US3775616A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Nittan Co Ltd
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Filing: 1971-05-10
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Granted: 1973-11-27
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Expires: 1991-05-10
Abstract
Abstract An ionization smoke detector having an open ionization chamber and a closed ionization chamber and each chamber includes a first electrode, at least two additional electrodes and a radioactive source. Corresponding additional electrodes of the chambers are interconnected while the first electrode of one chamber is connected to one terminal of a source of energy and the first electrode of the other chamber is connected to the other terminal of said source. A pair of field effect transistors have their bases individually connected to the junctions of each pair of connected additional electrodes and their source-drain paths including a load resistor connected between said source terminals. The voltage drop across each load resistor is then used to operate individual series connected switches.
Inventors
- 👤 H Tagashira
- 👤 K Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:27
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/62; G01N27/64; G01N27/66; G01T; G01T7/00; G01T7/12; G01T7/125; G08; G08B; G08B17/00; G08B17/10; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
214 words
An ionization smoke detector, comprising a closed ionization chamber which is closed to the external air and includes a first electrode, a second electrode and a radioactive source, an open ionization chamber which is opened to the external air and includes a first electrode, a second electrode and a radioactive source, a pair of terminals connected respectively to both of said first electrodes of said ionization chambers, the second electrode of both said ionization chambers being connected in common, a first field effect transistor having a gate electrode connected to the junction of the second electrodes of said both ionization chambers and a source-to-drain conduction path connected through a load resistor between said both terminals, said ionization chambers further including third electrodes, said third electrodes of said ionization chambers being connected in common, a second field effect transistor having a gate electrode connected to the junction of the third electrodes of said both ionization chambers and a source-to-drain conduction path connected through a load resistor between both said terminals, and first and second relay elements connected in series between said terminals, said relay elements each including control means, and individual connections between said control means and the source-drain paths of said first and second field effect transistors respectively for control of said relay elements.
Claim 2
Dependent Claim
214 words
An ionization smoke detector, comprising a closed ionization chamber which is closed to the external air and includes a first electrode, a second electrode and a radioactive source, an open ionization chamber which is opened to the external air and includes a first electrode, a second electrode and a radioactive source, a pair of terminals connected respectively to both of said first electrodes of said ionization chambers, the second electrode of both said ionization chambers being connected in common, a first field effect transistor having a gate electrode connected to the junction of the second electrodes of said both ionization chambers and a source-to-drain conduction path connected through a load resistor between said both terminals, said ionization chambers further including third electrodes, said third electrodes of said ionization chambers being connected in common, a second field effect transistor having a gate electrode connected to the junction of the third electrodes of said both ionization chambers and a source-to-drain conduction path connected through a load resistor between both said terminals, and first and second relay elements connected in series between said terminals, said relay elements each including control means, and individual connections between said control means and the source-drain paths of said first and second field effect transistors respectively for control of said relay elements.
Claim 3
Dependent Claim
47 words
An ionization smoke detector according to claim 1 including first and second zener diodes connected in series between said terminals and a connection between the junction of the series connected first and second relay elements and the junction of the series connected first and second zener diodes.
Claim 4
Dependent Claim
89 words
An ionization smoke detector according to claim 1 wherein said second and third electrodes constitute opposite surfaces of single insulated electrodes, means including said single electrodes enclosing the first electrode of said closed chamber, one of said radioactive sources being disposed in said closed chamber, means including the first electrode of said open chamber enclosing the last said means to form said open chamber with the other radioactive source disposed therein, and individual connections between each of said single insulated electrodes and the gates of said field effect transistors.
Claim 5
Dependent Claim
47 words
An ionization smoke detector according to claim 3 including first and second zener diodes connected in series between said terminals and a connection between the junction of the series connected first and second relay elements and the junction of the series connected first and second zener diodes.
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) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |