Mercury-free-high-pressure gas discharge Lamp

• US 20050116608A1
• Filed: 01/30/2003
• Published: 06/02/2005
• Est. Priority Date: 02/06/2002
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Haacke, Michael, Janssen, Marc F. R.
• Granted Patent: US 8,269,406 B2
• Time in Patent Office: Days
• US Class Current: 313/489
• CPC Class Codes: H01J 61/35 provided with coatings on the walls thereof; Selection of materials for the coatings using coloured coatings H01J61/40; using luminescent coatings H01J61/42
• CPC Class Codes: H01J 61/827 Metal halide arc lamps

Abstract

A mercury-free high-pressure gas discharge lamp (HID [high intensity discharge] lamp) is described which is provided for use in automotive technology. To achieve improved lamp characteristics, in particular a substantially equal luminous efficacy in comparison with lamps of the same power and a mercury-free gas filling, as well as a highest possible burning voltage, the discharge vessel (1) is provided in its wall regions (10) which are lowermost in the operational position with a coating (15) which reflects at least a portion of the infrared radiation generated during operation, such that the temperature of the coldest spots, and in particular of the light-generating substances collected there, is raised, with the result that the light-generating substances can enter the gas phase in sufficient quantities also without mercury, and in particular with the use of a metal halide as a voltage-gradient generator.

Claims

1. A mercury-free high-pressure gas discharge lamp having a discharge vessel (1) which comprises an at least substantially infrared-reflecting coating (15) on its wall portions (10) which are lowermost in the operational position, the dimensioning of said coating (15) being chosen such that after switching-on of the lamp the temperature of the light-generating substances collected on the coated wall portions is increased to the extent that said substances enter the gaseous state at least substantially.

2. A high-pressure gas discharge lamp as claimed in claim 1, wherein the dimensioning of the coating is given by its surface area and/or thickness and/or particle size and/or packing density of the particles.

3. A high-pressure gas discharge lamp as claimed in claim 1, wherein the coating (15) is at least substantially impermeable to visible light.

4. A high-pressure gas discharge lamp as claimed in claim 1, wherein the coating (15) is provided on the outer surfaces of the discharge vessel (1) or on the inner or outer surfaces of an outer bulb surrounding the discharge vessel.

5. A high-pressure gas discharge lamp as claimed in claim 1, wherein the coating (15) is provided on regions of pinches (5), i.e. on those regions thereof which adjoin the discharge vessel (1).

6. A high-pressure gas discharge lamp as claimed in claim 1, wherein the coating (15) is formed from zirconium oxide.

7. A high-pressure gas discharge lamp as claimed in claim 1, which comprises in its gas filling a voltage-gradient generator in the form of one or several metal halides.

8. A high-pressure gas discharge lamp as claimed in claim 7, wherein the voltage-gradient generator comprises zinc iodide.

9. A high-pressure gas discharge lamp as claimed in claim 1, wherein the gas filling comprises additional quantities of rare gases such as xenon so as to increase the gas pressure and to enhance the luminous efficacy of the lamp.

10. A lighting unit, in particular for motor vehicle headlights, comprising a high-pressure gas discharge lamp as claimed in claim 1.