EP0130992B1 - Photoelektrischer rauchdetektor - Google Patents

Photoelektrischer rauchdetektor Download PDF

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Publication number
EP0130992B1
EP0130992B1 EP83902981A EP83902981A EP0130992B1 EP 0130992 B1 EP0130992 B1 EP 0130992B1 EP 83902981 A EP83902981 A EP 83902981A EP 83902981 A EP83902981 A EP 83902981A EP 0130992 B1 EP0130992 B1 EP 0130992B1
Authority
EP
European Patent Office
Prior art keywords
signal
circuit
radiation
smoke
smoke detector
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
EP83902981A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0130992A1 (de
Inventor
Hannes Güttinger
Martin Labhart
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
Application filed by Cerberus AG filed Critical Cerberus AG
Publication of EP0130992A1 publication Critical patent/EP0130992A1/de
Application granted granted Critical
Publication of EP0130992B1 publication Critical patent/EP0130992B1/de
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors
    • G08B29/185—Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system
    • 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
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors
    • G08B29/20—Calibration, including self-calibrating arrangements
    • G08B29/22—Provisions facilitating manual calibration, e.g. input or output provisions for testing; Holding of intermittent values to permit measurement
    • 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 photoelectric smoke detector according to the preamble of claim 1.
  • a smoke detector is known from EP-A-0 011 205.
  • the smoke detector can e.g. be designed as a scattered radiation detector, in which the radiation scattered on smoke particles is evaluated, or as a radiation extinction detector, which uses radiation attenuation or absorption by smoke particles, or also as a photoacoustic smoke detector, in which the smoke particles emit acoustic impulses when absorbed by radiation impulses, which are emitted by an acoustic -electric converters are converted into electrical impulses, such as in EP-A-0 014 251.
  • the smoke detector can serve as a smoke sensor in which the value of the smoke signal emitted is a measure of the smoke density, or as a smoke detector which signals the occurrence of a certain smoke density.
  • electromagnetic radiation which is to be understood as visible light, infrared or ultraviolet radiation
  • a measurement volume e.g. by means of a light-emitting diode (LED)
  • the radiation scattered on smoke particles in the measurement volume is picked up by a scatter radiation receiver arranged outside the radiation range of the radiation source, and by means of an evaluation circuit, a smoke alarm signal is given if the scatter radiation level exceeds a certain threshold.
  • LED light-emitting diode
  • a crucial problem here is to ensure that a smoke alarm signal is only triggered by scattered radiation from smoke particles, but not by interfering radiation entering the measurement volume, which is also picked up by the radiation receiver and simulates the presence of radiation-scattering smoke particles. This is particularly important for smoke detectors in which only a limited radiation intensity is available in the measurement volume, for example in smoke detectors in which the radiation is guided into and removed from the measurement volume by means of radiation-conducting elements or fiber optics, e.g. described in DE-A-30 37 636.
  • the object of the invention is to avoid the aforementioned disadvantages of the prior art and, moreover, to provide a photoelectric smoke detector which, with very low smoke densities, has a greater sensitivity even with reduced radiation intensity and power and has improved immunity to interference.
  • the invention is defined in more detail in the characterizing part of claim 1.
  • a detector unit D is radiation-conducting elements or light guides L, and L 2 connected to an evaluation circuit A.
  • the type of light guide is expediently adapted to the radiation used.
  • a plurality of detector units can also be connected in parallel to the evaluation circuit A by means of the same light guide via known branching elements or by means of different light guides.
  • a control circuit 1 provided in the evaluation circuit A intermittently controls a radiation source 2 designed as a radiation-emitting diode LED, for example with a frequency of 0.1-40 kHz.
  • the switch-on time is preferably of the same order of magnitude as the switch-off time.
  • the radiation emitted by the radiation source 2 depending on the type of LED visible light, infrared or ultraviolet radiation, is coupled into the light guide L, and guided via this to the detector unit D.
  • a collimation device 4 is arranged, ie a special optic that collimates the radiation emerging from the light guide into an at least approximately parallel radiation beam.
  • a further collimation device 6 whose reception area is oriented in such a way that it receives radiation scattered on smoke particles from a scattering volume 7 and feeds the input 8 of a second light guide L 2 , which feeds the received scattered radiation from a solar cell 9.
  • This solar cell converts the received radiation, ie the optical signal, into an electrical signal, which is amplified by a receiving amplifier 10.
  • the amplifier output signal is received by a signal processing circuit which, on the other hand, receives a reference signal from the control circuit 1 via a line 12 and which only forwards a signal to the downstream display circuit 13 when the emitted and received radiation are in coincidence.
  • This display circuit 13 when used as a smoke sensor, indicates the smoke concentration according to the value of the scattered radiation signal, or it triggers an alarm device 14, when used as a fire detector, if the scattered radiation signal exceeds a predetermined threshold, and thus indicates a fire outbreak.
  • FIG. 2 shows the construction of the detector unit D of a scattered radiation smoke detector which is particularly suitable for fire detection.
  • a plastic base plate 20 carries an air-permeable housing 21 enclosing the measuring chamber M and a support element 22 inside.
  • a known connection or plug connection C is provided in the base plate 20, which is used to connect the light guides L and L 2 to the light guide Connections 23 and 28 inside the detector is used, the ends of which interact with the collimation devices 24 and 26.
  • a plurality of diaphragms 25 for shielding the residual radiation from the collimator 26 are placed in the central part of the carrier element.
  • the optical arrangement in the interior of the housing 21 is surrounded by an air-permeable, but radiation-absorbing, labyrinth-like element 27, which can have nested slats or radiation-absorbing ribs 29 on the surfaces, for example.
  • a suitable radiation trap 30 can be provided to catch the direct radiation, as well as a corresponding radiation trap 31 at the end of the reception area.
  • the invention is particularly advantageous for those detector units in which the supply and signal transmission is carried out by means of optical fibers or fiber optics, where usually only a small radiation power is available, it also proves to be particularly advantageous in the case of classic smoke detectors with electrical transmission , especially when a particularly high sensitivity is required, ie when the lowest smoke concentrations are to be detected.
  • the radiation source 2 takes the place of the device 4
  • the radiation receiver 9 takes the place of the device 6, and the light guide connections L 1 and L 2 are omitted.
  • the construction of such smoke detectors can be carried out, for example, in accordance with US Pat. No. 4,181,439.
  • FIG. 3 shows an example of a signal processing circuit 11 suitable for the smoke detector according to FIGS. 1 and 2.
  • the output signal of the receiver amplifier and signal converter 10 is fed via a low-noise preamplifier 15 to a frequency filter 16, which is preferably transparent to the frequency of the control circuit 1 and dampens the noise.
  • Preamplifier 15 and frequency filter 16 can also be combined to form a frequency-selective amplifier.
  • the filtered signal arrives at a phase-sensitive circuit 17, which on the other hand is controlled by the control circuit 1 via a trigger circuit 32 and a phase shifter 33.
  • This phase-sensitive circuit 17 has the effect that the polarity of the signal coming from the receiver 10 is maintained, or vice versa, depending on the phase position of the alternating signal of the control circuit 1.
  • the polarity is maintained during the switch-on phases of the radiation source, ie the receiver signal is passed on unchanged, but vice versa during the switch-off phases in between, ie a positive signal is converted into a negative one and vice versa a negative signal is turned into a positive one.
  • That so changed output signal of the phase-sensitive circuit 17 now arrives at a downstream integration circuit 18 with a predetermined time constant, which can be adjustable, for example by means of a capacitor 19.
  • the entire signal processing circuit 11 can also be designed as a single hybrid circuit or a corresponding device, for example as so-called lock-in amplifier.
  • the phase-sensitive circuit 17 receives the amplified signal a of the control circuit 1 at its control input, with the phase shifter 33 being able to correct any phase shifts in the receiver signal during signal passage, and the amplified and filtered receiver signal b at its signal input.
  • the output signal c of the phase-sensitive circuit 17 appears at the output and is integrated by the integration circuit 18 into an output signal d. No scattered radiation is received during the period X.
  • the signal b is then a pure noise signal without any frequency component of the control circuit 1.
  • the rate of increase is determined by the time constant of the integration circuit 18 and can be adapted to the expected interference frequency by a suitable choice or setting of the time constant, so that a certain increase is achieved by a certain number of successive synchronous receiver pulses, but never by irregularly occurring interference pulses becomes.
  • a predefined threshold d o ie the alarm threshold is reached, a.
  • Display circuit 13 controlled in a known manner, which triggers a visual, acoustic or electrical alarm signal.
  • the circuit can be simplified if the control voltage output by the control circuit 1 is rectangular.
  • the alternating signal coming out of the circuit 32 designed as a simple frequency filter fluctuates periodically back and forth between the extreme values (+1) and (-1).
  • the phase-sensitive circuit can then be designed as a simple multiplication circuit 17, since the alternating multiplication by (+1) and (-1) has exactly the required effect, namely the polarity reversal of the signal in the rhythm of the control signal.
  • the invention has been described above using a scattered radiation smoke detector.
  • the inventive idea can be analog, with similar advantages also with other types of photoelectric smoke detectors, such as Use radiation absorbance or photoacoustic smoke detectors.
  • the adjustment measures required for this are familiar to the person skilled in the art.
  • it can be achieved that a display or an alarm signal with exceptional security is only triggered if the receiver signal is exactly synchronous, i.e. is absolutely the same frequency and in phase with the signal controlling the radiation source, but no other interference signals.
  • the circuit also works safely and reliably when the receiver signal is extremely weak and the noise completely covers the useful signal, so that lower smoke concentrations can be detected or measured than before.
  • the invention deliberately deviates from the previous tendency, which is obvious to the person skilled in the art, to improve the signal / noise ratio by increasing the radiation pulse height and reducing the radiation pulse width.
  • the circuit according to the invention works with particular advantage even in cases where it is expedient or necessary to choose the pulse widths in the same order of magnitude as the intermediate times.
  • the smoke detector described preferably serves as a fire detector, but is also suitable for other uses, e.g. for smoke gas monitoring, smoke density measurement etc.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
EP83902981A 1983-01-11 1983-10-05 Photoelektrischer rauchdetektor Expired EP0130992B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH119/83 1983-01-11
CH119/83A CH660244A5 (de) 1983-01-11 1983-01-11 Photoelektrischer rauchdetektor und dessen verwendung.

