1. Technical Field
The present invention relates to a display device.
2. Description of the Related Art
There have recently been an increasing demand for display devices designed for mobile apparatuses and the like, such as mobile phones and electronic paper. In such display devices, each pixel includes a plurality of sub-pixels that output light of respective colors. The display devices switch on and off the display in the sub-pixels, thereby causing each pixel to display various colors. Display characteristics, such as resolution and luminance, of the display devices have been improved year by year. An increase in the resolution, however, reduces the aperture ratio. To achieve high luminance, it is necessary to increase the luminance of a backlight, resulting in increased power consumption of the backlight. To address this, there has been developed a technology of adding a white pixel serving as the fourth sub-pixel to the conventional red, green, and blue sub-pixels (e.g., Japanese Patent Application Laid-open Publication No. 2010-33014). Because the white pixel increases the luminance, the technology reduces the current value of the backlight, thereby reducing the power consumption.
Japanese Patent Application Laid-open Publication No. 2010-44389 (JP-A-2010-44389) discloses a light source local dimming control method for controlling dimming of a light source module including a light source block provided with a light source that supplies light to a plurality of image regions. In the method, duty ratios of a first light source and a second light source are primarily determined using a first target luminance value of a first image region closest to a first light source and a second target luminance value of a second image region closest to a second light source adjacent to the first light source. The primarily determined duty ratios are compensated using a target luminance value of a remaining image region excluding the first and the second image regions out of the image regions that receive the light from the first and the second light sources. The first and the second light sources are driven by drive signals resulting from compensation of the primarily determined duty ratios.
Let us assume a case where the technology disclosed in JP-A-2010-44389 is applied to a sidelight light source including a plurality of light sources at a position facing an incident surface corresponding to at least one side surface of a light guide plate. In this case, the luminance distribution of a backlight may possibly vary in a complicated manner, resulting in unnecessary power consumption.
For the foregoing reasons, there is a need for a display device that controls the luminance of light sources of a sidelight light source individually, thereby reducing power consumption of the light sources.