EP0030621A1 - Détecteur de fumée à ionisation ayant une fiabilité opérationnelle améliorée - Google Patents

Détecteur de fumée à ionisation ayant une fiabilité opérationnelle améliorée Download PDF

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Publication number
EP0030621A1
EP0030621A1 EP80106923A EP80106923A EP0030621A1 EP 0030621 A1 EP0030621 A1 EP 0030621A1 EP 80106923 A EP80106923 A EP 80106923A EP 80106923 A EP80106923 A EP 80106923A EP 0030621 A1 EP0030621 A1 EP 0030621A1
Authority
EP
European Patent Office
Prior art keywords
voltage
detector
operating voltage
transistor
resistor
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.)
Granted
Application number
EP80106923A
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German (de)
English (en)
Other versions
EP0030621B1 (fr
Inventor
Andreas Scheidweiler
Peter Müller
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
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Cerberus AG
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Publication date
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Priority to AT80106923T priority Critical patent/ATE11345T1/de
Publication of EP0030621A1 publication Critical patent/EP0030621A1/fr
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Publication of EP0030621B1 publication Critical patent/EP0030621B1/fr
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas

Definitions

  • the present invention relates to an ionization smoke detector with at least one ionization chamber operated with low voltage with a measuring and a counterelectrode sensor, to which "chamber the surrounding air has practically free access and which has at least one radioactive source for generating ions, and an electrical one Circuit for triggering an alarm, which detector is connected via lines to a signaling center that delivers a detector operating voltage to the lines:.
  • ionization smoke detectors are the most widely used early warning detectors.
  • the main advantages of this type of detector include its universal applicability and its simple and robust mechanical construction. Since the detectors must respond quickly and safely in the event of a fire, but on the other hand they must not trigger false alarms, high demands are placed on their reliability.
  • FIG. 1 shows the circuit of a typical low-voltage smoke detector, in which the mession chamber is operated in series with a load resistor, preferably a saturated reference chamber. The connection point of the two chambers is connected to the control electrode of a cold cathode tube. The voltage drop across the measuring chamber is approx. 80 V in the idle state. When smoke enters the measuring chamber, this voltage increases by approx. 50 V and thus reaches the ignition voltage of the cold cathode tube. This leads to the triggering of a current flow between the anode and cathode, which can be evaluated via a relay for triggering the alarm.
  • the chamber voltage of approx. 100 V required to operate the low-voltage ionization smoke detectors means that high electrical field strengths of a few 100 V / cm occur at the measuring electrode.
  • the dust particles that are always present in the air are therefore deposited electrostatically on the electrodes, which means that the electrodes are covered with a gradually thicker layer of dust. If these dusts are electrically non-conductive material, which is often the case especially in the dry winter periods, the ion current in the measuring chamber is blocked and a false alarm can be triggered. This makes it necessary to clean the detectors frequently, which is very expensive.
  • FIG. 2 shows the circuit of a typical low-voltage ionization smoke detector.
  • the voltage across the measuring chamber is also the gate voltage for a field effect transistor. It is selected so that the transistor is de-energized in the idle state.
  • the controlled rectifier (SCR) is therefore also blocked and the relay is not energized. If flue gases penetrate the measuring chamber, the chamber voltage increases and causes an overflow After a certain threshold, the SCR is fired, which triggers the relay alarm.
  • the object of the present invention is to remedy the disadvantages mentioned above of the known ionization smoke detectors, and in particular to provide an ionization smoke detector with increased operational reliability, which reduces the tendency of the detectors to become dirty due to a low field strength in the ionization chamber, so that the service intervals can be selected for a long time that requires a smaller amount of radioactive material than high-voltage detectors and that is insensitive to electromagnetic interference.
  • the detector has a converter which reduces the detector operating voltage to the sensor operating voltage in such a way that it is at least five times smaller than the detector operating voltage so that it has a first switching element which is connected to the sensor operating voltage and is controlled by the voltage drop across the ionization chamber and which is conductive when a certain smoke density is exceeded is and the sensor operating voltage decreases, and that it has a second switching element which is connected to the detector operating voltage and is controlled by the sensor operating voltage and which becomes conductive when the sensor operating voltage falls below a predetermined value and triggers an alarm signal.
