ES338880A1 - Geodesic electromagnetic deflection yoke - Google Patents

Abstract

An electromagnetic beam deflection yoke, particularly for a three gun shadow mask colour television tube, comprises a pair of horizontal and a pair of vertical deflection coils each of which is formed by two spaced groups of side conductors 24, 25, which extend longitudinally of the tube and lie along a geodesic line following the curvature of the flared bulb section of the tube, joined by front and rear groups of end conductors 26 and 27 respectively extending transversely to define a window area 28. Preferably, in order to obtain a wide angle deflection with a minimum of raster distortion and coma, and selected astigmatism, the distribution of side conductors in transverse cross-section shifts progressively from uniformity at the rear end of the coil to a minimum at the inner edge of the window area and a maximum at the outer edge at the front end of the coil, Figs. 5 and 6 (not shown). The winding distribution and shape of the coils is obtained by particularly designing the shape of the curved sides of a window block and the configuration of the cavity formed between the male and female halves of an arbour comprising the window block and a mating cap which are used in a conventional coil winding machine. The relationship between the radii of the inner and outer surfaces of each coil is discussed, Fig. 7 (not shown).