Wall metal detector and method for locating target thereof

Abstract

The invention discloses a wall metal detector and a method for locating a target thereof, comprising a shell, a power supply, a controller, a transmitting coil (L1), a receiving coil and a compensation coil; the receiving coil comprises a first receiving coil (L2), a second receiving coil (L3) and a third receiving coil (L4); the compensation coil is connected in series in a loop formed by the receiving coils; the first receiving coil (L2) and the third receiving coil (L4) are symmetrically arranged on the left and right sides of the transmitting coil (L1), and the winding direction of the first receiving coil (L2) is opposite to that of the third receiving coil (L4); the first receiving coil (L2) can be connected with the third receiving coil (L4) to form a receiving loop for detecting the left and right directions of the wall metal; the compensation coil comprises a first compensation coil (L5), a second compensation coil (L6), a third compensation coil (L7) and a fourth compensation coil (L8), and switches K1, K2, K3, K4, K5, K6, K7 and K8 are used to switch the inner coil and the outer coil respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of metal detection, and in particular to a wall metal detector and a method for locating a target thereof. Background Art

[0002] At present, metal detectors can detect hidden metal objects and have been widely used in military, security, mining, industry, daily life and other aspects. Metal detectors use the principle of electromagnetic induction and are equipped with a controller, transmitting coil and receiving coil. The controller controls the transmitting coil to generate a periodically changing alternating magnetic field. The alternating magnetic field generates an eddy electric field around the metal detector. If the metal detector is close to the metal, an eddy current is formed on the eddy electric field receiving coil, which is sensed by the controller inside the metal detector, thereby controlling the issuance of an alarm reminder signal.

[0003] This metal detector has a simple manufacturing process, low cost and is easy to implement. However, the biggest technical difficulty in detecting hidden metal objects is that the reflected signal of the metal being detected is very small and the sensitivity is low. Due to the volume and properties of the metal, especially when the ferrous metal object is small or the metal object is non-ferrous metal, the signal output is very small, which will make detection difficult.

[0004] In order to detect this weak signal and improve the measurement sensitivity of the metal detector, it is necessary to obtain a larger signal from the receiving coil. Therefore, it is necessary to increase the number of turns of the receiving coil. After increasing the receiving coil, when no metal enters the magnetic field, the receiving coil can directly obtain a larger reflected signal from the transmitting coil. However, after the metal enters the magnetic field, the signal after the coil coupling will increase exponentially, which will cause the signal output to exceed the measurement range, and the controller will be unable to accurately obtain the measured signal.

[0005] Ideally, when there is no metal, a signal of 0 is output. When metal enters the alternating magnetic field of the metal detector, the output signal gradually increases as the metal approaches. When the metal is close to the metal detector, the output signal is just close to the full scale. This can not only accurately identify the metal, but also significantly improve the sensitivity.

[0006] To achieve this function, a receiving coil is added to generate a counter voltage to offset the original received signal. At the same time, the coil itself is less sensitive to the magnetic field generated by metal. Therefore, when metal enters the magnetic field, a differential pressure is output.

[0007] During the production process, the gap caused by the installation of the transmitting coil and the unevenness of the transmitting coil may cause the differential pressure signal to be non-zero, or even very large, which will cause the detection coil itself to fail.

[0008] In order to solve the above problems, the document with patent application number CN201710864187.3 discloses a metal detector and a method for compensating its detection coil. It includes: a magnetic field transmitting unit, a magnetic field receiving unit, and an alarm; the magnetic field transmitting unit includes a transmitting coil; the magnetic field receiving unit includes a receiving coil, the receiving coil includes a first receiving coil and a second receiving coil, and the second receiving coil is provided with a fine compensation switch; the first receiving coil and the second receiving coil are wound in opposite directions, and the second receiving coil is close to the transmitting coil; the alarm is electrically connected to the magnetic field receiving unit.

[0009] The transmitting coil and the receiving coil are located in the same plane and their centers overlap. The second receiving coil is divided into four groups, each group is provided with two fine compensation switches; the fine compensation switch is arranged at the outermost circle of the second receiving coil. The transmitting coil and the receiving coil are arranged in a circular shape. The coarse compensation coil is located between the second receiving coil and the transmitting coil. The coarse compensation coil and the second receiving coil have the same winding direction. The coarse compensation coil is divided into four groups, each group is provided with two coarse compensation switches, and the coarse compensation switches are arranged at the outermost circle of the coarse compensation coil. Preferably, the coarse compensation switch and the fine compensation switch are separated by a spatial angle difference of 45°.

