The foregoing forms as well as other forms, features and advantages of the present invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the present invention rather than limiting, the scope of the present invention being defined by the appended claims and equivalents thereof.
FIG. 1 illustrates a high wattage metal halide lamp employing a charged mount structure as known in the art;
FIG. 2 illustrates a high wattage metal halide lamp employing a first embodiment of a floating mount structure in accordance with the present invention;
FIG. 3 illustrates a high wattage metal halide lamp employing a second embodiment of a floating mount structure in accordance with the present invention;
FIG. 4 illustrates an exemplary graph of a voltage rise in a vacuum over time for a 1000 watt version of the lamp illustrated in FIG. 1 and of the lamps illustrated in FIGS. 2 and 3;
FIG. 5 illustrates an exemplary graph of a lumen maintenance in a vacuum over time for a 1000 watt version of the lamp illustrated in FIG. 1 and of the lamps illustrated in FIGS. 2 and 3;
FIG. 6 illustrates an exemplary graph of a lamp efficacy in a vacuum over time for a 1000 watt version of the lamp illustrated in FIG. 1 and of the lamps illustrated in FIGS. 2 and 3;
FIG. 7 illustrates an exemplary graph of a color shift in a vacuum over time for a 1000 watt version of the lamp illustrated in FIG. 1 and of the lamps illustrated in FIGS. 2 and 3; and
FIG. 8 illustrates an exemplary graph of an x-coordinate in a vacuum over time for a 1000 watt version of the lamp illustrated in FIG. 1 and of the lamps illustrated in FIGS. 2 and 3.
The drawings illustrated in FIGS. 1-3 are not intended to be drawn to scale, but to facilitate an understanding of various principles of the present invention. Those having ordinary skill in the art will appreciate that, in practice, the actual shapes, dimensions and material construction of each discharge lamp in accordance with the present invention are dependent upon an intended commercial application of the discharge lamp. Thus, the inventor of the present invention does not impose any restrictions as to the shapes, dimensions and material construction of each discharge shape, and does not assert any “best” shape or any “best” dimension or any “best” material construction of each discharge lamp in accordance with the present invention.
One inventive principle of the present invention is to electrically isolate each metal strap and each getter from each frame wire to thereby impede a production of photoelectrons by the metal strap(s) and the getter(s) when the lamp is in operation. This is accomplished by an electric insulation of any connection of a metal strap to one or more of the frame wires and by establishing a minimum air gap between unconnected portions of the metal strap(s) and the frame wire(s).
The following descriptions of FIGS. 2 and 3 provide exemplary embodiments of the present invention incorporating the aforementioned inventive principle of the present invention.
FIG. 2 illustrates a high wattage metal halide lamp 11 having a floating mount structure for mounting arc tube 30 within outer bulb envelope 20. This floating mount structure employs primary frame wire 40, secondary frame wire 50, dome metal strap 60, base metal strap 61, dome getter 70, base getter 71, spring strap 80, stem 81, dome connector 90 and base connector 91 as previously introduced in connection with FIG. 1. To electrically isolate metal strap 60 and getter 70 from frame wires 40 and 50, an insulator 100 (e.g., 3 mm length) is wrapped around a portion of dome wire section 41 adjacent the physical connection of metal strap 60 to dome wire section 41, and adjacent the physical connection of dome connector 90 to dome wire section 41. Additionally, metal strap 60 is physically connected to insulated wire section 43 and spaced from the boundary between dome wire section 41 and insulated wire section 43 (e.g., 3 mm spatial distance), and metal strap 60 is considerably spaced from frame wire 50. To electrically isolate metal strap 61 and getter 71 from frame wires 40 and 50, an air gap AG1 (e.g., 8 mm air gap) is established between frame wire 50 and metal strap 61. Additionally, metal strap 61 is physically connected to insulated wire section 43 and spaced from the boundary between base wire section 42 and insulated wire section 43 (e.g., 3 mm spatial distance).
FIG. 3 illustrates a high wattage metal halide lamp 12 having another floating mount structure for mounting arc tube 30 within outer bulb envelope 20. This floating mount structure also employs primary frame wire 40, secondary frame wire 50, dome metal strap 60, base metal strap 61, dome getter 70, base getter 71, spring strap 80, stem 81, and base connector 91 as previously introduce in connection with FIG. 1. This floating mount structure further employs a dome connector 92 in lieu of dome connector 90 (FIG. 1). To electrically isolate metal strap 60 and getter 70 from frame wires 40 and 50, an air gap AG2 (e.g., 8 mm air gap) is established between frame wire 40 and metal strap 60. Additionally, metal strap 60 is physically connected to insulated wire section 43 and spaced from the boundary between dome wire section 41 and insulated wire section 43 (e.g., 3 mm spatial distance), and metal strap 60 is considerably spaced from frame wire 50. To support the weight of arch tube 30, connector 92 is further physically connected to both legs of dome wire section 41 as well as a hairpin 36 extending into dome pinch 31. To electrically isolate metal strap 61 and getter 71 from frame wires 40 and 50, air gap AG1 is again established between frame wire 50 and metal strap 61, and metal strap 61 is physically connected to insulated wire section 43 and spaced from the boundary between base wire section 42 and insulated wire section 43 (e.g., 3 mm spatial distance).
An accelerated life test of lamps in accordance with lamps 10-12 (FIGS. 1-3) for up to 2,000 hours demonstrated that the floating mount structure provides much less voltage rise, better lumen maintenance, and better color consistency than the prior art charged mount structure. Graphs 110-114 as illustrated in FIGS. 4-8 exemplarily highlight this distinction between the floating mount structure and the prior art charged mount structure based on 1000 watt metal halide versions of lamps 10-12. A chemical analysis of arc tubes in accordance with lamps 10-12 revealed a much slower sodium diffusion for the floating mount structure as compared to the prior art charged mount structure. The following TABLE 1 exemplarily highlights this distinction between the floating mount structure and the prior art charged mount structure based on 1000 watt metal halide versions of lamps 10-12:
TABLE 1
|
|
Lamp ID
|
1
2
3
4
|
Structure
|
Floating Mount Structure
Charged Mount Structure
|
1000 W
1000 W
1000 W
1000 W
|
2000 hrs.
2000 hrs.
2000 hrs.
2000 hrs.
|
|
Outer bulb
|
Inner Bulb μg
140
49.7
373
308
|
Na
|
Stem μg Na
24.5
14.1
28.8
30.9
|
Base μg Na
47.5
22.9
28.3
72.0
|
Al2O3 μg Na
56.6
22.7
26.5
26.5
|
Arc tube
|
Na mg
7.806
7.996
3.812
3.492
|
I mg
54.8
54.9
47.5
42.5
|
Th μg
894
475
382
196
|
Sc μg
868
693
927
466
|
|
Clearly, the floating mount structure of the present invention provides advantages over the prior art charged mount structure.
While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.
Patent Application
20080093991
