JPH09284171A - Non-contact data transmission / reception method and device - Google Patents

Abstract

(57) [Abstract] [Problem] When a plurality of transponders exist in a communication area, a problem occurs in which communication occurs between the interrogator and the transponder depending on a distance between the transponders. there were. SOLUTION: The frequency of a carrier wave of a signal transmitted from an interrogator to a responder is changed, and a received output obtained by the responder receiving the carrier wave having the frequency at this time is also obtained by a predetermined resonance characteristic. And when notifying the interrogator by determining that the transponder is ready for communication, the interrogator recognizes the frequency of the carrier wave that is being transmitted to the transponder at that time. Then, the carrier wave having the recognized frequency is used to communicate with the responder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a tool, luggage, or person with an answering device such as a contactless card in a production line or a distribution line of a factory, entrance / exit management of an office, and the like. The present invention relates to a non-contact data transmission / reception method and device for registering a unique ID code, a product number, data at the time of manufacturing, etc., and communicating and managing the data in a non-contact manner.

[0002]

2. Description of the Related Art FIG. 15 is a block diagram showing a configuration of a conventional non-contact data transmitting / receiving apparatus, FIG. 16 is a characteristic diagram showing a general relationship between a distance between two transponders and a receiving level, and FIG.
FIG. 4 is a characteristic diagram showing a general relationship between the frequency and the impedance of the resonance circuit depending on the distance between the transponders. In FIG. 15, 1 is an interrogator, and 2 is a responder that communicates with the interrogator 1 in the communication area 3. The interrogator 1 has an oscillator (O
SC) 21, modulator 22, transmitter 23, receiver 24, demodulator 25, and controller 26. The output end of the oscillator 21 is connected to the input end of the modulator 22, and the output end of the modulator 22 is connected to the transmitter 23. The control unit 26 is composed of a CPU and the like. The controller 26 is connected to the modulator 22 and the demodulator 25.

The transponder 2 includes a receiver 27, a power supply circuit 28, a demodulator 29, a power supply voltage detector 30, a controller 31, and a memory 3.
2, a modulator 33, a transmitter 34, and a capacitor C2. The receiver 27 is connected to the power supply circuit 28 and the demodulator 29. The power supply circuit 28 is connected to the power supply voltage detection unit 30, and the power supply voltage detection unit 30 is connected to the charging capacitor C2. The power supply circuit 28
Is to rectify the high-frequency signal received from the interrogator 1 by the receiver 27 into a direct current, store it in the capacitor C2, and use it as the entire power source of the responder 2. The power supply voltage detector 30 detects the voltage of the power supply circuit 28. Transmitter 3
4 is connected to the modulator 33, and the controller 31 is connected to the demodulator 2
9, modulator 33, memory 32, and power supply voltage detector 3
0.

In the conventional non-contact card device, a command signal is sent from the interrogator 1 to the responder 2 in a non-contact manner, and the responder 2 returns a unique ID code or data from the signal. . In this case, the arrival area of the command signal from the interrogator 1 is the communication area 3, and only the responder 2 in the area is allowed to communicate.

First, the interrogator 1 sends a read command signal to the responder 2 in the communication area 3. As for the command signal, the command for the responder 2 is ASK (Am
It is a signal modulated by the Plotide Shift Keying) or the like. The responder 2 demodulates the command signal from the interrogator 1 received by the receiver, rectifies the signal, and charges the charging capacitor C2 as an internal power supply. The command signal is also used as the internal clock of the responder 2. The receiving unit 27 is configured by a parallel resonant circuit (not shown) having a high Q value in order to improve receiving efficiency. Then, the ID code and data are read from the memory 32 in the responder 2 according to the content of the command, and the high frequency signal is modulated and returned. In the transponder 2 shown in FIG. 15, it is conceivable that the parallel resonant circuit forming the receiving unit 27, the charging capacitor C2, and the transmitting unit are incorporated into a single-chip IC to reduce the cost.

When the responder 2 receives the command signal from the interrogator 1, it performs half-wave or full-wave rectification to convert it into direct current,
The external charging capacitor C2 is charged. Then, the charging voltage is detected by the power supply voltage detection unit 30, and when the IC in the transponder 2 reaches a voltage at which the IC can operate, the IC is reset once and the command from the interrogator 1 can be demodulated. Since normal operation of the internal IC is not guaranteed until the output of the power supply voltage detection unit 30 is turned on, memory access,
Operations such as modulation / demodulation are not performed. These are premised on that the interrogator 1 and the responder 2 perform one-to-one communication within the communication area 3.

However, when the transponders 2 are close to each other, the signal from the interrogator 1 in the resonance circuit of each transponder 2 becomes smaller as the distance 1 between the transponders 2 becomes smaller as shown in FIG. The received waveform amplitude of becomes smaller. This is because the resonance frequencies of the resonance circuits of the two transponders 2, which resonate at different distances, are different as shown in FIG. Note that the horizontal axis of FIG. 17 shows the frequency, and the vertical axis shows the impedance of the resonance circuit. The high-impedance frequency is the resonance frequency of the resonance circuit. The sharper the slope, the higher the Q value of the resonance circuit. ing. This phenomenon is 2
When the two responders 2 are close to each other, the resonance circuits are coupled to each other. The capacitance of the capacitors forming the resonance circuits of the respective responders 2 is C, the inductance of the coil is L, and the two resonance circuits When the coupling coefficient is k, the resonance frequencies fc, fp1 and fp2 can be approximated by the following equations.

[0008]

[Equation 1]

[0009]

[Equation 2]

[0010]

(Equation 3)

Here, the coupling coefficient k takes a value of 0 to 1,
By approaching, k approaches 1, and fp1 and fp2 move away from fc. In this way, when the transponders 2 are close to each other, the resonance frequency of the resonance circuit of each of the transponders 2 departs from the frequency fc set at the time of manufacture, so that the interrogator 1 transmits on the carrier wave of the original resonance frequency fc of the transponders 2. However, since the resonance is off on the transponder 2 side, the received waveform amplitude decreases,
Insufficient power supply voltage can be charged to the charging capacitor. Therefore, since it is impossible to obtain sufficient operating power for the IC in the transponder 2, power is not supplied to each internal block, and the command transmitted by the interrogator 1 is demodulated and the memory 32 is used. Access was impossible.

Further, since the above-mentioned deviation of the resonance frequency is much larger than the variation at the time of manufacturing and the variation due to the ambient temperature, it is possible to obtain the power supply for operating the internal IC due to the variation at the time of manufacturing. However, it is impossible to operate the internal IC in the above-mentioned state,
There is a problem that the resonance circuit of the transponder 2 cannot be corrected using the internal circuit. Note that the above equation (2),
(3) is an equation when two transponders 2 are overlapped. When the transponders 2 are tripled, the above equations (2) and (3) do not apply, but for the same reason, resonance of the resonance circuit is caused. The frequency will change.

[0013]

As described above, the problem to be solved by the present invention is that the resonance frequency of the resonance circuit of each responder greatly deviates from the frequency fc set at the time of manufacture when the responders are close to each other. Even if the interrogator transmits on the carrier wave of the original resonance frequency fc of the transponder, the resonance of the transponder side is deviated, so that the amplitude of the received waveform decreases and the charging capacitor can be charged with a sufficient power supply voltage. Can not.
Therefore, since it is impossible to obtain sufficient operating power for the IC in the transponder, power is not supplied to each internal block, and it is not possible to demodulate the command transmitted by the interrogator or access the memory. It will be possible.

The present invention has been made in order to solve the above-mentioned problems, and a plurality of transponders approach each other in a communication area, so that the resonant frequency of the resonant circuit of each transponder is set at the time of manufacture. Even when the transponders are separated from the frequency fc, it is an object to avoid a decrease in the received waveform amplitude on the transponder side as much as possible and each transponder obtains a sufficient power supply voltage.

[0015]

According to a first aspect of the present invention, an interrogator scans a resonance frequency of a resonance circuit of each responder and transmits command data by using a carrier wave of the recognized resonance frequency of each responder. It has a function.

According to the second aspect of the present invention, the frequency of the carrier wave transmitted by the interrogator is transmitted to the communication area in which the transponders may exist close to each other, and the transponder transmits the frequency, while the transponder operates stably. When it becomes possible to send it to the interrogator, the interrogator receiving this will store the frequency of the carrier wave at that time, and then transmit the communication with the responder at the stored frequency. It has a function.

According to a third aspect of the present invention, in the non-contact data transmission / reception apparatus according to the second aspect, the interrogator has a function of making a transition at a constant frequency interval at a constant time interval.

According to a fourth aspect of the present invention, in the non-contact data transmission / reception apparatus according to the second aspect, the interrogator has a function of selecting a random frequency and making a transition at a constant time interval.

According to a fifth aspect of the present invention, in the non-contact data transmission / reception apparatus according to the second aspect, the interrogator has a function of selecting a preset frequency and making a transition at a constant time interval.

According to a sixth aspect of the present invention, in the non-contact data transmitting / receiving apparatus according to the fifth aspect, a function of setting a plurality of transponders in a fixed state with a holder is provided.

According to a seventh aspect of the present invention, in the non-contact data transmitting / receiving apparatus according to the second aspect, the interrogator has a function of shifting the frequency at a certain fixed rate.

According to an eighth aspect of the present invention, in the contactless data transmitter / receiver according to the first or second aspect, among the responders,
The transponder that has completed transmission has a function of changing the resonance frequency of the resonance circuit.

According to a ninth aspect of the present invention, in the contactless data transmitter / receiver according to the first or second aspect, among the responders,
The transponder that has completed transmission has a function of lowering the Q value of the resonance circuit.

According to a tenth aspect of the present invention, an interrogator and a modulator are provided.
A signal control means, a transmission means composed of a series resonance circuit of a resistor, a variable capacitor and a coil, a reception means for receiving response data from a responder, a demodulator, and a modulator in the responder and a coil. Transmitting / receiving means composed of a parallel resonance circuit of capacitors, demodulating means for demodulating signals from the transmitting / receiving means, internal power supply means for converting a carrier wave from the interrogator into internal power supply of the responder, and transmitting / receiving means of the responder Control means for controlling the signal from the memory, a memory for storing data, an internal power supply detection means for detecting the internal supply voltage of the responder, and a power supply voltage detection means for detecting a voltage higher than the voltage detected by the internal power supply detection means. Is provided.

In the eleventh aspect of the present invention, the frequency of the carrier wave transmitted by the interrogator is transmitted to the communication area where the transponders may be close to each other, and the transponders reach the operable state. After that, the resonant frequency of the resonant circuit is corrected by the carrier of the fixed frequency sent by the interrogator, the interrogator sends the command data by the carrier of the fixed frequency, and the responder is the interrogator by the corrected resonant circuit. It has a function of performing subsequent communication with.

According to a twelfth aspect of the present invention, the interrogator includes a modulator,
A signal control means, a resistor, a transmission means, a reception means for receiving response data from the responder, a demodulation section, and a control section for controlling the transmission frequency of the carrier wave from the transmission means are provided. The transponder is composed of a modulator, a parallel resonance circuit of a coil and a capacitor, and transmitting / receiving means for transmitting and receiving signals to and from the interrogator, demodulation means,
The carrier frequency from the interrogator is converted to direct current, and the resonance frequency of the parallel resonant circuit is changed in response to the signals from the internal power supply means that uses the direct current power as the internal power supply of the responder and the transmitter / receiver means of the responder. And a memory for storing data. Further, the parallel resonance circuit is provided with a plurality of capacitors selectively connected in parallel to the parallel resonance circuit by the control means.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. Embodiment 1. FIG. 1 is a block diagram showing an embodiment of the non-contact data transmitting / receiving apparatus according to the present invention, FIG. 2 is a flow chart showing a temporal signal flow when an interrogator and a responder perform one-to-one communication. Is a characteristic diagram showing a change in the power supply voltage of the transponder due to a change in carrier frequency, FIG. 4 is a flow chart showing a communication flow between the interrogator and a plurality of transponders, and FIGS. 5, 6 and 7 are transitions showing a frequency transition method. FIG. 8 is a circuit diagram showing an example of the transmission circuit of the interrogator.

