EP0094534B1 - Rauchdetektor nach dem Strahlungs-Extinktions-Prinzip - Google Patents

Rauchdetektor nach dem Strahlungs-Extinktions-Prinzip Download PDF

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Publication number
EP0094534B1
EP0094534B1 EP83104219A EP83104219A EP0094534B1 EP 0094534 B1 EP0094534 B1 EP 0094534B1 EP 83104219 A EP83104219 A EP 83104219A EP 83104219 A EP83104219 A EP 83104219A EP 0094534 B1 EP0094534 B1 EP 0094534B1
Authority
EP
European Patent Office
Prior art keywords
radiation
smoke detector
detector according
reference voltage
pulses
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
EP83104219A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0094534A1 (de
Inventor
Jürg Dr. sc. nat. Muggli
Martin Dr. Sc. Nat. 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 EP0094534A1 publication Critical patent/EP0094534A1/de
Application granted granted Critical
Publication of EP0094534B1 publication Critical patent/EP0094534B1/de
Expired 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
    • 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
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/04—Monitoring of the detection circuits
    • G08B29/043—Monitoring of the detection circuits of fire detection circuits

Definitions

  • the invention relates to a smoke detector with a pulsed operated radiation source for emitting a bundled beam into an area freely accessible to the ambient air, a radiation receiver arranged in the beam, the downstream input amplifier of which generates receive pulses proportional to the received radiation intensity and an evaluation circuit containing an element for generating one with the received pulses comparative reference voltage, an alarm level that triggers an alarm signal for a longer period of time if the received pulses weaken below a predetermined alarm threshold, and a fault level that, if the received pulses weaken faster than the alarm signal that triggers the alarm signal, falls below an alarm threshold less than the alarm threshold triggers an interference signal, and means which change a tracking variable with a time constant greater than one minute so that the difference nz between the level of the received pulses and the reference voltage is minimized, and a first device with which the ratio of the alarm threshold to the reference voltage can be changed.
  • DE-A-28 22 547 discloses a smoke detector in which, as is customary with these so-called “line extinction detectors", the radiation source and radiation receiver are accommodated in two different housings which, depending on the place of use, are at different distances from the walls of the room to be monitored be attached.
  • a fixed alarm threshold is specified.
  • this corresponds to very different smoke densities when the distance between the radiation source and receiver is different. This disadvantage leads to false alarms.
  • slow disturbances in the response behavior of the smoke detector which are caused by aging, pollution, temperature fluctuations and moisture, are eliminated by tracking the reference voltage of the output voltage of the radiation receiver.
  • GB-A-2 059128 describes an optical smoke detector according to the preamble of claim 1, in which slow disturbances due to contamination and aging are also eliminated by adapting the amplification of the output voltage of the radiation receiver to the respective state.
  • the invention has for its object to provide a smoke detector, the sensitivity of which does not depend, or only insignificantly, on the distance between the radiation source and the receiver, changes in the operating state due to contamination, aging and temperature fluctuations are to be rendered ineffective, and the smoke detector should in particular have a reduced sensitivity to interference . In the event of a fault, a fault signal should be issued reliably.
  • FIGS 1 and 2 show circuit examples of preferred embodiments.
  • the radiation source 3 in this case a light or infrared radiation emitting diode (LED), is activated by the pulse generator 1 via a driver stage 2.
  • the current is preferably regulated with the aid of the reference radiation receiver 4 in such a way that the radiation intensity of the pulses assumes a fixed value.
  • T22, R21 and R23 switch the current through LED 3, which is supplied by the capacitor C21.
  • C21 is recharged between the pulses via R24.
  • T21 and R22 regulate the radiation intensity in connection with the reference radiation receiver 4.
  • the radiation pulses falling on the radiation receiver 5 are amplified by the input amplifier 6 and fed to three comparison circuits 7, 8, 9.
  • a two-stage transistor amplifier T61, T62 whose operating point is determined by the resistors R61, R62, and R64, is sufficient as the input amplifier.
  • the differential resistance of the diode D61 together with the feedback resistor R 63 and the resistor R62 determine the gain.
  • the quiescent current through the diode D61 and thus its differential resistance is determined by the voltage U v and the resistor R65. In this way, the gain of the input amplifier 6 can be controlled.
  • the entire amplifier is separated by coupling capacitors C61 and C63.
  • the output of the input amplifier 6 is connected to the positive input of the comparison circuit 9.
  • the voltage U s (interference threshold), which is obtained with the voltage divider R1, R2, 14 from the reference voltage Uref.
  • U s interference threshold
  • a correlation pulse appears at the output of the comparison circuit 9, which is passed on to the clock inputs C of the counters 10 and 15.
