Improved metal detector device for locating the presence of metal objects

Abstract

The present invention relates to a system for detecting prohibited items worn or carried by an individual, comprising a metal detector, the metal detector comprising at least three transducers (141, 142, 143) arranged on both sides of a channel (102), two of the transducers (142, 143) being placed on the same side of the channel (102) and spaced longitudinally apart in the direction of movement through the channel (102), while the third transducer (141) being arranged on the opposite side of the channel (102), so that the three transducers (141, 142, 143) can be combined to perform spatial discrimination on the position of the detected metal object (M1, M2, M3).

Description

Technical Field

[0001] The present invention relates to the field of detectors designed to detect prohibited objects or substances in restricted areas.

[0002] The present invention relates more particularly to the field of inductive metal detectors.

[0003] The invention has particular, but not exclusive, application in the integration of metal detectors in body scanners designed to perform checks before individuals (e.g. passengers) board aircraft, and before individuals enter public places (e.g. sports venues, such as stadiums or auditoriums), in order to detect prohibited items concealed in clothing. These devices can in particular avoid systematic palpation. Background Art

[0004] It now appears necessary to monitor very reliably attempts to bring prohibited items, especially weapons, into or out of sensitive areas.

[0005] The questions asked therefore cover a wide range of situations, including but not limited to attempts to bring prohibited items into protected areas (e.g. airports, shops, schools, train stations, public or private organizations), or to take prohibited items out of the prescribed area (e.g. to prevent theft in a company or protected location).

[0006] There are different types of metal object detectors. These metal detectors are usually inductive detectors. They comprise at least one transmitting coil and at least one receiving coil. The transmitting coil is powered by an alternating current. The receiving coil is designed to detect disturbances in this magnetic field due to the presence of a metal object, such as a decay in the amplitude of the magnetic field, or a change in the phase of the signal, for example due to the generation of eddy currents on the metal object.

[0007] There are also different types of body scanners. The oldest body scanner is the X-ray body scanner. Newer body scanners use wave technology called millimeter wave technology.

[0008] An example of a body scanner can be found in document EP 2 202 700. This document proposes in particular to provide an additional metal detector at the entrance of the body scanner.

[0009] For several years, body scanners have been developed to detect weapons, explosives, etc. concealed under the clothing of individuals entering protected areas. All of these systems use technology based on detecting radiant energy modulated, reflected or emitted by the body of the individual being inspected. Radiant energy used in this way includes X-rays, microwaves, millimeter waves, infrared light, terahertz waves, and ultrasound.

[0010] Although various types of radiation energy and imaging geometries are used, these body scanners all create an electronic image of an individual through which the individual's clothing is transparent. This image is then displayed on a screen and viewed by an operator who can determine whether the individual is carrying a target object. To do this, an operator trained in detecting target objects must be able to determine whether an object identified by a body scanner corresponds to human anatomy, an authorized object (e.g., a lighter, handkerchief, or spare parts), or a target object such as a weapon or explosive.

[0011] Today, it has been shown that individuals who attempt to fraudulently bring prohibited items, especially weapons, into protected areas use all sorts of imaginative means to conceal said items, such as by dividing the items into different pieces and scattering them around the body.

[0012] Examinations using body scanners are therefore becoming increasingly complex and time-consuming to perform.

[0013] Furthermore, while existing metal detectors are generally satisfactory in detecting the presence or absence of metal objects, they are often inadequate in detecting the location of such metal objects on an individual's person.

[0014] Document EP 1 750 148 describes a metal detector comprising three or four coils arranged on both sides of a channel in order to determine the position of a target object worn transversely and / or centrally to an individual.

[0015] Document US 4 012 690 describes a detection system comprising induction loops parallel to each other and surrounding a door.

[0016] Document EP 2 202 700 describes a detection system which combines two detection techniques.

[0017] Document WO 2018 / 225028 describes a system comprising a body scanner and a shoe detection device. Summary of the invention

[0018] It is an object of the present invention to propose new detection devices for improving the detection of target objects that can be concealed on the body of an individual.

[0019] Another object of the invention is to allow the localization of metal objects detected on a person.

[0020] In particular, it is an object of the present invention to provide a detection device that is effective regardless of where the concealed object is attached to the individual's body.

[0021] A second object of the invention is to propose a device allowing examinations to be carried out using a body scanner with greater accuracy and speed than the body scanners of the prior art.

[0022] The objects according to the invention are achieved by means of a system for detecting prohibited items carried by a person and a method for detecting associated prohibited items according to the appended independent claims. Embodiments are subject matter of the dependent claims.

[0023] Note that the system of the invention allows further improvement of the determination regarding the position of a metal object identified by at least three transducers, in particular compared to document EP 1 750 148 in the name of the applicant. In fact, it is not possible to discern the position of a metal object in depth direction (front / back) without passing through a detection barrier and based solely on the signals from at least three transducers.

[0024] In particular, the detection system includes a metal detector, which includes at least three inductive transducers arranged on both sides of a channel, two of which are placed on the same side of the channel and longitudinally spaced apart in the direction of movement in the channel, and the third transducer is arranged on the opposite side of the channel, so that the three transducers in combination allow spatial discrimination of the position of a detected metal object.

[0025] According to another advantageous feature of the invention, the system comprises a combination of a body scanner and said metal detector integrated into the body scanner, the metal detector being adapted to control the body scanner by adjusting the sensitivity of the body scanner at least in the region of interest depending on whether the metal detector detects a metal object.

[0026] According to another advantageous feature of the invention, the metal detector comprises three inductive transducers forming one transmitter and two receivers, for example arranged in the form of one transmitter on a first side of the passage and two associated receivers arranged on opposite sides of the passage.

[0027] According to another advantageous feature of the invention, the metal detector comprises three inductive transducers forming two transmitters and one receiver, for example arranged in the form of two transmitters on a first side of the passage and an associated receiver on the opposite side of the passage.

[0028] According to another advantageous feature of the invention, the metal detector comprises four inductive transducers forming two transmitters and two receivers, for example arranged in the form of two transducers located on a first side of the passage and two transducers arranged on the opposite side of the passage.

[0029] According to another advantageous feature of the invention, the metal detector comprises at least three inductive transducers suitable for identifying the position of the detected metal object, on the one hand in the width direction of the channel transverse to the movement direction, usually on the left or right side of the individual, and on the other hand in the depth direction longitudinally parallel to the movement direction, usually on the front or back of the individual.

[0030] According to another advantageous characteristic of the invention, each inductive transducer is suitable for operating alternately as a transmitter and / or as a receiver.

[0031] According to another advantageous characteristic of the invention, each transducer is formed by at least one coil.

[0032] According to another advantageous feature of the invention, the metal detector comprises at least one passage detection barrier, for example an optical barrier, associated with the transducer to detect the position of an individual in the passage relative to the transducer.

[0033] According to another advantageous feature of the invention, the metal detector comprises three passage detection barriers, for example three optical barriers, distributed longitudinally along the passage in the metal detector and associated with the transducer to detect the position of a person in the passage relative to the transducer.

[0034] According to another advantageous feature of the present invention, the metal detector includes an inductive transducer, which generates a main detection line between two transducers, respectively a transmitting transducer and a receiving transducer, some of which are transverse to the direction of movement in the metal detector, while others are inclined or diagonally inclined relative to the direction of movement in the metal detector. The transverse detection lines are mainly used to detect metal objects carried by an individual on the front and back of his body. In this regard, the front and back of the individual's body first reach and last leave these lines, respectively, while the inclined detection lines are mainly used to detect metal objects carried by an individual on his left or right side. In this regard, the side of the individual continuously passes through these lines.

[0035] The present invention also relates to a method for detecting prohibited items carried by an individual using a metal detector, the metal detector comprising at least three inductive transducers arranged on both sides of a channel, two of the transducers being placed on the same side of the channel and longitudinally spaced apart in the direction of movement in the channel, and the third transducer being arranged on the opposite side of the channel, characterized in that it includes the step of detecting a metal object carried by an individual by using the metal detector to detect and locate the three-dimensional spatial position of the detected metal object on the individual.

[0036] According to another advantageous feature, the method of the invention comprises the step of controlling the body scanner by adjusting the sensitivity of the body scanner in at least one region of interest corresponding to the location of the metal object detected by the metal detector depending on whether the associated metal detector detects a metal object. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other characteristics, objectives and advantages of the invention will become apparent on reading the following detailed description and with reference to the accompanying drawings, given by way of non-limiting examples, in which:

[0038] Figure 1a , 1b1c and 1c schematically show horizontal cross-sectional views of metal detectors according to three alternatives of the present invention, respectively,

[0039] Figure 1d A perspective view schematically showing a metal detector according to a preferred embodiment of the present invention,

[0040] Figures 2a to 2i 1 represents a series of detection sequences when a person passes through a metal detector channel using a metal detector including three transducers according to the present invention, and more specifically, represents nine consecutive steps of the detection process,

[0041] Figure 3a and 3b represents the signal obtained on the receiving transducer shown in FIG2 when a person carrying a metal object on his front, back, left and right sides passes through the channel of the metal detector,

[0042] Figure 3c and 3d Schematically represents the signal obtained on the receiving transducer shown in FIG2 when the individual passes through the channel of the metal detector under the theoretical assumption that the metal object completely surrounds the individual being inspected.

[0043] Figure 4a , 4b and 4c represent the signals obtained at the exit through the detection barrier shown in FIG2 when an individual passes through the metal detector,

[0044] FIG. 5 shows a series of detection sequences performed using a variant of a metal detector according to the present invention comprising four transducers, two of which are transmitting transducers and two of which are receiving transducers, when a person carrying a metal object on his front, back, left and right sides passes through the channel of the metal detector, more specifically, Figures 5a to 5h Represents the eight consecutive steps of the detection process,

[0045] Figure 6a , 6b , 6c and 6d represent the signals obtained on the receiving transducer shown in FIG. 5 when a person passes through the metal detector after the transmitting transducer is continuously activated,

[0046] Figure 6e , 6f , 6g and 6h schematically represent the signals obtained on the receiving transducer shown in FIG. 5 when the individual passes through the channel of the metal detector under the theoretical assumption that the metal object completely surrounds the individual under inspection.

[0047] Figure 7a , 7b 7c and 7c represent the signals obtained at the exit of the detection screen shown in FIG5 when an individual passes through the passage of the metal detector,

[0048] Figure 8 A flow chart schematically showing an example of a detection method according to the present invention,

[0049] Fig. 9 A perspective view schematically showing an apparatus for integrating a metal detector into a body scanner according to the present invention,

[0050] Figures 10a to 10e Schematically showing horizontal cross-sections of five alternatives of such a body scanner with integrated metal detector according to the invention, and

[0051] Fig.11 A flow chart schematically represents an exemplary detection method using a device according to the present invention, the device comprising a body scanner with an integrated metal detector,

[0052] Fig.12 is a flow chart illustrating the steps of a method for detecting prohibited items carried by an individual according to one embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to improve the detection of target objects that can be hidden on a person's body, the present invention proposes a system for detecting prohibited items carried by a person according to the present invention, the system comprising a metal detector 100, the metal detector 100 comprising transducers 141, 142, 143 located in the metal detector 100, at least one through-detection barrier 130, and a central unit 50, which analyzes the signal from the transducer 140 through the detection barrier 130 to infer therefrom at which part of the person's body the metal objects M1, M2, M3 are located.

[0054] First describe Figure 1a , 1b , 1c and 1d show the structure of the metal detector 100.

[0055] The inductive metal detector 100 is preferably formed by a walk-through detector or a similar detector, which includes two vertical posts or panels 110, 120, on which a horizontal rod 160 is mounted, such as Figure 1d shown.

[0056] The central unit 50 may be housed anywhere in the system, for example in the housing of the detector 100, typically at the horizontal bar 160. In particular, the central unit 50 may comprise a computer of the processor, microprocessor, microcontroller type configured to execute instructions.

[0057] The metal detector 100 defines a passage or path 102 through which any person must pass when passing through the walk-through detector. The passage or path 102 is formed by two side panels 110,120.

[0058] The side panels 110, 120 house means 140 forming metal detectors. These means 140 are preferably formed by coils placed in the panels 110, 120 respectively.

[0059] Coil-based metal detector technology is well known to those skilled in the art and will therefore not be described in detail below.

[0060] However, it should be remembered that usually inductive metal detectors include at least one transmitting coil placed on one side of the channel 102 and at least one receiving coil placed on the opposite side of the channel 102. The transmitting coil is powered by an alternating current of a monitoring frequency, which is preferably a series of determined and monitored frequencies, to emit a magnetic field usually between 100 Hz and 50 kHz. The receiving coil is designed to detect disturbances of the magnetic field caused by the presence of a metal object in the channel 102 and the movement of the metal object in the channel 102, such as a decay of the magnetic field amplitude, or a signal phase change, which is for example due to the generation of eddy currents on the metal object.

[0061] In practice, each transmitting coil and receiving coil is preferably formed by a plurality of elementary coils or turns, covering a corresponding height portion of the walk-through detector, to allow the position of detected metallic targets to be discerned, thereby locating the position of these targets in height.

[0062] Furthermore, preferably, each coil is alternately a transmitting coil and a receiving coil.

[0063] Figure 1a 1 represents a first alternative according to which the device 140 is formed by three coil transducers 141 , 142 , 143 distributed between the side plates 110 , 120 in the form of at least one coil 141 in the side plate 120 and two coils 142 , 143 in the opposite side plate 110 .

[0064] The two coils 142 and 143 located in the common side plate 110 or 120 are also longitudinally spaced apart.

[0065] As will be explained below, this configuration allows metal detection of the three-dimensional position of metal. This three-dimensional positioning can be achieved due to the individual's successive crossing of several privileged detection lines (these detection lines correspond to virtual lines connecting the centers of the transmitting and receiving coils, respectively). Therefore, if it is arbitrarily considered that the coil 141 located on one side of the detector 100 is a transmitting coil, and the two coils 142 and 143 located on the opposite side of the detector 100 are receiving coils, then the individual moving in the detector 100 successively crosses the first privileged line 141D connecting the transducers 141 and 142 and extending transversely to the direction of movement in the metal detector, and then crosses the second privileged line 143D connecting the transducers 141 and 143 and oriented obliquely relative to the direction of movement in the metal detector.

[0066] Figure 1b 1 shows an alternative solution according to which the device 140 is formed by four coil transducers 141 , 142 , 143 and 144 distributed between the side plates 110 , 120 , in the form of two coils 141 and 144 in the side plate 120 and two coils 142 , 143 in the opposite side plate 110 .

[0067] The two coils 141 and 144 located in the common side plate 120 are spaced apart longitudinally. The two coils 142 and 142 located in the other common side plate 110 are also spaced apart longitudinally.

[0068] This configuration allows metal detection of the three-dimensional location of metal. This three-dimensional positioning is achieved due to the individual's successive crossing of several privileged detection lines (these detection lines correspond to virtual lines connecting the centers of the transmitting and receiving coils, respectively). Therefore, if the coil 141 located on one side of the detector 100 is arbitrarily considered to be a transmitting coil, and the two coils 142 and 143 located on the opposite side of the detector 100 are receiving coils, the individual moving in the detector 100 sequentially crosses the first privileged line 141D connecting the transducers 142 and 141, and then crosses the second privileged line 143D connecting the transducers 141 and 143. Similarly, if the coil 144 located on one side of the detector 100 is arbitrarily considered to be a transmitting coil, and the two coils 142 and 143 located on the opposite side of the detector 100 are receiving coils, the individual moving in the detector 100 sequentially crosses the oblique privileged line 142D connecting the transducers 144 and 142, and then crosses the transverse privileged line 144D connecting the transducers 144 and 143.

[0069] Advantageously, transducers 142 and 143 are placed facing transducers 141 and 144, respectively.

[0070] Also remember that each of the four transducers 141, 142, 143 and 144 can alternately operate in either a transmit mode or a receive mode.

[0071] according to Figure 1a and 1b , the transducers 141 , 142 , 143 , and 144 are configured in the form of coils wound around corresponding poles.

[0072] Preferably, Figure 1a and 1b The width D of each cylindrical transducer 141, 142, 143 and 144 shown is between 140 and 300 mm, and the interval L between two adjacent columns 141 and 144 or 142 and 143 is preferably between 1.5 and 3 times the width D, that is, between 210 mm and 900 mm, so the center distance between the transducer pairs is between 350 mm and 1,200 mm, and the lateral distance W between two opposing cylindrical transducers 141 and 142 or 144 and 143 is preferably between 680 and 820 mm.

[0073] Therefore, the angle formed by the lateral detection lines 141D and 144D connecting the opposite transducer pairs 141 and 142 on the one hand and the opposite transducer pairs 144 and 143 on the other hand and the inclined detection lines 142D and 143D connecting the diagonally positioned transducer pairs is between 15° and 60°, or typically about 30° to 45°.

[0074] This angle is particularly important for allowing the location of metal targets across the width of the individual, i.e., determining whether the metal target is to the left or right of the individual. By defining detection lines 142D and 143D that are actually tilted relative to the direction of movement of the individual, this angle imposes which detection line (142 / 144, 143 / 141, 144 / 142, 141 / 143) passes through one side of the individual first or last.

[0075] The localization of the metal target between the front and back of the person is performed in particular when the front or back of the person crosses the transverse detection lines 141D and 144D (141 / 142, 143 / 144, 142 / 141, 144 / 143).

[0076] Of course, the central unit 50 specifies the position (left / right, front / back) of the metal target using all the data detected by all the receiving transducers 141, 142, 143 and 144. In fact, the detected metal objects, whether located on the left or right side of the individual, in front of the individual or behind the individual, will have an impact when they cross the detection line, whether lateral or oblique.

[0077] Figure 1c Represents something like Figure 1a and 1b An alternative solution according to which Figure 1a and1b The cylindrical transducers 141, 144 and 142, 143 are Figure 1c In the Figure 1c In FIG. 1 , the option of having three panel-type transducers 141 , 142, 143 is indicated by solid lines. The option of having four panel-type transducers 141 , 142, 143, 144 is also indicated, wherein the fourth transducer 144 is indicated by dashed lines.

[0078] Preferably, Figure 1c The width D of each panel of the transducers 141, 142, 143 and 144 represented in FIG. 1 is between 140 and 600 mm. Figure 1a and 1b The values ​​shown for the gap L between the transducers, the lateral distance W between the transducers and the angles between the lateral and oblique detection lines formed thereby still apply. Figure 1c .

[0079] The side panels 110 , 120 also accommodate means 130 forming a through detection barrier, which is longitudinally distributed over the movement path in the passage 102 .

[0080] The pass detection barrier 130 may be formed by any known technology, such as but not limited to an optical barrier.

[0081] According to the particular embodiment represented in FIG. 1 , three successive passing detection barriers 131 , 132 and 133 are therefore provided along the movement path in the metal detector 100 .

[0082] In practice, each of the passing detection barriers may include a transmitter 131.1, 132.1, 133.1 placed in one of the panels 110 or 120 and a receiver 131.2, 132.2, 133.2 placed in the opposite panel 120 or 110 opposite to each other. The receiver receives the signal from the oppositely placed transmitter as long as there is no obstacle between the receiver and the transmitter. On the other hand, when a person stands between the transmitter and the receiver, the receiver does not receive the signal from the opposite transmitter.

[0083] As an individual moves through the passage 102, the corresponding signals received at the receivers 131.2, 132.2, 133.2 are Figure 4a , 4b and 4c and Figure 7a , 7b and 7c.

[0084] As in these Figure 4a , 4bAs can be seen in 4c and 7a, 7b and 7c, as a person passes through the passage 102, the outlets of the receivers 131.2, 132.2, 133.2 continuously change state in either positive or negative logic.

[0085] The relative positioning between the detection barriers 130, 131, 132 and 133 and the metal detection transducers 140, 141, 142 and 143 may be the subject of different embodiments and are not limited to the embodiments shown in the drawings. For example, it will be noted that Figure 1a , 1b The positioning of the safety barriers shown in 1 and 1c is different from that shown in FIGS. 2 and 5 .

[0086] According to the embodiment illustrated in FIG. 1 , transducers 141 and 142 are placed opposite each other on both sides of the channel 102, in panels 110, 120, respectively, at the same longitudinal level in the passing direction in the channel 102. They define a main transverse detection line 141D. A third transducer 143 is in the same panel 110, offset downstream with respect to the passing direction in the channel 102 with respect to the transducer 142. It defines in combination with the transducer 141 a main inclined detection line 143D. Similarly, a fourth transducer 144 is in the same panel 120, offset downstream with respect to the passing direction in the channel 102 with respect to the transducer 141, facing the transducer 143. It defines in combination with the transducer 143 a main transverse detection line 144D and in combination with the transducer 142 a inclined detection line 142D.

[0087] Preferably, at least one through detection barrier 130 coincides with the transducer pair 140 in longitudinal position, thus coinciding with the preferred transverse detection line 141D or 144D. According to Figures 1 and 5, barrier 131 coincides with the transducer pair 141-142, while barrier 133 coincides with the transducer pair 143-144. According to Figure 2, barrier 132 coincides with the transducer pair 141-142.

[0088] Furthermore, preferably, at least one through detection barrier 130 coincides in longitudinal position with the intersection point between the two tilted detection lines 142D and 143D. According to Figures 1 and 5, barrier 132 coincides with the intersection point between the two tilted detection lines 142D and 143D.

[0089] According to the exemplary embodiment shown in FIG1 , a first passage detection barrier 131 formed by a transmitter 131.1 and a receiver 131.2 is located at the transducer pair 141 and 142, that is, at the entrance of the metal detector 100. A central passage detection barrier 132 formed by a transmitter 132.1 and a receiver 132.2 is located between the transducer pair 141 and 142 and a third transducer 143 or a transducer pair 143 and 144. A third passage detection barrier 133 formed by a transmitter 133.1 and a receiver 133.2 is located at the transducers 143 and 144.

[0090] As mentioned above, the positioning of the through detection barriers 131, 132 and 133 relative to the transducer 140 may be the subject of alternatives. According to the embodiment shown in Figure 2, a first through detection barrier 131 formed by a transmitter 131.1 and a receiver 131.2 is located upstream of the transducer pair 141 and 142, a central through detection barrier 132 formed by a transmitter 132.1 and a receiver 132.2 is located at the transducer pair 141 and 142 at the entrance of the metal detector 100, and a third through detection barrier 133 formed by a transmitter 133.1 and a receiver 133.2 is located between the transducer pair 141 and 142 and the transducers 143 and 144 located downstream.

[0091] In order to improve the system's determination of the position detection of metal objects M1, M2, M3, M4 carried by an individual, the central unit 50 is configured to analyze and use the signal from the detection barrier 130 and the signal from the transducer 140, and through the use of this combination, infer the position of the metal objects M1, M2, M3, M4 relative to the individual.

[0092] In practice, the signals from at least three transducers 141, 142, 143 allow the determination of the width position of the metal object on the person, i.e. whether it is located more on the right or left side of the person, by means of the transverse and oblique detection lines. On the other hand, these detection lines do not by themselves identify the depth position of the metal object, i.e. whether the metal object detected by the transducers is on the front or back side of the person.

[0093] On the other hand, the central unit 50 can determine the position of the individual relative to the transducer 140, and more specifically the position of the front of the individual, by means of the signal from the passage detection barrier 130. The passage detection barrier 130 thus allows the central unit 50 to identify a reference for the front of the individual, that is to say to locate the limit of the origin of the individual's body.

[0094] For example, in the case where the detector 100 includes a through detection barrier 132 at the first transducer pairs 141, 142 opposite to each other (along the direction of the individual passing in the detector 100), when the individual passes through the detector 100, the barrier 132 detects the through and generates a through detection signal. Therefore, the central unit 50 infers the front position of the individual at time t. If no metal object is detected at the first transducer pair 141, 142 at time t corresponding to the frontal passage of the individual, the central unit 50 infers that the front of the individual does not carry any metal object M1. On the other hand, when the first transducer pair 141, 142 detects metal objects M1-M4 at a moment of time t that deviates from the barrier 132 to generate the through detection signal, the central unit 50 infers that the metal object M4 is located at the back of the individual rather than the front.

[0095] This reasoning also applies when the first passing detection barrier 130 is offset relative to the first transducer, taking into account the time offset caused by the distance between the detection barrier 130 and the transducer pair 141 , 142 in the direction of the person's passing.

[0096] In one embodiment, the detector 100 comprises several through detection barriers 131, 132, 133. This embodiment further allows to improve the determination of the position of the metal objects M1-M4 on the individual, in particular when crossing the inclined detection line and the possible lateral detection line formed between two other pairs of transducers 143, 144 opposite to each other, and verifying the detection of the metal objects M1-M4 and their position on the individual's body (see in particular Figure 8 Flowchart in, steps 208 / 226 and 216 / 234).

[0097] Now, with respect to FIGS. 2, 3 and 4, using Figure 1a A metal detector of the type shown comprising three inductive transducers 141 , 142 and 143 describes the main steps of the method according to the invention.

[0098] The three transducers 141 , 142 and 143 in combination allow for spatial discrimination of the location of a detected metal object.

[0099] In fact, and as mentioned above, from Figure 4a , 4b The analysis of the evolution of the signal passing through the detection barrier 130 represented in 4c (allowing to define the position of the individual in the metal detector 100 and therefore the position of the individual relative to the transducer 140) combined with the analysis of the signal coming from the metal detection transducer 140 allows to detect a metal object carried by the individual and to locate the position of the three-dimensional point at which the object is located on the individual's body.

[0100] Arbitrarily, FIGS. 2 , 3 and 4 show a situation where a person carrying a metal object M1 in front of him, a metal object M4 on his back, and metal objects M2 and M3 on his left and right sides passes through the walk-through metal detector 100 according to the present invention.

[0101] exist Figure 3a In FIG. 1 , S1 , S2 , S3 , and S4 refer to four signal components from the receiving transducer 142 associated with the transmitting transducer 141 when the masses M1 , M2 , M3 , and M4 successively pass through the transverse detection line 141D.

[0102] exist Figure 3b In FIG. 1 , S10 , S20 , S30 , and S40 refer to four signal components from the receiving transducer 143 associated with the transmitting transducer 141 when the masses M1 , M2 , M3 , and M4 successively pass through the inclined detection line 143D.

[0103] With regard to Figures 2, 3 and 4, which are given by way of non-limiting example, it should be understood that:

[0104] When the individual reaches the barrier 132 and the lateral detection line 141D (corresponding to Figure 2c The combined detection of the signal S1 on the transducer 142 and the signal from the barrier 132 allows the detection of the presence of a metal object M1 placed in front of the individual,

[0105] When a person crosses the transverse detection line 141D connecting the transmitter 141 and the receiver 142 (corresponding to Figure 2d The metal detection achieved by the signals S2 and S3 from the transducer 142 allows the generation of an additional metal presence alarm, interpreted a priori as the presence of at least one metal object on at least one side of the individual,

[0106] When the individual leaves the barrier 132 (and therefore the individual's presence is no longer detected) and the lateral detection line 141D (corresponding to Figure 2g The detection of the signal S4 on the transducer 142 allows the detection of the presence of a metal object M4 placed on the back of the individual,

[0107] When the individual reaches the barrier 133 and the tilt detection line 143D (corresponding to Figure 2e The detection of the signal S10 on the transducer 143 and the signal from the barrier 133 allows the presence of the metal object M1 in front of the individual to be verified,

[0108] ·like Figure 2f As shown, when an individual passes the intersection of the barrier 133 and the inclined detection line 143D, the detection of the signal S20 on the same transducer 143 allows the detection of the presence of a metal object M2 located to the left of the individual,

[0109] ·like Figure 2h As shown, the detection of the signal S30 on the same transducer 143 allows the detection of the presence of a metal object M3 located to the right of the individual, while the individual is still passing the intersection of the obstacle 133 and the inclined detection line 143D, and

[0110] When the individual leaves the barrier 133 (and thus no longer detects the individual's presence) and the tilted detection line 143D (corresponding to Figure 2i Detection of signal S40 on transducer 143 when in the position shown allows verification of the presence of metal object M4 on the back of the individual.

[0111] The height positions of the objects M1 , M2 , M3 and M4 on the person are determined in a manner known per se according to conventional metal detection modes in known walk-through detectors, in particular by dividing the coils in height to define different detection areas in height.

[0112] The exemplary embodiment according to which the transducer 141 is a transmitting transducer and the transducers 142 and 143 placed on the opposite sides are receiving transducers has been described previously.

[0113] However, an opposite arrangement may be provided, ie, the receiving transducer 141 and the transmitting transducers 142 and 143 are placed on opposite sides.

[0114] The analysis of the signals from transducers 141 , 142 and 143 in conjunction with the analysis of the signals from passing through detection barriers 131 , 132 and 133 remains the same.

[0115] However, in this case, when the transducers 142 and 143 are respectively transmitting transducers, Figure 3a and 3b The signals shown correspond to the signals received at receiver 141. These signals are distinguishable by the specific frequencies of transmitters 142 and 143, respectively.

[0116] Preferably, each of the transducers 141 , 142 and 143 very preferably acts alternately and continuously as a transmitter and a receiver. A signal redundancy is thus obtained which allows verification and makes the detection more reliable.

[0117] Figure 3c and 3d Schematically represents the signals from the receiving transducers 142 and 143 under the assumption that the metal object completely surrounds a portion of the individual being examined, for example, around the waist of the individual. Figure 3c As shown, in this case, when Figure 2cAs the individual begins to cross the detection barrier 132 and the lateral detection line 141D, the metal object detection signal is activated once the detection barrier 132 generates a presence detection signal, and when the detection barrier 132 no longer detects the presence of the individual, i.e., as shown in FIG. Figure 2g As shown, when the individual has passed the barrier 132 and the transverse detection line 141D, the metal object detection signal ends. Figure 3d As shown, when an individual Figure 2e As shown in FIG. 1 , when the detection barrier 133 begins to cross the inclined detection line 143D, the metal object detection signal is activated as soon as the detection barrier 133 generates a presence detection signal. When the detection barrier 133 no longer detects the presence of the individual, that is, when the metal object detection signal is activated, the metal object detection signal is activated. Figure 2i When the person shown has passed the detection barrier 133 and the inclined detection line 143D, the metal object detection signal ends.

[0118] When the metal target is not formed by a continuous band wrapped around the individual, but by a series of discrete objects distributed around the individual, the signal from the receiving transducers 142 and 143 is formed by a series of pulses distributed in time between the beginning and end of the crossing of the detection barriers 132, 133 and the lateral detection line 141D and the inclined detection line 143D, in a manner similar to Figure 3a and 3b .

[0119] FIG. 5 shows another alternative, according to which the metal detector 100 comprises four transducers 141, 142, 143 and 144 forming two transmitters and two receivers, arranged in the form of two transducers located on a first side of the channel 102 and two transducers arranged on the opposite side of the channel 102, according to Figure 1b , respectively located in the side panels 110 and 120.

[0120] Remember that each of these transducers 141, 142, 143 and 144 can alternately form a transmitter and a receiver. When it constitutes a transmitter, it preferably cooperates with two receivers placed on opposite sides of the channel 102. When it constitutes a receiver, it preferably cooperates with two transmitters placed on opposite sides of the channel 102.

[0121] The four transducers 141, 142, 143 and 144 thus define four main detection areas or lines 141D, 144D, 143d and 142D, defined between the transducers 141 and 142, 144 and 143, 141 and 143, 144 and 142, respectively.

[0122] Preferably, the frequency of the signal emitted by a transmitter 140 and detected respectively on two associated receivers differs from receiver to receiver and likewise, the frequency of the signal emitted by two transmitters 140 and intended to be detected by a common receiver differs from transmitter to transmitter to allow identification of the relevant main detection areas or lines 141D, 142D, 143D or 144D.

[0123] Now, with respect to FIGS. 5, 6 and 7, the Figure 1b A metal detector of the type shown comprising four inductive transducers 141, 142, 143, 144 is used to describe the main steps of the method according to the invention, again arbitrarily, the figures showing a person carrying a metal object M1 on his front, M4 on his back and M2 and M3 on his left and right sides passing through a walk-through metal detector 100 according to the invention.

[0124] Figure 6a It represents the signals S1, S2, S3, S4 from the receiving transducer 142 when the facing transducer 141 is the transmitting transducer.

[0125] Figure 6b 1 and 2 represent signals S10, S20, S30, S40 from the receiving transducer 143 when the diagonal transducer 141 is the transmitting transducer.

[0126] Figure 6c 1 and 2 represent signals S11, S21, S31, S41 from the receiving transducer 142 when the diagonal transducer 144 is the transmitting transducer.

[0127] Figure 6d Represents signals S12, S22, S32, S42 from the receiving transducer 143 when the facing transducer 144 is a transmitting transducer.

[0128] Remember that according to the embodiment represented in FIG. 5 , four transducers 141 , 142 , 143 and 144 are associated with three consecutive passing detection barriers 131 , 132 and 133 along the path of movement in the metal detector 100 .

[0129] According to a specific and non-limiting embodiment shown in FIG. 5 , the entrance barrier 131 coincides with the lateral detection line 141D and the transducer pairs 141 and 142 , the exit barrier 133 coincides with the lateral detection line 144D and the transducer pairs 143 and 144 , and the intermediate barrier 132 coincides with the intersection between the two inclined detection lines 143D and 144D.

[0130] The pass detection barrier 130 may again be formed by any known technique, such as but not limited to an optical barrier.

[0131] In practice, each through detection barrier may include a transmitter 131.1, 132.1, 133.1 placed in one of the panels 110 or 120 and an opposite receiver 131.2, 132.2, 133.2 placed in the opposite panel 120 or 110 in a manner similar to FIG. 2. As long as there is no obstacle between the receiver and the transmitter, the receiver will receive the signal from the oppositely placed transmitter. On the other hand, when an individual stands between the transmitter and the receiver, the receiver will not receive the signal from the opposite transmitter.

[0132] When a person passes through channel 102, the corresponding signals received at receivers 131.2, 132.2, 133.2 are Figure 7a , 7b and 7c.

[0133] From these Figure 7a , 7b As can be seen from Figure 7c, when a person passes through channel 102, the outlets of receivers 131.2, 132.2, and 133.2 continuously change state in positive logic or negative logic.

[0134] The relative positioning between the through detection barriers 131 , 132 and 133 and the metal detection transducer 140 may be the subject of different embodiments and is not limited to the arrangement shown in FIG. 5 .

[0135] In particular, with respect to Figures 5, 6 and 7, which are given by way of non-limiting examples, it should be understood that:

[0136] · can be detected by passing through detection barriers 131 and 133 (combined signals S1, S10, S11 and S12), and as Figure 5d As shown, when the individual reaches the intersection of the detection lines 142D and 143D and the central through barrier 132, the metal object M1 carried by the front of the individual's body is detected, and the signals of the detection barriers 131 and 133 allow the central unit 50 to determine that the individual has arrived and started to cross the detection lines 141D and 144D formed between the transducer pairs 141 and 142 and the transducer pairs 143 and 144, respectively (these positions are Figure 5a and 5f and also corresponds to passing through channel barriers 131 and 133),

[0137] When a person crosses a first inclined detection line 143D defined between transducers 141 and 143 (a position between Figure 5d ), or when a person crosses a second inclined detection line 142D defined between transducers 142 and 144 (a position in Figure 5e ), detecting the metal object M2 located on the left side of the individual (signals S20, S21). Figure 5b and5g As shown in FIG. 1 , when the person passes through the transverse detection lines 141D and 144D that coincide with the obstacles 131 and 133, the metal object M2 located on the left side of the person can also be detected (signals S2, S22).

[0138] When a person crosses a first detection line 142D defined between transducers 142 and 144 (this position is also Figure 5d ) or when a person crosses a second inclined detection line 143D defined between transducers 141 and 143 (the position is Figure 5e ), the metal object M3 located on the right side of the individual can be detected (signals S30, S31); Figure 5b and 5g When the object crosses the transverse detection lines 141D and 144D, the object M3 located on the right side of the individual can also be detected (signals S3, S32), and

[0139] · Can be detected by passing through detection barriers 131 and 133 (combined signals S4, S42) and when the individual reaches the detection line 142D and 143D and the central channel barrier 132 ( Figure 5e ), detecting the metal object M4 carried on the back of the individual's body, and by detecting the signals of the barriers 131 and 133, allowing the central unit 50 to determine that the individual has left the detection lines 141D and 144D formed respectively between the transducer pairs 141 and 142 and the transducer pairs 143 and 144 (these positions also correspond to Figure 5c and 5h 1 and 133).

[0140] 2 , the height positions of the objects M1 , M2 , M3 and M4 on the person are determined in a manner known per se according to conventional metal detection modes in known walk-through detectors, specifically by dividing the coils in height to define different detection areas in height.

[0141] Figure 6e , 6f , 6g and 6h schematically represent signals from receiving transducers 142, 143 when transducers 141 and 144 are continuous transmitting transducers, assuming that the metal object completely surrounds a portion of the individual being examined, for example, around the waist of the individual. Figures 6e to 6h As seen in FIG. 1 , in this case, transducers 142 and 143 initiate a metal object detection signal when the individual begins to cross the corresponding detection line and terminate the detection signal when the individual has passed the corresponding detection line.

[0142] When the metal target is not formed by a continuous band wrapped around the individual, but by a series of discrete objects distributed around the individual, the signal from the receiving transducers 142 and 143 is formed by a series of pulses distributed in time between the beginning and end of the crossing of the detection barrier and the lateral detection lines 141D, 144D and the inclined detection lines 142D, 143D, in a manner similar to Figure 6a , 6b , 6c and 6d.

[0143] It will be understood from reading the above description that the device according to the present invention combines a metal detector 100 comprising at least three detection transducers 140, 141, 142 and 143 or 144, and detection barriers 130, 131, 132 and 133, which allows searching for coincidence between the signal from the metal detector 100 formed by the transducer 140 and the signal from passing through the detection barrier 130, or interpreting the signal from the transducer 140 based on the signal from passing through the detection barrier 130, thereby allowing locating the individual in the channel 102 and identifying the position of the detected metal object, which position is on the one hand in the width direction of the channel transverse to the direction of movement, usually on the left or right side of the individual, and on the other hand in the depth direction longitudinally parallel to the direction of movement, usually in front of or behind the individual.

[0144] As mentioned above, the present invention also relates to a method for detecting hidden items carried by an individual using the above-mentioned device including the advanced metal detector 100. The method specifically includes the step of detecting the metal object carried by the individual by using the metal detector 100 to locate the three-dimensional spatial position of the detected metal object on the individual.

[0145] Figure 8 A non-limiting example of implementation of the detection method according to the invention is illustrated.

[0146] Figure 8 A flow chart is shown comprising the following steps:

[0147] an initial step 200 of using the signal from passing through the detection barrier 130 and determining the position of the individual relative to the metal detection transducer 140,

[0148] step 202 of using the signal from the metal detection transducer 140,

[0149] A step 204 of searching for crossing of the transverse detection lines 141D, 144D,

[0150] If yes, find out whether the crossing corresponds to step 206 with metal detection reaching the lateral detection line,

[0151] If yes, a step 208 of verifying the detection of the metal object M1 in front of the person,

[0152] In the event of a negative response to step 206, a step 210 of searching for an individual located at the center of the transverse detection line is followed by metal detection,

[0153] If yes, a step 212 of verifying the detection of the metal objects M2 and / or M3 to the left or right of the individual,

[0154] In case of a negative response to step 210, a step 214 of finding out whether the crossing corresponds to a crossing of a transverse detection line accompanying the start or end of metal detection,

[0155] If yes, a step 216 of verifying the detection of the metal object M4 on the back of the person,

[0156] In case of a negative response to step 204 or 214, a step 218 of searching for a line crossing the tilt detection line 142D, 143D,

[0157] If yes, find out whether the crossing corresponds to a step 220 of the individual accompanying the metal detecting crossing the inclined detection line to the left,

[0158] If yes, a step 222 of verifying the detection of the metal object M2 to the left of the person,

[0159] In case of a negative response to step 220, a step 224 of searching for an individual who has reached the intersection between the two inclined detection lines is followed by a metal detection search,

[0160] If yes, a step 226 of verifying the detection of the metal object M1 in front of the person,

[0161] In case of a negative response to step 224, a step 228 of finding out whether the crossing corresponds to a right crossing of the inclined detection line by the individual accompanying the metal detection,

[0162] If yes, a step 230 of verifying the detection of the metal object M3 to the right of the person,

[0163] In case of a negative response to step 228, a step 232 of searching for an individual leaving the intersection between the two inclined detection lines is followed by a metal detection,

[0164] If yes, a step 234 of verifying the detection of the metal object M4 on the back of the person, and

[0165] If a negative response occurs at the end of steps 218 and 232, the loop returns to step 204.

[0166] Depending on the selected transducer configuration, Figure 8 Not all steps shown may be implemented.

[0167] In addition, you can modify Figure 8 The order and timing of the steps shown in .

[0168] The method according to the present invention may further include the following steps: when the analysis determines that the superimposed signature is the superimposed feature Sx of the metal object identified in step Tx including the signature Sn, the signature Sn of at least one metal object previously clearly identified is removed from the superimposed signature Sx of the metal object identified in step Tx so as to facilitate the individual identification of the signature of each metal object.

[0169] As mentioned above, the present invention also relates to a specific application of the above-mentioned metal detector 100, according to which the metal detector forming an inductive field type detection device is integrated into a human body scanner 10 forming a microwave field imaging type detection device.

[0170] Therefore, the attached Fig. 9 A device according to the invention is shown, comprising a body scanner 10 with an integrated metal detector 100 .

[0171] The body scanner 10 may be the subject of any known embodiment and will therefore not be described below.

[0172] The body scanner 10 operates primarily by measuring microwave energy reflected and / or absorbed based on the properties of the material being inspected, particularly based on dielectric properties and magnetic permeability.

[0173] As a non-limiting example, the body scanner 10 may comply with the provisions described in document EP 2 202 700 .

[0174] The metal detector 100 is preferably placed at the entrance of the body scanner 10. It defines a passage or channel 102 that any individual must pass through to reach the body scanner 10.

[0175] The manner in which the metal detector 100 is integrated into the body scanner 10 may be the subject of different alternatives.

[0176] Fig.10a Indicates that Figure 1a A metal detector 100 of the type shown, comprising three cylindrical transducers 141 , 142 and 143 , is located upstream of a body scanner 10 comprising a transmitter 12 and a receiver 14 respectively arranged in opposite panels constituting the outer frame of an examination room of the body scanner 10 .

[0177] Fig.10b Indicates that Figure 1bA metal detector 100 of the type shown, having four cylindrical transducers 141, 142, 143 and 144, is located upstream of a body scanner 10 comprising a transmitter 12 and a receiver 14, respectively arranged in opposite panels constituting the outer frame of an examination room of the body scanner 10.

[0178] Fig.10c Indicates that Figure 1b A metal detector 100 of the type shown in c, which has three or four panel-type transducers 141, 142, 143 and 144, is located upstream of a body scanner 10, which includes a transmitter 12 and a receiver 14 respectively arranged in opposite panels of an outer frame of an inspection room constituting the body scanner 10.

[0179] Fig.10d represents an alternative embodiment of the invention, according to which the metal detector 100 is not arranged upstream of the body scanner 10, but is co-located with the body scanner 10, that is, it is integrated into the panels of the body scanner 10, which panels house the transmitter 12 and the receiver 14 and constitute the outer frame of the examination room of the body scanner 10. The metal detector 100 integrated into the panel of the body scanner 10 can thus meet Figures 1a to 1c Any of the alternatives shown, that is, may include three or four cylindrical or panel-type transducers.

[0180] Fig.10e 1 represents an alternative embodiment of the present invention, according to which a first metal detector 100 is arranged upstream of the body scanner 10, and a second metal detector 100b is arranged co-located with the body scanner 10, that is, the second metal detector is integrated into the panels of the body scanner 10, which panels house the transmitter 12 and the receiver 14 and constitute the outer frame of the examination room of the body scanner 10. The metal detector 100 arranged upstream of the body scanner 10 may conform to Figures 1a to 1c , that is, it may include three or four columnar or panel-type transducers. Alternatively, it may include only two transducers 140 disposed on either side of the channel 102, respectively, to detect the presence of metal objects. The metal detector 100b integrated into the panel of the body scanner 10 may conform to Figures 1a to 1c Any of the alternatives shown in , that is, may include three or four cylindrical or panel type transducers.

[0181] according to Fig.10eAn embodiment represented by the invention (according to which a metal detection device 140 capable of performing 3D detection is co-located with the body scanner 10, but an additional metal detection device 100 capable of performing 1D detection upstream of the body scanner 10 is also provided) provides the following advantages: with this configuration, it is possible to use an inductive upstream 1D metal detector (which is optimized for distinguishing the presence or absence of metal objects and correspondingly controlling the sensitivity of the body scanner 10 to maintain a minimum number of nuisance alarms) and a 3D metal detector co-located with the inductive body scanner 10 (which is optimized for locating metal objects, thereby achieving maximum accuracy in locating metal objects).

[0182] As previously indicated within the scope of the present invention, preferably the results of the inductive analysis aimed at searching for metal objects and the results of the microwave-based imaging analysis are displayed on a single screen available to the operator.

[0183] According to a particular embodiment of the invention, in the case of sensing field detection of one or more targets, in the area where the sensing system 100 has determined the presence of a metal target, the sensitivity of the microwave imaging system 10 is preselected at the "metal and dielectric" level; while in other areas, the sensitivity of the microwave imaging system 10 is preselected at the "dielectric" level. In the case of using a 1D sensing system, the above-mentioned areas are defined only in height, while in the case of using a 3D sensing system, these areas are defined in height, width and depth.

[0184] As mentioned in the foregoing, the present invention also relates to a method for detecting hidden items carried by an individual using the above-mentioned device comprising a body scanner 10 and a metal detector 100 integrated into the body scanner 10 in combination. 10. The method specifically comprises the following steps: detecting a metal object carried by an individual by locating the three-dimensional spatial position of the detected metal object on the individual using the metal detector 100, and controlling the body scanner 10 by adjusting the sensitivity of the body scanner 10 at least in the area of ​​interest when the metal detector detects the presence of the metal object.

[0185] Thus, the present invention allows focusing the region of interest analyzed by the body scanner 10 on a region containing metal objects M1 , M2 , M3 and / or M4 detected by the metal detector 100 by concentrating the analysis performed by the body scanner 10 on that region of interest.

[0186] More specifically, within the scope of the present invention, the sensitivity of the human body scanner 10 forming a microwave-based imaging analysis device is set to a high level when the inductive detection device detects the possible presence of a metal target at least in the area of ​​interest identified by the metal detector, and conversely, when the inductive detection device does not detect the possible presence of a metal target, the sensitivity is set to a lower level.

[0187] Therefore, within the scope of the present invention, if the inductive analysis device formed by the metal detector 100 does not detect the possible presence of a metal object, the sensitivity of the microwave-based imaging analysis device formed by the body scanner 10 can be kept relatively low, at a level sufficient to detect non-metallic objects.

[0188] The usual high false alarm rates (typically in the order of 65% to 85%) caused by the use of microwave imaging-based analysis devices are limited according to the invention to cases where metal objects are previously detected by the associated inductive metal detector (these cases are themselves about 10%), so that the overall false alarm rate caused by the body scanner according to the invention is relatively low. For the remaining 90% of people on whom no metal objects are detected by the metal detection device, the body scanner is indeed at a low sensitivity level. Therefore, the overall false alarm rate caused by the body scanner according to the invention typically falls within the range of between 10% and 20%.

[0189] Those skilled in the art will appreciate that controlling the sensitivity of these microwave-based imaging analysis devices forming a body scanner by increasing the sensitivity of these microwave-based imaging analysis devices only when the metal detection device pre-detects a metal object allows the overall false alarm rate of the system to be significantly reduced.

[0190] Statistically, considering the standard of detecting metal type induction alarms occurring in less than 10% of the examined population, at least 90% of the examined individuals will be checked only for dielectric type (non-metallic) targets by the microwave-based body scanner with the aid of the reduced sensitivity microwave field, thereby greatly reducing the overall false alarm rate.

[0191] Fig.11 A flow chart showing the main steps of the detection method according to the present invention is shown, which implements a metal detector 100 integrated into a body scanner 10, specifically comprising the following consecutive steps:

[0192] - Step 300: Start checking the person. At this stage, according to the present invention, the individual being checked is invited to enter the body scanner, pass through the metal detector 100,

[0193] - Step 310: The individual begins to pass through the induction field generated by the metal detector 100, more specifically the induction field generated by the coil 140. During this step, the individual being inspected passes / stops, passing through the induction field inspection area (remember, as mentioned above, the inspection area based on the induction field is strictly speaking like Fig. 9 and Figures 10a to 10c As shown, it is located upstream of the body scanner 10, or as shown Fig.10d and 10e The area shown covers the human body scanner 10),

[0194] - Step 311: Acquiring a signal corresponding to the induction field,

[0195] - Step 320: Analyzing the signal from the metal detector 100 to find out if a metal target has been detected.

[0196] - Step 330 implemented in the case of a negative response to the target detection step 320: the central unit of the system positions the sensitivity of the microwave imaging 10 at a low "dielectric" sensitivity level. The modification of the sensitivity of the microwave imaging 10 is carried out by the central unit modifying the microwave image processing parameters, with the aim of determining, based on the signal generated by the metal detector 100, whether an instruction to generate an alarm (acoustic and / or optical alarm) must be sent by the analysis device 50 to the appropriate alarm device. In the present case, since the metal detector 100 does not detect a metal target, the central unit modifies the microwave image processing parameters so as to perform the analysis at the body scanner 10 based on the imaging sensitivity in the microwave inspection field, which corresponds to the level required for detecting dielectric targets, i.e. a sensitivity lower than that required for detecting metal targets. This configuration allows limiting the risk of false alarms.

[0197] - Step 340 implemented in the case of a positive response to step 320: the central unit positions the sensitivity of the microwave imaging 10 at a higher "metal and dielectric" sensitivity level this time. Again, the sensitivity of the microwave imaging 10 is modified by the central unit 50 modifying the microwave image processing parameters. In particular, this modification of the sensitivity allows the simultaneous detection of metal targets and dielectric targets. Although more stringent and may produce a certain degree of false alarms, this arrangement is required because the metal detector 100 has detected the possible presence of upstream metal (this situation only occurs in 10% of the cases, although it essentially leads to a high risk of false alarms, but does not cause a large amount of false alarms).

[0198] - Step 342: Acquisition of signals from detection devices in the microwave field 10. During this step, the individual under examination is scanned by the microwave examination field 10. The relevant data from the detection devices are collected and analyzed.

[0199] - Step 360: During this step, the central unit analyses the signals coming from the microwave detection means 10 and finds out whether they correspond to the position of the target. To this end, according to the response to step 320, the analysis means 50 carry out a processing of the microwave image, taking into account the sensitivity of the microwave imaging determined in step 330 or step 340.

[0200] It should be understood that, in an alternative solution, the step 340 of modifying the sensitivity may alternatively be performed simultaneously with the step 342 of acquiring or after the step 342 of acquiring, the modification of the sensitivity corresponding to the modification of the microwave image processing parameters.

[0201] - Step 380, implemented in the event of a positive response to step 360: indicating an alarm and displaying the location of the target on the microwave image generated by the central unit 50. The operator can generally see an alarm display on a screen that displays the location of the detected target. It will be observed that step 380 is omitted on the assumption that no target has been detected in step 360.

[0202] - Step 390: End the inspection of the individual.

[0203] In one embodiment, during step 340, the central unit 50 may be configured to modify the sensitivity of the microwave imaging only in the microwave image region where the metal detector 100 has detected a metal target, while the sensitivity remains unchanged in other regions of the microwave image. In other words, the central unit 50 modifies the sensitivity only in a portion of the microwave image obtained from the signal from the microwave detection device 10, the portion corresponding to the region where the metal detector has detected a metal target.

[0204] In FIG. 10 , please note the presence of floor markings 20, 22, which are located substantially in the center of the space forming the body scanner 10. These markings 20, 22 preferably correspond to the contours of the sole imprint. These markings 20, 22 are used to place the feet of the individual during the inspection of the individual by the body scanner 10. These markings 20, 22 allow to ensure the precise positioning of the individual under inspection relative to the microwave transmitting / receiving device 12 and the microwave receiving / transmitting device 14, which are placed opposite each other (respectively located on both sides of the channel thus formed in the body scanner 10, in the extension of the upstream channel 102 formed by the metal detector 100).

[0205] Although this is not shown in the accompanying drawings, the metal detector 100 can also be set on the ground and provided with a center line or equivalent device for defining the preferred path of an individual as he moves in the metal detector 100 to ensure accurate positioning of the individual relative to the side panels 110, 120 and therefore relative to the detection device 140.

[0206] The body scanner 10 can be a walk-through scanner. In this case, after being checked by the body scanner 10, the individual being checked leaves the body scanner 10 through an end opposite to the entrance into the metal detector 100.

[0207] The body scanner 10 may also be closed at one end thereof opposite to the entrance in the metal detector 100. In this case, after being checked by the body scanner 10, the checked individual leaves the body scanner 10 by passing through the metal detector 100 again.

[0208] Of course, the present invention is not limited to the above-described embodiments, but extends to any alternatives according to the spirit thereof.

[0209] As described above, the passage detection barrier 130 may be formed by any technology other than optical technology.

[0210] For example, at least one correctly placed camera can be used to detect the movement of an individual and his position in the passage 102, thereby allowing, for example, by pixel analysis, the detection of an individual's successive passage through a plurality of virtual barriers corresponding to the positions of the barriers described in the previous description.

