US3708710A
Expired / Lapsed
US
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Discharge lamp thermoionic cathode containing emission material
Assignee: General Electric Co
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Filing: 1970-12-14
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Granted: 1973-01-02
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Expires: 1990-12-14
Abstract
Abstract Thermionic electrodes for high intensity discharge lamps, particularly sodium vapor lamps, contain dibarium calcium tungstate, Ba2CaWO6, as emission material. At temperatures over 1000*C, the material has good electron emission coupled with an evaporation rate appreciably lower than that of other bariumcontaining emission materials. Lamps show negligible voltage rise, maintenance of 89 percent at 14,000 hours, and life in excess of 14,000 hours.
Inventors
- 👤 W Smyser
- 👤 D Speros
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:37
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/04; H01J61/06; H01J61/073; H01J61/0735; H01J61/0737
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
22 words
A lamp as in claim 1 wherein the electron emissive material consists of BaO:CaO:WO3 in molar ratios extending from 1.9:1:1 to 2.1:1:1.
Claim 2
Dependent Claim
18 words
A lamp as in claim 1 wherein the electron emissive material consists of a Ba2CaWO6 solid solution phase.
Claim 3
Dependent Claim
15 words
A lamp as in claim 1 wherein the electron emissive material consists of essentially Ba2CaWO6.
Claim 4
Dependent Claim
98 words
A high intensity sodium vapor discharge lamp comprising a slender tubular elongated ceramic envelope, a pair of electrodes sealed into the ends of said envelope, a filling of sodium, mercury and an inert gas within said envelope, each electrode comprising a tungsten wire coil to which is applied an electron emissive material filling the interstices between turns of the coil, said electron emissive material consisting of a refractory metal support structure and electron emissive material applied thereto consisting of composites in the BaO-CaO-WO3 system containing 43-54 mole percent BaO, 20-30 mole percent CaO, and 21-27 mole percent WO3.
Claim 5
Dependent Claim
22 words
A lamp as in claim 5 wherein the electron emissive material consists of BaO:CaO:WO3 in molar ratios extending from 1.9:1:1 to 2.1:1:1.
Claim 6
Dependent Claim
18 words
A lamp as in claim 5 wherein the electron emissive material consists of a Ba2CaWO6 solid solution phase.
Claim 7
Dependent Claim
15 words
A lamp as in claim 5 wherein the electron emissive material consists of essentially Ba2CaWO6.
References Cited (Backward Citations)
US3434812A
Cited
US3294998A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |