Sharp Kabushiki Kaisha Corporation

Hiroyoshi Kure

Michiaki Takeda

Eishi Oda

The present invention effectively suppresses not only occurrences of halos but also degradation of the black level. This image display device has a liquid crystal panel () that displays images according to an image signal and a backlight () in which LEDs are used and controls the light emission brightness of the LEDs for each division region, which is obtained by dividing the backlight () into a plurality of regions, on the basis of a prescribed relation between a gradation value for an image region corresponding to each division region and the LED light emission brightness. When the gradation value for an image satisfies prescribed conditions, a first luminance adjusting portion () adjusts the LED light emission brightness such that the range of variation in LED light emission brightness in a first range for the gradation value of the image region, which is determined on the basis of the prescribed conditions above, is smaller than the range of variations for the LED light emission brightness that is determined on the basis of the prescribed relation above, and a second luminance adjusting portion () adjusts the LED light emission brightness in a second range for which the value is smaller than the first range such that the light emission brightness is smaller than a lower limit value for the LED light emission brightness adjusted above.

Video display device

Light leakage and black float are reduced in dark ambient while a perception of high contrast is achieved when a backlight is divided into a plurality of areas and backlight brightness is controlled depending on a video signal corresponding to each area. An area active control portion () divides a video signal into a plurality of areas and outputs a first feature value for each area. An LED control portion () acquires a first brightness for each divided area of an LED backlight () depending on the first feature value of each area, and acquires a second brightness for each area that is acquired by uniformly multiplying a specific multiplying factor acquired depending on the lighting ratio of the LED backlight () with respect to the first brightness within a range where a total value of the LED driving current does not exceed a predetermined permissible current value. When the lighting ratio of the LED backlight () is at or below a predetermined value, the second brightness is reduced in accordance with ambient lighting detected by a photosensor () to acquire a third brightness.

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Osaka, Japan

Hiroyoshi Kure