US3812362A - Smoke detector circuit - Google Patents

Smoke detector circuit Download PDF

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Publication number
US3812362A
US3812362A US00376011A US37601173A US3812362A US 3812362 A US3812362 A US 3812362A US 00376011 A US00376011 A US 00376011A US 37601173 A US37601173 A US 37601173A US 3812362 A US3812362 A US 3812362A
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US
United States
Prior art keywords
terminal
output
voltage
input terminal
electrode
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00376011A
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English (en)
Inventor
L Larsen
E Kobek
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honeywell Inc
Original Assignee
Honeywell Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honeywell Inc filed Critical Honeywell Inc
Priority to US00376011A priority Critical patent/US3812362A/en
Application granted granted Critical
Priority to CA200,342A priority patent/CA1015071A/en
Publication of US3812362A publication Critical patent/US3812362A/en
Priority to JP49062460A priority patent/JPS5829459B2/ja
Priority to GB2689774A priority patent/GB1439448A/en
Priority to DE2430809A priority patent/DE2430809C2/de
Priority to CH897574A priority patent/CH566603A5/xx
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T7/00—Details of radiation-measuring instruments
    • G01T7/12—Provision for actuation of an alarm
    • G01T7/125—Alarm- or controlling circuits using ionisation chambers, proportional counters or Geiger-Mueller tubes, also functioning as UV detectors
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas

Definitions

  • FIG. 1 of the drawing is a schematic representation of a preferred embodiment of the invention.
  • FIG. 2 is a variation of a portion of the circuit of FIG. 1.
  • FIG. 1 there is generally shown at an ionization smoke detector circuit having a plurality of output terminals which are wired to a common or central station 11.
  • the smoke detector circuit discloses a pair of series connected ionization chambers including a closed or nearly sealed reference chamber 12 and a smoke sensing chamber 13 which has louvers to allow a free exchange of air in and out of the chamber so that the appearance of products of combustion or smoke in the surrounding air is quickly sensed.
  • Reference chamber 12 has electrodes 14 and 15 and the sensing chamber 13 has electrodes 16 and 17.
  • the electrodes 14 and 17 are connected across the supply voltage on conductors 20 and 21, and the intermediate electrodes 15 and 16 are electrically connected together and provide an analogue signal output at conductor 22.
  • the impedance 12 has been specifically described as a reference chamber it is not a necessary part of the invention and may be in the form of any suitable resistor or impedance means.
  • the conductor 22 is connected to the gate G of a field effect transistor 23, which is shown as being an nchannel device of the junction-gate type connected in a source follower configuration.
  • the drain electrode D of PET 23 is directly connected to the positive supply conductor 20 and the source electrode S is connected by a junction 24 and a resistor 25 to the negative conductor 21.
  • the junction 24 is also connected by a resistor 26 to the input terminal 30 of a four-terminal comparator switching means 31.
  • the four-terminal comparator switching means 31 is shown as comprising a PNP and an NPN transistor in I a positive feedback configuration.
  • Input terminal 30 connects to the emitter electrode of the PNP transistor.
  • the PNP base electrode is directly connected to the NPN transistor collector electrode and to a reference terminal 32.
  • the PNP collector electrode is directly connected to the NPN transistor base electrode and to a third terminal 33.
  • the NPN transistor emitter electrode is directly connected to an output terminal 34 and terminal 34 is further connected through a resistor 35 to negative conductor 21.
  • the reference terminal 32 is directly connected to the adjustable wiper of a setpoint potentiometer 36.
  • Potentiometer 36 is part of a resistive voltage divider connected across supply conductors 20 and 21 and adjustment of the wiper permits a selection of a desired reference or set-point voltage at terminal 32.
  • the third terminal 33 is connected to the negative conductor 21 by a delay circuit comprising a capacitor 40 paralleled by a resistor 41.
  • Output terminal 34 of the comparator or threshold switching circuit 31 is directly connected to the input of a further transistor 42.
  • the collector load circuit for transistor 42 is a light emitting diode LED and a resistor 43.
  • An output terminal 5 is also connected to the collector electrode of transistor 42.
  • Several other exterior terminals of the ionization smoke detector circuit 10 are tied to various parts of the circuit just described, including terminal 1 which is connected by a resistor 44 to the electrode 17; terminal 2 connected to conductor 20; terminal 3 connected to terminal 32; terminal 6 connected to junction 24' and terminal 7 connected to conductor 21.
  • Terminals 2 and 7 are connected by conductors 50 and 51, respectively to a suitable source of DC potential in panel 11.
  • a relay coil or coils 52 may be in series with one of these conductors to sense changes in current magnitude as is well known in the art.
  • the switching output terminal 5 may be connected through an alarm relay coil 53 to the positive supply line.
  • the exterior terminal 6 may be connected to a voltmeter 54 to provide an indication of the analogue voltage at junction 24 with respect to the negative source lead 51 and in addition to indication this voltage may be used in a control system.
  • the exterior terminal 3 may be connected to a voltmeter 55 to provide an indication of the differential voltage between the set point voltage of point 32 and the analogue voltage at junction 24, or the meter 55 may have one terminal connected to conductor 51 to indicate the set point voltage.
  • a normally open Test switch in the central panel when operated, connects a positive potential to the exterior terminal 1 to cause the detector circuit 10 to go into alarm.
  • FIG. 2 shows a variation of a portion of the circuit of FIG. 1, namely that the four terminal comparator switching means 31 is shown in the form of a silicon controlled switch (SCS).
  • the anode is the input terminal 30
  • the anode gate is the reference terminal 32
  • the cathode gate is the third terminal 33
  • the cathode the output terminal 34 is shown in the form of a silicon controlled switch (SCS).
  • the effective impedance of the two chambers l2 and 13 is approximately the same and therefore about half of the supply potential on conductor 20 appears on conductor 22 to gate electrode G.
  • the F ET 23 is connected as a source follower circuit and conducts sufficient current so that the analogue voltage at junction 24 follows the analogue signal voltage at the gate.
  • the standby analogue voltage at junction 24 is coupled through resistor 26 to input electrode 30 of the comparator switch circuit 31.
  • the position of the wiper of set point potentiometer 36 adjusts the clean air operating differential voltage.
  • the position is selected to be higher in voltage than the standby voltage of terminal 30 so that the circuit 31 is non-conductive; thus there is no voltage at output terminal 34 and transistor 42 is also non-conductive.
  • the comparator switch 31 is stable, and due to the delay circuit connected toterminal 33 of switch 31, even the occurrence of a voltage transient tending to momentarily increase the potential of terminal 32, will not turn on switch 31.
  • the potentiometer 36 makes it possible to adjust the clean air operating differential as desired at any time during the life of the device, and it may be desirable at specific intervals of time over the years to check the differential and to adjust as necessary.
  • the potential at the gate electrode G increases above its clean air magnitude resulting in an increased potential at terminal 30.
  • the voltage magnitude is a function of the 1 density of smoke.
  • An analogue voltage exists at sensor 13, and this analogue voltage may be measured at exterior terminal 6 with respect to terminal 7, by a measuring and/or. control system which in most elementary form is shown as voltmeter 54.
  • the switch 31 begins to turn on.
  • a delay in the switching occurs as the delay network comprising capacitor 40 charges. This delay prevents transient voltages from turning on the switch.
  • a positive voltage developed across resistor 35 appears at output terminal 34 and biases on transistor 42.
  • the collector current flowing in transistor 42 turns on the LED indicator and also provides a low impedance path from output terminal tothe negative supply conductor 21.
  • the relay 53 in the common panel 11 is energized. Subsequent to the switching on of comparator switch 31, the supply potential on conductors and 21 remains substantially constant and the analogue voltage at terminal 24 continues to indicate the density of smoke at sensor 13.
  • the Test switch is closed applying a positive voltage through resistor 4410 electrode 17 thereby raising the potential at conductor 22.
  • the switch 56 in the positive supply conductor can be opened briefly to reset, or the exterior terminal 3 can be briefly connected to the positive conductor to reset switch 31.
  • the switch of FIG. 2 may be explained in the same manner as has been explained for FIG. 1.
  • an improved circuit for providing an analogue output signal voltage indicative of the sensed condition as well as providing a switched output indicative of the sensed condition exceeding a set point, the improved circuit comprising in combination;
  • first and second power input terminals to be energized from a dc. source
  • impedance means and an ionization sensing chamber 6 analogue output signal voltage indicative of the sensed condition exists at said signal terminal;
  • a four-terminal semiconductor switch having as terminals an input terminal, a reference terminal, a third terminal, and an output terminal, said switch switching from an off to an on condition when the voltage at the input terminal exceeds the voltage at the reference terminal;
  • said fourterminal semiconductor switch comprises two transistors, one an NPN transistor and the other a PNP transistor, the base electrode of the PNP transistor being directly connected to the collector electrode of the NPN transistor and also to said reference terminal, the base electrode of the NPN transistor being directly connected to the collector electrode of the PNP transistor and also to said third terminal, the emitter electrode of said PNP and NPN transistors comprising said input terminal and output terminal, respectively.
  • said fourterminal semiconductor switch is a four-terminal SCS (silicon controlled switch) having an anode, an anode gate, a cathode gate and a cathode as the input terminal, reference terminal, third terminal and output terminal, respectively.
  • SCS silicon controlled switch
  • said delay circuit means comprises a capacitor and resistive means in parallel connecting said third terminal to said second power input terminal.
  • circuit means connecting said analogue output signal voltage to an external connection point where it can be adapted for use in control and indication.
  • impedance means connecting one of the current carinput terminal, the gate electrode thereof being connected to said signal terminal, so that in operation an analogue output signal voltage indicative of the sensed condition exists at a terminal connected to said one current carrying electrode;
  • said four-terminal semiconductor switch having as terminals an input terminal, a reference terminal, a third terminal, and an output terminal in which said four-terminal switch comprises two transistors, one an NPN transistor and the other a PNP transistor, the base electrode of the PNP transistor being directly connected to the collector electrode of the NPN transistor and also to said reference terminal, the base electrode of the NPN transistor being directly connected to the collector electrode of the PNP transistor and also to said third terminal, the emitter electrode of said PNP and NPN transistors comprising said input terminal and output terminal, respectively, said switching means switching from an off to an on condition when the voltage at the input terminal exceeds the voltage at the reference terminal;
  • a source of adjustable set-point voltage connected to said reference terminal and to an output signal terminal for providing an analogue output signal voltage indicative of the set-point
  • resistive means connecting the input terminal to said one current carrying electrode

