JP2626882B2 - Contactless card reader - Google Patents

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 A personal recognition system using a contactless card has the following features. (1) The security performance of personal data stored in the contactless card is high. (2) Unlike a magnetic stripe card, there is no need to insert a card into a card reader when writing and reading card data, which is excellent in convenience. (3) Since it is excellent in waterproof performance, it is hardly affected by the external environment such as rain.

[0003] Compared with a contact-type card represented by a magnetic stripe card, for example, it has many advantages and is increasingly used as a personal identification medium used in an access control system for buildings and the like.

In particular, in a system in which a non-contact card is attached to a chest or the like also as a name tag or an identification card, an electric lock of the door is unlocked just by approaching a non-contact card reader installed in front of the door, and the door is unlocked. The point that can be opened is evaluated.

[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.

Furthermore, 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 on the front (front) side but also on the back (rear) side. The card-shaped directional characteristic (described later) makes it possible to read card data from the back of the contactless card reader. To prevent this, a metal wall is attached to the back of the contactless card reader. In some cases, shielding by a plate is performed (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 non-contact card reader for a battery-less non-contact card, which uses the latter long-wave or medium-wave electromagnetic waves for data exchange.

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 non-contact card 1 transmits a modulated wave obtained by modulating an electromagnetic wave with card data (personal identification data) to the non-contact 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 as an electromagnetic wave having a predetermined frequency within 1 Hz and receives an electromagnetic wave (ie, a modulated wave) modulated with card data (personal identification data) from the non-contact card 1; 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.

The actual non-contact card reader 2 includes a data comparison section for preventing the read guard data from becoming erroneous data due to mixed noise and the like, and a data comparison section between the card data and a higher-level controller or computer. A communication control unit, a power supply unit, and a control unit such as an electric lock may be included in some cases.

The modulation scheme of the card data includes 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.

Many non-contact card readers 2 perform intermittent operation at all times in order to reduce power consumption, but the cycle of intermittent operation is such that an individual holding the non-contact card 1 approaches the non-contact 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 coil-shaped antenna is a coil having a diameter of several cm to several tens cm, and its diameter is selected according to 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 denotes a final stage (transistor) of a drive circuit for driving an LC resonance circuit including the coil 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 figure-shaped directional characteristic 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 example of an actual arrangement of the conventional contactless 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).
And the like, and a case 10 for accommodating 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 with reference to FIG. 8, the coiled antenna 4 is placed on the inside front surface of the non-contact card reader 2 in order to read the card data efficiently. As shown in FIG. 7, the antenna 4 has an 8-shaped directional characteristic, so that a part of the electromagnetic wave emitted from the coiled antenna 4 passes through the electronic circuit 9 and the back of the non-contact card reader 2. When the non-contact card 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 the card data, the shape of the non-contact card reader 2 may be made thick so that the electromagnetic waves are not emitted to the back side of the non-contact card reader 2. Since the non-contact card reader 2 is often embedded and mounted on a wall, it is desirable that the thickness of the non-contact card reader 2 be as thin as possible. By increasing the thickness of the non-contact card reader 2, the emission of electromagnetic waves to the rear side is prevented. That is not realistic.

In order to prevent the card data from being read from the back side 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 is generated on the metal plate by the electromagnetic wave of the coiled antenna 4, and the inductance of the coiled antenna 4 is reduced accordingly, and the coiled antenna 4 is connected to the capacitance element (the capacitors 61 and 62 in FIG. 6). ) Changes the resonance frequency of the LC resonance circuit.

Even when the back wall of the non-contact card reader 2 is not shielded by a metal plate, the coiled antenna 4 is naturally affected by the metal around the non-contact 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 configured as described above 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 improve the efficiency of communication with the non-contact card 1, the non-contact card reader 2 is used in which a capacitance element including the capacitors 61 and 62 of FIG. 6 is connected in parallel with the coil antenna 4 to form an LC resonance circuit. This improves the efficiency of communication with the card.

Accordingly, the non-contact card reader 2 is used to prevent the reinforcement of concrete around the back side and the like, the wires used for other electronic devices, and the emission of electromagnetic waves to the back side of the coiled antenna 4. When installed in an environment where there is 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 communication of the present invention, the efficiency of transmission and reception with the non-contact card 1 is reduced, and the reading distance of the non-contact card reader 2 is remarkably shortened, but also the coiled antenna Inconveniences such as an increase in power consumption due to a decrease in the impedance of No. 4 have occurred.

