GB494672A - Improvements in cathode ray deflecting devices - Google Patents

Abstract

494,672. Cathoderay tubes. MARCONI'S WIRELESS TELEGAPH CO., Ltd. April 26, 1937, No. 11891. Convention date, April 25, 1936. [Class 39 (i)] In a cathode-ray tube using magnetic deflection for scanning, current for producing a deflection in one plane is passed through two or more pairs of coils the current for effecting deflections in the plane at right-angles thereto being passed through the same or another set of coils ; the increased number of coils reduces the distortion of the beam. In one form eight coils 13, Fig. 2, are all on separate polepieces of a core 12 and are in series, the incoming vertical deflection current is supplied by the leads 14, 16 and the horizontal deflection current by the leads 17, 18 the pole markings N, S, at the pole tips corresponding to the horizontal deflection effect. This form of coils may be applied to a core with only four polepieces. In a modification two diametrically opposed pairs of coils 34, 36 and 37, 38, Fig. 3, form the main deflecting coils ; on each of the four polepieces 29, 31, 32, 33 are two independent coils, one of which is used with the vertical, the other the horizontal deflection means. For example coils 39, 41 are in series and in parallel with coils 34, 36 ; these poles 31, 32, 33 act as shading poles and the numbers of windings in the coils in both constructions need not be the same on all the polepieces. The deflection currents are supplied through transformers but the supply for the horizontal deflection may be direct. The windings on some of the poles as shown in Fig. 2 may be reversed.