JP2000059261A - Non-contact data transmission / reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate a bit rate by judging the phase of a modulated wave from a transponder as soon as possible in the interrogator. SOLUTION: The transponder 2 sends a signal obtained by inverting the phase of a modulated wave B each time a digital value constituting answer data changes. The interrogator 1 extracts a signal having the same cycle as the modulate wave B and inputs a rectangular wave F(0) having the same cycle as the modulated wave B from an oscillator part 4 to a demodulation part 9. This rectangular wave F(0) is shifted by a shift register to obtain a reference signal synchronized with the modulated wave B. Then data are decided as, for example, '1' and '0' when the modulated wave B and reference wave are coincident in phase and not coincident with each other respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact data transmission / reception device.

[0002]

2. Description of the Related Art Conventionally, as a system for managing entry and exit of a production line, a distribution line, and an office of a factory, an ID card is attached to a tool or a luggage to return response data to a question, For example, a method and apparatus for managing a work by carrying out a non-contact response to a question while possessing the same are known. In such a non-contact data transmission / reception device,
A unique ID code, product number, data at the time of manufacture, and the like are registered in the transponder, and the transponder is identified by non-contact communication of the data between the transponder and the interrogator.

FIG. 7 is a schematic diagram showing a general use state of an interrogator and a transponder of such a non-contact data transmitting / receiving apparatus. In FIG. It is a transponder which communicates with the device 1.

FIG. 8 is a block diagram showing a configuration of a conventional non-contact data transmission / reception apparatus. In FIG. 8, an interrogator 1 includes an oscillator 4, a modulator 5, a transmitter 6, a receiver 7, a filter 8 The transponder 2 includes a receiving unit 11, a rectifying circuit 18, a power supply circuit 12, a demodulating unit 13, a control unit 14, a memory 15, and a modulating unit 1.
6 and a transmission unit 17. In addition, Cv
Is a charging capacitor connected to the power supply circuit 12,
Used as a power supply for the transponder 2.

Next, the operation will be described. In general, when performing transmission and reception by this non-contact data transmitting and receiving apparatus, a use state as shown in FIG. 7 is adopted. That is, when there is a transponder 2 in the communication area 3, the interrogator 1 communicates with the transponder 2. At this time, the interrogator 1 and the transponder 2 in the conventional non-contact data transmitting / receiving device are
Reading of data in a memory built in the transponder 2,
Alternatively, a command for performing writing, write data, or the like is modulated into a high-frequency signal from the oscillator unit 4 by the modulation unit 5 and transmitted. As a modulation method, ASK (Amplitude Shift Keying) for changing the amplitude of a high-frequency signal can be considered.

The transponder 2 obtains the driving power of the internal LSI from the high-frequency signal transmitted from the interrogator 1, and extracts commands and data by envelope detection in the demodulation unit 13 and further extracts a clock for operating the internal LSI. I do. Control unit 1
4 performs processing such as access to the internal memory 15 according to the processing content of the command from the interrogator 1.

[0007] Normally, when the mobile terminal deviates from the communication area 3, the internal power cannot be generated.
A non-volatile memory such as OM is used. Interrogator 1 for writing to memory 15 or reading from memory 15
After processing the command sent from the
Transmits the response data to the interrogator 1.

The response data includes data read from the memory 15 and a result of processing a command from the interrogator 1. The transponder 2 returns a modulated wave modulated with the response data by the modulator 16 to the interrogator 1 by the transmitter 17, and the transponder 2 generates an internal power supply from the high-frequency signal from the interrogator 1. Therefore, when replying, the reply is made with a weak radio wave so that the power supply is not lowered and the operation is not stopped.

As a modulation method, ASK or FSK (Frequequent
ncy Shift Keying) can be considered, but PSK (Phase Shift Keying) which is usually good in quality and can be set at one frequency when the modulated wave from the transponder 1 received by the interrogator 1 is filtered by the filter 8 Etc. are considered valid. In particular, in the transponder 2, the digital value "1",
Binary PSK in which the phase is inverted by 180 degrees at “0” is used.

FIG. 9 shows an output waveform example of each block of the interrogator 1 and the responder 2. The transponder 2 generates a modulated wave B based on binary PSK in the modulating unit 16 according to the digital value A from the control unit 14. The transmitting unit 17 returns the signal C to the interrogator 1 using a method such as changing the Q value of the antenna.

On the other hand, the receiving unit 7 of the interrogator 1 receives the response data from the transponder 2 and performs filtering by the filter 8. Here, the filtering is performed so that the transponder 2 can take out the frequency component of the binary PSK modulated. Since the return signal from the transponder 2 is weak, a signal D excluding as much as possible the frequency components other than the binary PSK frequency component is output to the demodulation unit 9.

The demodulation unit 9 detects the phase of the signal D from a plurality of wave numbers of the signal D using a phase detector such as an analog PLL as shown in FIG. 9 and locks the phase to obtain a digital value. Demodulate.

[0013]

Since the conventional non-contact data transmitting / receiving apparatus is configured as described above, when a phase detector such as an analog PLL is used, it is necessary to determine the phase of an input signal. Since multiple wave numbers are required, and it takes a certain period to determine the digital value,
It is necessary to secure a length of one bit, and the bit rate cannot be increased.

As shown in FIG. 9, since the noise cannot be sufficiently eliminated from the output of the filter 8, the input signal is disturbed by the noise while the phase of the signal D is locked by the phase detector. In this case, it takes more time to lock the phase.

In particular, in the non-contact data transmission / reception device, since the receiving section 7 of the interrogator 1 is configured by a resonance circuit or the like in order to receive a weak radio wave from the transponder 2,
When the phase of the modulated wave from is switched, the waveform becomes dull, and it is highly likely that it takes time for the modulated wave to stabilize after the phase is switched.

When the interrogator 1 demodulates the binary PSK return signal from the transponder 2, the demodulator 9 outputs the analog PSK signal.
The signal is demodulated to a digital value by locking the phase using a phase detector such as L. However, a plurality of wave numbers are required to determine the phase of the input signal, and a constant is required until the digital value is determined. Since a period is required, it is necessary to secure a long length of one bit, and the bit rate cannot be increased.

Further, since noise cannot be completely eliminated from the output of the filter 8, if the input signal is disturbed by the noise while the phase is locked by the phase detector, the time for further locking the phase is obtained. Will take.
The conventional non-contact data transmission / reception device has a problem that such a point must be solved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can transmit accurate digital data from a transponder to an interrogator with a relatively simple configuration. It is an object of the present invention to obtain a non-contact data transmission / reception device capable of judging the phase of a modulated wave as soon as possible and improving a bit rate.

[0019]

According to the present invention, there is provided a non-contact data transmission / reception apparatus, wherein a transponder transmits a modulated wave, which is phase-modulated based on a digital value constituting response data, as a transmission signal. Receiving means for receiving a transmission signal from a transponder, extracting a modulation wave from the transmission signal, and a reference signal synchronized with a modulation wave corresponding to at least one digital value constituting the response data , A phase comparison unit that compares the phase of the modulated wave extracted by the reception unit with the phase of the reference signal acquired by the synchronization unit, and a response based on the comparison result of the phase comparison unit. Data determining means for determining a digital value constituting the application data.

The non-contact data transmission / reception device according to the present invention is configured such that the transmission means of the transponder inverts the phase of the modulated wave to generate a transmission signal every time the digital value forming the response data changes. It was done.

In the non-contact data transmitting / receiving apparatus according to the present invention, the transmitting means of the transponder transmits a modulated wave whose phase is not inverted during the first predetermined period of the response data.

In the non-contact data transmitting and receiving apparatus according to the present invention, the synchronization acquisition means may include a shift register for shifting a signal having the same cycle as the modulated wave from the transponder, and a phase of the output signal of the shift register may be changed to a phase of the modulated wave. And a synchronization acquisition circuit that outputs the output signal of the shift register as a reference signal to the phase comparison means when the phase of the output signal of the shift register matches the phase of the modulated wave. .

In the non-contact data transmitting and receiving apparatus according to the present invention, the phase comparison means samples the reference signal and the value of the extracted modulated wave with a clock faster than the reference signal output from the synchronization acquisition means, and performs sampling. Counts up when the logic of the reference signal and the modulation wave match,
It is provided with a counter that is reset every predetermined period, and is configured to output the count number of the counter as a result of comparison between the phase of the modulated wave and the phase of the reference signal.

[0024] In the contactless data transmitting and receiving apparatus according to the present invention, the phase comparison means samples the reference signal and the value of the extracted modulated wave with a clock faster than the reference signal output from the synchronization acquisition means, and performs sampling. When the logic of the reference signal coincides with the logic of the modulation wave, each of the counters is counted up and reset at predetermined intervals. It is configured to output the count number of each counter as a result of comparison between the phase and the phase of the reference signal.

In the non-contact data transmitting and receiving apparatus according to the present invention, the data discriminating means is configured to set a count value output from the phase comparing means and a preset threshold for each cycle of the reference signal output from the synchronization acquiring means. It is configured to include a data determination circuit that determines whether or not the phases of the reference signal and the modulated wave are in phase by comparing the values with each other, and determines a digital value that forms the response data.

In the contactless data transmitting / receiving apparatus according to the present invention, the data discriminating means compares the count number of each counter output from the phase comparing means with a preset threshold value, and compares the reference signal with the modulated wave. A data determination circuit configured to determine whether the phases are in phase, count the result by a counter, and determine a digital value forming the response data based on the count number of the counter. Things.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. 1 is a block diagram showing a configuration of a contactless data transmitting / receiving apparatus according to Embodiment 1 of the present invention. The same components as those of the conventional device are denoted by the same reference numerals and description thereof is omitted. However, in the first embodiment, unlike the configuration of the conventional device, the oscillator unit 4 sends the demodulation unit 9 the A square wave F (0) having the same cycle as the modulated wave corresponding to at least one digital value forming the response data is input.

In FIG. 1, reference numeral 21 denotes a transmitting / receiving section (transmitting means) of the transponder 2. The transmitting / receiving section 21 includes one parallel resonance circuit including a coil L1 and a capacitor C1 corresponding to a receiving section and a transmitting section. It comprises a resistor R1 and an FET (field effect transistor) 1.

In the interrogator 1, the transmitting section 6 includes a series resonance circuit including a capacitor C6, a resistor R6 and a coil L6, and the receiving section 7 includes a parallel resonance circuit including a coil L7 and a capacitor C7. .

However, the configuration of the non-contact data transmission / reception device shown in FIG. 1 is an example, and the transmission / reception unit 21 may be provided separately and the antennas may be separately provided. There is no problem in transmitting the signal by transmitting the radio wave from the transponder 2 instead of causing the change. Further, the components other than the resonance circuit and the charging capacitor of the transponder 2 may be integrated into one chip using an LSI to reduce the size and cost of the transponder 2.

FIG. 2 is a diagram showing the configuration of the demodulation unit 9. 2, reference numeral 91 denotes a waveform shaping circuit (phase comparing means); 92, a synchronization acquiring circuit (synchronizing acquiring means); 93, a shift register (synchronizing acquiring means); 94, a counter (phase comparing means); (Data determining means), 96 is a clock generator (data determining means,
In the figure, it is described as "CLK GEN." ).

Next, the operation will be described. The interrogator 1 emits a high-frequency signal to the transponder 2 existing in the communication area 3 by the transmission unit 6, that is, the series resonance circuit having an antenna function. The series resonance circuit constituting the transmitting section 6 of the interrogator 1 is for transmitting power efficiently to the transponder 2, but the configuration is not limited to this as long as it has the same function.

The high-frequency signal is obtained by modulating the signal from the oscillator 4 by the modulator 5 in accordance with a digital data command transmitted to the transponder 2 from the controller 10. As the command, for example, the memory 1 in the transponder 2
5, a command to read and return a unique ID code and various data stored in the memory 5, a command to write non-contact data to the memory 15, and the like.

Here, the interrogator 1 uses the ASK
The high-frequency signal is modulated by FSK or FSK, and the modulated signal is transmitted from the series resonance circuit of the transmission unit 6.

On the other hand, the transponder 2 receives a signal from the interrogator 1 in a parallel resonance circuit including the coil L1 and the capacitor C1. The high-frequency signal from the interrogator 1 is transmitted to the rectifier circuit 18 and the demodulation unit 13 connected to the resonance circuit.
8, and is charged into the charging capacitor Cv through the power supply circuit 12. The power supply charged in the charging capacitor Cv is used by the power supply circuit 12 as a power supply for the internal circuit (LSI) of the transponder 2. The rectifier circuit 18 is a full-wave rectifier or a half-wave rectifier.

The resonance circuit is also connected to the demodulation unit 13,
It demodulates the modulated wave from the interrogator 1 and extracts the operating clock of the transponder 2. Examples of the demodulation method include envelope detection in ASK and detection using PLL in FSK. The transponder 2 also uses the high frequency signal from the interrogator 1 as a clock for operation. Demodulation unit 1
The digital data demodulated in 3 is transmitted to the control unit 14. In accordance with the command transmitted from the interrogator 1, the control unit 14 performs processing such as reading data from the memory 15 or writing data transmitted following the command.

In the first embodiment, since the transponder 2 obtains the internal power from the modulated wave from the interrogator 1, the memory 15 uses a nonvolatile memory such as an EEPROM.
For example, when a battery backup power supply can be secured by mounting a battery, a volatile memory such as an SRAM may be used.

The control unit 14 transmits data and the like read from the memory 15 to the modulation unit 16. The modulation unit 16 modulates the data in accordance with the data, and transmits and receives data to the transmission / reception unit 21 having a resonance circuit.
Send back at

Here, the reply method of the transponder 2 will be described. Hereinafter, an example in which the transponder 2 receives a read command of data in the memory 15 from the interrogator 1 will be described. However, as described above, the commands of the interrogator 1 include commands for writing to the memory 15 and other processing. is there.

The control unit 14 of the transponder 2 reads from the memory 15
The digital value A as shown in FIG. 3 is read, and the digital value A is transmitted to the modulation unit 16 bit by bit. Modulation unit 1
At 6, the high frequency signal is modulated in accordance with the digital value A. Although various types of modulation schemes are conceivable, a binary PSK that can form a filter having a steep frequency characteristic is effective because communication quality is good and since the same frequency is used when filtering is performed by the interrogator 1, PSK such as value
Alternatively, select an appropriate one for each system.

Since the transponder 2 uses the high-frequency signal from the interrogator 1 also as an operation clock, the modulator 16
Then, the clock is frequency-divided to generate a modulated wave B by binary PSK. In the first embodiment, one bit of the digital value A is composed of four modulated waves B as shown in FIG.
Since the response data is constituted by binary digital values, the phase of the modulated wave B is inverted by 180 degrees when the bit changes, but the phase difference may be 90 degrees regardless of this. Select an appropriate one for each.

The transmission / reception unit 2 according to the signal from the modulation unit 16
1, a response is sent. In FIG. 1, by turning on and off the gate of the FET, the resistance R1
, And the impedance of the transponder 2 is changed. This causes a change in the component of the modulated wave B from the transponder 2 in the high-frequency signal in the communication area 3,
The interrogator 1 can detect this small change in the receiving unit 7.

In this method, since the interrogator 1 outputs a non-modulated wave from the transmission unit 6, the reception waveform of the transmission / reception unit 21 of the transponder 2 becomes like the high-frequency signal C in FIG. However, it is possible to continuously extract the power and the operation clock.

The interrogator 1 detects a minute change in the high-frequency signal C generated by the response of the transponder 2 in the receiving unit 7, and filters the high-frequency signal C by the filter 8.

The filter 8 is a modulated wave B returned from the transponder 2.
It is desirable to have a frequency characteristic that allows only the frequency of the signal to be extracted. However, since an increase in circuit size leads to an increase in cost, external noise such as the signal D cannot be completely removed. , A filter circuit that is simply composed of a coil, a capacitor, a resistor, and the like is used.

The receiving section 7 of the interrogator 1 is composed of a parallel resonance circuit that resonates with the signal D in order to extract a weak signal from the transponder 2. In this case, the modulated wave of the transponder 2 Since the frequency component is different in the portion where the phase is switched by 180 degrees in B, there is a possibility that the noise is superimposed as in the signal D or the waveform is rounded. In the first embodiment, a method is used in which such extraneous noise and dullness of the extracted waveform can be ignored as much as possible.

Next, the operation of the demodulator 9 of the interrogator 1 will be described. The signal D output from the filter 8 is input to the waveform shaping circuit 91 of the demodulation unit 9,
1, the waveform is shaped as shown in FIG. 3, and a square wave E is output. The waveform shaping circuit 91 may be simply an inverter or a circuit having a threshold value capable of removing external noise. The shaped square wave E is input to a synchronization acquisition circuit 92 and a counter 94.

Since the modulated wave B transmitted by the transponder 2 has two phases according to the digital value data A, the interrogator 1 generates the reference signal F synchronized with one of the phases. . The generation method is shown in FIG.

When transmitting the response data, the transponder 2 transmits the same digital value as the header for the first few bits. The logic of the digital value of the header may be either "0" or "1" as long as it is determined in the system.

The signal from the receiving unit 7 is filtered by the filter 8 to output a signal D. The waveform shaping circuit 91 performs waveform shaping and outputs a square wave E, which is input to the synchronization acquisition circuit 92. .

On the other hand, a square wave F (0) having the same cycle as the modulated wave B transmitted from the transponder 2 is input from the oscillator unit 4 to the shift register 93. In the responder 2, the interrogator 1
The high-frequency signal is divided to generate a clock, and no oscillator is provided. Therefore, the interrogator 1 and the transponder 2 use a signal having the same frequency as that of the oscillator unit 4 and can be synchronized. Become.

The shift register 93 shifts the square wave F (0) using a clock several tens times faster than the square wave F (0). The clock frequency and the number of stages of the shift register 93 are not limited, but the higher the clock frequency and the greater the number of stages, the more accurate synchronization can be achieved. The square wave F (1) to F (n) output from the shift register 93 and the square wave E output from the waveform shaping circuit 91 are synchronized with the synchronization acquisition circuit 9
2 and compare the phases of the two signals.

As a comparison method, it is conceivable to count up when the logic of the signal matches with a high-speed counter and select the one with the largest count number. In the example shown in FIG. 4, since the square wave whose phase is closest to the square wave E is F (2), the square wave F (2) is output as the reference signal F output from the synchronization acquisition circuit 92. I have.

During synchronization, that is, during transmission of the header from the transponder 2, there is no change in the digital value and no change in the phase of the signal D.
In the signal D output from, there is almost no waveform distortion, and a signal having the same cycle can be extracted for each wave. Also,
Although the number of bits used as a header is variable for each system, it is appropriate to set the number of bits to be equal to or greater than the number of modulated waves from the transponder 2 that can reliably acquire synchronization.

When the synchronization acquisition circuit 92 can select the reference signal F synchronized with one of the digital values of the reply signal from the transponder 2, the interrogator 1 demodulates the response data after the header from the transponder 2. A system that can do it. That is, for demodulation of response data after the header, the counter 94
Compares the phase of the reference signal F selected by the synchronization acquisition circuit 92 with the phase of the square wave E output from the waveform shaping circuit 91. If both phases are the same, the bits have the same logic as that transmitted in the header. If the phase is inverted, it is determined that the bit is different from the bit transmitted in the header.

FIG. 3 shows an example in which the phases are the same, that is, the bit transmitted by the transponder 2 in the header is "1".
Reference signal F and square wave E output from waveform shaping circuit 91
Is input to the counter 94, and the phases of the two signals are compared in the same manner as in synchronization acquisition.

The signal G in FIG. 2 shows the transition of the count value of the counter 94, and counts up when the logics of the two signals match, and the count value of the counter 94 is reset every time the reference signal F rises. You. The frequency of the clock used for counting is the modulated wave B from the transponder 2.
It is appropriate that the number is several tens of times or more.

Here, in the data judgment circuit 95, the upper limit value th_u and the lower limit value th_d are set in advance, and if the count number is equal to or more than the upper limit value th_u, it is regarded that the phases match, and the data judgment circuit 95 Output data I
Is “1”.

On the other hand, if the count number is equal to or smaller than the lower limit value th_d, it is considered that the phases do not match, and the data I output from the data determination circuit 95 is set to “0”. Further, between the upper threshold value th_u and the lower threshold value th_d, which are the two threshold values, it is difficult to determine a difference in phase due to noise or waveform distortion, so that the value of the data I is maintained in the previous state.
The upper limit value th_u and the lower limit value th_d are determined by the system,
Setting of phase shift of modulated wave generated by transponder 2 (90
Degrees, 180 degrees).

The clock H for data determination is generated by the clock generator 96. The timing of the clock H rises immediately before the counter 94 is reset.
It is appropriate that the count value can be determined at this timing. However, the timing is not limited to such timing.

The reset timing may be determined not by one cycle of the modulated wave from the transponder 2 but by counting for a certain period of time in a plurality of cycles.
By using this method, it is possible to demodulate if at least one signal of a waveform whose phase matches or does not match can be obtained by the signal D output from the filter 8, until demodulation like an analog PLL. The transponder 2 can reduce the number of 1-bit waves and increase the bit rate, and all the demodulators 9 of the interrogator 1 Can also be configured.

In this demodulation method, since the data is determined based on the coincidence and inversion of the phase, the length of one bit of the data I may be changed. To separate the data I.

As described above, according to the first embodiment, the reference signal F is obtained from the signal D extracted by receiving the modulated wave from the transponder 2 and the square wave F (0) input from the oscillator unit 4. And the phase of the signal D is compared with the phase of the reference signal F. Therefore, it is possible to accurately and quickly synchronize with the modulated wave from the transponder 2, and
The number of input waves for judging the phase of the modulated wave from is reduced, the bit rate can be increased, and even if the modulated wave is disturbed or distorted due to noise, it has the effect of being able to demodulate normally, and the digital value is reduced. It can be determined immediately.

When the transponder 2 transmits response data, the first few bits transmit the same digital value as a header and synchronize, so that the digital value changes during synchronization. Since there is no phase change and no phase change, a reference signal synchronized with a modulated wave corresponding to at least one of the digital values constituting the response data can be immediately extracted. Then, after transmitting the header, the data can be immediately determined based on the reference signal.

When the logic of the square wave E having the same period as that of the modulated wave B from the transponder 2 matches the logic of the reference signal F, the count value of the counter 94 is counted up. , And inversion, it is possible to easily determine whether the phases match or not.

Further, since the square wave F (0) having the same cycle as the modulated wave B transmitted from the transponder 2 is shifted by the shift register 93 to obtain the reference signal F, the modulation from the transponder 2 is obtained. For a signal D with the same period as the wave,
In addition, the reference signal can be output quickly in synchronization.

Embodiment 2 FIG. 5 shows a demodulator 9 of an interrogator 1 of a contactless data transmitting / receiving apparatus according to Embodiment 2 of the present invention.
FIG. 3 is a block diagram showing the configuration of FIG. In FIG. 5, 97,
Reference numeral 98 denotes a counter. In the second embodiment, the waveform shaping circuit 91 and the counters 94 and 97 correspond to a phase comparing unit, and the data determining circuit 95, the clock generator 96 and the counter 98 correspond to a data determining unit. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Next, the operation will be described. In FIG. 5, the transponder 2 is controlled by the waveform shaping output E and the synchronization acquisition circuit 92.
The reference signal F synchronized with one of the phases of the digital value transmitted by the counter 94 is input to the counter 94 and the counter 97. The counters 94 and 97 shift the counting cycle (signals G and G ') as shown in FIG. The shift period differs depending on the system. In the example of FIG. 6, the shift period is shifted by a half wavelength of the modulated wave transmitted by the transponder 2. In each counter, the phase of the two signals is calculated in the same manner as in the first embodiment. Are compared.

Here, each count value is compared with each threshold value as in the first embodiment, and data is not immediately determined when the phase coincidence or non-coincidence is determined, but the upper limit value th_u is determined. , And the lower limit value th_d is input to the counter 98. That is, if the count value of the counter 94 is equal to or more than the upper limit value th_u, the counter 98
Is counted up, and if the count value of the counter 97 is equal to or smaller than the lower limit value th_d, the counter 98 is counted down.

This makes it possible to judge data when the phases match or mismatch several times in succession. For example, when the counter 98 is composed of a 2-bit up / down counter, if the output of the counter 98 is "11" as shown by data J and I in FIG. If the output is "1" and the output of the counter 98 is "00", the phase has been inverted three times, and the data determination output is set to "0". Thereby, the length of one bit transmitted by the transponder 2 is longer than that in the first embodiment, but it is possible to avoid making a judgment only when the phases coincide with each other.

As described above, according to the second embodiment, the result of comparison with the upper limit value th_u and the lower limit value th_d is input to the counter 98, so that the same cycle as the modulated wave B from the transponder 2 is used. Even if the phases of the square wave E and the reference signal F coincide with each other or coincide with each other, it is possible to avoid erroneously judging the coincidence or non-coincidence of the phase. Therefore, the effect that the communication quality can be improved can be obtained.

In the second embodiment, two counters 94 and 97 for counting while shifting by a half cycle are used.
The shift period and the number of counters may be changed, and a plurality of counters may be held and counted while shifting by 1 / n periods. By doing so, the number of samplings at which the phases match or mismatch can be increased, and data determination can be performed more accurately.

In the second embodiment, the filter 8
Generates a square wave F (0) having the same frequency as the frequency of the modulated wave returned by the transponder 2 in the interrogator 1 and generates a reference signal F synchronized with the output of the transponder 2. Is selected, the modulation wave from the transponder 2 is input to the shift register and shifted, and the synchronization wave is obtained by selecting the one having the same phase as F (0). And the subsequent demodulation may be performed.
Further, the waveform of the modulated wave from the transponder 2 is rounded by being filtered by the filter 8, and the DUTY ratio is likely to be not 50%.
It is also conceivable to convert to UTY 50% and perform subsequent processing.

At this time, only when the modulated wave is digitally “H” for a predetermined period, the DUTY is converted to 50% to make it more resistant to extraneous noise.
By configuring with TY50%, the phase comparison accuracy is improved.

[0075]

As described above, according to the present invention, the transponder includes transmission means for transmitting as a transmission signal a modulated wave phase-modulated based on a digital value constituting response data. Receiving means for receiving a transmission signal from a transponder, extracting a modulation wave from the transmission signal, and synchronizing to obtain a reference signal synchronized with a modulation wave corresponding to at least one digital value constituting the response data Acquisition means,
Phase comparing means for comparing the phase of the modulated wave extracted by the receiving means with the phase of the reference signal acquired by the synchronization acquiring means; and a digital value forming response data based on a comparison result of the phase comparing means. The interrogator and the transponder can be synchronized accurately and quickly because of the configuration including the data discriminating means for discriminating. Further, the number of input waves for judging the phase of the modulated wave from the transponder is reduced. Thus, the bit rate can be increased, and furthermore, even when the modulated wave is disturbed or distorted due to noise, the demodulation can be performed normally.

According to the present invention, the transmission means of the transponder generates the transmission signal by inverting the phase of the modulated wave every time the digital value constituting the response data changes. When the data is constituted by binary digital values, it is possible to easily determine whether or not the data matches the phase of the modulated wave.

According to the present invention, since the transmitting means of the transponder transmits the modulated wave whose phase is not inverted during the first predetermined period of the response data, the digital signal is transmitted during the first predetermined period. Since there is no change in value and no change in phase, there is an effect that a reference signal synchronized with a modulated wave corresponding to at least one of the digital values constituting the response data can be obtained.

According to the present invention, the synchronization acquiring means shifts the signal having the same cycle as the modulated wave from the transponder, compares the phase of the output signal of the shift register with the phase of the modulated wave, A synchronization acquisition circuit that outputs the output signal of the shift register as a reference signal to the phase comparison means when the phase of the output signal of the register matches the phase of the modulation wave. There is an effect that a reference signal synchronized with the reference signal can be acquired with high accuracy and quickly.

According to the present invention, the phase comparing means samples the reference signal and the value of the extracted modulated wave with a clock faster than the reference signal output from the synchronization acquiring means, and samples the sampled reference signal and the modulated wave. Since the counter counts up when the logics of the counters coincide with each other and are reset at predetermined intervals, the counter number is output as a comparison result between the phase of the modulated wave and the phase of the reference signal. There is an effect that it is possible to easily determine whether the phases match or not.

According to the present invention, the phase comparison means samples the reference signal and the value of the extracted modulated wave with a clock faster than the reference signal output from the synchronization acquisition means, and samples the sampled reference signal and the modulated wave. Are counted up and reset at predetermined intervals, and each period is 1 / n (n> 1).
Since a plurality of counters shifted by a period are provided and the count number of each counter is output as a result of comparison between the phase of the modulated wave and the phase of the reference signal, it is determined whether the phase of the modulated wave matches or not. Therefore, there is an effect that the data determination can be performed more accurately.

According to the present invention, the data discriminating means compares the count number output from the phase comparing means with the preset threshold value for each cycle of the reference signal output from the synchronization acquiring means. The reference signal and the modulating wave are configured to include a data determination circuit that determines whether the phase of the reference signal and the modulating wave are in phase and determines a digital value forming the response data. Has an effect that it is possible to immediately determine whether the phase is reversed.

According to the present invention, the data discriminating means compares the count number of each counter output from the phase comparing means with a predetermined threshold value, and determines that the phase of the reference signal and that of the modulated wave are the same. It is configured to include a data determination circuit that determines whether or not there is a counter, counts the result with a counter, and determines a digital value forming response data based on the count number of the counter. Even if the phase of the modulated wave coincides with or disagrees by mistake, it is possible to avoid erroneously determining whether the phase coincides or disagrees. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a contactless data transmitting / receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a demodulation unit of an interrogator in the non-contact data transmission / reception device of FIG.

FIG. 3 is a waveform chart showing an operation of the non-contact data transmission / reception device of FIGS. 1 and 2;

FIG. 4 is a waveform diagram illustrating the synchronization acquisition method of FIG.

FIG. 5 is a block diagram illustrating a configuration of a demodulation unit according to a second embodiment of the non-contact data transmission / reception device of the present invention.

FIG. 6 is a waveform chart showing an operation of the non-contact data transmission / reception device of FIG.

FIG. 7 is a schematic diagram showing a general use state of an interrogator and a transponder in a non-contact data transmission / reception device.

FIG. 8 is a block diagram illustrating a configuration of a conventional non-contact data transmission / reception device.

FIG. 9 is a waveform diagram showing an operation of a conventional non-contact data transmission / reception device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 interrogator 2 transponder 21 transmission / reception unit (transmission means) 91 waveform shaping circuit (phase comparison means) 92 synchronization acquisition circuit (synchronization acquisition means) 93 shift register (synchronization acquisition means) 94, 97 counter (phase comparison means) 95 data Judgment circuit (data judgment means) 96 Clock generator (data judgment means) 95 Data judgment circuit (data judgment means) 98 Counter (data judgment means)

Claims (8)

[Claims] An interrogator for transmitting a modulated wave modulated with interrogation data including command data, receiving and demodulating a modulated wave from the interrogator, performing processing in accordance with an instruction of the interrogation data command data, A transponder for transmitting a modulated wave modulated with response data to the interrogator, wherein the transponder comprises: a phase-modulated modulation based on a digital value constituting the response data. Transmitting means for transmitting a wave as a transmission signal, wherein the interrogator receives a transmission signal from a transponder, and extracts a modulated wave from the transmission signal; and at least one digital constituting the response data Synchronization acquisition means for acquiring a reference signal synchronized with the modulated wave corresponding to the value; and a phase of the reference signal acquired by the synchronization acquisition means for the phase of the modulated wave extracted by the reception means. A non-contact data transmission / reception device comprising: a phase comparison unit that compares a phase; and a data determination unit that determines a digital value forming response data based on a comparison result of the phase comparison unit. 2. The transmitting means of the transponder is configured to generate a modulated wave whose phase is inverted each time a digital value forming the response data changes. Non-contact data transmission and reception device. 3. The non-contact data transmission / reception according to claim 1, wherein the transmission means of the transponder transmits a modulated wave whose phase is not inverted during the first predetermined period of the response data. apparatus. 4. The synchronization acquisition means includes: a shift register for shifting a signal having the same cycle as a modulation wave from a transponder; comparing a phase of an output signal of the shift register with a phase of the modulation wave; 2. A synchronization acquisition circuit for outputting an output signal of a shift register as a reference signal to a phase comparison means when a phase of a signal coincides with a phase of a modulated wave. 4. The non-contact data transmission / reception device according to claim 1. 5. The phase comparison means samples a reference signal and a value of an extracted modulated wave with a clock faster than the reference signal output from the synchronization acquisition means, and performs a logic operation between the sampled reference signal and the modulated wave. A counter that counts when the values match, and is reset at predetermined intervals, and is configured to output the count number of the counter as a result of comparison between the phase of the modulated wave and the phase of the reference signal. The non-contact data transmission / reception device according to any one of claims 1 to 4, wherein: 6. The phase comparison means samples the reference signal and the value of the extracted modulated wave with a clock faster than the reference signal output from the synchronization acquisition means, and performs a logic operation on the sampled reference signal and the modulated wave. Are counted and reset at predetermined intervals, and each counter is shifted by 1 / n (n> 1) periods, and a plurality of counters are provided to compare the phase of the modulated wave with the phase of the reference signal. The non-contact data transmitting / receiving device according to any one of claims 1 to 4, wherein a count number of each counter is output as a result. 7. The data determination means compares the count number output from the phase comparison means with a preset threshold value for each cycle of the reference signal output from the synchronization acquisition means, and compares the reference signal with the reference signal. The non-contact data transmission / reception according to claim 5, further comprising a data determination circuit that determines whether or not the phases of the modulated waves are in phase and determines a digital value that forms the response data. apparatus. 8. The data determination means compares the count number of each counter output from the phase comparison means with a predetermined threshold value and determines whether the phase of the reference signal and the phase of the modulated wave are the same. 7. A data judging circuit which judges whether or not the result is counted by a counter and judges a digital value constituting response data based on the count number of the counter. A non-contact data transmission / reception device according to claim 1.