DE2140121A1 - Fire alarm device - Google Patents

Description

NIttan Company ^ Limited Tokyo, Japan «,

Fire alarm device »

The invention relates to fire alarm devices, and in particular to those with ionization smoke sensorsj, and it concerns specifically a facility, that between a fake and a correct response of a rough sensor and reported the wrong response separately from the correct response

In a well-known one that works according to the oenization principle Fire alarm devices are several local ionization smoke ... sensor connected in parallel between two lines leading from go out from a central office. The control center contains a power supply and a relay connected in series with the lines and an alarm device that can be triggered by the relay. Any local Ionization smoke sensor contains two ionization chambers each with a pair of electrodes and a radioactive radiation source for ionizing the atmosphere inside the chamber. One chamber is closed off from the ambient air and is referred to below as the "closed ionization chamber", while the other chamber towards the ambient air is open and is referred to as "open ionization chamber. Both chambers are connected in series between the two lines, and the common connection between the chambers is to the control electrode of a field effect transistor, whose Source-drainage path in series with a load resistor

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is switched between the two lines. The smoke detector also contains a controlled silicon rectifier, its control electrode via a zener diode with the source electrode of the field effect transistor is connected and its anode-cathode path is between the two lines.

When smoke gets into the open ionization chamber, the current flowing through ionization in this chamber is reduced and the voltage increases at the common connection point between aen two chambers and thus also at the control electrode of the field effect transistor. This results in an increase in the source voltage of the field effect transistor, and when this voltage exceeds the Zenera voltage of the Zener diode, it acts on the control electrode of the controlled silicon rectifier, so that it becomes conductive and creates a short circuit between the two lines. Thus the relay responds and triggers the alarm device.

With these known fire prevention devices, however, an alarm is also triggered when the ionization smoke sensor responds incorrectly without a breath getting into the open ionization chamber. Sin such wrong addressing can for example, if the field effect transistor breaks down, if there is insufficient insulation and similar errors and is extremely annoying.

It is therefore the object of the invention to provide a fire alarm device to create that distinguish such an incorrect response of the ionization smoke sensor from the correct response can and reports it separately. According to the invention, this object is achieved in principle by a device the voltage applied to the response of the smoke sensor to a value below that for operation

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of the ionization smoke sensor is reduced and by a discriminator for current changes in the lines.

Details of the invention are described in more detail below with reference to the drawings.

Figure 1 shows a circuit diagram of a typical after

Ionization principle working fire alarm device according to the state of the art;

Fi ^ ur 2 shows a diagram to explain the invention with current-voltage characteristics of the ionization chambers;

FIG. 3 is a block diagram of one according to the invention Fire alarm device;

FIG. 4 shows the circuit diagram of a first embodiment of the invention;

Figure 5 shows the circuit diagram of a second embodiment of the invention;

FIG. 6 shows the circuit diagram of a third embodiment of the invention;

Figure 7 is a circuit diagram of an embodiment of the invention üiskriminators for the change in current;

Figures 8-1 through 8-3 illustrate the operation of the various relay shown in the circuit diagram of FIG.

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Corresponding parts are indicated for the same throughout the drawings Provide reference numbers "

In the typical exemplary embodiment of a known fire alarm device operating according to the ionization principle shown in FIG. 1, a local unit 1 and a control center 2 are connected to one another by a pair of lines 3 and 4 Units parallel to each other between the two conductors 3 and A * A conventional ionization smoke sensor is shown as the local unit 1, consisting of a closed ionization chamber 10 _f which is in series with an open ionization chamber 20 between the lines 3 and 4, a field effect transistor 6 _f whose control electrode is at the common connection point 5 between the two ionization chambers and whose source-drainage path is via a load or working resistor. 7 is between lines 3 and 4, and a controlled silicon rectifier 8, the control electrode of which is connected to the source electrode of the field effect transistor 6 via a Zener diode 9, and its mode-cathode path or main current path also between the lines 3 and 4 lies. The control electrode of the controlled silicon rectifier 6 is also connected to the line 4 via a bleeder resistor 14. The closed ionization chamber 10 contains two electrodes 11 and 12 as well as a radioactive radiation source 13f and in a similar way the open ionization chamber 20 is provided with two electrodes 21 and 22 and a radioactive radiation source 23. The closed ionization chamber 10 can also be provided with a fixed resistor comparable impedance are replaced * The control center 2 contains a supply source 15 and an electromagnetic relay 16 in series

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between the two lines 3 and 4 »In the central © is also an alarm device is present ^ which from the relay contact 17, a supply source j, a loudspeaker 24 and an indicator lamp 25 ",

The mode of operation of the device shown in FIG. 1 will now be described with reference to FIG. The voltage at the connection point 5 between the two ionization chambers 10 and 20 according to FIG. 1 forms the abscissa of the diagram shown in FIG. 2, while the ionization current flowing through both ionization chambers forms the ordinate * Curve A is the load curve of the closed ionization chamber 10 and represents the ionization current in this chamber as a function of the voltage at point 5 bsi normal operating voltage & ar _e The curve B is the characteristic of the open ionization chamber 2 © and represents the ionization current in this chamber as a function of the voltage at the same point 5 in the normal monitoring state _? that is, in the event that there is no smoke in the open ionization chamber. Since the ionization currents in the two ionization chambers are the same in the circuit according to FIG. 1 _? the voltage at point 5 adjusts itself to a stable value Sp, which corresponds to the point of intersection of the two curves A and B when there is no puff in the open ionization chamber 20. However, if this chamber 20 fills with smoke, its characteristic changes to curve B ^{1, for} example.This increases the voltage at point 5, which is also applied to the field effect transistor 6 as a control voltage, from S ₁ to Ep as shown in FIG . This has the overall a corresponding increase in the source voltage of the Feldeffekttranaistors 6 consequence ₉ when exceeding the Zener voltage of the Zener diode 9 to the control electrode of the silicon controlled rectifier 8

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and switches it to conductivity. This means that the two lines 3 and 4 are above the rectifier short-circuited, the relay 16 in the control center 2 responds and closes its contact 17 », giving a fire alarm will.

Once the silicon controlled rectifier 8 has become conductive, its locked state is not restored, unless the power source is removed 15 from it * This also applies to the Pail of a false Aasprechens of the smoke sensor due to a damage m field effect transistor 6, a destroyed insulation or similar Errors as well as in the event of a temporary response due to electrical interference signals, ingress of dust, wind or the like. Such an erroneous response cannot be distinguished from normal and correct triggering »

The block diagram according to FIG. 3 illustrates the basic Seheiaa of the fire alarm device according to the invention · Between a voltage source 15 and the ionization smoke sensor 27, a spaimungs-changing device 26 is connected, which is hereinafter referred to as "voltage changer" for short. The voltage changer 26 is used to change the supplied voltage to a special low value as soon as the ionization sensor 27 responds and to restore the original voltage as soon as the air sensor no longer responds.

The smoke sensor 27 according to the invention is constructed so that it cannot respond at the above-mentioned reduced voltage, even if it is in the open ionization chamber Smoke is located. If during normal operation

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If smoke of the smoke sensor penetrates into the ionization chamber, the smoke sensor excited by this will soon be de-excited again because the voltage applied by the voltage changer 26 is reduced when the smoke sensor responds. As a result of the de-excitation of the smoke sensor, the voltage from the voltage changer 26 is reset to its original high value. The ionization smoke sensor 27 according to the invention therefore changes constantly between the excited and de-excited state at a certain frequency and actuates όΒ.ε .Tielfis 16 periodically.

The value of the above-mentioned reduced voltage is also selected so that it is sufficient to maintain the state of excitation of the relay 16 when the ionization smoke sensor 27 is erroneously triggered. Therefore, if the smoke sensor responds abnormally as a result of a defect, the smoke sensor 27 is not de-excited by the reduced voltage supplied and continues to respond to _f, so that the relay 16 does not return to its original open state. If the ionization smoke sensor is temporarily excited by an electrical interference signal or by penetrating wind, it only responds briefly and then returns to its old state, whereby the relay 16 is also only temporarily, but neither repeatedly nor constantly excited *

A discriminator 28 shown in Figure 3 distinguishes with these different types of response of the ionization smoke sensor 27 between normal and irregular operation and generates output signals corresponding to the various operating modes. A message shown in Figure 3 « device 29 receives the output signals from the discriminator 28 and reports an outbreak of fire or an error in the smoke

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feelers in separate and distinguishable ways.

FIGS. 4, 5 and 6 show 3 embodiments of the fire alarm device according to the invention, whereby mainly practical embodiments of the voltage changer 26 and the ionization touch sensor 27 according to FIG. 3 are shown. The devices according to FIGS. 4, 5 and 6 also each contain a local unit 1 and a control center _2f, which are connected to one another by two lines 3 and 4, as in the device according to FIG Units w parallel between lines 3 and 4 »in each drawing, however, only one such unit is shown for the sake of simplicity.

The local unit of Figure 4 consists of a loni- ■ Sations-Itauchfühler, the one of FIG 1 is almost the same, but instead of a controlled Siliziumgleiehriohters β a bipolar transistor Jl * contains the h & nis of Transistors'31 _f is at the Zener diode 9, and its 3-middle-Koliektor-3trecke is connected in series with a further Zener diode 32 swisehen the two lines 3 and 4 * The transistor 31 and the Zener diode 32 act in the manner described below, to the function of the voltage changer 26 according to r'igur "5 Connected in parallel to the Zener diode 32 is an indicator lamp 33 which indicates that the Zener diode 32 is conducting.

in the case of the roof breath sensor in FIG. 4 in. the ionization chamber 20 If smoke penetrates, the, -. Corpse process plays from j the one in ZUDEifflraenhan ,; rait dent - well-known .diving sensors .jach Figure 1 has been described ρ and au the Baris des l "rait-

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A transistor 31 creates a control voltage which drives this transistor into conductivity. Because of the Zener diode 32, the lines 3 and 4 are not directly short-circuited and a voltage which corresponds to the Zener voltage of the Zener diode 32 remains as the reduced supplied voltage described above if there is a reduced voltage across the series circuit consisting of the two ionization chambers 10 and 20, the load curve A of the closed ionization chamber 10 changes to the curve ^{shown in FIG. 2 with the dashed curve A 1} , and the control voltage of the field effect transistor β is reduced in a corresponding manner from E to si, even if there is smoke in the open ionization chamber 20 exceeds, then the transistor r 31 is blocked and the originally applied voltage is restored between the two lines 3 and 4 it is shown schematically by the shaft (16) in Figure 8-1.

The local unit 1 of Figure 5 corresponds to that of Figure 4, only that the Zener diode 32 by a fixed Resistor 34 is replaced and that the control center 2 in addition one contains another voltage source 35, which is moved by a switch 16-1 moved by the relay 16 in place of the voltage source 15 can be switched. The voltage of the voltage source 35 is lower than that of the voltage source 15 and selected from the outset so that it corresponds to the above mentioned condition for the reduced voltage is fulfilled.

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When smoke enters the open ionization chamber 20 and the transistor 31 becomes conductive, then the relay 16 is energized and the switch 16-1 thrown, so that the Voltage source 15 is switched over to voltage source 35. The supply voltage between the lines 3 and 4 are thus minimized, and the transistor 31 is blocked again, as is also the case with the circuit according to FIG was the case. This results in a similar periodic energization of the relay 16.

W corresponds to the device according to FIG β to that of Figure 5, except that the additional voltage source 35 and the changeover switch are omitted 16-1. In this device, the impedance of the relay 16 is selected from the outset so that when the relay is energized, a reduced voltage is created between the two lines 3 and 4, which fulfills the above-mentioned conditions. This results in the same change in the Zug@fah.rten voltage as in the arrangements of FIGS. 4 and 5, and the relay 16 is similarly energized periodically when smoke penetrates into the open ionization chamber 20.

