METHOD OF FORMING A PATTERNED PORTION ON A PHOSPHOR SCREEN OF A CATHODE-RAY TUBE FOR COLOUR TELEVISION SETS

摘要

1319647 Vapour deposition NIPPON VICTOR K K 28 July 1970 [31 July 1969] 36492/70 Heading C7F [Also in Division H1] A layer of material of low reflectivity is deposited on the screen of a colour television tube by placing a layer 25 Fig.7 of boron carbide in powder form and a layer 26 of chromium in solid form in a crucible 23 which is surrounded by a filament 24 adapted to emit electrons which bombard the materials to evaporate them. The crucible and the screen are placed in an evacuated bell jar Fig.6 (not shown) and are separated by a grid (28) adapted to collect stray electrons or charged particles and by a shutter (27) which prevents deposition during an initial pre-heating period. The chromium evaporates first to form a layer which may be 1000ASP‹/SP thick and is followed by a 500A‹ layer of mixed composition and then a 2000A‹ layer of boron carbide, Fig.11 (not shown).