# US 5,708,331 A · Electrodeless lamp with external insulative coating > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,331 A - Document ID: US5708331A - Status: Granted - Kind: A - Application number: 08/656,678 - Filed: 1996-05-31 - Granted: 1998-01-13 - Earliest claimed: 1996-05-31 - Assignees: General Electric Company - Inventors: Spiro Vamvakas; Timothy A. Taubert; Mahomed H. Girach; Curtis E. Scott; Vito J. Arsena - Web page: https://patentgrep.com/patent/US5708331A ## CPC - H01J 65/048: {the field being produced by using an excitation coil} - H01J 61/04: Electrodes (for igniting H01J61/54); Screens; Shields - H01J 61/35: provided with coatings on the walls thereof; Selection of materials for the coatings (using coloured coatings H01J61/40; using luminescent coatings H01J61/42) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract An electrodeless, low pressure gas discharge lamp includes a vitreous envelope containing a discharge medium and being shaped with an external chamber for receiving an electrical excitation circuit. The excitation circuit is effective for exciting the discharge medium to emit light with electromagnetic fields that are generated by the excitation circuit. A circuit is included for supplying electrical power from power mains to the excitation circuit. A transparent, electrically conductive coating is provided atop the vitreous envelope and is electrically connected substantially directly to one of the power mains at any given time. A transparent, electrically insulative coating is disposed atop the electrically conductive coating, and comprises a contiguous, inorganic glass layer. The insulative coating preferably has a minimum coating thickness of at least about 3.1 microns. ## Claims ### Claim 1 An electrodeless, low pressure gas discharge lamp, comprising: (a) a vitreous envelope containing a discharge medium, said envelope being shaped with an external chamber for receiving an electrical excitation circuit and having a surface facing outwardly formed of adjoining non-overlapping first and second sides; (b) said excitation circuit being effective for exciting said discharge medium to emit light with electromagnetic fields that are generated by said excitation circuit; (c) a circuit for sulpplying electrical power from power mains to said excitation circuit; (d) a housin for said circuit; (e) an electrically insulative skirt depending from said housing and aproximately encircling said first side of said envelop; (f) a transparent, electrically conductive coating atop said vitreous envelope that is ohmically connected to said circuit, and, through said circuit, is electrically connected substantially directly to one of said power mains at any given time; and (g) a transparent, electrically insulative coating comprising a contigous, inorganic glass layer; said insulative coating being disposed atop said electrically conductive coating, extending fully over said second side of said envelope, and further extending over said first side, beneath said skirt, for a redetermined distance. ### Claim 2 (depends on 1) The gas discharge lamp of claim 1, wherein said vitreous envelope comprises soda-lime-silicate glass. ### Claim 3 (depends on 2) The gas discharge lamp of claim 2, wherein said insulative coating comprises lead-borosilicate glass. ### Claim 4 (depends on 1) The gas discharge lamp of claim 1, wherein said vitreous envelope comprises borosilicate glass. ### Claim 5 (depends on 4) The gas discharge lamp of claim 4, wherein said insulative coating comprises boron. ### Claim 6 An electrodeless, low pressure gas discharge lamp, comprising: (a) a vitreous envelope containing a discharge medium, said envelope being shaped with an external chamber for receiving an electrical excitation circuit and having a surface facing outwardly formed of adjoining, non-overlapping first and second sides; (b) said excitation circuit being effective for exciting said discharge medium to emit light with electromagnetic fields that are generated by said excitation circuit; (c) a circuit for supplying electrical power from power mains to said excitation circuit; (d) a housing for said circuit; (e) an electrically insulative skirt depending from said housing and aproximately encircling said first side of said envelope; (f) a transparent, electrically conductive coating atop said vitreous envelope that is ohmically connected to said circuit, and, through said circuit, is electrically connected substantially directly to one of said power mains at any given time; (g) a transparent, electrically insulative coating comprising a contigous, inorganic glass layer; said insulative coating being disposed atop said electrically conductive coating, extending fully over said second side of said envelope, and further extending over said first side, beneath said skirt, for a redetermined distance; and (h) said insulative coating having a minimum coating thickness of at least about 3.1 microns. ### Claim 7 (depends on 6) The gas discharge lamp of claim 6, wherein said insulative coating has a minimum coating thickness of at least about 4.6 microns. ### Claim 8 (depends on 6) The gas discharge lamp of claim 6, wherein said insulative coating has a minimum coating thickness of at least about 8.3 microns. ### Claim 9 (depends on 6) The gas discharge lamp of claim 6, wherein said insulative coating has a minimum coating thickness of at least about 12.4 microns. ### Claim 10 (depends on 6) The gas discharge lamp of claim 6, wherein said vitreous envelope comprises soda-lime-silicate glass. ### Claim 11 (depends on 10) The gas discharge lamp of claim 10, wherein said insulative coating comprises lead-borosilicate glass. ### Claim 12 (depends on 11) The gas discharge lamp of claim 11, wherein said insulative coating has a minimum coating thickness of at least about 4.6 microns. ### Claim 13 (depends on 6) The gas discharge lamp of claim 6, wherein said vitreous envelope comprises borosilicate glass. ### Claim 14 (depends on 13) The gas discharge lamp of claim 13, wherein said insulative coating comprises boron. ### Claim 15 (depends on 6) The gas discharge lamp of claim 6, wherein said insulative coating comprises zinc borosilicate.