Television Film Projector

a device for the television transmission of images from motion-picture film. A television film projector consists of a film-advance mechanism and an optoelectronic reading device, which converts the film image into a video signal. Modern types can transmit both color and black-and-white motion pictures.

Television film projectors may convert the light image into a video signal by means of conventional television camera tubes or flying-spot scanners. When conventional tubes are used, the image on each film frame is projected onto three separate photosensitive camera tubes (Plumbicons or vidicons) by a color-separation optical system. The optical system contains dichroic mirrors and prisms in combination with light filters, which makes it possible to separate the light flux into three color components—red, green, and blue. In television film projectors that use flying-spot scanning, the image is read from the film by a light beam formed by projecting onto the surface of the film a spot of light generated on the screen of an electron-beam tube, or projection kinescope. The beam is modulated as it passes successively over sections of the film having varying optical densities, and it is then separated into three component beams by a color-separation optical system. The beams are converted into video signals by photomultipliers. After amplification, the video signals are converted into a complete television signal.

Television film projectors currently being developed scan the transmitted image with a three-color laser beam and convert the light signals into electrical signals by means of a raster of semiconductor photosensitive diodes.