JP2008040862A - Rfid reader/writer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID reader/writer which requires no specific space, ensures a sufficient communication distance and is excellent in durability. <P>SOLUTION: A connector 11 is provided at one end of a base board 10. An antenna 12 for transmission and reception is formed, with a coil-shaped pattern, in the vicinity of the end part, opposite to the connector 11, on the upper surface of the base board 10. The base board 10 is provided with components necessary for a reader/writer. A case 20 for accommodating the base board 10 is formed with a resin. A magnetic material is mixed on the opposite side, in the case 20, to the communication surface of the antenna 12 for transmission and reception. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an RFID reader / writer that can read and write information without contact with an RFID card by connecting to an external device such as a personal computer. The present invention relates to an RFID reader / writer in which communication performance of an antenna is improved.

  In recent years, an IC chip that can store information electronically, and a system using a card or a tag that includes an interface for exchanging information between the IC chip and the outside, has attracted attention because of its various possibilities. Collecting. Such a system is generally referred to as an RFID (Radio Frequency Identification) system. By combining a small recording medium (card or tag) with a reader / writer that reads and writes data on the recording medium, it is possible to perform solid-state authentication in various situations. It can be used to send and receive data.

  As for a small-sized recording medium, there are various names such as an RFID card, an IC card, a wireless card, an RFID tag, and an IC tag. In the present invention, although referred to as an RFID card, it is not intended to be limited to a specific type, but is a broad concept including all the above cards, tags, and the like. Since such an RFID card can store a large amount of information in the memory of the IC chip and prevent counterfeiting, compared with the magnetic recording type used in conventional cards, Widely used as credit cards, electronic money, electronic tickets, telephone cards, ID cards, cargo management tags, and the like.

  As a method for transmitting and receiving information to and from the reader / writer, a contact type in which an electrode contact provided on the surface of the RFID card and a contact terminal provided on the reader / writer are brought into contact with each other, an RFID card and a reader / writer are used. There is a non-contact type that is performed wirelessly through an antenna (coil) provided. In particular, non-contact type RFID cards have high durability because they do not wear due to contact, do not require a mechanism to move the RFID card to the reader / writer, and have a high degree of freedom in direction during transmission and reception. It is expected to spread as something with convenience.

By the way, the communication distance of the non-contact type RFID reader / writer that performs transmission / reception via the antenna as described above is remarkably reduced when there is metal on the back surface. In order to cope with this, what has been proposed in which a magnetic powder is mixed in a binder to form a sheet or plate and is attached to the back surface of an antenna made of a coil in a direction parallel to the coil ( (See Patent Document 1 and Patent Document 2).
JP 2005-340759 A JP 2006-13976 A

  However, as described above, when a sheet mixed with magnetic powder is attached, the magnetic layer is thin and a sufficient communication distance cannot be secured. Furthermore, in the case of the sheet, there are problems such as the magnetic powder peeling off or the magnetic powder rusting at high humidity. Further, when a plate mixed with magnetic powder is used, there is a problem that the shape becomes large.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and an RFID reader that can secure a sufficient communication distance without using a special space and has excellent durability. The purpose is to provide a writer.

  In order to achieve the above object, the invention of claim 1 is directed to an antenna for transmitting / receiving information to / from the outside, a control unit for processing information transmitted / received via the antenna for transmitting / receiving, the antenna for transmitting / receiving, and the control. In the RFID reader / writer having a case housing a portion, the side of the case opposite to the communication surface of the transmitting / receiving antenna is made of a material containing a magnetic material.

  In the invention of claim 1 as described above, the case itself is made of a material containing a magnetic material, so that the communication distance can be extended, and a special space for the magnetic material is not required at all. Can be maintained. Further, since the magnetic material is hardened by the material of the case, peeling and rusting are prevented.

  The invention according to claim 2 is a transmission / reception antenna for transmitting / receiving information to / from the outside, a control unit for processing information transmitted / received via the transmission / reception antenna, and a case housing the transmission / reception antenna and the control unit The material including the magnetic material is potted on the opposite side to the communication surface of the transmitting / receiving antenna in the case.

  In the invention of claim 2 as described above, since the magnetic material can be arranged by potting using the gap inside the case, the communication distance can be extended while eliminating the need for a special space. Moreover, since the magnetic material is hardened with resin, peeling and rusting are prevented. Further, the potting portion protects the parts in the same manner as the filling resin.

  According to a third aspect of the present invention, in the RFID reader / writer according to the second aspect, the transmitting / receiving antenna and the control unit are disposed on a substrate, and the potting is sized to cover the entire surface of the substrate. To do.

  In the invention of claim 3 as described above, the function of extending the communication distance and protecting the parts can be improved by setting the size to cover the substrate on which the transmitting / receiving antenna and the control unit are arranged.

  According to a fourth aspect of the present invention, in the RFID reader / writer according to the second aspect, the potting material has a hardness of 80 or less.

  In the invention of claim 4 as described above, since the hardness is 80 or less, deterioration of the magnetic properties of the magnetic material can be prevented even when subjected to external stress.

  According to a fifth aspect of the present invention, in the RFID reader / writer according to any one of the first to fourth aspects, the magnetic material is a soft magnetic material selected from an amorphous alloy, permalloy, silicon steel, sendust alloy, and soft magnetic ferrite. It is characterized by including.

  In the invention of claim 5 as described above, by using the soft magnetic material, a material suitable for improving the communication distance can be applied.

  A sixth aspect of the present invention is the RFID reader / writer according to any one of the first to fifth aspects, wherein the case has a loop coil having a diameter larger than that of the transmission / reception antenna and a transmission / reception antenna disposed therein. And a capacitor connected to the loop coil, and a resonance antenna that resonates in the vicinity of the carrier frequency of the RFID reader / writer is provided.

  In the invention of claim 6 as described above, by using the resonance antenna so that the magnetic flux density of the transmitting and receiving antenna can reach the far side while maintaining high strength, the RFID reader / writer can be brought closer to the card or tag side. Can also be used.

  According to a seventh aspect of the present invention, in the RFID reader / writer according to the sixth aspect, the loop coil is disposed on an adhesive tape and is affixed to the inner surface of the case.

  In the above invention of Claim 7, since the loop coil is comprised on the adhesive tape affixed on the inner surface of a case, the clearance inside a case can be utilized.

  According to an eighth aspect of the present invention, in the RFID reader / writer according to the sixth aspect, the loop coil is embedded in a resin constituting the case.

  In the invention of claim 8 as described above, since the loop coil is embedded in the case, no special space is required.

  According to a ninth aspect of the present invention, in the RFID reader / writer according to the sixth aspect, the resonant antenna is formed on a flexible substrate by printing.

  In the invention of claim 9 as described above, since the resonant antenna is formed on the flexible substrate, the entire resonant antenna can be disposed using the gap inside the case.

  As described above, according to the present invention, it is possible to provide an RFID reader / writer that can secure a sufficient communication distance without using a special space and has excellent durability.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described.
[First Embodiment]
[Constitution]
[Basic configuration]
First, the basic configuration of the RFID reader / writer according to the present embodiment will be described with reference to FIGS. 2 and 3 show the arrangement of each part, and the shape is simplified. That is, the present embodiment is configured by arranging parts necessary for the reader / writer on the substrate 10 and accommodating them in the case 20 as shown in FIG. The board 10 is a substantially rectangular parallelepiped printed wiring board, and a connector 11 is provided at one end in the longitudinal direction.

  The connector 11 is a USB (Universal Serial Bus) interface capable of realizing plug and play or the like by being inserted into a connector such as a personal computer. In the drawing, USB 2.0 series A is shown, but series B, series mini B, and the like that can be used at present or in the future can be applied. For example, conventional USB 1.0, 1.1, USB On-The-Go (OTG), etc., which are expected to become popular in the future, can be applied.

  In general, the male side and the female side are collectively referred to as a “connector”, and the male side is referred to as a “plug”. However, in the claims and the following description, for convenience, the “plug” is also referred to as a “connector”. Call it.

  A transmitting / receiving antenna 12 is formed in a coiled pattern on the upper surface of the substrate 10 (the upper surface when connected to a personal computer). The transmitting / receiving antenna 12 is disposed in the vicinity of the end of the substrate 10 opposite to the connector 11. For example, in the case of an RFID card using the 13.56 MHz band, the transmission / reception antenna 12 is a circular spiral loop having a diameter of about 1 cm and a line width of 100 μm, so that a communication distance of about 2 cm can be secured. It is conceivable that the distance is 125 μm. However, the embodiment of the present invention is not limited to these numerical values.

  Further, as shown in FIGS. 2 and 3, the substrate 10 includes a control circuit including a resonator 13, a control IC 14 and the like, and a radio wave interface. The oscillator 13 is a crystal oscillator that generates a high-frequency wave that is a carrier wave, is amplified by an amplifier, and is supplied to the transmission / reception antenna 12. Between the connector 11 and the transmission / reception antenna 12 on the upper surface side of the substrate 10. It is arranged.

  The control IC 14 is a mold-sealed IC chip, and constitutes a CPU, a memory, and the like that perform processing necessary for USB connection and a reader / writer. The control IC 14 is disposed between the connector 11 and the transmitting / receiving antenna 12 on the lower surface side of the substrate 10. Since other electronic components can be realized by a known technique, the description thereof is omitted.

  Further, a mini jack 15 that is a terminal for connecting an external antenna is attached to an end of the substrate 10 opposite to the connector 11. The mini jack 15 is configured such that when a mini plug of an external antenna (not shown) is inserted, the connection between the transmission / reception antenna 12 and the control unit is cut off and the external antenna becomes effective. The connector 11, the transmission / reception antenna 12, the control unit, and the mini jack 15 are connected by a wiring pattern formed on the substrate 10. Details of these, the connection method of each component, and the like are well-known techniques. Therefore, the description is omitted.

[Case structure]
Next, the configuration of the case 20 will be described. That is, the case 20 incorporates the substrate 10 and the connector 11 is exposed from one end thereof. The cap 30 is detachably provided on the case 20 and is configured to cover and protect the connector 11 by being attached. The case 20 is made of resin, but in the present embodiment, the following structure is adopted.

[When magnetic material is mixed in the case]
First, a case where a magnetic material is mixed in the case 20 will be described with reference to FIG. That is, the case 20 is made of resin mixed with a magnetic material on the side opposite to the communication surface of the transmitting / receiving antenna 12 on the substrate 10 (M1). As the magnetic material, soft magnetic materials such as amorphous alloy, permalloy, silicon steel, sendust alloy, soft magnetic ferrite, and the like are suitable, but not limited thereto.

[When magnetic material is potted in the case]
On the other hand, a case where a magnetic material is potted inside the case 20 will be described with reference to FIG. That is, the case 20 is potted with a mixture of resin and soft magnetic powder on the opposite side of the communication surface of the transmitting / receiving antenna 12 on the substrate 10 (M2). Potting is filling a specific part with resin, and in this embodiment, potting is performed in a range covering the entire one surface of the substrate 10.

[Action]
[how to use]
The operation of the present embodiment as described above will be described with reference to FIGS. The RFID card 40 used in the present embodiment is a passive type that does not incorporate a power supply, and has a basic structure similar to that of a general RFID card such as an IC chip having a memory, a CPU, and the like and an antenna. .

  First, as shown in FIG. 4, the cap 30 is removed from the reader / writer case 20 to expose the connector 11. Then, the connector 11 is connected to the USB connector (female side) of the notebook personal computer PC. Then, the reader / writer is automatically recognized in the OS of the notebook personal computer PC by the USB plug and play function, and the keyboard and the display can be used as input / output means.

  It is convenient to set the device driver or the like so that, when first connected, the one stored in the control unit in advance is called and automatically performed. However, it is also possible to install it by downloading it separately from a recording medium such as a CD-ROM or via a network.

