US4412963A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing discharge lamp arc tubes
Assignee: Thorn EMI Ltd
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Filing: 1981-12-18
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Granted: 1983-11-01
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Expires: 2001-12-18
Abstract
Abstract The invention provides a method of producing discharge lamp arc tubes of ceramic material complete with metal cermet end closure members using initially incompletely fired sintered components and a sealing composition selected from silica, alumina and magnesia in proportions such that the composition falls within the accompanying ternary phase diagram BCDEFXYZPQ. The sealing compositions may also contain up to 5% by weight of nucleating agents such as phosphorous pentoxide, rare earth oxides, titania, zirconia or chromia. The inclusion of up to 5% by weight of boric oxide improves the flow characteristics and up to 10% by weight of Y 2 O 3 , Yb 2 O 3 , La 2 O 3 , Dy 2 O 3 , Eu 2 O 3 , HfO 2 improves the thermal and mechanical properties of the seals. The invention eliminates the need to make a first end seal by separate sintering and sealing operations.
Inventors
- 👤 Peter Hing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:39
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/36; C; C04; C04B; C04B37/00; C04B37/003; C04B37/005; C04B2237/00; C04B2237/02; C04B2237/04; C04B2237/06; C04B2237/062; C04B2237/064; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/343; C04B2237/40; C04B2237/401; C04B2237/50; C04B2237/76; C04B2237/765
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
141 words
A method of producing an arc tube for a discharge lamp which method comprises forming an assembly of one sintered cermet end closure member hermetically sealed to a ceramic arc tube of polycrystalline alumina, sapphire or a spinel by means of the following steps: providing an arc tube in the incompletely fired state, providing an end closure member in the incompletely fired state complete with an electrode assembled thereto, applying a layer of sealing composition between said end closure member and said arc tube and sintering the assembled arc tube and end closure complete with electrode at a temperature of from 1800° C. to 1900° C. in a vacuum, inert gas or a hydrogen atmosphere wherein said sealing composition comprises silica, alumina and magnesia in proportions such that said composition falls between the area BCDEFXYZPQ on the accompanying ternary phase diagram.
Claim 2
Independent Claim
141 words
A method of producing an arc tube for a discharge lamp which method comprises forming an assembly of one sintered cermet end closure member hermetically sealed to a ceramic arc tube of polycrystalline alumina, sapphire or a spinel by means of the following steps: providing an arc tube in the incompletely fired state, providing an end closure member in the incompletely fired state complete with an electrode assembled thereto, applying a layer of sealing composition between said end closure member and said arc tube and sintering the assembled arc tube and end closure complete with electrode at a temperature of from 1800° C. to 1900° C. in a vacuum, inert gas or a hydrogen atmosphere wherein said sealing composition comprises silica, alumina and magnesia in proportions such that said composition falls between the area BCDEFXYZPQ on the accompanying ternary phase diagram.
Claim 3
Dependent Claim
27 words
A method of producing an arc tube for a discharge lamp according to claim 1 wherein the cermet material comprises alumina and tungsten or alumina and molybdenum.
Claim 4
Dependent Claim
29 words
A method of producing an arc tube according to claim 1 wherein said sealing composition includes minor additions of nucleating agents selected from phosphorus pentoxide, titania, zirconia or chromia.
Claim 5
Dependent Claim
30 words
A method of producing an arc tube for a discharge lamp according to claim 3 wherein said nucleating agent is added in an amount up to about 5% by weight.
Claim 6
Dependent Claim
29 words
A method of producing an arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes up to about 5% by weight of boric oxide.
Claim 7
Dependent Claim
30 words
A method of producing an arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes up to about 10% by weight of rare earth oxides.
Claim 8
Dependent Claim
51 words
A method of producing an arc tube for a discharge lamp according to claim 6 wherein said rare earth oxides are selected from Y 2 O 3 , Yb 2 O 3 , La 2 O 3 , Dy 2 O 3 , Eu 2 O 3 and HfO 2 .
Claim 9
Dependent Claim
30 words
A method of producing an arc tube for a discharge lamp according to claim 1 wherein the volume fraction of metal in the cermet material is between 0.045 and 0.2.
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) | 1986-10-31 | 1987-05-02 | 1987-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-31 | 1991-05-02 | 1991-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-31 | 1995-05-02 | 1995-11-01 | $7700.00 | Window Closed / Lapsed |