Patent ID: 8558770

Claim:
A semi-transmissive liquid crystal display device comprising: a liquid crystal panel provided with a liquid crystal layer between two substrates having electrodes formed thereon; a backlight for outputting light to the liquid crystal panel; and a controller for controlling a voltage applied to said liquid crystal layer; wherein each pixel of said liquid crystal panel individually has a reflective portion for reflecting and displaying light incident from the display screen side, and a transmissive portion for transmitting and displaying light that is output by said backlight; said controller independently controls voltages applied to said liquid crystal layer in said reflective portion and said transmissive portion to switch a viewing angle of said liquid crystal panel between a wide viewing field mode and a narrow viewing field mode, said each pixel has luminance viewing angle characteristics such that luminance of cancelling data display, which is pseudo-information display, of said reflective portion is greater than luminance of normal display of said transmissive portion in a wide viewing angle region greater than a certain viewing angle, and that the luminance of the normal display of said transmissive portion is greater than the luminance of the cancelling data display of said reflective portion in another viewing angle region, the normal display of said transmissive portion independently has wide viewing field angle characteristics of being viewable in the wide viewing angle region and the another viewing angle region, said controller controls said voltages such that said reflective portion performs the cancelling data display while said transmissive portion performs the normal display, so that the cancelling data display with the luminance greater than the luminance of the normal display causes the normal display of said transmissive portion to be unviewable in the wide viewing angle region, and the normal display of said transmissive portion with the luminance greater than the luminance of the cancelling data display is viewable in the another viewing angle region, thereby achieving the narrow viewing field mode, and said controller controls said voltages such that said reflective portion performs the normal display or dark display while said transmissive portion performs the normal display, so that the normal display of said transmissive portion is viewable in the wide viewing angle region and the another viewing angle region, thereby achieving the wide viewing field mode.