JP2003030611A - Wireless communication module and wireless communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication module and a radio communication method increasing a communicable distance and enabling communication with the reader-writer of a conventional system. SOLUTION: The radio communication module performing the communication without contacting by electromagnetic induction with an alternating magnetic field as a communication medium with the reader-writer generating the alternating magnetic field is provided with a battery 3, an antenna coil 31, a carrier wave signal generation means 14 utilizing power supplied from the battery 32 and generating carrier wave signals synchronized with an alternating current induced by the alternating magnetic field through the antenna coil 31 on the basis of the alternating current, and a modulation means 22 utilizing the power supplied from the battery 32, modulating the carrier wave signals generated by the carrier wave signal generation means 14 by transmission data and supplying modulated signals to the antenna coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication module and a wireless communication method for contactlessly communicating with a reading / writing device which generates an AC magnetic field using an AC magnetic field as a communication medium by electromagnetic induction. Used.

[0002]

2. Description of the Related Art Conventionally, a non-contact IC device does not have a built-in power source and receives power from a wireless communication device reading / writing device (hereinafter referred to as a reader / writer) by electromagnetic induction. Conventional non-contact IC using AC magnetic field
Since the power cord does not have a built-in power supply, maintenance can be eliminated. However, I have no contact with the reader / writer.
The communicable distance to the C-mode is limited by the power supply. That is, since the magnitude of the electric power induced in the antenna coil of the non-contact IC mode by electromagnetic induction must be equal to or larger than the predetermined electric power required for the operation of the integrated circuit in the card, the non-contact IC mode is It cannot be separated greatly from the reader / writer.

Further, between the reader / writer and the non-contact IC mode, data communication is also performed using electromagnetic induction. For this reason, when the reader / writer and the non-contact IC mode are largely separated from each other, the magnetic coupling between the antenna coils is weakened, the level of the received signal is reduced, and communication becomes impossible. Therefore, communication cannot be performed in a state where the non-contact IC mode is largely separated from the reader / writer.

In the conventional device, the signal waveform of each part is as shown in FIG. In FIG. 10, R / W represents a reader / writer, and a card represents a non-contact IC device. As described above, in the system using the non-contact IC mode using electromagnetic induction, the reader / writer constantly transmits the AC magnetic field which is a carrier (carrier wave) while communicating with the card.

An antenna coil is built in the non-contact IC mode. The non-contact IC mode obtains the electric power necessary for the operation of the electric circuit in the card from the current induced in the antenna coil by the alternating magnetic field (carrier). Non-contact I
The C mode uses the AC magnetic field to transmit information with the reader / writer while being supplied with the electric power required for operation by the AC magnetic field.

When the reader / writer sends information,
The amplitude of the carrier to be transmitted is directly modulated. Therefore,
The modulated carrier is received by a non-contact IC field antenna coil. On the other hand, when the non-contact IC mode transmits information to the reader / writer, it operates as follows.

The reader / writer continues to send the unmodulated carrier. The transmitted non-modulated carrier is a non-contact IC.
It is received as an alternating magnetic field by the antenna coil of the field.
Then, an induced current flows in the antenna coil of the non-contact IC mode in the direction of canceling the magnetic field penetrating the antenna coil. A magnetic field is generated by this induced current, and the AC magnetic field sent by the reader / writer is canceled, so that the amount corresponding to the induced current
The strength of the alternating magnetic field decreases.

Such a change in the strength of the alternating magnetic field can be detected also on the reader / writer side. Further, since the change in the strength of the alternating magnetic field corresponds to the magnitude of the induced current flowing in the antenna coil of the non-contact IC mode, the strength of the alternating magnetic field can be changed by changing the magnitude of the induced current. Therefore, the magnitude of the induced current is switched in association with the data transmitted by the non-contact IC mode. As a result, the reader / writer can read the transmission data of the non-contact IC mode from the change in the strength of the AC magnetic field.

In practice, resistors, capacitors, switches, etc. are mounted on the non-contact IC mode, and the path of the induced current is switched by the switch to switch the magnitude of the induced current. As a result, data can be transmitted by mounting a signal on the carrier sent by the reader / writer on the non-contact IC mode side.

In reality, a signal waveform as shown in FIG. 9 is specified as an international standard for communication between the reader / writer and the non-contact IC mode. That is, ASK
Two types of methods are defined, a type A having a modulation degree of (Amplitude Shift Keying) of 100% and a type B having a modulation degree of ASK of 10%.

[0011]

As described above, magnetic coupling using an antenna coil is adopted as the transmission means when communicating between the reader / writer and the non-contact IC mode. Therefore, when the distance between the reader / writer and the non-contact IC mode increases, the magnetic coupling between the antenna coils decreases, the power received by the non-contact IC mode decreases, and the non-contact IC mode decreases. Of the signal transmitted from S
/ N ratio decreases. Therefore, the reader / writer does not contact I
Communication distance with C-mode is limited.

