EP0111012B1 - Ionization type of smoke sensor - Google Patents

Ionization type of smoke sensor Download PDF

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Publication number
EP0111012B1
EP0111012B1 EP83901734A EP83901734A EP0111012B1 EP 0111012 B1 EP0111012 B1 EP 0111012B1 EP 83901734 A EP83901734 A EP 83901734A EP 83901734 A EP83901734 A EP 83901734A EP 0111012 B1 EP0111012 B1 EP 0111012B1
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EP
European Patent Office
Prior art keywords
ionization
electrode
smoke
radioactive source
source
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EP83901734A
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German (de)
French (fr)
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EP0111012A4 (en
EP0111012A1 (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
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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 an ionization smoke detector with a single radioactive source according to the preamble of claim 1.
  • the ionization smoke detectors known to date can be divided into two categories: 1) smoke detectors with two radioactive sources and an outer measurement ionization chamber that is freely accessible to the smoke, and an inner comparison or reference ionization 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 which divides the two ionization chambers and which has a small passage. Opening contains for the irradiation of the outer ionization chamber by the radioactive source arranged in the inner ionization 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.
  • GB-A-2 013 393 describes such a smoke detector with a radioactive source for both ionization chambers.
  • the radioactive source is arranged in the inner ionization chamber and is exposed to contamination by the smoke particles entering the inner ionization chamber.
  • a cover plate was placed over it, which has an opening for the desired passage of the radioactive radiation for ionizing the inner and outer ionization chamber.
  • the size of the opening is a compromise between the desired ionization of the two chambers and the undesirable contamination of the radioactive source and can never be optimal. Either ionization and pollution are large or small at the same time. In no case is the ionization large and the pollution small. This did not solve the problem of preventing pollution.
  • US-A-3935466 shows a smoke detector with a radioactive source for both ionization chambers.
  • the radioactive source can be located within the inner or outer ionization chamber.
  • the size of the opening required for the passage of the ionization rays into both chambers is only dependent on the desired amount of the rays, since the influence of the contamination of the radioactive source on the sensitivity was not known.
  • the object of the invention is to provide an 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 back to its initial or normal state.
  • FIGS. 1 and 2 show an exemplary embodiment.
  • Figure 1 shows an ionization 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.
  • 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 disc-shaped inner electrode 6 is arranged on the annular wall 2.
  • a disc-like intermediate electrode 8 is provided which is supported by a plurality of webs 9 and in the middle of which an opening 10 is provided.
  • a 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 chamber a, b, specifically through the openings 7, 10, which are coaxial with the source 3. As a result, the air is ionized 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 at the tap of a change union resistor VR connected between terminals p and n.
  • the source electrode of the FET is on a 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 in it is in the saturation range.
  • the operation of the smoke detector is described below.
  • the dust-carrying air moves evenly into the ionization chambers a, b and out of the ionization chambers again, depending on 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 decreases. 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 ionization chambers a and b is quickly removed. 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 satisfactorily 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-source ionization smoke detector has several advantages over the prior art.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

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).

Description

Die vorliegende Erfindung bezieht sich auf einen lonisations-Rauchmelder mit einer einzigen radioaktiven Quelle gemäss Oberbegriff des Anspruches 1.The present invention relates to an ionization smoke detector with a single radioactive source according to the preamble of claim 1.

Die bisher bekannten lonisations-Rauchmelder können in zwei Kategorien eingeteilt werden : 1) in Rauchmelder mit zwei radioaktiven Quellen und einer äusseren, für den Rauch frei zugänglichen Mess-Ionisationskammer, sowie einer inneren, dem Rauch nicht zugänglichen Vergleichs-oder Bezugs-Ionisationskammer, wobei jede Kammer eine radioaktive Quelle aufweist, und 2) in Rauchmelder mit einer einzigen radioaktiven Quelle und einer die zwei Ionisationskammern teilenden Zwischenelektrode, die einen kleinen Durchlass bezw. Oeffnung enthält für die Bestrahlung der äusseren lonisationskammer durch die in der inneren lonisationskammer angeordneten radioaktiven Quelle. 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 Ionisationskammer zu gelangen. Der einmal in die äussere lonisationskammer eingedrungene Rauch kann nur schwierig entfernt werden, wodurch der Rauchmelder an der schnellen Rückkehr in seinen Anfangs- Bezw. Normal-Zustand gehindert wird. Zur Ueberwindung dieser Schweirigkeit wurden die Oeffnung bzw. der Durchlass in der Zwischenelektrode vergrössert und der in der inneren lonisationskammer fliessende lonisationsstrom in seinem Sättigungsbereich gehalten. Hierdurch bleibt der Widerstand der inneren lonisationskammer stabil und ist unabhängig vom Rauchfluss. Allerdings ist bei dieser Konstruktion die radioaktive Quelle in der inneren lonisationskammer stets der Atmosphäre und somit der Verschmutzung ausgesetzt, so dass der lonisationsstrom sich ändert. Dies führt zu unrichtiger Betriebsweise und zu Fehlalarmen.The ionization smoke detectors known to date can be divided into two categories: 1) smoke detectors with two radioactive sources and an outer measurement ionization chamber that is freely accessible to the smoke, and an inner comparison or reference ionization 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 which divides the two ionization chambers and which has a small passage. Opening contains for the irradiation of the outer ionization chamber by the radioactive source arranged in the inner ionization 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. However, operational tests of the single-source smoke detector have shown disadvantages that lie in its design. The smoke has great difficulty entering the inner ionization chamber through the small passage. Once the smoke has penetrated into the outer ionization chamber, it can only be removed with difficulty, causing the smoke detector to return quickly to its initial or Normal state is prevented. To overcome this difficulty, the opening or the passage in the intermediate electrode was enlarged and the ionization current flowing in the inner ionization chamber was kept in its saturation range. As a result, the resistance of the inner ionization chamber remains stable and is independent of the smoke flow. In this construction, however, 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.

In der GB-A-2 013 393 ist ein solcher Rauchmelder mit einer radioaktiven Quelle für beide lonisationskammern beschrieben. Die radioaktive Quelle ist in der inneren lonisationskammer angeordnet und der Verschmutzung durch die in die innere lonisationskammer eintretenden Rauchpartikel ausgesetzt. Um diese Verschmutzung der auf der inneren Elektrode befestigten radioaktiven Quelle zu verringern, wurde ein Abdeckblech über sie gelegt, welches eine Oeffnung für den gewünschten Durchtritt der radioaktiven Strahlung zur Ionisation der inneren und äusseren lonisationskammer hat. Die Grösse der Oeffnung ist ein Kompromiss zwischen der gewünschten Ionisation der beiden Kammern und der unerwünschten Verschmutzung der radioaktiven Quelle und kann nie optimal sein. Entweder sind Ionisation und Verschmutzung gleichzeitig gross oder klein. In keinem Fall sind die lonisation gross und die Verschmutzung klein. Das Problem der Verhinderung der Verschmutzung konnte hierdurch nicht gelöst werden.GB-A-2 013 393 describes such a smoke detector with a radioactive source for both ionization chambers. The radioactive source is arranged in the inner ionization chamber and is exposed to contamination by the smoke particles entering the inner ionization chamber. In order to reduce this contamination of the radioactive source attached to the inner electrode, a cover plate was placed over it, which has an opening for the desired passage of the radioactive radiation for ionizing the inner and outer ionization chamber. The size of the opening is a compromise between the desired ionization of the two chambers and the undesirable contamination of the radioactive source and can never be optimal. Either ionization and pollution are large or small at the same time. In no case is the ionization large and the pollution small. This did not solve the problem of preventing pollution.

Die US-A-3935466 zeigt einen Rauchdetektor mit einer radioaktiven Quelle für beide lonisationskammern. Die radioaktive Quelle kann innerhalb der inneren oder äusseren lonisationskammer angeordnet sein. Die Grösse der für den Durchtritt der lonisationsstrahlen in beide Kammern erforderlichen Oeffnung ist nur abhängig von der gewünschten Menge der Strahlen, da der Einfluss der Verschmutzung der radioaktiven Quelle auf die Empfindlichkeit nicht bekannt war.US-A-3935466 shows a smoke detector with a radioactive source for both ionization chambers. The radioactive source can be located within the inner or outer ionization chamber. The size of the opening required for the passage of the ionization rays into both chambers is only dependent on the desired amount of the rays, since the influence of the contamination of the radioactive source on the sensitivity was not known.

Daher hat die Erfindung die Aufgabe, einen lonisations-Rauchmelder mit einer einzigen radioaktiven Quelle zu schaffen, bei dem diese Verschmutzung der Quelle eliminiert 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 an 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 back to its initial or normal state.

Diese Aufgabe wird durch die Merkmale des kennzeichnenden Teiles des Anspruches 1 gelöst.This object is achieved by the features of the characterizing part of claim 1.

Im Folgenden wird die Erfindung anhand der Figuren 1 und 2 beschrieben, die ein Ausführungsbeispiel zeigen. Die Figur 1 zeigt einen lonisations-Rauchmelder im Querschnitt und Figur 2 zeigt den elektrischen Stromkreis für diesen Melder. In den Zeichnungen sind die innere lonisationskammer a, die äussere lonisationskammer b, Substrat 1, ringförmige Wand 2, radioaktive Quelle 3, Innenelektrode 6, Oeffnungen 7, 10, Zwischenelektrode 8, und die Aussenelektrode 11 dargestellt. Auf dem Substrat 1 ist eine ringförmige Wand 2 vorgesehen. Eine radioaktive Quelle 3 ist an einer Elektrode 5 angeordnet, deren vertikale Stellung mittels einer Schraube 4 einstellbar ist. Eine scheibenförmige Innenelektrode 6 ist an der ringförmigen Wand 2 angeordnet. Parallel zu der scheibenförmigen Innenelektrode 6 ist eine von mehreren 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 Ionisationskammer a wird von der Innenelektrode 6 and der Zwischenelektrode 8 gebildet. Die äussere lonisationskammer b wird von der Zwischenelektrode 8 und der Aussenelektrode 11 begrenzt. Die radioaktive Quelle 3 sendet ihre Strahlung in die lonisationskammer a, b, und zwar durch die Oeffnungen 7, 10, welche koaxial zur Quelle 3 liegen. Hierdurch erfolgt die lonisierung der Luft in den beiden Kammern a und b. Die Innenelektrode 6 ist 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 Schaltkreis SW, der zwischen den Klemmen p und n angeschlossen ist. Die innere Ionisationskammer a hat eine solche Spannung, dass der in ihr fliessende lonisationsstrom im Sättigungsbereich liegt.The invention is described below with reference to FIGS. 1 and 2, which show an exemplary embodiment. Figure 1 shows an ionization 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. 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 disc-shaped inner electrode 6 is arranged on the annular wall 2. In parallel to the disc-shaped inner electrode 6, a disc-like intermediate electrode 8 is provided which is supported by a plurality of webs 9 and in the middle of which an opening 10 is provided. A 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 chamber a, b, specifically through the openings 7, 10, which are coaxial with the source 3. As a result, the air is ionized 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 at the tap of a change union resistor VR connected between terminals p and n. The source electrode of the FET is on a 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 in it is in the saturation range.

