US3798490A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vibration resistant lamp
Assignee: General Electric Co
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Filing: 1972-09-01
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Granted: 1974-03-19
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Expires: 1992-09-01
Abstract
Abstract An incandescent lamp having a filament made of tungsten wire containing between 1-2 percent by weight thoria has greatly improved resistance to fracture caused by shock and vibration thereby increasing the service life of the lamp. The thoriated tungsten filament has a recrystallized grain structure which is characterized by approximately equiaxed crystals of tungsten of a smaller and more uniform size and thoria particles which are more uniformly distributed throughout the tungsten matrix than can be obtained by conventional powder metallurgy.
Inventors
- 👤 S Ackerman
- 👤 T Dunham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:04
CPC Classifications
H; H01; H01K; H01K1/00; H01K1/02; H01K1/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
19 words
An incandescent lamp as claimed in claim 1 wherein said thoria range is 1.3 to 1.9 by weight percent.
Claim 2
Dependent Claim
57 words
An incandescent lamp as claimed in claim 1 wherein said filament is further characterized by the thoria particles being distributed in a slight but uniform concentration gradient with maximum concentration being located at the exterior surface of the filament and with said thoria concentration continuously diminishing with increasing distance to the longitudinal central axis of the filament.
Claim 3
Dependent Claim
34 words
An incandescent lamp as claimed in claim 1 wherein said filament is further characterized by the thoria particles being distributed more uniformly throughout the tungsten than can be obtained by conventional powder metallurgy processes.
Claim 4
Dependent Claim
74 words
An incandescent lamp comprisiNg a sealed vitreous envelope, lead-in conductors hermetically sealed in the envelope and connected to a plurality of incandescible filaments wherein the improvement comprises that one of the filaments consists essentially of a tungsten alloy containing between 1 and 2 percent thoria by weight, said tungsten alloy having a recyrstallized grain structure of approximately equiaxed tungsten crystals with a grain size smaller than can be obtained by conventional powder metallurgy preparation.
Claim 5
Dependent Claim
21 words
An incandescent lamp as claimed in claim 5 wherein the thoria concentration range is between 1.3 and 1.9 by weight percent.
References Cited (Backward Citations)
US3211943A
Cited
US3697321A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |