WO2006080300A1

WO2006080300A1 - Antenna device, antenna driving method and id tag reader

Info

Publication number: WO2006080300A1
Application number: PCT/JP2006/301031
Authority: WO
Inventors: Takashi Takano
Original assignee: Central Engineering Co., Ltd.
Priority date: 2005-01-26
Filing date: 2006-01-24
Publication date: 2006-08-03
Also published as: JPWO2006080300A1; JP4803755B2

Abstract

An antenna device for more surely detecting a plurality of ID tags near the center of a long and thin space, an antenna driving method and an ID tag reader are provided. The antenna device is provided with facing antennas (13, 14), which are two loop antennas arranged to face each other, a resonant antenna circuit (15) which is arranged between the facing antennas and is provided with a loop antenna configuring a resonant circuit, and an antenna driving circuit (10) for driving the facing antennas. Alternatively, the antenna device is provided with a plurality of loop antennas arranged on every two facing rectangular parallelepiped faces, and an antenna driving circuit for driving each antenna in a desired phase so that a magnetic flux having a component parallel to facing two planes at the center part of the rectangular parallelepiped is generated. Since sufficient power is supplied to an ID tag even near a shelf (12), ID information can be detected at a higher accuracy.

Description

Specification

Antenna device, antenna driving method, and ID tag reader

Technical field

TECHNICAL FIELD [0001] The present invention relates to an antenna device, an antenna driving method, and an ID tag reader, and communicates with an ID tag activated by AC magnetic field and received radio wave power to obtain operating power, and stores information stored in the ID tag. The present invention relates to an antenna device, an antenna driving method, and an ID tag reader that can detect an ID with respect to a plurality of ID tags in a long and narrow space in a RFID (Radio Frequency Identification) system to be read.

Background art

Conventionally, there is a known electromagnetic induction type ID tag standardized by the “ISOZlEC15693” standard or the like. Various types of antennas and antenna devices for supplying power to the ID tag and performing communication have been proposed. For example, as an antenna, there is an antenna device that generates two uniform antennas facing each other across a tag placement space and generates a uniform alternating magnetic field by driving in phase, and there are three sets of such antenna devices. A configuration has also been proposed in which the antenna devices are arranged so that the axes of the antenna devices are orthogonal to each other around the tag.

[0003] In addition, in the antenna drive system, the above-described three sets of antenna devices are turned on and off in turn for each axis in a three-azimuth drive system, which has two axes on a two-dimensional plane. A method of generating a rotating magnetic field on a two-dimensional plane using an antenna configuration has been proposed. For example, in the following patent document, tag coil excitation that generates a rotating magnetic field on a two-dimensional plane with a multi-axis crossed antenna configuration using a plurality of coil devices configured by facing a pair of exciting coils (antennas). An apparatus is disclosed. (However, the method of generating the rotating magnetic field is different from the present invention.)

Patent Document 1: Japanese Patent Laid-Open No. 10-200452

Disclosure of the invention

Problems to be solved by the invention A known ID tag operates by being supplied with electric power by an alternating magnetic field. However, when the ID tag antenna is tilted with respect to the magnetic flux, or when the ID tag's resonance frequency shifts due to multiple ID tags being stacked close to each other in the same direction, they are supplied to the ID tag. The power that is used is reduced, making it difficult to detect. Therefore, the AC magnetic field needs to have a certain level of strength. However, if the magnetic field is too strong, the circuit inside the ID tag will saturate and communication will not be possible. In addition, there is a legal restriction, and an electric field strength exceeding a predetermined value cannot be generated.

[0005] There are the following problems when trying to apply such ID tags to bookshelves in libraries and bookstores, and display shelves for DVDs and CDs. When an ID tag is attached to a book or DVD, the antenna surface of the tag is parallel to the surface of the book or DVD, and the position can be within an area within a predetermined range near the center of the book or DVD. However, bookshelves and display shelves are horizontally long, and there is a high possibility that many ID tags overlap, so even if loop antennas are placed at both ends of the shelves, the magnetic flux density decreases or resonates at the center of the shelves. There was a problem that the frequency was shifted and the power was not supplied sufficiently and the ID could not be read.

[0006] The present invention solves the above-described problems of the prior art and enables an antenna device, an antenna driving method, and an ID tag that can more reliably detect IDs to a plurality of ID tags near the center of an elongated! /! Space An object is to provide a reader.

Means for solving the problem

[0007] An antenna device of the present invention includes antenna means in which two loop antennas are arranged facing each other on both sides of a predetermined space so that the directional center axes coincide with each other, and an antenna that drives the antenna means with a carrier signal having a predetermined frequency. The main feature is that it comprises driving means and resonant antenna circuit means including a loop antenna that is disposed in the predetermined space and that constitutes a resonant circuit that resonates at the predetermined frequency.

