High-pressure discharge lamp

To reduce the quantity of a noble gas, typically xenon, and improve the sk and vibration resistance of the quartz glass bulb upon possible movement of electrode support shafts (4, 4') in transport or handling, a support element (6, 6') is engaged against a constriction between the bulb portion (1) and the neck portions (2, 2') of the discharge vessel structure. A spiral spring (8), preferably of tungsten, is engaged against one or more ceramic, perferably aluminum oxide disks, backed up against a melt seal, and pressing the respective disk or disks against the support element. The ceramic disks are loosely seated on the electrode shaft and located within the neck portions with clearance, so that, upon operation of the lamp, and expansion due to heating of the ceramic disks, the stability of the arc is improved and ignition is facilitated due to the lower fill pressure of the noble gas. The disks support the electrode shaft, decrease stress on the support element (6, 6') and permit better heat radiation to the necks, which can still be improved by coating the neck portions with a radiation emitting coating (11').

I claim:

1. A high pressure discharge lamp having a discharge vessel structure including

a quartz glass bulb (1) defining a lamp axis;

two neck portions (2, 2') extending from said bulb in alignment with said axis, and forming a transition region including a constriction in the region of a junction between the bulb and the respective neck;

two electrodes (3, 3') located within said bulb;

two electrode support shafts (4, 4'), one each supporting an electrode, and extending outwardly of the respective necks;

a melt seal (7) for each of said shafts, gas-tightly sealing the respective electrode shaft (4, 4') to a respective neck portion (2, 2'),

said melt seals being located on the respective neck portion at the position remote from the bulb;

a support element (6, 6') loosely surrounding each of said shafts, located in said transition region between the bulb (1) and the respective portion (2, 2 ') and engaging the wall of the discharge vessel structure in the region of the constriction;

a fill, including at least a noble gas, within said discharge vessel structure,

spring means (8) loosely surrounding the respective electrode shafts (4, 4') positioned adjacent to, and supported on the respective melt seals (7); and comprising

a plurality of spacing disks (9, 9'), each disk defining a top and a bottom surface, said plurality of spacing disks forming a stack of disks loosely surrounding the respective electrode shafts, with radial clearance, and stacked on said electrode shafts and, at a temperature when the lamp is extinguished, having radial clearance from the interior wall of the respective neck portion,

said plurality of spacing disks being positioned between the support element (6, 6') and the spring means (8), said spring means engaging an adjacent surface of one of the said disks and resiliently pressing facing surfaces of said disks in said stack of elements together.

2. The lamp of claim 1, wherein said plurality of spacing disks (9, 9') in the respective neck portion (2, 2') comprise ceramic material.

3. The lamp of claim 1, wherein said plurality of disks (9, 9') in each neck portion (2, 2') comprises aluminum oxide ceramic material.

4. The lamp of claim 1, wherein said plurality of disks (9, 9') in the respective neck portion (2, 2') has a thickness of between 1 to 5 mm, and a diameter which is less than the inner diameter of the neck portion (2, 2') by between 0.2 to 0.8 mm.

5. The lamp of claim 1, wherein said plurality of spacing disks (9, 9') are located within each neck portion;

wherein each of said plurality of disks (9, 9') comprises ceramic material having a thickness of between 1 to 5 mm, and a diameter which is less than the inner diameter of the respective neck portion (2, 2') by between 0.2 to 0.8 mm.

6. The lamp of claim 5, wherein said disks (9, 9') comprise aluminum oxide ceramic.

7. The lamp of claim 1, wherein said support element (6, 6') is self-centering within said constriction.

8. The lamp of claim 1, wherein said support element (6, 6') is of frusto-conical or part-spherical shape.

9. The lamp of claim 1, further including a high temperature resistant coating (11') applied to the outside of said neck portion (2, 2'), said coating having a high heat emission in at least the infrared spectral region.

10. The lamp of claim 1, further including a high temperature resistant coating (11') applied to the outside of said neck portion (2, 2'), said coating having a high heat emission in at least the visible spectral region.

11. The lamp of claim 9, wherein said high temperature resistant coating comprises a high temperature resistant black lacquer or varnish.

12. The lamp of claim 10, wherein said high temperature resistant coating comprises a high temperature resistant black lacquer or varnish.

13. The lamp of claim 1, wherein said plurality of spacing disks (9, 9') in the respective neck portion (2, 2') comprises ceramic material, optionally an aluminum ceramic;

and further including a high temperature resistant coating (11'), optionally a high temperature resistant lacquer or varnish, having a high heat emission within at least one of: infrared range, and visible spectral range.

14. The lamp of claim 1, wherein said noble gas of the fill comprises xenon.

15. The lamp of claim 13, wherein said noble gas of the fill comprises xenon.

16. The lamp of claim 1, wherein said plurality of disks forming the stack comprises at least five disks.