Method of manufacturing fluorescent screens of cathode ray tubes

Abstract

A fluorescent screen of a cathode ray tube is prepared by forming a film of photosensitive sticky substance, for example, an aqueous solution of a copolymer of a complex salt of diazonium salt and zinc chloride, oN an inner surface of a face plate of the tube, exposing the film to light to render portions thereof sticky, applying a powdery substance, for example, .[.phosphors of three colors.]. .Iadd.graphite.Iaddend., onto the film to cause the powdery substance to adhere to the portions of the film rendered sticky, removing excess powder to form a film pattern of the powdery substance, causing the substance responsible for stickiness to ooze out onto the film pattern, applying another powdery substance, for example, .[.graphite.]. .Iadd.titanium oxide .Iaddend.onto the film pattern and removing an excess of another powder substance, thus forming the fluorescent screen. The invention is applicable to the manufacture of a fluorescent screen for use in a color picture tube, a monochromatic picture tube and a penetration tube.

What is claimed is: 
     
       1. A method of manufacturing a fluorescent screen of a cathode ray tube comprising the steps of: forming a film of photosensitive .[.sticky.]. substance that exhibits stickiness when exposed to light on an inner surface of a face plate of said tube;   exposing said film to light to render portions thereof sticky;   applying a powdery substance onto said film to cause said powdery substance to adhere to said portions of the film rendered sticky;   removing excess powder to form a film pattern of said powdery substance;   causing the substance responsible for stickiness to ooze out onto said film pattern;   applying another powdery substance onto said film pattern; and   removing an excess of said another powdery substance, thus forming said fluorescent screen.   
     
     
       2. The method according to claim 1 wherein said photosensitive .[.sticky.]. substance comprises a compolymer of a complex salt of diazonium salt and zinc chloride. 
     
     
       3. The method according to claim 1 wherein said film of photosensitive .[.sticky.]. substance has a thickness of about 0.5 to 0.8 microns. 
     
     
       4. The method according to claim 1 wherein said powdery substance comprises .[.powders.]. .Iadd.a powder .Iaddend.of phosphors of .Iadd.one of .Iaddend.three colors of green, blue and red. 
     
     
       5. The method according to claim .[.1.]. .Iadd.4 .Iaddend.wherein said another powdery substance comprises a powder of .[.graphite.]. .Iadd.silica.Iaddend.. 
     
     
       6. The method according to claim 5 which further comprises the step of applying a powder of .[.white substance onto a film of graphite to form a reflection layer.]. .Iadd.a phosphor of a second of said three colors.Iaddend.. 
     
     
       7. The method according to claim .[.1.]. .Iadd.6 .Iaddend.wherein .[.said.]. .Iadd.a second .Iaddend.another powdery substance .[.comprises.]. .Iadd.comprising .Iaddend.a powder of silica .Iadd.is applied to said phosphor of said second color.Iaddend.. .Iadd. 
     
     
       8.  A method according to claim 1 wherein said powdery substance comprises a powder of graphite and said another powdery substance comprises a powder of titanium oxide. .Iaddend. .Iadd. 
     
     
       9.  The method according to claim 1 wherein said powdery substance is a powder of a phosphor and said another powdery substance comprises an isobutyl methacrylate resin. .Iaddend.