JP4463822B2 - Non-contact communication system - Google Patents

Description

  In the present invention, for example, an RF-ID (Radio Frequency Identification) tag that is not equipped with a driving source such as a battery and a reader / writer device (hereinafter referred to as an R / W device) are wirelessly arranged at a distance of about 10 meters. The present invention relates to a contactless communication system that performs communication.

In the conventional contactless communication system, even when the tag is not equipped with a drive source such as a battery, the R / W device uses the charging carrier as a tag so that the tag can perform communication processing. Send.
When the tag receives the charge carrier transmitted from the R / W device, the tag rectifies the charge carrier to acquire drive power, and accumulates the power.

Thereafter, the R / W device transmits a reflection carrier to the tag when receiving the modulation signal from the tag.
When the tag receives the reflection carrier transmitted from the R / W device, the tag starts communication processing by using the previously accumulated power. That is, a process of modulating the reflection carrier according to the transmission target data and transmitting the modulated signal to the reader / writer device is performed (for example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 11-41155 (paragraph numbers [0014] to [0016], FIG. 1)

  Since the conventional contactless communication system is configured as described above, when a plurality of R / W devices are installed, the plurality of R / W devices do not synchronize with each other and perform communication processing asynchronously. . For this reason, mutual interference occurs between a plurality of R / W devices (for example, when a certain R / W device receives a modulated signal from a tag, a signal transmitted from another R / W device is received). ) Occurred and communication quality deteriorated.

  The present invention has been made to solve the above-described problems, and is capable of preventing non-contact between a plurality of R / W devices even when a plurality of R / W devices are installed. It aims at obtaining a type communication system.

The non-contact communication system according to the present invention receives a plurality of reader / writer devices that transmit a reflection carrier when receiving a modulation signal, and receives a reflection carrier transmitted from the reader / writer device. A tag that modulates the reflection carrier in response to the signal and transmits the modulated signal to the reader / writer device, a control device that performs diversity processing of the modulation signals received by the plurality of reader / writer devices, and the reader / writer When the device transmits a charging carrier, the tag acquires driving power from the charging carrier, and the reader / writer device transmits a modulation signal from the tag even if it transmits a reflective carrier. If not, transmission of the reflective carrier is stopped.

  Thus, even when a plurality of reader / writer devices are installed, there is an effect that it is possible to prevent the occurrence of mutual interference between the plurality of reader / writer devices.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the non-contact-type communication system by Embodiment 1 of this invention. It is a block diagram which shows the inside of a R / W apparatus and a tag. It is explanatory drawing which shows transmission / reception of the signal between R / W apparatus and a tag. It is explanatory drawing which shows transmission / reception of the signal between the R / W apparatus and tag by Embodiment 2 of this invention. It is explanatory drawing which shows transmission / reception of the signal between the R / W apparatus and tag by Embodiment 3 of this invention. It is explanatory drawing which shows transmission / reception of the signal between the R / W apparatus and tag by Embodiment 4 of this invention. It is explanatory drawing which shows transmission / reception of the signal between the R / W apparatus and tag by Embodiment 5 of this invention. It is a block diagram which shows the non-contact-type communication system by Embodiment 5 of this invention. It is explanatory drawing which shows transmission / reception of the signal between W apparatus and R apparatus, and a tag by Embodiment 6 of this invention. It is a block diagram which shows the non-contact-type communication system by Embodiment 6 of this invention.

Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a contactless communication system according to Embodiment 1 of the present invention. In the figure, reader / writer devices R / W devices 1A, 1B, 1C, 1D are communication areas 2A, 2B, 2C. , A tag reflection carrier is transmitted when a reflected signal (modulated signal) is received from a tag in 2D.
The tags 3B, 3C, and 3D are, for example, card-shaped passive tags that are not equipped with a driving source such as a battery, and are located in the communication areas 2B, 2C, and 2D of the R / W devices 1B, 1C, and 1D. When the tags 3B, 3C, 3D receive the tag reflection carrier transmitted from the R / W devices 1B, 1C, 1D, the tag reflection carrier is modulated in accordance with the transmission target data, and the reflected signal is the modulated signal. Is transmitted to the R / W devices 1B, 1C, 1D.

