Patent GB-523263-A (GB)
Title: Improvements in or relating to the distribution of electric signals
IPC: H04J14/08
Filed: 1938-12-29
Abstract: 523,263. Thermionic distributers; television. TOULON, P. M. G. Dec. 29, 1938, No. 37779. Convention date, Jan. 5, 1938. [Classes 40 (iii) and 40 (v)] The distribution of electric impulses arriving successively through a single channel between different branch lines, or the successive transmission along a common channel, of signals simultaneously generated by several transmitters is effected by blocking elements in the various channels. controlled by a succession of peaked waves. A row of electro-optical elements 1, 1<SP>1</SP> &c., Fig. 1, are connected in the anode circuits of the tubes T, the second control grids of which are all connected to conductor 25, which is fed with vision signals from terminals 52. The tubes T are normallv all blocked by potential from source 31 fed over resistances 26, and a resistance-condenser combination 24, 44, 45 is provided in each anode circuit to prolong the effect of the impulse when the valve is made conducting. The light from elements 1 is reflected by a mirror drum 2, which is driven by the synchronous motor 5 and provides the vertical scanning on the screen 4. An oscillator 7 is synchronized with the horizontal line-scanning frequency F supplied at terminals 6, and feeds into the network 15, 17, 18, 19, 20, which produces a four-phase supply of frequency F on the conductor 10, 11, 12, 13. Oscillators 8, 9, are also synchronized with oscillator 7 and produce multiple-frequency (F<SP>1</SP>, F<SP>11</SP>), supplies on conductor systems 10<SP>1</SP>, 11<SP>1</SP>, 12<SP>1</SP>, 131 and 10<SP>11</SP>, 11<SP>11</SP>, 12<SP>11</SP>, 1311. In conjunction with two of the conductors of each four-phase supply are arranged capacity elements such as 27, 28 ; 29, 30 ; 31, 32 ; which together produce three approximately-equal voltage vectors of different frequency which combine to give a peaked wave. This is arranged to unblock the valve T, by virtue of its connection to the first grid G, once only during the cycle of the fundamental frequency of oscillator 7. By selection of the size and position of the capacity elements connected to the first grids G<SP>1</SP>, G<SP>11</SP> of the succeeding valves T<SP>1</SP>, T", it is arranged that all the valves T become conducting in turn for the period when the voltage peak exceeds the cut-off bias. Instead of hexode valves T, T<SP>1</SP>, etc., which amplify the vision currents, diodes may be employed to block the various channels. In some cases an auxiliary carrier of high frequency is employed and modulated by the frequencies F, F<SP>1</SP>, F", in which case the envelope of the modulated carrier has the peaked form. The advantage of this method is that the capacity elements 27, 28, etc., may be smaller. Figs. 4 and 5 show an embodiment of the capacity elements of Fig. 1. Sheets of mica 33 have independent conductive deposits 36, 37. &c. on one side, which correspond to the twelve conductors of the three four-phase systems, and mica sheets 34, Fig. 4b, are arranged between sheets 33 in a stack and have a conducting deposit 40, 41, 42, 43, so shaped as to provide the capacities to the requisite phases of each four-phase system. The edges of the conducting segments on the sheets 33 are connected up by conducting layers 50, Fig. 5, deposited on the edge of the pile of sheets. The conductive portions 43 on sheets 34 are connected to the respective grids G of the valves T.