WO2017016000A1

WO2017016000A1 - Metal sensor

Info

Publication number: WO2017016000A1
Application number: PCT/CN2015/087330
Authority: WO
Inventors: 蒋洪洲
Original assignee: 金华马卡科技有限公司
Priority date: 2015-07-29
Filing date: 2015-08-18
Publication date: 2017-02-02
Also published as: CN105182427B; CN105182427A

Abstract

A metal sensor, having at least one transmission coil (100) and at least one receiving coil system (200) inductively coupled to each other, wherein the receiving coil system (200) comprises at least one first receiving coil (201) and at least one second receiving coil (202) which are located in a same plane, the transmission coil (100) forms a projection on the plane, an area formed by the first receiving coil (201) on the plane contains the projection, and an area formed by the second receiving coil (202) on the plane is arranged around the projection. The receiving coils (201, 202) are arranged to have the same winding direction therebetween, and induced voltages of a second magnetic field (700), generated by a target metal object, on the receiving coils (201, 202) are superimposed with one another. The sensitivity to a target object can be improved, and a measurement blind zone is not formed, which significantly improves the measurement accuracy.

Description

Metal sensor

Technical field

The invention relates to the field of detection and positioning, and in particular to a metal sensor.

Background technique

Metal detectors are mainly used to locate metal objects. Existing detectors are divided into many categories and operate through a variety of principles. For example, the main component is a sensor, the sensor is formed by a coil, and the transmitting coil is used to emit a continuous alternating field. The alternating field is received by the receiving coil. The receiving coil is arranged such that it is not When the object to be tested has an influence, the induced voltages on the receiving coil cancel each other out, so that the induced voltage output is close to zero. If the object to be measured has an influence, the object to be measured changes the original alternating field, and To be precise, the object to be measured produces another alternating field, which is transmitted to the receiving coil and generates an induced voltage on the receiving coil, which is amplified and analyzed accordingly.

1 is a schematic structural view of a sensor in the prior art, the geometry of which is: a receiving coil system consisting of two sets of inverted first receiving wire loop 1 and second receiving wire loop 2, first receiving wire loop 1 and The two receiving wire loops 2 are arranged coaxially to one another in a common plane 3, the transmitter coil 4 being situated at a distance z above the common receiver plane 3, the transmitter coil also being identical to the first receiving wire loop 1 and The two receiving wire loops 2 are arranged coaxially. The windings of the first receiving wire loop 1 are here, for example, arranged to be wound clockwise, and the windings of the second receiving wire loop 2 are wound in a counterclockwise direction, so that the voltages induced in these windings have opposite signs and After appropriately sizing, it is possible to compensate each other without outputting an induced voltage in the absence of an external target. The object positioned by the sensor has the following defects: (1) because the transmitting coil generates a large alternating field, and the measured object passes the sense The reverse field that should be generated is extremely small, so when detecting the alternating field generated by the extremely weak object, the receiving coil must ignore the alternating field generated by the huge transmitting coil, so that the receiving coil and the transmitting coil do not exist. Inductive coupling, in the coil layout of the prior art, the first receiving wire loop 1 and the second receiving wire loop 2 must be reversed, so that the alternating field generated by the target must be cancelled, and the sensitivity of the detecting is reduced. When the target is at a specific position, the induced voltage of the second magnetic field in the receiving coil is completely canceled, so that a dead zone of measurement is formed, and the target is not detected, but the target actually exists, that is, There is a blind spot or the most extremely low sensitivity area; (2) Since the second coil of the first coil is coaxial with different radii, changing the magnetic flux is mainly achieved by changing the area. In order to reach a larger range of compensation, the radius of the two coils The difference can not be too small, can only be achieved by increasing the size of the board, which inevitably occupies board space.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, and provides a metal sensor in which the receiving coils are arranged with the same winding direction, and the second magnetic field generated for the target metal object is superimposed on the receiving coil to generate an induced voltage. Sensitivity to the target, and does not form a blind spot of measurement, greatly improving the accuracy of the measurement.

In order to solve the above technical problems, the present invention is solved by the following technical solutions:

A metal sensor having at least one transmitting coil and at least one receiving coil system inductively coupled to each other, the receiving coil system including at least one first receiving coil and at least one second receiving coil in a same plane, the transmitting coil being a projection is formed on the plane, an area formed by the first receiving coil on the plane includes the projection, and an area formed by the second receiving coil on the plane is disposed around the projection, The first receiving coil and the second receiving coil are electrically connected.

Preferably, the area formed by the first receiving coil on the plane all includes the cast Shadow.

Preferably, the portion of the region formed by the first receiving coil on the plane contains the projection.

Preferably, the second receiving coil has a region formed on the plane, and the region is surrounded by an opening around the projection.

Preferably, the second receiving coil has at least two regions formed on the plane, and the regions are sequentially distributed around the projection.

Further, one output stage is respectively disposed on the connection line of the first receiving coil and/or the second receiving coil and/or the first and second receiving coils.

Further, the first receiving coil is provided with at least two output stages, and the second receiving coil is provided with at least two output stages.

Further, the switching device is included, and the output stages on the first receiving coil and the second receiving coil are respectively connected to the switching device.

Further, the switching device is a Mos tube or a tertiary tube.

Further, an analysis circuit is included, and an output stage of the receiving coil system is connected to the analysis circuit through a switching device.

Further, an analysis circuit is included, and an output stage of the receiving coil system is connected to the analysis circuit.

Further, the analysis circuit includes an operational amplifier and a processor.

Further, the transmitting coil is embedded in a printed circuit board.

A measuring device comprising the sensor described above.

Further, the measuring device is a handheld positioning device.

The present invention achieves the following beneficial effects:

The second magnetic field generated by the target is superimposed by the coils in the same direction, so that the induced electromotive force generated by the coils is superimposed on each other, thereby enhancing the sensitivity of the receiving coil to the magnetic field induction of the target, and Forming the blind zone of the measurement greatly improves the accuracy of the measurement; at the same time, the first receiving coil and the second receiving coil are arranged on the circuit board, and the precision of the position is very high for the external winding receiving coil, which can be 0.1 mm at present The above greatly improves the consistency of the product, and can better offset the induced voltage generated by the first magnetic field, and the cost can be reduced by being arranged on the circuit board.

The additional aspects and advantages of the invention will be set forth in part in the description which follows.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

1 is a schematic structural view of a prior art metal sensor;

2 is a schematic structural view of a first embodiment of a metal sensor according to the present invention;

3 is a schematic structural view of a second embodiment of a metal sensor according to the present invention;

4 is a schematic diagram showing the connection of a receiving coil system corresponding to a metal sensor according to an embodiment of the present invention;

5 is a schematic diagram showing the connection of a receiving coil system corresponding to the second embodiment of the metal sensor of the present invention;

6 is a schematic structural diagram of a geometrical structure corresponding to a metal sensor according to the present invention;

7 is a schematic structural diagram of a geometrical structure corresponding to a metal sensor according to a second embodiment of the present invention;

8 is a schematic diagram of detection of a metal sensor according to a first embodiment of the present invention;

9 is a schematic diagram of detection of a second embodiment of a metal sensor according to the present invention;

Figure 10 is a vector diagram of the analysis method of the present invention;

Figure 11 is a measurement curve of a detection signal of the detection method of the present invention.

detailed description

The technical solutions of the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings. It is apparent that the described embodiments are part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the described embodiments of the present invention without departing from the scope of the invention are within the scope of the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" The orientation or positional relationship of the instructions is based on the orientation or positional relationship shown in the drawings, and is merely for the convenience of the description of the present invention and the simplified description, rather than indicating or implying that the device or component referred to has a specific orientation, The orientation and construction of the orientation are not to be construed as limiting the invention.

In the present invention, the terms "installation", "connected", "connected", "fixed" and the like shall be understood broadly, and may be either a fixed connection or a detachable connection, unless explicitly stated and defined otherwise. , or connected integrally; may be mechanical connection or electrical connection; may be directly connected, or may be indirectly connected through an intermediate medium, and may be internal communication between the two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In the present invention, the first feature "on" or "under" the second feature may include direct contact of the first and second features, and may also include first and second features, unless otherwise specifically defined and defined. It is not in direct contact but through additional features between them. Moreover, the first feature "above", "above" and "above" the second feature includes the first feature directly above and above the second feature, or merely indicating that the first feature level is higher than the second feature. The first feature "below", "below" and "below" the second feature includes the first feature directly below and below the second feature, or simply The first feature level is less than the second feature.

