Photosensitive luminous substance suspensions based on polyvinyl alcohol, ammonium dichromate and luminophores as well as processes for their preparation

摘要

1,197,772. Luminescent materials. MATSUSHITA ELECTRONICS CORP. 23 Oct., 1967 [1 Nov., 1966; 11 April, 1967], No. 48010/67. Heading C4S. [Also in Division G2] A photo-sensitive slurry comprises polyvinyl alcohol, 1 to 30% by wt. of ammonium dicliromate phosphor particles and a quantity of Ge dioxide, tetra-chloride, disulphide or an orthogermanate ester, which gives 0À001 to 1À25 gm. of GeO 2 per 100 c.c. of P.V.A. solution. The Ge compound maintains photosensitivity by preventing an increase of the pH value and also prevents a reduction in phosphor emission due to adsorption of chromium on to the phosphor. Components of the slurry are blended together or the dichromate may be added during blending. The GeO 2 may be added as metagermanic acid, ethoxy germanium or ethanol containing GeCl 4 . Phosphors referred to are Eu actuated Y, Gd and Y-Gd oxides, Y and Gd oxysulphides and YVO 4 also ZnS and ZnCdS. A dot pattern on a colour T.V. tube is formed by applying the slurry and exposing to U.V. light through a shadow mask.