EP0014779A1 - Smoke detector comprising a pulse evaluating circuit - Google Patents

Smoke detector comprising a pulse evaluating circuit Download PDF

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Publication number
EP0014779A1
EP0014779A1 EP79200721A EP79200721A EP0014779A1 EP 0014779 A1 EP0014779 A1 EP 0014779A1 EP 79200721 A EP79200721 A EP 79200721A EP 79200721 A EP79200721 A EP 79200721A EP 0014779 A1 EP0014779 A1 EP 0014779A1
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Prior art keywords
radiation
counter
pulses
smoke detector
output
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EP79200721A
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German (de)
French (fr)
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EP0014779B1 (en
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Erwin Tresch
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Cerberus AG
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Cerberus AG
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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
    • G08B17/103—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

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  • the invention relates to a smoke detector with a pulsed radiation source, a radiation receiver which is arranged outside the direct radiation region of the radiation source and which is acted upon by scattered radiation in the presence of smoke in the radiation region and emits output signals, and an evaluation circuit which is capable of triggering a signal when radiation pulses of the radiation source and output pulses of the Radiation recipient are in coincidence.
  • Such a smoke detector is known, for example, from US Pat. No. 3,316,410.
  • a radiation source is controlled by a pulse generator and emits short-lasting radiation pulses.
  • the evaluation circuit connected to the scattered radiation receiver is controlled by the pulse generator of the radiation source in such a way that, when scattered radiation is picked up, it can only output an output signal during the pulse phases of the radiation source. Interference pulses that occur between the radiation pulses are therefore blocked in the evaluation circuit and cannot lead to the triggering of a signal.
  • the disadvantage here is that interference pulses which occur accidentally during the same time as the radiation pulses can trigger a faulty signal.
  • Such a smoke detector is less prone to faulty signaling and accordingly shows improved operational reliability, however, if several interference pulses occur in succession, it can still happen that several of these interference pulses coincide with the radiation pulses and still cause a faulty signal.
  • the invention is based on the object of eliminating the disadvantages of known smoke detectors and avoiding faulty signaling as much as possible as a result of the occurrence of interference pulses and thus further improving operational safety, in particular when used as a fire detector.
  • the invention is characterized in that the evaluation circuit has a counting device which counts both the radiation source pulses and the output pulses of the radiation receiver, and resets the counter to zero after any radiation pulse in the event of an odd-numbered counter reading, but triggers a signal when a predetermined even-numbered counter reading is reached .
  • the invention takes advantage of the fact that when smoke is present in the radiation area, each radiation pulse must always correspond to a corresponding output pulse from the radiation receiver. Are now from If the radiation source pulses and the output pulses of the radiation receiver are counted in a counting device, the counter must have an even number after each radiation pulse. An odd-numbered counter reading is an unmistakable sign that there is no receive pulse. In this case, the evaluation circuit is automatically reset to zero so that the counter cannot reach the counter reading required for signaling. The counter is locked when there is no radiation source pulse.
  • the invention is explained with reference to the circuit of an embodiment shown in the figure.
  • the mechanical construction of the R detector can also be carried out in a known manner, for example as described in Swiss Patent No. 592 932.
  • the radiation transmitter consists of a pulse generator 1 of a known type which, for example, produces transmission pulses of 100 pS duration and a pulse interval of one second, which are fed to a power transistor 2.
  • the parallel connection of a load resistor 3 and a light- or infrared-emitting diode 4 is connected in series with a resistor 5 at the transistor output.
  • the diode 4 emits radiation pulses in the rhythm of the pulse generator 1 into the stray volume of the smoke detector.
  • 2 coincidence pulses are output via a line K from the output of the power transistor taken and supplied to the logic correlation circuit L.
  • the radiation receiving part A contains a storage capacitor 13 and a solar cell 6 which, in the presence of smoke in the scattering volume of the detector, receives scattered radiation in the rhythm of the radiation pulses of the diode 4.
  • a load resistor 7 is connected in parallel with the solar cell 6.
  • the output pulses from the solar cell 6 are fed via a capacitor 8 to an amplifier 9, for example an operational amplifier with a degree of amplification 10 3 , the output signals of which are fed to the logic correlation circuit L via a capacitor 11 with an associated bleeder resistor 12 .
  • the received pulses E emitted by the radiation receiving part A are flattened exponentially by a suitable choice of the frequency response of the amplifier and the solar cell 6.
  • the logic correlation circuit L contains two AND gates 14 and 15 and an OR gate 16.
  • the first AND gate 14 is supplied with the incidence pulses K of the radiation transmitter S at its first input, while the other AND gate 15 receives the receive pulses at one input of the radiation receiving part A receives.
  • the output of this AND gate 15 is led to an input of the OR gate 16, the other input of which also receives the coincidence pulses K.
  • the output of the OR gate 16 is connected to the counter input C of the binary counter B. Both the received pulses E and the coincidence pulses K are therefore counted by the counter B, interference from both types of pulse being avoided by the flattened shape of the E pulse.
  • the counter can be of the type Motorola MC14024, for example.
  • Counter B has various outputs for the individual digits of the binary counter reading, for example an output Q 0 for the first bit or the final digit and an output Q n for the nth or nth digit of the binary number.
  • the exit Q 0 is now connected to the other two inputs of the two AND gates 14 and 15, while the output of the AND gate 14 is connected to a reset input of the binary counter B, so that the counter status is reset to zero as soon as at the output of the AND -Tores 14 a signal occurs.
  • the output Q 0 is connected to the line L 1 via a delay capacitor 17.
  • This circuit has the effect that, without the presence of smoke in the scatter volume of the detector, i.e. if there is no receive pulse E via OR gate 16 at the counter input C of counter B, only one coincidence pulse is counted at the start of each transmit pulse. Signal 1 is therefore present at output Q 0 . Immediately after the coincidence pulse has elapsed, a signal is produced at the output of the AND gate 14, so that the counter B is reset to zero via a reset input R. In the absence of stray radiation, ie in the absence of receive pulses, counter B does not count further.
  • the control electrode of a thyristor 19 is connected to the n.
  • Output Q of the counter B via a resistor 18, which is connected in series with a resistor 20 and a display device 21, for example a light-emitting diode, between the lines L I and L 2 .
  • a resistor 18 which is connected in series with a resistor 20 and a display device 21, for example a light-emitting diode, between the lines L I and L 2 .
  • the thyristor 19 is switched through and an alarm current flows, which actuates the display device 21 and thus the presence of Smoke signals.
  • an alarm current also flows from the connecting terminals of the detector to the center, which can also be evaluated there for signaling in a known manner.
  • logic correlation circuit L can also be designed as an integrated circuit with the same function.
  • the circuit described thus achieves the advantage that an alarm signal can only be triggered if both a coincidence pulse taken from the radiation transmitter and a receive pulse supplied by the radiation receiver arrive at the same time or within a short delay time and when such correlated receive pulses occur a predetermined number of times occur following.
  • a coincidence pulse taken from the radiation transmitter and a receive pulse supplied by the radiation receiver arrive at the same time or within a short delay time and when such correlated receive pulses occur a predetermined number of times occur following.
  • the signaling is automatically blocked. This correlated multi-pulse dependency therefore significantly improves the immunity to interference.

Abstract

A smoke detector containing a radiation source operating in a pulsed mode and a scattered radiation receiver connected in a coincidence circuit. This circuit contains a counter which counts both the radiation pulses and the incoming scattered radiation pulses. With undisturbed operation this counter, following each radiation pulse, has an even numbered counter state. The appearance of an uneven numbered counter state is indicative of the presence of spurious pulses and leads to resetting of the counter to null, so that there is prevented attainment of a counter state adequate for tripping an alarm signal. On the other hand, with the presence of a predetermined even numbered counter state there is triggered an alarm. Such smoke detector is almost immune to spurious pulses and does not tend to trigger faulty alarm signals.

Description

Die Erfindung betrifft einen Rauchdetektor mit einer impulsweise betriebenen Strahlungsquelle, einem ausserhalb des direkten Strahlungsbereiches der Strahlungsquelle angeordneten, bei Anwesenheit von Rauch im Strahlungsbereich durch Streurtrahlung beaufschlagten und Ausgangssignale abgebenden Strahlungsempfänger und einer Auswerteschaltung, welche ein Signal auszulösen vermag, wenn Strahlungsimpulse der Strahlungsquelle und Ausgangsimpulse des Strahlunasempfängers in Koinzidenz sind.The invention relates to a smoke detector with a pulsed radiation source, a radiation receiver which is arranged outside the direct radiation region of the radiation source and which is acted upon by scattered radiation in the presence of smoke in the radiation region and emits output signals, and an evaluation circuit which is capable of triggering a signal when radiation pulses of the radiation source and output pulses of the Radiation recipient are in coincidence.

Ein derartiger Rauchdetektor ist beispielsweise durch das US-Patent 3 316 410 bekannt. Dabei wird eine Strahlungsquelle von einem Impulsgeber gesteuert und sendet kurzdauernde Strahlungsimpulse aus. Die mit dem Streustrahlungsempfänger verbundene Auswerteschaltung ist vom Impulsgeber der Strahlungsquelle so gesteuert, dass sie bei Aufnahme von Streustrahlung nur während der Impulsphasen der Strahlungsquelle ein Ausgangssignal abzugeben vermag. Störimpulse, die zwischen den Strahlungsimpulsen auftreten, werden daher in der Auswerteschaltung blockiert und können nicht zur Auslösung eines Signales führen.Such a smoke detector is known, for example, from US Pat. No. 3,316,410. A radiation source is controlled by a pulse generator and emits short-lasting radiation pulses. The evaluation circuit connected to the scattered radiation receiver is controlled by the pulse generator of the radiation source in such a way that, when scattered radiation is picked up, it can only output an output signal during the pulse phases of the radiation source. Interference pulses that occur between the radiation pulses are therefore blocked in the evaluation circuit and cannot lead to the triggering of a signal.

Nachteilig ist hierbei, dass Störimpulse,welche zufällig während der gleichen Zeit auftreten wie die Strahlungsimpulse, ein fehlerhaftes Signal auslösen können.The disadvantage here is that interference pulses which occur accidentally during the same time as the radiation pulses can trigger a faulty signal.

Zur Vermeidung dieses Nachteiles ist bereits versucht worden, an die Auswerteschaltung eines solchen in Koinzidenz arbeitenden Rauchdetektors einen Integrator oder Speicher anzuschliessen. welcher erst dann ein Signal auslöst, wenn von der Auswerteschaltung innerhalb einer bestimmten Zeit eine vorgegebene Zahl von Ausgangsimpulsen abgegeben worden ist, wie z.B. im US-Patent No. 3 946 241 beschrieben.To avoid this disadvantage, attempts have already been made to connect an integrator or memory to the evaluation circuit of such a smoke detector operating in coincidence. which only triggers a signal when a predetermined number has been given of output pulses from the evaluation circuit within a specified time, such as in U.S. Patent N o. 3946241 described.

Ein solcher Rauchdetektor neigt zwar weniger zu einer fehlerhaften Signalgabe und zeigt demgemäss eine verbesserte Betriebssicherheit, jedoch kann es bei Auftreten mehrerer Störimpulse hintereinander immer noch vorkommen, dass zufällig mehrere dieser Störimpulse mit den Strahlungsimpulsen zusammenfallen und trotzdem ein fehlerhaftes Signal verursachen.Such a smoke detector is less prone to faulty signaling and accordingly shows improved operational reliability, however, if several interference pulses occur in succession, it can still happen that several of these interference pulses coincide with the radiation pulses and still cause a faulty signal.

Der Erfindung liegt die Aufgabe zugrunde, die erwähnten Nachteile vorbekannter Rauchdetektoren zu beseitigen und eine fehlerhafte Signalgabe infolge Auftretens von Störimpulsen möglichst weitgehend zu vermeiden und damit die Betriebssicherheit weiter zu verbessern, insbesondere bei der Verwendung als Brandmelder.The invention is based on the object of eliminating the disadvantages of known smoke detectors and avoiding faulty signaling as much as possible as a result of the occurrence of interference pulses and thus further improving operational safety, in particular when used as a fire detector.

Die Erfindung ist dadurch gekennzeichnet, dass die Auswerteschaltung eine Zähleinrichtung aufweist, welche sowohl die Strahlungsquellenimpulse als auch die Ausgangsimpulse des Strahlungsempfängers zählt, und jeweils bei ungeradzahligem Zählerstand nach einem beliebigen Strahlungsimpuls den Zähler auf Null zurückstellt, jedoch bei Erreichen eines vorgegebenen geradzahligen Zählerstandes ein Signal auslöst.The invention is characterized in that the evaluation circuit has a counting device which counts both the radiation source pulses and the output pulses of the radiation receiver, and resets the counter to zero after any radiation pulse in the event of an odd-numbered counter reading, but triggers a signal when a predetermined even-numbered counter reading is reached .

Die Erfindung macht sich die Tatsache zunutze, dass bei Anwesenheit von Rauch im Strahlungsbereich stets jedem Strahlungsimpuls ein entsprechender Ausgangsimpuls des Strahlungsempfängers entsprechen muss. Werden nun von einer Zähleinrichtung sowohl die Strahlungsquellenimpulse als auch die Ausgangsimpulse des Strahlungsempfängers gezählt, so muss nach jedem Strahlungsimpuls der Zähler einen geradzahligen Stand aufweisen. Ein ungeradzahliger Zählerstand ist dabei ein untrügliches Zeichen, dass kein Empfangsimpuls vorhanden ist. In diesem Fall wird die Auswerteschaltung sofort automatisch auf Null zurückgestellt, so dass der Zähler nicht den für eine Signalgabe erforderlichen Zählerstand erreichen kann. Der Zähler ist gesperrt, wenn kein Strahlungsquellenimpuls vorhanden ist.The invention takes advantage of the fact that when smoke is present in the radiation area, each radiation pulse must always correspond to a corresponding output pulse from the radiation receiver. Are now from If the radiation source pulses and the output pulses of the radiation receiver are counted in a counting device, the counter must have an even number after each radiation pulse. An odd-numbered counter reading is an unmistakable sign that there is no receive pulse. In this case, the evaluation circuit is automatically reset to zero so that the counter cannot reach the counter reading required for signaling. The counter is locked when there is no radiation source pulse.

Die Erfindung wird anhand der in der Figur dargestellten Schaltung eines Ausführungsbeispieles erläutert. Der mechanische Aufbau des Rauchdetektors kann dabei in bekannter Weise ausgeführt sein, beispielsweise wie im Schweizer Patent Nr. 592 932 beschrieben.The invention is explained with reference to the circuit of an embodiment shown in the figure. The mechanical construction of the R detector can also be carried out in a known manner, for example as described in Swiss Patent No. 592 932.

Bei der in der Figur wiedergegebenen Schaltung liegen zwischen zwei Gleichspannung führenden Leitungen L1 und L2 ein Strahlungssender S, ein Strahlungsaufnehmer A und eine an einen Binärzähler B mit nachgeschalteter Schaltstufe angeschlossene logische Korrelationsschaltung L.In the circuit shown in the figure, between two lines L 1 and L 2 carrying a direct voltage there is a radiation transmitter S, a radiation detector A and a logic correlation circuit L connected to a binary counter B with a downstream switching stage.

Der Strahlungssender besteht aus einem Impulsgenerator 1 bekannter Art, welcher beispielsweise Sendeimpulse von 100 pS Dauer und einem Impulsabstand von einer Sekunde produziert, welche einem Leistungstransistor 2 zugeführt werden. Am Transistorausgang liegt die Parallelschaltung eines Belastungswiderstandes 3 und einer licht- oder infrarotemittierenden Diode 4 in Serie mit einem Widerstand 5. Die Diode 4 sendet in das Streuvolumen des Rauchmelders Strahlungsimpulse im Rhythmus des Impulsgenerators 1 aus. Gleichzeitig werden vom Ausgang des. Leistungstransistors 2 Koinzidenzimpulse über eine Leitung K abgenommen und der logischen Korrelationsschaltung L zugeführt.The radiation transmitter consists of a pulse generator 1 of a known type which, for example, produces transmission pulses of 100 pS duration and a pulse interval of one second, which are fed to a power transistor 2. The parallel connection of a load resistor 3 and a light- or infrared-emitting diode 4 is connected in series with a resistor 5 at the transistor output. The diode 4 emits radiation pulses in the rhythm of the pulse generator 1 into the stray volume of the smoke detector. At the same time, 2 coincidence pulses are output via a line K from the output of the power transistor taken and supplied to the logic correlation circuit L.

Der Strahlungsaufnahmeteil A enthält einen Speicherkondensator 13, sowie eine Solarzelle 6, welche bei Vorhandensein von Rauch im Streuvolumen des Melders Streustrahlung im Rhythmus der Strahlungsimpulse der Diode 4 erhält. Parallel zur Solarzelle 6 liegt ein Belastungswiderstand 7. Die Ausgangsimpulse der Solarzelle 6 werden über einen Kondensator 8 einem Verstärker 9, beispielsweise einem Operationsverstärker mit einem Verstärkungsgrad 103, zugeleitet, dessen Ausgangssignale über einen Kondensator 11 mit zugehörigem Ableitwiderstand 12 der logischen Korrelationsschaltung L zugeführt werden. Die vom Strahlungsaufnahmeteil A abgegebenen Empfangsimpulse E sind durch geeignete Wahl des Frequenzganges von Verstärker und Solarzelle 6 exponentialförmig abgeflacht. Die logische Korrelationsschaltung L enthält zwei UND-Tore 14 und 15 sowie ein ODER-Tor 16. Dem ersten UND-Tor 14 werden an seinem ersten Eingang die Kcinzidenzimpulse K des Strahlungssenders S zugeführt, während das andere UND-Tor 15 an einem Eingang die Empfangsimpulse des Strahlungsaufnahmeteiles A erhält. Der Ausgang dieses UND-Tores 15 ist an einen Eingang des ODER-Tores 16 geführt, dessen anderer Eingang ebenfalls die Koinzidenzimpulse K erhält. Der Ausgang des ODER-Tores 16 ist mit dem Zähleingang C des Binärzählers B verbunden. Vom Zähler B werden also sowohl die Empfangsimpulse E als auch die Koinzidenzimpulse K gezählt, wobei eine Interferenz beider Impulsarten durch die abgeflachte Form des E-Impulses vermieden wird. Der Zähler kann z.B. vom Typ Motorola MC14024 sein.The radiation receiving part A contains a storage capacitor 13 and a solar cell 6 which, in the presence of smoke in the scattering volume of the detector, receives scattered radiation in the rhythm of the radiation pulses of the diode 4. A load resistor 7 is connected in parallel with the solar cell 6. The output pulses from the solar cell 6 are fed via a capacitor 8 to an amplifier 9, for example an operational amplifier with a degree of amplification 10 3 , the output signals of which are fed to the logic correlation circuit L via a capacitor 11 with an associated bleeder resistor 12 . The received pulses E emitted by the radiation receiving part A are flattened exponentially by a suitable choice of the frequency response of the amplifier and the solar cell 6. The logic correlation circuit L contains two AND gates 14 and 15 and an OR gate 16. The first AND gate 14 is supplied with the incidence pulses K of the radiation transmitter S at its first input, while the other AND gate 15 receives the receive pulses at one input of the radiation receiving part A receives. The output of this AND gate 15 is led to an input of the OR gate 16, the other input of which also receives the coincidence pulses K. The output of the OR gate 16 is connected to the counter input C of the binary counter B. Both the received pulses E and the coincidence pulses K are therefore counted by the counter B, interference from both types of pulse being avoided by the flattened shape of the E pulse. The counter can be of the type Motorola MC14024, for example.

Der Zähler B besitzt verschiedene Ausgänge für die einzelnen Ziffern des binären Zählerstandes, z.B. einen Ausgang Q0 für den ersten Bit oder die Endziffer und einen Ausgang Qn für den n.Bit oder n.Stelle der Binärzahl. Der Ausgang Q0 ist nun mit den beiden anderen Eingängen der beiden UND-Tore 14 und 15 verbunden, während der Ausgang des UND-Tores 14 mit einem Rückstelleingang des Binärzählers B verbunden ist, so dass der Zählerstand auf Null zurückgestellt wird, sobald am Ausgang des UND-Tores 14 ein Signal auftritt. Der Ausgang Q0 ist mit der Leitung L1 über einen Verzögerungskondensator 17 verbunden .Counter B has various outputs for the individual digits of the binary counter reading, for example an output Q 0 for the first bit or the final digit and an output Q n for the nth or nth digit of the binary number. The exit Q 0 is now connected to the other two inputs of the two AND gates 14 and 15, while the output of the AND gate 14 is connected to a reset input of the binary counter B, so that the counter status is reset to zero as soon as at the output of the AND -Tores 14 a signal occurs. The output Q 0 is connected to the line L 1 via a delay capacitor 17.

Durch diese Schaltung wird bewirkt, dass ohne Anwesenheit von Rauch im Streuvolumen des Melders, also bei Ausbleiben der Empfangsimpulse E über das ODER-Tor 16 an den Zähleingang C des Zählers B zu Beginn jedes Sendeimpulses nur ein Koinzidenzimpuls gezählt wird. Am Ausgang Q0 steht also ei Signal 1 an. Unmittelbar nach Ablauf des Koinzidenzimpulses entsteht am Ausgang des UND-Tores 14 ein Signal, so dass der Zähler B über einen Rückstelleingang R wieder auf Null zurückgestellt wird. Bei Abwesenheit von Streustrahlung, also bei Ausbleiben von Empfangsimpulsen, zählt der Zähler B also nicht weiter.This circuit has the effect that, without the presence of smoke in the scatter volume of the detector, i.e. if there is no receive pulse E via OR gate 16 at the counter input C of counter B, only one coincidence pulse is counted at the start of each transmit pulse. Signal 1 is therefore present at output Q 0 . Immediately after the coincidence pulse has elapsed, a signal is produced at the output of the AND gate 14, so that the counter B is reset to zero via a reset input R. In the absence of stray radiation, ie in the absence of receive pulses, counter B does not count further.

Trifft jedoch ein Koinzidenzimpuls K und nach einer geringen Verzögerungszeit ein Empfangsimpuls E ein, so gelangt über das ODER-Tor 16 direkt ein Zählimpuls K an den Zähleingang C und verzögert über das UND-Tor 15 und das ODER-Tor 16 ein Empfangsimpuls E. Dies hat zur Folge, dass am Ende des Koinzidenzimpulses der Zählerstand eine gerade Zahl ist, also die Endziffer Null am Ausgang QO ansteht, wodurch das UND-Tor 14 gesperrt ist und der Rückstelleingang R kein Signal erhält. Der Zähler zählt also weiter, wobei der Zählerstand stets eine gerade Zahl ist, also am Ausgang Q0 das Signal Null auftritt, wenn jeweils ein zusammengehöriger Koinzidenzimpuls und ein Empfangsimpuls eingetroffen sind. Während der Dauer des Sendeimpulses kann zum Koinzidenzimpuls nur noch maximal ein Empfangsimpuls in den Zähler eingelesen werden.However, if a coincidence pulse K arrives and a receive pulse E arrives after a short delay, a count pulse K reaches the count input C directly via the OR gate 16 and delays a receive pulse E via the AND gate 15 and the OR gate 16 has the consequence that at the end of the coincidence pulse the counter reading is an even number, that is to say the final digit zero is present at the output Q O , as a result of which the AND gate 14 is blocked and the reset input R receives no signal. The counter thus continues to count, the counter reading being always an even number, that is to say the signal zero occurs at the output Q 0 when a coincidence pulse and a reception pulse have arrived in each case. During the duration of the transmission pulse, only a maximum of one reception pulse can be read into the counter for the coincidence pulse.

An den n. Ausgang Q des Zählers B ist über einen Widerstand 18 die Steuerelektrode eines Thyristors 19 angeschlossen, welcher in Serie mit einem Widerstand 20 und einer Anzeigeeinrichtung 21, z.B. einer lichtemittierenden Diode, zwischen den Leitungen LI und L2 liegt. Sobald der Zählerstand einen bestimmten vorgegebenen Wert erreicht hat, d.h. sobald die n., z.B. die 4. Ziffer der Binärzahl, zu 1 geworden ist, wird der Thyristor 19 durchgeschaltet und es fliesst ein Alarmstrom, welcher die Anzeigeeinrichtung 21 betätigt und somit das Vorhandensein von Rauch signalisiert. Bei Anschluss des Melders an eine Signalzentrale fliesst zudem ein Alarmstrom von den Anschlussklemmen des Melders zur Zentrale, welcher dort ebenfalls in bekannter Weise zur Signalgabe ausgewertet werden kann.The control electrode of a thyristor 19 is connected to the n. Output Q of the counter B via a resistor 18, which is connected in series with a resistor 20 and a display device 21, for example a light-emitting diode, between the lines L I and L 2 . As soon as the counter reading has reached a certain predetermined value, ie as soon as the n., For example the 4th digit of the binary number, has become 1, the thyristor 19 is switched through and an alarm current flows, which actuates the display device 21 and thus the presence of Smoke signals. When the detector is connected to a signaling center, an alarm current also flows from the connecting terminals of the detector to the center, which can also be evaluated there for signaling in a known manner.

Es sei bemerkt, dass die logische Korrelationsschaltung L auch als integrierter Schaltkreis mit gleicher Funktion ausgeführt sein kann.It should be noted that the logic correlation circuit L can also be designed as an integrated circuit with the same function.

Durch die beschriebene Schaltung wird also der Vorteil erreicht, dass nur dann ein Alarmsignal ausgelöst werden kann, wenn gleichzeitig oder innerhalb einer geringen Verzögerungszeit sowohl ein vom Strahlungssender abgenommener Koinzidenzimpuls als auch ein vom Strahlungsaufnehmer gelieferter Empfangsimpuls eintreffen und wenn solche korrelierte Empfangsimpulse eine vorgegebene Anzahl Mal aufeinander folgend auftreten. Falls jedoch nur ein einzelner Impuls eintrifft, entweder weil wegen der Abwesenheit von Rauch keine Empfangsimpulse entstehen oder infolge einer Störung,wird automatisch die Signalgabe blockiert. Diese korrelierte Mehrimpulsabhängigkeit verbessert daher die Störunempfindlichkeit wesentlich.The circuit described thus achieves the advantage that an alarm signal can only be triggered if both a coincidence pulse taken from the radiation transmitter and a receive pulse supplied by the radiation receiver arrive at the same time or within a short delay time and when such correlated receive pulses occur a predetermined number of times occur following. However, if only a single pulse arrives, either because there are no receive pulses due to the absence of smoke or as a result of a fault, the signaling is automatically blocked. This correlated multi-pulse dependency therefore significantly improves the immunity to interference.

Claims (7)

1. Rauchdetektor mit einer impulsweise betriebenen Strahlungsquelle, einem ausserhalb des direkten Strahlungsbereiches der Strahlungsquelle angeordneten, bei Anwesenheit von Rauch im Strahlungsbereich durch Streustrahlung beaufschlagten und Ausgangsimpulse abgebenden Strahlungsempfänger, und einer Auswerteschaltung, welche ein Signal auszulösen vermag, wenn Strahlungsimpulse der Strahlungsquelle und Ausgangsimpulse des Strahlungsempfängers in Koinzidenz sind, dadurch gekennzeichnet, dass die Auswerteschaltung eine Zähleinrichtung (B) aufweist, welche sowohl die Strahlungsquellenimpulse als auch die Ausgangsimpulse des Strahlungsempfängers zählt, und jeweils bei ungeradzahligem Zählerstand nach einem beliebigen Strahlungsimpuls den Zähler auf Null zurückstellt, jedoch bei Erreichen eines vorgegebenen geradzahligen Zählerstandes ein Signal auslöst.1. Smoke detector with a pulsed radiation source, a radiation receiver arranged outside the direct radiation area of the radiation source, which is exposed to scattered radiation in the presence of smoke in the radiation area and emits output pulses, and an evaluation circuit which is capable of triggering a signal if radiation pulses from the radiation source and output pulses of the radiation receiver are in coincidence, characterized in that the evaluation circuit has a counting device (B) which counts both the radiation source pulses and the output pulses of the radiation receiver, and resets the counter to zero after an arbitrary radiation pulse in the case of an odd-numbered counter reading, but when a predetermined even number has been reached Counter signal triggers. 2. Rauchdetektor nach Anspruch l, dadurch gekennzeichnet, dass die Zähleinrichtung einen Binärzähler (B) enthält, sowie eine Rückstelleinrichtung (L) auf Null bei Auftreten der binären Endziffer 1 des binären Zählerstandes.2. Smoke detector according to claim 1, characterized in that the counting device contains a binary counter (B) and a reset device (L) to zero when the binary end digit 1 of the binary counter reading occurs. 3. Rauchdetektor nach Anspruch 2, dadurch gekennzeichnet, dass die Rückstelleinrichtung (L) den Zähler (B) zurückstellt, wenn unmittelbar nach Ablauf eines Sendeimpulses die Endziffer des binären Zählerstandes eine 1 ist.3. Smoke detector according to claim 2, characterized in that the resetting device (L) resets the counter (B) if the end digit of the binary counter reading is a 1 immediately after the expiry of a transmission pulse. 4. Rauchdetektor nach Anspruch 2, dadurch gekennzeichnet, dass die Rückstelleinrichtung (L) den Zähler (B) auf Null zurückstellt, wenn die Endziffer 1 des binären Zählerstandes eine vorgegebene Zeitdauer ansteht.4. Smoke detector according to claim 2, characterized in that the reset device (L) resets the counter (B) to zero when the final digit 1 of the binary counter reading is pending for a predetermined period of time. 5. Rauchdetektor nach Anspruch 2, dadurch gekennzeichnet, dass die Rückstelleinrichtung (L) während der Dauer der Strahlungsimpulse inhibiert ist.5. Smoke detector according to claim 2, characterized in that the reset device (L) is inhibited during the duration of the radiation pulses. 6. Rauchdetektor nach einem der Ansprüche 2 - 4, dadurch gekennzeichnet, dass die Zählereinrichtung (B) ein Signal auslöst, wenn eine vorgegebene andere Binärziffer des Zählerstandes 1 wird.6. Smoke detector according to one of claims 2-4, characterized in that the counter device (B) triggers a signal when a predetermined other binary number of the counter reading is 1. 7. Rauchdetektor nach einem der Ansprüche 2 - 5, dadurch gekennzeichnet, dass die Rückstelleinrichtung eine logische Korrelationsschaltung (L) enthält, die zwei UND-Tore (14, 15) aufweist, deren einem Eingang jeweils die Empfangsimpulse (E) des Strahlungsempfängers (6) bzw. die Strahlungsquellenimpulse (K), und deren anderem Eingang das Endziffersignal (Q0) des Binärzählers (B) zugeführt werden, sowie ein ODER-Tor (16), das die Strahlungsquellenimpulse (K) und das Ausgangssignal des dem Empfänger zugeordneten UND-Tores (15) erhält und dessen Ausgang mit dem Zähleingang (C) des Binärzählers (B) verbunden ist, wobei der Ausgang des anderen UND-Tores (14) mit dem Rückstelleingang (R) des Binärzählers (B) verbunden ist.7. Smoke detector according to one of claims 2 - 5, characterized in that the return device contains a logical correlation circuit (L), the two AND gates (14, 15), one input of which respectively the reception pulses (E) g of Strahlun sempfängers (6) or the radiation source pulses (K), and the other input of which the final digit signal (Q 0 ) of the binary counter (B) is fed, and an OR gate (16) which contains the radiation source pulses (K) and the output signal of the receiver assigned AND gate (15) and whose output is connected to the counting input (C) of the binary counter (B), the output of the other AND gate (14) being connected to the reset input (R) of the binary counter (B).
EP79200721A 1979-02-22 1979-12-04 Smoke detector comprising a pulse evaluating circuit Expired EP0014779B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79200721T ATE1207T1 (en) 1979-02-22 1979-12-04 SMOKE DETECTOR WITH IMPULSE EVALUATION CIRCUIT.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH177379A CH638331A5 (en) 1979-02-22 1979-02-22 SMOKE DETECTOR.
CH1773/79 1979-02-22

