WO2008018253A1

WO2008018253A1 - Direction detection device

Info

Publication number: WO2008018253A1
Application number: PCT/JP2007/063117
Authority: WO
Inventors: Hironori Hirata; Kazunari Taki; Shiro Yamada; Hideyuki Nebiya
Original assignee: Brother Kogyo Kabushiki Kaisha
Priority date: 2006-08-11
Filing date: 2007-06-29
Publication date: 2008-02-14

Abstract

Provided is a direction detection device capable of reducing the affect of a multi-path and realizing an appropriate direction detection. The direction detection device includes: an array antenna (16) formed by a plurality of antenna elements (26); a directivity control unit (54) for controlling a phase corresponding to each of the antennas (26) so as to control transmission and/or reception directivity of the array antennas (16); and a direction detection unit (60) for detecting a radio tag (14) by comparing a reception signal received when the directivity control unit (54) has set the transmission and/or reception directivity of the array antennas (16) to a directivity direction corresponding to a first angle, to a reception signal received when the directivity direction corresponds to a second angle obtained by shifting the first angle by a predetermined angle. Thus, by using a reception result corresponding to the angle scarcely affected by the multi-path, it is possible to appropriately detect the direction of the radio tag (14).

Description

Specification

Direction detection device

Technical field

[oooi] The present invention relates to a direction detection device that performs transmission and Z or reception of a radio signal to a radio terminal and detects the direction of the radio terminal based on the radio signal, and more particularly, a multipath. It relates to technology for reducing the impact.

Background art

An RFID (Radio Frequency Identification) system is known in which information is read out in a non-contact manner from a small-sized wireless tag (responder) in which predetermined information is stored by a predetermined wireless tag communication device (interrogator). ing. This RFID system can read information stored in a wireless tag by communication with the wireless tag communication device even when the wireless tag is dirty or placed at an invisible position. Therefore, practical use is expected in various fields such as product management and inspection processes.

As one form of such a wireless tag communication device, use as a direction detecting device that detects the direction of the wireless tag based on a response wave from the wireless tag has been proposed. For example, this is the wireless tag position detection system described in Patent Document 1. According to this technology, an interrogation wave is transmitted toward a radio tag to be detected, and a response wave returned from the radio tag power is received according to the interrogation wave, and a radio wave is transmitted to the radio tag. It is said that the direction or position of the wireless tag can be detected through communication.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-105723

Disclosure of the invention

Problems to be solved by the invention

[0005] However, when the direction of a wireless terminal is detected by the PAA (Phased Array Antenna) process using the conventional technology as described above, a plurality of reflections and diffractions caused by obstacles are used. Due to the effect of so-called multipath that creates a radio reception path, the radio signal of the directional force corresponding to the radio terminal to be detected becomes weak, or the radio signal from the direction where no radio terminal exists becomes strong, etc. And it may be difficult to detect the direction of the wireless terminal. was there. For this reason, there has been a demand for the development of a direction detection device that realizes suitable direction detection by reducing the influence of multipath.

[0006] The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a direction detection device that reduces the influence of multipath and realizes preferable direction detection. is there.

Means for solving the problem

[0007] In order to achieve such an object, the gist of the first invention is that a radio signal is transmitted and Z or received to a radio terminal \ based on the radio signal! A direction detection device for detecting a direction of a terminal, which is an array antenna composed of a plurality of antenna elements for transmitting a radio signal to the radio terminal and for receiving a radio signal from Z or the radio terminal A directivity control unit that controls the transmission directivity and Z or reception directivity of the array antenna by controlling the phase corresponding to each of the plurality of antenna elements, and the directivity control unit transmits the array antenna. When the directivity and Z or reception directivity are set to the directivity direction corresponding to the first angle, the received signal and its first angular force correspond to the second angle shifted by a predetermined deviation angle. And a reception signal received in case of a directivity direction of, the direction detection unit for detecting the direction of the pre-Symbol radio terminal by comparison, is characterized in that it comprises.

[0008] Further, in order to achieve the above object, the gist of the second invention is that a radio signal is transmitted and Z or received to a radio terminal \ based on the radio signal! A direction detection device for detecting a direction of a wireless terminal, which is configured by a plurality of antenna elements for transmitting a wireless signal to the wireless terminal and for receiving a wireless signal of Z or its wireless terminal power. A plurality of array antennas, and a direction detection unit that detects the direction of the wireless terminal by comparing received signals received as a result of transmission and Z or reception by each of the array antennas. It is characterized by having it.

The invention's effect

Thus, according to the first aspect of the present invention, a plurality of antenna elements are used for transmitting a radio signal to the radio terminal and for receiving a radio signal from Z or the radio terminal. Array antenna, a directivity control unit that controls the transmission directivity and Z or reception directivity of the array antenna by controlling the phase corresponding to each of the plurality of antenna elements, and directivity control thereof Received signals received when the transmission directivity and Z or reception directivity of the array antenna is set to a directivity direction corresponding to the first angle, and a first deviation angle shifted from the first angle by a predetermined deviation angle. And a direction detection unit that detects the direction of the wireless terminal by comparing the received signal received in the case of the directivity direction corresponding to the angle of 2. By comparing the signals and using the reception result in the directivity direction corresponding to the angle with less influence of the multipath, the direction of the wireless terminal can be suitably detected. That is, it is possible to provide a direction detection device that reduces the influence of multipath and realizes suitable direction detection.

[0010] Here, in the first invention, preferably, a signal strength detection unit that detects a signal strength of a reception signal received by the array antenna is provided, and the direction detection unit detects the signal strength. The direction of the wireless terminal is detected according to the signal strength detected by the unit. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0011] Preferably, the direction detection unit is received when the first angle is changed stepwise by a predetermined angle and the directivity direction corresponding to the first angle is set. The received signal or the signal strength thereof and the received signal or the signal strength received in the case of the directivity direction corresponding to the second angle are stored in a predetermined storage device, and the storage device The direction of the wireless terminal is detected by comparing the received signal stored in the signal or its signal strength. In this way, the directivity direction corresponding to an angle with less influence of multipath can be determined in a practical manner, and the direction of the wireless terminal can be suitably detected.

[0012] Preferably, the deviation angle is not less than 1Z10 and not more than 1Z5 of a predetermined angle that is a stepwise change in the first angle. In general, even if the directivity direction of the array antenna is shifted by a sufficiently small angle, the received signal strength due to the direct wave is hardly changed, but the influence of multipath changes greatly because the path difference between the direct wave and the indirect wave changes. . Follow By comparing the received signals corresponding to each directivity direction by shifting the directivity direction of the array antenna by a deviation angle sufficiently smaller than the predetermined angle, the directivity corresponding to the angle with less influence of multipath is obtained. Sex direction can be determined, and the direction of the wireless terminal can be suitably detected.

[0013] Preferably, the deviation angle is in a range of 1 to 2 °. Generally, even if the directivity direction of the array antenna is shifted within a range of 1 to 2 °, the received signal intensity due to the direct wave is almost the same, but the path difference between the direct wave and the indirect wave changes, so multipath The impact of changes greatly. Therefore, by comparing the received signals corresponding to each directivity direction by shifting the directivity direction of the array antenna within a range of 1 to 2 °, the directivity direction corresponding to an angle with less multipath effect is obtained. And the direction of the wireless terminal can be suitably detected.

[0014] Preferably, the deviation angle is equal to or less than an allowable error angle in the direction detection of the wireless terminal. In this way, the influence of multipath can be reduced by comparing the received signals corresponding to the respective directivity directions by shifting the directivity direction of the array antenna within a range equal to or smaller than the allowable error angle in the direction detection. The directivity direction corresponding to a small angle can be determined, and the direction of the wireless terminal can be suitably detected.

[0015] Preferably, the direction detection unit first changes the transmission directivity and the array antenna of the array antenna by the directivity control unit while gradually changing the first angle by a predetermined angle.

The received signal or the signal strength received when Z or the reception directivity is a directivity direction corresponding to each first angle is stored in the storage device, and then the first angle is determined. Corresponding to the second angle by shifting the array antenna's transmission directivity and Z or reception directivity by the respective first angular force deviation angle while changing the predetermined angle step by step. The received signal or the signal strength received in the case of the directivity direction is stored in the storage device, and the direction of the wireless terminal is determined by comparing the received signal or the signal strength stored in the storage device. It is something to detect. In this way, it is possible to determine the directivity direction corresponding to an angle with less influence of multipath in a practical manner, and it is possible to suitably detect the direction of the wireless terminal. [0016] In addition, preferably, the direction detection unit, when the signal strength of the received signal received when the directivity direction corresponds to the first angle is equal to or less than a predetermined value, First angular force The directivity control corresponding to the second angle shifted by a predetermined deviation angle and the wireless signal transmission and Z or reception control are not performed. In this way, it is necessary to detect the direction of the wireless terminal by performing suitable communication due to the presence of an obstacle, etc., and omitting the control corresponding to the second angle according to the direction. Time can be shortened.

[0017] Preferably, the direction detection unit compares the detection results detected by the signal intensity detection unit for each received signal stored in the storage device, and the detection result is the maximum. The direction corresponding to the transmission directivity and Z or reception directivity taking a value is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0018] Preferably, the direction detection unit compares a detection result detected by the signal intensity detection unit for each reception signal stored in the storage device, and the detection result is the first detection result. The directivity direction corresponding to the angle and the directivity direction corresponding to the second angle are the direction corresponding to the transmission direction and Z or the reception directivity that are equal to or greater than a predetermined threshold. Is detected. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0019] Preferably, the direction detection unit compares a detection result detected by the signal intensity detection unit for each received signal stored in the storage device, and compares the detection result with the first angle. The direction corresponding to the angle with the smallest difference between the detection result of the corresponding directivity direction and the detection result of the directivity direction corresponding to the second angle is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0020] Preferably, the direction detection unit has a directivity direction corresponding to the first angle and a directivity direction corresponding to the second angle for each reception signal stored in the storage device. For each, the detection results detected by the signal intensity detection unit are averaged, and the detection result has a maximum value in the directivity direction corresponding to the average large angle. A direction corresponding to directivity and z or reception directivity is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0021] Preferably, the obstacle direction detection unit that detects the direction in which the obstacle exists by comparing the received signals or the signal strengths stored in the storage device, or the direction of the obstacle is known. If there is an obstacle direction setting unit for setting the direction of the obstacle, the direction detection unit is set in the direction in which the obstacle is detected by the obstacle direction detection unit or in the obstacle direction setting unit. The direction of the wireless terminal is detected by excluding the direction. In this way, the direction of the wireless terminal can be suitably detected by avoiding the direction in which an obstacle causing multipath occurs.

[0022] Preferably, the direction detection device transmits a predetermined transmission signal toward the detection target wireless tag and returns a response signal returned from the wireless tag in response to the transmission signal. The wireless tag direction detection device detects a direction of the wireless tag by receiving the wireless tag. In this way, it is possible to provide a wireless tag direction detection device that reduces the influence of multipath and realizes detection of a suitable wireless tag direction.

[0023] Preferably, the direction detection unit detects a direction of the wireless tag by changing a frequency of a carrier wave of the transmission signal and comparing a reception signal received corresponding to each frequency. Is. In this way, it is possible to compare the received signals received corresponding to each directional direction at each of a plurality of carrier frequencies and use the reception result by the carrier frequency with less multipath effect. The direction of the wireless tag can be detected more suitably.

[0024] According to the second invention, each of the antenna elements is configured to transmit a radio signal to the radio terminal and to receive a radio signal from Z or the radio terminal. A plurality of array antennas and a direction detection unit that detects the direction of the wireless terminal by comparing received signals received as a result of transmission and Z or reception by each of the plurality of array antennas; Therefore, the direction of the wireless terminal can be suitably detected by using the reception result of the array antenna with less influence of multipaths by comparing the received signals. That is, the effect of multipath It is possible to provide a direction detection device that realizes suitable direction detection by reducing the above.

[0025] Here, in the second invention, preferably, the direction detection unit includes a directivity control unit that controls transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas. The directivity control unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas, and the received signal is received corresponding to each transmission directivity and Z or reception directivity. Is used to detect the direction of the wireless terminal. In this way, the received signals received by the plurality of sets of array antennas corresponding to the respective transmission directivities and Z or reception directivities are compared, and the reception results obtained by the array antennas are less affected by multipath. By using it, the direction of the wireless terminal can be suitably detected.

[0026] In addition, preferably, a signal strength detection unit that detects a signal strength of a reception signal received by the array antenna is provided, and the direction detection unit corresponds to the signal strength detected by the signal strength detection unit. The direction of the wireless terminal is detected. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0027] Preferably, at least one of the antenna elements constituting the plurality of sets of array antennas is shared by the plurality of sets of array antennas. In this way, the space occupied by the plurality of array antennas can be made as small as possible, and thus the apparatus can be downsized.

[0028] Also, preferably, an antenna that switches a circuit so that a radio signal to the radio terminal is selectively transmitted and Z or received by any one of the plurality of array antennas. It has a selection control part. In this way, a reception signal processing circuit is provided corresponding to each array antenna by sequentially switching array antennas that transmit and Z or receive wireless signals to the wireless terminal by the antenna selection control unit. The configuration of the apparatus that is not necessary can be simplified.

[0029] Preferably, the plurality of array antennas have a reception signal processing circuit corresponding to each of the plurality of array antennas, and the plurality of array antennas simultaneously receive radio signals from the radio terminal. It is. In this way, the processing time of the radio signal can be shortened as much as possible, and thus the time required for detection of the radio terminal can be reduced. can do.

[0030] Preferably, the direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of array antennas by the directivity control unit, so that each transmission directivity and Z Or, compare the detection results detected by the signal strength detection unit for the received signal received corresponding to the reception directivity, and determine the transmission direction and Z or reception directivity where the detection result takes the maximum value. The corresponding direction is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0031] Preferably, the direction detection unit controls the transmission directivity and Z or the reception directivity of each of the plurality of array antennas by the directivity control unit, so that each transmission directivity and Z Alternatively, the detection result detected by the signal strength detection unit is compared with respect to the received signal received corresponding to the reception directivity, and the detection result is equal to or greater than a predetermined threshold in any of the plurality of sets of array antennas. And the direction corresponding to Z or reception directivity is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0032] Preferably, the direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of array antennas by the directivity control unit, so that each transmission directivity and Z Alternatively, the detection results detected by the signal intensity detection unit for received signals corresponding to the reception directivity are compared, and the detection is performed at the array antenna with the least variation in the detection results among the plurality of sets of array antennas. The direction corresponding to the transmission directivity and Z or reception directivity where the result is the maximum value is detected as the direction of the wireless terminal. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0033] Preferably, the direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of array antennas by the directivity control unit, and corresponds to each reception directivity. The detection results detected by the signal strength detector for the received signal received are averaged, and the transmission directivity and Z or reception directivity at which the detection result takes the maximum value for the array antenna having the largest average. Direction corresponding to the direction of the wireless terminal Is detected. In this way, the direction of the wireless terminal can be detected in a practical manner.

[0034] Preferably, the array antenna also includes a plurality of linear antenna element forces arranged so as to be parallel to each other. In this way, it is possible to reduce the influence of multipath and realize suitable direction detection in the direction detection device having a practical array antenna having a plurality of linear antenna element forces.

[0035] Preferably, among the plurality of linear antenna elements constituting the array antenna, the distance between the linear antenna elements arranged farthest from each other is the carrier wave of the radio signal. Or less. In this way, the space occupied by the plurality of sets of array antennas can be made as small as possible, and thus the apparatus can be downsized.

[0036] Preferably, the plurality of sets of array antennas includes two linear antenna elements adjacent to each other among three linear antenna elements arranged so as to be parallel to each other. There are two sets of array antennas, each of which consists of forces. In this way, the radio signals can be compared by comparing the received signals corresponding to each of two sets of array antennas that are selectively composed of three linear antenna elements arranged in parallel to each other. The direction of the terminal can be detected suitably.

[0037] Preferably, the plurality of sets of array antennas include two linear antenna elements adjacent to each other among three linear antenna elements arranged so as to be parallel to each other. There are two sets of array antennas, each of which is also configured with force, and one set of array antennas, which is also configured with the force of two linear antenna elements arranged farthest from each other. In this way, by comparing the received signals corresponding to each of the three sets of array antennas that are selectively configured with three linear antenna element forces arranged so as to be parallel to each other, The direction of the wireless terminal can be preferably detected.

[0038] Preferably, the plurality of sets of array antennas are composed of two linear antenna elements adjacent to each other among four linear antenna elements arranged so as to be parallel to each other. There are 3 sets of array antennas. In this way, by comparing the received signals corresponding to each of the three sets of array antennas selectively configured from the four linear antenna elements arranged so as to be parallel to each other, Optimize the direction of the wireless terminal Can be detected.

[0039] Preferably, the plurality of sets of array antennas are selected from four linear antenna elements arranged so as to be parallel to each other. Two sets of array antennas are constructed. In this way, by comparing the received signals corresponding to each of two sets of array antennas selectively configured from four linear antenna elements arranged so as to be parallel to each other, The direction of the wireless terminal can be detected suitably.

[0040] Further, preferably, the direction detection unit corresponds to a predetermined relative angle range determined in advance, and the directivity control unit performs transmission directivity and Z or reception of each of the plurality of sets of array antennas. The directivity is controlled, and the direction of the wireless terminal is detected by comparing the reception signals received corresponding to each transmission directivity and Z or reception directivity. In this way, the time required for detection of the wireless terminal can be shortened by limiting the range of the direction detection target in advance.

[0041] Preferably, the obstacle direction detection detects the direction in which the obstacle exists by comparing the received signals received as a result of transmission and Z or reception by each of the plurality of sets of array antennas. Or an obstacle direction setting unit for setting the direction of the obstacle when the direction of the obstacle is known in advance, and the direction detection unit detects the obstacle by the obstacle direction detection unit. The direction of the wireless terminal is detected by excluding the direction or the direction set in the obstacle direction setting unit. In this way, the direction of the wireless terminal can be suitably detected by avoiding the direction in which the obstacle causing the multipath occurs.

[0042] Preferably, the direction detection device transmits a predetermined transmission signal toward the detection target wireless tag and returns a response signal returned from the wireless tag in response to the transmission signal. The wireless tag direction detection device detects a direction of the wireless tag by receiving the wireless tag. In this way, it is possible to provide a wireless tag direction detection device that reduces the influence of multipath and realizes detection of a suitable wireless tag direction.

[0043] Preferably, the direction detection unit changes the frequency of the carrier wave of the transmission signal and compares the reception signal received corresponding to each frequency to determine the direction of the wireless tag. It is to detect. In this way, by comparing the reception signals received corresponding to the respective reception directivities at each of the plurality of carrier frequencies, and using the reception result at the carrier frequency with less multipath effect, the radio The direction of the tag can be detected suitably.

Brief Description of Drawings

FIG. 1 is a diagram for explaining a wireless tag communication system in which the direction detection device of the present invention is preferably used.

FIG. 2 is a diagram for explaining the configuration of a wireless tag communication device which is a preferred embodiment of the direction detection device of the first invention.

3 is a diagram illustrating in detail the configuration of a transmission / reception module provided in the RFID tag communication apparatus of FIG. 2.

4 is a diagram illustrating a configuration of a wireless tag circuit element provided in a wireless tag that is a wireless terminal to be detected by the wireless tag communication device of FIG. 2.

FIG. 5 is a diagram for explaining multipath that occurs when the RFID tag communication system of FIG. 1 is operated indoors.

[FIG. 6] The signal strength of the received signal received when the RFID tag communication device of FIG. 2 changes the first angle stepwise by a predetermined angle and sets the directivity direction corresponding to the first angle. FIG. 6 is a diagram showing a comparison between the signal strength of a received signal received in the case of a directivity direction corresponding to a second angle that is shifted from each first angle by a predetermined deviation angle.

[FIG. 7] If the signal strength of the received signal is less than or equal to the predetermined value when the directionality control corresponding to the first angle is set in the direction detection control by the RFID tag communication apparatus of FIG. FIG. 6 is a diagram for explaining that directivity control and radio signal transmission and Z or reception control corresponding to a second angle shifted by a predetermined deviation angle are not performed.

FIG. 8 is a flowchart for explaining a main part of an example of tag direction detection control by the wireless tag communication device of FIG. 2.

FIG. 9 illustrates a main part of another example of tag direction detection control by the RFID tag communication apparatus of FIG. It is a flowchart.

FIG. 10 is a flowchart for explaining a main part of yet another example of tag direction detection control by the wireless tag communication device of FIG.

FIG. 11 is a flowchart for explaining a main part of yet another example of tag direction detection control by the wireless tag communication device of FIG. 2.

FIG. 12 is a flowchart for explaining a main part of still another example of tag direction detection control by the wireless tag communication device of FIG. 2.

FIG. 13 is a flowchart for explaining a main part of yet another example of tag direction detection control by the wireless tag communication device of FIG. 2.

FIG. 14 is a flowchart for explaining a main part of still another example of tag direction detection control by the wireless tag communication device of FIG.

[15] FIG. 15 is a diagram illustrating a configuration of a wireless tag communication device which is a preferred embodiment of the direction detection device of the second invention.

FIG. 16 is a diagram illustrating a multipath that occurs when the RFID tag communication system of FIG. 1 is operated indoors.

圆 17] Explain the difference in signal strength of received signals when the directivity is changed in the same way with multiple sets of array antennas composed of multiple antenna elements provided in the RFID tag communication device of Fig. 15. The signal strength of the received signal corresponding to each directivity direction is indicated by an arrow.

圆 18] Explain the difference in signal strength of received signals when the directivity is similarly changed in multiple sets of array antennas composed of multiple antenna elements provided in the RFID tag communication device of FIG. The signal strength of the received signal corresponding to each directivity direction is indicated by an arrow.

FIG. 19 is a flowchart for explaining a main part of an example of tag direction detection control by the wireless tag communication device of FIG.

FIG. 20 is a flowchart for explaining a main part of another example of tag direction detection control by the wireless tag communication device of FIG.

[FIG. 21] The main part of still another example of tag direction detection control by the RFID tag communication apparatus of FIG. It is a flowchart to explain.

22 is a flowchart for explaining a main part of yet another example of tag direction detection control by the wireless tag communication device of FIG.

FIG. 23 is a flowchart for explaining a main part of still another example of tag direction detection control by the wireless tag communication device of FIG. 15.

FIG. 24 is a flowchart for explaining a main part of still another example of tag direction detection control by the wireless tag communication apparatus of FIG.

FIG. 25 is a diagram for explaining the configuration of a wireless tag communication device which is another preferred embodiment of the direction detection device of the second invention.

FIG. 26 is a diagram for explaining the configuration of a wireless tag communication device which is still another preferred embodiment of the direction detection device according to the second invention.

Explanation of symbols

[0045] 10: wireless tag communication system, 12, 93, 94, 96: wireless tag communication device (direction detection device), 14: wireless tag (wireless terminal), 16: array antenna, 20: carrier wave generation unit, 22: Carrier amplifier, 24: Transmitter / receiver module, 26: Antenna element, 28: Received signal synthesizer, 30: Variable amplifier, 32: Homodyne detector, 34: I¾LPF, 36: 1 phase 8 0 converter, 38: 1 phase Memory part (storage device), 40: Q phase LPF, 42: Q phase AZD conversion part, 44: Q phase memory part (storage device), 4 6: Transmission circuit switching part, 48: Reception circuit switching part, 50: Transmission Data generation unit, 52: Antenna selection control unit, 54: Directivity control unit, 56: Signal strength detection unit, 58: Obstacle direction detection unit, 59: Obstacle direction setting unit, 60: Direction detection unit, 62: Transmit phase shifter, 64: Transmit amplifier, 66: Transmit / receive separation unit, 68: Filter, 70: Receive phase shift unit, 72: RFID circuit element, 74: Antenna unit, 76: IC circuit unit, 78: Rectifier unit , 8 0: Power supply unit, 82: Clock extraction unit, 84: Memory unit, 86: Modulation / demodulation unit, 88: Control unit, 90: Room, 92: Wall (obstacle)

BEST MODE FOR CARRYING OUT THE INVENTION

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

Example

FIG. 1 is a diagram illustrating a radio tag communication system 10 in which the direction detection device of the present invention is preferably used. The RFID tag communication system 10 is a direction detection device of the first invention. A RFID tag communication device 12 that is one embodiment of the device and a single or plural (single in FIG. 1) wireless tags 14 that are wireless terminals to be detected by the RFID tag communication device 12, so-called RFID (Radio Frequency Identification) system, the RFID tag communication device 12 functions as an interrogator of the RFID system, and the RFID tag 14 functions as a responder. That is, when the interrogation wave F (transmission signal) is transmitted from the radio tag communication device 12 toward the radio tag 14, the radio tag 14 that has received the interrogation wave F uses a predetermined command (transmission data). The interrogation wave F is modulated, and a response wave F (reply signal) is sent back to the RFID tag communication device 12 to communicate information between the RFID tag communication device 12 and the RFID tag 14. Is done. Through such communication, the direction or position of the wireless tag 14 relative to the wireless tag communication device 12 is detected. The wireless tag communication system 10 is used, for example, for management of articles in a predetermined communication area, and the wireless tag 14 is preferably attached to an article to be managed. It is integrated with the product.

FIG. 2 is a diagram illustrating the configuration of the wireless tag communication device 12. As shown in FIG. 2, the RFID tag communication apparatus 12 of the present embodiment includes a carrier generation unit 20 that generates a carrier wave of a predetermined frequency in response to a command from a direction detection unit 60 described later, and the carrier generation unit 20 A carrier wave amplification unit 22 that amplifies the carrier wave output from the carrier wave, and a transmission signal based on the carrier wave supplied from the carrier wave amplification unit 22 is transmitted from the corresponding antenna element 26 and a reception signal received by the antenna element 26 is received. A plurality of transmission / reception modules 24a, 24b, 24c (3 in FIG. 2) to be processed (hereinafter simply referred to as transmission / reception modules 24 unless otherwise specified) are provided corresponding to each transmission / reception module 24a, 24b, 24c. The antenna elements 26a, 26b, and 26c shared by transmission and reception (hereinafter simply referred to as the antenna element 26 unless otherwise specified) and the reception elements supplied from the plurality of transmission / reception modules 24. Received signal combining unit 28, which is a combining unit for combining (adding) signals, variable amplifying unit 30 for amplifying the combined signal supplied from received signal combining unit 28, and supplied from variable amplifying unit 30 A homodyne detection circuit 32 that performs homodyne detection of the composite signal, and an I-phase LPF (Low Pass Filter) 34 that passes only signals in a predetermined frequency band among the I-phase signals (in-phase components) that are also output from the homodyne detection circuit 32 The I-phase signal that passed through the I-phase LPF34 is digitally converted. Of the I-phase AZD conversion unit 36, the I-phase memory unit 38 that stores the signal digitally converted by the I-phase AZD conversion unit 36, and the Q-phase signal (orthogonal component) output from the homodyne detection circuit 32 A Q-phase LPF40 that passes only signals in the specified frequency band, a Q-phase AZD converter 42 that digitally converts the Q-phase signal that has passed through the Q-phase LPF40, and a signal digitally converted by the Q-phase AZD converter 42 Q memory unit 44 for storing. In addition, in order to perform direction detection control for detecting the direction of the wireless tag 14, a transmission data generation unit 50, a directivity control unit 54, a signal intensity detection unit 56, an obstacle direction detection unit 58, an obstacle direction setting unit 59 and a direction detector 60 are provided.

[0049] The antenna element 26 is, for example, a linear antenna element such as a dipole antenna, and is preferably arranged so that the plurality of linear antenna elements 26 are parallel to each other in the same plane and at equal intervals. It has been. In the RFID tag communication apparatus 12 of the present embodiment, the array antenna 16 that is used for both transmission and reception is constituted by the plurality of linear antenna elements 26. Preferably, among the plurality of linear antenna elements 26 constituting the array antenna 16, the distance between the linear antenna elements 26 arranged farthest from each other, that is, between the antenna elements 26a and 26c. Is less than the wavelength of the carrier wave generated by the carrier wave generator 20.

FIG. 3 is a diagram for explaining the configuration of the transmission / reception module 24 in detail. As shown in FIG. 3, the transmission / reception module 24 includes a transmission phase shifter 62 that is a variable phase shifter for controlling the phase of the carrier wave supplied from the carrier wave amplification unit 22, and its transmission phase shift. 62 A transmission amplifier 64 that is a variable gain amplifier for modulating the output carrier wave with predetermined transmission data and outputting the transmission signal, and a signal transmission path between the transmission amplifier 64 and the antenna element 26 And a transmission signal output from the transmission amplifier 64 is supplied to the antenna element 26 via the filter 68, and is received by the antenna element 26 and supplied via the filter 68. Transmission / reception separating unit 66 for supplying the received signal to reception amplifier 70, and reception phase shifting unit 70, which is a variable phase shifter for controlling the phase of the received signal supplied from transmission / reception separating unit 66, , It is equipped.

FIG. 4 is a diagram for explaining the configuration of the RFID circuit element 72 provided in the RFID tag 14. is there. As shown in FIG. 4, the RFID circuit element 72 has an antenna unit 74 for transmitting and receiving signals to and from the RFID tag communication apparatus 12, and processes a signal received by the antenna unit 74. And an IC circuit unit 76 for the purpose. The IC circuit unit 76 rectifies the interrogation wave F received from the RFID tag communication apparatus 12 received by the antenna unit 74, and stores the energy of the interrogation wave F rectified by the rectification unit 78. Power supply unit 80, a carrier wave force received by the antenna unit 74, a clock extraction unit 82 that extracts a clock signal and supplies it to the control unit 88, and a memory that functions as an information storage unit that can store a predetermined information signal Unit 84, modulation / demodulation unit 86 connected to the antenna unit 74 to modulate and demodulate signals, the RFID circuit element 72 via the rectification unit 78, the clock extraction unit 82, the modulation / demodulation unit 86, etc. And a control unit 88 for controlling the operation of the apparatus. The control unit 88 performs control for storing the predetermined information in the memory unit 84 by communicating with the RFID tag communication device 12, and the interrogation wave F received by the antenna unit 74. In 86, basic control such as control of reflecting and returning the response wave F as the response wave F from the antenna unit 74 is executed based on the information signal stored in the memory unit 84.

Returning to FIG. 2, the transmission data generation unit 50 generates transmission data to be transmitted to the wireless tag 14 on the carrier wave generated by the carrier wave generation unit 20, and in each transmission / reception module 24. Supply to transmission amplifier 64. In the transmission amplifier 64, modulation is performed based on the transmission data supplied from the transmission data generating unit 50 to obtain a transmission signal, which is transmitted from the antenna element 26 through the filter 68 and the like.

The directivity control unit 54 controls the transmission directivity and Z or reception directivity of the array antenna 16 composed of the plurality of antenna elements 26. Specifically, the transmission directivity of the array antenna 16 is controlled by controlling the phase of the transmission signal transmitted from the corresponding antenna element 26 via the transmission phase shifter 62 in each transmission / reception module 24. To do. Further, the reception directivity of the array antenna 16 is controlled by controlling the phase of the reception signal received by the corresponding antenna element 26 via the reception phase shift unit 70 in each transmission / reception module 24.

[0054] The signal strength detection unit 56 receives a signal of a reception signal received by the array antenna 16. Detect the strength of the signal. Specifically, the I-phase signal stored in the I-phase memory unit 38 and the Q-phase signal stored in the Q-phase memory unit 44 are read, and the square root of the sum of the squares of the I-phase signal and the Q-phase signal is calculated. The signal strength of the received signal corresponding to the I-phase signal and Q-phase signal is detected by calculation.

The obstacle direction detector 58 detects the direction in which the obstacle exists by comparing the received signals received as a result of transmission or reception by the array antenna 16. This detection is preferably performed based on the detection result of the signal intensity detection unit 56. That is, the obstacle direction detection unit 58 sets the direction in which the received signal strength is minimized or maximized as a direction in which the obstacle exists as a result of transmission or reception by the array antenna 16. To detect. The obstacle direction setting unit 59 sets the direction when the obstacle direction is known.

[0056] The direction detection unit 60 is received by the directivity control unit 54 when the transmission directivity and Z or reception directivity of the array antenna 16 is set to the directivity direction corresponding to the first angle. The radio tag is compared by comparing a received signal received in a directivity direction corresponding to a second angle shifted from the first angle by a predetermined deviation angle (minute angle). Detect 14 directions. Hereinafter, the direction detection control of the wireless tag 14 by the direction detection unit 60 will be described in detail.

FIG. 5 is a diagram for explaining multipath that occurs when the RFID tag communication system 10 is operated in the room 90. As shown in FIG. 5, when the RFID tag communication system 10 is operated in a room 90 having a wall 92 that is an obstacle (a radio wave reflector other than the RFID tag 14 to be detected) on all sides, the wall It is conceivable that a so-called multipath is generated in addition to the direct wave path due to reflection and diffraction caused by 92. In FIG. 5, direct waves and multipaths are indicated by solid line arrows when the transmission directivity and Z or reception directivity of the array antenna 16 are set to directivity directions corresponding to a predetermined first angle. The direct wave and multipath in the case of the directivity direction corresponding to the second angle shifted from the angle by a predetermined deviation angle are indicated by dashed arrows. When a multinos occurs in this way, the multinos and the direct wave have different phases depending on the path, so the signal of the direct wave path is strengthened by the signal of the multipath path. Or weakened. Also, due to multipath, radio waves can reach places where direct waves do not reach.

FIG. 6 shows signal strengths of received signals received when the first angle is changed stepwise by a predetermined angle and the directivity direction corresponding to the first angle is set. FIG. 6 is a diagram showing the signal strength of the received signal in comparison with the directivity direction corresponding to the second angle shifted by a predetermined deviation angle, corresponding to the first angle The received signal strength corresponding to the second angle is indicated by a broken line, and the received signal strength corresponding to the second angle is indicated by a broken line. FIG. 6 shows that the first angle is -40 with respect to a predetermined reference direction, for example, a direction indicated by a straight line passing through the antenna element 26b disposed in the center and perpendicular to the plane in which the antenna element 26 is disposed. The figure shows a case where the force is changed stepwise by 10 ° up to 40 °, and as such, the direction detection unit 60 preferably corresponds to the directivity corresponding to a predetermined relative angle range. The reception control unit 54 controls the array antenna 16 so that the transmission directivity and Z or reception directivity of the array antenna 16 are changed step by step by a predetermined angle, and is received corresponding to each transmission directivity and Z or reception directivity. The direction of the wireless tag 14 is detected by comparing the signals. Further, the deviation angle, that is, the deviation of the second angle from the first angle is preferably a predetermined angle of 1Z10 or more and 1Z5 or less, which is a step change of the first angle. In the example shown in Fig. 6, it is 1 °. Generally, even if the array antenna directivity direction is shifted within a range of 1 to 2 °, the received signal strength due to the direct wave is hardly changed, but the path difference between the direct wave and the indirect wave changes. As shown in Fig. 6, there is a significant difference in the signal strength of the received signal corresponding to each directivity. The direction detector 60 in the RFID tag communication apparatus 12 of the present embodiment compares the received signals corresponding to the respective directivity directions by shifting the directivity direction of the array antenna 16 within the range of 1 to 2 ° in this way. By doing so, the influence of multipath is small! Determine the directivity direction corresponding to the angle. The deviation angle is preferably equal to or smaller than an allowable error angle in the direction detection of the radio tag 14.

[0059] Specifically, the direction detection unit 60 sets the first angle by a predetermined angle by the directivity control unit 54 (for example, 10 ° up to 40 ° force 40 ° with respect to the reference direction). If the directionality corresponding to the first angle is changed step by step, V when the received signal or its signal strength is received and the directivity direction corresponding to the second angle shifted from the first angle by a predetermined deviation angle (for example, about 1 to 2 °), V, The direction of the wireless tag 14 is detected by comparing the received signal or its signal strength. Preferably, first, the directivity control unit 54 changes the transmission directivity and Z or reception directivity of the array antenna 16 while changing the first angle step by step by a predetermined angle. Is stored in the storage device such as the I-phase memory unit 38 and Z or Q-phase memory unit 44, and then the first signal is received. The directivity control unit 54 changes the transmission directivity and the Z or reception directivity of the array antenna 16 with respective first angular forces and second deviations shifted by a predetermined deviation angle. The received signal or the signal strength received when the directivity direction corresponding to the angle is stored in the storage device such as the I-phase memory unit 38 and Z or Q-phase memory unit 44, and stored in the storage device. Received signal or its signal Detecting the direction of the wireless tag 14 by comparing reading in degrees. In other words, first, in response to the first angle, the directivity control unit 54 changes the directivity of the array antenna 16 in steps of the predetermined angle within the predetermined angle range, thereby receiving the received signal or its signal strength. Then, the directivity control unit 54 changes the directivity of the array antenna 16 in steps of a predetermined angle within the predetermined angle range corresponding to the second angle. Control to memorize the signal strength. Further, in the control corresponding to the second angle, preferably, the result of the control corresponding to the first angle previously performed is considered, and a part of the control is performed as will be described later with reference to FIG. Is omitted. Hereinafter, the direction detection control of the wireless tag 14 will be described with reference to the flowcharts of FIGS. In the control shown in the flow charts of FIGS. 8 to 14, common steps are denoted by the same reference numerals and description thereof is omitted.

Preferably, the direction detection unit 60 receives each received signal stored in the I-phase memory unit 38 and the Z-phase memory unit 44 corresponding to the first angle and the second angle, respectively. Then, the detection results detected by the signal strength detection unit 56 are compared one by one, and the direction corresponding to the transmission directivity and Z or reception directivity at which the detection result takes the maximum value is compared with the wireless tag. Detected as 14 direction. FIG. 8 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed at a predetermined cycle.

In the control of FIG. 8, first, in step (hereinafter, step is omitted) S1, an angle Θ indicating the directivity direction is set to Θ which is an initial value. Next, in S 2, change the directivity direction to start

The transmission phase shifter 62 and Z or the reception phase shifter 70 are set so that the angle shown is 0, and a transmission signal is transmitted toward the wireless tag 14 that is a detection target, and a response is made to the transmission signal. Then, a transmission / reception process for receiving a reply signal returned from the wireless tag 14 is performed. Next, in S3, the signal strength of the received signal received by the transmission / reception processing of S2 is detected, and the detection result S is stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. Next, in S4, it is determined whether or not the force Θ indicating the directivity direction is a predetermined value Θ. If the determination of S4 is negative, the finger d in S5

After Δ 0 is added to the angle 0 indicating the directional direction, the processing after S2 is executed again, but when the determination of S4 is affirmed, the angle Θ indicating the directional direction is initially set in S6. The value is Θ. Next, in S 7, the angle indicating the directivity direction is Θ + 1. start

Thus, the transmission phase shifter 62 and Z or the reception phase shifter 70 are set to transmit a transmission signal to the wireless tag 14 to be detected, and in response to the transmission signal, the wireless tag Transmission / reception processing for receiving a reply signal returned from 14 is performed. Next, in S8, the signal strength of the received signal received by the transmission / reception processing in S7 is detected, and the detection result S is stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. The

Θ +1

Next, in S9, it is determined whether or not the force directional angle Θ is a predetermined value Θ end

It is. If the determination of S9 is negative, in S10, when Δ0 is added to the angle 0 indicating the directivity direction, and then the process of S7 and subsequent steps is executed again. In S11 corresponding to the operation of the direction detection unit 60, the received signal strengths S and S stored in the I-phase memory unit 38 and Z or Q-phase memory unit 44 are read and compared, and the maximum value is obtained. After Θ corresponding to the received signal strength taking the following is detected as the direction of the wireless tag 14, this routine is terminated. In the above control, S2 and S7 correspond to the operation of the directivity control unit 54, and S3 and S8 correspond to the operation of the signal intensity detection unit 56, respectively. Further, the direction detection unit 60 is preferably stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44 corresponding to the first angle and the second angle, respectively. For each received signal, the detection result detected by the signal intensity detection unit 56 is compared, and the detection result indicates which of the directivity direction corresponding to the first angle and the directivity direction corresponding to the second angle. The direction corresponding to the transmission directivity and Z or reception directivity that is equal to or greater than a predetermined threshold is detected as the direction of the wireless tag 14. FIG. 9 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed at a predetermined cycle. If the determination in S9 described above is affirmed in this control, the received signal stored in the I-phase memory unit 38 and Z or the Q-phase memory unit 44 in S12 corresponding to the operation of the direction detection unit 60. Intensities S and S are read and compared.

Θ Θ +1

Is detected as a direction of the wireless tag 14, the routine is terminated.

[0063] Further, the direction detection unit 60 is preferably stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44 corresponding to the first angle and the second angle, respectively. For each received signal, the detection result detected by the signal intensity detector 56 is compared, and the detection result of the directivity direction corresponding to the first angle and the detection result of the directivity direction corresponding to the second angle are compared. The direction corresponding to the angle having the smallest difference from the fruit is detected as the direction of the wireless tag 14. FIG. 10 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed at a predetermined cycle. If the determination in S9 described above is affirmed in this control, the received signal strength stored in the I-phase memory unit 38 and Z or the Q-phase memory unit 44 in S13 corresponding to the operation of the direction detection unit 60. S and S are read and the corresponding difference between s and S is calculated.

Θ Θ +1

After the direction corresponding to is detected as the direction of the wireless tag 14, this routine is ended.

Further, the direction detection unit 60 is preferably stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44 corresponding to the first angle and the second angle, respectively. For each received signal, the detection results detected by the signal intensity detection unit 56 with respect to the directivity direction corresponding to the first angle and the directivity direction corresponding to the second angle are averaged, In the directivity direction corresponding to the average large angle, the direction corresponding to the transmission directivity and Z or reception directivity in which the detection result has the maximum value is detected as the direction of the wireless tag 14. FIG. 11 is a flowchart for explaining the main part of the tag direction detection control of such a mode, and is repeatedly executed at a predetermined cycle. If the determination of S9 described above is affirmed in this control, V is stored in S14 corresponding to the operation of the direction detection unit 60, and stored in the I-phase memory unit 38 and Z or the Q-phase memory unit 44. Received signal strength S

Θ

, S are read out, and the average value (arithmetic mean) is calculated for each of S 1 and S, and S θ +1 Θ Θ +1

The angle at which the received signal strength takes the maximum value when

The average value of Θ s

Θ +1

After the direction corresponding to the degree 0 is detected as the direction of the wireless tag 14, this routine is terminated.

Further, the direction detection unit 60 is preferably based on the direction in which the obstacle is detected by the obstacle direction detection unit 58 or the direction set in the obstacle direction setting unit 59, for example. The direction of the wireless tag 14 is detected excluding the direction. FIG. 12 is a flowchart for explaining a main part of the tag direction detection control of such an aspect, and is repeatedly executed at a predetermined cycle. If the determination in S9 described above is affirmed in this control, it is stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44 in S15 corresponding to the operation of the obstacle direction detection unit 58. The received signal strengths S and S are read, and the received signal strengths S and S are compared to detect (determine) the direction in which the obstacle exists. Next, in S16 corresponding to the operation of the direction detection unit 60, it corresponds to the obstacle direction detected in S15 or an angle range that is more than a predetermined angle away from the direction set in the obstacle direction setting unit 59. S and S are compared and the maximum received signal strength is

Θ Θ +1

After the direction corresponding to the corresponding angle 0 is detected as the direction of the wireless tag 14, the routine is terminated.

[0066] In addition, the direction detection unit 60 preferably has a signal intensity S of a received signal that is less than or equal to a predetermined value when the directivity direction corresponds to the first angle! in case of

Θ

The detection of the received signal intensity s Θ +1 corresponding to the second angle shifted from the first angle by a predetermined deviation angle, that is, directivity control and transmission and Z or reception control of the radio signal are omitted. FIG. 7 is a diagram for explaining such control and corresponds to the first angle. The signal strength s of the received signal that is received when the directivity direction is

Θ

For the angles of 20 °, 30 °, and 40 °, detection of the received signal strength S corresponding to the second angles of 21 °, 29 °, and 39 ° is omitted. In addition, FIG.

Θ +1

5 is a flowchart for explaining a main part of the direction detection control, and is repeatedly executed at a predetermined cycle. In this control, the received signal strength S stored in the I-phase memory unit 38 and Z or the Q-phase memory unit 44 corresponding to the angle Θ at that time in S17 after the processing of S6 described above. Is read and the received signal strength S is greater than or equal to the specified value

Θ Θ

It is determined whether or not. When the determination at S17 is affirmed, the force at which the above-described processing after S7 is executed. When the determination at S17 is negative, the processing at S9 and below is executed. If the determination of S9 is affirmative, the received signal strength S stored in the I-phase memory unit 38 and the Z-phase memory unit 44 in S18 corresponding to the operation of the direction detection unit 60, S is read and the received signal strengths S and S

θ θ +1 θ Θ +1

After the direction of the wireless tag 14 is detected, this routine is terminated.

[0067] Further, the direction detection unit 60 preferably changes the frequency of the carrier wave of the transmission signal, that is, the frequency of the carrier wave generated by the carrier wave generation unit 20, and receives the signal corresponding to each frequency. The direction of the wireless tag 14 is detected by comparing the signals. FIG. 14 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed in a predetermined cycle. In this control, first, in S 19, the frequency set value f of the carrier wave generated by the carrier wave generator 20 is set to f ¾ and then S 1 or less.

1

The process is executed. If the determination in S9 described above is affirmed, it is determined in S20 whether or not the frequency set value f of the carrier wave generated by the carrier wave generation unit 20 is f. If the determination at S20 is negative, the power at which S1 and subsequent processing is executed again after S∆ is added to the frequency set value f at S21. In S22 corresponding to the operation of the direction detection unit 60, the received signal strengths S and S stored in the I-phase memory unit 38 and the Ζ or Q-phase memory unit 44 are read.

θ Θ +1 is extracted, and the direction of the wireless tag 14 is detected by comparing the received signal strengths S and S.

θ Θ +1

After being issued, this routine is terminated.

Thus, according to the present embodiment, a wireless signal to the wireless tag 14 that is a wireless terminal is transmitted. By controlling the phase corresponding to each of the plurality of antenna elements 26 and the array antenna 16 composed of a plurality of antenna elements 26 for transmitting and for receiving radio signals from Z or its radio tag 14 A directivity control unit 54 (S2 and S7) that controls the transmission directivity and Z or reception directivity of the array antenna 16, and the directivity control unit 54 control the transmission directivity and Z or reception directivity of the array antenna 16. The received signal received when the directivity corresponding to the first angle is set to the directivity direction corresponding to the second angle shifted by a predetermined deviation angle. And a direction detection rod 60 (S11, S12, S13, S14, S16, S18, S22) for detecting the direction of the wireless tag 14 by comparing the received signal with the received signal. From the said reception No. By using the reception result in the directivity direction corresponding to the angle is less affected multipath by comparing, it said can and preferably detect child the direction of the wireless tag 14. That is, it is possible to provide a direction detection device that reduces the influence of multipath and realizes suitable direction detection.

[0069] Further, a signal strength detection unit 56 (S3 and S8) for detecting the signal strength of the received signal received by the array antenna 16 is provided, and the direction detection unit 60 is detected by the signal strength detection unit. Since the direction of the wireless tag 14 is detected according to the signal strength, the direction of the wireless tag 14 can be detected in a practical manner.

[0070] Further, the direction detection unit 60 receives the received signal when the first angle is changed stepwise by a predetermined angle and the directivity direction corresponding to the first angle is received, or the signal thereof The intensity and the received signal received in the direction of directivity corresponding to the second angle or its signal intensity are stored in the I-phase memory unit 38 and Z or Q-phase memory unit 44 that are storage devices. Since the direction of the wireless tag 14 is detected by storing and comparing the received signal stored in the storage device or its signal strength, a directivity direction corresponding to an angle with less influence of multipath is practically used. Can be determined in a specific manner

The direction of the wireless tag 14 can be detected suitably.

[0071] Further, since the deviation angle is not less than 1Z10 and not more than 1Z5 of a predetermined angle that is a step change of the first angle, the directivity direction of the array antenna 16 is compared with the predetermined angle. The received signal corresponding to each directivity direction is shifted by a sufficiently small deviation angle. By comparing, it is possible to determine the directivity direction corresponding to the angle with less influence of the multipath, and the direction of the wireless tag 14 can be suitably detected.

[0072] Further, since the deviation angle is in the range of 1 to 2 °, the directivity direction of the array antenna 16 is shifted within the range of 1 to 2 °, and the received signal corresponding to each directivity direction is changed. By comparing, it is possible to determine the directivity direction corresponding to the angle with less influence of the multipath, and the direction of the wireless tag 14 can be suitably detected.

[0073] Further, since the deviation angle is equal to or smaller than the allowable error angle in the direction detection of the wireless tag 14, each directivity direction of the array antenna 16 is shifted within a range equal to or smaller than the allowable error angle in the direction detection. By comparing the received signals corresponding to the directivity direction, the directivity direction corresponding to the angle with less influence of the multipath can be determined, and the direction of the radio tag 14 can be detected suitably.

[0074] Further, the direction detection unit 60 first changes the first directivity stepwise by a predetermined angle step by step while the directivity control unit 54 performs transmission directivity and Z or reception directivity of the array antenna 16. Stored in the I-phase memory unit 38 and Z or Q-phase memory unit 44, and the received signal or signal strength received when the directivity is set to the directivity direction corresponding to each first angle. The directivity control unit 54 changes the transmission directivity and Z or reception directivity of the array antenna 16 to the respective first angular forces while changing the first angle step by step by a predetermined angle. The received signal or its signal strength received in the direction of directivity corresponding to the shifted second angle is stored in the I-phase memory unit 38 and Z or Q-phase memory unit 44, and the I-phase memory unit 38 And Z or Q phase memory Since the direction of the wireless tag 14 is detected by comparing the received signal or the signal strength thereof, the directivity direction corresponding to the angle can be determined in a practical manner with little multipath effect. It is possible to detect the direction of the wireless tag 14 suitably.

[0075] Further, the direction detection unit 60, when the signal strength of the received signal received when the directivity direction corresponds to the first angle is less than or equal to a predetermined value, Since there is no directivity control corresponding to the second angle shifted by a predetermined deviation angle and transmission and Z or reception control of the wireless signal, there is an obstacle, etc. For this reason, it is possible to shorten the time required for detecting the direction of the wireless tag 14 by performing suitable communication and omitting the control corresponding to the second angle according to the direction.

Further, the direction detection unit 60 (S 11) detects the detection result detected by the signal intensity detection unit 56 for each received signal stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. And the direction corresponding to the transmission directivity and Z or the reception directivity at which the detection result has the maximum value is detected as the direction of the wireless tag 14, so that the wireless tag 14 can be used in a practical manner. The direction of the tag 14 can be detected.

Further, the direction detection unit 60 (S12) detects the detection result detected by the signal intensity detection unit 56 for each received signal stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. And the transmission directivity and Z or reception directivity in which the detection result is equal to or greater than a predetermined threshold in both the directivity direction corresponding to the first angle and the directivity direction corresponding to the second angle. Since the direction corresponding to is detected as the direction of the wireless tag 14, the direction of the wireless tag 14 can be detected in a practical manner.

Further, the direction detection unit 60 (S13) detects the detection result detected by the signal strength detection unit 56 for each received signal stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. And the direction corresponding to the angle with the smallest difference between the detection result of the directivity direction corresponding to the first angle and the detection result of the directivity direction corresponding to the second angle is Since the direction is detected, the direction of the wireless tag 14 can be detected in a practical manner.

[0079] Further, the direction detection unit 60 (S14) has a directivity direction corresponding to the first angle and each received signal stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. The detection results detected by the signal intensity detection unit 56 for each of the directivity directions corresponding to the second angle are averaged, and the transmission result having the maximum detection value in the directivity direction corresponding to the large average angle is transmitted. Since the direction corresponding to the directivity and Z or reception directivity is detected as the direction of the wireless tag 14, the direction of the wireless tag 14 can be detected in a practical manner.

In addition, an obstacle direction detection unit 58 that detects the direction in which an obstacle exists by comparing the received signals or signal strengths stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44. (S15), and the direction detection unit 60 (S16) excludes the direction in which the obstacle is detected by the obstacle direction detection unit 58 or the direction set in the obstacle direction setting unit 59. Since the direction of the wireless tag 14 is detected, the direction of the wireless tag 14 can be suitably detected by avoiding the direction in which an obstacle that causes multipath occurs.

Further, the direction detection device transmits a predetermined transmission signal toward the detection target wireless tag 14 and receives a return signal returned from the wireless tag 14 in response to the transmission signal. Thus, the wireless tag communication device (wireless tag direction detection device) 12 that detects the direction of the wireless tag 14, the wireless tag that realizes the preferred direction detection of the wireless tag 14 by reducing the influence of multipath. A communication device 12 can be provided.

Further, the direction detection unit 60 (S22) detects the direction of the wireless tag 14 by changing the frequency of the carrier wave of the transmission signal and comparing the received signals received corresponding to the respective frequencies. Therefore, by comparing the received signals received corresponding to the respective directivity directions in each of the plurality of carrier frequencies, and using the reception result with the carrier frequency with less influence of the multipath, the wireless tag 14 The direction can be detected more suitably.

As described above, the preferred embodiment of the first invention has been described in detail with reference to the drawings. However, the first invention is not limited to this, and may be implemented in still another mode.

For example, the directivity control unit 54, the signal intensity detection unit 56, the obstacle direction detection unit 58, the direction detection unit 60, etc. are all provided individually in the above-described embodiment. However, this first invention is not limited to this, and a control function equivalent to those of DSP (Digital Signal Processor) that executes digital signal processing including CPU, ROM, RAM, etc. It may be provided functionally. Regardless of whether the control by these control devices is digital signal processing or analog signal processing.

In the above-described embodiment, each of the antenna elements 26 provided in the RFID tag communication apparatus 12 is a linear antenna element such as a dipole antenna, and the plurality of linear antenna elements 26 are used. Force that consisted of multiple sets of array antennas 16 For example, the antenna power of a flat (planar) antenna element such as a patch antenna The first invention can be suitably applied to a communication apparatus having such an antenna, even if it is configured.

In the above-described embodiment, the first angular force is received for each first angle when the directivity direction corresponds to a single second angle shifted by a predetermined deviation angle. For example, the power of detecting the direction of the wireless tag 14 by detecting the received signal and comparing the received signal corresponding to the second angle with the received signal corresponding to the first angle. When the first angle is Θ, the first angular force is also shifted by a predetermined deviation angle for each first angle, such that the angle Θ ± 1 is the second angle. Detecting the received signal when the directionality corresponds to the second angle, and comparing the received signal corresponding to the plurality of second angles with the received signal corresponding to the first angle The direction of the wireless tag 14 may be detected. In this way, it is possible to reduce the influence of multipath as much as possible and realize more suitable direction detection.

Further, in the above-described embodiment, the transmission / reception used for transmitting a transmission signal toward the wireless tag 14 and receiving a return signal returned from the wireless tag 14 in response to the transmission signal. Although the example in which the first invention is applied to the RFID tag communication device 12 having the shared antenna element 26 having the shared antenna element 26 has been described, the transmission antenna and the received signal for transmitting the transmitted signal are described above. The first invention is also suitably applied to an RFID tag communication apparatus that is separately provided with a receiving antenna for receiving the message.

In the above-described embodiment, a predetermined transmission signal is transmitted toward the wireless tag 14 that is a communication target, and a reply signal returned from the wireless tag 14 in response to the transmission signal is received. Thus, the example in which the first invention is applied to the RFID tag communication device 12 that communicates information with the RFID tag 14 has been described. However, other wireless communication devices such as a mobile phone and a mobile communication device have been described. The first invention can also be suitably applied to direction detection of a communication terminal in a communication device.

[0089] In addition, although not illustrated one by one, the first invention is implemented with various modifications without departing from the spirit thereof.

[0090] Next, a preferred embodiment of the second invention will be described in detail with reference to the drawings. Note that In the following description, parts common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

FIG. 15 is a diagram for explaining the configuration of a wireless tag communication device 93 according to an embodiment of the second invention. As shown in FIG. 2, the RFID tag communication apparatus 93 according to the present embodiment includes the carrier generation unit 20, the carrier amplification unit 22, the transmission / reception module 24, the antenna element 26, the reception signal synthesis unit 28, and the variable amplification unit 30 described above. A homodyne detection circuit 32, an I-phase LPF 34, an I-phase AZD conversion unit 36, an I-phase memory unit 38, a Q-phase LPF 40, a Q-phase AZD conversion unit 42, and a Q-phase memory unit 44. Also, a transmission circuit switching unit 46a that opens and closes a signal transmission circuit between the carrier wave amplification unit 22 and the transmission / reception module 24a, and a transmission circuit switching that opens and closes a signal transmission circuit between the carrier wave amplification unit 22 and the transmission / reception module 24c. Unit 46b (hereinafter simply referred to as a transmission circuit switching unit 46 unless otherwise distinguished from the transmission circuit switching unit 46a) and a reception circuit that opens and closes a signal transmission circuit between the transmission / reception module 24a and the reception signal synthesis unit 28. A circuit switching unit 48a and a reception circuit switching unit 48c that opens and closes a signal transmission circuit between the transmission / reception module 24c and the reception signal combining unit 28 (hereinafter simply referred to as a reception circuit unless otherwise distinguished from the reception circuit switching unit 48a). (Referred to as switching unit 48). In addition, in order to perform direction detection control for detecting the direction of the wireless tag 14, a transmission data generation unit 50, a directivity control unit 54, a signal intensity detection unit 56, an obstacle that performs control according to each control unit described above A direction detection unit 58, an obstacle direction setting unit 59, and a direction detection unit 60 are provided. In addition, an antenna selection control unit 52 is provided in addition to these.

The antenna selection control unit 52 transmits the transmission circuit switching unit 46, Z, or Z so that the signal is transmitted and Z or received by at least two antenna elements 26 of the plurality of antenna elements 26. The circuit is switched via the receiving circuit switching unit 48. In the RFID tag communication apparatus 93 of this embodiment, a plurality of sets of array antennas are selectively established by the plurality of antenna elements 26. That is, regarding transmission of a transmission signal to the wireless tag 14, the array antenna 16a including the antenna elements 26a and 26b is connected to the transmission circuit by connecting the transmission circuit switching unit 46a and opening 46c. When the switching unit 46a is opened and 46c is connected, the array antenna 16b composed of the antenna elements 26b and 26c is connected to the antenna circuit by connecting the transmission circuit switching units 46a and 46c together. An array antenna 16c consisting of children 26a, 26b and 26c is established. Further, with respect to reception of the reply signal from the wireless tag 14, the receiving circuit switching unit 48a is connected and the array antenna 16a including the antenna elements 26a and 26b is opened by the 48c being opened, so that the receiving circuit switching unit 48a is opened. The array antenna 16b composed of the antenna elements 26b and 26c is connected to the antenna elements 26a, 26b, and 26c by connecting both the receiving circuit switching units 48a and 48c. Each of the array antennas 16c is formed. In other words, the antenna selection control unit 52 is one of a plurality of sets of array antennas 16a, 16b, 16c (hereinafter simply referred to as array antenna 16 unless otherwise specified). To selectively switch the circuit so that a radio signal for the radio tag 14 is transmitted and Z or received. As described above, in the present embodiment, among the antenna elements 26 constituting the plurality of sets of array antennas 16, one antenna element 26b positioned at the center in the arrangement width direction of the antenna elements 26 is the plurality of sets. Common to array antenna 16

The directivity control unit 54 controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16. Specifically, the transmission directivity of each of the plurality of array antennas 16 is controlled by controlling the phase of the transmission signal transmitted from the corresponding antenna element 26 via the transmission phase shifter 62 in each transmission / reception module 24. To control. Further, the reception directivity of each of the plurality of sets of array antennas 16 is controlled by controlling the phase of the reception signal received by the corresponding antenna element 26 via the reception phase shift unit 70 in each transmission / reception module 24. .

The signal strength detector 56 detects the signal strength of the received signal corresponding to each of the plurality of array antennas 16. Specifically, the I-phase signal stored in the I-phase memory unit 38 and the Q-phase signal stored in the Q-phase memory unit 44 are read, and the square root of the sum of the squares of the I-phase signal and the Q-phase signal is calculated. The signal strength of the received signal corresponding to the I-phase signal and Q-phase signal is detected by calculation.

The obstacle direction detection unit 58 detects the direction in which the obstacle exists by comparing the received signals received as a result of transmission or reception by each of the plurality of array antennas 16. . This detection is preferably performed by the detection result of the signal intensity detection unit 56. Based on. That is, the obstacle direction detection unit 58 has the obstacle in a direction in which the signal intensity of the received signal received is minimized or maximized as a result of transmission or reception by each of the plurality of sets of array antennas 16. Detect as direction. The obstacle direction setting unit 59 sets the direction of the obstacle when the direction is known.

The direction detection unit 60 detects the direction in which the wireless tag 14 exists by comparing received signals received as a result of transmission and Z or reception by the plurality of array antennas 16. That is, for each of the array antennas 16 that is selectively established by the antenna selection control unit 52, transmission and Z or reception of a wireless signal to the wireless tag 14 are performed, and reception that is received corresponding to the wireless signal is performed. The direction in which the wireless tag 14 exists is detected by comparing the signals.

[0097] The plurality of antenna elements 26 provided in the RFID tag communication apparatus 93 of the present embodiment are preferably all linear antenna elements such as a dipole antenna, and the plurality of linear antenna elements 26 are the same. They are arranged in a plane so as to be parallel to each other and at equal intervals. Preferably, among the plurality of linear antenna elements 26 constituting the array antenna 16, the distance between the linear antenna elements 26 arranged farthest from each other, that is, the antenna elements 26a and 26c The distance between them is equal to or less than the wavelength of the carrier wave generated by the carrier wave generator 20. As described above, two sets of two linear antenna elements 26a and 26b, 26b and 26c adjacent to each other out of the three linear antenna elements 26 arranged so as to be parallel to each other. Array antennas 16a and 16b are respectively configured. Although not particularly illustrated, in addition to the configuration of FIG. 15 described above, a transmission circuit switching unit 46b that opens and closes a signal transmission circuit between the carrier wave amplification unit 22 and the transmission / reception module 24b, and the transmission / reception module 24b and reception signal synthesis The array antenna 16 is composed of two linear antenna elements 26a and 26c that are arranged farthest from each other by providing a receiving circuit switching unit 48b that opens and closes a signal transmission circuit with the unit 28. I'll do it for you.

FIG. 16 is a diagram for explaining multipath that occurs when the RFID tag communication system 10 to which the RFID tag communication apparatus 93 is applied is operated in the room 90. this As shown in FIG. 16, when the RFID tag communication system 10 is operated in a room 90 having walls 92 that are obstacles on all sides, a direct wave path is caused by reflection or diffraction caused by the walls 92. In addition to this, a so-called multipath may occur. In FIG. 16, the direct wave and multipath by the array antenna 16a consisting of the antenna elements 26a and 26b are indicated by solid arrows, and the direct wave and multipath by the array antenna 16b consisting of the antenna elements 26b and 26c are indicated by dashed arrows, respectively. And When a multipath occurs in this way, the multipath and the direct wave have different phases depending on the path, so the signal of the direct wave path is strengthened or weakened by the signal of the multipath path. . In addition, radio waves can reach places where direct waves cannot reach due to multipath. FIG. 17 and FIG. 18 are diagrams for explaining the difference in signal strength of the received signal when the directivity is similarly changed in the array antennas 16a and 16b. The signal strength of the signal is indicated by an arrow. As shown in FIGS. 17 and 18, since the path of the multipath is also changed by changing the position of the array antenna 16 with respect to the wall 92, which is an obstacle, the transmission directivity and Z of the array antennas 16a and 16b are changed. Or, even when the reception directivity is changed in the same way, the signal strength of the received signal varies depending on the directivity.

Specifically, the direction detection unit 60 controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and each transmission directivity and Z or The direction in which the wireless tag 14 exists is detected by comparing the detection results of the signal intensity detection unit 56 corresponding to the received signal received corresponding to the reception directivity. Preferably, each of the plurality of sets of array antennas 16 is transmitted by the directivity control unit 54 corresponding to a predetermined relative angle range such as 30 ° to 30 ° with respect to a predetermined center direction. The direction of the wireless tag 14 is detected by controlling the directivity and Z or reception directivity and comparing the received signals received corresponding to each transmission directivity and Z or reception directivity. Hereinafter, the direction detection control of the wireless tag 14 will be described with reference to the flowcharts of FIGS. In the control shown in the flowcharts of FIGS. 19 to 24, common steps are denoted by the same reference numerals and description thereof is omitted. [0100] Preferably, the direction detection unit 60 controls the transmission directivity and Z or reception directivity of each of the plurality of array antennas 16 by the directivity control unit 54, so that each transmission directivity and Compare the detection results detected by the signal strength detection unit 56 with respect to the received signal received corresponding to Z or reception directivity, and transmit directivity and Z or reception at which the detection result takes the maximum value. The direction corresponding to the directivity is detected as the direction of the wireless tag 14. FIG. 19 is a flowchart for explaining a main part of the tag direction detection control of such a mode, and is repeatedly executed at a predetermined cycle.

In the control of FIG. 19, first, in step (hereinafter, step is omitted) S101, from the plurality of array antennas 16 i = l (for example, for i = l, the array antenna 16a becomes i = l The array antenna 16 specified in (2) corresponds to the array antenna 16b), and the transmission circuit switching unit 46 and the Z or reception circuit switching unit 48 are switched so that the selected array antenna 16 is configured. It is done. Next, in S102, the angle Θ indicating the directivity direction is the initial value Θ

The transmission phase shift unit 62 and Z or the reception phase shift unit 70 are set according to the angle Θ. Next, in S103, a transmission / reception process is performed in which a predetermined transmission signal is transmitted to the detection target wireless tag 14 and a reply signal returned from the wireless tag 14 in response to the transmission signal is received. . Next, in S104 corresponding to the operation of the signal strength detection unit 56, the signal strength of the received signal received by the transmission / reception processing in S103 is detected, and the detection result S is used as the I-phase memory.

Ϊ Θ

Stored in the memory unit 38 and the Z or Q phase memory unit 44. Next, in S105, it is determined whether or not the angle Θ indicating the directivity direction is a predetermined value Θ. This S 105 judgment is denied

end

In S106, ΔΘ is added to the angle Θ indicating the directivity direction, and the transmission phase shifter 62 and Z or the reception phase shifter 70 are set according to the angle Θ. When the determination of the force S105 in which the processing from S103 onward is executed again is affirmed, it is determined in S107 whether or not the force for specifying the array antenna 16 is i. this

end

If the determination in S107 is negative, in S108, 1 is added to i, the array antenna 16 designated by i is selected, and the transmission circuit switching unit 46 and Z or the reception circuit switching unit 48 are switched. If the determination at S107 is affirmative after S102, the process at S102 and subsequent steps is executed again at S109 corresponding to the operation of the direction detection unit 60. The received signal strength S stored in the I-phase memory unit 38 and Z or the Q-phase memory unit 44 are all compared, and after Θ corresponding to S taking the maximum value is detected as the direction of the wireless tag 14, The routine is terminated. In the above control, S101 and S108 correspond to the operation of the antenna selection control unit 52, and S102 and S106 correspond to the operation of the directivity control unit 54, respectively.

[0102] In addition, the direction detection unit 60 preferably controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and transmits each transmission directivity. And the detection result detected by the signal intensity detection unit 56 for the received signal corresponding to Z or reception directivity is compared, and the detection result is equal to or greater than a predetermined threshold value in any of the plurality of sets of array antennas 16. The direction corresponding to the transmission directivity and Z or the reception directivity is detected as the direction of the wireless tag 14. FIG. 20 is a flowchart for explaining a main part of the tag direction detection control of such an aspect, and is repeatedly executed at a predetermined cycle. If the determination in S107 described above is affirmed in this control, the data is stored in the I-phase memory unit 38 and the Z-phase memory unit 44 in S110 corresponding to the operation of the direction detection unit 60. The received signal strength S is compared and the array

Ϊ Θ

Designate antenna 16 i = l ~ i for all angles where S is greater than or equal to a predetermined threshold A

end ΐ θ

After the direction corresponding to the angle Θ is detected as the direction of the wireless tag 14, this routine is terminated.

[0103] In addition, the direction detection unit 60 preferably controls the transmission directivity and the trapping or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and each transmission directivity. And the detection results detected by the signal intensity detection unit 56 for received signals received corresponding to Ζ or reception directivity, and the array having the smallest variation in the detection results among the plurality of sets of array antennas 16 The antenna 16 detects the direction of the radio tag 14 as the direction corresponding to the transmission directivity and Ζ or the reception directivity at which the detection result takes the maximum value. FIG. 21 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed at a predetermined cycle. In this control, if the determination in S107 described above is affirmed, the data is stored in the I-phase memory unit 38 and the Ζ or Q-phase memory unit 44 in SI 11 corresponding to the operation of the direction detection unit 60. Received The signal strength S is read out, and the array antenna 16 is specified. I = l to i

After the difference between the maximum value and the minimum value of S is calculated, and the direction corresponding to the angle 0 at which S takes the maximum value is detected as the direction of the wireless tag 14 in the array antenna 16 with the smallest difference. This routine is terminated.

[0104] In addition, the direction detection unit 60 preferably controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and each reception directivity. The detection results detected by the signal intensity detection unit 56 are averaged for the received signals received corresponding to the transmission directivity and Z or reception at which the detection result has the maximum value in the array antenna 16 having the largest average. A direction corresponding to directivity is detected as the direction of the wireless tag. FIG. 22 is a flowchart for explaining a main part of the tag direction detection control of such a mode, which is repeatedly executed at a predetermined cycle. If the determination in S107 described above is affirmed in this control, the reception stored in the I-phase memory unit 38 and Z or Q-phase memory unit 44 in S112 corresponding to the operation of the direction detection unit 60. The signal strength S is read and designates the array antenna 16 i = l to i

The average value of S (arithmetic average) is calculated for each of ίθ end, and the direction corresponding to the angle 0 at which S takes the maximum value is detected as the direction of the wireless tag 14 in the array antenna 16 having the largest average. Then, this routine is terminated.

Further, the direction detection unit 60 is preferably based on the direction in which the obstacle is detected by the obstacle direction detection unit 58 or the direction set in the obstacle direction setting unit 59, for example. The direction of the wireless tag 14 is detected excluding the direction. FIG. 23 is a flowchart for explaining a main part of the tag direction detection control of such an aspect, and is repeatedly executed at a predetermined cycle. If the determination in S107 described above is affirmed in this control, it is stored in the I-phase memory unit 38 and the Z-phase or Q-phase memory unit 44 in S113 corresponding to the operation of the obstacle direction detection unit 58. The received signal strength S is read, and the received signal strength S is compared to detect (determine) the direction in which the obstacle exists. Next, in S114 corresponding to the operation of the direction detection unit 60, S is detected in the obstacle range detected in S113 or in an angle range that is more than a predetermined angle away from the direction set in the obstacle direction setting unit 59. The direction corresponding to the angle 0 taking the maximum value is the wireless tag 14 After the direction is detected, this routine is terminated.

[0106] Further, the direction detection unit 60 preferably changes the frequency of the carrier wave of the transmission signal, that is, the frequency of the carrier wave generated by the carrier wave generation unit 20, and is received corresponding to each frequency. The direction of the wireless tag 14 is detected by comparing the signals. FIG. 24 is a flowchart for explaining a main part of the tag direction detection control in this mode, and is repeatedly executed in a predetermined cycle. In this control, first, in S115, the frequency set value f of the carrier wave generated by the carrier wave generating unit 20 is set to f ¾ and then S101 and thereafter.

1

The following processing is executed. If the determination in S107 described above is affirmed, it is determined in S116 whether or not the frequency set value f of the carrier wave generated by the carrier wave generation unit 20 is f end. When the determination at S116 is negative, the force at which S101 and subsequent processes are executed again after Δ ί is added to the frequency set value f at S117. When the determination at S116 is affirmative. Then, in S118 corresponding to the operation of the direction detection unit 60, the received signal strength S stored in the I-phase memory unit 38 and the 対応 or Q-phase memory unit 44 is read out, and the received signal strength S is obtained. By comparing, the direction of the wireless tag 14 ϊ θ Ϊ Θ

Is detected, the routine is terminated.

Thus, according to the present embodiment, a plurality of antenna elements each for transmitting a radio signal to the radio tag 14 and / or for receiving a radio signal of the power of the radio tag 14 are used. Direction in which the direction of the wireless tag 14 is detected by comparing the received signals received as a result of transmission, reception, or reception by the plurality of array antennas 16 each including the plurality of array antennas 16 configured by 26. Since the detection unit 60 (S109, S110, Sill, S112, S114, S118) is provided, the reception result of the array antenna 16 that has less influence of multipath is used by comparing the reception signals. Thus, the direction of the wireless tag 14 can be suitably detected. That is, it is possible to provide a direction detection device that realizes suitable direction detection by reducing the influence of multipath.

[0108] Further, it includes a directivity control unit 54 (S102 and S106) for controlling the transmission directivity and Z or reception directivity of each of the multiple & array antennas 16, and the direction detection unit 60 includes the directivity control unit 54. The control unit 54 controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 and corresponds to each transmission directivity and Z or reception directivity. The direction of the wireless tag 14 is detected by comparing the received signals received in response to each of the transmission directivities and Z or reception directivities in each of the plurality of sets of array antennas 16. By comparing the received signals received and using the reception result by the array antenna 16 that is less affected by multipath, the direction of the wireless tag 14 can be suitably detected.

[0109] Further, a signal strength detection unit 56 (S104) for detecting the signal strength of the received signal received by the array antenna 16 is provided, and the direction detection unit 60 is detected by the signal strength detection unit 56. Therefore, the direction of the wireless tag 14 can be detected in a practical manner.

[0110] Further, among the antenna elements 26 constituting the plural sets of array antennas 16, at least one antenna element 26 is shared by the plural sets of array antennas 16, so The space occupied by the _ array antenna 16 can be made as small as possible, and the apparatus can be downsized.

[0111] Further, the antenna selection control for switching the circuit so that the radio signal to the radio tag 14 is selectively transmitted and Z or received by any one of the array antennas 16 of the plurality of array antennas 16 Since each of the array antennas 16 (S101 and S108) is sequentially switched by the antenna selection control unit 52 to transmit and Z or receive the radio signal for the radio tag 14, the array antenna 16 Therefore, it is possible to simplify the configuration of the device that does not require the reception signal processing circuit to be provided.

[0112] Further, the direction detection unit 60 (S109) controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and transmits each transmission direction. The received signal received corresponding to the transmission characteristics and Z or reception directivity is compared with the detection results detected by the signal intensity detection unit 56, and the detection result takes the maximum value. Since the direction corresponding to the directivity is detected as the direction of the wireless tag 14, the direction of the wireless tag 14 can be detected in a practical manner.

[0113] Further, the direction detection unit 60 (S110) is configured to transmit the plurality of sets of keys by the directivity control unit 54. The detection of the received signal received corresponding to each transmission directivity and Z or reception directivity is detected by the signal intensity detector 56 by controlling the transmission directivity and Z or reception directivity of each of the ray antennas 16. Compare the results, and detect the direction corresponding to the transmission directivity and Z or reception directivity that the detection result is equal to or greater than a predetermined threshold in any of the plurality of sets of array antennas 16 as the direction of the wireless tag 14. Therefore, the direction of the wireless tag 14 can be detected in a practical manner.

[0114] Further, the direction detection unit 60 (S111) controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and transmits each transmission directivity. And the detection results detected by the signal intensity detection unit 56 for received signals received corresponding to Z or reception directivity, and the variation in the detection results of the plurality of sets of array antennas 16 is the least. The direction corresponding to the transmission directivity and Z or reception directivity at which the detection result of the array antenna 16 takes the maximum value is detected as the direction of the wireless tag 14, so that the wireless tag 14 is used in a practical manner. The direction of can be detected.

[0115] Further, the direction detection unit 60 (S112) controls the transmission directivity and Z or the reception directivity of each of the plurality of sets of array antennas 16 by the directivity control unit 54, and each reception directivity. The detection results detected by the signal intensity detection unit 56 are averaged with respect to the received signals received corresponding to the transmission antennas, and the transmission directivity and the maximum detection value of the array antenna 16 having the largest average are obtained. Since the direction corresponding to Z or the reception directivity is detected as the direction of the wireless tag 14, the direction of the wireless tag 14 can be detected in a practical manner.

[0116] Since the array antenna 16 is composed of a plurality of linear antenna elements 26 arranged so as to be parallel to each other, the array antenna 16 is practically composed of a plurality of linear antenna elements 26. In a direction detection apparatus having a flexible array antenna 16, it is possible to reduce the influence of multipath and realize suitable direction detection.

[0117] Of the plurality of linear antenna elements 26 constituting the array antenna 16, the distance between the linear antenna elements 26 arranged farthest from each other is determined by the carrier of the radio signal. The space occupied by the multiple sets of array antennas 16 is less than the wavelength. It can be made as small as possible, and thus the apparatus can be miniaturized.

[0118] Further, the plurality of sets of array antennas 16 are respectively composed of two linear antenna elements 26 adjacent to each other among the three linear antenna elements 26 arranged so as to be parallel to each other. 2 array antennas 16 that correspond to two sets of array antennas 16 that are selectively composed of three linear antenna elements 26 arranged so as to be parallel to each other. By comparing the received signals, the direction of the wireless tag 14 can be suitably detected.

[0119] In addition, the plurality of sets of array antennas 16 also includes two linear antenna elements 26 adjacent to each other among the three linear antenna elements 26 arranged so as to be parallel to each other. The two array antennas 16 and the two array antennas 16 that are arranged at the furthest distance from each other are arranged in parallel with each other. By comparing the received signals corresponding to each of the three sets of array antennas 16 that are selectively configured from the three linear antenna elements 26 provided, the direction of the wireless tag 14 can be suitably detected. .

[0120] Further, the direction detection unit 60 corresponds to a predetermined relative angle range determined in advance, and the directivity control unit 54 performs transmission directivity and Z or reception of each of the plurality of sets of array antennas 16. The direction of the wireless tag 14 is detected by controlling the directivity and comparing the received signals received corresponding to each transmission directivity and Z or reception directivity. By limiting the target range, the time required to detect the wireless tag 14 can be shortened.

[0121] In addition, obstacle direction detection that detects the direction in which an obstacle exists by comparing the received signals as a result of transmission and Z or reception by each of the array antennas 16 of multiple & 58 (S113), the direction detection unit 60 (S114) excludes the direction in which the obstacle is detected by the obstacle direction detection unit 58 or the direction set in the obstacle direction setting unit 59. Since the direction of the wireless tag 14 is detected, the direction of the wireless tag 14 can be suitably detected by avoiding the direction in which an obstacle causing multipath occurs.

[0122] In addition, the direction detection device according to the present embodiment transmits a predetermined transmission toward the wireless tag 14 to be detected. Since the wireless tag direction detection device 12 detects the direction of the wireless tag 14 by receiving a reply signal transmitted from the wireless tag 14 in response to the transmission signal, It is possible to provide a wireless tag direction detection device that realizes detection of a preferable wireless tag direction by reducing the influence of a path.

[0123] Further, the direction detection unit 60 (S108) changes the frequency of the carrier wave of the transmission signal, and compares the reception signal received corresponding to each frequency, thereby comparing the direction of the wireless tag 14 Therefore, by comparing the received signals received corresponding to each reception directivity at each of a plurality of carrier frequencies, and using the reception result with the carrier frequency with less multipath influence, The direction of the wireless tag 14 can be detected suitably.

[0124] Next, another preferred embodiment of the direction detection device of the second invention will be described in detail with reference to the drawings. FIG. 25 is a view for explaining the configuration of an RFID tag communication apparatus 94 which is another preferred embodiment of the direction detection apparatus of the second invention. As shown in FIG. 25, the wireless tag communication device 94 of this embodiment includes a received signal combining unit 28a that is a combining unit that combines (adds) the received signals supplied from the transmission / reception modules 24a and 24b. A variable amplification unit 30a that amplifies the combined signal supplied from the received signal combining unit 28a, a homodyne detection circuit 32a that detects the combined signal supplied from the variable amplification unit 30a, and a homodyne detection circuit 32a I-phase LPF34a that passes only signals in the specified frequency band from the I-phase signal output from the I-phase AZ D converter 36a that digitally converts the I-phase signal that has passed through the I-phase LPF 34a, and its I-phase An I-phase memory unit 38a for storing the signal digitally converted by the AZD conversion unit 36a, a Q-phase LPF 40a for passing only a signal in a predetermined frequency band among the Q-phase signals output from the homodyne detection circuit 32a, Q phase LP Q-phase AZD converter 42a that digitally converts the Q-phase signal that has passed through F40a, Q-phase memory 44a that stores the signal digitally converted by the Q-phase AZD converter 42a, and the transmission / reception module 24b Receiving signal synthesizer 28b that combines (adds) received signals supplied from 24c, variable amplifying unit 30b that amplifies the combined signal supplied from the received signal combining unit 28b, and its variable A homodyne detection circuit 32b that detects the combined signal supplied from the amplification unit 30b and the I-phase signal output from the homodyne detection circuit 32b. The I-phase LPF34b that passes only signals in the specified frequency band, the I-phase AZD converter 36b that digitally converts the I-phase signal that has passed through the I-phase LPF34b, and the signal digitally converted by the I-phase AZD converter 36b I-phase memory 38b, Q-phase LPF40b that passes only signals in the specified frequency band among the Q-phase signals output from the homodyne detection circuit 32b, and Q-phase signals that have passed through the Q-phase LPF40b are digital A Q-phase AZ D conversion unit 42b for conversion and a Q-phase memory unit 44b for storing signals digitally converted by the Q-phase AZD conversion unit 42b are provided.

As described above, the RFID tag communication apparatus 94 according to the present embodiment includes reception signal processing circuits such as the reception signal synthesis unit 28a, the variable amplification unit 30a, and the homodyne detection circuit 32a corresponding to the array antenna 16a. Corresponding to the array antenna 16b, reception signal processing circuits such as a reception signal synthesis unit 28b, a variable amplification unit 30b, and a homodyne detection circuit 32b are provided independently, and the array antennas 16a and 16b The wireless tag is configured to receive as many as 14 wireless signals at the same time, so the processing time of the wireless signal can be shortened as much as possible, and thus the time required for detection of the wireless tag 14 Can be shortened

FIG. 26 is a diagram for explaining the configuration of a wireless tag communication device 96 that is still another preferred embodiment of the direction detection device according to the second aspect of the present invention. As shown in FIG. 26, the RFID tag communication apparatus 96 of the present embodiment has an antenna element 26d in addition to the antenna elements 26a, 26b, and 26c, and a transmission / reception module 24d corresponding to the antenna element 26d. It has. This transmission / reception module 24d has the same configuration as the transmission / reception modules 24a, 24b, 24c, etc. described above with reference to FIG. 3, and processes transmission signals based on the carrier wave supplied from the carrier wave amplification unit 22. The received signal transmitted from the antenna element 26d and received by the antenna element 26d is processed and supplied to the received signal combining unit 28. Also, a transmission circuit switching unit 46b that opens and closes a signal transmission circuit between the carrier wave amplification unit 22 and the transmission / reception module 24b, and a transmission circuit that opens and closes a signal transmission circuit between the carrier wave amplification unit 22 and the transmission / reception module 24d. A switching unit 46d, a reception circuit switching unit 48b for opening and closing a signal transmission circuit between the transmission / reception module 24b and the reception signal synthesis unit 28, and a signal transmission circuit between the transmission / reception module 24d and the reception signal synthesis unit 28. Open / close receiving circuit The reception signal synthesizer 28 is selectively selected from the transmission / reception modules 24a, 24b, 24c, 24d according to the opening / closing of the reception circuit switching units 48a, 48b, 48c, 48d. Is combined with the received signal.

[0127] The four antenna elements 26 provided in the RFID tag communication apparatus 96 of the present embodiment are all linear antenna elements such as dipole antennas, and the plurality of linear antenna elements 26 are in the same plane. Are arranged at equal intervals so as to be parallel to each other. Of these four linear antenna elements 26, at least two antenna element 26 forces constitute the array antenna 16 for transmission and Z or reception. For example, three sets of array antennas 16 are constituted by two linear antenna elements 26 adjacent to each other among the four linear antenna elements 26. That is, the antenna elements 26a and 26b constitute an array antenna 16a, the antenna elements 26b and 26c constitute an array antenna 16b, and the antenna elements 26c and 26d constitute an array antenna 16c. Further, any of the three linear antenna elements 26 selected from the four linear antenna elements 26 constitutes two sets of array antennas 16. That is, the antenna elements 26a, 26b, and 26c constitute the array antenna 16d, and the antenna elements 26b, 26c, and 26d constitute the array antenna 16e. In the RFID tag communication device 96, a plurality of sets of array antennas 16 as described above are selectively established by the antenna selection control unit 52 via the transmission circuit switching unit 46 and Z or the reception circuit switching unit 48. The array antenna 16 transmits and Z or receives a wireless signal to the wireless tag 14.

[0128] Thus, according to the present embodiment, the plurality of sets of array antennas 16 includes two linear antenna elements 26 arranged so as to be parallel to each other and two adjacent to each other. Since there are three sets of array antennas 16a, 16b, 16c composed of linear antenna elements 26, they are selectively composed of four linear antenna elements 26 arranged in parallel to each other. By comparing the received signals corresponding to the three sets of array antennas 16a, 16b, and 16c, the direction of the wireless tag 14 can be suitably detected.

[0129] Further, the plurality of sets of array antennas 16 are composed of any three linear antenna elements 26 selected from four linear antenna elements 26 arranged so as to be parallel to each other. 2 sets of array antennas 16d and 16e, so they are arranged parallel to each other The direction of the wireless tag 14 can be suitably detected by comparing the received signals corresponding to each of the two sets of array antennas 16 that are selectively composed of the four linear antenna elements 26 .

[0130] The preferred embodiment of the second invention has been described in detail with reference to the drawings. However, the second invention is not limited to this embodiment, and may be implemented in another mode.

[0131] For example, in the above-described embodiment, the antenna selection control unit 52, the directivity control unit 54, the signal strength detection unit 56, the obstacle direction detection unit 58, the obstacle direction setting unit 59, and the direction detection unit 60 However, the second invention is not limited to this, and the same control functions as those include CPU, ROM, RAM, etc. for digital signal processing. A DSP (Digital Signal Processor) to be executed or the like may be functionally provided. Regardless of whether the control by these control devices is digital signal processing or analog signal processing.

In the above-described embodiment, each of the antenna elements 26 provided in the RFID tag communication device 93 is a linear antenna element such as a dipole antenna, and the plurality of linear antenna elements 26 are used. Forces that consist of multiple sets of array antennas 16 For example, a flat (planar) antenna element force such as a patch antenna may be used to configure an array antenna. The second invention can be suitably applied to an apparatus.

[0133] In the above-described embodiment, a predetermined transmission signal is transmitted to the wireless tag 14 that is a communication target, and a reply signal returned from the wireless tag 14 in response to the transmission signal is received. Thus, the example in which the second invention is applied to the wireless tag communication device 93 that performs information communication with the wireless tag 14 has been described. However, other wireless devices such as a mobile phone and a mobile communication device have been described. The second aspect of the present invention can also be suitably applied to direction detection of a communication terminal in a communication device.

[0134] Although not illustrated one by one, the second invention is implemented with various modifications within the scope not departing from the gist thereof.

Claims

The scope of the claims

[1] A direction detection device that performs transmission and Z or reception of a wireless signal to a wireless terminal, and detects the direction of the wireless terminal based on the wireless signal,

An array antenna composed of a plurality of antenna elements for transmitting a radio signal to the radio terminal and receiving a radio signal of Z or the radio terminal power, and a phase corresponding to each of the plurality of antenna elements A directivity control unit for controlling the transmission directivity and Z or reception directivity of the array antenna by controlling

Received signal received when the directivity control unit sets the transmission directivity and Z or reception directivity of the array antenna to the directivity direction corresponding to the first angle, and the first angular force predetermined deviation A direction detection unit that detects the direction of the wireless terminal by comparing the received signal received in the case of the directivity direction corresponding to the second angle shifted in angle;

A direction detecting device characterized by comprising:

[2] A signal strength detection unit that detects a signal strength of a reception signal received by the array antenna is provided, and the direction detection unit is configured to correspond to the signal strength detected by the signal strength detection unit. The direction detection device according to claim 1, wherein the direction detection device detects a direction of.

[3] The direction detection unit receives the received signal or its signal strength when the first angle is changed stepwise by a predetermined angle and the directivity direction corresponds to the first angle. The received signal received in the direction of directivity corresponding to the second angle or the signal strength thereof is stored in a predetermined storage device, and the received signal stored in the storage device or the signal strength thereof is stored. 3. The direction detection device according to claim 2, wherein the direction of the wireless terminal is detected by comparing the two.

4. The direction detecting device according to claim 3, wherein the deviation angle is not less than 1Z10 and not more than 1Z5 of a predetermined angle that is a stepwise change in the first angle.

[5] The direction detection device according to any one of claims 1 to 4, wherein the deviation angle is within a range of 1 to 2 °.

[6] The direction detection device according to any one of claims 1 to 5, wherein the deviation angle is equal to or smaller than an allowable error angle in direction detection of the wireless terminal.

[7] The direction detection unit first changes each of the transmission directivity and Z or reception directivity of the array antenna by the directivity control unit while gradually changing the first angle by a predetermined angle. The received signal or the signal strength received in the case of the directivity direction corresponding to the angle of 1 is stored in the storage device, and then the first angle is changed step by step by a predetermined angle. Received when the directivity control unit sets the transmit directivity and Z or receive directivity of the array antenna to a directivity direction corresponding to a second angle shifted from the first angle by a predetermined deviation angle. The received signal or its signal strength is stored in the storage device, and the direction of the wireless terminal is detected by comparing the received signal stored in the storage device or its signal strength. Either Direction detection device.

[8] The direction detection unit, when the signal strength of the received signal received when the directivity direction corresponds to the first angle is less than or equal to a predetermined value, 8. The direction detection device according to claim 7, wherein directivity control corresponding to a second angle shifted by a constant deviation angle and transmission and Z or reception control of the radio signal are not performed.

[9] The direction detection unit compares the detection results detected by the signal intensity detection unit for each received signal stored in the storage device, and the transmission directivity at which the detection result takes a maximum value. And a direction corresponding to Z or a reception directivity is detected as the direction of the wireless terminal.

[10] The direction detection unit compares detection results detected by the signal intensity detection unit for each received signal stored in the storage device, and the detection result corresponds to the directivity corresponding to the first angle. The direction corresponding to the transmission directivity and Z or reception directivity that are equal to or greater than a predetermined threshold value in any of the direction and the directivity direction corresponding to the second angle is detected as the direction of the wireless terminal. Any direction detection device from 2 to 8.

[11] The direction detection unit compares a detection result detected by the signal intensity detection unit for each received signal stored in the storage device, and detects a directivity direction corresponding to the first angle. 9. The direction detection device according to claim 2, wherein the direction corresponding to the angle with the smallest difference between the result and the detection result of the directivity direction corresponding to the second angle is detected as the direction of the wireless terminal. .

[12] The direction detection unit includes the signal intensity detection unit for each of the reception signals stored in the storage device with respect to the directivity direction corresponding to the first angle and the directivity direction corresponding to the second angle. Average the detection results detected by the transmission direction, and in the directivity direction corresponding to the average large angle, the direction corresponding to the transmission directivity and Z or reception directivity where the detection result takes the maximum value is the direction of the wireless terminal. 9. The direction detection device according to claim 2, wherein the direction detection device is for detection.

[13] An obstacle direction detection unit that detects a direction in which an obstacle exists by comparing each received signal or signal intensity stored in the storage device, or sets the direction of the obstacle if the direction is known An obstacle direction setting unit, wherein the direction detection unit excludes the direction in which the obstacle is detected by the obstacle direction detection unit or the direction set in the obstacle direction setting unit, and the direction of the wireless terminal The direction detecting device according to any one of claims 1 to 12, wherein the direction detecting device is a device for detecting the above.

[14] The direction detection device transmits a predetermined transmission signal toward the detection target wireless tag and receives a return signal returned from the wireless tag in response to the transmission signal. The wireless tag direction detecting device for detecting a direction of the wireless tag

Any one of the direction detection devices of 3.

15. The direction detecting unit detects a direction of the wireless tag by changing a frequency of a carrier wave of the transmission signal and comparing a reception signal received corresponding to each frequency. 14 direction detection devices.

[16] A direction detection device that performs transmission and Z or reception of a wireless signal to a wireless terminal, and detects the direction of the wireless terminal based on the wireless signal,

A plurality of sets of array antennas each configured by a plurality of antenna elements for transmitting a radio signal to the radio terminal and for receiving a radio signal of Z or the radio terminal power;

A direction detection unit that detects the direction of the wireless terminal by comparing the received signals received as a result of transmission and Z or reception by each of the plurality of sets of array antennas. Direction detection device.

[17] Control the transmission directivity and Z or reception directivity of each of the plurality of array antennas. A directivity control unit that controls the transmission directivity and z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit, and each transmission directivity and Z or 17. The direction detection device according to claim 16, wherein the direction of the wireless terminal is detected by comparing reception signals received corresponding to reception directivities.

[18] A signal strength detection unit that detects a signal strength of a reception signal received by the array antenna is provided, and the direction detection unit is configured to correspond to the signal strength detected by the signal strength detection unit. 18. The direction detection device according to claim 16 or 17, wherein the direction detection device detects the direction of the direction.

19. The direction detecting device according to claim 16, wherein at least one antenna element among the antenna elements constituting the plurality of sets of array antennas is shared by the plurality of sets of array antennas.

[20] An antenna selection control unit that switches a circuit so that a radio signal for the wireless terminal is selectively transmitted and Z or received by any one of the plurality of array antennas. The direction detection device according to any one of claims 16 to 19

21. A reception signal processing circuit corresponding to each of the plurality of sets of array antennas, wherein the plurality of sets of array antennas simultaneously receive a radio signal from the radio terminal. Any one of 19 direction detection apparatuses.

[22] The direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit, and supports each transmission directivity and Z or reception directivity. The reception result received by the signal strength detection unit is compared with the detection results detected by the signal intensity detector, and the direction corresponding to the transmission directivity and the Z or reception directivity at which the detection result takes the maximum value is determined. The direction detection device according to any one of claims 18 to 21, wherein the direction detection device detects the direction as a direction.

[23] The direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit, and corresponds to each transmission directivity and Z or reception directivity. Then, the detection results detected by the signal intensity detection unit are compared for the received signal received, and the detection result is determined by any of the plurality of array antennas! However, the direction corresponding to the transmission directivity and Z or reception directivity that are equal to or greater than a predetermined threshold is not The direction detection device according to any one of claims 18 to 21, wherein the direction detection device detects the direction of the line terminal.

[24] The direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit, and corresponds to each transmission directivity and Z or reception directivity. The detection results detected by the signal intensity detection unit are compared for the received signals received in the same manner, and the detection results of the array antennas with the smallest variation in the detection results are compared among the plurality of sets of array antennas. The direction detection device according to any one of claims 18 to 21, wherein a direction corresponding to transmission directivity and Z or reception directivity at which the maximum value is detected as a direction of the wireless terminal.

[25] The direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit, and supports each transmission directivity and Z or reception directivity. The detection results detected by the signal intensity detection unit are averaged for the received signals received in response to the transmission directivity and Z or reception directivity at which the detection result has the maximum value in the array antenna having the largest average. The direction detecting device according to any one of claims 18 to 21, wherein a direction to be detected is detected as a direction of the wireless terminal.

26. The direction detection device according to claim 16, wherein the array antenna is also configured with a plurality of linear antenna element forces arranged so as to be parallel to each other.

[27] Of the plurality of linear antenna elements constituting the array antenna, the distance between the linear antenna elements arranged farthest from each other is equal to or less than the wavelength of the carrier wave of the radio signal 27. The direction detection device according to claim 26.

[28] The plurality of sets of array antennas are composed of two sets of linear antenna element forces each adjacent to each other among three linear antenna elements arranged so as to be parallel to each other. The direction detection device according to claim 26 or 27, wherein the direction detection device is an array antenna.

[29] The plurality of sets of array antennas include two sets of two linear antenna element forces adjacent to each other among three linear antenna elements arranged so as to be parallel to each other. 28. The direction detection device according to claim 26 or 27, wherein the array antenna is a pair of array antennas, and the force of two linear antenna elements arranged farthest from each other is also configured.

[30] The plurality of sets of array antennas includes three sets of array antennas that are configured by two linear antenna element forces adjacent to each other among four linear antenna elements arranged so as to be parallel to each other. The direction detection device according to claim 26 or 27.

[31] The plurality of sets of array antennas include two sets of four linear antenna elements selected from four linear antenna elements arranged so as to be parallel to each other. The direction detection device according to claim 26 or 27, wherein the direction detection device is an array antenna.

[32] The direction detection unit controls the transmission directivity and Z or reception directivity of each of the plurality of sets of array antennas by the directivity control unit corresponding to a predetermined relative angle range determined in advance. 32. The direction detection device according to claim 17, wherein the direction of the wireless terminal is detected by comparing reception signals received corresponding to transmission directivity and Z or reception directivity.

[33] As a result of transmission or reception by each of the plurality of sets of array antennas, an obstacle direction detection unit that detects a direction in which an obstacle exists by comparing received received signals, or an obstacle in advance When the direction is known, an obstacle direction setting unit is provided for setting the direction of the obstacle. The direction detection unit is a direction in which the obstacle is detected by the obstacle direction detection unit, or the obstacle direction. The direction detection device according to any one of claims 16 to 32, wherein the direction of the wireless terminal is detected by excluding the direction set in the setting unit.

[34] The direction detection device transmits a predetermined transmission signal toward the detection target wireless tag, and receives a reply signal returned from the wireless tag in response to the transmission signal. 34. The direction detection device according to claim 16, wherein the direction detection device is a wireless tag direction detection device that detects a direction of the wireless tag.

[35] The direction detection unit detects a direction of the wireless tag by changing a frequency of a carrier wave of the transmission signal and comparing a reception signal received corresponding to each frequency. 34 direction detection devices.