[0010] A method for a metal detector to compensate its detection coil, characterized in that it includes the following steps: S1. The magnetic field transmitting unit generates an alternating current magnetic field; S2. The magnetic field receiving unit determines whether there is metal involved in the alternating current magnetic field, and if so, the first receiving coil generates different induction intensities according to different metals; S3. The alarm sends out alarm signals of different frequencies according to different induction intensities; S4. If there is no metal involved in the alternating current magnetic field, it is determined whether the alternating current magnetic field is uniform, and if not, the fine compensation switch is turned on to adjust the strength of the magnetic field generated by the second receiving coil.

[0011] Preferably, the step S4 further comprises: turning on the coarse compensation switch to adjust the magnitude of the magnetic field strength generated by the coarse compensation coil.

[0012] The inventors have found that the above technical solution has the following disadvantages: 1. It is not possible to determine the direction of the location of the metal target; 2. There are not many combinations of compensation coils. Summary of the invention

[0013] The object of the present invention is to provide a wall metal detector and a method for locating a target thereof, so as to overcome the defects in the above-mentioned prior art.

[0014] The technical solution adopted by the present invention is as follows:

[0015] A wall metal detector comprises a housing, a power supply, a controller, a transmitting coil L1, a receiving coil and a compensating coil; the receiving coil comprises a first receiving coil L2, a second receiving coil L3 and a third receiving coil L4; the compensating coil surrounds the outer side of the transmitting coil L1, and the compensating coil is connected in series in a loop formed by the receiving coil;

[0016] The first receiving coil L2 and the third receiving coil L4 are symmetrically arranged on the left and right sides of the transmitting coil L1; and the winding direction of the first receiving coil L2 is opposite to that of the third receiving coil L4; the first receiving coil L2 can be connected with the third receiving coil L4 to form a receiving circuit for detecting the left and right directions of the wall metal;

[0017] The second receiving coil L3 is arranged outside the first receiving coil L2 and the third receiving coil L4, and the winding direction of the second receiving coil L3 is opposite to that of the third receiving coil L4; the second receiving coil L3 can be connected with the third receiving coil L4 to form a receiving circuit for judging the strength of the induction signal.

[0018] Preferably, the transmitting coil L1 , the receiving coil and the compensation coil may be arranged on the same plane; or arranged on different planes, and the different planes are parallel to each other and respectively perpendicular to a common Z direction.

[0019] Preferably, the transmitting coil L1 and the compensation coil are circular in shape and are arranged coaxially with respect to each other.

[0020] Furthermore, the receiving coil includes an nth receiving coil and an n+2th receiving coil, the nth receiving coil and the n+2th receiving coil are symmetrically arranged around the transmitting coil, and the winding direction of the nth receiving coil is opposite to that of the n+2th receiving coil; the nth receiving coil can be connected with the n+2th receiving coil to form a receiving circuit for detecting the orientation of the metal wall.

[0021] A wall metal detector comprises a housing, a power supply, a controller, a transmitting coil L1, a receiving coil, and a compensation coil; wherein the receiving coil comprises a first receiving coil L2, a second receiving coil L3, and a third receiving coil L4;

[0022] The first receiving coil L2 and the third receiving coil L4 are symmetrically arranged on the left and right sides of the transmitting coil L1; and the winding direction of the first receiving coil L2 is opposite to that of the third receiving coil L4; the first receiving coil L2 can be connected with the third receiving coil L4 to form a receiving circuit for detecting the left and right directions of the wall metal;

[0023] The second receiving coil L3 is arranged outside the first receiving coil L2 and the third receiving coil L4, and the winding direction of the second receiving coil L3 is opposite to that of the first receiving coil L2; the second receiving coil L3 can be connected with the first receiving coil L2 to form a receiving circuit for judging the strength of the induction signal.

[0024] Furthermore, the wall metal detector also includes a fourth receiving coil L21 and a fifth receiving coil L41; the fourth receiving coil L21 and the fifth receiving coil L41 are symmetrically arranged on the upper and lower sides of the transmitting coil L1; the winding direction of the fourth receiving coil L21 is opposite to that of the fifth receiving coil L41; the fourth receiving coil L21 can be connected with the fifth receiving coil L41 to form a receiving circuit for detecting the upper and lower positions of the wall metal.

[0025] When there is no metal target in the wall, the induction signal generated by the fourth receiving coil L21 is balanced with the induction signal generated by the fifth receiving coil L41; when the metal target is located on one side of the fifth receiving coil L41, the induction signal of the fifth receiving coil L41 is greater than the induction signal of the fourth receiving coil L21; when the metal target is located on one side of the fourth receiving coil L21, the induction signal of the fourth receiving coil L21 is greater than the induction signal of the fifth receiving coil L41.

[0026] Further, the compensation coil can be connected in series with any one coil, any two coils or three coils of the first receiving coil L2, the second receiving coil L3 or the third receiving coil L4 to perform signal compensation; the compensation coil includes a first compensation coil L5 and a second compensation coil L6, the first compensation coil L5 includes an outer ring L5a farther from the transmitting coil and an inner ring L5b closer to the transmitting coil, and the compensation coil L5 is provided with a switch K1 for switching the outer ring L5a and the inner ring L5b; the second compensation coil L6 includes an outer ring L6a farther from the transmitting coil and an inner ring L6b closer to the transmitting coil, and the compensation coil L6 is provided with a switch K2 for switching the outer ring L6a and the inner ring L6b.

[0027] Since the closer the compensation coil is to the transmitting coil L1, the stronger the induced signal is, if the outer ring L5a is switched on, the signal is enhanced; if the inner ring L5b is switched on, the signal is reduced.

[0028] Furthermore, the compensation coil also includes a third compensation coil L7 and a fourth compensation coil L8, the third compensation coil L7 includes an outer ring L7a farther from the transmitting coil and an inner ring L7b closer to the transmitting coil, and the compensation coil L7 is provided with a switch K3 for switching the outer ring L7a and the inner ring L7b; the fourth compensation coil L8 includes an outer ring L8a farther from the transmitting coil and an inner ring L8b closer to the transmitting coil, and the compensation coil L8 is provided with a switch K4 for switching the outer ring L8a and the inner ring L8b.

[0029] Further, the shapes of the first compensation coil L5, the second compensation coil L6, the third compensation coil L7 and the fourth compensation coil L8 are different equally divided circles. For example, the first compensation coil L5 is a half circle; the second compensation coil L6 is a quarter circle; the third compensation coil L7 is an eighth circle; the fourth compensation coil L8 is a sixteenth circle, etc.

[0030] A method for locating a target by a wall metal detector comprises the following steps:

[0031] Introducing current into the first receiving coil L2 and the third receiving coil L4, so that the first receiving coil L2 and the third receiving coil L4 form a group of receiving coils; the first receiving coil L2 and the third receiving coil L4 respectively generate induction signals;

[0032] connecting the third receiving coil L4, the first compensating coil L5 and the second compensating coil L6 to compensate for the induction signal generated by the third receiving coil L4;

[0033] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b; so that when there is no metal target on the wall, the induction signals generated by the first receiving coil L2 and the third receiving coil L4 are balanced;

[0034] When there is a metal target on the wall, if the metal target is located on the side of the third receiving coil L4, the induction signal of the third receiving coil L4 is greater than the induction signal of the first receiving coil L2; if the metal target is located on the side of the first receiving coil L2, the induction signal of the first receiving coil L2 is greater than the induction signal of the third receiving coil L4;

[0035] Current is introduced into the second receiving coil L3 and the third receiving coil L4, and the second receiving coil L3 and the third receiving coil L4 are wound in opposite directions; the second receiving coil L3 and the third receiving coil L4 form a group of receiving coils; the second receiving coil L3 and the third receiving coil L4 respectively generate induction signals, and the strength of the induction signal generated by the second receiving coil L3 and the induction signal generated by the third receiving coil L4 are compared to determine the size of the metal target.

[0036] A method for locating a target by a wall metal detector comprises the following steps:

[0037] Introducing current into the first receiving coil L2 and the third receiving coil L4, so that the first receiving coil L2 and the third receiving coil L4 form a group of receiving coils; the first receiving coil L2 and the third receiving coil L4 respectively generate induction signals;

[0038] Connecting the third receiving coil L4, the first compensation coil L5 and the second compensation coil L6 to compensate for the induction signal generated by the third receiving coil L4;

[0039] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b, so that when there is no metal target on the wall, the induction signals generated by the first receiving coil L2 and the third receiving coil L4 are balanced;

[0040] When there is a metal target on the wall, if the metal target is located on the side of the third receiving coil L4, the induction signal of the third receiving coil L4 is greater than the induction signal of the first receiving coil L2; if the metal target is located on the side of the first receiving coil L2, the induction signal of the first receiving coil L2 is greater than the induction signal of the third receiving coil L4;

[0041] Current is introduced into the second receiving coil L3 and the first receiving coil L2, and the second receiving coil L3 and the first receiving coil L2 are wound in opposite directions; the second receiving coil L3 and the first receiving coil L2 form a group of receiving coils; the second receiving coil L3 and the first receiving coil L2 respectively generate induction signals, and the induction signal generated by the second receiving coil L3 is compared with the induction signal generated by the first receiving coil L2 to determine the size of the metal target.

[0042] Furthermore, the method further comprises the following steps: introducing current into the fourth receiving coil L21 and the fifth receiving coil L41, wherein the fourth receiving coil L21 and the fifth receiving coil L41 form a group of receiving coils; and the fourth receiving coil L21 and the fifth receiving coil L41 respectively generate induction signals;

[0043] connecting the fourth receiving coil L41, the first compensation coil L5 and the second compensation coil L6 to compensate for the induction signal generated by the fourth receiving coil L41;

[0044] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b; switching so that when there is no metal target on the wall, the induction signals generated by the fourth receiving coil L21 and the fifth receiving coil L41 are balanced;

[0045] When there is a metal target on the wall, if the metal target is located on the side of the fifth receiving coil L41, the induction signal of the fifth receiving coil L41 is greater than the induction signal of the fourth receiving coil L21; if the metal target is located on the side of the fourth receiving coil L21, the induction signal of the fourth receiving coil L21 is greater than the induction signal of the fifth receiving coil L41.

[0046] Furthermore, the method further comprises the following steps:

[0047] The third receiving coil L4, the first compensating coil L5, the second compensating coil L6, the third compensating coil L7, and the fourth compensating coil L8 are connected to compensate for the induction signal generated by the third receiving coil L4; the outer ring L5a and the inner ring L5b are switched; the outer ring L6a and the inner ring L6b are switched; the outer ring L7a and the inner ring L7b are switched; the outer ring L8a and the inner ring L8b are switched; so that when there is no metal target on the wall, the induction signals generated by the first receiving coil L2 and the third receiving coil L4 are balanced.

[0048] The beneficial effects of the present invention are as follows: First, the wall metal detector of the present invention has the function of detecting metal targets and sizes by arranging receiving coils L2 and L4 for determining the direction and a receiving coil L3 for determining the strength of the induced signal on the outside of the transmitting coil.

[0049] Second, the present invention creatively sets each group of compensation coils as an outer ring and an inner ring that can be switched by a switch. By switching the outer ring and the inner ring, a combination method with twice the number of compensation coils can be obtained to form a receiving circuit.

[0050] Third, the present invention creatively sets the shape of each group of compensation coils to be different equally divided circles, and compensates the receiving coil by connecting compensation coils of different shapes. Assuming that the detector is equipped with four groups of compensation coils of different shapes, the shapes of the four groups of compensation coils are respectively one-half circle, one-quarter circle, one-eighth circle and one-sixteenth circle, then by switching different compensation coils, 24 combinations of the number of compensation coils can be obtained to form a receiving circuit.

[0051] The above-mentioned multiple combinations of compensation methods can compensate for the deviations caused by the coil production and installation process and electronic components, thereby improving the detection sensitivity of the metal detector and the ability to detect weak signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the structure of the compensation coil and the receiving coil of the present invention from a top view;

[0053] Figure 2 It is a schematic diagram of the exploded structure of the compensation coil and the receiving coil of Embodiment 1 of the present invention;

[0054] Figure 3 It is a schematic diagram of the structure of the compensation coil and the receiving coil from a top view according to Embodiment 1 of the present invention;

[0055] Figure 4 Schematic diagram of a circuit of Embodiment 1 of the present invention;

[0056] Figure 5 It is a schematic diagram of the structure of the compensation coil and the receiving coil from a top view according to Embodiment 2 of the present invention;

[0057] Figure 6 Schematic diagram of a circuit of Embodiment 2 of the present invention;

[0058] Figure 7 It is a schematic diagram of the structure of the compensation coil and the receiving coil from a top view according to Embodiment 3 of the present invention;

[0059] Figure 8 This is a circuit diagram of Embodiment 3 of the present invention;

[0060] In the figure: Z, axial direction; L1, transmitting coil; L2, first receiving coil; L3, second receiving coil; L4, third receiving coil; L21, fourth receiving coil; L41, fifth receiving coil; L5, first compensation coil; L5a, outer coil; L5b, inner coil; L6, second compensation coil; L6a, outer coil; L6b, inner coil; L7, third compensation coil; L7a, outer coil; L7b, inner coil; L8, fourth compensation coil; L8a, outer coil; L8b, inner coil; K1, switching switch; K2, switching switch; K3, switching switch; K4, switching switch; K5, switching switch; K6, switching switch; K7, switching switch; K8, switching switch; DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] The terms "first", "second", "third", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions.

[0063] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0064] Embodiment 1, as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a wall metal detector includes a housing, a power supply, a controller, a transmitting coil L1, a receiving coil and a compensation coil; the receiving coil includes a first receiving coil L2, a second receiving coil L3 and a third receiving coil L4; the compensation coil surrounds the outer side of the transmitting coil L1, and the compensation coil is connected in series in the loop formed by the receiving coil;

[0065] The first receiving coil L2 and the third receiving coil L4 are symmetrically arranged on the left and right sides of the transmitting coil L1; and the winding direction of L2 is opposite to that of L4; L2 can be connected with L4 to form a receiving loop for detecting the left and right directions of the wall metal;

[0066] The second receiving coil L3 is arranged outside the first receiving coil L2 and the third receiving coil L4, and the winding direction of the second receiving coil L3 is opposite to that of the third receiving coil L4; the second receiving coil L3 can be connected with the third receiving coil L4 to form a receiving circuit for judging the strength of the induction signal.

[0067] The transmitting coil L1 , the receiving coil, and the compensation coil are arranged on the same plane; the transmitting coil L1 and the compensation coil are circular in shape and are arranged coaxially with respect to each other.

[0068] The compensation coil includes a first compensation coil L5 and a second compensation coil L6; a third compensation coil L7 and a fourth compensation coil L8; the first compensation coil L5 includes an outer ring L5a which is farther away from the transmitting coil and an inner ring L5b which is closer to the transmitting coil, and the compensation coil L5 is provided with a switch K1 for switching the outer ring L5a and the inner ring L5b; the second compensation coil L6 includes an outer ring L6a which is farther away from the transmitting coil and an inner ring L6b which is closer to the transmitting coil, and the compensation coil L6 is provided with a switch K2 for switching the outer ring L6a and the inner ring L6b. The third compensation coil L7 includes an outer ring L7a which is farther away from the transmitting coil and an inner ring L7b which is closer to the transmitting coil. The compensation coil L7 is provided with a switch K3 for switching the outer ring L7a and the inner ring L7b; the fourth compensation coil L8 includes an outer ring L8a which is farther away from the transmitting coil and an inner ring L8b which is closer to the transmitting coil. The compensation coil L8 is provided with a switch K4 for switching the outer ring L8a and the inner ring L8b; k5 is turned on and K6 is turned off; K7 is turned on and K8 is turned off; L3 and L4 form a receiving coil.

[0069] k5 is turned on, K6 is turned on; K7 is turned off, K8 is turned on; L2 and L4 form a receiving coil.

[0070] The first compensation coil L5 is in the shape of one-sixteenth of a circle; the second compensation coil L6 is in the shape of one-eighth of a circle; the third compensation coil L7 is in the shape of one-fifth of a circle; and the fourth compensation coil L8 is in the shape of one-half of a circle.

[0071] A method for locating a target by a wall metal detector comprises the following steps:

[0072] Introducing current into the first receiving coil L2 and the third receiving coil L4, so that the first receiving coil L2 and the third receiving coil L4 form a group of receiving coils; the first receiving coil L2 and the third receiving coil L4 respectively generate induction signals;

[0073] connecting the third receiving coil L4, the first compensating coil L5 and the second compensating coil L6 to compensate for the induction signal generated by the third receiving coil L4;

[0074] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b, so that when there is no metal target on the wall, the induction signals generated by the first receiving coil (L2) and the third receiving coil (L4) are balanced;

[0075] When there is a metal target on the wall, if the metal target is located on the side of the third receiving coil L4, the induction signal of the third receiving coil L4 is greater than the induction signal of the first receiving coil L2; if the metal target is located on the side of the first receiving coil L2, the induction signal of the first receiving coil L2 is greater than the induction signal of the third receiving coil L4;

[0076] Current is introduced into the second receiving coil L3 and the third receiving coil L4, and the windings of the coil L3 and the third receiving coil L4 are opposite; the second receiving coil L3 and the third receiving coil L4 form a group of receiving coils; the second receiving coil L3 and the third receiving coil L4 respectively generate induction signals, and the strengths of the induction signals generated by the second receiving coil L3 and the induction signals generated by the third receiving coil L4 are compared to determine the size of the metal target.

[0077] Furthermore, the method further comprises the following steps:

[0078] The third receiving coil L4, the first compensating coil L5, the second compensating coil L6, the third compensating coil L7, and the fourth compensating coil L8 are connected to compensate for the induction signal generated by the third receiving coil L4; the outer ring L5a and the inner ring L5b are switched; the outer ring L6a and the inner ring L6b are switched; the outer ring L7a and the inner ring L7b are switched; the outer ring L8a and the inner ring L8b are switched; so that when there is no metal target on the wall, the induction signals generated by the first receiving coil L2 and the third receiving coil L4 are balanced.

[0079] Embodiment 2, as Figure 5 and Figure 6 As shown, a wall metal detector includes a housing, a power supply, a controller, a transmitting coil L1, a receiving coil, and a compensation coil; characterized in that the receiving coil includes a first receiving coil L2, a second receiving coil L3 and a third receiving coil L4;

[0080] The first receiving coil L2 and the third receiving coil L4 are symmetrically arranged on the left and right sides of the transmitting coil L1; and the winding direction of the first receiving coil L2 is opposite to that of the third receiving coil L4; the first receiving coil L2 can be connected with the third receiving coil L4 to form a receiving circuit for detecting the left and right directions of the wall metal;

[0081] The second receiving coil L3 is arranged outside the first receiving coil L2 and the third receiving coil L4, and the winding direction of the second receiving coil L3 is opposite to that of the first receiving coil L2; the second receiving coil L3 is connected with the first receiving coil L2 to form a receiving circuit for judging the strength of the induction signal.

[0082] A method for locating a target by a wall metal detector comprises the following steps:

[0083] Introducing current into the first receiving coil L2 and the third receiving coil L4, the first receiving coil L2 and the third receiving coil L4 form a group of receiving coils; the first receiving coil L2 and the third receiving coil L4 generate induction signals respectively;

[0084] connecting the third receiving coil L4, the first compensation coil L5 and the second compensation coil L6 to compensate for the induction signal generated by the third receiving coil L4;

[0085] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b, so that when there is no metal target on the wall, the induction signals generated by the first receiving coil L2 and the third receiving coil L4 are balanced;

[0086] When there is a metal target on the wall, if the metal target is located on the side of the third receiving coil L4, the induction signal of the third receiving coil L4 is greater than the induction signal of the first receiving coil L2; if the metal target is located on the side of the first receiving coil L2, the induction signal of the first receiving coil L2 is greater than the induction signal of the third receiving coil L4;

[0087] Current is introduced into the second receiving coil L3 and the first receiving coil L2, and the second receiving coil L3 and the first receiving coil L2 are wound in opposite directions; the second receiving coil L3 and the first receiving coil L2 form a group of receiving coils; the second receiving coil L3 and the first receiving coil L2 respectively generate induction signals, and the induction signals generated by the second receiving coil L3 are compared with the induction signals generated by the first receiving coil L2 to determine the size of the metal target.

[0088] Embodiment 3, as Figure 7 and Figure 8As shown, a wall metal detector further includes a fourth receiving coil L21 and a fifth receiving coil L41; the fourth receiving coil L21 and the fifth receiving coil L41 are symmetrically arranged on the upper and lower sides of the transmitting coil L1; the winding direction of the fourth receiving coil L21 is opposite to that of the fifth receiving coil L41; the fourth receiving coil L21 can be connected with the fifth receiving coil L41 to form a receiving circuit for detecting the upper and lower positions of the wall metal.

[0089] When there is no metal target in the wall, the induction signal generated by the fourth receiving coil L21 is balanced with the induction signal generated by the fifth receiving coil L41; when the metal target is located on one side of the fifth receiving coil L41, the induction signal of the fifth receiving coil L41 is greater than the induction signal of the fourth receiving coil L21; when the metal target is located on one side of the fourth receiving coil L21, the induction signal of the fourth receiving coil L21 is greater than the induction signal of the fifth receiving coil L41.

[0090] A method for locating a target with a wall metal detector, further comprising the following steps: introducing current into the fourth receiving coil L21 and the fifth receiving coil L41, wherein the fourth receiving coil L21 and the fifth receiving coil L41 form a group of receiving coils; the fourth receiving coil L21 and the fifth receiving coil L41 respectively generate induction signals;

[0091] connecting the fifth receiving coil L41, the first compensation coil L5 and the second compensation coil L6 to compensate for the induction signal generated by the fifth receiving coil L41;

[0092] Switching the outer ring L5a and the inner ring L5b; switching the outer ring L6a and the inner ring L6b; switching so that when there is no metal target on the wall, the induction signals generated by the fourth receiving coil L21 and the fifth receiving coil L41 are balanced;

[0093] When there is a metal target on the wall, if the metal target is located on the side of the fifth receiving coil L41, the induction signal of the fifth receiving coil L41 is greater than the induction signal of the fourth receiving coil L21; if the metal target is located on the side of the fourth receiving coil L21, the induction signal of the fourth receiving coil L21 is greater than the induction signal of the fifth receiving coil L41.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wall metal detector, comprising a housing, a power supply, a controller, a transmitting coil (L1), a receiving coil and a compensation coil; characterized in that: The receiving coil comprises a first receiving coil (L2), a second receiving coil (L3) and a third receiving coil (L4); the compensation coil is connected in series in a loop formed by the receiving coils; The first receiving coil (L2) and the third receiving coil (L4) are symmetrically arranged on the left and right sides of the transmitting coil (L1); and the winding direction of the first receiving coil (L2) is opposite to that of the third receiving coil (L4); the first receiving coil (L2) can be connected with the third receiving coil (L4) to form a receiving circuit for detecting the left and right directions of the metal wall; The second receiving coil (L3) is arranged outside the first receiving coil (L2) and the third receiving coil (L4), and the winding direction of the second receiving coil (L3) is opposite to that of the third receiving coil (L4); the second receiving coil (L3) can be connected with the third receiving coil (L4) to form a receiving circuit for judging the strength of the induction signal; It also includes a fourth receiving coil (L21) and a fifth receiving coil (L41); the fourth receiving coil (L21) and the fifth receiving coil (L41) are symmetrically arranged on the upper and lower sides of the transmitting coil (L1); the winding direction of the fourth receiving coil (L21) is opposite to that of the fifth receiving coil (L41); the fourth receiving coil (L21) can be connected with the fifth receiving coil (L41) to form a receiving circuit for detecting the upper and lower positions of the wall metal; The compensation coil surrounds the outside of the transmitting coil (L1), and the compensation coil can be connected in series with any one coil, any two coils or three coils among the first receiving coil (L2), the second receiving coil (L3) or the third receiving coil (L4) to perform signal compensation; the compensation coil comprises a first compensation coil (L5) and a second compensation coil (L6), the first compensation coil (L5) comprises an outer coil (L5a) which is farther from the transmitting coil and an inner coil (L5b) which is closer to the transmitting coil, and the compensation coil (L5) is provided with a switch (K1) for switching the outer coil (L5a) and the inner coil (L5b); the second compensation coil (L6) comprises an outer coil (L6a) which is farther from the transmitting coil and an inner coil (L6b) which is closer to the transmitting coil, and the compensation coil (L6) is provided with a switch (K2) for switching the outer coil (L6a) and the inner coil (L6b).

2. The wall metal detector according to claim 1, characterized in that: The compensation coil further comprises a third compensation coil (L7) and a fourth compensation coil (L8); the third compensation coil (L7) comprises an outer ring (L7a) which is farther from the transmitting coil and an inner ring (L7b) which is closer to the transmitting coil; the third compensation coil (L7) is provided with a switch (K3) for switching the outer ring (L7a) and the inner ring (L7b); the fourth compensation coil (L8) comprises an outer ring (L8a) which is farther from the transmitting coil and an inner ring (L8b) which is closer to the transmitting coil; the compensation coil (L8) is provided with a switch (K4) for switching the outer ring (L8a) and the inner ring (L8b).

3. The wall metal detector according to claim 2, characterized in that: The shapes of the first compensation coil (L5), the second compensation coil (L6), the third compensation coil (L7) and the fourth compensation coil (L8) are different equally divided circles.

4. A wall metal detector, comprising a housing, a power supply, a controller, a transmitting coil (L1), a receiving coil, and a compensation coil; characterized in that: The receiving coil comprises a first receiving coil (L2), a second receiving coil (L3) and a third receiving coil (L4); The first receiving coil (L2) and the third receiving coil (L4) are symmetrically arranged on the left and right sides of the transmitting coil (L1); and the winding direction of the first receiving coil (L2) is opposite to that of the third receiving coil (L4); the first receiving coil (L2) can be connected with the third receiving coil (L4) to form a receiving loop for detecting the left and right directions of the metal wall; the compensation coil is connected in series in the loop formed by the receiving coils; The second receiving coil (L3) is arranged outside the first receiving coil (L2) and the third receiving coil (L4), and the winding direction of the second receiving coil (L3) is opposite to that of the first receiving coil (L2); the second receiving coil (L3) can be connected with the first receiving coil (L2) to form a receiving circuit for judging the strength of the induced signal; It also includes a fourth receiving coil (L21) and a fifth receiving coil (L41); the fourth receiving coil (L21) and the fifth receiving coil (L41) are symmetrically arranged on the upper and lower sides of the transmitting coil (L1); the winding direction of the fourth receiving coil (L21) is opposite to that of the fifth receiving coil (L41); the fourth receiving coil (L21) can be connected with the fifth receiving coil (L41) to form a receiving circuit for detecting the upper and lower positions of the wall metal; The compensation coil surrounds the outside of the transmitting coil (L1), and the compensation coil can be connected in series with any one coil, any two coils or three coils among the first receiving coil (L2), the second receiving coil (L3) or the third receiving coil (L4) to perform signal compensation; the compensation coil comprises a first compensation coil (L5) and a second compensation coil (L6), the first compensation coil (L5) comprises an outer ring (L5a) farther from the transmitting coil and an inner ring (L5b) closer to the transmitting coil, and the compensation coil (L5) is provided with a switch (K1) for switching the outer ring (L5a) and the inner ring (L5b); the second compensation coil (L6) comprises an outer ring (L6a) farther from the transmitting coil and an inner ring (L6b) closer to the transmitting coil, and the compensation coil (L6) is provided with a switch (K2) for switching the outer ring (L6a) and the inner ring (L6b); The compensation coil further comprises a third compensation coil (L7) and a fourth compensation coil (L8); the third compensation coil (L7) comprises an outer ring (L7a) which is farther from the transmitting coil and an inner ring (L7b) which is closer to the transmitting coil; the third compensation coil (L7) is provided with a switch (K3) for switching the outer ring (L7a) and the inner ring (L7b); the fourth compensation coil (L8) comprises an outer ring (L8a) which is farther from the transmitting coil and an inner ring (L8b) which is closer to the transmitting coil; the compensation coil (L8) is provided with a switch (K4) for switching the outer ring (L8a) and the inner ring (L8b).

5. The wall metal detector according to claim 4, characterized in that: The shapes of the first compensation coil (L5), the second compensation coil (L6), the third compensation coil (L7) and the fourth compensation coil (L8) are different equally divided circles.

6. A method for locating a target using the wall metal detector according to claim 1, comprising the following steps: Current is introduced into the first receiving coil (L2) and the third receiving coil (L4), so that the first receiving coil (L2) and the third receiving coil (L4) form a group of receiving coils; the first receiving coil (L2) and the third receiving coil (L4) respectively generate induction signals; connecting the third receiving coil (L4), the first compensating coil (L5) and the second compensating coil (L6) to compensate for the induction signal generated by the third receiving coil (L4); Switching the outer ring (L5a) and the inner ring (L5b); switching the outer ring (L6a) and the inner ring (L6b) so that when there is no metal target on the wall, the induction signals generated by the first receiving coil (L2) and the third receiving coil (L4) are balanced; When there is a metal target on the wall, if the metal target is located on one side of the third receiving coil (L4), the induction signal of the third receiving coil (L4) is greater than the induction signal of the first receiving coil (L2); if the metal target is located on one side of the first receiving coil (L2), the induction signal of the first receiving coil (L2) is greater than the induction signal of the third receiving coil (L4); Current is introduced into the second receiving coil (L3) and the third receiving coil (L4), and the windings of the coils L3 and L4 are opposite; the second receiving coil L3 and the third receiving coil (L4) form a group of receiving coils; the second receiving coil (L3) and the third receiving coil (L4) respectively generate induction signals, and the induction signals generated by the second receiving coil (L3) are compared with the induction signals generated by the third receiving coil (L4) to determine the size of the metal target; Introducing current into the fourth receiving coil (L21) and the fifth receiving coil (L41), so that the fourth receiving coil (L21) and the fifth receiving coil (L41) form a group of receiving coils; the fourth receiving coil (L21) and the fifth receiving coil (L41) respectively generate induction signals; connecting the fifth receiving coil (L41), the first compensation coil (L5) and the second compensation coil (L6) to compensate for the induction signal generated by the fifth receiving coil (L41); Switching the outer ring (L5a) and the inner ring (L5b); switching the outer ring (L6a) and the inner ring (L6b); switching so that when there is no metal target on the wall, the induction signals generated by the fourth receiving coil (L21) and the fifth receiving coil (L41) are balanced; When there is a metal target on the wall, if the metal target is located on one side of the fifth receiving coil (L41), the induction signal of the fifth receiving coil (L41) is greater than the induction signal of the fourth receiving coil (L21); if the metal target is located on one side of the fourth receiving coil (L21), the induction signal of the fourth receiving coil (L21) is greater than the induction signal of the fifth receiving coil (L41).

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