Patent GB-519653-A (GB)
Title: Improvements in or relating to electron multiplier arrangements
IPC: H03K4/10
Filed: 1938-09-21
Abstract: 519,653. Cathode-ray tubes and electron multipliers and circuits therefor. KOLSTERBRANDES, Ltd., and BEATTY, W. A. Sept. 27, 1938, No. 28112. [Classes 39 (i), 40 (iii) and 40 (v)] Apparatus for amplifying, modulating, or the production of oscillations of a particular wave-form or frequency comprises two or more electronmultiplier structures with feed-back from one or more of the structures to intensity-controlled means (grids) or deflection-controlled means (electrostatic plates or electro-magnetic coils) for controlling the flow of primary electrons. Fig. 2 shows an arrangement having a primary cathode K, a control grid G1, an accelerating electrode G2 producing an electron beam, two pairs of deflecting electrodes D, D1, and two multiplier branches each comprising five secondary emitting electrodes P1, SE1...SE4., P2, SE1a... SE4a and output anodes A1, A2. As shown, the outputs are connected in push-pull and oscillations are produced by a feedback from the tuned circuit L1, C1 to the plates D. The apparatus may be used as a frequency-changer by applying a high-frequency signal to grid G1, producing local oscillations by feedback from one pair of secondaryemitting plates SE1, SEla through a tuned circuit to plates D, and connecting circuits tuned to the beat frequency across the remaining multiplier stages. For this purpose, the plates P1, P2 are shaped as in Fig. 4, a section of the beam being shown at B. For use in amplifying television signals and simultaneously separating line and frame synchronising pulses, plates P2, P3, Fig. 7, shaped and arranged as shown, form the primary cathodes of the multiplier branches (corresponding to P1, P2, Fig. 2) and additional plates P1, P4 (which may be non-emitting and imperforate parts of P2, P3 respectively) are used for taking off line and frame pulses. The beam B, deflected in directions 9, 10 by incoming signals applied to plates D engage plate P2 for all signals above the 30 per cent. black-out level and an amplified signal is taken off from the anode of the corresponding multiplier branch. On the arrival of a 0 per cent. synchronizing pulse the beam moves off P1 and strikes P3, the output of which is coupled back to plates D1 so that the beam is deflected in the direction 11 moving to point 12 for each line pulse and on to plate P4 for a frame pulse. At the end of each pulse the deflecting circuit associated with plates D1 is discharged by a valve circuit. For'the production of square-shaped pulses, a beam focussed to a spot is moved in direction 13 by alternating current 15...21 Fig. 8, applied to plates D. The spot moves across plate P1 during the period 16, 17 and then on to plate P2 which is coupled back to plates D1 so that deflection takes place in direction 14 and no pulse is produced in P1 during the period 18, 19. Amplifier pulses are taken from the anode of the multiplier branch associated with P1. For the production of saw-tooth or other specialshaped waves, beam B, Fig. 5, is moved by a controlling pulse applied to plates D on to plate PI which is coupled back to D so that movement continues in direction 23 and amplified waves of a shape determined by the shape of P2 are produced in the multiplier branch associated with P2. In a modification, Fig. 6 (not shown), in which there is no external controlling pulse, the beam is normally resting on the top edge of P1 and a further electrode is provided near the bottom of P1 to discharge the control circuit and return the beam to its initial position. When employing more than two multiplier branches or more than two beams, the invention is stated to be applicable to automatic control of volume, frequency, or selectivity, and to the provision of phasereversal feed-back. The section of the beam may be circular, rectangular,.,or of L, T, or X shape. Specifications 447,039, 493,217 and 495,839 are referred to.