Liquid crystal display device with red, green and blue subpixels having different aperture ratios
View Patent ↗In a liquid crystal display device, the reduction of power consumption is realized by reddening a backlight while maintaining a white balance. An aperture ratio of a red subpixel and an aperture ratio of a blue subpixel are set such that, in a state where an aperture ratio of a green subpixel in each pixel of a liquid crystal panel is fixed to a desired value, white brightness efficiency takes a maximum value which is set based on a balance between light emission efficiency which is increased corresponding to lowering of a color temperature of the backlight and transmissivity of the pixel which is decreased corresponding to the increase of the aperture ratio of the blue subpixel.
1. A liquid crystal display device comprising:
a light source which generates an irradiation light; and
a liquid crystal panel which includes a liquid crystal layer which is sandwiched between a pair of substrates, the liquid crystal panel being provided pixels, each consisting of red, green and blue subpixels, and controlling a transmission of the irradiation light; wherein
the irradiation light is generated from emission of phosphors of a fluorescent lamp as the light source;
an aperture ratio of the green subpixel in the each pixel of the liquid crystal panel is fixed to a desired value in advance;
aperture ratios of the red subpixel and the blue subpixel in the each pixel of the liquid crystal panel are determined such that, in a state where the aperture ratio of the green subpixel is fixed to the desired value, white brightness efficiency takes a maximum value which is set based on a balance between light emission efficiency which is increased corresponding to lowering of a color temperature of the light source and transmissivity of the pixel which is decreased corresponding to an increase of the aperture ratio of the blue subpixel;
the liquid crystal display device is an active-matrix-drive type liquid crystal display device in which each subpixel includes a thin film transistor which connects an individual electrode arranged in the subpixel to a signal line in response to a control voltage applied to a gate of the thin film transistor from a scanning line;
a ratio among areas of the individual electrodes of the red subpixel, the green subpixel and the blue subpixel in each pixel is set to a value corresponding to a ratio among the aperture ratios of the red subpixel, the green subpixel and the blue subpixel in each pixel; and
a size of the thin film transistor which is defined by a ratio W/L between a gate width W and a gate length L is set such that the ratio W/L of the size of the thin film transistor among the red subpixel, the green subpixel and the blue subpixel takes a value corresponding to the ratio among the aperture ratios.
2. The liquid crystal display device according to claim 1 , wherein the areas of the individual electrodes of the red subpixel, the green subpixel and the blue subpixel satisfy the relationship of red<green<blue, and capacitors formed between a common electrode and each of the individual electrodes of the red, green and blue subpixels differ from each other in capacitance.
3. The liquid crystal display device according to claim 1 , wherein the aperture ratio of only the green subpixel is fixed to the desired value in advance, and wherein the aperture ratios of both of the red subpixel and blue subpixel are determined in the state where the aperture ratio of only the green subpixel is fixed to the desired value.