EP2940666A2 - Danger warning system - Google Patents

Abstract

A hazard detector comprising a measuring chamber, a functional unit comprising a detection device for detecting a gas in the measuring chamber, a voltage source and an electrical circuit by means of which the functional unit can be electrically connected to the voltage source is characterized in that the circuit comprises a transistor which in a deactivation switching position, the functional unit separates from the voltage source and connects the functional unit to the voltage source in an activation switching position.

Description

The invention relates to a hazard detector, in particular a smoke detector.

Smoke detectors are usually mounted on ceilings and are used to detect smoke in case of fire. For this they have a measuring chamber with one or more inlet openings through which smoke can penetrate into the measuring chamber. In the measuring chamber, for example, an optical detection device is arranged which detects the entry of smoke into the measuring chamber on the basis of a changed scattering behavior for light emitted by the optical detection device. If a permitted smoke concentration in the measuring chamber is exceeded, an optical and / or acoustic alarm is triggered.

In addition, such hazard alarms often have an actuating element, by the actuation of which the proper function of the detection device can be tested. It is also known to switch off an example unwanted alarm by pressing the actuator.

Known hazard alarms can be supplied with electrical energy via a power connection laid in a wall or ceiling. This, however, a considerable installation effort is connected. This is especially true when in buildings a large number of danger detectors must be installed, which is the case regularly. It is therefore also known to equip hazard alarms with a battery as an electrical energy source to reduce installation costs.

Hazard detectors, which are supplied with the necessary electrical energy for operation via a battery, are regularly expected to have an operating time of at least ten years after commissioning, without the need to change the battery. As a result, the maintenance of such hazard alarms should be kept within limits. The problem may be that there is an indefinite storage time between the time of production of a hazard alarm and the start-up time, which can often be up to one year. So that the battery is charged as little as possible during this storage time, it can be provided that this is connected only when the hazard alarm is put into operation with the electrical consumers. This is to reduce the load on the battery during the storage time on the self-discharge of the battery and possible leakage currents.

For the separation or connection of the battery with the electrical loads simple mechanical switches can be used. However, this can be associated with several disadvantages.

On the one hand, the closer should be designed nobly and ideally have gas-tight sealed gold contacts so that it is not high impedance during the life of the hazard alarm. The less noble the contact material of the switch or switches, the more likely a corrosion takes place, whereby the contact resistance can rise sharply. This would increase the drop in the battery voltage across the switch (s), which could result in premature battery replacement because of the correspondingly reduced operating voltage for the electrical loads.

Another disadvantage of using a simple mechanical switch may be that the first time the switch is closed, the capacitive elements of the electrical loads are charged, with pulse currents of several amperes over a period of up to 100 μs. This can lead to a sparking and resulting burning of the contact materials of the switch. On the one hand, this can directly result in a greatly increased contact resistance, which in turn either greatly reduces the operating time or even operation of the hazard alarm completely prevented. Furthermore, the sparking can lead to sticking or welding of the closed contacts of the switch, which possibly prevents the battery from being disconnected again by the electrical consumers, for example when the danger detector is being uninstalled.

Another problem is that switches that have both a high pulse current carrying capacity, as well as a high-quality, corrosion-resistant gold contact, are difficult to obtain. In particular, a Goldkontaktierung is usually found only in very small-sized switches, which in turn are provided due to their size only for the conduction of very low currents. Data sheets of common switch manufacturers usually have only the DC continuous load, which is regularly far below the required pulse load.

Based on this prior art, the present invention seeks to provide a hazard detector, especially smoke detectors, which allows advantageously to separate the electrical loads during a storage period of the danger detector from a voltage source, in particular battery, while a simple and in particular safe connection of the electrical consumers with the voltage source during installation is possible.

This object is achieved by a hazard detector according to claim 1. Advantageous embodiments thereof are claimed in the further claims and will become apparent from the following description of the invention.

The invention is based on the idea, in the electrical connection between electrical consumers of a hazard alarm and a voltage source, in particular DC voltage source, for the danger detector, which may be in particular in the form of a battery, a transistor as (electric) Integrate switch. By means of the transistor, the electrical consumers can advantageously be disconnected from the voltage source or electrically connected to it.

According to the invention, a generic danger detector comprising at least one measuring chamber, a functional unit comprising a detection device for detecting a gas in the measuring chamber, a voltage source and an electrical circuit by which the functional unit is electrically connectable to the voltage source comprises the circuit comprises a transistor which disconnects the functional unit from the voltage source in a deactivation switching position and connects the functional unit to the voltage source in an activation switching position.

An advantage that results from the inventive use of a transistor as a switch for disconnecting and connecting the functional unit from / to the voltage source, lies in the insensitivity of common transistors with respect to pulse currents, which is in particular due to the fact that they do not build spark gaps. It is also advantageous that transistors available on the market are regularly checked by the manufacturers for their pulse current carrying capacity, so that reliable data are available for the selection of a suitable transistor for the production of a hazard detector according to the invention. Furthermore, transistors are generally not susceptible to coagulation, so that expensive additional treatments, as may be required in the prior art as precious metal coatings for switches, which may also have to be gas-tight if necessary, can be dispensed with.

In a preferred embodiment of the danger detector according to the invention can be provided that the circuit also has a mechanical switch whose switching causes a switching of the transistor from the deactivation switching position into the activation switching position (and preferably vice versa).

According to the invention, a "mechanical switch" or a mechanical "changeover switch" is understood to mean such a switch which has at least two contact elements which have a spatial distance from one another in a first switching position which interrupts an electrical connection and which switches when switching the (re) Switches are moved towards each other to a contacting, whereby the interruption of the electrical connection is canceled. In this case, the movement of the contact elements in any manner, in particular mechanically and / or (electro-) magnetic (for example, in a reed switch) take place.

The combination of a transistor and a mechanical switch in the circuit of the danger detector according to the invention allows a simple switching of the transistor by the operation of the mechanical switch.

In particular, it can be provided that the mechanical change-over switch can be switched over by attaching a base unit comprising the measuring chamber, the functional unit, the voltage source and the electrical circuit in a holder. The posture may in particular be intended to be fastened to a mounting surface, in particular to a wall or ceiling of a room to be monitored by means of the danger detector, independently of the base unit.

In a preferred embodiment of the danger detector according to the invention can be provided that the transistor is designed as a FET (field effect transistor) and in particular as a MOSFET (metal oxide semiconductor field effect transistor). Then, it can further be provided that in a first switching position of the mechanical switch, a same electrical potential at the source terminal and the gate terminal of the FET (or MOSFET) is set, while in a second Switching position, an electrical potential difference between the source terminal and the gate terminal of the FET (or MOSFET) is set.

An equalization of the electrical potential at the source terminal on the one hand and the gate terminal on the other hand can preferably be achieved in that in the first switching position of the mechanical switch, the gate terminal of the FET (or MOSFET) via at least one (preferably high-resistance) resistor is connected to a first pole of the (DC) voltage source. The generation of the electrical potential difference, which is to be achieved by switching the mechanical switch to the second switching position, however, can be effected in that the gate terminal of the FET (or MOSFET) connected via at least one resistor to a second pole of the voltage source is. The resistors thus act as so-called pull-up or pull-down resistors, by means of which the electrical potential at the gate terminal of the FET (or MOSFET) is matched to the electrical potentials of the respective poles of the voltage source. If these resistors are selected to be relatively high-impedance, the currents flowing in the process can be kept low.

In one embodiment of the danger detector according to the invention can be provided that the FET is a p (conducting) MOSFET and in the first switching position of the mechanical switch, the gate terminal of the p-MOSFET is connected to the positive pole of the voltage source.

In a further embodiment of the danger detector according to the invention can also be provided that the FET is an n- (conductive) MOSFET and in the first switching position of the mechanical switch, the gate terminal of the n-MOSFET is connected to the negative terminal of the voltage source.