In order to increase the communication distance between the reader / writer and the non-contact IC mode, it is necessary to increase the magnetic coupling between the antenna coils, and there is a method of increasing the antenna diameter on the reader / writer side. A method of increasing the current flowing through the antenna coil on the reader / writer side can be considered. However, increasing the antenna diameter has the following problems.

(1) Increasing the size of the device and card is unavoidable. (2) It becomes easier to pick up noise. (3) There is a possibility that the existing non-contact IC field cannot be used because the magnetic flux density decreases. When increasing the current flowing through the antenna coil,
Since the electric field strength that can be output is limited by the provisions of the Radio Law, a large current cannot flow.

An object of the present invention is to provide a wireless communication module and a wireless communication method capable of increasing a communicable distance and communicating with a reader / writer of a conventional system.

[0015]

According to a first aspect of the present invention, there is provided a wireless communication module for performing contactless communication by electromagnetic induction with a reading / writing device which generates an alternating magnetic field using the alternating magnetic field as a communication medium. Battery, antenna coil,
Carrier power signal generating means for generating a carrier wave signal synchronized with the alternating current based on the alternating current induced by the alternating magnetic field penetrating the antenna coil by using the power supplied from the battery, and the power supplied from the battery. Power is used to modulate the carrier wave signal generated by the carrier wave signal generating means with transmission data, and the modulating means supplies the modulated signal to the antenna coil.

The wireless communication module of claim 1 can be mounted on a card and used as a non-contact IC card. In addition, this wireless communication module is equipped with a battery, and the signal modulated using the electric power is transmitted from the antenna coil. The carrier signal used for signal transmission of the wireless communication module is controlled so as to be synchronized with the carrier signal transmitted from the reading / writing device and received by the antenna coil of the wireless communication module. Therefore, the signal received by the antenna coil of the wireless communication module and the signal output from the modulation means of the wireless communication module overlap and are amplified on the antenna coil.

Since the amplified signal affects the magnitude of the magnetic field detected by the read / write device, the read / write device has a larger signal than the conventional non-contact IC mode because of the amplified amount. Can be detected. Therefore, the communicable distance between the read / write device and the non-contact IC device can be increased. Further, even if the distance becomes large and the electric power received by the antenna coil of the non-contact IC mode becomes very small, the electric power is supplied from the battery, so that the electric circuit on the non-contact IC mode is normal. It is possible to maintain various operating states.

Further, since a larger amount of electric power than the electric power received by the antenna coil of the wireless communication module can be obtained from the battery, a large amount of electric power can be supplied from the modulating means to the antenna coil. For this reason, when supplying a signal having a phase opposite to the received signal from the modulating means to the antenna coil, a current is caused to flow in a direction opposite to the induced current flowing in the antenna coil due to the alternating magnetic field detected by the antenna coil, It is also possible to amplify the magnetic field sent from the reading / writing device on the non-contact IC field side.

According to a second aspect of the present invention, there is provided a wireless communication module for performing contactless communication by electromagnetic induction with a reading / writing device which generates an AC magnetic field, using the AC magnetic field as a communication medium, which can be connected to an external power source. A power supply unit, an antenna coil, and electric power supplied from the power supply unit are used to generate a carrier signal synchronized with the alternating current based on an alternating current induced by an alternating magnetic field penetrating the antenna coil. Carrier wave signal generation means, and modulation means for utilizing the power supplied from the power supply means to modulate the carrier wave signal generated by the carrier wave signal generation means with transmission data and supplying the modulated signal to the antenna coil. Is provided.

The wireless communication module according to claim 2 can be mounted on a card and used as a non-contact IC device as in the case of claim 1. Further, this wireless communication module takes in electric power from an external power supply through the electric power supply means and transmits a signal modulated using the electric power from the antenna coil. The carrier signal used for signal transmission of the wireless communication module is controlled so as to be synchronized with the carrier signal transmitted from the reading / writing device and received by the antenna coil of the wireless communication module. Therefore, the signal received by the antenna coil of the wireless communication module and the signal output from the modulation means of the wireless communication module overlap and are amplified on the antenna coil.

Since the amplified signal influences the magnitude of the magnetic field detected by the read / write device, the read / write device produces a larger signal than the conventional non-contact IC mode by the amount of the amplified signal. Can be detected. Therefore, the communicable distance between the read / write device and the non-contact IC device can be increased.

Further, even when the distance is increased and the power received by the antenna coil of the non-contact IC mode becomes very small, the power is supplied from the external power source, so that the power on the non-contact IC mode is increased. The electric circuit can maintain a normal operating state. Further, since it is possible to obtain electric power larger than the electric power received by the antenna coil of the wireless communication module from the battery, large electric power can be supplied to the antenna coil from the modulation means. For this reason, when supplying a signal having a phase opposite to the received signal from the modulating means to the antenna coil, a current is caused to flow in a direction opposite to the induced current flowing in the antenna coil due to the alternating magnetic field detected by the antenna coil, It is also possible to amplify the magnetic field sent from the reading / writing device on the non-contact IC field side.