"In contrast to the behavior just described, with an incorrect response to the smoke fault as a result of damage to the field effect transistor 6 or as a result of a destroyed Isolation of the smoke sensor does not return to its original State reset, even if the supplied Voltage is reduced as described above, because this reduced voltage is selected from the outset in such a way that that they are used to maintain the response state of the smoke sensor sufficient. The relay 16 remains constantly excited in this case, as shown schematically by the shaft (16) in FIG 8-2 is shown. In the event of an erroneous response due to electrical interference or due to a

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passing over air flow speaks the Rauchfiihler temporarily and ends soon with the response again, and the relay 16 is energized in a manner _f as shown schematically by the shaft (16) in Figure 8-3.

Fi-jur 7 shows an embodiment of the discriminator 28 according to FIG. 3 _f, the circuit structure of which is described below. A series connection of a normally open contact 16-2, a resistor 44 and a capacitor 45 "which forms a time constant circuit _f lies between two lines 53 and 54" which originate from a supply source 43. The ingenious connection between the resistor 44 and the: a capacitor 45 is connected to the control electrode of a field effect transistor 66, the source-drain path of which lies in series with a relay 36 and a working resistor 47 between lines 53 and 54 '. A working contact 36-1 of the relay 36 is parallel to the series connection of the field effect transistor 46 and the working resistor 47 'to form a self-holding contact for the relay 36. A _{normally open contact 36-3 r} a relay 38 and a normally closed contact 37-1 are connected in series between the lines 53 and 54 _f and a normally open contact 38-1 of the relay 3ö is parallel to the contact 16-3 »around a self-holding contact for the relay 38 to form. The contacts 16-2 and luh-3 are operated by the relay 16 _t which is contained in the circuits of Figures 4 and _f 5. 6 The contact 3 7-1 is actuated by a relay 37 to be described later. A normally open contact 38-2 of the relay 38 and a V / resistor 48 as well as a capacitor 4 ^ _9, which also form a time constant circuit, are in series between the lines 53 and 54 «The time constants belonging to the relays 36 and 37 must be chosen so that the operating conditions described below are complied with for a circuit

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made equal by the determining components of the Time constant circuits receive the same values.

The above-described part of the circuit of Figure 7 is now on the basis of the signal forms in FIGS. 8-1, 8-2 and 8-3 in the event that the same time constants are decisive for both relays 36 and 37. If in the open ionization chamber 20 of an ionization smoke sensor smoke penetrates the fire alarm device according to the invention, the relay 16 in the control center 2 is periodically energized, as it is to be described above and how it is B shown schematically by shaft (16) in Figure 8-1. Such periodic energization of the relay 16 and the corresponding actuation of the contact 16-2 is gradual Charging of the capacitor 45 results, whereby the control voltage and thus also the source current of the field effect transistor 46 increases. When this current has reached a certain value, the relay 36 responds and switches his self-holding contact 36-1. The way in which the relay 36 is switched on is shown schematically by the shaft (36) in FIG Fi, illustrated for 8-1. The relay 16 also operates contact 16-3, which energizes relay 38. The relay 38 actuates its self-holding contact 38-1 to close itself hold, and at the same time actuates the contact 38-2, which establishes a charging path for the capacitor 49. If then the drain stream of the field effect transistor 50 has reached a certain value as a result of the charging of the capacitor 49, the relay 37 is energized, and its normally closed contact 37-1 switches d £ s relay 38 from, whereby the contacts 38-1 and 38-2 open. The capacitor 49 is then gradually discharged, and when the discharge current dep field effect transistor 50 falls below a certain value, the relay 37 is de-energized. Since the contact 38-2 through the latching relay 38 was permanently closed and the loading time constants of the

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both capacitors 45 and 49, as assumed above, are the same are, the capacitor 49 charges faster than the capacitor 45 and the relay 37 is therefore earlier than the relay 36 excited. The relays 37 and 38 are therefore excited according to the curve shapes (37) and (38) of Figure 8-1. The time difference between the leading edges of the waves (16) and (38) corresponds to the time delay by which the helix 38 is later than the relay L6 responds.

