EP0020674B1 - Smoke detector operating with scattered radiation - Google Patents

Smoke detector operating with scattered radiation Download PDF

Info

Publication number
EP0020674B1
EP0020674B1 EP80900014A EP80900014A EP0020674B1 EP 0020674 B1 EP0020674 B1 EP 0020674B1 EP 80900014 A EP80900014 A EP 80900014A EP 80900014 A EP80900014 A EP 80900014A EP 0020674 B1 EP0020674 B1 EP 0020674B1
Authority
EP
European Patent Office
Prior art keywords
radiation
webs
smoke detector
receiver
region
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.)
Expired
Application number
EP80900014A
Other languages
German (de)
French (fr)
Other versions
EP0020674A1 (en
Inventor
Zoltan Horvath
Jürg Muggli
Hans Ackermann
Erwin Tresch
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.)
Cerberus AG
Original Assignee
Cerberus AG
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
Priority claimed from CH1300178A external-priority patent/CH634429A5/en
Priority claimed from CH1300078A external-priority patent/CH634428A5/en
Priority to AT80900014T priority Critical patent/ATE3597T1/en
Application filed by Cerberus AG filed Critical Cerberus AG
Publication of EP0020674A1 publication Critical patent/EP0020674A1/en
Application granted granted Critical
Publication of EP0020674B1 publication Critical patent/EP0020674B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • 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
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
    • 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 invention relates to a smoke detector which works with scattered radiation and has a radiation source which emits radiation in a cone-shaped radiation region which opens vertically downwards, and a radiation receiver which is arranged outside the direct radiation region in the cone axis and which has its radiation-receiving element aligned with the radiation source
  • a radiation source which emits radiation in a cone-shaped radiation region which opens vertically downwards
  • a radiation receiver which is arranged outside the direct radiation region in the cone axis and which has its radiation-receiving element aligned with the radiation source
  • Surface of particles in the radiation area receives scattered radiation, the radiation area in the radiation direction being delimited by the radiation receiver on all sides, concentrically arranged in a circular ring shape and arranged rotationally symmetrically to the cone axis, the inner surfaces of which are approximately parallel to the cone axis and the outer surfaces of which form an acute angle with the cone axis.
  • Such smoke detectors are used for fire detection, for example.
  • interference radiation emanating from the radiation source and scattered on the inner wall of the housing also strikes the radiation receiver as interference radiation.
  • interference radiation is processed by the receiver in the same way as real radiation scattered by smoke particles in the radiation area, since it has exactly the same modulation.
  • the invention has for its object to provide, while avoiding the disadvantages of prior art smoke detectors mentioned, one which has a lower sensitivity to interference radiation and which has an increased sensitivity, which is retained even over longer periods and with increasing dustiness and which is accordingly reliable over longer periods without the need for cleaning works, and can still quickly get into the smoky air.
  • a smoke detector in that the acute angle which the outer surfaces of the webs form with the cone axis is smaller than the angle of the incident radiation with the cone axis, so that no direct radiation impinges on the outer surfaces of the webs that the upper edges of the webs in the radiation direction are arranged behind the plane of the radiation-receiving upper side of the radiation receiver, so that no direct radiation impinging on these upper edges of the webs hits the radiation-receiving surface of the radiation receiver, and that the majority of the spaces between the webs are open on both sides that penetrated dust sinks further down and does not settle in the area of the webs.
  • the rotationally symmetrical smoke detector shown is enclosed by a housing 1 which has openings 0 for the entry of air into the interior of the detector.
  • a carrier part 2 Provided in the interior of the housing 1 is a carrier part 2, the upper part of which projects beyond the housing 1 and is designed for mechanical fastening and for the electrical connection of the smoke detector to a base (not shown).
  • a holder part 3 is inserted, in which the radiation source is inserted.
  • This radiation source consists of a base part 4, which centrally carries a light or infrared radiation emitting diode 5.
  • a light or infrared radiation emitting diode 5 In the radiation direction, i.e. H.
  • an optical system 6 Below this diode 5 there is an optical system 6, the optically effective surfaces of which are designed in such a way that the radiation emitted by the diode 5 is given a cone-shaped characteristic, so that essentially only radiation in a cone-shaped radiation region C is present, but almost no radiation in Direction of the cone axis A.
  • the residual radiation remaining in the axial direction is additionally shielded by a diaphragm part 7 with a radiation-absorbing surface.
  • the radiation receiver R is arranged in the cone axis A so that its radiation-receiving surface is upwards, i. H. is directed in the direction of the radiation source, so that forward scattered radiation, which is caused by smoke particles in the cone-shaped radiation area C, strikes this radiation receiver R.
  • Parts 8 and 10 hold the radiation receiver in the correct position and at the correct distance from the radiation source.
  • the radiation area C is closed off by a radiation trap part 10.
  • This part has a number of concentric webs S which have annular cross sections and which are arranged rotationally symmetrically about the cone axis A and enclose the radiation receiver R.
  • This part 10 is mounted and positioned in the detector such that the upper edges of the webs S are arranged below the plane E of the radiation-receiving surface of the radiation receiver R, that is to say facing away from this surface.
  • the inner surfaces of the webs S represent cylindrical surfaces around the cone axes, while the outward-facing surfaces of the webs are, at least in the upper part, slightly conical with an acute angle to the cone axis.
  • the opening angle is matched to the opening angle of the cone shell of the radiation area, specifically the angle of inclination of the outer surfaces of the webs S against the cone axis A is advantageously chosen to be somewhat smaller than the opening angle of the cone-shaped radiation area. This ensures that the direct radiation emanating from the radiation source strikes only the vertical inner surfaces of the webs S, but not the inclined outer surfaces.
  • the advantage of this measure is that dust can hardly settle on the vertical inner surfaces. The effect is enhanced when the spaces Z between the webs S are at least predominantly open, so that dust that has entered the detector sinks further down and does not settle at all in the area of the webs S.
  • the open spaces between the webs S are also relative to the openings so that there is no straight path from the openings 0 through these spaces into the detector interior, but smoke-containing air has another option, quickly into the detector interior and to get into the radiation area S or to get out again. This ensures an optimal flow through the smoke detector and ensures a quick alarm when smoke appears in the air.
  • the radiation area is delimited by a diaphragm system 7, which consists of several circular diaphragm disks B, B '...
  • a projection is provided on the optics 6, on which the diaphragm system 7 can be placed.
  • the diameter and the mutual position of the individual diaphragm disks B, B 'in relation to one another is now selected such that one of the diaphragms facing the front, that is to say the radiation source, in the example shown B, acts as an inner boundary of the radiation area C, that is, it projects the furthest into the radiation area .
  • a further aperture B 'facing the radiation receiver is designed in such a way that the direct interference radiation emanating from the edge of the aperture B is completely shielded from the radiation receiver R. .
  • the radiation area C is delimited on the outside by a diaphragm K.
  • This is also chosen in terms of its diameter and arranged relative to the further shielding diaphragm B 'in such a way that the direct interference radiation emanating from the inner edge of this diaphragm K is completely shielded from the radiation receiver R by the diaphragm B'.
  • the measures described first of all ensure that all parts which limit the radiation region C, to which direct radiation impinges, cannot direct any first-degree scatter radiation caused by scattering the direct radiation onto the radiation receiver R. All elements that limit the radiation area C, in the example shown, the parts K, B and S, are therefore outside the direct reception area of the radiation receiver R.
  • those parts of the smoke detector which surround the radiation area C and which are in the direct reception area of the radiation receiver R can be radiation-absorbing.
  • corresponding parts can be provided with ribs X, on which a multiple reflection of stray radiation occurs and therefore only a very weak secondary stray radiation is produced, which could influence the radiation receiver R.
  • These ribs can advantageously with acute-angled edges with an angle of inclination between 20 ° and 70 °, z. B. 45 °, which causes a sufficient radiation absorption.
  • the level of interference radiation can be significantly reduced and the sensitivity of the smoke detector can be increased even further.
  • this guarantees an early alarm even with the lowest smoke density and operational reliability over longer periods of time, even if these smoke detectors are used under unfavorable ambient conditions and are exposed to slow dusting.

Landscapes

  • 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)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
  • Plural Heterocyclic Compounds (AREA)

Abstract

Smoke detector particularly provided for fire alarm with a radiation source (5) having a conical radiation diagram and a radiation receiver (R) located onto the axis but out of reach of the direct radiation which collects the radiation diffused within the conical annular area (C). To limit the parasite light falling onto the receiver, the radiation area (C) is defined by elements located outside the direct collecting area of the receiver for example, in the radiation direction, by pieces (S) located behind the collecting surface and laterally by screens (B, K) of which the edges are concealed by another screen (B'), of the radiation receiver.

Description

Die Erfindung betrifft einen mit gestreuter Strahlung arbeitenden Rauchdetektor mit einer Strahlungsquelle, welche Strahlung in einen kegelringförmig ausgebildeten sich vertikal nach unten öffnenden Strahlungsbereich aussendet, und einem Strahlungsempfänger, der außerhalb des direkten Strahlungsbereiches in der Kegelachse angeordnet ist und der mit seiner zur Strahlungsquelle hin ausgerichteten strahlungsempfangenden Oberfläche an Partikeln im Strahlungsbereich gestreute Strahlung erhält, wobei der Strahlungsbereich in Strahlungsrichtung durch den Strahlungsempfänger allseitig umgebende, konzentrisch in Kreisringform und zur Kegelachse rotationssymmetrisch angeordnete Stege begrenzt wird, deren Innenflächen angenähert parallel zur Kegelachse sind und deren Außenflächen einen spitzen Winkel mit der Kegelachse bilden.The invention relates to a smoke detector which works with scattered radiation and has a radiation source which emits radiation in a cone-shaped radiation region which opens vertically downwards, and a radiation receiver which is arranged outside the direct radiation region in the cone axis and which has its radiation-receiving element aligned with the radiation source Surface of particles in the radiation area receives scattered radiation, the radiation area in the radiation direction being delimited by the radiation receiver on all sides, concentrically arranged in a circular ring shape and arranged rotationally symmetrically to the cone axis, the inner surfaces of which are approximately parallel to the cone axis and the outer surfaces of which form an acute angle with the cone axis.

Solche Rauchdetektoren werden beispielsweise zur Brandmeldung verwendet.Such smoke detectors are used for fire detection, for example.

Zugrunde liegender Stand derTechnikUnderlying state of the art

Ein wichtiges Problem bei solchen Rauchdetektoren besteht darin, die Bestrahlung des Strahlungsempfängers ohne Anwesenheit von Rauch im Strahlungsbereich möglichst klein zu halten, so daß bereits die geringste, durch Rauchpartikeln im Streustrahlungsbereich hervorgerufene Streustrahlung ein Signal am Ausgang des Strahlungsempfängers hervorruft. Ein solcher Rauchdetektor würde bereits auf geringste Rauchkonzentrationen ansprechen und die Anwesenheit von Rauch mit erhöhter Empfindlichkeit signalisieren.An important problem with such smoke detectors is to keep the radiation of the radiation receiver as small as possible without the presence of smoke in the radiation area, so that even the smallest scatter radiation caused by smoke particles in the scattered radiation area causes a signal at the output of the radiation receiver. Such a smoke detector would respond to even the smallest smoke concentrations and signal the presence of smoke with increased sensitivity.

In der Praxis ist jedoch stets ein gewisses Störstrahlungsniveau vorhanden, durch welches die Erreichung dieses Zieles verhindert wird. Es ist daher bekannt geworden, die von außen in einen Rauchdetektor durch die Gehäuseöffnungen eindringende Störstrahlung durch Schikanen an den Lufteintrittsöffnungen fernzuhalten und somit das Störstrahlungsniveau herabzusetzen, wobei jedoch auch der Lufteintritt verlangsamt wird. Eine weitere bekannte Maßnahme besteht darin, die Strahlungsquelle zu modulieren und den Strahlungsempfänger darauf abzustimmen, so daß dieser vorzugsweise nur für Strahlung empfindlich ist, deren Modulation derjenigen der Strahlungsquelle gleicht (CH 491 449 und CH 417 405).In practice, however, there is always a certain level of interference radiation that prevents this goal from being achieved. It has therefore become known to keep the interference radiation penetrating into the outside of a smoke detector through the housing openings by means of baffles at the air inlet openings and thus to reduce the level of interference radiation, although the air inlet is also slowed down. Another known measure is to modulate the radiation source and to match the radiation receiver so that it is preferably only sensitive to radiation whose modulation is the same as that of the radiation source (CH 491 449 and CH 417 405).

Auf die genannte Weise kann jedoch nicht verhindert werden, daß von der Strahlungsquelle ausgehende, an der Gehäuseinnenwand gestreute Strahlung ebenfalls als Störstrahlung auf den Strahlungsempfänger trifft. Eine solche Störstrahlung wird vom Empfänger in gleicher Weise wie echte, an Rauchpartikeln im Strahlungsbereich gestreute Strahlung verarbeitet, da sie genau die gleiche Modulation aufweist. Zur Verminderung dieser Art von Störstrahlung ist es bekannt geworden, die Gehäuseinnenseite des Rauchdetektors weitgehend, jedoch zumindest an den Auftreffstellen der direkten Strahlung im Strahlungsbereich strahlungsabsorbierend auszubilden, beispielsweise matt-schwarz auszuführen, mit Rippen zu versehen oder als Strahlungsfalle auszubilden (US 3 185 975).In the manner mentioned, however, it cannot be prevented that radiation emanating from the radiation source and scattered on the inner wall of the housing also strikes the radiation receiver as interference radiation. Such interference radiation is processed by the receiver in the same way as real radiation scattered by smoke particles in the radiation area, since it has exactly the same modulation. In order to reduce this type of interference radiation, it has become known to design the inside of the smoke detector largely, but at least at the points of impact of the direct radiation in the radiation area, for example to make it matt black, to provide it with ribs or to form it as a radiation trap (US Pat. No. 3,185,975) .

Nachteilig hierbei ist es, daß sich auf den strahlungsabsorbierenden Elementen, z. B. auf den matt-schwarzen Flächen oder den Kanten der aufgesetzten Rippen, im Laufe der Zeit Staub niederschlägt, welcher das Reflexionsvermögen erhöht und die strahlungsabsorbierende Wirkung wieder aufhebt. Solche vorbekannte Rauchdetektoren werden also im Laufe der Zeit mit zunehmender Verstaubung der Gehäuseinnenseite störanfällig.The disadvantage here is that the radiation-absorbing elements, for. B. on the matt black surfaces or the edges of the ribs, over time, deposits dust, which increases the reflectivity and cancels the radiation-absorbing effect again. Such previously known smoke detectors become susceptible to failure over time with increasing dustiness on the inside of the housing.

Offenbarung der ErfindungDisclosure of the invention

Der Erfindung liegt die Aufgabe zugrunde, unter Vermeidung der erwähnten Nachteile vorbekannter Rauchdetektoren einen solchen zu schaffen, der eine geringere Störstrahlungsempfindlichkeit besitzt und der eine erhöhte Empfindlichkeit aufweist, welche auch über längere Zeiträume und bei zunehmender Verstaubung erhalten bleibt und welcher demgemäß über längere Zeiträume betriebssicher ohne die Notwendigkeit einer Reinigung arbeitet, und in den rauchhaltige Luft trotzdem schnell eindringen kann.The invention has for its object to provide, while avoiding the disadvantages of prior art smoke detectors mentioned, one which has a lower sensitivity to interference radiation and which has an increased sensitivity, which is retained even over longer periods and with increasing dustiness and which is accordingly reliable over longer periods without the need for cleaning works, and can still quickly get into the smoky air.

Diese Aufgabe wird bei einem erfindungsgemäßen Rauchdetektor dadurch gelöst, daß der spitze Winkel, den die Außenflächen der Stege mit der Kegelachse bilden, kleiner ist als der Winkel der auftreffenden Strahlung mit der Kegelachse, so daß keine direkte Strahlung auf die Außenflächen der Stege auftrifft, daß die Oberkanten der Stege in Strahlungsrichtung hinter der Ebene der strahlungsempfangenden Oberseite des Strahlungsempfängers angeordnet sind, so daß keine auf diese Oberkanten der Stege auftreffende Direktstrahlung auf die strahlungsempfangende Fläche des Strahlungsempfängers auftrifft, und daß der überwiegende Teil der Zwischenräume zwischen den Stegen beidseitig offen ist, so daß eingedrungener Staub weiter nach unten sinkt und sich nicht im Bereich der Stege absetzt.This object is achieved in a smoke detector according to the invention in that the acute angle which the outer surfaces of the webs form with the cone axis is smaller than the angle of the incident radiation with the cone axis, so that no direct radiation impinges on the outer surfaces of the webs that the upper edges of the webs in the radiation direction are arranged behind the plane of the radiation-receiving upper side of the radiation receiver, so that no direct radiation impinging on these upper edges of the webs hits the radiation-receiving surface of the radiation receiver, and that the majority of the spaces between the webs are open on both sides that penetrated dust sinks further down and does not settle in the area of the webs.

Eine vorteilhafte Weiterbildung der Erfindung ergibt sich dann, wenn der Strahlungsbereich durch äußere und innere Blenden begrenzt wird, welche so angeordnet sind, daß deren bestrahlte Kanten durch eine weitere Blende vom zentralen Strahlungsempfänger abgeschirmt sind. Damit wird erreicht, daß die Streustrahlung von diesen Kanten nicht direkt auf den Strahlungsempfänger gelangen kann.An advantageous further development of the invention results when the radiation area is delimited by outer and inner diaphragms which are arranged in such a way that their irradiated edges are shielded from the central radiation receiver by a further diaphragm. This ensures that the scattered radiation from these edges cannot reach the radiation receiver directly.

Kurze Beschreibung der ZeichnungBrief description of the drawing

In der Figur ist im Schnitt ein bevorzugtes Ausführungsbeispiel eines erfindungsgemäßen Rauchdetektors wiedergegeben.In the figure, a preferred embodiment of a smoke detector according to the invention is shown in section.

Bester Weg zur Ausführung der ErfindungBest way to carry out the invention

Der dargestellte, rotationssymmetrische Rauchdetektor wird von einem Gehäuse 1 umschlossen, welches Öffnungen 0 zum Eintritt von Luft in das Detektorinnere aufweist. Im Inneren des Gehäuses 1 ist ein Trägerteil 2 vorgesehen, dessen über das Gehäuse 1 hinausragender Oberteil zur mechanischen Befestigung und zum elektrischen Anschluß des Rauchdetektors an einen nicht dargestellten Sockel ausgebildet ist.The rotationally symmetrical smoke detector shown is enclosed by a housing 1 which has openings 0 for the entry of air into the interior of the detector. Provided in the interior of the housing 1 is a carrier part 2, the upper part of which projects beyond the housing 1 and is designed for mechanical fastening and for the electrical connection of the smoke detector to a base (not shown).

In einer zentralen Bohrung dieses Trägerteiles 2 ist ein Halterungsteil 3 eingesetzt, in welches die Strahlungsquelle eingesetzt ist.In a central bore of this carrier part 2, a holder part 3 is inserted, in which the radiation source is inserted.

Diese Strahlungsquelle besteht aus einem Basisteil 4, welches zentral eine Licht- oder Infrarotstrahlung emittierende Diode 5 trägt. In Strahlungsrichtung, d. h. unterhalb dieser Diode 5 ist eine Optik 6 angesetzt, deren optisch wirksame Flächen so ausgebildet sind, daß die von der Diode 5 emittierte Strahlung eine kegelringförmige Charakteristik erhält, so daß im wesentlichen nur Strahlung in einem kegelringförmigen Strahlungsbereich C vorhanden ist, dagegen nahezu keine Strahlung in Richtung der Kegelachse A.This radiation source consists of a base part 4, which centrally carries a light or infrared radiation emitting diode 5. In the radiation direction, i.e. H. Below this diode 5 there is an optical system 6, the optically effective surfaces of which are designed in such a way that the radiation emitted by the diode 5 is given a cone-shaped characteristic, so that essentially only radiation in a cone-shaped radiation region C is present, but almost no radiation in Direction of the cone axis A.

Die in Achsenrichtung verbleibende Reststrahlung wird zusätzlich durch ein Blendenteil 7 mit strahlungsabsorbierender Oberfläche abgeschirmt. Unterhalb der Strahlungsquelle und des Blendenteiles ist in der Kegelachse A der Strahlungsempfänger R so angeordnet, daß seine strahlungsempfangende Fläche nach oben, d. h. in Richtung zur Strahlungsquelle gerichtet ist, so daß vorwärts gestreute Streustrahlung, welche durch Rauchpartikel im kegelringförmigen Strahlungsbereich C verursacht wird, auf diesen Strahlungsempfänger R trifft. Der Strahlungsempfänger wird durch die Teile 8 und 10 in der richtigen Position und in richtigem Abstand zur Strahlungsquelle gehalten.The residual radiation remaining in the axial direction is additionally shielded by a diaphragm part 7 with a radiation-absorbing surface. Below the radiation source and the diaphragm part, the radiation receiver R is arranged in the cone axis A so that its radiation-receiving surface is upwards, i. H. is directed in the direction of the radiation source, so that forward scattered radiation, which is caused by smoke particles in the cone-shaped radiation area C, strikes this radiation receiver R. Parts 8 and 10 hold the radiation receiver in the correct position and at the correct distance from the radiation source.

In Strahlungsrichtung ist der Strahlungsbereich C durch ein strahlungsauffanges Teii 10 abgeschlossen. Dieses Teil weist eine Anzahl von konzentrischen Stegen S auf, welche kreisringförmige Querschnitte aufweisen und welche rotationssymmetrisch um die Kegelachse A angeordnet sind und den Strahlungsempfänger R umschließen. Dieses Teil 10 ist so im Detektor angebracht und positioniert, daß die Oberkanten der Stege S unter der Ebene E der strahlungsempfangenden Fläche des Strahlungsempfängers R angeordnet sind, also dieser Fläche abgewandt. Mit dieser Maßnahme wird erreicht, daß die auf die Oberkanten der Stege S auftreffende Direktstrahlung zwar in gewissem Maße dort gestreut wird; diese Streustrahlung ersten Grades kann jedoch bei der angegebenen Lage der einzelnen Teile zueinander nicht direkt auf die strahlungsempfangende Fläche des Strahlungsempfängers R auftreffen, sondern erst die mehrfach gestreute Strahlung, welche dann eine wesentlich schwächere lntensi•ät aufweist.In the radiation direction, the radiation area C is closed off by a radiation trap part 10. This part has a number of concentric webs S which have annular cross sections and which are arranged rotationally symmetrically about the cone axis A and enclose the radiation receiver R. This part 10 is mounted and positioned in the detector such that the upper edges of the webs S are arranged below the plane E of the radiation-receiving surface of the radiation receiver R, that is to say facing away from this surface. With this measure it is achieved that the direct radiation impinging on the upper edges of the webs S is scattered there to a certain extent; However, this scattered radiation of the first degree cannot strike the radiation-receiving surface of the radiation receiver R directly at the specified position of the individual parts, but only the multiple-scattered radiation, which then has a much weaker intensity.

Die Innenflächen der Stege S stellen in diesem Beispiel Zylinderflächen um die Kegelachsen dar, während die nach außen gerichteten Flächen der Stege zumindest im oberen Teil leicht konisch mit spitzem Winkel zur Kegelachse ausgeführt sind. Der Öffnungswinkel ist dabei auf den Öffnungswinkel des Kegelmantels des Strahlungsbereiches abgestimmt, und zwar wird der Neigungswinkel der Außenflächen der Stege S gegen Kegelachse A zweckmäßigerweise etwas kleiner gewählt als der Öffnungswinkel des kegelringförmigen Strahlungsbereiches. Hierdurch wird erreicht, daß die von der Strahlungsquelle ausgehende direkte Strahlung nur auf die vertikalen Innenflächen der Stege S auftrifft, jedoch nicht auf die geneigten Außenflächen. Der Vorteil dieser Maßnahme ist, daß sich auf den vertikalen Innenflächen Staub nahezu nicht absetzen kann. Verstärkt wird die Wirkung dann, wenn die Zwischenräume Z zwischen den Stegen S zumindest überwiegend offen sind, so daß in den Detektor eingedrungener Staub weiter nach unten sinkt und sich überhaupt nicht im Bereich der Stege S absetzt.In this example, the inner surfaces of the webs S represent cylindrical surfaces around the cone axes, while the outward-facing surfaces of the webs are, at least in the upper part, slightly conical with an acute angle to the cone axis. The opening angle is matched to the opening angle of the cone shell of the radiation area, specifically the angle of inclination of the outer surfaces of the webs S against the cone axis A is advantageously chosen to be somewhat smaller than the opening angle of the cone-shaped radiation area. This ensures that the direct radiation emanating from the radiation source strikes only the vertical inner surfaces of the webs S, but not the inclined outer surfaces. The advantage of this measure is that dust can hardly settle on the vertical inner surfaces. The effect is enhanced when the spaces Z between the webs S are at least predominantly open, so that dust that has entered the detector sinks further down and does not settle at all in the area of the webs S.

Um zusätzlich ein schnelles Eindringen rauchhaltiger Luft in das Detektor-Innere zu ermöglichen, ohne den Zutritt von Störlicht von außen zu gestatten, ist es zweckmäßig, den Außenrand des Strahlungsauffang-Teiles 10 so zu gestalten und die Öffnungen 0 seitlich am Gehäuse 1 so anzubringen, daß diese vom Rand des Teiles 10 überdeckt werden. Das obere Ende des Randes greift dabei in einen Zwischenraum zwischen Gehäuse 1 und einem Steg 11 auf dem Distanzring 8 ein, so daß kein geradliniger Pfad von den Öffnungen 0 in das Detektor-Innere führt, also Licht von außen nicht direkt eintreten kann, daß jedoch einströmende Luft nur um etwa 90° umgelenkt wird, also deren Eindringen nur wenig behindert wird. Dabei liegen die offenen Zwischenräume zwischen den Stegen S relativ zu den Öffnungen ebenfalls so, daß auch kein geradliniger Pfad von den Öffnungen 0 durch diese Zwischenräume in das Detektor-Innere führt, rauchhaltige Luft jedoch eine weitere Möglichkeit hat, schnell in das Detektor-Innere und in den Strahlungsbereich S zu gelangen oder wieder hinauszugelang,en. Damit wird eine optimale Durchströmung des Rauchdetektors erreicht und eine schnelle Alarmgabe bei Auftreten von Rauch in der Luft gewährleistet.In order to allow a rapid penetration of smoke-containing air into the interior of the detector without allowing outside light to enter, it is advisable to design the outer edge of the radiation-absorbing part 10 in this way and to make the openings 0 on the side of the housing 1 in such a way that that these are covered by the edge of part 10. The upper end of the edge engages in a space between the housing 1 and a web 11 on the spacer ring 8, so that no straight path leads from the openings 0 into the inside of the detector, that is, light from the outside cannot enter directly, but that incoming air is deflected by only about 90 °, so its penetration is only slightly impeded. The open spaces between the webs S are also relative to the openings so that there is no straight path from the openings 0 through these spaces into the detector interior, but smoke-containing air has another option, quickly into the detector interior and to get into the radiation area S or to get out again. This ensures an optimal flow through the smoke detector and ensures a quick alarm when smoke appears in the air.

