• Filed: 07/10/2001
• Issued: 04/18/2006
• Est. Priority Date: 07/10/2001
• Status: Expired due to Term

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Seung-Woo, Kim, Jong-Seon, Kwon, Su-Hyun
• Primary Examiner(s): Liang, Regina
• Application Number:
  US09/901,137
• Publication Number:
  US 20030016199A1
• Time in Patent Office: 1,743 Days
• Field of Search: 345 87- 89, 345/601, 345/602, 345/616, 345/690, 348/671, 348/674
• US Class Current: 345/89
• 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 3/2055 the pattern being varied in time
• 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

A liquid crystal display includes a liquid crystal display panel for displaying picture images, and a color correction unit. Upon receipt of raw RGB picture data corresponding to raw RGB gamma curves, the color correction unit generates corrected RGB picture data based on values over a predetermined imaginative gamma curve established in accordance with the characteristic of the liquid crystal display panel. The color correction unit stores values over corrected RGB gamma curves corresponding to the corrected picture data, and gamma-corrects the raw RGB picture data based on values over the stored corrected RGB gamma curves, thereby displaying the picture images.

Claims

1. A liquid crystal display, comprising:

a liquid crystal display panel for displaying picture images; and

a color correction unit;

wherein upon receipt of raw RGB picture data corresponding to raw RGB gamma curves, the color correction unit generates corrected RGB picture data based on gray values over a predetermined imaginative gamma curve established in accordance with the characteristic of the liquid crystal display panel, stores gray values of corrected RGB gamma curves corresponding to the corrected picture data, and gamma-corrects the raw RGB picture data based on gray values of the stored corrected RGB gamma curves.

2. The liquid crystal display of claim 1, wherein the number of bits in the corrected picture data is altered through making bit extension with respect the raw picture data.

3. The liquid crystal display of claim 1, wherein the imaginative gamma curve is the G gamma curve adapted to the G picture data.

4. The liquid crystal display of claim 3, wherein the corrected gamma curves are approximated to the G gamma curve.

5. The liquid crystal display of claim 1, wherein the liquid crystal display panel makes the display in a vertical alignment (VA) mode.

6. The liquid crystal display of claim 1, wherein the liquid crystal display panel makes the display in a patterned vertical alignment (PVA) mode.

7. A liquid crystal display, comprising:

a vertically aligned mode liquid crystal display panel for displaying picture images; and

a color correction unit,

wherein upon receipt of raw RGB picture data corresponding to raw RGB gamma curves, the color correction unit transforms the raw RGB picture data into corrected RGB picture data based on gray values of a predetermined imaginative gamma curve established in accordance with the characteristic of the vertically aligned mode liquid crystal display panel, stores gray values of corrected RGB gamma curves corresponding to the transformed corrected picture data, and gamma-corrects the raw RGB picture data based on gray values of the stored corrected RGB gamma curves.

8. The liquid crystal display of claim 7, wherein the vertically aligned mode liquid crystal display panel is a patterned vertical alignment (PVA) mode.

9. The liquid crystal display of claim 7, wherein the corrected gamma curves intercept overlapping of the input picture data through gray scale extension.

10. A liquid crystal display, comprising:

a liquid crystal display panel having an internal layer of liquid crystal with a predetermined property, a plurality of gate lines transmitting scanning signals, a plurality of data lines transmitting picture signals, and switching circuits connected to the gate and the data lines;

a scan driver sequentially applying gate on voltages for turning-on the switching circuits to the gate lines;

a data driver applying data voltages for representing picture signals to the data lines; and

a control unit, at initial driving, generating corrected picture data over a predetermined imaginative gamma curve corresponding to raw RGB picture data fed from the outside while storing the corrected picture data into a predetermined memory, and after the initial driving, upon receipt of raw RGB picture data from the outside, extracting corrected picture data corresponding to the raw RGB picture data from the memory while transmitting the extracted picture data to the data driver, and generating timing signals for controlling the operation of the scan driver and the data driver while outputting the generated timing signals to the scan driver and the data driver, respectively.

11. The liquid crystal display of claim 10, wherein the control unit receives picture signals corresponding to respective RGB gamma curves from the outside, normalizes the RGB gamma curves into one gamma curve, and controls the gray scale levels of the picture signals input from the outside based on the normalized gamma curve.

12. The liquid crystal display of claim 10, wherein the control unit comprises:

a color correction unit, at initial driving, receives raw RGB picture data from an external graphic controller and transforms the raw RGB picture data into corrected picture data while storing the corrected picture data into the memory, and after the initial driving, upon receipt of raw RGB picture data from the outside, extracting the corrected picture data corresponding to the raw RGB picture data from the memory and transforming the extracted picture data into multi-gray scales; and

a timing control unit outputting the transformed picture data to the data driver, and generating timing signals for controlling the operation of the scan driver and the data driver while outputting the generated timing signals to the scan driver and the data driver, respectively.

