IMAGE DISPLAY DEVICE AND IMAGE DISPLAY METHOD

• US 20120154459A1
• Filed: 05/18/2010
• Published: 06/21/2012
• Est. Priority Date: 09/30/2009
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Fujiwara, Kohji, Otoi, Katsuya, Hashimoto, Katsuteru
• Granted Patent: US 8,988,338 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• 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 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 2340/0414 Vertical resolution change
• CPC Class Codes: G09G 2340/0421 Horizontal resolution change
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

In an image display device which performs area-active drive, backlight sources are emitted with appropriate luminances while inhibiting increase in power consumption and inhibiting reduction of image quality. An emission luminance calculation section divides an input image into a plurality of areas, and obtains luminances upon emission (first emission luminances) of LEDs in the areas. A plurality of correction modes are prepared as methods for correcting the first emission luminances, and a correction mode that is applied to an emission luminance correction process (selected correction mode) is stored to a correction mode storage section. For any LED units whose flag data stored in a correction-enabled map has the value of 1, an emission luminance correction section corrects their first emission luminances to obtain second emission luminances in accordance with the selected correction mode, with reference to correction value data stored in correction value tables.

Claims

1. An image display device having a function of controlling a backlight luminance, comprising:

a display panel including a plurality of display elements;

a backlight including a plurality of light sources;

an emission luminance calculation section for dividing an input image into a plurality of areas and obtaining luminances upon emission of light sources corresponding to each area as first emission luminances on the basis of a portion of the input image of a corresponding area;

an emission luminance correction section for obtaining second emission luminances by correcting the first emission luminances in accordance with a selected correction mode which is selected from among a plurality of prepared correction modes;

a display data calculation section for obtaining display data for controlling light transmittances of the display elements, on the basis of the input image and the second emission luminances;

a panel driver circuit for outputting signals for controlling the light transmittances of the display elements to the display panel, on the basis of the display data; and

a backlight driver circuit for outputting signals for controlling luminances of the light sources to the backlight, on the basis of the second emission luminances.

2. The image display device according to claim 1, further comprising a correction value storage section having stored therein correction values corresponding to the areas, wherein,

the plurality of correction modes include a first correction mode in which, for each area, the greater of a value for the first emission luminance and the correction value stored in the correction value storage section is set as the second emission luminance.

3. The image display device according to claim 1, further comprising a correction value storage section having stored therein correction values corresponding to the areas, wherein,

the plurality of correction modes include a second correction mode in which, for each area, the lesser of a value for the maximum emission luminance of the light sources and a value obtained by adding a value for the first emission luminance to the correction value stored in the correction value storage section is set as the second emission luminance.

4. The image display device according to claim 2, wherein the plurality of correction modes includes a third correction mode in which, for each area, the correction value stored in the correction value storage section is set as the second emission luminance, and a fourth correction mode in which, for each area, the value for the first emission luminance is set as the second emission luminance.

5. The image display device according to claim 1, further comprising a correction value storage section having stored therein correction values corresponding to the areas, wherein,

the plurality of correction modes include a first correction mode in which, for each area, the greater of a value for the first emission luminance and the correction value stored in the correction value storage section is set as the second emission luminance, a second correction mode in which, for each area, the lesser of a value for the maximum emission luminance of the light sources and a value obtained by adding a value for the first emission luminance to the correction value stored in the correction value storage section is set as the second emission luminance, a third correction mode in which, for each area, the correction value stored in the correction value storage section is set as the second emission luminance, and a fourth correction mode in which, for each area, the value for the first emission luminance is set as the second emission luminance.

6. The image display device according to claim 1, further comprising a correctability data storage section having stored therein correctability data corresponding to the areas as data indicating whether or not to perform a correction in accordance with the selected correction mode, wherein,

the emission luminance correction section sets the value for the first emission luminance as the second emission luminance for any area for which the correctability data stored in the correctability data storage section indicates that the correction in accordance with the selected correction mode is not performed.

7. An image display method in an image display device provided with a display panel including a plurality of display elements and a backlight including a plurality of light sources, the method comprising:

an emission luminance calculation step for dividing an input image into a plurality of areas and obtaining luminances upon emission of light sources corresponding to each area as first emission luminances on the basis of a portion of the input image of a corresponding area;

an emission luminance correction step for obtaining second emission luminances by correcting the first emission luminances in accordance with a selected correction mode which is selected from among a plurality of prepared correction modes;

a display data calculation step for obtaining display data for controlling light transmittances of the display elements, on the basis of the input image and the second emission luminances;

a panel drive step for outputting signals for controlling the light transmittances of the display elements to the display panel, on the basis of the display data; and

a backlight drive step for outputting signals for controlling luminances of the light sources to the backlight, on the basis of the second emission luminances.

8. The image display method according to claim 7, wherein,

the image display device further includes a correction value storage section having stored therein correction values corresponding to the areas, and

the plurality of correction modes include a first correction mode in which, for each area, the greater of a value for the first emission luminance and the correction value stored in the correction value storage section is set as the second emission luminance.

9. The image display method according to claim 7, wherein,

the image display device further includes a correction value storage section having stored therein correction values corresponding to the areas, and

the plurality of correction modes include a second correction mode in which, for each area, the lesser of a value for the maximum emission luminance of the light sources and a value obtained by adding a value for the first emission luminance to the correction value stored in the correction value storage section is set as the second emission luminance.

10. The image display method according to claim 8, wherein the plurality of correction modes includes a third correction mode in which, for each area, the correction value stored in the correction value storage section is set as the second emission luminance, and a fourth correction mode in which, for each area, the value for the first emission luminance is set as the second emission luminance.

11. The image display method according to claim 7, wherein,

the image display device further includes a correction value storage section having stored therein correction values corresponding to the areas, and

the plurality of correction modes include a first correction mode in which, for each area, the greater of a value for the first emission luminance and the correction value stored in the correction value storage section is set as the second emission luminance, a second correction mode in which, for each area, the lesser of a value for the maximum emission luminance of the light sources and a value obtained by adding a value for the first emission luminance to the correction value stored in the correction value storage section is set as the second emission luminance, a third correction mode in which, for each area, the correction value stored in the correction value storage section is set as the second emission luminance, and a fourth correction mode in which, for each area, the value for the first emission luminance is set as the second emission luminance.

12. The image display method according to claim 7, wherein,

the image display device further includes a correctability data storage section having stored therein correctability data corresponding to the areas as data indicating whether or not to perform a correction in accordance with the selected correction mode, and

in the emission luminance correction step, the value for the first emission luminance is set as the second emission luminance for any area for which the correctability data stored in the correctability data storage section indicates that the correction in accordance with the selected correction mode is not performed.