GB552659A - Colour television signal-translating system - Google Patents

Abstract

552,659. Colour television; cathode-ray tubes. HAZELTINE CORPORATION. March 27, 1942, No. 4105. Convention date, April 28, 1941. [Classes 39 (i) and 40 (iii)] A colour television signal-translating system comprises a cathoderay tube having a plurality of spaced targets associated with respective optical systems and cathode-ray beams, one for each colour, the cathode-ray beams being arranged to pass through a restricted region where a single set of beam-deflecting means are provided to cause the scanning action of all the beams. In the transmitter shown in Fig. 1, the picture 23 is imaged by three optical systems 22a, 22b, 22c with colour filters 24a, 24b, 24c on three spaced targets 21a, 21b, 21c in the cathode-ray tube 20, which also contains three separate cathodes 25a, 25b, 25c, three separate control grids 26a, 26b, 26c, first and second accelerating anodes 27, 28, and a common collector anode 29. The three beams cross each other in a restricted region where they are subjected to a single set of line and field scanning means of the electrostatic or magnetic type. The magnetic type is indicated on the Figure by the windings 32, 33 and 34, 35. The three spaced targets, which may be separate screens or parts of one screen, are connected to the output impedance 36, from which the signals are fed to an aerial system 14, 15 through the usual channel 11, 12, 13. The scanning windings are supplied from usual circuits 16, 17 connected to the synchronizing signal generator 18. The three cathoderay beams are triggered in succession by pulses 39a, 39b, 39c fed to the control grids 26a, 26b, 26c from relaxation oscillators 38a, 38b, 38c controlled by the synchronizing signal generator 18. These pulses 39a, 39b, 39c serve also to modulate supersonic oscillators 44a, 44b, 44c, the output of which is mixed with the audio frequency from a generator 43 and fed through a sound transmitter 40 to an aerial system 41, 42. The receiver, Fig. 2 (not shown), is similar to the transmitter, the supersonic signals being separated from the audiofrequency and then divided into its three constituents by means of tuned circuit to trigger the three cathode-ray beams in succession. Instead of transmitting supersonic signals for the keying of the successive cathode-ray beams of the receiver, this may be performed by the provision at the receiver of relaxation oscillators corresponding to the oscillators 38a, 38b, 38c of the transmitter. Instead of rendering each cathoderay beam operative in turn by means of the pulses 39a, 39b, 39c, the beams may be arranged to be normally operative and the pulses arranged to suppress in succession the unwanted beams.