JP2007158546A - Rfid system with power control function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an interrogator for improving the possibility of communication with a prescribed RF tag by reducing interference under an environment wherein direct waves and indirect waves or the like are intermingled and to provide a communication method. <P>SOLUTION: The interrogator is configured with: an interrogator main body; an antenna; and an adjustment unit located in a transmission reception path between the antenna and the interrogator main body and controlling the gain and the phase. A voltage controlled variable attenuator as an example is used for the adjustment unit. Further, controlling the gain and the phase temporally at random can reduce interference and improve the possibility of communication with the RF tag. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an RFID (Radio Frequency Identification) system. More specifically, the present invention relates to an interrogator and a communication method for communicating with an RF tag.

  The RFID system is a system for exchanging information by performing wireless communication between a reader / writer serving as an interrogator and an RF tag serving as a responder. FIG. 1 is a diagram showing an example of a conventional RFID system. As shown in FIG. 1, an interrogator body (101), an antenna (102) connected to the interrogator body for transmitting and receiving radio waves, and communication with the interrogator based on radio waves from the antenna (102). RF tag (103) to be performed.

  For example, such an RFID system is used for physical distribution management in a factory. That is, an RF tag is affixed to an object as a product, the object with the tag affixed is moved on a belt conveyor, etc., and the RF tag is communicated with an interrogator installed in the middle of the object. Product management is done in

  FIG. 2 shows an example of an RFID system in physical distribution management in a factory. The interrogator (200) of FIG. 2 emits radio waves for performing communication. Here, for example, when the RF tag (201C) responds to the interrogator, in addition to the direct wave in which the radio wave is directly transmitted to the interrogator, the question is reflected on other RF tags or walls. Various radio waves are sent to the interrogator (200) such as an indirect wave (multipath) in which the radio wave reaches the instrument, or a response from another RF tag (201A). As described above, since the interrogator (200) receives various radio waves, there is a problem that interference cannot occur and satisfactory communication cannot be performed with a tag that desires communication.

Patent Document 1 discloses an invention related to an article management shelf that prevents interference based on electromagnetic induction between loop antennas arranged on a plurality of shelves. The invention of this Patent Document 1 is to prevent a malfunction based on electromagnetic induction between a plurality of shelves by attenuating supplied power in an antenna portion of a reader / writer that performs wireless communication with an IC card attached to an article. By providing this attenuator, interference between antennas can be prevented.
JP 2001-348111 A

  However, the invention of Patent Document 1 is merely a technique for preventing interference between loop antennas, and there is a problem that interference in communication with a plurality of RF tags cannot be avoided. That is, an RF tag in a logistics system or the like is moving on a belt conveyor or the like, and is in a complicated radio wave environment in which direct waves and indirect waves dynamically change. Under such circumstances, there is a problem that it is difficult to prevent interference because it is difficult to predict the radio wave environment.

  Accordingly, the present invention has been made in view of such problems, and has improved the feasibility of communication with a predetermined RF tag by reducing interference in an environment where direct waves and indirect waves are mixed. An object is to provide an interrogator and a communication method.

  Therefore, in the present invention, in order to solve such a problem, an interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag, an antenna for communicating with the RF tag, Provided is an interrogator having a gain adjuster arranged in a transmission / reception path between an antenna and an interrogator body to control a transmission / reception gain.

  As another invention, an interrogator body for outputting a signal to or obtaining a signal from an RF tag, an antenna for communicating with the RF tag, and the antenna and the interrogator body An interrogator having a phase adjuster arranged in a transmission / reception path to control a transmission / reception phase is provided.

  The gain adjuster and the phase adjuster may control gain and the like based on time information, a predetermined random number, and the like. Further, the gain adjuster and the phase adjuster may have a voltage controlled variable attenuation circuit.

  The present invention inserts a device for controlling the transmission / reception gain and transmission / reception phase between the interrogator body and the antenna, so that the direct wave and the indirect wave cannot be predicted, such as logistics management in a factory. Even in the case of being sent to the device, it is possible to reduce the interference and improve the feasibility of communication with the RF tag. Moreover, since such a function can be realized only by inserting a regulator between the conventional interrogator body and the antenna, interference can be reduced at low cost.

  Hereinafter, embodiments of each invention will be described. Note that the present invention is not limited to these embodiments, and can be implemented in various modes without departing from the spirit of the present invention.

In addition, the relationship between the following embodiment and a claim is as follows.
The first embodiment will mainly describe claims 1, 2, 4, 10, and the like. In the second embodiment, claims 3 and 11 will be mainly described. In the third embodiment, claims 4 and 12 will be mainly described. The fourth embodiment will mainly describe claims 5, 6, and 13. In the fifth embodiment, claims 7 and 14 will be mainly described. In the sixth embodiment, claims 8 and 15 will be mainly described. In the seventh embodiment, claims 9 and 16 will be mainly described.

<< Embodiment 1 >>
<Outline of Embodiment 1>
The present embodiment relates to an interrogator in which a gain adjuster for controlling transmission / reception gain is provided between an interrogator body and an antenna.

<Configuration of Embodiment 1>
FIG. 3 shows an example of a functional block diagram of the first embodiment. As shown in FIG. 1, the “interrogator” (300) of the first embodiment includes an “interrogator body” (301), an “antenna” (302), and a “gain adjuster” (303). . FIG. 3 is characterized by having a gain adjuster (303) in addition to the conventional example shown in FIG.

  The “interrogator body” (301) outputs a signal to the RF tag or acquires a signal from the RF tag. As an example, the interrogator body is composed of a control processor, ROM, RAM, modulator, and the like, and a conventionally used interrogator called a reader / writer can be used. . As the “RF tag” (310), an RF tag such as a non-contact tag that has been conventionally used can be used as in the interrogator body (301). When a signal is output from the interrogator body (301) to the RF tag or a signal is acquired from the RF tag, the interrogator body and the antenna (302) having a feeding point are used. .

  The “antenna” (302) is for communicating with the RF tag. As an example, communication with the RF tag is performed using a frequency such as a 2.45 GHz band or a UHF band. As for this antenna, a dipole antenna that has been conventionally used can be used as well as the interrogator body and the RF tag.

  The “gain adjuster” (303) is arranged in the transmission / reception path between the antenna (302) and the interrogator body (301) to control the transmission / reception gain. The “transmission / reception gain” is a gain at the time of transmission or a gain at the time of reception, and examples thereof include a power gain and a directivity gain. By controlling such a transmission / reception gain, communication with the RF tag can be appropriately realized even in an environment where the communication path dynamically changes over time.

  As already described, the first embodiment assumes a case where an RF tag is used in an automated production line such as a factory as shown in FIG. In this way, the RF tag moving on the belt conveyor on the production line receives not only direct waves but also indirect waves reflected on other objects and factory walls. Due to the deviation, a phenomenon in which communication with the RF tag cannot be performed occurs. Here, this phenomenon can be avoided by controlling the transmission / reception gain. For example, by performing power control using a variable attenuator or the like, it is possible to reduce interference and improve the feasibility of communication between the interrogator and an arbitrary RF tag. Details will be described later.

  FIG. 4 is a block diagram illustrating an example of the gain adjuster in the first embodiment in more detail. As shown in FIG. 4, the “gain adjuster” (403) includes a “time information holding unit” (404) and a “time corresponding gain control unit” (405).

  The “time information holding unit” (404) holds time information. An example of the time information holding unit is a built-in clock of a gain adjuster. Further, it is not always necessary to have a clock function. For example, a clock circuit that generates a predetermined clock frequency may be the time information holding unit.

  The “time-dependent gain control means” (405) outputs a control command for temporally changing the transmission / reception gain based on the time information. A specific example of changing the transmission / reception gain is to change the transmission power from the interrogator to the transponder. “Change in time” means, for example, as shown in FIG. 5, changing the timing at which the gain (transmission power in FIG. 5) is changed as time elapses. As will be described later, the change in the magnitude of the gain can be controlled by the random gain control means described in the second embodiment. The “control command” is output to, for example, the inside of the gain adjuster, and as a result, processing for changing the transmission / reception gain is performed. Specifically, the control command is output to the voltage controlled variable attenuation circuit. That is, as shown in FIG. 6, the gain adjuster (610) may have a first voltage controlled variable attenuation circuit (611) in addition to the configuration of FIG. The “first voltage control type variable attenuation circuit” (611) is for controlling the transmission / reception gain based on the control command. That is, the gain can be controlled by changing the attenuation amount based on the control command. By having such a voltage-controlled variable attenuation circuit, for example, the transmission power is changed by changing the control voltage as a control command, and as a result, the signal-to-noise ratio of the RF tag on the receiver side is changed. (Signal to NOISE ratio, S / N ratio) and RF tag noise figure (NOISE Figure, NF) can be changed. This is equivalent to changing the propagation loss of the communication line or increasing / decreasing ambient noise. In this way, by controlling the attenuation amount randomly in time, radio waves arrive only in a predetermined RF tag in the form of a direct wave or an indirect wave. Therefore, an RF tag that responds to communication from an interrogator is substantially used. Therefore, it is possible to reduce interference caused by response radio waves emitted from other RF tags. FIG. 7 is a graph schematically showing this state. As shown in FIG. 7, the S / N ratio of the RF tag is changed by controlling the attenuation amount randomly in time. For example, at the point of time t in FIG. 7, the RF tag A deteriorates the S / N ratio. However, since the RF tag B has an S / N ratio that allows communication, the RF tag B can only communicate with the RF tag B at the time t.

  Note that, as in the prior art, adjusting the communication environment using an attenuator (attenuator) is effective only when the surrounding object is static, but as the present invention assumes, When the object is moving on the belt conveyor, the communication path changes dynamically with time, so that a direct wave or an indirect wave changes. And it becomes difficult to predict such a radio wave environment that dynamically changes over time. Furthermore, communication may not be performed properly when the intensity of radio waves is the strongest. In this way, in a situation where the radio wave environment changes dynamically over time, the feasibility of communication with the RF tag is improved by controlling the transmission / reception gain to change over time based on time information. Can do. Note that such control does not necessarily enable communication with the RF tag, but can improve the feasibility of communication with the RF tag.

  In addition, the interrogator of the present invention is not an invention that performs communication only with a specific RF tag. In other words, in situations where the radio wave environment changes over time and dynamically, whether the interrogator wishes to communicate with an RF tag or other RF tag, it can be There is a problem that communication cannot be performed, and it is an object of the present invention to solve such a problem. That is, it is a feature of the present invention that it is possible to create a situation in which communication is possible from a situation in which communication with the RF tag is not possible. Therefore, whether or not communication with a desired RF tag is performed is not a problem that the present invention directly solves. Whether or not communication with a desired RF tag is being performed can be easily determined by a host computer or the like connected to the interrogator.

  The gain adjuster in the first embodiment includes, for example, a voltage control type variable attenuator as a first voltage control type variable attenuation circuit, a time information holding unit, and a time corresponding gain control unit. And a voltage generator.

<Processing flow of Embodiment 1>
FIG. 8 is a diagram illustrating an example of a processing flow according to the first embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 8A, the time information held in the time information holding unit is acquired (S801). As described above, this time information may be acquired based on a predetermined clock frequency. Next, based on the time information acquired in step S801, control is performed so as to change the transmission / reception gain over time (S810). In step S810, for example, control processing is performed as shown in FIG. That is, based on the time information acquired in step S801, a control command for changing the transmission / reception gain with time is output (S811). Then, transmission / reception gain control is executed based on the control command output in step S811 (S812). The process shown in FIG. 8B is realized, for example, by changing the control voltage for the variable attenuator.

<Effect of Embodiment 1>
The interrogator according to the first embodiment reduces interference even in a complicated radio wave environment in which direct waves and indirect waves are mixed by arranging a gain adjuster between the interrogator body and the antenna. The feasibility of communication with can be improved. Moreover, even when the communication environment changes dynamically by controlling the transmission / reception gain to change with time, the feasibility of communication with the RF tag can be improved.

<< Embodiment 2 >>
<Outline of Embodiment 2>
The second embodiment relates to an interrogator having a gain adjuster, similar to that described in the first embodiment, but has a feature in that the magnitude of the transmission / reception gain is controlled.

<Configuration of Embodiment 2>
FIG. 9 shows an example of a functional block diagram of the second embodiment. As shown in FIG. 2, the “interrogator” (900) of the second embodiment includes an “interrogator body” (901), an “antenna” (902), and a “gain adjuster” (903). . The gain adjuster (903) includes “random gain control means” (904). Since the components other than the “random gain control means” (904) are the same as those described in the first embodiment, description thereof is omitted here.

  “Random gain control means” (903) outputs a control command for the magnitude of the transmission / reception gain in accordance with a predetermined random number. The “predetermined random number” is a random number generated by a random number generator such as Mersenne Twister. In addition, random numbers generated by the squaring method, the linear congruential method, the mixed congruent method, etc. included. The “transmission / reception gain magnitude” is described with reference to transmission power as an example, as in the first embodiment. For example, as shown in FIG. The control described in the first embodiment is the control of the transmission / reception gain fluctuation timing on the time axis, but the second embodiment controls the magnitude of the transmission / reception gain. And the output of the command which controls the magnitude | size of this fluctuation | variation according to a random number can improve the feasibility of communication with RF tag in a complicated electromagnetic wave environment. The control command is output to the voltage controlled variable attenuation circuit as described in the first embodiment, for example.

  The power gain has been described as an example of the transmission / reception gain. However, for example, as shown in FIG. 11, a gain adjuster can be used as a device for controlling the directivity gain. That is, although the antenna has a certain directivity, the feasibility of communication with the RF tag can be improved by controlling the directivity gain. The gain adjuster (1103) shown in FIG. 11 realizes transmission / reception gain control by, for example, controlling the antenna (1102) to be rotatable. For example, by rotating the position of the antenna (1102) at random according to a predetermined random number, the feasibility of communication with the RF tag (1110) is improved.

  In the second embodiment, the transmission / reception gain is controlled according to the random number. However, the size may be quantitatively changed according to a predetermined rule, for example. Further, control according to random numbers and quantitative control may be performed alternately.

<Processing flow of Embodiment 2>
FIG. 12 is a diagram illustrating an example of a processing flow according to the second embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 12A, a predetermined random number is acquired (S1201). Next, the magnitude of the transmission / reception gain is controlled according to the random number acquired in step S1201 (S1210). In step S1210, for example, a control process as shown in FIG. 12B is performed. That is, a control command for the magnitude of the transmission / reception gain is output according to the random number acquired in step S1201 (S1211). Then, transmission / reception gain control is executed based on the control command output in step S1211 (S1212).

<Effect of Embodiment 2>
The interrogator of the second embodiment reduces interference even when the communication environment changes dynamically by controlling the magnitude of the transmission / reception gain to be changed randomly, and improves the feasibility of communication with the RF tag. Can be made.

<< Embodiment 3 >>
<Outline of Embodiment 3>
The third embodiment relates to an interrogator having a function combined with the transmission / reception gain control described in the first and second embodiments.

<Configuration of Embodiment 3>
FIG. 13 shows an example of a functional block diagram of the third embodiment. As shown in FIG. 3, the “interrogator” (1300) of the third embodiment includes an “interrogator body” (1301), an “antenna” (1302), and a “gain adjuster” (1303). . The gain adjuster (1303) includes a “time information holding unit” (1304), a “time corresponding gain control unit” (1305), a “random gain control unit” (1306), and a “first voltage control type variable attenuation”. Circuit "(1307). Each configuration is the same as that described in the first or second embodiment.

  The gain adjuster (1303) of the third embodiment is characterized in that it can output the control command for changing the transmission / reception gain described in the first embodiment and the control command of the magnitude of the transmission / reception gain. is there. In other words, since the magnitude of the transmission / reception gain can be changed randomly with time, depending on the radio wave environment, it is possible to further reduce the interference and improve the feasibility of communication with the RF tag. Become.

  In addition, regarding the first to third embodiments, the case where the direct wave and the indirect wave are mixed and described in the radio wave environment arriving at the interrogator has been described as an example, but for example, there is almost no influence of the indirect wave, In the case of receiving only a direct wave, by using a variable attenuator or the like to lower the transmission / reception gain, a signal from only a nearby RF tag is received without receiving a signal from a distant RF tag. It is also possible. Further, by artificially changing the propagation loss and noise figure (NF) of the communication line, the problem of interference between the interrogators with other interrogators installed in the vicinity of the interrogator is reduced. It is also possible.

  Thus, adjusting the gain randomly in time is a solution to the interference problem unique to the RF tag system. That is, unlike a wireless communication such as a mobile phone, the RF tag system employs, as an example, a system in which a passive RF tag responds by receiving a radio wave from an interrogator and using the radio wave. In addition, it is difficult to add a power control function for controlling the transmission power to the interrogator in an RF tag intended to be easily used at low cost. In such a case, it is possible to receive only response signals from some RF tags by unilaterally attenuating the transmission power from the interrogator, and as a result, interference can be reduced.

  Depending on the object to which the RF tag is attached, the indirect wave may be stronger than the direct wave. Moreover, in an environment where the radio wave environment changes complicatedly such as in a factory, it is difficult to accurately predict the environment. Therefore, instead of quantitatively controlling the transmission / reception gain, by controlling to change the magnitude of the transmission / reception gain etc. at random in time, the interference of communication with the RF tag is reduced by the interrogator, The feasibility of communication with the RF tag can be improved.

  Specifically, the gain adjuster in the third embodiment that has been described above specifically includes a voltage controlled variable attenuator as a first voltage controlled variable attenuating circuit, a time information holding unit, a time corresponding gain, for example. And a random voltage generator as a random gain control means.

<Processing flow of Embodiment 3>
FIG. 14 is a diagram illustrating an example of a processing flow according to the third embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 14A, time information is acquired (S1410). Next, the transmission / reception gain is temporally controlled based on the time information acquired in step S1410 (S1420). In step S1420, the process shown in FIG. 14B may be executed as described in the first embodiment. In step S1430, a predetermined random number is acquired and transmission / reception gain is controlled (S1440). Note that step S1440 may execute the process shown in FIG. 14C as described in the second embodiment. Further, the processing flow of the third embodiment is not limited to that shown in FIG. For example, steps S1430 and S1440 may be executed first.

<Effect of Embodiment 3>
The interrogator of the third embodiment can be used even when the communication environment changes dynamically by controlling the transmission / reception gain to change randomly or to change the transmission / reception gain over time. Interference can be reduced and the feasibility of communication with the RF tag can be improved. Further, since the existing interrogator and antenna can be used as they are, the interference problem can be avoided at a low cost.

<< Embodiment 4 >>
<Outline of Embodiment 4>
The fourth embodiment is characterized in that the interrogator described in any of the first to third embodiments adjusts the phase instead of adjusting the gain.

<Configuration of Embodiment 4>
FIG. 15 is a diagram illustrating an example of a functional block diagram of the interrogator according to the fourth embodiment. As illustrated in FIG. 15, the interrogator (1500) of the fourth embodiment includes an “interrogator body” (1501), an “antenna” (1502), and a “phase adjuster” (1503). The phase adjuster (1503) may include a “time information holding unit” (1504) and a “time corresponding phase control unit” (1505). Since the interrogator body (1501), the antenna (1502), and the time information holding unit (1504) are the same as those described in the first embodiment, description thereof is omitted here.

  The “phase adjuster” (1503) is arranged in the transmission / reception path between the antenna and the interrogator body to control the transmission / reception phase. The “transmission / reception phase” is a phase at the time of transmission or a phase at the time of reception. In the first place, indirect waves are radio waves that can cause a phase shift compared to direct waves. When both the indirect wave and the direct wave are received by the interrogator, if there is no phase shift due to the indirect wave, the wave is synthesized and the amplitude is increased. If a gap occurs, they cancel each other and communication cannot be performed properly. As described above, the present embodiment aims to increase the probability that a phase shift does not occur when an indirect wave is received and to improve the feasibility of communication.

  Therefore, in the second embodiment, it is possible to improve the feasibility of communication with the RF tag by controlling the transmission / reception phase using a phase adjuster. This enhances the probability that phase shift does not occur by changing the phase when the radio wave environment changes over time, while enhancing the reception sensitivity by combining the direct wave and the indirect wave. This is because the possibility of improvement can be increased. FIG. 16 is a diagram showing that a variable phase shifter is provided as an example of the phase adjuster. For phase control, for example, a plurality of transmission lines (L1, L2, L3) having different lengths are prepared, and the phase at the time of transmission or reception is changed by switching the switch (SW) according to the control voltage or the like. Is possible.

  The “time corresponding phase control means” (1505) outputs a control command for temporally changing the transmission / reception phase based on the time information. The time-corresponding phase control means is different from the time-corresponding gain control of the first embodiment in that the object of control is the phase, but is otherwise the same as the time-corresponding gain control means described in the first embodiment. It is.

<Processing Flow of Embodiment 4>
FIG. 17 is a diagram illustrating an example of a processing flow according to the fourth embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 17A, the time information held in the time information holding unit is acquired (S1701). As described above, this time information may be acquired based on a predetermined clock frequency. Next, based on the time information acquired in step S1701, control is performed so that the transmission / reception phase is temporally changed (S1710). In step S1710, for example, control processing is performed as shown in FIG. That is, based on the time information acquired in step S1701, a control command for changing the transmission / reception phase with time is output (S1711). Then, transmission / reception phase control is executed based on the control command output in step S1711 (S1712). The process shown in FIG. 17B is realized, for example, by changing the control voltage for the variable phase shifter. Further, as will be described later, it can also be realized by changing the control voltage for the variable attenuator.

<Effect of Embodiment 4>
The interrogator of the fourth embodiment appropriately communicates with the RF tag even in a complicated radio wave environment in which direct waves and indirect waves are mixed by arranging a phase adjuster between the interrogator body and the antenna. The possibility of doing so can be improved. Moreover, even when the communication environment changes dynamically by controlling the transmission / reception phase to change with time, the feasibility of communication with the RF tag can be improved.

<< Embodiment 5 >>
<Outline of Embodiment 5>
The interrogator according to the fifth embodiment has a phase adjuster similar to the interrogator according to the fourth embodiment, and is characterized in that the phase change amount can be controlled.

<Configuration of Embodiment 5>
FIG. 18 shows an example of a functional block diagram of the fifth embodiment. As illustrated in FIG. 18, the “interrogator” (1800) of the fifth embodiment includes an “interrogator body” (1801), an “antenna” (1802), and a “phase adjuster” (1803). . The phase adjuster (1803) includes “random phase control means” (1804). Since the components other than the “random phase control means” (1804) are the same as those described in the fourth embodiment, a description thereof is omitted here.

  The “random phase control means” (1804) outputs a control command for the phase change amount of the transmission / reception phase in accordance with a predetermined random number. The “phase change amount” is a phase shift amount when the phase is shifted. The random phase control means is different from the random gain control means of the first embodiment in that the object of control is a phase, but the rest is the same as the random gain control means described in the first embodiment. .

<Processing Flow of Embodiment 5>
FIG. 19 is a diagram illustrating an example of a processing flow according to the fifth embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 19A, a predetermined random number is acquired (S1901). Next, the phase change amount of the transmission / reception phase is controlled according to the random number acquired in step S1901 (S1910). In step S1910, for example, the control process shown in FIG. 19B is performed. That is, according to the random number acquired in step S1901, a control command for the phase change amount of the transmission / reception phase is output (S1911). Then, transmission / reception phase control is executed based on the control command output in step S1911 (S1912).

<Effect of Embodiment 5>
The interrogator of the fifth embodiment controls the RF tag so that the phase change amount of the transmission / reception phase is changed randomly according to a predetermined random number, thereby reducing interference even when the communication environment changes dynamically. The feasibility of communication with can be improved.

<< Embodiment 6 >>
<Overview of Embodiment 6>
The interrogator of the sixth embodiment is characterized in that it has a voltage-controlled variable attenuation circuit that adjusts the phase in response to the phase control command described in the fourth or fifth embodiment.

<Configuration of Embodiment 6>
FIG. 20 shows an example of a functional block diagram of the sixth embodiment. As shown in FIG. 6, the “interrogator” (2000) of the sixth embodiment includes an “interrogator body” (2001), an “antenna” (2002), and a “phase adjuster” (2003). . The phase adjuster (2003) includes a “time information holding unit” (2004), a “time corresponding phase control unit” (2005), a “random phase control unit” (2006), and a “second voltage controlled variable attenuation”. Circuit "(2007). Since the components other than the “second voltage controlled variable attenuation circuit” (2007) are the same as those described in the fourth or fifth embodiment, the description thereof is omitted here.

  The “second voltage control type variable attenuation circuit” (2007) is for performing transmission / reception phase control based on a control command. In the fourth embodiment, a variable phase shifter has been described as an example. However, as a method for controlling the phase, a phase change can be caused by using a voltage controlled variable attenuation circuit. . FIG. 21 is a diagram showing how the attenuation and phase change according to the control voltage. As shown in FIG. 21, attenuating power by adjusting the control voltage is equivalent to changing the phase. That is, in general, when an attenuator is arranged, a variable phase shifter is arranged to correct a change in the phase, but the phase adjuster of the present embodiment is By not arranging the variable phase shifter, the phase change due to attenuation is realized. And as already explained in other embodiments, a phase change is caused by changing the attenuation amount randomly in time, and as a result, in a radio wave environment in which direct waves and indirect waves are mixed. The feasibility of communication with the RF tag can be improved. Specifically, the phase adjuster of the sixth embodiment includes a voltage control type variable attenuator as a second voltage control type variable attenuation circuit, a time information holding unit, a time corresponding phase control unit, and a random voltage as a random phase control unit. And a generator.

  In FIG. 20, the gain adjuster (2003) of the sixth embodiment receives the control command for temporally changing the transmission / reception phase and the control command for the phase change amount of the transmission / reception phase described in the fourth and fifth embodiments. Although the description has been made assuming that the configuration is an output configuration, only one of the control commands may be output.

<Processing flow of Embodiment 6>
FIG. 22 is a diagram illustrating an example of a processing flow according to the sixth embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 22A, time information is acquired (S2210). Next, the transmission / reception phase is temporally controlled based on the time information acquired in step S2210 (S2220). Note that step S2220 may execute the process shown in FIG. 22B as described in the fourth embodiment. In step S2230, a predetermined random number is acquired and the phase change amount of the transmission / reception phase is controlled (S2240). Note that step S2240 may execute the processing shown in FIG. 22C as described in the fifth embodiment. Further, the processing flow of the sixth embodiment is not limited to that shown in FIG. For example, steps S2230 and S2240 may be executed first. The processes shown in FIGS. 22B and 22C are realized by, for example, changing the control voltage for the variable attenuator.

<Effect of Embodiment 6>
The interrogator of Embodiment 6 reduces interference by arranging a voltage-controlled variable attenuator in the transmission / reception path between the antenna and the interrogator body, and controlling the phase change amount of the transmission / reception phase randomly in time. As a result, the feasibility of communication with a predetermined RF tag can be improved.

<< Embodiment 7 >>
<Outline of Embodiment 7>
The present embodiment relates to an interrogator including both the gain adjuster described in any of Embodiments 1 to 3 and the phase adjuster described in any of Embodiments 4 to 6.

<Configuration of Embodiment 7>
FIG. 23 shows a functional block diagram of the interrogator in the seventh embodiment. As shown in FIG. 23, the interrogator (2300) of the present embodiment includes an “interrogator body” (2301), an “antenna” (2302), and a “gain / phase adjuster” (2303). . The “gain / phase adjuster” (2303) includes a “time information holding unit” (2304), a “time corresponding gain control unit” (2305), a “random gain control unit” (2306), and a “first voltage”. "Control type variable attenuation circuit" (2307), "Time corresponding phase control means" (2308), "Random phase control means" (2309), and "Second voltage control type variable attenuation circuit" (2310) Have.

  The “gain / phase adjuster” (2303) includes both the gain adjuster described in any of the first to third embodiments and the phase adjuster described in any of the third to sixth embodiments. In FIG. 23, the gain adjuster and the phase adjuster are integrated and the time information holding unit is described as a common one, but each may have a time information holding unit separately. Good.

  By including both the gain adjuster and the phase adjuster in this way, communication with the RF tag can be performed randomly in time under various conditions, for example, by adjusting the phase while adjusting the directivity gain. Therefore, interference reduction can be further promoted. Conversely, for example, the first voltage controlled variable attenuating circuit and the second voltage controlled variable attenuating circuit are shared, and a single voltage controlled variable attenuator is used to adjust the gain and phase. You can also. This is because, as already described, it is possible to realize both gain and phase control by attenuating the transmission power. Therefore, when the present invention is realized at a relatively low cost, a voltage-controlled variable attenuator controlled by a random voltage generator is arranged between the interrogator body and the antenna so as to be complicated. Even in a situation where the radio wave environment changes, interference can be reduced and the feasibility of communication with the RF tag can be improved.

<Processing flow of Embodiment 7>
FIG. 24 is a diagram illustrating an example of a processing flow according to the third embodiment. When the interrogator according to the present embodiment communicates with the RF tag, the interrogator performs the following processing to perform communication. First, as shown in FIG. 24A, time information is acquired (S2410). Next, the transmission / reception gain and the transmission / reception phase are temporally controlled based on the time information acquired in step S2410 (S2420). Note that step S2420 may execute the process shown in FIG. 24B as described in the first and fourth embodiments. In step S2430, a predetermined random number is acquired, and the magnitude of the transmission / reception gain and the phase change amount of the transmission / reception phase are controlled (S2440). Note that step S2440 may execute the process shown in FIG. 24C as described in the second and fifth embodiments. Further, the processing flow of the seventh embodiment is not limited to that shown in FIG. For example, steps S2430 and S2440 may be executed first. In FIG. 24, the transmission / reception gain and the transmission / reception phase are executed in the same step, but it is of course possible to separate them as different steps.

<Effect of Embodiment 7>
The interrogator according to the seventh embodiment includes both the gain adjuster and the phase adjuster described in any of the first to sixth embodiments, and can combine them. The gain and phase can be adjusted under various conditions. It is possible to construct various communication environments. For this reason, even in a situation where the radio wave environment changes in a complicated manner, interference can be reduced and the RF tag communication can be improved. Further, by sharing the gain adjuster and the phase adjuster, it is possible to reduce interference during communication with the RF tag at a low cost.

The figure which shows an example of the conventional RF tag system The figure which shows a mode that a direct wave and an indirect wave change dynamically in time etc. in a factory etc. as an example of utilization environment. The block diagram which shows the outline | summary of Embodiment 1. The block diagram which clarified the function of the gain regulator of Embodiment 1. The figure for demonstrating an example which changes transmission / reception gain temporally Second block diagram clarifying the function of the gain adjuster of the first embodiment. The figure which shows that communication with RF tag becomes impossible by the fluctuation of S / N ratio The figure for demonstrating an example of the flow of a process of Embodiment 1. FIG. Functional block diagram for explaining the second embodiment The figure for demonstrating an example which changes the magnitude | size of a transmission / reception gain according to a predetermined random number The figure which shows an example which controls directivity gain The figure for demonstrating an example of the flow of a process of Embodiment 2. Functional block diagram for explaining the third embodiment The figure for demonstrating an example of the flow of a process of Embodiment 3. Functional block diagram for explaining the fourth embodiment The figure which shows the variable phase shifter of an example of the phase adjuster of Embodiment 4. The figure explaining the flow of processing of Embodiment 4 Functional block diagram for explaining the fifth embodiment The figure for demonstrating the flow of a process of Embodiment 5. Functional block diagram for explaining the sixth embodiment The figure which shows a mode that attenuation amount and phase change arise according to control voltage The figure for demonstrating the flow of a process of Embodiment 6. FIG. Functional block diagram for explaining the seventh embodiment The figure explaining the flow of processing of Embodiment 7.

Explanation of symbols

400 Interrogator 401 Interrogator Main Body 402 Antenna 403 Gain Adjuster 404 Time Information Holding Unit 405 Time Corresponding Gain Control Unit 611 First Voltage Control Type Variable Attenuation Circuit 904 Random Gain Control Unit

Claims (16)

An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
An interrogator having a gain adjuster arranged in a transmission / reception path between the antenna and the interrogator body to control a transmission / reception gain. The gain adjuster is
A time information holding unit for holding time information;
The interrogator according to claim 1, further comprising time-dependent gain control means for outputting a control command for temporally changing a transmission / reception gain based on the time information. The gain adjuster is
3. The interrogator according to claim 1, further comprising random gain control means for outputting a control command for the magnitude of transmission / reception gain in accordance with a predetermined random number.   The interrogator according to any one of claims 1 to 3, wherein the gain adjuster includes a first voltage-controlled variable attenuation circuit for performing transmission / reception gain control based on a control command. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
An interrogator having a phase adjuster arranged in a transmission / reception path between the antenna and the interrogator body to control a transmission / reception phase. The phase adjuster is
A time information holding unit for holding time information;
6. The interrogator according to claim 5, further comprising a time-corresponding phase control means for outputting a control command for temporally changing the transmission / reception phase based on the time information. The phase adjuster is
The interrogator according to claim 5 or 6, further comprising random phase control means for outputting a control command for a phase change amount of a transmission / reception phase in accordance with a predetermined random number.   The interrogator according to any one of claims 5 to 7, wherein the phase adjuster includes a second voltage-controlled variable attenuation circuit for performing transmission / reception phase control based on a control command. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
An interrogator comprising the gain adjuster according to any one of claims 1 to 4 and the phase adjuster according to any one of claims 5 to 8. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a gain adjuster that is disposed in a transmission / reception path between the antenna and the interrogator body and controls transmission / reception gain,
A communication method for executing a time-dependent gain control step for controlling a transmission / reception gain to change with time based on time information. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a gain adjuster that is disposed in a transmission / reception path between the antenna and the interrogator body and controls transmission / reception gain,
A communication method for executing a random gain control step of controlling the magnitude of a transmission / reception gain according to a predetermined random number. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a gain adjuster that is disposed in a transmission / reception path between the antenna and the interrogator body and controls transmission / reception gain,
A time-dependent gain control step for controlling the transmission / reception gain to change with time based on the time information;
A random gain control step for controlling the magnitude of the transmission / reception gain according to a predetermined random number;
Communication method to execute. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a phase adjuster that is arranged in a transmission / reception path between the antenna and the interrogator body and controls a transmission / reception phase,
A communication method for executing a time-corresponding phase control step for controlling a transmission / reception phase to change temporally based on time information. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a phase adjuster that is arranged in a transmission / reception path between the antenna and the interrogator body and controls a transmission / reception phase,
A communication method for executing a random phase control step of controlling a phase change amount of a transmission / reception phase according to a predetermined random number. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a phase adjuster that is arranged in a transmission / reception path between the antenna and the interrogator body and controls a transmission / reception phase,
A time corresponding phase control step for controlling the transmission / reception phase to change temporally based on the time information;
And a random phase control step of controlling a phase change amount of the transmission / reception phase according to a predetermined random number. An interrogator body that outputs a signal to the RF tag or obtains a signal from the RF tag;
An antenna for communicating with the RF tag;
A communication method using an interrogator having a gain adjuster for controlling a transmit / receive gain and a phase adjuster for controlling a transmit / receive phase, arranged in a transmit / receive path between the antenna and the interrogator body,
The communication method which performs the step as described in any one of Claim 10 to 12, and the step as described in any one of Claim 13 to 15.

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