GB1223969A - Convergence deflecting device for single-gun, plural-beam color picture tube - Google Patents

Abstract

1,223,969. Colour television tubes. SONY CORP. 9 April, 1969 [14 April, 1968], No. 18063/69. Heading HID. In a colour television receiver tube of the type wherein three co-planar beams diverge from a common focusing lens and are converged on to a shadow mask or the like by two pairs of deflection plates, the latter are curved in the direction normal to the plane of the beams to correct for raster errors. In Fig. 7 the three beams B R , B G , B B lie in a horizontal plane and the deflection plates PP<SP>1</SP>, QQI are divergently curved in a vertical plane. This corrects for raster errors (Fig. 3, not shown) caused by the outside beam following a longer path in the field of the magnetic deflecting yoke than the inside beam or the centre beam at large deflections; at zero vertical deflection (i.e. in the central positions of the beams as shown) the error in horizontal deflection may be corrected by a non-uniform scanning field but the error remains at large vertical deflections unless corrected as described. In modifications the inner plates P (Fig. 4, not shown) or the outer plates Q (Fig. 5, not shown) are planar. For correcting the opposite type of raster error the plates are curved in the opposite sense (Figs. 6 and 8, not shown). When there are two sets of convergence deflection plates the set nearest the magnetic deflection yoke should be shaped as described.