Metal halide lamp having ionizable iodide salt
View Patent ↗A metal halide lamp comprising a substantially cylindrical discharge vessel having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance EA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas, such as Xe, having a pressure at room temperature between 5 and 25 bar, and an ionizable salt, characterized in that said ionizable salt is selected from the group comprising PrI3, NdI3 and LuI3.
1. A metal halide lamp comprising a substantially cylindrical discharge vessel ( 3 ) having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance EA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas having a pressure at room temperature between 5 and 25 bar, and an ionizable salt, characterized in that said ionizable salt is selected from the group comprising PrI 3 , NdI 3 and LuI 3 .
2. A lamp according to claim 1 , wherein said ionizable salt further comprises NaI, and wherein the molar ratio NaI/(PrI 3 +NdI 3 +LuI 3 ) lies between 1.0 and 10.3.
3. A lamp according to claim 2 , wherein the molar ratio NaI/PrI 3 lies between 2.3 and 10.3.
4. A lamp according to claim 3 , wherein the molar ratio NaI/PrI 3 lies between, preferably between 3.0 and 5.7.
5. A lamp according to claim 4 , wherein the molar ratio NaI/PrI 3 is approximately 3.5.
6. A lamp according to claim 2 , wherein the molar ratio NaI/NdI 3 lies between 3.0 and 67.
7. A lamp according to claim 6 , wherein the molar ratio NaI/NdI 3 lies between 3.6 and 4.8.
8. A lamp according to claim 7 , wherein the molar ratio NaI/NdI 3 is approximately 4.2.
9. A lamp according to claim 2 , wherein the molar ratio NaI/LuI 3 lies between 1.0 and 3.2.
10. A lamp according to claim 9 , wherein the molar ratio NaI/LuI 3 lies between 1.2 and 1.8.
11. A lamp according to claim 10 , wherein the molar ratio NaI/LuI 3 is approximately 1.4.
12. A lamp according to claim 1 , wherein the amount of PrI 3 in the discharge vessel is between 10 and 335 μmol/cm 3 .
13. A lamp according to claim 12 , wherein the amount of PrI 3 in the discharge vessel is between 25 and 160 μmol/cm 3 .
14. A lamp according to claim 13 , wherein the amount of PrI 3 in the discharge vessel is approximately 50 μmol/cm 3 .
15. A lamp according to claim 1 , wherein the amount of NdI 3 in the discharge vessel is between 8 and 301 μmol/cm 3 .
16. A lamp according to claim 15 , wherein the amount of NdI 3 in the discharge vessel is between 30 and 167 μmol/cm 3 .
17. A lamp according to claim 16 , wherein the amount of NdI 3 in the discharge vessel is approximately 45 μmol/cm 3 .
18. A lamp according to claim 1 , wherein the amount of LuI 3 in the discharge vessel is between 15 and 414 μmol/cm 3 .
19. A lamp according to claim 18 , wherein the amount of LuI 3 in the discharge vessel is between 27 and 230 μmol/cm 3 .
20. A lamp according to claim 19 , wherein the amount of LuI 3 in the discharge vessel is approximately 69 μmol/cm 3 .
21. A lamp according to claim 1 , wherein Di<1.5 mm.
22. A lamp according to claim 1 , wherein EA lies between 3 mm and 7 mm.
23. A lamp according to claim 1 , wherein the discharge vessel has a ceramic wall.
24. A lamp according to claim 1 , wherein the discharge vessel is surrounded by a gas-filled outer bulb.
25. A lamp according to claim 1 , wherein the lamp power lies between 20 W and 40 W.
26. A metal halide lamp comprising a substantially cylindrical discharge vessel ( 3 ) having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance EA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas having a pressure at room temperature between 5 and 25 bar, and an ionizable salt selected from the group comprising PrI 3 , NdI 3 and LuI 3 , wherein the amount of NdI 3 in the discharge vessel is between 8 and 301 μmol/cm 3 .
27. A lamp according to claim 26 , wherein the amount of NdI 3 in the discharge vessel is between 30 and 167 μmol/cm 3 .
28. A lamp according to claim 27 , wherein the amount of NdI 3 in the discharge vessel is approximately 45 μmol/cm 3 .
29. A metal halide lamp comprising a substantially cylindrical discharge vessel ( 3 ) having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance LA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas having a pressure at room temperature between 5 and 25 bar, and an ionizable salt selected from the group comprising PrI 3 , NdI 3 and LuI 3 , wherein said ionizable salt further comprises NaI, and wherein the molar ratio NaI/(PrI 3 +NdI 3 +LuI 3 ) lies between 1.0 and 3.2.
30. A lamp according to claim 29 , wherein the molar ratio NaI/(PrI 3 +NdI 3 +LuI 3 ) lies between 1.2 and 1.8.
31. A lamp according to claim 30 , wherein the molar ratio NaI/(PrI 3 +NdI 3 +LuI 3 ) is approximately 1.4.
32. A metal halide lamp comprising a substantially cylindrical discharge vessel ( 3 ) having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance EA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas having a pressure at room temperature between 5 and 25 bar, and an ionizable salt selected from the group comprising PrI 3 , NdI 3 and LuI 3 , wherein the amount of LuI 3 in the discharge vessel is between 15 and 414 μmol/cm 3 .
33. A lamp according to claim 32 , wherein the amount of LuI 3 in the discharge vessel is between 27 and 230 μmol/cm 3 .
34. A lamp according to claim 33 , wherein the amount of LuI 3 in the discharge vessel is approximately 69 μmol/cm 3 .