GB1454921A - Method for making a stripe screen on a face plate of a cathode ray tube equipped with an in-line electron gun - Google Patents

Abstract

1454921 Colour television tube TOKYO SHIBAUBA ELECTRIC CO Ltd 7 June 1974 [13 June 1973] 25443/74 Heading H1D To form accurately the dark lines between red-green-blue phosphor stripes on the screen, in operation bombarded by electrons from inline guns (Fig. 1, not shown) through slotted shadow mask 7, photoresist coated faceplate 2 is exposed through shadow-mask 7 and correction lens 28 to linear light source 21 parallel to the mask-slots and positioned to correspond to the deflection centre of the electrons from each gun in turn, the lens being rotated through 90 degrees between exposures for central and side beams. With filter 29 controlling intensity distribution, lens 28 corrects for electron radial aberrations in all beams and applies required lateral corrections to outer beams, varying in different zones: for the central gun the shift axis is set parallel to the stripes and light source (Fig. 4B, not shown); for the outer guns the lens is rotated 90 degrees in the appropriate direction, the off-set centre of the source being rotated about the central gun axis with the lens while the source is relatively counterrotated to maintain fixed direction and is moved longitudinally to eliminate asymmetry of exposure. The resist of dichromated PVA is developed and the unexposed areas washed off; the entire screen is graphite coated and the remaining PVA with graphite is removed by H 2 O 2 , leaving graphite lines (Figs. 3A-3H, not shown). By three similar but less critical stages preferably in another exposure unit, three sets of phosphor stripes are laid down, slight overlap over the graphite being permissible.