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Filament support for lamp

Imported: 24 Feb '17 | Published: 24 Aug '04

Michael W. Halpin

USPTO - Utility Patents

Abstract

An improved support is provided for locating a lamp filament axially within a lamp sleeve. The illustrated support is a spiral coil that includes a small diameter center portion that makes contact with the filament. On either side of the filament-contacting portion, the coil opens up to larger diameters for contacting the inner wall of the quartz sleeve within which the filament is housed. The support thus appears H-shaped when viewed from the side. A lamp filament is also provided with expansion compensation sections at either end of a central section. The filament wire in the compensation sections is wound into coils having a greater diameter and also a greater spacing between windings, as compared to coil in the central section. The expansion compensation sections are preferably capable of compressing and thereby absorbing thermal expansion of the filament during operation, without shorting the filament across adjacent windings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be readily apparent from the description below and the appended drawings, in which like reference numerals refer to similar parts throughout, which are meant to illustrate and not to limit the invention, and in which:

FIG. 1 is a side view of a typical lamp with a conventional filament support.

FIG. 2 is a side view of a typical lamp illustrating the problem of shorting caused by rotation of the support and sagging of the filament.

FIG. 3 is a side view of a filament support used in conjunction with a dimpled lamp sleeve.

FIG. 4 is an enlarged view showing two supports which hold a filament away from a lamp tube wall, constructed in accordance with a preferred embodiment of the present invention

FIG. 5 is a side view of a tubular lamp having a plurality of supports, constructed in accordance with a preferred embodiment of the present invention.

FIG. 6 is a schematic side view of a lamp, for purposes of illustrating the effect of thermal expansion upon the lamp filament.

FIG. 7 is a schematic side view of one end of a lamp provided with thermal compensation sections, in accordance with another embodiment of the present invention.

FIG. 8 is a schematic side view of a lamp employing thermal expansion compensation sections at both ends, for purposes of illustrating the operation of the preferred embodiment.

Claims

1. A lamp, comprising:

2. The lamp of claim 1, wherein the ratio of L/D for each pair is between about 0.7 and 1.1.

3. The lamp of claim 2, wherein the ratio of L/D for each pair is about 1.0.

4. The lamp of claim 1, wherein the sleeve-contacting portions of each pair are connected to one another.

5. The lamp of claim 4, wherein the sleeve-contacting portions are sized to closely conform to the inner surface of the transparent sleeve, each filament support further comprising a smaller inner portion sized to closely conform to an outer surface of the filament.

6. The lamp of claim 5, wherein the filament comprises a wire coil and the inner portion of each filament support closely conforms to the outer surface of the coiled wire.

7. The lamp of claim 4, wherein each filament support comprises two conical spirals joined at their apexes, the sleeve-contacting portions formed by outer winds of the conical spirals.

8. The lamp of claim 4, wherein each filament support resembles the letter “H” when viewed from the side.

9. The lamp of claim 4, wherein each filament support resembles the letter “X” when viewed from the side.

10. The lamp of claim 1, wherein the filament is suspended between a pair of expansion compensation sections proximate lateral ends of the filament, the expansion compensation sections being more readily compressible than the coil of the central section without shorting.

11. The lamp of claim 1, having a maximum capacity of greater than about 1 kW.

12. The lamp of claim 1, having a maximum capacity of greater than about 3 kW.

13. The lamp of claim 1, having a maximum capacity of greater than about 6 kW.

14. The lamp of claim 1, having a maximum capacity of greater than about 10 kW.

15. A lamp having a maximum capacity of at least about 1 kW, the lamp comprising:

16. The lamp of claim 15, wherein the filament-contacting portion is interposed between the first and second sleeve-contacting portions.

17. The lamp of claim 15, wherein the filament comprises a wire coil and the filament-contacting portion of the filament support closely conforms to an outer surface of the coiled wire.

18. The lamp of claim 15, wherein the filament support comprises two spirals, the sleeve-contacting portions formed by outer winds of the spirals.

19. The lamp of claim 18, wherein the spirals comprise conical spirals tapering from the sleeve-contacting portions.

20. The lamp of claim 19, wherein spirals are joined near their apexes to form the filament-contacting portion.

21. The lamp of claim 15, wherein the ratio of L/D is between about 0.7 and 1.1.

22. The lamp of claim 15, comprising a plurality of axially spaced filament supports.

23. A filament support for radially spacing a lamp filament from a transparent sleeve, the filament support comprising:

24. The filament support of claim 23, comprising two conical spirals joined at their apexes, the sleeve-contacting portions formed by outer winds of the conical spirals.

25. The filament support of claim 23, wherein the filament-contacting portion is interposed between the first and second sleeve-contacting portions.

26. The filament support of claim 23, wherein the ratio of L/D is between about 0.7 and 1.1.