[0211] Likewise, according to the invention, the metal detector 100 placed upstream of the body scanner 10 can be equipped with a Doppler type system or the same allowing the position and movement of individuals in the passage 102 to be known.

[0212] The system according to the invention comprises a central unit which analyses the signals coming from the passage of the detection barrier 130 on the one hand and the signals coming from the transducers 140 on the other hand.

[0213] The central unit uses the signal from passing through the detection barrier 130 to define the position of the individual in the metal detector 100 and relative to the transducer 140. Knowing the position of the individual relative to the transducer 140, the central unit can determine in which part of the body the metal object is placed when the transducer 140 detects the metal object.

[0214] It should be noted that within the scope of the present invention, the arrangement of transducers 141, 142, 143, 144 and their cooperation defined by controlling the configuration of these transducers in a transmitting mode or a receiving mode, respectively, produces main detection lines between two transmitting transducers and a receiving transducer, some of which are transverse to the direction of movement in the metal detector 100, while others are inclined or diagonally inclined relative to this direction of movement in the metal detector 100.

[0215] In addition, by reading the preceding description and examining the accompanying drawings, it will be understood that the lateral detection lines allow for the detection of metal objects carried primarily by an individual on the front and back of his or her body, in which case the front and back of the individual's body first reach and last leave these lines, respectively, while the inclined detection lines allow for the detection of metal objects carried primarily by an individual on his or her left or right side, in which case the side of the individual continuously crosses these lines.

[0216] The combination of the metal detector 100 and the body scanner 10 according to the invention in particular allows ensuring reliable detection of metal objects on the entire body of a person including at foot level, by means of a focused analysis of the body scanner 10 resulting from a first search by the metal detector 100 .

[0217] The implantation of the metal detecting transducers 141 , 142 , 143 and 144 may be the subject of many embodiments.

[0218] As mentioned above, the detectors located on the same side of the channel 102, ie detectors 141 and 144 on the one hand and detectors 142 and 143 on the other hand, are preferably located in the side plates 110, 120, respectively. They can be placed on a common side support or on corresponding supports.

[0219] Alternatively, the detectors 141, 144 and 142, 143 may be placed in corresponding columns.

[0220] In effect, the operator can see on a single screen the results of the inductive analysis designed to find metal objects and a display of the imaging produced by the microwave-based analysis.

Claims

1. A system for detecting prohibited items carried by an individual, comprising a metal detector (100), wherein the metal detector comprises: - two panels (110, 120) defining a channel, - at least three transducers (141, 142, 143, 144) housed in said panels (110, 120) and arranged on both sides of said channel (102), two of these transducers (142, 143) being placed in a first of said panels (110) and spaced longitudinally along the direction of movement in said channel (102), while a third transducer (141, 144) is arranged in a second of said panels (120) on the opposite side of said channel (102), so that said at least three transducers (141, 142, 143, 144) allow in combination a spatial discrimination of the position of at least one detected metal object (M1, M2, M3, M4), - three passage detection barriers (131, 132, 133) configured to generate a detection signal when an individual passes through the metal detector (100), wherein the three passage detection barriers are longitudinally distributed along the passage (102) in the metal detector (100) and are associated with the transducers (141, 142, 143, 144) to determine the position of the individual in the passage (102) relative to the transducers (141, 142, 143, 144), and - A central unit (50) configured to analyse and use the signals from the passing detection barrier (131, 132, 133) and the signals from the at least three transducers (141, 142, 143, 144) in the metal detector (100) to determine the position of the individual in the metal detector (100) relative to the transducers (141, 142, 143, 144) and to infer therefrom the position of the detected metal object (M1, M2, M3, M4) relative to the body of the individual when at least one transducer (141, 142, 143, 144) generates a signal for detecting a metal object.

2. A system according to claim 1, wherein the at least three transducers (141, 142, 143, 144) include the following elements: one transmitter and two receivers; two transmitters and one receiver; two transmitters and two receivers; the transducers (141, 142, 143, 144) are suitable for operating alternately as transmitters and receivers.

3. According to the system of claim 1, the central unit (50) is configured to, on the one hand, identify the position of the detected metal object (M1, M2, M3, M4) in the width direction of the channel (102), wherein the width direction is transverse to the moving direction, and on the other hand, identify the position of the detected metal object (M1, M2, M3, M4) in the depth direction, wherein the depth direction is parallel to the moving direction.

4. The system according to claim 1, wherein each transducer (141, 142, 143, 144) is formed by at least one coil.

5. The system of claim 1, wherein the passage detection barrier (131, 132, 133) comprises an optical barrier.

6. The system according to claim 1, wherein the passing detection barrier (131, 132, 133) comprises: Detectors are positioned in panels (110, 120) that frame the channel (102).

7. The system of claim 1, wherein at least one through-detection barrier (131, 132, 133) is longitudinally coincident with the transducer pair (141, 142).

8. The system according to claim 1, wherein at least one through detection barrier (131, 132, 133) coincides longitudinally with the center of the inclined detection line connecting two transducers (141, 143), respectively.

9. The system of claim 1, wherein the transducers (141, 142, 143, 144) cooperate in groups of three.

10. The system of claim 9, wherein in each group of three transducers, one transducer functions as a transmitter or a receiver, while the other two transducers perform complementary receiving or transmitting functions.

11. A system according to claim 1, wherein the transducer pairs (141, 142) are arranged opposite to each other on both sides of the channel (102), respectively in the panels (110, 120), and are at the same longitudinal level in the passing direction in the channel (102), at least one transducer is offset downstream relative to the above-mentioned transducer pair (141, 142) with reference to the passing direction in the channel (102), and at least one through-detection barrier (132) is at the same longitudinal level as the transducer pair (141, 142).

12. The system according to claim 1 comprises four transducers (141, 142, 143, 144) associated with successive passing detection barriers (131, 132, 133) along a moving path in the metal detector (100), one passing detection barrier (132) being located at a transducer pair (141, 142), and another passing detection barrier being located at an intersection between two inclined detection lines respectively connecting the paired transducers (141, 142, 143, 144).

13. The system of claim 1, wherein the at least three transducers are positioned to define two privileged detection lines between each pair of transducers disposed on opposite sides of the channel, having an angle between 15° and 60°.

14. The system according to claim 1 further includes a human body scanner (10), the human body scanner (10) including a microwave imaging detection device configured to generate a microwave image, and the metal detector (100) is located upstream of the human body scanner (10) relative to the moving direction.

15. A system according to claim 14, wherein the central unit (50) is configured to adjust the sensitivity of the microwave imaging detection device when the metal detector (100) identifies the possible presence of at least one metal object, and determine the position of the detected metal object (M1, M2, M3, M4) relative to the individual's body, so that the sensitivity in one or more regions of interest corresponding to the position of the at least one metal object is greater than the rest of the microwave image.

16. A method for detecting a metal object (M1, M2, M3, M4) carried by an individual, comprising the following steps: - S1: detecting (204, 220, 228) at least one metal object (M1, M2, M3, M4) carried by a person passing through the system according to any one of claims 1 to 15 and generating a metal detection signal, - S2: Detecting that a person passes through the metal detector (100) and generating a passing detection signal, - S3: Analyze and use the through detection signal and the metal detection signal, - S4: determining the position of the individual in the metal detector (100) relative to the transducers (141, 142, 143, 144) of the metal detector when generating the metal detection signal, - S5: Inferring (208, 212, 216, 222, 226, 230, 234) the position of the detected metal object (M1, M2, M3, M4) relative to the body of the individual.

17. The method according to claim 16, further comprising the steps of: -S6: Probe through a body scanner to produce microwave images, and - S7: After step S5, adjusting the detection sensitivity of the human body scanner so that the sensitivity in one or more regions of interest corresponding to the position of the metal object is greater than the rest of the microwave image.

Images