Im Folgenden wird die Betriebsweise des Rauchmelders beschrieben. Im normalen Zustand bewegt sich die staubmitführende Luft gleichmässig in die lonisationskammern a, b und wieder aus den lonisationskammern und zwar entsprechend der im Raum vorherrschenden Luftströmung, in welchem der Rauchmelder installiert ist. Dies wird dadurch ermöglicht, 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 ionization chambers a, b and out of the ionization chambers again, depending on 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 Ionisationskammer b fliessende lonisationsstrom. 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 lonisationskammern a und b vorhandene Rauch schnell entfernt. Diese schnelle Entfernung des Rauchs geschieht durch die Luftzirkulation im Raum, weil die beiden lonisationskammern 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 veränderbaren Widerstandes VR wird das Potential der Zwischenelektrode 8 entsprechend geändert, sodass die Empfindlichkeit des Rauchmelders eingestellt werden kann.When smoke from a fire enters the smoke detector, the ionization current flowing in the outer ionization chamber b decreases. 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 ionization chambers a and b is quickly removed. 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 mounted by means of the variable resistor VR, the potential of the intermediate electrode 8 is changed accordingly, so that the sensitivity of the smoke detector can be adjusted.

Infolge der Konstruktion des erfindungsgemässen Rauchmelders, der in der eben beschriebenen Weise arbeitet, kann die radioaktive Quelle zufriedenstellend gegen Verschmutzung geschützt 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 lonisation-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 satisfactorily protected against contamination. 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-source ionization smoke detector has several advantages over the prior art.

Claims (3)

1. An ionization type smoke detector comprising a substrate (1) supporting an inner ionization chamber (a) defined by an inner electrode (6) and an intermediate electrode (8), an outer ionization chamber (b) defined by the intermediate electrode (8) and an outer electrode (11), a single radioactive source (3) for ionizing air present in both ionization chambers (a, b), whereby openings (7, 10) are provided in the inner electrode (6) and the intermediate electrode (8) to enter radioactive rays of the radioactive source (3) both ionization chambers (a, b), and the radioactive source (3) is provided outside of the inner ionization chamber (a), characterized in that the radioactive source (3) is arranged in an aperture, defined by the substrate (1) and the inner electrode (6), having a determined distance to the inner electrode (6) which distance is variable.
2. An ionization type smoke detector according claim 1, characterized in that the radioactive source (3) is fixed to a movable means (4, 5) for varying the distance between the source (3) and the inner electrode (6).
3. An ionization type smoke detector according claim 2, characterized in that the movable means (4, 5) consists of electric conducting material and is connected with an electronic circuit of the detector to adjust the potential of the movable means (4, 5).
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
JP83510/82U 1982-06-07
JP1982083510U JPS58186463U (en) 1982-06-07 1982-06-07 ionization smoke detector

Publications (3)

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

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EP83901734A Expired EP0111012B1 (en) 1982-06-07 1983-06-07 Ionization type of smoke sensor

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

Families Citing this family (7)

* 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
US4761557A (en) * 1985-08-24 1988-08-02 Kohmi Bosai Kogyo Co., Ltd. Ionization-type smoke detector
CA1267735A (en) * 1986-01-17 1990-04-10 Nohmi Bosai Kogyo Co., Ltd. Ionization type-smoke detector
FR2594953B1 (en) * 1986-02-25 1989-05-05 Lewiner Jacques SMOKE DETECTOR WITH IONIZATION CHAMBER
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

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1280304A (en) * 1968-09-26 1972-07-05 Hochiki Co A smoke sensing detector for smoke sensing apparatus
USRE30323E (en) * 1968-09-26 1980-07-01 Hochiki Kabushiki Kaisha Smoke detector adapted to a smoke sensing apparatus
GB2010578B (en) * 1977-11-18 1982-09-15 Radiochemical Centre Ltd Smoke detectors
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
GB2013393B (en) * 1977-11-18 1982-03-03 Radiochemical Centre Ltd 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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JPS58186463U (en) 1983-12-10
WO1983004449A1 (en) 1983-12-22
US4594512A (en) 1986-06-10
EP0111012A4 (en) 1984-12-11
JPH029430Y2 (en) 1990-03-08
EP0111012A1 (en) 1984-06-20
DE3380374D1 (en) 1989-09-14

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