PURPOSE:To apply an existing device constitution unified with liquid crystal to another purpose by increasing the sending speed of data for display of images with use of a memory which temporarily stores the image data to secure a non-display period and by detecting coordinates in this non-display period. CONSTITUTION:A clock generating circuit 26 generates a display control signal to control a period when the images are displayed on a liquid crystal display panel and a period when no image is displayed on the panel respectively based on another display control signal. The image data which are sent by the timing of the first display control signal are given to the frame memories A21 and B22 via the data selectors 30 and 31 respectively. Meanwhile the image data are sent from both memories 21 and 22 by the timing of the second display control signal. Thus the memories 21 and 22 alternate with each other for each frame between the writing and reading modes. Therefore, the image displayed on the liquid crystal panel is delayed by a single frame. As a result, a non-display period is secured.
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