A hard tag magnetic insertion digital quantity control circuit and control method thereof

Abstract

The present invention discloses a hard tag magnetic insertion digital quantity control circuit and a control method thereof, wherein the control circuit comprises a control unit, a signal source unit, a compensation capacitor unit, a sensitive probe, a precision resistor R1, a zero-crossing comparator, and an edge D trigger. The present invention adopts a single coil probe design, which is simple in structure and convenient for installation and debugging. It adopts a phase change characteristic to sense the change in the resonant frequency of the hard tag, which effectively solves the problem that the control accuracy is affected by the change in amplitude as the control signal and the mutual inductance coefficient M between the hard tag and the detection probe changes with the magnetic insertion; the control signal in the circuit is a switch signal, and the control method program design is simple, which effectively improves the control accuracy of the resonant frequency of the hard tag production of the magnetic insertion device.

Description

Technical field:

[0001] The invention belongs to the technical field of production and processing of commodity anti-theft hard labels, and in particular relates to a hard label magnetic insertion digital quantity control circuit and a control method thereof. Background technology:

[0002] In the Electronic Article Surveillance (EAS) system, electronic anti-theft tags can be divided into two categories: soft tags and hard tags according to their structures. Among them, anti-theft hard tags can be further divided into four categories: bottle tags, buckle tags, can tags and other categories. EAS can be divided into radio frequency systems (4.75MHz / 8.2MHz / 10MHz) and acoustic magnetic systems (58KHz) according to their operating frequencies.

[0003] The internal structure of the electronic tag is mainly an LC oscillation circuit. One of the criteria for determining whether a tag is qualified is to see whether the tag resonates within the resonant frequency range. At present, in the production process of hard tags, the resonant frequency of the hard tag is adjusted by inserting a magnetic bar into the frame wound with a coil to adjust the inductance value in the resonant circuit of the hard tag so that the resonant frequency of the series circuit composed of the inductance and capacitance of the hard tag meets the industry requirements. This process is called the magnetic insertion process.

[0004] According to the existing literature, the sensing technology that provides the resonant frequency signal of the hard tag for the magnetic insertion control device can be divided into single coil, double coil and three coil types according to the number of probe coils. The paper "Research on Quality Parameter Detection Technology of Three-coil Passive Electronic Tags" explains the detection principle of the three-coil hard tag resonant frequency tag, which can effectively solve the problem of indirect acquisition and test frequency offset of single coil and double coil, but its principle ignores the influence of the hard tag on the left receiving coil. The three patents with patent announcement numbers CN107239079A, CN108268929A and CN108549265A disclose magnetic insertion devices and corresponding control methods based on three-coil sensor probe technology, realize semi-automatic magnetic insertion, and the quality and efficiency of magnetic insertion are better than traditional manual magnetic insertion. However, these three patent technologies also have some shortcomings. First, the assembly, debugging and zeroing of the three-coil probe structure are cumbersome. Second, there is a principle error in the detection of resonant frequency by the three-coil sensor technology. Third, the magnetic insertion control method based on the three-coil sensor probe technology is complex and the control accuracy is not high. Summary of the invention:

[0005] In view of the above technical problems, the present invention adopts a single-coil probe and proposes a hard tag magnetic insertion digital quantity control circuit and a control method thereof, which senses the change of the hard tag resonant frequency based on the phase change characteristics and uses a switching signal as the output.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A hard tag magnetic insertion digital quantity control circuit, comprising:

[0008] Control unit, signal source unit, compensation capacitor unit, sensitive probe, precision resistor R1, zero-crossing comparator, edge D trigger;

[0009] The signal source unit is used to generate an excitation signal, the frequency of which is the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process;

[0010] The compensation capacitor unit includes a capacitor C1 and a fine-tuning capacitor C2, the capacitor C1 and the fine-tuning capacitor C2 are connected in parallel, and a first end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel is connected to the output signal end of the signal source unit;

[0011] The first end of the sensitive probe is connected to the second end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel;

[0012] The first end of the precision resistor R1 is connected to the second end of the sensitive probe, and the second end of the precision resistor R1 is connected to the ground end of the signal source unit;

[0013] The total capacitance C of the compensation capacitor unit 总 When the target frequency F0 corresponds to the angular frequency w0, the corresponding capacitive reactance and inductive reactance are equal, that is, w0L1=1 / w0C 总 ;

[0014] The zero-crossing comparator includes a first zero-crossing comparator A and a second zero-crossing comparator B, wherein an input end of the first zero-crossing comparator A is connected to an output signal end of the signal source unit, and an input end of the second zero-crossing comparator B is connected to a first end of the precision resistor R1;

[0015] The clock pulse CP input terminal of the edge-edge D trigger is connected to the output terminal of the first zero-crossing comparator A, the edge D input terminal of the edge-edge D trigger is connected to the output terminal of the second zero-crossing comparator B, and the first signal output terminal Q terminal of the edge-edge D trigger is electrically connected to the I / O port of the control unit.

[0016] As a preferred embodiment of the above technical solution, the signal source unit adopts a programmable waveform generator AD9833, and the signal source unit works in a sine wave output mode.

[0017] As a preferred embodiment of the above technical solution, the sensitive probe is a multi-strand coil formed by winding copper wire.

[0018] As a preferred embodiment of the above technical solution, the first zero-crossing comparator A and the second zero-crossing comparator B are comparators of model TLV3502.

[0019] As a preferred embodiment of the above technical solution, the edge-triggered D trigger adopts an edge-triggered D trigger of model SN74LVC1G79.

[0020] As a preferred embodiment of the above technical solution, the control unit adopts an MSP430 single-chip microcomputer.

[0021] A control method for a hard tag magnetic insertion digital quantity control circuit, characterized in that:

[0022] S1: The control unit controls the signal source unit to generate an excitation signal, the frequency of the excitation signal being the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process;

[0023] S2: Place the hard tag to be FM into the magnetic inserting base, control the stepper motor to drive the pressing block to press the magnetic rod into the frame of the hard tag to be FM, and at the same time, the first zero-crossing comparator A and the second zero-crossing comparator B work. The first zero-crossing comparator A converts the received signal U s The second zero-crossing comparator B shapes the received signal U0 into a second square wave signal P2;

[0024] S3: The first zero-crossing signal comparator sends the first square wave signal P1 to the clock pulse CP input terminal of the edge-edge D flip-flop, the second zero-crossing signal comparator sends the second square wave signal P2 to the edge D input terminal of the edge-edge D flip-flop, and the first signal output terminal Q of the edge-edge D flip-flop sends the output level to the I / O port of the control unit;

[0025] S4: The control unit receives the output level sent by the first signal output terminal Q of the edge-triggered D trigger in real time. When a rising edge of the first signal output terminal Q is detected, the signal U received by the first zero-crossing comparator A is s The phase is consistent with the signal U0 received by the second zero-crossing comparator B, which is the best control point for the insertion depth of the magnetic rod. The control unit controls the stepper motor to stop pressing down and reverse to rise, completing a magnetic pressure frequency modulation.

[0026] The beneficial effects of the present invention are as follows: the single-coil probe has a simple design structure and is easy to install and debug. It uses a phase change characteristic to sense the change in the resonant frequency of the hard tag, which effectively solves the problem that the control accuracy is affected by the change in the mutual inductance coefficient M between the hard tag and the detection probe as the magnetic insertion changes when the amplitude change is used as the control signal. The control signal in this circuit is a switch signal, and the control method program design is simple, which effectively improves the control accuracy of the resonant frequency of the hard tag production of the magnetic insertion device. Description of the drawings:

[0027] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0028] Figure 1This is a connection diagram of a hard tag magnetic insertion digital quantity control circuit module according to an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of a hard tag magnetic insertion digital quantity control circuit according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of signal conversion of a hard tag magnetic insertion digital quantity control circuit according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the mechanical structure of a hard tag magnetic insertion and frequency modulation according to an embodiment of the present invention.

[0032] Explanation of symbols in the figure:

[0033] 1- magnetic base, 2- hard label, 3- magnetic rod, 4- sensitive probe, 5- lead screw, 6- stepping motor, 7- pressing block. Specific implementation method:

[0034] like Figure 1 , Figure 2 As shown, a hard tag magnetic insertion digital quantity control circuit of the present invention includes:

[0035] Control unit, signal source unit, compensation capacitor unit, sensitive probe, precision resistor R1, zero-crossing comparator, edge D trigger;

[0036] The signal source unit is used to generate an excitation signal, the frequency of which is the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process;

[0037] The compensation capacitor unit includes a capacitor C1 and a fine-tuning capacitor C2, the capacitor C1 and the fine-tuning capacitor C2 are connected in parallel, and a first end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel is connected to the output signal end of the signal source unit;

[0038] The first end of the sensitive probe is connected to the second end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel;

[0039] The first end of the precision resistor R1 is connected to the second end of the sensitive probe, and the second end of the precision resistor R1 is connected to the ground end of the signal source unit;

[0040] The total capacitance C of the compensation capacitor unit 总 When the target frequency F0 corresponds to the angular frequency w0, the corresponding capacitive reactance and inductive reactance are equal, that is, w0L1=1 / w0C 总 ;

[0041] The zero-crossing comparator includes a first zero-crossing comparator A and a second zero-crossing comparator B, wherein an input end of the first zero-crossing comparator A is connected to an output signal end of the signal source unit, and an input end of the second zero-crossing comparator B is connected to a first end of the precision resistor R1;

[0042] The clock pulse CP input terminal of the edge-edge D trigger is connected to the output terminal of the first zero-crossing comparator A, the edge D input terminal of the edge-edge D trigger is connected to the output terminal of the second zero-crossing comparator B, and the first signal output terminal Q terminal of the edge-edge D trigger is electrically connected to the I / O port of the control unit (not shown in the figure).

[0043] The signal source unit adopts a programmable waveform generator AD9833, and the signal source unit works in a sine wave output mode.

[0044] The sensitive probe is a multi-strand coil formed by winding copper wire.

[0045] The first zero-crossing comparator A and the second zero-crossing comparator B are TLV3502 comparators.

[0046] The edge-triggered D flip-flop adopts an edge-triggered D flip-flop of model SN74LVC1G79.

[0047] The control unit adopts MSP430 single chip microcomputer.

[0048] like Figure 2 As shown, the circuit structure of the hard tag can be equivalent to Figure 2 In the middle, L3, C3, and R3 are connected in series. When the signal source frequency w is set to control the target hard tag resonant frequency w0, and by adjusting the fine-tuning capacitor C2, w0L1=1 / w0C 总 , referring to patent CN201710202121.8, an EAS electronic tag quality parameter detector and its detection method, it can be known that:

[0049]

[0050] Right now

[0051] During the process of inserting the magnetic hard tag - the magnetic rod is inserted into the frame with the coil, the values ​​of the resistor R3 and the capacitor C3 remain unchanged, the inductor L3 increases, and the mutual inductance coefficient M between the sensitive probe and the hard tag inductor L3 also increases.

[0052] Qualitative analysis of formula (2) shows that when the angular frequency is w0, the total impedance of the equivalent circuit of the hard tag L3, C3, and R3 in series becomes capacitive, and the signal U s Phase advance signal U0; when the total impedance of the equivalent circuit of hard tag L3, C3, and R3 in series becomes inductive, signal U sPhase lag signal U0; when the total impedance of the equivalent circuit of hard tag L3, C3, and R3 in series becomes resistive, signal U s The phase is consistent with signal U0.

[0053] During the magnetic insertion process of hard tag production, signal U s The phase first leads U0, then lags U0, signal U s When the phase is consistent with signal U0, this is the best control point for the insertion depth of the magnetic rod.

[0054] SignalU s , U0 are shaped into square wave signals by zero-crossing comparator A and zero-crossing comparator B respectively, and then processed by edge-triggered D trigger, such as Figure 3 As shown, the signal U s The leading and lagging U0 correspond to the low level and high level of the output terminal Q of the D flip-flop respectively.

[0055] This embodiment also provides a control method for a hard tag magnetic insertion digital quantity control circuit, comprising the following steps:

[0056] S1: The control unit controls the signal source unit to generate an excitation signal, the frequency of the excitation signal being the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process;

[0057] S2: Place the hard tag to be FM into the magnetic inserting base, control the stepper motor to drive the pressing block to press the magnetic rod into the frame of the hard tag to be FM, and at the same time, the first zero-crossing comparator A and the second zero-crossing comparator B work. The first zero-crossing comparator A converts the received signal U s The second zero-crossing comparator B shapes the received signal U0 into a second square wave signal P2;

[0058] S3: The first zero-crossing signal comparator sends the first square wave signal P1 to the clock pulse CP input terminal of the edge-edge D flip-flop, the second zero-crossing signal comparator sends the second square wave signal P2 to the edge D input terminal of the edge-edge D flip-flop, and the first signal output terminal Q of the edge-edge D flip-flop sends the output level to the I / O port of the control unit;

[0059] S4: The control unit receives the output level sent by the first signal output terminal Q of the edge-triggered D trigger in real time. When a rising edge of the first signal output terminal Q is detected, the signal U received by the first zero-crossing comparator A is s The phase is consistent with the signal U0 received by the second zero-crossing comparator B, which is the best control point for the insertion depth of the magnetic rod. The control unit controls the stepper motor to stop pressing down and reverse to rise, completing a magnetic pressure frequency modulation.

[0060] like Figure 4As shown, this embodiment provides a schematic diagram of a mechanical device for realizing hard tag insertion and frequency modulation in cooperation with the present invention. The sensitive probe 4 is fixed on the pressing block 7. The magnetic rod 3 can be manually or automatically placed into the hard tag 2 to be frequency modulated, and then the hard tag 2 to be frequency modulated can be placed into the magnetic insertion base 1; the stepping motor 6 is controlled to work, and the lead screw 5 rotates to drive the pressing block 7 to press down. At the beginning, the circuit of the present invention Figure 2 The middle Q terminal outputs a low level. When the control detects the rising edge of the Q terminal, the stepper motor stops pressing down and reverses to rise, completing a magnetic pressure frequency modulation.

[0061] This embodiment provides a hard tag magnetic insertion digital quantity control circuit and control method, the control circuit includes a control unit, a signal source unit, a compensation capacitor unit, a sensitive probe, a precision resistor R1, a zero-crossing comparator, and an edge D trigger. The present invention adopts a single coil probe design with a simple structure, convenient installation and debugging, and uses a phase change characteristic to sense the change in the resonant frequency of the hard tag, which effectively solves the problem that the control accuracy is affected by the change in amplitude as the control signal and the mutual inductance coefficient M between the hard tag and the detection probe changes with the magnetic insertion; the control signal in this circuit is a switch signal, and the control method program design is simple, which effectively improves the control accuracy of the resonant frequency of the hard tag production of the magnetic insertion device.

[0062] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A hard tag magnetic insertion digital quantity control circuit, characterized in that: include: Control unit, signal source unit, compensation capacitor unit, sensitive probe, precision resistor R1, zero-crossing comparator, edge D trigger; The signal source unit is used to generate an excitation signal, the frequency of which is the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process; The compensation capacitor unit includes a capacitor C1 and a fine-tuning capacitor C2, the capacitor C1 and the fine-tuning capacitor C2 are connected in parallel, and a first end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel is connected to the output signal end of the signal source unit; The first end of the sensitive probe is connected to the second end of the capacitor C1 and the fine-tuning capacitor C2 connected in parallel; The first end of the precision resistor R1 is connected to the second end of the sensitive probe, and the second end of the precision resistor R1 is connected to the ground end of the signal source unit; The total capacitance C of the compensation capacitor unit 总 When the target frequency F0 corresponds to the angular frequency w0, the corresponding capacitive reactance and inductive reactance are equal, that is, w0L1=1 / w0C 总 ; The zero-crossing comparator includes a first zero-crossing comparator A and a second zero-crossing comparator B, wherein an input end of the first zero-crossing comparator A is connected to an output signal end of the signal source unit, and an input end of the second zero-crossing comparator B is connected to a first end of the precision resistor R1; The clock pulse CP input terminal of the edge-triggered D flip-flop is connected to the output terminal of the first zero-crossing comparator A, the edge D input terminal of the edge-triggered D flip-flop is connected to the output terminal of the second zero-crossing comparator B, and the first signal output terminal Q terminal of the edge-triggered D flip-flop is electrically connected to the I / O port of the control unit; The signal source unit adopts a programmable waveform generator AD9833, and the signal source unit works in a sine wave output mode; The sensitive probe is a multi-strand coil formed by winding copper wire.

2. A hard tag magnetic insertion digital quantity control circuit according to claim 1, characterized in that: The first zero-crossing comparator A and the second zero-crossing comparator B are TLV3502 comparators.

3. A hard tag magnetic insertion digital quantity control circuit according to claim 1, characterized in that: The edge-triggered D flip-flop adopts an edge-triggered D flip-flop of model SN74LVC1G79.

4. A hard tag magnetic insertion digital quantity control circuit according to claim 1, characterized in that: The control unit adopts MSP430 single chip microcomputer.

5. A control method for a hard tag magnetic insertion digital quantity control circuit according to any one of claims 1 to 4, characterized in that: The steps include: S1: The control unit controls the signal source unit to generate an excitation signal, the frequency of the excitation signal being the target frequency F0 of the hard tag resonant frequency controlled during the magnetic insertion process; S2: Place the hard tag to be FM into the magnetic inserting base, control the stepper motor to drive the pressing block to press the magnetic rod into the frame of the hard tag to be FM, and at the same time, the first zero-crossing comparator A and the second zero-crossing comparator B work. The first zero-crossing comparator A converts the received signal U s The second zero-crossing comparator B shapes the received signal U0 into a second square wave signal P2; S3: The first zero-crossing signal comparator sends the first square wave signal P1 to the clock pulse CP input terminal of the edge-edge D flip-flop, the second zero-crossing signal comparator sends the second square wave signal P2 to the edge D input terminal of the edge-edge D flip-flop, and the first signal output terminal Q of the edge-edge D flip-flop sends the output level to the I / O port of the control unit; S4: The control unit receives the output level sent by the first signal output terminal Q of the edge-triggered D trigger in real time. When a rising edge of the first signal output terminal Q is detected, the signal U received by the first zero-crossing comparator A is s The phase is consistent with the signal U0 received by the second zero-crossing comparator B, which is the best control point for the insertion depth of the magnetic rod. The control unit controls the stepper motor to stop pressing down and reverse to rise, completing a magnetic pressure frequency modulation.

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