US3877495A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing improved filaments for fluorescent lamps
Assignee: Duro Test Corp
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Filing: 1974-03-04
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Granted: 1975-04-15
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Expires: 1994-03-04
Abstract
Abstract A method for manufacturing an annealed tungsten filament wire for electric lamps with a reduced amount of impurities in which the filament wire is wound on a mandrel, either the wire or the mandrel is coated with a protective material, the wire is annealed at an elevated temperature, and the wire is removed from the mandrel.
Inventors
- 👤 Ronald C Koo
- 👤 Joel Shurgan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:13
CPC Classifications
H; H01; H01K; H01K3/00; H01K3/02; B; B21; B21F; B21F3/00; B21F3/02; B21F3/04; H01K1/00; H01K1/02; H01K1/04; H01K1/08; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/4981; Y10T29/49812
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
78 words
A METHOD OF FORMING A FILAMENT FOR AN ELECTRIC LAMP COMPRISING THE STEPS OF WINDING A TUNGSTEN WIRE MEMBER IN A COIL ON A MANDREL CONTAINING IRON, COATING ONE OF THE WIRE AND MANDREL MEMBERS WITH A COATING CONTAINING COPPER, ANNEALING THE TUNGSTEN WIRE ON THE MANDREL AT AN ELEVATED TEMPERATURE TO MELT THE COATING FOR A PERIOD OF TIME SUCH THAT NO SIGNIFICANT AMOUNT OF IMPURITIES DIFFUSE INTO THE WIRE, AND REMOVING THE MANDREL FROM THE COIL.
Claim 2
Independent Claim
78 words
A METHOD OF FORMING A FILAMENT FOR AN ELECTRIC LAMP COMPRISING THE STEPS OF WINDING A TUNGSTEN WIRE MEMBER IN A COIL ON A MANDREL CONTAINING IRON, COATING ONE OF THE WIRE AND MANDREL MEMBERS WITH A COATING CONTAINING COPPER, ANNEALING THE TUNGSTEN WIRE ON THE MANDREL AT AN ELEVATED TEMPERATURE TO MELT THE COATING FOR A PERIOD OF TIME SUCH THAT NO SIGNIFICANT AMOUNT OF IMPURITIES DIFFUSE INTO THE WIRE, AND REMOVING THE MANDREL FROM THE COIL.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said annealing is carried out so that there is less than about 15 parts per million (by weight) of iron in the annealed filament coil.
Claim 4
Dependent Claim
21 words
The method of claim 1 further comprising the step of drawing the tungsten wire before it is wound over the mandrel.
Claim 5
Dependent Claim
21 words
The method of claim 2 further comprising the step of drawing the tungsten wire before it is wound over the mandrel.
Claim 6
Dependent Claim
13 words
The method of claim 1 wherein said coating step comprises coating said wire.
Claim 7
Dependent Claim
13 words
The method of claim 1 wherein said coating step comprises coating said mandrel.
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) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |