Liquid crystal display apparatus

• US 20050184952A1
• Filed: 02/09/2005
• Published: 08/25/2005
• Est. Priority Date: 02/09/2004
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Yamamoto, Tsunenori, Konno, Akitoyo, Inuzuka, Tatsuki, Kondo, Katsumi, Utsumi, Yuka, Adachi, Masaya, Hiyama, Ikuo, Kajita, Daisuke
• Granted Patent: US 7,460,103 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• 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 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/064 by time 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 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3208 : organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3225 : using an active matrix
• CPC Class Codes: G09G 3/3426 : the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/346 : based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: G09G 3/3648 : using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The video display apparatus has a light modulation device for forming a picture in accordance with a video signal and a lighting unit for irradiating, on the light modulation device, illumination light necessary to cause it to display the picture. In the apparatus, the lighting unit irradiates the illumination light in sequence of individual plural illumination light source partitive areas, a luminance distribution calculating unit calculates luminance distributions of video signals corresponding to the plural partitive areas to determine illumination light luminance levels of the individual partitive areas, an illumination controller controls rays of the illumination light of individual areas of the lighting unit on the basis of determination by the luminance distribution calculating unit, and a video corrector corrects the video signal inputted to the light modulation device on the basis of the determination by the luminance distribution calculating unit.

Claims

1. A lighting unit for irradiating illumination light, on a light modulation device adapted to form a picture in accordance with a video signal, illumination light necessary to cause it to display the picture, comprising:

illumination means for emitting the illumination light in sequence of individual plural partitive areas of said illumination means;

luminance distribution calculating means for determining luminance levels of illumination light of the individual areas by calculating luminance distributions of video signals corresponding to said plural areas; and

illumination control means for controlling the illumination light of said individual areas of illumination means on the basis of determination by said luminance distribution calculating means.

4. A lighting unit or video display apparatus according to claim 1, wherein said illumination means includes a plurality of light sources arranged directly beneath said light modulation device.

5. A lighting unit or video display apparatus according to claim 1, wherein said illumination means includes light guide means and a light source which are arranged directly beneath said light modulation device and said light source is disposed at at least one side of said light guide.

6. A lighting unit or video display apparatus according to claim 4, wherein said light source includes a light emitting diode.

7. A lighting unit or video display apparatus according to claim 4, wherein said light source includes an organic EL element.

8. A lighting unit or video display apparatus according to claim 4, wherein said light source includes a cold cathode fluorescent lamp.

9. A lighting unit or video display apparatus according to claim 4, wherein said illumination means is based on the matrix drive mode controlled in column and row.

10. A lighting unit or video display apparatus according to claim 9, wherein said illumination means is based on the active matrix drive mode driven by a light source and an active switch.

11. A lighting unit or video display apparatus according to claim 9, wherein said illumination means is based on the passive matrix drive mode.

12. A lighting unit or video display apparatus according to claim 9, wherein said illumination means is based on the pulse width modulation scheme.

13. A lighting unit or video display apparatus according to claim 9, wherein said illumination means is based on the pulse amplitude modulation scheme.

14. A lighting unit or video display apparatus according to any one of claims 1 and 2, wherein said illumination means has a sensor for detecting luminance of its illumination light and said illumination control means controls the illumination light in accordance with a signal from said sensor.

15. A lighting unit or video display apparatus according to any one of claims 1 and 2, wherein said illumination means has a sensor for detecting luminance of its illumination light and the video signal inputted to said light modulation device is corrected in accordance with a signal from said sensor.

16. A lighting unit or video display apparatus according to claim 14, wherein a plurality of said sensors are located at at least any of a peripheral portion, plural areas and a boundary between areas of said illumination means.

17. A lighting unit or video display apparatus according to claim 1, wherein said light modulation device includes a liquid crystal device of the lateral electric field switching scheme.

2. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal and a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture, comprising:

illumination means for emitting the illumination light in sequence of individual plural partitive areas of said illumination means;

luminance distribution calculating means for determining luminance levels of illumination light of the individual areas by calculating luminance distributions of video signals corresponding to said plural areas;

illumination control means for controlling the illumination light of said individual areas of illumination means on the basis of determination by said luminance distribution calculating means; and

video correction means for correcting the video signal inputted to said light modulation device on the basis of determination by said luminance distribution calculating means.

3. A video display apparatus according to claim 2, wherein said luminance distribution calculating means determines a distribution of luminance between areas and on the basis of the determination, said video correction means corrects an inter-area video signal inputted to said light modulation device.

18. A video display method for causing a light modulation device irradiated with illumination light from a lighting unit to display a picture in accordance with a video signal, said lighting unit being operative to emit the illumination light in sequence of individual partitive areas, comprising the steps of:

determining, on the basis of video signals for the individual areas, luminance levels of rays of the illumination light of individual areas which are emitted from said lighting unit; and

on the basis of the determination, controlling the illumination light of said lighting unit and correcting said video signals.

19. A video display method according to claim 18, wherein correction of said video signals is carried out on the basis of a distribution of luminance between areas.

20. A video display method according to claim 19, wherein when determining the illumination light of individual areas emitted from said lighting unit, said illumination light is determined by correcting said video signals such that areas at which said light modulation device has a good characteristic are used.

21. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal and a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture, comprising:

detection means for detecting ambient light of the neighborhood of said video display apparatus;

illumination means for emitting said illumination light in sequence of individual plural partitive areas of said illumination means;

luminance distribution calculating means for calculating luminance distributions of video signals corresponding to said plural areas and determining luminance levels of illumination light of the individual areas;

illumination control means for controlling illumination light of individual areas of said illumination means on the basis of determination by said luminance distribution calculating means and controlling the illumination light of said illumination means on the basis of a neighboring ambient light level detected by said detection means; and

video correction means for correcting the video signal inputted to said light modulation device on the basis of the determination by said luminance distribution calculating means.

22. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal and a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture, comprising:

a remote control unit for remotely controlling said video display apparatus;

illumination means for emitting said illumination light in sequence of individual plural partitive areas of said illumination means;

luminance distribution calculating means for calculating a luminance distribution of video signals corresponding to said plural areas to determine luminance levels of illumination light of said individual areas;

illumination control means for controlling illumination light of individual areas of said illumination means on the basis of determination by said luminance distribution calculation means and controlling the illumination light of said illumination means on the basis of a command from said remote control unit; and

video correction means for correcting the video signal inputted to said light modulation device on the basis of the determination by said luminance distribution calculating means.

23. A liquid crystal display apparatus comprising:

a display panel having a liquid crystal layer sandwiched between a pair of substrates;

a light source for supplying light to said display panel;

a light diffusing layer for diffusing the light from said light source; and

a display processing circuit for controlling a picture on said display panel and the luminance of said light source,

wherein said light source can be controlled in luminance in respect of a plurality of areas, and said display processing circuit calculates a maximum luminance distribution for one frame of said display panel on the basis of video signals and controls luminance levels of individual areas of said light source on the basis of said maximum luminance distribution.

24. A liquid crystal display apparatus according to claim 23, wherein said maximum luminance distribution is a distribution obtained by calculating a maximum luminance level for one scan period of said display panel over all scan periods for one frame.

25. A liquid crystal display apparatus according to claim 23, wherein said display processing circuit calculates a luminance distribution on said light diffusing layer and controls the luminance levels of individual plural areas of said light source on the basis of the luminance distribution on said light diffusing layer.

26. A liquid crystal display apparatus according to claim 23, wherein said display processing circuit calculates a luminance distribution on said light diffusion layer on the basis of determined values of luminance of said individual plural areas and corrects a picture on said display panel on the basis of the result of the calculation.

27. A liquid crystal display apparatus according to claim 23, wherein said display processing circuit calculates a luminance distribution on said light diffusing layer, calculates a luminance distribution capable of being displayed on said liquid crystal display panel on the basis of the luminance distribution on said light diffusing layer and a maximum transmission factor of said liquid crystal layer and controls luminance levels of individual plural areas of said light source on the basis of the luminance distribution capable of being displayed on said liquid crystal panel.