13. The liquid crystal display of claim 10, wherein the control unit comprises:

a timing control unit generating timing signals for controlling the operation of the scan driver and the data driver while outputting the generated timing signals to the scan driver and the data driver, and outputting the raw RGB picture data input from the outside; and

a color correction unit, at initial driving, receives raw RGB picture data from an external graphic controller and transforms the raw RGB picture data into corrected picture data while storing the corrected picture data into the memory, and after the initial driving, upon receipt of raw RGB picture data from the outside, extracting the corrected picture data corresponding to the raw RGB picture data from the memory and transforming the extracted picture data into multi-gray scales while outputting the transformed picture data to the data driver.

14. The liquid crystal display of claim 12 or 13, wherein the color correction unit further makes a treatment of dithering.

15. The liquid crystal display of claim 12 or 13, wherein the color correction unit comprises:

a volatile memory;

a data controller, at initial driving, receiving raw RGB picture data from the outside and generating corrected picture data while storing the corrected picture data into the volatile memory, and after the initial driving, upon receipt of raw RGB picture data from the outside, outputting corrected picture data corresponding to the raw picture data from the volatile memory; and

a frame rate control (FRC) unit transforming the corrected picture data into gray scale data, and outputting the gray scale data to the data driver.

16. The liquid crystal display of claim 15, wherein the color correction unit further comprises a memory control unit, the memory control unit storing values of an imaginative gamma curve corresponding to the characteristic of the liquid crystal display panel, and at initial driving, feeding gamma data corresponding to the values of the imaginative gamma curve to the volatile memory while controlling the storing.

17. The liquid crystal display of claim 16, wherein the memory control unit comprises:

a non-volatile memory storing the corrected picture data corresponding to the characteristic of the liquid crystal display panel; and

a memory controller, at initial driving, controlling the storing of the gamma data corresponding to the imaginative gamma curve into the non-volatile memory.

18. The liquid crystal display of claim 12 or 13, wherein the multi-gray scale transformation is made through frame rate control (FRC).

19. The liquid crystal display of claim 10, wherein the corrected picture data are generated based on a predetermined imaginative gamma curve.

20. The liquid crystal display of claim 10, wherein the bit number of the corrected picture data is the same as the bit number of the raw picture data.

21. The liquid crystal display of claim 10, wherein the corrected picture data are obtained through bit extension of the raw picture data.

22. A driving unit for a liquid crystal display, the liquid crystal display having a layer of liquid crystal with a predetermined property, a plurality of gate lines, a plurality of data lines crossing over the gate lines while being insulated from the gate lines, and pixels surrounded by the gate and data lines each with a switching circuit connected to the corresponding gate and the data lines, the pixels being arranged in a matrix form, the driving unit for the liquid crystal display, comprising:

a scan driver sequentially applying gate on voltages for turning-on the switching circuits to the plurality of gate lines;

a data driver applying data voltages for representing picture signals to the data lines; and

a control unit, at initial driving, generating corrected picture data over a predetermined imaginative gamma curve corresponding to raw RGB picture data fed from the outside while storing the corrected picture data into a predetermined memory, and after the initial driving, upon receipt of raw RGB picture data from the outside, extracting corrected picture data corresponding to the raw RGB picture data from the memory while transmitting the extracted picture data to the data driver, and generating timing signals for controlling the operation of the scan driver and the data driver while outputting the generated timing signals to the scan driver and the data driver, respectively.

23. The driving unit for the liquid crystal display of claim 22, wherein the liquid crystal display panel makes the display in a vertical alignment mode (VA) mode.

24. The driving unit for the liquid crystal display of claim 22, wherein the liquid crystal display panel makes the display in a patterned vertical alignment (PVA) mode.

25. A method of driving a liquid crystal display, the liquid crystal display having a layer of liquid crystal with a predetermined property, a plurality of gate lines, a plurality of data lines crossing over the gate lines while being insulated from the gate lines, and pixels surrounded by the gate and data lines each with a switching circuit connected to the corresponding gate and data lines, the pixels being arranged in a matrix form, the method comprising the steps of:

(a) sequentially transmitting scanning signals to the gate lines;

(b) upon receipt of RGB gray scale data for displaying picture images from the outside, establishing corrected RGB gammas curves based on the RGB gray scale data and predetermined imaginative gamma curves, and generating data voltages based on the RGB gamma curves; and

(c) feeding the data voltages generated at the (b) step to the data lines.

