Electric lamp and discharge devices – With gas or vapor – Having a particular total or partial pressure
Reexamination Certificate
1999-02-03
2001-07-31
Patel, Nimeshkumar D. (Department: 2873)
Electric lamp and discharge devices
With gas or vapor
Having a particular total or partial pressure
C313S493000, C313S573000, C313S634000, C313S635000, C313S636000, C313S637000, C313S638000, C501S064000, C501S066000
Reexamination Certificate
active
06268696
ABSTRACT:
TECHNICAL FIELD
This invention relates to discharge lamps and more particularly to high pressure sodium lamps. Still more particularly, it relates to such lamps that are environmentally disposable.
BACKGROUND ART
Discharge lamps generally include a discharge chamber of quartz or alumina supported within an envelope of borosilicate or aluminosilicate glass. Disposal of these lamps at the end of life has been deemed an environmental hazard because the outer envelope glass includes lead and arsenic and the discharge chamber includes mercury. Further, the electrically conductive base may have the in-leads for the lamp attached thereto by a lead-based solder. The lead, arsenic and mercury are presumed to be hazardous to animal and human health.
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 provide an environmentally safe lamp that may be disposed of easily.
Yet another object of the invention is the enhancement of lamp disposal.
These objects are accomplished, in one aspect of the invention, by the provision of a long-life, environmentally disposable high pressure sodium lamp comprising: an arc tube capable of withstanding internal wall temperatures of 1250 to 1300° C. and having electrodes sealed therein and being designed for operation at a given wattage; a discharge space within the arc tube and an arc generating and sustaining medium within the discharge space, the medium being mercury-free and containing sodium in an amount of about 0.02 mg to 0.06 mg/watt of designed operation, and xenon at a pressure of 100 to 200 Torr; mounting means supporting the arc tube within a glass outer envelope, the glass outer envelope being lead-free and arsenic-free; and an electrically conductive base closing the outer envelope and containing lead-in wires affixed to the electrodes, the lead-in wires being attached to the base by welding.
Lamps so constructed may be safely and legally disposed of in conventional land fills.
REFERENCES:
patent: 5682082 (1997-10-01), Wei et al.
patent: 6118216 (2000-09-01), Marlor
patent: 0790639 (1997-08-01), None
patent: 7272680 (1995-10-01), None
Dolan Robert B.
Plumb John L.
Wyner Elliot F.
Haynes Mack
McNeill William H.
Osram Sylvania Inc.
Patel Nimeshkumar D.
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