US3693009A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detecting device
Assignee: Nittan Co Ltd
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Filing: 1971-04-13
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Granted: 1972-09-19
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Expires: 1991-04-13
Abstract
Abstract An ionization smoke detector having a single ionization chamber, a pair of spaced electrodes in said chamber, a grid electrode between said spaced electrodes and a radioactive source within the chamber. A potential is applied between the spaced electrodes and means are connected between one of the spaced electrodes and the grid electrode to detect potential changes in the grid produced by the presence of smoke.
Inventors
- 👤 Koju Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:14
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/62; G01N27/64; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
136 words
An ionization smoke detecting device comprising a pair of spaced electrodes having means for applying a DC potential therebetween, means supporting said electrodes to permit the movement of ambient air therebetween, a Potential sensing grid disposed between said spaced electrodes, a radioactive source positioned in the vicinity of one of said electrodes, said DC potential and radioactive source producing a substantially linear voltage gradient between said electrodes, a voltage amplifier having an input and output, means connecting one of said spaced electrodes and said grid to the input of said amplifier and indicating means connected to the output thereof, said amplifier being responsive to voltage changes between said one electrode and said grid produced by the production of a nonlinear voltage gradient between said electrodes upon the entry of smoke therebetween and actuating said indicating means.
Claim 2
Dependent Claim
136 words
An ionization smoke detecting device comprising a pair of spaced electrodes having means for applying a DC potential therebetween, means supporting said electrodes to permit the movement of ambient air therebetween, a Potential sensing grid disposed between said spaced electrodes, a radioactive source positioned in the vicinity of one of said electrodes, said DC potential and radioactive source producing a substantially linear voltage gradient between said electrodes, a voltage amplifier having an input and output, means connecting one of said spaced electrodes and said grid to the input of said amplifier and indicating means connected to the output thereof, said amplifier being responsive to voltage changes between said one electrode and said grid produced by the production of a nonlinear voltage gradient between said electrodes upon the entry of smoke therebetween and actuating said indicating means.
References Cited (Backward Citations)
US3448261A
Cited
US3560737A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-19 | 1976-03-20 | 1976-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-19 | 1980-03-20 | 1980-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-19 | 1984-03-20 | 1984-09-19 | $7700.00 | Window Closed / Lapsed |