EP0111012A1 - Ionization type of smoke sensor - Google Patents

Ionization type of smoke sensor Download PDF

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Publication number
EP0111012A1
EP0111012A1 EP83901734A EP83901734A EP0111012A1 EP 0111012 A1 EP0111012 A1 EP 0111012A1 EP 83901734 A EP83901734 A EP 83901734A EP 83901734 A EP83901734 A EP 83901734A EP 0111012 A1 EP0111012 A1 EP 0111012A1
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EP
European Patent Office
Prior art keywords
electrode
smoke
ionization
source
radioactive source
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Granted
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EP83901734A
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German (de)
French (fr)
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EP0111012A4 (en
EP0111012B1 (en
Inventor
Toru Nohmi Bosai Kogyo Co. Ltd. Sasaki
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Nohmi Bosai Ltd
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Nohmi Bosai Kogyo Co Ltd
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Publication of EP0111012A1 publication Critical patent/EP0111012A1/en
Publication of EP0111012A4 publication Critical patent/EP0111012A4/en
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    • 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
    • G08B17/113—Constructional details

Definitions

  • the present invention relates to a single radioactive source ionization smoke detector.
  • the previously known jonization smoke detectors can be divided into two categories: 1) in the smoke detector with two radioactive sources and an outer measurement jonification chamber that is freely accessible to the smoke, as well as an inner comparison or reference jonification chamber that is not accessible to the smoke, whereby each chamber has a radioactive source, and 2) in smoke detectors with a single radioactive source and an intermediate electrode dividing the two jonification chambers, which contains a small passage or opening, for the irradiation of the outer jonification chamber by the radioactive source arranged in the inner jonification chamber.
  • the smoke detector with a radioactive source has advantages over the two-source smoke detector because of its simple construction and its lower radiation energy requirement.
  • operational tests of the single-source smoke detector have shown disadvantages that lie in its construction.
  • the smoke has great difficulty in getting through the small passage into the inner ionization chamber. Once the smoke has entered the outer ionization chamber, it is difficult to remove it, which prevents the smoke detector from returning quickly to its initial or normal state.
  • the Oeff voltage or the passage in the intermediate electrode is increased and the ionization current flowing in the inner ionization chamber is kept in its saturation range.
  • the resistance of the inner ionization chamber remains stable and is independent of the smoke flow.
  • the radioactive source in the inner ionization chamber is always exposed to the atmosphere and thus to pollution, so that the ionization current changes. This leads to incorrect operation and false alarms.
  • the object of the invention is to provide a ionization smoke detector with a single radioactive source, in which this contamination of the source is eliminated and the smoke is quickly dispersed after the operational test has been completed. This quickly brings the smoke detector into its initial or normal state.
  • FIGS. 1 and 2 show an exemplary embodiment.
  • An annular wall 2 is provided on the substrate 1.
  • a radioactive source 3 is arranged on an electrode 5, the vertical position of which can be adjusted by means of a screw 4.
  • a disk-shaped inner electrode 6 is provided with a disk-like intermediate electrode 8 carried by several webs 9, in the middle of which an opening 10 is provided.
  • One. grid-shaped outer electrode 11 is attached to the substrate and surrounds the electrodes 6 and 8.
  • the inner ionization chamber a is formed by the inner electrode 6 and the intermediate electrode 8.
  • the outer ionization chamber b is delimited by the intermediate electrode 8 and the outer electrode 11.
  • the radioactive source 3 sends its radiation into the ionization chambers a, b through the. Openings 7, 10, which are coaxial to the source 3. This is the jonider
  • the inner electrode 6 is electrically connected to the positive terminal p and the outer electrode 11 to the negative terminal n of the detector.
  • the intermediate electrode 8 is connected to the gate electrode of an FET located between the terminals p, n and via a resistor R.
  • the electrode 5 is connected to the tap of a variable resistor VR, which lies between the terminals p and n.
  • the source electrode of the FET is located on a switching circuit SW, which is connected between the terminals p and n.
  • the inner ionization chamber a has such a voltage that the ionization current flowing into it lies in the saturation range.
  • the operation of the smoke detector is described below.
  • the dust-carrying air moves evenly into the jonification chambers a, b and again out of the jonification chambers, in accordance with the air flow prevailing in the room in which the smoke detector is installed.
  • This is made possible because the intermediate electrode 8 is only supported by a plurality of webs 9. Because the inner electrode 6 and the annular wall 2 cover the radioactive source 3, the source is protected from the air flow and remains in a clean state despite the opening 7 in the inner electrode 6.
  • the ionization current flowing in the outer ionization chamber b is reduced. This increases the gate potential of the FET that operates the fire alarm display circuit SW when it reaches a predetermined voltage.
  • a smoke generator supplies the necessary smoke to test the smoke detector. If the smoke generator is removed from the detector at the end of the test process, the smoke present in the ionization chambers a and b is quickly removed. The This rapid removal of the smoke takes place through the air circulation in the room, because the two ionization chambers are freely accessible to the air. The smoke detector is quickly returned to its normal working state at the end of the test.
  • the potential of the intermediate electrode 8 is changed accordingly, so that the sensitivity of the smoke detector can be adjusted.
  • the radioactive source can be adequately protected against contamination.
  • the smoke detector is quickly cleared of any smoke after the end of an operational test and is therefore returned to its initial or normal state within a short time.
  • This single radioactive jonization smoke detector has several advantages over the prior art.
  • Figure 1 shows a Jonisation smoke detector in cross section and Figure 2 shows the electrical circuit for this detector.
  • the inner ionization chamber a the outer ionization chamber b, substrate 1, annular wall 2, radioactive source 3, inner electrode 6, openings 7, 10, intermediate electrode 8, and the outer electrode 11 are shown.

Abstract

This relates to an ionization type of smoke sensor for a fire alarm, and in particular to an ionization type of smoke sensor in which an internal ion chamber (a) consists of an inner electrode (6) and an intermediate electrode (8), and an outer ion chamber (b) consists of the intermediate electrode (8) and an outer electrode (11), these chambers (a,b) ionizing the air within them by a radiation source (3). In the ionization smoke sensor of this type according to this invention, the radiation source is difficult to contaminate. When smoke is actually applied during an operating test, in order that the smoke can diffuse immediately after the test and the operation can recover readily, the source (3) is surrounded by the inner electrode (6), a substrate (1), and a ring wall (2), the intermediate electrode (8) is supported by a plurality of posts (9) extending from the substrate (1), and holes (7, 10) are formed in the electrodes (6) and (8) so that the radiation from the source (3) can be emitted through the holes (7, 10) to the chambers (a,b).This relates to an ionization type of smoke sensor for a fire alarm, and in particular to an ionization type of smoke sensor in which an internal ion chamber (a) consists of an inner electrode (6) and an intermediate electrode (8), and an outer ion chamber (b) consists of the intermediate electrode (8) and an outer electrode (11), these chambers (a, b) ionizing the air within them by a radiation source (3). In the ionization smoke sensor of this type according to this invention, the radiation source is difficult to contaminate. When smoke is actually applied during an operating test, in order that the smoke can diffuse immediately after the test and the operation can recover readily, the source (3) is surrounded by the inner electrode (6), a substrate (1), and a ring wall (2), the intermediate electrode (8) is supported by a plurality of posts (9) extending from the substrate (1), and holes (7, 10) are formed in the electrodes (6) and (8) so that the radiation from the source (3) can be emitted through the holes (7, 10) to the chambers (a, b).

Description

Die vorliegende Erfindung bezieht sich auf einen Jonisation-Rauchmelder mit einer einzigen radioaktiven Quelle.The present invention relates to a single radioactive source ionization smoke detector.

Die bisher bekannten Jonisation-Rauchmelder können in zwei Kategorien eingeteilt werden: 1) im Rauchmelder mit zwei radioaktiven Quellen und einer äusseren, für den Rauch frei zugänglichen Mess-Jonisationskammer, sowie einer inneren, dem Rauch nicht zugänglichen Vergleichs- oder Bezugs-Jonisationskammer, wobei jede Kammer eine radioaktive Quelle aufweist, und 2) in Rauchmelder mit einer einzigen radioaktiven Quelle und einer die zwei Jonisationskammer teilenden Zwischenelektrode, die einen kleinen Durchlass bzw. Oeffnung enthält, für die Bestrahlung der äusseren Jonisationskammer durch die in der inneren Jonisationskammer angeordnete radioaktive Quelle.The previously known jonization smoke detectors can be divided into two categories: 1) in the smoke detector with two radioactive sources and an outer measurement jonification chamber that is freely accessible to the smoke, as well as an inner comparison or reference jonification chamber that is not accessible to the smoke, whereby each chamber has a radioactive source, and 2) in smoke detectors with a single radioactive source and an intermediate electrode dividing the two jonification chambers, which contains a small passage or opening, for the irradiation of the outer jonification chamber by the radioactive source arranged in the inner jonification chamber.

Der Rauchmelder mit einer radioaktiven Quelle hat wegen seiner einfachen Konstruktion und seines geringeren Strahlungsenergie-Bedarfs Vorteile gegenüber dem Zwei-Quellen-Rauchmelder. Betriebstests des Ein-Quellen-Rauchmelders'ergaben jedoch Nachteile, die in seiner Konstruktion liegen. Der Rauch hat grosse Mühe, durch den kleinen Durchlass in die innere Jonisationskammer zu gelangen. Der einmal in die äussere Jonisationskammer eingedrungene Rauch kann nur schwierig entfernt werden, wodurch der Rauchmelder an der schnellen Rückkehr in seinen Anfangs- bzw. Normal-Zustand gehindert wird. Zur Ueberwindung dieser Schwierigkeit wurden die Oeffnung bzw. der Durchlass in der Zwischenelektrode vergrössert und der in der inneren.Jonisationskammer fliessende Jonisationsstrom in seinem Sättigungsbereich gehalten. Hierdurch bleibt der Widerstand der inneren Jonisationskammer stabil und ist unabhängig vom Rauchfluss. Allerdings ist bei dieser Konstruktion die radioaktive Quelle in der inneren Jonisationskammer stets der Atmosphäre und somit der Verschmutzung ausgesetzt-, sodass.der Jonisationsstrom sich ändert. Dies führt zu unrichtiger Betriebsweise und zu Fehlalarmen.The smoke detector with a radioactive source has advantages over the two-source smoke detector because of its simple construction and its lower radiation energy requirement. However, operational tests of the single-source smoke detector have shown disadvantages that lie in its construction. The smoke has great difficulty in getting through the small passage into the inner ionization chamber. Once the smoke has entered the outer ionization chamber, it is difficult to remove it, which prevents the smoke detector from returning quickly to its initial or normal state. To overcome this difficulty, the Oeff voltage or the passage in the intermediate electrode is increased and the ionization current flowing in the inner ionization chamber is kept in its saturation range. As a result, the resistance of the inner ionization chamber remains stable and is independent of the smoke flow. However, with this construction, the radioactive source in the inner ionization chamber is always exposed to the atmosphere and thus to pollution, so that the ionization current changes. This leads to incorrect operation and false alarms.

Daher hat die Erfindung die Aufgabe, einen Jonisation-Rauchmelder mit einer einzigen radioaktiven Quelle zu schaffen, bei dem diese Verschmutzung der Quelle eleminiert ist und der Rauch nach Vollendung des Betriebstests schnell zerstreut wird. Hierdurch wird der Rauchmelder schnell in seinen Anfang- bzw. Normal-Zustand gebracht.Therefore, the object of the invention is to provide a ionization smoke detector with a single radioactive source, in which this contamination of the source is eliminated and the smoke is quickly dispersed after the operational test has been completed. This quickly brings the smoke detector into its initial or normal state.

