JP2001094485A - Contactless communication unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a magnetic field with a stable level independently of dispersion in am amplification factor of amplifiers and a difference from an installation environment or the like without the need for adjustment of the resistance of variable resistors different from a conventional communication unit in a contactless communication unit such as a reader/writer that makes contactless communication with a mobile information communication body such as an IC card by generating the magnetic field from a loop antenna. SOLUTION: In the case of contactlessly transmitting power and information from, e.g. the reader/writer to the IC card by generating the magnetic field from the loop antenna 7, a pickup coil 9 detects the magnetic field generated from the loop antenna 7 and an adjustment means consisting of a control section 12 and a power control circuit 3 or the like adjusts a level of the magnetic field generated from the lop antenna 7 to the prescribed level based on the level of the magnetic field detected by the pickup coil 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact communication device such as a reader / writer device which generates a magnetic field from a loop antenna and transmits power and information to a mobile information communication device such as an IC card in a non-contact manner. In particular, the present invention relates to a non-contact communication device that generates a magnetic field at a stable level regardless of an installation environment or the like.

[0002]

2. Description of the Related Art For example, an IC card formed by embedding a microcomputer chip and a memory chip on a card substrate having a size similar to that of a credit card or the like has been put to practical use in various fields such as finance, distribution, transportation, and medicine. Is planned. In an IC card system using such an IC card, for example, power is transmitted from a reader / writer device to the IC card, and information such as a control code and data is communicated between the reader / writer device and the IC card. Has been done. In power transmission and information communication between a reader / writer device and an IC card, in addition to a contact system in which terminals are brought into contact with each other, a non-contact system in which, for example, electromagnetic coupling is used is also adopted.

FIG. 5 shows an example of the configuration of a reader / writer device provided in an IC card system (non-contact IC card system) employing such a non-contact method. For example, when power is transmitted from the reader / writer device shown in FIG. 1 to an IC card (non-contact IC card) in a non-contact manner and information (for example, transmission data) is transmitted in a non-contact manner, The modulator 42 modulates the carrier signal output from the oscillator 41 with data (transmission data) from the controller 49, and the amplifier 44 amplifies the modulated signal passed through the variable resistor 43, and combines the amplified signal. The signal is transmitted from the loop antenna 47 via the device 45 and the impedance conversion circuit 46. The loop antenna 47 is composed of, for example, a coil wound in a rectangular shape or the like, and the above-described amplified signal is transmitted to the outside world by a magnetic field radiated from the coil.

On the other hand, an IC card is provided with, for example, a loop antenna similar to the above-described loop antenna 47. The IC card uses an electromagnetic coupling between the loop antenna and the loop antenna 47 of the reader / writer device. The amplified signal is received. Also, for example, no power supply is provided inside the IC card, and the IC card performs various operations by using power extracted from the received amplified signal as operating power, and includes, for example, the power contained in the amplified signal. Extract the data that exists. The power is extracted from the carrier component of the amplified signal, and the data is extracted from the modulated component of the amplified signal.

Further, for example, when an information signal transmitted from a loop antenna of an IC card in a non-contact manner is received by a loop antenna 47 of the reader / writer device shown in FIG. Is input to the demodulation unit 48 via the impedance conversion circuit 46 and the coupler 45, and the demodulation unit 48 demodulates data (reception data) from the information signal and outputs the data to the control unit 49. Note that information communication from the IC card to the reader / writer device is also performed using electromagnetic coupling between both loop antennas in the same manner as described above.

In the above-described reader / writer device, for example, the amplification factor of the amplifier 44 may be different for each reader / writer device depending on, for example, variations in the quality of components. For this reason, it is necessary to compensate for such variation in the amplification factor. Specifically, in the related art,
For example, when shipping the reader / writer device, the resistance value of the variable resistor 43 is adjusted for each reader / writer device, and the level of the power output from the loop antenna 47 (the level of the magnetic field generated from the loop antenna 47) is set to a desired value. Adjustments to the level were done.

[0007]

However, in the above-described reader / writer device, as described above, for example, at the time of shipment, the resistance value of the variable resistor 43 is adjusted for each reader / writer device and the Since it was necessary to adjust the level of the generated magnetic field to a predetermined level, there was a problem that the number of man-hours required for the operation increased and it took time. In addition, even if such adjustment at the time of shipment is performed, since the reader / writer device is generally installed and used in various places after shipment, for example, the power supply voltage is set according to the installation location of the reader / writer device. Of the magnetic field generated from the loop antenna 47 varies depending on such a difference in the installation environment. .

