GB606324A - Television system for transmitting and receiving pictures in stereoscopic relief - Google Patents

Abstract

606,324. Television. FARNSWORTH TELEVISION & RADIO CORPORATION. March 1, 1946, No. 6470. Convention date, March 29, 1945. [Class 40 (iii)] A stereoscopic television system comprises means for periodically reversing at a predetermined frequency the polarity of successive groups of picture signals produced in a picture signal-generating tube, means for reproducing a television picture from said groups of-picture signals and means for displacing the reproduced images due to groups of signals of one polarity with respect to those due to groups of signals of opposite polarity. The polarity reversal of the picture signals developed across the load resistor 23 of an electron-multiplier 5 associated with the image dissector tube 1, Fig. 1, is effected by applying to an electrode 10 of the multiplier keying voltage pulses from generator 27 which alternately vary the potential of the latter electrode with respect to the final multiplier stage 8. The signals thus produced are transmitted in conventional manner by means of transmitter 32. The relative displacement of the two groups of picture signals, necessary to produce a stereoscopic result, is effected at the receiver, Fig. 3, by supplying the horizontal deflecting coils 91 (or the vertical deflecting coils) with a current pulse, superimposed on the normal scanning waveform, during alternate field scanning cycles. These current pulses comprise symmetrical square wave-pulses 101 developed by a multivibrator 100 under the control of rectangular pulses 98 produced by a differentiating amplifier 96 fed with saw-tooth waves from the fieldscanning generator 94. In place of the above receiver arrangement a conventional receiver may be employed and the necessary image dis. placement effected at the transmitter. An alternative method of producing the image displacement comprises means for keying either the vertical or horizontal synchronising ,pulses so that the time delay between the beginning of each blanking pulse and the beginning of each synchronising pulse changes at a predetermined frequency, Fig. 2 (not shown). As applied to the transmitter, these means include the circuit 45, Fig. 1, in which horizontal synchronising pulses from a generator 18 are fed to valves 47, 48 arranged to conduct alternately under the control of keying pulses from the generator 27, a delay network 70 being included in the output circuit of valve 47 to effect a predetermined delay to the horizontal synchronising pulses which are then fed to the horizontal scanning generator 16. Instead of the electron-multiplier keying arrangement for reversing the polarity of the successive groups of picture signals a reversing amplifier in which the number of stages is varied at the required frequency may be employed.