According to a third aspect of the present invention, in the wireless communication module according to the first or second aspect, the magnetic field strength detecting means for detecting the magnetic field strength received by the antenna coil and the magnetic field strength detected by the magnetic field strength detecting means are used. Further, a carrier wave control means for automatically changing the magnitude or amplification degree of the carrier wave signal generated by the carrier wave signal generating means is further provided.

In the third aspect, the magnetic field strength detecting means detects the magnetic field strength received by the antenna coil. Also,
The carrier wave control means automatically changes the magnitude or amplification degree of the carrier wave signal generated by the carrier wave signal generation means according to the magnetic field strength detected by the magnetic field strength detection means. Therefore, when the magnetic field strength received by the antenna coil is very small, for example, when the distance between the read / write device and the non-contact IC field is long, a larger carrier signal and modulation signal are generated. As a result, the signal strength received by the read / write device can be increased and the reception quality can be improved.

Further, when the magnetic field strength received by the antenna coil is very large, for example, when the distance between the reading / writing device and the non-contact IC field is short, the levels of the carrier signal and the modulation signal are changed. By suppressing
It is possible to prevent the signal strength received by the reading / writing device from becoming excessive and improve the reception quality.

According to a fourth aspect of the present invention, in the wireless communication module according to the first or second aspect, the carrier signal generating means generates a carrier signal having the same phase as the alternating current induced in the antenna coil. In claim 4,
Since the alternating current induced in the antenna coil and the carrier wave signal generated by the carrier wave signal generating means have the same phase, both signals are overlapped and added on the antenna coil. As a result, the signal transmitted by the wireless communication module is amplified.

According to a fifth aspect of the present invention, in the wireless communication module according to the first or second aspect, the carrier signal generating means generates a carrier signal having a phase opposite to an alternating current induced in the antenna coil and having a power larger than the alternating current. It is characterized by generating. According to the present invention, since the alternating current induced in the antenna coil and the carrier signal generated by the carrier signal generating means have opposite phases, both signals are overlapped and subtracted on the antenna coil. When the carrier wave signal and the modulation signal to be transmitted are larger than the reception signal, the current in the direction of canceling the magnetic field penetrating the antenna coil does not flow, but the current flows in the direction of amplifying the magnetic field penetrating the antenna coil.

According to a sixth aspect of the present invention, in the wireless communication module according to the first or second aspect, there is provided a power receiving circuit for generating direct current power from alternating current induced in the antenna coil,
Load switch means for switching the load path of the alternating current induced in the antenna coil according to the transmission data is further provided. In the sixth aspect, the power receiving circuit generates DC power from the AC current induced in the antenna coil. Further, the load switch means switches the load path of the alternating current induced in the antenna coil according to the transmission data. Therefore, the same operation as the conventional non-contact IC mode can be performed. Therefore, even if the battery is exhausted or the external power supply cannot be connected,
Communication is possible between the wireless communication module and the read / write device.

A seventh aspect of the present invention is that the wireless communication module according to any one of the first, second, third, fourth, fifth and sixth aspects is mounted on a card-shaped case. And In claim 7, the wireless communication module can be used as a non-contact IC module.

The wireless communication method according to claim 8 is a wireless communication used for controlling a wireless communication module that performs contactless communication by electromagnetic induction with a reading / writing device that generates an alternating magnetic field using the alternating magnetic field as a communication medium. A method, based on an alternating current induced by an alternating magnetic field penetrating an antenna coil mounted on a wireless communication module, generating a carrier signal synchronized with the alternating current, modulating the carrier signal with transmission data, A modulated signal is supplied to the antenna coil to transmit the signal.

By using the wireless communication method according to the eighth aspect, the same operation of the wireless communication module as the first and second aspects can be realized.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) One embodiment of a wireless communication module and a wireless communication method of the present invention will be described with reference to FIGS. 1 to 4 and 8. This form is defined in claim 1, claim 4, claim 7, and claim 8.
Corresponding to.

FIG. 1 is a block diagram showing the configuration of the wireless communication module of this embodiment. FIG. 2 is a perspective view showing a configuration example of the system. FIG. 3 is a flowchart showing the operation of the wireless communication module of this embodiment. FIG. 4 is a time chart showing the signal waveform of this embodiment. FIG. 8 is a schematic diagram showing the current of each antenna coil.

In this embodiment, the battery, the antenna coil, the carrier signal generating means and the modulating means of claim 1 correspond to the internal power supply 32, the antenna coil 31, the clock generating circuit 14 and the modulating circuit 22, respectively. In this form, FIG.
It is assumed to use the system shown in. That is, the non-contact IC card 51 communicates with the reader / writer 52 in a non-contact manner. A higher-level device 53 (for example, a personal computer) is connected to the reader / writer 52 to control it.

Non-contact IC card 51 and reader / writer 52
Communication is performed with and using electromagnetic induction. Therefore, the reader / writer 52 is provided with an antenna coil 61.
A wireless communication module including the antenna coil 31 is incorporated in the non-contact IC card 51. The configuration of this wireless communication module is shown in FIG. As shown in FIG. 1, this wireless communication module includes a receiver 10, a transmitter 20, an antenna coil 31, an internal power supply 32, and a control circuit 33.

In addition, the receiving section 10 includes a receiving amplifier circuit 11,
Demodulation circuit 12, decoding circuit 13 and clock generation circuit 1
4 is provided, and the transmission unit 20 is provided with an encoding circuit 21, a modulation circuit 22, and a transmission amplification circuit 23. In the case of a general non-contact IC card, the electric power received by electromagnetic induction is used as the power supply for the electric circuit on the card. However, the wireless communication module of FIG.
Since it is provided with, the electric power supplied from the internal power source 32 can be used as a power source. A battery is used as the internal power supply 32 in this example.

The power supply from the internal power supply 32 is received by the receiving unit 1.
0, the transmitter 20, and the control circuit 33. The reception amplification circuit 11 amplifies the signal received by the antenna coil 31. The demodulation circuit 12 is the reception amplification circuit 1
The received signal amplified by 1 is demodulated. The decoding circuit 13 decodes the received signal appearing in the demodulation output of the demodulation circuit 12,
The digital signal transmitted from the reader / writer 52 is reproduced.

The clock generation circuit 14 also generates a clock signal based on the reception signal output from the reception amplification circuit 11. The clock signal is a binary signal that periodically changes at a constant cycle, and has the same frequency and the same phase as the alternating current (received signal) induced in the antenna coil 31 by the magnetic field applied from the outside. Also,
In this example, the received signal and the clock signal are in phase.

The control circuit 33 is composed of a logic circuit such as a microprocessor, and carries out predetermined digital processing. That is, the content of the reception signal input from the receiving unit 10 is analyzed, and the transmission data of the response signal according to the content is generated. This transmission data is transmitted by the transmission unit 20.
Is input to the encoding circuit 21. The encoding circuit 21 generates a signal obtained by encoding the transmission data input from the control circuit 33. The encoded transmission data signal is modulated by the modulation circuit 22. The modulation circuit 22 receives the clock signal generated by the clock generation circuit 14 as a carrier wave.
Is applied as.

That is, the modulation circuit 22 amplitude-modulates the clock signal with the signal of the transmission data output from the encoding circuit 21. The modulation signal output from the modulation circuit 22 is amplified by the transmission amplification circuit 23 and supplied to the antenna coil 31. Since the clock signal generated by the clock generation circuit 14 has the same frequency and the same phase as the alternating current reception signal induced in the antenna coil 31 by the external magnetic field, the modulated transmission signal supplied from the transmission unit 20 to the antenna coil 31 is transmitted. The signal has the same frequency and the same phase as the received signal.

Therefore, as shown in FIG. 8, the current component of the reception signal and the current component of the transmission signal flowing through the antenna coil 31 always flow in the same direction. That is, the current component of the reception signal and the current component of the transmission signal are added and flow into the antenna coil 31.

The current component of the received signal is an induced current induced in the antenna coil 31 by the external magnetic field (transmitted signal of the reader / writer 52), and is a current in the direction of canceling the external magnetic field. Therefore, the current component of the transmission signal output from the transmission unit 20 also works in the direction of canceling the external magnetic field. In any case, since the magnitude of the current flowing through the antenna coil 31 is the result of adding the current component of the received signal and the current component of the transmitted signal, the level is higher than that when only the current component of the received signal is used. Grows larger. Therefore, non-contact I
A larger signal can be transmitted from the C card 51 to the reader / writer 52, and communication can be performed even if the distance between the non-contact IC card 51 and the reader / writer 52 is larger than in the conventional case.

In practice, the transmitting unit 20 controls the current flowing through the antenna coil 31 so that the reception level of the reader / writer 52 greatly changes depending on whether the non-contact IC card 51 is modulated or not. . There are the following two types of control methods (1) and (2). (1) When the non-contact IC card 51 modulates for transmission (corresponding to the ON state of the load switch), the transmission unit 20
To the antenna coil 31 to stop the current output from the transmitter 20 when no modulation is performed. As a result, the reception level of the reader / writer 52 becomes extremely small when the non-contact IC card 51 transmits a modulation signal, and becomes relatively large when there is no modulation, so the difference in amplitude between the modulated wave and the unmodulated wave is large, It enables long-distance communication.

(2) When the non-contact IC card 51 transmits a non-modulated signal, a current is sent from the transmitter 20 to the antenna coil 31 to modulate (corresponding to the ON state of the load switch) the transmitter 20. Stop the current output by. As a result, the reception level of the reader / writer 52 becomes extremely small when the non-contact IC card 51 transmits an unmodulated signal, and becomes relatively large during modulation, so that the difference in amplitude between the modulated wave and the unmodulated wave is large, It enables long-distance communication.

Non-contact IC card 51 and reader / writer 5
The signal waveform of each part of No. 2 will be described with reference to FIG. The card and R / W shown in FIG. 4 correspond to the non-contact IC card 51 and the reader / writer 52, respectively. The reader / writer 52 always continues to transmit an AC magnetic field which is a carrier while communicating with the non-contact IC card 51. When the reader / writer 52 is in the receiving state, an unmodulated carrier (W12) is transmitted from the reader / writer 52, and when the reader / writer 52 transmits, the carrier is amplitude-modulated according to the transmission data of the reader / writer 52 (W11). .

The carrier and the modulated signal are attenuated according to the distance and the like, and the antenna coil 3 of the non-contact IC card 51.
1 is received (W21, W22). When the non-contact IC card 51 transmits, the transmission operation is performed based on the signal (W22) received by the antenna coil 31. That is, a clock signal synchronized with the received signal (W22) is generated by the clock generation circuit 14, and this clock signal is used by the modulation circuit 22 as a carrier for transmission.

The transmission data output by the control circuit 33 is encoded by the encoding circuit 21 and input to the modulation circuit 22. Therefore, a modulation signal obtained by modulating the transmission data with the clock signal as a carrier is obtained at the output of the modulation circuit 22. This modulated signal is amplified by the transmission amplifier circuit 23 and supplied to the antenna coil 31 as a transmission output (W3).
Since the electric circuit on the non-contact IC card 51 uses the electric power of the internal power supply 32, the amplitude of the transmission output (W3) supplied to the antenna coil 31 can be made larger than the reception signal (W22). Further, since the transmission output (W3) and the reception signal (W22) are in phase and synchronized with each other, the result of adding them affects the reception of the reader / writer 52.

Further, the received signal (W
Since 22) is a current in the direction of canceling the magnetic field penetrating the antenna coil 31, the phase of the transmission output (W3) of the non-contact IC card 51 is opposite to the phase of the carrier (W12) sent by the reader / writer 52.

Transmission output of non-contact IC card 51 (W3)
Is attenuated according to the distance and the like, and is received by the antenna coil of the reader / writer 52 (W4). The received waveform (W5) actually detected by the reader / writer 52 is the non-contact IC from the carrier (W12) sent by the reader / writer 52 itself.
The result is obtained by subtracting the transmission component (W4) on the card 51 side.

In any case, since the transmission output (W3) of the non-contact IC card 51 is larger than the reception signal (W22) of the non-contact IC card 51, the reader / writer 52 has a larger amplitude (change in intensity). As the signal, the signal (W4, W5) from the non-contact IC card 51 can be received. Therefore, communication is possible even when the distance between the non-contact IC card 51 and the reader / writer 52 becomes long.

Moreover, since the non-contact IC card 51 uses the electric power of the internal power source 32, the non-contact IC card 51
And the distance between the reader / writer 52 and the reader / writer 52 increase, and the contactless I
Even when the received power of the C card 51 becomes small, the electric circuit inside the non-contact IC card 51 can be operated to perform communication. The operation of the wireless communication module shown in FIG. 1 is as shown in FIG. Each step of FIG. 1 will be described below.

In step S11, the antenna coil 31 receives the magnetic field sent from the reader / writer 52. In step S12, the antenna coil 31 is driven by the external magnetic field.
The signal of the induced current induced in the signal is amplified by the reception amplification circuit 11. In step S13, the clock signal synchronized with the received signal is generated by the clock generation circuit 14 based on the signal output from the reception amplification circuit 11.

In step S14, the demodulation circuit 12 demodulates the reception signal appearing at the output of the reception amplification circuit 11. In step S15, the reception signal demodulated by the demodulation circuit 12 is decoded and the received digital signal is reproduced.

In step S16, the information of the received signal output from the decoding circuit 13 is analyzed by the control circuit 33 to check whether or not a predetermined command is received. In step S17, the control circuit 33 creates transmission data of a response according to the received command. In step S18, the transmission data output from the control circuit 33 is transmitted to the encoding circuit 2
Encode with 1.

In step S 19, the modulation circuit 22 modulates the clock signal output from the clock generation circuit 14 using the signal of the transmission data output from the encoding circuit 21. In step S20, the modulation signal output from the modulation circuit 22 is amplified by the transmission amplification circuit 23.

In step S21, the modulation signal output from the transmission amplifier circuit 23 is supplied to the antenna coil 31,
It transmits from the antenna coil 31. (Second Embodiment) Another embodiment of the wireless communication module and the wireless communication method of the present invention will be described with reference to FIG. This form corresponds to claim 3.

FIG. 5 is a block diagram showing the configuration of the wireless communication module of this embodiment. This form is a modification of the first embodiment. In FIG. 5, elements corresponding to those in FIG. 1 are designated by the same reference numerals. The following description will be omitted for the same configurations and operations as those of the first embodiment. In this form, the magnetic field strength detection means and the carrier wave control means of claim 3 correspond to the electromagnetic wave strength detection circuit 15 and the transmission amplification circuit 23A, respectively.

As shown in FIG. 5, in this example, the receiving unit 10
Is provided with an electromagnetic wave intensity detection circuit 15. The electromagnetic wave intensity detection circuit 15 detects the intensity of the electromagnetic wave that reaches the antenna coil 31 as the magnitude of the amplitude of the induced current flowing in the antenna coil 31. The amplification degree of the transmission amplifier circuit 23A is variable. In addition, the transmission amplifier circuit 23A has a built-in attenuator circuit capable of switching the degree of attenuation. The amplification degree and the attenuation degree in the transmission amplification circuit 23A are automatically switched according to the signal of the electromagnetic wave intensity detected by the electromagnetic wave intensity detection circuit 15.

When the signal intensity sent from the wireless communication module is constant as in the first embodiment, the reader / writer 52 of the reader / writer 52 increases as the distance between the non-contact IC card 51 and the reader / writer 52 increases. The amplitude of the modulation component of the received signal becomes small. In addition, the non-contact IC card 51
If the distance between the reader and writer 52 is too short,
The signal strength sent by the wireless communication module becomes excessive,
The reader / writer 52 cannot receive the signal.

Therefore, in this embodiment, the transmission amplifier circuit 23 is responsive to the electromagnetic wave intensity detected by the electromagnetic wave intensity detection circuit 15.
Automatically adjust the amplification or attenuation of A. As a result, when the distance between the non-contact IC card 51 and the reader / writer 52 becomes large and the intensity of the electromagnetic wave reaching the antenna coil 31 becomes small, the transmission amplifier circuit 23A.
Will output a larger modulated signal, and the reader / writer 52 can receive the modulated signal having a relatively large amplitude change from the non-contact IC card 51.

Further, the distance between the non-contact IC card 51 and the reader / writer 52 becomes small, and the antenna coil 31
When the intensity of the electromagnetic wave arriving at the transmission amplifier becomes excessive, the amplitude of the modulation signal output from the transmission amplification circuit 23A is suppressed by the reduction of the amplification degree or the operation of the attenuation circuit in the transmission amplification circuit 23A. It is prevented that the amplitude change of the modulation signal received by the writer 52 becomes excessive.

Therefore, even if the distance between the non-contact IC card 51 and the reader / writer 52 is long or the distance becomes very small, the transmission output of the non-contact IC card 51 is automatically adjusted to perform communication. be able to. (Third Embodiment) Another embodiment of the wireless communication module and the wireless communication method of the present invention will be described with reference to FIG. This form corresponds to claim 6.

FIG. 6 is a block diagram showing the structure of the wireless communication module of this embodiment. This form is a modification of the first embodiment. 6, the elements corresponding to those in FIG. 1 are shown with the same reference numerals. The following description will be omitted for the same configurations and operations as those of the first embodiment. In this form, the power receiving circuit and the load switch means of claim 6 correspond to the power generating circuit 35 and the load switch 34, respectively.

As shown in FIG. 6, a load switch 34, a power generation circuit 35 and a mode switch 36 are added to the wireless communication module of this embodiment. In this embodiment, the non-contact IC card 51 and the reader / writer 52 can communicate with each other even when the battery of the internal power source 32 is exhausted. The operation when the internal power supply 32 can supply sufficient power is the same as in the first embodiment.

The load switch 34 incorporates a resistor, a capacitor, a changeover switch and the like. That is, similarly to the conventional non-contact IC card, the load switch 34 switches the load path of the induced current flowing through the antenna coil 31 between the path through which the current flows and the path through which the current does not flow to change the magnitude of the current. The AC magnetic field formed by the transmission of the reader / writer 52 changes according to the magnitude of the current (load) flowing through the antenna coil 31 of the non-contact IC card 51. This change in the AC magnetic field can be detected by the reader / writer 52.

Therefore, by switching the current path of the antenna coil 31 in accordance with the transmission data of the non-contact IC card 51, the carrier of the reader / writer 52 carries the information of the transmission data of the non-contact IC card 51. It can be transmitted to the reader / writer 52.

When the load switch 34 is used,
Since the transmitter 20 does not need to operate, the power consumption of the wireless communication module can be suppressed. The power generation circuit 35 generates power supply power necessary for the operation of the electric circuits of the control circuit 33 and the load switch 34 based on the current induced in the antenna coil 31 by the alternating magnetic field formed by the transmission of the reader / writer 52. .

In this example, the control circuit 33 uses the internal power source 32.
The voltage of the battery is monitored and the mode switch 36 is automatically switched. That is, the mode switch 3 connects the antenna coil 31 to the output terminal of the transmitter 20 when sufficient power remains in the battery, and connects the antenna coil 31 to the load switch 34 when the battery is exhausted.
Switch 6

(Fourth Embodiment) Another embodiment of the wireless communication module and wireless communication method of the present invention will be described with reference to FIG. This form corresponds to claim 2. FIG. 7 is a block diagram showing the configuration of the wireless communication module of this embodiment. This form is a modification of the first embodiment. In FIG. 7, elements corresponding to those in FIG. 1 are designated by the same reference numerals. The following description will be omitted for the same configurations and operations as those of the first embodiment.

In this embodiment, the power supply means of claim 2,
The antenna coil, the carrier signal generating means and the modulating means,
Each corresponds to the external power supply terminal 38, the antenna coil 31, the clock generation circuit 14, and the modulation circuit 22. As shown in FIG. 7, in this embodiment, an external power supply terminal (for example, a connector) 38 is provided instead of the internal power supply 32. Therefore, it is possible to connect to an external power source (for example, a battery) via the external power source terminal 38 and supply power to each electric circuit in the wireless communication module.

(Fifth Embodiment) Another embodiment of the wireless communication module and wireless communication method of the present invention will be described. This form corresponds to claim 5. The basic configuration of the wireless communication module of this form is the same as that of FIG. However, the functions of some circuits have been changed. That is, the clock generation circuit 14 of this embodiment has a phase inversion function, and the clock generation circuit 14 generates a clock signal having a phase opposite to the phase of the induced current induced in the antenna coil 31.

Further, the antenna coil 3 is applied by an external magnetic field.
Since the induced current (received signal) generated in 1 and the current supplied to the antenna coil 31 by the transmitter 20 are in opposite directions, a clock synchronized with the received signal cannot be generated depending on a certain timing due to current cancellation. there is a possibility. Therefore, in this embodiment, the clock generation circuit 14 has a self-oscillation circuit that oscillates by itself. That is, when the clock generation circuit 14 cannot generate a clock in synchronization with the received signal (transmitter 20
Outputs a clock signal generated by the self-oscillation circuit when a current flows through the antenna coil 31. Of course, the clock signal generated by the self-oscillation circuit is also synchronized with the clock signal generated by the clock generation circuit 14, and thus is controlled so as to be synchronized with the phase of the received signal.

Since the modulation circuit 22 performs modulation using the clock signal generated by the clock generation circuit 14 as a carrier wave, the phase of the modulation signal output from the transmission section 20 is the external magnetic field (the carrier transmitted by the reader / writer 52). Thus, the phase is opposite to the induced current generated in the antenna coil 31.
The induced current (received signal) generated in the antenna coil 31 by the external magnetic field flows in a direction of canceling the external magnetic field, but a signal having a phase opposite to that is supplied from the transmitter 20 to the antenna coil 31. Further, since the power source power supplied from the internal power source 32 is used, the transmission signal output by the transmission unit 20 can be made larger than the amplitude of the reception signal.

When the transmission signal output from the transmission section 20 is larger than the amplitude of the reception signal, the magnetic field of the signal transmitted from the antenna coil 31 of the non-contact IC card 51 is added to the magnetic field generated from the reader / writer 52. , Non-contact IC
The magnetic field strength increases as compared to the case where the card 51 does not transmit. Further, since the signal transmitted by the non-contact IC card 51 is modulated by the transmission data, the reader / writer 52
The transmission data of the non-contact IC card 51 can be detected from the change of the magnetic field strength. Further, since the magnetic field strength is larger than that in the case of using the conventional non-contact IC card, communication is possible even when the distance between the non-contact IC card 51 and the reader / writer 52 is long.

In practice, the transmitting unit 20 controls the current flowing through the antenna coil 31 so that the reception level of the reader / writer 52 changes significantly when the non-contact IC card 51 is modulated and when it is not modulated. . There are the following two types of control methods (3) and (4). (3) When the non-contact IC card 51 modulates for transmission (corresponding to the ON state of the load switch), the transmission unit 20
To the antenna coil 31 to stop the current output from the transmitter 20 when no modulation is performed. As a result, the reception level of the reader / writer 52 becomes very large when the non-contact IC card 51 transmits a modulation signal and becomes small when there is no modulation, so that the amplitude difference between the modulation wave and the non-modulation wave is large and the distance is long. Communication becomes possible.

(4) When the non-contact IC card 51 transmits a non-modulated signal, a current is sent from the transmitter 20 to the antenna coil 31 to modulate (corresponding to the ON state of the load switch) the transmitter 20. Stop the current output by. As a result, the reception level of the reader / writer 52 becomes extremely large when the non-contact IC card 51 transmits an unmodulated signal and becomes relatively small during modulation, so that the difference in amplitude between the modulated wave and the unmodulated wave is large and long. Distance communication is possible.

The first embodiment and the fifth embodiment can be combined. For example, non-contact IC
When the card 51 transmits a non-modulated signal, a current having the same phase as the induced current flowing through the antenna coil 31 of the non-contact IC card 51 is sent from the transmitter 20 to the antenna coil 31 as in the first embodiment. When the contact IC card 51 modulates for transmission (corresponding to the ON state of the load switch), the contactless IC is used as in the fifth embodiment.
A current having a phase opposite to the induced current flowing through the antenna coil 31 of the card 51 is passed from the transmitter 20 to the antenna coil 31.

On the contrary, when the non-contact IC card 51 transmits a non-modulated signal, a current having a phase opposite to the induced current flowing through the antenna coil 31 of the non-contact IC card 51 is transmitted as in the fifth embodiment. Part 20 to antenna coil 31
When the non-contact IC card 51 modulates for transmission (corresponding to the ON state of the load switch), the induction flowing to the antenna coil 31 of the non-contact IC card 51 is performed as in the first embodiment. A current in phase with the current is transmitted by the transmitter 20
May be supplied to the antenna coil 31.

As described above, the in-phase signal and the anti-phase signal are combined and supplied from the transmitting section 20 to the antenna coil 31, so that the non-contact IC card 51 transmits the non-modulated signal and the modulated signal. When this is done, the change in the reception level of the reader / writer 52 becomes larger, and long-distance communication becomes possible. In each of the above embodiments, the case where the wireless communication module is mounted on the non-contact IC card has been described, but the wireless communication module of the present invention can be applied to other systems. Further, as long as it is a system that performs communication by amplitude modulation, the wireless communication module of the present invention can be applied even if the system does not use the international standard communication system as shown in FIG.

[0080]

As described above, according to the present invention, the non-contact I
The communicable distance of a C card or the like can be made longer than before. Moreover, since the same communication method as that of the conventional non-contact IC card is basically used, the existing reader / writer can be used as it is without the need to make a large change to the system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless communication module according to a first embodiment.

FIG. 2 is a perspective view showing a configuration example of a system.

FIG. 3 is a flowchart showing an operation of the wireless communication module according to the first embodiment.

FIG. 4 is a time chart showing a signal waveform according to the first embodiment.

FIG. 5 is a block diagram showing a configuration of a wireless communication module according to a second embodiment.

FIG. 6 is a block diagram showing a configuration of a wireless communication module according to a third embodiment.

FIG. 7 is a block diagram showing a configuration of a wireless communication module according to a fourth embodiment.

FIG. 8 is a schematic diagram showing a current of each antenna coil.

FIG. 9 is a waveform diagram showing an international standard signal waveform.

FIG. 10 is a time chart showing a signal waveform of a conventional example.

[Explanation of symbols]

10 Receiver 11 Receive amplifier circuit 12 Demodulation circuit 13 Decoding circuit 14 Clock generation circuit 15 Electromagnetic wave intensity detection circuit 20 Transmitter 21 Encoding circuit 22 Modulation circuit 23,23A transmission amplifier circuit 31 antenna coil 32 Internal power supply 33 Control circuit 34 load switch 35 Power generation circuit 36 mode switch 38 External power supply terminal 51 Non-contact IC card 52 Reader / Writer 53 Host device 61 antenna coil

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naofumi Suzuki             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Yasuhiro Nagai             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 2C005 MA22 NA08 NA09                 5B035 AA07 BB09 CA12 CA23                 5K012 AB02 AC06 AC08 AC10 AE13

Claims (8)

[Claims] 1. A wireless communication module for performing non-contact communication by electromagnetic induction with a reading / writing device that generates an AC magnetic field using the AC magnetic field as a communication medium, the battery comprising: an antenna coil; Carrier power signal generating means for generating a carrier signal synchronized with the alternating current, based on the alternating current induced by the alternating magnetic field penetrating the antenna coil, and the power supplied from the battery. By using, to modulate the carrier signal generated by the carrier signal generating means with transmission data,
A wireless communication module comprising: a modulation unit that supplies a modulated signal to the antenna coil. 2. A wireless communication module for performing contactless communication by electromagnetic induction with a reading / writing device which generates an AC magnetic field using the AC magnetic field as a communication medium, and a power supply means connectable to an external power source. A carrier wave signal generation for generating a carrier wave signal synchronized with the alternating current, based on an alternating current induced by an alternating magnetic field penetrating the antenna coil, using an antenna coil and electric power supplied from the electric power supply means. Means for modulating the carrier wave signal generated by the carrier wave signal generating means with transmission data using the power supplied from the power supply means, and supplying the modulated signal to the antenna coil. A wireless communication module characterized by the above. 3. The wireless communication module according to claim 1 or 2, wherein the magnetic field strength detecting means for detecting the magnetic field strength received by the antenna coil, and the magnetic field strength detected by the magnetic field strength detecting means, A wireless communication module, further comprising a carrier wave control means for automatically changing the magnitude or amplification degree of the carrier wave signal generated by the carrier wave signal generation means. 4. The wireless communication module according to claim 1 or 2, wherein the carrier wave signal generating means generates a carrier wave signal having the same phase as an alternating current induced in the antenna coil. 5. The wireless communication module according to claim 1 or 2, wherein the carrier wave signal generating means generates a carrier wave signal having a phase opposite to an alternating current induced in the antenna coil and having a power larger than the alternating current. A wireless communication module characterized by. 6. The wireless communication module according to claim 1, wherein a power receiving circuit that generates direct current power from the alternating current induced in the antenna coil, and a load path of the alternating current induced in the antenna coil. And a load switch unit for switching the switch according to the transmission data. 7. The wireless communication module according to claim 1, claim 2, claim 3, claim 4, claim 5, or claim 6, wherein the wireless communication module is mounted in a card-shaped case. Communication module. 8. A wireless communication method used to control a wireless communication module that performs contactless communication by electromagnetic induction with a reading / writing device that generates an alternating magnetic field using the alternating magnetic field as a communication medium. Based on an alternating current induced by an alternating magnetic field penetrating an antenna coil mounted on a module, a carrier signal synchronized with the alternating current is generated, the carrier signal is modulated with transmission data, and the modulated signal is the antenna. A wireless communication method comprising supplying a coil and transmitting a signal.