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EP0014779A1 true EP0014779A1 (en) 1980-09-03
EP0014779B1 EP0014779B1 (en) 1982-06-16

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EP (1) EP0014779B1 (en)
JP (1) JPS55114938A (en)
AT (1) ATE1207T1 (en)
AU (1) AU528534B2 (en)
CA (1) CA1129034A (en)
CH (1) CH638331A5 (en)
DE (1) DE2963129D1 (en)
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NO (1) NO147619C (en)

Cited By (4)

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EP0079010A1 (en) * 1981-11-11 1983-05-18 Cerberus Ag Smoke detector
WO1984002790A1 (en) * 1983-01-11 1984-07-19 Cerberus Ag Photoelectric smoke detector and utilization thereof
EP0067313B1 (en) * 1981-06-15 1985-08-28 Cerberus Ag Smoke detector with a pulse-actuated radiation source
GB2214682A (en) * 1988-01-21 1989-09-06 Huang Ding Li Smoke warning apparatus

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US2609216A (en) * 1947-06-06 1952-09-02 Eric M Mcelhinney Sharp turn steering apparatus for vehicles
DE943797C (en) * 1950-02-26 1956-06-01 Hermann E Mueller K G Dr Motorized vehicle for carrying out in particular agricultural work
US5019805A (en) * 1989-02-03 1991-05-28 Flash-Alert Inc. Smoke detector with strobed visual alarm and remote alarm coupling
AU652513B2 (en) * 1992-06-29 1994-08-25 Nohmi Bosai Ltd Smoke detecting apparatus for fire alarm
UA78855C2 (en) * 2005-04-05 2007-04-25 Private Entpr Arton Smoke detector
CN102426751B (en) * 2011-08-26 2013-07-17 无锡蓝天电子有限公司 Point-type photoelectric smoke detector
WO2018089668A2 (en) 2016-11-11 2018-05-17 Carrier Corporation High sensitivity fiber optic based detection
CA3043587A1 (en) 2016-11-11 2018-05-17 Carrier Corporation High sensitivity fiber optic based detection
CA3043583A1 (en) 2016-11-11 2018-05-17 Carrier Corporation High sensitivity fiber optic based detection
WO2018089654A1 (en) 2016-11-11 2018-05-17 Carrier Corporation High sensitivity fiber optic based detection
WO2018089660A1 (en) * 2016-11-11 2018-05-17 Carrier Corporation High sensitivity fiber optic based detection

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0067313B1 (en) * 1981-06-15 1985-08-28 Cerberus Ag Smoke detector with a pulse-actuated radiation source
EP0079010A1 (en) * 1981-11-11 1983-05-18 Cerberus Ag Smoke detector
US4555634A (en) * 1981-11-11 1985-11-26 Cerberus Ag Optical smoke detector with contamination detection circuitry
WO1984002790A1 (en) * 1983-01-11 1984-07-19 Cerberus Ag Photoelectric smoke detector and utilization thereof
GB2214682A (en) * 1988-01-21 1989-09-06 Huang Ding Li Smoke warning apparatus

Also Published As

Publication number Publication date
AU528534B2 (en) 1983-05-05
US4321595A (en) 1982-03-23
EP0014779B1 (en) 1982-06-16
JPS55114938A (en) 1980-09-04
NO147619B (en) 1983-01-31
AU5471580A (en) 1980-08-28
CA1129034A (en) 1982-08-03
DK149726C (en) 1987-04-13
NO794342L (en) 1980-08-25
CH638331A5 (en) 1983-09-15
DK64380A (en) 1980-08-23
NO147619C (en) 1983-05-18
DE2963129D1 (en) 1982-08-05
DK149726B (en) 1986-09-15
ATE1207T1 (en) 1982-07-15
JPS6327653B2 (en) 1988-06-03

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