Electric lamp and discharge devices – With gas or vapor – Having electrode exterior to envelope
Reexamination Certificate
1998-12-11
2001-01-23
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Having electrode exterior to envelope
C313S035000, C313S036000
Reexamination Certificate
active
06177763
ABSTRACT:
BACKGROUND OF THE INVENTION
A known class of lamps excites a gas causing it to break down to a light emitting plasma. The well-known fluorescent lamp falls into this class. With a fluorescent lamp, a direct current (DC) is applied to a pair of electrodes in a glass tube filled with a mixture of argon and mercury. Another type of lamp falling within this class is the electrodeless lamp. As discussed in, for example, U.S. Pat. No. 5,013,959 to Kogelschatz issued May 7, 1991, an electrodeless lamp may comprise a pair of concentric dielectric tubes. An electrode is disposed within the inner tube and another surrounds the outer tube; the gas is contained in the annulus between the tubes. An alternating current (AC) is applied to the electrodes to create an electric field in the gas thereby exciting the gas. This type of lamp is known as “electrodeless” because the electrodes do not contact the gas.
Electrodeless lamps may be filled with gas which emits in the UV spectrum. In such case, the lamp will be arranged to direct light to a treatment chamber so as to treat material in the chamber with UV light.
It is desirable to maximize the light generated by the lamp, however, the outer electrode may block some light from leaving the lamp. It is also desirable to maximize lamp life, however, the high energy plasma ions may degrade the dielectric tubes.
This invention seeks to overcome drawbacks of known electrodeless lamps.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an electrodeless lamp, comprising: a gas containing chamber; a first electrode surrounded by a dielectric within said gas chamber; a second electrode surrounded by a dielectric within said gas chamber; an AC source coupled between said first and second electrodes.
In accordance with another aspect of the invention, there is provided an electrodeless lamp, comprising: a gas containing chamber having a dielectric chamber wall; a first electrode extending along said dielectric chamber wall outside of said gas containing chamber; a wound second electrode surrounded by a dielectric within said gas chamber; an AC source coupled between said first and second electrodes.
REFERENCES:
patent: 4837484 (1989-06-01), Eliasson et al.
patent: 5013959 (1991-05-01), Kogelschatz
patent: 5283498 (1994-02-01), Von Arx et al.
patent: 5866991 (1999-02-01), Farkas et al.
patent: 5932960 (1999-07-01), Terada et al.
Gallagher Thomas A.
Gordon David P.
Hopper Todd Reed
Jacobson David S.
Patel Nimeshkumar D.
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