Patent US3935492A successfully refreshed from Google Patents.
US3935492A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Nittan Co Ltd
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Filing: 1973-05-03
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Granted: 1976-01-27
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Expires: 1993-05-03
Abstract
Abstract An ionization smoke detector having two ionization chambers with one of said chambers having an electrode at least partially surrounded by a conductive mesh constituting an intermediate electrode and the other of said chambers being formed between the intermediate electrode and an outer surrounding electrode of conductive mesh and a radioactive source carried by said outer electrode. The volume defined by the outer and intermediate electrodes is greater than the volume defined by the intermediate electrode.
Inventors
- 👤 Koju Sasaki
- 👤 Akihiro Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:05
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
101 words
An ionization smoke detector comprising an inner electrode, means including an air permeable intermediate electrode enclosing said inner electrode, means including an air permeable outer electrode enclosing said inner and intermediate electrodes, said intermediate electrode defining an inner chamber which includes said inner electrode and said intermediate and outer electrodes defining an outer chamber of substantially greater volume than said inner chamber and a radioactive source disposed within one of said chambers to ionize the gas within the last said chamber, the radioactive emission from said source penetrating said intermediate electrode to ionize the gas within the other of said chambers.
Claim 2
Dependent Claim
101 words
An ionization smoke detector comprising an inner electrode, means including an air permeable intermediate electrode enclosing said inner electrode, means including an air permeable outer electrode enclosing said inner and intermediate electrodes, said intermediate electrode defining an inner chamber which includes said inner electrode and said intermediate and outer electrodes defining an outer chamber of substantially greater volume than said inner chamber and a radioactive source disposed within one of said chambers to ionize the gas within the last said chamber, the radioactive emission from said source penetrating said intermediate electrode to ionize the gas within the other of said chambers.
Claim 3
Dependent Claim
18 words
An ionization smoke detector according to claim 1 wherein said radioactive source is disposed within the outer chamber.
Claim 4
Dependent Claim
19 words
An ionization smoke detector according to claim 1 wherein said inner, intermediate and outer electrodes are of rectangular configuration.
Claim 5
Dependent Claim
19 words
An ionization smoke detector according to claim 1 wherein said inner, intermediate and outer electrodes are of semicircular configuration.
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) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |