Videoscope—A High-Gain, Color Television Screen-Process System

Tanji Kishino

For broadcasting monochrome TV programs, Japan Broadcasting Corp. (NHK) has been using a screen process in which video signals are projected by Eidophor. When these programs were to be rebroadcast in color, it was found that the screen brightness was insufficient for the color camera; therefore, color slides were used. However, this method also proved inadequate, because, although it required considerable time and effort to improve the brightness, the pictures turned out unsatisfactory in other respects. To overcome this, the “Lumiscope” was developed in 1967. The Lumiscope is a 1010- × 1320-mm lens made of sheet plastic which is capable of focusing the light from the projector into the camera without reducing the side-edge luminance. At the same time, it ensures a gain some hundreds of times greater than that obtainable from a conventional screen. This high-gain screen has been incorporated in a system called the “Videoscope,” consisting of camera, lens screen, and a projection-type color TV receiver which contains three picture tubes (one for each primary color) and red- and blue-reflecting dichroic mirrors. With the Videoscope system, it is possible to project any arbitrary color video signal with high brightness, at low cost, and under stable operation.

Print ISSN
Published
1970-06
Content type
Original Research
DOI
10.5594/J10680