GB1420793A - Colourdisplay cathode ray tube - Google Patents

Abstract

1420793 Colour television tubes PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 12 Oct 1973 [17 Oct 1972] 47749/73 Heading H1D In a shadow mask colour tube having phosphor stripes, the spacings between the centres of adjacent stripes, and between the three electron beams, are adjusted to take advantage of the fact that the seriousness of the subjective colour defect caused by mislanding of the electron beams decreases in the sequence: red beam on the green or blue phosphor; blue or green beam on the green or blue phosphor, respectively; and blue or green beam on the red phosphor. In Fig. 4, the width of the red stripe is increased at the expense of the adjacent blue and green stripes. In the black matrix screen shown in Fig. 6, the spacing between centres of the red stripes and the adjacent blue and green stripes is increased at the expense of the spacing between the green and blue stripes; in addition, the spacing between the impact areas of the red beam and both the green and blue beams is decreased with respect to the spacing between the blue and green impact areas. The observable colour defect may be still further reduced by positioning the red gun further from the blue gun than the green gun. The phosphor stripe spacings and beam impact spacings may be uniform in the centre of the screen and steadily increase to a difference of up to 20% at the periphery. Numerical data are provided. The phosphor screen may be produced by optical exposure of a photosensitive layer through the shadow mask, the desired spacings being obtained by suitable choice of light source positions. The shadow mask apertures may be interrupted by spaced reinforcing bridges, the phosphor stripes exhibiting corresponding interruptions.