  • the capacitance C161 is also discharged with the correlation pulse in the interference circuit 16 with the aid of resistor R161 and transistor T161. If there are no correlation pulses, ie if the output pulses of the input amplifier no longer reach the interference threshold U s the capacitance C161 is charged via the resistor R162 and a fault signal 19 is emitted by the logic circuit 17.
  • the comparison circuit 7 compares the signal at the output of the input amplifier 6 (receive pulses) with the reference voltage U ret . Its output controls the counting direction U / D of the V-up / down counter 11.
  • the digital value Q o ... Q I of the counter is converted in the digital-to-analog converter 12 into an analog voltage, from which a non-linear amplifier 13 the control voltage U v for the amplification of the input amplifier 6 is generated.
  • the counter reading is increased or decreased by one in accordance with the value of the output of the comparison circuit 7.
  • the gain of the input amplifier 6 is changed such that the difference between the level of the received pulses and the reference voltage is minimized, that is to say practically zero.
  • the binary counter 10 divides the frequency of the correlation pulses by a certain factor and uses them to generate the clock pulses of the up-down counter 11.
  • the tracking becomes slow enough to not or only insignificantly compensate for changes in the reception pulses due to the increase in smoke density, but nevertheless due to changes slow dusting, aging and temperature fluctuations. If the up-down counter 11 reaches its lower or upper limit (zero or 21 + 1 -1), further tracking is no longer possible.
  • a fault signal can be derived from the negated carry-out output C out , which assumes the value zero at the counter limits. This value is processed by the logic circuit 17 and a fault signal 19 is generated.
  • Another comparison circuit 8 compares the received pulses E (output of the input amplifier) with the alarm threshold U A. The output of this comparison circuit controls the reset input of the alarm delay counter 15. If the received pulses fall below the alarm threshold U A , the alarm delay counter 15 is no longer reset and the correlation pulses increase the counter reading. After a certain number of pulses, an alarm signal 18 is emitted, however, based on the logic circuit 17, only if a fault signal 19 is not also present at the same time.
  • the level of the up-down counter 11 corresponds to a certain gain of the input amplifier 6 and thus a certain radiation intensity at the radiation receiver 5.
  • This radiation intensity is in turn a good measure of the distance between the radiation source 3 and 5, since they are inversely proportional to the square of this distance behaves.
  • the counter reading Qo ... Q i is therefore characteristic of a certain distance between the radiation source and receiver.
  • the digitally controllable resistor 14 is controlled by the meter reading and thus the ratio of the alarm threshold to the reference voltage is adapted to the different distances. The functional dependence of this ratio on the distance is now preferably chosen such that the alarm threshold always corresponds to the same smoke density. This is possible by a suitable definition of the transfer function of the non-linear amplifier 13.
  • FIG. 2 shows a further circuit of a smoke detector according to the invention.
  • the pulse generator 1 controls the radiation source 3 via the driver stage 2.
  • the transistor T22 and the resistor R21 switch the current through the radiation source 3, which is supplied by the capacitance C21, which in turn is charged between the pulses via the resistor R24.
  • the current through the radiation source is regulated to a specific value with the aid of the Zener diode D21 and the resistor R23.
  • the radiation pulses falling on the radiation receiver 5 are amplified by the input amplifier 6 and fed to the three comparison circuits 7, 8, 9.
  • This amplifier 6 consists of an operational amplifier A61 and the variable feedback resistor R63, with which the gain can be set to a suitable value when the smoke detector is started up.
  • the coupling capacitance C61 separates DC components.
  • the processing of the outputs of the comparison circuits 7, 8, 9 takes place in the same way as in FIG. 1. Reference is made to their description.
  • the output of the digital-to-analog converter 12, on the other hand, is not used to control the input amplifier, but rather directly represents the reference voltage U ret .
  • the (slow) change in the counter reading of the up-down counter 11 tracks the reference voltage U ref in such a way that that the difference between the level of the received pulses and the reference voltage is minimized, i.e. practically zero.
  • the ratio of the alarm threshold to the reference voltage can be set by the variable resistor 14.
  • a switch 141 is provided, which changes the resistance value of the resistor 14 by connecting the resistors R141 or R142 in parallel to R143.
  • a continuously variable resistor eg potentiometer
  • the smoke detectors described have a significantly improved stability even over longer periods of time. Slow changes due to dust, aging of the components and temperature fluctuations are caused by a tracking mechanism is automatically compensated, without the risk of an incorrect alarm triggering and without loss of sensitivity. They are also characterized by a better defined sensitivity in that the ratio of the alarm threshold to the reference voltage is adapted to the distance between the radiation source and receiver.

