US3733596A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alarm circuit
Assignee: TOKYO HACHIKI KK
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Filing: 1972-05-16
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Granted: 1973-05-15
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Expires: 1992-05-16
Abstract
Abstract An alarm system to detect combustion products such as smoke, gas and the like, has one or more alarm signal sending units and an alarm signal receiving unit interconnected by wiring to the sending units. Each alarm signal sending unit has a sensing or response element to detect the presence of vapors or smoke and the like and provide a signal; the sending unit also includes an amplifier non-continuously brought to its current-carrying state for amplifying an output signal of the response elements responding to a change of the surrounding physical condition. The alarm signal sending units are suitable for being connected in large numbers in parallel with a common alarm signal receiver unit, because the amplifier in each sending unit has a high impedance and dissipates low power. A smoke-sensing element of the ion type and necessitating no repeater is expediently included in the alarm signal sending device.
Inventors
- 👤 T Arima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:15
CPC Classifications
G; G01; G01T; G01T7/00; G01T7/12; G01T7/125; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
213 words
An alarm system for detecting smoke, vapor and physical conditions in an ambient region comprising in combination, an alarm signal sending unit, an alarm signal receiving unit, connecting means interconnecting said sending and receiving units with a power source, said alarm signal sending unit comprising: a sensing means featuring a changed impedance in response to a change in said physical conditions in the ambient region of said sensing means, said changed impedance providing an output signal; and amplifier means connected to amplify said output signal; a pulse switching means producing a continuous series of conducting intermittent pulses each pulse of said series of pulses lasting for a first interval of time which is substantially shorter than a second interval of time between successive of said pulses; means connecting said power source to said amplifier means through said pulse switching means to place said amplifier means intermittently in conductive state for short durations of time each of which equals said first interval of time; and a power switching means connected to receive an amplified output signal through said amplified means and establish flow of current through said alarm signal receiving unit to actuate an alarm, whereby the alarm system is responsive to signals from said sensing means only during said first intervals of time.
Claim 2
Dependent Claim
213 words
An alarm system for detecting smoke, vapor and physical conditions in an ambient region comprising in combination, an alarm signal sending unit, an alarm signal receiving unit, connecting means interconnecting said sending and receiving units with a power source, said alarm signal sending unit comprising: a sensing means featuring a changed impedance in response to a change in said physical conditions in the ambient region of said sensing means, said changed impedance providing an output signal; and amplifier means connected to amplify said output signal; a pulse switching means producing a continuous series of conducting intermittent pulses each pulse of said series of pulses lasting for a first interval of time which is substantially shorter than a second interval of time between successive of said pulses; means connecting said power source to said amplifier means through said pulse switching means to place said amplifier means intermittently in conductive state for short durations of time each of which equals said first interval of time; and a power switching means connected to receive an amplified output signal through said amplified means and establish flow of current through said alarm signal receiving unit to actuate an alarm, whereby the alarm system is responsive to signals from said sensing means only during said first intervals of time.
Claim 3
Dependent Claim
21 words
An alarm system as claimed in claim 1 wherein said pulse switching means comprises a switching element cyclically opening and closing.
Claim 4
Dependent Claim
42 words
An alarm system as claimed in claim 1 wherein said pulse switching means comprises a blocking oscillator, generating a pulse train output having a short ''''on'''' period and a comparatively long ''''off'''' period, and wherein said power switching means comprises a thyristor.
Claim 5
Dependent Claim
41 words
An alarm system as claimed in claim 1 wherein said pulse switching means comprises a multivibrator, generating a pulse train output having a short ''''on'''' period and a comparatively long ''''off'''' period, and wherein said power switching means comprises a thyristor.
Claim 6
Dependent Claim
50 words
An alarm system as claimed in claim 1 wherein said connecting means interconnecting said sending and receiving units with the power source comprises first and second lines, and wherein a resistor is included in series with said first line and a capacitor is connected across said first and second lines.
Claim 7
Dependent Claim
30 words
An alarm system as claimed in claim 5 which includes a Zener diode connected in parallel with said capacitor so as to supply said sensing means with a constant voltage.
Claim 8
Dependent Claim
20 words
An alarm system as claimed in claim 6 wherein said sensing means comprises two ion-type smoke detectors connected in series.
Claim 9
Dependent Claim
44 words
An alarm system as claimed in claim 7, wherein said amplifier means comprises a first transistor, and wherein a field effect transistor is connected at the base of said first transistor so as to be able to adjust the conductivity of said first transistor.
Claim 10
Dependent Claim
51 words
An alarm system as claimed in claim 8 wherein a source-electrode of said field effect transistor is connected to an output terminal of said pulse switching means and a gate electrode of said field effect transistor is connected to a junction point between said two ion-type smoke detectors connected in series.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |