# US 5,708,328 A · Universal burn metal halide lamp > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,328 A - Document ID: US5708328A - Status: Granted - Kind: A - Application number: 07/892,857 - Filed: 1992-06-03 - Granted: 1998-01-13 - Earliest claimed: 1992-06-03 - Assignees: General Electric Company - Inventors: Paul G. Mathews; Brian L. Gordon; David E. Korow; Martin N. Hassink - Web page: https://patentgrep.com/patent/US5708328A ## CPC - H01J 61/30: Vessels; Containers - H01J 61/825: {High-pressure sodium lamps} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A metal halide arc discharge lamp rated for not more than 150 watts and 100 volts and which can be operated in either a horizontal or vertical position without a significant change in color temperature or lumen output has an ellipsoidal arc chamber mounted within a nitrogen-containing outer envelope. The arc chamber contains a pair of electrodes, mercury and sodium and scandium iodides and is coated at each end with a heat reflective coating. The chamber aspect ratio, electrode insertion length, metal halide density, coating length and wall loading are defined within narrow ranges. ## Claims ### Claim 1 A vitreous, light transmissive arc chamber for a universal burn metal halide arc discharge lamp rated for a power input of not more than 150 watts and having a wall loading of 17-23 watts/cm.sup.2 during operation, said arc chamber having an ellipsoidal shape including a volume no greater than 1 cm.sup.3 with an aspect ratio ranging between 1.6-2.3, said chamber being coated at both ends with a heat reflective coating whose length at each end is from 12-16% of said chamber length, said chamber enclosing within a pair of spaced apart electrodes each extending into said chamber a distance no greater than 15% of said chamber length, said chamber further containing (i) inert starting gas, (ii) a metal halide comprising a halide of sodium and at least one additional metal in an amount sufficient to achieve a metal halide density of from 1.5 to 4 mg/cc, and (iii) mercury in an amount sufficient to achieve desired operating voltage of no more than 100 volts, and wherein said arc discharge lamp exhibits a difference in lumen output between vertical and horizontal orientation which is less than 10% in variance to one another. ### Claim 2 (depends on 1) The arc chamber of claim 1 wherein said volume is no greater than 3/4 cm.sup.3. ### Claim 3 (depends on 2) The arc chamber of claim 2 wherein said aspect ratio is between 1.8-2.1. ### Claim 4 (depends on 3) The arc chamber of claim 3 wherein said metal halide density is from 2-31/3 mg/cc. ### Claim 5 (depends on 4) The arc chamber of claim 4 wherein said volume is no greater than 1/2 cm.sup.3. ### Claim 6 (depends on 5) The arc chamber of claim 5 containing a scandium halide. ### Claim 7 (depends on 6) The arc chamber of claim 6 wherein said halide comprises iodide. ### Claim 8 A universal burn metal halide arc discharge lamp rated for power input of no more than 150 watts, comprising a vitreous, light transmissive outer envelope with an inert gas present in the space between said arc chamber and the interior surface of said envelope, said chamber having a wall loading of 17-23 watts/cm.sup.2 during operation and having an ellipsoidal shape including a volume no greater than 1 cm.sup.3 with an aspect ratio ranging between 1.6-2.3, said chamber being coated at both ends with a heat reflective coating having a coating length of from 12-16% of the arc chamber length, and enclosing within a pair of spaced apart electrodes each extending into said chamber a distance no greater than 15% of said chamber length, said chamber further containing (i) inert starting gas, (ii) metal halide comprising a halide of sodium and at least one additional metal in an amount sufficient to achieve metal halide density of from 1.5 to 4 mg/cc, and (iii) mercury in an amount sufficient to achieve desired operating voltage of no more than 100 volts during operation of said lamp, and wherein said arc discharge lamp exhibits a difference in lumen output between vertical and horizontal orientation which is less than 10% in variance to one another. ### Claim 9 (depends on 8) The lamp of claim 8 wherein said gas present within said space between said arc chamber and outer envelope comprises nitrogen. ### Claim 10 (depends on 9) The lamp of claim 9 wherein said arc chamber volume is no greater than 3/4 cm.sup.3. ### Claim 11 (depends on 10) The arc chamber of claim 10 wherein said aspect ratio is between 1.8-2.1. ### Claim 12 (depends on 11) The lamp of claim 11 wherein said metal halide density is from 2-31/3 mg/cc. ### Claim 13 (depends on 12) The lamp of claim 12 wherein said arc chamber volume is no greater than 1/2 cm.sup.3. ### Claim 14 (depends on 13) The lamp of claim 13 wherein said arc chamber also contains a scandium halide. ### Claim 15 (depends on 14) The lamp of claim 14 wherein said halide comprises iodide.