JPH08263610A - Non-contact card reader - Google Patents

Abstract

PURPOSE: To provide a non-contact card reader which can prevent the unnecessary reading of card data out of the back and which has less influence to other electronic units without being affected by installation environment. CONSTITUTION: A coil-like antenna 4 which discharges an electromagnetic wave having a previously decided frequency to a non-contact card and receives a modulation wave obtained by modulating the electromagnetic wave discharged from the non-contact card by means of card data in response to the discharge, a capacitance element constituting an LC resonance circuit having a resonance frequency equal to a previously selected frequency together with the coil-like antenna 4 and a metallic plate 11 arranged at the back of the coil-like antenna 4 are provided. The metallic plate 11 is provided with a function for insulating the discharge of the electromagnetic wave discharged to the back of the coil-like antenna 4 more back than the metallic plate 11 and a function for shifting the resonance frequency of the LC resonance circuit from the previously selected frequency so that it becomes equal to the previously decided frequency by excess current generated in the metallic plate 11 when the electromagnetic wave is insulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transfers data between a contactless card and a contactless card reader using electromagnetic waves, and reads and writes card data of the contactless card without contacting each other. The present invention relates to a contactless card reader used in a contactless card system.

[0002]

2. Description of the Related Art (1) A personal identification system using a contactless card has a high security performance for personal data stored in the contactless card. (2) There is no need to insert a card into a card reader when writing and reading card data, unlike a magnetic stripe card, which is excellent in convenience. (3) Since it is excellent in waterproof performance, it is hardly affected by the external environment such as rain.

There are many advantages as compared with a contact type card represented by a magnetic stripe card, and it is increasingly used as a personal identification medium used in an entrance / exit management system such as a building.

In particular, in a system in which a contactless card is attached to a chest or the like also as a name tag or an identification card, the electric lock of the door is unlocked only by approaching the contactless card reader installed in front of the door. The fact that it can open the door is appreciated.

[0005] Most of the non-contact card readers used in such access control systems are mounted on the wall near the entrance door of the office by being exposed or embedded in the wall. In many cases, there is a reinforcing bar for reinforcing concrete, but it is extremely rare that all of these surrounding conditions can be grasped when the non-contact card reader is installed.

Further, when the wall on which the non-contact card reader is mounted is relatively thin, the coil antenna of the non-contact card reader emits electromagnetic waves not only to the front side (front side) but also to the back side (rear side) thereof. Since it has a square-shaped directional characteristic (described later), it may be possible to read card data from the back side of the non-contact card reader, and in order to prevent this, a metal is placed on the back wall of the non-contact card reader. There is also a case where a plate is used for shielding (described later).

[0007] As described above, despite the fact that the surrounding conditions when the contactless card reader is actually installed vary widely, the conventional contactless card reader is not suitable when placed in free space. It is designed to exhibit the best performance, and in most cases, when the installation environment changes, the reading performance of the card data is greatly reduced.

Hereinafter, a conventional contactless card reader will be described in detail with reference to the drawings.

At present, non-contact cards used as personal identification media for access control systems are roughly classified into 2G cards.
There are two types, one using near microwaves of about Hz to 3 GHz and one using long waves or medium waves of about several tens kHz to several hundred kHz. In the former, the contactless card often has a battery as a power source, but in the latter, the contactless card itself does not have a power source such as a battery, but receives electromagnetic waves radiated from the contactless card reader and detects it. In many cases, a non-contact card is used as a power source for the contactless card.

The present invention relates to a contactless card reader for a batteryless contactless card, which uses the latter electromagnetic waves in the long-wave band or the medium-wave band for data transfer.

FIG. 3 shows an electric configuration of a main part of a non-contact card 1 of a battery-less type and a conventional non-contact card reader 2. The non-contact card 1 used as a personal identification medium of the access control system stores individual personal identification data as card data. When power is supplied to the non-contact card 1 in the form of an electromagnetic wave, the non-contact card 1 Card 1
Then, the card data (personal identification data) is transmitted to the non-contact card reader 2 by modulating the electromagnetic wave. That is, the contactless card 1 transmits a modulated wave obtained by modulating electromagnetic waves with card data (personal identification data) to the contactless card reader 2.

