GB675261A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

675,261. Cathode-ray tubes; luminescent materials. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 4, 1945 [Oct. 7, 1944], No. 25849/45. Class 39 (i). Electric discharge device of the type comprising a cathode, a fluorescent anode and two deflecting members connectable each to a separate voltage source so that the fluorescent pattern on the anode indicates a voltage difference between the sources has the deflecting members 5, 6, Fig. 1, in the form of plates or vanes in the same plane substantially parallel to and on the same side of a rectilinear cathode 1, the deflecting members having adjacent faces parallel to and at a short distance from each other so as to form together an elongated structure with a gap or slot extending between its longer sides. The fluorescent anode 2 is planar and parallel to the cathode and is formed from a nickel plate having a coating 3 of zinc orthosilicate deposited thereon from a suspension of that material in alcohol. The cathode 1 is supported by conductors 16 from a shield member 4 which is positioned behind the cathode to direct the electron beam towards the anode. In the construction shown in Fig. 2 the shield is of angular cross-section with both sides inclined to the anode 2 and the deflecting members 5, 6 lie in the same plane as part of the shield. In the construction shown in Fig. 5, the deflecting members 5, 6 are parallel to the anode 21 which has an overhanging portion 20 to obscure the edge portion of the anode. The above constructions give a kinked line separation between the light and dark portions of the anode when different voltages are applied to the deflecting members 5, 6. In the construction shown in Fig. 7 the shield 4 is of T crosssection, and the deflecting members 23, 24 are separated by an inclined slot. This arrangement gives an inclined indication on the fluorescent anode 2 according to the difference in magnitude of the voltages impressed on the deflecting members 5, 6. Fig. 8 shows a construction in which the shield 25 is of box formation and in which a masking 27 having an elongated aperture 27<SP>1</SP> is supported at 26 from the anode 2. More than two deflecting members can be arranged so that groups of two deflecting members have adjacent edges or end faces to form gaps between them and are connected to separate voltage sources.