JP2007281592A - Wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication device in which a wraparound signal from the transmission side included in a received signal can be removed sufficiently. <P>SOLUTION: The wireless communication device comprises a cancel amplitude control unit 62 for suppressing cancel signal supply to a cancel signal synthesizer 52 selectively, a terminator 50 for terminating a received signal input end 64i selectively, a signal strength detector 78, a storage 82 for storing a signal strength detected at the signal strength detector 78, a comparator 80 for comparing a plurality of kinds of signal strength read out from the storage 82, and a controller 72 for controlling the amplitude and the phase of a cancel signal based on the comparison results from the signal strength comparator 80. Since the cancel amplitude control unit 62 suppresses cancel signal, strength of the received signal can be detected accurately; and since the received signal terminator 50 terminates the received signal, strength of the cancel signal can be detected accurately. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of a wireless communication apparatus having a cancel circuit for suppressing a sneak signal from a transmission side.

  2. Description of the Related Art A wireless communication device is known that includes a transmission unit that transmits a predetermined transmission signal from a transmission antenna and a reception unit that receives a reply signal returned in response to the transmission signal by a reception antenna. For example, an RFID (Radio Frequency Identification) system RFID tag communication device (interrogator) that reads information without contact from a small RFID tag (responder) in which predetermined information is stored. This RFID system is capable of reading information stored in a wireless tag by communication with the wireless tag communication device even when the wireless tag is dirty or disposed at an invisible position. Therefore, practical use is expected in various fields such as merchandise management and inspection processes.

  By the way, normally, the wireless tag communication device transmits a predetermined transmission signal (question wave) from the antenna toward the wireless tag, and a reply signal (response wave) returned from the wireless tag that has received the transmission signal. Is received by the antenna, and information is communicated with the wireless tag. However, a strong sneak signal (direct wave) from the transmission side is mixed in the received reply signal, increasing the overall received signal strength. There is a case. As a result, since the allowable input intensity of the amplifier is exceeded, the received signal cannot be sufficiently amplified, and as a result, the return signal component from the wireless tag cannot be sufficiently amplified. There was a problem that it decreased. Therefore, a technique for removing such a sneak signal from the transmission side has been proposed. For example, this is the carrier phase noise suppression circuit described in Patent Document 1. According to this technology, a signal-to-noise ratio is generated by generating a cancel signal having the same carrier component, frequency, and signal strength as the received signal and having an opposite phase, adding the cancel signal to the received signal, and inputting the signal to the receiving circuit. It is said that a large signal can be obtained and reception sensitivity can be improved.

JP-A-10-62518

  However, in order to sufficiently remove the sneak signal included in the received signal by the technique as described above, it is necessary to accurately detect the signal strengths of the received signal and the cancel signal. As a result, it was difficult to accurately detect the signal strength of each signal, and the wraparound signal included in the received signal could not be sufficiently removed. That is, there has been a demand for the development of a wireless communication apparatus that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a wireless communication apparatus capable of sufficiently removing a sneak signal from a transmission side included in a reception signal. .

  In order to achieve such an object, the gist of the present invention is to control a distribution unit that distributes a carrier component of a transmission signal transmitted from a transmitting antenna and an amplitude of the carrier component distributed by the distribution unit. An amplitude control unit, a phase control unit for controlling the phase of the carrier wave component distributed by the distribution unit, and a cancel signal generated from the carrier wave component via the amplitude control unit and the phase control unit by the receiving antenna A wireless communication apparatus comprising a cancel signal combining unit for adding to a received signal received, a cancel signal supply suppressing unit for selectively suppressing supply of a cancel signal to the cancel signal combining unit, and the reception A reception signal termination unit for selectively terminating a reception signal input terminal from the antenna to the cancellation signal synthesis unit, and the cancellation signal, reception signal, or A signal intensity detection unit for detecting the intensity of the combined signal, a storage unit for storing the signal intensity detected by the signal intensity detection unit, and a plurality of types of signal intensities read from the storage unit, And the signal strength detection unit for comparing the signal strength detected by the signal strength detection unit, and the amplitude of the cancellation signal via the amplitude control unit and / or the phase control unit based on the comparison result by the signal strength comparison unit And / or a cancel signal control unit for controlling the phase.

  With this configuration, the cancel signal supply suppressing unit that selectively suppresses the supply of the cancel signal to the cancel signal combining unit, and the reception signal input terminal from the receiving antenna to the cancel signal combining unit are selectively selected. A reception signal termination unit to be terminated, a signal strength detection unit for detecting the strength of the cancellation signal, the reception signal, or a combined signal thereof, a storage unit for storing a signal strength detected by the signal strength detection unit, and The signal intensity comparison unit that compares a plurality of types of signal intensities read from the storage unit with each other or the signal intensity detected by the signal intensity detection unit, and the amplitude based on a comparison result by the signal intensity comparison unit A cancel signal control unit that controls the amplitude and / or phase of the cancel signal via the control unit and / or the phase control unit. Further, the intensity of the received signal can be accurately detected by suppressing the cancel signal by the cancel signal supply suppressing unit, while the intensity of the cancel signal is accurately detected by terminating the received signal by the received signal terminating unit. it can. That is, it is possible to provide a wireless communication apparatus that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  Here, preferably, the reception signal termination unit includes a circuit switching unit that switches a circuit between the reception antenna and a reception signal input terminal, and a termination resistor connected to the circuit switching unit. The circuit switching unit is configured to connect the reception signal input terminal and a termination resistor when detecting the intensity of the cancel signal. In this way, by using the circuit switching unit at the end of the received signal, the signal path at the time of reception and the termination path at the time of termination can be switched in a practical manner.

  Preferably, the reception signal termination unit is a second circuit switching unit that switches a circuit between the reception antenna and the circuit switching unit to the reception antenna side from the circuit switching unit and a termination resistor. And a second termination resistor connected to the second circuit switching unit, and the second circuit switching unit, when detecting the intensity of the cancellation signal, The second terminal resistor is connected. In this way, by dropping the reception antenna to the terminating resistor, the state of the reception antenna can be made the same at the time of control of the cancellation signal and at the time of reception. It is possible to more accurately detect the signal strengths of the received signal and the cancel signal.

  Preferably, the cancel signal supply suppressing unit controls the amplitude of the carrier wave component so that the output from the amplitude control unit is as small as possible when detecting the intensity of the received signal. . In this way, the supply of the cancel signal to the cancel signal combining unit can be suppressed in a practical manner without providing a new configuration.

  Preferably, the cancel signal supply suppressing unit includes a third circuit switching unit that switches a circuit between the amplitude control unit and the cancel signal input terminal, and a third circuit switching unit connected to the third circuit switching unit. 3 is provided to connect the cancel signal input terminal and the third terminal resistance when detecting the intensity of the received signal. According to this configuration, by using the third circuit switching unit, it is possible to suppress the input of the cancel signal to the cancel signal input terminal as much as possible, and to reduce the output from the amplitude control unit. By making it small, reflection to the cancel circuit side can be suppressed.

  Preferably, the transmitting antenna and the receiving antenna are individually provided as separate antennas. In this way, the influence on the transmission side when the cancel signal is controlled can be minimized.

  Preferably, the transmission antenna and the reception antenna are integrally provided as a transmission / reception shared antenna. In this way, the configuration of the apparatus can be made as simple as possible.

  Preferably, when detecting the strength of the cancel signal, a transmission signal having a signal strength smaller than that of the transmission signal transmitted from the transmission antenna for communication with a predetermined communication target is used. It is transmitted from the antenna. In this way, it is possible to prevent unnecessary transmission of a large transmission signal to save power, and to suppress the influence on other stations.

  Preferably, the cancellation signal control unit first suppresses the supply of the cancellation signal to the cancellation signal synthesis unit by the cancellation signal supply suppression unit, and the signal strength detection unit causes the reception signal to be reduced. The intensity is detected and the detection result is stored in the storage unit. Next, the suppression of the supply of the cancel signal to the cancel signal combining unit is released, and the reception signal input unit is terminated by the reception signal termination unit. In this state, the amplitude of the cancellation signal is controlled so that the strength of the cancellation signal detected by the signal strength detection unit is equal to the strength of the reception signal stored in the storage unit. In a state in which the termination of the reception signal input end by the termination unit is canceled, the composite signal of the reception signal and the cancellation signal detected by the signal strength detection unit Strength is used to control the phase of the cancellation signal so as to reduce as much as possible. In this way, the cancel signal can be easily controlled by separately controlling the amplitude and phase of the cancel signal.

  Preferably, the cancellation signal control unit first suppresses the supply of the cancellation signal to the cancellation signal synthesis unit by the cancellation signal supply suppression unit, and the signal strength detection unit causes the reception signal to be reduced. The intensities of the in-phase component and the quadrature component are detected, and the detection results are stored in the storage unit.Then, the suppression of the supply of the cancel signal to the cancel signal combining unit is canceled, and the reception signal termination unit With the received signal input terminal terminated, the in-phase component and quadrature component of the cancellation signal detected by the signal strength detector are respectively in-phase component and quadrature component of the received signal stored in the storage unit. The amplitude and / or phase of the cancel signal is controlled to be equal to the intensity of the cancel signal, and the phase of the cancel signal is 18 After controlling the phase of ° the cancellation signal to be rotated, it is intended to release the end of the reception signal input by the reception signal terminal unit. In this way, by simultaneously controlling the amplitude and phase of the cancel signal, the cancel signal can be controlled in a relatively short time.

  Preferably, the cancellation signal control unit first suppresses the supply of the cancellation signal to the cancellation signal synthesis unit by the cancellation signal supply suppression unit, and the signal strength detection unit causes the reception signal to be reduced. The intensities of the in-phase component and the quadrature component are detected, and the detection results are stored in the storage unit.Then, the suppression of the supply of the cancel signal to the cancel signal combining unit is canceled, and the reception signal termination unit With the reception signal input terminal terminated, the in-phase component and the quadrature component of the cancellation signal detected by the signal strength detection unit are respectively intensities of the in-phase component and the quadrature component of the reception signal stored in the storage unit. Are equal to each other, and the amplitude and / or phase of the cancel signal is controlled so that the sign is opposite, and then the received signal termination unit It is intended to release the end of the reception signal input terminal. In this way, the cancel signal can be controlled in the shortest possible time by simultaneously controlling the amplitude and phase of the cancel signal and eliminating the need for phase rotation.

  Preferably, the cancel signal control unit controls the cancel signal prior to execution of information transmission to a predetermined communication target. In this way, the reception state can be made suitable before communication with the communication target.

  Preferably, the cancel signal control unit controls the cancel signal during execution of information transmission to a predetermined communication target. In this way, the reception state can be made favorable when a reply signal returned from the communication target is received.

  Preferably, the cancel signal is controlled by the cancel signal control unit every time the frequency of the transmission signal is switched. In this way, a sneak signal from the transmission side that changes following the frequency of the transmission signal can be suitably suppressed by a cancel signal that is set every time the frequency is switched.

  Preferably, the cancel signal is controlled by the cancel signal control unit when the intensity of the combined signal of the reception signal and the cancel signal detected by the signal strength detection unit becomes a predetermined value or more. . In this way, it is possible to suitably determine the timing at which the cancellation signal needs to be controlled.

  Preferably, the transmitting antenna is an array antenna composed of a plurality of transmitting antenna elements, and transmission phase control for controlling transmission directivity by controlling the phase of each transmission signal transmitted to each transmitting antenna element. The cancel signal is controlled by the cancel signal control unit when the phase of the array antenna is changed. In this way, a sneak signal from the transmission side that changes following the weight of the array antenna can be suitably suppressed by a cancel signal that is set every time the weight is switched.

  Preferably, as the receiving antenna, an array antenna comprising a plurality of receiving antenna elements and a receiving phase control for controlling the receiving directivity by controlling the phase of each received signal transmitted to each receiving antenna element. The cancel signal is controlled by the cancel signal control unit when the phase of the array antenna is changed. In this way, a sneak signal from the transmission side that changes following the weight of the array antenna can be suitably suppressed by a cancel signal that is set every time the weight is switched.

  Preferably, a homodyne detection circuit is provided as a demodulator for the received signal. In this way, the sneak signal from the transmission side can be suitably suppressed for the homodyne detection circuit that is particularly affected by the sneak signal from the transmission side.

  Preferably, the wireless communication device transmits a predetermined transmission signal to the wireless tag by a transmitting antenna, and transmits a reply signal returned from the wireless tag in response to the transmission signal for the reception. The wireless tag communication device performs communication of information with the wireless tag by receiving the signal through an antenna. In this way, it is possible to suitably suppress the sneak signal from the transmission side regarding the RFID tag communication apparatus that is particularly affected by the sneak signal from the transmission side.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a wireless tag communication system 10 in which the wireless communication apparatus of the present invention is preferably used. The wireless tag communication system 10 includes a wireless tag communication device 12 that is an embodiment of the wireless communication device of the present invention and a single or multiple (single in FIG. 1) wireless communication target of the wireless tag communication device 12. The RFID tag is a so-called RFID (Radio Frequency Identification) system. The RFID tag communication device 12 functions as an interrogator of the RFID system, and the RFID tag 14 functions as a responder. That is, when the interrogation wave F _c (transmission signal) is transmitted from the radio tag communication device 12 toward the radio tag 14, a predetermined information signal (transmission data) is transmitted in the radio tag 14 that has received the interrogation wave F _c. The interrogation wave F _c is modulated by the above and is returned as a response wave F _r (reply signal) to the RFID tag communication apparatus 12, so that information is transmitted between the RFID tag communication apparatus 12 and the RFID tag 14. Communication is performed. The wireless tag communication system 10 is used, for example, for managing articles in a predetermined communication area. The wireless tag 14 is preferably attached to an article to be managed, for example. And are provided integrally.

FIG. 2 is a diagram for explaining the configuration of the RFID circuit element 16 provided in the RFID tag 14. As shown in FIG. 2, the RFID circuit element 16 has an antenna 18 for communicating with the RFID tag communication device 12 and is connected to the antenna 18 from the RFID tag communication device 12. And an IC circuit unit 20 for processing the transmission signal. The IC circuit portion 20, the storage and rectifying section 22 for rectifying the interrogating wave F _c from the radio tag communication apparatus 12 received by the antenna 18, the energy of the interrogation wave rectified F _c by the rectifying section 22 Power supply unit 24, a clock extraction unit 26 that extracts a clock signal from the carrier wave received by the antenna 18 and supplies the clock signal to the control unit 32, and a memory unit that functions as a storage unit that can store a predetermined information signal 28, the modulation / demodulation unit 30 that is connected to the antenna 18 and modulates and demodulates the signal, and the operation of the RFID circuit element 16 is controlled through the rectification unit 22, the clock extraction unit 26, the modulation / demodulation unit 30 and the like. The control part 32 for performing is functionally included. The control unit 32 performs control for storing the predetermined information in the memory unit 28 by communicating with the RFID tag communication device 12, and transmits the interrogation wave F _c received by the antenna 18 in the modulation / demodulation unit 30. executes basic control such as control that reflects back from the antenna 18 as a response wave F _r in terms of modulated based on the information signal stored in the memory unit 28.

FIG. 3 is a diagram illustrating the configuration of the wireless tag communication device 12. As shown in FIG. 3, the wireless tag communication device 12 according to the present embodiment performs information communication with the wireless tag 14 in order to execute at least one of reading and writing of information with respect to the wireless tag 14. is intended, or to output the information signal in the interrogating wave F _c to such a wireless tag 14, to control the intensity of the interrogating wave F _c, that controls the phase and / or amplitude of the cancellation signal to be described later In this way, a central control unit 34 that comprehensively controls the operation of the RFID tag communication device 12 and a carrier generation unit that generates a carrier wave having a predetermined frequency and intensity according to a control signal supplied from the central control unit 34 36, a first distributor 38 that distributes the carrier generated by the carrier generator 36 to the second distributor 40 and the quadrature demodulator 54, and the first distributor 38 A second distributor 40 that distributes the supplied carrier wave to the transmission amplifier 42 and the cancel signal generation unit 46, and an information signal (transmission) supplied from the central control unit 34 to the carrier wave supplied from the second distributor 40 Information) is transmitted from the transmitting antenna 44 as the interrogation wave _Fc to the wireless tag 14, and the phase and / or amplitude of the carrier wave supplied from the second distributor 40 is controlled and canceled. A cancel signal control unit 46 to be output as a signal, a reception antenna 48 for receiving a reply signal returned from the wireless tag 14, and a reception signal input terminal from the reception antenna 48 to the cancel signal combining unit 52 are selected. And the received signal supplied from the receiving antenna 48 via the received signal terminating unit 50 to the received signal terminating unit 50. A cancel signal combining unit 52 for adding a cancel signal supplied from the cell signal generating unit 46, and a reception signal combined with the cancel signal in the cancel signal combining unit 52 is multiplied by the carrier wave supplied from the first distributor 38. Then, a quadrature demodulator 54 that converts the signal into an in-phase component (in-phase signal, I-phase component) and a quadrature component (quadrature signal, Q-phase component) and supplies it to the central control unit 34, and outputs from the quadrature demodulator A first low-pass filter 114 that removes unnecessary harmonic components from the in-phase signal thus generated, a first A / D converter 116 that converts the output of the first low-pass filter 114 into a digital signal, and the orthogonal signal A second low-pass filter 118 that removes unnecessary harmonic components from the quadrature signal output from the demodulator 54, and the output of the second low-pass filter 118 is converted into a digital signal. The second A / D conversion unit 120 is configured to be provided.