In FIG. 1, reference numeral 1 is an interrogator, and 2 is a transponder that communicates with the interrogator 1 in the communication area 3.
In the transponder 2, reference numeral 4 denotes a transmission / reception unit, which includes a parallel resonance circuit 5 having a coil L1 and a capacitor C1 and resonating at a frequency fc. A demodulation unit 6 is connected to the output terminal of the transmission / reception unit 4. A control unit 7 is connected to the output terminal of the demodulation unit 6. A power supply unit 8 is connected to the output terminal of the transmission / reception unit 4, and the power supply unit 8 is further connected to a charging capacitor C2. Reference numeral 9 is a first power supply voltage detection unit connected between the power supply unit 8 and the control unit 7, 10 is a second power supply voltage detection unit connected between the power supply unit 8 and the control unit 7, 11
Is a memory and is connected to the control unit 7. Reference numeral 12 denotes a modulator connected to the output end of the controller 7 via a switch 13,
Is a timer provided between the control unit 7 and the switch 13. In addition, the portion surrounded by the dotted line in FIG.
Although it is considered to be made into chips and cost reduction,
It is not limited to this. Further, the transmission / reception unit 4 may be configured with a transmission unit and a reception unit separately.

Next, the flow of signals to each block will be described with reference to FIG. That is, the transponder 2 converts the carrier wave from the interrogator 1 into a direct current by the power supply unit 8 and charges the externally connected charging capacitor C2 to be used as the power source of the internal IC. Therefore, the Q value of the parallel resonant circuit 5 is set high. The carrier wave from the interrogator 1 received by the transmitter / receiver 4 is rectified into a direct current by half-wave or full-wave rectification by the power supply 8.

Further, the rectified current is charged in the capacitor C2. First power supply voltage detector 9 and second
The power supply voltage detector 10 detects the charging voltage of the capacitor C2, and its output is transmitted to the controller 7. Here, the power supply voltage charged in the charging capacitor C2 is monitored by the first power supply voltage detection unit 9 and the second power supply voltage detection unit 10. The first power supply voltage detection unit 9 is a block that detects a state in which a sufficient power supply voltage is maintained to enable normal communication, while the second power supply voltage detection unit 10 is different from the conventional one. Similarly, this block is used during communication such as writing to the memory 11 or for resetting the communication for the first time (power-on reset) and the like, and is a block for monitoring the power supply voltage at which the IC can operate. The control unit 7 also accesses the memory 11 and encodes data to be transmitted to the interrogator 1. The signal modulated by the modulator 12 is transmitted to the transmitter / receiver 4, and the transmitter / receiver 4 generates a reply signal to the interrogator 1.

Here, the first power supply voltage detector 9 and the second power supply voltage detector 9
Assuming that the voltage thresholds detected by the power supply voltage detection unit 10 are V1 and V2, respectively, as shown in FIG. 3, V1> V
Set to a relationship of 2. This is to enable the transponder 2 to perform communication while obtaining a sufficient power supply voltage from the carrier wave of the interrogator 1, but V1 = V2 may be set. Here, when the charging voltage of the charging capacitor C2 exceeds V1, the responder 2 is in a stopped state, so-called sleep mode (SL
From EEP MODE), a receivable state, so-called wakeup mode (WAKEUP MODE) is entered.

Therefore, the interrogator 1 and the responder 2 will be described with reference to FIG.
The communication procedure of the signal will be described. First, the interrogator 1 transmits an unmodulated wave of the frequency fc or a command for returning a receivable signal to the responder 2 for a certain period of time. When the transponders 2 are not in the overlapping state but only one is present in the communication area 3, the parallel resonant circuit 5 of the transponder 2 is resonated at fc, and therefore the frequency transmitted by the interrogator 1 is set. It is possible to obtain a power supply voltage equal to or higher than the threshold value V1 of the first power supply voltage detection unit 9 from the carrier wave fc. Therefore, the transponder 2 returns a receivable signal notifying that the receivable state has been reached to the interrogator 1. As a receivable signal, it is conceivable to use a dedicated specific code or a unique ID code of each responder.

When the interrogator 1 receives the receivable signal, the interrogator 1 determines that the responder 2 can demodulate the command and holds a sufficient power supply voltage, and transmits the carrier wave modulated by the command. . The responder 2 generates a power supply voltage from a carrier wave, demodulates a command, and makes the control unit 7 access the memory 11. Access to the memory 11 is reading of data from the memory 11 or writing of data to the memory 11.

The memory 11 mounted on the transponder 2 may be a non-volatile memory such as an EEPROM so that data is not lost even outside the communication area 3. The control unit 7, which has read the data in the memory 11, adds CRC (Cyclic Redundancy Ch) to the data.
processing, etc., and transmits it to the modulator 12 together with the data to generate a reply signal. The signal from the modulator 12 is transmitted to the transmitter / receiver 4 and returned to the interrogator 1. As a method of replying, a method of changing the impedance of the transmitting / receiving unit 4 according to the data, a method of modulating a high frequency signal from a built-in oscillator, and transmitting the signal can be considered.
The switch 13 is ON during transmission, and the control unit 7 and the modulation unit 12 are in a connected state.

On the other hand, as shown in FIG. 4, when there are a plurality of transponders 2a and 2b overlapping in the communication area 3, the resonance frequency of the resonance circuit of each of the transponders 2a and 2b is shown in FIG. (2) and equation (3). In FIG. 17, the resonance frequencies of the resonance circuits differ depending on the distances between the two responders 2a and 2b, but the resonance frequencies of the responders are almost the same. Therefore, the interrogator 1 transmits the frequency fc at the beginning of communication, and thereafter releases the carrier wave having the changed frequency to the communication area 3.

Examples of frequency transition of the carrier wave transmitted by the interrogator 1 are shown in FIGS. 5, 6 and 7. In FIG. 5, the interrogator 1 raises the frequency of the carrier wave to be transmitted at fixed time intervals T1. This constant time T1 has a certain period after the charging voltage of the charging capacitor of the transponder 2 reaches V1 which is the threshold value of the first power supply voltage detection unit 9, and the power for returning the receivable signal is set. This is to keep it, and to prevent the frequency of the carrier wave from changing when the interrogator 1 is receiving the receivable signal from the responder 2.
Note that Tr is the time when the receivable signal from the transponder 2 is returned.

On the other hand, in FIG. 6, the frequency is changed at every constant time T1, but the way of the change is changed aiming at a random or fixed frequency. This is because the overlapping distance of the transponder 2 can be estimated in advance from its thickness and the like, and when it is used when the resonance frequency fp1 of the resonance circuit can be grasped to some extent, the time Tr during which the receivable signal from the transponder 2 is returned. Has the effect of being shortened. For example, in a device in which the transponder 2 is in the form of a card and a plurality of transponders 2 are brought close to each other, a card-shaped transponder 2
A holder for storing a plurality of transponders 2 is stored, and a plurality of transponders 2 can be stored in a fixed state. The resonance frequency of the resonance circuit of each transponder 2 is measured in advance in a state of being stored in a holder, and the interrogator 1 uses the frequency at the time of communication, so that the communication can be started without making many transitions of the frequency. It will be possible.

Further, FIG. 7 shows an example in which the frequency of the carrier wave is increased at a constant rate after transmitting at the frequency fc for a certain period of time. In this case, in addition to the detection by the first power supply voltage detection unit 9, a block for measuring the level of the carrier wave is mounted on the transponder 2, and a pulse-like receivable signal is transmitted at the time when the reception amplitude is most obtained. Conceivable. Thereby, the interrogator 1 can recognize the frequency when the receivable signal is returned from the time Tr and stores the frequency. By using the stored frequency for the subsequent communication, the frequency of the carrier wave to be transmitted and the resonance frequency of the responder 2 match, so that the power can be supplied most efficiently.

An example of the circuit of the transmitter of the interrogator 1 is shown in FIG. Reference numeral 15 is an oscillator, 16 is a modulator, 17 is a controller, 2
0 is an amplifier, 18 is a transmitter, and this transmitter 18 has a resistor R
1 and a capacitor Cv and a coil L2, and the capacitance of the capacitor Cv can be variably set by the signal of the CPU according to the method of FIG. 5, FIG. 6 or FIG.

In FIG. 4, when the frequency of the carrier wave transmitted by the interrogator is fp1, the responders 2a and 2b return the receivable signals to the interrogator 1 almost at the same time. The interrogator 1 recognizes the interference state because the responders 2a and 2b reply almost at the same time, and this confirms that the plurality of responders 2a and 2b are present in the communication area 3 and close to each other. Figure out On the other hand, when there is only one responder 2a or 2b, the interrogator 1 can normally receive the receivable signal, and there is a reply during the transmission of the frequency fc. It is set to communicate with the responder 2a or 2b, and normal communication is performed by the communication method as described above.

When the interrogator 1 recognizes that the plurality of responders 2a and 2b have made a reply, the interrogator 1 stores the frequency fp1 that was transmitted when the receivable signal from the responder was replied, and the communication thereafter. Uses fp1. In FIG. 4, the frequency f
At p1, the signal modulated by the command is sent to each of the responders 2a, 2
b. Since the charging voltage of the capacitor C2 is V1 or more, the transponders 2a and 2b are in a state of holding a sufficient power supply voltage to stably operate the internal IC. The carrier demodulates the carrier wave modulated by the command from the interrogator 1, and the result is transmitted to the controller 7.

Here, as the command, a command for reading out data in the memory 11 or a command for writing and write data, etc. can be considered, but together with this, the transponders 2a and 2b are present close to each other in the communication area 3. Command that indicates that This is to notify the fact to the responder in advance so that the signal received by the interrogator 1 such as the receivable signal does not become the interference state, and the memory 11
Be careful not to send the data and so on at the same time. In order not to reply at the same time, each responder 2a, 2b sets the timer 14 shown in FIG. 1 and turns on the switch 13.
It is conceivable that the reply times do not overlap with each other by making the different times. If a command that exists more than one is not included, or if the command indicates that there is only one responder, the timer 14
By setting switch 13 to ON without setting
Since the transponder can immediately return the response data, the communication time can be shortened. In FIG. 4, after recognizing the command, the responder 2a first returns data,
After that, the responder 2b indicates that the data is transmitted.

In the case of the transponder that extracts the clock used for the internal IC from the carrier wave of the interrogator 1, since the carrier wave frequency differs for each communication, the communication time varies depending on the carrier wave frequency. 1 sets the CPU so that the communication time can be measured in consideration of the frequency of the carrier wave being transmitted.

Thus, the interrogator 1 causes the frequencies of the carrier waves to be transmitted to the transponders 2a and 2b existing in the communication area 3 at certain intervals or gradually, while the transponders 2a and 2b respectively The power supply voltage charged in the charging capacitor is detected by the first power supply voltage detection unit 9, and when the power supply voltage reaches a certain power supply voltage value, a signal indicating a stable operation is returned to the interrogator 1, The interrogator 1 uses the transmission frequency at that time for the subsequent communication, so that the plurality of transponders 2
It is possible to avoid the problem of the reduction of the amplitude of the received waveform due to the coupling of the resonance circuits, which occurs when a and 2b are close to each other and are present in the communication area 3, and each transponder 2a and 2b can obtain a sufficient power supply voltage. Then, communication with the interrogator 1 becomes possible.

In the above example, the transmission frequency of the interrogator 1 is changed at a high frequency with reference to fc, but this is for shortening the communication time. ), And since there is a frequency that resonates even at a low frequency as shown in Expression (3), the same effect can be obtained even when the transition is performed at a frequency of fc or less. In addition, in the case of a low frequency, since it can be approximated by the equation (3), the variation of the frequency fp2 is approximated in the range of the following equation even when the coupling coefficient is 1, which is the maximum.

[0046]

(Equation 4)

Therefore, since the interrogator 1 can limit the range of frequency variation due to the coupling of the resonance circuits of the responders 2a and 2b, the carrier frequency may be changed within the range of the formula (4) by the above method. . Further, the number of responding devices that approach each other does not depend on two, and even when a larger number of responding devices are approaching, the same effect can be obtained by using the above method.

Embodiment 2 Next, a second embodiment will be described. 9 is a diagram showing the existing positions of the interrogator and the responder in the communication area, FIG. 10 is a communication flow diagram of the interrogator and the responder, FIG. 11 is a circuit diagram of the receiving unit of the responder, and FIG. FIG. 13 is a circuit diagram showing another example of the receiving unit, FIG. 13 is a communication flow diagram of the interrogator and responder, and FIG. 14 is a circuit diagram showing another example of the receiving unit of the responder.

As shown in FIG. 9, when a plurality of transponders 2a, 2b are present close to each other or at a certain fixed interval, the transponder 2a existing near the interrogator has a normal waveform. However, the transponder 2b, which has a communication distance with the interrogator that is slightly distant from the transponder 2a, is affected by the coupling of the resonance circuits with each other and the current value of the internal circuit of the transponder 2a changes. The internal impedance of 2a changes, and the received waveform is distorted by the influence of the disturbance generated in the resonance circuit of the responder 2b, which may prevent normal communication. These are problems caused by the fact that the power supply voltage charged in the charging capacitor becomes V1 or higher in FIG. 3, but the command cannot be demodulated due to the distortion of the received waveform, or the clock cannot be taken out from the carrier wave. Further, there is a very high possibility that the above-mentioned decrease in the received waveform amplitude may occur due to the coupling of the resonance circuit.

Therefore, in order to solve this problem, a method of shifting the resonance point of the resonance circuit in the transponder which has completed the reply can be considered. An example of the communication state is shown in FIG. The interrogator 1 transmits the frequency of the carrier wave to be transmitted at the beginning of communication at fc by the method of the above-described embodiment, and the responders 2a and 2b.
If there is no response from, change the frequency. Here, since the transponders 2a and 2b resonate at the frequency fp1, when the interrogator 1 transmits the carrier wave of the frequency fp1, it returns a receivable signal. The interrogator 1 detects that the receivable signal is interfering, and transmits the signal modulated by the command at the frequency fp1. However, the responder 2a can normally receive the signal and demodulate it to recognize the command, but the responder 2b cannot demodulate the command from the distortion of the received waveform. Here, the responder 2a reads out the data in the memory 11 or writes the data in the memory 11 according to the command, and returns the data or the execution completion signal to the interrogator 1.

On the other hand, the responder 2a can recognize from the command signal that there is a responder approaching itself, so that it does not affect the resonance circuit of another responder 2b after returning to the interrogator 1. To For example, it is possible to use a circuit as shown in FIG. That is, in FIG. 11, 21 is an FET, and R2 is a resistor connected in series with this FET. In this figure, the FET 21 is turned on to reduce the Q value of the resonance circuit so that the idle mode, that is, the dead mode (DEAD MODE) in FIG. 10 is set.

Further, in FIG. 12, a capacitor C2 is connected in series with the FET 21. In this figure, F
By bringing ET into conduction so that the resonance frequency of the resonance circuit is far away from fc, similarly, the so-called dead mode (DEAD MODE) of FIG. 10 is set.
As a result, the resonance circuit of the transponder 2a does not affect the resonance circuit of the transponder 2 by coupling, and the resonance frequency of the resonance circuit of the transponder 2b returns from fp1 to the original resonance frequency fc.

Since the interrogator 1 recognizes that there are a plurality of responders 2a and 2b because the receivable signals are interfering with each other, after receiving the reply signal from the responder 2a,
The other responder 2b recognizes that the command cannot be recognized because the reply signal from the other responder 2b is in a standby state, but there is no reply. Here, since it is recognized that the responder 2a has performed the operation of eliminating the influence of the coupling of the resonance circuit by the method of FIG. 11 or 12, the carrier frequency of the command to be retransmitted is returned from fp1 to fc. When the transponder 2b receives the command signal transmitted by fc, the resonance circuit of the transponder 2a has no influence, so that a normal waveform and a large received waveform amplitude can be obtained. Yes, data can be returned according to the command. Here, the interrogator has frequency f
After the command is transmitted using the carrier wave of c, if there is no reply signal, it is determined that there is a responder in a close state other than the responders 2a and 2b. Transponder 2a
However, after the response, the resonance frequency of the resonance circuit of the transponder closer to the transponder 2b is fc and fp.
It is different from 1. Therefore, the interrogator 1 transits the frequency again and repeats the above method. This enables communication with all transponders.

Interrogator 1 that received data from the responder 2b
Is to communicate with the responders 2a and 2b again, the interrogator 1
It is conceivable to send a command to notify that the communication has been completed. In that case, the method of FIG. 12 transmits at the frequency at which the resonance circuit of the transponder 2a resonates, or the method of FIG. 11 raises the transmission power at the frequency fc and transmits, or the received signal on the side of the transponder 2a. After the amplification, the responder 2a returns the resonance circuit to the original state after grasping the command for notifying the communication end. After that, the communication with each of the transponders 2a and 2b can be performed again by the same method.

On the other hand, the transponder filters the signal from the interrogator 1 received by the resonance circuit and inputs only the frequency in a certain band to the demodulation section 6 to avoid the influence of disturbance. The band is set to the frequency fc of the carrier wave transmitted by the interrogator 1, the bit rate of the command data, etc. so that it is optimal when only one responder exists in the communication area 3. In the case of ASK, the envelope detection circuit is also optimized at this bit rate and integrated into one chip in the IC. However, in the method in which the interrogator 1 changes the carrier frequency to transmit a command or the like as described above, the bit rate or the like of the data transmitted by the interrogator 1 also differs from the bit rate or the like set in the responder 2. Will end up.

Therefore, the interrogator 1 fixes the frequency of the carrier wave to be transmitted, and FIGS. 13 and 14 show a method in which the transponders 2a and 2b correct the deviation of the resonance frequency of the resonance circuit. FIG.
4, a plurality of switches SW3, SW4 ... SW
n are used, and capacitors C3, C4 ... Cn are connected in series to these switches, respectively. First, the interrogator 1 causes the frequency of the carrier wave to transition within the range of Expression (4) within the communication area 3 at the beginning of communication. This is communication area 3
This is because each of the transponders 2a and 2b that are close to each other is set to have a power supply voltage (V2 in FIG. 3) or more in an operable state. As a method of changing the frequency of the carrier wave, it is possible to make a transition at a certain ratio as shown in FIG. The transponder 2 can hold the operable power supply voltage (V2) by receiving the transitioned frequency, but does not resonate up to the power supply voltage (V1 in FIG. 3) capable of performing stable operation. Since the resonance frequency of the circuit does not match the frequency of the carrier wave transmitted by the interrogator 1, it cannot be reached. Therefore, the resonance frequency of the resonance circuit is corrected by the circuit as shown in FIG.

The resonant circuits of the transponders 2a and 2b are L1 and C, respectively.
In parallel with 1, a capacitor of C3 to Cn and switches SW3 to SWn connected in series with the capacitor are formed. The interrogator 1 shifts the frequency of the carrier wave, and then uses the frequency fc of the carrier wave used when communicating with one transponder 2a.
The unmodulated wave of is transmitted. At this time, the responders 2a and 2b turn on the switches SW3 to SWn gradually or in a set order and timing in response to a signal from the control unit 7. When the switch is turned on, the resonance frequency of the resonance circuit changes due to the capacitors C3 to Cn connected in parallel to the resonance circuit. Each of the transponders 2a and 2b monitors the power supply voltage charged in the charging capacitor by the first power supply voltage detection unit 9 of FIG. 1 and confirms whether the power supply voltage capable of stable operation is held. . When the power supply voltage becomes V1 or higher, the resonance frequency of the resonance circuit of each of the transponders 2a and 2b becomes fc.
It means that the resonance frequency has been corrected.

In FIG. 13, responder 2a and responder 2b
Then, the resonance frequency of the resonance circuit before correction is almost the same,
Further, the switches SW3, SW4 ... SWn in FIG.
Since the N timings are made equal, the power supply voltage V1 capable of stable operation is held almost simultaneously, and the receivable signal is returned almost at the same time. After returning the receivable signal, the resonant frequency of the resonant circuit of each transponder 2a, 2b becomes
It is almost corrected to the frequency fc of the carrier wave transmitted by the interrogator 1. The subsequent communication is performed by the method described above.

In FIG. 14, the switch SW is turned ON / O.
Although the resonance frequency of the resonance circuit is made variable by performing FF, an FET may be connected instead of the switch SW, and the resonance frequency may be changed by conduction / non-conduction of the FET. Here, the power supply voltage charged in the charging capacitor C2 is the first
The method of monitoring by the power supply voltage detection unit 9 has been described, but it is detected that the amplitude of the received waveform is amplified as the resonance frequency of the resonance circuit is corrected, and the resonance circuit with the largest amplitude is used. You may do it.

Since the interrogator 1 sets the frequency of the carrier wave to fc at the time of transmitting a command, it can communicate at the same bit rate as when there is only one responder in the communication area 3. It will be possible. In addition, each responder 2a, 2
b is capable of correcting the shift of the resonance frequency of the resonance circuit caused by the coupling of the resonance circuit, holding the power supply voltage capable of stable communication when the frequency of the carrier wave is fc, and also the bit rate of the received signal. It is the same as when the other transponder 2b is not close. Therefore, each responder 2a, 2b
Since constants such as a filter capacity in the IC and a capacitor capacity and a resistance value of the demodulation unit 6 are suitable for communication at the carrier frequency fc at the time of manufacturing, even when the transponders 2a and 2b are close to each other. , Optimal operation is possible. In addition, as described above, when three or more transponders are overlapped, equations (2) and (3) cannot be applied, but if there is a signal from the interrogator 1 to each transponder in the same manner, each transponder Can secure a sufficient power supply voltage.

[0061]

According to the first aspect of the present invention, the interrogator 1 has a function of scanning the resonance frequency of the resonance circuit of each transponder and transmitting a command or data by using the carrier of the recognized resonance frequency of each transponder. Therefore, when multiple transponders are in close proximity to each other in the communication area, it is possible to avoid a drop in the received waveform amplitude that occurs when the resonant frequency changes due to the coupling of the resonant circuits, and each transponder There is an effect that a sufficient power supply voltage can be obtained and normal communication with the interrogator 1 becomes possible.

According to the second aspect of the present invention, the frequency of the carrier wave transmitted by the interrogator 1 is transmitted to the communication area where the transponders may be close to each other, and the transponders transmit, while the transponder operates stably. When it becomes possible to send a message to the interrogator 1, the interrogator 1 receiving this message stores the frequency of the carrier wave at that time, and thereafter the communication with the responder is stored at the stored frequency. Since it has a function of transmitting, when a plurality of transponders are close to each other and exist in the communication area, reception generated by changing the resonance frequency due to mutual coupling of the resonance circuits, as in claim 1. It is possible to avoid a decrease in the waveform amplitude and to obtain a sufficient power supply voltage for each transponder, thereby enabling normal communication with the interrogator 1.

The invention of claim 3 has the function of causing the interrogator 1 to make a transition at a constant frequency interval at a constant time interval in the second aspect, so that a plurality of transponders are provided as in the first aspect. , Which is close to each other in the communication area, avoids a decrease in the received waveform amplitude that occurs when the resonance frequency changes due to the mutual coupling of the resonance circuits, and each responder can obtain a sufficient power supply voltage. This has the effect of enabling normal communication with the interrogator 1.

According to a fourth aspect of the present invention, in the second aspect, the interrogator 1 has a function of selecting a random frequency at a certain fixed time and making a transition. When the transponders of the above are in close proximity to each other in the communication area, each transponder can obtain a sufficient power supply voltage by avoiding the decrease of the received waveform amplitude caused by the change of the resonance frequency due to the mutual coupling of the resonance circuits. Therefore, there is an effect that normal communication with the interrogator 1 becomes possible.

According to the invention of claim 5, in claim 2, since the interrogator 1 has a function of selecting a preset frequency and making a transition at a constant time interval, the same as in claim 1. , When a plurality of transponders are close to each other in the communication area, the decrease of the received waveform amplitude caused by the change of the resonance frequency due to the mutual coupling of the resonance circuits is avoided,
Each transponder can obtain a sufficient power supply voltage, and the interrogator 1
With this, it is possible to perform normal communication with the mobile phone, and to reduce the transition frequency to shorten the communication time.

The invention of claim 6 has a function of setting a plurality of transponders in a state of being fixed by a holder in claim 5, so that the plurality of transponders approach each other as in the case of claim 1. In the communication area, it is possible to avoid a drop in the received waveform amplitude that occurs when the resonance frequency changes due to mutual resonance circuit coupling, and each responder can obtain a sufficient power supply voltage. It is possible to perform normal communication with the No. 1 and to fix the deviation of the resonance frequency of the resonance circuit of each responder.

According to a seventh aspect of the invention, in the second aspect, the interrogator 1 has a function of shifting the frequency at a certain fixed rate. Therefore, as in the first aspect, a plurality of responders approach each other. In the communication area, it is possible to avoid a drop in the received waveform amplitude that occurs when the resonance frequency changes due to mutual resonance circuit coupling, and each responder can obtain a sufficient power supply voltage. 1 has the effect of enabling normal communication with the No. 1 and each of the transponders can perform subsequent communication at the frequency of the carrier wave when the received waveform amplitude is maximum.

According to an eighth aspect of the present invention, in the first or second aspect of the invention, among the transponders, the transponder that has completed transmission has a function of changing the resonance frequency of the resonance circuit.
Similarly to claim 1, when a plurality of transponders are present close to each other in a communication area, the reduction of the received waveform amplitude caused by the change of the resonance frequency due to the mutual coupling of the resonance circuits is avoided, and each transponder is responded. Can obtain a sufficient power supply voltage and can normally communicate with the interrogator 1. Furthermore, since the transponders that have completed transmission have the function of changing the resonance frequency of the resonant circuit, other transponders will not be affected by the coupling of the resonant circuits of the transponders that have completed transmission, and the subsequent communication will not be performed. There is an effect that it becomes possible to perform.

According to a ninth aspect of the present invention, in the first or second aspect, the transponder that has completed transmission has a function of lowering the Q value of the resonance circuit.
Similarly, when multiple transponders are in close proximity to each other in the communication area, avoiding a decrease in the received waveform amplitude that occurs when the resonant frequency changes due to the mutual coupling of the resonant circuits, and each transponder has sufficient The power supply voltage can be obtained, and normal communication with the interrogator 1 becomes possible. Furthermore, since the transponder that has completed transmission has the function of lowering the Q value of the resonant circuit, other transponders will not be affected by the coupling of the resonant circuit of the transponder that has completed transmission, and will perform subsequent communications. There is an effect that it can be performed.

According to a tenth aspect of the present invention, the interrogator 1 is provided with a transmitting means composed of a series resonance circuit of a resistor, a variable capacitor and a coil, a receiving means for receiving response data from the responder, and a demodulator. The transponder has a transmitting / receiving means composed of a parallel resonant circuit of a coil and a capacitor, and a power supply voltage detecting means for detecting a power supply voltage higher than a voltage detected by the internal power supply voltage detecting means. Similarly, when multiple transponders are in close proximity to each other in the communication area, avoiding a decrease in the received waveform amplitude that occurs when the resonant frequency changes due to mutual resonance circuit coupling, and each transponder has a sufficient power supply. The voltage can be obtained, and the communication with the interrogator can be normally performed.

According to the eleventh aspect of the invention, the frequency of the carrier wave transmitted by the interrogator is transmitted to the communication area where the transponders may be close to each other, and the transponders reach the operable state. After that, the resonance frequency of the resonance circuit is corrected by the carrier of the fixed frequency transmitted by the interrogator, the interrogator transmits the command data at the fixed frequency, and the responder uses the corrected resonance circuit and the interrogator. Since it has a function of performing subsequent communication, when a plurality of transponders are close to each other and exist in the communication area, the resonance frequency changes due to the mutual coupling of the resonance circuits. Each transponder can obtain a sufficient power supply voltage while avoiding a decrease in the received waveform amplitude that occurs, and normal communication with the interrogator becomes possible. Furthermore, the frequency at which the interrogator sends commands etc. is fixed,
Since each responder corrects the resonant frequency of the resonant circuit to the fixed frequency, there is an effect that communication can be performed while the constants of the filter and the demodulation unit in the IC of the responder are kept optimal.

According to the twelfth aspect of the invention, since the resonance circuit of the responder is corrected by the plurality of capacitors connected in parallel with the resonance circuit, the plurality of responders approach each other as in the first aspect. When in the communication area, avoiding a decrease in the received waveform amplitude that occurs when the resonant frequencies change due to mutual resonance circuit coupling, and each transponder can obtain a sufficient power supply voltage. Normal communication is possible. Further, as in the eleventh aspect, the frequency at which the interrogator transmits a command or the like is fixed, and each responder corrects the resonant frequency of the resonant circuit to the fixed frequency.
Communication can be performed while the constants of the filter and demodulation unit in C remain optimal. Further, since the resonance frequency of the resonance circuit is corrected by the plurality of capacitors, there is an effect that the circuit configuration is simple and can be corrected by this simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of a non-contact data transmitting / receiving apparatus according to the present invention.

FIG. 2 is a flowchart showing a temporal signal flow when an interrogator and a responder perform one-to-one communication.

FIG. 3 is a characteristic diagram showing a change in transponder power supply voltage due to a change in carrier frequency.

FIG. 4 is a flowchart showing a communication flow between an interrogator and a plurality of responders.

FIG. 5 shows the frequency of the carrier wave transmitted by the interrogator for a certain time T
It is a transition diagram which shows the transition method which raises for every 1.

FIG. 6 shows the frequency of the carrier wave transmitted by the interrogator for a certain time T
FIG. 6 is a transition diagram showing a transition method in which each target is changed randomly or at a fixed frequency.

FIG. 7 is a transition diagram showing a transition method in which the frequency of the carrier wave transmitted by the interrogator is transmitted at a predetermined frequency for a certain period of time and then the frequency of the carrier wave is increased at a constant rate.

FIG. 8 is a circuit diagram showing an example of a transmission circuit of an interrogator of the contactless data transmission / reception device according to the present invention.

FIG. 9 is a non-contact data transmission / reception device of the present invention,
It is the figure which showed the existence position in the communication area of an interrogator and each responder.

FIG. 10 is a communication flow diagram of an interrogator and a responder of the non-contact data transmitter / receiver according to the present invention.

FIG. 11 is a circuit diagram of a receiver of a transponder of the contactless data transmitter / receiver according to the present invention.

FIG. 12 is a circuit diagram showing another example of the receiving unit of the transponder of the contactless data transmitter / receiver according to the present invention.

FIG. 13 is a communication flow diagram of an interrogator and a responder of the non-contact data transmitter / receiver according to the present invention.

FIG. 14 is a circuit diagram showing another example of the receiving unit of the transponder of the contactless data transmitter / receiver according to the present invention.

FIG. 15 is a block diagram showing a conventional non-contact data transmission / reception device.

FIG. 16 is a characteristic diagram showing a general relationship between a distance between two transponders and a reception level.

FIG. 17 is a characteristic diagram showing a general relationship between the frequency and the impedance of the resonance circuit depending on the distance between the transponders.

[Explanation of symbols]

 1 Interrogator 2 Responder 3 Communication Area 4 Transmitter / Receiver 5 Parallel Resonance Circuit 6 Demodulator 7 Controller 8 Power Supply 9 First Power Supply Voltage Detector 10 Second Power Supply Voltage Detector 11 Memory 12 Modulator 18 Transmitter L1 Coil C1 capacitor C2 charging capacitor

Claims (12)

[Claims] 1. An interrogator transmits a command or data to the responder, the responder accesses an internal memory for the command, and the responder transmits response data to the interrogator. In the non-contact data transmission / reception device, the interrogator scans the resonance frequency of the resonance circuit of each responder, and transmits the command data by using the carrier of the recognized resonance frequency of each responder. Contact data transmission / reception method. 2. The interrogator transmits a command or data to the responder, the responder accesses an internal memory for the command, and the responder transmits response data to the interrogator. In the contactless data transmitter / receiver, the interrogator transits the frequency of the carrier wave to be transmitted to a communication area in which the transponders may exist close to each other, and the transponder transmits the internal operating power supply. When the voltage becomes equal to or higher than the set voltage value, it sends a signal to the interrogator to notify that stable operation is possible, and the interrogator changes the carrier wave when the signal is received. A non-contact data transmission / reception method characterized in that a frequency is stored, and after the storage of the frequency, communication with the transponder is transmitted at the stored frequency. 3. The non-contact data transmission / reception method according to claim 2, wherein the interrogator makes a transition at a constant frequency interval at a constant time interval. 4. The non-contact data transmission / reception method according to claim 2, wherein the interrogator selects and makes a transition at a random frequency at every certain time. 5. The non-contact data transmission / reception method according to claim 2, wherein the interrogator selects a preset frequency and makes a transition at regular intervals. 6. The non-contact data transmission / reception method according to claim 5, wherein the plurality of transponders are set in a fixed state by a holder. 7. The non-contact data transmitting / receiving apparatus according to claim 2, wherein the interrogator makes frequency transition at a certain fixed rate. 8. The non-contact data transmission / reception method according to claim 1, wherein the transponder that has completed transmission among the transponders has a different resonance frequency of a resonance circuit. 9. The non-contact data transmission / reception method according to claim 1 or 2, wherein, of the transponders, the transponder that has completed transmission has a reduced Q value of a resonance circuit. 10. The interrogator transmits a command or data to the responder, the responder accesses an internal memory for the command, and the responder transmits response data to the interrogator. In the non-contact data transmitter / receiver, the interrogator receives a modulator, a signal controller, a transmitter configured by a series resonance circuit including a resistor, a variable capacitor and a coil, and response data from a responder. Receiving means and a demodulating section are provided, and the responding section includes a modulating section and a parallel resonance circuit of a coil and a capacitor, and transmitting and receiving means for transmitting and receiving signals to and from the interrogator, and Demodulation means for demodulating a signal, internal power supply means for converting the carrier wave from the interrogator into direct current, and using the direct current power as the internal power supply of the responder, Control means for controlling signals from the transmitting / receiving means of the responder, memory for storing data, internal power supply detecting means for detecting voltage supplied to the inside of the responder, and voltage detected by the internal power supply detecting means. A non-contact data transmission / reception device comprising a power supply voltage detection means for detecting a higher voltage. 11. The interrogator transmits a command or data to the responder, the responder accesses an internal memory for the command, and the responder transmits response data to the interrogator. In the contactless data transmission / reception device, the interrogator transits the frequency of the carrier wave to be transmitted to a communication area where the transponders may exist close to each other, and transmits the transponder. After reaching, the resonance frequency of the resonance circuit is corrected by the carrier of the fixed frequency set in advance transmitted by the interrogator, the interrogator transmits the command data by the carrier of the fixed frequency, and the responder is A non-contact data transmission / reception method, characterized in that subsequent communication with the interrogator is performed by a corrected resonance circuit. 12. An interrogator transmits a command or data to a plurality of transponders existing close to each other in a communication area, and the transponder accesses an internal memory for the command and responds to the response. In a non-contact data transmitter / receiver for transmitting response data from the interrogator to the interrogator, the interrogator includes a modulator, a signal controller, and a series resonance circuit including a resistor, a variable capacitor, and a coil. Means, a receiving means for receiving response data from the responder, a demodulation portion, and a control portion for controlling the transmission frequency of the carrier wave transmitted from the transmitting means to be transited, and the responder has a modulator. Section, a parallel resonance circuit of a coil and a capacitor, and transmitting / receiving means for transmitting / receiving signals to / from the interrogator, and the transmitting / receiving means. Demodulating means for demodulating these signals, an internal power source means for converting the carrier wave from the interrogator into a direct current, and using the direct current power as the internal power source of the responder, and a signal from the transmitting / receiving means of the responder. Correspondingly, a control means for controlling the resonance frequency of the parallel resonance circuit to transition is provided, and a memory for storing data. Further, the parallel resonance circuit of the responder is provided to the parallel resonance circuit by the control means. A non-contact data transmission / reception device comprising a plurality of capacitors selectively connected in parallel.