JP2011166729A - Antenna for non-contact information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna for a non-contact information recording medium, wherein communication with an IC card can be performed regardless of the shape of a reader/writer body. <P>SOLUTION: A reader/writer 51 includes: a receiving-side antenna 1 electromagnetically coupled with an electromagnetic wave 2 radiated from a loop antenna 3 of a reader/writer body 4; a communication cable 6 for transferring a current which is made electro-motive by the electromagnetic wave 2 received by the receiving-side antenna 1; an output-side antenna 10 for generating an electromagnetic wave with the current transferred by the communication cable 6; and impedance matching devices 5, 7 for impedance matching with the communication cable 6. The reader/writer 51 is then configured to make a loop diameter of the receiving-side antenna 1 smaller than a loop diameter of the loop antenna 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna for a non-contact information recording medium, and more particularly to a signal transmission technique that enables communication between a reader / writer disposed at a separated position and an RFID such as an IC tag.

In recent years, a system for reading and managing information recorded on an IC card held by an entrance / exit by a reader / writer provided at a ticket gate of a station, an entrance / exit gate to a building, etc. has become widespread. When constructing these systems, it is necessary to install a reader / writer. Therefore, there are reader / writers as custom-made products whose sizes and configurations are determined in accordance with a specific installation environment, but many reader / writers are manufactured for general use. Therefore, when constructing a system using these general-purpose reader / writers, it is necessary to secure an installation space according to the size and shape of the reader / writer used and to design a measurement jig to check the performance. Met. In addition, when the IC card side is fixed and there is a demand to install a reader / writer on the movable side, there is a problem that the movable part is loaded due to the shape and weight of the reader / writer, making installation difficult.
As one method for solving the problems with the reader / writer installation specifications as described above, Patent Document 1 discloses a primary coil that is electromagnetically coupled to a transmission / reception antenna of a reader / writer, a secondary coil that is electromagnetically coupled to an antenna of an IC chip, There is disclosed an antenna adapter device for a reader / writer provided with a capacitor for series resonance and an adapter with a concave portion for guiding to appropriately position a key.

JP 2004-94532 A

However, the conventional technique disclosed in Patent Document 1 has a problem that the arrangement of all the constituent elements is fixed and the versatility of the technique is poor.
The present invention has been made in view of such a problem, and connects a power receiving side antenna that is electromagnetically coupled to a reader / writer main body to an output side antenna by a communication cable that can be set to a predetermined length. An object of the present invention is to provide an antenna for a non-contact information recording medium that can communicate with an IC card regardless of the shape.

In order to solve this problem, the present invention provides a power receiving side antenna that is electromagnetically coupled to a reader / writer body including a loop antenna that emits an electromagnetic wave for reading and writing recorded information on a non-contact information recording medium, A communication cable for transmitting a current generated by an electromagnetic wave received by the power receiving side antenna; and an output side antenna for generating an electromagnetic wave by the current transmitted by the communication cable, wherein the loop diameter of the power receiving side antenna is It is characterized by being configured to be smaller than the loop diameter of the loop antenna.
In order to perform the most efficient electromagnetic coupling with the electromagnetic wave radiated from the loop antenna, it is preferable to couple the coils having the same diameter as the loop antenna so as to overlap each other. If the loop diameter of the power receiving antenna is smaller than the loop diameter of the loop antenna, the power receiving antenna can be arranged around the loop of the loop antenna having the highest magnetic flux density. However, the shape of the reader / writer main body manufactured by each company (that is, the diameter of the loop antenna) varies, and the size of the loop diameter cannot be uniquely determined. Therefore, as one guideline, when it is determined that the loop diameter of the IC card is the smallest in the current technology, the loop diameter of the power receiving antenna can be used as the loop diameter of the IC card. Accordingly, by making the loop diameter of the power receiving side antenna smaller than the loop diameter of the loop antenna, the power receiving side antenna can be arranged at a position where the magnetic flux density of the loop antenna is highest.

According to a second aspect of the present invention, the power receiving antenna and the output antenna are connected to each other by the communication cable via an impedance matching unit.
Since the antenna is composed of a coil, it is important to configure an LC resonance circuit in order to efficiently transmit and receive signals. In order to efficiently transmit the magnetic field current obtained from the power receiving antenna to the output antenna, it is important to match the impedance with the communication cable. Therefore, in the present invention, impedance matching units are provided at both ends of the communication cable, and each is connected to the power receiving antenna and the output antenna. Thereby, a signal can be efficiently transmitted between the antennas.
According to a third aspect of the present invention, the power receiving antenna includes a power receiving level detector that monitors a level received by the power receiving antenna.
Since the power receiving antenna is configured to be smaller than the diameter of the loop antenna, it can be disposed around the loop antenna having the highest magnetic flux density. However, the loop antenna is often housed in the case and cannot be seen from the outside. Therefore, the present invention includes a power receiving level detector that monitors the level received by the power receiving antenna, and detects the level of the magnetic flux density visually or by sound. Thereby, the position with the strongest electromagnetic coupling can be easily confirmed.

According to a fourth aspect of the present invention, the output-side antenna and / or the power-receiving-side antenna are arranged in close contact with the loop coil formed by winding a conducting wire, and a magnetic path of electromagnetic waves generated from the loop coil. A magnetic member to be formed and a metal member disposed in close contact with the magnetic member are provided.
When the output antenna is disposed, the surrounding environment is various. That is, if the surrounding magnetic noise is picked up, the S / N deteriorates that much, and there is a possibility that the signal is erroneously detected. Further, if there is a metal member in the vicinity, impedance matching is lost, and signal transmission efficiency is reduced. Therefore, in the present invention, a magnetic member and a metal member are laminated in advance on the output side antenna and / or the power receiving side antenna. Thereby, external magnetic noise can be removed, and resistance to surrounding metal members can be enhanced.
According to a fifth aspect of the present invention, the power receiving antenna is disposed at a place where the power receiving level monitored by the power receiving level detector is maximized.
The magnetic flux density is highest around the loop of the loop antenna. Therefore, when the loop diameter of the power reception antenna is smaller than the loop diameter of the loop antenna, the place where the power reception level monitored by the power reception level detector is the largest can be regarded as the loop periphery of the loop antenna. Thereby, the optimal position of the power receiving antenna can be easily determined.
Claim 6 is configured such that the loop diameter of the output antenna is larger than the loop diameter of the loop antenna, and the loop diameter of the loop antenna is larger than the loop diameter of the power receiving antenna. It is characterized by.

According to the present invention, since the loop diameter of the power reception side antenna is made smaller than the loop diameter of the loop antenna, the power reception side antenna can be arranged at a position where the magnetic flux density of the loop antenna is highest.
Moreover, since the impedance matching device is provided at both ends of the communication cable and each is connected to the power receiving antenna and the output antenna, a signal can be efficiently transmitted between the antennas.
Moreover, since the power receiving level detector for monitoring the level received by the power receiving antenna is provided, the position with the strongest electromagnetic coupling can be easily confirmed.
In addition, since the magnetic member and the metal member are laminated on the output side antenna and / or the power receiving side antenna, external magnetic noise can be removed and resistance to the surrounding metal members can be enhanced.
Further, since the place where the power reception level monitored by the power reception level detector is the highest can be regarded as the loop periphery of the loop antenna, the optimum position of the power reception antenna can be easily determined.

It is a block diagram which shows the structure of a general reader / writer main body. It is a figure explaining the use condition of the reader / writer which concerns on embodiment of this invention. It is a figure which shows the positional relationship of a loop antenna and a receiving side antenna. It is a figure which shows the circuit example of the power receiving level detector of this invention. It is a timing chart which shows the signal waveform of each part of a power receiving level detector. It is a figure explaining the Example which used the reader / writer of this invention for the ticket gate. It is sectional drawing which shows the structure of the output side antenna of this invention. It is a figure which shows the relationship of the loop diameter size of a loop antenna, a receiving side antenna, and an output side antenna. It is a figure explaining the Example which used the electromagnetic coupling type transmission / reception antenna of this invention for the display shelf. It is a figure explaining the Example which used the electromagnetic coupling type transmission / reception antenna of this invention for the taxi.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  FIG. 1 is a block diagram showing a configuration of a general reader / writer main body. The reader / writer main body 4 is controlled by a PC 50 that exchanges data with the reader / writer main body 4 to control the entire system. The reader / writer body 4 reads the transmission / reception device 41 that controls the data communication protocol with the external PC 50, the control device 42 that controls the operation of the entire reader / writer body 4, and the firmware that records the procedure for operating the control device 42. A memory device 43 for storing the received data, a modulator 44 for modulating the data from the control device 42 on a carrier wave, an input device 45 for inputting an operation command, and a display for displaying information controlled by the control device 42 A power amplifier 47 that amplifies a power supply signal that is an AC signal from the control device 42 and a write command from the modulator 44; and a detection that converts the carrier wave received from the loop antenna 3 into binary data. Loop antenna for exchanging power carrier waves and data between the demodulator 48 and an IC card (RF tag) (not shown). It is configured to include a 3 and.

FIG. 2 is a diagram for explaining a usage state of the reader / writer according to the embodiment of the present invention. The reader / writer 51 includes a power receiving side antenna 1 electromagnetically coupled to the electromagnetic wave 2 radiated from the loop antenna 3 of the reader / writer main body 4, and a communication cable 6 for transmitting a current generated by the electromagnetic wave 2 received by the power receiving side antenna 1. And an output-side antenna 10 that generates an electromagnetic wave by the current transmitted through the communication cable 6 and impedance matching units 5 and 7 that match impedances of the communication cable 6. Then, the loop diameter of the power receiving antenna 1 is configured to be smaller than the loop diameter of the loop antenna 3.
That is, the electromagnetic wave 2 emitted from the reader / writer main body 4 is emitted in a loop as indicated by an arrow. By arranging the power receiving antenna 1 so as to cross the electromagnetic wave 2, an electromotive force is generated in the power receiving antenna 1. The current is transmitted through the communication cable 6 through the impedance matching unit 5 and generates an electromagnetic wave 9 in the output side antenna 10 through the impedance matching unit 7. Since the electromagnetic wave 9 is radiated in a loop as indicated by an arrow, a non-contact IC card (hereinafter simply referred to as an IC card) 8 loop antenna is disposed so as to cross the electromagnetic wave 9, whereby the IC card 8 Communication with the reader / writer 4 is established.
In addition, since the antenna is composed of a coil, it is important to configure an LC resonance circuit in order to efficiently transmit a signal. Further, in order to efficiently transmit the magnetic field current obtained from the power receiving antenna 1 to the output antenna 10, it is important that the impedance with the communication cable 6 is matched. Therefore, in the present embodiment, the impedance matching units 5 and 7 are provided at both ends of the communication cable 6, and each is connected to the power receiving side antenna 1 and the output side antenna 10. Thereby, a signal can be efficiently transmitted between the antennas.

FIG. 3 is a diagram illustrating a positional relationship between the loop antenna and the power receiving antenna. When the loop diameter of the power receiving side antenna 1 is smaller than the loop diameter of the loop antenna 3, the magnetic flux density is highest around the loop A of the loop antenna 3 as shown in the figure. Therefore, the power receiving side antenna 1 is arranged around the loop A of the loop antenna 3 having the highest magnetic flux density.
That is, for the most efficient electromagnetic coupling with the electromagnetic wave 2 radiated from the loop antenna 3, it is preferable to couple the coils having the same diameter as the loop antenna 3 so as to overlap each other. Further, when the loop diameter of the power receiving side antenna 1 is smaller than the loop diameter of the loop antenna 3, the power receiving side antenna 1 can be arranged around the loop A of the loop antenna 3 having the highest magnetic flux density. However, the shape of the reader / writer main body manufactured by each company (that is, the diameter of the loop antenna) varies, and the size of the loop diameter cannot be uniquely determined. Therefore, as a guideline, it can be determined that the loop diameter of the IC card 8 is the smallest in the current technology, and can be set as the loop diameter of the power receiving antenna 1. Thereby, by making the loop diameter of the power receiving side antenna 1 smaller than the loop diameter of the loop antenna 3, the power receiving side antenna 1 can be arranged at a position where the magnetic flux density of the loop antenna 3 is the highest.

FIG. 4 is a diagram showing a circuit example of the power reception level detector of the present invention. This power reception level detector 51 is a method for digitally displaying a high level (appropriate level) and a low level (inappropriate level) by LEDs. FIG. 5 is a timing chart showing signal waveforms of respective parts of the power reception level detector.
This will be described with reference to FIGS. The level of the input signal generated from the antenna unit 15 varies depending on the position of the power receiving antenna 1 as shown in FIG. The signal is rectified to a direct current by a rectifier circuit including diodes 17 and 18 via a capacitor C16. Then, the pulsating flow component is removed by the capacitor C19 and supplied to the circuit as the diode output of FIG. This diode output is supplied to the Zener diode ZD20 and to the base of the transistor Tr29 via the resistors R26, R27, and R28. When the diode output is lower than the threshold level Vt of the Zener diode ZD20, the Tr 29 is turned on to light the LED 31 (L level).

When the position of the power receiving antenna 1 is moved and the diode output becomes higher than Vt, the voltage is supplied to the base of Tr23 via ZD20, R21, and R22. As a result, Tr23 is turned on and the LED 30 (H level) is turned on. At that time, since the diode D25 is connected to the collector of the TR23, the base voltage of the Tr29 becomes substantially the ground level, the Tr29 is turned off, and the LED 31 (L level) is turned off. Thereafter, the LED 30 and the LED 31 are turned ON and OFF in a complementary manner in accordance with the diode output. After the LED 30 is turned on and the optimum location of the power receiving antenna 1 is determined, if the power receiving level detector 51 is operated, the original signal level is lowered accordingly, so illustration is omitted. However, a switch for switching to the communication cable 6 side may be provided. Moreover, it may replace with LED30 and LED31, and the method of alert | reporting with a sound with a buzzer etc. may be sufficient.
That is, since the power receiving side antenna 1 is configured to be smaller than the diameter of the loop antenna 3, it can be disposed around the loop antenna 3 having the highest magnetic flux density. However, the loop antenna 3 is often housed in the case and cannot be seen from the outside. Therefore, in the present embodiment, a power receiving level detector 51 that monitors the level received by the power receiving antenna 1 is provided, and the level of the magnetic flux density is detected visually or with sound. Thereby, the position with the strongest electromagnetic coupling can be easily confirmed.

FIG. 6 is a diagram for explaining an embodiment in which the non-contact communication cable of the present invention is used in a ticket gate. The same components will be described with the same reference numerals as in FIG. The ticket gate 33 has a small space in which the reader / writer main body 4 is arranged. For example, a case where the reader / writer main body 4 cannot be arranged will be described. In such a case, the output side antenna 10 is arranged at the place A where the IC card of the ticket gate 33 is close, and is extended with the communication cable 6 to be connected to the power receiving side antenna 1. Then, the selector switch 32 of the power receiving level detector 51 is connected to the detector side, the power receiving antenna 1 is moved over the loop antenna 3, and the position where the LED 30 is lit is searched. Since the LED 30 and the LED 31 are repeatedly turned ON and OFF depending on the reception level, the position where the LED 30 is stably lit is fixed as the optimum position of the power receiving antenna 1. In this state, the changeover switch 32 is turned OFF. Since the power receiving level detector 51 is not required after the power receiving antenna 1 is fixed, the power receiving level detector 51 is not necessary.
That is, the highest magnetic flux density is around the loop A of the loop antenna 3. Therefore, when the loop diameter of the power reception side antenna 1 is smaller than the loop diameter of the loop antenna 3, the place where the power reception level monitored by the power reception level detector 51 is the largest can be regarded as the loop periphery of the loop antenna 3. . Thereby, the optimal position of the power receiving side antenna 1 can be determined easily.

FIG. 7 is a cross-sectional view showing the configuration of the output side antenna and / or the power receiving side antenna of the present invention. The output side antenna 10 includes a loop coil 35 formed by winding a conducting wire, a magnetic member 36 that is disposed in close contact with the loop coil 35 and forms a magnetic path of an electromagnetic wave 38 generated from the loop coil 35, and a magnetic member. A metal member 37 disposed in close contact with the member 36.
When the output side antenna 10 is arranged, the surrounding environment is various. That is, if the surrounding magnetic noise is picked up, the S / N deteriorates that much, and there is a possibility that the signal is erroneously detected. Therefore, in this embodiment, the magnetic member 36 and the metal member 37 are laminated on the loop coil 35. Thereby, the external magnetic noise 39 can be removed and the magnetic field 38 can be efficiently radiated from the output side antenna 10.
Specifically, when a general-purpose reader / writer has a metal object around it, a magnetic path cannot be formed, and communication with an IC card or RF tag may not be performed correctly. In that case, it is necessary to install a reader / writer at a position away from the metal, or change to a reader / writer that can be installed on a metal surface. When the electromagnetic coupling type transmission / reception antenna 51 of the present invention is used, a general-purpose reader / writer is installed in a position not affected by metal in advance, and the output antenna 10 of the present invention is configured as shown in FIG. Install.
As described above, the present invention can realize providing a card touch unit in the vicinity of a metal object without modifying a general-purpose reader / writer that cannot be installed in a metal environment.

  FIG. 8 is a diagram illustrating the relationship of the loop diameter sizes of the loop antenna, the power receiving antenna, and the output antenna. As described above, assuming that the loop diameter of the loop antenna is B, the power receiving side antenna loop diameter is A, and the output side antenna loop diameter is C, according to the relationship of A <B, A is independent of the size of the loop diameter of B. Electric power can be received efficiently at the portion with the highest magnetic flux density. In addition, it is desirable that B <C and further A <B <C depending on the operation conditions. That is, since the electromagnetic wave radiated from the loop antenna depends on the loop diameter, the communication distance between the IC card and the RF tag can be extended by the relationship of B <C. Further, when a transmission loss occurs in the cable between A and C, the attenuation of the communication distance due to the loss can be compensated by the relationship of B <C.

FIG. 9 is a view for explaining an embodiment in which the electromagnetic coupling type transmitting / receiving antenna of the present invention is used for a display shelf. In FIG. 9, the output side antenna 10 is arranged on the upper surface or the lower surface of the glass plate 55 constituting the glass shelf 54, and the output side antenna 10 is electromagnetically coupled to the reader / writer 4 by the power receiving side antenna 1 through the communication cable 6. . Although not shown, RF tags are attached to the clothes 53 on the glass plate 55, and information on each clothes is recorded.
General-purpose reader / writers are sold for various purposes such as entry / exit rooms and goods management, but their design and shape do not always match the intended use. Therefore, it is difficult for the reader / writer maker to make changes because of the cost and the change period. For example, when a reader / writer is attached to the glass shelf 54 for displaying clothes used in the apparel industry or the like for managing the clothing 53, there are few general-purpose reader / writers that can be installed on the glass shelf 54.
Therefore, by using the electromagnetic coupling type transmission / reception antenna 51 of the present invention, the base of the output side antenna 10 is made transparent, and affixed to the upper surface or the lower surface of the glass plate 55. Correspondence is possible regardless of the shape. In addition, an existing product can be used as the reader / writer to which the power receiving antenna is attached. As described above, the present invention can serve as an adapter that converts the design of the antenna surface that communicates with the IC card or the RF tag without modifying a general-purpose reader / writer. Similarly, the following cases can be easily dealt with.
1) The design of the card touch part of the entrance / exit leader of buildings where various manufacturers enter can be shared.
2) The design of reader / writers installed at supermarkets and convenience store cash registers can be improved.

In general, a general-purpose reader / writer is exposed and installed due to its device configuration. For example, a reader / writer in a cash register of a convenience store is arranged on a cash register for each standard. As described above, the reader / writer is an expensive terminal including the control unit, but can be easily stolen or mischievous.
Therefore, by using the electromagnetic coupling type transmitting / receiving antenna 51 of the present invention, the reader / writer used conventionally is installed in a hidden place such as under the register, and the output side antenna 10 of the present invention is installed on the register. Thus, the exposed portion can be converted into an inexpensive configuration with only an antenna.
FIG. 10 is a diagram for explaining an embodiment in which the electromagnetic coupling type transmitting / receiving antenna of the present invention is used in a taxi. The taxi 56 installs the reader / writer 4 in the driver's seat 59 and outputs it from the power receiving side antenna 1 electromagnetically coupled to the loop antenna of the reader / writer 4 to the partition wall 58 that separates the driver's seat 59 and the passenger seat 57 via the communication cable 6. The side antenna 10 is installed. With this configuration, a passenger who settles a taxi fare with an IC card can complete the settlement by touching the IC card to the output side antenna 10, so that an expensive reader / writer is kept at hand while protecting the driver's safety. Can be arranged.
As described above, the present invention allows the reader / writer main body to be placed at a position hidden from the human eye or placed at hand without adding a hand to a general-purpose reader / writer. Writer can be protected.
Similarly, the following cases can be easily handled.
1) In the case of a house door locked by a reader / writer, the reader / writer is installed in the house and the output side antenna of the present invention is installed outside.
2) In the vending machine, the payment reader / writer is arranged inside the vending machine, and the output side antenna of the present invention is installed outside.

  1 power receiving side antenna, 2 electromagnetic wave, 3 loop antenna, 4 reader / writer main body, 5, 7 impedance matching unit, 6 communication cable, 8 non-contact IC card, 9 electromagnetic wave, 10 output side antenna, 35 loop coil, 36 magnetic member, 37 Metal member, 38 Electromagnetic wave, 39 External noise, 50 PC, 51 Electromagnetic coupling type transmitting / receiving antenna, 52 Power reception level detector, 54 Glass shelf, 55 Glass plate, 56 Taxi, 57 Passenger seat, 58 Bulkhead, 59 Driver's seat

Claims (6)

A reader / writer body equipped with a loop antenna that emits electromagnetic waves for reading and writing recorded information on a non-contact information recording medium;
A power receiving antenna that is electromagnetically coupled;
A communication cable for transmitting a current generated by electromagnetic waves received by the power receiving antenna;
An output-side antenna that generates an electromagnetic wave by the current transmitted by the communication cable,
An antenna for a non-contact information recording medium, wherein the loop diameter of the power receiving antenna is configured to be smaller than the loop diameter of the loop antenna.   The non-contact information recording medium antenna according to claim 1, wherein the power receiving antenna and the output antenna are connected by the communication cable via an impedance matching unit.   The non-contact information recording medium antenna according to claim 1, wherein the power receiving side antenna includes a power receiving level detector that monitors a level received by the power receiving side antenna.   The output-side antenna and / or the power-receiving-side antenna are a loop coil formed by winding a conducting wire, a magnetic member that is disposed in close contact with the loop coil and forms a magnetic path of electromagnetic waves generated from the loop coil, An antenna for a non-contact information recording medium according to any one of claims 1 to 3, further comprising: a metal member disposed in close contact with the magnetic member.   5. The contactless information recording medium according to claim 1, wherein the power reception side antenna is disposed at a place where a power reception level monitored by the power reception level detector is maximized. 6. antenna.   The loop diameter of the output antenna is configured to be larger than the loop diameter of the loop antenna, and the loop diameter of the loop antenna is configured to be larger than the loop diameter of the power receiving antenna. Item 6. The non-contact information recording medium antenna according to any one of Items 1 to 5.

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