Jenn the ionization smoke sensor because of damage on the field effect transistor or because of a damaged insulation errümiicli responds, the relay 16 is constantly energized, such as it by the curve shape. (16) is shown in Fig. D-2, and are the charging conditions for both capacitors 45 and 49 Same with the exception of the time delay at the start of charging üfj; j capacitor 49. Therefore, the relay 36 is increased by one Serve, delayed time, excited earlier than relay 37. Thus, the operation of the various relays is as shown in Figure 8-2 because of the excitation the two idtin relays 37 and 36 in this case the same is as in the case of Figure 8-1,

., eriri α ..- r LonisatLorus smoke sensor, on the other hand, temporarily anr.ori uit due to electrical Störni.naleu or an air flow, the relay 16 is also temporarily energized, but if it is not sufficient to energize the relay 36 . Therefore, the operation of the relay corresponds in this case to the situation in FIG.

If one considers the general conditions of the excitation of the two iieLais 3 *> and j /, then one can see that between the riohtigf.'U and duui faLBchen Amiprechon deu [oiiLvUitiniii-RuuohfühLer / 3 by "1 Lo F} £ jbi: tnliun _r , I can be different,

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which relay is reached earlier than the other. Sin embodiment a discriminator circuit that makes this determination is shown in the lower part of FIG.

Four relays 39, 40, 41 are located in this part of the circuit and 42 between lines 53 and 54. Relay 3j can actuate an element (not shown) for reporting an error operation, and the element 41 can operate a (not shown) Trigger the fire alarm device. The relay 39 is via a Working contact 40-1 of a relay 40, the working contact of a switch operated by the relay 37 3 7-3 and one Working contact 36-2 of the relay 36 between the two lines 53 and 54 switched. Dar, relay 40 is via the normally closed contact of the switch 37-3 and the contact 36-2 between the conductors 53 and 54 are connected. A work contact 40-2 of the relay 40 bridges the normally closed contact of the Umscha.ltere 37-3 to form a self-holding contact of the relay 40. The relay 41 is via a normally open contact 42-1 of the ReLaL 42, the normally open contact of a switch that can be actuated by the relay 36 36-3 and an Arböitskonbakt 37-2 of the relay 37 shaded between the lines 53 and 54, while d ..- j Relay 42 via the break contact of the switch 36-3 and is connected via the contact 37-2 between the lines 53 and 54. An Arbeibkontakb 42-2 of the relay 42 bridged the break contact of the switch 36-3 ^ to form a SeLbßthaLbelonüaktü of the relay 42.

If daw tie ta is 37 ^ uor .. t and the relay; 5υ then excited v / ird, as ^> - is vorainjohaulioht in iUur ü-1, then wühl.iolJfc iji.ih άον Kont-uU Υί-2, da ;} ReL-tüi 42 will err ^ jb and ijchLiojJ t dio ICou *. »Kt; 42-1 and 42-2 and is given by Lub ^ bür «n .nh'il t:) ii, An.uihl it) i.-md L ^ yb nich der bov / e ^ licho K> nb? Ikb

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of the switch 36-3 against the contact connected to the relay 41, whereby this relay 41 is energized and triggers a fire alarm in the alarm device (not shown). Since the "moving contact of the switch 37-3 on the with the fixed contact connected to the relay 39 is before the contact 36-2 is closed by the relay 36, this can Relay 40 does not respond and contact 40-1 is therefore not closed. Therefore, the relay 39 cannot be energized will.

On the other hand, if first the relay 36 and then the relay is excited, as it is illustrated in Figure 8-2, then the events with respect to the relays 39 and 40 take place in reverse order and the relay 39 responds, so that an error alarm is issued by the error reporting device (not shown) given we d. The relay 41 does not respond, however. In the case of the erroneous operation as illustrated in Figure 8-3 is, none of the relays 39 and 41 is energized and no alarm is triggered by the circuit.

As described above, with the inventive Setup can easily distinguish between correct and incorrect response of the ionization smoke sensor, and nobody is bothered by a false alarm as a result of an improper response of the smoke sensor.

The circuit arrangements described above are only exemplary embodiments to explain the invention. Further modifications and changes for realizing the principle according to the invention are possible without the area

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to leave the invention. For example, the discriminator Contain a conventional pulse counter that counts the number of Ionisations-Hauchfühlei from the invention generated pulses counts.