Unless otherwise defined, technical terms or scientific terms used herein shall be taken to mean the ordinary meaning of the ordinary skill in the art to which the invention pertains. The words "first", "second" and similar terms used in the specification and claims of the present invention do not denote any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the words "a" or "an" and the like do not denote a quantity limitation, but mean that there is at least one.

It is a known fact for all those skilled in the art that the term "field line" should not be understood literally, since to some extent the "field line" only more simply represents the same magnetic strength and pole. Sexual area. For this reason, in the following description of the invention, this term will be used to denote the magnetic density. For better description, only one winding is used to represent the coil. It will be readily understood that the present invention is considered to have its starting coil having a plurality of windings, or the coils being "printed" on the board. The alternating signal can operate in the coil; the field lines are represented during the course of a single clock phase.

As an embodiment of the invention, as shown in Fig. 2, a greatly simplified schematic diagram shows a first embodiment of the sensor geometry of the sensor of the invention for positioning a metal object. A metal sensor having a transmitting coil 100 and a receiving coil system 200 inductively coupled to each other. This embodiment is described by taking one transmitting coil 100 and one receiving coil system 200 as an example, but the sensor of the present invention is not limited to one. The receiving coil system 200 of the present invention includes a first receiving coil 201 and a second receiving coil 202 on the same plane, the transmitting coil 100 forming a projection on the plane, the first receiving coil 201 being in the plane The above-formed regions all include the projections, and of course may also partially include the projections, the second receiving coil 202 has one area formed on the plane, and the area is surrounded by an opening. Around the projection, and the first receiving coil 201 and the second receiving coil 202 are electrically connected, the receiving coil system 200 is not limited to include a first receiving coil 201 and a second receiving coil 202 in the same plane, which constitute Can be two or more.

As an embodiment of the present invention, as shown in FIG. 3, a greatly simplified schematic diagram for positioning gold A second embodiment of the sensor geometry of the sensor of the invention belonging to the object. A metal sensor having a transmitting coil 100 and a receiving coil system 200 inductively coupled to each other. This embodiment is described by taking one transmitting coil 100 and one receiving coil system 200 as an example, but the sensor of the present invention is not limited to one. The receiving coil system 200 of the present invention includes a first receiving coil 201 and a second receiving coil 202 on the same plane, the transmitting coil 100 forming a projection on the plane, the first receiving coil 201 being in the plane The above-formed regions all include the projections. Of course, the projections may be partially included. The second receiving coil 202 has two regions formed on the plane, respectively being the second receiving coils (202'. , 202"), the regions are sequentially distributed around the projection, and the first receiving coil 201 and the second receiving coil (202', 202") are electrically connected, and the receiving coil system 200 is not limited to include One first receiving coil 201 and two second receiving coils second receiving coils (202', 202") of the same plane may be composed of three or more.

In this embodiment, when the layout is as shown in FIG. 3, the optimal mode is that the second receiving coil (202', 202") group is symmetrically distributed with respect to the transmitting coil 100, and the various factors such as humidity and temperature may affect the emission. The magnetic field of the coil 100, if it is symmetrical, better offsets this effect, of course, the asymmetry can also be achieved. In the specific implementation process, sometimes to increase the sensitivity, while maintaining the balance of the induced voltage, increase the reception The number of wires of the coil system such as the first receiving coil 201 or the second receiving coil (202, 202', 202") and the area enclosed by the coil can improve the sensitivity of the measurement.

The position setting of the transmitting coil 100 of this embodiment may be located at a certain distance above the common receiving plane and arranged in parallel with the receiving coil system 200. At least two of the printed circuit are provided for fixed mounting of the transmitting coil 100. a positioning hole, a pin of the transmitting coil 100 is inserted into the positioning hole and soldered on the circuit board; the transmitting coil 100 may also be a wire structure directly disposed on the printed circuit board or embedded in the printed circuit board. The way is fine.

The first receiving coil 201 and the second receiving coil 202 of the present invention have the same winding direction. For the corresponding connection manner of the first embodiment, as shown in FIG. 4, the positive electrode of the induced voltage of the first receiving coil 201 is as shown in FIG. Connected to the negative pole of the induced voltage of the second receiving coil 202, the induced voltages of the coils are added, and the connection manner corresponding to the second embodiment is similar to that shown in FIG. 5. In this connection mode, it can be seen that for the induced voltage of the receiving coil to induce the first magnetic field, the connection mode can cancel the induced voltage, and the induced voltage of the second magnetic field is superimposed, so that the first sensing can be cancelled out. The induced voltage of the magnetic field can increase the induced voltage of the second magnetic field, which greatly improves the sensitivity of the detection.

As shown in Figures 6 and 7, for the second magnetic field generated by the target, the induced voltage formula is based on E = n ΔΦ / Δt, E: induced electromotive force (V), n: number of induction coil turns, ΔΦ / Δt: change in magnetic flux Rate, due to the co-directional winding of the coils, the induced electromotive forces generated by them are superimposed on each other, so the sensitivity of the receiving coil to the magnetic field induction of the target object is enhanced, the blind area of the measurement is not formed, and the measurement accuracy is greatly improved; The receiving coil and the second receiving coil are arranged on the circuit board, and the precision of the position is very high for the external winding receiving coil, and can be more than 0.1 mm at present, which greatly improves the consistency of the product and can better offset The induced voltage generated by the first magnetic field can be reduced on the circuit board.

In the present embodiment, as shown in FIG. 8, the black dots in the figure indicate that the connection points, that is, the output stages, are generally disposed at the beginning and the end of the coil, and the first receiving coil 201 is generally disposed at least in the figure. A connection point, if set as a connection point, is generally set at the beginning of the coil. The more the set point, the larger the range that can be calibrated. Generally, it is preferable to set 3 points, corresponding to the first one of the first embodiment. The receiving coil 201 is provided with three output stages (11, 22, 33). The smaller the position interval of the output stage, the higher the accuracy of the calibration, and it is generally about one turn apart, and the interval is consistent. In the figure, at least one connection point is generally disposed on the second receiving coil 202. If it is set as a connection point, it can be disposed at the end position of the coil, generally about 3 to 10, corresponding to the second receiving coil of the first embodiment. The 202 has three output stages (44, 55, 66). For better calibration, the output stage connection point can be set to a position that satisfies the following conditions: in the absence of metal, the second reception The voltage induced between the output stages furthest apart on the coil is substantially equal to the voltage induced between the two output stages closest to the first receiving coil; or the first connection The voltage induced between the output stages of the farthest interval on the receiving coil is substantially equal to the voltage induced between the two output stages of the second receiving coil, and the smaller the position interval of the connecting points on the second receiving coil, The higher the accuracy of the calibration, the more connection points are required, generally about one turn apart, and the spacing is consistent.

The three output stages (11, 22, 33) on the first receiving coil 201 are electrically connected to one ends of the switching devices (11ˋ, 22ˋ, 33ˋ), respectively, and the other ends of the three switching devices are electrically connected to the input terminals of the amplifying circuit 500. The output port of the amplifying circuit 500 is connected to the processor 400. The switching device of the embodiment is generally a Mos tube or a three-stage tube, and the processor 400 controls the closing and opening of the switching device. The amplifier of this embodiment generally selects an operational amplifier with high input impedance, low noise, and low temperature drift.

Similarly, the three output stages (44, 55, 66) on the second receiving coil 202 are electrically connected to one end of the switching device (44ˋ, 55ˋ, 66ˋ), respectively, and the other end of the three switching devices and the input of the amplifying circuit 500. The terminal is electrically connected, and the output of the amplifying circuit 500 is connected to the processor 400.

The operating device runs the device in the absence of the object to be located, and the processor 400 sequentially detects the output signal amplitude of each output stage through the switching device by controlling each output stage, and stores the switching device setting information, the switching device setting information is The output signal amplitude is used to compare and filter the open/close state information of each switch device corresponding to the selected minimum amplitude output signal; the switch device is controlled to open and close according to the switch device setting information, and the running device performs object positioning.

The specific implementation process is as follows:

The transmitting coil 100 is driven to generate an alternating magnetic field in the absence of an object, and the processor 400 detects the amplitude of the output signal of the amplifying circuit 500.