The contactless card reader 2 is a contactless card 1
An oscillation amplifying unit 3 that oscillates and amplifies a continuous signal or an intermittent signal of several tens kHz to several hundreds kHz serving as a power supply of
The output signal of the oscillation amplifier 3 is set to several tens of kHz to several hundreds of kHz.
A coil-shaped antenna 4 which emits an electromagnetic wave having a predetermined frequency within Hz and receives an electromagnetic wave (that is, a modulated wave) modulated by the card data (personal identification data) from the contactless card 1, and Electromagnetic waves (ie modulated waves)
And a card data demodulation circuit 5 for demodulating card data. That is, this card data demodulation circuit 5
The card data superimposed on the electromagnetic wave is discriminated.

In the actual contactless card reader 2, the guard data read in addition to the above is compared with a data comparing portion for preventing the guard data from becoming erroneous data due to mixed noise, etc., and the card data and the host controller or computer. A part that controls communication, a power supply part, and a control part such as an electric lock may be included, but they are omitted here because they are not directly related to the present invention.

As a card data modulation method, FSK (fre
Frequency shift keying) modulation, phase modulation and the like are often used.

FIG. 3 shows an example in which the transmission antenna and the reception antenna are shared by one coil antenna 4, but the coil antenna 4 may be divided into a transmission antenna and a reception antenna.

The contactless card reader 2 often operates intermittently at all times in order to reduce the power consumption, but the cycle of the intermittent operation is such that an individual having the contactless card 1 approaches the contactless card reader 2. , Which is sufficiently shorter than the time for reading the card data, and is selected from several times / second to several tens times / second.

FIGS. 4 and 5 are a front view and a side view of the coiled antenna 4 of FIG. The coiled antenna is a coiled one having a diameter of several cm to several tens of cm, and its diameter is selected depending on the installation conditions of the non-contact card reader 2 (FIG. 3), the required performance of reading card data, and the like.

As shown in FIG. 6, capacitors 61 and 62 are connected in parallel to the coiled antenna 4 in order to improve the efficiency of transmission and reception of electromagnetic waves, and together with the coiled antenna 4, a frequency of several tens of kHz to several hundreds of kHz is selected. An LC resonance circuit having the above-described predetermined frequency as a resonance frequency is configured. That is, the capacitor 61
And 62, together with the coiled antenna 4, constitute a resonance circuit at a frequency used for transmitting and receiving card data. In order to supply sufficient power to the coiled antenna 4, the power supply of the non-contact card reader 2 (FIG. 3) In order to increase the voltage at both ends of the coil antenna 4 as compared with the voltage, the antenna is often divided as shown in the figure. Reference numeral 7 is a final stage (transistor) of a drive circuit for driving the LC resonance circuit including the coiled antenna 4 and the capacitors 61 and 62.

In the illustrated example, a voltage sufficient to drive the coiled antenna 4 is obtained by dividing the capacitor, but a tap is provided on the coiled antenna 4 to drive a part of the coiled antenna 4. By doing so, the voltage is also amplified, and the same effect can be obtained.

The coiled antenna 4 shown in FIGS. 4 and 5 has a directivity characteristic of a figure 8 as shown in FIG.
That is, the electromagnetic wave is emitted not only to the area 81 on the front side of the coiled antenna 4 but also to the area 82 on the back side of the coiled antenna 4. As described above, the conventional non-contact card reader 2 (FIG. 3) having the coiled antenna 4 shown in FIGS. 4 and 5 generally has figure-shaped card data reading ranges 81 and 82.

FIG. 8 shows an actual arrangement example of the conventional non-contact card reader 2 (FIG. 3). 8, this contactless card reader 2 includes a coiled antenna 4, an oscillation amplifier 3 (FIG. 3), and a card data demodulation circuit 5 (FIG. 3).
It has an electronic circuit 9 including the above, and a case 10 that houses the coiled antenna 4, the electronic circuit 9, and the like. This case 1
Numeral 0 has a waterproof structure so as to withstand outdoor use, and electric wires required for power supply, signal output, and the like are drawn out through a waterproof structure outlet (not shown).

[0022]

Continuing to refer to FIG. 8, the coiled antenna 4 is placed on the inner front surface (front surface) of the contactless card reader 2 in order to efficiently read card data. As shown in FIG. 7, the antenna 4 has a directivity characteristic of the shape of a figure 8. Therefore, a part of the electromagnetic wave emitted from the coiled antenna 4 passes through the electronic circuit 9 and the back surface of the contactless card reader 2. When the non-contact card is also discharged to the side and approaches the back surface of the non-contact card reader 2, the non-contact card reader 2 also reads the card data of the non-contact card.

In order to prevent such unnecessary reading of card data, the contactless card reader 2 may be thickened so that electromagnetic waves are not emitted to the back side of the contactless card reader 2. Since the non-contact card reader 2 is often embedded in a wall and attached, it is desirable that the non-contact card reader 2 be as thin as possible from that surface. By increasing the thickness of the non-contact card reader 2, the emission of electromagnetic waves to the back side is prevented. That is not realistic.

In order to prevent reading of card data from the back surface of the non-contact card reader 2, the back wall of the non-contact card reader 2 may be shielded by a metal plate as described above. However, in this case, an eddy current due to the electromagnetic wave of the coiled antenna 4 is generated on the metal plate, and the inductance of the coiled antenna 4 is reduced accordingly, so that the coiled antenna 4 and the capacitance element (capacitors 61 and 62 in FIG. 6). ) And the resonant frequency of the LC resonant circuit configured by

Even if the back wall of the contactless card reader 2 is not shielded by a metal plate, the coiled antenna 4 is naturally affected by the metal around the contactless card reader 2,
When there is a metal object on the back (back) side of the non-contact card reader 2, the inductance of the coiled antenna 4 changes greatly. That is, when the coiled antenna 4 is operated near a metal object, an eddy current is generated in the metal object due to the electromagnetic wave of the coiled antenna 4, and the inductance of the coiled antenna 4 is reduced accordingly. And a capacitance element (capacitors 61 and 6 in FIG. 6)
2) The resonance frequency of the LC resonance circuit constituted by and changes.

Such a change in the resonance frequency lowers the transmission efficiency and the reception efficiency of the coiled antenna 4, so that the reading distance of the contactless card reader 2 is significantly reduced and the current consumption is increased. Will degrade the operation stability.

Referring to FIGS. 1 to 8, as described above,
In order to increase the efficiency of communication with the non-contact card 1, the non-contact card reader 2 uses a capacitor in which a capacitance element including capacitors 61 and 62 of FIG. 6 is connected in parallel to the coiled antenna 4 to form an LC resonance circuit. This increases the efficiency of communication with the card.

Therefore, the non-contact card reader 2 is provided with a reinforcing bar for reinforcing concrete around its back side, electric wires used for other electronic equipment, and emission of electromagnetic waves to the back side of the coiled antenna 4. When installed in an environment with a metal object such as a metal plate to prevent, the inductance of the coiled antenna 4 of the non-contact card reader 2 changes due to the influence of the surrounding metal object, and the resonance frequency of the LC resonance circuit is different from that of the non-contact card 1. Not only does the frequency deviate from the predetermined frequency used for the communication, the efficiency of transmission / reception to / from the contactless card 1 is reduced, and the reading distance of the contactless card reader 2 is significantly shortened. Due to the decrease in the impedance of No. 4, the power consumption becomes very large and other inconveniences occur.

In addition, the long-term stable operation of the non-contact card reader 2 is often impaired, for example, due to the effect of leakage noise from electric wires used for other devices, such as unstable reception of card data.

Further, when the resonance frequency of the LC resonance circuit deviates from the frequency of the electromagnetic wave used in the non-contact card 1, the generation of harmonics increases, which may affect the operation of other electronic devices. .

Therefore, the conventional contactless card reader 2 is
The installation environment must be strictly regulated, for example, by stipulating a certain distance from the wires of metal objects and other equipment, and this hinders the free construction of an access control system.

In addition, when an access control system using the contactless card 1 is actually installed, a new electronic device or a metal object is placed around the back or the like after the contactless card reader 2 is installed. However, the installation environment of the non-contact card reader 2 changes, which often leads to operational problems.

Therefore, an object of the present invention is to prevent a change in the resonance frequency of the coiled antenna due to a metal object around a place where the non-contact card reader is installed, and to obtain a stable operation of the non-contact card reader. It reduces the effects of leakage noise from other electronic devices or wires, prevents the effects of other harmonics on other electronic devices, and prevents card data from being read from the back of the contactless card reader. An object of the present invention is to provide a contactless card reader with few restrictions when constructing an access control system using a contactless card.

[0034]

According to the present invention, there is provided a contactless card reader for reading the card data as read data from a contactless card storing card data, the electromagnetic wave having a predetermined frequency. To the contactless card, the contactless card receives the electromagnetic wave, modulates the electromagnetic wave into a modulated wave with the card data, and emits the modulated wave to the contactless card reader. In the contactless card reader that receives the modulated wave by the coiled antenna and demodulates the card data as the read data from the modulated wave, the coiled antenna is connected to the coiled antenna. Together with a capacitance element forming an LC resonant circuit having a resonant frequency equal to a preselected frequency And a back side metal member disposed on the back side of the coiled antenna and spaced apart from the back side, the back side metal member being emitted to the back side of the coiled antenna. The function of blocking the emission of the electromagnetic wave to the rear of the back side metal member, and the eddy current generated in the back side metal member when blocking the electromagnetic wave, the resonance frequency of the LC resonance circuit A contactless card reader having a function of shifting from the preselected frequency so as to be equal to the predetermined frequency is obtained.

[0035]

Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a contactless card reader 2 'according to a first embodiment of the present invention, like the contactless card reader 2 of FIG. From FIG. 3), the card data is read as read data. This non-contact card reader 2 '
Is provided with a coiled antenna 4 for emitting an electromagnetic wave having a predetermined frequency to the non-contact card as shown in FIGS. The contactless card 1 (FIG. 3) receives the electromagnetic wave, modulates the electromagnetic wave into a modulated wave with the card data, and emits the modulated wave to the contactless card reader 2 '. The non-contact card reader 2'receives this modulated wave at the coiled antenna 4, and demodulates the card data from this modulated wave as read data.

In FIG. 1, a contactless card reader 2 '.
Has a capacitance element (not shown in FIG. 1) made up of capacitors (61 and 62 in FIG. 6) connected in parallel to the coiled antenna 4. The capacitance element, together with the coiled antenna 4, constitutes an LC resonant circuit having a resonant frequency equal to a preselected frequency.
This non-contact card reader 2'has a case 10 for accommodating the above-mentioned coil antenna 4 and an electronic circuit 9 including an oscillation amplification unit (3 in FIG. 3) and a card data demodulation circuit (5 in FIG. 3). Have. This case 10 corresponds to case 1 in FIG.
As in the case of No. 0, it has a waterproof structure to withstand outdoor use, and electric wires required for power supply, signal output, and the like are drawn out from a waterproof structure outlet (not shown).

In FIG. 1, the contactless card reader 2
The ′ further has a metal plate 11 arranged inside the case 10 on the back side of the coiled antenna 4 with a space between the back side and the back side. The metal plate 11 is arranged on the back side of the electronic circuit 9. This metal plate 11 is used for the coiled antenna 4
The electromagnetic wave emitted to the back side of the electromagnetic wave is shielded from being emitted to the rear side of the metal plate 11, and an eddy current generated in the metal plate 11 when shielding the electromagnetic wave causes the resonance frequency of the LC resonance circuit. With the function of shifting from the preselected frequency to be equal to the predetermined frequency.

As described above, the coiled antenna 4 is placed on the inner front surface (front surface) of the contactless card reader 2'in order to efficiently read the card data, as in the contactless card reader 2 of FIG. However, the contactless card reader 2'is adjusted so that the contactless card reader 2'resonates at the frequency used by the contactless card reader 2'with the metal plate 11 attached.

The coiled antenna 4 has an 8-shaped directional characteristic as shown in FIG. 7, and a part of the electromagnetic wave emitted from the coiled antenna 4 is also emitted to the back side of the coiled antenna 4. Since it is blocked by the metal plate 11, it is not discharged to the back surface of the non-contact card reader 2 ′, and even if the non-contact card approaches the back surface of the non-contact card reader 2 ′, the non-contact card reader 2 ′ is erroneously detected. It never reads the card data.

Further, since electromagnetic waves are not emitted to the back surface of the non-contact card reader 2 ', even if there is a metal object on the back surface of the non-contact card reader 2', resonance as in the conventional non-contact card reader 2 occurs. It goes without saying that the frequency does not change and the operation of the contactless card reader 2'is not affected.

The power consumption of the contactless card reader 2'in FIG. 1 is slightly increased by the eddy current generated in the metal plate 11, but it is around the contactless card reader 2 in FIG. It is much smaller than when there is a metal object (that is, when the resonance frequency has moved from the used frequency and the impedance of the coiled antenna 4 has decreased).

In addition, since the change in power consumption due to the situation around the non-contact card reader 2'of FIG. 1 (particularly the back side) is small, the system design is rather easy.

Referring to FIG. 2, a contactless card reader 2 "according to a second embodiment of the present invention is similar to contactless card reader 2'of FIG. 1 except for the following. In the non-contact card reader 2 ", the metal plate 1
1 is arranged on the back side of the coiled antenna 4 inside the case 10 and on the front side of the electronic circuit 9. In the contactless card reader 2 ″ of FIG. 2, the coiled antenna 4 and the metal plate 1 are used.
1 is closer to the contactless card reader 2'of FIG. 1, the loss due to the eddy current generated in the metal plate 11 is relatively large, but the coiled antenna 4 and the metal plate 11 are the same. Since it is housed in the case 10, the effect of facilitating the adjustment of the resonance frequency of the resonance circuit is obtained, and at the same time, when the electronic circuit 9 includes a CPU or a circuit that uses a clock, the coiled antenna 4 It can also have an effect of blocking the influence of mutual induction between the electronic circuit 9 and the electronic circuit 9.

Needless to say, if the metal plate 11 is connected to the ground potential of the electronic circuit 9 in FIGS. 1 and 2, it will be more efficient.

Further, in FIGS. 1 and 2, the metal plate 11 is provided only on the back side of the coiled antenna 4,
Another metal plate may be further arranged on the side of the peripheral surface of the coiled antenna 4 (the cylindrical surface of the coiled antenna 4 in FIGS. 4 and 5) with a space provided therebetween. In this case, another metal plate is electrically connected to the metal plate 11. In FIGS. 1 and 2, another metal plate electrically connected to the metal plate 11 is provided on the back surface of the non-contact card reader 2 ′ or 2 ″ or electrically connected to the metal plate 11. It is a matter of course that the electronic circuit 9 may be covered with another metal plate as shown in Fig. 1. In Fig. 1 and Fig. 2, the metal plate 11 is used. The same effect can be obtained by using the above metal member.

[0047]

As described above, according to the present invention, not only is the structure simple and is not easily affected by the installation environment,
We can prevent reading of unnecessary card data from the back,
It is possible to configure a non-contact card reader having a wide range of use that has little influence on other electronic devices.

[Brief description of drawings]

FIG. 1 is a sectional view of a contactless card reader according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a contactless card reader according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a contactless card and an electrical configuration of a main part of a conventional contactless card reader.

FIG. 4 is a front view of the coiled antenna of FIG.

FIG. 5 is a side view of the coil antenna of FIG. 3;

FIG. 6 is a diagram showing a circuit around a coiled antenna of the contactless card reader of FIG. 3;

FIG. 7 is a diagram for explaining the directional pattern of the figure eight of the coiled antenna of FIGS. 4 and 5;

FIG. 8 is a sectional view of a conventional contactless card reader.

[Explanation of symbols]

 1 Non-contact card 2 Non-contact card reader 2'Non-contact card reader 2 "Non-contact card reader 3 Oscillation amplification section 4 Coil antenna 5 Card data demodulation circuit 61 Capacitor 62 Capacitor 7 Final stage of drive circuit (transistor) 9 Electronics Circuit 10 Case 11 Metal plate

Claims (3)

[Claims] 1. A non-contact card reader for reading the card data as read data from a non-contact card storing card data, the coil shape emitting an electromagnetic wave having a predetermined frequency to the non-contact card. The contactless card is provided with an antenna, receives the electromagnetic wave, modulates the electromagnetic wave into a modulated wave with the card data, and emits the modulated wave to the contactless card reader. In a non-contact card reader that receives by a coiled antenna and demodulates the card data as the read data from this modulated wave, it is connected to the coiled antenna and, together with this coiled antenna, a resonance equal to a preselected frequency. A capacitance element forming an LC resonance circuit having a frequency;
A back side metal member disposed on the back side of the coiled antenna and spaced apart from the back side, the back side metal member being emitted to the back side of the coiled antenna. The resonance frequency of the LC resonance circuit is set in advance by the function of blocking the emission of electromagnetic waves rearward of the back side metal member and the eddy current generated in the back side metal member when blocking the electromagnetic waves. A non-contact card reader having a function of shifting from the preselected frequency so as to be equal to a predetermined frequency. 2. The non-contact card reader according to claim 1, wherein the back side metal member is connected to a ground potential. 3. A peripheral metal member disposed on the peripheral surface of the coiled antenna with a space between the coil antenna and the peripheral surface, wherein the peripheral metal member is disposed on the rear surface side. The non-contact card reader according to claim 1, wherein the non-contact card reader is electrically connected to a metal member.