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Management (AREA)
  • Business, Economics & Management (AREA)
  • Analytical Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Fire Alarms (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US00376011A 1973-06-22 1973-07-02 Smoke detector circuit Expired - Lifetime US3812362A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US00376011A US3812362A (en) 1973-07-02 1973-07-02 Smoke detector circuit
CA200,342A CA1015071A (en) 1973-07-02 1974-05-21 Ionization smoke detector circuit
JP49062460A JPS5829459B2 (ja) 1973-06-22 1974-06-01 イオンシキケムリカンチキ
GB2689774A GB1439448A (en) 1973-06-22 1974-06-18 Ionization smoke detector
DE2430809A DE2430809C2 (de) 1973-07-02 1974-06-27 Ionisations-Feuermelder
CH897574A CH566603A5 (de) 1973-07-02 1974-07-01

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00376011A US3812362A (en) 1973-07-02 1973-07-02 Smoke detector circuit

Publications (1)

Publication Number Publication Date
US3812362A true US3812362A (en) 1974-05-21

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00376011A Expired - Lifetime US3812362A (en) 1973-06-22 1973-07-02 Smoke detector circuit

Country Status (4)

Country Link
US (1) US3812362A (de)
CA (1) CA1015071A (de)
CH (1) CH566603A5 (de)
DE (1) DE2430809C2 (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4148022A (en) * 1977-04-28 1979-04-03 Honeywell Inc. Chemical smoke or pollutant detector
US4238677A (en) * 1977-04-08 1980-12-09 Societe Gamma-Electronic Smoke detector by ionization associated to a velocimetric measurement electronic circuit
US4238788A (en) * 1978-01-03 1980-12-09 Teledyne Industries, Inc. System for detecting a combustion process
USRE30620E (en) * 1978-07-03 1981-05-19 P. R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4401979A (en) * 1981-02-11 1983-08-30 General Signal Corporation Electrical controls for ionization smoke detector
US4456907A (en) * 1981-01-12 1984-06-26 Pyrotector, Inc. Ionization type smoke detector with test circuit
US4469947A (en) * 1981-04-15 1984-09-04 Commissariat A L'energie Atomique X-Ray detector with compensating secondary chamber
US20030201901A1 (en) * 2002-04-24 2003-10-30 Administrator Of The National Aeronautics And Space Administration Marking electrical wiring with condition indicators
US20030200786A1 (en) * 2002-04-24 2003-10-30 U.S.A. As Represented By The Administrator Of The National Aeronautics And Space Administration Method for anticipating problems with electrical wiring
CN115158381A (zh) * 2022-07-11 2022-10-11 石家庄国祥运输设备有限公司 用于轨道车辆空调机组的烟雾探测控制电路及控制方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2713280C3 (de) * 1977-03-25 1986-10-23 Esser Sicherheitstechnik GmbH & Co KG, 4040 Neuss Funktionsüberprüfbare Feuermelderanlage

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1576497A (de) * 1968-05-07 1969-08-01
NL7010779A (de) * 1969-07-24 1971-01-26

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4238677A (en) * 1977-04-08 1980-12-09 Societe Gamma-Electronic Smoke detector by ionization associated to a velocimetric measurement electronic circuit
US4148022A (en) * 1977-04-28 1979-04-03 Honeywell Inc. Chemical smoke or pollutant detector
US4238788A (en) * 1978-01-03 1980-12-09 Teledyne Industries, Inc. System for detecting a combustion process
USRE30620E (en) * 1978-07-03 1981-05-19 P. R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4456907A (en) * 1981-01-12 1984-06-26 Pyrotector, Inc. Ionization type smoke detector with test circuit
US4401979A (en) * 1981-02-11 1983-08-30 General Signal Corporation Electrical controls for ionization smoke detector
US4469947A (en) * 1981-04-15 1984-09-04 Commissariat A L'energie Atomique X-Ray detector with compensating secondary chamber
US20030201901A1 (en) * 2002-04-24 2003-10-30 Administrator Of The National Aeronautics And Space Administration Marking electrical wiring with condition indicators
US20030200786A1 (en) * 2002-04-24 2003-10-30 U.S.A. As Represented By The Administrator Of The National Aeronautics And Space Administration Method for anticipating problems with electrical wiring
US6838995B2 (en) 2002-04-24 2005-01-04 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method for anticipating problems with electrical wiring
US6985083B2 (en) 2002-04-24 2006-01-10 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Marking electrical wiring with condition indicators
CN115158381A (zh) * 2022-07-11 2022-10-11 石家庄国祥运输设备有限公司 用于轨道车辆空调机组的烟雾探测控制电路及控制方法
CN115158381B (zh) * 2022-07-11 2024-04-26 石家庄国祥运输设备有限公司 用于轨道车辆空调机组的烟雾探测控制电路及控制方法

Also Published As

Publication number Publication date
CH566603A5 (de) 1975-09-15
DE2430809A1 (de) 1975-01-23
CA1015071A (en) 1977-08-02
DE2430809C2 (de) 1984-09-27

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