Hand-held detector for metal article identification

Abstract

The utility model discloses a hand-held detector for metal article identification. The hand-held detector comprises a transmitting coil, a receiving coil which is electromagnetically coupled with the transmitting coil, and a single-chip microcomputer. The output end of the receiving coil serves as the first input end of the first operational amplifier. The output end of the digital-to-analog converter module of the single-chip microcomputer serves as the input end of the second operational amplifier, and the output end of the second operational amplifier serves as the second input end of the first operational amplifier. The output end of the first operational amplifier is connected with the input end of the analog-to-digital converter module of the single-chip microcomputer. A digital-to-analog converter module of the single-chip microcomputer is used for generating an offset signal, and the offset signal is subtracted from a receiving coil signal to obtain an input signal of the analog-to-digital converter module. According to the utility model, the signal of the receiving coil is automatically adjusted to an appropriate input signal conforming to the analog-to-digital converter module of the single-chip microcomputer, the assembly production efficiency is improved, and the adaptability is stronger.

Description

TECHNICAL FIELD

[0001] The utility model relates to metal detection technical field especially relates to a metal article identification hand-held detector. BACKGROUND

[0002] The metal detector needs to fine tune the receiving coil and control the amplitude of the receiving coil in a certain small range to reach the initial value requirement during production and assembly due to the structure of the transmitting coil and the receiving coil. The existing technology adjusts the amplitude of the receiving coil by manually adjusting the wire to increase or decrease the magnetic flux through the receiving coil, which causes the voltage amplitude on the receiving coil to change, resulting in low production and assembly efficiency.

[0003] During actual production and assembly, the transmitting coil can be installed at one time, that is, the transmitting coil is installed and fixed with glue. However, the installation of the receiving coil is more complicated. After the receiving coil is simply fixed, the wire of the receiving coil overlapping part with the transmitting coil needs to be adjusted, and the simulated signal voltage of the receiving coil is observed at the same time. When the voltage of the receiving coil falls within the preset range (for example, less than 200mv), the wire of the receiving coil is fixed with glue; the operation is complicated. UTILITY MODEL CONTENT

[0004] The utility model provides a metal article identification hand-held detector, which can improve production efficiency.

[0005] The utility model adopts the following technical scheme:

[0006] The metal article identification hand-held detector comprises a transmitting coil, a receiving coil electromagnetically coupled with the transmitting coil, and a single-chip microcomputer.

[0007] The output end of the receiving coil serves as the first input end of the first operational amplifier; the output end of the digital-to-analog converter module of the single-chip microcomputer serves as the input end of the second operational amplifier, and the output end of the second operational amplifier serves as the second input end of the first operational amplifier; and the output end of the first operational amplifier is connected to the input end of the analog-to-digital converter module of the single-chip microcomputer.

[0008] The digital-to-analog converter module of the single-chip microcomputer is used to generate a cancellation signal, and the input signal of the analog-to-digital converter module is obtained by subtracting the receiving coil signal from the cancellation signal.

[0009] A third operational amplifier is arranged between the receiving coil and the first operational amplifier and used to amplify the signal of the receiving coil.

[0010] The input end of the analog-to-digital converter module of the single-chip microcomputer is connected to the output end of the third operational amplifier.

[0011] As the improvement of the above-mentioned scheme, the single-chip microcomputer comprises a PWM module, an output end of the PWM module is connected to an input end of the power amplifier, and an output end of the power amplifier is connected to the transmitting coil.

[0012] As the improvement of the above-mentioned scheme, the transmitting coil and the receiving coil are partially overlapped.

[0013] Preferably, the transmitting coil and the receiving coil are rectangular respectively.

[0014] Preferably, the transmitting coil and the receiving coil are semicircular respectively, and the two semicircles of one side of the diameter are overlapped.

[0015] As the improvement of the above-mentioned scheme, the single-chip microcomputer is connected to a button for switching on and off, setting a working frequency, a transmitting power, a detection sensitivity, an alarm prompt mode and / or a working mode.

[0016] As the improvement of the above-mentioned scheme, the screen is used for displaying a menu, displaying an alarm object schematic diagram, a current power and a current working mode.

[0017] As the improvement of the above-mentioned scheme, the single-chip microcomputer is connected to a medium carrying an alarm database, and a phase characteristic table is stored in the alarm database.

[0018] Advantages

[0019] 1) The digital-to-analog converter DAC module is arranged to generate a cancellation signal, the cancellation signal is subtracted from a receiving coil signal to obtain an input signal of an analog-to-digital converter module, so that the signal of the receiving coil is automatically adjusted to a suitable input signal of the single-chip microcomputer analog-to-digital converter ADC module, the assembly production efficiency is improved, and the adaptability is stronger.

[0020] 2) The transmitting coil and the receiving coil are partially overlapped in the detection area, compared with the structure that only the receiving coil is arranged in the detection area of the existing handheld detector, or the structure that the transmitting coil and the differential receiving coil are arranged, the scheme that the transmitting coil and the receiving coil are partially overlapped has higher detection sensitivity, and the detection distance reaches 20 cm.

[0021] 3) The single-chip microcomputer compares the phase value of the metal detection signal of the receiving coil with the phase characteristic value in the alarm database, identifies the type of the metal object, and can effectively distinguish a mobile phone from other daily objects. DRAWINGS

[0022] Figure 1a is a circuit structure schematic diagram of a handheld detector for metal object identification provided by the utility model;

[0023] Figure 1b is a circuit structure schematic diagram of a handheld detector for metal object identification provided by the utility model;

[0024] Figure 1c Figure 3 is a circuit structure schematic diagram of the handheld detector for metal article identification provided by the utility model; Figure 2

[0025] Figure 3 Figure 2 is a structure schematic diagram of the position setting of the transmitting coil and the receiving coil of the handheld detector for metal article identification provided by the utility model;

[0026] Figure 4 Figure 1 is an overall assembly view of the handheld detector for metal article identification provided by the utility model. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model.

[0028] Referring to Figure 1a The utility model provides a kind of handheld detector for metal article identification, it includes receiving coil and single-chip microcomputer, the output end of receiving coil is as the first input end of 1 operational amplifier;The digital-analog converter DAC module output end of single-chip microcomputer is as the input end of operational amplifier 2, the output end of operational amplifier 2 is as the second input end of operational amplifier 1;The input end of operational amplifier 1 is connected the input end of the analog-digital converter ADC module of single-chip microcomputer.

[0029] Single-chip microcomputer includes PWM module, the input end of power amplifier is connected the output end of PWM module, the output end of power amplifier is connected transmitting coil.Single-chip microcomputer PWM module, generate the PWM signal (chopper) of sine wave, and the frequency of its sine wave is set through single-chip microcomputer.The amplitude of transmitting signal is adjusted by adjusting the duty ratio of PWM signal.Single-chip microcomputer uses low-power single-chip microcomputer.

[0030] Transmitting coil and receiving coil electromagnetic coupling.

[0031] ​Working Process: The microcontroller's DAC module generates a cancellation signal. During detector initialization, the microcontroller acquires the signal from operational amplifier 1 via the ADC, adjusts the DAC output cancellation signal, and simultaneously sends the receiving coil signal and the output signal from operational amplifier 2 to operational amplifier 1, adjusting them to the optimal cancellation state. To achieve the initial value requirements, the amplitude of the receiving coil is controlled below 200mV. The DAC channel cancels the receiving coil signal. Even if the amplitude of the receiving coil is within a large range, such as less than 500mV, subtracting the cancellation signal from the receiving coil signal yields an input signal that matches the ADC module. This allows the transmitting and receiving coils to be directly fixed without further fine-tuning, thereby improving production efficiency and increasing adaptability.

[0032] The receiving coil sends the detected metal detection signal to operational amplifier 1, which is connected to a microcontroller's ADC module. The ADC module samples, analyzes, and judges the received signal. The microcontroller analyzes the signal and calculates the phase characteristic value of the metal object. The microcontroller is connected to an alarm database or alarm data table that stores the phase characteristic values ​​of common prohibited items (i.e., a phase characteristic table). The phase characteristic value obtained from each sampling analysis is compared with the data in the phase characteristic table to identify and distinguish various prohibited items.

[0033] In another embodiment, see Figure 1b An operational amplifier 3 is placed between the receiving coil and operational amplifier 1 to amplify the signal from the receiving coil, thereby increasing the amplification factor and improving sensitivity.

[0034] In another embodiment, see Figure 1c The output of the third amplifier is connected to the input of the microcontroller's analog-to-digital converter module. Under normal operating conditions, the microcontroller acquires the signal from operational amplifier 1. When a large metal object is detected, causing operational amplifier 1 to saturate, the microcontroller acquires and analyzes the signal from operational amplifier 3.

[0035] See Figure 2In another embodiment, the transmitting coil and the receiving coil partially overlap, filling the detection area 301 of the handheld detector for metal object identification. The detection area is rectangular, using two rectangular coils. Alternatively, the detection area is circular, using two semi-circular coils, with the two halves of the diameter side overlapping each other. During assembly, the transmitting coil 20 and the receiving coil 10 are first fixed, leaving the wires 11 in the overlapping area of the receiving coil 10 for fine adjustment, so that the signal of the receiving coil 10 falls within the sampling range, and then the wires 11 are fixed. Preferably, the transmitting coil 20' and the receiving coil 10' can be partially overlapped in the up-down direction, and the magnetic flux passing through the receiving coil can be adjusted by adjusting the position in the up-down direction, and then the wires 11' in the overlapping area of the receiving coil 10' are adjusted more finely, so that the width of the detection area 301 is shorter, and the overall structure of the detector is more compact and simple.

[0036] Referring to Figure 3 In an alternative embodiment, the single-chip microcomputer is also connected to a display screen 302 for displaying menus, displaying alarm object diagrams, current power, current working mode (mobile phone detection mode, contraband detection mode, full-metal detection mode), etc.

[0037] The handheld detector is provided with three working modes. The mobile phone detection mode is suitable for school campus management, examination entry detection, scientific research and information security control places. The contraband detection mode is suitable for public security inspection in crowded places, improving the efficiency of security inspection. The full-metal detection mode has the highest security level and alarms if a small amount of metal is carried.

[0038] Functions of the handheld detector for metal object identification:

[0039] The handheld detector for metal object identification is used for manual inspection or as a re-inspection tool in combination with a through-type metal detector, and is suitable for places where mobile phone detection doors, contraband detection doors or full-metal detection doors are deployed.

[0040] The first input end of the single-chip microcomputer is connected to a button 303, which is provided with three input buttons for turning on and off, parameter setting, and can set the working frequency, transmission power, detection sensitivity, alarm prompt mode and working mode.

[0041] Alternatively, the first output end of the single-chip microcomputer is connected to a buzzer 304, and the second output end is connected to a vibration motor for alarm prompt function.

[0042] The single-chip microcomputer is also connected to a charging interface, which is provided at the end of the handle, and the handheld part is a battery compartment 305, using a type-c charging interface 306.

[0043] The handheld metal detector distinguishes daily items as mobile phones, keys, belt buckles, etc.

[0044] The above is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, under the premise of can make a number of improvements and refinements, these improvements and refinements also as the protection scope of the present application.

Claims

1. A hand-held detector for metal article identification, characterized in that, The transmitter coil, the receiving coil electromagnetically coupled with the transmitter coil, and a single-chip microcomputer; An output end of the receiving coil is used as a first input end of a first operational amplifier; an output end of a digital-to-analog converter module of the single-chip microcomputer is used as an input end of a second operational amplifier; an output end of the second operational amplifier is used as a second input end of the first operational amplifier; and an output end of the first operational amplifier is connected to an input end of an analog-to-digital converter module of the single-chip microcomputer. The digital-to-analog converter module of the single-chip microcomputer is used to generate a cancellation signal, and the cancellation signal is subtracted from a receiving coil signal to obtain an input signal of the analog-to-digital converter module.

2. The hand-held probe of claim 1, wherein the metal article identification means comprises a metal detector. A third operational amplifier is arranged between the receiving coil and the first operational amplifier.

3. The hand-held metal article identification probe of claim 2 wherein, An output end of the third operational amplifier is connected to an input end of the analog-to-digital converter module of the single-chip microcomputer.

4. The hand-held probe of claim 1, wherein the metal article identification means comprises a metal detector. The single-chip microcomputer comprises a PWM module, an output end of the PWM module is connected to an input end of a power amplifier, and an output end of the power amplifier is connected to the transmitter coil.

5. The hand-held metal article identification probe of claim 1, wherein, The transmitter coil and the receiving coil are partially overlapped.

6. The hand-held metal article identification probe of claim 3, wherein, The transmitter coil and the receiving coil are rectangular.

7. The hand-held metal article identification probe of claim 3, wherein the probe head is configured to be held in a hand of a user and the probe head is configured to be moved by the user to scan the metal article. The transmitter coil and the receiving coil are semicircular, and two semicircles with a diameter and a side are overlapped.

8. The hand-held probe of claim 1, wherein the metal article identification means comprises a metal detector. The single-chip microcomputer is connected to a button for switching on and off, setting a working frequency, a transmitting power, a detection sensitivity, an alarm prompt mode, and / or a working mode.

9. The hand-held probe of claim 1, wherein The single-chip microcomputer is connected to a display screen for displaying a menu, displaying an alarm object schematic diagram, displaying a current power, and displaying a current working mode.

10. A hand-held probe for metal object identification according to any one of claims 1-9, characterized in that, The single-chip microcomputer is connected to a medium carrying an alarm database, and a phase feature table is stored in the alarm database.

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