GB1150927A - Improvements in or relating to Methods Of Manufacturing A Picture Screen For A Cathode Ray Tube For Reproducing Colour Pictures - Google Patents

Abstract

1,150,927. Luminescent screens. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 29 Sept., 1966 [2 Oct., 1965], No. 43608/66. Heading H1D. In a method of manufacturing the screen of a colour cathode-ray tube in which the phosphor strips, the intermediate, non-luminescent, opaque strips which separate each phosphor strip, and the indexing strips are provided using a photosensitive binder, the mask which is used to provide the intermediate strips is also used, when partly covered with an additional mask, to provide the phosphor strips and the indexing strips. Preferably also, the hardening radiation after passing through this mask passes through a plane parallel glass plate interposed in a fixed though rotatable manner between the mask and the screen. The mask 2, which comprises a glass plate 5 on which opaque strips 11, 13, 15 &c. have been deposited, the lens system 3, which projects a magnified image of the mask on to the photosensitive layer on screen 1, and the glass plate 4 are fixed with respect to each other and are arranged such that they may be replaced in exactly the same relationship to the screen after each step in the process. The intermediate strips 41-50, e.g. of iron oxide, are first deposited by hardening through mask 2, with the plate 4 parallel to mask 2, selected areas of a photosensitive layer, e.g. polyvinyl alcohol with ammonium dichromate sensitizer, washing away unexposed areas and then depositing the iron oxide from suspension on to the hardened strips. Strips 65-68 of a first phosphor, e.g. the green phosphor, are then deposited by exposing a photosensitive layer containing the phosphor through mask 2 which has two out of each successive three apertures covered by an additional mask 6 and with the glass plate 4 at an angle to the mask 2, as shown in Fig. 2, so that the areas of the photosensitive layer which are hardened lie between the intermediate strips. The remaining sets of phosphor strips, e.g. 75-77 and 101-104 of blue and red, are deposited similarly either by using a different additional mask or by translating the mask 6 with respect to fixed mask 2 so that different apertures in mask 2 are covered. Finally the indexing strips 111-115 are applied in correspondence with alternate intermediate strips over an aluminium layer 105, which covers the intermediate and phosphor strips, by using an additional mask 8 which covers alternate apertures in mask 2 and with the glass plate 4 once again parallel to mask 2 as shown in Fig. 4. The indexing strips may be secondary electron emissive or may emit radiation upon electron excitation. The screen is subsequently heated to bake out the volatile organic compounds.