EP3513395B1 - Smoke detector and method for monitoring a smoke detector - Google Patents

Description

The invention relates to a fire, smoke or smoke alarm, referred to briefly in the following as a smoke detector, a smoke detector system and a method for monitoring a smoke detector, namely a method for monitoring a smoke detector for the presence of adjacent interfering objects.

Smoke detectors are known per se and are used for the early detection of smoke development due to a fire. From the DE 10 2013 003614 a smoke detector is known with a cover plate, the contamination of which is monitored by means of guided radiation. From the EP 2 348 495 A1 is a smoke detector for closed rooms with a mountable to a mounting surface (ceiling or wall) is known, in which a smoke chamber with smoke inlets is divided in a basically known manner, with measuring electronics being arranged in the smoke chamber, which detects smoke particles evaluable measurement signal generated. In addition, this smoke detector has at least one ultrasound transceiver on its front, which is arranged such that it can emit ultrasound signals into a hemispherical area below the smoke detector and can receive reflected ultrasound signals.

By emitting ultrasound signals and receiving reflected ultrasound signals, objects located in the immediate vicinity of the smoke detector are to be recognized, which can impair the safe operation of the smoke detector. This is to prevent situations in which, due to the proximity of the smoke detector placed furnishings or the like, the detection function of the smoke detector is drastically deteriorated due to shadowing and / or thermal influences.

Smoke detectors of the type described are preferably used in living rooms, since the people present there in most cases have little knowledge of the spread of smoke and are therefore difficult to assess what is permissible and what could impair safety. At the same time, there is a particularly high risk in living rooms of being surprised by a fire while sleeping, so it is particularly important that smoke detectors are in working order.

A disadvantage of the arrangement mentioned is that the radiation source and the receiver have to be located on the underside of the smoke detector and that they have to be able to emit sound waves somewhat unhindered. As a result, there is a form of smoke detector that cannot be aesthetically pleasing and is unsuitable in a living room. The present invention is intended to make it possible to recognize the presence of interfering objects without the need for components that are visible from below. It is therefore possible to design the smoke detector so that it also meets high aesthetic standards.

According to the invention, this object is achieved by means of a smoke detector with the features of claim 1. For this purpose, the following is provided in a smoke detector, which comprises a sensor system as a means of detecting an object in the vicinity of the smoke detector (adjacent object): by means of the sensor system, signals, in particular sound waves in the ultrasound range, can be emitted and received, and such sensors become operational when the sensor system is operated Signals sent out and possibly from a neighboring object receive reflected signals. Such received signals can be evaluated for the detection of an adjacent object and are evaluated during the operation of the sensor system for the detection of a neighboring object. As a sensor system and as a means for detecting an adjacent object, the smoke detector comprises a transmitter or a plurality of transmitters and a receiver or a plurality of receivers, the transmitter and receiver being able to be combined in one component, each transmitter for emitting a signal, in particular for Radiating ultrasound, in a radiation direction and the or each receiver for receiving and for detecting a signal arriving from a receiving direction, in particular energy in the range of ultrasound, is determined and set up. In a special embodiment of the smoke detector, the at least one transmitter is separated from the at least one receiver and is spatially separated from the receiver in a housing of the smoke detector, since with such an arrangement it is easier to separate the transmitted signals from the received signals. In operation, ultrasound of a sufficiently high frequency is preferably, but not necessarily, used so that the transmitted signals cannot be heard by people or animals present, but also because ultrasound can be bundled or shaped in a relatively simple manner in the desired manner. The transmitters are aligned so that during operation they radiate away from the smoke detector on a base or mounting surface (ceiling, wall) on which the smoke detector is attached. The transmitters are so aligned that their direction of radiation points towards the mounting surface of the smoke detector and the emitted signals are reflected on the mounting surface and then spread in the respective room that is to be monitored for the presence of objects.

In a smoke detector system with a smoke detector according to the invention and with a detector base for the detachable attachment of the smoke detector to the detector base, the detector base is provided for attachment to a ceiling or wall. The detector base is designed in such a way that it takes the place of the mounting surface in the captured state of the smoke detector or forms the mounting surface itself, onto which the transmitters radiate in an oblique direction away from the smoke detector.

In a method for operating and monitoring such a smoke detector, signals, in particular signals in the ultrasound range, are emitted in an oblique direction away from the smoke detector onto the mounting surface, reflected on the mounting surface and emitted into the surrounding space by means of the sensor system.

