Liquid crystal display unit having fine color control

• US 6,700,559 B1
• Filed: 10/13/2000
• Issued: 03/02/2004
• Est. Priority Date: 10/13/1999
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Tanaka, Seiichi, Nakajima, Takayuki, Shimizu, Hajime
• Primary Examiner(s): AWAD, AMR A
• Application Number:
  US09/689,618
• Time in Patent Office: 1,236 Days
• Field of Search: 345/87, 345/88, 345/89, 345/98, 345/99, 345/204, 345/690-693, 345/589, 345/596, 345/600, 345/601, 345/605, 348/671-686, 358/455-457
• US Class Current: 345/88
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence

Abstract

Eight-bit digital image data of R, G and B output from an image data memory are corrected by conversion controllers to meet characteristics of a liquid crystal panel. The corrected data are input to a liquid crystal drive circuit as digital image data, and an image is displayed on the liquid crystal panel. A LUT stored in a LUT reference processor stores data (addresses) by a number that makes it possible to refer to input image digital data at one to one. A random number generator is for generating random numbers and supplying the random numbers to a round-to-integer processor as threshold value data. The round-to-integer processor compares the data referred to by the LUT reference processor with the threshold data, and carries out a round-to-integer processing.

Claims

1. A liquid crystal display unit comprising:

a liquid crystal panel that can display a color image;

a liquid crystal drive circuit that drives the liquid crystal panel; and

a conversion controller that controls the conversion of image digital data consisting of digital signals of R, G, B respectively, and supplies the converted data to the liquid crystal drive circuit, wherein

the conversion controller comprises;

correcting means that corrects the image digital data having a number of bits by outputting corrected image digital data, having bits below a decimal point and having a larger number of bits than the image digital data, in order to carry out a color reproduction that meets characteristics of the liquid crystal panel; and

color improving means for generating a threshold value and changing the corrected image digital data to an integer based on said generated threshold value, thereby adding a fine variation to the corrected image digital data.

2. The liquid crystal display unit according to claim 1, further comprising:

an image data memory that stores image digital data and supplies it to the conversion controller, wherein

the liquid crystal drive circuit is driven by digital signals from the conversion controller.

3. The liquid crystal display unit according to claim 1, further comprising:

an A/D converter that converts analog input signals of R, G and B respectively that are color image signals input from the outside of the unit into digital signals, and supplies the digital signals to the conversion controller; and

a D/A converter that converts image digital data from the conversion controller into analog signals, and supplies the analog signals to the liquid crystal drive circuit, wherein

the liquid crystal drive circuit is driven by analog signals from the D/A converter.

4. The liquid crystal display unit according to claim 1, 2 or 3, wherein

the correcting means carries out a correction by referring to a lookup table consisting of characteristic data of the liquid crystal panel, and each data of the lookup table that becomes the corrected data has bits of a larger number than the number of bits of the image digital data.

5. The liquid crystal display unit according to claim 1, 2 or 3, wherein

the correcting means carries out a correction calculation using a functional expression by approximating characteristic data of the liquid crystal panel, and the corrected data has bits of a larger number than the number of bits of the image digital data.

6. The liquid crystal display unit according to claim 1, 2 or 3, wherein

the correcting means carries out a correction by linearly matrix converting the image digital data using a matrix coefficient that has been calculated from characteristic data of the liquid crystal panel, and the corrected data has bits of a larger number than the number of bits of the image digital data.

7. The liquid crystal display unit according to claim 4, wherein

the color improving means has a random number generator that generates a random threshold value, and changes the corrected data into an integer by the random threshold value, thereby to add a fine variation.

8. The liquid crystal display unit according to claim 5, wherein

the color improving means has a random number generator that generates a random threshold value, and changes the corrected data into an integer by the random threshold value, thereby to add a fine variation.

9. The liquid crystal display unit according to claim 6, wherein

the color improving means has a random number generator that generates a random threshold value, and changes the corrected data into an integer by the random threshold value, thereby to add a fine variation.

10. The liquid crystal display unit according to claim 4, wherein

the color improving means stores a dither matrix pattern, and changes the corrected data into an integer by a threshold value obtained from the dither matrix pattern, thereby to add a fine variation.

11. The liquid crystal display unit according to claim 5, wherein

the color improving means stores a dither matrix pattern, and changes the corrected data into an integer by a threshold value obtained from the dither matrix pattern, thereby to add a fine variation.

12. The liquid crystal display unit according to claim 6, wherein

the color improving means stores a dither matrix pattern, and changes the corrected data into an integer by a threshold value obtained from the dither matrix pattern, thereby to add a fine variation.

13. The liquid crystal display unit according to claim 10, wherein

the color improving means stores the dither matrix patterns separately in the image data of R, G and B respectively, and can change a variation that is added to the image data of R, G and B respectively.

14. The liquid crystal display unit according to claim 11, wherein

the color improving means stores the dither matrix patterns separately in the image data of R, G and B respectively, and can change a variation that is added to the image data of R, G and B respectively.

15. The liquid crystal display unit according to claim 12, wherein

the color improving means stores the dither matrix patterns separately in the image data of R, G and B respectively, and can change a variation that is added to the image data of R, G and B respectively.