CN212433431U

CN212433431U - Wall detector

Info

Publication number: CN212433431U
Application number: CN202021168818.1U
Authority: CN
Inventors: 王振兴
Original assignee: Shenzhen Dobiy Electronic Co ltd
Current assignee: Shenzhen Changmaoxiang Electronics Co ltd
Priority date: 2020-01-04
Filing date: 2020-06-22
Publication date: 2021-01-29
Anticipated expiration: 2030-06-22
Also published as: CN111812722A; CN212255734U; WO2021135092A1

Abstract

A wall body detecting instrument comprises a shell and a wall body detecting coil, wherein the wall body detecting coil is positioned in the shell and used for detecting a metal target; the wall detection coil comprises at least one concentric annular transmitting wall detection coil L1, at least one first annular receiving wall detection coil and at least one second annular receiving wall detection coil L4, which are inductively coupled with each other; wherein the first receiving wall detection coil and the second receiving wall detection coil are in a series relationship; the annular first receiving wall detection coil is constructed as two identical geometric left and right coils L2 and L3, the winding direction of the left and right coils L2 and L3 being opposite to the winding direction of the second receiving wall detection coil L4.

Description

Wall detector

Technical Field

The utility model relates to a metal detection technology field, concretely relates to multi-functional and fix a position rapid accurate wall body detection instrument.

Background

In the industries of building, decoration, machining and the like, a large number of operations such as leveling, marking, detection of the position of a wood beam in a wall, an alternating current live wire, a metal object, measurement of the relative moisture content of the wall, measurement of the area, the volume and the distance of a room and the like need to be carried out, and the laser marking instrument, the laser distance measuring instrument, the detector in the wall and the wall moisture measuring instrument which are commonly used at present only can carry out single operation due to single function, so that a plurality of instruments are required to be matched for use, and the operation is very inconvenient. At present, although simple combined products exist, the functions are not complete, the precision is low, and the structure is not reasonable.

Patent No. 201310078120 discloses a multifunctional wall detector. The device comprises five parts: the third part is a metal detection circuit which is formed by sequentially connecting a transmitting winding 100, a current resonance circuit 110, a differential receiving coil 9, an amplifying circuit 393, a filter circuit 394 and a bias circuit 395 in series. The metal detection function is implemented by using the transmitting coil, 100, the differential receiving coil 9, the trimming coil 12, the filter circuit 394 and the bias circuit 395. The transmitting winding 100 is a self-winding coil, and is formed by uniformly winding a common enameled wire 101 on a framework 106, and has a certain inductance value. When the current resonant circuit 110 is connected to the first-second-hundredth capacitor 102, the current resonant circuit can be formed. The excitation signal 103 of the resonant circuit is derived from a square wave signal generated by a controller timer module, the frequency and phase of which is program controlled. The generated square wave is smoothed by a one hundred four resistor 104 and a one hundred five capacitor 105.

The current in the coil can generate a magnetic field, which is linked with the differential receiving coil 9 to generate an induction signal output on the differential receiving coil 9. Because the differential receiving coil 9 adopts a differential coil receiving mode, when no metal object to be detected exists around the instrument, the output signal of the receiving coil can be ensured to be 0 through the parameter design of the receiving coil, and the differential coil is in a balanced state at the moment. When there are metallic objects around the instrument, the metallic objects will affect the distribution of the electromagnetic field, resulting in a change of the magnetic field flux of the differential receiving coil 9, and finally in a change of the voltage value and phase value of the output signal.

The utility model discloses a differential receiving coil has adopted the PCB coil, and differential receiving coil all designs on double-deck circuit board. In order to ensure the balanced state of the differential receiving coil, coils with different winding directions need to be designed to be connected in series. Therefore, the differential coil of the present invention includes the following four parts: a first receiving coil group 8, a second receiving coil 9, a third receiving coil 10, and a fourth receiving coil 11. The four receiving coils are connected in series and are concentric with the transmitting winding. The winding directions of the first receiving coil group 8 and the fourth receiving coil 11 are the same, and the winding directions of the second receiving coil group 9 and the third receiving coil group 10 are opposite. Therefore, through reasonable design of the coil, the sum of the magnetic fluxes of the coil can be ensured to be zero under the condition of no measured object. The design of the trimming coil 12 ensures that a better equilibrium state is still achieved in the presence of processing errors in the dimensions of the circuit board. The trimming coil 12 is connected in series between the third receiving coil 10 and the fourth receiving coil 11. The trimming coil 12 consists of two concentric coils running in the same direction but with different radii. The smaller radius is referred to as inner radius 135 and the larger radius is referred to as outer radius 136. The two coils are divided into four sections: the angles of the first section 141, the second section 142, the third section 143 and the fourth section 144 are 24 degrees, 48 degrees, 96 degrees and 192 degrees in sequence. Through 4 pairs of MOS tube switches: the third MOS transistor switch 150, the fourth MOS transistor switch 151, the fifth MOS transistor switch 152 and the sixth MOS transistor switch 153 gate whether the arc of the above-mentioned section is the inner circle or the outer circle to be connected in series into the receiving coil. The receiving areas surrounded by the arcs with different radiuses are different, so that the radians with different angles are selected to be connected into the receiving coil, and the receiving area of the receiving coil can be changed. Therefore, the purpose of fine adjustment of the differential coil can be achieved through gating of the MOS tube, so that the balance of the differential coil is ensured. Whether the differential coil reaches the balanced state or not directly affects the detection range of the instrument, so the design of the fine tuning coil in the balanced coil is very important.

The output signal of the detection coil 390 is mixed with a large amount of noise signals, and the signal itself is very weak. In order to achieve the purpose of metal detection, the utility model designs a signal processing circuit for handle output signal. The circuit is divided into an amplifying circuit 393, a filter circuit 394 and a bias circuit 395 at the later stage, wherein the amplifying circuit 393 is an in-phase amplifying circuit, and the filter circuit 394 is an infinite gain filter circuit.

The amplification part adopts a first operational amplifier 391 with the model number of TLC2272, and the ratio of the fourth hundred zero first resistor 401 and the fourth hundred zero second resistor 402 determines the amplification factor of the amplifier. The filter is an infinite gain feedback filter designed based on the second operational amplifier 392 and is model TLC 2272. The first operational amplifier 391 used by the non-inverting amplifier and the second operational amplifier 392 used by the filter are integrated in the same chip. The non-inverting input end of the amplifying circuit adopts an LC filter circuit and is composed of a patch inductor 416 and a patch capacitor 420, the fourth hundred-zero one resistor 401 of the input resistor of the amplifier and the fourth hundred-zero two resistor 402 of the feedback resistor determine the signal amplification factor, and the fourth hundred-fifteen capacitor 415 is a small capacitor for frequency compensation. The fourth hundred and eighteenth capacitor 418 is a standing capacitor, the fourth hundred and nineteen resistor 419 is a matching resistor, and the signal is output to the filter. By selecting the four hundred eleven resistor 411, the four hundred twelve resistor 412, the four hundred thirteen capacitor 413 and the four hundred fourteen capacitor 414, the cut-off frequency of the filter can be obtained. The cut-off frequency of the filter circuit is consistent with the frequency of the excitation signal and is 5 KHz. To collect the output signal, a dc component needs to be added to the signal to make the signal voltage within the conversion range of the AD adaptation module 405. The dc component is obtained by dividing the voltage by the fourth hundred and seven resistor 407 and the fourth hundred and eight resistor 408. The output signal enters the fourth hundred and four capacitors 404 without a dc component, and the fourth hundred and nineteen resistors 419 and the fourth hundred and ten capacitors 410 form an RC low-pass filter.

And processing the data obtained by the AD sampling module in the controller by adopting an FFT algorithm to calculate the phase of the output signal. Because the frequency of the signal is fixed to be 5KHz, the phase information of the signal is obtained by adopting a fixed-point FFT algorithm, the phase is compared with the phase of the square wave signal, and the advance or the lag of the phase reflects the magnetic conductivity of the measured object. Since ferrous metal and non-ferrous metal have different magnetic permeability, it is possible to recognize whether the detected object is ferrous metal or non-ferrous metal by such difference.

The utility model discloses a realize that the procedure flow of metal detection does, after the instrument is started, when the user selects the metal to survey the function, get into the metal and survey the state, the controller sends excitation square wave signal, makes transmission winding work at the electric current resonance state. And carrying out AD sampling and recording the phase information of the square wave signal at the moment. And after sampling is finished, processing the obtained data by methods such as mean filtering, middle finger filtering and the like. And calculating the phase information of the signal through an FFT algorithm module. The difference between the signal phase and the square wave phase is obtained and the fixed phase shift of the circuit is subtracted from the result to obtain the final result. The measurements are repeated a number of times to finally obtain a phase mean 208. And when the absolute value of the phase mean value exceeds a certain threshold value, retaining the phase information and indicating that a metal object exists. And if the phase mean value is smaller than a certain threshold value, clearing the display information and measuring again. And if the object to be detected exists, indicating the approximate strength information of the metal object through a built-in fitting formula, and judging whether the object to be detected belongs to ferrous metal or non-ferrous metal through the lead-lag of the phase information. And comparing the phase information obtained by the current measurement with the previous measurement result, and judging the central position of the measured object if the absolute value of the phase is obviously reduced. And setting a central position judgment mark by software, and correcting relevant parameters of a central position fitting formula built in the controller by using the phase information at the moment. And then, the obtained phase information is directly displayed by using the intensity information and the central position in one measurement. And if the absolute value of the obtained phase mean value is smaller than a certain threshold value in a certain measurement, the measurement is quitted, the stored data is emptied, and another measurement is started.

Above-mentioned technical scheme can the fast switch-over measurement mode, conveniently carries out laser marking and wall inner structure and surveys, and is multiple functional. However, the inventor finds that the technical scheme is complex in structure and is not beneficial to reducing the cost. And the specific position of the metal object cannot be quickly and accurately located.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an overcome the defect among the above prior art, provide a wall body detection instrument for fixing a position metal object efficient, that the component is few, with low costs to and with the method at this kind of wall body detection instrument location metal target center.

The utility model adopts the technical scheme as follows: a wall body detecting instrument comprises a shell and a wall body detecting coil, wherein the wall body detecting coil is positioned in the shell and used for detecting a metal target;

the wall detection coil comprises at least one concentric annular transmitting wall detection coil L1, at least one first annular receiving wall detection coil and at least one second annular receiving wall detection coil L4, which are inductively coupled with each other; wherein the first receiving wall detection coil and the second receiving wall detection coil are in a series relationship;

the annular first receiving wall detection coil is constructed as two identical geometric left coil L2 and right coil L3, preferably with the left coil L2 and right coil L3 surrounding the outer periphery of the annular transmitting wall detection coil L1; the winding directions of the left coil L2 and the right coil L3 are opposite to the winding direction of the second receiving wall detection coil L4; if the L4 is a forward coil, then L2 and L3 are reverse coils;

the left coil L2 and the second receiving wall detection coil L4 are connected to form a left receiving loop; the right coil L3 and the second receiving wall detection coil L4 are connected to form a right receiving loop; the projection of the transmitting wall detection coil L1, the left coil L2, the right coil L3, and the second receiving wall detection coil L4 are the same plane.

Further, the wall body detection instrument still includes laser module and the support module of throwing the line, laser module and the support module of throwing the line all are located in the casing, laser module of throwing the line is used for launching the laser line, the support module is used for supporting laser module of throwing the line.

Preferably, the transmitting wall detection coil L1 has a transmitting frequency of 1-10 KHZ.

Preferably, the annular first receiving wall detection coil is configured as four identical geometric left coil L2, right coil L3, upper coil L5, and lower coil L6, preferably with the left coil L2, right coil L3, upper coil L5, and lower coil L6 surrounding the outer periphery of the annular transmitting wall detection coil L1; the winding directions of the left coil L2, right coil L3, upper coil L5 and lower coil L6 are opposite to the winding direction of the second receiving wall detection coil L4; (if L4 is a forward coil, then L2, L3, L5, and L6 are reverse coils);

the left coil L2 and the second receiving wall detection coil L4 are connected to form a left receiving loop; the right coil L3 and the second receiving wall detection coil L4 are connected to form a right receiving loop; the upper coil L5 and the second receiving wall detection coil L4 are connected to form an upper side receiving loop; the lower coil L6 and the second receiving wall detection coil L4 are connected to form a lower side receiving loop;

the transmission wall body detection coil L1, coil L5 on left coil L2, right coil L3 and coil L6 down, and the projection of second reception wall body detection coil L4 is coplanar.

Preferably, the annular first receiving wall detection coil is configured as six identical geometric left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, lower right coil L8, preferably the left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, and lower right coil L8 surrounding the periphery of the annular transmitting wall detection coil L1; the winding directions of the left coil L2, the right coil L3, the upper coil L5, the lower coil L6, the left upper coil L7 and the right lower coil L8 are opposite to the winding direction of the second receiving wall detection coil L4; (if L4 is a forward coil, then L2, L3, L5, L6, L7, and L8 are reverse coils);

the left coil L2 and the second receiving wall detection coil L4 are connected to form a left receiving loop; the right coil L3 and the second receiving wall detection coil L4 are connected to form a right receiving loop; the upper coil L5 and the second receiving wall detection coil L4 are connected to form an upper side receiving loop; the lower coil L6 and the second receiving wall detection coil L4 are connected to form a lower side receiving loop; the upper left coil L7 and the second receiving wall detection coil L4 are connected to form an upper left receiving loop; the right lower coil L8 and the second receiving wall detection coil L4 are connected to form a right lower side receiving loop;

launch wall body detection coil L1, left coil L2, right coil L3 go up coil L5, lower coil L6, upper left coil L7 and lower right coil L8 and the projection of wall body detection coil L4 is the coplanar is received to the second.

The method for positioning the metal target center by the wall body detector comprises the following steps:

when the wall body has a metal target, the L2 and the L4 generate a first induction signal, and the L3 and the L4 generate a second induction signal; if the first sensing signal is equal to the second sensing signal, outputting a signal indicating that the metal target is located at the central position corresponding to the detector;

if the first induction signal is not equal to the second induction signal, amplifying the first induction signal and connecting the first induction signal to a left receiving loop, and amplifying the second induction signal and connecting the second induction signal to a right receiving loop; and comparing the amplitude and the phase of the change of the first induction signal and the second induction signal, wherein the output signal indicates that the metal target is positioned on one side with large amplitude change or large phase change.

A method for positioning a metal target center by a wall detector comprises the following steps: when the wall body has a metal target, the L2 and the L4 generate a first induction signal, the L3 and the L4 generate a second induction signal, the L5 and the L4 generate a third induction signal, and the L6 and the L4 generate a fourth induction signal;

if the first sensing signal is equal to the second sensing signal, outputting a signal indicating that the metal target is positioned at the center position of the left and right directions corresponding to the detector;

if the first induction signal is not equal to the second induction signal, amplifying the first induction signal and connecting the first induction signal to a left receiving loop, and amplifying the second induction signal and connecting the second induction signal to a right receiving loop; comparing the amplitude and the phase of the change of the first induction signal and the second induction signal, and outputting a signal indicating that the metal target is positioned on one side with large amplitude change or large phase change;

if the third induction signal is equal to the fourth induction signal, outputting a signal indicating that the metal target is located at the central position in the vertical direction corresponding to the detector;

if the third induction signal is not equal to the fourth induction signal, amplifying the third induction signal and connecting the third induction signal to the upper side receiving loop, and amplifying the fourth induction signal and connecting the fourth induction signal to the lower side receiving loop; and comparing the amplitude and the phase of the change of the third induction signal and the fourth induction signal, wherein the output signal indicates that the metal target is positioned on one side with large amplitude change or large phase change.

A method for positioning a metal target center by using a wall detector comprises the following steps: when the wall body has a metal target, the L2 and the L4 generate a first induction signal, the L3 and the L4 generate a second induction signal, the L5 and the L4 generate a third induction signal, and the L6 and the L4 generate a fourth induction signal; the L7, L4 generates a fifth sensing signal, and the L8, L4 generates a sixth sensing signal;

if the first sensing signal is equal to the second sensing signal, outputting a signal indicating that the metal target is positioned at the center position of the left and right directions corresponding to the detector; if the first induction signal is not equal to the second induction signal, amplifying the first induction signal and connecting the first induction signal to a left receiving loop, and amplifying the second induction signal and connecting the second induction signal to a right receiving loop; comparing the amplitude and phase of the first and second induced signal changes; the output signal indicates that the metal target is positioned on one side with large amplitude change or large phase change;

if the third induction signal is not equal to the fourth induction signal, amplifying the third induction signal and connecting the third induction signal to the upper side receiving loop, and amplifying the fourth induction signal and connecting the fourth induction signal to the lower side receiving loop; comparing the amplitude and phase of the third and fourth sensing signal changes; the output signal indicates that the metal target is positioned on one side with large amplitude change or large phase change;

if the fifth sensing signal is equal to the sixth sensing signal, outputting a signal indicating that the metal target is positioned at the center position of the left upper side and the right lower side corresponding to the detector;

if the fifth induction signal is not equal to the sixth induction signal, amplifying and connecting the fifth induction signal into a left upper side receiving loop, and amplifying and connecting the sixth induction signal into a right lower side receiving loop; comparing the amplitude and phase of the change of the fifth sensing signal and the sixth sensing signal; the output signal indicates that the metal target is located on the side where the amplitude variation is large or the phase variation is large.

Further, the method comprises the following steps: and when the metal target is detected to be positioned at the central position corresponding to the detector, starting the laser demarcation module to indicate the position of the metal target.

Further, the method comprises the following steps: and starting BUZZ sound prompt or alarm when the metal target is detected to be positioned at the central position corresponding to the detecting instrument.

The beneficial effects of the utility model reside in that: first, the first ingenious receiving wall detection coil of the present invention is configured in an annular shape, and the second receiving wall detection coil is configured in two left coils L2 and right coils L3 with the same geometric shape, and at the same time, the left coils L2 and right coils L3 surround the periphery of the annular transmitting wall detection coil L1; configuring the winding directions of the left and right coils L2 and L3 to be opposite to the winding direction of the second reception wall detection coil L4; in this manner, when no metal target is present, the magnetic influence of the transmitting wall detection coil is eliminated in the receiving wall detection coil path, thus minimizing the magnetic influence of the metal detection circuit on the other circuits of the detector.

Second, when having metal object around the wall body detection instrument, the utility model discloses ingenious receive wall body detection coil with the second construct four or six the same geometric shape's coil encircle in annular emission wall body detection coil L1's periphery has improved detection instrument location metal object's sensitivity and accuracy greatly.

Drawings

Fig. 1 is a schematic structural diagram of a wall body detector provided in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a wall detection coil in the wall detector provided in embodiment 1 of the present invention;

fig. 3 is a schematic circuit diagram of a method for positioning a metal target center by using a wall detector in embodiment 1 of the present invention.

Fig. 4 is a schematic structural diagram of a wall detection coil in a wall detector provided in embodiment 2 of the present invention;

fig. 5 is a schematic structural diagram of a wall detection coil in the wall detector provided in embodiment 3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The terms "first", "second", "third", etc. in the present application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," "third," etc. may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. All directional indicators (such as upper, lower, left, right, front, and rear … …) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

Example 1

Referring to fig. 1, 2 and 3, a wall detector includes a housing 10, a laser projection module 20, a wall detection coil 30 and a support module 40, wherein the laser projection module and the wall detection coil are both located in the housing, the laser projection module is used for emitting laser beams, the wall detection coil is used for detecting metal targets, and the support module is used for supporting the laser projection module;

the wall detection coil 30 comprises at least one concentric annular transmitting wall detection coil L1, at least one first annular receiving wall detection coil, and at least one second annular receiving wall detection coil L4 inductively coupled to each other; wherein the first receiving wall detection coil and the second receiving wall detection coil are in a series relationship;

the transmitting wall coil is used for transmitting electromagnetic signals to the air to form an alternating magnetic field; the first receiving wall detection coil and the second receiving wall detection coil are connected to form a receiving wall detection coil passage; and the winding directions of the first receiving wall detection coil and the second receiving wall detection coil are opposite.

The annular first receiving wall detection coil is constructed as two left coil L2 and right coil L3 of the same geometry, preferably the left coil L2 and right coil L3 are semi-circular; the winding directions of the left coil L2 and the right coil L3 are opposite to the winding direction of the second receiving wall detection coil L4; if L4 is a forward coil, L2 and L3 are reverse coils); the left coil L2 and the second receiving wall detection coil L4 are connected to form a left receiving loop; the right coil L3 and the second receiving wall detection coil L4 are connected to form a right receiving loop; the projection of the transmitting wall detection coil L1, the left coil L2, the right coil L3, and the second receiving wall detection coil L4 are the same plane.

The transmitting frequency of the transmitting wall detection coil L1 is 1-10 KHZ.

Example 2

As shown in fig. 4, a wall detector was the same as in example 1. In contrast, the annular first receiving wall detection coil is configured as four identical geometric left coil L2, right coil L3, upper coil L5, and lower coil L6, preferably the left coil L2, right coil L3, upper coil L5, and lower coil L6 are quarter-circle rings; the winding directions of the left coil L2, right coil L3, upper coil L5 and lower coil L6 are opposite to the winding direction of the second receiving wall detection coil L4; if L4 is a forward coil, then L2, L3, L5, and L6 are reverse coils;

Example 3

As shown in fig. 5, a wall detector was the same as in example 1. Stated differently, the annular first receiving wall detection coil is constructed as six identical geometric shapes of left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, lower right coil L8, preferably the left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, and lower right coil L8 are one-sixth circular ring shapes; the winding directions of the left coil L2, the right coil L3, the upper coil L5, the lower coil L6, the left upper coil L7 and the right lower coil L8 are opposite to the winding direction of the second receiving wall detection coil L4; if L4 is a forward coil, then L2, L3, L5, L6, L7, and L8 are reverse coils;

As shown in fig. 2 and 3, a method for locating a metal target center using a wall detector includes the following steps:

As shown in fig. 4, a method for positioning a metal target center by a wall detector includes the following steps: when the wall body has a metal target, the L2 and the L4 generate a first induction signal, the L3 and the L4 generate a second induction signal, the L5 and the L4 generate a third induction signal, and the L6 and the L4 generate a fourth induction signal;

As shown in fig. 5, a method for locating a metal target center by using a wall detector includes the following steps: when the wall body has a metal target, the L2 and the L4 generate a first induction signal, the L3 and the L4 generate a second induction signal, the L5 and the L4 generate a third induction signal, and the L6 and the L4 generate a fourth induction signal; the L7, L4 generates a fifth sensing signal, and the L8, L4 generates a sixth sensing signal;

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A wall body detecting instrument comprises a shell and a wall body detecting coil, and is characterized in that the wall body detecting coil is positioned in the shell and used for detecting a metal target;

the wall detection coil comprises at least one concentric annular transmitting wall detection coil L1, at least one first annular receiving wall detection coil and at least one second annular receiving wall detection coil L4, which are inductively coupled with each other; the first annular receiving wall detection coil and the second annular receiving wall detection coil are in a series connection relationship;

the annular first receiving wall detection coil is constructed as two left coil L2 and right coil L3 of the same geometry, the left coil L2 and right coil L3 surrounding the periphery of the annular transmitting wall detection coil L1; the winding directions of the left coil L2 and the right coil L3 are opposite to the winding direction of the second receiving wall detection coil L4;

2. The wall detector according to claim 1, wherein the wall detector further comprises a laser projection module and a support module, the laser projection module and the support module are both located in the housing, the laser projection module is configured to emit a laser beam, and the support module is configured to support the laser projection module.

3. The wall detector according to claim 1 or 2, wherein the transmitting wall detection coil L1 has a transmitting frequency of 1-10 KHZ.

4. The wall detector of claim 1, wherein said annular first receiving wall detection coil is configured as four identical geometric shapes of a left coil L2, a right coil L3, an upper coil L5, and a lower coil L6, said left coil L2, right coil L3, upper coil L5, and lower coil L6 surrounding the outer periphery of said annular transmitting wall detection coil L1; the winding directions of the left coil L2, right coil L3, upper coil L5 and lower coil L6 are opposite to the winding direction of the second receiving wall detection coil L4;

the upper coil L5 and the second receiving wall detection coil L4 are connected to form an upper side receiving loop; the lower coil L6 and the second receiving wall detection coil L4 are connected to form a lower side receiving loop;

5. The wall detector of claim 1, wherein said annular first receiving wall detection coil is configured as six identical geometric shapes of left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, lower right coil L8, said left coil L2, right coil L3, upper coil L5, lower coil L6, upper left coil L7, and lower right coil L8 surrounding the periphery of said annular transmitting wall detection coil L1; the winding directions of the left coil L2, the right coil L3, the upper coil L5, the lower coil L6, the left upper coil L7 and the right lower coil L8 are opposite to the winding direction of the second receiving wall detection coil L4;

the upper coil L5 and the second receiving wall detection coil L4 are connected to form an upper side receiving loop; the lower coil L6 and the second receiving wall detection coil L4 are connected to form a lower side receiving loop; the upper left coil L7 and the second receiving wall detection coil L4 are connected to form an upper left receiving loop; the right lower coil L8 and the second receiving wall detection coil L4 are connected to form a right lower side receiving loop;