DISPLAY DEVICE

PURPOSE:To prevent the display from being hindered regardless of an explainer placed in the front of the display surface and to sufficiently display a picture even in a bright room by displaying the display output of a computer on a video display device as the picture. CONSTITUTION:A control computer 11 sends the display output to a video projector 12 as a video signal. The projector 12 transmissively projects the picture on a display screen 13. An observer brings a pen 15 into contact with a digitizer 14 provided on the surface of the display screen. An interface 16 detects the contacting position of the pen 15 by the signal from the digitizer 14 and sends it to the computer 11 as a signal. The computer 11 outputs the locus of the contacting position as the display output and sends it as a video signal while overlapping it on information displayed at this time. Thus, the display output is displayed on the display screen as if it were written with the pen 15, and the display screen 14has the same function as a blackboard.