  The R / W control device 4 controls communication processing of the R / W devices 1A, 1B, 1C, and 1D. For example, the R / W devices 1A, 1B, and 1C are controlled to transmit the tag reflection carrier at different timings. However, since the R / W device 1A and the R / W device 1D have a wide installation interval and the signals do not interfere with each other, the R / W devices 1A and 1D transmit the tag reflection carrier at the same timing. So that it is controlled.

FIG. 2 is a configuration diagram showing the inside of the R / W devices 1A, 1B, 1C, 1D (denoted as R / W device 1 in the figure) and the tags 3B, 3C, 3D (denoted as tag 3 in the figure). In the figure, the RF signal oscillator 11 oscillates an unmodulated signal having a frequency f, for example.
When transmitting a tag recognition signal to the tag 3, the control circuit 12 outputs a command indicating the tag recognition signal to the pulse modulator 13 and the amplifier 14, and transmits a charge carrier and a tag reflection carrier to the tag 3. In this case, a control signal instructing transmission of the charge carrier or the tag reflection carrier is output to the pulse modulator 13 and the amplifier 14.

When receiving a command from the control circuit 12, the pulse modulator 13 modulates an unmodulated signal oscillated from the RF signal oscillator 11 in response to the command, outputs the modulated signal to the amplifier 14, and charges from the control circuit 12. When receiving a control signal instructing transmission of the carrier for tag and the carrier for tag reflection, the unmodulated signal oscillated from the RF signal oscillator 11 is output to the amplifier 14 as it is.
When the amplifier 14 receives a command from the control circuit 12, the amplifier 14 amplifies the modulation signal output from the pulse modulator 13, and receives a control signal instructing transmission of a charge carrier or a tag reflection carrier from the control circuit 12. The unmodulated signal output from the modulator 13 is amplified.

The circulator 15 outputs the modulated signal or unmodulated signal amplified by the amplifier 14 to the antenna 16, and outputs the reflected signal (modulated signal) received by the antenna 16 to the demodulation circuit 17.
The antenna 16 transmits the modulated signal or non-modulated signal output from the circulator 15 to the tag 3, while receiving the reflected signal (modulated signal) transmitted from the tag 3.
When receiving the reflection signal (modulation signal) from the circulator 15, the demodulation circuit 17 demodulates the reflection signal and analyzes the data.

The antenna 21 of the tag 3 receives the modulated signal or non-modulated signal transmitted from the R / W device 1, while transmitting the reflected signal (modulated signal) output from the modulation / demodulation circuit 24 to the R / W device 1.
If the received signal of the antenna 21 is a non-modulated signal of the charging carrier, the charging circuit 22 rectifies the non-modulated signal to obtain driving power, and accumulates the driving power in the capacitor 23.

  The modulation / demodulation circuit 24 is driven by using the electric power stored in the capacitor 23 of the charging circuit 22. If the received signal of the antenna 21 is a modulation signal, the modulation / demodulation circuit 24 demodulates the tag recognition signal from the modulation signal. It is determined whether or not it represents its own identification information. If the received signal of the antenna 21 is an unmodulated signal of the tag reflection carrier, the reflection carrier is modulated according to the data addressed to the R / W device 1 and the modulated signal is output to the antenna 21.

Next, the operation will be described.
The tag 3 is not equipped with a power source such as a battery, and cannot be activated unless power is supplied from the outside.
Therefore, when the R / W device 1 needs to receive data from the tag 3, power is supplied to the tag 3 in a non-contact state in advance.

First, the control circuit 12 of the R / W device 1 outputs a control signal instructing transmission of a charge carrier to the pulse modulator 13 and the amplifier 14.
When the pulse modulator 13 of the R / W device 1 receives a control signal instructing transmission of the charge carrier from the control circuit 12, the pulse modulator 13 does not modulate the unmodulated signal oscillated from the RF signal oscillator 11, but modulates the unmodulated signal. The signal is output to the amplifier 14 as it is.

When the amplifier 14 of the R / W device 1 receives a control signal instructing transmission of a charge carrier from the control circuit 12, the amplifier 14 amplifies the unmodulated signal output from the amplifier 14 and outputs the amplified signal to the circulator 15.
Note that the amplifier 14 normally applies the non-modulated signal of the charging carrier so that the amplitude value of the signal is larger than that when the modulated signal such as the tag recognition signal or the non-modulated signal of the tag reflection carrier is amplified. Amplify (see FIG. 3).

When the circulator 15 of the R / W device 1 receives the unmodulated signal of the charge carrier from the amplifier 14, it outputs the unmodulated signal to the antenna 16.
When receiving the amplified unmodulated signal from the circulator 15, the antenna 16 of the R / W device 1 transmits the unmodulated signal to the tag 3 by radiating the unmodulated signal into the air.

The antenna 21 of the tag 3 receives an unmodulated signal transmitted from the R / W device 1.
In the example of FIG. 1, the tags 3B, 3C, 3D receive the unmodulated signal of the charging carrier transmitted from the R / W devices 1B, 1C, 1D. Since the tag 3 does not exist in the communication area 2A of the R / W device 1A, there is no tag 3 that receives the unmodulated signal of the charging carrier transmitted from the R / W device 1A.

The charging circuit 22 of the tag 3 determines whether or not the reception signal of the antenna 21 is an unmodulated signal of the charging carrier.
For example, the envelope of the received signal of the antenna 21 is detected, and if the envelope value is equal to or greater than a set value, the received signal is recognized as an unmodulated signal of the charging carrier.
If the received signal of the antenna 21 is an unmodulated signal of the charging carrier, the charging circuit 22 of the tag 3 rectifies the unmodulated signal to acquire driving power, and accumulates the driving power in the capacitor 23. .

When the R / W device 1 needs to receive a modulated signal on which data is superimposed from the tag 3 after supplying power to the tag 3 as described above, the R / W device 1 modulates the tag 3 to be communicated. In order to instruct the transmission of the signal, the tag recognition signal of the tag 3 is transmitted.
Specifically, it is as follows.

First, the control circuit 12 of the R / W device 1 outputs a command indicating a tag recognition signal to the pulse modulator 13 and the amplifier 14.
When receiving a command from the control circuit 12, the pulse modulator 13 of the R / W device 1 modulates an unmodulated signal oscillated from the RF signal oscillator 11 in response to the command, and generates a tag recognition signal that is the modulated signal. Output to the amplifier 14.

When receiving the command from the control circuit 12, the amplifier 14 of the R / W device 1 amplifies the tag recognition signal that is a modulation signal output from the pulse modulator 13.
When the circulator 15 of the R / W device 1 receives a tag recognition signal that is a modulation signal from the amplifier 14, the circulator 15 outputs the tag recognition signal to the antenna 16.
When receiving the amplified tag recognition signal from the circulator 15, the antenna 16 of the R / W device 1 transmits the tag recognition signal to the tag 3 by radiating the tag recognition signal into the air.

The antenna 21 of the tag 3 receives a tag recognition signal that is a modulated signal transmitted from the R / W device 1.
In the example of FIG. 1, the tags 3B, 3C, 3D receive tag recognition signals transmitted from the R / W devices 1B, 1C, 1D. Since the tag 3 does not exist in the communication area 2A of the R / W device 1A, there is no tag 3 that receives the tag recognition signal transmitted from the R / W device 1A.

The modulation / demodulation circuit 24 of the tag 3 is driven using the electric power stored in the capacitor 23 of the charging circuit 22 and determines whether or not the reception signal of the antenna 21 is a modulation signal.
For example, the envelope of the received signal of the antenna 21 is detected, and it is determined whether or not the received signal is a modulated signal based on fluctuations in the envelope.
When the modulation / demodulation circuit 24 of the tag 3 recognizes that the reception signal of the antenna 21 is a modulation signal, it demodulates the tag recognition signal that is the modulation signal.
When the tag recognition signal represents its own identification information, the modulation / demodulation circuit 24 recognizes that it is necessary to transmit data when the tag reflection carrier is transmitted from the R / W device 1.

When transmitting the tag recognition signal to the tag 3 as described above, the R / W device 1 transmits the tag reflection carrier to the tag 3.
Specifically, it is as follows.

First, the control circuit 12 of the R / W device 1 outputs a control signal instructing transmission of the tag reflection carrier to the pulse modulator 13 and the amplifier 14.
When the pulse modulator 13 of the R / W device 1 receives a control signal instructing transmission of the tag reflection carrier from the control circuit 12, the pulse modulator 13 does not modulate the unmodulated signal oscillated from the RF signal oscillator 11, The modulated signal is output to the amplifier 14 as it is.

When receiving the control signal instructing transmission of the tag reflection carrier from the control circuit 12, the amplifier 14 of the R / W device 1 amplifies the unmodulated signal output from the amplifier 14 and outputs the amplified signal to the circulator 15.
When the circulator 15 of the R / W device 1 receives the unmodulated signal of the tag reflection carrier from the amplifier 14, it outputs the unmodulated signal to the antenna 16.
When receiving the amplified unmodulated signal from the circulator 15, the antenna 16 of the R / W device 1 transmits the unmodulated signal to the tag 3 by radiating the unmodulated signal into the air.

The antenna 21 of the tag 3 receives an unmodulated signal transmitted from the R / W device 1.
In the example of FIG. 1, the tags 3B, 3C, 3D receive the unmodulated signal of the tag reflection carrier transmitted from the R / W devices 1B, 1C, 1D. Since the tag 3 does not exist in the communication area 2A of the R / W device 1A, there is no tag 3 that receives the non-modulated signal of the tag reflection carrier transmitted from the R / W device 1A.

The modulation / demodulation circuit 24 of the tag 3 determines whether or not the received signal of the antenna 21 is an unmodulated signal of the tag reflection carrier.
For example, the envelope of the received signal of the antenna 21 is detected, and if the envelope value is within a set value range, the received signal is recognized as an unmodulated signal of the tag reflection carrier.
When the modulation / demodulation circuit 24 recognizes that the received signal of the antenna 21 is an unmodulated signal of the tag reflection carrier, the modulation / demodulation circuit 24 modulates the reflection carrier in accordance with the data addressed to the R / W device 1, and reflects the modulation signal. The signal is output to the antenna 21.
When receiving the reflected signal from the modulation / demodulation circuit 24, the antenna 21 of the tag 3 transmits the reflected signal to the R / W device 1 by radiating the reflected signal into the air.

The antenna 16 of the R / W device 1 receives the reflected signal transmitted from the tag 3.
In the example of FIG. 1, the R / W devices 1B, 1C, and 1D receive the reflected signals transmitted from the tags 3B, 3C, and 3D. Since the tag 3 does not exist in the communication area 2A of the R / W device 1A, the R / W device 1A does not receive a reflected signal from the tag 3.

The circulator 15 of the R / W device 1 outputs the reflected signal received by the antenna 16 to the demodulation circuit 17.
When receiving the reflection signal from the circulator 15, the demodulation circuit 17 of the R / W device 1 demodulates the reflection signal and analyzes the data addressed to itself.

Thus, the R / W devices 1B, 1C, and 1D can analyze the data addressed to the tags 3B, 3C, and 3D. For example, the R / W device 1B receives the reflected signal from the tag 3B. When the R / W device 1A or the R / W device 1C transmits a modulated signal or a non-modulated signal, the R / W device 1B transmits the modulated signal transmitted from the R / W device 1A or the R / W device 1C, or nothing. A modulated signal may be received.
This modulated signal or non-modulated signal becomes an interference wave when the R / W device 1B receives the reflected signal from the tag 3B, and the reception characteristics of the reflected signal deteriorate.

Therefore, in the first embodiment, the R / W control device 4 performs control so that the R / W devices 1A, 1B, and 1C do not transmit a tag recognition signal or a tag reflection carrier at the same timing.
That is, by controlling the R / W devices 1A, 1B, and 1C to transmit the tag recognition signal and the tag reflection carrier at different timings, for example, the R / W device 1B receives the reflected signal from the tag 3B. In this case, the R / W device 1A and the R / W device 1C are prevented from transmitting a tag recognition signal or a tag reflection carrier so that an interference wave of the reflected signal is not received (see FIG. 3).
However, since the R / W device 1A and the R / W device 1D have a wide installation interval and the signals do not interfere with each other, in the example of FIG. 3, the R / W devices 1A and 1D are tagged at the same timing. Control is performed to transmit a recognition signal and a tag reflection carrier.

  Here, the R / W control device 4 controls the communication of the R / W devices 1A, 1B, and 1C. However, the R / W devices 1A, 1B, and 1C monitor other communication statuses with each other. The R / W devices 1A, 1B, and 1C may transmit a tag recognition signal and a tag reflection carrier at different timings.

  As apparent from the above, according to the first embodiment, the R / W devices 1A, 1B, and 1C are configured to transmit the tag recognition signal and the reflection carrier at different timings. Even if the / W devices 1A, 1B, and 1C are installed, there is an effect that it is possible to prevent the occurrence of mutual interference among the plurality of R / W devices.

  In the first embodiment, the R / W device 1 transmits the tag recognition signal to the tag 3 before transmitting the tag reflection carrier to the tag 3. If the R / W device 1 is set to transmit the reflected signal unconditionally if the received carrier is received, the tag recognition signal is sent to the tag 3 before the R / W device 1 transmits the tag reflected carrier to the tag 3. There is no need to send to.

Embodiment 2. FIG.
In the first embodiment, the R / W device 1 transmits a single pulse as a charge carrier when supplying power to the tag 3. However, as shown in FIG. May be divided into a plurality of pulses (the duty ratio of the plurality of pulses is lower than the duty ratio of the single pulse), and the plurality of pulses may be transmitted as a charge carrier.
In this case, there is an effect that the power storage effect of power in the tag 3 can be enhanced.

Embodiment 3 FIG.
In the first embodiment, when the R / W devices 1A, 1B, 1C, and 1D supply power to the tag 3, the charging carrier is transmitted at the same timing. However, as shown in FIG. The R / W devices 1A, 1B, and 1C may transmit charge carriers at different timings.

Thereby, there is an effect that the influence of the interference of the charging carrier transmitted from the R / W devices 1A, 1B, 1C can be reduced.
When a tag 3 receives charge carriers having the same frequency transmitted from a plurality of R / W devices 1A, 1B, and 1C, a plurality of charge carriers are added. Depending on the phase of the carrier used, reverse phase addition may occur, and the stored power may be significantly reduced. However, if the R / W devices 1A, 1B, and 1C transmit charge carriers at different timings, no reverse-phase addition occurs, so that a reduction in stored power can be prevented.

  However, in the example of FIG. 5, the R / W device 1A and the R / W device 1D have a wide installation interval, and there is no tag 3 that receives both the charge carriers transmitted from the R / W devices 1A and 1D. The R / W devices 1A and 1D transmit the tag reflection carrier at the same timing.

  Note that the timing of charging carriers transmitted from the R / W devices 1A, 1B, 1C, and 1D may be controlled by the R / W control device 4, or the R / W devices 1A, 1B, and 1C may be different from each other. By monitoring the communication status, the R / W devices 1A, 1B, 1C may transmit charging carriers at different timings.

Embodiment 4 FIG.
In the first embodiment, the case where the charge carrier, the tag recognition signal, and the tag reflection carrier are repeatedly transmitted even when the tag 3 does not exist in the communication area 2A of the R / W device 1A has been described. As shown in FIG. 4, even if the R / W device 1A transmits the reflection carrier, if the reflection signal that is the modulation signal is not transmitted from the tag 3, the charging carrier, the tag recognition signal, and the tag reflection carrier are thereafter processed. May be canceled.

As a result, useless radio waves are not transmitted from the R / W device 1A, so that it is possible to reduce signal interference with respect to the other R / W devices 1B and 1C.
Even if the R / W device 1A stops transmitting the charge carrier, the tag recognition signal, and the tag reflection carrier, for example, under the instruction of the R / W control device 4, the R / W device 1A Needless to say, transmission of the tag recognition signal and the tag reflection carrier can be resumed.

Embodiment 5 FIG.
In the first embodiment, the R / W devices 1A, 1B, and 1C transmit reflection carriers at different timings to prevent mutual interference between a plurality of R / W devices. However, as shown in FIG. 7, when the R / W devices 1A, 1B, and 1C transmit the reflection carriers at the same timing, the reception characteristics of the R / W devices 1A, 1B, and 1C deteriorate as described above. To do.
Therefore, in the fifth embodiment, the reception characteristics of the R / W device 1 are enhanced as follows.

For example, as shown in FIG. 8, the modulation signal (reflected signal) transmitted from the tag 3E existing in the communication area 2E of the R / W device 1E is received by the R / W device 1E, but the R / W device 1E. If the R / W device 1F adjacent to the R / W device 1F can also receive the reflected signal, the R / W control device 4 receives the reflected signal received by the R / W device 1E, and the reflected signal received by the R / W device 1F. Are collected, and both reflected signals are selected and combined with diversity processing.
As is well known, the selection / combination diversity processing can improve the reception characteristics of the received signal, and therefore has the effect of improving the reception characteristics of the reflected signal transmitted from the tag 3E.

  Here, the R / W control device 4 performs the selection / combination diversity processing of both reflected signals. For example, the R / W device 1E collects the reflected signals received by the R / W device 1F. Then, the selection / combination diversity processing of the reflected signal received by itself and the reflected signal received by the R / W device 1F may be performed.

In the fifth embodiment, the R / W devices 1A, 1B, and 1C transmit the reflection carrier at the same timing. However, as in the first embodiment, the R / W devices 1A, 1A, Even when 1B and 1C transmit reflection carriers at different timings, selection / combination diversity processing of a plurality of reflection signals may be performed.
In this case, the R / W devices 1A, 1B, and 1C can improve reception characteristics by a synergistic effect of transmitting the reflection carrier at different timings and performing the selection / combination diversity processing. Play.

Embodiment 6 FIG.
In the above first to fifth embodiments, the R / W device 1 has been shown to have a radio wave transmission function and a reception function. However, as shown in FIGS. 9 and 10, as shown in FIGS. The R / W device 1 is separated into a W device that is a writer device that transmits a tag reflection carrier (only for transmission) and an R device that is a reader device that receives a reflected signal transmitted from the tag 3 (only for reception). The W device and the R device may be installed separately.
Thus, by separating the R / W device 1 into the W device and the R device, there is an effect that it is possible to avoid the problem of isolation between transmission and reception of the R / W device 1 itself.

  As described above, the contactless communication system according to the present invention prevents communication interference between a plurality of R / W devices and improves communication quality even when a plurality of R / W devices are installed. Suitable for things you need.

Claims (2)

When receiving a plurality of reader / writer devices that transmit a reflection carrier when receiving a modulation signal and the reflection carrier transmitted from the reader / writer device, the reflection carrier is modulated according to the data to be transmitted, A tag that transmits the modulation signal to the reader / writer device, a control device that performs diversity processing of the modulation signal received by the plurality of reader / writer devices ,
When the reader / writer device transmits a charge carrier, the tag acquires drive power from the charge carrier,
The reader / writer device stops the transmission of the reflection carrier when the modulation signal is not transmitted from the tag even if the reflection carrier is transmitted. When receiving a plurality of reader / writer devices that transmit a reflection carrier when receiving a modulation signal and the reflection carrier transmitted from the reader / writer device, the reflection carrier is modulated according to the data to be transmitted, In a contactless communication system including a tag that transmits the modulation signal to the reader / writer device,
The reader / writer device performs diversity processing between the modulation signal received by itself and the modulation signal received by another reader / writer device ,
When the reader / writer device transmits a charge carrier, the tag acquires drive power from the charge carrier,
The reader / writer device stops the transmission of the reflection carrier when the modulation signal is not transmitted from the tag even if the reflection carrier is transmitted.

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