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 coil-shaped antenna for emitting an electromagnetic wave having a predetermined frequency to a contactless card storing card data. Receiving the electromagnetic wave, modulating the electromagnetic wave into a modulated wave with the card data, and emitting the modulated wave to the non-contact card reader; receiving the modulated wave with the coiled antenna; In a non-contact card reader for demodulating the card data as read data from a wave, a capacitance element connected to the coil antenna and constituting an LC resonance circuit having a resonance frequency equal to a preselected frequency together with the coil antenna. And a back-side metal member provided on the back side of the coiled antenna at a distance from the back side, The back side metal member has a function of shielding the electromagnetic wave emitted to the back side of the coiled antenna from being emitted backward from the back side metal member, and a function of shielding the electromagnetic wave emitted from the back side when shielding the electromagnetic wave. A function of shifting the resonance frequency of the LC resonance circuit from the preselected frequency by a frequency determined by the distance due to an eddy current generated in the metal member is provided between the coil-shaped antenna and the back side metal member. A distance adjusting device that adjusts the distance by relatively changing the positions of the coiled antenna and the rear-side metal member, and further includes a distance adjusting device that adjusts the distance between the coiled antenna and the rear surface by the distance adjusting device. The distance between the side metal member is adjusted so that the resonance frequency of the LC resonance circuit is equal to the predetermined frequency. Contactless card reader, wherein the door 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 contactless card reader 2 'receives the modulated wave by the coil antenna 4, and demodulates card data from the modulated wave as read data.

In FIG. 1, a non-contact card reader 2 '
Has a capacitance element (not shown in FIG. 1) composed of capacitors (61 and 62 in FIG. 6) connected in parallel to the coiled antenna 4. The capacitance element, together with the coil antenna 4, forms an LC resonance circuit having a resonance frequency equal to a preselected frequency.
This non-contact card reader 2 ′ has a case 10 for housing the above-described coiled antenna 4 and an electronic circuit 9 including an oscillation amplifier (3 in FIG. 3) and a card data demodulation circuit (5 in FIG. 3). Having. 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
'Further has a metal plate 11 disposed inside the case 10 on the back side of the coiled antenna 4 at a distance from the back side. This metal plate 11 is provided on the back side of the electronic circuit 9. This metal plate 11 is used for the coiled antenna 4
The function of blocking the electromagnetic wave emitted to the rear side of the LC plate from being emitted behind the metal plate 11 and the eddy current generated in the metal plate 11 when shielding the electromagnetic wave cause the resonance frequency of the LC resonance circuit to be reduced. Is shifted from the preselected frequency by a frequency determined by the distance.

The contactless card reader 2 'further adjusts the distance between the coiled antenna 4 and the metal plate 11 by relatively changing the positions of the coiled antenna 4 and the metal plate 11. The distance adjusting device 12 is provided.
The distance adjusting device 12 adjusts the distance between the coil antenna 4 and the metal plate 11 such that the resonance frequency of the LC resonance circuit becomes equal to the predetermined frequency.

The distance adjusting device 12 includes the coiled antenna 4
A pair of adjusting screws 13 made of an electrical insulator for changing the distance between the metal plate 11 and the coil antenna 4 and the metal plate 11 at both ends so as to cover the pair of adjusting screws 13. And a pair of springs 14. When the pair of adjusting screws 13 are tightened, the coiled antenna 4 approaches the metal plate 11 and the eddy current generated in the metal plate 11 by the electromagnetic wave transmitted from the coiled antenna 4 increases. Is reduced, and the resonance frequency moves to a higher one. When the pair of adjustment screws 13 is turned in the loosening direction, the pair of springs 14
The coiled antenna 4 is separated from the metal plate 11 by the electromagnetic wave transmitted from the coiled antenna 4 by the
The eddy current generated in the coil antenna 4
The apparent inductance increases and the resonance frequency moves to lower.

In FIG. 1, the coiled antenna 4 and the metal plate 1
Although the fixing method of the first case 10 to the case 10 is not shown, the effect of the present invention is caused by a change in the relative distance between the coiled antenna 4 and the metal plate 11, so that
The coiled antenna 4 is fixed to the case 10 and the metal plate 11
Is variable, the effect remains unchanged even if the metal plate 11 is fixed to the case 10 and the coil antenna 4 is variable. In FIG. 1, the distance is adjusted by the coiled antenna 4.
The distance is adjusted from the back side of the metal plate 11 as a matter of course.

As described above, the coiled antenna 4 is placed on the front surface inside the non-contact card reader 2 'in order to read the card data efficiently, similarly to the non-contact card reader 2 of FIG. However, in the non-contact card reader 2 ′, the adjustment is performed by the distance adjustment device 12 so that the non-contact card reader 2 ′ resonates at the frequency used by the non-contact card reader 2 ′ with the metal plate 11 mounted.

The coiled antenna 4 has a directional pattern of eight characters 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. , Is not discharged to the back of the non-contact card reader 2 'because the metal plate 11 blocks the non-contact card reader 2'. The card data will not be read.

Further, since the electromagnetic waves are not emitted to the back of the non-contact card reader 2 ', even if there is a metal object on the back of the non-contact card reader 2', resonance as in the conventional non-contact card reader 2 is performed. Of course, the frequency does not change and does not affect the operation of the contactless card reader 2 '.