34. A liquid crystal display apparatus according to claim 23, wherein said light source can be controlled in luminance in respect of individual partitive areas in the vertical scan direction.

35. A liquid crystal display apparatus according to claim 23, wherein said display processing circuit controls the luminance of said light source pursuant to the pulse amplitude modulation scheme.

36. A liquid crystal display apparatus according to claim 23, wherein said light source includes a light emitting diode.

37. A liquid crystal display apparatus according to claim 23, wherein said light source includes an organic EL element.

38. A liquid crystal display apparatus according to claim 23, wherein said light source includes a cold cathode fluorescent lamp.

28. A liquid crystal display apparatus comprising:

a display panel having a liquid crystal layer sandwiched between a pair of substrates;

a light source for supplying light to said display panel;

a light diffusing layer for diffusing the light from said light source; and

a display processing circuit for controlling a picture on said display panel and the luminance of said light source,

wherein said light source can be controlled in luminance in respect of a plurality of areas, a permissible amount is provided for a change of the luminance of said light source and said display processing circuit corrects a setting value of said luminance on the basis of the permissible luminance change amount.

29. A liquid crystal display apparatus according to claim 28, wherein the permissible luminance change amount is controlled by said display processing circuit.

30. A liquid crystal display apparatus according to claim 28, wherein said display processing circuit detects a scene change in a picture on said display panel and controls the permissible luminance change amount on the basis of the scene change.

31. A liquid crystal display apparatus comprising:

a display panel having a liquid crystal layer sandwiched between a pair of substrates;

a light source for supplying light to said display panel;

a light diffusing layer for diffusing the light from said display panel;

a display processing circuit for controlling a picture on said display panel and the luminance of said light source; and

means for detecting ambient light external of said display panel,

wherein said light source can be controlled in luminance in respect of a plurality of areas, and said display processing circuit includes means for detecting a signal corresponding to a caption from a video signal for said display panel and means for converting the signal corresponding to said caption.

32. A liquid crystal display apparatus comprising:

a display panel having a liquid crystal layer sandwiched between a pair of substrates;

a light source for supplying light to said display panel;

a light diffusing layer for diffusing the light from said light source;

a display processing circuit for controlling a picture on said display panel and the luminance of said light source; and

means for detecting ambient light external of said display panel,

wherein said light source can be controlled in luminance in respect of a plurality of areas and said display processing circuit calculates a luminance distribution for one frame of said display panel on the basis of video signals and controls luminance levels of individual plural areas of said light source on the basis of said luminance distribution and the external ambient light detected by said detection means.

33. A liquid crystal display apparatus according to claim 32, wherein said luminance distribution is a distribution obtained by calculating a luminance distribution for one scan period of said display panel over all scan periods for one frame.

39. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture, and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a maximum luminance distribution detecting circuit for calculating a maximum luminance distribution on the screen from video signals;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said maximum luminance distribution detection circuit;

an illumination light source luminance control circuit for controlling the luminance levels of said individual illumination light source partitive areas on the basis of illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit; and

video signal correction means for correcting the video signal on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

40. A video display apparatus according to claim 39 further comprising a scene change detection circuit for detecting from a video signal a switchover of picture scene,

wherein said illumination light source luminance setting circuit resets the illumination luminance setting values of said individual partitive areas on the basis of the result of detection by said scene change detection circuit, said illumination light source luminance control circuit controls luminance levels of said individual light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit, said light diffusing layer luminance distribution calculating circuit calculates a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values reset by said illumination light source luminance setting circuit, and said video signal correction means corrects the video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

41. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a caption detection circuit;

a caption data conversion circuit for suitably changing a video signal corresponding to a caption detected by said caption detection circuit;

a maximum luminance distribution detecting circuit for calculating a maximum luminance distribution on the screen from video signals;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said maximum luminance distribution detecting circuit;

an illumination light source luminance control circuit for controlling the luminance levels of said individual illumination light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit; and

video signal correction means for correcting the video signal on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

43. A video display apparatus according to claim 41 further comprising neighboring ambient light detection means for detecting ambient light of the neighborhood, wherein said caption data conversion circuit converts the video signal corresponding to the caption detected by said caption detection circuit on the basis of the result of detection by said neighboring ambient light detection means.

42. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a caption detection circuit;

a caption data conversion circuit for suitably changing a video signal corresponding to a caption detected by said caption detection circuit;

a maximum luminance distribution detecting circuit for calculating a maximum luminance distribution on the screen from video signals;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said maximum luminance distribution detection circuit;

a scene change detection circuit for detecting from a video signal a switchover of picture scene, said illumination light source luminance setting circuit being operative to reset the illumination luminance setting values of said individual partitive areas on the basis of the result of detection by said scene change detection circuit;

an illumination light source luminance control circuit for controlling the illumination light source luminance setting values of said individual partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit;

a light diffusing layer luminance calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit; and

video signal correction means for correcting video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

44. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a luminance distribution detection circuit for calculating a brilliancy distribution on the screen from video signals;

neighboring ambient light detection means for detecting ambient light of the neighborhood;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said luminance distribution detection circuit and the result of detection by said neighboring ambient light detection means;

an illumination light source luminance control circuit for controlling the luminance levels of said individual illumination light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit; and

video signal correction means for correcting video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

45. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a luminance distribution detection circuit for calculating a luminance distribution on the screen from video signals;

neighboring ambient light detection means for detecting ambient light of the neighborhood;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said luminance distribution detection circuit and the result of detection by said neighboring ambient light detection means;

a scene change detection circuit for detecting from a video signal a switchover of a picture scene, said illumination light source luminance setting circuit being operative to reset the illumination luminance setting values of said individual partitive areas on the basis of the result of detection by said scene change detection circuit;

an illumination light source luminance control circuit for controlling the luminance levels of said illumination light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusion layer on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit; and

video signal correction means for correcting video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

46. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a caption detection circuit;

a caption data conversion circuit for suitably changing a video signal corresponding to the caption detected by said caption detection circuit;

a neighboring ambient light detection circuit for detecting ambient light of the neighborhood;

a luminance distribution detection circuit for calculating a luminance distribution on the screen from video signals;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual illumination light source partitive areas on the basis of the result of calculation by said luminance distribution detection circuit and the result of detection by said neighboring ambient light detection circuit;

an illumination light luminance control circuit for controlling the luminance levels of said individual illumination light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas set by said illumination light source luminance setting circuit; and

video signal correction means for correcting video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.

47. A video display apparatus having a light modulation device for forming a picture in accordance with a video signal, a lighting unit for irradiating, on said light modulation device, illumination light necessary to cause it to display the picture and a light diffusing layer for diffusing the illumination light from said lighting unit, said lighting unit being divided into n light source partitive areas which are controllable in luminance individually, said apparatus comprising:

a caption detection circuit;

a caption data conversion circuit for suitably changing a video signal corresponding to the caption detected by said caption detection circuit;

a neighboring ambient light detection circuit for detecting ambient light of the neighborhood;

a luminance distribution detection circuit for calculating a luminance distribution on the screen from video signals;

an illumination light source luminance setting circuit for setting illumination luminance levels of said individual light source partitive areas on the basis of the result of calculation by said luminance distribution detection circuit and the result of detection by said neighboring ambient light detection means;

a scene change detection circuit for detecting from a video signal a switchover of a picture scene, said illumination light source luminance setting circuit being operative to reset the illumination luminance setting values of said individual partitive areas on the basis of the result of detection by said scene change detection circuit;

an illumination light source luminance control circuit for controlling the luminance levels of said individual illumination light source partitive areas on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit;

a light diffusing layer luminance distribution calculating circuit for calculating a luminance distribution on said light diffusing layer on the basis of the illumination light source luminance setting values of said individual partitive areas reset by said illumination light source luminance setting circuit; and

video signal correction means for correcting video signals on the basis of the result of luminance calculation by said light diffusing layer luminance distribution calculating circuit.