US4255687A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low pressure mercury vapor discharge lamp
Assignee: US Philips Corp
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Filing: 1979-01-19
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Granted: 1981-03-10
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Expires: 1999-01-19
Abstract
Abstract Low pressure mercury vapor discharge lamp having a cylindrical discharge vessel the inner surface of which is, at least partly, coated with a luminescent layer, a reflecting layer containing titanium dioxide being provided between the said surface and the luminescent layer over a portion of the circumference between the ends of the discharge vessel. The reflecting layer contains up to 10% by weight of fine-grained silicon dioxide, thereby increasing the luminous flux emitted by the lamp.
Inventors
- 👤 Hielke A. van Engelen
- 👤 Petrus J. M. Willemsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:48
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/30; H01J61/35
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
113 words
A low pressure mercury vapor discharge lamp which comprises: a cylindrical discharge vessel having an inner surface; a reflecting layer containing titanium dioxide disposed on said inner surface except for an axially elongated aperture, said reflecting layer containing a finite quantity of silicon dioxide which is up to 10% by weight of the total weight of said reflecting layer, said silicon dioxide having an average particle size which is substantially equal to 25 micrometers; a luminescent layer disposed over substantially all of said reflecting layer and on said inner envelope over substantially all of said axially elongated aperture; and said axially elongated aperture having a coating which is substantially free of silicon dioxide.
Claim 2
Dependent Claim
113 words
A low pressure mercury vapor discharge lamp which comprises: a cylindrical discharge vessel having an inner surface; a reflecting layer containing titanium dioxide disposed on said inner surface except for an axially elongated aperture, said reflecting layer containing a finite quantity of silicon dioxide which is up to 10% by weight of the total weight of said reflecting layer, said silicon dioxide having an average particle size which is substantially equal to 25 micrometers; a luminescent layer disposed over substantially all of said reflecting layer and on said inner envelope over substantially all of said axially elongated aperture; and said axially elongated aperture having a coating which is substantially free of silicon dioxide.
Claim 3
Dependent Claim
25 words
A low pressure mercury vapor discharge lamp as claimed in claim 1 wherein said reflecting layer contains up to 5% by weight of antimony trioxide.
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) | 1984-03-09 | 1984-09-08 | 1985-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-09 | 1988-09-08 | 1989-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-09 | 1992-09-08 | 1993-03-10 | $7700.00 | Window Closed / Lapsed |