[0008] Further, the antenna device of the present invention includes an antenna unit in which a plurality of loop antennas are arranged at predetermined first intervals inside a predetermined space of a rectangular parallelepiped so that the directional center axes thereof coincide with each other, Antenna driving means for simultaneously driving a plurality of loop antennas with a carrier signal having a predetermined frequency, and a predetermined second interval between the plurality of loop antennas inside the predetermined space, the predetermined frequency being arranged, And a resonant antenna circuit means including a loop antenna that constitutes a resonant circuit that resonates with frequency. Features. In the antenna device described above, the bottom surface and both side surfaces of the predetermined space

Another feature is that a magnetic plate is disposed on at least one of the back surfaces.

[0009] In addition, the antenna driving unit may further include an output power control unit that controls output power for driving the antenna, and the output unit that increases or decreases the output power stepwise. Another feature is that it has a control means that repeats the ID tag reading operation while controlling the power control means.

[0010] Further, the antenna device of the present invention includes a plurality of loop antenna means arranged for each of two opposing surfaces of the rectangular parallelepiped, and the two opposing surfaces across a central portion of the rectangular parallelepiped. The main feature is that it includes antenna driving means for driving at least a part of the plurality of loop antenna means at the same or different desired phases so that magnetic fluxes having parallel components are generated. In addition, the antenna device described above is characterized in that loop antenna means are provided on each of two opposing surfaces that are orthogonal to the two surfaces of the rectangular parallelepiped.

[0011] An ID tag reader of the present invention includes the antenna device described above, and further communicates with an ID tag that is activated by obtaining operating power from an AC magnetic field, and a communication unit that reads information stored in the ID tag. The main feature is that it includes the position estimation means for estimating the position of one or a plurality of antennas that have received an ID tag signal and the transmission power value at that time.

[0012] In the antenna driving method of the present invention, step 1 for setting the driving power of the antenna to the minimum, and a plurality of loop antennas arranged in a predetermined space are simultaneously supplied with a carrier signal with the power set in step 1. Step 2 to drive, communicate with the ID tag arranged in the predetermined space, read the information Step 3, determine whether the current drive power is greater than or equal to the preset maximum power, and the determination result is In the negative case, the main feature is to include step 4 in which the drive power is increased by one step and then returned to step 2.

The invention's effect

[0013] According to the antenna device of the present invention, the electromagnetic wave emitted from the facing antenna is amplified by the resonance of the resonant antenna, and is far from the antenna and near the center of the shelf, even if the ID tag has sufficient power. Since it can be supplied, there is an effect that HD information can be detected more reliably. In addition, since the response signal from the ID tag is also amplified by the resonant antenna, the reception accuracy of the weak response signal from the tag is improved. Therefore, ID tags that are densely packed in a wide reading space such as a bookshelf can be read collectively.

[0014] Further, according to the antenna device of the present invention, a plurality of loop antennas are provided for each of two opposing faces of the rectangular parallelepiped, and at least a part of the plurality of loop antennas is the same or different. By driving at a desired phase, a magnetic flux having a component parallel to the two opposing surfaces can be generated in the central portion of the rectangular parallelepiped. Therefore, for example, by arranging a plurality of antennas on the top and bottom of the horizontally long shelf, sufficient power can be supplied to the ID tag even near the center of the shelf that partitions the horizontally long space. There is an effect that ID tags that are densely packed in the reading space can be read collectively.

Brief Description of Drawings

FIG. 1 is a block diagram showing the configuration of the entire system including an ID tag reader of the present invention.

FIG. 2 is a block diagram showing a configuration of a resonant antenna circuit board 15 of the present invention.

FIG. 3 is a block diagram showing a hardware configuration of an embodiment of the ID tag reader 10 of the present invention.

FIG. 4 is a block diagram showing a configuration of an antenna drive circuit 41.

FIG. 5 is a block diagram showing details of a modulator 62, an output amplifier 64, and the like.

FIG. 6 is an explanatory diagram showing a method for specifying the ID tag detection position in the first embodiment.

FIG. 7 is a block diagram showing a configuration example of a known ID tag.

FIG. 8 is a flowchart showing the contents of RFID tag reading processing of the present invention.

FIG. 9 is a front view and a side view showing the configuration of the antenna of Example 2 of the present invention.

FIG. 10 is an explanatory diagram showing an antenna drive pattern and a generated magnetic field in Example 2.