Publications (2)

Publication Number Publication Date
EP0130992A1 EP0130992A1 (de) 1985-01-16
EP0130992B1 true EP0130992B1 (de) 1987-04-08

Family

ID=4179681

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83902981A Expired EP0130992B1 (de) 1983-01-11 1983-10-05 Photoelektrischer rauchdetektor

Country Status (7)

Country Link
US (1) US4647786A (enrdf_load_stackoverflow)
EP (1) EP0130992B1 (enrdf_load_stackoverflow)
JP (1) JPS60500467A (enrdf_load_stackoverflow)
CH (1) CH660244A5 (enrdf_load_stackoverflow)
DE (1) DE3370888D1 (enrdf_load_stackoverflow)
NO (1) NO159424C (enrdf_load_stackoverflow)
WO (1) WO1984002790A1 (enrdf_load_stackoverflow)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4839527A (en) * 1986-10-28 1989-06-13 Alan Leitch Optical-fibre smoke detection/analysis system
GB9014015D0 (en) * 1990-06-23 1990-08-15 Dennis Peter N J Improvements in or relating to smoke detectors
US5546074A (en) * 1993-08-19 1996-08-13 Sentrol, Inc. Smoke detector system with self-diagnostic capabilities and replaceable smoke intake canopy
US6501810B1 (en) 1998-10-13 2002-12-31 Agere Systems Inc. Fast frame synchronization
JP3330438B2 (ja) * 1993-12-16 2002-09-30 能美防災株式会社 煙感知器およびその調整装置
US5629458A (en) * 1996-07-26 1997-05-13 Alliedsignal Inc. Process for the preparation of 2 2 2 trifluoroethanol
GB2367358B (en) * 1997-06-30 2002-05-15 Hochiki Co Smoke detecting apparatus
DE19741853A1 (de) * 1997-09-23 1999-03-25 Bosch Gmbh Robert Rauchmelder
US7324004B2 (en) * 2003-10-29 2008-01-29 Honeywell International, Inc. Cargo smoke detector and related method for reducing false detects
EP2093734B1 (de) * 2008-02-19 2011-06-29 Siemens Aktiengesellschaft Rauchmelder mit zeitlicher Auswertung eines Rückstreusignals, Testverfahren für Funktionsfähigkeit eines Rauchmelders
DE102013213721B4 (de) * 2013-03-07 2015-10-22 Siemens Schweiz Ag Brandmeldeanlage für den Einsatz in einem Nuklearbereich oder EX-Bereich
US10943449B2 (en) * 2016-11-11 2021-03-09 Carrier Corporation High sensitivity fiber optic based detection
CN115223323B (zh) * 2022-07-18 2023-05-23 深圳市千宝通通科技有限公司 光电式烟感传感器、烟感传感器自检方法及烟感报警器

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU493347B1 (en) * 1974-04-23 1976-10-21 Cabili Electronics Pty. Ltd False alarm inhibitor
US4206454A (en) * 1978-05-08 1980-06-03 Chloride Incorporated Two channel optical flame detector
JPS609914Y2 (ja) * 1978-11-14 1985-04-05 能美防災工業株式会社 光電式煙感知器
CH638331A5 (de) * 1979-02-22 1983-09-15 Cerberus Ag Rauchdetektor.

Also Published As

Publication number Publication date
NO159424C (no) 1988-12-21
NO159424B (no) 1988-09-12
DE3370888D1 (en) 1987-05-14
JPH0568000B2 (enrdf_load_stackoverflow) 1993-09-28
WO1984002790A1 (en) 1984-07-19
NO842034L (no) 1984-07-19
US4647786A (en) 1987-03-03
CH660244A5 (de) 1987-03-31
JPS60500467A (ja) 1985-04-04
EP0130992A1 (de) 1985-01-16

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