Bulletin of the Association of Swiss Electricians

SUBJECT AREA: Broadcasting, Electronics and information technology

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Fischer was a professor of engineering at the Swiss Federal Institute of Technology in the late 1930s. Interested in the emerging technology for television, he was of the opinion that the growth of television would take place through the development and use of large-screen cinema-type displays serving large audiences. He therefore carried out research into suitable techniques. Realizing the brightness limitations of projection systems based on the optical magnification of the image produced by a conventional cathode ray tube, he used the deflected electron-beam, not to excite a phosphor screen, but to deposit a variable charge on the surface of a film or oil. By means of a Schlieren slit system, the consequent deformations of the surface were used to spatially modulate the light from an electric arc or a discharge tube, giving a large, high-brightness image. Although the idea, first put forward in 1939, was not taken up for cinema television, the subsequent requirement of the US National Aeronautics and Space Administration in the 1960s for large colour displays in its Command and Control Centres led to the successful development of the idea by Gretag AG, a subsidiary of Ciba-Geigy: separate units were used for the red, green and blue images. In the 1990s, colour Eidophor projectors were used for large conference meetings and pop concerts.

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