Ceramic metal halide lamp with oxygen content selected for high lumen maintenance
A lamp includes a discharge vessel with electrodes extending into the discharge vessel and an ionizable fill scaled within the vessel. The fill includes a buffer gas, optionally mercury, and a halide component. The lamp includes available oxygen, sealed within the discharge vessel, at a concentration of at least 0.1 μmol O/cc.
1. A lamp comprising:
a discharge vessel;
electrodes extending into the discharge vessel;
an ionizable fill sealed within the vessel, the fill comprising:
a buffer gas, and
a halide component, the halide component including a rare earth halide selected from the group consisting of lanthanum halides, cerium halides, neodymium halides, praseodymium halides, samarium halides, and combinations thereof;
available oxygen, sealed within the vessel at a concentration of at least 0.1 micromoles of oxygen, expressed as singlet oxygen, per cubic centimeter of lamp volume (μmol O/cc).
2. The lamp of claim 1 , wherein the available oxygen is at a concentration of at least 0.14 μmol O/cc.
3. The lamp of claim 2 , wherein the available oxygen is at a concentration of at least 0.3 μmol O/cc.
4. The lamp of claim 1 , wherein the available oxygen is at a concentration of up to 1.5 μmol O/cc.
5. The lamp of claim 4 , wherein the available oxygen is at a concentration of up to 1.0 μmol O/cc.
6. The lamp of claim 1 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 98%.
7. The lamp of claim 6 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 99%.
8. The lamp of claim 1 , wherein the halide component includes at least one source of iodine.
9. The lamp of claim 1 , wherein the halide component comprises a sodium halide, a lanthanum halide, a thallium halide, and a calcium halide.
10. The lamp of claim 9 , wherein the lanthanum halide is present in the halide component at a mol. fraction of at least 0.009.
11. The lamp of claim 9 , wherein the lanthanum halide is present in the halide component at a mol. fraction of up to 0.3.
12. The lamp of claim 9 , wherein the sodium halide is present in the halide component at a mol fraction of at least 0.3.
13. The lamp of claim 9 , wherein the thallium halide is present in the halide component at a mol fraction of at least 0.01.
14. The lamp of claim 9 , wherein the calcium halide is present in the halide component at a mol fraction of at least 0.09.
15. The lamp of claim 9 , wherein the available oxygen is at a concentration of at least 0.14 μmol O/cc.
16. The lamp of claim 15 , wherein the available oxygen is at a concentration of at least 0.3 μmol O/cc.
17. The lamp of claim 15 , wherein the available oxygen is at a concentration of up to 1.5 μmol O/cc.
18. The lamp of claim 17 , wherein the available oxygen is at a concentration of up to 1.0 μmol O/cc.
19. The lamp of claim 15 , wherein the lanthanum halide is present in the halide component at a mol. fraction of at least 0.009.
20. The lamp of claim 15 , wherein the lanthanum halide is present in the halide component at a mol. fraction of up to 0.3.
21. The lamp of claim 15 , wherein the sodium halide is present in the halide component at a mol fraction of at least 0.3.
22. The lamp of claim 15 , wherein the thallium halide is present in the halide component at a mol fraction of at least 0.01.
23. The lamp of claim 15 , wherein the calcium halide is present in the halide component at a mol fraction of at least 0.09.
24. The lamp of claim 9 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 98%.
25. The lamp of claim 24 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 99%.
26. The lamp of claim 1 , wherein the halide component is free of all rare earth halides other than halides of lanthanum, cerium, neodymium, praseodymium, and samarium.
27. The lamp of claim 26 , wherein the fill is free of all rare earth halides other than halides of lanthanum.
28. The lamp of claim 27 , wherein the available oxygen is at a concentration of at least 0.14 μmol O/cc.
29. The lamp of claim 28 , wherein the available oxygen is at a concentration of at least 0.3 μmol O/cc.
30. The lamp of claim 27 , wherein the available oxygen is at a concentration of up to 1.5 μmol O/cc.
31. The lamp of claim 30 , wherein the available oxygen is at a concentration of up to 1.0 μmol O/cc.
32. The lamp of claim 27 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 98%.
33. The lamp of claim 27 , wherein the available oxygen is at a concentration that provides a lumen maintenance at 1000 hrs, expressed as a percentage of lumens at 100 hrs, of at least 99%.
34. The lamp of claim 27 , wherein the lanthanum halide is present in the halide component at a mol. fraction of at least 0.009.
35. The lamp of claim 27 , wherein the lanthanum halide is present in the halide component at a mol. fraction of up to 0.3.
36. The lamp of claim 1 , wherein the lamp further satisfies a lumen maintenance of at least 95% at 2000 hours.
37. The lamp of claim 1 , wherein the ionizable fill further includes mercury.
38. The lamp of claim 1 , wherein the available oxygen is provided by a source of available oxygen disposed in the discharge vessel.
39. The lamp of claim 38 , wherein the source of available oxygen comprises an oxide of tungsten.
40. The lamp of claim 1 , wherein a ratio of
[
total
halide
]
[
O
]
/
cc
of arc tube volume in the fill is from 900 to 6000.
41. The lamp of claim 40 , wherein the molar ratio of
[
total
halide
]
[
O
]
/
cc
of arc tube volume in the fill is from 1000 to 5700.
42. A method of operating a lamp comprising:
providing the lamp of claim 1 ;
operating the lamp by supplying an electric current to the lamp to generate a discharge in the lamp vessel, wherein in operation, the lamp operates at a 1000 hr % lumen maintenance of at least 98.
43. A lamp comprising:
a discharge vessel;
electrodes extending into the discharge vessel;
an ionizable fill sealed within the vessel, the fill comprising:
a buffer gas,
and
a halide component, the halide component consisting essentially of halides which, to the extent that they form oxides during lamp operation, the oxides formed are unstable oxides which provide available oxygen; and
available oxygen, sealed within the discharge vessel, at a concentration of 0.1-1.5 μmol O/cc.
44. A method of forming lamps with a high lumen maintenance comprising:
providing a set of ceramic metal halide lamps with a halide fill component and a source of available oxygen, whereby at least three lamps of the set differ in their respective available oxygen concentrations to provide lamps covering a range of different available oxygen concentrations within a range of from 0.1 μmol O/cc-1.5 μmol O/cc;
operating each of the lamps by supplying an electric current to the lamp to generate a discharge in the lamp vessel;
determining a lumen maintenance value for each of the lamps; and
computing an optimum oxygen concentration or concentration range based on the determined lumen maintenance values;
forming lamps with the computed oxygen concentration or within the computed concentration range.
45. The lamp of claim 43 , wherein the ionizable fill further comprises mercury.