GB553532A - Improvements in and relating to electronic valve devices - Google Patents

Abstract

553,532. Cathode-ray tubes ; thermionic circuits. INTERNATIONAL TELEVISION CORPORATION, Ltd., NAGY, P., and GODDARD, M. J. July 23, 1941, No. 9309. [Classes 39 (i) and 40 (v) ] In beam deflection valves, an auxiliary electrode system is provided adjacent the target electrode O, Fig. 1, and collecting electrode E1, whereby, on the application of suitable potentials thereto, the passage of secondary electrons to and from the target electrode is controlled. As shown in Fig. 1, the auxiliary electrode system consists of an electrode E2 and a grid E3 disposed at the side of and across the electron beam in its passage to the target. The system is connected to the collecting electrode and by maintaining it at a definite potential relatively to the target, the secondary electron emission generated by the impact of the beam is either wholly suppressed or wholly transferred. Preferably the target is inclined as shown, and the beam in the form of a strip is focused to pass across the edge Z. In this arrangement, by making the secondary electron emission co-efficient greater or less than 1, the deflection sensitivity of the valve is increased or decreased by the impact of the beam on the target. Volume control may be effected by altering the focus of the beam ; this may be done by varying the potentials of the first anode A1, or the deflection plates P1, P2 or by an additional electrode E11. Where it is desired to avoid reaction between the beam and the electrode E2, the arrangement of Fig. 4 (not shown) may be used. An arrangement in which the target electrode is alternately charged positively and negatively is shown in Fig. 3. The collector electrode E1 and the target electrode O have a secondary electron emission co-efficient greater than 1. Impact of the beam on the target charges it positively by secondary emission which goes to the electrode E3. Secondary emission from the collector electrode is prevented from reaching the electrode E3 by the system E8, E7 and goes to the target, which is thus charged negatively. A simplified form of this arrangement is described with reference to Fig. 3 (not shown). The Specification describes the application of the invention to circuits for amplifying, detecting, frequency changing and oscillation generating. In the frequency changing circuit, the local oscillator may be incorporated in the electron beam valve, Fig. 6 (not shown). Specifications 366,053, 443,364, 467,573, 476,653 and 553,530 are referred to.