Im Folgenden wird die Erfindung anhand der Figuren 1 und 2 beschrieben, die ein Ausführungsbeispiel zeigen. Auf dem Substrat 1 ist eine ringförmige Wand 2 vorgesehen. Eine radioaktive Quelle 3 ist an einer Elektrode 5 angeordnet, dessen vertikale Stellung mittels einer Schraube 4 einstellbar ist. Eine scheibenförmige Innenelektrode 6 ist eine von mehrern Stegen 9 getragene scheibenartige Zwischenelektrode 8 vorgesehen, in deren Mitte eine Oeffnung 10 angebracht ist. Eine . gitterförmige Aussenelektrode 11 ist am Substrat angebracht und umgibt die Elektroden 6 und 8. Die innere Jonisationskammer a wird von der Innenelektrode 6 und der Zwischenelektrode 8 gebildet. Die äussere Jonisationskammer b wird von der Zwischenelektrode 8 und der Aussenelektrode 11 begrenzt. Die radioaktive Quelle 3 sendet ihre Strahlung in die Jonisationskammern a,b und zwar durch die. Oeffnungen 7,10, welche koaxial zur Quelle 3 liegen. Hierdurch erfolgt die JoniderThe invention is described below with reference to FIGS. 1 and 2, which show an exemplary embodiment. An annular wall 2 is provided on the substrate 1. A radioactive source 3 is arranged on an electrode 5, the vertical position of which can be adjusted by means of a screw 4. A disk-shaped inner electrode 6 is provided with a disk-like intermediate electrode 8 carried by several webs 9, in the middle of which an opening 10 is provided. One. grid-shaped outer electrode 11 is attached to the substrate and surrounds the electrodes 6 and 8. The inner ionization chamber a is formed by the inner electrode 6 and the intermediate electrode 8. The outer ionization chamber b is delimited by the intermediate electrode 8 and the outer electrode 11. The radioactive source 3 sends its radiation into the ionization chambers a, b through the. Openings 7, 10, which are coaxial to the source 3. This is the jonider

Luft in den beiden Kammern a und b. Die Innenelektrode 6 list elektrisch an der positiven Klemme p und die Aussenelektrode 11 an der negativen Klemme n des Melders angeschlossen. Die Zwischenelektrode 8 ist mit der Gate-Elektrode eines zwischen den Klemmen p, n und über einen Widerstand R liegenden FET verbunden. Die Elektrode 5 ist am Abgriff eines veränderlichen Widerstandes VR angeschlossen, der zwischen den Klemmen p und n liegt. Die Source-Elektrode des FET liegt an einem Schaltkries SW, der zwischen den Klemmen p und n angeschlossen ist. Die innere Jonisationskammer a hat eine solche Spannung, dass der in ihr fliessende Jonisationsstrom im Sättigungsbereich liegt.Air in the two chambers a and b. The inner electrode 6 is electrically connected to the positive terminal p and the outer electrode 11 to the negative terminal n of the detector. The intermediate electrode 8 is connected to the gate electrode of an FET located between the terminals p, n and via a resistor R. The electrode 5 is connected to the tap of a variable resistor VR, which lies between the terminals p and n. The source electrode of the FET is located on a switching circuit SW, which is connected between the terminals p and n. The inner ionization chamber a has such a voltage that the ionization current flowing into it lies in the saturation range.

Im Folgenden wird die Betriebsweise des Rauchmelders beschrieben. Im normalen Zustand bewegt sich die staubmitführende Luft gleichmässig in die Jonisationskammern a, b und wieder aus den Jonisationskammern und zwar entsprechend der im Raum vorherschenden Luftströmung, in welchem der Rauchmelder instralliert ist. Dies wird dadurch ermöglich, weil die Zwischenelektrode 8 nur von mehreren Stegen 9 getragen wird. Weil die Innenelektrode 6 und die ringförmige Wand 2 die radioaktive Quelle 3 abdecken, ist die Quelle vor dem Luftstrom geschützt und bleibt trotz der Oeffnung 7 in der Innenelektrode 6 in einem sauberen Zustand.The operation of the smoke detector is described below. In the normal state, the dust-carrying air moves evenly into the jonification chambers a, b and again out of the jonification chambers, in accordance with the air flow prevailing in the room in which the smoke detector is installed. This is made possible because the intermediate electrode 8 is only supported by a plurality of webs 9. Because the inner electrode 6 and the annular wall 2 cover the radioactive source 3, the source is protected from the air flow and remains in a clean state despite the opening 7 in the inner electrode 6.

