Display device and method of controlling backlight of display device

1. A display device comprising:

a backlight including a plurality of backlight blocks;

a display panel configured to display an image with light from the backlight; and

a controller,

wherein the controller is configured to:

acquire video data;

determine provisional luminance values for the plurality of backlight blocks based on the video data;

determine an adjustment coefficient for a backlight block of interest selected from the plurality of backlight blocks;

determine an adjusted luminance value for the backlight block of interest based on the provisional luminance value and the adjustment coefficient for the backlight block of interest; and

control the backlight block of interest in accordance with the adjusted luminance value, and

wherein, in determining the adjustment coefficient for the backlight block of interest, the controller is configured to:

calculate a statistic of provisional luminance values for a plurality of reference backlight blocks including backlight blocks adjacent to the backlight block of interest;

calculate a relative value of the statistic with respect to the provisional luminance value for the backlight block of interest; and

determine the adjustment coefficient for the backlight block of interest based on the relative value and a predefined function.

2. The display device according to claim 1 ,

wherein the controller is configured to determine a product of the provisional luminance value for the backlight block of interest and the adjustment coefficient to be the adjusted luminance value for the backlight block of interest, and

wherein the adjustment coefficient takes a value not smaller than 1.

3. The display device according to claim 1 , wherein the relative value is a value obtained by dividing the statistic by the provisional luminance value for the backlight block of interest.

4. The display device according to claim 1 ,

wherein the plurality of backlight blocks include a first backlight block of interest the entire perimeter of which is surrounded by adjacent backlight blocks, and

wherein the plurality of reference backlight blocks for the first backlight block of interest consist of all of the backlight blocks adjacent to the first backlight block of interest.

5. The display device according to claim 1 , wherein the statistic is a simple average.

6. The display device according to claim 1 ,

wherein the plurality of backlight blocks are disposed in a matrix,

wherein the statistic is a weighted average, and

wherein, in calculating the statistic, the controller is configured to assign a reference backlight block diagonally adjacent to the backlight block of interest a smaller weight than a weight assigned to a reference backlight block adjacent to the backlight block of interest in a row direction or a column direction.

7. The display device according to claim 1 , wherein the plurality of reference backlight blocks include backlight blocks that are adjacent to backlight blocks adjacent to the backlight block of interest on an outer side with respect to the backlight block of interest.

8. The display device according to claim 1 ,

wherein the plurality of backlight blocks are disposed in a matrix, and

wherein the plurality of reference backlight blocks consist of backlight blocks adjacent to the backlight block of interest in a row direction and backlight blocks adjacent to the backlight block of interest in a column direction.

9. The display device according to claim 1 ,

wherein the controller is configured to select each of the plurality of backlight blocks as a backlight block of interest and determine an adjusted luminance value for each of the plurality of backlight blocks,

wherein disposition of reference backlight blocks is common to each backlight block of interest,

wherein the plurality of backlight blocks include a second backlight block of interest located at an end of the backlight, and

wherein reference backlight blocks for the second backlight block of interest include backlight blocks adjacent to the second backlight block of interest within the backlight and virtual backlight blocks adjacent to the second backlight block of interest outside the backlight.

10. The display device according to claim 9 , wherein a provisional luminance value for a virtual backlight block is the same as a provisional luminance value for a reference backlight block adjacent to the virtual backlight block.

11. The display device according to claim 1 ,

wherein the controller is configured to:

determine a value smaller than 1 for the adjustment coefficient for the backlight block of interest by a method different from a method used in the determination based on the relative value and the function, in a case where predetermined conditions are satisfied; and

determine a value for the adjustment coefficient for the backlight block of interest based on the relative value and the function, in a case where the predetermined conditions are not satisfied, and

wherein the predetermined conditions are that provisional luminance values for the plurality of reference backlight blocks are maximum values and that a provisional luminance value for the backlight block of interest is smaller than a maximum value.

12. The display device according to claim 1 ,

wherein the controller includes:

a first processing circuit configured to control a first display region of the display panel and a first backlight block group opposite to the first display region,

a second processing circuit configured to control a second display region of the display panel and a second backlight block group opposite to the second display region,

wherein the first processing circuit is configured to:

acquire information on provisional luminance values for second border backlight blocks that are adjoining the first backlight block group; and

control the first backlight block group based on provisional luminance values for the first backlight block group and the second border backlight blocks, and

wherein the second processing circuit is configured to:

acquire information on provisional luminance values for first border backlight blocks that are adjoining the second backlight block group; and

control the second backlight block group based on provisional luminance values for the second backlight block group and the first border backlight blocks.

13. A method of controlling a backlight of a display device,

the backlight including a plurality of backlight blocks, and

the method comprising:

acquiring video data;

determining provisional luminance values for the plurality of backlight blocks based on the video data;

determining an adjustment coefficient for a backlight block of interest selected from the plurality of backlight blocks;

determining an adjusted luminance value for the backlight block of interest based on the provisional luminance value and the adjustment coefficient for the backlight block of interest; and

controlling the backlight block of interest in accordance with the adjusted luminance value,

wherein the determining an adjustment coefficient for the backlight block of interest includes:

calculating a statistic of provisional luminance values for a plurality of reference backlight blocks including backlight blocks adjacent to the backlight block of interest;

calculating a relative value of the statistic with respect to the provisional luminance value for the backlight block of interest; and

determining the adjustment coefficient for the backlight block of interest based on the relative value and a predefined function.