JP2003141466A - Card read / write device and electromagnetic wave absorber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To be less affected by a member made of a metal material disposed inside a housing, to be able to stably transmit and receive to and from a non-contact IC card, and to have excellent workability. Provided are a card read / write device and an electromagnetic wave absorber. SOLUTION: An antenna 14 has one surface 1404 in a thickness direction of a printed board 1402 formed in a rectangular plate shape.
Further, a conductor (copper foil) 1406 is formed so as to extend in a rectangular annular shape so as to form one or more loops. The electromagnetic wave absorber 16 is formed in a rectangular plate shape having substantially the same shape as the outer shape of the printed circuit board 1402, and has a thickness in a state where one surface 1602 in the thickness direction is superimposed on the surface 1405 of the printed circuit board 1402. The other surface 1603 in the direction is disposed so as to face the inside of the housing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a card read / write device and an electromagnetic wave absorber.

[0002]

2. Description of the Related Art There is a non-contact type card read / write device for reading / writing (read / write) a non-contact type IC card. Such a card read / write device,
In order to read data from the non-contact type IC card or write data to the non-contact type IC card,
Data is exchanged between the built-in loop antenna and the built-in loop antenna of the non-contact type IC card via electromagnetic waves. For example, when the read / write device exchanges data with a non-contact type IC card having an electric circuit inside, a loop antenna built in each of the read / write device and the non-contact type IC card. Power is supplied from the reader / light device to the non-contact type IC card through electromagnetic waves transmitted and received between the reader and the reader. That is, the power of the data signal transmitted from the reader / light device to the non-contact type IC card is rectified and used as a power source in the electric circuit inside the non-contact type IC card. When data is exchanged between the non-contact type IC card and the card read / write device, it becomes more difficult to exchange data as the communication distance between them increases. The card read / write device uses an area where data can be exchanged as a communication area.

As disclosed in Japanese Patent Application Laid-Open No. 10-261055, a card read / write device can be classified into a near type having a communication distance of several mm and a distant type having a communication distance of several cm to several meters. The near-field type and the distant-type have different advantages, and are used properly according to their respective applications. In the proximity type card read / write device, since the communication distance is several mm, the non-contact type IC card is used by being inserted into the card read / write device. On the other hand, in the remote type card read / write device, there is no need for this, and if the contactless IC card is carried in the communication area, data can be freely written from the contactless IC card. An example of application of a remote card read / write device is a ticket gate system at a station. In the case of this ticket gate system, the person trying to pass the contactless type I
When a predetermined ID card consisting of a C card is held over the front of the card read / write device attached to the ticket gate, the LC resonance circuit in the ID card resonates with the electromagnetic wave radiated from the loop antenna of the card read / write device to generate a high-frequency current. Is induced. Then, the power supply circuit in the non-contact type IC card rectifies the high frequency current induced in the LC resonance circuit and is used as a power source for each circuit built in the non-contact type IC card. The information in the non-contact type IC card is transmitted to the card reader device by using this power source. In such a ticket gate system, the card read / write device is attached to a conventional mechanical ticket gate. A lot of metal parts are built inside the mechanical ticket gate. Therefore, when the card read / write device is attached to the ticket gate, electromagnetic waves emitted directly from the front surface of the loop antenna provided in the card read / write device and electromagnetic waves emitted from the back surface of the loop antenna are attached to the back surface of the loop antenna. There is a problem that the electromagnetic waves in front of the loop antenna are weakened because the reflected waves generated by being reflected by the metal parts of the existing ticket gate interfere with each other.

This will be specifically described. Figure 1
3 is a schematic configuration diagram of a conventional card read / write device. The card read / write device 30 is configured to write and read data to and from the memory of the non-contact IC card 40 by transmitting and receiving radio wave signals to and from the non-contact IC card 40 having a memory that holds data. . The card read / write device 30 includes an antenna 32 and a signal transmission / reception circuit 34 that transmits / receives a radio wave signal via the antenna 32. The antenna 32
Is formed in a plate shape, and one surface 3202 in the thickness direction thereof is formed.
Is provided at the location of the housing 31 so that the other surface 3204 faces the outside of the housing 31 and the other surface 3204 faces the inside of the housing 31. It is configured to generate a field H. However,
In the conventional card read / write device 30 described above, the electromagnetic field H generated from the antenna 32 is transferred to the housing 31.
It is also formed inside. Therefore, when the member M containing a metal material is disposed inside the housing 31, the directivity of the electromagnetic field H changes due to the influence of the member M,
The magnetic field strength weakens. Accordingly, the non-contact I
Inconvenience has occurred such that the communication distance with the C card 40 is shortened.

In order to solve the above problems, for example, Japanese Utility Model Laid-Open No. 6-13214 discloses that an electromagnetic wave absorber made of ferrite is attached to the back surface of the loop antenna, and the radiated electromagnetic wave radiated from the loop antenna to the back surface of the loop antenna. Is absorbed by ferrite to eliminate the reflected wave from the metal wall head and avoid the interference of the reflected wave and the electromagnetic wave directly radiated from the loop antenna to the front surface, and a technique to obtain a stable communication distance is shown. . It should be noted that increasing the radiated electromagnetic field strength of the loop antenna is also one of the methods for solving the above problems, but increasing the radiated electromagnetic field strength may interfere with the operation of peripheral electronic devices or communication devices. Since they are connected, the radiated electromagnetic field strength of the loop antenna cannot be increased infinitely. In addition, the electromagnetic field method limits the electromagnetic field strength within a predetermined distance from the loop antenna.

[0006]

However, in the above-mentioned technique, since the electromagnetic wave absorber is made of ferrite, there is a drawback that the more complicated the electromagnetic wave absorber has, the more difficult it is to process. Further, since ferrite has the property of being hard but brittle, it is impossible to provide a shape such as a screw receiver. The present invention has been made in view of such an actual situation, and the purpose thereof is to:
A card read / write device and an electromagnetic wave absorber that are less susceptible to a member made of a metal material disposed inside the housing, can stably perform transmission / reception with a non-contact IC card, and are excellent in workability. To provide.

[0007]

In order to achieve the above-mentioned object, the present invention is a card read / write device having an antenna for transmitting and receiving radio signals to and from a non-contact type IC card, which is formed in a housing and a plate shape. The electromagnetic field is provided in a direction along the thickness direction of the housing so that one surface in the thickness direction faces the outside of the housing and the other surface faces the inside of the housing. The antenna includes a generating antenna and an electromagnetic wave absorber that is formed in a plate shape and is disposed so as to overlap with the other surface of the antenna, and the electromagnetic wave absorber is formed in substantially the same shape as the outer shape of the antenna. It is characterized by being composed of a ferrite composite material. Therefore, according to the present invention, when the antenna operates to generate an electromagnetic field, the direction of the electromagnetic field is along the side opposite to the side where the electromagnetic wave absorber is located in the thickness direction of the antenna. After extending, bend toward the outside of the outer edge of the antenna,
It is guided by the electromagnetic wave absorber so as to pass through the inside of the electromagnetic wave absorber. Further, according to the present invention, in a card read / write device having an antenna for transmitting and receiving a radio signal to and from a non-contact type IC card, the casing and a plate are formed, and one face in the thickness direction thereof is the casing. An antenna which is provided at the housing location so as to face the outside of the body and the other surface of which faces the inside of the housing, and which generates an electromagnetic field in a direction along the thickness direction thereof,
A plate-shaped electromagnetic wave absorber disposed on the other surface of the antenna so as to be superposed on the other surface of the antenna, wherein the electromagnetic wave absorber is formed of a soft magnetic metal alloy having substantially the same shape as the outer shape of the antenna. It is characterized by being composed of a composite material containing. Therefore, according to the present invention, when the antenna operates to generate an electromagnetic field, the direction of the electromagnetic field is along the side opposite to the side where the electromagnetic wave absorber is located in the thickness direction of the antenna. After extending, it bends toward the outside of the outer edge of the antenna and is guided by the electromagnetic wave absorber so as to pass through the inside of the electromagnetic wave absorber.

The present invention also provides an electromagnetic wave absorber which is disposed so as to be superposed on one surface in the thickness direction of a plate-shaped antenna that generates an electromagnetic field in the thickness direction. The electromagnetic wave absorber is made of a plate-shaped ferrite composite material formed in substantially the same shape as the outer shape of the antenna. Therefore, according to the present invention, when the antenna operates to generate an electromagnetic field, the direction of the electromagnetic field is along the side opposite to the side where the electromagnetic wave absorber is located in the thickness direction of the antenna. After extending
It bends toward the outside of the outer edge of the antenna and is guided by the electromagnetic wave absorber so as to pass through the inside of the electromagnetic wave absorber. The present invention also provides an electromagnetic wave absorber which is disposed so as to be superposed on one surface in the thickness direction of a plate-shaped antenna that generates an electromagnetic field in a direction along the thickness direction. The body is characterized by being made of a composite material containing a plate-shaped soft magnetic metal alloy formed in substantially the same shape as the outer shape of the antenna. Therefore, according to the present invention, when the antenna operates to generate an electromagnetic field, the direction of the electromagnetic field is along the side opposite to the side where the electromagnetic wave absorber is located in the thickness direction of the antenna. After extending, it bends toward the outside of the outer edge of the antenna and is guided by the electromagnetic wave absorber so as to pass through the inside of the electromagnetic wave absorber.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of a card read / write device and an electromagnetic wave absorber of the present invention will be described with reference to the drawings. FIG. 2 is an explanatory diagram showing a schematic configuration of the card read / write device and the non-contact type IC card according to the first embodiment. The card read / write device 10 includes a housing 12, an antenna 14, an electromagnetic wave absorber 16, a signal transmission / reception circuit 18, an information processing circuit (not shown), and the like. The housing 12 is configured to house the signal transmitting / receiving circuit 18 and the information processing circuit therein. As shown in FIGS. 1 and 3, in the antenna 14, a conductor (copper foil) 1406 forms a loop at least once on one surface 1404 in the thickness direction of a printed board 1402 formed in a rectangular plate shape. It is configured by extending and forming a rectangular ring shape. That is, the antenna 14 is configured as a loop antenna. The printed circuit board 140
Screw insertion holes 1408 are formed at positions near the four corners of 2. As shown in FIG. 6B, the antenna 14 generates an electromagnetic field H in the direction along the thickness direction of the printed circuit board 1402 (the direction orthogonal to the plane including the loop of the conductor 1406). In other words, the electromagnetic field H is generated above the upper surface of the printed board 1402.

As shown in FIGS. 1 and 4, the electromagnetic wave absorber 16 is formed in a rectangular plate shape having substantially the same shape (or almost the same contour) as the outer shape of the printed circuit board 1402, and has a thickness. One surface 1602 in the direction is superimposed on the surface 1405 of the printed circuit board 1402,
The other surface 1603 in the thickness direction is arranged so as to face the inside of the housing 12. Screw insertion holes 1604 are formed through the electromagnetic wave absorber 16 in the vicinity of the four corners thereof. When the electromagnetic wave absorber 16 is superposed on the printed circuit board 1402, the screw insertion holes 1604 and the screw insertion holes 14 are formed.
The positions of 08 are configured to match. The electromagnetic wave absorber 16 is composed of a ferrite composite material formed by mixing a powder material obtained by pulverizing a ferrite material formed by sintering iron oxide and an oxide, and a synthetic resin material. As the ferrite material, for example, manganese-zinc ferrite, nickel-zinc ferrite, manganese-zinc ferrite, or the like can be used. As the synthetic resin material, thermoplastic polyamide resin, polyurethane resin, chlorinated polyethylene, silicone rubber or the like can be used.

As shown in FIG. 2, the signal transmitting / receiving circuit 1
Reference numeral 8 denotes a conductor 14 of the antenna 14 via an LC circuit (not shown) whose capacitance value is set so as to resonate corresponding to the inductance of the antenna 14 and a predetermined resonance frequency.
It is connected to both ends of 06. This signal transmitting / receiving circuit 18
Is configured to transmit and receive data by radio waves to and from the non-contact IC card 20 via the antenna 14. The information processing circuit is the non-contact IC card 2
The data for writing to 0 is input to the signal transmitting / receiving circuit 18, and the non-contact IC card 20
The data transmitted from is input and read from the transmission / reception circuit 18.

As shown in FIG. 6B, the antenna 1
4 and the electromagnetic wave absorber 16 are attached to the housing 12, the surface 1404 of the printed board 1402 faces the outside (upper) of the housing 12, and the other surface 1 of the printed board 1402 is attached.
405 and the surface 1602 of the electromagnetic wave absorber 16 are overlapped with each other, and the surface 1405 of the printed circuit board 1402 and the surface 1605 of the electromagnetic wave absorber 16 face the inside of the housing 12 from the surface 1402 side of the printed circuit board 14. It is performed by inserting screws in the order of the screw insertion holes 1408 and 1604 and screwing the screws into the screw holes provided in the housing 12.

As shown in FIGS. 2 and 5, the non-contact IC
The card 20 is a card body 22 formed in a rectangular plate shape.
And an IC 24 incorporated in the card body 22 and an antenna 26 made of a conductor extending annularly so as to form a loop on the card body 22 one or more times. The IC 24 includes a signal transmission / reception circuit 2402 and a signal transmission / reception circuit 240 which are connected to the antenna 26 via an LC circuit (not shown) as shown in FIG.
It has a control circuit (not shown) that sends and receives signals to and from the memory 2, and a memory (not shown) in which data is read / written by the control circuit. The IC 24 is configured to operate using, as a power source, electromotive force generated by electromagnetic induction of the antenna 26 generated by an electromagnetic field emitted from the antenna 14 of the card read / write device 10.

Next, the operation of the card read / write device 10 configured as described above will be described. Figure 6
As shown in (B), when the electric current is supplied to the conductive member 1406 of the antenna 14 by the operation of the transmission / reception circuit 18, an electromagnetic field H forming an annular shape along the circumferential direction of the conductive member 1406 is generated. Occur. That is, the electromagnetic field H
Is oriented toward the surface 14 opposite to the electromagnetic wave absorber 16.
After extending from 04 along the thickness direction of the antenna 14, it bends toward the outside of the outer edge of the antenna 14 and is guided by the electromagnetic wave absorber 16 so as to pass through the inside of the electromagnetic wave absorber 16.

In this state, when the non-contact IC card 20 is positioned within the reach of the electromagnetic field H, electromagnetic induction is generated in the antenna 26 which receives the electromagnetic field H, and the electromotive force causes the IC 24 to operate. Operate. Then, the signal transmission / reception circuit 2402 of the non-contact IC card 20 becomes a state capable of transmission / reception. That is, when writing data to the non-contact IC card 20 by the card read / write device 10, data transmitted from the information processing circuit of the card read / write device 10 is input to the antenna 14 from the signal transmission / reception circuit 18. This is performed by being transmitted as a radio wave signal, received by the antenna 26 of the non-contact IC card 20, input to the control circuit via the signal transmission / reception circuit 2402, and written in the memory by the control circuit. . The non-contact IC card 2 by the card read / write device 10
In the reading of data of 0, the data read from the memory by the control circuit of the non-contact IC card 20 is input to the antenna 26 from the signal transmission / reception circuit 2402 and transmitted as a radio wave signal, and the radio wave signal is transmitted to the card. This is performed by being received by the antenna 14 of the read / write device 10 and being input to the information processing circuit via the signal transmission / reception circuit 18.

As described above, according to the present embodiment, FIG.
As shown in (B), the electromagnetic field H is generated by the electromagnetic wave absorber 1
By being shielded by 6, the surface 1 of the antenna 14
It is not formed inside the housing 12 that the 405 faces, so that the directivity of the electromagnetic field H from the surface 1404 of the antenna 14 to the outside of the housing 12 can be strengthened. Therefore, even if the member M containing the metal material is present inside the casing 12, the electromagnetic field H is not guided to the member M, so that it is not affected and the outside of the casing 12 is prevented. The electromagnetic field H generated in the field becomes stable. Therefore, the transmission / reception state of the radio signal between the card read / write device 10 and the non-contact IC card 20 is determined by the member M containing the metal material existing inside the housing 12 of the card read / write device 10.
Is less likely to be affected by the size and position of the radio wave, and thus the transmission / reception state of the radio signal can be stabilized.

As shown in FIG. 6 (A), the electromagnetic wave absorber 1
In the case where 6 is not provided, that is, when the configuration is the same as that of the conventional device, the electromagnetic field H is formed even inside the housing 12, so the card read / write device 10 and the non-contact IC card 2
The transmission / reception state of the radio signal between 0s is easily affected by the size and the arrangement position of the member M containing the metal material existing inside the housing 12 of the card read / write device 10. On the other hand, in the present embodiment, it is understood that the influence of the member M is reduced.

Further, in the present embodiment, since the ferrite composite material forming the electromagnetic wave absorber 16 is formed by mixing the powder material obtained by crushing the ferrite material and the synthetic resin material, the electromagnetic wave absorber is formed. The strength (hardness and tenacity) can be improved as compared with the case where 16 is composed of only a ferrite material. Therefore, there is an advantage that it is easy to provide the screw insertion hole 1408 in the electromagnetic wave absorber 16 and process and mold the electromagnetic wave absorber 16 into a desired shape. Further, in the case where the electromagnetic wave absorber 16 is composed only of a ferrite material, even if a screw hole is provided, when screwing through the screw hole, the portion of the screw hole that abuts the screw. Inconvenience such as chipping is expected, but the electromagnetic wave absorber 16
If the above-mentioned ferrite composite material is used, such inconvenience will not occur.

Next, the card read / write device 1 described above
Specific experimental results for No. 0 will be described with reference to FIGS. 7 to 9. FIG. 7 is an explanatory diagram showing the results of the first experiment. In the first experiment, when a plurality of kinds of materials forming the electromagnetic wave absorber 20 are changed and a member M (shown as a metal part in the drawing) containing a metal material is disposed inside the housing 12, the influence thereof is exerted. The hardness of the electromagnetic wave absorber 20 was evaluated by a spring hardness tester. The conditions for the material of the electromagnetic wave absorber 16 are as follows. Condition 1: No electromagnetic wave absorber Condition 2: Only ferrite (mixing ratio ferrite 100
%) Condition 3: Ferrite powder and polyamide resin ferrite composite material Condition 4: Ferrite powder and polyurethane resin ferrite composite material Condition 5: Ferrite powder and chlorinated polyethylene ferrite composite material Condition 6: Ferrite powder and silicon rubber ferrite composite material In material conditions 3 to 6, the compounding ratio is ferrite 70.
vol% and resin 30 vol%. In addition, the polyamide resin has thermoplasticity. In the first experiment, the longest communication distance that can be transmitted and received between the card read / write device 10 and the non-contact IC card 20 under each of the above conditions was set when the member M was not provided. By measuring the time, it is measured how much the communication distance is reduced by disposing the member M. Specifically, a metal plate was used as the member M, and the measurement was performed in a state in which the member M was provided at a position spaced 50 mm from the back side of the antenna. As shown in FIG. 7, the ferrite composite material has a communication reduction rate of -8% when the electromagnetic wave absorber is not provided and a communication distance reduction rate of -5% when the electromagnetic wave absorber 16 composed of only ferrite is provided. It can be seen that when the electromagnetic wave absorber 16 composed of is provided, the communication distance reduction rate is a good value of -3%.
In addition, when a polyamide resin is used as the synthetic resin material, the hardness thereof is 90, which is advantageous in improving the workability when performing processing such as forming through a screw hole. It was

FIG. 8 is an explanatory diagram showing the results of the second experiment. In the second experiment, the volume resistivity and the communication distance were measured by changing the compounding ratio of the ferrite and the compounding ratio of the polyamide resin forming the electromagnetic wave absorber 20. The conditions for the ferrite composite material of the electromagnetic wave absorber 16 are as follows. Sample A: ferrite powder (Mn-Zn: manganese-
70% by volume of zinc), 30% by volume of polyamide resin Sample B: ferrite powder (Mn-Zn: manganese-)
Zinc) 50 vol%, polyamide resin 50 vol% Sample C: Ferrite powder (Ni-Zn: Nickel-
70% by volume of zinc), 30% by volume of polyamide resin Sample D: ferrite powder (Ni-Zn: nickel-)
Zinc) 60 vol%, polyamide resin 40 vol% Sample E: Ferrite powder (Mg-Zn: magnesium-zinc) 50 vol%, polyamide resin 50 vol% The second experiment was carried out under the respective conditions under the conditions described above with the card read / write device 10. The longest communication distance that can be transmitted and received to and from the contact IC card 20 is measured. Also,
The polyamide resin has thermoplasticity. As shown in FIG. 8, Samples C, D, and E having a volume resistivity of 1 × 10 ⁵ Ωm or more have a communication distance of 103 mm or more, which are good.

FIG. 9 is an explanatory view showing the result of the third experiment. In the third experiment, the magnetic permeability and the communication distance were measured by changing the compounding ratios of the ferrite and the polyamide resin that compose the electromagnetic wave absorber 20. The conditions for the ferrite composite material of the electromagnetic wave absorber 16 are as follows. Sample F: ferrite powder (Ni-Zn: nickel-
Zinc) 50 vol%, polyamide resin 50 vol% Sample G: Ferrite powder (Ni-Zn: Nickel-)
Zinc) 60 vol%, polyamide resin 40 vol% Sample H: Ferrite powder (Ni-Zn: Nickel-
Zinc) 70 vol%, polyamide resin 30 vol% Sample I: Ferrite powder (Mg-Zn: magnesium-zinc) 60 vol%, polyamide resin 40 vol% Sample J: Ferrite powder (Mg-Zn: magnesium-zinc) 70 vol%, polyamide resin 30 vol % In the third experiment, the longest communication distance and magnetic permeability that can be transmitted and received between the card read / write device 10 and the non-contact IC card 20 are measured under the respective conditions. The magnetic permeability of the composite material was measured by making a toroidal coil from the composite material and determining the effective magnetic permeability at 10 MHz. In addition, the polyamide resin has thermoplasticity. As shown in FIG. 9, samples F, G, and H having a magnetic permeability of 15 or less are good because they ensure a communication distance of 104 mm or more.

Next, a second embodiment will be described. The difference between the second embodiment and the first embodiment is that the electromagnetic wave absorber is made of a composite material containing a soft magnetic metal alloy. The composite material is formed by mixing soft magnetic metal alloy powder and a synthetic resin material. Next, specific experimental results of the card read / write device according to the second embodiment will be described with reference to FIGS. Further, in the following description, the same parts as those of the read / write device and the electromagnetic wave absorber in the first embodiment will be denoted by the same reference numerals. Figure 10
It is explanatory drawing which shows the 4th experiment result. In the fourth experiment,
By changing the types of materials that make up the electromagnetic wave absorber 20,
When a member M (shown as a metal component in the drawing) containing a metal material is arranged inside the casing 12, how much the influence is exerted is measured, and the hardness of the electromagnetic wave absorber 20 is measured by a spring hardness. It was evaluated by a testing machine. Electromagnetic wave absorber 1
The conditions for the composite material of No. 6 are as follows. Condition 1: No electromagnetic wave absorber Condition 2: Only ferrite (mixing ratio ferrite 100
%) Condition 3: Composite material of soft magnetic metal alloy powder and polyamide resin Condition 4: Composite material of soft magnetic metal alloy powder and polyamide resin Condition 5: Composite material of soft magnetic metal alloy powder and chlorinated polyethylene Condition 3 to Condition 5 In the above, the compounding ratio was 50 vol% of soft magnetic metal alloy powder and 50 vol% of resin. In addition, the polyamide resin has thermoplasticity. Fourth
Under the conditions described above, the longest communication distance that can be transmitted and received between the card read / write device 10 and the non-contact IC card 20 under each of the above conditions is obtained when the member M is not provided and when the member M is provided. By measuring, it is measured how much the communication distance is reduced by disposing the member M. The experimental conditions are the same as in the first experiment.
As shown in FIG. 10, when the electromagnetic wave absorber 16 is not provided, the communication reduction rate is -8%, and when the electromagnetic wave absorber 16 made of only ferrite is provided, the communication distance reduction rate is -5%. When an electromagnetic wave absorber made of a composite material containing a metal alloy powder is provided, the communication distance reduction rate is −
It can be seen that the value is as good as 3%. Further, when a polyamide resin is used as the synthetic resin material, the hardness thereof is 100, which is advantageous in improving workability when performing processing such as forming through a screw hole. It was

FIG. 11 is an explanatory diagram showing the results of the fifth experiment. In the fifth experiment, the volume resistivity and the communication distance were measured by changing the types of soft magnetic metal alloy powder and the mixing ratio of the polyamide resin that compose the electromagnetic wave absorber 16. The conditions for the composite material of the electromagnetic wave absorber 16 are as follows. Sample A: Soft magnetic metal alloy powder (Fe-Si: iron-silicon) 40 vol%, polyamide resin 60 vol% Sample B: Soft magnetic metal alloy powder (Fe-Si: iron-silicon) 50 vol%, polyamide resin 50 vol% Sample C : Soft magnetic metal alloy powder (Fe-Al-Si:
40 vol% of iron-aluminum-silicon, 60 vol% of polyamide resin Sample D: Soft magnetic metal alloy powder (Fe-Al-Si:
(Iron-aluminum-silicon) 50 vol%, polyamide resin 50 vol% The fifth experiment is to measure the longest communication distance that can be transmitted and received between the card read / write device 10 and the non-contact IC card 20 under each of the above conditions. It was done. Also,
The polyamide resin has thermoplasticity. As shown in FIG. 11, in all samples A, B, C, and D having a volume resistivity of 7 × 10 ⁴ Ωm or more, a communication distance of 98 m
It is good because it secures m or more. Therefore, it can be judged that those having a volume resistivity of 1 × 10 ⁵ Ωm or more are good.

FIG. 12 is an explanatory diagram showing the results of the sixth experiment. In the sixth experiment, the magnetic permeability, the permittivity, and the communication distance were measured by changing the types of the soft magnetic metal alloy powder and the polyamide resin composition ratio that compose the electromagnetic wave absorber 16. The magnetic permeability of the composite material was measured by making a toroidal coil from the composite material and determining the effective magnetic permeability at 10 MHz. The dielectric constant of the composite material is 10 MHz when a disk is made of the composite material.
It was measured by determining the effective dielectric constant of. The conditions for the composite material of the electromagnetic wave absorber 16 are as follows. Sample E: Soft magnetic metal alloy powder (Fe-Si: iron-silicon) 40 vol%, polyamide resin 60 vol% Sample F: Soft magnetic metal alloy powder (Fe-Si: iron-silicon) 50 vol%, polyamide resin 50 vol% Sample G : Soft magnetic metal alloy powder (Fe-Al-Si:
40 vol% of iron-aluminum-silicon, 60 vol% of polyamide resin Sample H: Soft magnetic metal alloy powder (Fe-Al-Si:
(Iron-aluminum-silicon) 50 vol%, polyamide resin 50 vol% In the sixth experiment, the longest communication distance that can be transmitted and received between the card read / write device 10 and the non-contact IC card 20 is measured under the respective conditions. It was done. Also,
The polyamide resin has thermoplasticity. As shown in FIG. 12, the magnetic permeability is 15 or less and the dielectric constant is 100.
The above samples E, G, and H are good because they ensure a communication distance of 102 mm or more.

Also in the second embodiment, as in the first embodiment, the composite material forming the electromagnetic wave absorber 16 is formed by mixing the soft magnetic metal alloy powder and the synthetic resin material. Therefore, the strength (hardness and tenacity) can be improved as compared with the case where the electromagnetic wave absorber 16 is made of only a ferrite material. Therefore, there is an advantage that it is easy to form the screw insertion hole in the electromagnetic wave absorber and to process and mold the electromagnetic wave absorber into a desired shape.

In each of the above-described embodiments, the antenna 14 of the card read / write device 10 has a structure in which the conductor 1406 forms one loop. However, the antenna 14 is
The conductor 1406 may form a plurality of loops, and the conductors 1406 of each loop may be connected in parallel. Further, in each of the embodiments, the printed circuit board 1402 forming the antenna 14 is adhered to the insulating substrate via the insulating adhesive film, and the electromagnetic wave absorber 16 is disposed on the other surface of the loop antenna 14. Alternatively, the electromagnetic wave absorber 16 may be attached in a state of being parallel to the insulating substrate.

[0027]

As described above, according to the card read / write device and the electromagnetic wave absorber of the present invention, it is unlikely to be affected by the member made of the metallic material disposed inside the housing, and the transmission / reception with the non-contact IC card is performed. Can be done stably. Further, it is possible to provide a card read / write device and an electromagnetic wave absorber having excellent workability.

[Brief description of drawings]

FIG. 1 is a perspective view showing configurations of an antenna and an electromagnetic wave absorber of a card read / write device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a card read / write device and a non-contact type IC card according to the first embodiment.

FIG. 3 is a plan view of the antenna according to the first embodiment.

FIG. 4 is a plan view of the electromagnetic wave absorber according to the first embodiment.

FIG. 5 is a plan view of a non-contact IC card.

FIG. 6A is an explanatory view showing a state of an electromagnetic field when the electromagnetic wave absorber is not provided in the card read / write device, and FIG. 6B is a case where the electromagnetic wave absorber is provided in the card read / write device. FIG. 6 is an explanatory diagram showing the state of the electromagnetic field of FIG.

FIG. 7 is an explanatory diagram showing a first experimental result according to the first embodiment.

FIG. 8 is an explanatory diagram showing a second experimental result in the first embodiment.

FIG. 9 is an explanatory diagram showing a result of a third experiment in the first embodiment.

FIG. 10 is an explanatory diagram showing a result of a fourth experiment according to the second embodiment.

FIG. 11 is an explanatory diagram showing a fifth experimental result in the second embodiment.

FIG. 12 is an explanatory diagram showing a sixth experimental result according to the second embodiment.

FIG. 13 is a schematic configuration diagram of a conventional card read / write device.

[Explanation of symbols]

10 ... Card read / write device, 14 ... Antenna,
1404 ... surface, 1405 ... surface, 1406 ... conductor, 16 ... electromagnetic wave absorber, 1602 ... surface, 1603
... surface, 20 ... non-contact IC card, H ... electromagnetic field.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiichi Kagami             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 5B058 CA17 CA22 KA24 KA40 YA20                 5E040 CA13                 5E041 AB01 AB02 CA10                 5E321 BB21 BB32 BB51 GG11

Claims (38)

[Claims] 1. A card read / write device having an antenna for transmitting and receiving a radio signal to and from a non-contact type IC card, comprising: a casing; and a plate-shaped surface of which one side in the thickness direction is the casing. Of the antenna, which is formed in the shape of a plate and which is provided in the housing location so that the other surface thereof faces the outside of the housing and which generates an electromagnetic field in the direction along the thickness direction thereof. An electromagnetic wave absorber disposed so as to be superposed on the other surface, wherein the electromagnetic wave absorber is made of a ferrite composite material formed into substantially the same shape as the outer shape of the antenna. Card read / write device. 2. The ferrite composite material is formed by mixing a powder material obtained by crushing a ferrite material formed by sintering iron oxide and an oxide, and a synthetic resin material. The card read / write device according to claim 1. 3. The ferrite material is any one of manganese-zinc ferrite, nickel-zinc ferrite, and manganese-zinc ferrite.
Card read / write device described. 4. The synthetic resin material is a polyamide resin,
The card read / write device according to claim 2, wherein the card read / write device is one of polyurethane resin, chlorinated polyethylene, and silicone rubber. 5. The card read / write device according to claim 2, wherein the synthetic resin material is a thermoplastic polyamide resin. 6. The card read / write device according to claim 1, wherein the volume resistivity of the ferrite composite material is 1.0 × 10 ⁵ Ωm or more. 7. The magnetic permeability of the ferrite composite material is 15
The card read / write device according to claim 1, wherein: 8. The card read / write device according to claim 1, wherein the ferrite composite material has a hardness and a viscosity such that holes for screwing can be formed. 9. The card read / write device according to claim 1, wherein the antenna is a loop antenna configured by forming a conductor on a printed circuit board in an annular shape. 10. The printed circuit board provided with the loop antenna is adhered onto an insulating substrate via an insulating adhesive film, and the electromagnetic wave absorber is arranged on the other surface of the antenna. 10. The card read / write device according to claim 9, wherein the electromagnetic wave absorber is mounted in parallel with the insulating substrate. 11. The electromagnetic wave absorber blocks the entry of an electromagnetic field emitted from the antenna into the housing, and directs the electromagnetic field emitted from the antenna to the outside of the housing. The card read / write device according to claim 1, which is characterized in that. 12. The card read / write device according to claim 1, wherein a member containing a metal material is disposed inside the housing. 13. A card read / write device having an antenna for transmitting and receiving a radio wave signal to and from a non-contact type IC card, comprising: a casing; and a plate-shaped one surface of which one side in the thickness direction is the casing. Of the antenna, which is formed in the shape of a plate and which is provided in the housing location so that the other surface thereof faces the outside of the housing and which generates an electromagnetic field in the direction along the thickness direction thereof. An electromagnetic wave absorber disposed so as to be superimposed on the other surface, wherein the electromagnetic wave absorber is composed of a composite material containing a soft magnetic metal alloy formed in substantially the same shape as the outer shape of the antenna, A card read / write device characterized in that 14. The card read / write device according to claim 13, wherein the composite material is formed by mixing soft magnetic metal alloy powder and a synthetic resin material. 15. The card read / write device according to claim 14, wherein the synthetic resin material is a thermoplastic polyamide resin. 16. The volume resistivity of the composite material is 1.0 ×
14. The card read / write device according to claim 13, wherein the card read / write device has a resistance of 10 ⁵ Ωm or more. 17. The card read / write device according to claim 13, wherein the composite material has a dielectric constant of 100 or more. 18. The card read / write device according to claim 13, wherein the magnetic permeability of the composite material is 15 or less. 19. The card read / write device according to claim 13, wherein the composite material has hardness and tenacity to the extent that holes for screwing can be formed. 20. The card read / write device according to claim 13, wherein the antenna is a loop antenna configured by forming a conductor on a printed circuit board in an annular shape. 21. The printed circuit board provided with the loop antenna is adhered to an insulating substrate via an insulating adhesive film, and the electromagnetic wave absorber is disposed on the other surface of the antenna. 21. The card read / write device according to claim 20, wherein the electromagnetic wave absorber is mounted in parallel with the insulating substrate. 22. The electromagnetic wave absorber prevents the electromagnetic field emitted from the antenna from entering the inside of the housing, and directs the electromagnetic field emitted from the antenna to the outside of the housing. 14. The card read / write device according to claim 13, which is characterized in that. 23. The card read / write device according to claim 13, wherein a member containing a metal material is disposed inside the housing. 24. An electromagnetic wave absorber disposed so as to be superposed on one surface in the thickness direction of a plate-shaped antenna that generates an electromagnetic field in the thickness direction, the electromagnetic wave absorber Is composed of a plate-shaped ferrite composite material formed in substantially the same shape as the outer shape of the antenna. 25. The ferrite composite material is formed by mixing a powder material obtained by pulverizing a ferrite material formed by sintering iron oxide and an oxide, and a synthetic resin material. The electromagnetic wave absorber according to claim 24. 26. The ferrite material is manganese-zinc ferrite, nickel-zinc ferrite, manganese-
26. The electromagnetic wave absorber according to claim 25, which is any one of zinc ferrite. 27. The electromagnetic wave absorber according to claim 24, wherein the synthetic resin material is any one of polyamide resin, polyurethane resin, chlorinated polyethylene, and silicon rubber. 28. The electromagnetic wave absorber according to claim 24, wherein the synthetic resin material is a thermoplastic polyamide resin. 29. The electromagnetic wave absorber according to claim 24, wherein the volume resistivity of the ferrite composite material is 1.0 × 10 ⁵ Ωm or more. 30. The magnetic permeability of the ferrite composite material is 1.
25 or less, The electromagnetic wave absorber of Claim 24 characterized by the above-mentioned. 31. The electromagnetic wave absorber according to claim 24, wherein the ferrite composite material has a hardness and a viscosity such that holes for screwing can be formed. 32. An electromagnetic wave absorber disposed so as to be superposed on one surface in the thickness direction of a plate-shaped antenna that generates an electromagnetic field in a direction along the thickness direction. The electromagnetic wave absorber is characterized in that it is made of a composite material containing a plate-shaped soft magnetic metal alloy formed in substantially the same shape as the outer shape of the antenna. 33. The electromagnetic wave absorber according to claim 32, wherein the composite material is formed by mixing soft magnetic metal alloy powder and a synthetic resin material. 34. The electromagnetic wave absorber according to claim 32, wherein the synthetic resin material is a thermoplastic polyamide resin. 35. The volume resistivity of the composite material is 1.0 ×
33. The electromagnetic wave absorber according to claim 32, which has a resistance of 10 ⁵ Ωm or more. 36. The electromagnetic wave absorber according to claim 32, wherein the dielectric constant of the composite material is 100 or more. 37. The electromagnetic wave absorber according to claim 32, wherein the magnetic permeability of the composite material is 15 or less. 38. The electromagnetic wave absorber according to claim 32, wherein the composite material has a hardness and a viscosity such that holes for screwing can be formed.