Image projection display and pick-up apparatus with optical shutter

Claim 1

An image projection display and pick-up apparatus operating in a display mode and a pick-up mode and comprising: a viewing screen with controllable transmissivity; an image projection device disposed behind the screen comprising image display means for generating a picture and means for projecting this picture on the back surface of the viewing screen to thereby display the picture image to a viewer in front of the viewing screen; an image pick-up device disposed behind the viewing screen for taking pictures of the viewer through the screen: the image pick-up device and the image projection device being arranged one above the other; and characterized by the presence of a controllable shutter in the image projection device, which shutter is kept opaque during the image pick-up mode, thereby preventing light from the image projection device from reaching the viewing screen during the image pick-up mode and the image pick-up device being arranged relative to the shutter so that no light from the viewer is prevented by the shutter, from reaching the image pick-up device and is prevented, by the image pick-up device, from reaching the shutter and wherein the projection device comprises in this order: a light source, a transmission type video display element and a projection lens, said shutter being arranged between the light source and the projection lens.