GB795908A - Improvements in or relating to methods of manufacturing colour cathode ray tubes - Google Patents

Abstract

795,908. Colour television tubes. ZENITH RADIO CORPORATION. June 22,1956 [June 24, 1955], No. 19382/56. Class 39(1). A method of manufacturing a cathode ray tube comprising a luminescent screen 15 composed of a plurality of sets of areas 14 which exhibit different colours under electron bombardment and an apertured mask member 10 in which the method comprises providing a sheet of conductive material suitable for use as the mask member with a layer 12 of resist material pierced by apertures 13 of a first predetermined size, etching away at least those parts of the sheet exposed by these apertures, employing the resist coated apertured mask thus formed to control, e.g., photographically, the production of the sets of areas 14 of the screen 15 and thereafter, if necessary enlarging the apertures 13 to a second predetermined size 23, removing the resist-layer and incorporating the mask in the tube. The sheet 10 may have resist layers on both faces. The apertures 13 of first predetermined size corresponds to the dimensions of the sets of areas 14 and the second size 23 is that finally necessary for the mask apertures. The etching may be stopped at the first size and restarted after the mask in its first stage has been used in the production of the screen or the etching may be allowed to proceed in the first operation to the final size 23 in which case the resist layers must be opaque to mask down the apertures 23 to the size of apertures 13 during the step of producing the screen. The screen may be non-planar and the resist-coated sheet deformed to a corresponding configuration before being used to control the production of the screen.