  • the ionization smoke detector has means which actuate the switch when opening the field effect transistor in such a way that the control voltage of the cold cathode tube rises slowly until the ignition voltage is reached and the cold cathode tube ignites.
  • the switch consists of a transistor which conducts and is saturated in the idle state, a capacitor being connected between the collector and emitter of the transistor and a resistor being connected between the collector of the transistor and the anode of the cold cathode tube is, the time constant R x C> 2s, preferably> 5s and in particular> 10s.
  • the converter consists of a resistor, a zener diode and the base-emitter path of the transistor.
  • FIG. 3 shows an example of an ionization smoke detector according to the invention.
  • a mession chamber MK accessible to the outside atmosphere is in series with a load resistance R 6 .
  • the connection point between the mession chamber MK and the load resistor R 6 is with the gate electrode trode G of a field effect transistor T l connected, the drain-source path of the FET T 1 is connected in parallel with the Z-diode ZD 1 to the measuring chamber load resistance path.
  • the detector operating voltage U 1 of approximately 200 V , for example, applied to the detector via the lines L 1 and L 2 is fed to a converter T, which reduces the detector operating voltage U 1 to the sensor operating voltage U 2 .
  • the low voltage output of the converter T is connected both to one electrode of the measuring chamber MK and to a discriminator D, which is used to control a switch S which is connected to the control electrode St of the cold cathode tube KR, which is connected between the lines L 1 and L 2 , acts.
  • the control electrode St of the cold cathode tube KR is connected to the output L of the switch S via the resistor R 2 to the line L 1 and via the capacitor C to the line L 2 .
  • the discriminator D is designed in such a way that, when the sensor operating voltage U 2 falls below a certain threshold value, it actuates the switch S, the output of which, in the idle state, holds the control electrode voltage U St of the cold cathode tube KR below the ignition voltage (preferably more than 50 V below) in such a way that the capacitor C can charge via the resistor R 2 until the ignition voltage is reached and the cold cathode tube KR is ignited.
  • the current rise that occurs in lines L 1 and L 2 can be evaluated in the signal center as an alarm signal.
  • FIG. 1 A preferred embodiment of a circuit of an ionization smoke detector according to the invention is explained in more detail in FIG.
  • the working resistance R 6 in series with the measuring chamber MK is designed as a reference ionization chamber RK which is difficult to access from the outside atmosphere and operates in the saturation region.
  • the detector operating voltage U 1 is fed to a voltage stabilizer circuit consisting of a resistor R 1, a Zener diode ZD 2 and the base-emitter path of a transistor T 2 .
  • This voltage stabilizer circuit provides the sensor operating voltage U 2 necessary for the operation of the low voltage sensor.
  • the FET T 1 switches through and an additional current flows through the resistor R 1 .
  • the sensor operating voltage U 2 is reduced to such an extent that the Zener voltage of the Zener diode ZD 2 is undershot, as a result of which the base current of the transistor T 2 is interrupted, so that it blocks.
  • the capacitor C is charged via the resistor R 2 .
  • the voltage U St across the capacitor C reaches the ignition voltage of the cold cathode the tube KR, this ignites and a strong current flows over the lines L 1 , L 2 ; this current flow can be evaluated to Alarmgebun g in the central station Z.
  • the time constant of the element R 2 , C is selected so that after the transistor T 2 is turned off, the ignition voltage of the control electrode St is only reached after about 2 seconds. Short-term electrical disturbances, which lead to the opening of the field effect transistor T 1 , do not trigger an alarm, since the ignition voltage of the cold cathode tube KR is not reached. While the charging of the capacitor C via the resistor R 2 takes place slowly, an immediate discharge of the capacitor C is carried out when the field effect transistor T 1 is closed , since this is short-circuited via the transistor T 2 .
  • the time constant can be adjusted by changing the R 2 and / or C operating conditions of the smoke detector, for example, several seconds or set to about ten seconds. Repeated short bursts of smoke, such as those caused by heavy tobacco smoke, cannot lead to a false alarm, since the charges C cannot accumulate due to the immediate discharge of the charges.
  • Zener diode ZD 2 is placed between the emitter of the transistor T 2 and the line L 2 and the base of the transistor T 2 is connected directly to the point A.
  • the resistor R 5 can thus be omitted.
  • the open circuit voltage at the control electrode St of the cold cathode tube KR corresponds approximately to the Zener voltage and a lower collector-emitter voltage at the transistor T 2 is necessary for the ignition of the cold cathode tube.
EP80106923A 1979-12-14 1980-11-10 Détecteur de fumée à ionisation ayant une fiabilité opérationnelle améliorée Expired EP0030621B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80106923T ATE11345T1 (de) 1979-12-14 1980-11-10 Ionisationsrauchmelder mit erhoehter betriebssicherheit.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1107779 1979-12-14
CH11077/79 1979-12-14