  Next, as shown in FIG. 5, when the RFID card 40 is brought close to the case 20, communication by electromagnetic induction is possible between the transmitting / receiving antenna 12 and the antenna AT of the RFID card 40. That is, an induction electromagnetic field is generated by applying a carrier wave to the transmission / reception antenna 12, and when the RFID card 40 enters this, a current flows through the antenna AT. Electric power is supplied by the induced electromotive force, and the RFID card 40 becomes operable.

  Thereby, for example, information recorded in the RFID card 40 can be displayed and read on the display of the notebook personal computer PC via the reader / writer. Moreover, desired information can be written in the RFID card 40 by inputting from a keyboard or mouse of the notebook personal computer PC.

[Experimental result]
The experimental results comparing the communication distance between the reader / writer of this embodiment used as described above and the conventional reader / writer will be described. First, in the example manufactured as the present embodiment, a mixture of silicon rubber and NiZn ferrite powder was potted on the opposite side to the communication surface of the transmitting / receiving antenna 12 on the substrate 10 in the case 20.

  The conventional example to be compared is the same as the example except that the soft magnetic powder is not mixed and potted with respect to the case 20. In addition, in both the example and the conventional example, those with a metal plate and those without a metal plate were prepared, and the communication distances were compared. FIG. 6 shows experimental results comparing such an example with a conventional example. As is apparent from FIG. 6, it can be seen that the communication distance is longer in the embodiment with and without the metal plate.

[effect]
According to the present embodiment as described above, when a magnetic material is mixed into the case 20 itself, the thickness is sufficient and the communication distance can be extended, and a space for the magnetic material is completely unnecessary. , Can keep downsizing. Moreover, since the magnetic powder is hardened with resin, there is no problem that the magnetic powder is peeled off or rusted.

  In addition, when a magnetic material is potted in the case 20, since a gap inside the case 20 is used, a sufficient space can be secured in the same manner as described above while eliminating the need for a special space. The distance can be extended, and there is no problem that the magnetic powder is peeled off or rusted. Further, the potted portion protects the electronic components on the substrate 10 as in the case of the filling resin.

[Second Embodiment]
[Constitution]
A second embodiment of the present invention will be described with reference to FIGS. That is, in this embodiment, basically, a magnetic material is mixed in the case 20 (indicated by M1 in FIGS. 8, 10, and 11), or the magnetic material is contained in the case, as in the above-described embodiment. (Not shown, but similar to the first embodiment). However, in the present embodiment, as shown in FIG. 7, a resonance antenna 21, which is a circuit electrically independent from the circuit of the RFID reader / writer, is provided on the inner surface of the case 20. In the present embodiment, the resonance antenna 21 is provided on the inner surface of the case 20 facing the transmission / reception antenna 12 provided on the substrate 10 as shown in FIG. The resonant antenna 21 is disposed between the transmission / reception antenna 12 and the RFID card 40.

  In this embodiment, the resonant antenna 21 includes a loop coil 23 wound in a loop on an adhesive tape 22 and a capacitor 24 connected to the loop coil 23, as shown in FIG. The adhesive tape 22 is fixed to the case 20 by affixing it to the inner surface of the case 20. In this case, for example, the coil length and the capacitance of the loop coil 23 and the capacitor 24 are determined so as to resonate at 13.56 MHz which is the transmission frequency of the RFID reader / writer.

[Function and effect]
In general, the magnetic flux density B (z) at a distance z from the center of a loop antenna such as the transmitting / receiving antenna 12 is defined as a current I flowing through the loop antenna, a radius a of the circular loop antenna, and a conversion constant μ0 in MKS units.
B (z) = (μ0Ia2) / 2 (z2 + a2) 3/2
As the radius a decreases, the magnetic flux density B (z) increases (higher), and as z increases, it decreases (lowers) in proportion to the cube of z.

  When the distance of z gradually increases and becomes a distance of z> a, the magnetic flux density B (z) decreases, and finally communication with the RFID card becomes impossible. That is, the greater the radius of the transmission / reception antenna 12, the greater the communication distance. In the present embodiment, the resonance antenna 21 allows the transmission / reception antenna 12 to reach the far side with high magnetic flux density, so that the RFID reader / writer can be used closer to the card or tag side. become.

  In other words, in this embodiment, the resonant antenna 21 that resonates at the transmission frequency from the transmission / reception antenna 12 is provided in the case 20, so that a larger-diameter booster antenna is disposed in the vicinity of the transmission / reception antenna 12. Therefore, at the time of transmission from the RFID reader / writer, a magnetic flux density stronger in the resonance antenna 21 portion than in the transmission / reception antenna 12 portion can be obtained by the resonance action.

  As a result, a far greater communication distance can be ensured than when the transmitting / receiving antenna 12 is used alone. For example, by connecting the RFID reader / writer to a personal computer with a USB cable, It can be used as a reader / writer. Therefore, combined with the effect of the first embodiment, the communication distance can be further increased.

[Other Embodiments]
The present invention is not limited to the above-described embodiment, and includes various aspects as described below.

(a) As described above, amorphous alloy, permalloy, silicon steel, sendust alloy, or soft magnetic ferrite is suitable as the soft magnetic material, but is not limited thereto. Multiple materials may be used. The region where the soft magnetic material is mixed into the case and the region where potting is performed are preferably within the range covering the entire surface of the substrate, but are not limited thereto. Further, the resin used as the case material or potting is not limited to those exemplified above. The hardness of the resin is not limited to a specific one, but may be 80 or less, for example. More preferably, 50 or less is good. By setting it as such hardness, even if it receives external stress, deterioration of the magnetic characteristic of a magnetic material can be prevented.

となる。この場合、インダクタンスＬとキャパシタンスＣの値の調整で、共振周波数を変更できるが、搬送周波数に対して多少高い周波数にした方が値のばらつきに対して余裕がでる。 (b) When the resonance point wave of the resonant antenna 21, the resonance frequency is f, the inductance is L, and the capacitance is C,

It becomes. In this case, the resonance frequency can be changed by adjusting the values of the inductance L and the capacitance C. However, if the frequency is slightly higher than the carrier frequency, there is a margin for variation in the values.

(c) In order to enhance the effect of the resonant antenna, adjustment is performed to match the impedance of the resonant circuit of the transmitting / receiving antenna 12 formed on the substrate with the output impedance of the RF section. By adjusting with an LCR meter or the like, the peak of the resonance frequency is made lower than the carrier frequency.

(d) The effect of the present invention is not achieved unless the transmitting / receiving antenna 12 on the substrate is within the loop of the resonant antenna 21 when viewed from the upper surface of the substrate. However, in consideration of this point, the positional relationship between the transmitting / receiving antenna 12 and the resonant antenna 21 is not limited to the illustrated one. For example, as shown in FIG. 10, it is also possible to provide the resonant antenna 21 on the opposite side with the substrate of the transmitting / receiving antenna 12 interposed therebetween.

(e) The circuit on the resonant antenna side can be formed on an adhesive sheet using printing technology, or can be formed on a flexible substrate by printing, etc., and it is easy to manufacture thinly and inexpensively. .

(f) As shown in FIG. 11, it is also possible to embed the resonant antenna in the resin constituting the case.

(g) The distance between the transmitting / receiving antenna 12 and the resonant antenna 21 on the board is the same as the radius of the antenna on the board, and the communication distance is the longest, but within this distance, the resonant antenna is not used. The effect can be confirmed compared to. However, the effect cannot be expected when the resonant antenna is used apart from the radius distance.

(h) The position where the resonant antenna is provided on the case may be on either the upper surface side or the lower surface side of the case, considering the positional relationship with the antenna as described above. In addition, as long as the area of the resonance antenna can be accommodated in the case, it is more effective to maximize the area.

