JP2008028506A - Communication area expansion device of reader/writer for noncontact ic card and reader/writer employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an attachment for expanding communication area between an IC card and an R/W module without modifying the configuration of the R/W module at all. <P>SOLUTION: In the attachment 26 of reader/writer of noncontact IC card, a coil having a planar shape larger than the antenna of an R/W module 28 is covered with a synthetic resin coating of such as vinyl chloride, and the attachment is placed under the R/W module when in use. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication area expansion device for a non-contact IC card reader / writer and a reader / writer using the same, and more particularly, for example, a non-contact IC card (including an IC tag) by a reader / writer (R / W) module. Communication area expansion of a new IC card reader / writer that can expand the communication area between the IC card and the R / W module when reading information from or writing information to the card. The present invention relates to an apparatus and a reader / writer using the same.

  An example of this type of IC card and its reader is disclosed in Non-Patent Document 1, for example.

In order to improve versatility, the R / W module of the IC card is becoming smaller. In many cases, an antenna (usually a coil) is provided on the same circuit board on which a semiconductor chip for R / W is mounted. Therefore, as the R / W module becomes smaller, the size of the antenna also becomes smaller. Therefore, in a product incorporating such an R / W module, although the module can be downsized, there is an advantage that it is easy to incorporate, but the communication area with the IC card becomes narrow due to the small antenna, There are various restrictions (size, position, arrangement, etc.) in those products, and it is difficult to read information from or write information to the IC card as it is.
http://www.jpo.go.jp/shiryou/s_sonota/map/denki03/

  Therefore, a main object of the present invention is to provide a novel IC card reader / writer communication area expansion apparatus and a reader / writer using the same.

  Another object of the present invention is to provide an IC card reader / writer communication area expansion device and a reader / writer using the same, which can expand the communicable area without changing the configuration of the R / W module itself. is there.

  The invention of claim 1 is an apparatus for expanding a communication area of a reader / writer that reads information from or writes information to a non-contact IC card using an R / W module, and is an R / W module in plan view. This is a communication area expansion device for a reader / writer of a non-contact IC card, comprising a coil having a size equal to or larger than that of the antenna, and an electric circuit including the coil having a capacitive impedance when viewed from the antenna.

  In the first aspect of the present invention, the R / W module (28: reference numeral exemplifying a corresponding part in the embodiment, hereinafter the same) reads information on the IC card while communicating with the IC card (16). Write information to the IC card. The communication area extending device, that is, the attachment (26) of the embodiment has a coil having a size equal to or larger than the antenna (32) of the R / W module 28, and an electric circuit including the coil is connected to the antenna of the R / W module. Is set to have a capacitive impedance as viewed from the perspective.

  The antenna (32) of the R / W module receives a current having a carrier frequency (for example, 13.56 MHz, 125 kHz) as a center frequency when communicating with the IC card, and an AC magnetic field is present in the vicinity of the antenna (32). Is formed. When the coil (36) of the attachment (26) is brought close to the alternating magnetic field, an induced current flows through the coil. Normally, an induced current flows in a direction to cancel the AC magnetic field, but by making the electric circuit including this coil (36) a capacitive circuit, an induced current in phase with the AC magnetic field flows to the coil (36), This induced current strengthens the AC magnetic field of the antenna (32). Therefore, the communication between the IC card (16) and the R / W module (28) becomes possible only by bringing the IC card 16 in the vicinity of the attachment (26).

  By using the communication area extending apparatus according to the first aspect of the present invention, the communicable distance between the IC card and the R / W module, that is, the communicable area can be expanded without changing the R / W module.

  The invention according to claim 2 is the communication area extending apparatus according to claim 1, wherein the electric circuit resonates at a frequency near and higher than the center frequency of the R / W module.

  By setting the resonance frequency of the electric circuit including the coil as in the second aspect of the invention, the electric circuit can be made a capacitive circuit.

  A third aspect of the present invention is the communication area extending device according to the first or second aspect, wherein the coil has a shape of “8” in plan view.

  In the third aspect of the invention, since the orientation of the magnetic field formed on each coil side is reversed by making the shape of the attachment coil planar shape “8”, the magnetic field is strong in the vicinity of the R / W module. However, the magnetic fields cancel each other at a distance, and the magnetic field strength (radiation of radio waves) rapidly decreases with distance. Therefore, it is possible to reduce the influence on the outside when the attachment is used.

  The invention of claim 4 is a reader / writer that reads information from or writes information to a non-contact IC card, and has an R / W module having an antenna, and is equal to or more than the antenna of the R / W module in plan view. Including an attachment having a capacitive impedance when viewed from the antenna, and the attachment and the R / W module are arranged so that the coil is coupled to the antenna. It is a reader / writer for non-contact IC cards.

  According to the present invention, the communicable distance, that is, the communicable area between the IC card and the R / W module can be expanded without changing the R / W module.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  An electronic balance 10 as an embodiment of the present invention shown in FIG. 1 includes a housing 12 made of metal such as stainless steel, and the front surface of the housing 12 is inclined rearward as it goes upward, An operation panel 14 is attached. Although not shown in detail, the operation panel 14 includes operation keys for operating the IC card 16 for electronic payment, for example, for payment.

  In this embodiment, the IC card 16 is a passive non-contact IC card. However, it should be pointed out in advance that the communication area expanding device and reader / writer of the reader / writer according to the present invention can be used for an IC card of any other type or configuration.

  As shown in FIG. 2, the IC card 16 includes a card 18 made of, for example, a synthetic resin, and the planar view shape built into the card 18 is built into the rectangular loop antenna 20 and the card 18 and is electrically connected to the loop antenna 20. IC chip 22 connected to each other. The IC chip 22 includes a memory and a transmission / reception circuit as shown in FIG. 5 to be described later, and can exchange various data with the R / W module 28 (FIG. 4) to be described later via the loop antenna 20. It is configured.

  Returning to FIG. 1, the housing 12 is made of metal as described above. Therefore, all the side surfaces and the upper surface except the front surface of the housing 12 are sealed with metal, and the bottom surface is not made of metal but is made of synthetic resin. It is sealed with. Above the upper surface of the housing 12, a mounting table or an upper plate 24 for mounting an article (not shown) for measuring the weight is provided. And this upper plate 24 comprises the scale mechanism with the electronic circuit which is incorporated in the housing | casing 12 and which is not shown in figure.

  As the scale mechanism, for example, a mechanism in which the upper plate 24 is displaced downward according to the weight of the article placed thereon, and the weight of the article is calculated by detecting the displacement amount with an electronic circuit, or A mechanism for calculating the weight of an article from an electrical signal having a magnitude corresponding to the weight of the article placed on the upper plate 24 using an electrical means such as a strain gauge is conceivable. However, since the weighing mechanism itself is not the gist of the present invention, any weighing mechanism can be applied.

  Although the lower surface of the housing 12 is sealed with resin as described above, a part of the attachment 26 which is an example of the communication area expanding device protrudes forward from the lower surface. In this embodiment, as shown in FIG. 3, the attachment 26 is used by being stacked below the R / W module 28 (may be above). That is, the R / W module 28 is housed inside the housing 12, and a part of the distal end side of the attachment 26 superimposed on the R / W module 28 is projected forward from the bottom surface of the housing 12. As described above, the casing 12 is made of metal and does not transmit electromagnetic waves, but a part (bottom surface) of the casing 12 is sealed with a resin that can transmit electromagnetic waves. Is disposed in a housing made at least partially of an electromagnetic wave transmissive material.

  As shown in FIG. 4, the R / W module 28 includes a substrate 30, a loop antenna 32 having a rectangular shape in plan view formed on the substrate 30, and mounted on the substrate 30 and electrically connected to the loop antenna 32. A connected transmission / reception circuit 33, a CPU 34 connected to the transmission / reception circuit 33, and a memory 35 cooperating with the CPU 34 are included. Therefore, the R / W module 28 is configured to exchange various data with the above-described IC card 16 via the loop antenna 32, as shown in FIG.

  That is, as shown in FIG. 5, the transmission / reception circuit included in the IC chip 22 of the IC card 16 and the transmission / reception circuit 33 of the R / W module 28 through the antenna 20 of the IC card 16 and the antenna 32 of the R / W module 28. Communicate, and data and information are exchanged between the IC card 16 and the R / W module 28.

  The attachment 26 is used to expand the range, area, or distance in which the IC card 16 and the R / W module 28 can communicate with each other. As shown in FIG. The lower surface of the R / W module 28 and the upper surface of the R / W module 28 are arranged so as to be in close contact with each other, and a part thereof (portion not overlapping with the R / W module 28) is as shown in FIG. The electronic balance 10 is placed so as to protrude forward from the lower portion of the housing 12.

  That is, the attachment 26 of this embodiment is particularly effective when the R / W module 28 is sealed in a housing that does not transmit electromagnetic waves. In such a case, as described above, a part of the attachment 26 is exposed to the outside of the casing 12 through the bottom surface of the casing, and a part of the attachment 26 is electromagnetically transmitted to the R / W module 28 inside the casing 12. By coupling, the communicable range between the IC card 16 and the R / W module 28 can be substantially expanded as will be described in detail below.

  As shown in FIG. 6, the attachment 26 is obtained by covering a coil 36 having a rectangular shape in plan view with an exterior 38 made of a synthetic resin such as vinyl chloride.

  For example, the horizontal / vertical size of the planar rectangular loop antenna 20 of the IC card 16 is 50 mm × 80 mm as an example, and the horizontal / vertical size of the flat rectangular loop antenna 32 of the R / W module 28 is 50 mm × 80 mm as an example. In this case, the size of the flat rectangular coil 36 of the attachment 26 is set to 120 mm × 80 mm as an example.

  As described above, in the embodiment, the size of the coil 36 of the attachment 26 is set to about 1.5 to 2 times that of the loop antennas 20 and 32 of the IC card 16 and the R / W module 28. Is not limited to the arc ratio, and may be designed in consideration of the necessary communicable area, distance, size of empty space, and the like.

  In the embodiment shown in FIG. 1, a current having a carrier frequency (13.56 MHz, 125 kHz, etc.) as a center frequency flows through the antenna 32 of the R / W module 28 when communicating with the antenna 20 of the IC card 16. An alternating magnetic field is formed in the vicinity of. When the coil 36 of the attachment 26 is brought close to the AC magnetic field, an induced current flows through the coil 36.

  Normally, an induction current flows through the attachment coil 36 in a direction that cancels the alternating magnetic field, but the electric circuit including the coil 36 is a capacitive circuit when viewed even by the antenna 32 of the R / W module 28. An induced current having the same phase as the alternating magnetic field flows through the coil 36, and this induced current strengthens the alternating magnetic field of the antenna 32. Accordingly, the IC card 16 is merely brought near the attachment 26 as shown in FIG. 1, and the antenna 20 of the IC card 16 can be increased even if it is away from the antenna 32 of the R / W module 28. The IC card 16 and the R / W module 28 can communicate with each other. That is, the communicable distance can be expanded.

  Specifically, consider an equivalent circuit as shown in FIG. In the equivalent circuit of FIG. 7, the circuit A shows only the portion of the coil antenna 32 of the R / W module 28 built in the electronic balance 10, and the circuit B of the coil 36 of the attachment 26 for expanding the reading area of the embodiment. Indicates the part. Actually, the resistance (r) of the coil (L) and the loss resistance R due to the loss (tan δ) of the capacitor are present in the circuit, but are omitted here for simplicity.

  I1 and I2 are currents (AC) flowing through the respective circuits A and B, L is an inductance of the coil (Henry; H: usually μH order), and C is a capacitance of the capacitor (Farad; F, normal) Is pF order). M is the mutual inductance of the two coils L1 and L2.

  When the magnetic fluxes of the coil L1 and the coil L2 are linked to each other (in the case where the central axes of the two coils are common, or when the coil surfaces overlap each other when viewed in the axial direction), for example, An alternating magnetic field is generated by the current flowing through the coil L1, and the magnetic flux intersects (links) with the coil L2. The alternating magnetic field causes the coil L2 to follow the Faraday's law of electromagnetic induction (V = −dφ / dt). An induced voltage is generated so as to prevent the magnetic field change, and a current I2 flows in the circuit.

At this time, the circuit equation is the simplest equation (1).
[Equation 1]
jωM · I1 + (jωL · I2 + 1 / (j / ωC · I2)) = 0
When the capacitance value C is small in Equation 1, the additional circuit becomes capacitive, and Equation 1 can be approximated to Equation 2.
[Equation 2]
jωM · I1 + 1 / (j / ωC · I2) = 0
jωM · I1-jX · I2 = 0 (X = 1 / ωC)
jωM · I1 = jX · I2
Thus, the phases of the currents I1 and I2 match.

To be precise, the circuit equation shown in Equation 3 is obtained.
[Equation 3]
jωM · I1 + (jωL · I2 + 1 / (j / ωC · I2) + R · I2) = 0
In Equation 3, when ω = 1 / √ (L / C), that is, the impedance of the additional circuit is minimized at the resonance frequency, and the maximum current flows.

  When the resonance point is set to a high frequency near 13.56 MHz, for example, 14 MHz, the additional circuit including the coil 36 of the attachment 26 can be regarded as capacitive as described above, and the current of the same phase flows, thereby strengthening the magnetic field. Can do. Thus, by resonating the coil 36 of the attachment 26 preferably at a frequency slightly higher than 13.56 MHz, for example, the above-described 14 MHz, the impedance of the electric circuit B is reduced, and a larger current is generated. The magnetic field can be further increased by being induced by the coil 36. Therefore, the communication between the IC card 16 and the R / W module 28 becomes possible not only on the antenna 32 of the R / W module 28 but also on the coil 36 of the attachment 26 used for expansion. The communicable distance between the two becomes longer.

  When actually making an attachment, the general procedure is as follows.

  A coil of a suitable number of turns is wound and adjusted to a few μH.

  Connect a capacitor that can change its capacitance (semi-fixed) across the coil. The capacitance value is usually about several tens of pF.

  Using actual numbers, let's simply find each constant below.

Now, in order to resonate at 14 MHz with an inductance of 5 μH, the capacitance value is given by Equation 5 according to Equation 4.
[Equation 4]
fo = 1 / 2π√ (L · C)
C = 1 / (4π ² · fo ² · L)
[Equation 5]
C = 1 / (4 × 3.14 ² × 14 ² × 10 ¹² × 5 × 10 ⁻⁶ )
= 25.8 × 10 ⁻¹² = 25.8 pF
FIG. 8 is an illustrative view showing an experimental example of how long the communicable distance is increased by using the attachment 26 for extending the communicable area performed by the inventors. In the experiment, as shown in FIG. Further, both the antenna 32 of the R / W module 28 and the antenna 20 of the IC card 16 are 50 mm × 80 mm, the coil 36 of the attachment 26 is 120 mm × 80 mm, and the IC card 16 has the antenna of the R / W module 28. The antenna 32 is arranged in parallel. In the experiment, the IC card 16 was sequentially approached from the far side of the coil 36 of the attachment 26 (left side in FIG. 8), and the distance at which the R / W module started reading was measured. The result is shown in FIG.

  As can be seen from FIG. 9, when the attachment 26 is not used, the IC card 16 and the R / W module 28 become incapable of communication even if they are very far from the center of the R / W module antenna. When the attachment 26 was used, communication was possible even 100 mm away from the antenna center of the R / W module far away (leftward in FIG. 8). This experimental result clearly shows that the communicable distance, that is, the communicable area between the IC card and the R / W module can be expanded by using the attachment 26 as in the embodiment.

  In the embodiment of FIG. 6, the coil 36 of the attachment 26 has a flat rectangular shape. However, as shown in FIG. 10, the coil of the attachment 26 is changed to a coil 36 </ b> A having a shape of “8” in plan view. The direction of the current flowing through each coil side is opposite. For this reason, the direction of the magnetic field formed on each coil side is reversed, so that the magnetic field is strong in the vicinity (right side in FIG. 8), but the magnetic fields cancel each other far away, and the magnetic field strength (radio wave (Radiation) is reduced, and the influence on the outside can be reduced.

  Furthermore, in the above-described embodiment, the attachment 26 has a two-dimensional shape such as a flat plate. However, as in the embodiment shown in FIG. It can also be a dimensional shape. Also in this embodiment, as in the previous embodiment, the IC card 16 may be disposed near the attachment 26 and receive electromagnetic waves from its coil 36, as shown in FIG. .

FIG. 1 is an illustrative view showing one embodiment in which the present invention is applied to an electronic balance. FIG. 2 is an illustrative view showing one example of an internal configuration of an IC card used in the embodiment of FIG. FIG. 3 is an illustrative view showing only a reader / writer portion of the electronic balance of the embodiment shown in FIG. FIG. 4 is an illustrative view showing one example of an internal configuration of the R / W module used in the embodiment of FIG. FIG. 5 is a block diagram showing that the IC card and the R / W module can communicate with each other in the embodiment of FIG. 6 is an illustrative view showing the attachment shown in FIGS. 1 and 3 in a plan view. FIG. 7 is a circuit diagram showing an equivalent circuit when the antenna of the R / W module and the coil of the attachment are coupled as shown in FIG. FIG. 8 is a circuit diagram showing a method of an experiment conducted by the inventors for measuring the communicable area (distance) between the R / W module and the IC card in the embodiment shown in FIG. FIG. 9 is a graph showing that the communicable area (distance) between the R / W module and the IC card is expanded by the attachment in the embodiment shown in FIG. FIG. 10 is an illustrative plan view showing another embodiment of the attachment. FIG. 11 is an illustrative view showing still another embodiment of the attachment in relation to the R / W module and the IC card.

Explanation of symbols

10 ... Electronic scale 16 ... Non-contact IC card (IC card)
20, 32 ... Loop antenna 22 ... IC chip 26 ... Attachment 28 ... R / W module 36, 36A ... Coil

Claims (4)

An apparatus for extending a communication area of a reader / writer that reads information from or writes information to a non-contact IC card using an R / W module,
A coil having a size equal to or greater than that of the antenna of the R / W module in plan view;
A communication area expansion device for a reader / writer of a non-contact IC card, wherein an electric circuit including the coil has a capacitive impedance when viewed from the antenna.   The communication area extending device according to claim 1, wherein the electric circuit resonates at a frequency near and higher than a center frequency of the R / W module.   The communication area expanding device according to claim 1 or 2, wherein the coil has a shape of "8" in a plan view. A reader / writer that reads information from or writes information to a non-contact IC card,
An R / W module having an antenna, and a coil having a size equal to or larger than that of the antenna of the R / W module in plan view, and an electric circuit including the coil has a capacitive impedance when viewed from the antenna. With an attachment made to have,
A reader / writer for a non-contact IC card in which the attachment and the R / W module are arranged so that the coil is coupled to the antenna.

Images