The present invention has been made to solve such a conventional problem, and generates electric field from a loop antenna to transmit electric power and information to a mobile information communication body such as an IC card in a non-contact manner. In doing so, it is an object of the present invention to provide a non-contact communication device such as a reader / writer device capable of generating a magnetic field at a stable level regardless of, for example, a variation in amplification factor of an amplifier or a difference in an installation environment.

[0009]

Means for Solving the Problems In order to achieve the above object, a non-contact communication device according to the present invention, when generating a magnetic field from a loop antenna and communicating with a mobile information communication body in a non-contact manner, is as follows. To adjust the level of the magnetic field generated from the loop antenna. That is, the pickup coil detects a magnetic field generated from the loop antenna, and the adjusting unit adjusts the level of the magnetic field generated from the loop antenna to a predetermined level based on the level of the magnetic field detected by the pickup coil.

Therefore, since the level of the magnetic field generated from the loop antenna is adjusted by feedback based on the level of the magnetic field detected by the pickup coil, for example, the resistance value of the variable resistor is adjusted at the time of shipment as in the prior art. The variation in the amplification factor of the amplifier can be compensated for without performing the operation, and a magnetic field of a stable level can be generated regardless of, for example, a difference in installation environment.

In the non-contact communication from the non-contact communication device to the mobile information communication body according to the present invention, the non-contact communication device always superimposes power and information with a magnetic field generated from a loop antenna to perform the mobile information communication. A configuration capable of transmitting to the body may not be used. Specifically, for example, when there is no need to transmit information from the non-contact communication device to the mobile information communication body, a configuration in which the non-contact communication device transmits only power using the magnetic field may be used, For example, when the mobile information communication body is provided with a power source such as a battery or a battery, a configuration in which the non-contact communication device transmits only information using the magnetic field may be used.

Further, the non-contact communication device according to the present invention does not necessarily need to be a device for two-way communication of information with a mobile information communication device like a reader / writer device, but for example, a mobile device like a reader device. One-way communication such as receiving information transmitted from an information communication body may be performed. Note that the configuration of adjusting the level of the magnetic field generated from the loop antenna by feedback as in the present invention is very effective when applied to a non-contact communication device used in various environments.

The mobile information communication body referred to in the present invention is not limited to an IC card, but may be, for example, a name plate attached to a person, a tag attached to a product or article, or an identification attached to livestock. A plate for delivery, a delivery destination plate attached to a parcel delivery baggage or a container, or the like may be used. Further, as described above, it is not always necessary to use a configuration in which the mobile information communication body is not provided with a power supply,
For example, a configuration in which a power supply is provided in the mobile information communication body can be used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to the drawings. In this example, a case is shown in which the non-contact communication device according to the present invention is applied to a reader / writer device of a non-contact IC card system. In this example, the non-contact IC
A case is shown in which the IC card of the card system is not provided with a power source, and power and information are transmitted from the reader / writer device to the IC card, while information is transmitted from the IC card to the reader / writer device.

FIG. 1 shows an example of a reader / writer device to which a non-contact communication device according to the present invention is applied. The reader / writer device includes an oscillator 1 for oscillating a carrier signal.
A modulator 2 for modulating a carrier signal, a power control circuit 3 for controlling the power level of the signal, an amplifier 4 for amplifying the signal, and a coupler 5 for enabling one loop antenna 7 to be used for transmission and reception. An impedance conversion circuit 6 for converting impedance, a loop antenna 7 for generating a magnetic field, a demodulation unit 8 for demodulating a received signal, a pickup coil 9 for detecting a magnetic field, and a rectifier 10 for rectifying an alternating current to a direct current. A to convert analog signal to digital signal
A / D converter 11 and a control unit 12 for controlling the processing units 1 to 11 are provided.

The oscillator 1 has a function of oscillating a carrier signal and outputting the carrier signal to the modulation section 2. The modulation unit 2 has a function of modulating a carrier signal input from the oscillator 1 with data (transmission data) input from a control unit 12 described below. For example, data to be transmitted is input from the control unit 12. If the data is modulated, the carrier signal is modulated by the data and the modulated signal is output to the power control circuit 3. On the other hand, if the data to be transmitted is not input from the control unit 12, the carrier signal is modulated. It outputs to the power control circuit 3 without any processing.

The power control circuit 3 is controlled by a control signal input from a control unit 12 described later, controls the power level of the signal input from the modulation unit 2, and outputs the signal after the control to the amplifier 4. Has a function. Here, FIG.
Shows a specific configuration example of the power control circuit 3 of the present example. The power control circuit 3 of the present example has an input terminal 21 connected to the modulation unit 2 and an output terminal connected to the amplifier 4. 22 are provided with four path switching units (first to fourth path switching units).

As shown in FIG. 1, each path switching unit includes an attenuator 23 for attenuating the signal power by a predetermined level.
26 to the attenuation path (upper path in the figure);
A path that does not include such an attenuator (a lower path in the figure) and a path that passes a signal input from the modulation unit 2 and output to the amplifier 4 are provided in one of these two paths. It comprises switches SW1 to SW4 for switching.

In this embodiment, the attenuator 23 provided in the first path switching unit is an attenuator (8 dBATT) for attenuating the signal power by 8 dB, and the attenuator provided in the second path switching unit. Reference numeral 24 denotes an attenuator (4 dBATT) for attenuating the signal power by 4 dB. An attenuator 25 provided in the third path switching unit is an attenuator (2 dBATT) for attenuating the signal power by 2 dB. The attenuator 26 provided in the switching unit is an attenuator (1 dBATT) that attenuates the signal power by 1 dB.

Further, the four switches SW1 to S
W4 has a function of switching two paths provided in each path switching unit according to a control signal (for example, a binary signal) input from the control unit 12 described later. In this example, there are a total of 16 patterns of path switching by these four switches SW1 to SW4, and the power control circuit 3 as a whole uses the 16 patterns to attenuate the signal power by 0 dB (that is, the signal power). A path that does not attenuate), a path that attenuates 1 dB,
A path for attenuating 2 dB,..., A path for attenuating 14 dB, and a path for attenuating 15 dB can be switched.

The amplifier 4 has a function of amplifying a signal input from the power control circuit 3 and outputting the amplified signal to the coupler 5.
The coupler 5 has a function of outputting an amplified signal input from the amplifier 4 to the impedance conversion circuit 6 and outputting a received signal input from the impedance conversion circuit 6 to the demodulation unit 8. The impedance conversion circuit 6 includes the coupler 5
Has a function of impedance-converting the amplified signal input from the antenna and outputting the amplified signal to the loop antenna 7 and impedance-converting the signal received by the loop antenna 7 and outputting the signal to the coupler 5.

The loop antenna 7 is composed of, for example, a coil wound in a rectangular shape or the like, and radiates a signal input from the impedance conversion circuit 6 as a magnetic field from the coil, thereby making the signal non-contact with the IC card. And has a function of receiving an information signal transmitted in a non-contact manner by a magnetic field generated from a loop antenna provided in the IC card and outputting the received signal to the impedance conversion circuit 6.

Here, FIG. 3 shows a specific preferred configuration example of the above-described loop antenna 7 and a pickup coil 9 described later. As shown in FIG. For example, 200mm side and 100m
It is composed of a coil wound in a rectangle consisting of m sides.

Non-contact communication of power and information between the reader / writer device and the IC card is performed by electromagnetic coupling between the loop antenna 7 provided in the reader / writer device and the loop antenna provided in the IC card. This is performed using Power transmission from the reader / writer device to the IC card is performed using a carrier component of a signal transmitted from the loop antenna 7 of the reader / writer device, and information transmission is performed using a modulation component of the signal.

The demodulation unit 8 has a function of demodulating data (reception data) from the reception signal input from the coupler 5 and outputting the data to the control unit 12. The pickup coil 9 is formed of, for example, a coil wound in a circular shape, and has a function of detecting a magnetic field generated from the loop antenna 7.

Specifically, as shown in FIG.
The pickup coil 9 of this example has a diameter of 10 mm (φ10
mm), the center axis of the coil is aligned with the center axis of the coil forming the loop antenna 7, and the two coils are parallel to each other. Are arranged as follows. Then, an AC voltage (or AC current) is generated in the pickup coil 9 by electromagnetic induction according to a magnetic field generated from the loop antenna 7, and the pickup coil 9 of this example is generated from the loop antenna 7 in the form of the AC voltage. Detect the magnetic field.