  The cancel signal control unit 46 includes a cancel phase control signal D / A conversion unit 56 that converts the cancel phase control signal supplied from the central control unit 34 into analog, and a cancel amplitude control signal supplied from the central control unit 34. Is distributed by the second distributor 40 in accordance with a cancellation phase control signal supplied via a cancellation amplitude control signal D / A conversion unit 58 for analog conversion and a cancellation phase control signal D / A conversion unit 56. A cancel phase control unit 60 that is a variable phase shifter that controls the phase of a carrier wave (carrier wave component) and the cancel phase according to the cancel amplitude control signal supplied via the cancel amplitude control signal D / A converter 58. Cancellation oscillation, which is a variable attenuator that controls the amplitude of the phase-controlled carrier wave output from the control unit 60 And a control unit 62, a. As described above, in the RFID tag communication apparatus 12, the second distributor 40 functions as a distributing unit that distributes the carrier component of the transmission signal transmitted from the transmitting antenna 44, and the second distributor 40 distributes the carrier component. The phase and amplitude of the carrier wave are controlled by the cancel phase control unit 60 and cancel amplitude control unit 62 and output as a cancel signal, and are added to the received signal by the cancel signal combining unit 52.

  The reception signal termination unit 50 includes a circuit switching unit 64 for switching a circuit between the reception antenna 48 and the reception signal input terminal 64i, and a termination resistor 66 of about 50Ω connected to the circuit switching unit 64, for example. , Which is provided. The reception antenna 48 and the termination resistor 66 are connected in parallel to the circuit switching unit 64, and by switching the circuit switching unit 64, the reception antenna 48 and the termination resistor 66 are selectively used as the reception signal. It is configured to be connected to the input terminal 64i. Further, the end of the termination resistor 66 opposite to the circuit switching unit 64 is grounded.

  The central control unit 34 includes a CPU, a ROM, a RAM, and the like, and is a so-called microcomputer system that performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. Control functions such as a cancel signal control unit 72, a signal strength detection unit 78, and a signal strength comparison unit 80 are provided. Further, a storage unit 82 such as a RAM or a hard disk is provided.

The transmission control unit 68 performs transmission control of the interrogation wave F _c (transmission signal) toward the wireless tag 14. For this purpose, a transmission information output unit 70 that outputs transmission information (information signal) for transmission to the wireless tag 14 is included. In the information communication with the wireless tag 14, the transmission control unit 68 outputs a predetermined information signal from the transmission information output unit 70 and supplies it to the transmission amplifier 42, and outputs it from the carrier wave generation unit 36. The frequency and intensity of the carrier wave to be controlled are controlled. Further, by generating only a carrier wave from the carrier wave generating unit 36 without outputting an information signal from the transmission information output unit 70, a carrier wave not including an information signal can be output from the transmitting antenna 44.

  The cancel signal control unit 72 controls a cancel signal generated by the cancel signal generation unit 46. Specifically, the phase of the cancel signal is controlled by supplying a predetermined cancel phase control signal to the cancel phase control unit 60 via the cancel phase control signal D / A conversion unit 56, and the cancel amplitude control is performed. By supplying a predetermined cancel amplitude control signal to the cancel amplitude control unit 62 via the signal D / A conversion unit 58, the phase of the cancel signal is controlled. In order to suitably control the cancel signal, a cancel signal that selectively suppresses supply of the cancel signal to the cancel signal combining unit 52 via the cancel amplitude control unit 62 that functions as a cancel signal supply suppressing unit. A supply suppression control unit 74 and a reception signal termination control unit 76 that selectively terminates a reception signal input terminal 64i from the reception antenna 48 to the cancel signal synthesis unit 52 via the reception signal termination unit 50; Contains.

  Specifically, the cancel signal supply suppression control unit 74 selectively suppresses the supply of the cancel signal to the cancel signal synthesis unit 52 via the cancel amplitude control unit 62 that is a variable attenuator. That is, the cancel amplitude control signal is changed so that the output from the cancel amplitude control unit 62 is as small as possible, thereby suppressing the supply of the cancel signal to the cancel signal combining unit 52, while the cancel amplitude is reduced. The cancel signal is supplied to the cancel signal combining unit 52 by setting the output from the control unit 62 to a necessary and sufficient level. That is, in the present embodiment, the cancel amplitude control unit 62 functions as a cancel signal supply suppressing unit that selectively suppresses supply of the cancel signal to the cancel signal combining unit 52. Further, the reception signal termination control unit 76 specifically connects the reception signal input terminal 64i and the termination resistor 66 by the circuit switching unit 64 to connect the cancellation signal synthesis unit 52 from the reception antenna 48. The reception signal input terminal 64i is terminated, and the reception signal input terminal 64i and the reception antenna 48 are connected by the circuit switching unit 64, whereby the reception signal is transmitted from the reception antenna 48 to the cancel signal synthesis unit 52. Is entered.

  The signal strength detector 78 detects the signal strength input to the central controller 34. Specifically, the cancel signal generated by the cancel signal generation unit 46, the reception signal received by the reception antenna 48, or the combination of the cancel signal and the reception signal synthesized by the cancel signal synthesis unit 52 Detect signal strength. In the RFID tag communication apparatus 12 of the present embodiment, the signals input to the central control unit 34 are all converted into in-phase signals and quadrature signals by the quadrature demodulation unit 54, so that the signal strength The detection unit 78 detects the intensity of the signal or the demodulation result converted into the in-phase signal and the quadrature signal by the quadrature demodulation unit 54. This detection mode may be to detect the intensities of the in-phase signal and the quadrature signal, or to detect the sum of the squares of the in-phase signal and the quadrature signal as the intensity of the signal itself. Also good. The storage unit 82 stores a plurality of types of signal intensities detected by the signal intensity detection unit 78, and the signal intensity comparison unit 80 reads a plurality of signal intensities read from the storage unit 82. The signal strengths of the types are compared, and the comparison result is supplied to the cancel signal control unit 72.

  The cancel signal supply suppression control unit 74 preferably suppresses the supply of the cancel signal to the cancel signal combining unit 52 when detecting the strength of the received signal received by the receiving antenna 48. That is, when the signal strength of the received signal received by the receiving antenna 48 is detected by the signal strength detector 78, the output from the cancel amplitude controller 62 is reduced as much as possible. Controls the amplitude of the cancel signal. In this way, the strength of the received signal received by the receiving antenna 48 can be accurately detected by the signal strength detector 78.

  Further, the reception signal termination control unit 76 preferably receives a reception signal input terminal 64i from the reception antenna 48 to the cancellation signal combining unit 52 when detecting the intensity of the cancellation signal generated by the cancellation signal generation unit 46. Terminate. That is, when the signal strength of the cancel signal generated by the cancel signal generator 46 is detected by the signal strength detector 78, the circuit is connected to connect the reception signal input terminal 64i and the termination resistor 66. The switching unit 64 is controlled. In this way, the intensity of the cancel signal generated by the cancel signal generator 46 can be accurately detected by the signal intensity detector 78.

In addition, the transmission control unit 68 preferably transmits from the transmission antenna 44 in order to communicate with the wireless tag 14 when detecting the intensity of the reception signal and the cancellation signal in the control of the cancellation signal. A transmission signal having a smaller signal strength than the transmission signal to be transmitted is transmitted from the transmission antenna 44. In the control of the cancellation signal, it is only necessary to detect and compare the reception signal received by the reception antenna 44, that is, the sneak signal from the transmission side and the cancellation signal, so that the response wave F _r is returned to the wireless tag 14. It is not necessary to output a comparatively large transmission signal that is sufficient to cause the signal to be transmitted, and a smaller carrier than that used for communication with the wireless tag 14 is sufficient.

  The cancel signal control unit 72 controls the phase and / or amplitude of the cancel signal based on the comparison result from the signal strength comparison unit 80. That is, a plurality of types of signal intensities stored in the storage unit 82 are supplied to the cancel phase control unit 60 by comparing them with each other or by comparing them with the signal intensities detected by the signal intensity detection unit 78. The cancel phase control signal and / or the cancel amplitude control signal supplied to the cancel amplitude control unit 62 are changed. Hereinafter, three modes of control of the cancel signal by the cancel signal control unit 72 will be described.

  In the first control mode, first, the transmission control unit 68 transmits the transmission signal from the transmission antenna 44 in a state where the cancellation signal supply suppression control unit 74 suppresses the supply of the cancellation signal to the cancellation signal synthesis unit 52. And the signal strength detector 78 detects the strength of the received signal received by the receiving antenna 48 (the sum of the squares of the in-phase component and the quadrature component) and stores the detection result in the storage unit 82. Let In this way, the strength of the received signal received by the receiving antenna 48 can be accurately detected by the signal strength detector 78. The intensity of the received signal is approximately equal to the intensity of the sneak signal from the transmission side. Next, the suppression of the supply of the cancel signal to the cancel signal combining unit 52 is released (that is, returned to a necessary and sufficient size), and the received signal input end 64i is terminated by the received signal termination control unit 76 Then, the transmission control unit 68 generates a carrier wave from the carrier wave generation unit 36, and the strength of the cancel signal (sum of squares of the in-phase component and the quadrature component) detected by the signal strength detection unit 78 is the storage unit 82. The amplitude of the cancel signal is controlled so as to be equal to the intensity of the received signal stored in (1). In this way, the intensity of the cancel signal generated by the cancel signal generator 46 can be accurately detected by the signal intensity detector 78, and the intensity of the cancel signal is stored in the storage unit 82. Further, the amplitude of the cancel signal can be controlled so as to be substantially equal to the intensity of the received signal, that is, the intensity of the sneak signal from the transmission side. Then, the transmission control unit 68 outputs a transmission signal from the transmission antenna 44 in a state where the reception signal input end 64 i is terminated by the reception signal termination control unit 76, and is detected by the signal strength detection unit 78. The phase of the cancel signal is controlled so that the intensity of the combined signal of the received signal and the cancel signal becomes as small as possible. In this way, the phase of the cancel signal is controlled so as to suppress the sneak signal from the transmission side to the maximum.

  In the second control mode, first, the transmission control unit 68 transmits the transmission signal from the transmission antenna 44 in a state in which the cancellation signal supply suppression control unit 74 suppresses the supply of the cancellation signal to the cancellation signal synthesis unit 52. , The intensities of the in-phase component and the quadrature component of the received signal output from the quadrature demodulation unit 54 are detected by the signal strength detection unit 78 and the detection result is stored in the storage unit 82. In this way, the intensities of the in-phase component and the quadrature component of the received signal received by the receiving antenna 48 can be accurately detected by the signal strength detection unit 78. Next, the transmission control unit 68 generates the carrier wave in a state where the suppression of the supply of the cancellation signal to the cancellation signal synthesis unit 52 is released and the reception signal termination control unit 76 terminates the reception signal input terminal 64i. The carrier wave is generated from the unit 36, and the in-phase component and the quadrature component intensity of the cancellation signal detected by the signal strength detection unit 78 are the in-phase component and the quadrature component of the received signal stored in the storage unit 82, respectively. The amplitude and / or phase of the cancel signal is controlled through the cancel phase control unit 60 and the cancel amplitude control unit 62 so as to be equal to the intensity. In this way, the strength of the cancel signal generated by the cancel signal generator 46 can be accurately detected by the signal strength detector 78, and the cancel signal is stored in the storage unit 82. The phase and / or amplitude of the cancellation signal can be controlled so as to be approximately equal to the reception signal, that is, the sneak signal from the transmission side. Then, after controlling the phase of the cancellation signal via the cancellation phase control unit 60 so that the phase of the cancellation signal is rotated by 180 °, the termination of the reception signal input end 64i by the reception signal termination control unit 76 Is released. In this way, the cancel signal can be controlled so as to suppress the sneak signal from the transmission side to the maximum extent.

  In the third control mode, first, the transmission control unit 68 transmits the transmission signal from the transmission antenna 44 in a state in which the cancellation signal supply suppression control unit 74 suppresses the supply of the cancellation signal to the cancellation signal synthesis unit 52. , The intensities of the in-phase component and the quadrature component of the received signal output from the quadrature demodulation unit 54 are detected by the signal strength detection unit 78 and the detection result is stored in the storage unit 82. In this way, the intensities of the in-phase component and the quadrature component of the received signal received by the receiving antenna 48 can be accurately detected by the signal strength detection unit 78. Next, the transmission control unit 68 generates the carrier wave in a state where the suppression of the supply of the cancellation signal to the cancellation signal synthesis unit 52 is released and the reception signal termination control unit 76 terminates the reception signal input terminal 64i. The in-phase component and the quadrature component of the cancellation signal detected by the signal strength detection unit 78 are generated from the unit 36, and the in-phase component and the quadrature component of the received signal stored in the storage unit 82 After the cancellation phase control unit 60 and / or the cancellation amplitude control unit 62 controls the amplitude and / or phase of the cancellation signal so that the signs are equal and opposite, the reception by the reception signal termination control unit 76 is performed. The termination of the signal input terminal 64i is canceled. In this way, the cancel signal can be controlled so as to suppress the sneak signal from the transmission side to the maximum extent.

  The cancel signal control (cancellation circuit control) by the cancel signal control unit 72 has been described above. The control timing is preferably (a) prior to execution of information transmission to the wireless tag 14 to be communicated. (B) performed during the execution of information transmission to the wireless tag 14 to be communicated, (c) performed every time the transmission control unit 68 switches the frequency of the transmission signal (carrier wave), (D) Various modes are conceivable, for example, when the intensity of the combined signal of the reception signal and the cancellation signal detected by the signal intensity detection unit 78 becomes a predetermined value or more. In the aspect of (a), the reception state can be made suitable before communication with the wireless tag 14 by controlling the cancel signal prior to the execution of information transmission to the wireless tag 14. . Further, in the mode (b), by performing control of the cancel signal during execution of information transmission to the wireless tag 14, the reception state is preferable when the reply signal returned from the wireless tag 14 is received. can do. In the aspect (c), the cancel signal is controlled every time the frequency of the transmission signal is switched, so that the sneak signal from the transmission side that changes following the frequency of the transmission signal can be switched. It can suppress suitably by the cancellation signal set for every. Further, in the mode (d), the cancel signal is controlled from the transmission side by controlling the cancel signal when the intensity of the combined signal detected by the signal intensity detecting unit 78 becomes a predetermined value or more. When it is determined that the signal cannot be sufficiently suppressed, the control can be performed.

  Thus, according to the present embodiment, the cancel amplitude control unit 62 that functions as a cancel signal supply suppressing unit that selectively suppresses the supply of the cancel signal to the cancel signal combining unit 52, and the receiving antenna 48 A reception signal termination unit 50 that selectively terminates a reception signal input terminal 64i to the cancel signal synthesis unit 52; a signal strength detection unit 78 that detects the intensity of the cancellation signal, the reception signal, or a combination thereof; The storage unit 82 that stores the signal intensity detected by the signal intensity detection unit 78 and a plurality of types of signal intensities read from the storage unit 82 or signals detected by the signal intensity detection unit 78 with each other. A signal intensity comparison unit 80 for comparing the intensity and the cancellation amplitude control unit 6 based on a comparison result by the signal intensity comparison unit 80. And / or a cancel signal control unit 72 that controls the amplitude and / or phase of the cancel signal via the cancel phase control unit 60, so that the cancel signal is suppressed by the cancel signal supply suppression unit. While the intensity of the received signal can be accurately detected, the intensity of the cancel signal can be accurately detected by terminating the received signal by the received signal termination unit 50. In other words, it is possible to provide a wireless communication apparatus that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  The reception signal termination unit 50 includes a circuit switching unit 64 that switches a circuit between the reception antenna 48 and the reception signal input terminal 64i, and a termination resistor 66 connected to the circuit switching unit 64. The circuit switching unit 64 connects the reception signal input terminal 64i and the termination resistor 66 when detecting the strength of the cancel signal. Therefore, the circuit switching unit 64 is connected to the termination of the reception signal. By using it, the signal path at the time of reception and the termination path at the time of termination can be switched in a practical manner.

  The cancel signal supply suppression control unit 76 controls the amplitude of the carrier component so that the output from the cancel amplitude control unit 62 is as small as possible when detecting the intensity of the received signal. Therefore, the supply of the cancel signal to the cancel signal combining unit can be suppressed in a practical manner without providing a new configuration.

  Further, since the transmitting antenna 44 and the receiving antenna 48 are individually provided as separate antennas, the influence on the transmitting side when the cancel signal is controlled can be minimized. .

  In addition, the transmission control unit 68, when detecting the strength of the cancellation signal, has a signal strength higher than that of the transmission signal transmitted from the transmission antenna 44 in order to communicate with the wireless tag 14 that is a communication target. Since a small transmission signal is transmitted from the transmitting antenna 44, it is possible to prevent unnecessary transmission of a large transmission signal and save power, and to suppress the influence on other stations.

  In addition, the cancel signal control unit 72 first uses the signal strength detection unit 78 to suppress the strength of the received signal while the cancel amplitude control unit 62 suppresses the supply of the cancel signal to the cancel signal combining unit 52. And the detection result is stored in the storage unit 82. Next, the suppression of the supply of the cancellation signal to the cancellation signal combining unit 52 is released, and the reception signal terminal unit 50i receives the reception signal input terminal 64i. In the state where the signal is detected, the cancellation signal detected by the signal strength detection unit 78 controls the amplitude of the cancellation signal so as to be equal to the strength of the reception signal stored in the storage unit 82, Further, the signal strength detecting unit 78 detects the terminal of the reception signal input end 64i released by the reception signal termination unit 50. Since the phase of the cancellation signal is controlled so that the intensity of the combined signal of the received signal and the cancellation signal is reduced as much as possible, by separately controlling the amplitude and phase of the cancellation signal, The cancel signal can be easily controlled.

  In addition, the cancel signal control unit 72 first causes the signal strength detection unit 78 to in-phase the received signal while the cancel amplitude control unit 62 suppresses the supply of the cancel signal to the cancel signal combining unit 52. The intensity of each of the component and the orthogonal component is detected, and the detection result is stored in the storage unit 82. Next, the suppression of the supply of the cancellation signal to the cancellation signal combining unit 52 is released, and the reception signal termination unit 50 With the received signal input end 64i terminated, the in-phase component and the quadrature component of the cancellation signal detected by the signal strength detection unit 78 have the in-phase received signal stored in the storage unit 82. Controlling the amplitude and / or phase of the cancellation signal to be equal to the intensity of each of the component and the quadrature component, After controlling the phase of the cancellation signal so that the phase of the cancellation signal is rotated by 180 °, the termination of the reception signal input end 64i by the reception signal termination unit 50 is canceled. By simultaneously controlling the phase and the phase, the cancel signal can be controlled in a relatively short time.

  In addition, the cancel signal control unit 72 first causes the signal strength detection unit 78 to in-phase the received signal while the cancel amplitude control unit 62 suppresses the supply of the cancel signal to the cancel signal combining unit 52. The intensity of each of the component and the orthogonal component is detected, and the detection result is stored in the storage unit 82. Next, the suppression of the supply of the cancellation signal to the cancellation signal combining unit 52 is released, and the reception signal termination unit 50 The in-phase component and the quadrature component of the cancel signal detected by the signal strength detection unit 78 with the reception signal input end 64i terminated by the above-mentioned are the in-phase component and the in-phase component of the reception signal stored in the storage unit 82, respectively. The amplitude and / or phase of the cancellation signal is controlled so that the intensity of each orthogonal component is equal and the sign is opposite. Thereafter, since the termination of the reception signal input end 64i by the reception signal termination unit 50 is canceled, the amplitude and phase of the cancellation signal are simultaneously controlled and the rotation of the phase is not required. Signal control can be performed in as short a time as possible.

  In addition, since the cancel signal control unit 72 controls the cancel signal prior to the execution of information transmission to the wireless tag 14 that is a communication target, the reception state is set before communication with the wireless tag 14. It can be made suitable.

  In addition, since the cancel signal control unit 72 controls the cancel signal during the transmission of information to the wireless tag 14 that is a communication target, it is received when a reply signal returned from the wireless tag 14 is received. A state can be made suitable.

  Further, since the cancel signal control unit 72 controls the cancel signal every time the frequency of the transmission signal is switched, a sneak signal from the transmission side that changes following the frequency of the transmission signal Can be suitably suppressed by a cancel signal set at each switching.

  The cancel signal control unit 72 controls the cancel signal when the intensity of the combined signal of the received signal and the cancel signal detected by the signal strength detection unit 78 exceeds a predetermined value. In this way, it is possible to suitably determine the timing at which the cancellation signal needs to be controlled.

  In addition, since the demodulator of the received signal includes a homodyne detection circuit including an orthogonal demodulator 54, the sneak signal from the transmission side of the homodyne detection circuit that is particularly affected by the sneak signal from the transmission side is obtained. It can suppress suitably.

  Preferably, the wireless communication apparatus transmits a predetermined transmission signal to the wireless tag 14 by the transmitting antenna 44 and transmits a reply signal returned from the wireless tag 14 in response to the transmission signal. Since the wireless tag communication device 12 performs communication of information with the wireless tag 14 by receiving by the reception antenna 48, the wireless tag communication device 12 that is particularly affected by the sneak signal from the transmission side. The sneak signal from the transmission side can be suitably suppressed.

  Next, another preferred aspect of the wireless communication apparatus of the present invention will be described in detail based on the drawings. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 4 is a diagram for explaining the configuration of a wireless tag communication device 84 which is another embodiment of the wireless communication device of the present invention. As shown in FIG. 4, the RFID tag communication device 84 of this embodiment includes a reception signal termination unit 86 that selectively terminates a reception signal input end 64 i from the reception antenna 48 to the cancel signal synthesis unit 52. I have. In addition to the circuit switching unit 64 and the termination resistor 66 provided in the above-described reception signal termination unit 50, the reception signal termination unit 86 is connected to the reception antenna 48 side from the circuit switching unit 64 and the termination resistor 66. A second circuit switching unit 88 that switches a circuit between the receiving antenna 48 and the circuit switching unit 64, and a second termination resistor 90 of about 50Ω connected to the second circuit switching unit 88, for example. , Which is provided. The circuit switching unit 64 and the second termination resistor 90 are connected in parallel to the second circuit switching unit 88. By switching the second circuit switching unit 88, the circuit switching unit 64 and the second termination resistor 90 are connected. The terminating resistor 90 is alternatively connected to the receiving antenna 48 (not necessarily connected directly). The end of the second termination resistor 90 opposite to the second circuit switching unit 88 is grounded. The reception signal termination control unit 76 provided in the central control unit 34 connects the reception signal input terminal 64i and the termination resistor 66 by the circuit switching unit 64 and the second circuit switching unit 88. By connecting the reception antenna 48 and the second termination resistor 90, the reception signal input terminal 64i from the reception antenna 48 to the cancel signal combining unit 52 is terminated, while the circuit switching unit 64 inputs the reception signal. The terminal 64 i and the receiving antenna 48 are connected and the receiving antenna 48 and the circuit switching unit 64 are connected by the second circuit switching unit 64, so that the receiving antenna 48 connects to the cancel signal combining unit 52. Receive signals are input. The timing at which the circuit is terminated by the reception signal termination unit 86 is the same as that of the above-described embodiment, and the reception signal input terminal 64i from the reception antenna 48 to the cancellation signal synthesis unit 52 is used for the detection of the intensity of the cancellation signal. Terminate.

  Thus, according to the present embodiment, the reception signal termination unit 86 is connected to the reception antenna 48 side of the circuit switching unit 64 and the termination resistor 66 between the reception antenna 48 and the circuit switching unit 64. A second circuit switching unit 88 for switching circuits between the second circuit switching unit 88 and a second termination resistor 90 connected to the second circuit switching unit 88. The second circuit switching unit 88 includes: When detecting the intensity of the cancel signal, the reception antenna 48 and the second termination resistor 90 are connected to each other. Therefore, the reception antenna 48 is dropped to the second termination resistor 90 to receive the signal. The state of the reception antenna 48 can be made the same during control and reception of the cancellation signal, and the signal strength of each of the reception signal and cancellation signal received by the reception antenna 48 can be changed. It can be accurately detected.

  FIG. 5 is a diagram for explaining the configuration of a wireless tag communication device 92 which is still another embodiment of the wireless communication device of the present invention. As shown in FIG. 5, the RFID tag communication apparatus 92 according to the present embodiment includes a third circuit switching unit 94 that switches a circuit between the cancel amplitude control unit 62 and the cancel signal input terminal 94i, and a third circuit switching unit 94. And a third termination resistor 96 of about 50Ω, for example, connected to the circuit switching unit 94. The cancel amplitude control unit 62 and the third termination resistor 96 are connected in parallel to the third circuit switching unit 94, and the cancel amplitude control unit 62 and the third termination switching unit 94 are switched by the switching of the third circuit switching unit 94. A third terminal resistor 96 is alternatively connected to the cancel signal input terminal 94i. Further, the end of the third termination resistor 96 opposite to the third circuit switching unit 94 is grounded. The third circuit switching unit 94 and the third termination resistor 96 function as a part of a cancel signal supply suppressing unit that selectively suppresses supply of a cancel signal to the cancel signal combining unit 52, The third circuit switching unit 94 is switched according to a control signal from the cancel signal supply suppression control unit 74. That is, the cancel signal supply suppression control unit 74 provided in the central control unit 34 connects the cancel signal input terminal 94i and the third termination resistor 96 by the third circuit switching unit 94, thereby canceling the cancellation. The cancellation signal input terminal 94i from the signal generation unit 46 to the cancellation signal synthesis unit 52 is terminated to suppress the supply of the cancellation signal to the cancellation signal synthesis unit 52, while the third circuit switching unit 94 performs the cancellation. By connecting the amplitude control unit 62 and the cancel signal input terminal 94i, the cancel signal is input from the cancel signal generating unit 46 to the cancel signal combining unit 52. The timing for suppressing the supply of the cancel signal to the cancel signal combining unit 52 is the same as in the above-described embodiment, and is generated by the cancel signal generating unit 48 when detecting the intensity of the received signal received by the receiving antenna 48. The third circuit switching unit 94 is switched so as to suppress the supply of the canceled cancel signal to the cancel signal combining unit 52. Further, when the cancel signal is suppressed, it is preferable that the cancel signal supplied to the cancel amplitude control unit 62 so that the output from the cancel amplitude control unit 62 becomes as small as possible, as in the above-described embodiment. Control the amplitude control signal.

  Thus, according to the present embodiment, the cancel signal supply suppressing unit includes the third circuit switching unit 94 that switches the circuit between the cancel amplitude control unit 62 and the cancel signal input terminal 94i, and the third circuit switching unit 94. And a third termination resistor 96 connected to the circuit switching unit 94. When detecting the intensity of the received signal, the cancel signal input end 94i and the third termination resistor 96 are connected. Therefore, by using the third circuit switching unit 94, the input of the cancel signal to the cancel signal input terminal 94i can be suppressed as much as possible, and the output from the cancel amplitude control unit 62 can be suppressed. By reducing as much as possible, reflection to the cancel circuit side can be suppressed.

  FIG. 6 is a diagram for explaining the configuration of a wireless tag communication device 98 which is still another embodiment of the wireless communication device of the present invention. As shown in FIG. 6, the RFID tag communication apparatus 98 of this embodiment is output from the transmit / receive amplifier 42 and the array antenna 100 for transmission / reception composed of a plurality (two in FIG. 6) of antenna elements 102a and 102b. A plurality of (two in FIG. 6) transmission / reception separation units 104a that supply transmission signals to the antenna elements 102a and 102b and supply reception signals received by the antenna elements 102a and 102b to the reception signal synthesis unit 106, respectively. , 104b and a reception signal combining unit 106 that combines the reception signals corresponding to the antenna elements 102a and 102b supplied via the transmission / reception separation units 104a and 104b and inputs them to the reception signal termination unit 86, respectively. It is prepared for. In addition, transmission / reception shared phase control units 108a and 108b for controlling the phases of transmission signals and / or reception signals corresponding to the antenna elements 102a and 102b according to the phase control signals supplied from the central control unit 34 are provided. The central control unit 34 controls the transmission directivity and / or reception directivity of the array antenna 100 by supplying phase control signals to the phase control units 108a and 108b. Is functionally provided. Further, a plurality (two in FIG. 6) of phase control signals D / A converters 112a and 112b that are analog-converted from the phase control signal output from the directivity controller 110 and are supplied to the phase controllers 108a and 108b. Is provided. In the wireless tag communication device 98 of this embodiment, the cancel signal control unit 72 controls the cancel signal described above when the phase of the array antenna 100 is changed by the directivity control unit 110. Since the sneak signal from the transmission side changes following the phase of the array antenna 100, the cancellation signal can be optimized as necessary in this way.

  As described above, according to the present embodiment, the transmission antenna is controlled by controlling the phase of the array antenna 100 including the plurality of antenna elements 102a and 102b and the transmission signals transmitted to the antenna elements 102a and 102b. Since the phase control units 108a and 108b for controlling the directivity are provided and the cancel signal control unit 72 controls the cancel signal when the phase of the array antenna 100 is changed, the array antenna A sneak signal from the transmission side that changes following the 100 weights can be suitably suppressed by a cancel signal set every time the weights are switched.

  In addition, as a receiving antenna, an array antenna 100 including a plurality of antenna elements 102a and 102b, and a phase control unit 108a that controls reception directivity by controlling the phase of each received signal transmitted to each antenna element 102a and 102b. 108b, and when the phase of the array antenna 100 is changed, the cancel signal control unit 72 controls the cancel signal, so that it changes following the weight of the array antenna 100. A sneak signal from the transmission side can be suitably suppressed by a cancel signal set every time the weight is switched.

  Further, since the transmitting antenna and the receiving antenna are integrally provided as an array antenna 100 that is shared for transmission and reception, the configuration of the apparatus can be made as simple as possible.

  Next, cancel circuit control by the central control unit 34 of the above-described RFID tag communication apparatuses 12, 84, 92, and 98 will be described with reference to the flowcharts of FIGS. Note that the cancel circuit control (cancellation signal control) shown in the flowcharts of FIGS. 7 to 10 described in detail below can be applied to any of the above-described RFID tag communication apparatuses 12, 84, 92, and 98. 7 to 8 are the first control mode exemplified in the description of the RFID tag communication apparatus 12, the control of FIG. 9 is the second control mode, and the control of FIG. 10 is the third control mode. Respectively.

  7 to 8 are flowcharts for explaining the main part of the cancel circuit control by the central control unit 34, which is repeatedly executed at a predetermined cycle. In this control, first, in step (hereinafter, step is omitted) S1, the frequency of the transmission signal (carrier wave) is switched by the transmission control unit 68, or the received signal detected by the signal strength detection unit 78 is canceled. It is determined whether or not the cancel circuit control start condition is satisfied, for example, when the intensity of the combined signal with the signal becomes a predetermined value or more. If the determination at S1 is negative, the routine is terminated. If the determination at S1 is affirmative, the output from the cancel amplitude control unit 62 is as much as possible at S2. The cancel signal cut means is turned on by controlling the cancel amplitude control signal so as to be small. Next, in S3, the signal strength of the received signal received by the receiving antenna 48 or the array antenna 100 is detected. Next, in S4, the signal strength of the received signal detected in S3 is stored in the storage unit 82. Next, in S5, the cancel signal cut means is turned off by controlling the cancel amplitude control signal so that the output from the cancel amplitude control unit 62 has a necessary and sufficient magnitude. Next, in S6, the reception signal termination unit 50 or 86 terminates the reception signal termination means such as the reception signal input terminal 64i from the reception antenna 48 or the array antenna 100 to the cancel signal synthesis unit 52 is terminated. Turned on. Next, in S7, the signal strength of the cancel signal generated by the cancel signal generator 46 is detected. Next, in S8, the signal strength of the cancel signal detected in S7 is compared with the signal strength of the received signal stored in the storage unit 82 in S4. Next, in S9, it is determined whether or not the signal strength of the cancel signal detected in S7 in the comparison in S8 is greater. If the determination in S8 is affirmative, in S10, after the cancel amplitude control signal is controlled so that the amplitude of the cancel signal output from the cancel amplitude control unit 62 is smaller than the amplitude at that time, The processing after S7 is executed again, but if the determination in S9 is negative, it is determined in S11 whether or not the signal strength of the cancel signal detected in S7 in the comparison of S8 is smaller. The If the determination in S11 is affirmative, in S12, after the cancel amplitude control signal is controlled so that the amplitude of the cancel signal output from the cancel amplitude control unit 62 is larger than the amplitude at that time, The processes after S7 are executed again, but if the determination at S11 is negative, the processes after S13 shown in FIG. 8 are executed.

  In S13 subsequent to the processing of S11 described above, the reception signal input end 64i from the reception antenna 48 or the array antenna 100 to the cancel signal combining unit 52 in the reception signal termination unit 50 or 86 is the reception antenna 48 or array. The reception signal termination unit is turned off, for example, by being connected to the antenna 100. Next, in S14, the P flag (P_Flag) is set to zero. Next, in S15, the signal strength of the combined signal of the reception signal combined with the cancellation signal combined by the cancel signal combining unit 52 is detected. Next, in S16, the signal intensity of the combined signal detected in S15 is stored in the storage unit 82. Next, in S22, the cancellation phase control unit 60 controls the cancellation phase control signal so that the phase of the cancellation signal is advanced by a predetermined value. Next, in S <b> 17, the signal strength of the combined signal of the reception signal combined with the cancel signal combined by the cancel signal combining unit 52 is detected. Next, in S18, the signal strength of the composite signal detected in S17 is compared with the signal strength of the composite signal stored in the storage unit 82 in S16. Next, in S19, it is determined whether or not the signal strength of the combined signal detected in S17 in the comparison in S18 is smaller. If the determination in S19 is negative, the processing from S23 is executed. If the determination in S19 is positive, the signal strength of the combined signal detected in S17 is stored in S20 in S20. Stored in the unit 82. Next, in S21, after the P flag (P_Flag) is set to 1, processing in S22 and subsequent steps is executed. In the processing of S23, it is determined whether or not the signal strength of the combined signal detected in S17 in the comparison of S18 is greater. If the determination in S23 is negative, the routine is terminated accordingly. If the determination in S23 is affirmative, the signal strength of the combined signal detected in S17 is stored in S24 in S24. Stored in the unit 82. Next, in S25, after the P flag (P_Flag) is set to zero, the processing from S22 is executed. In the above control, S1 to S25 are operations of the cancel signal control unit 72, S2 and S5 are operations of the cancel signal supply suppression control unit 74, and S6 and S13 are operations of the reception signal termination control unit 76. S3, S7, S15, and S17 correspond to the operation of the signal strength detection unit 78, and S8 and S18 correspond to the operation of the signal strength comparison unit 80, respectively.

  FIG. 9 is a flowchart for explaining a main part of another example of the cancel circuit control by the central control unit 34, which is repeatedly executed at a predetermined cycle. In the control shown in FIG. 9, the steps common to the control shown in FIGS. 7 to 8 described above are denoted by the same reference numerals, and the description thereof is omitted. In the control shown in FIG. 9, the in-phase component (I-phase component) and the quadrature component (Q) of the received signal supplied from the receiving antenna 48 via the quadrature demodulator 54 in S27 following the processing of S2 described above. The signal intensity of each phase component) is detected. Next, in S28, the signal strengths of the in-phase component and the quadrature component of the received signal detected in S27 are stored in the storage unit 82. Next, after the processing of S5 to S6 described above is performed, in S29, the signal intensities of the in-phase component and the quadrature component of the cancel signal supplied from the cancel signal generation unit 48 via the quadrature demodulation unit 54 are obtained. Detected. Next, in S30 corresponding to the operation of the signal strength comparison unit 80, the received signal stored in the storage unit 82 in S28 and the signal strength of each of the in-phase component and the quadrature component of the cancellation signal detected in S29. Are compared with the signal intensities of the in-phase and quadrature components of Next, in S31, as a result of the comparison in S30, the in-phase component and the quadrature component of the cancellation signal detected in S29 and the in-phase component and the quadrature component of the received signal stored in the storage unit 82 in S28, respectively. It is determined whether or not the signal intensity of each component is equal. If the determination in S31 is negative, the cancellation phase control signal and the cancellation amplitude control signal are controlled in S32 so that the cancellation signal is transmitted via the cancellation phase control unit 60 and the cancellation amplitude control unit 62. After the phase and amplitude are changed, the processing from S29 is executed again. However, if the determination in S31 is affirmative, after the processing in S13 described above is executed, in S33, the cancel phase control unit After the phase at 60 has been rotated 180 degrees (advanced), the routine is terminated. In the above control, S1, S2, S5, S6, S13, S27 to S33 correspond to the operation of the cancel signal control unit 72, and S27 and S29 correspond to the operation of the signal strength detection unit 78, respectively.

  FIG. 10 is a flowchart for explaining a main part of still another example of cancel circuit control by the central control unit 34, which is repeatedly executed at a predetermined cycle. In the control shown in FIG. 10, steps common to the control shown in FIGS. 7 to 9 described above are denoted by the same reference numerals and description thereof is omitted. In the control shown in FIG. 10, the value obtained by reversing the sign of the signal strength of each of the in-phase component and the quadrature component of the received signal detected in S27 in S34 following the processing of S27 described above is the storage unit 82. Is remembered. Next, after the processes of S5, S6, and S29 described above are performed, in S35 corresponding to the operation of the signal intensity comparison unit 80, the signal intensities of the in-phase component and the quadrature component of the cancel signal detected in S29 are detected. Are compared with the signal intensities of the in-phase component and the quadrature component of the received signal stored in the storage unit 82 (values with positive and negative signs reversed) in S28. Then, after the above-described processing from S31 is executed, this routine is terminated.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other modes.

  For example, in the above-described embodiment, the cancel signal control unit 72, the signal strength detection unit 78, the signal strength comparison unit 80, the storage unit 82, and the like are provided as control functions of the central control unit 34. However, the present invention is not limited to this, and a control device having functions equivalent to those may be provided separately from the central control unit 34. The cancel signal generator 46, the cancel signal synthesizer 52, the quadrature demodulator 54, and the like are provided as separate control devices from the central control unit 34, but the functions equivalent to those are provided in the central control. It may be provided as a control function of the unit 34. Moreover, it does not ask | require whether the process by those control functions is a digital signal process and an analog signal process.

  In the above-described embodiment, the cancel amplitude control unit 62 is used as a cancel signal supply suppressing unit, and the carrier wave component is set so that the output from the cancel amplitude control unit 62 becomes as small as possible when suppressing the supply of the cancel signal. However, various other modes are conceivable as the cancel signal supply suppression unit. For example, the cancel is performed by switching the switch as in the third circuit switching unit 94 shown in FIG. The signal supply may be suppressed. In the above-described embodiment, the example in which the reception signal input terminal 64i from the reception antenna 48 to the cancel signal combining unit 52 is selectively terminated by switching the circuit switching unit 64 or the like has been described. Similarly, various aspects are conceivable as the configuration of the reception signal termination unit.

  Further, in the RFID tag communication device 12 and the like of the above-described embodiment, the transmitting antenna 44 and the receiving antenna 48 are individually provided as separate antennas. It may be provided. This has the advantage that the configuration of the apparatus can be made as simple as possible. Further, a mode is also conceivable in which the RFID tag communication device 98 is provided with a transmitting array antenna and a receiving array antenna, respectively.

  Further, a configuration in which the third circuit switching unit 94 and the third termination resistor 96 shown in FIG. 5 are applied to the RFID tag communication apparatus 12 shown in FIG. 3, or the RFID tag communication apparatus 12 shown in FIG. The configurations of the above-described embodiments, such as the configuration in which the array antenna 100 and the directivity control unit 110 shown in FIG. 6 are applied to the RFID tag communication device 84, can be applied simultaneously to a common device as necessary. .

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

It is a figure explaining the radio | wireless tag communication system with which the radio | wireless communication apparatus of this invention is used suitably. It is a figure explaining the structure of the radio | wireless tag circuit element with which the radio | wireless tag which is a communication object of the radio | wireless communication apparatus of this invention was equipped. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is one Example of the radio | wireless communication apparatus of this invention. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is the other Example of the radio | wireless communication apparatus of this invention. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is another Example of the radio | wireless communication apparatus of this invention. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is another Example of the radio | wireless communication apparatus of this invention. 7 is a part of a flowchart for explaining a main part of cancel circuit control by a central control unit of any of the RFID tag communication apparatuses of FIGS. 3 to 6; 7 is a part of a flowchart for explaining a main part of cancel circuit control by a central control unit of any of the RFID tag communication apparatuses of FIGS. 3 to 6; 7 is a flowchart for explaining a main part of another example of cancel circuit control by the central control unit of any of the RFID tag communication apparatuses of FIGS. 3 to 6. 7 is a flowchart for explaining a main part of still another example of cancel circuit control by the central control unit of the RFID tag communication apparatus of any of FIGS. 3 to 6.

Explanation of symbols

12, 84, 92, 98: RFID tag communication device (wireless communication device)
14: Wireless tag (communication target)
40: Second distributor (distributor)
44: Transmitting antenna 48: Reception antenna 50, 86: Received signal termination unit 52: Cancel signal synthesis unit 60: Cancel phase control unit 62: Cancel amplitude control unit (cancel signal supply suppression unit)
64: circuit switching unit 64i: received signal input terminal 66: termination resistor 72: cancellation signal control unit 78: signal strength detection unit 80: signal strength comparison unit 82: storage unit 88: second circuit switching unit 90: second Termination resistor 94: third circuit switching unit 94i: cancel signal input terminal 96: third termination resistor 100: array antenna 102: antenna element 108: phase control unit

Claims (19)

A distribution unit that distributes a carrier component of a transmission signal transmitted from a transmission antenna;
An amplitude control unit for controlling the amplitude of the carrier wave component distributed by the distribution unit;
A phase control unit for controlling the phase of the carrier wave component distributed by the distribution unit;
A cancellation signal combining unit that adds a cancellation signal generated from the carrier wave component via the amplitude control unit and the phase control unit to a reception signal received by a receiving antenna;
A cancel signal supply suppressing unit that selectively suppresses supply of a cancel signal to the cancel signal combining unit;
A reception signal termination unit that selectively terminates a reception signal input terminal from the reception antenna to the cancel signal synthesis unit;
A signal strength detection unit for detecting the strength of the cancellation signal, the reception signal, or the combined signal thereof;
A storage unit for storing the signal intensity detected by the signal intensity detection unit;
A signal intensity comparison unit that compares a plurality of types of signal intensities read from the storage unit with each other or with a signal intensity detected by the signal intensity detection unit;
And a cancel signal control unit that controls the amplitude and / or phase of the cancel signal via the amplitude control unit and / or phase control unit based on a comparison result by the signal strength comparison unit. apparatus.   The reception signal termination unit includes a circuit switching unit that switches a circuit between the reception antenna and a reception signal input terminal, and a termination resistor connected to the circuit switching unit, and the circuit switching unit The wireless communication apparatus according to claim 1, wherein when detecting the intensity of the cancel signal, the unit connects the reception signal input terminal and a termination resistor.   The reception signal termination unit includes a second circuit switching unit that switches a circuit between the reception antenna and the circuit switching unit closer to the reception antenna than the circuit switching unit and a termination resistor, and the second circuit switching unit A second termination resistor connected to the circuit switching unit, and the second circuit switching unit includes the reception antenna, the second termination resistor, and the like when detecting the intensity of the cancellation signal. The wireless communication device according to claim 2, wherein the wireless communication device is connected.   4. The cancel signal supply suppressing unit controls the amplitude of the carrier wave component so that the output from the amplitude control unit is as small as possible when detecting the intensity of the received signal. Any wireless communication device.   The cancellation signal supply suppressing unit includes a third circuit switching unit that switches a circuit between the amplitude control unit and the cancellation signal input terminal, and a third termination resistor connected to the third circuit switching unit. The wireless communication apparatus according to claim 1, wherein when the intensity of the received signal is detected, the cancel signal input terminal and a third terminal resistor are connected.   6. The wireless communication apparatus according to claim 1, wherein the transmitting antenna and the receiving antenna are individually provided as separate antennas.   6. The wireless communication apparatus according to claim 1, wherein the transmitting antenna and the receiving antenna are integrally provided as a transmission / reception shared antenna.   When detecting the strength of the cancel signal, a transmission signal having a signal strength smaller than that of the transmission signal transmitted from the transmission antenna is transmitted from the transmission antenna in order to communicate with a predetermined communication target. The wireless communication device according to claim 1. The cancel signal controller is
First, in a state where the cancel signal supply suppressing unit suppresses the supply of the cancel signal to the cancel signal combining unit, the signal intensity detecting unit detects the intensity of the received signal, and the detection result is stored in the storage unit. Remember,
Next, in the state where the suppression of the supply of the cancellation signal to the cancellation signal combining unit is released and the reception signal input end is terminated by the reception signal termination unit, the cancellation signal detected by the signal strength detection unit Controlling the amplitude of the cancellation signal so that the intensity is equal to the intensity of the received signal stored in the storage unit;
Further, the strength of the combined signal of the reception signal and the cancellation signal detected by the signal strength detection unit is made as small as possible in a state where the termination of the reception signal input end by the reception signal termination unit is released. The wireless communication apparatus according to claim 1, wherein the phase of the cancel signal is controlled. The cancel signal controller is
First, in a state where the cancel signal supply suppressing unit suppresses the supply of the cancel signal to the cancel signal combining unit, the signal intensity detecting unit detects the intensities of the in-phase component and the quadrature component of the received signal. The detection result is stored in the storage unit,
Next, in the state where the suppression of the supply of the cancellation signal to the cancellation signal combining unit is released and the reception signal input end is terminated by the reception signal termination unit, the cancellation signal detected by the signal strength detection unit Controlling the amplitude and / or phase of the cancellation signal so that the in-phase component and the quadrature component each have the same intensity as the in-phase component and the quadrature component of the received signal stored in the storage unit,
The termination of the reception signal input end by the reception signal termination unit is canceled after controlling the phase of the cancellation signal so that the phase of the cancellation signal is rotated by 180 °. Any wireless communication device. The cancel signal controller is
First, in a state where the cancel signal supply suppressing unit suppresses the supply of the cancel signal to the cancel signal combining unit, the signal intensity detecting unit detects the intensities of the in-phase component and the quadrature component of the received signal. The detection result is stored in the storage unit,
Next, in the state where the suppression of the supply of the cancellation signal to the cancellation signal combining unit is released and the reception signal input end is terminated by the reception signal termination unit, the cancellation signal detected by the signal strength detection unit After controlling the amplitude and / or phase of the cancellation signal so that the in-phase component and the quadrature component are equal to the in-phase component and the quadrature component of the received signal stored in the storage unit, respectively, and are opposite in sign. The wireless communication device according to claim 1, wherein the termination of the reception signal input end by the reception signal termination unit is canceled.   12. The wireless communication apparatus according to claim 1, wherein the cancel signal control unit controls the cancel signal prior to execution of information transmission to a predetermined communication target.   12. The wireless communication apparatus according to claim 1, wherein the cancel signal is controlled by the cancel signal control unit during execution of information transmission to a predetermined communication target.   The wireless communication apparatus according to any one of claims 1 to 13, wherein the cancel signal control unit controls the cancel signal every time the frequency of the transmission signal is switched.   15. The cancel signal is controlled by the cancel signal control unit when the strength of the combined signal of the reception signal and the cancel signal detected by the signal strength detection unit exceeds a predetermined value. Any wireless communication device.   The transmission antenna includes an array antenna including a plurality of transmission antenna elements, and a transmission phase control unit that controls transmission directivity by controlling the phase of each transmission signal transmitted to each transmission antenna element. The wireless communication apparatus according to claim 1, wherein when the phase of the transmission phase control unit is changed, the cancel signal control unit controls the cancel signal.   The receiving antenna includes an array antenna composed of a plurality of receiving antenna elements, and a receiving phase control unit that controls the receiving directivity by controlling the phase of each received signal transmitted from each receiving antenna element. The wireless communication apparatus according to claim 1, wherein when the phase of the reception phase control unit is changed, a cancel signal is controlled by the cancel signal control unit.   The radio communication apparatus according to claim 1, further comprising a homodyne detection circuit as a demodulator for the received signal.   The wireless communication device transmits a predetermined transmission signal to the wireless tag by the transmitting antenna and receives a return signal returned from the wireless tag in response to the transmission signal by the receiving antenna. The wireless communication device according to claim 1, which is a wireless tag communication device that communicates information with the wireless tag.

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