GB1535192A - Multiple beam cathode ray tube arrangements - Google Patents

Abstract

1535192 Electron beam magnetic deflecting apparatus LICENTIA PATENT VERWALTUNGS GmbH 12 Dec 1975 [21 Dec 1974] 50952/75 Heading H1D An in-line multiple beam cathode-ray tube has line and field deflection coils with a ring-like core 5 having recesses 6 diametrically opposed and each containing a magnet 9, the magnets producing fields each having a static component and substantially transverse to the plane of the beams and effecting line-direction dynamic convergence. Preferably three beams are present and Fig. 1 (not shown) includes vertical and horizontal deflection coils 3, 4. The magnets may be electromagnets fed with adjustable direct current, and dynamic correction currents as required, or permanent magnets 9 magnetized diametrically and movable parallel to the plane of the beams. In Fig. 2, magnets 9 are adjustably secured to a holder (not shown) which is secured either to the tube neck or to core 5. Magnets 9 may be additionally rotatable about their axes and movable in the direction of the tube axis, and their axes may be slightly inclined to the tube axis 12 to compensate for axial errors of the tube system. The polarities of the magnets are mutually opposed in the vertical direction for symmetrical errors and similarly magnetized for asymmetrical errors. Dimensions are given. Vertical direction dynamic convergence may be effected for example by toroidal coils. The correcting action is greater at the periphery than at the centre (Fig. 3, not shown) and any remaining misconvergence in the centre may be compensated by an additional static convergence device. Raster error caused by the deflection unit may also be corrected.