The rectifier 10 has a function of converting the magnetic field detected by the pickup coil 9, that is, the AC voltage generated in the pickup coil 9 into a DC voltage, and outputting the DC voltage to the A / D converter 11. have. Specifically, as shown in FIG. 3, the rectifier 10 of the present embodiment includes, for example, four diodes 31 and the like, and the capacitor 3 shown in FIG.
2 corresponds to the rectified DC voltage.

The A / D converter 11 has a function of digitizing a DC voltage input as an analog signal from the rectifier 10, detecting a digital value Vdc of the DC voltage, and outputting the DC voltage value Vdc to the control unit 12. are doing.
The control unit 12 has, for example, a function of controlling the above-described processing units 1 to 11, and specifically, a function of outputting data (transmission data) to be transmitted to the IC card to the modulation unit 2, A function of analyzing data (received data) received from the IC card and input through the demodulation unit 8;
It has a function of controlling the power control circuit 3 with a control signal based on the DC voltage value Vdc input from the / D converter 11.

FIG. 4 shows the power level P (dBm) of the amplified signal output from the amplifier 4 and the DC voltage value Vdc (V) obtained from the magnetic field detected by the pickup coil 9. Is shown as an example. It should be noted that the graph shown in the figure is obtained by an experiment, and the horizontal axis indicates the power level P, and the vertical axis indicates the DC voltage value Vdc.

The control unit 12 of this embodiment stores the correspondence shown in FIG. 4 in the form of, for example, a data table. In this data table, a plurality of power levels P and a plurality of corresponding DC voltage values Vdc are stored. Are associated and held. Then, the control unit 12 of the present embodiment detects the power level P corresponding to the DC voltage value Vdc input from the A / D converter 11 by referring to the data table, and the power level P is set in advance, for example. The power control circuit 3 is controlled by the control signal so as to be adjusted to the predetermined level.

In this example, the control unit 12 controls the power control circuit 3 based on the DC voltage value Vdc input from the A / D converter 11 to change the level of the magnetic field generated from the loop antenna 7 to a predetermined level. Thus, the adjusting means for adjusting the level of the magnetic field generated from the loop antenna to a predetermined level based on the level of the magnetic field detected by the pickup coil according to the present invention is configured.

In this embodiment, the level of the magnetic field detected by the pickup coil 9 is set to the above-described DC voltage value Vd.
Detected in the form of c. Further, in this example, the level of the magnetic field generated from the loop antenna 7 is adjusted to a predetermined level by adjusting the power level P to a predetermined level.

When the level of the magnetic field generated from the loop antenna 7 is adjusted to a predetermined level, the accuracy of the adjustment may be, for example, the accuracy of the signal power attenuation process by the power control circuit 3 (in this example, at 1 dB intervals). Control can be performed) and the like may be set to a practically effective degree. For example, the predetermined level referred to in the present invention may have a certain width depending on the required accuracy of the adjustment. In this case, for example, the level of the magnetic field generated from the loop antenna 7 is not less than “H1” and not more than “H2” It can be adjusted to the level.

With the above configuration, in the reader / writer device of the present embodiment, when a magnetic field is generated from the loop antenna 7 and power and information are communicated without contact with the IC card,
The pickup coil 9 detects the magnetic field generated from the loop antenna 7, and the control unit 12 controls the power control circuit 3 based on the level of the magnetic field detected by the pickup coil 9, thereby detecting the magnetic field generated from the loop antenna 7. The level can be adjusted to a predetermined level.

Here, an example of a procedure of a process of adjusting the level of the magnetic field generated from the loop antenna 7 by the reader / writer device of the present embodiment will be described. First, in the reader / writer device,
For example, when the power is turned on, the control unit 12 controls the power control circuit 3 by a control signal, and the signal power attenuation amount (in the present example, the value of 0 dB to 15 dB can be taken as described above) in the entire power control circuit 3, for example. A predetermined attenuation (for example, 7 dB or the like) is set, and the loop antenna 7 is set in the set state.
Generates a magnetic field.

When a magnetic field is generated from the loop antenna 7 as described above, in the reader / writer device, an AC voltage is generated in the pickup coil 9 by electromagnetic induction in accordance with the magnetic field generated from the loop antenna 7, and the rectifier 10 generates the AC voltage. The A / D converter 11 converts the voltage into a DC voltage, and the A / D converter 11 digitizes the DC voltage to obtain the DC voltage value Vd.
c is output to the control unit 12.