Bei Eintritt von Rauch eines Feuers in den Rauchmelder vermindert sich der in der äusseren Jonisationskammer b fliessende Jonisationsstrom. Hierdurch erhöht sich das Gate-Potential des FET, das den Schaltkreis SW zur Feueralarm-Anzeige betätigt, wenn es eine vorbestimmte Spannung erreicht hat. Zum Testen des Rauchmelders liefert ein Raucherzeuger den notwendigen Rauch. Wenn am Ende des Testvorganges der Raucherzeuger vom Melder entfernt wird, wird der in den Jonisationskammern a und b vorhandene Rauch schnell entfernt. Diese schnelle Entfernung des Rauchs geschieht durch die Luftzirkulation im Raum, weil die beiden Jonisationskammern für die Luft frei zugänglich sind. Der Rauchmelder wird am Ende des Tests schnell in seinen normalen Arbeits-Zustand zurückgeführt. Durch ändern des Potentials der Elektrode 5, auf der die radioaktive Quelle angebracht ist, mittels des ver- . änderbaren Widerstandes VR wird das Potential der Zwischenelektrode 8 entsprechend geändert, sodass die Empfindlichkeit des Rauchmelders eingestellt werden kann.If smoke from a fire enters the smoke detector, the ionization current flowing in the outer ionization chamber b is reduced. This increases the gate potential of the FET that operates the fire alarm display circuit SW when it reaches a predetermined voltage. A smoke generator supplies the necessary smoke to test the smoke detector. If the smoke generator is removed from the detector at the end of the test process, the smoke present in the ionization chambers a and b is quickly removed. The This rapid removal of the smoke takes place through the air circulation in the room, because the two ionization chambers are freely accessible to the air. The smoke detector is quickly returned to its normal working state at the end of the test. By changing the potential of the electrode 5, on which the radioactive source is attached, by means of the ver. changeable resistance VR, the potential of the intermediate electrode 8 is changed accordingly, so that the sensitivity of the smoke detector can be adjusted.

Infolge der Konstrukton des erfindungsgemässen Rauchmelders, der in der eben beschriebenen Weise arbeitet, kann die radioaktive Quelle zufriedenstellend gegen Verschmutzung geschütz. werden. Ausserdem ist der Rauchmelder nach Beendigung eines Betriebstests schnell von jeglichem Rauch befreit und somit innerhalb kurzer Zeit in seinen Anfangs- bzw. Normal-Zustand geführt. Dieser Jonisation-Rauchmelder mit einer einzigen radioaktiven Quelle hat gegenüber dem Stand der Technik mehrere Vorteile.As a result of the construction of the smoke detector according to the invention, which operates in the manner just described, the radioactive source can be adequately protected against contamination. will. In addition, the smoke detector is quickly cleared of any smoke after the end of an operational test and is therefore returned to its initial or normal state within a short time. This single radioactive jonization smoke detector has several advantages over the prior art.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

Die Figur 1 zeigt einen Jonisation-Rauchmelder im Querschnitt und Figur 2 zeigt den elektrischen Stromkreis für diesen Melder. In den Zeichnungen sind die innere Jonisationskammer a, die äussere Jonisationskammer b, Substrat 1, ringförmiger Wand 2, radioaktive Quelle 3, Innenelektrode 6, Oeffnungen 7, 10, Zwischenelektrode 8, und die Aussenelektrode 11 dargestellt.Figure 1 shows a Jonisation smoke detector in cross section and Figure 2 shows the electrical circuit for this detector. In the drawings, the inner ionization chamber a, the outer ionization chamber b, substrate 1, annular wall 2, radioactive source 3, inner electrode 6, openings 7, 10, intermediate electrode 8, and the outer electrode 11 are shown.

Claims (2)

1. Jonisätion-Rauchmelder mit einer inneren Jonisationskammer (a), die durch eine Innenelektrode (6) und eine Zwischenelektrode (8) begrenzt ist, einer äusseren Jonisationskammer (b), die durch die Zwischenelektrode (8) und einer Aussenelektrode (11) begrenzt ist, und einer einzigen radioaktiven Quelle (3), die die Luft in beiden Jonisationskammern jonisiert, dadurch gekennzeichnet, dass die radioaktive Quelle (3) von der Innenelektrode (6) und einem Substrat (1) umschlossen ist, und die Innenelektrode (6) und Zwischenelektrode (8) Oeffnungen (7, 10) aufweisen, durch welche die radioaktive Quelle (3) die beiden Jonisationskammern bestranlt.1. Jonisätion smoke detector with an inner jonization chamber (a), which is delimited by an inner electrode (6) and an intermediate electrode (8), an outer jonification chamber (b), which is delimited by the intermediate electrode (8) and an outer electrode (11) and a single radioactive source (3) which ionizes the air in both jonization chambers, characterized in that the radioactive source (3) is enclosed by the inner electrode (6) and a substrate (1), and the inner electrode (6) and intermediate electrode (8) have openings (7, 10) through which the radioactive source (3) irradiates the two ionization chambers. 2. Jonisation-Rauchmelder nach Anspruch 1, dadurch gekennzeichnet, dass die radioaktive Quelle (3) an eine Elektrode (5) befestigt ist, deren Potential veränderbar ist.2. Jonisation smoke detector according to claim 1, characterized in that the radioactive source (3) is attached to an electrode (5) whose potential can be changed.
EP83901734A 1982-06-07 1983-06-07 Ionization type of smoke sensor Expired EP0111012B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1982083510U JPS58186463U (en) 1982-06-07 1982-06-07 ionization smoke detector
JP83510/82U 1982-06-07

Publications (3)

Publication Number Publication Date
EP0111012A1 true EP0111012A1 (en) 1984-06-20
EP0111012A4 EP0111012A4 (en) 1984-12-11
EP0111012B1 EP0111012B1 (en) 1989-08-09

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP83901734A Expired EP0111012B1 (en) 1982-06-07 1983-06-07 Ionization type of smoke sensor

Country Status (5)

Country Link
US (1) US4594512A (en)
EP (1) EP0111012B1 (en)
JP (1) JPS58186463U (en)
DE (1) DE3380374D1 (en)
WO (1) WO1983004449A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0217100A2 (en) * 1985-08-24 1987-04-08 Nohmi Bosai Ltd. An ionization-type smoke detector
FR2594953A1 (en) * 1986-02-25 1987-08-28 Lewiner Jacques SMOKE DETECTOR WITH IONIZATION CHAMBER

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6044194U (en) * 1983-09-05 1985-03-28 能美防災工業株式会社 Heat-resistant case for ionization smoke detector
CA1267735A (en) * 1986-01-17 1990-04-10 Nohmi Bosai Kogyo Co., Ltd. Ionization type-smoke detector
DE3921377A1 (en) * 1989-06-29 1991-01-03 Inotech Ag Wohlen DEVICE AND METHOD FOR MEASURING ELECTRONES
US5485144A (en) * 1993-05-07 1996-01-16 Pittway Corporation Compensated ionization sensor
US20030180591A1 (en) * 2001-03-29 2003-09-25 Steven Danyluk Contact potential difference ionization battery

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US3935466A (en) * 1968-09-26 1976-01-27 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
GB2010578A (en) * 1977-11-18 1979-06-27 Radiochemical Centre Ltd Smoke detectors
GB2013393A (en) * 1977-11-18 1979-08-08 Radiochemical Centre Ltd Smoke Detectors
USRE30323E (en) * 1968-09-26 1980-07-01 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus

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Publication number Priority date Publication date Assignee Title
CA1115860A (en) * 1977-11-18 1982-01-05 Dennis W.S. Smout Smoke detectors
CA1116319A (en) * 1977-11-18 1982-01-12 Jack Bryant Smoke detectors
JPS5821031Y2 (en) * 1978-03-15 1983-05-02 ホーチキ株式会社 Smoke detectors
JPS5759965Y2 (en) * 1978-04-25 1982-12-21

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935466A (en) * 1968-09-26 1976-01-27 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
USRE30323E (en) * 1968-09-26 1980-07-01 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
GB2010578A (en) * 1977-11-18 1979-06-27 Radiochemical Centre Ltd Smoke detectors
GB2013393A (en) * 1977-11-18 1979-08-08 Radiochemical Centre Ltd Smoke Detectors

Non-Patent Citations (1)

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Title
See also references of WO8304449A1 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0217100A2 (en) * 1985-08-24 1987-04-08 Nohmi Bosai Ltd. An ionization-type smoke detector
EP0217100A3 (en) * 1985-08-24 1988-02-10 Nohmi Bosai Kogyo Co., Ltd. An ionization-type smoke detector
FR2594953A1 (en) * 1986-02-25 1987-08-28 Lewiner Jacques SMOKE DETECTOR WITH IONIZATION CHAMBER
EP0236223A1 (en) * 1986-02-25 1987-09-09 Jacques Lewiner Ionization chamber smoke detector

Also Published As

Publication number Publication date
JPS58186463U (en) 1983-12-10
JPH029430Y2 (en) 1990-03-08
EP0111012A4 (en) 1984-12-11
WO1983004449A1 (en) 1983-12-22
EP0111012B1 (en) 1989-08-09
US4594512A (en) 1986-06-10
DE3380374D1 (en) 1989-09-14

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