GB1079969A - Improvements in or relating to fibre-type light transfer face plates and methods of making the same - Google Patents

Abstract

<PICT:1079969/C1/1> A cathode-ray tube faceplate, composed of a multiplicity of optical glass fibres hermetically sealed together in side-by-side relation, has a tapered, even, edge which is hermetically sealed to a corresponding tapered inner surface of an annular glass frame by means of which the faceplate may be sealed to the funnel portion of a cathode-ray tube envelope. The optical fibres may comprise cores of optical flint glass, each with a cladding of crown or soda lime or potash soda lead glass, elongated fibres being stacked under pressure and fused together in vacuo to form a sealed bundle which is sliced to form faceplates, the edges of which are tapered by grinding. The faceplate 21 is then assembled in the glass frame 15 of potash soda lead glass supported by a refractory block 24, a small space being left between faceplate 21 and block 24 to permit slight downward movement of the faceplate during sealing by fusion but preventing any tendency for the cores of the fibres to flow outwardly of their claddings. Alternatively, the opposite face of faceplate 21 may be supported by a refractory block, the frame being fitted thereover, Figs. 7 and 10 (not shown). Instead of fusing the frame directly to the fibre faceplate, a sealing of flux glass powder, e.g. Pyroceram cement, mixed with a binder may be applied to one or both of the mating surfaces. Either or both of the light receiving and emitting surfaces of the faceplate may be curved, and the faceplate may be composed of tapered fibres, Fig. 9 (not shown), to provide magnification or demagnification of light images.