JP3581264B2 - Resonance frequency adjustment method for non-contact mobile object identification device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact mobile object identification device, and more particularly, to an improvement in a method of adjusting a resonance frequency of a reception resonance circuit forming a transponder.
[0002]
[Prior art]
A conventional non-contact moving object identification device will be described with reference to FIG. In FIG. 4, the non-contact mobile unit identification device includes an interrogator 2 and a transponder 3 fixed to the identification target mobile unit. The interrogator 2 is a command (a command (transmission signal) transmitted from the higher-level control device 1). A command signal serving as rewriting information in the memory of the transponder is modulated by a modulation circuit 11 via an interface circuit 10, amplified by an amplification circuit 12, and amplified by a series resonance circuit of a transmission capacitor 13 and a transmission coil 15. The signal is transmitted to the transponder 3 at the frequency of 1.
[0003]
The transponder 3 receives a command from the interrogator 2 by a receiving resonance circuit in which the receiving coil 30 and the receiving capacitor 31 are connected in parallel, demodulates the received signal by the modulation / demodulation circuit 33, and controls the inside of the control circuit (control unit) 37. Write or read data to or from the built-in memory (rewriting the stored contents of the memory), modulate a response (a response signal transmitted to the interrogator 2), and transmit the modulated signal to the interrogator 2 at a third frequency. On the other hand, power is taken from the rectifier circuit 35 from the reception resonance circuit.
[0004]
Interrogator 2 receives a response transmitted from the responder 3 at a third frequency in the receiving coil 20 and the receiving capacitor 21, the demodulation circuit 28 to record scan Pons this output via the filter circuit 26 After demodulation, the signal is transmitted to the host control device 1 via the interface circuit 10.
[0005]
The second resonance frequency of the reception resonance circuit of the transponder 3 changes due to errors in the self-inductance of the reception coil 30, the variation in the capacitance of the reception capacitor 31, the mounting of the reception coil 30, and the like. Due to the change in the resonance frequency, the received power decreases or the signal from the interrogator 2 cannot be received with high accuracy.
[0006]
Therefore, the resonance frequency of the reception resonance circuit is adjusted by the following method. First, the voltage measuring device 50 is connected to the terminals T1 and T2 at both ends of the receiving resonance circuit via the lead wires 50a and 50b, and the interrogator 2 and the transponder 3 are connected at a predetermined distance value. The capacitance value of the receiving capacitor 31 is adjusted so that the measured voltage of 50 becomes a predetermined value.
[0007]
Second, using only the transponder 3, an impedance measuring device (not shown) is connected to the terminals T1 and T2 at both ends of the receiving resonance circuit via the lead wires 50a and 50b, and the impedance for each frequency is measured. Then, the resonance frequency is estimated from the frequency characteristics of the impedance, and the capacitance value of the receiving capacitor 31 is adjusted so as to be within a range of a predetermined allowable resonance frequency.
[0008]
[Problems to be solved by the invention]
However, in the above-described method of adjusting the resonance circuit for reception, the voltage measuring device 50 and the like are connected to both ends of the resonance circuit for reception via the leads 50a and 50b, and the leads 50a and 50b are detached for each transponder 3. I had to do it and it was troublesome. In addition, the impedance value or voltage value of the reception resonance circuit cannot be accurately measured due to the floating impedance of the lead wires 50a and 50b, and the measured value of the resonance frequency of the reception resonance circuit differs from the actual value. There was a problem that the accuracy was not sufficient.
[0009]
When measuring the impedance or voltage characteristic of the receiving resonance circuit only with the transponder 3, the measured value is not affected by the mutual inductance due to the transmission coil 15 of the interrogator 2 in the actual use state. Measures different things. Therefore, there is a problem that the measured value of the resonance frequency of the reception resonance circuit differs from the actual value and the accuracy is not sufficient.
[0010]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a resonance frequency adjustment method for a non-contact mobile object identification device that can easily adjust a resonance frequency by non-contact.
[0011]
[Means to solve the problem]
According to a first aspect of the present invention, there is provided a non-contact moving object identification device adjusting method, comprising: a transmitting coil; A first receiving capacitor for receiving a signal and a first receiving coil are connected in parallel, a first receiving resonant circuit resonating at a second frequency, and a signal from the first receiving resonant circuit. A response unit that demodulates an output signal to write or read data to / from a built-in memory, modulates the generated response signal, and transmits the response signal via the first reception resonance circuit. In the resonance frequency adjusting method of the non-contact moving object identification device, a measuring coil having a self-inductance sufficiently smaller than a self-inductance of the first receiving coil is connected to the first receiving resonant circuit. A first step of arranging the transmission voltage close to the surface, and sweeping a constant transmission voltage from the signal generating means via the transmission coil at a frequency including the predetermined second resonance frequency; A second step of sending to the first receiving coil by electromagnetic induction, and measuring the characteristics of the induced voltage and the frequency of the measuring coil by the measuring means, and the measured value is within a predetermined range, The capacitance value of the first receiving capacitor or the self-inductance value of the first receiving coil is changed so that the first receiving resonance circuit resonates at the second frequency. It is assumed that.
[0012]
According to a second aspect of the present invention, the interrogator includes a transmission resonance circuit for resonating a transmission signal at a first resonance frequency including a transmission capacitor and a transmission coil; and a response signal. And a second reception resonance circuit that connects a second reception capacitor and a second reception coil in parallel and resonates at a third frequency. A predetermined transmission voltage is swept at a frequency including a predetermined second resonance frequency from the signal generation means via the signal generating means, and the transmission voltage is sent to the first receiving coil by electromagnetic induction. is there.
[0013]
According to a third aspect of the invention, there is provided a method for adjusting a non-contact moving object identification device, comprising: a step of transmitting a signal generation means by a measuring means instead of measuring characteristics of an induced voltage and a frequency of a measuring coil by a measuring means according to claim 1 or 2; The characteristic of gain and frequency based on the voltage value and the induced voltage value of the measuring coil is measured.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a non-contact moving object identification device showing an embodiment of the present invention. 1, the same reference numerals as those in the related art denote the same or corresponding parts, and a description thereof will be omitted. In FIG. 1, the interrogator 2 is provided with terminals a and b from the output side of the modulation circuit 11 and the terminals c and d also on the input side of the amplifier circuit 12. A signal generator 150 capable of generating a constant signal voltage including the resonance frequency and sweeping the frequency is connected to terminals c and d. The front of the receiver coil 30 is arranged a measuring coil 201, the terminal of the measuring coil 2 01 voltmeter 203 measuring the voltage versus frequency characteristic are connected.
[0015]
Here, the self-inductance L1 of the measuring coil 201 and the self-inductance of the receiving coil 30 have a relationship of L2 >> L1. This is because the mutual induction inductance M is formed between the measurement coil 201 and the reception coil 30 because the measurement coil 201 is inserted in front of the reception coil 30, and the self-inductance of the reception coil 30 is reduced. This is to suppress as much as possible that L2 changes and the resonance frequency changes as compared to before the measurement coil 201 is inserted.
[0016]
The relationship of L2 >> L1 will be clarified by the impedance Zi viewed from the receiving coil 30.
Zi = jωL2 + jωM (I1 / I2) (1)
Here, I1 = current flowing in the measuring coil I2 = current flowing in the first receiving coil In the above equation (1), the receiving coil 30 forming the parallel resonance circuit is hardly affected by the mutual inductance M. L2 >> M. The mutual inductance M is affected by the arrangement of the receiving coil 30 and the measuring coil 201, but if the relationship L2 >> L1, the relationship L2 >> M is satisfied. In order to satisfy such a relationship, if the number of turns N2 of the receiving coil 30 and the resistance R2, and the number of turns N1 and the resistance R1 of the measuring coil 201, it is configured to have a relationship of N2 >> N1, R2 >> R1. I have.
[0017]
The operation of the mobile object identification device configured as described above will be described with reference to FIGS. First, remove the jumper lines 101 and 103 of the interrogator 2 from the terminal to d, an output and a terminal c of the signal generator 150, a d connect the measuring coil on the front of the receiver coil 30 (reception resonant circuit) 201 is arranged. A voltage measuring device 203 is connected to both ends of the measuring coil 201.
[0018]
In this state, the transmission frequency from the signal generator 150, a start frequency fs around the second resonance frequency fr of the parallel resonance circuit, when the end frequency f _f, fs <fr <constant value signal voltage at f _f To sweep. The signal voltage is applied to the transmission resonance circuit including the transmission capacitor 13 and the transmission coil 15 via the amplification circuit 12, and the signal voltage between the reception capacitor 31 and the reception coil 30 of the transponder 3 is induced by electromagnetic induction. A voltage is generated in the parallel resonance circuit for reception. At the same time, since the magnetic flux in the measuring coil 201 changes with time, an induced voltage is generated, and the output voltage curve of the voltage versus frequency characteristic shown in FIG. 2 is obtained.
[0019]
At the same time, the transponder 3 receives the data by the reception resonance circuit, demodulates the data by the modulation / demodulation circuit 33, and writes or reads the data to / from the internal memory in the control circuit (control unit) 37 (rewrites the stored contents of the memory) (The response signal transmitted to the interrogator 2) is modulated and transmitted to the interrogator 2 at the third frequency. On the other hand, power is extracted from the rectifier circuit 35 from the reception resonance circuit. The interrogator 2 receives the response transmitted from the transponder 3 at the third frequency by the receiving coil 20 and the receiving capacitor 21.
[0020]
While the signal generator 150 sweeps the frequency of the signal generator 150 within a range of a predetermined frequency Δf centered on the second resonance frequency fr from the signal generator 150, a signal is received from the measuring coil 201 so that a voltage equal to or higher than a predetermined voltage is obtained. adjusting the self-inductance of the capacitive or receiving coil 3 0 of the capacitor 3 1. By this adjustment, the output curve of the voltage vs. frequency characteristic shown in FIG. The frequency Δf is determined in consideration of the communication distance between the interrogator 2 and the transponder 3 and the communication reliability.
[0021]
In the above embodiment, the signal voltage of the signal generator 150 by electromagnetic induction via the transmission resonant circuit, but was induced in the receiving coil 3 0, simply transmitting coil 15 to the signal voltage (other in coils, the receiving coils 3 0 may be any electromagnetic coupling.) only may be induced in the receiving coil 3 0.
[0022]
Here, without measuring the output voltage versus frequency characteristics of the measuring coil 201, the frequency of the signal voltage generated from the signal generator 150 is fixed at the second resonance frequency, and the output voltage of the measuring coil 201 is fixed. the but it showed that the maximum value, adjusting the capacitance of the receiving capacitor 3 1, because it does not measure the output voltage versus frequency characteristic, it takes time not fixed increase or decrease the adjustment value of the electrostatic capacitance value .
[0023]
Embodiment 2 FIG.
Another embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the non-contact moving object identification device. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. In FIG. 3, the difference from the first embodiment is that the measurement coil 201 is arranged on the front surface of the reception coil 30, and the output voltage Vi of the signal generator 150 and the voltage V0 across the measurement coil 201 are different from each other. gain V0 / Vi, i.e., gain versus frequency characteristic and gain measurement 300 is connected to measure the gain vs. capacitance or receiving coil 3 0 of the self-inductance of the receiving capacitor 3 1 based on the frequency characteristic It is the point that is adjusted.
[0024]
【The invention's effect】
According to the first invention, a first step of arranging a measuring coil having a self-inductance sufficiently smaller than a self-inductance of a first receiving coil close to a front surface of the first receiving resonance circuit; A predetermined transmission voltage is swept by the signal generation means via the transmission coil at a frequency including the predetermined second resonance frequency, and the transmission voltage is transmitted to the first reception coil by electromagnetic induction. Measuring the characteristics of the induced voltage and the frequency of the measuring coil by the measuring means, and measuring the first reception signal at the second frequency within a predetermined range. The capacitance value of the first receiving capacitor or the self-inductance value of the first receiving coil is changed so that the resonance circuit resonates. There is an effect that can adjust the resonance frequency.
[0025]
According to the second aspect, in addition to the effects of the first aspect, the interrogator includes a transmission resonance circuit for resonating a transmission signal at a first resonance frequency including a transmission capacitor and a transmission coil, A second receiving resonance circuit for connecting a signal in parallel with a second receiving capacitor and a second receiving coil and resonating at a third frequency; A constant transmission voltage is swept from the signal generation means via a predetermined frequency including the second resonance frequency, and the transmission voltage is transmitted to the first receiving coil by electromagnetic induction. It is possible to adjust the resonance frequency of the reception resonance circuit after operating the transponder and the transponder in an actual use state, so that the reception resonance circuit can be adjusted with high accuracy.
[0026]
According to the third aspect, in addition to the effects of the first or second aspect, the characteristic of the gain and the frequency based on the transmission voltage value of the signal generating means and the induced voltage value of the measuring coil is measured by the measuring means. Therefore, there is an effect that the resonance frequency of the reception resonance circuit can be adjusted while checking the frequency characteristics of the gain.
[Brief description of the drawings]
FIG. 1 is a block diagram of a non-contact moving object identification device showing an embodiment of the present invention.
FIG. 2 is a curve showing frequency versus voltage characteristics of the measurement coil shown in FIG.
FIG. 3 is a block diagram of a non-contact moving object identification device showing another embodiment of the present invention.
FIG. 4 is a block diagram of a conventional non-contact moving object identification device.
[Explanation of symbols]
2 interrogator, 3 responder, 13 transmitting capacitor, 15 transmitting coil, 30 receiving coil , 31 receiving capacitor , 150 signal generator, 201 measuring coil, 203 voltage measuring instrument, 300 gain measuring instrument.

Claims (3)

A transmission coil, an interrogator for transmitting a transmission signal at a first frequency via the transmission coil, and receiving a response signal; a first reception capacitor for receiving the transmission signal; and a first reception capacitor. A first receiving resonance circuit that resonates at a second frequency while connecting a coil in parallel, and demodulates an output signal from the first reception resonance circuit to write or read data to or from a built-in memory to generate data A transponder having a control unit for modulating the response signal and transmitting the response signal via the first receiving resonance circuit. A first step of disposing a measuring coil having a self-inductance sufficiently smaller than the self-inductance of the receiving coil in close proximity to the front surface of the first receiving resonance circuit; A second transmission frequency is sent from the signal generating means to the first receiving coil by electromagnetic induction while a constant transmission voltage is swept at a frequency including the predetermined second resonance frequency from the signal generation means via the signal generating means. Measuring the characteristics of the induced voltage and the frequency of the measuring coil by measuring means, and measuring the first reception resonance circuit at the second frequency within a predetermined range. Changing the capacitance value of the first receiving capacitor or the self-inductance value of the first receiving coil so that the resonance of the first receiving capacitor occurs. The interrogator includes a transmission resonance circuit that resonates the transmission signal at a first resonance frequency, the transmission resonance circuit including a transmission capacitor and the transmission coil, a second reception capacitor, a second reception capacitor, and a second reception capacitor. And a second reception resonance circuit resonating at a third frequency, wherein the second step includes a step of transmitting a constant transmission voltage from the signal generation means via the transmission resonance circuit. 2. The non-contact moving body according to claim 1, wherein the frequency is swept at a frequency including the predetermined second resonance frequency, and the transmission voltage is sent to the first receiving coil by electromagnetic induction. A method for adjusting the resonance frequency of the identification device. Instead of measuring the characteristics of the induced voltage and the frequency of the measuring coil by the measuring means according to claim 1 or 2, the measuring means calculates the transmission voltage value of the signal generating means and the induced voltage value of the measuring coil. A resonance frequency adjustment method for a non-contact mobile object identification device, comprising measuring characteristics of a base gain and a frequency.

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