In a further preferred embodiment of the danger detector according to the invention, means for determining the potential at the gate connection be provided of the FET (or MOSFET). This makes it possible to realize a functionality, according to which the switching position of the mechanical changeover switch, in particular as a function of the switching position of the transistor, can be automatically checked. Such a shift position detection can in particular make it possible to generate an alarm in the event of an unauthorized deinstallation, for example by detaching the base unit from the holder. It can also be provided to regulate the operation of a radio module, which preferably comprises the danger detector according to the invention, as a function of the automatically recognizable circuit position of the mechanical changeover switch. In particular, it may be provided that the radioactivity of the radio module is reduced in the deactivation switching position of the transistor in comparison to the activation switching position. The energy consumption of the hazard detector can thus be minimized until complete installation, which is preferably completed by attaching the base unit in the holder.

In particular, when the hazard detector according to the invention comprises such a radio module, means for bridging the transistor can furthermore be provided. This may allow the danger detector to be put into operation temporarily before the final installation. This makes it possible, in particular, to couple several hazard alarms according to the invention in a comfortable manner to a radio network, since this can be done independently of the intended installation sites for the individual hazard alarms, which can often be provided poorly accessible to ceilings of several rooms.

The functional unit of the danger detector according to the invention may preferably comprise all functional elements required for the basic function of the hazard alarm. In addition to the detection device, which may be formed for example as an optical detection device, this can in particular be a control unit, an actuator and / or an alarm (acoustic and / or optical). It can be provided in particular that the individual functional elements of the functional unit are electrically conductively connected via printed conductors (at least) of a printed circuit board. The control unit may include a processor and a memory, on which operating software is stored, which is designed for the evaluation of signals transmitted by the detection device, and can thereby close to the exceeding of a limit value for a gas to be detected, in particular flue gas. The control unit may be further configured to transmit an alarm signal to an alarm device when the threshold has been exceeded. The alarm device may be, for example, an optical and / or acoustic alarm, which are then preferably likewise integrated in the functional unit and, in particular, permanently and electrically connected to the printed circuit board of the functional unit. The control unit can furthermore be designed to perform or permit a functional test of the detection device upon actuation of the actuating element and / or to interrupt an already triggered alarm of an alarm device. The control unit can also be set up to carry out the automatic switching position detection already described and the optionally dependent regulation of the radio activity of the radio module.

Fig. 1:

einen erfindungsgemäßen Gefahrenmelder in einer Explosionsdarstellung;

Fig. 2:

einen Längsschnitt durch den Gefahrenmelder in einer perspektivischen Darstellung;

Fig. 3:

die Integration einer Batterie in den Gefahrenmelder;

Fig. 4:

ein Schaltbild einer elektrischen Schaltung für den Gefahrenmelder in einer ersten Ausgestaltung; und

Fig. 5:

ein Schaltbild einer elektrischen Schaltung für den Gefahrenmelder in einer zweiten Ausgestaltung.

The invention will be explained in more detail with reference to an embodiment shown in the drawings. In the drawings shows:

Fig. 1:

a danger detector according to the invention in an exploded view;

Fig. 2:

a longitudinal section through the hazard detector in a perspective view;

3:

the integration of a battery in the hazard detector;

4:

a circuit diagram of an electrical circuit for the hazard detector in a first embodiment; and

Fig. 5:

a circuit diagram of an electrical circuit for the hazard detector in a second embodiment.

The hazard detector shown in the drawings comprises a base unit. This has a housing with a housing lower part 1 and a housing upper part 2. Furthermore, a arranged between the lower housing part 1 and the upper housing part 2 functional unit 3 and a radio module 4, which, based on the functional unit 3, is arranged on the other side of a formed from the lower housing part 1 partition 5, is provided.

An underside of the danger detector is intended for installation and attachment to a surface, in particular on a ceiling or wall of a room. For this purpose, a holder of the housing, not shown, which is detachably connected to the lower housing part 1 is used. This makes it possible to first fix the holder to the surface independently of the base unit, for example by screwing it on, and only then to connect the base unit to the holder. This can be done for example via formed between the holder and the lower housing part 1 locking connections and / or a bayonet connection. The holder may be designed such that it partially or completely closes the receiving space formed by the lower housing part 1 and accommodating the radio module 4.

The lower housing part 1 forms on the housing upper part 2 facing side of its partition 5 from a tubular housing portion 6, which limits a measuring chamber 7 circumferentially. A bottom surface 8 of the measuring chamber is likewise formed by the dividing wall 5 of the housing lower part 1.

In the tubular housing section 6 are two upwards, i. in the direction of the upper housing part 2 open receiving housing 9 is integrated, which serve to receive two at a defined angle to each other, optical detection elements 10 of a detection device. The two detection elements 10, one of which comprises an optical radiation source and the other an optical radiation receiver, are aligned such that their optical axes intersect each other and a longitudinal axis 11 of the measuring chamber 7 at one point. A partition wall 12 protruding into the measuring chamber 7 prevents a direct "visual contact" of the two detection elements 10.

Furthermore, a control unit (not visible), a sounder 14, an actuator 15 and a connector 16 are fixed and electrically conductive to the circuit board 13 connected. All of these functional elements are arranged on the same surface of the printed circuit board 13.

By an actuation of the actuating element 15, a functional test of the hazard alarm can be performed and this also be switched off again after a successful triggering.

The connector 16 serves to electrically connect the radio module 4 to the functional unit 3. For this purpose, the radio module 4 a corresponding, also connected to a circuit board 17 connector 18 with a plurality of pin contacts, which are provided for engagement in corresponding socket contacts of the connector 16 of the functional unit 3. In this case, the pin contacts pass through both the partition wall 5 of the housing base 1, which is provided for this purpose with an opening for all pin contacts, as well as the circuit board 13 of the functional unit 3, which is provided for this purpose with a corresponding number of individual openings.

The radio module 4 has a radio transceiver unit (not visible) through which a radio-based networking of several hazard detectors can be filed. This allows, for example, a detected by a hazard alarm, triggering an alarm triggering concentration of a gas the networked hazard alarms, in which case an alarm and / or audible alarm is triggered by all the hazard detectors.

The upper housing part 2 forms a cover-shaped housing section 19, which limits the measuring chamber 7 at its upper axial end. In this case, the cover-shaped housing section 19 is arranged at a distance from the free end of the tubular housing section 6 of the housing lower part 1 (cf. Fig. 2 ), whereby an at least partially encircling inlet opening 20 is formed, through which gas to be detected can flow into the measuring chamber 7. Of the lid-shaped housing portion 19 of the upper housing part 2 extend in the direction of the lower housing part 1 at least two circumferential, spaced in the radial direction of the tubular housing portion 6 collar 21, one of which is disposed on the inside and the other outside of the measuring chamber 7 and so far extend in the direction of the lower housing part 1 that they cover the inlet opening 20 and a piece and the tubular housing portion 6 in the axial direction. The collars 21 serve to prevent penetration of ambient light via the inlet opening 20 into the measuring chamber 7 as much as possible by shielding them.

From the outer collar 7 extending with circumferentially substantially uniform pitch radially with respect to the longitudinal axis 11 of the measuring chamber 7 aligned baffles 22. These serve to direct a flow of gas to be detected in the most direct way to the inlet port 20 and thereby a spiral Flow to avoid the outside of the tubular housing portion 6 with a circumferentially directed flow component. The free ends of the baffles 22 are for a system provided on the printed circuit board 13 of the functional unit 3, while the printed circuit board 13 of the functional unit in turn rests on the receiving housings 9 formed by the lower housing part 1. As a result, the printed circuit board 13 is held between the lower housing part 1 and the upper housing part 2.

The free ends of the baffles 22 are fixed via part-ring-shaped stabilizing elements 23. As a result, these are protected against damage due to deformation, in particular during installation of the hazard alarm. Furthermore, it is provided that the radially inner edges of the baffles 22 abut in the mounted state of the danger detector on the outside of the tubular housing portion 6.

All larger, the measuring chamber 7 bounding surfaces of the lower housing part 1 and the upper housing part 2 are provided with a tooth-shaped contour. This serves to scatter the light emitted by the optical radiation source of the corresponding detection element 10 in order to prevent direct reflection on the optical radiation receiver of the other detection element 10.

The upper housing part 2 also still forms two cover sections 25, by which the receiving housings 9 with the detection elements 10 received therein are closed in the mounted state of the danger detector. An intrusion of ambient light into the measuring chamber 7 via the receiving housing 9 is thereby prevented as possible.

The housing may further comprise a housing cover, not shown, which can be placed on the housing upper part and connected via a bayonet connection thereto. The lower housing part 1 forms this closure tabs 24. The housing cover surrounds the housing upper part 2 and the functional unit 3 and thus protects them from damage by external Violence. Through openings in the housing cover simultaneously ensure that gas to be detected can flow into the measuring chamber 7.

The functional elements of the hazard alarm are supplied by means of a battery 26 with the required electrical energy for operation. The battery 26 is arranged in a battery compartment, which is arranged for the most part within the recording module of the housing which also accommodates the radio module 4. The battery compartment is bounded at the top by a section of the circuit board 13 of the functional unit 3, downwardly from the bottom plate and laterally by the insides of a through opening 27 formed in the partition wall 5 of the lower housing part 1, and the battery 26 thus securely held within the danger detector.

An electrically conductive connection between the poles of the battery 26 and corresponding contact points 28 of the circuit board 13 of the functional unit 3 is realized by means of contact elements 29. Each of the contact elements 29 comprises two contact tabs 30, wherein the contact tabs 30 extend in the direction of the printed circuit board 13 and each contact one of the contact points 28 on the printed circuit board 13 with their end sections (cf. Fig. 3 ). In this case, the contact tabs 30 are at least slightly deformed elastically in the assembled state of the hazard alarm, whereby a sufficiently large contact pressure is provided. In order to keep the contact resistance permanently low, the contact elements 29 and also the conductor tracks of the printed circuit boards 13, 17 can be made gold-plated.

The supply of the functional elements of the hazard alarm with electrical energy by the battery 26 can be controlled by an electrical circuit. Two embodiments of such circuits, which are preferably integrated in the functional unit 3 are in the 4 and 5 shown.

The circuit according to the Fig. 4 comprises a transistor in the form of a p-MOSFET 31. The p-MOSFET 31 is in a known manner in combination with a parasitic Diode 32 is provided, which is connected between the source terminal 33 and the drain terminal 34. Furthermore, the circuit comprises two high-impedance resistors 35 (eg, 1 MS2 to 10 MS2) and a mechanical switch 36, which is shown here in the form of two separate simple switches 37, 38, which are switched synchronously.

The p-MOSFET 31 is integrated with the source terminal 33 and the drain terminal 34 in a first electrical connection path between the positive pole 39 of the battery and a ground terminal 43, which in turn is connected to the negative pole 40 of the battery. In this electrical connection path are on the drain side of the p-MOSFET 31 also the functional elements of the hazard detector, which are supplied by the battery 26 with the required electrical energy for operation integrated. These are in the Fig. 4 simplified in the form of a single consumer 41 shown. Via a second electrical connection path, the positive pole 39 of the battery 26 can be connected to the gate terminal 42 of the p-MOSFET 31. In this second connection path, the two resistors 35 and a first switch 37 of the switch 36 are integrated. Via a third electrical connection path, the negative pole 40 of the battery 26 can be connected to the gate terminal 42 of the p-MOSFET 31. This electrical connection integrates the second switch 38 of the switch 36 and one of the two resistors 35.

In the delivery state of the hazard alarm, ie before it is put into operation, there is the switch 36 in the in the Figure 4 shown switching position, which leads to a deactivation switching position of the p-MOSFET. In this switching position of the switch 36, the first switch 37 is closed and the two switches 38 are opened. As a result, the gate terminal 42 of the p-MOSFET 31 is charged via the two resistors 35, that is, brought to the positive electric potential of the positive pole 39 of the battery 26. The potential equality thus achieved between the source terminal 33 and the gate terminal 42 ensures that the p-MOSFET 31 blocks and thus no relevant current flow between the source terminal 33 and the drain terminal 34 is possible. As a result, the consumer 41 of the danger detector is cut off from a power supply by the battery 26. In this deactivation switching position of the p-MOSFET, the energy consumption of the danger detector is essentially limited to the self-discharge of the battery 26. In addition, there is a very low energy loss, which results from a correspondingly low current flow between the positive pole 39 of the battery 26 and the ground terminal 43 via the two resistors 35, the blocking layer of the p-MOSFET 31 and the load 41.

For the commissioning of the hazard alarm, the switch 36 must be switched and thereby the p-MOSFET to be switched to an activation switching position. The switching of the switch 36 is preferably carried out automatically when attaching the base unit to the holder. The switching causes opening of the first switch 37 and closing of the second switch 38. Thereby, the gate terminal 42 of the p-MOSFET 31 can be discharged via the closed third connection path, i. be brought to the negative electric potential of the negative pole 40 of the battery 26. The potential difference thus set between the source terminal 33 and the gate terminal 42 of the p-MOSFET 31 provides for opening the p-MOSFET 31. The load 41 is then connected to both poles of the battery 26 via the first connection path and thus becomes powered by this with electrical energy.

As a result of the opening of the first switch 37, the current flow through the two resistors 35 is prevented. Accordingly, the energy consumption of the hazard alarm is not increased to the relevant extent by self-consumption of the electrical circuit in the operating state.

The activation or deactivation of the hazard detector by means of the electrical circuit has a number of advantages. In particular, the switch 36 does not have contact elements made of noble materials, since even if the contact surfaces of the contact elements within the operating life of the danger detector due to corrosion continuously high impedance, no problems are to be expected from this because the switch only for the function of the shop and Discharging the gate terminal 42 of the p-MOSFET 31, ie is used for switching the electrical circuit, but not for conducting the required for the operation of the hazard alarm current. For this purpose, even bleeder resistors in the higher MΩ range would suffice, which are hardly to be expected even with very advanced corrosion of the contact elements.

In addition, no high currents flow when the changeover switch 36 is actuated for the first time, so that the changeover switch 36 does not have to meet any special requirements with regard to the pulse current carrying capacity. A spark on the switch 36 is therefore not expected.

A pulse current that occurs due to capacitive elements in the electrical system of the hazard alarm when first activated flows exclusively through the p-MOSFET 31, which is regularly unproblematic because transistors are tested by the manufacturers usually on the pulse current carrying capacity and thus correspondingly reliable transistors for Training the electrical circuit are available. Furthermore, in comparison with mechanical switches, transistors are fundamentally much better able to be loaded with pulse currents, since no spark gaps are built up in them. Corrosion problems are also not expected in commercial transistors.

The electrical circuit also provides the ability to temporarily activate the hazard detector independently of attaching the base unit to the bracket. This can be provided in particular if a plurality of Hazard detectors are to be coupled by means of the built-in these radio modules 4 to a wireless network. This should not be done to simplify the handling only when already mounted in the brackets base units, as this, for example, a manual switching of the radio modules 4 each hazard alarm in a coupling state, for example by means of the actuator 15 must be made. For this purpose, it should therefore be possible to place all provided for the wireless network hazard side by side on, for example, a table, so that they are easy and quick to handle.

Such a temporary activation of the danger detector can be done by bridging the p-MOSFET 31, for which purpose the electrical circuit has a bridging connection 44 both on the source side and on the drain side of the p-MOSFET 31. If these bridging connections 44 are connected to one another in an electrically conductive manner, the load 41 and thus also the radio module 4 are supplied with electrical energy by the battery without the p-MOSFET 31 being bypassed, without the changeover switch 36 having to be switched over.

Without switching the switch 36, the potential at the gate terminal 42 of the p-MOSFET 31 remains unchanged and corresponds to the potential of the positive pole 39 of the battery 26. By monitoring this potential, to which the electrical circuit is provided with a corresponding terminal 45, is allows, when activated, ie energized consumer 41 to check in which switching position, the switch 36 is located. In particular, this can serve to reduce the radioactivity of an activated by bridging the p-MOSFET 31, but not mounted in the holder and thus not yet put into operation hazard detector and in particular to only that radio activity that is required for coupling with other hazard detectors to restrict. As a result, an increased energy consumption by an increased, provided for the operation of the hazard detector radioactivity during the

Bridging the p-MOSFET 31 can be prevented. Likewise, it can be provided to detect by monitoring the potential at the gate terminal 42 of the p-MOSFET 31, whether the hazard detector is released from the holder when the p-MOSFET 31 is bridged and thus in the still activated state, which involves switching the changeover switch 36 and thus a potential drop at the gate terminal 42 would be connected.

The in the Fig. 5 shown electrical circuit is different from that of Fig. 4 in the interchanging of the poles of the battery 26 and a thus justified use of an n-MOSFET 46 instead of a p-MOSFET. The function of the electrical circuit and the functionality of the hazard alarm enabled by this corresponds to that of the circuit of Fig. 4 ,

LIST OF REFERENCE NUMBERS

1

Housing bottom

2

Housing top

3

functional unit

4

radio module

5

Partition wall of the housing base

6

tubular housing section

7

measuring chamber

8th

Bottom surface of the measuring chamber

9

receiving housing

10

detection element

11

Longitudinal axis of the measuring chamber

12

Partition of the measuring chamber

13

Printed circuit board of the functional unit

14

control unit

15

actuator

16

Plug connector of the functional unit

17

Printed circuit board of the radio module

18

Plug-in connector of the radio module

19

cover-shaped housing section

20

inlet port

21

collar

22

baffle

23

stabilizing element

24

Locking tab of the housing base

25

cover section

26

battery

27

Through opening in the partition wall of the housing base

28

Contact point of the circuit board

29

contact element

30

Contact tab

31

p-MOSFET

32

diode

33

Source terminal

34

Drain

35

resistance

36

switch

37

first switch

38

second switch

39

Positive pole of the battery

40

Negative pole of the battery

41

consumer

42

Gate terminal

43

ground connection

44

bridging connection

45

Connection for potential monitoring

46

n-MOSFET

Claims (11)

Hazard detector having a measuring chamber (7), a detecting means for detecting a in the measuring chamber (7) located gas comprehensive functional unit (3), a voltage source and an electrical circuit by which the function unit (3) to the voltage source is electrically connectable, characterized characterized in that the circuit comprises a transistor which separates the functional unit (3) from the voltage source in a deactivation switching position and connects the functional unit (3) to the voltage source in an activation switching position. Hazard detector according to claim 1, characterized by a mechanical switch (36), the switching of which causes either a switching of the transistor from the deactivation switching position into the activation switching position or a switching of the transistor from the activation switching position into the deactivation switching position. Hazard detector according to Claim 2, characterized in that the changeover switch (36) can be switched in a holder by attaching a base unit comprising the measuring chamber (7), the functional unit (3), the voltage source and the circuit. Hazard detector according to claim 2 or 3, characterized in that the transistor is designed as a FET, wherein in a first switching position of the switch (36) an equal electrical potential at the source terminal (33) and the gate terminal (42) of the FET is set, while in a second switching position, an electric potential difference between the source terminal (33) and the gate terminal (42) of the FET is set. Hazard detector according to claim 4, characterized in that in the first switching position of the switch (36) of the gate terminal (42) of the FET via at least one resistor (35) is connected to a first pole of the voltage source and in the second switching position of the switch ( 36), the gate terminal (42) of the FET is connected via at least one resistor (35) to a second pole of the voltage source. Hazard detector according to claim 5, characterized in that the FET is a p-MOSFET (31) and in the first switching position of the switch (36) of the gate terminal (42) of the p-MOSFET (31) with a positive pole (39) of Voltage source is connected. Hazard detector according to claim 5, characterized in that the FET is an n-MOSFET (46) and in the first switching position of the switch, the gate terminal (42) of the n-MOSFET (46) is connected to a negative terminal (40) of the voltage source , Hazard detector according to one of claims 4 to 7, characterized by means for determining the potential at the gate terminal (42) of the FET. Hazard detector according to one of the preceding claims, characterized by means for bridging the transistor. Hazard detector according to one of the preceding claims, characterized by a radio module (4) which is electrically connected to the functional unit (3). Hazard detector according to claim 10, characterized in that the radioactivity of the radio module (4) is reduced in the deactivation switching position of the transistor in comparison to the activation switching position.

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