EP0175940B1 - Photoelektrischer Rauchdetektor - Google Patents

Photoelektrischer Rauchdetektor Download PDF

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Publication number
EP0175940B1
EP0175940B1 EP85110642A EP85110642A EP0175940B1 EP 0175940 B1 EP0175940 B1 EP 0175940B1 EP 85110642 A EP85110642 A EP 85110642A EP 85110642 A EP85110642 A EP 85110642A EP 0175940 B1 EP0175940 B1 EP 0175940B1
Authority
EP
European Patent Office
Prior art keywords
light
smoke detector
photoelectric smoke
front wall
wall
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 - Lifetime
Application number
EP85110642A
Other languages
English (en)
French (fr)
Other versions
EP0175940A1 (de
Inventor
Yoshiharu Nohmi Bosai Kogyo Co. Ltd. Orioka
Mikio Nohmi Bosai Kogyo Co. Ltd. Mochizuki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nohmi Bosai Ltd
Original Assignee
Nohmi Bosai Kogyo Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP59174043A external-priority patent/JPS6153550A/ja
Priority claimed from JP17940084A external-priority patent/JPS6157835A/ja
Priority claimed from JP13058784U external-priority patent/JPS6146454U/ja
Application filed by Nohmi Bosai Kogyo Co Ltd filed Critical Nohmi Bosai Kogyo Co Ltd
Priority to AT85110642T priority Critical patent/ATE58976T1/de
Publication of EP0175940A1 publication Critical patent/EP0175940A1/de
Application granted granted Critical
Publication of EP0175940B1 publication Critical patent/EP0175940B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • 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 present invention broadly relates to a photoelectric smoke detector and, more specifically, pertains to a new and improved construction of a small-size or miniature photoelectric smoke detector.
  • the present invention specifically relates to a new and improved construction of a photoelectric smoke detector which is equipped with a light emitter for radiating light into a measuring chamber and a light receiver for detecting scattered light caused by the entry or presence of smoke in the measuring space.
  • Dark chambers of conventional photoelectric smoke detectors have a complicated labyrinth construction or double covers and/or additional light shielding plates to prevent the environmental light from entering the dark chamber but to facilitate entry of smoke into the same, see, for example, US-A-3,708,675.
  • photoelectric smoke detectors as mentioned above, being large in size, are not suitable for use as photoelectric smoke detectors to be built-in into equipment such as electronic computers or to be installed in lavatories in aircraft.
  • These photoelectric smoke detectors also have the disadvantage that miniaturization thereof by merely reducing the size of their dark chambers result in lowering the SN ratio.
  • An important and more specific object of the present invention is directed to the provision of a new and improved construction of a photoelectric smoke detector which, although being a small-sized construction, possesses a favourable signal-to-noise ratio for smoke detection.
  • Yet a further significant object of the present invention aims at providing a new and improved construction of a photoelectric smoke detector which is relatively simple in construction and design, extremely economical to manufacture, highly reliable in operation, not readily subject to breakdown or malfunction and requires a minimum of maintenance and servicing.
  • a dark chamber forming the measuring space comprises at least one wall comprising planar or curved surfaces arranged substantially in front of the light emitter for reflecting the light radiated from the light emitter at a predetermined angle to the optical axis of the light emitter.
  • the dark chamber also possesses side walls arranged substantially parallel to the optical axis defined by the light emitter.
  • the photoeletric smoke detector according to the present invention is equipped with a dark chamber of the aforesaid construction such that the dark chamber itself is capable of performing the light trap function. More specifically, the dark chamber is designed in such a way that the light beam radiated by the light emitter is reflected from the wall surfaces of the dark chamber several times without allowing the initially reflected light to reach the light receiving element of the light receiver. The reflected light, if any, reaching the light receiver or receiving element is attenuated to a very weak intensity. Therefore it is not necessary to specially provide a light trap means. Thus a small-sized photoelectric smoke detector with a narrow measuring space is obtained.
  • FIG. 1 is a cross section and (b) is a transverse section of the dark chamber according to the present invention, wherein the components are indicated by numerals as follows: 1 - a light emitter which is equipped with a light source such as light emitting diode and a lens, and radiates a convergent light beam; 2-a light receiver comprising a light receiving element such as solar cell and a lens; 3 - a light shielding plate provided between the light emitter 1 and the light receiver 2; 4, 5 - side walls arranged nearly in parallel with the optical axis of the light beam radiated from the light emitter 1; 6 - a front wall with a plane or curved surface which is arranged in front of the light emitter 1 to reflect the light at a predetermined angle to the optical axis; 7 - a rear wall with plane or curved surface which is arranged in the rear of the light emitter 1 to
  • the wall surfaces are of black color and finished up like a mirror. Further in the figures, s - a starting point of the light beam; arrow - a point where the light beam reaches; black dots - reflection points on the side wall 4; white dots - reflection points on the side wall 5; triangle - a reflection point on the top wall 9.
  • the walls of the dark chamber have mirror-like surfaces with good absorbance.
  • the convergent light beam radiated from the light emitter 1 impinges on the left side surface of the front wall 6 and is absorbed by the black surface. Unabsorbed light is reflected from the mirror-like surface nearly as it is, i.e. in the form of convergent light beam without being diffused, and from the left wall 4, the right and left walls 5, 4, further from the top wall 9, the right wall 5, the left wall 4, the left side of the rear wall 7, and then impinges on the outer wall of the light receiver 2.
  • the dark chamber acts as light trap, where the light radiated from the light emitter 1 is absorbed by the black surfaces and attenuated while being reflected several times, and eventually becomes a very weak light.
  • the light radiated from the light emitter 1 is reflected from the left side of the front wall 6, the left wall 4, the right, left, right walls, the top wall 9, the left wall 4, the right wall 5, and the right side of the rear wall 7 and then impinges on the outer wall of the light receiver 2.
  • the light radiated from the light emitter 1 is reflected from the left side of the front wall 6, the left wall 4, the top wall 9, the right, left, right, left walls and the left of the rear wall 7, and then impinges on the outer wall of the light emitter 1, thus being attenuated to a very weak light.
  • Fig. 4 shows characteristics of the dark chamber, with S representing output of the light receiving element when a predetermined density of smoke for decision on fire entered the dark chamber, N representing output of the light receiving element in normal condition, and 6 representing angles of the front and rear walls 6, 7. According to this Figure, a sufficient SN ratio for practical use is obtained at 6 of not more than 140° or not less than 210°.
  • the photoelectric smoke detector according to the present invention is equipped with a dark chamber of the above composition whereby the dark chamber itself is capable of performing a light trap function. More specifically, the dark chamber is designed in such a way that the light beam radiated by the light emitter is reflected several times from the side walls via the front and rear walls, without allowing the initially reflected light to reach the light receiving element of the light receiver, and that reflected light reaching the light receiving element if any is attenuated to a very weak one. Therefore, this idea has such an effect that a small-sized photoelectric smoke detector which has a narrow measuring space and does not require special provision of a light trap means is obtained.

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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)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Claims (6)

1. Ein photoelektrischer Rauchdetektor mit einer Vorderwand (6), zwei sich gegenüberliegenden Seitenwänden (4, 5), einer Rückwand (7) einer Decke (9) und einem Boden (8), welche zusammen einen Meßraum begrenzen; mit einer Lichtquelle (1) zum Aussenden von Licht entlang einer vorbestimmten optische Achse; mit einem Lichtempfänger (2) zur Detektion von gestreutem Licht, welches bei Anwesenheit von Rauch von dem Licht gestreut wird, das in den Meßraum eingestrahlt wird; wobei die Vorderwand (6) praktisch gegenüber der Lichtquelle (1) angeordnet ist, um Licht zu empfangen, das von der Lichtquelle (1) ausgesandt wurde und die beiden einander gegenüberliegenden Seitenwänder praktisch parallel zu der optischen Achse angeordnet sind; dadurch gekennzeichnet, daß wenigstens die Vorderwand (6) und die beiden einander gegenüberliegenden Seitenwände (4, 5) dem Meßraum zugewandte reflektierende Oberflächen aufweisen und daß die Vorderwand (6) zwei benachbarte, praktisch ebene Seitenflächen aufweist, welche zwischen sich einen vorbestimmten Winkel bilden und die dem Meßraum zugewandte reflektierende Oberfläche darstellen und welche das empfangene Licht in einem praktisch rechten Winkel zu einer durch die vorbestimmte optische Achse der Lichtquelle (1) und der optischen Achse des Lichtempfängers (2) gebildeten Ebene refklektieren; wobei die reflektierenden Oberflächen der Vorderwand (6) und der beiden einander gegenüberliegenden Seitenwände (4, 5) Lichtfallen für das von der Lichtquelle (1) ausgesandte Licht darstellen und dieses Licht vielfach durch den Meßraum reflektieren und wobei der Lichtempfänger (2) außerhalb des Strahlengangs dieses vielfach reflektierten Lichts angeordnet ist.
2. Photoelektrischer Rauchdetektor gemäß Patentanspruch 1, dadurch gekennzeichnet, daß die beiden benachbarten Seitenflächen der Vorderwand (6) zwischen sich einen Winkel bilden, der kleiner als 140° oder größer als 210° ist.
3. Photoelektrischer Rauchdetektor gemäß Patentanspruch 1, dadurch gekennzeichnet, daß die Lichtquelle (2) zur Aussendung von Licht entlang der vorbestimmten optischen Achse in den Meßraum einen konvergenten Lichtstrahl aussendet.
4. Photoelektrischer Rauchdetektor gemäß Patentanspruch 1, dadurch gekennzeichnet, daß der Lichtempfänger (2) außerhalb der vorbestimmten optischen Achse, entlang der das Licht von der Lichtquelle (1) ausgesandt wird, angeordnet ist.
5. Photoelektrischer Rauchdetektor gemäß einem der Patentansprüche 1 bis 4, dadurch gekennzeichnet, daß der Meßraum eine Dunkelkammar darstellt; wobei diese Dunkelkammer durch reflektierende, lichtabsorbierende Oberflächen von mindestens der Vorderwand (6) der Rückwand (7) un den beiden einander gegenüberliegenden Seitenwänden (4, 5) begrenzt wird.
6. Photoelektrischer Rauchdetektor gemäß einem der Patentansprüche 1 bis 4, dadurch gekennzeichnet, daß die reflektierenden Oberflächen von mindestens der Frontwand (6), der Rückwand (7) und den beiden einander gegenüberliegenden Seitenwänden (4, 5) spiegelähnliche Oberflächen mit guter Absorptionsfähigkeit aufweisen.
EP85110642A 1984-08-23 1985-08-23 Photoelektrischer Rauchdetektor Expired - Lifetime EP0175940B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85110642T ATE58976T1 (de) 1984-08-23 1985-08-23 Photoelektrischer rauchdetektor.