FIG. 11 is a perspective view and a front view showing a configuration of a shelf unit in Embodiment 3.

FIG. 12 is a block diagram showing a configuration of an ID tag reader in Example 3.

FIG. 13 is a flowchart showing the contents of a book management process in the third embodiment.

FIG. 14 is a flowchart showing the contents of tag position search processing in the third embodiment. FIG. 15 is a block diagram showing the overall configuration of the library management system in Example 3. Explanation of symbols

[0016] 10 · “ID tag reader

11… Host device (PC)

12 ... Bookcase

13, 14 ... loop antenna

15 ... Resonant antenna

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments will be described with reference to the drawings.

Example 1

First, an ID tag read by the ID tag reading device of the present invention will be described.

FIG. 7 is a block diagram illustrating a configuration example of a known ID tag. The ID tag 50 includes a tag antenna 51 and an IC 52, and is also called an IC tag. The loop-shaped tag antenna 51 constitutes an LC circuit that resonates at the carrier frequency. Then, electric power is excited in the tag antenna 51 based on the change of the alternating magnetic flux penetrating the tag antenna 51. Therefore, the maximum power can be obtained when the loop plane of the tag antenna 51 is oriented in a direction perpendicular to the magnetic flux of the magnetic field, but no power can be obtained when they are parallel.

The power supply circuit 53 generates a DC power supply from the electric power excited by the tag antenna 51 and supplies it to each circuit. When the power is supplied from the power circuit 53, the control logic circuit 58 for control is reset by the power-on reset circuit and extracts a clock from the received signal based on the clock signal supplied from the clock extraction circuit 55. Perform the operation.

[0020] The data demodulating circuit 56 receives and demodulates the signal transmitted by the ID tag reader, and outputs it to the control and arithmetic logic circuit 58. For example, when a response instruction command is received, the control / arithmetic logic circuit 58 is pre-stored in the storage circuit 59 at a predetermined timing and receives unique ID (identification) information of 64 bits. Is encoded with Manchester and output to the data modulation circuit 57.

The data modulation circuit 57 transmits a signal by changing the load of the tag antenna 51 based on the transmission data output from the control * arithmetic logic circuit 58. This ID tag The configuration of the group is an example, and the antenna driving method of the present invention can be applied to an ID tag having any known configuration as long as it is an electromagnetic induction method.

Next, an example in which the present invention is applied to a bookshelf and the ID of an ID tag attached to a book is read will be described. FIG. 1 is a block diagram showing the configuration of the entire system including the ID tag reader of the present invention. Loop antennas 13 and 14 are arranged at both ends in the longitudinal direction of the horizontally long bookshelf 12 and are respectively connected to the ID tag reader 10 according to the present invention. The ID tag reader 10 is further connected to a host device 11 such as a personal computer (PC).

[0023] A plurality (three in the figure) of resonant antenna circuit boards 15 are arranged in the internal space of the bookshelf 12 at a predetermined interval. Each resonant antenna circuit board 15 is fixed to the bookshelf so that the surface of the resonant antenna circuit board 15 is parallel to the surfaces of the loop antennas 13 and 14 at both ends. It is better to match the central axes!

FIG. 2 is a block diagram showing a configuration of the resonant antenna circuit board 15 of the present invention. The resonant antenna circuit board 15 is a thin board provided with a loop antenna coil 30 and a capacitor 31 made of copper wire or copper plate. The inner space 32 of the loop antenna coil 30 may be hollow as much as possible.

The loop antenna coil 30 and the capacitor 31 constitute a resonance circuit. When dense ID tags are present near the resonant antenna circuit board 15, the resonant frequency of the resonant circuit is lowered.Therefore, the resonant frequency of the resonant circuit is calculated from the carrier frequency (for example, 13.56MHz). It is better to set it slightly higher.

As a result of experiments, the inventor has arranged a resonant antenna circuit board 15 as shown in the shelf as shown in FIG. 1 so that a strong ID tag that cannot be detected without the resonant antenna circuit board 15 is obtained. I discovered that I could detect it. The reason for this is that by arranging the resonant antenna circuit board 15, the magnetic flux generated by the antennas 13 and 14 at both ends does not diffuse near the center of the shelf, and the magnetic flux density increases due to resonance of the resonant antenna. This is presumed to be due to this.

FIG. 3 is a block diagram showing a hardware configuration of the embodiment of the ID tag reader 10 according to the present invention. The ID tag reader 10 is roughly divided into an antenna device 40 and a control block 20. Power is supplied to each from a power supply unit (not shown).

The antenna device 40 includes an antenna drive circuit 41 corresponding to each of the plurality of loop antennas 13 and 14. The oscillator 42 generates, for example, a 13.56 MHz carrier signal (digital signal: rectangular wave, actually a clock signal that is an integral multiple of the carrier frequency) based on the above standard.

[0029] The antenna drive circuit 41, which will be described in detail later, also generates a carrier signal having a plurality of phases as the carrier signal power supplied from the oscillator 12, and based on the control of the control block 20, each antenna 13, 14 is driven with a carrier signal of the desired phase and power.

[0030] The antennas 13 and 14 are loop antennas that generate a uniform magnetic field in the space by being placed in a face-to-face relationship with the central axes of the orientations facing each other across the bookshelf 12 that is the tag placement space. . Each antenna 13, 14 is, for example, a copper plate or copper pipe wound in a ring shape.

[0031] The control block 20 includes a CPU 21, ROM 22, RAM 23, a data interface (IZF) circuit 24 for inputting / outputting transmission / reception data to / from the ID tag, a control interface (IZF) circuit 25 for controlling the antenna device 40, and a host device. 11 is equipped with an external interface (IZF) circuit 26 for communication with 11 and a nose for connecting internal circuits. The CPU 21 executes processing to be described later based on the control program stored in the ROM 22.

FIG. 4 is a block diagram showing a configuration of the antenna drive circuit 41. As shown in FIG. The antenna drive circuit 41 includes a phase converter 60, a phase switch 61, a modulator 62, a DZA converter 63, an output amplifier 64, a reception amplifier 65, and a demodulator 66. Phase change 60 is input from oscillator 42, for example 13. Based on a clock signal that is an integral multiple of a 56 MHz carrier signal, for example, a multiphase carrier signal (digital signal: rectangular wave) with a phase of 0 degrees, 180 degrees, etc. Output.

[0033] The internal structure of the phase change 60 is such that, for example, a carrier signal is input to a serial input of a shift register that is shifted by a clock signal that is an integral multiple of the carrier, and an output of a predetermined stage of the shift register is taken out as an output. Alternatively, the waveform information of each phase may be read from the ROM card according to the value of the address counter that is advanced by the clock signal.

[0034] The phase switch 61 also has a gate group force, and according to the phase control information from the control block 20, A carrier signal to be supplied to the antenna 13 (14) is selected from a plurality of types of carrier signals output from the phase change 60. In the first embodiment, the antennas 13 and 14 may be driven in the same phase, and therefore the phase converter 60 and the phase switch 61 may be omitted.

Based on the modulation data from the control block 20, the modulator 62 amplitude-modulates the carrier signal with a modulation factor of 10% to 100%. The DZA converter 63 converts the modulated carrier signal into an analog signal, and the output amplifier 64 amplifies the signal output from the DZA converter 63 to a desired power and drives the antenna 13 (14). .

[0036] Connection lines of the antennas 13 and 14 are also connected to reception amplifiers 65 corresponding to the antennas 13 and 14, respectively. The demodulator 66 receives, demodulates, and detects a collision from the ID tag, and outputs received data or a collision detection signal.

FIG. 5 is a block diagram showing details of the modulator 62, the output amplifier 64, and the like. The modulator 62 calculates the logical product of the digital carrier signal input by the AND gate 73 and the digital modulation data output from the control block 20, and outputs a 4-bit carrier signal. The DZA converter 63 performs DZA conversion on this 4-bit carrier signal, and outputs a rectangular wave carrier signal having a desired amplitude. BPF70 is a bandpass filter that allows only the fundamental frequency of the carrier to pass. By passing BPF70, a sinusoidal carrier signal can be obtained.

The output amplifier 64 includes a phase adjuster 71 and a power amplifier 72. The phase adjuster 7 1 is a force for accurately aligning the phases of a pair of antennas facing each other, and is not an essential circuit for carrying out the present invention. The power amplifier 72 drives the antenna 13 with desired power based on the output control signal from the control block 20.

Next, a reading operation in the ID tag reading device will be described. FIG. 8 is a flowchart showing the contents of the ID tag reading process of the present invention. This process is executed by the CPU 21 periodically, for example. In S10, the phase switch 61 is controlled so that a carrier signal having a desired phase is generated, and the power amplifier 72 is controlled so that the drive power is minimized. In the first embodiment, the two antennas 13 and 14 are driven in the same phase.

[0040] In S11, a frame for reading an ID from an ID tag based on a known protocol. Send a command. The command is encoded and input to modulator 62 via data IZF 24, and the carrier is modulated. For example, when each ID tag receives a response instruction command, it transmits information at a predetermined timing.

[0041] In S12, it is determined whether or not there is a response from the ID tag 50. If the determination result is negative, the process proceeds to S16. If the determination result is affirmative, the process proceeds to S13. In S13, it is determined whether or not there are multiple ID tag force response collisions. If the determination result is negative, the process proceeds to S15, but if the determination is affirmative, the process proceeds to S14. .

[0042] Although the ID tag transmits unique information as a response, since the Manchester code is used, when multiple ID tag powers also respond, the logical values 0 and 1 in the data overlap. If a code other than 0 or 1 is received in this case, the demodulator 66 can detect a collision.

[0043] In S14, based on the bit position where the collision was detected, a command for limiting the ID tag to respond to, for example, a command for instructing to respond only to the ID tag whose logical value of the collision bit position is 1 is transmitted. Return to S11. In S15, the received HD information is saved, a command for stopping the response is sent to the corresponding ID tag, and the process returns to S11.

[0044] In S16, it is determined whether or not the antenna driving power has reached a predetermined maximum value. If the determination result is negative, the process proceeds to S17. If the determination result is negative, the process proceeds to S18. . In S17, the power amplifier 72 is controlled so that the antenna driving power is increased by one step, and the process proceeds to S11.

[0045] In S19, data that is duplicated in all detected HD information powers is excluded. In S20, HD information is output to the host device. All ID information is read by the above process.

[0046] As described above, by initially reading ID with low power, stopping the response of the read ID tag, and gradually increasing the power, the ID tag near the antenna becomes high power. Therefore, the problem that communication is impossible is solved. Note that reading may be started at maximum power first, and the power may be gradually reduced.

FIG. 6 is an explanatory diagram showing a method for specifying the ID tag detection position in the first embodiment. Fig 6

(c) shows the case where the material constituting the shelf is neither a magnetic material nor a conductor (indicated by the dotted line in the figure) Example). The force that two antennas 84 and two resonant antenna circuit boards 81 are arranged on the shelf. Each antenna 84 is also used by the left and right shelves. In this case, the ID tag in the vicinity of the antenna 84 may be detected even if it is in the vertical, horizontal, or offset direction. Therefore, it is only known that the position of the ID tag is in the vicinity of the detected antenna.

[0048] Fig. 6 (b) shows the case where the horizontally arranged shelf board is made of a magnetic material such as an iron plate and an electrical conductor among the materials constituting the shelf (shown by a solid line! /, In this case, the ID tag in the vicinity of the antenna 84 may be detected only in the left or right direction. Therefore, it turns out that the position of the ID tag is in the vicinity of the detected antenna on the same height shelf as the detected antenna.

[0049] Fig. 6 (a) shows a case where, among the materials constituting the shelf, the shelf plate arranged horizontally and the support column arranged vertically are made of a magnetic material such as an iron plate and a conductor (solid line in the figure). In this case, only the ID tag in the same shelf as the antenna 84 may be detected. Therefore, the ID tag is found to be in the same shelf as the detected antenna. However, in this case, it is necessary to provide two antennas 80 for each shelf. Example 2

[0050] In the first embodiment, an example in which the resonant antenna circuit board 15 is arranged in the reading area has been described. However, in order to arrange the resonant antenna circuit board 15, the shelf or at least the front surface of the shelf is partitioned. There are challenges. The second embodiment solves this problem. Nothing is arranged inside the shelf, and a plurality of antenna devices arranged on the wall surface of the shelf are simultaneously driven in a desired phase to achieve the desired inside of the shelf. The magnetic field is generated.

FIG. 9 is a front view and a side view showing the configuration of the antenna according to the second embodiment of the present invention. Figure 9 (a) is a top view, (b) is a front view, and (c) is a side view. In Example 2, in addition to the antennas 90 and 91 corresponding to the antennas 13 and 14 of Example 1 arranged at both ends in the longitudinal direction of the shelf, four antennas 92 to 95 are provided on the upper surface of the shelf and four are provided on the lower surface. Antennas 96-99 and four antennas 100-103 on the back.

[0052] The upper and lower four-threaded antennas 92 and 96, 93 and 97, 94 and 98, and 95 and 99 face each other! In addition, you may arrange | position an antenna along the edge of the front of a shelf. Also on the back The antennas 100 to 103 can be omitted. Further, the antennas 92, 95, 96, and 99 may be omitted, and the antenna may be disposed only in the center portion. The antenna driving circuit may be provided with the same antenna driving circuit 41 as that of the first embodiment corresponding to the antenna.

FIG. 10 is an explanatory diagram showing an antenna drive pattern and a generated magnetic field in the second embodiment. In addition, this figure is the figure which looked at the shelf from the front, and the antennas 100 to 103 on the back are omitted. In the shelf of Example 1, the magnetic flux density is the weakest, and the location is the central portion P of the shelf. Therefore, as shown in FIG. 10 (a), for example, the antenna 93 on the upper surface is driven at a phase of 0 degree with respect to the reference phase as indicated by the solid arrow, and the antenna 98 on the lower surface is opposed to this. Again, it is driven with the same phase of 0 degree with respect to the reference phase.

Then, at point P, a magnetic field in an oblique direction as indicated by a dotted arrow is generated. Since this magnetic field also has a component in the longitudinal (left and right) direction, power can be supplied to the ID tag. At this time, by driving the antennas 90 and 91 at both ends in the same phase (0 degree), the magnetic field at the point P is further increased.

[0055] Fig. 10 (b) shows the magnetic field generated when the antennas 93 and 98 are driven at a phase of 0 degrees and the antennas 94 and 97 are driven at a phase of 180 degrees. The magnetic field is generated. At this time, the magnetic field at point P is further strengthened by driving the antennas 90 and 91 at both ends with the same phase of 0 degrees. In order to generate a horizontal magnetic field in the central portion of the shelf, it is preferable to arrange the upper and lower antennas symmetrically with respect to the center of the shelf. Therefore, it is preferable that the number of antennas arranged on the upper surface and the lower surface is an even number (4 in the embodiment).

[0056] Figure 10 (c) drives the antennas 90 and 91 at both ends in the same phase, and the antennas 92 to 95 are all driven at 0 phase and the antennas 96 to 99 are all driven at 180 degrees, all driven with weak power. In this case, the magnetic flux generated by the antennas 90 and 91 at both ends can be prevented from spreading as in the first embodiment. In FIG. 10 (c), the antennas 94 and 95 may be driven at a phase of 180 degrees and the antennas 98 and 99 may be driven at a phase of 0 degrees.

[0057] In the second embodiment, since the vertical magnetic field can be easily generated by providing the antennas facing the top and bottom of the shelf, for example, a book placed horizontally on the bookshelf can be easily detected. It becomes possible to go out. Further, the configuration of the second embodiment and the resonant antenna circuit board 15 of the first embodiment may be combined.

Example 3

[0058] Embodiment 3 is an example of simultaneously reading a wider range by simultaneously driving three or more antennas. For example, a library in which books to be recognized are arranged on a bookshelf composed of a large number of shelves. It is a system applicable to a library, bookstore, CDZDVD shop, etc.

FIG. 11 is a perspective view and a front view showing the configuration of the shelf unit in the third embodiment. The shelf unit is, for example, a unit having a plurality of loop antennas that are made to have a size that can be stored in one shelf of a wooden bookshelf 410. The shelf unit includes a bottom plate 402 made of a magnetic material such as an iron plate, a back plate 403, and side plates 401 on both sides.

[0060] With these iron plates, the risk of reading the tag ID of another shelf unit when the antenna of this shelf unit is driven is greatly reduced. Also, if there is an iron plate, the transmission power increases even if the ID of the tag of another unit is read, so it is easy to determine which unit the tag is in. If the bottom, side, or back of a steel shelf or cabinet is made of a magnetic material such as a steel plate, there may be no iron plate parallel to that surface.

[0061] In the unit, four loop antennas 405 are arranged at equal intervals (L2), and two resonant antennas 406 are arranged on both sides thereof at intervals (L 1) narrower than the intervals of the loop antennas. The In the third embodiment, the loop antenna is not disposed at both ends, and the resonance antenna 406 is used, thereby reducing the possibility of reading the tag on the adjacent shelf and reducing the number of antennas. The number of loop antennas 405 can be increased or decreased as required. Further, a resonant antenna 406 may be added between the loop antennas 405.

[0062] Spacer 404 is also filled between the two resonant antennas 406 and the iron plates 401 at both ends so as to provide a foaming material equal force in order to leave a gap. If the resonance antenna 406 is brought too close to the iron plate 401, the effect of the resonance antenna is reduced. In order to prevent this, a gap by the spacer 404 is provided. FIG. 12 is a block diagram illustrating a configuration of the ID tag reader according to the third embodiment. In the third embodiment, the number of shelf units to be force-controlled, which explains an example in which four shelf units shown in FIG. 11 are controlled by one ID tag reader 200, is arbitrary. A plurality of coaxial cables 201 connected to each antenna of each shelf unit of the bookshelf 410 are connected to a switch 215 that also has a coaxial relay force in the ID tag reader 200.

The ID tag reading device 200 includes, for example, the same number (4) of antenna drive circuits 41 as the number of antennas in the shelf unit. Then, all the switches 215 are switched by the same control signal, and the four antennas in the shelf unit are simultaneously connected to the antenna driving device 41 and driven in the same phase, and each reads the ID tag. The power may be the same, but the power may be changed for each antenna. The configurations of the antenna drive circuit 41 and the oscillator 42 are the same as those in the first embodiment.

[0065] The configuration of the control block 20 is the same as that in the first embodiment. In order to perform the processing described later, the HD information read from the DB server 300 connected via the LAN 303 (only the difference) At the same time, information on the shelf number or antenna number that detected the ID and information on the transmission power value at that time are also transmitted.

FIG. 15 is a block diagram showing a configuration of the entire library management system in the third embodiment. A plurality of ID tag reading devices 200 each controlling a predetermined number (for example, four) of shelf units 400 are connected to the LAN 303. The controller 304 corresponds to the control block 20, the antenna drive circuit 41, and the oscillator 42 in FIG.

[0067] The LAN 303 is also connected to a DB server 300 having a DB 301 and a PC terminal 302 that requests processing to the DB server 300 based on a user operation. The ID tag reader 200 and the DB sano 300 are respectively connected to the LAN 303. Processing described later is performed.

FIG. 13 is a flowchart showing the contents of the book management process in the third embodiment. This process is always executed in the DB server 300. In S30, it is determined whether or not the ID update data is received from any ID tag reader 200 via LAN. If the determination result is negative, the process proceeds to S32. Migrate to

[0069] In S31, the ID location information in DB 301 is updated based on the received ID update information. That is, for the newly detected HD information, the latest time detected in the HD information Add data such as time, shelf number, transmission power, etc., and add the time, shelf number, etc. that were not detected for the HD information that was detected last time but was not detected this time.

[0070] When a plurality of ID tag readers 200 scan the book shelf in a shared manner, the tags near the boundary are respectively read by the two ID tag readers 200! And sent to the DB server 300. May be sent. Therefore, when updating the ID position information, it is checked whether it is detected in other shelf units. If it is detected in duplicate, the data of the transmitted power is deleted and the data is transmitted. Only the data with the smaller power is left.

[0071] In S32, it is determined whether or not there is a search request from any of the client PC terminals 302. If the determination result is negative, the process proceeds to S36, but if the determination is affirmative, the process proceeds to S33. To do. In S33, the library DB is searched based on the search key such as the book name input by the user, and the pre-registered information is acquired.

In S34, the position information corresponding to the ID acquired from the DB 301, that is, the shelf number is acquired. In S35, the search result is output to the requesting PC terminal. In the PC terminal 302, for example, a diagram of the entire bookcase is displayed on the screen of the display device, and the estimated tag position is displayed in a square area whose color is changed.

[0073] In S36, it is determined whether or not there is a request for statistical information from any of the client PC terminals 302. If the determination result is negative, the process proceeds to S30. If the determination is positive, the process proceeds to S37. Transition. In S37, for example, the recorded data in the DB is statistically processed, and the inventory list, misplaced list, list being retrieved, book availability (calculating force for how many times or how many hours the book is taken within a given period, etc. In S38, the statistical processing result is output to the requesting PC terminal.

FIG. 14 is a flowchart showing the contents of the tag position search process in the third embodiment.

This process is always executed in each ID tag reader 200. In S41, it is determined whether or not the previous scanning force has passed for a certain time (for example, 0 to several tens of seconds). If the determination result is negative, the process returns to S41, but if the determination is positive, the process proceeds to S42. To do.

[0075] In S42, it is determined whether or not the force of completing the entire shelf scan is completed. If the determination result is negative, the process proceeds to S43. If the determination is negative, the process proceeds to S49. In S43, the switch 215 is controlled to switch to an unread shelf. In S44, all antennas Set the transmission power to the minimum level. In S45, tag ID reading processing is executed. That is, the processing from S11 to S15 in FIG.

In S46, after reading, the transmission power, shelf number (and antenna number), time, etc. are recorded. In S47, it is determined whether or not the transmission power is a predetermined maximum power. If the determination result is negative, the process proceeds to S48. If the determination is negative, the process proceeds to S42. In S48, increase the transmission power of all antennas by one step and move to S45.

[0077] In S49, data other than those having the lowest transmission power are deleted from data with duplicate IDs. This process and the above-described duplication deletion process between the plurality of ID tag readers 200 are to estimate that the tag exists on the shelf where the transmission power can be detected at the lowest, and to estimate the position of the ID tag. Corresponds to means.

In S50, all the data for which the ID is detected are stored. In S51, the difference from the ID detection data at the time of the previous scan, that is, the data not detected last time but detected this time, or the power detected previously but not detected this time is extracted. In S52, the difference data is transmitted to the DB server 300.

With the configuration and processing as described above, a large number of books in a library or the like can be managed with high accuracy in almost real time.

Although the embodiments have been described above, the present invention can be modified as follows. In the first embodiment, the example in which the resonant antenna circuit board 15 is arranged in parallel with the antenna is disclosed. However, a configuration in which the resonant antenna circuit board 15 is arranged on the bottom surface is also conceivable. This makes it easier to read ID tags that are difficult to read perpendicular to the transmitting and receiving antennas.

In Example 2, the received signal strength may be detected for each antenna, and the detected ID tag position may be estimated together with the transmission power pattern at that time. In the second embodiment, an example of generating a magnetic field having a rectangular parallelepiped longitudinal component has been disclosed. For example, four antennas 93, 94, 97, and 98 arranged on two opposite surfaces shown in FIG. 10 are used. In addition, by driving the antennas 93 and 98 at a phase of 0 degrees and the antennas 94 and 97 at a phase of 90 degrees, a rotating magnetic field can be generated in a plane including the axis of each antenna. For example, belt control When reading an ID tag on a bear, it is possible to read the ID by placing a plurality of antennas on both sides of the conveyor, for example, without installing antennas on a plane perpendicular to the moving direction of the conveyor.

[0081] In Example 2, in order to generate a longitudinal magnetic field between antennas 93 and 97, non-adjacent antennas 92 and 98 are driven at phase 0 degrees and antennas 94 and 96 are driven at phase 180 degrees. You just have to do it.

In the third embodiment, for example, when a search for a book is requested, a re-reading check may be performed to check whether the corresponding tag is in the shelf recorded in the DB. It is also possible to record data up to the antenna number and display whether it is estimated to be in that part of the shelf.

Claims

The scope of the claims

[1] An antenna means in which two loop antennas are arranged facing each other on both sides of a predetermined space with the directional central axes coincided with each other,

An antenna driving means for driving the antenna means with a carrier signal having a predetermined frequency; and a resonant antenna circuit means having a loop antenna disposed in the predetermined space and constituting a resonant circuit that resonates at the predetermined frequency;

An antenna device comprising:

[2] An antenna means in which a plurality of loop antennas are arranged at predetermined first intervals within a predetermined space of a rectangular parallelepiped so that the directivity central axes coincide with each other;

Antenna driving means for simultaneously driving a plurality of loop antennas of the antenna means with carrier signals of a predetermined frequency;

Resonant antenna circuit means comprising a loop antenna that is disposed inside the predetermined space at both ends of the plurality of loop antennas with a predetermined second interval and that resonates at the predetermined frequency.

An antenna device comprising:

[3] The antenna device according to [2], wherein a magnetic plate is disposed on at least one of a bottom surface, both side surfaces, and a back surface of the predetermined space.

[4] The antenna driving means includes:

Output power control means for controlling the output power for driving the antenna;

Control means for controlling the output power control means so that the output power increases or decreases stepwise; and control means for repeating the ID tag reading operation;

The antenna device according to claim 1, further comprising:

[5] A plurality of loop antenna means arranged on each of two opposing faces of the rectangular parallelepiped,

Antenna driving means for driving at least a part of the plurality of loop antenna means at the same or different desired phases so that a magnetic flux having a component parallel to the two opposing faces is generated in the central portion of the rectangular parallelepiped. When An antenna device comprising:

[6] The antenna device according to [5], wherein loop antenna means are provided on each of two opposing surfaces orthogonal to and opposite to the two surfaces of the rectangular parallelepiped.

[7] The antenna device according to any one of claims 1 to 6,

Furthermore, the communication means for communicating with the ID tag that is activated by obtaining the operating power from the AC magnetic field force, and reading the information stored in the ID tag;

Position estimation means for estimating the position of the ID tag based on the position of the antenna or antennas that received the signal from the ID tag and the transmission power value at that time

An ID tag reading device comprising:

[8] Set the antenna drive power to the lowest step 1,

Step 2, driving a plurality of loop antennas arranged in a predetermined space simultaneously with a carrier signal at the power set in Step 1,

Communicating with the ID tag arranged in the predetermined space and reading the information Step 3, determining whether the current driving power is greater than or equal to the preset maximum power, and if the determination result is negative, the driving power Increase one step! Step 4 to return to Step 2

An antenna driving method comprising: