JP4148192B2 - Interrogator for wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system, for example, an interrogator of a wireless tag communication system that reads or writes information from and to a wireless tag capable of wireless communication of information with the outside.

RFID (Radio Frequency ) that reads / writes information of a wireless tag by transmitting and receiving an inquiry and receiving a response from a reader / writer as an interrogator with respect to a small wireless tag as a responder Identification) system is known.

  For example, a wireless tag circuit element included in a label-like wireless tag includes an IC circuit unit that stores predetermined wireless tag information and an antenna that is connected to the IC circuit unit and transmits / receives information. When a transmission wave is transmitted from a transmission antenna of a reader / writer as an interrogator to a wireless tag as a responder, the wireless tag circuit element transmits a response using the energy of the radio wave of the transmission wave. That is, when the reader / writer transmits radio waves, the radio wave from the wireless tag returned almost simultaneously is received by the receiving antenna of the reader / writer. At this time, since the attenuation amount (transmission / reception separation degree) of the radio wave between the transmission antenna and the reception antenna in the reader / writer is finite, the transmission signal is inevitably received and mixed by the reception system from the reception antenna. Thus, the reception of the reply signal from the wireless tag is disturbed.

  In order to solve this problem, conventionally, a canceling wave (compensation signal) for canceling (compensating) the unnecessary wave that interferes with the reception system during transmission of the transmission wave is created. Have been proposed (for example, see Patent Document 1). In this prior art, the signal demultiplexed from the transmission system is adjusted with the variable phase shifter and variable attenuator to adjust the phase and amplitude to create a cancellation wave, and this is combined with the reception system with the multiplexer to generate an unnecessary wave. Is offset. When setting the cancellation wave, the transmission signal is transmitted from the interrogator in a state where there is no reflection response from the responder, and the level of the combined signal of the signal mixed in the reception system and the cancellation wave is minimized in this state. As described above, the variable phase shifter and the variable attenuator are manually operated and adjusted. Moreover, when the mode of the unwanted wave changes due to aging, for example, it is adapted by manual periodic adjustment every year.

JP-A-8-122429 (paragraph numbers 0030 to 0038, FIGS. 1 to 4)

  The RFID system as described above accesses the RFID tag circuit element from the interrogator reader / writer side even when the responding RFID tag is dirty or in an invisible position (information Therefore, it is being put to practical use in various fields such as merchandise management, distribution management, inspection process, and search / detection of movements of objects and people.

  However, in view of the situation for actively introducing such RFID systems into various fields, the above-described conventional technology has the following problems. That is, for example, when searching for goods in a distribution warehouse, if another person passes by or there is a presence or movement of metal objects, the wireless communication status between the interrogator and the responder will be greatly affected. give. That is, as the introduction of the RFID system progresses to various fields or the like, the influence on the communication situation due to the change in the surrounding environment as described above becomes larger, and the generation behavior of unnecessary waves also changes greatly.

  In the above-described conventional technique, when the setting of the cancellation wave is once optimized manually and the mode of the unwanted wave changes, it can be dealt with only by manual adjustment every year, for example. For this reason, it is difficult to maintain high reception sensitivity by dealing with changes in the surrounding environment as described above in real time and performing sufficient cancellation with cancellation waves.

  An object of the present invention is to provide an interrogator for a wireless communication system that can perform sufficient cancellation by a cancellation wave in real time in response to changes in the surrounding environment and maintain high reception sensitivity.

In order to achieve the above object, the first invention is a carrier wave generating means for generating a carrier wave for accessing the responder, and a carrier wave modulation for modulating the carrier wave generated from the carrier wave generating means to obtain a modulated carrier wave. A carrier output means for outputting a carrier from the carrier generation means or the carrier modulation means, a transmission means capable of transmitting the carrier output from the carrier output means to the responder, and this transmission. A receiving unit capable of receiving a transmission signal from the transponder according to a transmission signal from the unit, and for canceling an unnecessary wave that may be generated based on the transmission signal from the transmitting unit when the signal is received by the receiving unit. Canceling wave generating means for generating a canceling wave, and signal strength detecting means for detecting the received signal strength of the receiving means canceled by the canceling wave from the canceling wave generating means; Prior to transmitting the transmission wave modulated by the carrier wave modulation means from the carrier wave output means and transmitting from the transmission means, the carrier wave output means outputs the carrier wave of the carrier wave generation means and transmits from the transmission means, The carrier wave generation unit, the transmission unit, and the transmission unit are configured to change the phase and amplitude of the cancellation wave generated from the cancellation wave generation unit according to the detection result of the signal intensity detection unit, and to set an optimum value. And canceling wave control means for controlling the canceling wave generating means.
In order to achieve the above object, the second invention is a carrier wave generating means for generating a carrier wave for accessing a responder, and a carrier wave modulation for modulating the carrier wave generated from the carrier wave generating means to obtain a modulated carrier wave. A carrier output means for outputting a carrier from the carrier generation means or the carrier modulation means, a transmission means capable of transmitting the carrier output from the carrier output means to the responder, and this transmission. A receiving unit capable of receiving a transmission signal from the transponder according to a transmission signal from the unit, and for canceling an unnecessary wave that may be generated based on the transmission signal from the transmitting unit when the signal is received by the receiving unit. Canceling wave generating means for generating a canceling wave, and signal strength detecting means for detecting the received signal strength of the receiving means canceled by the canceling wave from the canceling wave generating means; Prior to outputting the transmission wave modulated by the carrier wave modulation means from the carrier wave output means and transmitting from the transmission means, the carrier wave of the carrier wave generation means is output from the carrier wave output means and transmitted from the transmission means, The carrier wave generating means is configured to change the phase and amplitude of the cancellation wave generated by the cancellation wave generating means in accordance with the detection value variation based on the detection result of the signal intensity detection means and to set an optimum value. And a canceling wave control means for controlling the canceling wave generating means.

In the first and second inventions of the present application, before starting the main communication with the transponder, the cancellation wave control means controls the carrier wave generation means, the transmission means, and the cancellation wave generation means, so that the carrier wave output means The carrier wave (unmodulated) of the carrier wave generation means is output and transmitted from the transmission means. Based on the transmission signal from the transmission means at this time, a predetermined reception signal component can be generated by the reception means, but this is canceled by the cancellation wave generated by the cancellation wave generation means. The canceled received signal strength is detected by the signal strength detecting means, and the phase and amplitude of the canceling wave at the canceling wave generating means change according to the detection result, so that the received signal strength is minimized. Is set.

  As described above, before the interrogator and the responder start this communication, they are automatically adjusted and set so that the phase and amplitude of the cancellation wave of the cancellation wave generating means are optimal values each time. Therefore, for example, unlike the prior art in which periodic adjustment is performed manually every year or the like, unnecessary waves can be sufficiently canceled in response to changes in the surrounding environment in real time. As a result, high reception sensitivity can be maintained, and the reception signal (response signal) from the transponder can be obtained more clearly after the start of communication.

According to a third aspect of the present invention, in the first or second aspect of the invention, the canceling wave control means causes the canceling wave generating means to reduce the detected value of the signal strength detecting means so that the phase and amplitude of the canceling wave are reduced. And an optimum value is set.

  Depending on the detection result of the signal strength detecting means, the phase and amplitude of the canceling wave at the canceling wave generating means are set to optimum values so that the received signal strength becomes as small as possible. The offset can be performed sufficiently.

According to a fourth aspect of the present invention based on the third aspect , the canceling wave control means sets the phase and amplitude of the canceling wave as a pair, and sets these values to a relatively large first interval within a relatively large first range. The first search means for sequentially obtaining the detection values of the signal intensity detection means in each pair and searching for the first optimal value of the pair of phases and amplitudes in the first range; The phase and amplitude are changed at a relatively small second interval within a relatively small second range in the vicinity of the primary optimal value, and the detection values of the signal intensity detection means in each pair are sequentially obtained, and the first And a second search means for searching for a final optimum value within a range of 2 and selecting it as a set value.

  The first search means first searches for the primary optimum value roughly in the first range, and then the second search means searches for the final optimum value in the second range more precisely. Compared to searching for a value, the final optimum values of the phase and amplitude of the canceling wave can be acquired in a short time and efficiently with a small calculation processing load.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects , the canceling wave control unit is configured to detect the phase of the canceling wave in the canceling wave generating unit according to the detection result of the signal intensity detecting unit. And first determination means for determining whether or not to change a setting value already set for at least one of the amplitudes.

  As described above, after the communication is performed with the phase and amplitude of the cancellation wave set to the optimum values before the start of the communication, the first determination unit determines whether the phase or amplitude set value should be changed. As a result, once set phase or amplitude values can be corrected according to changes in the environment, etc., as needed.

According to a sixth aspect , in the fifth aspect , the first determination unit is configured to set a first value related to the received signal strength, which is set correspondingly after the optimum values related to the pair of phases and amplitudes are set. The threshold value is compared with the detection value of the signal intensity detection means, and it is determined whether or not the detection value is larger than the first threshold value.

  When the received signal strength is greater than the first threshold value, it is determined by the first determination means that at least one of the setting values of the phase or amplitude of the cancellation wave should be changed, and thereby the initially set phase or amplitude value After that, it can be revised as needed according to changes in the environment.

In a seventh aspect based on the sixth aspect , the canceling wave control means determines at least one of the phase and amplitude of the canceling wave in the canceling wave generating means before the determination by the first determining means. A second determination means for determining whether or not to change the already set value is provided.

  As described above, after the communication is performed with the phase and amplitude of the cancellation wave set to the optimum values before the start of the communication, the second determination unit determines whether the phase or amplitude set value should be changed. As a result, once set phase or amplitude values can be corrected according to changes in the environment, etc., as needed.

  In particular, by adopting a two-stage determination configuration in which the second determination unit is provided before the determination by the first determination unit, the second determination unit largely resets the basic setting (the same as the initial setting performed before the communication). A role of determining whether or not fine adjustment of the setting is necessary even if not so much as the above in the first determination means when this determination is not satisfied, Sharing can be achieved. By dividing the determination of the necessity of correction and the correction procedure according to how much correction is necessary for the set value of such phase and amplitude, the phase of the cancellation wave can be efficiently performed in a short time and with a small calculation processing load. And the set value of the amplitude can be corrected.

In an eighth aspect based on the seventh aspect , the second determination means sets the first value relating to the received signal strength, which is set correspondingly after the optimum values relating to the pair of phases and amplitudes are set. Comparing a second threshold value larger than the threshold value with a detection value of the signal intensity detection means, and determining whether the detection value is larger than the second threshold value; To do.

  When the received signal strength becomes larger than the second threshold value (which is larger than the first threshold value), it is determined by the second determination means that both set values of the canceling wave phase and amplitude should be changed. Thus, the initially set phase and amplitude values can be corrected at any time according to changes in the environment.

According to a ninth invention, in any one of the fifth to eighth inventions, when the determination by the first determination means is satisfied, at least one of the phase and the amplitude is changed. And a control signal output means for outputting a signal for controlling the canceling wave generating means.

  By changing at least one of the set values of the phase or amplitude of the cancellation wave according to the determination of the first determination means, the initially set phase or amplitude value is finely adjusted thereafter according to changes in the environment, etc. be able to.

In a tenth aspect based on the ninth aspect , the first determination means determines whether to change the setting of the phase of the cancellation wave in the cancellation wave generation means according to the detection result of the signal intensity detection means. The control signal output means outputs a signal for controlling the cancellation wave generating means so as to change the setting of the phase when the determination by the first determination means is satisfied. To do.

  By changing the phase setting value in accordance with the determination by the first determination means, the initially set phase value can be finely adjusted according to changes in the environment, etc., as needed.

In an eleventh aspect based on the tenth aspect , the determination by the first determination unit is satisfied, and at least one of the phase and the amplitude of the cancellation wave generation unit is set by a signal from the control signal output unit After the change, there is provided third determination means for determining whether or not to change the set values of the phase and amplitude of the cancellation wave in the cancellation wave generation means again according to the detection result of the signal intensity detection means. It is characterized by that.

  As described above, after the communication is performed with the phase and amplitude of the cancellation wave set to the optimum values before the start of the communication, at least one of the phase and amplitude is changed according to the determination by the first determination means. Even after fine adjustment, even if the third adjustment means determines whether the phase or amplitude setting value should be changed again, the above fine adjustment is not sufficient due to a large change in the environment. Corresponding and correct.

In a twelfth aspect according to any one of the first to fifth aspects, the transmission wave is transmitted from the transmission unit to the responder immediately after performing the control operation by the cancellation wave control unit, and the transmission is performed. The transmission means and a transmission / reception control means for controlling the reception means so as to receive the response signal transmitted from the responder in response to the transmitted wave by the reception means.

  Since the transmission wave transmission and response signal reception are performed immediately after performing the control operation of the cancellation wave control means, it communicates with the responder while making the best use of it without reducing the effect of the cancellation wave optimization by the cancellation wave control means. be able to.

  According to the present invention, before the interrogator and the responder start the main communication, the phase and amplitude of the canceling wave of the canceling wave generating means are automatically adjusted and set every time automatically. Therefore, it is possible to sufficiently cancel out unnecessary waves in response to changes in the surrounding environment in real time. As a result, high reception sensitivity can be maintained, and the reception signal from the responder can be acquired more clearly after the start of communication.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram illustrating an overall outline of a wireless communication system including an interrogator according to the present embodiment.

  In FIG. 1, the RFID tag communication system S includes an interrogator 100 according to the present embodiment and a RFID tag T as a responder corresponding thereto.

  The wireless tag T includes a wireless tag circuit element To including an antenna 151 and an IC circuit unit 150.

  The interrogator 100 transmits and receives signals by wireless communication with the antenna 151 of the RFID circuit element To, and accesses the IC circuit unit 150 of the RFID circuit element To through the antenna 1. A high-frequency circuit 2 (for reading or writing), a signal processing circuit 3 for processing a signal read from the RFID circuit element To, and a control circuit 4 are provided.

  The control circuit 4 is a so-called microcomputer, and although not shown in detail, it is composed of a central processing unit such as a CPU, a ROM, and a RAM, and is stored in advance in the ROM while using a temporary storage function of the RAM. Signal processing is performed according to the program.

  FIG. 2 is a block diagram illustrating an example of a functional configuration of the RFID circuit element To provided in the RFID tag T.

  In FIG. 2, the RFID circuit element To includes an antenna 151 (tag antenna) that transmits and receives signals in a non-contact manner using a high frequency wave such as a UHF band with the antenna 1 on the interrogator 100 side, and the antenna 151. And the IC circuit portion 150 connected to the terminal.

  The IC circuit unit 150 includes a rectifying unit 152 that rectifies the carrier wave received by the antenna 151, a power source unit 153 that accumulates energy of the carrier wave rectified by the rectifying unit 152 and serves as a driving power source, and the antenna 151. A clock extraction unit 154 that extracts a clock signal from the received carrier wave and supplies the clock signal to the control unit 157; a memory unit 155 that functions as an information storage unit that can store a predetermined information signal; and a modem that is connected to the antenna 151 And a controller 157 for controlling the operation of the RFID circuit element To via the rectifier 152, the clock extractor 154, the modem 156, and the like.

  The modulation / demodulation unit 156 demodulates the communication signal received from the antenna 151 of the interrogator 100 and reflects and modulates the carrier wave received from the antenna 1 based on the return signal from the control unit 157. .

  The control unit 157 interprets the received signal demodulated by the modulation / demodulation unit 156, generates a return signal based on the information signal stored in the memory unit 155, and performs basic control such as returning by the modulation / demodulation unit 156. Execute proper control.

  FIG. 3 is a functional block diagram showing a functional configuration of the high-frequency circuit 2 provided in the interrogator 100.

  In FIG. 3, the high-frequency circuit 2 includes a transmission unit (carrier wave output means) 32 that transmits a signal from the antenna 1 to the RFID circuit element To and a reflected wave from the RFID circuit element To that is received by the antenna 1. The input receiving unit 33, the transmitting unit 32 and the receiving unit 33 and the antenna 1 are connected in one direction, that is, the signal from the transmitting unit 32 is transmitted to the antenna 1 and at the same time the signal received by the antenna 1 is received by the receiving unit. When the signal is received by the transmission / reception separator 34 and the reception unit 33 (for example, comprising a circular radar or the like) transmitted to the transmission unit 33, the unnecessary wave (around signal) that may be generated based on the transmission signal from the transmission unit 33 is canceled out. And a cancel circuit (cancellation wave generating means) 200 for generating a cancel signal (cancellation wave).

  The cancel circuit 200 includes a cancel signal amplitude adjusting unit 201 and a cancel signal phase adjusting unit that control the amplitude and phase, respectively, in order to generate the cancel signal that is the canceling wave based on the carrier wave distributed and supplied from the transmission unit 32. And a combiner 203 that combines the cancel signal generated by the cancel signal amplitude adjusting unit 201 and the cancel signal phase adjusting unit 202 and the signal received by the antenna 1.

  The transmission unit 32 includes a crystal resonator 35, a PLL (Phase Locked Loop) serving as a carrier generation unit that generates a carrier for accessing (reading / writing) the RFID tag information of the IC circuit unit 150 of the RFID circuit element To. ) 36, and a VCO (Voltage Controlled Oscillator) 37 and the generated carrier wave based on a signal supplied from the control circuit 4 (in this example, amplitude modulation based on a “TX_ASK” signal from the control circuit 4) ) Transmitting-side multiplication circuit 38 (carrier modulation means; however, in the case of amplitude modulation, an amplification factor variable amplifier or the like may be used), and the modulated wave modulated by this transmission-side multiplication circuit 38 is sent from the control circuit 4 And a variable transmission amplifier 39 that determines and amplifies the amplification factor based on the “TX_PWR” signal. The carrier wave is preferably set to be in the vicinity of 950 MHz or 2.45 GHz, and the modulated wave modulated by the transmission side multiplication circuit 38 and amplified by the variable transmission amplifier 39 passes through the transmission / reception separator 34 and the antenna 1 as transmission means. This is supplied to the IC circuit unit 150 of the RFID circuit element To.

  The receiving unit 33 multiplies the combined signal of the reception signal of the antenna 1 and the cancellation signal combined by the multiplexer 203 and the carrier wave generated by the transmission unit 32 to perform homodyne detection. A first bandpass filter 41 for extracting only a signal of a necessary band from the output of the first multiplier circuit 40, the reception-side first multiplier circuit 40, and an output of the first bandpass filter 41 are amplified and amplified. A first side amplifier 43 to be supplied to one limiter 42; a combined signal of the reception signal of the antenna 1 and the cancellation signal combined by the multiplexer 203; ° Multiplying the delayed carrier wave, the reception side second multiplication circuit 44 that performs homodyne detection, and extracting only the signal in the necessary band from the output of the reception side second multiplication circuit 44 A second band-pass filter 45, and a reception-side second amplifier 47 is supplied to the second limiter 46 amplifies inputs the output of the second band-pass filter 45. The signal “RXS-I” output from the first limiter 42 and the signal “RXS-Q” output from the second limiter 46 are input to the signal processing circuit 3 and processed.

  The combined signal of the reception signal of the antenna 1 and the cancellation signal combined by the multiplexer 203 is also input to an RSSI circuit (Received Signal Strength Indicator) 48, and the signal of these signals is input. A signal “RSSI” indicating the strength (received signal strength) is input to the signal processing circuit 3. In this way, in the interrogator 100 of this embodiment, the reflected wave from the RFID circuit element To is demodulated by IQ orthogonal demodulation.

  The signal processing circuit 3 inputs a received signal from the above-described high-frequency circuit receiving unit 33, performs predetermined arithmetic processing, and outputs a modulation control signal to the transmission-side multiplication circuit 38 of the transmitting unit 32 in response thereto. .

  The control circuit 4 includes a cancel signal amplitude control unit of the cancel circuit 200 according to the arithmetic processing result of the signal processing circuit 3 based on the RSSI signal from the RSSI circuit 48 (corresponding to the output signal from the multiplexer 203). An amplitude control signal, a phase control signal, and the like are output to 201 and the cancel signal phase control unit 202. The control circuit 4 is connected to, for example, a communication line via, for example, an input / output interface (not shown), a route server (not shown) connected to the communication line, another terminal, a general-purpose computer, an information server, and the like Information may be exchanged between the two.

  The greatest feature of this embodiment is that the interrogator 100 transmits a carrier wave from the transmitter 32 in the absence of reception of a reflected wave from the RFID circuit element To before transmitting / receiving RFID tag information to / from the RFID circuit element To. The control circuit 4 controls the amplitude control to the cancel signal amplitude control unit 201 and the cancel signal phase control unit 202 in accordance with a signal from the signal processing circuit 3 to which the RSSI signal is input at this time. The signal and the phase control signal are controlled to set an optimum value of the cancel signal (cancellation wave) having a phase and amplitude that can cancel the most unnecessary waves. The details will be described below.

  As described above, in order to cancel (cancel) an unnecessary wave that is generated when the transmission wave transmitted from the transmission unit 32 via the antenna 1 is received by the reception unit 33 from the antenna 1, the same phase as the unnecessary wave is generated. Therefore, it is sufficient to generate a canceling wave having an opposite amplitude. Therefore, it is necessary to match (match) the unnecessary wave in both the amplitude A and the phase P of the cancellation wave generated by the cancel circuit 200.

  FIG. 4 is an explanatory diagram for conceptually explaining the matching method of the amplitude A and the phase P of the cancellation wave in the present invention. FIG. 4 is a P-A diagram with the horizontal axis representing the value of amplitude A and the vertical axis representing the value of phase P. The optimum values of amplitude A and phase P of the canceling wave that can cancel the unwanted wave are shown in FIG. Is represented by one point on this PA diagram. In the present invention, in order to search and detect one point (optimum point), as shown in FIG. 4, within a predetermined range (Astart to Aend) of the amplitude A at a predetermined interval (ΔA1) and again of the phase P. A large number of monitor points are set at a predetermined interval (ΔP1) within a predetermined range (Pstart to Pend), and the received signal strength is measured sequentially from the RSSI circuit 48 at each point. Identify as

  In particular, in the present embodiment, first, as shown in FIG. 4, the primary search range (Astart to Aend) of the amplitude and the primary search range (Pstart to Pend) of the phase are relatively large, and the primary monitoring interval (ΔA1) of the amplitude. And the phase primary monitoring interval (ΔP1) is also set to be relatively large, and the search is relatively rough, and the optimum point (primary optimum point; amplitude Abest1, phase Pbest1) among these points is primarily identified (= rough) matching).

  After that, as shown in FIG. 5, the amplitude secondary search range (Astart to Aend) and the phase secondary search range (Pstart to Pend) are newly set smaller in the vicinity of the roughly determined primary optimum point. The amplitude secondary monitoring interval (ΔAmin) and the phase secondary monitoring interval (ΔPmin) are also set small and a precise search is performed, and the optimum point (final optimum point; amplitude Abest2, phase Pbest2) is selected from these points. ) Is finally identified (= fine matching).

  In the example shown in FIG. 5, the amplitude secondary search range is a region that is half of the amplitude primary monitor interval (= ΔA1 / 2) from the primary optimal value Abest1 of the amplitude, and the phase secondary search range is the phase secondary search range. In this example, the region is a half of the phase primary monitoring interval before and after the primary optimum value Pbest1 (= ΔP1 / 2). However, the present invention is not limited to this. In short, it is sufficient if the setting allows precise matching with a monitor interval narrower than the primary monitor interval in a range including the primary optimum point and narrower than the primary search range.

  FIG. 6 is a flowchart showing a control procedure executed by the control circuit 4 in order to realize the cancel signal generation as described above.

  In FIG. 6, first, in step S10, initialization related to the entire interrogator 100, such as resetting of various parameters, is performed at the start of control.

  Next, in step S100, a carrier wave is transmitted from the transmitting unit 32 of the high frequency circuit 2 via the antenna 1 without receiving a reflected signal from the RFID circuit element To, and at this time, received by the receiving unit 33. The received signal strength detected by the RSSI circuit 48 is input via the signal processing circuit 3. Then, the amplitude control signal and the phase control signal are output to the cancel signal amplitude control unit 201 and the cancel signal phase control unit 202 of the cancel circuit 200 so that the magnitude of the received signal intensity (the magnitude of the unnecessary wave) becomes small. Then, the amplitude / phase of the cancel signal (cancellation wave) generated from the cancel circuit 200 is adjusted. The adjustment in the cancel circuit 200 is efficiently performed by performing fine matching after the rough matching described above.

  Thereafter, in step S20, the final value of the received signal strength in the RSSI circuit 48 after the adjustment of the cancel circuit 200 is set as a threshold value in subsequent cancel signal control, and an appropriate location (for example, RAM Etc.).

  Thereafter, the process proceeds to step S30, where the current received signal strength in the RSSI circuit 48 is equal to or less than the threshold value set in step S20 + the predetermined margin value (= α%; α is about several percent to 20%, for example). Determine if it exists.

  If the determination in step S30 is satisfied, it is considered that canceling of the unnecessary wave by the cancel signal (cancellation wave) is appropriately performed at present, and the process proceeds to step S40.

  If the determination in step S30 is not satisfied, the process proceeds to step S200, where the cancel signal (cancellation wave) is considered to be slightly out of the state suitable for canceling the unnecessary wave, and the process proceeds to step S200. Fine adjustment of the cancel circuit 200 is performed. That is, the cancel signal phase control is performed so that the magnitude of the received signal detected by the RSSI circuit 48 is reduced while the carrier wave is transmitted from the transmitter 32 via the antenna 1 in the absence of reception of the reflected wave. A phase control signal is output to the unit 202, and the phase of the cancel signal (cancellation wave) generated from the cancel circuit 200 is adjusted. Thereafter, the process proceeds to step S60, and the current received signal strength in the RSSI circuit 48 is equal to the threshold value + predetermined margin value (= α%; α is a value different from step S30, as in step S30. It is determined whether or not If the determination in step S60 is not satisfied, the fine adjustment of the cancel circuit 200 as described above is not sufficient, and it is considered that the readjustment (readjustment) of the cancel circuit 200 is necessary again, and the process returns to step S100. Repeat the same procedure. If the determination in step S60 is satisfied, it is considered that the cancellation of the unwanted wave due to the cancel signal has returned to an appropriate state by fine adjustment of the cancel circuit 200, and the process proceeds to step S40.

  In step S40, the responder (wireless tag T) is accessed (communication) to the wireless tag circuit element To under the setting of the cancellation wave appropriately set as described above, and the wireless communication from the IC circuit unit 150 is performed. The tag information is read (or the wireless tag information is written to the IC circuit unit 150).

  When step S40 ends, the process proceeds to step S50, and it is determined whether or not to further communicate with another responder (wireless tag T). If communication with another wireless tag T is not performed, the determination is satisfied and this flow is terminated. If communication with another wireless tag T is performed, the process returns to step S30 and the same procedure is repeated.

  FIG. 7 is a flowchart showing a detailed control procedure in step S100 (cancellation circuit adjustment procedure) in FIG.

  In FIG. 7, first, in step S110, for example, a control signal is output to the reception-side first amplifier 43 and the second amplifier 47, and the gain of the combined signal output from them is adjusted.

  Next, in step S120, rough matching of both the amplitude A and phase P of the cancellation wave generated by the cancel circuit 200 is performed. That is, as described above with reference to FIG. 4, the amplitude and phase of the cancel signal (cancellation wave) are sequentially changed by the amplitude control signal and the phase control signal by increasing the primary search range and the primary monitoring interval of the amplitude and phase, respectively. Searching is performed roughly roughly, and among them, amplitude / phase values (primary optimal points) at which the received signal strength by the RSSI circuit 48 is minimized are identified.

  Thereafter, in step S140, fine matching is performed on both the amplitude A and phase P of the cancellation wave generated by the cancel circuit 200. That is, as described above with reference to FIG. 5, based on the results of the rough matching, the amplitude / phase secondary search range and the secondary monitoring interval are relatively reduced, and the amplitude control signal and the phase control signal are sequentially canceled. A precise search is performed by changing the amplitude and phase of the signal (cancellation wave), and among them, the value of the amplitude and phase (final optimum point) at which the received signal strength by the RSSI circuit 48 is minimized is identified.

  Thereafter, the process proceeds to step S160, and the cancel signal amplitude control unit is configured so that the final amplitude and phase optimum values identified in step S140 (the aforementioned amplitude Abest2 and phase Pbest2) are used as the final optimum values in the cancel circuit 200 as they are. The amplitude control signal and the phase control signal are output to 201 and the cancel signal phase control unit 202.

  In step S170, as in step S110, for example, the control signal is output again to the first amplifier 43 and the second amplifier 47 on the receiving side, the gain of the synthesized signal output from them is adjusted, and this flow ends. To do.

  FIG. 8 is a flowchart showing a more detailed control procedure of step S120 (rough matching of the cancel circuit) in FIG.

  In FIG. 8, first, in step S121, a received signal strength minimum value RSSImin1 that will be required later for calculation processing determination is set to an appropriate initial value (for example, a sufficiently large predetermined value).

  Thereafter, in step S122, the start value Astart = Amin of the primary search range of amplitude A, the end value Aend = Amax, and the primary monitor interval ΔA = ΔA1 are set, and the start value Pstart of the primary search range of phase P is set. = Pmin, end value Pend = Pmax, and the primary monitoring interval ΔP = ΔP1. The above-described Amin, Amax, ΔA1, Pmin, Pmax, and ΔP1 are, for example, predetermined predetermined values (may be set to be variable each time).

  In step S123, an amplitude control signal having an amplitude A = Astart of the cancel signal generated by the cancel circuit 200 is output to the cancel signal amplitude control unit 201, and a phase control signal having the phase P = Pstart is canceled signal phase control. To the unit 202.

  Thereafter, the process proceeds to step S124, where the received signal strength RSSIcur1 in the current RSSI circuit 48 is measured. In step S125, it is determined whether or not the measured value is smaller than the minimum received signal strength value RSSImin1.

  If the determination in step S125 is satisfied, at least in the monitoring results up to the present time, the optimum value related to the amplitude and phase is reached, and the process proceeds to step S126, where the amplitude value A at this time is the amplitude primary optimum value by rough matching. In addition to being set to Abest1, the phase value P at this time is set to the phase primary optimum value Pbest1 by rough matching, and the current received signal strength RSSIcur1 as a result is set as a new received signal strength minimum value RSSImin1. Then, the process proceeds to step S127.

  If the determination in step S125 is not satisfied, there are other optimum values related to the amplitude and phase in the monitoring results up to now, and the process directly proceeds to step S127 without passing through step S126.

  In step S127, it is determined whether or not the value of phase P has reached the end value Pend of the primary search range. If the determination is not satisfied, the process proceeds to step S128, the monitor interval ΔP is added to the value of the phase P, the process returns to step S124, and the same procedure is repeated. If the determination in step S127 is satisfied, the process moves to step S129. In step S129, it is determined whether or not the value of the amplitude A has reached the end value Aend of the primary search range. If the determination is not satisfied, the process moves to step S130, the monitor interval ΔA is added to the value of amplitude A, the value of phase P is returned to the primary search range start value Pstart in step S131, and then the same procedure is performed by returning to step S124. repeat.

  As described above, at a certain amplitude A value, step S124 → step S125 → (step S126) → step S127 → step S128 → step S125 →... Is repeated until P = Pend. Only the value increases from the start value Pstart in increments of ΔP to Pend (in FIG. 4 described above, one grid is formed from the lowest point of a certain A value column upward in FIG. 4 one by one. Equivalent to moving it). When P = Pend, the value of A is added by ΔA in step S127 → step S129 → step S130, and the process returns to step S124 via step S131. As a result, with the amplitude A value increased by ΔA, the value of the phase P is repeated until step S124 → step S125 → (step S126) → step S127 → step S128 → step S124 →... Only increases from the start value Pstart to Pend while increasing in increments of ΔP (in FIG. 4, grids one by one upward from the lowest point of the A value column shifted to the right by one from the aforementioned column) Is equivalent to moving). By repeating such a procedure until A = Aend, finally, all the monitor values in the primary search range of Astart to Aend for the amplitude A and all the monitor values in the primary search range of Pstart to Pend for the phase P are obtained. Each time, the value of the received signal strength RSSIcur1 at that time is measured, and the measured value is compared with the previous minimum value RSSImin1. If it is smaller than the previous value, the received signal strength at that time is overwritten and updated as the minimum value RSSImin1, and the amplitude value A and the amplitude value P at that time are overwritten and updated as the optimum amplitude value Abest1 and the optimum phase value Pbest1, respectively. Rough matching is performed as a rough primary search.

  FIG. 9 is a flowchart showing a more detailed control procedure of step S140 (fine matching of the cancel circuit) in FIG.

  In FIG. 9, first, in step S141, a minimum received signal strength value RSSImin2 that will be required later in determining the arithmetic processing is set to an appropriate initial value (for example, a sufficiently large predetermined value).

  Thereafter, in step S142, the start value of the secondary search range of the amplitude A is set to Astart = Abest1-ΔA1 / 2, end value Aend = using the amplitude optimum value Abest1 and the primary monitoring interval ΔA1 in the rough matching. Abest1 + ΔA1 / 2, the secondary monitoring interval ΔA = ΔAmin (for example, the smallest unit possible in the system) is set, and the start value of the secondary search range of the amplitude P is set to the phase optimum in the rough matching Using the value Pbest1 and the primary monitoring interval ΔP1, Pstart = Pbest1−ΔP1 / 2, end value Pend = Pbest1 + ΔP1 / 2, and the secondary monitoring interval ΔP = ΔPmin (for example, the smallest possible on the system) Unit).

  Then, in step S143, as in step S123 of FIG. 8, the cancel control signal amplitude control signal with amplitude A = Astart is output to the cancel signal amplitude control unit 201, and the phase control signal with phase P = Pstart is canceled. Output to the signal phase control unit 202.

  Thereafter, the process proceeds to step S144, where the current received signal strength RSSIcur2 in the RSSI circuit 48 is measured, and in step S145, it is determined whether or not the measured value is smaller than the minimum received signal strength value RSSImin2.

  If the determination in step S145 is satisfied, at least the current (fine matching) monitoring result is the optimum value related to the amplitude and phase, and the process proceeds to step S146, where the amplitude value A at this time is the fine matching. Is set to the second-order optimal amplitude value Abest2 and the second-phase optimum value Pbest2 by fine matching is set. Further, the current received signal strength RSSIcur2 as a result is a new received signal. The strength minimum value RSSImin2 is set, and the process proceeds to step S147.

  If the determination in step S145 is not satisfied, there are other optimum values related to the amplitude and phase in the monitoring results (of fine matching) up to the present, and the process directly proceeds to step S147 without passing through step S146.

  In step S147, it is determined whether or not the value of the phase P has reached the end value Pend of the secondary search range. If the determination is not satisfied, the process proceeds to step S148, the monitor interval ΔP is added to the value of the phase P, the process returns to step S144, and the same procedure is repeated. If the determination in step S147 is satisfied, the process moves to step S149. In step S149, it is determined whether the value of the amplitude A has reached the end value Aend of the secondary search range. If the determination is not satisfied, the process proceeds to step S150, the monitor interval ΔA is added to the value of amplitude A, the value of phase P is returned to the secondary search range start value Pstart in step S151, and then the process returns to step S144 to perform the same procedure. repeat.

  As described above, in the vicinity of the primary optimum values Abest1 and Pbest1 roughly identified by the rough matching, first, at a certain amplitude A value, step S144 → step S145 → (step S146) → step S147 → step until P = Pend. S148 → step S144 →... Are repeated, and only the value of the phase P is increased from the start value Pstart to Pend in increments of ΔP with the same amplitude A (in FIG. This corresponds to moving the lattice one by one from the lowest point of FIG. When P = Pend, the value of A is added by ΔA in step S147 → step S149 → step S150, and the process returns to step S144 via step S151. As a result, with the amplitude A value increased by ΔA, step S144 → step S145 → (step S146) → step S147 → step S148 → step S144 →... Only increases from the start value Pstart to Pend while increasing in increments of ΔP (in FIG. 5, grids one by one upward from the lowest point of the A value column shifted to the right by one from the aforementioned column) Is equivalent to moving). By repeating such a procedure until A = Aend, finally, all monitor values in the secondary search range of Astart to Aend for the amplitude A and all monitors of the secondary search range of Pstart to Pend for the phase P In the value, the value of the received signal strength RSSIcur2 at that time is measured each time, and the measured value is compared with the previous minimum value RSSImin2. If it is smaller than the previous value, the received signal strength at that time is overwritten and updated as the minimum value RSSImin2, and the amplitude value A and the amplitude value P at that time are overwritten and updated as the optimum amplitude value Abest2 and the optimum phase value Pbest2, respectively. Fine matching is performed as a final search.

  FIG. 10 is a flowchart showing a detailed control procedure of step S200 (fine adjustment of the cancel circuit) in FIG. The fine adjustment of the cancel circuit is relatively similar to the fine matching procedure shown in FIG. 9, and a search for a relatively small fine adjustment search range is performed at a relatively small monitor interval for only the phase of the cancel signal. Is what you do.

  In FIG. 10, first, in step S210, the received signal strength RSSIcur3 in the current RSSI circuit 48 is measured.

  Next, in step S220, the minimum received signal strength value RSSImin3 that will be required later in the calculation processing determination is set to an appropriate initial value (for example, a sufficiently large predetermined value).

  Thereafter, in step S230, the search range for fine adjustment of the phase P is determined by using the current amplitude value Pcur and the primary phase monitoring interval ΔP1 in the rough matching as a start value Pstart = Pcur−ΔP1 / 2, and an end value. Pend = Pcur + ΔP1 / 2, and the fine adjustment monitor interval ΔP = ΔPmin (for example, the smallest unit possible in the system, but may be set to a value different from that for fine matching).

  In step S240, a phase control signal for setting the phase P of the cancel signal P = Pstart is output to the cancel signal phase control unit 202.

  Thereafter, the process proceeds to step S250, where the current received signal strength RSSIcur3 in the RSSI circuit 48 is measured, and in step S260, it is determined whether or not the measured value is smaller than the received signal strength minimum value RSSImin3.

  If the determination in step S260 is satisfied, the process proceeds to step S270, where the phase value P at this time is set to the phase optimum value Pbest3 after fine adjustment, and the current received signal strength RSSIcur3 as a result is newly received. The minimum signal strength value RSSImin3 is set, and the process proceeds to step S280.

  If the determination in step S260 is not satisfied, the process directly proceeds to step S280 without passing through step S270.

  In step S280, it is determined whether or not the value of the phase P has reached the end value Pend of the fine adjustment search range. If the determination is satisfied, this flow ends. If the determination is not satisfied, the process proceeds to step S290, the monitor interval ΔP is added to the value of the phase P, the process returns to step S250, and the same procedure is repeated.

  Thus, in the vicinity of the current phase value Pcur, step S250 → step S260 → (step S270) → step S280 → step S290 → step S250 →... Only the value of is increased from the start value Pstart in increments of ΔP to Pend. As a result, the value of the received signal strength RSSIcur3 at that time is measured each time in all monitor values of the fine adjustment search range of Pstart to Pend for the phase P, and the measured value is the minimum value until then. Compared with the value RSSImin3. If it is smaller than the previous value, the received signal strength at that time is overwritten and updated as the minimum value RSSImin3, and the phase value P at that time is overwritten and updated as the optimum phase value Pbest3, respectively, and fine adjustment of the cancel circuit 200 is executed. The In the above, only the phase P of the cancel circuit 200 is adjusted during fine adjustment. However, the adjustment is not limited to this, and only the amplitude A may be adjusted, or both the phase P and the amplitude A may be adjusted. Also good. In any case, it is preferable that at least one of the phase P and the amplitude A is adjusted with a smaller search range and with a smaller monitoring interval than the rough matching at the time of adjustment of the cancel circuit 200 described above.

  FIG. 11 is a diagram illustrating an example of the behavior of the detected received signal strength of the RSSI circuit 48 realized as a result of the control as described above. The horizontal axis represents time, and the vertical axis represents received signal strength.

  In FIG. 11, the cancellation signal is first adjusted from the initial value of the received signal strength (see step S100 in FIG. 6), so that the received signal strength is once significantly reduced ((A) in the figure). Thereafter, when the received signal strength value fluctuates due to a change in the surrounding environment and the threshold value exceeds the above-mentioned α% ((A) in the figure), the cancel circuit is finely adjusted (see step S200 in FIG. 6). As a result, the value of the received signal strength returns to a value smaller than the threshold value again ((c) in the figure). Thereafter, when the received signal strength value fluctuates again and greatly exceeds the threshold value ((D) in the figure), the cancel circuit is finely adjusted in the same manner as described above. If the value does not fall below the value + α% ((v) in the figure), the same cancel circuit adjustment (step S100 in FIG. 6) as that at the beginning is performed, whereby the received signal strength value returns to a value smaller than the threshold value. ((F) in the figure).

  In the above, the control circuit 4 outputs the carrier wave of the carrier wave generation means from the carrier wave output means before outputting the transmission wave modulated by the carrier wave modulation means from the carrier wave output means and transmitting from the transmission means according to each claim. Then, the carrier wave generating means and the transmission means are set so that the optimum value is set by changing the phase and amplitude of the cancellation wave generated from the cancellation wave generating means according to the detection result of the signal intensity detecting means. And canceling wave control means for controlling the canceling wave generating means.

  In addition, the flow (rough matching) procedure shown in FIG. 8 executed by the control circuit 4 makes the phase and amplitude of the cancellation wave a pair, and compares these values within a relatively large first range (primary search range). First, the detection values of the signal intensity detection means in each pair are sequentially obtained by changing at a first large interval (primary monitoring interval), and a first optimal value for a pair of phases and amplitudes in the first range is searched. The flow (fine matching procedure) shown in FIG. 9 corresponds to one search means, and a pair of phases and amplitudes are compared with each other in a relatively small second range (secondary search range) near the primary optimum value. By changing the interval of 2 (secondary monitoring interval), the detection values of the signal intensity detection means in each pair are sequentially acquired, the final optimum value in the second range is searched, and this is selected as the set value Corresponds to the second search means .

  Of the control procedures executed by the control circuit 4, step S30 shown in FIG. 6 has already been set for at least one of the phase and amplitude of the canceling wave in the canceling wave generating means according to the detection result in the signal intensity detecting means. A first determination means for determining whether or not to change the set value, the threshold value + α% used in the determination in step S30 is set to an optimum value related to a pair of phase and amplitude. This corresponds to the first threshold value for the received signal strength set correspondingly.

  Further, the flow (cancellation circuit fine adjustment) procedure shown in FIG. 10 executed by the control circuit 4 changes the setting of at least one of the phase and the amplitude when the determination by the first determination unit is satisfied. This corresponds to control signal output means for outputting a signal for controlling the cancellation wave generating means.

  Step S60 of the flow shown in FIG. 6 executed by the control circuit 4 satisfies the determination by the first determination unit, and at least one of the phase and amplitude of the cancellation wave generation unit is determined by the signal from the control signal output unit. After the setting is changed, it corresponds to a third determination means for determining whether or not to change the set values of the cancellation wave phase and amplitude in the cancellation wave generating means again according to the detection result of the signal intensity detection means. Further, immediately after the control operation by the cancellation wave control means is performed in step S40, the transmission wave is transmitted from the transmission means to the responder, and the response signal transmitted from the responder according to the transmitted transmission wave is received by the reception means. It corresponds to transmission / reception control means for controlling the transmission means and the reception means so as to receive.

  In the interrogator 100 of the present embodiment configured as described above, the cancel circuit 200 is adjusted in step S100 before starting the main communication with the wireless tag T in step S40 of the flow of FIG. A carrier wave (not modulated) is output from the transmitter 32 of the circuit 2 and transmitted from the antenna 1. An unnecessary wave is generated based on the transmission signal at this time, and a predetermined reception signal intensity may be generated in the reception unit 33 of the high-frequency circuit 2, but this is canceled by the cancellation wave generated by the cancellation circuit 200. The canceled received signal intensity is detected by the RSSI circuit 48, and the control circuit 4 outputs a control signal to the cancel signal amplitude control unit 201 and the cancel signal phase control unit 202 of the cancel circuit 200 according to the detection result to cancel the cancel wave. Are set to optimum values so that the received signal intensity is minimized.

  As described above, before the interrogator 100 and the wireless tag T start the main communication, the phase and amplitude of the canceling wave of the cancel circuit 200 are always adjusted and set so as to be optimal values each time. Therefore, unlike the prior art in which periodic adjustment is performed manually every year, for example, unnecessary waves can be sufficiently canceled in response to changes in the surrounding environment in real time. As a result, high reception sensitivity can be maintained, so that the reception signal (response signal) from the wireless tag T can be more clearly acquired after the main communication with the wireless tag T is started in step S40 of the flow of FIG. . In particular, since the main communication (transmission wave transmission and response signal reception) is performed in step S40 immediately after the cancellation circuit 200 is adjusted in step S100 of FIG. 6, the effect of the cancellation wave optimization by the control circuit 4 is reduced. It is possible to communicate with the wireless tag T while making the most of it.

  In the adjustment of the cancel circuit 200, first, the first optimum values Pbest1 and Abest1 of the phase P and the amplitude A are roughly searched in the primary search range by the rough matching described above, and then the secondary search is performed more precisely by fine matching. By searching for the final optimum values Pbest2 and Abest2 in the range, the phase P and the amplitude A of the canceling wave can be efficiently and in a short time compared with the case where a precise optimum value is searched from the beginning, with less calculation processing load. The final optimal value can be obtained.

  Further, even after the cancellation circuit 200 is adjusted as described above, if the received signal strength is greater than the threshold value + α%, at least either the phase P or the amplitude A of the cancellation wave is detected in step S30 in FIG. It is determined that the set value should be changed, and at least the set value of either the phase P or the amplitude A of the cancellation wave (only the phase P in the above example) is changed in step S200. As a result, the initially set phase P (or amplitude A) can be finely adjusted according to changes in the environment, etc., as needed. Further, even after fine adjustment is performed in this manner, it is determined whether or not the set value of the phase P (or amplitude A) should be changed again in step S60. It is possible to cope with a case where the adjustment is not sufficient, and to make a correct correction.

  In the above embodiment, as described with reference to FIG. 6, one threshold value is set, and if this threshold value + α% is exceeded after adjustment of the cancellation circuit 200, the cancellation circuit 200 is finely adjusted. I did it, but it is not limited to this. Hereinafter, a modification in which two threshold values are set and fine adjustment and readjustment of the cancel circuit 200 are performed according to comparison with the threshold values will be described with reference to FIGS. Parts equivalent to those in the above embodiment and control procedures are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 12 is a flowchart showing a control procedure executed by the control circuit 4 in this modification, and corresponds to FIG. 6 described above.

  In FIG. 12, first, in step S10 and step S100, initialization of the entire interrogator 100 and adjustment of the cancel circuit 200 similar to those in FIG. 6 are performed, and then the process proceeds to newly provided step S300.

  In step S300, the current received signal strength in the RSSI circuit 48 is measured, and + x% is set to the first threshold value and + y% is set to the second threshold value (x and y are, for example, several% to 20%, respectively). It is determined whether x <y) or less with a value of about%.

  Thereafter, in step S310, it is determined whether or not the current received signal strength in the RSSI circuit 48 is equal to or lower than the second threshold value set in step S300.

  If the determination in step S310 is not satisfied, the received signal strength is greater than the relatively large second threshold value, and therefore it is considered that the adjustment (re-adjustment) of the cancel circuit 200 is necessary again. Returning to step S100, the same procedure is repeated. When the determination in step S310 is satisfied, the process proceeds to next step S320.

  In step S320, it is determined whether the current received signal strength in the RSSI circuit 48 is equal to or less than the first threshold value set in step S300.

  If the determination in step S320 is not satisfied, the process proceeds to step S200 similar to FIG. 6 described above, and it is considered that the cancel signal (cancellation wave) is slightly out of the state suitable for canceling the unnecessary wave. After fine adjustment of the cancel circuit 200, the process proceeds to step S40.

  When the determination in step S320 is satisfied, it is considered that canceling of the unnecessary wave by the cancel signal (cancellation wave) is appropriately performed at present, and the process proceeds to step S40 without passing through step S200.

  Steps S40 and S50 are the same as in FIG. 6 described above, and access (communication) of the responder (wireless tag T) to the wireless tag circuit element To under the setting of the cancellation wave appropriately set as described above. ), It is determined whether or not to perform further communication with another responder (wireless tag T). If communication with another wireless tag T is not performed, the determination is satisfied and this flow is terminated. If communication with another wireless tag T is performed, the process returns to step S310 and the same procedure is repeated.

  FIG. 13 is a diagram illustrating an example of the behavior of the detected received signal strength of the RSSI circuit 48 realized as a result of the control as described above, and corresponds to FIG. 11 of the above embodiment.

  In FIG. 13, the cancellation signal is first adjusted from the initial value of the received signal strength (see step S100 in FIG. 12), so that the received signal strength is once significantly reduced ((A) in the figure). Thereafter, when the received signal strength value fluctuates due to a change in the surrounding environment or the like and exceeds the first threshold value ((i ′) in the figure), fine adjustment of the cancel circuit (step S320 → step S200 in FIG. 12). As a result, the value of the received signal strength returns to a value smaller than the threshold value again ((c) in the figure). Thereafter, when the received signal strength value fluctuates again and exceeds the first threshold value and further the second threshold value ((D ') in the figure), the same cancel circuit adjustment as in the beginning (step of FIG. 12) S100) is performed, whereby the value of the received signal strength returns to a value smaller than the threshold value, and the values of the first and second threshold values are also restored according to the value of the received signal strength at that time. The setting is updated ((K ') in the figure).

  In the above, step S320 of the flow shown in FIG. 12 executed by the control circuit 4 is based on the phase and amplitude of the canceling wave in the canceling wave generating means according to the detection result in the signal intensity detecting means described in each claim. This corresponds to first determination means for determining whether or not to change a setting value that has already been set for at least one, and before step S310 is determined by the first determination means, the phase of the cancellation wave in the cancellation wave generation means. This corresponds to second determination means for determining whether or not to change the set value that has already been set for at least one of the amplitude and the amplitude.

  Also in this modification, the same effect as the above embodiment is obtained.

  Further, in addition to this, before step S320 for determining whether or not fine adjustment of the cancel circuit 200 is performed, a step S310 for determining whether or not adjustment (readjustment) of the cancel circuit 200 is performed is provided. Therefore, in step S310, it is determined whether or not it is necessary to reconfigure the setting largely (reset as much as the initial setting performed before this communication). If this determination is not satisfied, step S310 is performed. Even if it is not as much as described above in S320, it is possible to share the role of determining whether or not fine adjustment of the setting is necessary. By dividing the determination of the necessity of correction and the correction procedure according to how much correction is necessary for the set values of the phase P and the amplitude A, the canceling wave can be efficiently performed in a short time and with a small calculation processing load. It is possible to correct the set values of the phase and amplitude.

  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 system configuration figure showing the whole outline of a radio communications system provided with an interrogator by one embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a functional configuration of a wireless tag circuit element provided in the wireless tag illustrated in FIG. 1. It is a functional block diagram showing the functional structure of the high frequency circuit with which the interrogator was equipped. It is explanatory drawing for demonstrating notionally the amplitude and phase matching method (rough matching) of the cancellation wave in this invention. It is explanatory drawing for demonstrating notionally the amplitude and phase matching method (fine matching) of the cancellation wave in this invention. It is a flowchart showing the control procedure which the control circuit shown in FIG. 1 performs. It is a flowchart showing the detailed control procedure of step S100 in FIG. It is a flowchart showing the further detailed control procedure of step S120 in FIG. It is a flowchart showing the further detailed control procedure of step S140 in FIG. It is a flowchart showing the detailed control procedure of step S200 in FIG. It is a figure showing an example of the behavior of the detection received signal strength of an RSSI circuit. It is a flowchart showing the control procedure which a control circuit performs in the modification which sets two threshold values and performs fine adjustment and readjustment of a cancellation circuit according to the comparison with it. It is a figure showing an example of the behavior of the detection received signal strength of an RSSI circuit.

Explanation of symbols

1 Antenna (transmitting means, receiving means)
4 Control circuit (cancellation wave control means)
32 Transmitter (carrier output means)
33 Receiver 34 Transmitter / receiver separator (transmitting means, receiving means)
35 Crystal resonator (carrier wave generation means)
36 PLL (carrier generation means)
37 VCO (carrier generation means)
38 Transmission side multiplication circuit (carrier modulation means)
48 RSSI circuit (signal strength detection means)
100 Interrogator 200 Cancellation circuit (cancellation wave generating means)
S wireless communication system T wireless tag (responder)

Claims (12)

Carrier generation means for generating a carrier wave for accessing the transponder, and carrier wave modulation means for modulating the carrier wave generated from the carrier wave generation means to obtain a modulated carrier wave, the carrier wave generation means or the carrier wave modulation Carrier wave output means for outputting a carrier wave from the means;
Transmission means capable of transmitting the carrier wave output from the carrier wave output means to the responder;
Receiving means capable of receiving a transmission signal from the responder in response to a transmission signal from the transmission means;
Canceling wave generating means for generating a canceling wave for canceling an unnecessary wave that may be generated based on a transmission signal from the transmitting means at the time of signal reception by the receiving means;
Signal strength detecting means for detecting the received signal strength of the receiving means canceled by the canceling wave from the canceling wave generating means;
Prior to outputting the transmission wave modulated by the carrier wave modulation means from the carrier wave output means and transmitting from the transmission means, the carrier wave of the carrier wave generation means is output from the carrier wave output means and transmitted from the transmission means, The carrier wave generation unit, the transmission unit, and the transmission unit are configured to change the phase and amplitude of the cancellation wave generated from the cancellation wave generation unit according to the detection result of the signal intensity detection unit, and to set an optimum value. An interrogator for a wireless communication system, comprising cancellation wave control means for controlling cancellation wave generation means.   Carrier generation means for generating a carrier wave for accessing the transponder, and carrier wave modulation means for modulating the carrier wave generated from the carrier wave generation means to obtain a modulated carrier wave, the carrier wave generation means or the carrier wave modulation Carrier wave output means for outputting a carrier wave from the means;
  Transmission means capable of transmitting the carrier wave output from the carrier wave output means to the responder;
  Receiving means capable of receiving a transmission signal from the responder in response to a transmission signal from the transmission means;
  Canceling wave generating means for generating a canceling wave for canceling an unnecessary wave that may be generated based on a transmission signal from the transmitting means at the time of signal reception by the receiving means;
  Signal strength detecting means for detecting the received signal strength of the receiving means canceled by the canceling wave from the canceling wave generating means;
  Prior to outputting the transmission wave modulated by the carrier wave modulation means from the carrier wave output means and transmitting from the transmission means, the carrier wave of the carrier wave generation means is output from the carrier wave output means and transmitted from the transmission means, The carrier wave generating means is configured to change the phase and amplitude of the cancellation wave generated by the cancellation wave generating means in accordance with the detection value variation based on the detection result of the signal intensity detection means and to set an optimum value. An interrogator for a radio communication system, comprising: a transmission means; and a cancellation wave control means for controlling the cancellation wave generation means. The interrogator of the wireless communication system according to claim 1 or 2 ,
The canceling wave control means changes the phase and amplitude of the canceling wave by the canceling wave generating means so as to reduce the detection value of the signal intensity detecting means, and sets an optimum value. Interrogator for communication systems. The interrogator of the wireless communication system according to claim 3 ,
The cancellation wave control means includes
The phase and amplitude of the cancellation wave are paired, and their values are changed at a relatively large first interval within a relatively large first range, and the detection values at the signal intensity detecting means in each pair are sequentially obtained. First searching means for searching for a first optimal value of the pair of phases and amplitudes in the first range;
The pair of phases and amplitudes are changed at relatively small second intervals within a relatively small second range in the vicinity of the primary optimum value, and the detection values of the signal intensity detection means in each pair are sequentially acquired. And a second search means for searching for a final optimum value within the second range and selecting it as a set value. The interrogator of the wireless communication system according to any one of claims 1 to 4 ,
The cancellation wave control means includes
First determination means for determining whether to change a setting value already set for at least one of the phase and amplitude of the cancellation wave in the cancellation wave generation means in accordance with a detection result of the signal intensity detection means; An interrogator for a wireless communication system, comprising: The interrogator of the wireless communication system according to claim 5 ,
The first determination means includes a first threshold value related to the received signal strength that is set correspondingly after the optimum values related to the pair of phases and amplitudes are set, and detection by the signal strength detection means. The interrogator of the wireless communication system, wherein the interrogator compares the value and determines whether the detected value is greater than the first threshold value. The interrogator of the wireless communication system according to claim 6 ,
The cancellation wave control means includes
Second determination means for determining whether or not to change the set value already set for at least one of the phase and amplitude of the cancellation wave in the cancellation wave generation means before the determination by the first determination means An interrogator for a wireless communication system, comprising: The interrogator of the wireless communication system according to claim 7 ,
The second determination means includes a second threshold value set larger than the first threshold value related to the received signal strength, which is set correspondingly after the optimum value related to the pair of phases and amplitudes is set. The interrogator of the wireless communication system, wherein the interrogator compares the detection value of the signal intensity detection means and determines whether the detection value is larger than the second threshold value. The interrogator of the wireless communication system according to any one of claims 5 to 8 ,
Control signal output means for outputting a signal for controlling the cancellation wave generating means so as to change the setting of at least one of the phase and the amplitude when the determination by the first determination means is satisfied; An interrogator for a wireless communication system. The interrogator of the wireless communication system according to claim 9 ,
The first determination unit determines whether to change the setting of the phase of the cancellation wave in the cancellation wave generation unit according to the detection result of the signal intensity detection unit,
The control signal output means outputs a signal for controlling the cancellation wave generating means so as to change the setting of the phase when the determination by the first determination means is satisfied. System interrogator. The interrogator of the wireless communication system according to claim 10 ,
After the determination by the first determination unit is satisfied and at least one of the phase and the amplitude of the cancellation wave generation unit is changed by a signal from the control signal output unit, the signal strength detection unit An interrogator for a wireless communication system, comprising: a third determination unit that determines whether to change again the set values of the phase and amplitude of the cancellation wave in the cancellation wave generation unit according to a detection result. The interrogator of the wireless communication system according to any one of claims 1 to 5 ,
Immediately after performing the control operation by the cancellation wave control means, the transmission wave is transmitted from the transmission means to the responder, and the response signal transmitted from the responder according to the transmitted transmission wave is received. An interrogator for a wireless communication system, comprising: the transmission means and a transmission / reception control means for controlling the reception means so as to be received by the means.

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