Mobile phone detector

Abstract

The utility model relates to the technical field of anti-cheating equipment, and particularly discloses a mobile phone detector, which comprises a detection shell, a metal detector, a current detector and a main controller, and is characterized in that the current detector comprises an exciting coil, a measuring coil, an exciting signal generating circuit, a filter circuit, an amplifying circuit and a comparator circuit; the output end of the measuring coil is sequentially connected with a filter circuit, an amplifying circuit and a comparator circuit, the output end of the excitation signal generating circuit and the input end of the comparator circuit, the output end of the comparator circuit is connected with the main controller, and the metal detector detects a metal device. Alternating excitation current generated by the excitation signal generating circuit is input to the excitation coil, the measuring coil induces and generates a corresponding alternating current signal, and the main controller judges whether a metal device is electronic equipment or not by detecting the output level change of the comparator circuit, so that mobile phone equipment hidden in places such as clothes and the like is detected. And the fairness of the examination is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of anti-cheating equipment, and particularly relates to a mobile phone detector. Background Art

[0002] The exam administrator's handheld detector is a tool used to check whether candidates are carrying prohibited items, such as mobile phones, electronic devices, opaque metal stationery and other items that candidates are not allowed to use in the examination room. Before entering the examination room, candidates need to undergo inspection, which usually includes inspection through the exam administrator's handheld detector. The exam administrator's handheld detector is a very effective anti-cheating tool that helps ensure the fairness of the examination.

[0003] The existing handheld detectors are mainly handheld metal detectors, which warn by detecting metal materials in electronic devices and other prohibited items. When in use, metal materials such as belt buckles and clothing metal buckles will trigger alarms. It is impossible to distinguish whether such metals are carrying cheating equipment on site. In actual operation, invigilators usually judge such cases as pure metal and allow candidates to enter the examination room, which poses a risk of cheating equipment flowing into the examination room, affecting the fairness of the examination. In the existing technology, although the mobile phone detection door can effectively detect whether the examinee is carrying electronic devices or other metal materials, due to its large size and weight, the weight is generally more than 50 kilograms, and the volume is more than 2 meters * 0.8 meters * 1.2 meters. It is very difficult to move before and after the exam, and it is difficult to use in every examination room.

[0004] In view of this, the utility model proposes a mobile phone detector to solve the above technical problems. Utility Model Content

[0005] The purpose of the utility model is to provide a mobile phone detector to overcome the problem that the existing handheld detectors for examination staff only detect metal devices and issue alarms, but cannot distinguish whether the alarm is triggered by a mobile phone device or a simple metal object, resulting in mobile phones hidden in clothes not being detected and being carried into the examination room by examinees, affecting the fairness of the examination.

[0006] To achieve the above purpose, the utility model provides a mobile phone detector, comprising:

[0007] A metal detector, which is installed in the detection housing and comprises a metal detection coil, an oscillation circuit and a Hall sensor module, wherein the metal detection coil is connected to an output end of the oscillation circuit;

[0008] A current detector, which is installed in the detection housing and includes a magnetic modulator and an excitation signal generating circuit. The magnetic modulator includes an excitation coil, a high-permeability iron core and a measuring coil. The excitation coil and the measuring coil are respectively wound around two sides of the high-permeability iron core. The output end of the excitation signal generating circuit is connected to the excitation coil.

[0009] A main controller, the input end of the oscillation circuit is connected to the main controller, the input end of the excitation signal generating circuit is connected to the main controller, and the Hall sensor module is connected to the main controller;

[0010] The current detector also includes a filtering circuit, an amplifying circuit and a comparator circuit. The input end of the filtering circuit is connected to the measuring coil, the input end of the amplifying circuit is connected to the output end of the filtering circuit, the output ends of the excitation signal generating circuit and the amplifying circuit are respectively connected to the input end of the comparator circuit, and the output end of the comparator circuit is connected to the main controller.

[0011] Preferably, in the above technical solution, it also includes an audible and visual alarm, and the audible and visual alarm is connected to the main controller.

[0012] Preferably, in the above technical solution, the filtering circuit is a second-order low-pass filter.

[0013] Preferably, in the above technical solution, the excitation signal generating circuit can be a triangle wave, pulse wave and sinusoidal wave excitation current generating circuit.

[0014] Preferably, in the above technical solution, the metal detector also includes a switching switch and a degaussing circuit, the degaussing circuit is connected in series with the metal detection coil through the switching switch, and the control end of the switching switch is connected to the main controller.

[0015] Preferably, in the above technical solution, it also includes a button, and the button is connected to the main controller.