Turning on the switching device 11A and the switching device 44A, turning off the other switching devices, detecting the amplitude A1 of the output signal of the amplifying circuit 500;

Turning on the switching device 11ˋ and the switching device 55ˋ, turning off the other switching devices, detecting the amplitude A2 of the output signal of the amplifying circuit 500;

Turn on the switch device 11ˋ and the switch device 66ˋ, turn off the other switch devices, and detect the amplified power. The amplitude A3 of the output signal of the road 500;

Turning on the switching device 22ˋ and the switching device 44ˋ, turning off the other switching devices, detecting the amplitude B1 of the output signal of the amplifying circuit 500;

Turning on the switching device 22ˋ and the switching device 55ˋ, turning off the other switching devices, detecting the amplitude B2 of the output signal of the amplifying circuit 500;

Turning on the switching device 22ˋ and the switching device 66ˋ, turning off the other switching devices, detecting the amplitude B3 of the output signal of the amplifying circuit 500;

Turning on the switching device 33ˋ and the switching device 44ˋ, turning off the other switching devices, detecting the amplitude C1 of the output signal of the amplifying circuit 500;

Turning on the switching device 33A and the switching device 55A, turning off the other switching devices, detecting the amplitude C2 of the output signal of the amplifying circuit 500;

Turning on the switching device 33ˋ and the switching device 66ˋ, turning off the other switching devices, detecting the amplitude C3 of the output signal of the amplifying circuit 500;

Finding the minimum amplitude, obtaining the state of the corresponding switching device, and storing the state in the non-volatile memory, the processor 400 directly reads the state of the switch from the non-volatile memory in the next operation, The sensitivity to the detection of the target is improved; the state of the switching device of this embodiment has n*m states, where n is the number of connection points on the first receiving coil, and m is the connection on the second receiving coil. The number of points.

In this embodiment, as shown in FIG. 9, for the apparatus of the second embodiment, since the second receiving coil 202' and the second receiving coil 202" are substantially symmetrically disposed, the output end of the second receiving coil 202' and the The input ends of the two receiving coils 202" are electrically connected. The other principles are the same as those in the first embodiment, and are not described here.

In summary, the first receiving coil 201 and the second receiving line of the embodiment of the present invention can arrange a plurality of coil numbers in a small area, and in the first receiving coil 201 and the second receiving coil (202, 202', 202" The coils are arranged at different positions, so that the calibration can be performed over a wide range. It saves space, can increase the number of switches set, improve the adjustment precision, and can realize bidirectional calibration of the induced voltage, greatly improving the adjustment accuracy.

In an embodiment of the present invention, an analysis circuit is further included, the analysis circuit includes an operational amplifier and a processor, and an output stage of the receiving coil system 200 of the embodiment of the present invention may be connected to the analysis circuit through a switching device. It can also be directly connected to the analysis circuit, and the following is described by being connected to the analysis circuit through a switching device. The processor can control the opening and closing of the switching device, and the switching device connected to the connection point on the first receiving coil 201 One end is connected to the input end of the amplifying circuit, the other end of the switching device connected to the connection point on the second receiving coil 202 is connected to the other end input end of the amplifying circuit, and a capacitor is connected in series at the input end of the amplifying circuit to reduce the receiving coil DC The effect of the signal, the amplifier output is electrically connected to the processor, and the op amp typically selects a high input impedance, low noise, low temperature drift op amp.

The line segments of the first receiving coil 201 and the second receiving coil 202 of the present embodiment have a planar, single-layer winding geometry. Moreover, it is possible to arrange a plurality of coil numbers in a small area, and the present invention can arrange a plurality of receiving coils in a small area, and connect each coil group in the switching device (1'-6'). The number of wires in the circuit can be adjusted in a larger range, and the arrangement space of the number of receiving coils can be saved, and the length (number of times) and the number of switching devices of each adjacent switching device can be adjusted in advance. The range and accuracy of the control are controlled, that is, the dimensional accuracy of the winding is very high, and it is technically not problematic to accurately manufacture a copper structure of up to 25 μm on the board.

