LIQUID CRYSTAL DISPLAY DEVICE AND IMAGE DISPLAY METHOD THEREOF
A liquid crystal panel displays an image from image signals. A backlight device disposed on the back side of the liquid crystal panel, and divided into a plurality of regions. The backlight device is configured to allow light emitted from the light source of each of the regions to leak to nearby regions. A light emission luminance calculator obtains a light emission luminance by using, as nearby regions, a group of regions from the regions in the backlight device and at least two virtual regions provided respectively at opposite ends of the group of regions.
1 . A liquid crystal display device, comprising:
a liquid crystal panel configured to display an image from image signals;
a backlight device disposed on the back side of the liquid crystal panel, and divided into a plurality of regions, the backlight device comprising light sources in the respective regions, the light sources positioned to emit light into the liquid crystal panel, and the backlight device configured to allow light emitted from the light source of each of the regions to leak to nearby regions; and
a light emission luminance calculator configured to obtain a second light emission luminance by multiplying a first light emission luminance by a first coefficient where the first light emission luminance is light emitted from each region in the backlight device, the second light emission luminance is light emitted by each light source of the regions in the backlight device, to obtain the first light emission luminance, and wherein the first coefficient is based on light leaked from each region of the light source to nearby regions, and the light emission luminance calculator is configured to obtain the second light emission luminance by using, as nearby regions, a group of regions from the regions in the backlight device and at least two virtual regions provided respectively at opposite ends of the group of regions.
2 . The liquid crystal display device according to claim 1 , wherein the calculation equation is a matrix equation.
3 . The liquid crystal display device according to claim 1 , further comprising:
a maximum gradation detector configured to detect, at predetermined intervals, a first maximum gradation of each of regional image signals displayed on a plurality of regions of the liquid crystal panel that correspond to regions of the backlight device;
an image gain calculator configured to obtain a gain for each image signal by dividing a second maximum gradation by the first maximum gradation wherein the second maximum gradation attainable by the image signals and is determined from a bit count of the image signals; and
a multiplier configured to multiply the image signal per region by the gain obtained by the image gain calculator and to output the multiplied image signal as an image signal for displaying an image on the liquid crystal panel, wherein
the light emission luminance calculator uses, as the first light emission luminance of light to be emitted from each of the regions in the backlight device, a light emission luminance obtained by multiplying a maximum luminance of the light source by an inverse of the gain obtained by the image gain calculator.
4 . The liquid crystal display device according to claim 1 , wherein
the regions in the backlight device are one-dimensionally divided in a vertical direction, and
at least one virtual region is provided to each of an upper portion adjacent to the uppermost region and a lower portion adjacent to the lowermost region.
5 . The liquid crystal display device according to claim 1 , wherein
the backlight device is two-dimensionally divided into regions, and
at least one virtual region is provided to each of an upper portion adjacent to the uppermost region, a lower portion adjacent to the lowermost region, a left portion adjacent to the leftmost region, and a right portion adjacent to the rightmost region.
6 . An image display method comprising:
obtaing, as image signals for display on a liquid crystal panel, an image signal per each of a plurality of regions set on the liquid crystal panel;
obtaining a second light emission luminance by multiplying a first light emission luminance by a first coefficient where a backlight device of the liquid crystal panel is divided into regions corresponding to regions of the liquid crystal panel, the first light emission luminance denotes a luminance of light from each region in the backlight device, the second light emission luminance denotes a luminance of light from each light source region in the backlight device in order to obtain the first light emission luminance, and the first coefficient is based on an amount of light leaked from each region of the light sources nearby to the each region, the second light emission luminance obtained by using, as the regions nearby to the each region, some regions from among the regions in the backlight device and at least two virtual regions provided respectively to opposite end sides of the group of the regions; and
displaying an image according to the image signal per region of the liquid crystal panel while causing each light source in respective regions of the backlight device to emit light with the second light emission luminance.
7 . The image display method according to claim 6 , wherein the calculation equation is a matrix equation.
8 . The image display method according to claim 6 , further comprising:
detecting, at predetermined intervals, a first maximum gradation of each of regional image signals displayed on a plurality of regions of the liquid crystal panel;
obtaining a gain for the each image signal by dividing a second maximum gradation by the first maximum gradation wherein the second maximum gradation attainable by the image signal and which is determined from a bit count of the image signal;
supplying the liquid crystal panel with the image signal per region multiplied by the gain;
using, as the first light emission luminance of light emitted from each region in the backlight device, a light emission luminance obtained by multiplying a maximum luminance of the light source by an inverse of the gain obtained by the image gain calculator; and
displaying an image on each region of the liquid crystal panel according to the image signal per region multiplied by the gain.
9 . The image display method according to claim 6 , wherein
the regions in the backlight device are one-dimensionally divided in a vertical direction, and
at least one virtual region is provided to each of an upper portion adjacent to the uppermost region and a lower portion adjacent to the lowermost region.
10 . The image display method according to claim 6 , wherein
the backlight device is two-dimensionally divided into regions, and
at least one virtual region is provided to each of an upper portion adjacent to the uppermost region, a lower portion adjacent to the lowermost region, a left portion adjacent to the leftmost region, and a right portion adjacent to the rightmost region.