[0016] Compared with the existing technology, the beneficial effects of the utility model are: the utility model detects metal materials through a metal detector, and the excitation signal generating circuit generates an alternating excitation current which is input into the excitation coil. Under the action of the magnetic field force, the measuring coil also induces and generates a corresponding excitation current signal. A charged conductor with a DC current will generate a bias magnetic field in the magnetic field. Under the action of the bias magnetic field, the symmetry of the alternating magnetic flux in the high permeability iron core is affected, causing the waveform symmetry of the current signal induced by the measuring coil to be destroyed. By detecting the difference between the current signal of the measuring coil and the current signal of the input excitation coil, the detected metal object is further confirmed to have a current signal, thereby determining whether it is a mobile phone device, thereby ensuring the fairness of the examination. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0018] Figure 2 This is a schematic diagram of the circuit principle structure of the utility model.

[0019] In the figure: 1-detection shell, 2-sound and light alarm, 3-high magnetic permeability iron core, 4-button, 5-main controller, 6-oscillation circuit, 7-Hall sensor module, 8-excitation signal generating circuit, 9-filter circuit, 10-amplifier circuit, 11-comparator circuit, 12-demagnetization circuit, 13-switching switch, L1-metal detection coil, L2-excitation coil, L3-measuring coil. DETAILED DESCRIPTION

[0020] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0021] like Figure 1 and Figure 2As shown, the mobile phone detector of this embodiment includes a detection shell 1, an audible and visual alarm 2, a button 4, a metal detector, a current detector and a main controller 5, the metal detector, the current detector and the main controller 5 are installed in the detection shell 1, the audible and visual alarm 2 and the button 4 are respectively installed on the detection shell 1, the audible and visual alarm 2 and the button 4 are respectively connected to the main controller 5, the metal detector includes a metal detection coil L1, an oscillation circuit 6 and a Hall sensor module 7, the input end of the oscillation circuit 6 is connected to the main controller 5, the output end of the oscillation circuit 6 is connected to the metal detection coil L1, and the Hall sensor module 7 is connected to the main controller 5. The current detector includes an excitation coil L2, a high permeability iron core 3, a measuring coil L3, an excitation signal generating circuit 8, a filtering circuit 9, an amplifying circuit 10 and a comparator circuit 11. The excitation coil L2 and the measuring coil L3 are respectively wound on both sides of the high permeability iron core 3. The excitation coil L2 is connected to the output end of the excitation signal generating circuit 8, the input end of the excitation signal generating circuit 8 is connected to the main controller 5, the measuring coil L3 is connected to the input end of the filtering circuit 9, the output end of the filtering circuit 9 is connected to the input end of the amplifying circuit 10, the excitation signal generating circuit 10 and the amplifying circuit 11 are connected to the main controller 5, and the measuring coil L3 is connected to the input end of the filtering circuit 9. The output end of the filtering circuit 9 is connected to the input end of the amplifying circuit 10. The output ends of the circuit 12 are respectively connected to the input ends of the comparator circuit 11, and the output ends of the comparator circuit 11 are connected to the main controller 5. In the present embodiment, the filter circuit 9 is preferably a second-order low-pass filter circuit, the oscillation circuit 6 can be a high-frequency pulse generating circuit, the excitation signal generating circuit can be a triangular wave, pulse wave or sinusoidal wave excitation current generating circuit, the main controller 5 can be a STC15f2k60s2 single-chip microcomputer, the Hall sensor module 7 can be a GN3503 linear Hall sensor, and the sound and light alarm 4 can be composed of an LED lamp and a speaker.

[0022] Continue to refer Figure 2 The metal detector in the mobile phone detector of this embodiment further includes a switch 13 and a degaussing circuit 12 . The degaussing circuit 12 is connected in series with the metal detection coil L1 through the switch 13 . The control end of the switch 13 is connected to the main controller 5 .

[0023] The working principle of the utility model is: using the magnetic field to induce eddy currents in the metal object to be detected, and the eddy currents in turn affect the original magnetic field. The main controller 5 controls the oscillation circuit 6 to input a high-frequency pulse signal to the metal detection coil L1, and the metal detection coil L1 generates a strong current, thereby generating a constant alternating magnetic field around the metal detection coil L1. The magnetic field changes of the metal detection coil L1 are collected by the Hall sensor module 7. The Hall sensor module 7 converts the alternating magnetic field of the metal detection coil L1 into a pulse voltage signal and outputs it to the main controller 5 for reception. The main controller 5 detects that the pulse voltage returned by the Hall sensor module 7 is different from the frequency of the oscillation pulse set by the oscillation circuit 6, thereby judging the existence of metal devices. When the main controller 5 After detecting the presence of a metal device, the main controller 5 drives the sound and light alarm 2 to sound and light alarm, specifically, the light flashes, and the loudspeaker broadcasts "metal device detected". Then, the main controller 5 controls the oscillation circuit 6 to stop output, and drives the switching switch 13 to close, and connects the demagnetization circuit 12 to the metal detection coil L1 to demagnetize the metal detection coil L1 and remove the residual current in the metal detection coil L1 to avoid affecting the subsequent current detector measurement. The main controller 5 drives the excitation signal generating circuit 8 to input an alternating excitation current signal to the excitation coil L2 to generate an alternating magnetic field around the excitation coil L2. The alternating magnetic field passes through the high permeability iron core 3. According to the principle of magnetic induction, the number of turns of the excitation coil L2 is equal to that of the measuring coil L3, so that The measuring coil L3 senses the corresponding alternating current signal. Even when the electronic device is turned off, some devices will have current flowing. Since a conductor with direct current has a bias magnetic field in a magnetic field, the bias magnetic field of the conductor will affect the alternating current signal in the measuring coil L3, causing the duty cycle of the positive and negative half-waves of the alternating current signal in the measuring coil L3 to change. The current signal in the measuring coil L3 is processed by the filtering circuit 9 to filter out the high-order harmonic components in the current signal induced by the measuring coil L3. The amplifier circuit 10 amplifies the filtered current signal to amplify the slight changes in the alternating current signal and then inputs it to an input end of the comparator circuit 11. The comparator circuit 11 compares the output of the amplifier circuit 10 with the The alternating current signal and the alternating current signal of the excitation signal generating circuit 8, a reference current source corresponding to the amplification factor of the amplifier circuit 10 is provided at the connection between the excitation signal generating circuit 8 and the comparator circuit 11, the current signal input from the excitation signal generating circuit 8 to the comparator circuit 11 is superimposed and raised, so that the current signal input from the excitation signal generating circuit 8 to the comparator circuit 11 is amplified in the same way as the alternating current signal output from the amplifier circuit 10, the comparator circuit 11 outputs positive and negative level signals to the main controller 5 by comparing the alternating current signals of the excitation signal generating circuit 8, the main controller 5 determines the presence of a mobile phone device by detecting the level change of the comparator 11 output, the main controller 5 drives the sound and light alarm 2 to sound and light alarm,Specifically, the light flashes, and the speaker announces "Mobile device detected". By pressing button 4 to turn on the detector, and releasing button 4 to turn off the detector, the detector is avoided from being turned on for a long time and causing the detector to consume power when it is not working, thus increasing the detector's battery life.

[0024] The utility model can further distinguish whether the detected metal device is an electronic device or other metal device, and can effectively detect mobile phone devices hidden in clothes. It solves the problem that examination staff use traditional examination handheld detectors to simply detect metal materials, but cannot distinguish whether the alarm is triggered by a mobile phone product or simple metal, and the problem that mobile phone products hidden in clothes cannot be detected and are brought into the examination room by candidates, thereby ensuring the fairness of the examination.

[0025] The foregoing description of specific exemplary embodiments of the utility model is for the purpose of illustration and illustration. These descriptions are not intended to limit the utility model to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the utility model and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the utility model and various different options and changes. The scope of the utility model is intended to be limited by the claims and their equivalents.

Claims

1. A mobile phone detector, characterized in that: include: Detection shell; A metal detector, which is installed in the detection housing and comprises a metal detection coil, an oscillation circuit and a Hall sensor module, wherein the metal detection coil is connected to an output end of the oscillation circuit; A current detector, which is installed in the detection housing and includes a magnetic modulator and an excitation signal generating circuit. The magnetic modulator includes an excitation coil, a high-permeability iron core and a measuring coil. The excitation coil and the measuring coil are respectively wound on both sides of the high-permeability iron core. The output end of the excitation signal generating circuit is connected to the excitation coil. A main controller, the input end of the oscillation circuit is connected to the main controller, the input end of the excitation signal generating circuit is connected to the main controller, and the Hall sensor module is connected to the main controller; The current detector also includes a filtering circuit, an amplifying circuit and a comparator circuit. The input end of the filtering circuit is connected to the measuring coil, the input end of the amplifying circuit is connected to the output end of the filtering circuit, the output ends of the excitation signal generating circuit and the amplifying circuit are respectively connected to the input end of the comparator circuit, and the output end of the comparator circuit is connected to the main controller.

2. A mobile phone detector according to claim 1, characterized in that: It also includes an audible and visual alarm, which is connected to the main controller.

3. A mobile phone detector according to claim 1, characterized in that: The filtering circuit is a second-order low-pass filter.

4. A mobile phone detector according to claim 1, characterized in that: The excitation signal generating circuit is a triangle wave generating circuit, a pulse wave generating circuit or a sine wave excitation current generating circuit.

5. A mobile phone detector according to claim 1, characterized in that: The metal detector further comprises a switching switch and a degaussing circuit. The degaussing circuit is connected in series with the metal detection coil via the switching switch. The control end of the switching switch is connected to the main controller.

6. A mobile phone detector according to claim 1, characterized in that: It also includes a button, which is connected to the main controller.

Images