Electric lamp and discharge devices – With gas or vapor – Having particular electrode structure
Reexamination Certificate
1998-12-04
2001-07-31
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Having particular electrode structure
C313S493000, C313S634000
Reexamination Certificate
active
06268698
ABSTRACT:
TECHNICAL FIELD
This invention relates to starting aids and more particularly to starting aids for high intensity discharge lamps. It has particular application to high intensity discharge lamps fabricated from quartz.
BACKGROUND ART
Starting low wattage (20w to 70w) or even higher wattage high intensity discharge lamps often requires the use of glow bottles in addition to a ballast that supplies a high voltage pulse to start the lamp. The glow bottles that have been suggested and employed contain a partial pressure (<1 atmosphere) of argon or nitrogen or other gas mixtures. They may even include a partial pressure of mercury. These glow bottles contain an additional electrical lead that facilitates the “glow” or ionization of the contained gases when a sufficient potential is applied thereto. The glass vessel of the glow bottle must also be in close proximity to a lead-in of the opposite potential for the glow or ionization to occur.
The use of glow bottles works well in normal environments; however, their use becomes a problem as the size of the lamps gets smaller. For example, there is insufficient room in the neck region of a PAR20 lamp jacket to permit glow bottle placement. Also, such placement would encounter additional problems associated with distortion of the projected image or light beam if the glow bottle were placed in an area that interferes with the reflector surface or with the lensing optics of the lamp.
One solution to the problem that has been suggested employs radioactive krypton 85 as the arc tube gas fill; however, that solution requires the expense of extra filtering and hazardous material licenses.
DISCLOSURE OF INVENTION
It is, therefore, an object of the invention to obviate the disadvantages of the prior art.
It is another object of the invention to enhance the starting of high intensity discharge lamps.
It is another object of the invention to provide a starting aid for high intensity discharge lamps that does not employ hazardous materials
These objects are accomplished, in one aspect of the invention, by the provision of an hermetically sealed arc tube which comprises a hollow body having oppositely disposed ends aligned along a longitudinal axis and containing an arc generating and sustaining medium therein. An electrode is positioned in each end of the hollow body and an ionization zone is positioned adjacent to one of the ends and is a part thereof. The ionization zone is exposed to an atmosphere different than the arc generating and sustaining medium.
In a further embodiment there is provided an arc tube for a discharge lamp comprising: an hermetically sealed hollow body containing an arc generating and sustaining medium therein and having first and second ends; an electrode receiving seal extending from each end; an electrode structure positioned in each of said seals, each of said electrode structures comprising a proximal electrode end projecting into the interior of said hollow body, a distal end projecting exteriorly of said seal, and an intermediate section therebetween, said intermediate section being sealed in said seal in an hermetic manner; and a seal extension attached to a first one of said seals and extending in a direction away from said hollow body, said extension comprising a tubular segment substantially surrounding said distal end of said electrode projecting from said seal at said first end; and a starting aid comprising an electrode adjunct affixed to said distal end of said electrode projecting from said first end within said tubular segment and an electrically conducting member surrounding said tubular segment and being electrically connected to the distal end of the electrode structure positioned in said second end.
REFERENCES:
patent: 5323091 (1994-06-01), Morris
patent: 0313027 (1989-04-01), None
patent: 0722184 (1996-07-01), None
patent: 2061957 (1990-03-01), None
patent: 2061958 (1990-03-01), None
McNeill William H.
Osram Sylvania Inc.
Patel Vip
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