Eidophor
From Wikipedia, the free encyclopedia
An Eidophor was a television projector used to create theatre-sized images. Its basic technology was the use of electrostatic charges to deform an oil surface.
Developed by the Swiss Federal Institute of Technology and Dr. Edgar Gretener A.G., Eidophors used an optical system somewhat similar to a conventional movie projector but substituted a slowly-rotating mirrored disk or dish for the film. The disk was covered with a thick transparent oil and through the use of a scanned electron beam, electrostatic charges could be deposited onto the oil, causing the surface of the oil to deform. Light was shone on the disc via a striped mirror consisting of strips of reflective material alternated with transparent non-reflective areas. Areas of the oil unaffected by the electron beam would allow the light to be reflected directly back to the mirror and towards the light source, whereas light passing through deformed areas would be displaced and would pass through the adjacent transparent areas and onwards through the projection system. As the disk rotated, a doctor blade discharged and smoothed the ripples in the oil, readying it for re-use on another television frame.
Simple Eidophors produced black-and-white images. More complex Eidophors produced sequential red, green, and blue fields, allowing the reproduction of a color image.
