Gretag Aktiengesellschaft

Bruno C Rhomberg

Beat Frick

In an illuminating apparatus for projection purposes, in particular a film projector or television image projector by the eidophor system, four condensers are located around a source of light in a cube-shaped housing, the condensers reproducing via the use of deflecting mirrors, an image of the light source on several, spatially adjacent imaging mirror segments, which in turn reproduce the condenser images superimposed upon one another, via an output mirror, on an image aperture of the projection optics.

Illuminating apparatus for projection purposes

Light emitted by a source arrives through a system of lenses and a first system of bars on the control layer of a control element. The light is reflected and refracted in keeping with local deformation of the control element nad then conducted through a concave mirror, a second bar system and a further system of lenses onto a projection surface. The image to be amplified is reproduced by means of a system of lenses on a photoelectric conducting layer in the control element. A control layer is a layer of gel and is located between two electrodes in an alternating electrical field, which may be affected by the photoelectric conducting layer. The electrode adjacent to the photoelectric conducting layer is electrically insulated relative to the photoelectric conducting layer and is in the form of a strip grid, the strips of which are connected alternatingly to one or the other pole of a source of alternating voltage. One of the poles is connected with the other electrode. An automatic switch periodically alters the polarity of the strips of the electrode grid. The alternating polarity of the strips, and the electrically insulating layout of the photoelectric conducting layer, effect an improved modulation and reduce undesirable space charge effects.

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Hausen, Switzerland

Bruno C Rhomberg