EP0122433A1 - Residential fire alarm system - Google Patents

Residential fire alarm system Download PDF

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Publication number
EP0122433A1
EP0122433A1 EP84102466A EP84102466A EP0122433A1 EP 0122433 A1 EP0122433 A1 EP 0122433A1 EP 84102466 A EP84102466 A EP 84102466A EP 84102466 A EP84102466 A EP 84102466A EP 0122433 A1 EP0122433 A1 EP 0122433A1
Authority
EP
European Patent Office
Prior art keywords
detector
fire
sensitivity
alarm system
fire alarm
Prior art date
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.)
Withdrawn
Application number
EP84102466A
Other languages
German (de)
French (fr)
Inventor
Shoichi C/O Nohmi Bosai Kogyo Co. Ltd. Kimura
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.)
Nohmi Bosai Ltd
Original Assignee
Nohmi Bosai Kogyo Co Ltd
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 Nohmi Bosai Kogyo Co Ltd filed Critical Nohmi Bosai Kogyo Co Ltd
Publication of EP0122433A1 publication Critical patent/EP0122433A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • 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

  • This invention relates to a fire alarm system for residential use.
  • sensitivities of fire detectors have been set to comparatively low levels to avoid that they will produce false alarms with cigarette smoke or heat from heating appliances and to permit their wide application.
  • the fire detectors With low sensitivities it is possible to build a reliable fire alarm system which does not produce an alarm with such a rise in ambient temperature as caused by room heating or with cigarette smoke.
  • an alarm is given only at an advanced stage of the fire. Therefore, for protection of general houses built with wood, it is preferable that the fire detectors have the highest possible sensitivity setting.
  • this invention is to offer a fire alarm system having a high sensitivity but less possibility of producing a false alarm, which is achieved by adjusting the sensitivities of the fire detectors to the ambient condition each time a fire is handled in lieu of the conventional thought of permanently fixing the sensitivities of the fire detectors.
  • the ionization type smoke detector 1 consists of outer ionization chamber 3; inner ionization chamber 4; FET 5 with its gate connected to the junction of the ionization chambers 3, 4, and its source equipped with bleeder resistors 6, 7 to determine a point at which the FET 5 becomes conductive, in other words the sensitivity of the detector; and a switching circuit 12 comprising resistors 8, 9, capacitor 10 and transistor 11.
  • the control panel 2 consists of power supply 13 for the detector 1 and control panel 2; push button switch 14 which is pressed when adjusting the sensitivity; timer 15 which is connected in series with the push button switch 14 and is capable of adjusting the set time; alarm relay 16 actuated as the switching circuit of the detector 1 switches on; self-holding contact 16-1 of the relay 16 connected in series with break contact 15 - 1 of the timer 15; alarm bell 17 connected in series with make contact 16 - 2 of the relay 16; and variable resistor 18 for sensitivity adjustment connected in series with make contact 15 - 2 of the timer 15 as sensitivity setting circuit, and between the source of the field effect transistor 5 of the detector 1 and plus terminal of the power supply 13.
  • the FET 5 becomes non-conductive, thus the sensitivity of the detector 1 is set to a highest possible level at which the detector 1 can remain unoperated under the condition that the range is being used.
  • the FET 5 immediately becomes conductive, causing the realy 16 to operate through the switching circuit 12 and the bell 17 to sound for alarm.
  • the make contact 15 - 2 opens due to action of the timer 15, and the sensitivity of the detector 1 returns to the fixed value determined by resistors 6, 7.
  • the detector is now set to a low sensitivity and continue surveillance of comparatively safe kitchen where no fire is being used after kitchen work.
  • the detector In the case of the fire alarm system installed in a living room, surveillance is normally made by the detector with low sensitivity which is determined by resistors 6, 7 and at which the detector is not actuated by cigarette smoke or heat from the heating appliance.
  • the detector When a housewife goes to kitchen, leaving her baby alone in the living room without putting off the heating appliance, the detector should be set to a high sensitivity under the condition that the heating appliance is in use as described for the case that the range is used in the kitchen.
  • the detector 1 even if the heating appliance is accidentally thrown down by baby and a fire occurs, the detector 1 immediately operates in the incipient stage of the fire and notifies her mother in the next room of the danger.
  • this invention offers a fire alarm system which does not produce an alarm even if soiling of the detector has changed the sensitivity because the sensitivity adjustment is made each time fire is used, and which is) capable of giving an alarm in the incipient stage of fire.
  • the drawing is a circuit diagram of an embodiment of the fire alarm system according to this invention.

Abstract

This invention relates to a fire alarm system in which sensitivities of detectors can be adjusted to the ambient conditions under which they are used, and which thus has a high sensitivity but less possibility of producing false alarm.

Description

  • This invention relates to a fire alarm system for residential use. Up to now, sensitivities of fire detectors have been set to comparatively low levels to avoid that they will produce false alarms with cigarette smoke or heat from heating appliances and to permit their wide application. 'By the use of the fire detectors with low sensitivities it is possible to build a reliable fire alarm system which does not produce an alarm with such a rise in ambient temperature as caused by room heating or with cigarette smoke. Conversely, in case of actual fire, an alarm is given only at an advanced stage of the fire. Therefore, for protection of general houses built with wood, it is preferable that the fire detectors have the highest possible sensitivity setting.
  • In view of the above, this invention is to offer a fire alarm system having a high sensitivity but less possibility of producing a false alarm, which is achieved by adjusting the sensitivities of the fire detectors to the ambient condition each time a fire is handled in lieu of the conventional thought of permanently fixing the sensitivities of the fire detectors.
  • The following describes an embodiment according to this invention with reference to a circuit diagram. Shown in the figure are an ionization type smoke detector 1 which is -installed, -for -example, -on the ceiling of the kitchen, and a control panel 2 installed on the wall nearby. The ionization type smoke detector 1 consists of outer ionization chamber 3; inner ionization chamber 4; FET 5 with its gate connected to the junction of the ionization chambers 3, 4, and its source equipped with bleeder resistors 6, 7 to determine a point at which the FET 5 becomes conductive, in other words the sensitivity of the detector; and a switching circuit 12 comprising resistors 8, 9, capacitor 10 and transistor 11. The control panel 2 consists of power supply 13 for the detector 1 and control panel 2; push button switch 14 which is pressed when adjusting the sensitivity; timer 15 which is connected in series with the push button switch 14 and is capable of adjusting the set time; alarm relay 16 actuated as the switching circuit of the detector 1 switches on; self-holding contact 16-1 of the relay 16 connected in series with break contact 15 - 1 of the timer 15; alarm bell 17 connected in series with make contact 16 - 2 of the relay 16; and variable resistor 18 for sensitivity adjustment connected in series with make contact 15 - 2 of the timer 15 as sensitivity setting circuit, and between the source of the field effect transistor 5 of the detector 1 and plus terminal of the power supply 13.
  • Operation of this fire alarm system is-described below. When fire is used in the kitchen such as use of a' gas range, the timer 15 on the control panel 2 is set to the time corresponding to the length of time that the gas range is in actual use with pans on, and the push button switch 14 is pressed. Then, the timer 15 is actuated to open its break contact 15 - 1, and the make contact 15 - 2 in the sensitivity setting circuit is closed. By adjusting the variable resistor 18, the sensitivity of the detector, i.e. the source potential of the FET 5 is raised until the FET 5 becomes conductive to operate the bell 17 through the relay 16. Now, the variable resistor 18 is reset until the bell 17 is silenced, i.e. the FET 5 becomes non-conductive, thus the sensitivity of the detector 1 is set to a highest possible level at which the detector 1 can remain unoperated under the condition that the range is being used. In this state, if oil in the pan ignites, even small amount of smoke entering the ionization chamber 3 causes the gate potential of the FET 5 to fall below the source potential. Thus, the FET 5 immediately becomes conductive, causing the realy 16 to operate through the switching circuit 12 and the bell 17 to sound for alarm. After lapse of a predetermined time without such an accident, the make contact 15 - 2 opens due to action of the timer 15, and the sensitivity of the detector 1 returns to the fixed value determined by resistors 6, 7. The detector is now set to a low sensitivity and continue surveillance of comparatively safe kitchen where no fire is being used after kitchen work.
  • In the case of the fire alarm system installed in a living room, surveillance is normally made by the detector with low sensitivity which is determined by resistors 6, 7 and at which the detector is not actuated by cigarette smoke or heat from the heating appliance. When a housewife goes to kitchen, leaving her baby alone in the living room without putting off the heating appliance, the detector should be set to a high sensitivity under the condition that the heating appliance is in use as described for the case that the range is used in the kitchen. Thus, even if the heating appliance is accidentally thrown down by baby and a fire occurs, the detector 1 immediately operates in the incipient stage of the fire and notifies her mother in the next room of the danger.
  • While the above has described the embodiment using an ionization type smoke detector, it is possible to provide photoelectric type ' smoke detectors, thermal detectors or gas sensors with similar sensitivity setting circuits, too.
  • With the above described composition and function this invention offers a fire alarm system which does not produce an alarm even if soiling of the detector has changed the sensitivity because the sensitivity adjustment is made each time fire is used, and which is) capable of giving an alarm in the incipient stage of fire.
    • 4. Brief Description of Drawing
  • The drawing is a circuit diagram of an embodiment of the fire alarm system according to this invention.
    • 1 ..................... Ionization smoke detector
    • 2 ..................... Control panel
    • 3 ..................... Outer ionization chamber
    • 4 ..................... Inner ionization chamber
    • 5 ..... FET
    • 6, 7, 8, 9 ..... Resistors
    • 10 ..... Capacitor
    • 11 .................... Transistor
    • 12 .................... Switching circuit
    • 13 .................... Power supply
    • 14 .................... Push button switch
    • 15 .................... Timer
    • 16 .................... Relay
    • 17 .................... Bell
    • 18 ..... Variable resistor

Claims (2)

1. A residential fire alarm system which is installed in the ordinary house or apartment house and which is characterized in that a sensitivity setting circuit is provided in the fire detector or the contro panel to adjust the sensitivity of the detector to the highest possib. value at which the detector will not operate when a fire is used.
2. A residential fire alarm system as set forth in Claim 1 wherin the sensitivity setting circuit is provided with a timer to reset the fire detector to the fixed sensitivity in a predetermined time.
EP84102466A 1983-03-23 1984-03-08 Residential fire alarm system Withdrawn EP0122433A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP4711983A JPS59173898A (en) 1983-03-23 1983-03-23 Fire alarm for home use
JP47119/83 1983-03-23

Publications (1)

Publication Number Publication Date
EP0122433A1 true EP0122433A1 (en) 1984-10-24

Family

ID=12766269

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84102466A Withdrawn EP0122433A1 (en) 1983-03-23 1984-03-08 Residential fire alarm system

Country Status (2)

Country Link
EP (1) EP0122433A1 (en)
JP (1) JPS59173898A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0345798A1 (en) * 1988-06-10 1989-12-13 Cerberus Ag Fire alarm system
FR2640384A1 (en) * 1988-12-13 1990-06-15 Morrison Co Ets IONIZATION COMBUSTION GAS DETECTOR
FR2689280A1 (en) * 1992-03-30 1993-10-01 Pittway Corp Alarm silencing circuit for photoelectric smoke detector.
AU652097B2 (en) * 1992-05-25 1994-08-11 Nohmi Bosai Ltd Ionization type smoke detector
AU654438B2 (en) * 1992-05-25 1994-11-03 Nohmi Bosai Ltd Fire detector
WO2007009153A1 (en) * 2005-07-18 2007-01-25 Gilbert Alain Garrick Method of facilitating access to operator functions of hazardous condition alarm devices
WO2023192498A1 (en) * 2022-03-30 2023-10-05 Johnson Controls Tyco IP Holdings LLP Dynamic control of detector sensitivity in fire alarm control systems

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6356797A (en) * 1986-08-27 1988-03-11 株式会社竹中工務店 Sensitivity setting system for fire sensor
JP2583529Y2 (en) * 1991-03-05 1998-10-22 ニッタン株式会社 Fire detector
JP4549494B2 (en) * 2000-06-14 2010-09-22 ホーチキ株式会社 Flame detection device and detection sensitivity setting method thereof
JP5164282B2 (en) * 2010-04-28 2013-03-21 ホーチキ株式会社 Flame detection device and detection sensitivity setting method thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2530848A1 (en) * 1974-07-20 1976-02-05 Nohmi Bosai Kogyo Co Ltd Electronic fire detection circuit - avoids false alarms by monitoring waveform shape of detected parameters over suitable period
DE2454196B2 (en) * 1974-06-14 1980-02-21 Cerberus Ag, Maennedorf, Zuerich (Schweiz) Fire alarm
US4313110A (en) * 1980-02-19 1982-01-26 Thomas Subulak Smoke alarm having temporary disabling features

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50123299A (en) * 1974-03-15 1975-09-27
US3952145A (en) * 1974-11-12 1976-04-20 Rca Corporation Pickup arm cartridge apparatus
JPS56132690A (en) * 1980-03-19 1981-10-17 Hochiki Co Fire detector
JPS5737272U (en) * 1980-08-11 1982-02-27
JPS57141791A (en) * 1981-02-27 1982-09-02 Mitsubishi Electric Corp Malfunctioning preventor for fire sensor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2454196B2 (en) * 1974-06-14 1980-02-21 Cerberus Ag, Maennedorf, Zuerich (Schweiz) Fire alarm
DE2530848A1 (en) * 1974-07-20 1976-02-05 Nohmi Bosai Kogyo Co Ltd Electronic fire detection circuit - avoids false alarms by monitoring waveform shape of detected parameters over suitable period
US4313110A (en) * 1980-02-19 1982-01-26 Thomas Subulak Smoke alarm having temporary disabling features

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0345798A1 (en) * 1988-06-10 1989-12-13 Cerberus Ag Fire alarm system
US4975684A (en) * 1988-06-10 1990-12-04 Cerberus Ag Fire detecting system
FR2640384A1 (en) * 1988-12-13 1990-06-15 Morrison Co Ets IONIZATION COMBUSTION GAS DETECTOR
WO1990007169A1 (en) * 1988-12-13 1990-06-28 Etablissements Morrison & Co Ionization-type combustion gas detector
FR2689280A1 (en) * 1992-03-30 1993-10-01 Pittway Corp Alarm silencing circuit for photoelectric smoke detector.
AU652097B2 (en) * 1992-05-25 1994-08-11 Nohmi Bosai Ltd Ionization type smoke detector
AU654438B2 (en) * 1992-05-25 1994-11-03 Nohmi Bosai Ltd Fire detector
WO2007009153A1 (en) * 2005-07-18 2007-01-25 Gilbert Alain Garrick Method of facilitating access to operator functions of hazardous condition alarm devices
WO2023192498A1 (en) * 2022-03-30 2023-10-05 Johnson Controls Tyco IP Holdings LLP Dynamic control of detector sensitivity in fire alarm control systems

Also Published As

Publication number Publication date
JPS59173898A (en) 1984-10-02

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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17P Request for examination filed

Effective date: 19840308

AK Designated contracting states

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STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19850725

RIN1 Information on inventor provided before grant (corrected)

Inventor name: KIMURA, SHOICHIC/O NOHMI BOSAI KOGYO CO., LTD.