The present invention relates to a liquid crystal display apparatus, and especially to an active matrix-type liquid crystal display apparatus.
In conventional active matrix-type liquid crystal display apparatus, a twisted nematic mode, a lateral electric field mode, MVA (Multidomain Vertical Alignment) mode, and so on which use nematic liquid crystal are used. Further, in those liquid crystal display apparatuses, there is a display method called a “hold type” display method, and in this display method, the same image is displayed during one display period of an image signal, that is, during one frame period.
When dynamic images are displayed on the “hold type” crystal display apparatus, one image of the dynamic images which actually change moment by moment is held during one frame period. That is, although one point in the displayed image is displayed at the correct position at one moment, the point in the displayed image is different from the actual point in other moments. Thus, since a human perceives dynamic images by averaging the displayed images, the perceived images are not focused.
A paper “Improving the Moving-Image Quality of TFT-LCDS” by K. Sueoka et al., IDRC '97, pp 203–206 (1998) discloses a technique in which, after the whole display panel has been scanned, a lighting device is turned on to eliminate the lack of focus due to the above averaging effect.
However, in the above technique, since the lighting device is turned on after the whole liquid crystal panel has been scanned, and the response of the whole liquid crystal has been completed, the scanning period and the response time must be significantly shortened. Also, since the lighting period of the lighting device is short, the light strength must be increased in order to achieve the same brightness as that in a conventional liquid crystal display method. Thus, it is necessary to increase the light-tube current, which in turn decreases the lifetime of the lighting device.