The invention analyzes the measurement signal of the sensor by the following method: digitally generating an excitation signal of frequency F1, driving the transmitting coil, generating an alternating magnetic field, and measuring amplifier of the analyzing circuit of the sensor The output signal is subjected to phase-synchronized analog-to-digital conversion, and the phase-synchronized analog-to-digital conversion of the output signal of the measuring amplifier is converted at a frequency f1=nF1 and a converted signal is output, where n≥2, n is an integer. Whether or not there is target data is analyzed. When there is no target object, as shown in FIG. 10, spectrum analysis is performed on the converted signal to obtain a vector of a signal of frequency F1, which is represented as a vector signal A (Vx1 in the complex plane). , Vy1); in the presence of the target In the case of the body, the spectrum of the converted signal is analyzed to obtain a vector of the signal of frequency F1, which is represented as a vector signal vector signal B (Vx2, Vy2) in the complex plane; and the vector signals A and B are subtracted to obtain a new vector. Signal C (Vx2-Vx1, Vy2-Vy1). Analyzing the amplitude change of the vector signal C, recording the first wave peak in the amplitude change of the vector signal C and the plane position one and two of the second wave peak, and using the midpoint position information of the plane position one and two as the medium object in the medium The closest location information output.

When the amplitude of the vector signal C is greater than a set threshold, theoretically, in the absence of an object, the amplitude of C is zero, and there is no phase, but in practice, due to the noise of the power supply, the receiving coil Distribution, the noise of the op amp circuit, temperature, humidity and other factors, so that the vector signal C is not 0, assuming the threshold is set to W, due to the randomness of the noise, the phase is also uncertain, at this time there is no The object exists. When the magnitude of the vector is greater than W and the phase also satisfies the condition, then an object is considered to exist.

Different circuit parameters, different receiving coil distributions, measuring the same object, the phase is also different, so after the circuit is determined, the metal objects with the largest magnetic permeability and the smallest magnetic permeability are respectively measured, and their phase values are recorded. The phase range covered by the metal object can be obtained, so when the amplitude of the vector C is greater than W, but the phase is within the range of the first phase interval covered, it can be judged that there is metal, and the first phase interval The values of the two ends are the phase values of the vector signal C when the object to be detected is the metal with the largest magnetic permeability and the lowest magnetic permeability. Similarly, the magnetic metals with the largest magnetic permeability and the smallest magnetic permeability are measured, and they are recorded. The phase value of the phase can be obtained, so when the amplitude of the vector C is greater than W, but the phase is within the range of the second phase interval covered, it can be judged that the presence of magnetic metal exists. The values of the two ends of the second phase interval are the phase values of the vector signal C when the object to be detected is the magnetic material with the largest magnetic permeability and the smallest magnetic permeability, and so on. Measuring the non-magnetic metal with the largest magnetic permeability and the smallest magnetic permeability, and recording their phase values, the phase range covered by the object can be obtained, so when the amplitude of the vector C is greater than W, the phase is at the third coverage. Within the range of the phase interval, it can be judged that there is a non-magnetic metal, wherein the two ends of the third phase interval are respectively the magnetic permeability of the object to be detected. The phase value of the vector signal C of the non-magnetic metal having the smallest and largest magnetic permeability, thereby distinguishing whether the target is a magnetic metal or a non-magnetic metal, and the analysis method of the present invention can accurately obtain the property of the detected object with high precision. .

In the present embodiment, the sensor of the present invention detects an object enclosed in a medium by the following detection method. The detection method of the present invention is as follows: the attribute and position information of the enclosed object are obtained by analyzing the measurement signal, the measurement The signal is a vector signal obtained by subtracting a signal generated by the receiving coil end from the preset signal when the sensor detects the state, and the preset signal is a signal generated by the sensor receiving coil end in the absence of the object.

When the amplitude of the measurement signal is greater than a set threshold, the output determination signal displays an object in the medium, analyzes the phase of the measurement signal, and outputs a determination signal when the phase of the measurement signal is within the first phase interval. The object in the display medium is metal, otherwise the output judgment signal indicates that the object in the medium is no metal object; the two ends of the first phase interval are respectively measured when the object to be detected is the metal with the largest magnetic permeability and the smallest magnetic permeability. The phase value of the signal.

When the amplitude of the measurement signal is greater than a set threshold, the output determination signal displays an object in the medium, analyzes the phase of the measurement signal, and outputs a determination signal when the phase of the measurement signal is within the second phase interval. The object in the display medium is a magnetic metal, and the two ends of the second phase interval are phase values of the measurement signal when the object to be detected is a magnetic metal having the largest magnetic permeability and the smallest magnetic permeability. When the phase of the measurement signal is in the third phase interval, the output judgment signal indicates that the object in the medium is a non-magnetic metal, and the two ends of the third phase interval are respectively the magnetic permeability and the magnetic permeability of the object to be detected. The phase value of the signal is measured with the smallest non-magnetic metal. The detection method of the present invention can also distinguish between magnetic metal and non-magnetic metal based on the phase value.

