GB1166175A - Colour Display Cathode-Ray Tube - Google Patents

Abstract

1,166,175. Colour television tubes. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 12 Oct., 1967 [15 Oct., 1966], No. 46628/67. Heading H1D. In a colour television tube having a substantially rectangular colour selection electrode-as shown, a shadow mask 3, Fig. 1-provided with an axially extending frame 4 around its edge, the electrode is supported by at least three supporting members 7 which are each secured to the periphery of the frame at points V which are nearer the tube screen 2 than the points R at which they are supported from the tube wall, whereby when the electrode expands upon heating its resultant displacement will have a component directed towards the screen, such as to reduce the mis-register, caused by the expansion, between the apertures in the electrode and the associated groups of colour elements on the screen. As shown, the shadow mask is provided with three supporting members 7, 7<SP>1</SP>, which at one end are welded to the support ring 4 of the electrode, and at the other end are supported by the engagement of their perforated ends 8 with the conical bosses 6. Upon expansion of the mask, the points V describe arcs of circles, such that the mask apertures are displaced by B and P 1 to give a resultant displacement P 2 lying on the line joining the mean deflection centre D of the electron beam and the associated group of colour elements on the screen. Since it is undesirable that the two supports 7 arranged one along each short side of the electrode, Fig. 3, should be located at the mid-points of those sides, the apertures at the top and bottom of the screen are displaced outwards by different distances C, E, the difference depending upon the distance between the line joining members 7 and the mid-line M of the electrode. This effect may be compensated by arranging the two members 7 to lie at an angle to a plane which is parallel to both the tube axis and the longer sides of the electrode (Fig. 2, not shown). The flange 5 of the electrode support ring 4 may be blackened on its surface remote from the screen, to enhance its effect as a cooling fin.