Liquid crystal display device for displaying video data

• US 6,850,214 B2
• Filed: 03/26/2001
• Issued: 02/01/2005
• Est. Priority Date: 03/27/2000
• Status: Expired due to Term

• Current Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Original Assignee: Hitachi, Ltd., Hitachi Micro Software SYST, Hitachi Video And Information System Inc.
• Inventors: Maeda, Takeshi, Kawabe, Kazuyoshi, Kurihara, Hiroshi, Nishitani, Shigeyuki, Ohashi, Toshiaki, Takagi, Tetsuo
• Primary Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US09/816,077
• Publication Number:
  US 20010033260A1
• Time in Patent Office: 1,408 Days
• Field of Search: 345/87, 345/89, 345/88, 345/589, 345/596, 345/606, 345/204, 348/493, 348/496, 348/631, 348/687, 348/671, 348/672, 348/690, 348/229.1, 348/254, 348/324, 348362-366, 382/168, 382/169, 382/171, 358/519
• US Class Current: 345/87
• 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 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: H04N 5/66 Transforming electric information into light information scanning details H04N3/00
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

A luminance characteristic of inputted video data is determined by input video image characteristic detection sections, and polygonal line point master data and polygonal line point correction data are calculated based on the luminance characteristic so as to provide a satisfactory display state using a microcomputer and are outputted to the polygonal line generation sections. The polygonal line point data determining the output gradation characteristic is calculated in polygonal point generation sections and outputted to inter-point gradation operation sections, and operation processing is conducted by using the polygonal point data and the inputted video data in the inter-point operation sections to determine the inter-point gradation and outputted to a display panel.

Claims

1. A liquid crystal display device for displaying video data, comprising:

a detection circuit for detecting a luminance distribution in one frame period, the luminance distribution being indicative of generation frequency of gradations in each of a plurality of divided regions, each divided region including a plurality of gradations based on the video data which is inputted,

a determination circuit for determining a divided region of higher generation frequency of gradation than that all of other divided regions based on the luminance distribution in one frame period,

a memory for delaying the video data which is inputted by one frame period,

a correction circuit for correcting the video data which is delayed by one frame period so as to make a luminance characteristic of the divided region of higher generation frequency of gradation more abrupt than a luminance characteristic of the other divided regions, and

a display panel for displaying the corrected video data.

2. A liquid crystal display device according to claim 1, wherein the detection circuit comprises:

a detection setting section for setting a detection period,

a divisional number setting section for setting a divisional number for the divided regions, and

a luminance distribution detection section for accumulating the generation frequency of gradations in each divided region divided by the divisional number set by the divisional number setting section during the detection period set by the detection setting section.

3. A liquid crystal display device according to claim 1, wherein the device further comprises a gradation correction coefficient generation section for calculating a correction coefficient in each divided region based on the luminance distribution detected by the detection circuit.

4. A liquid crystal display device according to claim 1, wherein the correction circuit increases output gradation number against input gradation number of the divided region of higher generation frequency of gradation more than output gradation number against input gradation number of the other divided regions.

5. A liquid crystal display device according to claim 1, wherein the correction circuit corrects the video data to emphasize contrast of the divided region of higher generation frequency of gradation more than contrast of the other divided regions.

6. A liquid crystal display device according to claim 1, further comprising:

a data driver for outputting to the display panel a driving voltage corresponding to the corrected video data; and

a scan driver for outputting to the display panel a scanning voltage for enabling the display panel to display the corrected video data;

wherein the display panel displays the corrected video data based on the driving voltage and the scanning voltage.

9. A liquid crystal display device according to claim 1, wherein the correction circuit makes a luminance characteristic of a divided region adjacent the divided region of higher generation frequency of gradation more smooth and maintains a luminance characteristic other divided regions.

10. A liquid crystal display device according to claim 1, further comprising a setting section for setting a value for determining a range of luminance for each divided region.

11. A liquid crystal display device according to claim 10, wherein intervals between two adjacent values are unequal.

12. A liquid crystal display device according to claim 11, wherein the value is set according to light transmission of liquid crystal of the display panel.

13. A liquid crystal display device according to claim 10, wherein the intervals between two adjacent values for higher or lower luminance are larger than the intervals between two adjacent values for intermediate luminance.

14. A liquid crystal display device according to claim 13, wherein the value is set according to light transmittance of liquid crystal of the display panel.

7. A liquid crystal display device for displaying video data, comprising:

a detection circuit for detecting a luminance distribution in one frame period, the luminance distribution being indicative of generation frequency of gradations in each of a plurality of divided regions, each divided region including a plurality of gradations based on the video data which is inputted;

a determination circuit for determining a divided region of higher generation frequency of gradation than that all of other divided regions based on the luminance distribution in one frame period;

a memory for delaying the video data which is inputted by one frame period;

a correction circuit for correcting the video data which is delayed by one frame period by increasing an output gradation number against an input gradation number of the divided region of higher generation frequency of gradation more that an output gradation number against an input gradation number of other divided regions; and

a display panel for displaying the corrected video data.

8. A liquid crystal display device for displaying video data, comprising:

a detection circuit for detecting a luminance distribution in one frame period, the luminance distribution being indicative of generation frequency of gradations in each of a plurality of divided regions, each divided region including a plurality of gradations based on the video data which is inputted;

a determination circuit for determining a divided region of higher generation frequency of gradation than that all of other divided regions based on the luminance distribution in one frame period;

a memory for delaying the video data which is inputted by one frame period;

a correction circuit for correcting the video data which is delayed by one frame period so as to emphasize contrast of the divided region of higher generation frequency of gradation more than contrast of the other divided regions; and

a display panel for displaying the corrected video data.