Landscapes

  • 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)
EP83104219A 1982-05-13 1983-04-29 Rauchdetektor nach dem Strahlungs-Extinktions-Prinzip Expired EP0094534B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH297382 1982-05-13
CH2973/82 1982-05-13

Publications (2)

Publication Number Publication Date
EP0094534A1 EP0094534A1 (de) 1983-11-23
EP0094534B1 true EP0094534B1 (de) 1987-01-14

Family

ID=4245793

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83104219A Expired EP0094534B1 (de) 1982-05-13 1983-04-29 Rauchdetektor nach dem Strahlungs-Extinktions-Prinzip

Country Status (8)

Country Link
US (1) US4559453A (no)
EP (1) EP0094534B1 (no)
JP (1) JPS58214997A (no)
CA (1) CA1208335A (no)
DE (1) DE3369213D1 (no)
ES (1) ES8404535A1 (no)
NO (1) NO159967C (no)
ZA (1) ZA833436B (no)

Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60144458U (ja) * 1984-03-05 1985-09-25 ホーチキ株式会社 火災検出装置
FI854809A (fi) * 1984-12-18 1986-06-19 Hochiki Co Branddetektor som baserar sig pao minskat ljus.
US5144286A (en) * 1990-08-06 1992-09-01 Allen-Bradley Company, Inc. Photosensitive switch with circuit for indicating malfunction
DE69325852T2 (de) * 1992-05-25 2000-01-27 Nohmi Bosai Ltd Feuerdetektor
US5502434A (en) * 1992-05-29 1996-03-26 Hockiki Kabushiki Kaisha Smoke sensor
AU653684B2 (en) * 1992-11-04 1994-10-06 Nohmi Bosai Ltd Smoke detecting apparatus for fire alarm
US5552765A (en) * 1993-07-12 1996-09-03 Detection Systems, Inc. Smoke detector with individually stored range of acceptable sensitivity
US5543777A (en) * 1993-07-12 1996-08-06 Detection Systems, Inc. Smoke detector with individual sensitivity calibration and monitoring
JPH09270085A (ja) * 1996-04-01 1997-10-14 Hamamatsu Photonics Kk 発煙検知装置
GB2319604A (en) * 1996-11-25 1998-05-27 Kidde Fire Protection Ltd Smoke and particle detector
US6504750B1 (en) * 2001-08-27 2003-01-07 Micron Technology, Inc. Resistive memory element sensing using averaging
US6826102B2 (en) * 2002-05-16 2004-11-30 Micron Technology, Inc. Noise resistant small signal sensing circuit for a memory device
US6813208B2 (en) * 2002-07-09 2004-11-02 Micron Technology, Inc. System and method for sensing data stored in a resistive memory element using one bit of a digital count
DE60325254D1 (de) * 2002-08-23 2009-01-22 Gen Electric Mmuner alarmsignalerzeugungs-rauchdetektor
KR100778153B1 (ko) 2006-11-14 2007-11-22 주식회사 가스트론 수신반까지의 전선의 길이에 적응하여 출력전류를 일정하게조절하는 회로를 가진 가스누설 감지기
JP5216767B2 (ja) * 2007-07-19 2013-06-19 ホーチキ株式会社 警報器
JP5795064B2 (ja) 2010-07-13 2015-10-14 ボルボ コンストラクション イクイップメント アーベー 建設機械の旋回制御装置及びその方法
DE102011108389A1 (de) * 2011-07-22 2013-01-24 PPP "KB Pribor" Ltd. Rauchdetektor
GB2537940B (en) 2015-05-01 2018-02-14 Thorn Security Fire detector drift compensation
WO2019089450A1 (en) * 2017-10-30 2019-05-09 Carrier Corporation Compensator in a detector device
CN113538837B (zh) * 2021-07-08 2022-09-13 深圳市豪恩安全科技有限公司 光电感烟探测方法、探测装置及计算机可读存储介质
CN113990023B (zh) * 2021-10-26 2023-01-24 无锡商业职业技术学院 一种用于光电式烟雾探测器的自校准、补偿电路和方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011458A (en) * 1975-10-09 1977-03-08 Pyrotector, Incorporated Photoelectric detector with light source intensity regulation
JPS5829558B2 (ja) * 1977-05-23 1983-06-23 ホーチキ株式会社 減光式感知器
JPS53144387A (en) * 1977-05-23 1978-12-15 Hochiki Co Depreciation type detector
US4185278A (en) * 1977-09-22 1980-01-22 HF Systems, Incorporated Obscuration type smoke detector
GB2044504B (en) * 1979-03-17 1983-04-20 Hochiki Co Count discriminating fire detector
JPS5631625A (en) * 1979-08-24 1981-03-31 Hochiki Corp Smoke detector of photoelectronic type
JPS56133548A (en) * 1980-03-25 1981-10-19 Shigeo Kobayashi Fan device for air exhaust
JPS5722541A (en) * 1980-07-15 1982-02-05 Matsushita Electric Works Ltd Light reduction type smoke sensor

Also Published As

Publication number Publication date
JPS58214997A (ja) 1983-12-14
ES522683A0 (es) 1984-04-16
DE3369213D1 (en) 1987-02-19
ES8404535A1 (es) 1984-04-16
ZA833436B (en) 1984-01-25
NO159967B (no) 1988-11-14
JPH0441395B2 (no) 1992-07-08
NO159967C (no) 1989-02-22
CA1208335A (en) 1986-07-22
NO831682L (no) 1983-11-14
EP0094534A1 (de) 1983-11-23
US4559453A (en) 1985-12-17

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