JP2009130389A - Communication apparatus, tuning frequency adjustment method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus capable of stabilizing a communication between the communication apparatus with a reader/writer function and an information processing terminal, on which a non-contact type IC chip is mounted, and to provide a tuning frequency adjustment method and a program. <P>SOLUTION: The communication apparatus capable of performing a non-contact communication with the information processing terminal, on which the IC chip is mounted, by transmitting carrier signals and performing a load modulation by the IC chip received with the carrier signals comprises: a reference clock generation part for generating the reference clock signals of a fixed cycle; a communication antenna for transmitting the carrier signals of a prescribed frequency corresponding to the reference clock signals, resonating response signals corresponding to the load modulation by a prescribed tuning frequency and receiving them; and a tuning frequency control part for adjusting the prescribed tuning frequency of the communication antenna on the basis of the phase change to the reference clock signals of the carrier signals in the communication antenna. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication device, a tuning frequency adjustment method, and a program.

  In recent years, reader / writers (or communication devices having a reader / writer function) such as non-contact IC (Integrated Circuit) cards, RFID (Radio Frequency Identification) tags, and mobile phones equipped with non-contact IC chips are not used. Information processing terminals that can communicate in a contact manner have become widespread.

  A reader / writer and an information processing terminal such as an IC card or a mobile phone use a magnetic field (carrier wave) of a specific frequency such as 13.56 MHz for communication. Specifically, the reader / writer transmits a carrier wave carrying a carrier wave signal, and an information processing terminal such as an IC card that has received the carrier wave by an antenna returns a response signal to the carrier wave signal received by load modulation, whereby the reader / writer / Writer and information processing terminal can communicate.

  In addition, an information processing terminal capable of communicating in a contactless manner with the reader / writer as described above includes a tamper-resistant IC chip, so that, for example, transmission / reception of data such as electronic money where data tampering is a problem Updates can be done safely. Therefore, the provision of various services using an information processing terminal equipped with an IC chip capable of non-contact communication with the reader / writer as described above is socially spreading. With the spread of service provision, information processing terminals equipped with non-contact IC chips such as IC cards and mobile phones are becoming more popular.

  Under such circumstances, various techniques for stabilizing communication between the reader / writer and the information processing terminal equipped with the non-contact IC chip have been developed. For example, Patent Literature 1 and Patent Literature 2 can be cited as techniques for shifting the frequency to be tuned by estimating the communication distance. Further, as a technique for determining the difficulty of detecting a modulation component and weakening the carrier wave according to the determination result, for example, Patent Document 3 is cited. Furthermore, as a technique for switching the output impedance in accordance with the passage of time when no response is received, for example, Patent Document 4 can be cited.

JP 2006-279813 A JP 2006-238398 A JP 2007-74153 A JP 2004-240716 A

[First problem]
Information processing terminal (hereinafter referred to as “IC chip-equipped terminal”) equipped with a reader / writer or a communication device having a reader / writer function (hereinafter referred to as “communication device”) and a non-contact IC chip such as an IC card or a mobile phone. ")", Since communication is performed using a magnetic field (carrier wave), the closer the communication distance is, the greater the energy of the magnetic field and the more stable communication can be expected. However, in practice, communication may not be performed even when the communication distance between the communication device and the IC chip mounted terminal is short (that is, within the communicable range). This occurs when the communication device cannot receive the response signal transmitted from the IC chip-equipped terminal and cannot demodulate it because the state change before and after the load modulation in the IC chip-equipped terminal is not captured. sell.

  Here, the conventional technique for estimating the communication distance and shifting the tuning frequency merely shifts the tuning frequency by estimating the communication distance. Therefore, for example, when the point where communication cannot be performed shifts due to the antenna size or the number of windings used for communication (that is, when the point where communication cannot be performed is not constant), the frequency to be tuned by estimating the communication distance is shifted. Even if the conventional technology is used, stabilization of communication cannot be expected.

  In addition, the technology that determines the difficulty of detecting the modulation component and weakens the carrier wave according to the determination result has to deliberately weaken the carrier wave used for communication in order to avoid points where communication cannot be performed. I can't expect it. In addition, the technique for determining the difficulty of detecting the modulation component and weakening the carrier wave according to the determination result cannot sufficiently avoid the point where communication cannot be performed unless the auxiliary antenna is provided. Therefore, even if a technique for determining the difficulty of detecting the modulation component and weakening the carrier according to the determination result is used, stabilization of communication cannot be expected.

  Furthermore, the conventional technique for switching the output impedance with the passage of time when no response is received merely switches the output impedance in order to avoid a point where communication cannot be performed. Therefore, since the switched output impedance is not necessarily an output impedance suitable for communication, stabilization of communication can be expected even if the conventional technique of switching the output impedance over time when no response is received is used. Absent.

  Therefore, the conventional technology for stabilizing communication between the reader / writer and the information processing terminal cannot solve the problem that communication cannot be performed within the communicable range.

[Second problem]
The communication device includes a resonance circuit including an antenna (inductor) and a capacitor, and efficiently outputs a carrier wave (magnetic field) to the outside by resonating with the output frequency of the carrier wave. Further, for example, an IC chip included in an IC chip mounting terminal such as an IC card or a mobile phone can be driven by obtaining power from a carrier wave transmitted from a communication device. However, when the coupling between the antenna of the communication device and the antenna of the IC chip mounting terminal becomes strong by bringing the IC chip mounting terminal closer to the communication device, the resonance frequency deviates from the output frequency due to the inductor component and the capacitance component of the IC chip mounting terminal. There is a case.

  When the resonance frequency deviates from the output frequency of the carrier wave, the output efficiency of the carrier wave of the communication device is deteriorated. At this time, since the antenna of the communication device and the antenna of the IC chip mounted terminal are in a strong state, the antenna of the communication device and the antenna of the IC chip mounted terminal are in a state similar to the state in which the transformer is coupled. Therefore, the communication device cannot supply sufficient power to the IC chip-equipped terminal when the resonance frequency deviates from the output frequency of the carrier wave. In the above case, the IC chip-equipped terminal cannot obtain sufficient power for driving, and thus stabilization of communication cannot be expected.

  Here, the conventional technique for estimating the communication distance and shifting the frequency to be tuned is merely shifting the tuning frequency, and the conventional technique for switching the output impedance over time when a response is not received is The output impedance is simply switched. Therefore, there is a high possibility that the resonance frequency will deviate from the output frequency of the carrier wave, and the conventional technique for estimating the communication distance and shifting the frequency to be tuned, or the conventional switching the output impedance in response to the passage of time when no response is received. Regardless of which technology is used, stabilization of communication cannot be expected.

  In addition, since the technology for determining the difficulty of detecting the modulation component and weakening the carrier wave according to the determination result intentionally weakens the carrier wave, it is not desirable to supply sufficient power to the IC chip mounted terminal. Communication cannot be stabilized.

  Therefore, the conventional technology for stabilizing communication between the reader / writer and the information processing terminal cannot solve the problem when the resonance frequency deviates from the output frequency of the carrier wave.

  The present invention has been made in view of the above problems, and an object of the present invention is to perform communication between a communication device having a reader / writer function and an information processing terminal equipped with a non-contact IC chip. It is an object of the present invention to provide a new and improved communication device, tuning frequency adjustment method, and program that can be stabilized.

  In order to achieve the above object, according to a first aspect of the present invention, an information processing terminal on which the IC chip is mounted by transmitting a carrier wave signal and performing load modulation on the IC chip that has received the carrier wave signal. A communication device capable of non-contact communication, a reference clock generation unit that generates a reference clock signal having a constant period, a carrier wave signal having a predetermined frequency corresponding to the reference clock signal, and a response signal corresponding to the load modulation A communication antenna that resonates with a predetermined tuning frequency and a tuning frequency control unit that adjusts the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal with respect to the reference clock signal in the communication antenna Is provided.

  With this configuration, communication between a communication device having a reader / writer function and an information processing terminal equipped with a non-contact IC chip can be stabilized.

  Further, the tuning frequency control unit is based on the real clock extraction unit that extracts the real clock signal from the voltage excited in the communication antenna by receiving the response signal, the real clock signal, and the reference clock signal. A phase determination unit that determines the advance / delay of the phase of the actual clock signal with respect to the reference clock signal, and an adjustment signal that adjusts the predetermined tuning frequency of the communication antenna according to the determination result of the phase determination unit And an adjustment signal output unit.

  With this configuration, the tuning frequency (resonance frequency) of the communication antenna is adjusted to match the output frequency of the carrier wave based on the phase advance / delay of the actual clock signal based on the voltage excited in the communication antenna with respect to the reference clock signal. Can do.

  The tuning frequency control unit further includes a phase shift amount determination unit that determines a phase shift amount of the real clock signal with respect to the reference clock signal based on the real clock signal and the reference clock signal. The adjustment signal output unit may output an adjustment signal for adjusting the predetermined tuning frequency of the communication antenna according to the determination result of the phase determination unit and the determination result of the phase shift amount determination unit.

  With this configuration, the tuning frequency (resonance frequency) of the communication antenna is adjusted to the output frequency of the carrier wave based on the phase advance / delay of the actual clock signal based on the voltage excited in the communication antenna and the phase shift amount. Can be adjusted in the direction.

  The phase shift amount determination unit includes an exclusive OR operation unit that outputs an exclusive OR based on the real clock signal and the reference clock signal, and a phase shift amount according to the exclusive OR. And a phase shift amount measuring unit for measuring.

  With this configuration, it is possible to determine the phase shift amount of the actual clock signal based on the voltage excited in the communication antenna with respect to the reference clock signal.

  The tuning frequency control unit further includes a frequency dividing unit that divides the real clock signal extracted by the real clock extraction unit and the reference clock signal generated by the reference clock generation unit, and the phase determination unit includes The real clock signal and the reference clock signal that have been frequency-divided by the frequency divider may be input.

  With this configuration, the difference in duty between the actual clock signal output from the actual clock extraction unit and the reference clock signal output from the reference clock generation unit can be reduced.

  The tuning frequency control unit includes a phase shift amount determination unit that determines a phase shift amount of the real clock signal with respect to the reference clock signal based on the real clock signal and the reference clock signal, and the reference clock. The phase when the predetermined frequency of the carrier wave signal according to the signal matches the tuning frequency is stored as a reference phase, and the reference phase, the determination result of the phase determination unit, and the determination result of the phase shift amount determination unit are stored in the reference phase. Based on the reference phase of the actual clock signal with respect to the reference phase, and a reference comparator for determining the amount of phase shift, the adjustment signal output unit according to the determination result of the reference comparator An adjustment signal for adjusting the predetermined tuning frequency of the communication antenna may be output.

  With this configuration, it is possible to adjust the tuning frequency (resonance frequency) of the communication antenna while canceling the influence of signal delay caused by wiring or the like.

  In addition, the communication antenna may include an inductor having a predetermined inductance and a capacitance variable unit that varies a capacitance according to an adjustment signal output from the tuning frequency control unit.

  With this configuration, the tuning frequency (resonance frequency) of the communication antenna can be adjusted.

  In addition, the communication antenna may include a capacitor having a predetermined capacitance and an inductance variable unit whose inductance varies according to an adjustment signal output from the tuning frequency control unit.

  With this configuration, the tuning frequency (resonance frequency) of the communication antenna can be adjusted.

  The communication device may be a reader / writer.

  The communication device may be a portable communication device.

  In order to achieve the above object, according to a second aspect of the present invention, an information processing device in which the IC chip is mounted by transmitting a carrier wave signal and performing load modulation by the IC chip receiving the carrier wave signal. A tuning frequency adjustment method in a communication device including a communication antenna capable of receiving a response signal transmitted from a terminal, the step of generating a reference clock signal having a fixed period, and the IC chip that has received the carrier signal transmitted from the IC chip Resonating and receiving the response signal at a predetermined tuning frequency, and adjusting the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal with respect to the reference clock signal at the communication antenna. A tuning frequency adjustment method is provided.

  By using this method, it is possible to stabilize communication between a communication device having a reader / writer function and an information processing terminal equipped with a non-contact IC chip.

  In order to achieve the above object, according to a third aspect of the present invention, an information processing device on which the IC chip is mounted by transmitting a carrier wave signal and performing load modulation on the IC chip that has received the carrier wave signal. A program that can be used in a communication device including a communication antenna capable of receiving a response signal transmitted from a terminal, the step of generating a reference clock signal having a constant period, and a transmission from the IC chip that has received the carrier signal Receiving the response signal resonated at a predetermined tuning frequency, and adjusting the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal with respect to the reference clock signal at the communication antenna. A program for causing a computer to execute is provided.

  Such a program can stabilize communication between a communication apparatus having a reader / writer function and an information processing terminal equipped with a non-contact IC chip.

  According to the present invention, it is possible to stabilize communication between a communication device having a reader / writer function and an information processing terminal equipped with a non-contact IC chip.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  Before describing a communication apparatus (communication apparatus having a reader / writer function) according to an embodiment of the present invention, first, a communication apparatus having a conventional reader / writer function will be described. In the following, a reader / writer will be described as an example of a communication apparatus having a reader / writer function.

(Conventional communication device)
FIG. 1 is a block diagram showing a conventional communication apparatus (reader / writer 20). FIG. 1 also shows a conventional IC chip-equipped terminal 10 including an IC chip 12 that can transmit a response signal by load modulation.

  Referring to FIG. 1, the conventional reader / writer 20 includes a communication antenna 22, a reference clock generation unit 24, a transmission unit 26, a demodulation unit 28, and a data processing unit 30. Further, the reader / writer 20 may include a control unit (not shown) configured by an MPU (Micro Processing Unit) or the like and controlling the reader / writer 20 as a whole.

  For example, the communication antenna 22 includes a resonance circuit including a coil L0 having a predetermined inductance and a capacitor C0 having a predetermined capacitance. With the above configuration, the communication antenna 22 can transmit a carrier wave signal as a transmission signal and receive a response signal transmitted from the IC chip mounted terminal 10.

  The reference clock generation unit 24 can generate a reference clock signal (for example, a 13.56 MHz clock signal) that serves as a reference for the frequency of the carrier wave and can be used as a processing clock in the data processing unit 30.

  The transmission unit 26 can be configured by a transmission circuit that transmits a carrier wave signal based on the reference clock signal generated by the reference clock generation unit 24 and the input from the data processing unit 30.

  The demodulator 28 envelope-detects the amplitude change of the voltage at the antenna end of the communication antenna 22 caused by the voltage excited in the communication antenna 22 by load modulation in the IC chip mounted terminal 10, and binarizes the detected signal. Therefore, the demodulator 28 can demodulate the response data corresponding to the response signal transmitted from the IC chip mounted terminal 10 by the change in the amplitude of the voltage at the communication antenna 22.

  The data processing unit 30 processes the response data demodulated by the demodulation unit 28. The data processing unit 30 can also generate a new carrier signal in accordance with the above processing.

  The conventional reader / writer 20 transmits a carrier wave signal with the above-described configuration, and also receives a received response using a change in amplitude of a voltage generated in the communication antenna 22 by a response signal transmitted from the IC chip-mounted terminal 10. Response data can be demodulated from the signal.

(Problems with conventional communication devices)
[First problem]
However, the conventional reader / writer 20 may not be able to communicate within the communicable range as described above. Then, next, the problem in the conventional communication apparatus is demonstrated.

  FIG. 2 is a first explanatory diagram for explaining a problem in the conventional communication apparatus (reader / writer 20). When load modulation is not performed in the IC chip-mounted terminal (load modulation OFF) and the IC chip When the load modulation is performed in the mounted terminal (load modulation ON), the amplitude of the voltage at the communication antenna is shown. FIG. 3 is a second explanatory diagram for explaining a problem in the conventional communication device, and shows the correct answer rate of the response data obtained by demodulating the response signal transmitted from the IC chip mounted terminal in the communication device. .

  Referring to FIG. 2, the voltage at the communication antenna 22 is measured when load modulation is not performed in the IC chip-equipped terminal 10 (load modulation OFF) and when load modulation is performed in the IC chip-equipped terminal 10 (load modulation). ON). This is because the IC chip mounted terminal 10 generates a demagnetizing field in the opposite direction to the magnetic field transmitted by the reader / writer 20 when the IC chip mounted terminal 10 performs load modulation (transmission of a response signal from the IC chip mounted terminal 10). This is because the communication antenna 22 receives the demagnetizing field.

  In the conventional reader / writer 20, as described above, the communication antenna 22 is configured by a resonance circuit, and reception is performed using the change in the amplitude of the voltage generated in the communication antenna 22 by ON / OFF of load modulation in the IC chip mounting terminal 10. The response data is demodulated from the response signal. However, as shown in FIG. 2A, the voltage generated in the communication antenna 22 may not change before and after the load modulation is turned OFF and ON in the IC chip mounting terminal 10. Here, the carrier wave transmitted by the reader / writer 20 is, for example, a predetermined frequency such as 13.56 MHz (hereinafter, the predetermined frequency of the carrier wave output by the conventional reader / writer 20 and the communication device according to the embodiment of the present invention is “ It is referred to as “output carrier frequency”.) Although it has fc, it may not be resonated at the output carrier frequency due to various factors (that is, the output carrier frequency fc and the resonance frequency f0 for reception may be shifted). Note that, as the above factors, for example, the antenna size and the number of turns of the communication antenna of the reader / writer 20 and the communication chip 10 of the IC chip mounting terminal 10, or the communication antenna of the reader / writer 20 and the communication antenna of the IC chip mounting terminal 10 The change in the coupling coefficient due to the distance between the antennas.

  In the above case, the reader / writer 20 cannot demodulate even though the response signal transmitted from the IC chip mounted terminal 10 is received. Therefore, as shown in FIG. 3, even if the communication distance between the IC chip-equipped terminal 10 and the reader / writer 20 is short, the demodulated response data has a region where the correct answer rate is extremely low (hereinafter, “communication impossible region”). ") Is born. Here, the distance a shown in FIG. 3 is a communication distance between the IC chip mounting terminal 10 and the reader / writer 20, and shows that the distance a is in the state shown in FIG. .

  As shown in FIG. 2 and FIG. 3, the conventional reader / writer 20 may not be able to demodulate the response signal transmitted from the IC chip-equipped terminal 10, so that a communication impossible area occurs even within the communicable range. End up. Therefore, the conventional reader / writer 20 cannot stabilize the communication with the IC chip mounted terminal 10 by eliminating the communication disabled area.

[Second problem]
Further, in the conventional reader / writer 20, when the coupling between the communication antenna 22 of the conventional reader / writer 20 and the antenna of the IC chip mounted terminal 10 becomes strong as described above, for example, the inductor component and capacitance of the IC chip mounted terminal 10 are increased. Depending on the component, the resonance frequency f0 may deviate from the output carrier frequency fc (for example, 13.56 MHz). In the conventional reader / writer 20, since no consideration is given to the difference between the resonance frequency f0 and the output carrier frequency fc, the conventional reader / writer 20 can supply sufficient power to the IC chip mounted terminal. There are cases where it is not possible. In particular, when the power supply voltage for transmitting a carrier wave is low, such as when the conventional reader / writer 20 is a portable communication device having a reader / writer function such as a mobile phone, it is sufficient for an IC chip mounted terminal. The possibility that power cannot be supplied is further increased. Therefore, the conventional reader / writer 20 cannot stabilize the communication with the IC chip mounted terminal 10.

(Problem solving approach according to embodiments of the present invention)
As described above, in the conventional reader / writer 20, communication may not be performed (or communication may not be stabilized) due to the first problem or the second problem. Therefore, next, a problem solving approach according to an embodiment of the present invention capable of solving the first problem and the second problem will be described.

  FIG. 4 is an explanatory diagram for explaining a problem solving approach according to an embodiment of the present invention. FIG. 4A shows the voltage amplitude in the communication antenna when load modulation is not performed in the IC chip mounted terminal (load modulation OFF). FIG. 4B shows the phase of the voltage at the communication antenna when load modulation is not performed in the IC chip mounted terminal (load modulation OFF).

  4A and 4B, it can be seen that the amplitude of the voltage becomes maximum at the resonance frequency f0 (FIG. 4A), and the phase of the voltage at that time is 0 degrees (FIG. 4). (B)). Further, when the resonance frequency deviates from the output carrier frequency, the phase of the antenna end excitation voltage with respect to the output carrier frequency is greater than 0 degree (phase advance), and the phase is less than 0 degree (phase delay). Can be divided into That is, if the phase advance or phase lag is detected and the resonance frequency f0 is adjusted so that the phase becomes 0 degree, the deviation between the resonance frequency f0 and the output carrier frequency fc can be eliminated. Here, if there is no deviation between the resonance frequency f0 and the output carrier frequency fc (or if the deviation is made smaller), communication will not be performed in A corresponding to the communication disabled area shown in FIG. Also, the output efficiency of the carrier wave does not deteriorate.

  Therefore, the communication apparatus according to the embodiment of the present invention solves the first problem and the second problem by detecting the phase advance or phase lag and adjusting the resonance frequency f0 (tuning frequency). Communication with the on-board terminal can be stabilized. Hereinafter, the communication apparatus according to the embodiment of the present invention capable of realizing the above problem solving approach will be described more specifically. Hereinafter, a reader / writer will be described as an example of the communication apparatus according to the embodiment of the present invention. Needless to say, the communication device according to the embodiment of the present invention is not limited to the reader / writer.

(First embodiment)
FIG. 5 is a block diagram showing the reader / writer 150 according to the first embodiment of the present invention. FIG. 5 also shows an IC chip mounting terminal 100 including an IC chip 102 that can transmit a response signal by load modulation.

  Referring to FIG. 5, the reader / writer 150 includes a communication antenna 152, a reference clock generation unit 154, a transmission unit 156, a demodulation unit 158, a tuning frequency control unit 160, and a data processing unit 162.

  The reader / writer 150 is configured by an MPU or the like, and a control unit (not shown) that controls the reader / writer 150 as a whole, or a ROM (program that is used by the control unit and control data such as calculation parameters) ( Read Only Memory (not shown), RAM (Random Access Memory; not shown) that primarily stores programs executed by the control unit, and registers (register; not shown) that hold calculation results and execution states in the control unit ), An encryption circuit for encrypting communication (not shown), an application used in the reader / writer 150, a storage unit (not shown) capable of storing data, etc., connected to other circuits, devices, etc. An interface (not shown) or the like may be provided. The reader / writer 150 connects, for example, the data processing unit 162 and each of the above-described constituent elements and between the above-described constituent elements via a bus as a data transmission path.

  Here, examples of the storage unit (not shown) include a magnetic recording medium such as a hard disk and a non-volatile memory such as a flash memory. I can't. Examples of the interface include a UART (Universal Asynchronous Receiver Transmitter), but are not limited to the above.

For example, the communication antenna 152 includes a resonance circuit including a coil L1 (inductor) having a predetermined inductance and a capacitance variable circuit C (capacitance variable unit) whose capacitance is variable. The capacitance variable circuit C varies the capacitance according to an adjustment signal output from a tuning frequency control unit 160 described later. Here, examples of the capacitance variable circuit C include the following configurations (a) and (b), but the capacitance variable circuit C according to the embodiment of the present invention includes the following (a), Needless to say, the configuration is not limited to (b).
(A) Varicap (b) A circuit comprising a capacitor having a predetermined capacitance and a switch element in parallel, and switching the capacitance digitally

  With the above configuration, the communication antenna 152 can transmit a carrier wave signal as a transmission signal and receive a response signal transmitted from the IC chip mounted terminal 100 by load modulation.

  The reference clock generation unit 154 generates a reference clock signal (for example, a 13.56 MHz clock signal) that serves as a reference for the frequency of the carrier wave and can be used as a processing clock in the data processing unit 162. Here, the reference clock generation unit 154 can generate a reference clock signal by including, for example, a crystal and an oscillator. The reader / writer 150 can also use the reference clock signal generated by the reference clock generation unit 154 as an internal clock of the reader / writer 150. For example, the data processing unit 162 (described later) can use the reference clock signal as a processing clock.

  The transmission unit 156 transmits the carrier wave signal from the communication antenna 152 based on the reference clock signal generated by the reference clock generation unit 154 and the input from the data processing unit 162 (described later). The transmission unit 156 includes, for example, a modulation circuit (not shown) that performs ASK modulation (Amplitude Shift Keying) based on the carrier signal transmitted from the data processing unit 162, and an amplification circuit (not shown) that amplifies the output of the modulation circuit. ).

  Demodulation section 158 envelope-detects the change in voltage amplitude at the antenna end of communication antenna 152 and binarizes the detected signal. That is, the demodulating unit 158 demodulates the response data using a voltage amplitude change caused by load modulation in the IC chip mounting terminal 100 as shown in FIG. Here, the demodulator 158 includes, for example, a detection circuit (not shown) that detects the voltage at the antenna end of the communication antenna 152, and a binarized response between a high level and a low level from the detected voltage. A binarization circuit (not shown) for outputting data can be used.

  The tuning frequency control unit 160 outputs an adjustment signal for adjusting the capacitance of the capacitance variable circuit C included in the communication antenna 152 based on the phase change of the voltage at the antenna end of the communication antenna 152. The tuning frequency control unit 160 outputs an adjustment signal to adjust the capacitance of the capacitance variable circuit C, thereby correcting a deviation between the resonance frequency f0 of the communication antenna 152 and the output carrier frequency fc, and mounting an IC chip. Communication with the terminal 100 can be stabilized. Hereinafter, the configuration of the tuning frequency control unit 160 will be described.

[Configuration Example of Tuning Frequency Control Unit 160]
FIG. 6 is a block diagram illustrating a configuration example of the tuning frequency control unit 160 according to the first embodiment of the present invention. In FIG. 6, the reference clock generation unit 154 is also shown.

  Referring to FIG. 6, the tuning frequency control unit 160 includes an actual clock extraction circuit 170 (real clock extraction unit), a frequency dividing circuit 172 (frequency dividing unit), a phase determination circuit 174 (phase determination unit), and an adjustment signal. And an output circuit 176 (adjustment signal output unit).

  The actual clock extraction circuit 170 performs clock extraction from the voltage generated at the antenna end of the communication antenna 152 and outputs an actual clock signal RFCK.

  The frequency divider 172 divides the actual clock signal RFCK output from the actual clock extraction circuit 170 by two and the reference clock signal OSCK output from the reference clock generator 154 by two. A second frequency dividing circuit 180. Needless to say, the frequency division in the first frequency divider circuit 178 and the second frequency divider circuit 180 according to the first embodiment of the present invention is not limited to frequency division by two.

  6 shows a configuration in which the tuning frequency control unit 160 includes the frequency dividing circuit 172, the embodiment of the present invention is not limited to the above. For example, the tuning frequency control unit according to the first embodiment of the present invention may be configured without the frequency dividing circuit 172. Here, the frequency dividing circuit 172 reduces the duty difference between the actual clock signal RFCK output from the actual clock extraction circuit 170 and the reference clock signal OSCK output from the reference clock generation unit 154, and more reliably controls the frequency. This is for determining the phase difference.

  The phase determination circuit 174 receives the actual clock signal RFCK and the reference clock signal OSCK divided by the frequency dividing circuit 172, and the phase determination circuit 174 determines the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK. Make a decision and output the decision result. The phase determination circuit 174 is composed of, for example, a D flip-flop 182, and outputs a high level signal (H) as a determination result when the phase of the actual clock signal RFCK is advanced with respect to the reference clock signal OSCK. When the phase of the actual clock signal RFCK is delayed with respect to the reference clock signal OSCK, a low level signal (L) is output as a determination result. Needless to say, the phase determination circuit 174 according to the embodiment of the present invention is not limited to the D flip-flop.

  The adjustment signal output circuit 176 outputs an adjustment signal corresponding to the determination result based on the determination result transmitted from the phase determination circuit 174. For example, the adjustment signal output circuit 176 counts according to the determination result, outputs a digital signal of a predetermined bit according to the count, and converts the output of the counter circuit into a voltage signal. And a D / A converter (Digital to Analog converter) that outputs an adjustment signal as an analog signal corresponding to the output of the signal. Note that the configuration of the adjustment signal output circuit 176 according to the embodiment of the present invention is not limited to the above. For example, an adjustment signal as a digital signal can be output without a D / A converter.

  The adjustment signal output circuit 176 outputs an adjustment signal for reducing the capacitance of the capacitance variable circuit C included in the communication antenna 152 when a low level signal is applied from the phase determination circuit 174. The adjustment signal output circuit 176 outputs an adjustment signal for increasing the capacitance of the capacitance variable circuit C included in the communication antenna 152 when a high level signal is applied from the phase determination circuit 174. To do. Here, a counter circuit (not shown) included in the adjustment signal output circuit 176 increases the count by 1 when a low level signal is applied from the phase determination circuit 174, and the high level is output from the phase determination circuit 174. The adjustment signal output circuit 176 can output the adjustment signal by decrementing the count by 1 when the above signal is voltageated, but the relationship between the count of the counter circuit (not shown) and the adjustment signal Is not limited to the above.

  The tuning frequency control unit 160 determines the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK, for example, with the configuration shown in FIG. 6, and based on the determination result, the resonance frequency f0 ( Tuning frequency) can be adjusted. Therefore, the tuning frequency control unit 160, based on the phase change of the carrier wave signal with respect to the reference clock signal OSCK in the communication antenna 152 caused by reception of the response signal transmitted from the IC chip mounted terminal 100, the resonance frequency f0 ( Tuning frequency) can be adjusted.

[Tuning Frequency Adjustment Method According to First Embodiment]
Here, a tuning frequency adjustment method according to the first embodiment of the present invention will be described. FIG. 7 is a flowchart showing an example of a tuning frequency adjustment method according to the first embodiment of the present invention.

  The reader / writer 150 detects the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK (S100). Here, the reader / writer 150 receives the response signal transmitted from the IC chip 102 of the IC chip mounting terminal 100 by causing the communication antenna 152 to resonate at a predetermined tuning frequency, and based on the voltage excited on the communication antenna 152, the real clock. The signal RFCK can be extracted. The reader / writer 150 can generate the reference clock signal OSCK by including the reference clock generation unit 154.

  When the phase advance / delay is detected in step S100, the reader / writer 150 determines whether or not the phase is advanced (S102). Here, the determination in step S102 can be performed by, for example, the reader / writer 150 including a flip-flop to which the real clock signal RFCK and the reference clock signal OSCK are input and the output of the flip-flop.

  If it is determined in step S102 that the phase is advanced, the reader / writer 150 lowers the tuning frequency (resonance frequency) by one step (S104: tuning frequency control processing). Here, the reader / writer 150 can perform the process of step S104 by applying an adjustment signal corresponding to the determination result of step S102 to the capacitance variable circuit C of the communication antenna 152.

  If it is determined in step S102 that the phase is delayed, the reader / writer 150 increases the tuning frequency (resonance frequency) by one step (S106; tuning frequency control processing). Here, similarly to step S104, the reader / writer 150 applies the adjustment signal according to the determination result of step S102 to the capacitance variable circuit C of the communication antenna 152, thereby performing the process of step S106. it can.

  The reader / writer 150 adjusts the resonance frequency f0 (tuning frequency) of the communication antenna 152 by repeatedly using the tuning frequency adjustment method according to the first embodiment shown in FIG. The deviation between the tuning frequency) and the output carrier frequency fc can be corrected. Therefore, the reader / writer 150 can stabilize communication with the IC chip mounted terminal 100 by using the tuning frequency adjustment method according to the first embodiment shown in FIG.

  With reference to FIG. 5 again, the reader / writer 150 according to the first embodiment will be described. The data processing unit 162 processes the response data demodulated by the demodulation unit 158. Further, the data processing unit 162 can generate a carrier wave signal based on, for example, a processing result obtained by processing the response data or a command from a control unit (not shown) of the reader / writer 150. Then, the data processing unit 162 can output the generated carrier wave signal to the transmission unit 156. The data processing unit 162 can be configured by an arithmetic processing device such as an MPU, for example, but the data processing unit 162 may be capable of processing input data for general purposes. , It may be dedicated for processing the response data.

  As described above, the reader / writer 150 according to the first embodiment of the present invention is generated in the communication antenna 152 including the coil L1 having a predetermined inductance and the capacitance variable circuit C whose capacitance is variable. The actual clock signal RFCK is extracted from the voltage, and the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK is determined. The reader / writer 150 increments or decrements the count one step at a time according to the phase advance / delay determination result, and sets the resonance frequency f0 (tuning frequency) of the communication antenna 152 based on the count value to the output carrier frequency. Adjust in the direction to match fc. Accordingly, the reader / writer 150 outputs the resonance frequency f0 of the communication antenna 152 based on the phase change of the carrier wave signal with respect to the reference clock signal OSCK caused by reception of the response signal transmitted from the IC chip mounted terminal 100. It can be adjusted in the direction to match the carrier frequency fc.

  Further, the reader / writer 150 can detect the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK, and can adjust the resonance frequency f0 of the communication antenna 152 in a direction to match the output carrier frequency fc. Communication in a non-communication area can be avoided, and the output efficiency of the carrier wave can be further increased. Therefore, the reader / writer 150 can solve the first problem and the second problem described above, and can further stabilize the communication with the IC chip mounted terminal 100.

[Modification of Communication Device According to First Embodiment]
In the reader / writer 150 (communication device) according to the first embodiment shown in FIG. 5, the communication antenna 152 includes a coil L1 having a predetermined inductance and a capacitance variable circuit C whose capacitance is variable, and is adjusted. A configuration is shown in which the capacitance is changed according to the signal. However, the communication apparatus according to the first embodiment of the present invention is not limited to the above configuration.

[First Modification]
For example, the communication device according to the modification of the first embodiment includes a capacitor having a predetermined electrostatic capacity in the communication antenna, and an inductance variable circuit (inductance variable unit) whose inductance is variable, and according to the adjustment signal. It is also possible to change the inductance. Even with the above-described configuration, the communication device according to the modification of the first embodiment can adjust the resonance frequency f0 of the communication antenna 152 in a direction to match the output carrier frequency fc. The same effects as those of the reader / writer 150 (communication device) according to the embodiment can be obtained.

  Note that the inductance variable circuit included in the communication antenna of the communication apparatus according to the modification of the first embodiment includes, for example, a loop coil provided with a midpoint tap and a switch that performs switching according to the adjustment signal. It is possible, but not limited to the above.

[Second Modification]
The communication device according to the modification of the first embodiment includes an inductance variable circuit (inductance variable unit) whose inductance is variable, and a capacitance variable circuit (capacitance variable unit) whose capacitance is variable. It is also possible to adjust both capacitance and inductance according to the adjustment signal. Even with the above-described configuration, the communication device according to the modification of the first embodiment can adjust the resonance frequency f0 of the communication antenna 152 in a direction to match the output carrier frequency fc. The same effects as those of the reader / writer 150 (communication device) according to the embodiment can be obtained.

  Although the reader / writer 150 has been described as the communication apparatus according to the first embodiment of the present invention, the first embodiment of the present invention is not limited to such a form. For example, the reader / writer function (that is, The present invention can be applied to a portable communication device such as a mobile phone having a function of mainly transmitting a carrier wave signal, a computer such as a UMPC (Ultra Mobile Personal Computer) having a reader / writer function, and the like.

(Program according to the first embodiment)
The program for causing the communication device according to the first embodiment to function as a computer stabilizes communication between the communication device having the reader / writer function and the information processing terminal equipped with the non-contact IC chip. it can.

(Second Embodiment)
In the communication apparatus (reader / writer 150) according to the first embodiment described above, the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK is determined and counted according to the phase advance / delay determination result. The configuration is shown in which the resonance frequency f0 (tuning frequency) of the communication antenna is adjusted in a direction to match the output carrier frequency fc by increasing and decreasing each step. However, the communication apparatus according to the embodiment of the present invention is not limited to the configuration in which the increment / decrement of the count is performed one step at a time according to the phase advance / delay determination result. Then, next, the communication apparatus which concerns on the 2nd Embodiment of this invention is demonstrated. In the following, a reader / writer will be described as an example of the communication apparatus according to the second embodiment of the present invention.

  A reader / writer (not shown; hereinafter referred to as “reader / writer 250”) according to the second embodiment can have the same configuration as the reader / writer 150 according to the first embodiment described above. However, the configuration and function of the tuning frequency control unit 260 are different from those of the tuning frequency control unit 160 according to the first embodiment. That is, the reader / writer 250 includes a communication antenna 152, a reference clock generation unit 154, a transmission unit 156, a demodulation unit 158, and a data processing unit 162 having the same configuration as the reader / writer 150 according to the first embodiment. And a tuning frequency control unit 260.

  The reader / writer 250 is configured by an MPU or the like, and a control unit (not shown) for controlling the reader / writer 250 as a whole, or a ROM (program for use by the control unit, control data such as calculation parameters, etc.) is recorded. (Not shown), a RAM (not shown) that primarily stores programs executed by the control unit, a register (not shown) that holds calculation results and execution states in the control unit, and a cipher for encrypting communication Circuit (not shown), an application used in the reader / writer 250, a storage unit (not shown) capable of storing data, an interface (not shown) for connecting to other circuits, devices, etc. You may prepare.

  Hereinafter, the configuration of the tuning frequency control unit 260 that is a difference between the reader / writer 250 and the reader / writer 150 according to the first embodiment will be described.

[Configuration Example of Tuning Frequency Control Unit 260]
FIG. 8 is a block diagram illustrating a configuration example of the tuning frequency control unit 260 according to the second embodiment of the present invention. In FIG. 8, the reference clock generation unit 154 is also shown.

  Referring to FIG. 8, the tuning frequency control unit 260 includes a real clock extraction circuit 170 (real clock extraction unit), a frequency division circuit 172 (frequency division unit), a phase determination circuit 174 (phase determination unit), and a phase shift. An amount determination circuit 262 (phase shift amount determination unit) and an adjustment signal output circuit 264 (adjustment signal output unit) are provided.

  Similar to the real clock extraction circuit 170 according to the first embodiment shown in FIG. 6, the real clock extraction circuit 170 performs clock extraction from the voltage generated at the antenna end of the communication antenna 152 and outputs a real clock signal RFCK. .

  Similarly to the frequency divider circuit 172 according to the first embodiment shown in FIG. 6, the frequency divider circuit 172 includes a first frequency divider circuit 178 that divides the actual clock signal RFCK output from the actual clock extraction circuit 170 by two. And a second frequency divider circuit 180 that divides the reference clock signal OSCK output from the reference clock generator 154 by two. Needless to say, the frequency division in the first frequency dividing circuit 178 and the second frequency dividing circuit 180 according to the second embodiment of the present invention is not limited to frequency division by two.

  8 shows a configuration in which the tuning frequency control unit 260 includes the frequency dividing circuit 172, the embodiment of the present invention is not limited to the above. For example, the tuning frequency control unit according to the second embodiment of the present invention may be configured not to include the frequency dividing circuit 172.

  The phase determination circuit 174 receives the actual clock signal RFCK and the reference clock signal OSCK divided by the frequency division circuit 172. The phase determination circuit 174 includes the phase determination circuit 174 according to the first embodiment shown in FIG. Similarly, the phase lead / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK is determined, and the determination result is output. The phase determination circuit 174 is composed of, for example, a D flip-flop 182, and outputs a high level signal (H) as a determination result when the phase of the actual clock signal RFCK is advanced with respect to the reference clock signal OSCK. When the phase of the actual clock signal RFCK is delayed with respect to the reference clock signal OSCK, a low level signal (L) is output as a determination result. Note that the phase determination circuit 174 according to the second embodiment is not limited to the D flip-flop.

  The phase shift amount determination circuit 262 receives the real clock signal RFCK and the reference clock signal OSCK that have been frequency-divided by the frequency divider circuit 172, and the phase shift amount determination circuit 262 receives the signal between the clock signal RFCK and the reference clock signal OSCK. The amount of phase shift is determined. Here, the phase shift amount determination circuit 262 includes, for example, an exclusive OR operation circuit 270 (XOR, exclusive OR operation unit) and a phase shift amount measurement circuit 272 (phase shift amount measurement unit). .

  The exclusive OR operation circuit 270 outputs an exclusive OR of the input real clock signal RFCK and the reference clock signal OSCK. Here, the exclusive OR output from the exclusive OR operation circuit 270 corresponds to the total amount of phase shift between the real clock signal RFCK and the reference clock signal OSCK.

  In addition, the phase shift amount measurement circuit 272 measures and measures the phase shift amount between the clock signal RFCK and the reference clock signal OSCK based on the exclusive OR output from the exclusive OR operation circuit 270. The result (corresponding to the determination result of the phase shift amount determination circuit 262) is output. For example, the phase shift amount measuring circuit 272 can measure the phase shift amount according to how many clocks the exclusive OR corresponds to. Here, for example, the reference clock signal OSCK can be used as the clock used by the phase shift amount measurement circuit 272 for measurement, but is not limited thereto. For example, the phase shift amount measurement circuit 272 may include a crystal or the like to generate a measurement clock and measure the phase shift amount using the measurement clock.

  The adjustment signal output circuit 264 outputs an adjustment signal corresponding to the determination result based on the determination result transmitted from the phase determination circuit 174 and the determination result of the phase shift amount determination circuit 262. Similar to the adjustment signal output circuit 176 according to the first embodiment shown in FIG. 6, the adjustment signal output circuit 264 counts according to the determination result and outputs a digital signal of a predetermined bit corresponding to the count. (Not shown) and a D / A converter (not shown) that converts the output of the counter circuit into a voltage signal and outputs an adjustment signal as an analog signal corresponding to the output of the counter circuit. . The configuration of the adjustment signal output circuit 264 according to the second embodiment is not limited to the above. For example, an adjustment signal as a digital signal can be output without including a D / A converter.

  Here, the determination result transmitted from the phase determination circuit 174 indicates the advance / delay of the phase, and the determination result of the phase shift amount determination circuit 262 indicates the phase shift amount. Therefore, the adjustment signal output circuit 264 determines the increase / decrease of the count based on the determination result transmitted from the phase determination circuit 174, and sets the count value to be increased / decreased based on the determination result transmitted from the phase shift amount determination circuit 262. Can be determined and counted.

[How to determine the count value]
Here, an example of a method for determining the count value in the adjustment signal output circuit 264 according to the second embodiment of the present invention will be described.

(1) First Determination Method The adjustment signal output circuit 264 determines the count value by threshold processing, for example. More specifically, the adjustment signal output circuit 264 compares the determination result transmitted from the phase shift amount determination circuit 262 with a predetermined threshold value, and determines a predetermined count according to the comparison result.

  Here, the adjustment signal output circuit 264 can determine the count value using one threshold value, but is not limited to the above. For example, the adjustment signal output circuit 264 may determine the count value by sequentially applying a plurality of threshold values. it can. The threshold information used by the adjustment signal output circuit 264 to determine the count value can be stored in, for example, a storage unit included in the adjustment signal output circuit 264. Here, as the storage means included in the adjustment signal output circuit 264, for example, EEPROM (Electronically Erasable and Programmable Read Only Memory), flash memory, MRAM (Magnetoresistive Random Access Memory), FeRAM (Ferroelectric Random Access Memory), PRAM (Phase non-volatile memory such as change Random Access Memory), but is not limited to the above. Note that threshold information used by the adjustment signal output circuit 264 to determine the count value is stored in a storage unit (not shown) of the reader / writer 250, and the adjustment signal output circuit 264 stores the storage unit (not shown). ) Can be read as appropriate.

(2) Second Determination Method The adjustment signal output circuit 264 is, for example, a look-up table (Look Up Table) in which a determination result (deviation amount) transmitted from the phase shift amount determination circuit 262 is associated with a count value. ) To determine the count value.

  Here, the lookup table used by the adjustment signal output circuit 264 to determine the count value can be stored in, for example, a storage unit included in the adjustment signal output circuit 264. The lookup table used by the adjustment signal output circuit 264 to determine the count value is stored in a storage unit (not shown) of the reader / writer 250, and the adjustment signal output circuit 264 is stored in the storage unit (not shown). ) Can be read as appropriate.

  The adjustment signal output circuit 264 determines the count value to be increased or decreased based on the determination result transmitted from the phase shift amount determination circuit 262 by using, for example, the first determination method or the second determination method. Can do.

  The adjustment signal output circuit 264 determines the count value as described above. For example, when a low level signal is applied from the phase determination circuit 174, the determination is transmitted from the phase shift amount determination circuit 262. Increase the count according to the result. Further, when a high level signal is applied from the phase determination circuit 174, the adjustment signal output circuit 264 decreases the count according to the determination result transmitted from the phase shift amount determination circuit 262.

  Further, the adjustment signal output circuit 264 responds to the count for reducing the capacitance of the capacitance variable circuit C included in the communication antenna 152 when a low level signal is applied from the phase determination circuit 174. Output adjustment signal. The adjustment signal output circuit 176 responds to the count for increasing the capacitance of the capacitance variable circuit C included in the communication antenna 152 when a high level signal is applied from the phase determination circuit 174. Output adjustment signal.

  The tuning frequency control unit 260 determines, for example, the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK and the amount of phase shift with the configuration shown in FIG. 8, and based on the determination result, the communication antenna The resonance frequency f0 (tuning frequency) of 152 can be adjusted. Therefore, the tuning frequency control unit 260, based on the phase change of the carrier wave signal with respect to the reference clock signal OSCK in the communication antenna 152 caused by reception of the response signal transmitted from the IC chip mounting terminal, the resonance frequency f0 (tuning frequency) of the communication antenna 152 Frequency) can be adjusted.

[Tuning Frequency Adjustment Method According to Second Embodiment]
Here, a tuning frequency adjustment method according to the second embodiment of the present invention will be described. FIG. 9 is a flowchart showing an example of a tuning frequency adjustment method according to the second embodiment of the present invention. FIG. 9 shows a tuning frequency adjustment method when the first determination method is used as the count value determination method.

  The reader / writer 250 detects the advance / delay of the phase of the actual clock signal RFCK relative to the reference clock signal OSCK and the amount of phase shift (S200). Here, as shown in FIG. 8, the reader / writer 250 can detect the phase advance / delay and the phase shift amount by separate components (phase determination circuit 174 and phase shift amount determination circuit 262). However, the present invention is not limited to the above, and may be a single component (for example, the phase determination circuit 174 and the phase shift amount determination circuit 262 may be configured as an integrated circuit).

  When the phase advance / delay and phase shift amount are detected in step S200, the reader / writer 250 determines whether or not the phase is advanced (S202). Here, the determination in step S202 can be performed by, for example, the reader / writer 250 including a flip-flop to which the real clock signal RFCK and the reference clock signal OSCK are input, and output of the flip-flop.

[1] When it is determined that the phase is advanced When it is determined in step S202 that the phase is advanced, the reader / writer 250 determines whether or not the phase shift amount is larger than the first threshold value. (S204; first threshold value determination process).

  If it is determined in step S204 that the phase shift amount is not greater than the first threshold value, the reader / writer 250 lowers the tuning frequency (resonance frequency) by one step (S206; tuning frequency control process). Here, for example, the reader / writer 250 increments the count of the counter circuit included in the adjustment signal output circuit 264, and applies the adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. Thus, the process of step S206 can be performed.

  If it is determined in step S204 that the phase shift amount is larger than the first threshold value, the reader / writer 250 determines whether or not the phase shift amount is larger than the second threshold value (S208; second). Threshold determination process). Here, the second threshold value can be a value larger than the first threshold value used in step S204.

  If it is determined in step S208 that the phase shift amount is not greater than the second threshold value, the reader / writer 250 lowers the tuning frequency (resonance frequency) by several steps (S210; tuning frequency control process). Here, the reader / writer 250, for example, increases the count of the counter circuit included in the adjustment signal output circuit 264 by a predetermined value, and sends the adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. By applying, the process of step S210 can be performed.

  If it is determined in step S208 that the phase shift amount is larger than the second threshold value, the reader / writer 250 lowers the tuning frequency (resonance frequency) more than step S210 (S212; tuning frequency control process). . Here, the reader / writer 250, for example, increases the count of the counter circuit included in the adjustment signal output circuit 264 more than in the case of step S210, and sends the adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. By applying the adjustment signal to step S212, the process of step S212 can be performed.

[2] When it is determined that the phase is delayed When it is determined in step S202 that the phase is delayed, the reader / writer 250 determines that the phase shift amount is less than the first threshold value, as in step S204. It is determined whether or not it is larger (S214; first threshold determination process).

  If it is determined in step S214 that the phase shift amount is not greater than the first threshold, the reader / writer 250 increases the tuning frequency (resonance frequency) by one step (S216; tuning frequency control process). Here, the reader / writer 250, for example, decrements the count of the counter circuit included in the adjustment signal output circuit 264, and applies the adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. Thus, the process of step S216 can be performed.

  If it is determined in step S214 that the phase shift amount is larger than the first threshold value, the reader / writer 250 determines whether the phase shift amount is larger than the second threshold value as in step S208. (S218; second threshold value determination process).

  If it is determined in step S218 that the phase shift amount is not greater than the second threshold, the reader / writer 250 increases the tuning frequency (resonance frequency) by several stages (S220; tuning frequency control process). Here, for example, the reader / writer 250 decrements the count of the counter circuit included in the adjustment signal output circuit 264 by a predetermined value, and sends an adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. By applying, the process of step S220 can be performed.

  If it is determined in step S218 that the phase shift amount is larger than the second threshold, the reader / writer 250 increases the tuning frequency (resonance frequency) to be larger than that in step S220 (S222; tuning frequency control process). . Here, for example, the reader / writer 250 lowers the count of the counter circuit included in the adjustment signal output circuit 264 more than in the case of step S220, and sends the adjustment signal corresponding to the count to the capacitance variable circuit C of the communication antenna 152. By applying the adjustment signal to step S222, the process of step S222 can be performed.

  The reader / writer 250 adjusts the resonance frequency (tuning frequency) of the communication antenna 152 by repeatedly using the tuning frequency adjustment method according to the second embodiment shown in FIG. Frequency) and the output carrier frequency fc can be corrected. Therefore, the reader / writer 250 can stabilize communication with the IC chip mounted terminal by using the tuning frequency adjustment method according to the second embodiment shown in FIG.

  As described above, the reader / writer 250 according to the second embodiment of the present invention basically has the same configuration as the reader / writer 150 according to the first embodiment, and has the coil L1 having a predetermined inductance. The real clock signal RFCK is extracted from the voltage generated in the communication antenna 152 including the capacitance variable circuit C having a variable capacitance, and the phase advance / delay of the real clock signal RFCK with respect to the reference clock signal OSCK is determined. Further, the reader / writer 250 determines the amount of phase shift between the actual clock signal RFCK and the reference clock signal OSCK. The reader / writer 250 determines the increase / decrease of the count according to the determination result of the phase advance / delay, and determines the increase / decrease value of the count according to the determination result of the phase shift amount, thereby counting the increase / decrease value of the count. Increase or decrease. Then, the reader / writer 250 adjusts the resonance frequency f0 (tuning frequency) of the communication antenna 152 in a direction to match the output carrier frequency fc based on the count value. Accordingly, the reader / writer 250 outputs the resonance frequency f0 of the communication antenna 152 based on the phase change of the carrier wave signal with respect to the reference clock signal OSCK generated by the reception of the response signal transmitted from the IC chip mounted terminal as the output carrier wave. It can be adjusted in the direction to match the frequency fc.

  In addition, the reader / writer 250 detects the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK, similarly to the reader / writer 150 according to the first embodiment, and sets the resonance frequency f0 of the communication antenna 152. Since the adjustment can be made in the direction to match the output carrier frequency fc, communication in the non-communication region can be avoided and the output efficiency of the carrier can be further increased. Therefore, the reader / writer 250 can solve the first problem and the second problem described above, and can further stabilize the communication with the IC chip mounted terminal.

[Modification of Communication Device According to Second Embodiment]
In the reader / writer 250 (communication device) according to the second embodiment, the communication antenna 152 includes a coil L1 having a predetermined inductance and a capacitance variable circuit C whose capacitance is variable, and according to an adjustment signal. A configuration for changing the capacitance is shown. However, the communication apparatus according to the second embodiment of the present invention is not limited to the above-described configuration, and may have the same configuration as that of the communication apparatus according to the modified example of the first embodiment described above.

  Although the reader / writer 250 has been described as the communication apparatus according to the second embodiment of the present invention, the second embodiment of the present invention is not limited to such a form. For example, the reader / writer function (that is, The present invention can be applied to a portable communication device such as a cellular phone having a function of mainly transmitting a carrier wave signal, a computer such as a UMPC having a reader / writer function, and the like.

(Program according to the second embodiment)
The program for causing the communication device according to the second embodiment to function as a computer can stabilize communication between the communication device having the reader / writer function and the information processing terminal equipped with the non-contact IC chip. it can.

(Third embodiment)
In the communication apparatus (reader / writer) according to the first and second embodiments described above, the resonance frequency f0 (tuning frequency) of the communication antenna 152 is based on the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK. ) Showed the configuration to adjust. However, for example, even when the phase of the actual clock signal RFCK and the phase of the reference clock signal OSCK coincide with each other due to delay due to wiring or the like, the resonance frequency f0 of the communication antenna 152 and the output carrier frequency fc do not coincide with each other. Can happen. Therefore, a communication apparatus according to the third embodiment of the present invention that can deal with the above case will be described next. In the following, a reader / writer will be described as an example of the communication device according to the third embodiment of the present invention.

  A reader / writer (not shown; hereinafter referred to as “reader / writer 350”) according to the third embodiment can have the same configuration as the reader / writer 150 according to the first embodiment described above. However, the configuration and function of the tuning frequency control unit 360 are different from those of the tuning frequency control unit 160 according to the first embodiment. That is, the reader / writer 350 includes a communication antenna 152, a reference clock generation unit 154, a transmission unit 156, a demodulation unit 158, and a data processing unit 162 that have the same configuration as the reader / writer 150 according to the first embodiment. And a tuning frequency control unit 260.

  The reader / writer 350 is configured by an MPU or the like, and a control unit (not shown) that controls the reader / writer 350 as a whole, or a ROM (program that is used by the control unit, control data such as calculation parameters, etc.) (Not shown), a RAM (not shown) that primarily stores programs executed by the control unit, a register (not shown) that holds calculation results and execution states in the control unit, and a cipher for encrypting communication Circuit (not shown), an application used in the reader / writer 350, a storage unit (not shown) capable of storing data, an interface (not shown) for connecting to other circuits, devices, etc. You may prepare.

  Hereinafter, the configuration of the tuning frequency control unit 360 that is a difference between the reader / writer 350 and the reader / writer 150 according to the first embodiment will be described.

[Configuration Example of Tuning Frequency Control Unit 360]
FIG. 10 is a block diagram illustrating a configuration example of the tuning frequency control unit 360 according to the third embodiment of the present invention. In FIG. 10, the reference clock generation unit 154 is also shown.

  Referring to FIG. 10, the tuning frequency control unit 360 includes a real clock extraction circuit 170 (real clock extraction unit), a frequency division circuit 172 (frequency division unit), a phase determination circuit 174 (phase determination unit), and a phase shift. An amount determination circuit 262 (phase shift amount determination unit), a reference comparison circuit 362 (reference comparison unit), and an adjustment signal output circuit 364 (adjustment signal output unit) are provided.

  Similar to the real clock extraction circuit 170 according to the first embodiment shown in FIG. 6, the real clock extraction circuit 170 performs clock extraction from the voltage generated at the antenna end of the communication antenna 152 and outputs a real clock signal RFCK. .

  Similarly to the frequency divider circuit 172 according to the first embodiment shown in FIG. 6, the frequency divider circuit 172 includes a first frequency divider circuit 178 that divides the actual clock signal RFCK output from the actual clock extraction circuit 170 by two. And a second frequency divider circuit 180 that divides the reference clock signal OSCK output from the reference clock generator 154 by two. Needless to say, the frequency division in the first frequency dividing circuit 178 and the second frequency dividing circuit 180 according to the third embodiment of the present invention is not limited to frequency division by two.

  10 shows a configuration in which the tuning frequency control unit 260 includes the frequency dividing circuit 172, the embodiment of the present invention is not limited to the above. For example, the tuning frequency control unit according to the third embodiment of the present invention may be configured without the frequency dividing circuit 172.

  Similar to the phase determination circuit 174 according to the first embodiment shown in FIG. 6, the phase determination circuit 174 determines the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK and outputs the determination result. The phase determination circuit 174 is composed of, for example, a D flip-flop 182, and outputs a high level signal (H) as a determination result when the phase of the actual clock signal RFCK is advanced with respect to the reference clock signal OSCK. When the phase of the actual clock signal RFCK is delayed with respect to the reference clock signal OSCK, a low level signal (L) is output as a determination result. Note that the phase determination circuit 174 according to the third embodiment is not limited to being configured with a D flip-flop.

  The phase shift amount determination circuit 262 determines the phase shift amount between the clock signal RFCK and the reference clock signal OSCK, similarly to the phase shift amount determination circuit 262 according to the second embodiment shown in FIG. Here, the phase shift amount determination circuit 262 includes, for example, an exclusive OR operation circuit 270 (XOR, exclusive OR operation unit) and a phase shift amount measurement circuit 272 (phase shift amount measurement unit). .

  The reference comparison circuit 362 stores in advance the phase of the reference clock signal OSCK at the point where the resonance frequency f0 of the communication antenna 152 matches the output carrier frequency fc as the reference phase. Here, the reference phase stored in the reference comparison circuit 362 is a phase that is set in order to cancel the influence, for example, by taking into consideration the influence of signal delay caused by wiring or the like in the reader / writer 350. The reference phase includes, for example, the phase of the reference clock OSCK immediately after being output from the reference clock generation unit 154 and the reference clock input to the phase shift amount determination circuit 262 in a state where the communication antenna 152 is removed from the reader / writer 350. It can be determined by comparing with the phase of OSCK. Needless to say, the reference phase determination method according to the embodiment of the present invention is not limited to the above. The reference comparison circuit 362 includes, for example, a register and can store the reference phase in the register, but is not limited thereto.

  Further, the reference comparison circuit 362 determines the phase of the actual clock signal RFCK relative to the reference phase based on the stored reference phase, the determination result transmitted from the phase determination circuit 174, and the determination result of the phase shift amount determination circuit 262. Advance / delay and phase shift amount are determined.

  By providing the reference comparison circuit 362, the reader / writer 350 can cancel the influence of signal delay caused by wiring or the like, and can precisely match the resonance frequency f0 of the communication antenna 152 with the output carrier frequency fc.

  The adjustment signal output circuit 364 outputs an adjustment signal corresponding to the determination result based on the determination result transmitted from the reference comparison circuit 362. Here, the adjustment signal output circuit 364 includes, for example, a counter circuit (not shown) and a D / A converter (not shown), and the adjustment signal output circuit 264 according to the second embodiment shown in FIG. Similarly to the above, an adjustment signal corresponding to the determination result can be output. The configuration of the adjustment signal output circuit 364 according to the third embodiment is not limited to the above. For example, an adjustment signal as a digital signal can be output without including a D / A converter.

  The tuning frequency control unit 360 determines, for example, the phase advance / delay of the actual clock signal RFCK with respect to the reference clock signal OSCK and the amount of phase shift with the configuration shown in FIG. 10, and uses the determination result to determine the actual clock signal. The phase advance / delay with respect to the reference phase of RFCK and the phase shift amount are determined. The tuning frequency control unit 360 can adjust the resonance frequency (tuning frequency) of the communication antenna 152 based on the determination result. Therefore, the tuning frequency control unit 360 is configured to change the resonance frequency (tuning frequency) of the communication antenna 152 based on the phase change of the carrier signal relative to the reference clock signal OSCK in the communication antenna 152 caused by reception of the response signal transmitted from the IC chip mounted terminal. ) Can be adjusted.

[Tuning Frequency Adjustment Method According to Third Embodiment]
Here, a tuning frequency adjustment method according to the third embodiment of the present invention will be described. FIG. 11 is a flowchart showing an example of a tuning frequency adjustment method according to the third embodiment of the present invention. FIG. 11 shows a tuning frequency adjustment method when the first determination method shown in the reader / writer 250 according to the second embodiment is used as the count value determination method.

  The reader / writer 350 detects the phase advance / delay with respect to the reference phase of the actual clock signal RFCK and the phase shift amount (S300). Here, the reader / writer 350 can detect the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK and the amount of phase shift, and perform the process of step S300 by comparing with the reference phase.

  When the phase advance / delay and phase shift amount are detected in step S300, the reader / writer 350 determines whether or not the phase is advanced with respect to the reference phase (S302).

[1] When it is determined that the phase is advanced If it is determined in step S302 that the phase is advanced with respect to the reference phase, the reader / writer 350 has a phase shift amount larger than the first threshold value. Whether or not (S304; first threshold value determination process).

  If it is determined in step S304 that the phase shift amount is not larger than the first threshold, the reader / writer 350, like step S206 of the tuning frequency adjustment method according to the second embodiment shown in FIG. The tuning frequency (resonance frequency) is lowered by one step (S306; tuning frequency control process).

  If it is determined in step S304 that the phase shift amount is larger than the first threshold value, the reader / writer 350, like step S208 of the tuning frequency adjustment method according to the second embodiment shown in FIG. Then, it is determined whether or not the phase shift amount is larger than the second threshold value (S308; second threshold value determination process).

  When it is determined in step S308 that the phase shift amount is not larger than the second threshold, the reader / writer 350, like step S210 of the tuning frequency adjustment method according to the second embodiment shown in FIG. The tuning frequency (resonance frequency) is lowered by several steps (S310; tuning frequency control process).

  If it is determined in step S308 that the phase shift amount is larger than the second threshold value, the reader / writer 350, like step S212 of the tuning frequency adjustment method according to the second embodiment shown in FIG. Then, the tuning frequency (resonance frequency) is greatly decreased from step S310 (S312; tuning frequency control process).

[2] When it is determined that the phase is delayed When it is determined in step S302 that the phase is delayed with respect to the reference phase, the reader / writer 350 determines that the phase shift amount is the same as in step S304. It is determined whether or not it is larger than the first threshold (S314; first threshold determination processing).

  If it is determined in step S314 that the phase shift amount is not greater than the first threshold, the reader / writer 350, like step S216 of the tuning frequency adjustment method according to the second embodiment shown in FIG. The tuning frequency (resonance frequency) is increased by one step (S316; tuning frequency control process).

  If it is determined in step S314 that the phase shift amount is larger than the first threshold, the reader / writer 350 determines whether the phase shift amount is larger than the second threshold as in step S308. (S318; second threshold value determination process).

  If it is determined in step S318 that the phase shift amount is not greater than the second threshold, the reader / writer 350, like step S220 of the tuning frequency adjustment method according to the second embodiment shown in FIG. The tuning frequency (resonance frequency) is increased by several steps (S320; tuning frequency control process).

  If it is determined in step S318 that the phase shift amount is larger than the second threshold value, the reader / writer 350, like step S222 of the tuning frequency adjustment method according to the second embodiment shown in FIG. The tuning frequency (resonance frequency) is increased more than step S320 (S322; tuning frequency control process).

  The reader / writer 350 repeatedly uses the tuning frequency adjustment method according to the third embodiment shown in FIG. 11 to cancel the influence of signal delay caused by wiring and the like, and then the resonance frequency (tuning frequency) of the communication antenna 152. ) To adjust the deviation between the resonance frequency f0 (tuning frequency) of the communication antenna 152 and the output carrier frequency fc. Therefore, the reader / writer 350 can stabilize communication with the IC chip mounted terminal by using the tuning frequency adjustment method according to the third embodiment shown in FIG.

  As described above, the reader / writer 350 according to the third embodiment of the present invention basically has the same configuration as the reader / writer 150 according to the first embodiment, and the coil L1 having a predetermined inductance and The real clock signal RFCK is extracted from the voltage generated in the communication antenna 152 including the capacitance variable circuit C having a variable capacitance, and the phase advance / delay of the real clock signal RFCK with respect to the reference clock signal OSCK is determined. Further, the reader / writer 350 determines the phase shift amount between the actual clock signal RFCK and the reference clock signal OSCK. Further, the reader / writer 350 determines the phase with respect to the reference phase of the actual clock signal RFCK based on the previously stored reference phase and the phase advance / delay and phase shift amount of the actual clock signal RFCK with respect to the reference clock signal OSCK. Lead / lag and phase shift amount are determined. Similar to the reader / writer 250 according to the second embodiment, the reader / writer 350 determines increase / decrease of the count according to the phase advance / delay determination result, and counts according to the phase shift amount determination result. The count is increased or decreased by determining the increase or decrease value. Then, the reader / writer 350 adjusts the resonance frequency f0 (tuning frequency) of the communication antenna 152 in a direction to match the output carrier frequency fc based on the count value. Therefore, the reader / writer 350 outputs the resonance frequency f0 of the communication antenna 152 based on the phase change of the carrier signal in the communication antenna 152 with respect to the reference clock signal OSCK caused by reception of the response signal transmitted from the IC chip mounted terminal as the output carrier wave. It can be adjusted in the direction to match the frequency fc.

  In addition, the reader / writer 350 detects the advance / delay of the phase of the actual clock signal RFCK with respect to the reference clock signal OSCK, similarly to the reader / writer 150 according to the first embodiment, and sets the resonance frequency f0 of the communication antenna 152. Since the adjustment can be made in the direction to match the output carrier frequency fc, communication in the non-communication region can be avoided and the output efficiency of the carrier can be further increased. Therefore, the reader / writer 350 can solve the first problem and the second problem described above, and can further stabilize the communication with the IC chip mounted terminal.

  Further, the reader / writer 350 determines the phase advance / delay and phase shift amount with respect to the reference phase of the actual clock signal RFCK, and matches the resonance frequency f0 of the communication antenna 152 with the output carrier frequency fc based on the determination result. Adjust the direction. Here, the reference phase is a phase that is set in order to cancel the influence of the influence of the signal delay caused by the wiring or the like in the reader / writer 350. Therefore, the reader / writer 350 adjusts the resonance frequency (tuning frequency) of the communication antenna 152 after canceling the influence of the signal delay caused by the wiring or the like, and the resonance frequency f0 (tuning frequency) of the communication antenna 152 and the output carrier wave. Since the deviation from the frequency fc can be corrected, the communication with the IC chip mounted terminal can be further stabilized.

[Modification of Communication Device According to Third Embodiment]
[First Modification]
In the reader / writer 350 (communication device) according to the third embodiment, the communication antenna 152 includes a coil L1 having a predetermined inductance and a capacitance variable circuit C whose capacitance is variable, and according to an adjustment signal. A configuration for changing the capacitance is shown. However, the communication device according to the third embodiment of the present invention is not limited to the above-described configuration, and may have the same configuration as the communication device according to the modified example of the first embodiment described above.

[Second Modification]
In the reader / writer 350 (communication apparatus) according to the third embodiment, the configuration in which the reference phase is stored and used in advance in order to cancel the influence of signal delay caused by wiring or the like is shown. However, the communication apparatus according to the third embodiment of the present invention is not limited to the above configuration. For example, the communication device according to the modified example of the third embodiment includes a delay unit that adjusts the phase of the reference clock OSCK by delaying the reference clock OSCK generated by the reference clock generation unit 154 for a predetermined time, and thereby wiring and the like. It is also possible to cancel the influence of signal delay caused by. Even with the above-described configuration, the communication device according to the modification of the third embodiment can adjust the resonance frequency (tuning frequency) of the communication antenna 152 after canceling the influence of signal delay caused by wiring or the like. Therefore, the same effect as the reader / writer 350 shown in FIG. 10 can be obtained.

  Note that the delay unit included in the communication device according to the modification of the third embodiment can be configured by, for example, a multi-stage buffer or a low-pass filter. Not limited.

[Third Modification]
Furthermore, the communication apparatus according to the modification of the third embodiment can also have a configuration in which the first modification and the second modification according to the modification of the third embodiment are combined.

  Although the reader / writer 350 has been described as a communication apparatus according to the third embodiment of the present invention, the third embodiment of the present invention is not limited to such a form, and for example, a reader / writer function (that is, The present invention can be applied to a portable communication device such as a cellular phone having a function of mainly transmitting a carrier wave signal, a computer such as a UMPC having a reader / writer function, and the like.

(Program according to the third embodiment)
The program for causing the communication device according to the third embodiment to function as a computer can stabilize communication between the communication device having the reader / writer function and the information processing terminal equipped with the non-contact IC chip. it can.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is a block diagram which shows the conventional communication apparatus. It is the 1st explanatory view for explaining the problem in the conventional communication apparatus. It is the 2nd explanatory view for explaining the problem in the conventional communication apparatus. It is explanatory drawing for demonstrating the problem-solving approach which concerns on embodiment of this invention. 1 is a block diagram illustrating a reader / writer according to a first embodiment of the present invention. It is a block diagram which shows the structural example of the tuning frequency control part which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of the tuning frequency adjustment method which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the tuning frequency control part which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows an example of the tuning frequency adjustment method which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structural example of the tuning frequency control part which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows an example of the tuning frequency adjustment method which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

10, 100 IC chip mounted terminal 12, 102 IC chip 20, 150 Reader / writer 22, 152 Communication antenna 24, 154 Reference clock generator 26, 156 Transmitter 28, 158 Demodulator 30, 162 Data processor 160, 260, 360 Tuning Frequency Control Unit 170 Real Clock Extraction Circuit 172 Frequency Dividing Circuit 174 Phase Determination Circuit 176, 264, 364 Adjustment Signal Output Circuit 262 Phase Deviation Amount Determination Circuit 270 Exclusive OR Calculation Circuit 272 Phase Deviation Amount Measurement Circuit 362 Reference Comparison Circuit

Claims (12)

A communication device capable of contactless communication with an information processing terminal equipped with an IC chip by transmitting a carrier wave signal and performing load modulation on the IC chip that has received the carrier wave signal:
A reference clock generator for generating a reference clock signal having a constant period;
A communication antenna that transmits a carrier wave signal having a predetermined frequency corresponding to the reference clock signal and resonates and receives a response signal corresponding to the load modulation at a predetermined tuning frequency;
A tuning frequency control unit that adjusts the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal with respect to the reference clock signal in the communication antenna;
A communication apparatus comprising: The tuning frequency controller is
An actual clock extraction unit that extracts an actual clock signal from a voltage excited in the communication antenna by receiving the response signal;
A phase determination unit that determines a lead / lag of the phase of the real clock signal with respect to the reference clock signal based on the real clock signal and the reference clock signal;
An adjustment signal output unit that outputs an adjustment signal for adjusting the predetermined tuning frequency of the communication antenna according to a determination result of the phase determination unit;
The communication apparatus according to claim 1, further comprising: The tuning frequency control unit further includes a phase shift amount determination unit that determines a phase shift amount of the real clock signal with respect to the reference clock signal based on the real clock signal and the reference clock signal,
The adjustment signal output unit outputs an adjustment signal for adjusting the predetermined tuning frequency of the communication antenna according to a determination result of the phase determination unit and a determination result of the phase shift amount determination unit. The communication device according to claim 2. The phase shift amount determination unit
An exclusive OR operation unit that outputs an exclusive OR based on the real clock signal and the reference clock signal;
A phase shift amount measuring unit that measures the phase shift amount according to the exclusive OR;
The communication apparatus according to claim 3, further comprising: The tuning frequency controller is
A frequency divider that divides the real clock signal extracted by the real clock extractor and the reference clock signal generated by the reference clock generator;
The communication apparatus according to claim 2, wherein the phase determination unit is input with an actual clock signal and a reference clock signal that have been frequency-divided by the frequency division unit. The tuning frequency controller is
A phase shift amount determination unit that determines a phase shift amount of the real clock signal with respect to the reference clock signal based on the real clock signal and the reference clock signal;
The phase when the predetermined frequency of the carrier wave signal corresponding to the reference clock signal matches the tuning frequency is stored as a reference phase, and the reference phase, the determination result of the phase determination unit, and the phase shift amount determination unit A reference comparison unit that determines a phase advance / delay and a phase shift amount with respect to the reference phase of the real clock signal based on a determination result;
Further comprising
The communication apparatus according to claim 2, wherein the adjustment signal output unit outputs an adjustment signal for adjusting the predetermined tuning frequency of the communication antenna according to a determination result of the reference comparison unit. The communication antenna is
An inductor having a predetermined inductance;
A capacitance variable unit that varies a capacitance according to an adjustment signal output from the tuning frequency control unit;
The communication apparatus according to claim 1, further comprising: The communication antenna is
A capacitor having a predetermined capacitance;
An inductance variable unit that varies the inductance in accordance with an adjustment signal output from the tuning frequency control unit;
The communication apparatus according to claim 1, further comprising:   The communication apparatus according to claim 1, wherein the communication apparatus is a reader / writer.   The communication device according to claim 1, wherein the communication device is a portable communication device. Tuning frequency adjustment in a communication apparatus including a communication antenna that can receive a response signal transmitted from an information processing terminal equipped with the IC chip by transmitting a carrier wave signal and performing load modulation on the IC chip that has received the carrier wave signal Method:
Generating a reference clock signal having a constant period;
Receiving the response signal transmitted from the IC chip that has received the carrier signal by resonating at a predetermined tuning frequency;
Adjusting the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal with respect to the reference clock signal at the communication antenna;
A tuning frequency adjustment method comprising: Whether an IC chip that transmits a carrier wave signal and that receives the carrier wave signal performs load modulation to use it for a communication apparatus including a communication antenna that can receive a response signal transmitted from an information processing terminal equipped with the IC chip. Possible programs are:
Generating a reference clock signal having a constant period;
Receiving the response signal transmitted from the IC chip that has received the carrier signal by resonating at a predetermined tuning frequency;
Adjusting the predetermined tuning frequency of the communication antenna based on a phase change of the carrier signal relative to the reference clock signal at the communication antenna;
A program that causes a computer to execute.

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