Patent ID: 6862005

Claim:
An image signal generating apparatus which transmits an image signal to a plurality of display units each having identification data, comprising: an image signal generator which sequentially generates an image signal for each frame that is an image signal for displaying one page image in one frame period, the one page image being an image to be displayed on each of the plurality of display units; an indexer which adds an index signal to the image signal for each frame; an image signal output circuit which sequentially transmits the image signal for each frame to the plurality of display units, thereby causing any of the plurality of display units having identification data corresponding to the index signal added to the transmitted image signal for each frame to display an image based on the transmitted image signal for each frame; and a window controller which causes the plurality of display units to display a window under control of an application software, holds display position information of the window, and controls input and output of data using the window; wherein, when the index signal added to the image signal for each frame is changed to an updated index signal, the window controller transforms the display position information of the window in accordance with the updated index signal.