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Claims (1)

2H0121 λ * Patent claims » ( 1.yFire alarm device with an ionization smoke sensor, which responds to the presence of smoke and delivers an output signal if its supply voltage exceeds a certain threshold, and with an alarm device that can be triggered by this output signal, characterized by a device that influences the supply voltage (26 ), which reduces the supply voltage below the certain minimum value in response to the output signal of the smoke sensor (27) and restores it to the associated termination of the output signal, and a discriminator circuit (2Ö) _f which in a case of a through the interaction of the Supply «- 'voltage changing device and the smoke sensor-produced periodic output signal of the smoke sensor acted upon the alarm device (29) in a different way than with a continuous output signal produced by incorrect operation of the roughness sensor. 2. Fire alarm device according to claim 1, characterized in that the alarm device (29) contains a fire alarm unit and a fault alarm unit and that the discriminator circuit (23) selectively acts on both units. 3. Fire alarm device according to claim 1, characterized in that that the device for influencing the supply voltage is one of the output signal of the smoke sensor (10, 20) controlled bipolar transistor (31) and a zener diode (32) contains, whose zener voltage is below the particular child t value of the supply voltage, and that the Iran . ßissor (31) and the Zener diode (32) together. 209808 / 13-61 - ■ «- 2H0121 in series between the poles (3 »4) of the supply voltage are switched. 4. Fire alarm device according to claim 1, characterized in that that the device for influencing the supply voltage is one of the output signal of the smoke sensor (10, 20) controlled bipolar transistor (31) which between the poles (3, 4) of the supply voltage is switched, and that a second voltage source Is W (35) having a voltage below the certain Kindestwert provided responsive via a wind speed for Leitfähi _o the transistor switching means (16, 16-1) being switchable to the site of Versorgungespannung. 5. Fire alarm device according to claim 4, characterized in that that the switching device is a Heiais (Ib), which that acting on the discriminator circuit (2o) Signal generated. 6. Fire alarm device according to claim 1, characterized in that that the device for influencing the supply ί voltage one from the output signal of the smoke sensor (10, 20) controlled bipolar transistor (31) which is connected between the poles (3 »4) of the supply voltage, and that in series with the source (15) for the supply voltage there is a resistor (16) whose resistance value is as follows it is selected that the supply voltage of the smoke sensor during its response below the certain minimum value sinks. 7 · Fire alarm device according to claim 6, characterized in that that the resistance through the electromegnatic winding a relay (16) is formed, which generates the discriminator circuit device (28) applied signal. 2 09808/1351 - 3 - -y- 2H0121 JR 8. Fire alarm device according to claim 1, characterized by a discriminator circuit consisting of a first capacitor (45), the charging of which begins at the same time as the start of the periodic or continuous output signal and continues for the duration of these output signals, a first relay (36) responding at a certain charging voltage of the first capacitor (45), a second relay . Capacitor (49), the charging of which begins a certain period of time after the start of the output signals and then turns off • in any case continues continuously, one with a certain one Charging voltage of the second capacitor (49) responsive second relay (37) * where the charging time constants of the capacitors are dimensioned so that in the case of a periodic output signal, the second relay (37) earlier than the first Relay (36) and in the case of a continuous output signal the first relay (36) responds earlier than the second relay (37) and one of the order of response of the two relays differentiating device applied to the alarm device selectively. 9. In a fire alarm device according to claim 1 usable and ionization smoke sensors with two connections that respond only above a certain minimum operating voltage, a closed ionization chamber and an open ionization chamber, and with a field effect transistor, its Control electrode at the connection point between the two ionization chambers lies and whose source-drainage path lies between the two connections, characterized in that a bipolar transistor (31) with a Zener diode is connected in series between the two connections (3, 4), and that the bipolar transistor can be controlled by the field effect transistor (6), and that the Zener voltage of the Zener diode is lower than the minimum operating voltage for the smoke sensor. 20 98087 135 1 IO Lee r s e i t e