Patent US4182972A successfully refreshed from Google Patents.
US4182972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent polycrystalline alumina and high pressure vapor discharge lamp
Assignee: NGK Insulators Ltd
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Filing: 1978-03-06
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Granted: 1980-01-08
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Expires: 1998-03-06
Abstract
Abstract A polycrystalline alumina has at least 50% unit surface area provided by crystals of at least 60 μm, and preferably 100 μm size. This improves the in-line transmission value and hence lamp efficiency in a tube for a high pressure metal vapor lamp having an envelope of alumina.
Inventors
- 👤 Masayuki Kaneno
- 👤 Isao Oda
- 👤 Noboru Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:29
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/115; H; H01; H01J; H01J61/00; H01J61/02; H01J61/30; H01J61/302
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
64 words
A transparent polycrystalline alumina comprising alumina crystals wherein the alumina consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina, and wherein crystals having a size of at least 60 μm occupy not less than 50% of unit surface area.
Claim 2
Dependent Claim
64 words
A transparent polycrystalline alumina comprising alumina crystals wherein the alumina consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina, and wherein crystals having a size of at least 60 μm occupy not less than 50% of unit surface area.
Claim 3
Dependent Claim
64 words
A transparent polycrystalline alumina comprising alumina crystals wherein the alumina consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina, and wherein crystals having a size of at least 100 μm occupy not less than 50% of unit surface area.
Claim 4
Dependent Claim
64 words
A transparent polycrystalline alumina comprising alumina crystals wherein the alumina consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina, and wherein crystals having a size of at least 100 μm occupy not less than 50% of unit surface area.
Claim 5
Dependent Claim
95 words
A high pressure vapor discharge lamp comprising a tubular discharge envelope, two sealed electrodes at respective ends of the envelope, and an ionizing medium within the envelope, the envelope comprising a transparent polycrystalline alumina tube wherein crystals of alumina having a size of at least 60 μm occupy not less than 50% of unit surface area, and wherein the alumina tube consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina.
Claim 6
Dependent Claim
95 words
A high pressure vapor discharge lamp comprising a tubular discharge envelope, two sealed electrodes at respective ends of the envelope, and an ionizing medium within the envelope, the envelope comprising a transparent polycrystalline alumina tube wherein crystals of alumina having a size of at least 60 μm occupy not less than 50% of unit surface area, and wherein the alumina tube consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina.
Claim 7
Dependent Claim
94 words
A high pressure discharge lamp comprising a tubular discharge envelope, two sealed electrodes at respective ends of the envelope, and an ionizing medium within the envelope, the envelope comprising a tranparent polycrystalline alumina tube wherein crystals of alumina having a size of at least 100 μm occupy not less than 50% of unit surface area, ad wherein the alumina tube consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina.
Claim 8
Dependent Claim
94 words
A high pressure discharge lamp comprising a tubular discharge envelope, two sealed electrodes at respective ends of the envelope, and an ionizing medium within the envelope, the envelope comprising a tranparent polycrystalline alumina tube wherein crystals of alumina having a size of at least 100 μm occupy not less than 50% of unit surface area, ad wherein the alumina tube consists of 0.01 to 0.2% MgO, 0.01 to 0.2% La 2 O 3 , 0.01 to 0.2% Y 2 O 3 , the balance being alumina and the percentages being by weight of alumina.
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) | 1983-01-07 | 1983-07-09 | 1984-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-01-07 | 1987-07-09 | 1988-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-01-07 | 1991-07-09 | 1992-01-08 | $7700.00 | Window Closed / Lapsed |