At the same time, the amplitude change of the measurement signal is analyzed, and the first wave peak and the second wave peak position in the amplitude change of the measurement signal are recorded, and the midpoint position information of the plane position one and two is used as the medium object in the medium. The closest location information output. As shown in FIG. 11, with the sensor of the present invention, when the target object is not located below the receiving coil, the closer the receiving coil system is to the target, the vector The larger the amplitude of C is, the smaller the amplitude of vector C is when the receiving coil is far away from the target; when the metal moves from the edge of the receiving coil toward the receiving coil, the amplitude of vector C becomes smaller from small to large. The amplitude of the vector C suddenly changes from large to small, indicating that the object is close to the center point of the second receiving coil system. At this time, it is marked as the starting point of the midpoint. When the amplitude of the vector C suddenly increases from small to large, the target is in the second position. The center position of the receiving coil, when the amplitude of the vector C suddenly changes from large to small, indicating that the target is away from the second receiving coil, and is marked as the end point of the midpoint.

The sensor of the invention can advantageously be integrated into a measuring device. In this case, the measuring device can be embodied in particular as a hand-held metal positioning device or as a further function comprising the metal positioning capability of the sensor of the invention. In addition, it is also possible and advantageous to integrate the sensor of the invention into a machine tool, for example into a drilling tool, in order to enable the user to work safely with the machine.

The invention makes it possible to realize a low-cost sensor which makes it possible to replace as many costly components and device components as possible, that is to say that the sensor circuit board is used not only as a carrier material for the electronic circuit but also as a functional part. The integral part of the sensor. A sensor for positioning a metal object according to the present invention requires only a single coil. This is in particular by replacing the typically wound receiving coil as disclosed in the prior art by means of a wire set on the circuit board of the sensor's analysis circuit.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not limited thereto; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced; and the modifications or substitutions do not deviate from the scope of the technical solutions of the embodiments of the present invention.

In summary, the above description is only the preferred embodiment of the present invention, and all changes and modifications made by the scope of the present invention should be covered by the present invention.

Claims

A metal sensor having at least one transmitting coil and at least one receiving coil system inductively coupled to each other, the receiving coil system including at least one first receiving coil and at least one second receiving coil in a same plane, the transmitting coil being Forming a projection on the plane, wherein: an area formed by the first receiving coil on the plane includes the projection, and an area formed by the second receiving coil on the plane is disposed at the projection Around the first receiving coil and the second receiving coil are electrically connected.
The sensor according to claim 1, wherein the area formed by said first receiving coil on said plane all comprises said projection.
The sensor of claim 1 wherein the portion of the region formed by the first receiving coil on the plane comprises the projection.
A sensor according to any one of claims 1 to 3, wherein the second receiving coil has a region formed on the plane, and the region is surrounded by an opening around the projection.
The sensor according to any one of claims 1 to 3, characterized in that the second receiving coil has at least two regions formed on the plane, and the regions are sequentially distributed around the projection.
The sensor according to claim 4 or 5, characterized in that each of the first receiving coil and/or the second receiving coil and/or the first and second receiving coils is provided with one output stage.
The sensor according to claim 4 or 5, characterized in that the first receiving coil is provided with at least two output stages, and the second receiving coil is provided with at least two output stages.
The sensor according to claim 7, comprising switching means, said output stages being respectively connected to the switching means.
The sensor according to claim 8, wherein said switching device is a Mos tube or a tertiary tube.
A sensor according to claim 9 including an analysis circuit, the output stage of said receiving coil system being coupled to said analysis circuit via a switching device.
The sensor of claim 6 including an analysis circuit, the output stage of said receive coil system being coupled to said analysis circuit.
The sensor of claim 11 wherein said analysis circuit comprises an operational amplifier and a processor.
The sensor of claim 12 wherein said transmitting coil is embedded in a printed circuit board.
A measuring device comprising the sensor of any of claims 1-13.
A measuring device according to claim 14, characterized in that said measuring device is a hand-held positioning device.