GB505653A - Improvements in or relating to television and the like systems - Google Patents

Abstract

505,653. Television. SCOPHONY, Ltd., and OKOLICSANYI, F. Oct. 11, 1937, No. 27561. [Classes 39 (i) and 40 (iii)] The amplitude of a signal at any instant represents more than one optical property, of the area scanned at that instant. The properties may be the brightnesses of a plurality of elements or the colour components of one element of the picture. The signal can be represented by the formula A(xa<-1>+ya<-2> ... +ka<-n>), where a is the number of tone gradations in which the brightness of each element or colour is transmitted and x, y, k are the tonegradation integers for the brightnesses of the separate eleinents or colours at that instant. At least n-1 of the outputs of the scanning of the n elements or colours are individually limited to one of a values, and are then so modified that the respective, ranges of amplitude are a, a<2> ... a<n-1> times that of the remaining output. When the amplitudes are combined the resultant amplitude has the above formula. When an iconoscope is used, each of a plurality of cathode ray beams, which are produced by separate guns to scan the mosaic, is modulated by a different frequency and filters separate the signals which correspond to the respective simultaneously scanned areas. Fig. 1 (not shown). Alternatively an imagedissector tube has a plurality of anode targets, each of which scans one of the areas. For colour television images of the object are projected through differently coloured filters on the screens of a plurality of iconoscopes, Fig. 5 (not shown). The amplitudes of the outputs are limited to a gradations by deflecting an electronic beam to an extent dependent on the amplitude of the output. In the case of two outputs, they operate at right angles on the beam, which is incident on a composite electrode divided in a separate insulated fractions 19 in each direction (three as shown). Each part 19 is connected to a separate tapping on a resistance 21 which is in series with a resistance 23 of the same order as the internal resistance of the tube. The tappings are so arranged that the current through the tube, which varies according to the degree of deflection, complies with the above formula. To limit individual outputs to a gradations, one or more deflected beams are incident on one or more electrodes with a steps, Fig. 1, Provisional Specification (not shown). For reception a strip of light is deflected, according to the amplitude of the signals, over a composite filter which consists of parallel strips, each of which corresponds to one of the optical properties and is subdivided in accordance with the representation of that property by the corresponding amplitude ranges of the signal. Specification 439,236 is referred to.