Auf der Innenseite des Kegelringes C wird der Strahlungsbereich durch ein Blendensystem 7 begrenzt, welches aus mehreren kreisförmigen Blendenscheiben B, B' ... besteht. Um das Blendensystem 7 gegenüber der Strahlungsquelle 5 in die richtige Position bringen zu können, ist an der Optik 6 ein Vorsprung vorgesehen, auf welchen das Blendensystem 7 aufgesetzt werden kann. Der Durchmesser und die gegenseitige Lage der einzelnen Blendenscheiben B, B' zueinander ist nun so gewählt, daß eine der vorderen, also der Strahlungsquelle zugewandten Blenden, im dargestellten Beispiel B, als innere Begrenzung des Strahlungsbereiches C wirkt, d. h. am weitesten in den Strahlungsbereich hineinragt. Um zu verhindern, daß die an der Kante dieser Blendenscheibe B gestreute Störstrahlung auf den Strahlungsempfänger R auftrifft, ist eine weitere, dem Strahlungsempfänger zugewandte Blende B' so gestaltet, daß die von der Kante der Blende B ausgehende direkte Störstrahlung vollständig vom Strahlungsempfänger R abgeschirmt ist.On the inside of the cone ring C, the radiation area is delimited by a diaphragm system 7, which consists of several circular diaphragm disks B, B '... In order to be able to bring the diaphragm system 7 into the correct position with respect to the radiation source 5 a projection is provided on the optics 6, on which the diaphragm system 7 can be placed. The diameter and the mutual position of the individual diaphragm disks B, B 'in relation to one another is now selected such that one of the diaphragms facing the front, that is to say the radiation source, in the example shown B, acts as an inner boundary of the radiation area C, that is, it projects the furthest into the radiation area . In order to prevent the interference radiation scattered at the edge of this diaphragm disk B from striking the radiation receiver R, a further aperture B 'facing the radiation receiver is designed in such a way that the direct interference radiation emanating from the edge of the aperture B is completely shielded from the radiation receiver R. .

An der Außenseite wird der Strahlungsbereich C durch eine Blende K begrenzt. Diese ist ebenfalls in ihrem Durchmesser so gewählt und gegenüber der weiteren Abschirmblende B' so angeordnet, daß auch die von der Innenkante dieser Blende K ausgehende direkte Störstrahlung vollständig durch die Blende B' vom Strahlungsempfänger R abgeschirmt ist.The radiation area C is delimited on the outside by a diaphragm K. This is also chosen in terms of its diameter and arranged relative to the further shielding diaphragm B 'in such a way that the direct interference radiation emanating from the inner edge of this diaphragm K is completely shielded from the radiation receiver R by the diaphragm B'.

Durch die beschriebenen Maßnahmen wird zunächst erreicht, daß sämtliche Teile, welche den Strahlungsbereich C begrenzen, auf welche also direkte Strahlung auftrifft, keine durch Streuung der direkten Strahlung hervorgerufene Streustrahlung ersten Grades auf den Strahlungsempfänger R richten können. Sämtliche Elemente, welche den Strahlungsbereich C begrenzen, im dargestellten Beispiel also die Teile K, B und S, liegen also außerhalb des direkten Empfangsbereiches des Strahlungsempfängers R.The measures described first of all ensure that all parts which limit the radiation region C, to which direct radiation impinges, cannot direct any first-degree scatter radiation caused by scattering the direct radiation onto the radiation receiver R. All elements that limit the radiation area C, in the example shown, the parts K, B and S, are therefore outside the direct reception area of the radiation receiver R.

Um das Störstrahlungsniveau weiter zu vermindern, ist es zweckmäßig, diejenigen Teile des Rauchdetektors, welche den Strahlungsbereich C umschließen und welche im direkten Empfangsbereich des Strahlungsempfängers R liegen, strahlungsabsorbierend auszubilden. Beispielsweise können entsprechende Teile mit Rippen X versehen sein, an welchen eine mehrfache Reflexion auftreffender Störstrahlung erfolgt und daher nur eine sehr schwache sekundäre Störstrahlung hervorgerufen wird, welche den Strahlungsempfänger R beeinflussen könnte. Diese Rippen können mit Vorteil mit spitzwinkligen Kanten mit einem Neigungswinkel zwischen 20° und 70°, z. B. 45° versehen sein, wodurch eine hinreichende Strahlungsabsorbtion bewirkt wird.In order to further reduce the interference radiation level, it is expedient to design those parts of the smoke detector which surround the radiation area C and which are in the direct reception area of the radiation receiver R to be radiation-absorbing. For example, corresponding parts can be provided with ribs X, on which a multiple reflection of stray radiation occurs and therefore only a very weak secondary stray radiation is produced, which could influence the radiation receiver R. These ribs can advantageously with acute-angled edges with an angle of inclination between 20 ° and 70 °, z. B. 45 °, which causes a sufficient radiation absorption.

Gewerbliche VerwertbarkeitCommercial usability

Auf diese Weise kann das Störstrahlungsniveau erheblich herabgesetzt und die Empfindlichkeit des Rauchdetektors noch mehr vergrößert werden. Speziell bei der Verwendung als Brandmelder ist dadurch eine frühzeitige Alarmgabe schon bei geringster Rauchdichte und eine Betriebssicherheit über längere Zeiträume gewährleistet, auch wenn diese Rauchdetektoren unter ungünstigen Umgebungsbedingungen verwendet werden und einer langsamen Verstaubung ausgesetzt sind.In this way, the level of interference radiation can be significantly reduced and the sensitivity of the smoke detector can be increased even further. Especially when used as a fire detector, this guarantees an early alarm even with the lowest smoke density and operational reliability over longer periods of time, even if these smoke detectors are used under unfavorable ambient conditions and are exposed to slow dusting.

Claims (8)

1. A smoke detector comprising a radiation source (4, 5, 6) for emitting radiation into a conical ring-shaped direct radiation region (C) extending vertically downwards from the radiation source a radiation receiver (R) arranged externally of the direct radiation region in the cone axis, said radiation receiver having its radiation receiving surface directed to the radiation source and receiving radiation scattered by particles located within the direct radiation region (C), webs (S) surrounding the radiation receiver (R) at all sides and limiting the radiation region (C) in the radiation direction of the radiation source, said webs being arranged in a ring-shaped configuration and rotationally symmetrical with respect to the cone axis, the inner surfaces of said webs (S) being arranged approximately parallel to the cone axis and the outer surfaces of said webs (S) enclosing an acute angle with the cone axis, characterized in that the acute angles which the outer surfaces of the webs (S) enclose with the cone axis are smaller than the angle between the direct radiation impinging onto the webs (S) and the cone axis, in order to thereby exclude direct radiation from impinging said outer surfaces of said webs, that the upper edges of said webs (C) are arranged rewardly of the plane (E) containing the radiation receiving surface of said radiation receiver (R), in order to thereby suppress the reception of radiation scattered by the upper edges of said webs (S) from reaching said radiation receiver (R) and that the predominant part of the intermediate spaces (2) between the webs (S) are open at both ends, so that dust which has penetrated into the smoke detector can further fall down and not settle at the region of the webs (S).
2. Smoke detector according to claim 1, characterized in that the webs (S) are arranged on a radiation entrapping element (10), the outer edge or rim of this element (10) being constructed such that the air openings (O) laterally at the housing (1) which encloses tile radiation region (C) are covered by that edge or rim such that no linear path leads from the openings (0) into the interior of the smoke detector.
3. Smoke detector according to claim 1, characterized in that the air openings (0) of the housing (1) which encloses the radiation region (C) relative to the open intermediate spaces (2) between the webs (S) are arranged such that no linear path leads from the openings (0) into the interior of the smoke detector.
4. Smoke detector according to any of the claims 1 to 3, characterized in that the surfaces (X) opposite the webs (S) comprise radiation absorbing ribs.
5. Smoke detector according to claim 4, characterized in that the ribs (X) comprise acute-angled edges having an angle of inclination between 20° and 70°.
6. Smoke detector according to any of the claims 1 to 5, characterized in that the radiation region (C) is limited by at least one diaphragm (K, B) having an outer edge, which is screened from the radiation receiver (R) by a further diaphragm (B'), which is disposed substantially parallel to the first-mentioned diaphragm (K, B).
7. Smoke detector according to claim 6, characterized in that the radiation region (C) is limited at its outer surface by the edge (K) of a circular diaphragm and that a circular diaphragm (B) is provided which screens the edge (K) from the radiation receiver (R).
8. Smoke detector according to claim 6, characterized in that the radiation region (C) is limited at its inner surface by a circular diaphragm (B) arranged axial to the radiation region (C) which diaphragm is screened from the radiation receiver (R) by a further circular diaphragm (B') arranged axial to the radiation region (C).
EP80900014A 1978-12-21 1980-07-01 Smoke detector operating with scattered radiation Expired EP0020674B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80900014T ATE3597T1 (en) 1978-12-21 1979-12-01 SCATTERED RADIATION SMOKE DETECTOR.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CH13000/78 1978-12-21
CH1300178A CH634429A5 (en) 1978-12-21 1978-12-21 Smoke detector
CH13001/78 1978-12-21
CH1300078A CH634428A5 (en) 1978-12-21 1978-12-21 Smoke detector

Publications (2)

Publication Number Publication Date
EP0020674A1 EP0020674A1 (en) 1981-01-07
EP0020674B1 true EP0020674B1 (en) 1983-05-25

Family

ID=25711348

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80900014A Expired EP0020674B1 (en) 1978-12-21 1980-07-01 Smoke detector operating with scattered radiation

Country Status (10)