Publications (2)

Publication Number Publication Date
EP0030621A1 true EP0030621A1 (fr) 1981-06-24
EP0030621B1 EP0030621B1 (fr) 1985-01-16

Family

ID=4369809

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80106923A Expired EP0030621B1 (fr) 1979-12-14 1980-11-10 Détecteur de fumée à ionisation ayant une fiabilité opérationnelle améliorée

Country Status (7)

Country Link
US (1) US4364031A (fr)
EP (1) EP0030621B1 (fr)
JP (1) JPS5694497A (fr)
AT (1) ATE11345T1 (fr)
CA (1) CA1148279A (fr)
DE (1) DE3069987D1 (fr)
YU (1) YU314380A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014019773A1 (de) 2014-12-17 2016-06-23 Elmos Semiconductor Aktiengesellschaft Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mittels des Displays eines Mobiltelefons
DE102014019172A1 (de) 2014-12-17 2016-06-23 Elmos Semiconductor Aktiengesellschaft Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mit einem kompensierenden optischen Messsystem

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH681932A5 (fr) * 1990-12-04 1993-06-15 Cerberus Ag
JP3128633B2 (ja) * 1992-05-25 2001-01-29 能美防災株式会社 イオン化式煙感知器
FR2872914B1 (fr) * 2004-07-07 2006-10-13 Univ Rennes I Etablissement Pu Capteur pour la detection et/ou la mesure d'une concentration de charges electriques contenues dans une ambiance, utilisations et procede de fabrication correspondants
US8101130B2 (en) * 2006-09-15 2012-01-24 Applied Nanotech Holdings, Inc. Gas ionization source

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521263A (en) * 1966-02-22 1970-07-21 Cerberus Ag Ionization fire alarm and improved method of detecting smoke and combustion aerosols

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK101900C (da) * 1961-12-30 1965-06-08 Danske Securitas As Elektrisk alarmanlæg, fortrinsvis til brandalarmering.
JPS446089Y1 (fr) * 1966-03-30 1969-03-05
CH489070A (de) * 1969-03-27 1970-04-15 Cerberus Ag Werk Fuer Elektron Ionisationsfeuermelder
US3657713A (en) * 1969-06-02 1972-04-18 Nittan Co Ltd Device for testing ionization smoke detector
US3797008A (en) * 1971-02-04 1974-03-12 Nittan Co Ltd Fire detecting system
CH570016A5 (fr) * 1973-03-30 1975-11-28 Cerberus Ag
JPS51100085U (fr) * 1975-02-10 1976-08-11
US4017852A (en) * 1976-06-24 1977-04-12 Honeywell Inc. Apparatus for supervising leads interconnecting a plurality of self-contained abnormal condition sensing and alarm annunciating units

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521263A (en) * 1966-02-22 1970-07-21 Cerberus Ag Ionization fire alarm and improved method of detecting smoke and combustion aerosols

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014019773A1 (de) 2014-12-17 2016-06-23 Elmos Semiconductor Aktiengesellschaft Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mittels des Displays eines Mobiltelefons
DE102014019172A1 (de) 2014-12-17 2016-06-23 Elmos Semiconductor Aktiengesellschaft Vorrichtung und Verfahren zur Unterscheidung von festen Objekten, Kochdunst und Rauch mit einem kompensierenden optischen Messsystem

Also Published As

Publication number Publication date
ATE11345T1 (de) 1985-02-15
EP0030621B1 (fr) 1985-01-16
JPS6242320B2 (fr) 1987-09-08
JPS5694497A (en) 1981-07-30
CA1148279A (fr) 1983-06-14
US4364031A (en) 1982-12-14
DE3069987D1 (en) 1985-02-28
YU314380A (en) 1983-10-31

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