GB1226614A - - Google Patents

Abstract

1,226,614. Colour television tubes. SONY CORP. 8 July, 1968 [10 July, 1967; 12 July, 1967], No. 32444/68. Heading H1D. In a colour television display tube in which a plurality of beams B B , B G and B R lying in a common plane intersect at the centre of the main focusing lens L and are converged laterally to a common point at the colour selection grid or shadow mask Gp by a system F which, as shown, comprises a centre pair of shielding plates P, P<SP>1</SP> and an outer pair of deflection plates Q, Q<SP>1</SP>, a coil 16 is provided to generate an axial flux in the vicinity of the lens L in order to effect a twisting displacement of the outer beams B B , B R about the axis of the system. By this means vertical misconvergence of the beams at the screen may be corrected, such misconvergence being due, e.g., to mechanical twist of the plane in which the beams are emitted, to spherical aberration of the deflection yoke D, to various other mechanical errors, or to the effect of the earth's magnetic field. Static vertical misconvergence is corrected by supplying current to the coil 16 from an adjustable D.C. source 17; dynamic vertical misconvergence is corrected by supplying to the coil 16 from source 18 saw tooth waves synchronized with the horizontal and vertical sweep signals applied to the deflection yoke. Dynamic horizontal misconvergence is corrected by applying a dynamic convergence deflection voltage synchronized with the horizontal sweep signal across the plates P, Q and P<SP>1</SP>, Q<SP>1</SP> of the convergence system F. Lateral shift of the beams B R , B B due to the earth's magnetic field may be corrected by a ring magnet 22 having two oppositely wound, series-connected coils connected to an adjustable D.C. source 25. The magnet 22 and the coil 16 may be included in a coil assembly having an insulating support 28, Fig. 9, provided with radial flanges 32, 33. Coil 16 is wound between flanges 32, 33 and the core of magnet 22 is formed in two halves 23a (23b), each half having end holes for receiving support pins 36 projecting axially from flange 33. All the beams may be laterally shifted by a further colour purity magnet 40, Fig. 1, similar to the magnet 22. The magnet 40 is mounted on screws (49, Fig. 11) extending through an end flange (45) of the deflection yoke assembly D. The magnets 16, 40 may be constituted by rotatable permanent ring magnets.