Device for detecting passage of infrared radiation emitters in monitoring area and associated method

Abstract

The present disclosure relates to a device and a related method for detecting passage of infrared (IR) radiation emitters in a monitoring area. The device has a first surface and a second surface inclined to each other and configured to face the monitoring area. The device includes a first IR radiation sensor extending on a first surface and a second IR radiation sensor extending on a second surface. The first IR radiation sensor is configured to detect IR radiation of the emitter when the emitter is in a first field of view of the first IR radiation sensor, and the second IR radiation sensor is configured to detect IR radiation of the emitter when the emitter is in a second field of view of the second IR radiation sensor. The first field of view and the second field of view are configured to partially overlap each other at the monitoring zone.

Description

Technical Field

[0001] The present disclosure relates to an apparatus for detecting the passage of an infrared radiation emitter in a surveillance zone and an associated method for detecting the passage of an emitter in a surveillance zone. Background Art

[0002] As is known, the need is often felt to detect the passage of people in certain areas. For example, it may be necessary to detect the passage of people through doors leading to rooms in order to monitor the number of people present in a room (e.g. for security reasons in places such as operating theatres and stadiums, or for organisational and control reasons in places such as public transport and conference rooms). This is useful for applications such as automatic control in lighting or heating rooms (i.e. automatically switching lights / heating devices / air conditioning in a room on and off depending on the number of people that may be present therein) and monitoring the number of people in an enclosed environment or multiple enclosed environments (e.g. operating theatres and stadiums) that have specific security requirements related to the maximum number of people they can accommodate.

[0003] To achieve this, it is usually necessary to be able to monitor the direction of passage of a person passing through the surveillance zone, and thus not only monitor his / her passage in the surveillance zone, in order to be able to determine, for example, whether a person is entering or leaving a room.

[0004] Some solutions are known which allow the passage of persons in a surveillance zone to be detected.

[0005] Most of these solutions are based on optical technology and, in particular, use optical radiation transmitters and receivers placed at mutually opposite ends of the surveillance zone in such a way that the passage of a person through the surveillance zone causes the interruption of a light beam (for example of the infrared IR type) emitted by the transmitter and received by the receiver in the absence of a person. This interruption of the light beam thus indicates the passage of a person in the surveillance zone. However, known solutions of this type have several disadvantages: it requires a large amount of circuitry for controlling both the transmitter and the receiver, it is not capable of selectively identifying human bodies (i.e. even non-transmitters such as inanimate objects placed in the surveillance zone may interrupt the light beam and generate false alarms), it is very expensive and requires accurate mounting and calibration of the transmitter and receiver in order to operate.

[0006] Furthermore, the known solutions are usually not able to detect the direction of passage of a person, but only his / her passage in the surveillance zone, so they do not allow a high measurement accuracy of the number of people in the monitored environment.

[0007] Various embodiments of the present disclosure provide apparatus for detecting the passage of infrared radiation emitters in a surveillance zone and related methods for detecting the passage of emitters in a surveillance zone that overcome the shortcomings of the prior art. Summary of the invention

[0008] According to the present disclosure, there is provided an apparatus for detecting the passage of an infrared radiation emitter in a surveillance zone and an associated method for detecting the passage of an emitter in a surveillance zone.

[0009] The device has a first surface and a second surface that are inclined to each other and configured to face a surveillance area. The device includes a first IR radiation sensor extending on the first surface and a second IR radiation sensor extending on the second surface. The first IR radiation sensor is configured to detect IR radiation of an emitter when the emitter is located in a first field of view of the first IR radiation sensor, and the second IR radiation sensor is configured to detect IR radiation of the emitter when the emitter is located in a second field of view of the second IR radiation sensor. The first field of view and the second field of view are configured to partially overlap each other at the surveillance area. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a better understanding of the present disclosure, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0011] Figure 1 shows a schematic top view of two environments connected by a passage with a surveillance zone in which there is a device for detecting the passage of infrared radiation emitters according to an embodiment;

[0012] Figure 2 The embodiment according to the embodiment is shown in detail Figure 1 equipment;

[0013] Figure 3 and Figure 4 is a diagram showing the Figure 2 a graph of an electrical signal generated by an infrared radiation sensor included in a device; and

[0014] Figure 5 is a block diagram schematically illustrating a method for detecting passage of an infrared radiation emitter in a surveillance area according to an embodiment.

[0015] In particular, the figures are shown with reference to a three-axis Cartesian system defined by an axis X, an axis Y and an axis Z that are orthogonal to one another.

[0016] In the following description, elements common to different embodiments are indicated by the same reference numerals. DETAILED DESCRIPTION

[0017] Figure 1 A device (or sensor device) 10 for detecting the passage of a person 12 in a surveillance zone 14 is shown.

[0018] In detail, the surveillance zone 14 is a passage area connecting the first environment 18 and the second environment 19 , through which the person 12 must pass in order to pass from the first environment 18 to the second environment 19 , and vice versa.

[0019] In more detail and for reasons better discussed below, the first environment 18 and the second environment 19 are considered to be in communication with each other via the surveillance zone 14, i.e., passage between the first environment 18 and the second environment 19 occurs via the surveillance zone 14, such that anyone who wants to pass from one of the two environments 18, 19 to the other can do so by passing through the surveillance zone 14. However, this may not necessarily be the case in other embodiments.

[0020] exist Figure 1 In the exemplary embodiment shown in , the surveillance zone 14 is a portion of a corridor 16 (or it is a door) that connects a second environment 19 (here, a room in a building) to a first environment 18 (here, an external environment (or a different room in a building)). In other words, for a person 12 located in the external environment 18, only passing through the surveillance zone 14 can enter the room 19.

[0021] Figure 2 The device 10 is shown in more detail, in particular in a plane XY defined by axes X and Y.

[0022] The device 10 includes a body or substrate 20 having a first surface 20a and a second surface 20b facing the monitoring area 14 and inclined relative to each other. Figure 2 As shown in FIG. 1 , the first surface 20 a and the second surface 20 b are directly connected to each other and form a continuous surface.

[0023] In detail, the first surface 20 a and the second surface 20 b are outer surfaces of the body 20 , and are adjacent to each other (ie, share a portion of outer edges thereof), for example.

[0024] The first surface 20a and the second surface 20b are fixed at a predetermined angular position with respect to each other.

[0025] In detail, the first surface 20a and the second surface 20b have a first tilt angle α therebetween. For example, the first tilt angle α between the first surface 20a and the second surface 20b is measured in plane XY inside the device 10 (e.g., extending through the body 20). In other words, the first tilt angle α is the smaller angle of the two complementary angles formed by the intersection of the first surface 20a and the second surface 20b.

[0026] In particular, in a design step, a first tilt angle α is determined based on parameters better described below.

[0027] According to an exemplary embodiment, the first inclination angle α is between about 110° and about 170°.

[0028] The device 10 also includes a first infrared IR radiation sensor 22a and a second IR radiation sensor 22b.

[0029] The first IR radiation sensor and the second IR radiation sensor are infrared radiation sensors, in particular MEMS type devices.Therefore, the first IR radiation sensor and the second IR radiation sensor are made by various microfabrication techniques for processing semiconductor materials, such as for example silicon.

[0030] The first IR radiation sensor 22a and the second IR radiation sensor 22b are carried by the body 20 and extend on the first surface 20a and the second surface 20b, respectively, in such a manner as to be also inclined to each other at a first inclination angle α.

[0031] In more detail, the first IR radiation sensor 22a and the second IR radiation sensor 22b have a first field of view (FoV) 24a and a second field of view 24b, respectively. When the person 12 is located in one of these fields of view 24a, 24b, the corresponding IR radiation sensor 22a, 22b is capable of detecting the IR radiation emitted by the person 12, and thus is capable of detecting the presence of the person 12 in the corresponding field of view 24a, 24b.

[0032] Each field of view 24a, 24b has substantially axial symmetry with respect to a respective detection direction 26a, 26b of the first IR radiation sensor 22a and the second IR radiation sensor 22b. These detection directions 26a, 26b are substantially orthogonal to the first surface 20a and the second surface 20b, respectively, and define between them a second tilt angle β complementary to the first tilt angle α.

[0033] In particular, here, the field of view means a volume, i.e. a part of the three-dimensional space, in which the person 12 can stand so that the IR radiation emitted thereby is detected by the corresponding IR radiation sensor. In particular, the field of view has a substantially conical shape defined by an opening angle θ measured along the corresponding detection direction and a field length, which are defined in the design step of the IR radiation sensor (for example, they depend on the presence or absence of a directional lens, its optical and physical parameters and the detector used, etc.). In general, as the opening angle θ increases, the field length decreases, and vice versa.

[0034] For example, the fields of view 24a, 24b are substantially equal to each other, ie, the respective opening angles θ and the respective field lengths are substantially equal to each other.

[0035] According to one embodiment, the opening angle θ of the fields of view 24a, 24b is between about 40° and about 110°. In addition, the field of view length of the fields of view 24a, 24b may be between about 50 cm and about 4 m.

[0036] like Figure 2 As shown in FIG. 1 , the fields of view 24a, 24b of the IR radiation sensors 22a, 22b partially overlap each other, ie they have a mutual overlapping area (or volume) 28 common to the two fields of view 24a, 24b. In detail, the fields of view 24a, 24b partially overlap each other.

[0037] According to an exemplary embodiment, the mutual overlapping area 28 is approximately 80% smaller than each of the first and second fields of view and, in particular, equal to approximately 20% of the first and second fields of view (here considered with substantially the same extension).

[0038] In particular, during the design step of the device 10, the first inclination angle α between the first surface 20a and the second surface 20b and the parameters of the fields of view 24a, 24b (i.e., the opening angle θ and the field of view length) are selected so as to ensure partial overlap of the fields of view 24a, 24b, in particular a relatively small value of the previously described mutual overlap area 28.

[0039] Furthermore, a mutually overlapping region 28 of the fields of view 24 a , 24 b extends at the monitoring zone 14 .

[0040] In detail, the fields of view 24a, 24b (and in particular the mutually overlapping region 28) extend at the surveillance zone 14, for example such that the entire or nearly the entire surveillance zone 14 is covered.

[0041] In general, the apparatus 10 is designed and arranged so that when a person 12 passes through the surveillance zone 14, the person 12 passes through the fields of view 24a, 24b of the IR radiation sensors 22a, 22b that are successive to one another.

[0042] In other words, when a person 12 passes through the surveillance zone 14, he / she substantially follows the direction of travel 30, which passes through the surveillance zone 14 and Figure 2 In the exemplary embodiment of , this passage direction is shown parallel to the axis X. The device 10 is oriented so that the passage direction 30 passes through both fields of view 24a, 24b, in particular also in the parts of the fields of view 24a, 24b that do not overlap each other, i.e. they are staggered transversely to each other, i.e. along the passage direction 30.

[0043] Since the fields of view 24a, 24b of the IR radiation sensors 22a, 22b extend transversely to each other and continuously in the passage direction 30, the passage of a person 12 through the surveillance zone 14 in the passage direction 30 is detected by two IR radiation sensors 22a, 22b consecutive to each other.

[0044] In particular, the device 10 and its arrangement relative to the surveillance zone 14 are designed and formed such that the surveillance zone 14 is completely covered by the fields of view 24a, 24b in a direction orthogonal to the direction of passage 30. In other words, each of the fields of view 24a, 24b is superimposed on the surveillance zone 14 along the entire extension of the surveillance zone 14 orthogonal to the direction of passage 30. In this way, a person 12 crossing the surveillance zone 14 parallel to the direction of passage 30 must have passed through both fields of view 24a, 24b.

[0045] For example, if a person 12 passes from a first environment 18 to a second environment 19 and thus Figure 2 In the example of , if the person 12 moves from left to right along the passage direction 30, the IR radiation emitted by the person 12 is detected by the first IR radiation sensor 22a (not by the second IR radiation sensor 22b) in the first time period and by the second IR radiation sensor 22b (not by the first IR radiation sensor 22a) in the second time period. In the intermediate time period between the first time period and the second time period, the IR radiation emitted by the person 12 can also be detected by both IR radiation sensors 22a and 22b at the same time (because the person 12 is located in the mutually overlapping area 28), however, in any case, information related to the passage can be obtained based on the IR radiation detected in the first time period and the second time period.

[0046] As better described below, this allows determining when passage of a person 12 through surveillance zone 14 occurs and the direction of that passage (ie, whether from first environment 18 towards second environment 19 or vice versa).

[0047] In more detail, the first IR radiation sensor 22 a and the second IR radiation sensor 22 b are based on “Thermal MOS” TMOS (Thermal Metal Oxide Semiconductor) technology, ie they each comprise a respective TMOS acting as a detector of the IR radiation emitted by the person 12 .

[0048] In particular, a TMOS is a field effect transistor device and is typically used in sensor applications to determine the amount of radiation (in detail, IR radiation) emitted by an emitting object (here, a person 12). An emitter is any thermal body that emits IR radiation, such as a person or an animal. The radiation emitted by the emitter and received by the TMOS causes charge carriers to be generated at the conductive channel of the TMOS, thus causing a corresponding change in the output current of the TMOS; the latter can be related to the degree of radiation emitted by the inspected object, so as to have a measure of the radiation emitted by the emitter. In detail, the detection of IR radiation by the TMOS occurs when the emitter is located in the field of view of the TMOS.

[0049] In general, a TMOS allows the detection of the presence or absence of an emitter in its field of view.

[0050] According to the embodiment exemplarily considered below, the TMOS present in the device is an infrared temperature sensor TMOS sold by STMicroelectronics with, for example, the reference code STHS34PF80 (further details can be found at the address https: / / www.st.com / en / mems-and-sensors / infrared-ir-sensors.html).

[0051] In particular, TMOS (eg, STHS34PF80 from STMicroelectronics) are each capable of generating at least one temperature signal and one motion signal, both of which are related to the presence or absence of an emitter in the field of view.

[0052] The temperature signal is a signal indicating the temperature of an entity (a living thing, such as a person, or an inanimate but hot object, such as a heating device) existing in the field of view of the TMOS.

[0053] Thus, the temperature signal is determined from both IR radiation emitted by emitters present in the field of view of the TMOS, and IR radiation that is normally present in the environment in which the TMOS is placed, even in the absence of living things. In other words, the temperature signal has a baseline that depends on the amount of ambient IR radiation measured by the TMOS in the absence of a person in the field of view (e.g., on the temperature of the air surrounding the TMOS, on electromagnetic noise due to the environment in which the TMOS is present, etc.), and may vary relative to that baseline when the TMOS detects IR radiation emitted by an emitter, which is added to the already present ambient IR radiation. Thus, a peak in the temperature signal of the TMOS relative to its baseline indicates the presence of a person in the field of view of the TMOS.

[0054] In the embodiment considered here in which the TMOS is the STHS34PF80 from STMicroelectronics, the temperature signal corresponds to the signal T indicated in the data sheet of the TMOS. object (or another T obj For this reason, hereinafter, reference symbol T object Indicates temperature signal.

[0055] In contrast, the motion signal is a signal indicating the change in temperature of the environment in which the TMOS exists over time, that is, a signal indicating the change in temperature of an entity (a living thing, such as a person, or a non-living thing but hot object, such as a heating appliance) existing in the field of view of the TMOS over time. In other words, the motion signal is a signal related to the change in temperature signal over time.

[0056] In particular, a motion signal is generated starting from a temperature signal. For example, the temperature signal is filtered using a first low-pass filter and a second low-pass filter (for example, considering the output data rate ODR of the TMOS, the first filter has a cutoff frequency equal to about ODR / 9, and the second filter has a cutoff frequency equal to about ODR / 20) to obtain a corresponding filtered temperature signal, and a motion signal that varies according to the difference (expressed in absolute value) of these filtered temperature signals.

[0057] Thus, the motion signal has a value of approximately zero when no emitters are passing through the field of view, and has a peak whenever a passage of an emitter in the field of view occurs. In other words, the motion signal is associated with transient events of the input and output of emitters in the field of view.

[0058] In the embodiment considered here in which the TMOS is the STHS34PF80 of STMicroelectronics, the motion signal corresponds to the signal T indicated in the data sheet of the TMOS. motion For this reason, hereinafter, reference symbol T motion Indicates motion signal.

[0059] For example, in this application, two TMOS can be operated with an ODR equal to about 8 Hz.

[0060] Reference again Figure 2 The device 10 also includes a control unit 32, for example housed in the body 20, which is coupled (in detail, electrically coupled) to the first IR radiation sensor 22a and the second IR radiation sensor 22b. The control unit 32 can be any type of circuit system (e.g., a processor, a controller, a signal processor, etc.) that processes data.

[0061] In use, the control unit 32 receives a first detection signal from the first IR radiation sensor 22a and a second detection signal from the second IR radiation sensor 22b. The first detection signal and the second detection signal may be corresponding temperature signals T object Or the corresponding motion signal T motion In both cases, the first detection signal and the second detection signal indicate the presence or absence of the person 12 in the first field of view 24a and the second field of view 24b, respectively.

[0062] Furthermore, the control unit 32 determines whether passage of the person 12 in the surveillance area 14 occurs based on the first detection signal and the second detection signal.

[0063] To do so, the control unit 32 verifies whether the first detection signal and the second detection signal have the first signal peak and the second signal peak, respectively, within the passage time interval, and if the first detection signal and the second detection signal have the first signal peak and the second signal peak within the passage time interval, the passage of the person 12 in the surveillance area 14 is confirmed. In detail, the passage time interval is measured from the first signal peak of the first signal peak and the second signal peak, that is, the passage time interval is measured from the peak (the first signal peak or the second signal peak) detected first.

[0064] The passage time interval is a predefined time interval whose duration is established in a design step in a manner that is self-evident based on factors such as the distance that person 12 travels to cross the field of view in surveillance zone 14, the average walking speed of person 12, etc. For exemplary purposes only, the passage time interval may be equal to about 5 seconds. For example, the passage time interval is measured from the rising edge of the detected first peak of a pair of peaks indicating the passage of person 12 in surveillance zone 14.

[0065] In particular, the detection of the first signal peak and the second signal peak occurs in different ways, depending on whether the control unit 32 processes the temperature signal T object Or process motion signal T motion to determine the passage of a person 12. This occurs due to the fact that the motion signal T motion has a zero baseline, and the temperature signal T object Typically have a non-zero baseline and generally have baselines that are different from each other.

[0066] Now, refer to Figure 3 The first detection signal and the second detection signal acquired by the control unit 32 are described as temperature signals T object situation.

[0067] In detail, Figure 3 The temperature signal T detected by the first IR radiation sensor 22a and the second IR radiation sensor 22b is shown. object Hereinafter, the temperature signal T detected by the first IR radiation sensor 22a is object Also known as the first temperature signal T object,1 , and the temperature signal T detected by the second IR radiation sensor 22b object Also known as the second temperature signal T object,2 .

[0068] exist Figure 3 In the example of FIG. 1 , the following cases are considered: a false pass (ie, a temperature signal T objectAn isolated peak of a temperature signal in the monitoring area 14, however, the peak does not indicate a real passage of the person 12 in the monitoring area 14), after which two passages of the person 12 in the monitoring area 14 occur successively to each other, a first passage associated with the person 12 passing from the first environment 18 to the second environment 19 and a second passage associated with the person 12 passing from the second environment 19 to the first environment 18.

[0069] In more detail, as time goes by, the first temperature signal T object,1 The first peak K has continuous peaks 1a , the second peak K 1b and the third peak K 1c , and the second temperature signal T object,2 The first peak K has continuous peaks 2a and the second peak K 2b .

[0070] The first temperature signal T object,1 The second peak K 1b and the second temperature signal T object,2 The first peak K 2a occurs when the travel time interval (here, also represented by Δt max Indication) Small first time interval Δt 1 , thus indicating the first passage of person 12 in surveillance zone 14; the second temperature signal T object,2 The second peak K 2b and the first temperature signal T object,1 The third peak K 1c Occurs at a time interval Δt max The second small time interval Δt 2 , thus indicating a second passage of person 12 in surveillance zone 14; and the first temperature signal T object,1 The first peak K 1a Relative to the second temperature signal T object,2 isolated over time (i.e., in the case of a first temperature signal T object,1 The first peak K 1b Start measuring the passage time interval Δt max The corresponding second temperature signal T object,2 The first temperature signal T defining the passage of person 12 in surveillance zone 14 is not present, so it does not indicate a complete passage of person 12 in surveillance zone 14 (for example, it may indicate the fact that the person entered first field of view 24a in surveillance zone 14, but then returned along the same path to leave surveillance zone 14 without also passing through second field of view 24b, and thus did not complete the passage through surveillance zone 14). object,1 and the second temperature signal T object,2The peak values ​​are also referred to as the first signal peak value and the second signal peak value, respectively.

[0071] In addition, the first temperature signal T object,1 The second peak K 1b In the second temperature signal T object,2 The first peak K 2a , and this indicates the passage of the person 12 first through the first field of view 24a and then through the second field of view 24b (thus indicating the passage of the person 12 from the first environment 18 to the second environment 19), while the second temperature signal T object,2 The second peak K 2b In the first temperature signal T object,1 The third peak K 1c , and this indicates the passage of the person 12 first through the second field of view 24b and then through the first field of view 24a (thus indicating the passage of the person 12 from the second environment 19 to the first environment 18).

[0072] In other words, the temperature signal T that defines the passage of the person 12 in the monitoring area 14 object The relative order of the peaks of indicates the direction of travel of the person 12 along the travel direction 30, i.e., this indicates whether the person 12 is traveling along a first travel direction or a second travel direction, the first travel direction and the second travel direction having axes that coincide with each other and with the travel direction 30 and having directions that are opposite to each other. For example, the first travel direction has an axis of the travel direction 30 and a direction from the first environment 18 to the second environment 19 (i.e., in Figure 2 from left to right in the direction coinciding with the axis X), and the second passage direction has an axis of the passage direction 30 and a direction from the second environment 19 to the first environment 18 (i.e., in Figure 2 from right to left in a direction not consistent with axis X).

[0073] In a manner known per se, such as described in document US20220366768, peak values ​​are identified starting from the detection signal (identifying them as temperature signals T object Or motion signal T motion ).

[0074] In detail, the detection signal is a temperature signal T object of Figure 3 In the case where the first temperature signal T object,1 and the second temperature signal T object,2 In the travel time interval Δt max There are two consecutive temperature signals: object,1 The rising edge of K 1b ', the second temperature signal T object,2 The rising edge of K 2a', the first temperature signal T object,1 The falling edge of K 1b ″ and the second temperature signal T object,2 The falling edge of K 2a "; or the second temperature signal T object,2 The rising edge of K 2b ', the first temperature signal T object,1 The rising edge of K 1c ', the second temperature signal T object,2 The falling edge of K 2b ″ and the first temperature signal T object,1 The falling edge of K 1c ″, the control unit 32 determines the first temperature signal T object,1 and the second temperature signal T object,2 indicates the passage in the surveillance area 14 (ie, they are within the passage time interval Δt max For example, an interval of the detection signal that seamlessly increases / decreases for a sufficient number of instants consecutive to each other (e.g., for N consecutive samples, where N is exemplarily equal to about 30) is considered a rising / falling edge.

[0075] The first case corresponds to the time interval Δt max The first temperature signal T is detected object,1 The second peak K 1b and the second temperature signal T object,2 The first peak K 2a , which therefore indicates the passage of the person 12 along the first passage direction (ie from the first environment 18 to the second environment 19), while the second case corresponds to the passage time interval Δt max The second temperature signal T is detected object,2 The second peak K 2b and the first temperature signal T object,1 The third peak K 1c , which therefore indicates a passage of the person 12 along the second passage direction, ie from the second environment 19 to the first environment 18 .

[0076] On the contrary, in the first temperature signal T object,1 The first peak K 1a In the case of a travel time interval Δt max In the second temperature signal T object,2 No corresponding peak is detected in (i.e., no confirmation of temperature signal T object ), so the control unit 32 does not confirm the detection of passage in the monitoring area 14.

[0077] On the other hand, now, refer to Figure 4 The first detection signal and the second detection signal acquired by the control unit 32 are described as motion signals T motion situation.

[0078] In detail, Figure 4 The motion signal T detected by the first IR radiation sensor 22a and the second IR radiation sensor 22b is shown. motion Hereinafter, the temperature signal T detected by the first IR radiation sensor 22a is motion Also known as the first temperature signal T motion,1 , and the motion signal T detected by the second IR radiation sensor 22b motion Also known as the second motion signal T motion,2 .

[0079] exist Figure 4 In the example of , the following situation is exemplarily considered: a person 12 makes two consecutive passes in the monitoring area 14, a first pass associated with the person 12 passing from the first environment 18 to the second environment 19 and a second pass associated with the person 12 passing from the second environment 19 to the first environment 18.

[0080] In more detail, as time goes by, the first motion signal T motion,1 The first peaks M have continuous 1a and the second peak M 1b , and the second motion signal T motion,2 The first peaks M have continuous 2a and the second peak M 2b .

[0081] The first motion signal T motion,1 The first peak M 1a and the second motion signal T motion,2 The first peak M 2a Occurs at a time interval Δt max Small first time interval Δt 1 , thus indicating the first passage of person 12 in surveillance zone 14; the second motion signal T motion,2 The second peak M 2b and the first motion signal T motion,1 The second peak M 1b Occurs at a time interval Δt max The second small time interval Δt 2 , thus indicating a second passage of the person 12 in the surveillance zone 14. The first motion signal T defining the passage of the person 12 in the surveillance zone 14 motion,1 and the second motion signal T motion,2 The peak values ​​are also referred to as the first signal peak value and the second signal peak value, respectively.

[0082] In addition, the first motion signal T motion,1 The first peak M 1a In the second motion signal T motion,2 The first peak M 2a , and this indicates the passage of the person 12 first through the first field of view 24a and then through the second field of view 24b (thus indicating the passage of the person 12 from the first environment 18 to the second environment 19), while the second motion signal T motion,2 The second peak M 2b In the first motion signal T motion,1 The second peak M 1b , and this indicates the passage of the person 12 first through the second field of view 24b and then through the first field of view 24a (thus indicating the passage of the person 12 from the second environment 19 to the first environment 18). In other words, and similarly to what has been described previously, the motion signal T defining the passage of the person 12 in the surveillance zone 14 motion The relative order of the peaks of φ indicates the direction of travel of the person 12 along the travel direction 30 , ie this indicates whether the person 12 is travelling along the first travel direction or along the second travel direction.

[0083] In detail, the detection signal is a motion signal T motion of Figure 4 In the case of motion,1 and the second motion signal motion,2 In the travel time interval Δt max are continuous with each other, they indicate passage in the surveillance area 14 (ie, they are separated by a passage time interval Δt max The first motion signal T has a first signal peak value and a second signal peak value respectively. motion,1 From the ratio switching threshold T m,th The lower value becomes lower than the switching threshold T m,th High value, the second motion signal T motion,2 From the ratio switching threshold T m,th The lower value becomes lower than the switching threshold T m,th High value, the first motion signal T motion,1 From the ratio switching threshold T m,th The higher value becomes higher than the switching threshold T m,th low value, and the second motion signal T motion,2 From the ratio switching threshold T m,th The higher value becomes higher than the switching threshold T m,th A low value; or a second motion signal T motion,2 From the ratio switching threshold T m,th The lower value becomes lower than the switching threshold T m,th High value, the first motion signal Tmotion,1 From the ratio switching threshold T m,th The lower value becomes lower than the switching threshold T m,th High value, the second motion signal T motion,2 From the ratio switching threshold T m,th The higher value becomes higher than the switching threshold T m,th low value, and the first motion signal T motion,1 From the ratio switching threshold T m,th The higher value becomes higher than the switching threshold T m,th Low value.

[0084] The first case corresponds to the time interval Δt max The first motion signal T is detected motion,1 The first peak M 1a and the second motion signal T motion,2 The first peak M 2a , which therefore indicates the passage of the person 12 along the first passage direction (ie from the first environment 18 to the second environment 19), while the second case corresponds to the passage time interval Δt max The second motion signal T is detected motion,2 The second peak M 2b and the first motion signal T motion,1 The second peak M 1b , which therefore indicates a passage of the person 12 along the second passage direction, ie from the second environment 19 to the first environment 18 .

[0085] Switching threshold T m,th The value of is chosen in a design step in a manner which is obvious per se, for example heuristically, depending on different factors such as the noise of the motion signal baseline, the distance travelled by the person 12 from the IR radiation sensors 22a and 22b, etc. Merely by way of example, the switching threshold T m,th Can be equal to about 300LSB.

[0086] In a completely similar manner, based on the switching threshold T m,th The previous comparison of can be performed with hysteresis to increase the reliability of determining the passage of person 12 in surveillance zone 14 and to make the measurement more robust. In this case, the first motion signal T motion,1 and the second motion signal T motion,2 From below the switching threshold T m,th The value is higher than the switching threshold T m,th The value of the passing condition depends on the first switching sub-threshold (with the switching threshold T m,th Related, for example, equal to T m,th +ΔT m , where ΔT m Example is equal to the switching threshold Tm,th , thus equal to about 30LSB) occurs, and the first motion signal T motion,1 and the second motion signal T motion,2 From above the switching threshold T m,th The value is lower than the switching threshold T m,th The value of the passage condition depends on the second switching sub-threshold (lower than the first switching sub-threshold and equal to the switching threshold T m,th Related and equal to T m,th -ΔT m )occur.

[0087] Thus, device 10 can implement a method for detecting passage of person 12 in surveillance zone 14 during use.

[0088] Now, refer to Figure 5 The method is discussed exemplarily, wherein the method is indicated by reference numeral 50 .

[0089] At step S10 of method 50, when person 12 is located in first field of view 24a, first IR radiation sensor 22a detects his / her IR radiation, and when person 12 is located in second field of view 24b, second IR radiation sensor 22b detects his / her IR radiation.

[0090] At step S12 following step S10, the control unit 32 receives a first detection signal from the first IR radiation sensor 22a and a second detection signal from the second IR radiation sensor 22b, wherein the first detection signal indicates the presence or absence of the person 12 in the first field of view 24a, and the second detection signal indicates the presence or absence of the person 12 in the second field of view 24b, and the detection signals are generated based on the IR radiation detected by the first IR radiation sensor 22a and the second IR radiation sensor 22b, respectively.

[0091] At step S14 following step S12, the control unit 32 determines whether a passage of a person 2 in the surveillance zone 14 has occurred based on the first detection signal and the second detection signal. This occurs as previously described, i.e., by verifying whether the first detection signal and the second detection signal are within a passage time interval Δt max There are first signal peaks and second signal peaks within the range, and if this condition is verified, then the passage is confirmed. In more detail, this can be described in the previous reference Figure 3 and Figure 4 The two modes described occur.

[0092] Furthermore, if passage of person 12 in surveillance zone 14 has been detected, at step S16 following step S14, control unit 32 may verify based on the first and second detection signals whether the passage occurs along the first or second passage direction, as previously described.

[0093] From an examination of the features of embodiments made in accordance with the present disclosure, the advantages they offer are apparent.

[0094] The device 10 allows the passage of a person 12 in a surveillance zone 14 to be detected efficiently with high accuracy (due to its ability to exclude false alarms as previously described) and with low energy consumption (for example, of the order of about 40 μA).

[0095] In fact, since the IR radiation sensors 22a and 22b are based on TMOS technology and therefore on passive sensors (ie they detect IR radiation emitted by hot bodies without emitting IR radiation themselves, for example according to the time-of-flight mode), they have a very low energy consumption.

[0096] Furthermore, the device 10 can be mounted in a simpler manner (eg with precise alignment between the IR radiation emitter and the receiver) relative to known solutions.

[0097] Furthermore, the use of two IR radiation sensors 22a, 22b tilted to each other allows not only detecting the passage of a person 12 in the surveillance zone 14, but also the direction in which he / she is walking (ie if he / she is travelling in the first passage direction or in the second passage direction).

[0098] In particular, using the first tilt angle α allows obtaining a partial superposition of the fields of view 24a and 24b by limiting the relative distance between the IR radiation sensors 22a and 22b (and thus achieving this objective). This allows the overall size of the device 10 to be reduced.

[0099] Thus, the device 10 can effectively be used to monitor the number of passages through the surveillance zone 14 and, more generally, to monitor the parameters of the environments 18 and 19 (e.g., to count the number of people present in the second environment 19). This allows respecting the safety parameters of the environments 18 and 19 (e.g., to count the number of people in the second environment 19 to signal any overcrowding) and controlling some functionality of the environments 18 and 19 (e.g., to automatically control the lighting or heating depending on the presence or absence of a person 12 in the second environment 19).

[0100] Furthermore, the device 10 may also allow the speed of passage of the person 12 in the surveillance zone 14 to be calculated, for example based on the time elapsed between the maximum values ​​of two peaks indicating passage and based on the distance travelled by the person 12 through the surveillance zone 14 (known during the design or installation steps of the device 10 ).

[0101] Finally, it is clear that modifications and variations may be made to the various embodiments described and illustrated herein without departing from the scope of the present disclosure herein. For example, the different embodiments described may be combined with each other to provide further solutions.

[0102] although Figure 1 By way of example, an embodiment is shown in which the second environment 19 is a room in a building (e.g., a conference room), the surveillance area 14 is included in a corridor, and the first environment 18 is an external environment or a different room in the building, and other examples can obviously be considered similarly. For example, the second environment 19 can be a building (e.g., a hospital, a stadium, etc.) that can be entered from the external environment 18 through the entrance 16.

[0103] Furthermore, the first environment 18 and the second environment 19 may also be connected to each other through a plurality of corridors / passageways / doors 16. In this case, each of them has a corresponding monitoring area 14, and for each monitoring area 14, there is a corresponding device 10, so that a person 12 passing through any of these corridors / passageways / doors 16 from the first environment 18 to the second environment 19 or from the second environment 19 to the first environment 18 can be detected by the corresponding device 10. In other words, if there are a plurality of corridors / passageways / doors 16, each of them is monitored so that a person 12 passing from the first environment 18 to the second environment 19 or from the second environment 19 to the first environment 18 can still be detected.

[0104] Furthermore, although reference has been made so far to a single person 12 passing between the first environment 18 and the second environment 19, it is apparent that what has been described previously applies in a similar manner to a plurality of persons 12. In this way, the number of persons 12 present in the second environment 19 can be monitored, for example, in order to control a parameter or functionality of the second environment 19 (e.g., air conditioning flow intensity, etc.).

[0105] Furthermore, although reference has thus far been made to a person 12 passing through surveillance zone 14, the foregoing description applies in a similar manner to any emitter (e.g., an animal) that emits infrared radiation. Thus, person 12 is but one example of any emitter 12 that device 10 can detect.

[0106] A device (10) can be used to detect passage of an infrared (IR) radiation emitter (12) in a surveillance zone (14), the device (10) having a first surface (20a) and a second surface (20b) that are inclined with respect to each other and configured to face the surveillance zone (14). The device (10) can be summarized as comprising a first IR radiation sensor (22a) extending on the first surface (20a) and a second IR radiation sensor (22b) extending on the second surface (20b), the first IR radiation sensor (22a) being configured to detect IR radiation from the emitter (12) when the emitter (12) is located in a first field of view (24a) of the first IR radiation sensor (22a), and the second IR radiation sensor (22b) being configured to detect IR radiation from the emitter (12) when the emitter (12) is located in a second field of view (24b) of the second IR radiation sensor (22b), wherein the first field of view (24a) and the second field of view (24b) are configured to partially overlap each other at the surveillance zone (14).

[0107] The first IR radiation sensor (22a) and the second IR radiation sensor (22b) each include a respective "thermal MOS" TMOS configured to detect IR radiation emitted by the emitter (12) in the first field of view (24a) and the second field of view (24b), respectively.

[0108] The first surface (20a) and the second surface (20b) have a first inclination angle (α) between 110° and 170° with respect to each other.

[0109] The first field of view (24a) and the second field of view (24b) have a mutual overlapping area (28) that is 80% smaller than each of the first field of view (24a) and the second field of view (24b).

[0110] The device may further include a control unit (32) coupled to the first IR radiation sensor (22a) and the second IR radiation sensor (22b) and configured to: receive a first detection signal (T) from the first IR radiation sensor (22a); object,1 ; T motion,1 ) and a second detection signal (T object,2 ; T motion,2 ), the first detection signal (T object,1 ; T motion,1 ) indicates the presence or absence of the emitter (12) in the first field of view (24a) and the second detection signal (T object,2 ; T motion,2 ) indicates the presence or absence of the emitter (12) in the second field of view (24b); based on the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (Tobject,2 ; T motion,2 ) to determine whether passage of the emitter (12) in the surveillance area (14) occurs.

[0111] If passage of the emitter (12) in the surveillance zone (14) is detected, the control unit (32) is further configured to detect, based on the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) to verify whether the passage of the emitter (12) in the monitoring area (14) occurs along a first passage direction or along a second passage direction, the first passage direction and the second passage direction being opposite to each other and extending in the monitoring area (14).

[0112] The first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) are corresponding temperature signals (T ) indicating the temperature of the emitter (12) when the emitter (12) is present in the first field of view (24a) and the second field of view (24b), respectively. object ), or the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) is the corresponding motion signal (T motion ), which indicates a corresponding temperature signal (T) configured to be generated by the first IR radiation sensor (22a) and the second IR radiation sensor (22b), respectively, and indicating the temperature of the emitter (12) when the emitter (12) is present in the first field of view (24a) and the second field of view (24b), respectively. object ) changes over time.

[0113] To determine whether passage of the emitter (12) in the surveillance zone (14) occurs, the control unit (32) is configured to: verify the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) in the passage time interval (Δt max ) respectively have a first signal peak value and a second signal peak value, the passage time interval is measured from the first signal peak value of the first signal peak value and the second signal peak value; and if the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) in the passage time interval (Δt max) has a first signal peak and a second signal peak, then the passage of the emitter (12) in the monitoring area (14) is confirmed.

[0114] If the first detection signal (T object,1 ) and the second detection signal (T object,2 ) is the corresponding temperature signal (T object ), the control unit (32) is configured to confirm that if the first detection signal and the second detection signal are within a passing time interval (Δt max ) have successively: the first detection signal (T object,1 ) rising edge (K 1b ′), the second detection signal (T object,2 ) rising edge (K 2a ′), the first detection signal (T object,1 )'s falling edge (K 1b ″) and the second detection signal (T object,2 )'s falling edge (K 2a ″); or the second detection signal (T object,2 ) rising edge (K 2b ′), the first detection signal (T object,1 ) rising edge (K 1c ′), the second detection signal (T object,2 )'s falling edge (K 2b ″) and the first detection signal (T object,1 )'s falling edge (K 1c ″), then the first detection signal (T object,1 ) and the second detection signal (T object,2 ) in the passage time interval (Δt max ) respectively have a first signal peak and a second signal peak.

[0115] If the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) is the corresponding motion signal (T motion ), the control unit (32) is configured to confirm that if within the passing time interval (Δt max ) appear successively with each other: the first detection signal (T motion,1 ) from the switching threshold (T m,th ) becomes lower than the switching threshold (T m,th ) is high, the second detection signal (T motion,2 ) from the switching threshold (T m,th ) becomes lower than the switching threshold (T m,th ) is high, the first detection signal (T motion,1) from the switching threshold (T m,th ) becomes higher than the switching threshold (T m,th ) is low, the second detection signal (T motion,2 ) from the switching threshold (T m,th ) becomes higher than the switching threshold (T m,th ) is low, or the second detection signal (T motion,2 ) from the switching threshold (T m,th ) becomes lower than the switching threshold (T m,th ) is high, the first detection signal (T motion,1 ) from the switching threshold (T m,th ) becomes lower than the switching threshold (T m,th ) is high, the second detection signal (T motion,2 ) from the switching threshold (T m,th ) becomes higher than the switching threshold (T m,th ) is low, the first detection signal (T motion,1 ) from the switching threshold (T m,th ) becomes higher than the switching threshold (T m,th ) is low, the first detection signal and the second detection signal are in the time interval (Δt max ) respectively have a first signal peak and a second signal peak.

[0116] To verify whether the passage of the emitter (12) in the monitoring area (14) occurs in the first passage direction or the second passage direction, the control unit (32) is configured to verify that max ) which of the first signal peak and the second signal peak is detected first; and if in the passage time interval (Δt max ), it is determined that the emitter (12) has passed through the monitoring area (14) along the first passing direction, or if the first signal peak in the passing time interval (Δt max ) is before the first signal peak, it is determined that the emitter (12) has passed through the monitoring area (14) along the second passing direction.

[0117] A method (50) can be used to detect the passage of an infrared (IR) radiation emitter (12) in a surveillance area (14), the method being performed by a device (10) having a first surface (20a) and a second surface (20b) that are inclined to each other and configured to face the surveillance area (14), and comprising a first IR radiation sensor (22a) extending on the first surface (20a), a second IR radiation sensor (22b) extending on the second surface (20b), and a control unit (32) coupled to the first IR radiation sensor (22a) and the second IR radiation sensor (22b). The method can be summarized as comprising the following steps: when the emitter (12) is located in a first field of view (24a) of the first IR radiation sensor (22a), the first IR radiation sensor (22a) detects (S10) IR radiation of the emitter (12); when the emitter (12) is located in a second field of view (24b) of the second IR radiation sensor (22b), the second IR radiation sensor (22b) detects (S10) IR radiation of the emitter (12); and receiving (S12) a first detection signal (T10) from the first IR radiation sensor (22a) by a control unit (32); object,1 ; T motion,1 ) and a second detection signal (T object,2 ; T motion,2 ), the first detection signal (T object,1 ; T motion,1 ) indicates the presence or absence of the emitter (12) in the first field of view (24a), and the second detection signal (T object,2 ; T motion,2 ) indicates the presence or absence of the emitter (12) in the second field of view (24B), and the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) is generated according to the IR radiation detected by the first IR radiation sensor (22a) and the second IR radiation sensor (22b), respectively; and by the control unit (32) and based on the first detection signal (T object,1 ; T motion,1 ) and the second detection signal (T object,2 ; T motion,2 ) to determine (S14) whether passage of an emitter (12) in a surveillance zone (14) occurs, wherein the first field of view (24a) and the second field of view (24b) are configured to partially overlap each other at the surveillance zone (14).

[0118] The method may further comprise the following steps: if passage of the emitter (12) in the surveillance area (14) is detected, based on the first detection signal (T object,1 ; Tmotion,1 ) and the second detection signal (T object,2 ; T motion,2 ) to verify (S16) whether the passage of the emitter (12) in the monitoring area (14) occurs along a first passage direction or along a second passage direction, the first passage direction and the second passage direction being opposite to each other and extending in the monitoring area (14).

[0119] The various embodiments described above can be combined to provide other embodiments. These and other changes can be made to the embodiments according to the above detailed description. In general, in the following claims, the terms used should not be understood to limit the claims to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments within the entire equivalent scope of the rights granted to these claims. Accordingly, the claims are not limited by the present disclosure.

Claims

1. A device for detecting the passage of an infrared (IR) radiation emitter in a surveillance area, the device comprising: a first surface; a second surface, the first surface and the second surface being inclined to each other and configured to face the monitoring area; a first IR radiation sensor extending over the first surface, the first IR radiation sensor configured to detect IR radiation from the emitter when the emitter is within a first field of view of the first IR radiation sensor; as well as A second IR radiation sensor extends on the second surface, the second IR radiation sensor being configured to detect IR radiation from the emitter when the emitter is located in a second field of view of the second IR radiation sensor, the first field of view and the second field of view being configured to partially overlap each other at the monitoring area.

2. The device of claim 1 , wherein the first IR radiation sensor and the second IR radiation sensor each comprise a corresponding thermal metal oxide semiconductor (TMOS) sensor configured to detect IR radiation emitted by the emitter in the first field of view and the second field of view, respectively. 3 . The apparatus of claim 1 , wherein the first surface and the second surface have a first inclination angle with respect to each other, the first inclination angle being between 110° and 170°.

4. The apparatus of claim 1, wherein the first field of view and the second field of view have a mutual overlapping area that is 80% smaller than each of the first field of view and the second field of view.

5. The apparatus according to claim 1, further comprising: a control unit coupled to the first IR radiation sensor and the second IR radiation sensor, the control unit being configured to: receiving a first detection signal from the first IR radiation sensor, the first detection signal indicating the presence or absence of the emitter in the first field of view; receiving a second detection signal from the second IR radiation sensor, the second detection signal indicating the presence or absence of the emitter in the second field of view; as well as Whether passage of the emitter in the surveillance zone has occurred is determined based on the first detection signal and the second detection signal.

6. The device according to claim 5, wherein if it has been determined that the passage of the emitter in the monitoring area has occurred, the control unit is configured to verify whether the passage of the emitter in the monitoring area has occurred along a first passage direction or along a second passage direction based on the first detection signal and the second detection signal, the first passage direction and the second passage direction being opposite to each other and extending in the monitoring area.

7. The apparatus of claim 5, wherein the first detection signal and the second detection signal are respective temperature signals indicating the temperature of the emitter when the emitter is present in the first field of view and the second field of view, respectively, or The first detection signal and the second detection signal are corresponding motion signals, the corresponding motion signals indicate changes in corresponding temperature signals over time, and the corresponding temperature signals are configured to be generated by the first IR radiation sensor and the second IR radiation sensor, respectively, and indicate the temperature of the emitter when the emitter is respectively present in the first field of view and the second field of view.

8. The device according to claim 5, wherein to determine whether the passage of the emitter in the surveillance zone occurs, the control unit is configured to: verifying whether the first detection signal and the second detection signal have a first signal peak value and a second signal peak value, respectively, within a passing time interval, the passing time interval being measured from a first one of the first signal peak value and the second signal peak value; and If the first detection signal and the second detection signal have the first signal peak value and the second signal peak value in the passage time interval, the passage of the emitter in the surveillance zone is confirmed.

9. The device according to claim 7, wherein if the first detection signal and the second detection signal are corresponding temperature signals, the control unit is configured to, if the first detection signal and the second detection signal have the following contents that are continuous with each other in the passage time interval: a rising edge of the first detection signal, a rising edge of the second detection signal, a falling edge of the first detection signal, and a falling edge of the second detection signal; or a rising edge of the second detection signal, a rising edge of the first detection signal, a falling edge of the second detection signal, and a falling edge of the first detection signal, It is then confirmed that the first detection signal and the second detection signal have a first signal peak value and a second signal peak value, respectively, within the passage time interval, and the passage time interval is measured from the first of the first signal peak value and the second signal peak value.

10. The device according to claim 7, wherein if the first detection signal and the second detection signal are corresponding motion signals, the control unit is configured to, if appearing successively to each other in a passage time interval: the first detection signal changes from a value lower than the switching threshold to a value higher than the switching threshold, the second detection signal changes from a value lower than the switching threshold to a value higher than the switching threshold, the first detection signal changes from a value higher than the switching threshold to a value lower than the switching threshold, the second detection signal changes from a value higher than the switching threshold to a value lower than the switching threshold, or the second detection signal changes from a value lower than the switching threshold to a value higher than the switching threshold, the first detection signal changes from a value lower than the switching threshold to a value higher than the switching threshold, the second detection signal changes from a value higher than the switching threshold to a value lower than the switching threshold, and the first detection signal changes from a value higher than the switching threshold to a value lower than the switching threshold, It is then confirmed that the first detection signal and the second detection signal have a first signal peak value and a second signal peak value, respectively, within the passage time interval, and the passage time interval is measured from the first of the first signal peak value and the second signal peak value.

11. The device according to claim 6, wherein, to verify whether the passage of the emitter in the surveillance zone occurs along the first passage direction or along the second passage direction, the control unit is configured to: verifying which of a first signal peak of the first detection signal and a second signal peak of the second detection signal has been detected in a passage time interval, the passage time interval being measured starting from a first of the first signal peak and the second signal peak; and If the first signal peak is before the second signal peak in the passage time interval, it is determined that the passage of the emitter in the monitoring area has occurred along the first passage direction, or if the second signal peak is before the first signal peak in the passage time interval, it is determined that the passage of the emitter in the monitoring area has occurred along the second passage direction.

12. A method for detecting the passage of an infrared (IR) radiation emitter in a surveillance area, the method comprising: detecting IR radiation from the emitter by a first IR radiation sensor when the emitter is within a first field of view of a first IR radiation sensor, the first IR radiation sensor being on a first surface of the device; detecting IR radiation of the emitter by a second IR radiation sensor when the emitter is located in a second field of view of a second IR radiation sensor, the second IR radiation sensor being disposed on a second surface of the device, the first surface and the second surface being inclined relative to each other and configured to face the surveillance zone; receiving, by a control unit of the device, a first detection signal from the first IR radiation sensor and a second detection signal from the second IR radiation sensor, the first detection signal indicating the presence or absence of the emitter in the first field of view, the second detection signal indicating the presence or absence of the emitter in the second field of view, the first detection signal and the second detection signal being generated based on the IR radiation detected by the first IR radiation sensor and the second IR radiation sensor, respectively, the first field of view and the second field of view being configured to partially overlap each other at the surveillance zone; as well as Whether the passage of the emitter in the surveillance zone has occurred is determined by the control unit and based on the first detection signal and the second detection signal.

13. The method according to claim 12, further comprising: If it has been determined that the passage of the emitter in the surveillance area has occurred, it is verified based on the first detection signal and the second detection signal whether the passage of the emitter in the surveillance area has occurred along a first passage direction or along a second passage direction, the first passage direction and the second passage direction being opposite to each other and extending in the surveillance area.

14. The method of claim 12, wherein the first detection signal and the second detection signal are respective temperature signals indicating the temperature of the emitter when the emitter is present in the first field of view and the second field of view, respectively, or The first detection signal and the second detection signal are corresponding motion signals, the corresponding motion signals indicate changes in corresponding temperature signals over time, and the corresponding temperature signals are configured to be generated by the first IR radiation sensor and the second IR radiation sensor, respectively, and indicate the temperature of the emitter when the emitter is respectively present in the first field of view and the second field of view.

15. The method according to claim 12, further comprising: verifying, by the control unit, whether the first detection signal and the second detection signal have a first signal peak value and a second signal peak value, respectively, within a passing time interval, the passing time interval being measured from a first one of the first signal peak value and the second signal peak value; as well as In the case where the first detection signal and the second detection signal have the first signal peak value and the second signal peak value in the passage time interval, the passage of the emitter in the surveillance zone is confirmed by the control unit.

16. A device comprising: a first surface facing the surveillance area,; a second surface facing the surveillance area; a first infrared (IR) radiation sensor located on the first surface, the first IR radiation sensor having a first field of view, the first IR radiation sensor being configured to detect first IR radiation emitted by the body when the body is located in the first field of view; a second infrared (IR) radiation sensor located on the second surface, the second IR radiation sensor having a second field of view that partially overlaps the first field of view, the second IR radiation sensor being configured to detect second IR radiation emitted by the body when the body is located in the second field of view; A control unit is coupled to the first IR radiation sensor and the second IR radiation sensor, the control unit being configured to determine passage of the body through the surveillance zone based on the first IR radiation and the second IR radiation.

17. The apparatus of claim 16, wherein the first surface and the second surface are surfaces of a substrate and the angle relative to the first surface and the second surface and extending through the substrate is between 110° and 170°.

18. The apparatus of claim 16, wherein the portion where the first field of view and the second field of view overlap is less than 80% of each of the first field of view and the second field of view.

19. The apparatus of claim 16, wherein the control unit is configured to determine a direction of the passage of the body through the surveillance zone based on the first IR radiation and the second IR radiation.

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