Patent US2734970A successfully refreshed from Google Patents.
Patent US5664011A successfully refreshed from Google Patents.
US4023152A
Expired / Lapsed
US
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Ionization type smoke sensing device
Assignee: Panasonic Electric Works Co Ltd
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Filing: 1975-04-28
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Granted: 1977-05-10
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Expires: 1995-04-28
Abstract
Abstract A smoke sensing device of the type having a single ionization chamber wherein stability and reliability are increased by driving the ionization chamber from a square wave oscillator, and utilizing an A.C. amplifier responsive to the ionization current within the chamber. The A.C. amplifier serves to amplify the current through the ionization chamber and couple the amplified current to a rectifier and detector adapted to respond to decreases in current, such as caused by smoke particles within the ionization chamber, to activate an alarm device.
Inventors
- 👤 Yoshihiko Okuda
- 👤 Tsunehiko Araki
- 👤 Shigeru Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:59
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
155 words
A smoke sensing device comprising in combination, a single ionization chamber including a pair of opposed electrodes exposed to the ambient atmosphere, a radioactive source associated with the electrodes and capable of ionizing the air between the electrodes, a load resistor coupling one of said electrodes to a reference potential, square wave oscillator means coupled to the other of said electrodes for causing a square wave ionization current to flow between said electrodes and through said load resistor, an A.C. amplifier coupled to the resistor for producing an alternating output signal proportional to said ionization current, a rectifier coupled to the amplifier for producing a direct voltage output signal which varies in accordance with the magnitude of said ionization current, and means coupled to the rectifier and responsive to said direct voltage output signal for switching to an alarm condition when said ionization current decreases due to the presence of smoke particles between the electrodes.
Claim 2
Dependent Claim
155 words
A smoke sensing device comprising in combination, a single ionization chamber including a pair of opposed electrodes exposed to the ambient atmosphere, a radioactive source associated with the electrodes and capable of ionizing the air between the electrodes, a load resistor coupling one of said electrodes to a reference potential, square wave oscillator means coupled to the other of said electrodes for causing a square wave ionization current to flow between said electrodes and through said load resistor, an A.C. amplifier coupled to the resistor for producing an alternating output signal proportional to said ionization current, a rectifier coupled to the amplifier for producing a direct voltage output signal which varies in accordance with the magnitude of said ionization current, and means coupled to the rectifier and responsive to said direct voltage output signal for switching to an alarm condition when said ionization current decreases due to the presence of smoke particles between the electrodes.
Claim 3
Dependent Claim
46 words
The smoke sensing device as set forth in claim 1 wherein the rectifier includes switch means driven by said oscillator to be on and off in synchronism with said square wave for synchronizing the operation of said rectifier with the square wave produced by said oscillator.
Claim 4
Dependent Claim
82 words
The smoke sensing device as set forth in claim 1 including a capacitor connected to the output of said amplifier, said rectifier comprising switch means connected to the capacitor and driven by the oscillator to be alternately conductive and non-conductive in synchronism with the square wave for charging said capacitor when conductive and for imposing the charge on said capacitor onto said means for switching to an alarm condition when non-conductive, thereby to synchronize operation of said rectifier with said square wave.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-09 | 1980-11-08 | 1981-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-09 | 1984-11-08 | 1985-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-09 | 1988-11-08 | 1989-05-10 | $7700.00 | Window Closed / Lapsed |