In recent years, in a place where a lot of people gather, such as an event site, a station, or an airport, a multi-display device in which a plurality of liquid crystal displays are arranged vertically or horizontally, or vertically and horizontally has been installed to display a large amount of information. In the multi-display device, the liquid crystal displays display images corresponding to their installation places to display a large-screen image.
A typical multi-display device employs liquid crystal displays having the same luminance of images, but in practice, the luminance of images for the liquid crystal displays may vary due to individual differences which cause luminance unevenness. In such a multi-display device, if variance occurs in the luminance of images displayed on the respective liquid crystal displays, continuity between the images is deteriorated, which may cause inconvenience to an observer.
In order to suppress such luminance unevenness, Japanese Unexamined Patent Application Publication No. 2009-169196 discloses a technique in which a backlight unit for forming images in a plurality of image display sections includes a plurality of light sources and the brightness of the light sources of the backlight unit is controlled to suppress the occurrence of luminance unevenness.
Further, as a liquid crystal display that constitutes the multi-display device, there is a device in which an image display region is divided into a plurality of areas (regions) and a backlight unit that controls, for each area, light emission of a light emitting element provided in each area (which may be hereinafter referred to as an “area-drive backlight unit”) is used. In the liquid crystal display provided with such an area-drive backlight unit, the brightness of the backlight is adjusted in accordance with an image displayed in the image display region.
Further, in the area-drive backlight unit, control is performed for decreasing the luminance of light emitting elements in areas corresponding to a peripheral part of the image display region to a degree that an observer cannot recognize decrease in the brightness. By performing such control, it is possible to reduce power consumption without the observer recognizing decrease in contrast.