GB443364A - Electronic tube - Google Patents

Abstract

443,364. Cathode - ray tubes and circuits. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, Berlin. July 26, 1934, No. 21824. Convention date, July 26, 1933. [Classes 39 (i) and 40 (v)] In electron discharge devices in which the current to the anode is controlled by transverse deflection of the electron stream to an extent varying with the control, the cathode or an aperture in an intermediate diaphragm is electron-optically reproduced in the plane of the anode by means of an electron-optical system other than the deflecting means and between the cathode and the anode. The cathode and aperture are preferably of great length compared with their width and the electron-optical system may act in one coordinate only similarly to a cylindrical lens. The cathode 6 is mounted in a semi-cylindrical electrode 7 concentrating electrons on to a slit in an electrode 8, and this slit is reproduced in the plane of the anode 11 by an electron-optical condensing system consisting of three slotted plates 1, 2, 4. The centre plate 2 is negative with respect to the outer plates and is provided with flat extensions 3, 5 on opposite sides of the electron stream. The plate 2 may be connected to earth and to the electrode 7, the electrodes 8, 1, 4 being connected together. Auxiliary anodes are formed by a plate 12 forming a mirror image of, and in the plane of, the plate 11 and by a coating 13 on the glass wall of the tube. The separation between the plates 11, 12 is small and the separating line 18 may be curved to give a variable-mu effect. If the undeflected beam falls at one end of the line 18, the tube rectifies : if at the centre of the line, the tube amplifies. The anodes 11, 12 may be connected to the same voltage supply through separate resistances to give outputs of opposed phase. The beam may enter the space between the deflecting plates obliquely and be restored to an axial direction by biassing the control plate 9 or 10 negatively, thus avoiding electron current to the control plate. Control potentials may be applied with opposed phases to the two plates 9, 10. One deflecting plate 10 may be connected to the anode 11 connected to a tuned circuit to generate oscillations. The beam may be deflected in two directions by two controls to operate as a modulator or as a mixing valve in a heterodyne receiver. The plates 9, 10 may be inclined as shown and deflection in two directions may be electrostatic or magnetic : electrostatic deflecting plates may act as magnetic poles for deflecting the ray magnetically in another direction. The tube may be shielded from external electrostatic or magnetic fields by enclosing it in a closed container 14 of iron &c. and this container may be provided with the usual valve base. A screening diaphragm may be arranged between the deflecting plates and the anodes. To avoid errors due to deflective focusing near the ends of the slits in the diaphragms, these slits have rounded ends or the anode 11 intercepts only the central part of the beam. The cathode may be directly heated and barium may be provided on the electrode 7 or in a separate container for activating the cathode and for producing a high vacuum. The electronoptical system may comprise a plurality of condensing or dispersing systems and the latter may be similar to the system 1.. 4 but with the central element 2 positive relatively to the outer elements 1, 4. Magnetic, or combined electrostatic and magnetic electron-optical systems, and the use of the tube in television receivers, are referred to.