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP174043/84 1984-08-23
JP59174043A JPS6153550A (ja) 1984-08-23 1984-08-23 光電式煙感知器
JP179400/84 1984-08-30
JP130587/84U 1984-08-30
JP17940084A JPS6157835A (ja) 1984-08-30 1984-08-30 光電式煙感知器
JP13058784U JPS6146454U (ja) 1984-08-30 1984-08-30 光電式煙感知器

Publications (2)

Publication Number Publication Date
EP0175940A1 EP0175940A1 (de) 1986-04-02
EP0175940B1 true EP0175940B1 (de) 1990-12-05

Family

ID=27316147

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85110642A Expired - Lifetime EP0175940B1 (de) 1984-08-23 1985-08-23 Photoelektrischer Rauchdetektor

Country Status (2)

Country Link
EP (1) EP0175940B1 (de)
DE (1) DE3580817D1 (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19741853A1 (de) * 1997-09-23 1999-03-25 Bosch Gmbh Robert Rauchmelder
GB2342987B (en) * 1998-10-20 2003-03-19 David Appleby Improved smoke sensor with a fault monitoring capability
US6876305B2 (en) 1999-12-08 2005-04-05 Gentex Corporation Compact particle sensor
DE102015004458B4 (de) 2014-06-26 2016-05-12 Elmos Semiconductor Aktiengesellschaft Vorrichtung und Verfahren für einen klassifizierenden, rauchkammerlosen Luftzustandssensor zur Prognostizierung eines folgenden Betriebszustands
DE102014019172B4 (de) 2014-12-17 2023-12-07 Elmos Semiconductor Se Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mit einem kompensierenden optischen Messsystem
DE102014019773B4 (de) 2014-12-17 2023-12-07 Elmos Semiconductor Se Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mittels des Displays eines Mobiltelefons
CN113470290B (zh) * 2021-07-01 2022-03-25 尼特智能科技股份有限公司 一种用于公共场所最短逃生路线的快速生成系统及方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1798135U (de) * 1957-07-27 1959-10-15 Walther & Cie Ag Rauchmelder, insbesondere brandmelder.
GB1129402A (en) * 1966-02-24 1968-10-02 Kidde Walter Co Ltd Improvements in or relating to detectors for smoke and like particles
US3708675A (en) * 1969-09-19 1973-01-02 Furukawa Electric Co Ltd Smoke detector in which air entrance and egress are located in oppositely disposed surfaces which are shaped to cause an air velocity differential
AU3100277A (en) * 1977-01-07 1979-06-07 Gen Electric Optical smoke detector
US4216377A (en) * 1977-06-27 1980-08-05 Nittan Company, Limited Light scattering smoke detector
SE428972B (sv) * 1979-03-07 1983-08-01 Svenska Utvecklings Ab Anordning for detektering av forekommande av svevande, fasta eller vetskeformade partiklar i en gas

Also Published As

Publication number Publication date
DE3580817D1 (de) 1991-01-17
EP0175940A1 (de) 1986-04-02

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