Liquid crystal display apparatus with luminance distribution calculating, backlight controller, and video correction to improve display contrast ratio

• US 7,460,103 B2
• Filed: 02/09/2005
• Issued: 12/02/2008
• 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
• Primary Examiner(s): Mengistu; Amare
• Assistant Examiner(s): LAM, VINH TANG
• Application Number:
  US11/053,029
• Publication Number:
  US 20050184952A1
• Time in Patent Office: 1,392 Days
• Field of Search: 345/38, 345/47, 345/48, 345/63, 345/77, 345/87, 345/90, 345/102, 345/104, 345/206, 345/207, 345/211, 345/690, 349/69
• 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 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.

2. A video display apparatus according to claim 1 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.

3. 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.

4. A video display apparatus according to claim 3 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.