GB1158487A - Coating Removal Device in the manufacture of Cathode Ray Tubes - Google Patents

Abstract

1,158,487. Luminescent screens. SYLVANIA ELECTRIC PRODUCTS, Inc. 22 Sept., 1966 [29 Sept., 1965 (2)], No. 42404/66. Heading H1D. In a process of applying an aluminium backing layer to the cathodo-luminescent screen 19 and surrounding sidewalls 15 of a cathode ray tube comprising applying first a layer of lacquer 21, removing the lacquer from the sidewall portion of the tube face plate, covering the entire inner surface of the face plate with an aluminium film and then baking to remove volatile constituents, the lacquer 21 is removed from the sidewall 15 by rotating horizontally a freshly lacquered face plate 11, with its inner surface facing downwards, relative to a stationary nozzle 23 which traverses the periphery of the sidewall at a constant distance to direct at a constant angle and pressure a jet of flushing liquid 27 on to the sidewall such that a constant terminal formation of liquid 39 results which completely flushes the lacquer layer from the sidewall before the lacquer has had time to form a film. The nozzle 23 is mounted in a panel tracking means 49 which is maintained a fixed distance from the sidewall by two tracking rollers 151, and the flushing liquid, which may be water, is supplied through the rod 107 which supports tracking means 49. The lacquer should not form a film too quickly-the mixture of xylene and toluene in which 4.6 to 5% by weight of acrylic resin solids and butyl phthalate plasticizer is dissolved is suitable As shown in Figs. 4 and 5, the face plate 11 is initially temporarily held on a number of panel rests 79 prior to being mounted without distortion by retainers 93 and pressure retainer 95 on an annular disc 51 which in turn is mounted on a base 61 by a number of vertical sets of rollers 55. Lateral movement of disc 51 is limited by horizontal rollers 63 and the disc 51 is rotated about vertical axis 104 by a chain 69 and drive mechanism 67. During the mounting of the face plate the tracking means 49, which are mounted on rods 107 and pivoted about post 109, are pushed towards the centre of the disc 51 by the plungers 113 of horizontal pressure means 111 against springs 117, which normally retain the rollers 151 of tracking means 49 against sidewall 15. A drainage well 161 is provided to dispose of the flushing effluence. During the tracking of the nozzle 23 round the sidewall 115 the jet of flushing liquid 27 is maintained at a constant angle to the sidewall and the head of the tracking means may swivel to have limited arcuate movement so that it can negotiate the corners of a rectangular tube face plate whilst maintaining constant spacing therefrom, Fig. 8 (not shown). The sequence of operations may be programmed and automatically controlled.