# US 5,346,721 A · Method for coating CRT face panels > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,346,721 A - Document ID: US5346721A - Status: Granted - Kind: A - Application number: 07/882,205 - Filed: 1992-05-13 - Granted: 1994-09-13 - Earliest claimed: 1989-12-28 - Assignees: Zenith Electronics Corporation - Inventors: Hua-Sou Tong; Gregory Prando - Web page: https://patentgrep.com/patent/US5346721A ## CPC - C03C 17/009: {Mixtures of organic and inorganic materials, e.g. ormosils and ormocers} - H01J 9/20: Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel - H01J 29/896: {Anti-reflection means, e.g. eliminating glare due to ambient light} - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract The present invention is directed to a cathode ray tube having a surface with reduced reflectivity and electrical resistivity and to a method for providing such reduced reflectivity and electrical resistivity. In the method of the invention, a solution of a soluble metallic cation moiety and a silane in an organic solvent is provided. The solution is applied to the surface of a cathode ray tube to provide a coating of the silane and the metallic moiety of the metallic compound on the surface. Thereafter, the cathode ray tube is cured at an elevated temperature for a period of time sufficient to convert the metallic cation moiety to a metal oxide in situ and to provide a metallic oxide in a matrix of siloxane. ## Claims ### Claim 1 A method for reducing both the reflectivity and the electrical resistivity of the surface of a cathode ray tube comprising: (a) providing an ionic solution consisting essentially of a dissociated metallic compound having a metallic cation moiety selected from the group consisting of tin, palladium, platinum, silver and antimony and a silane in an organic solvent, (b) applying said solution on the surface of a cathode ray tube to provide a coating of said silane and said metallic cation moiety on said surface, and (c) curing said cathode ray tube at an elevated temperature of from about 120.degree. C. to about 200.degree. C. for a period of from about 0.1 hour to about 2 hours to convert said metallic cation moiety to a metal oxide in situ and to provide a transparent coating of an oxide of said metallic moiety dispersed in a matrix of siloxane on the surface of said cathode ray tube. ### Claim 2 (depends on 1) A method in accordance with claim 1 wherein said metallic compound is selected from the group consisting of organometallic compounds and metal salts. ### Claim 3 (depends on 1) A method in accordance with claim 1 wherein said surface of said cathode ray tube is preheated prior to application of said solution. ### Claim 4 (depends on 3) A method in accordance with claim 3 wherein said cathode ray tube is preheated to a temperature in the range of from about 70.degree. C. to about 120.degree. C. prior to applying said solution. ### Claim 5 (depends on 1) A method in accordance with claim 1 wherein said curing of said cathode ray tube is at an elevated temperature of from about 120.degree. C. to about 200.degree. C. for a period of from about 0.1 hour to about 2 hours. ### Claim 6 (depends on 1) A method in accordance with claim 1 wherein said metallic oxide in said coating is present at a level of from about 0.3 to about 1.2 milligrams per square centimeter of said surface area of said cathode ray tube. ### Claim 7 (depends on 1) A method in accordance with claim 1 wherein said solution is applied by spraying a fine mist of said solution onto said surface. ### Claim 8 (depends on 1) A method in accordance with claim 1 wherein said solution is applied to said surface of said cathode ray tube by multiple spray passes. ### Claim 9 (depends on 8) A method in accordance with claim 8 wherein from 3 to 12 spray passes are used to apply said solution. ### Claim 10 (depends on 2) A method in accordance with claim 2 wherein said metallic compound is a metal salt. ### Claim 11 (depends on 10) A method in accordance with claim 10 wherein said metal salt is a halogen salt of a metal selected from the group consisting of tin, palladium, platinum, silver and antimony. ### Claim 12 (depends on 11) A method in accordance with claim 11 wherein said metal is tin. ### Claim 13 (depends on 11) A method in accordance with claim 11 wherein said metal salt is tin chloride. ### Claim 14 (depends on 2) A method in accordance with claim 2 wherein said metal compound is an organometallic. ### Claim 15 (depends on 14) A method in accordance with claim 14 wherein the metal moiety of said organometallic is selected from the group consisting of tin, palladium, platinum, silver and antimony. ### Claim 16 (depends on 1) A method in accordance with claim 1 wherein said metal compound is present in said solution at a level sufficient to provide from about 0.2 percent to about 0.6 percent of the metal moiety of said metal compound in said solution. ### Claim 17 (depends on 1) A method in accordance with claim 1 wherein said silane is selected from the group consisting of tetraalkyl silanes, tetraaryl silanes and halogenated silanes. ### Claim 18 (depends on 16) A method in accordance with claim 16 wherein said silane is selected from the group consisting of tetrachlorosilane, trichlorosilane, tetramethoxy silane and tetraethoxy silane. ### Claim 19 (depends on 1) A method in accordance with claim 1 wherein said silane is present in said solution at a level of from about 0.5% to about 20% by weight.