Country Link
US (1) US4269510A (en)
EP (1) EP0020674B1 (en)
JP (1) JPS55501074A (en)
AU (1) AU512930B2 (en)
CA (1) CA1115377A (en)
DE (1) DE2965556D1 (en)
DK (1) DK150045C (en)
IT (1) IT1124404B (en)
NO (1) NO149751C (en)
WO (1) WO1980001326A1 (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4430646A (en) 1980-12-31 1984-02-07 American District Telegraph Company Forward scatter smoke detector
USRE32105E (en) * 1980-12-31 1986-04-01 American District Telegraph Company Forward scatter smoke detector
CH656474A5 (en) * 1981-11-11 1986-06-30 Cerberus Ag SMOKE DETECTOR.
EP0135361B1 (en) * 1983-08-12 1995-04-26 I.E.I. Pty Ltd A.C.N. 053 531 212 Apparatus for detecting particulate material in suspension
US4618777A (en) * 1984-11-19 1986-10-21 Pittway Corporation Outer electrode with improved smoke entry
GB8502506D0 (en) * 1985-01-31 1985-03-06 Emi Ltd Smoke detector
US4906978A (en) * 1986-12-24 1990-03-06 Cerberus Ag Optical smoke detector
US5021677A (en) * 1989-05-02 1991-06-04 Nohmi Bosai Kabushiki Kaisha Light-scattering-type smoke detector
US5420440A (en) * 1994-02-28 1995-05-30 Rel-Tek Corporation Optical obscruation smoke monitor having a shunt flow path located between two access ports
DE19720007C2 (en) * 1997-05-13 1999-06-02 Siemens Ag Gas sensor system for the detection of at least one gas or of particles or a combination thereof with two gas sensors, method for its operation and use of the gas sensor system
US7592922B2 (en) * 2007-01-18 2009-09-22 Michael E. La Vigne Smoke detector guard concentrator
WO2014033921A1 (en) * 2012-08-31 2014-03-06 日本フェンオール株式会社 Light emitting unit and photoelectric smoke detector, and suction-type smoke detection system
CN108898780A (en) * 2018-07-13 2018-11-27 江苏慧学堂系统工程有限公司 A kind of smoke detector based on wireless network

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3185975A (en) * 1962-06-18 1965-05-25 Honeywell Inc Photoelectric smoke detector
FR2357888A1 (en) * 1976-04-01 1978-02-03 Cerberus Ag SMOKE DETECTOR

Also Published As

Publication number Publication date
EP0020674A1 (en) 1981-01-07
CA1115377A (en) 1981-12-29
WO1980001326A1 (en) 1980-06-26
JPS55501074A (en) 1980-12-04
NO149751C (en) 1984-06-20
AU5206679A (en) 1980-06-26
IT1124404B (en) 1986-05-07
DK150045C (en) 1987-05-11
NO149751B (en) 1984-03-05
NO794195L (en) 1980-06-24
IT7912865A0 (en) 1979-12-12
DK150045B (en) 1986-11-24
US4269510A (en) 1981-05-26
AU512930B2 (en) 1980-11-06
DE2965556D1 (en) 1983-07-07
DK357680A (en) 1980-08-20

Similar Documents

Publication Publication Date Title
EP0020674B1 (en) Smoke detector operating with scattered radiation
EP1376504B1 (en) Light scattering smoke detector
DE102005018559B4 (en) smoke detector
DE2619083C3 (en) Smoke detector
DE10246756B4 (en) Fire detection procedure and fire detector for its implementation
DE2046492C3 (en) smoke detector
DE2951459A1 (en) OPTICAL ARRANGEMENT FOR A SMOKE DETECTOR ACCORDING TO THE LIGHT DISTRIBUTION PRINCIPLE
WO2008017698A1 (en) Scattered light smoke detector
DE2754139A1 (en) SMOKE DETECTOR
DE19809896A1 (en) Fire alarm
WO1984001650A1 (en) Diffused radiation smoke detector
CH688166A5 (en) Smoke detector of the light scattering type.
DE3008183A1 (en) DEVICE FOR DISPLAYING PARTICLES SUSPENDED IN A GAS
EP0821330B1 (en) Smoke detector
DE3812969A1 (en) Infrared movement alarm
DE19741853A1 (en) Hollow ellipse smoke alarm
DE4137560C1 (en)
DE2908099C2 (en) Smoke detector
DE2709866A1 (en) Detector for suspended particles - has radiation receivers for direct and scattered radiation and evaluation circuit
DE2908100C2 (en) Smoke detector
DE1957494C3 (en) Photoelectric scanning device
DE2758517A1 (en) SMOKE DETECTOR WITH A DARK FIELD OPTICS
DE3345688A1 (en) Scattered-light smoke alarm
WO1998003947A1 (en) Smoke alarm
DE3018021C2 (en)

Legal Events

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

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19800910

AK Designated contracting states

Designated state(s): AT DE FR GB NL SE

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): AT DE FR GB NL SE

REF Corresponds to:

Ref document number: 3597

Country of ref document: AT

Date of ref document: 19830615

Kind code of ref document: T

REF Corresponds to:

Ref document number: 2965556

Country of ref document: DE

Date of ref document: 19830707

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

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

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19891108

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19891115

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19891231

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19901112

Year of fee payment: 12

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19901114

Year of fee payment: 12

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19901129

Year of fee payment: 12

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19901201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19901202

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19910701

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19911201

GBPC Gb: european patent ceased through non-payment of renewal fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19920831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19920901

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

EUG Se: european patent has lapsed

Ref document number: 80900014.4

Effective date: 19910910