Electrode for a Discharge Lamp and Corresponding Production Method

• US 20110163655A1
• Filed: 09/05/2008
• Published: 07/07/2011
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: OSRAM GmbH (Ams-Osram AG), Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Stange, Markus
• Granted Patent: US 8,502,439 B2
• Time in Patent Office: Days
• US Class Current: 313/311
• CPC Class Codes: H01J 61/0735 characterised by the material of the electrode

Abstract

An electrode for a discharge lamp, wherein the electrode comprises a pin and a mass arranged on an end of the pin by melting over an electrode coil. The pin consists of tungsten with microstructure-stabilizing additives, wherein the concentration of the microstructure-stabilizing additives is greater than or equal to 30 ppm. The electrode coil consists of pure tungsten, which has additives at most up to a concentration of 20 ppm.

Claims

1. An electrode for a discharge lamp, wherein the electrode comprises a pin and a mass arranged on an end of the pin by melting over an electrode coil, wherein the pin consists of tungsten with microstructure-stabilizing additives, wherein the concentration of the microstructure-stabilizing additives is greater than or equal to 30 ppm, and wherein the electrode coil consists of pure tungsten, which has additives at most up to a concentration of 20 ppm.

2. The electrode as claimed in claim 1, wherein the concentration of the microstructure-stabilizing additives in the pin is greater than or equal to 60 ppm.

3. The electrode as claimed in claim 1, wherein the concentration of the additives in the electrode coil is less than or equal to 5 ppm.

4. The electrode as claimed in claim 1, wherein the pin extends into the melt zone of the electrode coil.

5. The electrode as claimed in claim 1, wherein the pin does not extend into the melt zone of the electrode coil.

6. The electrode as claimed in claim 1, wherein the pin does not extend into a front region of the electrode coil facing away from the pin.

7. The electrode as claimed in claim 1, wherein the electrode coil comprises between 3 and 20 windings, wherein the pin at least does not extend into the front quarter facing away from the pin.

8. The electrode as claimed in claim 7, wherein the windings of the electrode coil are arranged at least in part in one layer.

9. The electrode coil as claimed in claim 7, wherein the windings of the electrode coil are arranged one above the other at least in part in at least two layers.

10. The electrode as claimed in claim 1, wherein the melting is designed such that a compact thermal mass is formed, wherein the portion of the pin in said compact thermal mass is less than or equal to 15%.

11. The electrode as claimed in claim 1, wherein the microstructure-stabilizing additives comprise potassium and/or thorium.

13. A discharge lamp with an electrode as claimed in claim 1.

14. The electrode as claimed in claim 1, wherein the concentration of the microstructure-stabilizing additives in the pin is greater than or equal to 80 ppm.

15. The electrode as claimed in claim 1 wherein the concentration of the additives in the electrode coil is less than or equal to 1 ppm.

16. The electrode as claimed in claim 1, wherein the electrode coil comprises between 3 and 20 windings, wherein the pin at least does not extend into the front third facing away from the pin of the windings.

17. The electrode as claimed in claim 1, wherein the melting is designed such that a compact thermal mass is formed, wherein the portion of the pin in said compact thermal mass is less than or equal to 1%.

12. A method for producing an electrode for a discharge lamp, comprising the steps of:

a) providing a pin made of tungsten with microstructure-stabilizing additives, wherein the concentration of the microstructure-stabilizing additives is greater than or equal to 30 ppm;

b) arranging an electrode coil at an end of the pin, wherein the electrode coil consists of pure tungsten, which has additives at most up to a concentration of 20 ppm; and

c) melting over the electrode coil such that a mass arranged at the end of the pin is formed.