US3792279A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Nittan Co Ltd
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Filing: 1971-10-29
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Granted: 1974-02-12
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Expires: 1991-10-29
Abstract
Abstract An ionization smoke detector having at least one ionization chamber open to ambient air and connected to a voltage supply, a field effect transistor having a source-drain path connected to said supply and a gate interconnected with said chamber to sense the voltage across the chamber, the source-drain path having a plurality of series connected diodes in series therewith and terminals connected to the junctions between the diodes in order to obtain a desired output voltage from the transistor upon the detection of smoke.
Inventors
- 👤 K Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:18
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/62; G01N27/64; G01T; G01T7/00; G01T7/12; G01T7/125; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
128 words
An ionization smoke detector comprising at least one open ionization chamber including a pair of electrodes and a radioactive source, means for applying a voltage to said electrodes, a field effect transister having gate, drain and source electrodes, a connection between one of said chamber electrodes and said gate electrode, a plurality of series connected diodes forwardly inserted in series with said source electrode, means for applying a voltage to said source and drain electrodes through said series connected diodes, a connection between the other of said chamber electrodes and said series connected diodes, an output terminal and means for connecting said output terminal to selected junctions between said series connected diodes to vary the magnitude of said output signal upon the entrance of smoke into said chamber.
Claim 2
Dependent Claim
128 words
An ionization smoke detector comprising at least one open ionization chamber including a pair of electrodes and a radioactive source, means for applying a voltage to said electrodes, a field effect transister having gate, drain and source electrodes, a connection between one of said chamber electrodes and said gate electrode, a plurality of series connected diodes forwardly inserted in series with said source electrode, means for applying a voltage to said source and drain electrodes through said series connected diodes, a connection between the other of said chamber electrodes and said series connected diodes, an output terminal and means for connecting said output terminal to selected junctions between said series connected diodes to vary the magnitude of said output signal upon the entrance of smoke into said chamber.
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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |