Backlight system, display apparatus, and light emission control method

1. A backlight unit, comprising:

a backlight including a plurality of light-emitting sections, the light-emitting sections being operable to emit light at mutually different timings and including a first light-emitting section and a second light-emitting section; and

a controller that controls a light emission operation of the backlight to cause the first light-emitting section and the second-light emitting section to emit light with mutually different light emission intensities in a first sub-frame period of a plurality of sub-frame periods corresponding to a frame period,

wherein, the backlight unit comprises a diffuser plate that diffuses light emitted from the plurality of light-emitting sections to output diffused light, and

wherein a gradient in a characteristic of the diffused light output from the diffuser plate, as determined by fitting a portion of the characteristic to a sinusoidal waveform, is equal to or lower than a maximum gradient in a sine-wave grating having a spatial frequency based on a resolution of images displayed on a screen of a display apparatus and a distance from the screen.

2. The backlight unit according to claim 1 , wherein

the light-emitting sections are arranged side by side in a first direction.

3. The backlight unit according to claim 2 , wherein

the controller controls light emission of the plurality of light-emitting sections such that, within a sub-frame period, light intensities of a predetermined number of selected successive light-emitting sections progressively increase from a first value to a maximum value and progressively decrease to the first value in a scanning direction in the sub-frame period.

4. The backlight unit according to claim 3 , wherein

the predetermined number is three or more, and

the controller performs control to cause a light emission intensity of a light-emitting section disposed at an end in the first direction out of the predetermined number of selected light-emitting sections to be lower than an average light emission intensity of a light-emitting section disposed around a center in the first direction.

5. The backlight unit according to claim 2 , wherein

the controller controls the light emission operation of the backlight by scanning in the first direction in the frame period.

6. The backlight unit according to claim 2 , wherein

a display section that modulates light emitted from the backlight displays a frame image by line-sequential scanning, and

the first direction is a scanning direction of the line-sequential scanning.

7. The backlight unit according to claim 6 , wherein

each of the light-emitting sections includes a plurality of light-emitting devices arranged side by side in a second direction intersecting with the first direction.

8. The backlight unit according to claim 1 , wherein

the first light-emitting section emits light with a first light emission intensity throughout the first sub-frame period, and

the second light-emitting section emits light with a second light emission intensity different from the first light emission intensity throughout the first sub-frame period.

9. The backlight unit according to claim 1 , wherein

the first light-emitting section emits light at a first light emission duty ratio in the first sub-frame period, and

the second light-emitting section emits light at a second light emission duty ratio different from the first light emission duty ratio in the first sub-frame period.

10. The backlight unit according to claim 1 , wherein

the first light-emitting section emits light also in a second sub-frame period, and

the average light emission intensity of the first light-emitting section in the first sub-frame period is different from the average light emission intensity of the first light-emitting section in the second sub-frame period.

11. A display apparatus, comprising:

a display section;

a backlight including a plurality of light-emitting sections, the light-emitting sections being operable to emit light at mutually different timings and including a first light-emitting section and a second light-emitting section; and

a controller that controls a light emission operation of the backlight to cause the first light-emitting section and the second light-emitting section to emit light with mutually different light emission intensities in a first sub-frame period of a plurality of sub-frame periods corresponding to a frame period,

wherein,

the backlight unit comprises a diffuser plate that diffuses light emitted from the plurality of light-emitting sections to output diffused light, and

a gradient in a characteristic of the diffused light output from the diffuser plate as determined by fitting a portion of the characteristic to a sinusoidal waveform, is equal to or lower than a maximum gradient in a sine-wave grating having a spatial frequency based on a resolution of images displayed on a screen of the display apparatus and a distance from the screen.

12. The display apparatus according to claim 11 , further comprising

a map generator that generates a luminance map on the basis of image data of a frame image; and

wherein

the display section displays the frame image by scanning in a first direction,

the light-emitting sections are arranged side by side in the first direction, each of the light-emitting sections includes a plurality of light-emitting devices arranged side by side in a second direction intersecting with the first direction, and the backlight performs a light emission operation by scanning in the first direction, and

the controller generates light emission distribution information in the first direction in each of the sub-frame periods, and controls the light emission operation of the backlight on the basis of the luminance map and the light emission distribution information.