The power consumption of the non-contact card reader 2 'in FIG. 1 slightly increases due to the eddy current generated in the metal plate 11. However, the power consumption near the non-contact card reader 2 in FIG. The state is substantially smaller than the state in which there is a metal object (that is, the state in which the resonance frequency has shifted from the operating 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 '(particularly on the back side) in FIG. 1 is reduced, the design of the system is rather easy.

In general, the adjustment of the resonance frequency of the coiled antenna 4 can be performed by making the capacitance (capacitance) of the capacitors 61 and 62 or the inductance of the coiled antenna 4 variable. In general wireless devices and the like, adjustment of the resonance frequency of the resonance circuit is often performed using a variable capacitor, a variable coil, or the like, and this is a simple method at a low voltage signal level.

However, in the coiled antenna 4 used in the contactless card reader, it is necessary to supply sufficient power to the coiled antenna 4 in order to increase the reading distance of the card data stored in the contactless card to some extent. As a result, the voltage applied to both ends of the coiled antenna 4 is often as high as 100 V to several 100 V, and it has been relatively difficult to take these simple methods.

Therefore, conventionally, several small-capacity capacitors are connected in parallel to the resonance capacitor of the coil-shaped antenna 4, and the total capacitance of the resonance capacitors is adjusted according to the number thereof, or a small piece of coil ferrite is attached. Thus, the resonance frequency was adjusted.

However, these methods have problems in that the adjustment is stepwise, and it is difficult to finely adjust the resonance frequency, and it takes time to adjust.

According to the non-contact card reader 2 'of FIG.
A contactless card reader which is not affected by the installation environment and whose resonance frequency can be easily adjusted is obtained.

Referring to FIG. 2, a contactless card reader 2 ″ according to a second embodiment of the present invention is similar to the contactless card reader 2 ′ of FIG. 1 except for the following: In the non-contact card reader 2 ", the metal plate 1
1 is located 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 non-contact card reader 2 ″ of FIG. 2, the distance between the coiled antenna 4 and the metal plate 11 is shorter than that of the non-contact card reader 2 ′ of FIG. On the other hand, since the coiled antenna 4 and the metal plate 11 are housed in the same case 10, the effect of easily adjusting the resonance frequency of the resonance circuit is obtained.
At the same time, when the electronic circuit 9 includes a CPU or a circuit using a clock, the effect of blocking mutual influence between the coil antenna 4 and the electronic circuit 9 can be obtained.

In FIGS. 1 and 2, if the metal plate 11 is connected to the ground potential of the electronic circuit 9, it goes without saying that it is more efficient.

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) at a distance from the peripheral surface. 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.

[0055]

As described above, according to the present invention, not only is the structure simple and not easily affected by the installation environment,
Unnecessary reading of card data from the back can be prevented,
A non-contact card reader having a wide range of use and having a small influence on other electronic devices and easily adjusting the resonance frequency can be configured.

[Brief description of the 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 non-contact card and an electrical configuration of a main part of a conventional non-contact card reader.

FIG. 4 is a front view of the coil antenna of FIG. 3;

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]

 DESCRIPTION OF SYMBOLS 1 Contactless card 2 Contactless card reader 2 'Contactless card reader 2 "Contactless card reader 3 Oscillation amplification part 4 Coiled antenna 5 Card data demodulation circuit 61 Capacitor 62 Capacitor 7 Final stage part (transistor) of drive circuit 9 Electronics Circuit 10 Case 11 Metal plate 12 Distance adjusting device 13 Adjusting screw 14 Spring

Claims (3)

(57) [Claims] 1. A non-contact antenna for emitting an electromagnetic wave having a predetermined frequency to a non-contact card storing card data, wherein the non-contact card receives the electromagnetic wave and transmits the electromagnetic wave to the non-contact card. The card data is modulated into a modulated wave, and the modulated wave is emitted to the non-contact card reader. The modulated wave is received by the coil antenna, and the card data is read from the modulated wave and demodulated as data. A non-contact card reader, connected to the coiled antenna, and together with the coiled antenna, a capacitance element forming an LC resonance circuit having a resonance frequency equal to a preselected frequency; and a back side of the coiled antenna. And a back-side metal member provided at a distance from the back surface. The function of shielding the electromagnetic wave emitted to the back side of the ill-shaped antenna from being emitted backward from the back side metal member, and an eddy current generated in the back side metal member when shielding this electromagnetic wave, A function of shifting the resonance frequency of the LC resonance circuit from the pre-selected frequency by a frequency determined by the distance, wherein the distance between the coil-shaped antenna and the rear-side metal member is determined by the coil-shaped A distance adjusting device for adjusting the relative position of the antenna and the rear-side metal member by relatively changing the position between the coiled antenna and the rear-side metal member by the distance adjusting device; A contactless card, wherein the distance is adjusted so that the resonance frequency of the LC resonance circuit is equal to the predetermined frequency. Over da. 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.