(i) It is also free to combine the above embodiments. Case with magnetic material mixed in the case itself, case material potted with magnetic material, resonance antenna provided on the upper surface side of the case, provided on the lower surface side, provided on both sides, inside the case Any of various aspects such as those embedded may be combined with each other. If a magnetic material is mixed in the case, potted with the magnetic material, and a resonant antenna is provided, the communication distance will be dramatically increased. If the resonant antenna is disposed so as to contact the inner surface of the case mixed with the magnetic material, the magnetic path passes through the magnetic material and leakage flux is reduced.

(j) The radio waves used for communication with the RFID card are not limited to those exemplified above. In the above embodiment, the passive type is exemplified as the RFID card to be used. However, an active type having a built-in power source may be used.

(k) The standards for each component are not limited to the above. For example, USB is suitable as a connector interface, but a standard having the same convenience can be freely applied at present or in the future.

(l) Any computer equipped with an input / output device such as a desktop personal computer, a server device, a PDA, and a mobile phone can be applied to an external device connected to and used by the present invention.

It is a top view which shows the time of cap mounting (A) of the 1st Embodiment of this invention, and the time of cap removal (B). FIG. 2 is a cross-sectional view showing a case where a magnetic material is mixed in a case in the embodiment of FIG. 1. FIG. 2 is a cross-sectional view showing a case where a magnetic material is potted in a case in the embodiment of FIG. 1. It is explanatory drawing which shows the mounting method to the notebook personal computer in embodiment of FIG. It is explanatory drawing which shows the utilization method of the RFID card | curd in embodiment of FIG. It is explanatory drawing which shows the comparison result of the communication distance of embodiment of FIG. 1, and a prior art example. It is a top view which shows the structure of the 2nd Embodiment of this invention. It is sectional drawing which shows the RFID reader / writer of embodiment of FIG. It is a top view of the resonant antenna in embodiment of FIG. It is sectional drawing which shows other embodiment of the RFID reader-writer of this invention. It is sectional drawing which shows other embodiment of the RFID reader-writer of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate 11 ... Connector 12 ... Transmission / reception antenna 13 ... Oscillator 14 ... Control IC
15 ... Mini jack 20 ... Case 21 ... Resonant antenna 22 ... Adhesive tape 23 ... Loop coil 24 ... Capacitor 30 ... Cap 40 ... RFID card AT ... Antenna PC ... Notebook PC

Claims (9)

In an RFID reader / writer having an antenna for transmitting / receiving information to / from the outside, a control unit for processing information transmitted / received via the transmission / reception antenna, and a case housing the transmission / reception antenna and the control unit,
The RFID reader / writer according to claim 1, wherein the case is formed of a material including a magnetic material on a side opposite to a communication surface of the transmitting / receiving antenna. An RFID reader / writer having a transmission / reception antenna for transmitting / receiving information to / from the outside, a control unit for processing information transmitted / received via the transmission / reception antenna, and a case housing the transmission / reception antenna and the control unit ,
An RFID reader / writer characterized in that a material containing a magnetic material is potted on the opposite side to the communication surface of the transmitting / receiving antenna in the case. The transmitting / receiving antenna and the control unit are disposed on a substrate,
3. The RFID reader / writer according to claim 2, wherein the potting is sized to cover the entire surface of the substrate.   3. The RFID reader / writer according to claim 2, wherein the potting material has a hardness of 80 or less.   5. The RFID reader / writer according to claim 1, wherein the magnetic material includes a soft magnetic material selected from an amorphous alloy, permalloy, silicon steel, Sendust alloy, and soft magnetic ferrite.   The case includes a loop coil having a diameter larger than that of the transmission / reception antenna and a transmission / reception antenna disposed therein, and a capacitor connected to the loop coil, and resonates in the vicinity of the carrier frequency of the RFID reader / writer. The RFID reader / writer according to claim 1, wherein a resonance antenna is provided.   The RFID reader / writer according to claim 6, wherein the loop coil is disposed on an adhesive tape and is affixed to an inner surface of the case.   The RFID reader / writer according to claim 6, wherein the loop coil is embedded in a resin constituting the case.   The RFID reader / writer according to claim 6, wherein the resonant antenna is formed on a flexible substrate by printing.

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