In the case of an object in the vicinity of the smoke detector, the emitted radiation is reflected by the object and the reflected radiation is detected by means of the sensor system of the smoke detector. On the basis of such a detection, an alarm signal is triggered automatically and, for example, an optical and / or acoustic signal element is triggered by means of the alarm signal or the alarm is also passed on to a central device in a suitable manner. The signal element is, for example, a loudspeaker.

The radiation is emitted by means of the sensor system, for example, at predetermined or predeterminable, in particular equidistant, times, for example every ten minutes, every hour, etc. The smoke detector is monitored in such a way that it is recognizable and automatically recognized in operation, whether there is an object near the smoke detector. Such an object can cover or shade the smoke detector, so that its function can be impaired.

Instead of ultrasound, another type of radiation, in particular sound waves in the audible range, but also light in the visible or invisible range as well as radio waves, in particular microwaves, or generally electromagnetic waves, as described in the EP 2 043 068 B1 is used. Signal types other than ultrasound are nevertheless always to be read in the following description. So far, however, the use of ultrasound has been particularly simple and generally has the lowest possible costs.

Advantageous embodiments of the invention are the subject of the dependent claims. References used here indicate the further development of the subject matter of the main claim through the features of the respective subclaim. They are not to be understood as a waiver of the achievement of independent, objective protection for the combinations of features of the related subclaims. Furthermore, with regard to an interpretation of the claims in the case of a more specific specification of a feature in a subordinate claim, it can be assumed that such a restriction does not exist in the respective preceding claims. Finally, it should be pointed out that the method specified here can also be developed in accordance with the dependent device claims and vice versa.

In a first, particularly simple embodiment, the smoke detector comprises ultrasonic transducers which can function as transmitters and receivers and which have a radiation characteristic in the required and necessary form without additional measures.

In a further embodiment of the smoke detector, it comprises at least one reflection surface in a beam path from a respective transmitter to the mounting surface. This allows the beam direction to be influenced by the orientation of the reflection surface and / or beam shaping by a respective surface shape of the reflection surface.

In a special embodiment of the smoke detector, this comprises one or more receivers placed or placed inside the smoke detector. For example, an electret microphone or a microphone using silicon technology can be considered as the receiver.

According to a further embodiment, the transducers or the transmitters are arranged in the smoke detector in such a way that the lobe of the respective emitted signal strikes the mounting surface at an angle in the range from 30 ° to 60 °, in particular in a range from 40 ° to 50 °. A preferred value for this angle is 45 °. The lobe of the transmitted signal of the respective converter or transmitter is formed around a main emission direction of the respective converter or transmitter. It is essentially rotationally symmetrical about this main emission direction.

In a further embodiment of the smoke detector, transducers comprised by this as sensors function spatially alternately as transmitters or receivers. In this way, objects in close proximity to the smoke detector can also be recognized with a correspondingly short transit time of an ultrasound signal emitted by the sensor system of the smoke detector and reflected by the object. In the case of a function of a transducer which alternates in time and which initially acts as a transmitter and later as a receiver, the transmitted signal must have decayed sufficiently to be able to To be able to use transducers as receivers. A spatially alternating arrangement is therefore advantageous, but is associated with greater costs.

In the case of a function of the transducer that alternates in time, either as a transmitter or as a receiver, there is a requirement and difficulty for the or each transducer functioning as a receiver that an oscillation resulting during a function as a transmitter has decayed sufficiently so that the reflected ultrasound signal can be recognized. Such an embodiment of the smoke detector and a corresponding method for its operation, i.e. a method in which the transducers included by the smoke detector as sensors function spatially or temporally alternatingly as transmitters or receivers, are independent of a smoke detector with transmitters oriented on the mounting surface Embodiment.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Corresponding objects or elements are provided with the same reference symbols in all figures.

The exemplary embodiment is not to be understood as a limitation of the invention. Rather, additions and modifications are also possible within the scope of the present disclosure, in particular those which, for example, by combining or modifying individual elements in conjunction with the features or method steps described in the general or special description part and in the claims and / or the drawings for can be taken from the person skilled in the art with regard to the solution of the task and by combinable features to a new object or to new method steps or result in procedural steps.

FIG 1

einen Rauchmelder mit einer zusätzlichen zur Detektion von in der Nähe des Rauchmelders vorhandenen Objekten bestimmten Sensorik,

FIG 2

ein Zeitdiagramm zur Illustration einer Sensorik in Form eines als Sender und Empfänger fungierenden Wandlers, insbesondere Ultraschallwandlers,

FIG 3

den Rauchmelder gemäss FIG 1 im Querschnitt,

FIG 4

den Rauchmelder gemäss FIG 1 mit einem Gehäuse im Querschnitt,

FIG 5

den Rauchmelder gemäss FIG 4 angebracht an einem Meldersockel als Montagefläche im Querschnitt,

FIG 6

den Rauchmelder gemäss FIG 1 mit zusätzlichen Reflektorflächen im Querschnitt,

FIG 7

einen Rauchmelder ähnlich wie in FIG 1, mit einer Überwachungsvorrichtung und mit getrennten Sendern und Empfängern,

FIG 8

einen Rauchmelder ähnlich wie in FIG 1, der jedoch das von einem Wandler ausgesandte und reflektierte Signal nicht mit dem gleichen Wandler, sondern mit einem benachbarten Wandlern empfängt,

FIG 9

eine zeitliche Darstellung der Signale, die in einem Rauchmelder gemäss FIG 8 vorkommen können,

FIG 10

einen Rauchmelder mit zwei getrennten Sendern und zwei getrennten Empfängern,

FIG 11

einen Rauchmelder gemäss FIG 10 im Querschnitt,

FIG 12

einen Rauchmelder gemäss FIG 10, wobei aber der Empfänger nicht zur Montagefläche, sondern davon weg orientiert ist und

FIG 13

einen Rauchmelder mit einer zur Detektion von in der Nähe des Rauchmelders platzierten Objekten bestimmten Sensorik sowie einen mittels der Sensorik ansteuerbaren optischen und/oder akustischen Aktor.

Show it

FIG. 1

a smoke detector with an additional sensor system intended for the detection of objects present in the vicinity of the smoke detector,

FIG 2

2 shows a time diagram to illustrate a sensor system in the form of a transducer that acts as a transmitter and receiver, in particular an ultrasound transducer,

FIG 3

according to the smoke detector FIG. 1 in cross section,

FIG 4

according to the smoke detector FIG. 1 with a housing in cross section,

FIG 5

according to the smoke detector FIG 4 attached to a detector base as a mounting surface in cross section,

FIG 6

according to the smoke detector FIG. 1 with additional reflector surfaces in cross section,

FIG 7

a smoke detector similar to that in FIG. 1 , with a monitoring device and with separate transmitters and receivers,

FIG 8

a smoke detector similar to that in FIG. 1 which, however, receives the signal emitted and reflected by one converter not with the same converter but with an adjacent converter,

FIG. 9

a temporal representation of the signals according to a smoke detector FIG 8 can occur

FIG 10

a smoke detector with two separate transmitters and two separate receivers,

FIG 11

a smoke detector according to FIG 10 in cross section,

FIG 12

a smoke detector according to FIG 10 , but the receiver is not oriented towards the mounting surface, but away from it and

FIG. 13

a smoke detector with a sensor system intended for the detection of objects placed in the vicinity of the smoke detector and an optical and / or acoustic actuator which can be controlled by means of the sensor system.

The representation in FIG. 1 shows, in a schematically simplified form, a top or bottom view of a smoke detector 10 with three regularly spaced (same or at least essentially the same angular distance) sensors 12, 13, 14 for detecting any neighboring objects 20 in the vicinity of the smoke detector 10. With the reference symbol A is an axis of rotation of the smoke detector 10, in particular its axis of symmetry. The sensors 12, 13, 14 are arranged around this axis of rotation A at the same radial distance and evenly distributed in the circumferential direction. Such an object 20 can be an object 20 placed near the smoke detector 10, for example a piece of furniture, or an object already present before the smoke detector 10 was attached, for example a bar with a supporting or supporting function , act.

The sensors 12-14 are often ultrasound transducers 12-14, also referred to briefly below as transducers 12, 13 and 14, which can be operated both as a transmitter and as a receiver. In their function as transmitters, such transducers 12-14 send out a signal in the ultrasonic range. In their function as receivers, such transducers 12-14 receive a signal in the ultrasonic range.

The representation in FIG 2 shows the signals transmitted and received by one of the transducers 12-14 in a schematic manner in the time domain and shows a short but very strong signal 28 (ultrasound signal) emitted by a transducer 12-14. This propagates at the speed of sound, in the case of an object 20 in the propagation area reaches this after the time t, is reflected on the object 20 (obstacle) and returns to the transducers 12-14 at the same speed. After the time 2t, it reaches the same converter 12-14 as the reflected signal 29, that is to say the converter 12-14 which originally emitted the signal 28, but which now functions as a receiver. In comparison to the transmitted signal 28, the returning signal 29 has been weakened very strongly and the time profile can differ significantly from that in FIG FIG 2 shown situation.

However, it should be noted that the representation in FIG 2 is greatly simplified and in many cases probably too optimistic.

Experiments have shown that using a transducer 12-14 as a transmitter and as a receiver does not work absolutely satisfactorily with respect to an object 20 to be detected. To transmit an ultrasound signal 28 (function as a transmitter), the transducer 12-14 is switched on for a short time (e.g. 200 µs) vibrated. During the time until the reflected signal 29 arrives, for example 3 ms, this oscillation gradually subsides. When the reflected signal 29 arrives, the oscillation must have decayed to such an extent that it is significantly smaller than the received signal 29 so that it can be detected correctly.

It has been shown that if the transducers 12-14 are appropriately connected, it is possible to let the oscillation of the transducer 12-14 functioning as a transmitter decay sufficiently within about 3 ms (for example by means of damping and / or by means of an antiphase Excitation) in order to be able to detect the received signal 29. A transit time of 3 ms, ie 1.5 ms for the outward journey (transmitted signal 28) and 1.5 ms for the return journey (reflected signal 29), correspond to an object 20 at a distance of approximately 0.5 m. Such an object 20 can have a disruptive effect and its detection makes sense. However, it may be that the object 20 is closer to the smoke detector 10, so that the running time is shorter. In the extreme case, the object 20 is even on the surface of the smoke detector 10, for example when it has been covered, in order to avoid false alarms. The detection of the received signal 29 is very difficult and impossible with a transit time of less than 3 ms when the transmit and receive signals 28, 29 are present at the same time, as is the case when the object 20 is on the surface of the smoke detector 10 lies.

In the representation in FIG. 1 it is assumed that there are three transducers 12-14. The transmission signal 28 can be applied to these three converters 12-14 simultaneously. However, it is also possible to apply the transmission signal 28 to the three converters 12-14 one after the other. In this case it is advantageous that the peak power required is smaller, but that is Circuit effort larger.

With the sensor system mentioned, the permanent presence of interfering objects 20, for example pieces of furniture, decorative objects, etc., is to be recognized. Moving objects 20 or a tall person, etc., on the other hand, can be assumed to be uncritical and should not be recognized. The monitoring is therefore preferably carried out at somewhat longer time intervals, for example every 10 minutes, every hour, every x hours or every day, and to avoid false alarms, a message is only triggered when the object 20 has been detected several times, in particular several times in succession Cycles was detected.

The representation in FIG 3 shows the smoke detector 10 attached to a mounting surface 24 according to FIG FIG. 1 in cross section. Only one of the transducers 12-14 can be seen, namely the transducer 12, since the other transducers 13, 14 lie outside the image plane. The transducer 12 is inclined by approximately 45 ° with respect to the vertical, so that the lobe of the transmitted signal 28 is also inclined by this value. The main emission direction of such a converter 12 is designated by HA. The emitted signal 28 is reflected on the respective mounting surface 24, for example the ceiling, and reaches an object 20 lying in the beam path. The signal 28 is reflected there and basically returns to the transducer 12 in the same way as a reflected signal 29.

The representation in FIG 4 shows the smoke detector 10 according to FIG. 1 with a surrounding housing G in cross section. The housing G is preferably designed to be rotationally symmetrical with respect to the axis of rotation A, for example cylindrical here. In addition, there are openings OF in the housing G for the transmission of the transmitted signal 18 and for the possible reception of the reflected one Signals 29 present.

The representation in FIG 5 shows the smoke detector 10 according to FIG 4 , which is in particular detachably attached to a detector base 25 as a mounting surface 24, in cross section. The detector base 25 is provided for attachment to a ceiling or wall. It is preferably designed such that it lies flat there with a first outer side facing the ceiling or wall. An opposite second outside of the detector base 25 is designed such that it is flat in the captured state of the smoke detector 10 and in relation to the axis of rotation A of the smoke detector 10, at least in its radial outer region, to which the transmitted signal 28 from the transducers 12-14 impinges is trained. The detector base 25 thus extends a few centimeters in the radial direction, in particular in a range from 1 to 10 cm, preferably in a range from 2.5 to 5 cm, beyond the radial outer limit of the smoke detector 10. The second outer surface of the detector base 25 therefore runs at least in this radial outer region parallel to the typically flat ceiling surface or wall surface to which the detector base 25 is attached, and it is also flat and preferably smooth. In the recorded state of the smoke detector 10, a surface normal of the flat ceiling surface or wall surface and the axis of rotation A of the fire detector 10 thus run parallel to one another. This guarantees a defined reflection behavior. The detector base 25 is preferably made of the same material as the housing G of the fire detector 10, such as plastic.

The representation in FIG 6 again shows the smoke detector 10 according to FIG. 1 in cross section, but in a second embodiment. In addition to the in FIG 3 The details shown are now a reflective surface inclined by approximately 22.5 ° with respect to the vertical 40 (reflection surface) available. The converter 12 sends its signal 28 perpendicular to the mounting surface 24. It is first reflected on the surface 40, so that it now spreads out at an angle of approximately 45 ° to the mounting surface 24, is reflected there again and now reaches an object 20 lying in the beam path at an angle of 45 °. There, the transmitted signal 28 is reflected and a resulting reflected signal 29 returns in approximately the same way, is reflected on the mounting surface 24 and on the surface 40 and returns to the converter 12. The advantages of this arrangement are the simpler assembly of each transducer 12-14, which can now take place perpendicular to a printed circuit board 11 of the smoke detector 10, and the possibility of appropriately shaping the surface 40, so that the shape of the emitted lobe is better adapted to the respective needs can be. However, the additional space required for surface 40 and the attenuation of the signal when reflecting twice on surface 40 must be taken into account.

It is not always favorable that with a smoke detector 10 according to FIG. 1 the same converter 12-14 is used cyclically as a transmitter and in a short time interval as a receiver. The switchover of the converters 12-14 between these two operating modes (transmitting mode, receiving mode) required for this in a short time is not without problems.

The representation in FIG 7 shows an embodiment of a smoke detector 10 which uses separate transmitters and receivers. For this purpose, in addition to a converter 12-14, which is now only used as a transmitter, a second converter is used as the microphone 15, 16, 17. This embodiment requires a sometimes problematic acoustic separation between transmitter 12-14 and receiver 15-17. In addition, this embodiment involves higher costs due to the additional microphones 15-17.

The in the illustration in FIG 8 The embodiment shown avoids such additional costs by as in the embodiment according to FIG. 1 there are only three transducers 12-14 that can be operated as transmitters and receivers, in such a way that the transducers 12-14 included in the smoke detector 10 function alternately as transmitters and receivers. With three transducers 12-14, for example, transducer 12 functions as a transmitter, while the other two transducers 13, 14 function as receivers.

In the representation in FIG 8 If the signal 28 emitted by the transducer 12 hits an object 20 located in the beam path, it is reflected there and a resulting reflected signal 29 reaches the transducer 13. Another signal 29 ′ reflected on the object 20 reaches the transducer 14.

In order to better illustrate the function, it is assumed that a further object 21 is present in the vicinity of the smoke detector 10. A signal 30 emitted by the converter 13 reaches this further object 21, is reflected and a resulting reflected signal 31 reaches the converter 14. A further reflected signal 31 'reaches the converter 12.

The converter 14 also sends out a signal 32, but this does not hit an object, so that no reflected signals are produced.

At the in FIG 8 It should be noted that the arrangement shown may require an opening angle of the transducers 12-14 of ± 60 ° and more. With a smoke detector 10 with reflective surfaces 40 according to FIG 6 can achieve the desired opening angle. However, it should also be noted that punctiform objects 20 are not disturbing. Objects 20 must reach a certain extent, so that the detection properties can also be sufficient if the opening angle is less than ± 60 °. However, the requirements placed on the converters 12-14 can also be reduced by using more than just three converters 12-14, that is to say for example four or five converters placed at an even distance, but with the disadvantage of higher costs.

The representation in FIG. 9 shows the in FIG 8 Illustrated operation of the smoke detector 10 for the three in FIG 8 illustrated transducers 12-14. On the one hand, it is shown when which converter 12-14 functions as a transmitter: First (upper third of the illustration), the first converter 12 functions as a transmitter. Thereafter (middle third of the illustration), the second converter 13 functions as a transmitter. Finally (lower third of the illustration), the third converter 14 functions as a transmitter. On the other hand, it is shown when which converter 12-14 functions as a receiver: if the first converter 12 functions as a transmitter, the second converter 13 and the third converter 14 function as a receiver; when the second transducer 13 functions as a transmitter, the first transducer 12 and the third transducer 14 function as a receiver; when the third transducer 14 functions as a transmitter, the first transducer 12 and the second transducer 13 function as a receiver. This applies correspondingly to more than three converters 12-14, for example four converters, five converters, etc. In the case of a larger number of transducers 12-14 (for example from four transducers 12-14 comprised by the smoke detector 10), it can also be provided that several transducers 12-14 act as transmitters and several other transducers 12-14 simultaneously act as receivers.

The illustration shows in detail in FIG. 9 that the converter 12 generates and transmits the signal 28, which is reflected by the object 20 and reaches the converter 13 as signal 29 and the converter 14 as signal 29 '. The converter 13 then generates the signal 30, which is reflected by the object 21 and which reaches the converter 14 as signal 31 and the converter 12 as signal 31 '. Finally, the converter 14 also sends out a signal 32, which, however, does not result in any reflected signals due to the lack of an object. In most cases, the interfering object 20, 21 will be in an asymmetrical position with respect to the smoke detector 10, so that the transit times of the signals 29, 29 'and the transit times of the signals 31, 31' can be different.

In comparison with the arrangement according to FIG. 1 does not apply in the arrangement according to FIG 8 the need to switch converters 12-14 from transmit mode to receive mode in a short time, so that objects 20, 21 can also be detected at a comparatively short distance from smoke detector 10.

Although in the FIG. 9 three measurements have to be carried out, the time required is still in the range of milliseconds. This is short compared to the duration of consecutive measurements FIG 2 . In addition, there is no disadvantage due to the longer time required, because with cyclical measurements (for example every ten minutes, every hour, every x hours, once a day) the duration of a measurement is at least short compared to such a cycle time.

The representation in FIG 10 finally shows a smoke detector 10 which avoids many of the previously not yet optimal properties.

The smoke detector 10 comprises two transducers 12, 13, which act as transmitters are operated, as well as two transducers 15, 16, which have the properties of microphones and function accordingly as receivers. The transmitters 12, 13 and microphones 15, 16 are arranged alternately and essentially evenly spaced along the circumference of the smoke detector 10. Compared to other arrangements that only require three transducers, the arrangement according to FIG 10 four transducers 12, 13, 15, 16 or possibly more, but an even number of transducers 12, 13, 15, 16. However, because microphones 15, 16 are generally significantly cheaper than transmitters 12, 13, the costs of the arrangement have to be reduced FIG 10 not necessarily higher than the cost of the arrangement FIG. 1 or FIG 8 lie.

The first transmitter 12 in turn transmits a signal 28 which is reflected by an interfering object 20. The reflected signals 29 and 29 'reach the two microphones 15, 16. The second transmitter 13 also sends out a signal 30. Because there is no disturbing object in the area of the transmitter 13, no reflected signals are produced.

It should be noted that the required opening angle of the transmitter and receiver is arranged in an order FIG 10 only has to be ± 90 ° and can be even smaller in practice.

It is not necessary to show the chronological sequence of the monitoring, since it is basically similar to that in FIG. 9 shown runs. Reference is therefore made here to this representation and the associated explanations.

The representation in FIG 11 shows a schematically simplified vertical section through a smoke detector 10, which for monitoring according to FIG 10 is set up without a housing surrounding the smoke detector 10. The smoke detector 10 is on a mounting surface 24 attached, for example a ceiling. The smoke detector 10 comprises a printed circuit board 11 and a plurality of transducers 12, 13, 15, 16, of which, in the selected sectional plane, the two transducers 12, 13 acting as transmitters lie in the image plane and the transducer 15 functioning as a receiver is visible while the second transducer 16 acting as a receiver is covered. All of the transducers 12, 13, 15, 16 comprised by the smoke detector 10 are aligned in the direction of the mounting surface 24 and, for this purpose, are mounted on the printed circuit board 11 at an angle of 45 ° or with reflecting surfaces 40 according to FIG 6 Mistake. The beam 28 of an ultrasound signal emitted by a transducer 12 initially runs from the transducer 12 to the mounting surface 24. There, the ultrasound signal is reflected and emitted into the surrounding space. The same applies accordingly when an ultrasound signal is received by a transducer 15, 16: an ultrasound signal reflected by an object 20 is reflected on the mounting surface 24 and from there reaches one or both of the transducers 15, 16 functioning as receivers.

The circuit board 11 of the smoke detector 10 is contacted with conductive parts 42 which engage in a base, not shown here. In a measuring chamber 34 of the smoke detector 10 there are optoelectric components 36 in a manner known per se. The measuring chamber 34 is mounted at a certain distance from the printed circuit board 11, which is sufficient for smoke 38 between the printed circuit board 11 and the measuring chamber 34 and then through an insect screen 39 can enter the so-called scattering volume inside the measuring chamber 34.

Objects 20, 21 ( FIG 1, 3 , 6, 7 , 8th and 10th ) in the vicinity of the smoke detector 10 are on the one hand by means of the transducers 12-14 already described as transmitters and on the other hand monitored by means of the converters 12-14 operated as receivers or also by means of special receivers 15-17. The at the in FIG 6 and FIG 10 In the embodiment shown, only transducers 12-14 functioning as transmitters emit ultrasound signals (rays 28, 30, 32) to detect any objects 20, 21 in the vicinity of the smoke detector 10. Radiation reflected from an object 20, 21 is detected by means of the transducers 12-14 operated as a receiver or by means of the transducers 15-17 operated only as a receiver (microphone). In the beam path 28, 29, 30, 31, 32 from and to the transducers 12-14; 15-17 can in principle be optional (see FIG 6 ) Reflecting surfaces 40 are located. To get an overview of the representation in FIG 11 possible beam paths to the receivers are not shown. Likewise, not every possible beam path is shown in the other figures.

So-called electret microphones come into consideration as receivers 15-17, but also microphones in silicon technology, which are considerably smaller than piezo transducers, but also any other embodiment of a microphone which is suitable for receiving signals in the selected frequency range, that is to say preferably ultrasound.

The ultrasound emitted by means of the transducers 12-14 functioning as a transmitter will travel from the transmitter 12-14 via reflections on the ceiling, wall or the like into or into one of the transducers 12-14 operated as a receiver or into transducers 15 operated only as a receiver Find -17. If the smoke detector 10 is covered or shadowed by an object 20, the received signal changes so that an alarm can be triggered. For this, after mounting the smoke detector 10, a normal level and a threshold value coding the normal level must be used be held. If, during later operation of the smoke detector 10, there is a deviation of the received signal level from this normal level, this indicates that the smoke detector 10 is covered or shaded by at least one object 20 which was not previously present in the vicinity of the smoke detector 10.

The representation in FIG 12 FIG. 10 shows another embodiment of a smoke detector 10 with a monitoring circuit that is in most details of that of FIG FIG 11 corresponds to the embodiment shown, but which contains a receiver 15 or possibly also a plurality of receivers 15, 16 which is or are oriented in a direction facing away from the mounting surface 24, typically towards the floor. While the commonly used ultrasound transducers, which can be operated as transmitters, are relatively large and have to be large in order to achieve an acceptable level of efficiency, microphones in the ultrasound range, in particular microphones that are produced on the basis of semiconductor technology, can be so small, that they can be arranged inconspicuously under the hood of the smoke detector 10.

The representation in FIG. 13 finally and schematically greatly simplifies the function of a smoke detector 10 of the type described here. The smoke detector 10 comprises a sensor system 50, for example a sensor system 50 in the form of a plurality of transducers 12-14 functioning as transmitter and receiver, or a plurality of alternately as transmitters or receivers functioning transducers 12-14 or a plurality of transmitters 12-14 and a plurality of receivers 15-17 separate therefrom. The sensor 50 emits radiation in the ultrasound range (ultrasound radiation). This is illustrated in the form of the wave front emanating from the smoke detector 10. From an object 20 located in the vicinity of the smoke detector 10 the emitted radiation reflects. This is illustrated in the form of the wavefront emanating from the object 20. The reflected radiation is detected by means of the sensor system 50 and a measure for a respective signal strength is compared by means of a comparator 52 with a predetermined or predeterminable threshold value. In the event of a deviation from the threshold value, in particular if the threshold value is exceeded, an actuator 54, which is comprised, for example, by the smoke detector 10 or an actuator 54 which can be controlled by the smoke detector 10, is triggered to emit an alarm signal.

The actuator 54 can be a loudspeaker which is provided anyway for emitting an alarm tone in the event of smoke or fire. Different signal patterns, different frequencies and / or different volumes can be provided for the respective alarm tone in order to distinguish between an alarm tone emitted in the vicinity of the smoke detector 10 in the case of a detected object 20 and an alarm tone emitted in the event of smoke or fire. Likewise, however, a corresponding message can be sent in a suitable manner to a remote location, for example to a service point, so that there is a guarantee that the cause of the alarm will be removed in a useful period and appropriately.

Although the invention has been illustrated and described in more detail by means of the exemplary embodiment, the invention is not restricted by the disclosed example or examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

Individual aspects of the description submitted here that are in the foreground can thus be briefly summarized as follows: a smoke detector 10 or generally a Monitoring device and a method for monitoring a smoke detector 10 or a monitoring device. The smoke detector 10 comprises a sensor system 50 for recognizing an adjacent object 20. Signals, in particular ultrasound signals, can be emitted and received by means of the sensor system 50. Received signals can be evaluated to identify an adjacent object 20. As the sensor system 50, the smoke detector 10 comprises a plurality of transmitters and either a plurality of transducers operated as receivers or a plurality of receivers, the function of the transmitters being separated from the function of the receivers by transformers which can be operated both as transmitters and receivers 12, 13, 14 are used and toggled between transmission mode and reception mode, or by using separate transmitters 12, 13, 14 and receivers 15, 16, 17, the transmitters 12-14 being oriented in such a way that they operate in the direction radiate onto a mounting surface 24 on which the smoke detector 10 is attached.

Claims (11)

1. Smoke detector (10) having a sensor system (50) for identifying an adjacent object (20), wherein signals can be transmitted and received by means of the sensor system (50), wherein a received signal for identifying an object (20) can be evaluated, wherein the sensor system (50) comprises a plurality of transmitters (12-14), wherein the smoke detector (10) is attached to a mounting surface (24), and wherein the transmitters (12-14) are aligned such that in operation they beam onto the mounting surface (24) in an oblique direction away from the smoke detector (10).
2. Smoke detector (10) according to claim 1, having at least one reflection surface (40) in the beam path (28) from the transmitter (12-14) to the mounting surface (24).
3. Smoke detector (10) according to claim 1 or 2, wherein the respective transmitter (12-14) is arranged in the smoke detector (10) such that a lobe of the respective transmitted signal (28) strikes the mounting surface (24) at an angle in the range between 30° and 60°, in particular in a range between 40° and 50°.
4. Smoke detector (10) according to one of the preceding claims, wherein each transmitter (12-14) is intended and designed to emit an ultrasound signal in an emission direction.
5. Smoke detector (10) according to one of the preceding claims, wherein transducers (12-14) comprised by the smoke detector (10) as a sensor system (50) function alternately as transmitters or receivers.
6. Smoke detector system having a smoke detector (10) according to one of the preceding claims and having a detector base (25) for in particular detachable attachment of the smoke detector (10) to the detector base (25), wherein the detector base (25) is provided for attachment to a ceiling or wall, and wherein the detector base (25) is embodied such that, when the smoke detector (10) is in the mounted state, it replaces the mounting surface (24) onto which the transmitters (12-14) beam in an oblique direction away from the smoke detector (10).
7. Method for operating a smoke detector (10) according to one of the preceding claims, wherein signals are emitted in the oblique direction away from the smoke detector (10) onto the mounting surface (24) by means of the sensor system (50) during operation of the smoke detector (10), are reflected off the mounting surface (24), and in the case of an object (20) located close to the smoke detector (10) the emitted signals are reflected by the object (20) and the reflected radiation is detected by means of the sensor system (50) of the smoke detector (10).
8. Method according to claim 7 for operating a smoke detector (10) according to claim 5, wherein transducers (12-14) comprised by the smoke detector (10) as a sensor system (50) function alternately as transmitters or receivers.
9. Method according to claim 7 or 8, wherein the signals emitted by means of the sensor system (50) are output at predetermined or predeterminable, in particular equidistant, points in time.
10. Method according to one of claims 7 to 9, wherein in the case of an object (20) identified due to reflected radiation an alarm signal is output.
11. Method according to claim 9 and claim 10, wherein the alarm signal is only output if the object (20) has been detected several times.

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