Thorium-free discharge lamp with reduced halides and increased relative amount of Sc

• US 8,436,539 B2
• Filed: 09/19/2008
• Issued: 05/07/2013
• Est. Priority Date: 09/24/2007
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Haacke, Michael, Lesch, Norbert
• Primary Examiner(s): Roy, Sikha
• Application Number:
  US12/678,532
• Publication Number:
  US 20100213807A1
• Time in Patent Office: 1,691 Days
• Field of Search: 313/633, 313/637, 313/638
• US Class Current: 313/638
• CPC Class Codes: H01J 61/125 having an halogenide as principal component
• CPC Class Codes: H01J 61/827 Metal halide arc lamps

Abstract

A high-pressure gas discharge lamp has a sealed discharge vessel with an inner discharge space. Two electrodes project into the discharge space. The filling in the discharge space includes metal halides and a rare gas. The filling is free of Hg and Th and includes halides in an amount of 7.1-11.4 μg/mm³ of the volume of the discharge space. The halides includes at least NaI and ScI₃, provided in such amounts that a ratio of the masses of NaI to ScI₃ is 1.2-1.6.

Claims

1. A discharge lamp comprising:

a sealed discharge vessel defining a discharge space having a volume and comprising a filling including metal halides and a rare gas and being free of Hg and Th;

at least two electrodes projecting into said discharge space, said electrodes being free of Th,

wherein said metal halides are provided in an amount of 7.1-11.4 μ

g/mm³ of the volume of said discharge space and comprise NaI and ScI₃ in such amounts that a ratio of masses of NaI to ScI₃ is 1.2-1.6.

2. The discharge lamp of claim 1, wherein said metal halides further comprise at least InI.

3. The discharge lamp of claim 1, where wherein said metal halides consist essentially of NaI, ScI₃, ZnI₂ and InI.

4. The discharge lamp of claim 1, wherein said metal halides are provided in an amount of 8.5-10.5 μ

g/mm³ of the volume of said discharge space.

5. The discharge lamp of claim 1, wherein the volume of said discharge space is 10-45 mm³.

6. The discharge lamp of claim 1, wherein the volume is 19-25 mm³.

7. The discharge lamp of claim 1, wherein the ratio of the masses of Nal to ScI₃ is 1.3-1.4.

8. The discharge lamp of claim 1, further comprising an outer envelope disposed around said discharge vessel, wherein said outer envelope is sealed and filled with a gas.

9. The discharge lamp of claim 8, wherein said outer envelope is filled with a gas having a thermal conductivity of 60-90 mW/m*K at 800°

C.

10. The lamp of claim 1, wherein said rare gas is xenon provided at a cold pressure of 11-17 bar.

11. The lamp of claim 1, wherein said electrodes are made of tungsten.

12. The lamp of claim 1, wherein said electrodes are rod-shaped with a rod diameter of 280-320 μ

m.

13. The lamp of claim 1, wherein said metal halides further comprise at least ZnI₂, and wherein an amount of the ZnI₂ is 4-6 wt-% of said metal halide.