Image display device

• US 8,823,633 B2
• Filed: 04/04/2011
• Issued: 09/02/2014
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi Consumer Electronics Company Limited (Hitachi, Ltd.)
• Inventors: Ogi, Yuya, Tsuru, Yasutaka, Tanaka, Kazuhiko
• Primary Examiner(s): HARRIS, DOROTHY H
• Application Number:
  US13/079,076
• Publication Number:
  US 20110249039A1
• Time in Patent Office: 1,247 Days
• Field of Search: 345/690, 345 87-104, 349/65
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

In a liquid-crystal display device including an edge-light-scheme-employed backlight device, it is implemented to reduce its power consumption while maintaining its excellent picture-quality. The present invention is applied to the backlight device with a plurality of edge-light-scheme backlight cells in a matrix-like manner including a LED light-source, and a light-guiding plate for emitting light. The intensity of light from a backlight cell positioned at a screen'"'"'s peripheral portion is so controlled as to be made lower than the intensity of light from a backlight cell at a central portion. The light intensity of a backlight cell having a LED light-source adjacent to a first edge portion of the illumination surface of the backlight device is so controlled as to be made higher than the light intensity of a backlight cell adjacent to a second edge portion opposed to the first edge portion.

Claims

1. An image display device including a display panel, and a backlight for illuminating said display panel with light, said image display device, comprising:

a plurality of edge-light-scheme backlight cells including both a plurality of light sources respectively arranged to emit light in a first direction, and a light-guiding plate for introducing light from a backlight control unit for respectively controlling intensity of said light from each of said backlight cells by controlling light intensity of each of the plurality of light sources;

wherein

the plurality of backlight cells are arranged in a matrix-like manner,

said backlight control unit controlling intensity of light from a backlight cell positioned at a screen'"'"'s peripheral portion in such a manner that said intensity of said light becomes lower than intensity of light from a backlight cell positioned at a screen'"'"'s central portion, and

the backlight control unit being configured to control light intensity of light at one of the backlight cells adjacently positioned on a first end portion of the light panel which is located upstream along the first direction to become higher than light intensity of another one of the backlight cells adjacent to a second portion opposed to the first end portion.

2. The image display device according to claim 1, wherein the first end portion comprises an upper portion of the light panel, and the second end portion comprises a lower portion of the light panel.

3. The image display device according to claim 1, further comprising:

a controller for transmitting a control signal in accordance with a video display mode set by a user;

wherein

said backlight control unit individually controls said light intensity of each backlight cell in accordance with said control signal transmitted from said controller.

4. The image display device according to claim 1, further comprising:

an image-signal processing unit for detecting a feature amount of an inputted image;

wherein

said backlight control unit controls a degree of the luminance intensity lowered for a backlight cell positioned at said screen'"'"'s peripheral portion in accordance with said feature amount of said inputted image detected by said image-signal processing unit.

5. The image display device according to claim 4, wherein

said feature amount of said inputted image detected by said image-signal processing unit is average picture level (APL) of said inputted image.

6. The image display device according to claim 1, further comprising:

an APC (auto power control) control unit for limiting maximum consumption power consumed by said backlight;

wherein

said APC control unit calculates consumption power consumed by said backlight in accordance with a control signal allocated to each backlight cell determined by said backlight control unit,

said APC control unit then changing said control signal allocated to each backlight cell, when said consumption power calculated is larger than a predetermined value.

7. A backlight device for illuminating a display panel with light, comprising:

a plurality of edge-light-scheme backlight cells, each of said backlight cells including a plurality of light sources respectively arranged to emit light in a first direction, and a light-guiding plate, said light-guiding plate being configured for introducing light from said light-source therein, and emitting said light therefrom toward said display panel; and

a backlight control unit for individually controlling each light-source on each backlight cell by controlling light intensity each of the plurality of light sources;

wherein

said backlight control unit controls intensity of light from a backlight cell positioned at a screen'"'"'s peripheral portion in such a manner that said intensity of said light becomes lower than intensity of light from a backlight cell positioned at a screen'"'"'s central portion, and

the backlight control unit being configured to control light intensity of light at one of the backlight cells adjacently positioned on a first end portion of the light panel which is located upstream along the first direction to become higher than light intensity of another one of the backlight cells adjacent to a second portion opposed to the first end portion.

8. An image display device including a display panel, and a backlight for illuminating said display panel with light,

said image display device, comprising:

a plurality of edge-light-scheme backlight cells including both a plurality of light sources respectively arranged to emit light in a first direction, and a light-guiding plate for introducing light from a backlight control unit for respectively controlling intensity of said light from each of said backlight cells by controlling light intensity of each of the plurality of light sources;

wherein;

the plurality of backlight cells are arranged in a matrix-like manner,

each light-source of each of said plurality of backlight cells being so provided as to emit said light in a direction which is oriented from side of a first edge portion of said backlight to side of a second edge portion opposed to said first edge portion,

said backlight control unit controlling light intensity of a backlight cell deployed on said first-edge portion side higher than light intensity of a backlight cell deployed on said second-edge portion side, and

the backlight control unit being configured to control light intensity of light at one of the backlight cells adjacently positioned on a first end portion of the light panel which is located upstream along the first direction to become higher than light intensity of another one of the backlight cells adjacent to a second portion opposed to the first end portion.