GB732236A - Improvements in or relating to devices for reproducing colour-television images - Google Patents

Abstract

732,236. Colour television tubes. PHILIPS ELECTRICAL INDUSTRIES, Ltd. April 29, 1952 [May 2, 1951], No. 10760/52. Class 39 (1). [Also in Group XL (b)] In colour or stereoscopic television reproduction a cathode-ray tube includes a cathode, an accelerating anode, a final anode, a lightemitting screen and a deflecting grid of parallel wires in front of the final anode, having a positive potential lower than that of the image screen and being supplied with varying voltages which alter the deflection of the beam to yield different colour responses on the image screen. The final anode may be a conductive layer on one side of the luminescent or incandescent screen, its position determining the direction of viewing, or conductive particles may be mixed with the luminescent material. The direction of the scanning beam is at an angle to the lines of force between the grid and the final anode and the latter may be curved or at an angle to each other. Various arrangements are described as in Specification 732,235. In Fig. 6 the grid 28 directs the beam 42 onto strips of luminescent material 30-41, alternating red, green and blue under dot-line- or framesequential scanning, the stepped voltage applied to the grid 28 determining which colour is excited. In a modification, Fig. 11, a single luminescent layer 62 is backed by a colour filter, the grid 61 functioning as the field electrode. The filtering may be inside or outside the tube. In a further modification, the light from the luminescent screen is focused on a projection screen formed of painted strips of different colours.