JP2001177449A - Communication unit, communication method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select a proper resonance frequency from a transmission reception state and to switch to it. SOLUTION: In a step S1, a controller transmits a Read Command to a receiver side communication unit to request the communication unit to transmit data stored in a prescribed block of a memory. Upon the receipt of the Read Command, the receiver side communication unit returns a Read Response, and when not receiving the Read Command, the communication unit returns no Read Response. In a step S2, the controller discriminates whether the controller has received the Read Response. When the controller discriminates that the controller has received the Read Response, the controller discriminates that the controller is in a communication enable state with the receiver side communication unit in a step S3, and executes information communication. When the controller discriminates that the controller has received no Read Response, the controller changes a resonance frequency of an antenna in a step S4. The processing returns to the step S1 and the processing after the step S1 is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus, a communication method, and a recording medium, and confirms a transmission / reception state, selects an appropriate one from a plurality of resonance frequencies based on the result, and automatically switches the resonance frequency. Accordingly, the present invention relates to a communication device, a communication method, and a recording medium capable of realizing reliable non-contact communication without adjustment.

[0002]

2. Description of the Related Art As shown in FIG. 1, communication between a communication device 1 having an antenna 3 and a communication device 2 having an antenna 4 is as follows.
There is a technique for transmitting and receiving signals in a non-contact manner using electromagnetic coupling generated between the antennas 3 and 4. When the antennas 3 and 4 of the communication device 1 and the communication device 2 are each composed of the general RLC circuit shown in FIG. 2, an equivalent circuit of the antenna 3 and the antenna 4 is shown in FIG. Communication performed between the antennas 3 and 4 is performed by the mutual inductance M.

The impedances Z1 to Z5 in FIG.
, Z1 is the impedance 1 / jωC1 of the capacitor C1 of the antenna 3, and Z2 is the mutual inductance M from the resistance R1 of the antenna 1 and the inductance L1.
Is the combined impedance R1 + jω (L1-M) with the inductance L1-M, Z3 is the impedance jωM corresponding to the mutual inductance M, and Z4 is the resistance R2 of the antenna 2 and the inductance obtained by subtracting the mutual inductance M from the inductance L2. Combined impedance R2 + jω (L2-M) with L2-M, Z5
Is the impedance 1 / of the capacitor C2 of the antenna 2
jωC2.

[0004] In the circuit of FIG.
Assuming that the current flowing through the impedance Z5 is i1 and the current flowing through the impedance Z5 is i2, the current i1 and the current i2 are expressed by the following equations 1 and 2, respectively. i1 = −SEin × Z1 / {Z1 + Z2 + Z3 (Z4 + Z5) / (Z3 + Z4 + Z5)} (1) i2 = i1 × Z3 / (Z3 + Z4 + Z5) (2) where S is an amplifier for driving the antenna 1 Is the mutual susceptance. Therefore, -SEin is the total current of the circuit.

[0005] A voltage value E2 applied to both ends of the antenna 2 is expressed by the following equation (3). E2 = i2 × Z5 = i1 × Z3 × Z5 / (Z3 + Z4 + Z5) (3) When the inverse amplification D, which is the reciprocal of the amplification G, is obtained from Expressions 1 to 3, the following Expression 4 is obtained.

D = 1 / G = Ein / E2 = {− 1 / (S × Z1 × Z3 × Z5)} × {(Z1 + Z2 + Z3) (Z3 + Z4 + Z5) −Z32} (4) where primary is Assuming that both the circuit and the secondary circuit are resonating, the resonance frequency ω0 is represented by the following Expression 5.

(Equation 1) (5) When the coupling coefficient is k, k is expressed by the following Expression 6 from the mutual inductance M and the values of the inductances L1 and L2 of the antennas 1 and 2.

(Equation 2) ・ ・ (6)

[0007] Q (quality factor) at resonance
Is Q1 in the primary circuit and Q2 in the secondary circuit, Q1 and Q2 are expressed by the following equations 7 and 8 from the inductances L1 and L2 of the antennas 1 and 2 and the resistors R1 and R2. . Q1 = ω0L1 / R1 (7) Q2 = ω0L2 / R2 (8)

Accordingly, if the loss rate d is d1 in the primary circuit and d2 in the secondary circuit, the loss rate d1 and the loss rate d2 are
It is expressed by the following equations 9 and 10. d1 = 1 / Q1
(9) d2 = 1 / Q2 (10)

Assuming that the detuning rate representing the difference between the actual communication frequency ω and the resonance frequency ω0 is x, the detuning rate x is expressed by the following equation (11).
It is represented by x = (ω−ω0) / ω0 (11) Here, since the vicinity of the resonance point is handled, the following equation 12 holds.

(Equation 3) ... (12)

Therefore, when Equations 5 to 12 are substituted into Equation 4 and rearranged, Equation 13 is derived.

(Equation 4) ... (13)

Here, the frequency characteristic of the reverse amplification gain is expressed by the following equation (1).
1 / k {(d1 + j2x) {d2
+ J2x} + k2}.
The following equation 14 is used as the frequency characteristic y of the inverse amplification gain.

(Equation 5) ... (14)

Since the maximum point and the minimum point at the inflection point of the frequency characteristic (communication efficiency) are the points where dy / dx = 0 in the equation (14), the maximum point is obtained by the following equations (15) and (16). Is represented by the following Expression 17 and Expression 18. x0 = 0 (15) y0 = (k2 + d1d2) / k (16)

(Equation 6) ... (17)

(Equation 7) ... (18)

Further, the optimum coupling coefficient k0 for obtaining the maximum gain (ie, at the time of critical coupling) is obtained by differentiating Equation 16 with respect to k, and is k such that dy0 / dk = 0. Indicated at 19.

(Equation 8) ... (19)

At this time, y0 can be obtained by substituting equation 19 into equation 16. The value of y0 at the time of critical coupling is given by Equation 2.
0 is shown.

(Equation 9) (20) Accordingly, the gain G0 is expressed by Expression 21.

(Equation 10) ... (21)

Assuming that the antennas 3 and 4 have the same performance, d1 = d2 = d = k0, y0 = yb = 2d
Becomes FIG. 4 shows that for Equation 11, the coupling coefficient k is k <k
0, k = k0, transmission frequency characteristic y when k> k0
Is shown. From FIG. 4, when the coupling coefficient k is k ≦ k0, y has a single-peak characteristic, and as k approaches k0, the value of y at x = 0 decreases. 4, the transmission frequency characteristic y changes from a single-peak characteristic to a wavy (bimodal) characteristic, and the maximum value of the communication efficiency at the time of the critical coupling (k = k0) and the wavy characteristic (k> k0) (ie,
It can be seen that the transmission frequency characteristic y has the same value. Further, the voltage value E1 of the antenna 1 also shows substantially the same characteristics. As can be seen from these, even when k becomes smaller from the critical coupling point k0, the passband center frequency level decreases, and the communication efficiency deteriorates. In other words, it is understood that communication becomes difficult if the non-contact distance (distance between antennas) is too short or too long.

The coupling coefficient k between the antennas is determined by the shape and relative distance of the antenna, but the critical coupling condition k0
Is determined by Q1 and Q2 of the antennas 3 and 4 as shown in Expression 19. Therefore, the transmission frequency characteristics such as whether the transmission frequency at a certain coupling coefficient k exhibits a single-peak characteristic or a wavy characteristic can be controlled to some extent by adjusting the Q of the antenna. That is, by changing the value of Q of this antenna into two values according to information to be transmitted, AS
Information can be transmitted and received using K (Amplitude shift keying).

