| 摘要 |
440,560. Cathode-ray tubes. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, Berlin. May 28, 1934, No. 15780. Convention date, May 27, 1933. [Class 39 (i)] Magnetic fields are produced in Braun tubes with picture screens for television &c. by means of pole-shoes inside the evacuated envelope of the tube and a field generator outside the envelope, both extending as close as possible to the envelope to reduce the gap between them and the shoes extending as close as possible to the ray. The magnetic field deflects or concentrates the ray and the pole-shoes may act simultaneously electrostatically to control the intensity of the ray or to concentrate or deflect it. An opposed pair of pole-shoes may deflect the ray horizontally and vertically at the same point along the tube, one deflection being electromagnetic and one electrostatic. The pole-shoes may be layers 3, 4, Fig. 4, of permalloy or steel on an apertured copper diaphragm 16. In a modification, semicircular pole-shoes are separated at each side of a central hole by a copper strip to form an apertured disc anode. For electrostatic concentration of the ray, one side of the pole-shoes is concave. Before reaching the usual deflecting plates, the ray may be given a preliminary constant deflection by passing between two polepieces co-operating with rotatable half-ring magnets 1, Fig. 3, the field of which is varied by adjusting a magnetic shunt consisting of loops 13, 14 joined by a strip 15. The ray from a cathode 18, Fig. 7, is concentrated by the magnetic field between pole-shoes 19, 20 co-operating with a coil 31, is modulated by control potentials applied to the shoes 19, is successively deflected whilst moving at slow and preferably constant speed by the fields of pole-shoes 24, 25 and is finally accelerated by an anode 26. Screens 21, 22 are continued outside the tube and provided with a constant bias. The tube is highly evacuated or gas-filled, preferably at a pressure of 10<-4>-10<-5> mm. To compensate for variations in the anode voltage, the currents through the coils producing the magnetic fields increase with this voltage. |