26. The method of claim 25 wherein the (b) step comprises the sub-steps of:

(b-1) at initial driving, receiving raw RGB picture data adapted to RGB gamma curves from the outside, and detecting light transmissions corresponding to grays of the raw picture data of the imaginative gamma curve;

(b-2) detecting gray values of the raw picture data corresponding to the detected light transmissions from the relevant gamma curves; and

(b-3) transforming the gray values detected at the (b-3) step into a predetermined number of bits, and storing the bit-transformed gray values.

27. The method of claim 26 wherein the (b) step further comprises the sub-steps of:

(b-4) after the initial driving, receiving raw picture data adapted to a predetermined gamma curve from the outside, and detecting the stored bit-transformed gray values; and

(b-5) transforming the detected gray values into multi-gray scales, and generating data voltages for the data lines.

28. The method of claim 26 or 27, wherein the imaginative gamma curve is established to be optimally adapted to the characteristic of the liquid crystal display panel.

29. The method of claim 26 or 27, wherein the imaginative gamma curve is one of the RGB gamma curves.

30. A liquid crystal display, comprising:

a liquid crystal display panel for displaying picture images; and

a color correction unit for generating first corrected RGB picture data corresponding to input RGB picture data and based on gray values over a predetermined imaginative gamma curve for outputting second corrected RGB picture data in accordance with the first corrected picture data,

wherein the first corrected RGB picture data has a bit number equal to or more than a bit number of the input RGB picture data and the second corrected RGB picture data has a bit number equal to or less than the bit number of the first corrected RGB picture data.

31. The liquid crystal display of claim 30, further comprising a memory to store the first corrected RGB picture data.

32. The liquid crystal display of claim 31, wherein the memory comprises at least one of a random access memory (RAM) or a read-only memory (ROM).

34. The liquid crystal display of claim 32, wherein the color correction unit further comprises:

a second memory to store the first corrected RGB picture data; and

a memory controller to control the first and second memories.

35. The liquid crystal display of claim 34, wherein the first corrected RGB picture data has a bit number equal to or more than a bit number of the input RGB picture data and the second corrected RGB picture data has a bit number equal to or less than the bit number of the first corrected RGB picture data.

36. The liquid crystal display of claim 35, wherein the first memory comprises at least one of a random access memory (RAM) or a read-only memory (ROM).

37. The liquid crystal display of claim 36, wherein the multi-grayscale unit generates the second corrected RGB picture data by means of dithering and frame rate control (FRC).

38. The liquid crystal display of claim 35, wherein the second memory comprises a ROM.

33. A liquid crystal display, comprising:

a liquid crystal display panel having an internal layer of liquid crystal with a predetermined property, a plurality of gate lines for transmitting scanning signals, a plurality of data lines for transmitting picture signals, and switching circuits connected to the gate and the data lines;

a scan driver sequentially applying a gate on voltage for turning on the switching circuits to the gate lines;

a data driver applying data voltages for representing picture signals to the data lines; and

a color correction unit for generating first corrected RGB picture data over a predetermined imaginative gamma curve corresponding to input RGB picture data and for outputting second corrected RGB picture data in accordance with the first corrected picture data,

wherein the color correction unit comprises;

a first memory to store the first corrected RGB picture data; and

a multi-grayscale unit to output the second corrected RGB picture data adapted to the data driver.

39. The liquid crystal display of claim 33, wherein the liquid crystal display panel makes the display in a vertical alignment (VA) mode.

40. The liquid crystal display of claim 39, wherein the liquid crystal display panel makes the display in a patterned vertical alignment (PVA) mode.

41. A method of driving a liquid crystal display, the liquid crystal display having a layer of liquid crystal with a predetermined property, a plurality of gate lines, a plurality of data lines crossing over the gate lines while being insulated from the gate lines, and pixels surrounded by the gate and data lines and arranged in a matrix form, each pixel having a switching circuit connected to the corresponding gate and data lines, the method comprising:

sequentially transmitting scanning signals to the gate lines;

generating first corrected RGB picture data corresponding to input RGB picture data based on gray values over a predetermined imaginative gamma curve established in accordance with the characteristic of the liquid crystal display panel;

outputting second corrected RGB picture data in accordance with the first corrected picture data; and

supplying the second corrected RGB picture data to the data lines.

42. The method of claim 41, wherein the first corrected RGB picture data has a bit number equal to or more than a bit number of the input RGB picture date and the second corrected RGB picture data has a bit number equal to equal to or less than the bit number of the first corrected RGB picture data.