In general, the communication device 2 has no power supply with respect to the communication device 1, and the degree of modulation is set to low modulation in order to suppress the spread of the ASK band, rectify the high-frequency signal and use it as its own power source. You. When information is transmitted from the communication device 2 to the communication device 1, the Q of the antenna 4 is set according to the information to be transmitted.
2 to change the resistance R2 of the antenna 4 equivalently.
Is turned ON / OFF (FIG. 2). When transmitting information from the communication device 1 to the communication device 2, the circuit current value of the antenna 3 is changed according to the information to be transmitted. Mutual communication is performed in a time-division (half-duplex) manner. While the communication device 1 is transmitting a signal, Q2 of the communication device 2 is fixed, while the communication device 2 is transmitting a signal. , The circuit current value of the communication device 1 is fixed.

FIG. 5 shows transmission frequency characteristics (output voltage with respect to communication frequency) when the resistor R2 of FIG. 2 is switched OFF when the information signal bit is 0 and ON when the information signal bit is 1. . 13.56 MHz carrier signal frequency
In the vicinity of (point c), a signal having an amplitude change corresponding to ON / OFF of the resistor R2 is supplied to the antenna 3 of the communication device 1. The difference between the transmission amplitudes is represented by A
This is the SK signal. In this case, although a binary change is obtained by a combination of the wavy characteristics, a binary change may be obtained by a combination of the wavy characteristic and the single-peak characteristic depending on circumstances.

[0019]

However, as shown in FIG. 5, the carrier signal frequency is 13.097 MHz.
As approaching z (point a), the difference in amplitude corresponding to ON / OFF of the resistor R2 decreases, and the modulation degree of ASK decreases. When the carrier signal frequency reaches 13.097 MHz (point a), the difference in amplitude disappears, and
The transmission of the signal to is disabled. This point is herein referred to as a “modulation null point”. 14.2
Even at 62 MHz (point b), 13.097 MHz (point a)
The same failure occurs. After this modulation null point,
Again, a modulated signal can be obtained. Although the polarity of 0/1 at the time of modulation is inverted, all bits are inverted, so that the receiving side can easily cope with it and decode data correctly.

FIG. 5 illustrates the case where the communication frequency is changed. However, the same trouble occurs when the communication frequency is fixed and the resonance frequency of each antenna varies. FIG. 6A shows a test result of a practical communication distance when the antenna resonance frequency of the antenna 3 of the communication device 1 is tuned to 13.56 MHz and the antenna resonance frequency of the antenna 4 of the communication device 2 is varied. The antenna resonance frequency of the antenna 3 of the communication device 1 is
FIG. 6B shows a test result of a practical communication distance when tuning is performed to 4.1 MHz and the antenna resonance frequency of the antenna 4 of the communication device 2 is varied.

As described above, the communication device 1 and the communication device 2
Is too far from the critical coupling point (for example, when the distance between the antennas exceeds 4 mm) and too close to the critical coupling point (for example, when the distance between the antennas is less than 1.4 mm). Regardless of the value of the resonance frequency 2, a communication failure occurs. However, a communication failure that occurs in other cases is a communication failure due to a modulation null point. That is, the resonance frequency 1 of the antenna 3 of the communication device 1
At 3.56 MHz, the resonance frequency of the antenna 4 of the communication device 2 is 12.63 MHz, the portion near the communication distance of 2.3 mm (the portion indicated by a in FIG. 6A), and the communication device 1
The resonance frequency of the antenna 4 of the communication device 2 at the resonance frequency of 14.1 MHz of the antenna 3 of 13.84 MHz,
Communication distance 2mm to 2.6mm and 3mm to 3.6
A communication failure in a portion near mm (portions indicated by b and c in FIG. 6B) is caused by a modulation null point.

As described above, the communication device 1 and the communication device 2
When the antenna resonance frequency varies, communication may or may not be possible depending on the communication distance.

Further, when an attempt is made to extend the communication distance by increasing the value of Q of the antenna, a modulation null point is likely to occur near a target communication frequency. Further, the allowable value of the variation of the general-purpose parts constituting the antenna is set to, for example, ± 5%.
Then, it is extremely likely that these failures will occur, and it has been difficult to realize non-adjustable and reliable non-contact communication.

The present invention has been made in view of such a situation, and confirms the state of transmission and reception, selects an appropriate one from a plurality of resonance frequencies based on the result, and automatically switches the resonance frequency. A non-adjustment and reliable non-contact communication is realized.

[0025]

According to a first aspect of the present invention, there is provided a communication apparatus comprising: a setting unit for setting a resonance frequency of an antenna; a detecting unit for detecting a transmission / reception state; and a setting unit according to a detection result of the detecting unit. Changing means for changing the set resonance frequency of the antenna.

According to a fourth aspect of the present invention, there is provided a communication method comprising: a setting step of setting a resonance frequency of an antenna; a detecting step of detecting a transmission / reception state; and a setting step according to a detection result of the detecting step. And changing the resonance frequency of the antenna.

The program recorded on the recording medium according to claim 5 includes a setting step of setting a resonance frequency of the antenna, a detecting step of detecting a transmission / reception state,
A changing step of changing a resonance frequency of the antenna set by the processing of the setting step according to a detection result by the processing of the detecting step.

According to a sixth aspect of the present invention, there is provided a communication apparatus for storing data used for detecting a transmission / reception state of communication with another communication apparatus, and for detecting a communication state from the other communication apparatus. And transmitting means for transmitting data to another communication device when a data transmission request is received.

[0029] According to a communication method of the present invention, a storage control step for controlling storage of data used for detecting a transmission / reception state of communication with another communication apparatus, and a communication state is controlled by the other communication apparatus. Sending a data transmission request to another communication device when receiving a data transmission request for detection.

[0030] The program recorded on the recording medium according to claim 8 is an acquisition control step for controlling acquisition of data used for detecting a transmission / reception state of communication with another communication device, and another communication. When receiving a data transmission request from the device to detect the communication state, the device includes a transmitting step of transmitting the data acquired by the processing of the acquiring step to another communication device.

In the communication device according to the first aspect, the communication method according to the fourth aspect, and the program of the recording medium according to the fifth aspect, the resonance frequency of the antenna is set,
The transmission / reception state is detected, and the resonance frequency of the antenna is changed according to the detection result.

In the communication device according to the sixth aspect, the communication method according to the seventh aspect, and the program of the recording medium according to the eighth aspect, the transmission / reception state of communication with another communication device is detected. The data to be used is stored, and when a data transmission request is received from another communication device to detect a communication state, the data is transmitted to the other communication device.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 is a block diagram showing a configuration of the communication device 11 and the communication device 12 to which the present invention is applied. Here, the communication device refers to a general device for exchanging information by non-contact communication, for example, a VTR, a cassette, a mobile phone, a card, a CAM, and the like.

The controller 21 of the communication device 11 transmits the data of a predetermined block of the data stored therein (for example, stored in the memory 35 of the communication device 12) by the communication device on the receiving side. Generates a Read Command requesting the internal bus 22 and the input / output interface 2
3 to the transmission / reception unit 24. The transmitting / receiving unit 24
By changing the circuit current value of the antenna 13,
Control (ASK) the amplitude modulation of the supplied data, and read
Command is transmitted from the antenna 13 to the communication device 12.

Then, the controller 21 controls the communication device 1
2 receives Read Command and replies to it
The ad Response (that is, data of a predetermined block stored in the memory 35 of the communication device 12) is transmitted to the antenna 1
3. If the data is received via the transmission / reception unit 24, the input / output interface 23, and the internal bus 22, it is determined that the communication is normally performed, and the data communication is performed. Read C
If the Read Response to the ommand has not been received, the controller 21 sends the internal bus 2
2 and a control signal for changing the resonance frequency of the antenna 13 via the input / output interface 23. The transmission / reception unit 24 receives a control signal from the controller 21 and changes the resonance frequency adjustment voltage of the antenna 13 in order to change the resonance frequency of the antenna 13 (change the value of the resonance capacitance).

As described with reference to FIG. 6, the modulation null point at a certain resonance frequency and the modulation null point at another resonance frequency in the vicinity of the modulation null point occur at different resonance frequencies of the receiving side device and at different distances between the devices. I do. Therefore, by changing the resonance frequency of the transmission-side device in accordance with the reception-side resonance frequency and the inter-device distance, it is possible to eliminate a communication failure due to a modulation null point. Communication device 11
For example, one or more sub-frequency (sub-tune), which is a value obtained by offsetting the frequency by about 500 KHz to 2 MHz with respect to the main resonance frequency (main tune), can be set (that is, antenna 1
3 can be set in advance, and the resonance frequency is sequentially switched while confirming the communication state with the receiving side device according to the processing described later with reference to FIG. (Searching).
Here, such a configuration in which stable communication can be obtained by changing the tune is referred to as tune diversity.

The controller 21 includes, for example, the magnetic disk 41 and the optical disk 4 inserted in the drive 26.
2. Data is read from the magneto-optical disk 43, the semiconductor memory 44, and the like, and stored in the memory 25 via the input / output interface 23, or the data stored in the memory 25 is read, and the internal bus 22 and the input / output interface The signal is supplied to the transmission / reception unit 24 via the transmission / reception unit 23. The transmission / reception unit 24 controls the amplitude modulation of the supplied data by changing the circuit current value of the antenna, and transmits the data from the antenna 13 to the communication device 12. The information transmitted from the communication device 12 is received by the antenna 13, demodulated by the transmission / reception unit 24, and input to the controller 21 via the input / output interface 23 and the internal bus 22. The controller 21 stores the input data in the memory 25, or determines that the communication is normally performed when the input data is a Read Response.

In the communication device 12, data transmitted from the communication device 11 is received by the antenna 14, demodulated by the transmission / reception unit 31, and supplied to the controller 34 via the input / output interface 32 and the internal bus 33. The controller 34 executes processing in accordance with the supplied data, and stores the supplied data or data generated by the executed processing in the memory 3 as necessary.
Save to 5. The memory 35 stores predetermined data used to check the state of transmission and reception with the communication device 11.

For example, from the communication device 11, a Read Command
Is received, the controller 34 reads the data stored in a predetermined block of the memory 35, and via the internal bus 33 and the input / output interface 32,
It is supplied to the transmission / reception unit 31. The transmission / reception unit 31 controls the amplitude modulation of the supplied data (ASK) by switching ON / OFF of a resistor R12 of the antenna 14 described later with reference to FIG. 14 to the communication device 11.

The input / output interface 32 includes:
The drive 36 is also connected, and the controller 34
For example, the magnetic disk 41 inserted into the drive 36,
Data is exchanged with the optical disk 42, the magneto-optical disk 43, the semiconductor memory 44, and the like.

The power generation unit 37 generates power required for the operation of the communication device 12 by rectifying the received signal, and supplies the power to each unit of the communication device 12.

When the communication device on the receiving side is a very small communication device such as a card, for example, FIG.
It is preferable to adopt a configuration in which a drive and an input / output interface are not provided like the communication device 51 shown in FIG.
The antenna 52 and the transmission / reception unit 61 to the power generation unit 64 of the communication device 51 perform the same processing as the antenna 14, the transmission / reception unit 31, the controller 34, the memory 35, and the power generation unit 37 of the communication device 12 described with reference to FIG. , And the description is omitted here.

When the communication device on the receiving side is, for example, a communication device of the size of a portable telephone, it is difficult to incorporate a drive or the like, so that the communication device 7 shown in FIG.
By providing the network interface 86 as shown in FIG. 1, an external device such as a drive may be connected externally. The communication device 71 has the same configuration as the communication device 12 described with reference to FIG. 7 except that the communication device 71 includes a network interface 86 instead of the drive 36 of the communication device 12 described with reference to FIG. Description is omitted.

FIG. 9 shows a communication device 11 and a communication device 12.
The detailed configuration of the antennas 13 and 14 of FIG. The antenna 13 and the antenna 14
In order to make it possible to change the resonance frequency of the variable capacitance diode (varicap) D11 in place of the capacitor C1 of the antenna 3, the input for changing the applied voltage E11 of the variable capacitance diode D11 is a variable capacitance diode.
Except that it is added to the cathode side of D11, the configuration is basically the same as that described with reference to FIG.
A variable capacitance diode is an element having a characteristic that the capacitance between the anode and the cathode changes according to the voltage value when a reverse bias is applied. The transmission / reception unit 24 of the communication device 11 performs processing described below with reference to FIG.
By changing the voltage E11 applied to the variable capacitance diode D11 and controlling its capacitance, the antenna 13
To change the resonance frequency.

Next, the antenna diversity searching process of the communication apparatus 11 will be described with reference to the flowchart of FIG.

In step S1, the controller 21
Corresponds to the memory 35 of the communication device 12.
Is a signal for reading data of a predetermined block stored in the communication device 11 and returning it to the communication device 11.
A Read Command is transmitted via the internal bus 22, the input / output interface 23, the transmitting / receiving unit 24, and the antenna 13. The antenna 14 of the communication device 12
If the mand can be received, the received signal
1, supplied to a controller 34 via an input / output interface 32 and an internal bus 33,
According to the Read Command, data is read from the specified block of the memory 35, and the data is read from the designated block.
nse, internal bus 33, input / output interface 3
2. Transmission to the communication device 11 via the transmission / reception unit 31 and the antenna 14. When the antenna 14 cannot receive the Read Command, the communication device 12
ad Response is not sent.

In step S2, the controller 21
Determines whether a Read Response has been received based on data input via the antenna 13, the transmission / reception unit 24, the input / output interface 23, and the internal bus 22. When it is determined in step S2 that the Read Response has been received, in step S3, the controller 21 determines that the communication with the communication device 12 is currently possible, and executes data communication. Then, the process returns to step S1, and the subsequent processes are repeated.

If it is determined in Step S2 that the Read Response has not been received, in Step S4, the controller 21 outputs a control signal for changing the resonance frequency of the antenna 13 to a resonance frequency other than the current resonance frequency. It is generated and output to the transmission / reception unit 24 via the internal bus 22 and the input / output interface 23. This control signal is, for example, if two resonance frequencies of main tune and sub tune are prepared in advance in the communication device 11 and communication is currently performed by main tune,
If the resonance frequency is changed to subtune and communication is currently performed by subtune, an instruction is issued to change the resonance frequency to maintune. Transceiver 2
4 changes the resonance frequency of the antenna 13 by changing the value of the resonance frequency adjustment voltage applied to the variable capacitance diode D11 of the antenna 13 according to the input control signal. Then, the process returns to step S1, and the subsequent processes are repeated.

Referring to FIG. 11, the antenna 13 of the communication apparatus 11 and the communication apparatus 12 will be described with reference to FIG.
The case where the distance to the antenna 14 changes will be considered.

For example, if the distance between antennas is 5 mm or more,
Consider a case where the distance between antennas is gradually reduced from the state where it is determined that a communication failure has occurred in both main tune and sub tune. Here, two resonance frequencies of a main tune and a sub tune are set in the communication device 11, and the main tune is set slightly higher than the communication frequency in order to improve a practical communication distance. In order to compensate for a communication failure due to a modulation null point in the main tune, the frequency is set to be about 500 kHz higher than the main tune.

When the distance between the antennas is 4.2 mm or more,
Since it is determined that a communication failure has occurred, the communication device 1
1 executes searching. When the distance between the antennas gradually approaches 4.2 mm, the main tune is an advantageous frequency in the communication distance,
At the distance between the antennas indicated by A0 in the figure, communication can be performed in the main tune.

When the distance between the apparatuses is further reduced to 3.6 mm, a modulation null point occurs at the current main tune frequency, and a communication failure occurs. That is, even if the communication device 11 transmits the Read Command,
However, the Read Response is not returned to the communication device 11. The controller 21 outputs a control signal for changing the resonance frequency to the subtune to the transmission / reception unit 24, and the transmission / reception unit 24 changes the value of the voltage applied to the variable capacitance diode D11 of the antenna 13, Adjust the frequency to the subtune, and send a Read Command to the communication device 12.
Send In the subtune, normal communication is possible even at a distance between the antennas of 3.0 mm to 3.6 mm (indicated by B2 in the figure).
The communication device 12 that has received the response returns a Read Response to the communication device 11. Then, the communication device 11 and the communication device 12
Starts normal communication. Thereafter, when a communication failure occurs due to a change in the distance between the antennas, the controller 21 controls the value of the voltage applied to the variable capacitance diode D11 to execute the tune, and always maintains a communicable state. .

In this way, even when the communication state changes with the change of the distance between the antennas, the communication device 11 automatically selects and sets the communicable resonance frequency so that the user can set the resonance frequency. It is possible to maintain a good communication state without performing a tuning operation or adjustment.

In FIG. 12, the antenna resonance frequency of the antenna 13 of the communication apparatus 11 is set to a main frequency of 13.56 MHz, which is a communication frequency, and to a subtune of 13.56 MHz.
The test results of the practical communication distance when the tune diversity is executed at two frequencies of 1 MHz and the antenna resonance frequency of the antenna 14 of the communication device 12 is varied are shown.

For example, when normal communication cannot be performed at the resonance frequency of 13.56 MHz which is the main tune (ie,
6A, the resonance frequency is changed to 14.1 MHz by the tune diversity, and is normal at the resonance frequency of 14.1 MHz which is a subtune. When communication is not possible (that is, in the case where the communication failure indicated by b and c in FIG. 6B described above occurs), the resonance frequency is changed to 13.56 MHz by tune diversity. . In other words, the test result in the case of using the tune diversity shown in FIG. 12 is equal to the result obtained by combining the communicable portions of the test results shown in FIGS. 6A and 6B. It turns out that it is.

As can be seen from FIG. 12, in the communication apparatus to which the present invention is applied, the use of the tune diversity eliminates the communication failure at the modulation null point, and achieves the non-adjustment and highly reliable communication. It is possible to do.

The software for executing the above-described series of processing may be a computer (for example, the controller 21 or the controller 34 in FIG. 7) in which a program constituting the software is built in dedicated hardware, or various programs. Is installed from a recording medium to, for example, a general-purpose personal computer capable of executing various functions.

As shown in FIG. 7, this recording medium is a magnetic disk 41 (including a floppy disk) on which the program is recorded and an optical disk 42, which are distributed separately from the computer to provide the user with the program.
(CD-ROM (Compact Disk-Read Only Memory), DVD (Di
gital Versatile Disk), magneto-optical disk 43
(Including MD (Mini-Disk)) or semiconductor memory 4
4 and the like.

In this specification, the step of describing a program recorded on a recording medium may be performed in a chronological order according to the described order, or may not necessarily be performed in a chronological order. This also includes processing executed in parallel or individually.

[0061]

According to the communication device of the first aspect, the communication method of the fourth aspect, and the program of the recording medium of the fifth aspect, the resonance frequency of the antenna is set, and the transmission / reception state is set. By detecting and changing the resonance frequency of the antenna according to the detection result, the state of transmission and reception is confirmed, and by selecting the appropriate one from a plurality of resonance frequencies based on the result, by automatically switching, Non-contact and reliable non-contact communication can be realized.

According to the communication device of the sixth aspect, the communication method of the seventh aspect, and the program of the recording medium of the eighth aspect, the state of transmission / reception of communication with another communication device is detected. When data transmission request is received from another communication device to detect a communication state, the data is transmitted to another communication device. The communication device on the side can confirm the state of transmission and reception, and can realize reliable non-contact communication without adjustment.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a communication device that performs electromagnetic coupling non-contact communication.

FIG. 2 is a diagram for explaining a circuit of an antenna of a conventional communication device that performs electromagnetic coupling non-contact communication.

FIG. 3 is a diagram showing an equivalent circuit of the antenna 3 and the antenna 4 of FIG.

FIG. 4 is a diagram illustrating a relationship between a coupling coefficient k and a transmission frequency characteristic y.

FIG. 5 is a diagram illustrating a relationship between an output voltage and a communication frequency.

FIG. 6 is a diagram showing the influence of the communication distance and the variation of the reception-side resonance frequency in the conventional electromagnetic coupling non-contact communication.

FIG. 7 is a block diagram showing a communication device to which the present invention is applied.

FIG. 8 is a block diagram showing a communication device to which the present invention is applied.

FIG. 9 is a diagram illustrating a circuit of an antenna of a communication device to which the present invention is applied.

FIG. 10 is a flowchart illustrating a process of switching antenna tunes.

FIG. 11 is a diagram for explaining switching between antennas and tune.

FIG. 12 is a diagram illustrating the influence of the communication distance and the variation of the receiving-side resonance frequency in the electromagnetic coupling non-contact communication to which the present invention is applied.

[Description of Signs] 11, 12 Communication device, 13, 14 Antenna, 2
1 controller, 22 internal bus, 23 input / output interface, 24 transceiver, 25 memory,
31 transceiver unit, 32 input / output interface,
33 internal bus, 34 controller, 35 memory

Claims (8)

[Claims] 1. A communication device for transmitting and receiving data to and from another communication device, comprising: setting means for setting a resonance frequency of an antenna; detecting means for detecting a transmission / reception state; and setting according to a detection result of the detecting means. Changing means for changing the resonance frequency of the antenna set by the means. 2. The communication device according to claim 1, wherein the detecting unit includes:
The information processing apparatus according to claim 1, wherein a transmission request for predetermined data is transmitted, and a transmission / reception state is detected based on whether or not the predetermined data has been received from the another communication apparatus. 3. The resonance frequency of the plurality of antennas set by the setting means is provided in advance, and the changing means sequentially switches the resonance frequencies of the plurality of antennas provided in advance to perform the setting. 2. The information processing apparatus according to claim 1, wherein the resonance frequency of the antenna set by means is changed. 4. A communication method of a communication device for transmitting and receiving data to and from another communication device, comprising: a setting step of setting a resonance frequency of an antenna; a detection step of detecting a transmission / reception state; A changing step of changing the resonance frequency of the antenna set by the processing of the setting step according to a result. 5. A program for a communication device for transmitting and receiving data to and from another communication device, comprising: a setting step of setting a resonance frequency of an antenna; a detection step of detecting a transmission / reception state; A changing step of changing the resonance frequency of the antenna set by the processing of the setting step in accordance with the detection result by the computer-readable recording medium. 6. A communication device for transmitting and receiving data to and from another communication device, wherein: a storage unit for storing data used for detecting a transmission / reception state of communication with the another communication device; and the other communication device. A communication device, further comprising: a transmission unit configured to transmit the data to the another communication device when a request for transmitting the data is received to detect a communication state. 7. A communication method of a communication device for transmitting / receiving data to / from another communication device, comprising: a storage control step of controlling storage of data used for detecting a transmission / reception state of communication with the other communication device. A transmission step of transmitting the data to the other communication device when receiving a request for transmitting the data to detect a communication state from the other communication device. 8. A program for a communication device for transmitting / receiving data to / from another communication device, the acquisition control being configured to control the acquisition of data used for detecting a transmission / reception state of communication with the other communication device. And a transmission step of transmitting the data obtained by the processing of the obtaining step to the other communication apparatus when receiving a transmission request for the data to detect a communication state from the other communication apparatus. A recording medium on which a computer-readable program is recorded.