US5325018A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrodeless fluorescent lamp shield for reduction of electromagnetic interference and dielectric losses
Assignee: General Electric Co
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Filing: 1992-08-28
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Granted: 1994-06-28
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Expires: 2012-08-28
Abstract
Abstract An electrodeless fluorescent lamp of the type having a solenoidal drive coil wound about a ferrite core includes an inner shield between the coil and the core and further includes an outer shield about the coil. The shields are preferably constructed of sheets of flexible polyimide material with vertical bands of metal etched thereon. The metal bands are connected to ground in order to shield the core and the plasma from the electric field generated about the drive coil. By thus shielding the core, the capacitance between the coil and the core is effectively short-circuited, substantially reducing or eliminating dielectric losses of the core. The outer shield substantially reduces the EMI generated by the drive coil.
Inventors
- 👤 Sayed-Amr A. El-Hamamsy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 02:32
CPC Classifications
H; H01; H01J; H01J65/00; H01J65/04; H01J65/042; H01J65/048
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
183 words
An electrodeless fluorescent lamp, comprising: a light-transmissive envelope containing an ionizable, gaseous fill for sustaining an arc discharge when subjected to a radio frequency magnetic field and for emitting ultraviolet radiation as a result thereof, said envelope having an interior phosphor coating for emitting visible radiation when excited by said ultraviolet radiation; a winding disposed about an inductive core and situated within said envelope for coupling to a radio frequency supply and establishing said radio frequency magnetic field about said winding, said inductive core being cylindrical with a longitudinal axis; an EMI shield wrapped about said winding, said EMI shield comprising a plurality of metal bands disposed on a flexible dielectric material, said metal bands being parallel to the longitudinal axis of said core, said metal bands being discontinuous in an aximuthal direction so as to avoid short-circuiting said discharge, said metal bands being coupled to a circuit ground; and an inner shield disposed between said core and said winding, said inner shield comprising a plurality of metal bands disposed on a dielectric material, said metal bands being coupled to said circuit ground.
Claim 2
Dependent Claim
183 words
An electrodeless fluorescent lamp, comprising: a light-transmissive envelope containing an ionizable, gaseous fill for sustaining an arc discharge when subjected to a radio frequency magnetic field and for emitting ultraviolet radiation as a result thereof, said envelope having an interior phosphor coating for emitting visible radiation when excited by said ultraviolet radiation; a winding disposed about an inductive core and situated within said envelope for coupling to a radio frequency supply and establishing said radio frequency magnetic field about said winding, said inductive core being cylindrical with a longitudinal axis; an EMI shield wrapped about said winding, said EMI shield comprising a plurality of metal bands disposed on a flexible dielectric material, said metal bands being parallel to the longitudinal axis of said core, said metal bands being discontinuous in an aximuthal direction so as to avoid short-circuiting said discharge, said metal bands being coupled to a circuit ground; and an inner shield disposed between said core and said winding, said inner shield comprising a plurality of metal bands disposed on a dielectric material, said metal bands being coupled to said circuit ground.
Claim 3
Dependent Claim
24 words
The electrodeless fluorescent lamp of claim 1 wherein said metal bands of said EMI shield are coupled together by a conductor situated perpendicular thereto.
Claim 4
Dependent Claim
18 words
The electrodeless fluorescent lamp of claim 2 wherein said conductor is situated toward the bottom of said envelope.
Claim 5
Dependent Claim
19 words
The electrodeless fluorescent lamp of claim 1 wherein said metal bands of said EMI shield are comprised of copper.
Claim 6
Dependent Claim
21 words
The electrodeless fluorescent lamp of claim 1 wherein said dielectric material of said EMI shield is comprised of a polyimide film.
Claim 7
Dependent Claim
24 words
The electrodeless fluorescent lamp of claim 1 wherein said metal bands of said inner shield are parallel to the longitudinal axis of said core.
Claim 8
Dependent Claim
24 words
The electrodeless fluorescent lamp of claim 6 wherein said metal bands of said inner shield are coupled together by a conductor situated perpendicular thereto.
Claim 9
Dependent Claim
18 words
The electrodeless fluorescent lamp of claim 7 wherein said conductor is situated toward the bottom of said envelope.
Claim 10
Dependent Claim
19 words
The electrodeless fluorescent lamp of claim 1 wherein said metal bands of said inner shield are comprised of copper.
Claim 11
Dependent Claim
21 words
The electrodeless fluorescent lamp of claim 1 wherein said dielectric material of said inner shield is comprised of a polyimide film.
Claim 12
Dependent Claim
17 words
The electrodeless fluorescent lamp of claim 1 wherein said EMI shield covers all turns of said winding.
Claim 13
Dependent Claim
22 words
The electrodeless fluorescent lamp of claim 1 wherein at least one turn of said winding is not covered by said EMI shield.
Claim 14
Dependent Claim
18 words
The electrodeless fluorescent lamp of claim 12 wherein said one turn comprises the top turn of said coil.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-06-27 | 1997-12-27 | 1998-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-27 | 2001-12-27 | 2002-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-27 | 2005-12-27 | 2006-06-28 | $7700.00 | Window Closed / Lapsed |