GB1416726A - Colour television display apparatus provided with a picture display tube with electron beams generated in one plane - Google Patents

Abstract

1416726 Cathode-ray tubes PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 19 Dec 1972 [22 Dec 1971] 58495/72 Heading H1D In a multi-beam colour television tube in which the beams are generated in a common plane, the colour selection angle is increased, without enlarging the tube cross-section; by use of a deflection system which includes a magnetic core on which coils for deflecting the beams in a pair of orthogonal directions are wound, together with means for producing at the deflection region a static, magnetic, quadripolar field, the poles of which lie on the diaagonals between the deflection directions, whereby beams which are initially diverging and are subsequently rendered less diverging (Fig. 2a, not shown) or converging (Fig. 2b, not shown), or beams which are initially parallel but are subsequently rendered diverging, Fig. 2c, are converged on to the screen S at an angle α. The arrangement for producing the quadripolar field may comprise four auxiliary D.C. fed coils 20 to 23, Fig. 3, serially connected and successively reverse wound on the deflection yoke, at positions lying in the deflection co-ordinate planes; or similarly situated and tangentially mangetized permanent magnets; or four diagonally arranged saddle coils (Fig. 4, not shown); or four similarly situated and radially magnetized permanent magnets. Alternatively, the deflection coils themselves, if toroidally wound, may be employed to produce the quadripolar field, by connecting the two opposed portions of the vertical or horizontal coils in parallel to the deflection signal genera tor; but in series with one another and a D.C. current generator (Fig. 5, not shown). Dynamic convergence may be provided by superimposing on the quadripole D.C. sources a sawtooth current at line or field frequeney, while centering may be effected by D.C. currents superimposed upon the deflection signal.