Next, in the reader / writer device, the control unit 12
Refers to the data table described above, and A /
Based on the DC voltage value Vdc input from the D converter 11, it is determined whether the level of the magnetic field generated from the loop antenna 7 matches a predetermined level or the like. As a result of this determination, when the control unit 12 determines that the level of the magnetic field generated from the loop antenna 7 is smaller than a predetermined level, for example, the control unit 3
To reduce the amount of signal power attenuation in the entire power control circuit 3 (that is, increase the power level P), for example, while the level of the magnetic field generated from the loop antenna 7 becomes a predetermined level. If it is determined that the power level is larger, the power control circuit 3 is controlled by the control signal to increase the signal power attenuation in the entire power control circuit 3 (that is, the power level P is reduced).

When the control unit 12 controls the power control circuit 3 as described above, the level of the magnetic field generated from the loop antenna 7 changes so as to approach a predetermined level.
2 repeats the process of controlling the power control circuit 3 based on the level of the magnetic field detected by the pickup coil 9 as described above until the level of the magnetic field generated from the loop antenna 7 is adjusted to a predetermined level. Do. When the control unit 12 confirms that the level of the magnetic field generated from the loop antenna 7 has been adjusted to a predetermined level based on the DC voltage value Vdc input from the A / D converter 11, the control unit 12 ends the adjustment processing. I do.

In this embodiment, as a preferred embodiment, a configuration is shown in which the reader / writer device automatically adjusts the level of the magnetic field generated from the loop antenna 7 when the power of the reader / writer device is turned on. It is also possible to adopt a configuration in which the reader / writer device automatically performs the adjustment at regular intervals, or a configuration in which the reader / writer device automatically performs the adjustment in response to an instruction from the user, for example.

As described above, in the reader / writer of this embodiment, the level of the magnetic field generated from the loop antenna 7 can be automatically adjusted to a predetermined level based on the level of the magnetic field detected by the pickup coil 9. Because it is performed, for example, it is possible to compensate for the variation of the amplification factor of the amplifier even if the work of adjusting the resistance value of the variable resistor is not performed at the time of shipping as in the conventional case, Regardless, a stable level of magnetic field can be generated. For this reason, in the reader / writer device of this example, even when used in various environments, for example, power and information are output at a stable output level (for example, at a constant output level regardless of the installation environment and the like). ) It can be transmitted from the loop antenna to the IC card.

Here, the configuration of the non-contact communication device according to the present invention is not necessarily limited to the configuration of the reader / writer device shown in the above-described embodiment, but it is based on the level of the magnetic field detected by the pickup coil. Various configurations may be used as long as the level of the magnetic field generated from the loop antenna is adjusted. For example, the shape, size, and the like of the loop antenna and the pickup coil need not necessarily be those shown in the above embodiments, and various shapes and the like may be used to the extent that they are practically effective.

The process of adjusting the level of the magnetic field generated from the loop antenna by using the pickup coil by the non-contact communication device according to the present invention includes, for example, a process in which the processor executes a control program in a hardware resource including a processor and a memory. May be used, and each functional unit for executing the processing may be configured as an independent hardware circuit. In addition, the present invention can be understood as a computer-readable recording medium such as a floppy disk or a CD-ROM storing the above-mentioned control program. Thereby, the processing according to the present invention can be performed.

[0043]

As described above, according to the non-contact communication device according to the present invention, when a magnetic field is generated from the loop antenna to perform non-contact communication with the mobile information communication body, the loop antenna uses the pickup coil. Since the generated magnetic field is detected and the level of the magnetic field generated from the loop antenna is adjusted to a predetermined level based on the detected level of the magnetic field, for example, the resistance value of the variable resistor is set at the time of shipment as in the related art. Even if the adjustment operation is not performed, the variation in the amplification factor of the amplifier can be compensated, and a magnetic field of a stable level can be generated regardless of, for example, a difference in installation environment.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a reader / writer device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a specific configuration example of a power control circuit.

FIG. 3 is a diagram illustrating a specific configuration example of a loop antenna, a pickup coil, and a rectifier.

FIG. 4 is a diagram illustrating an example of a correspondence relationship between an output power level from an amplifier and a DC voltage value obtained from a magnetic field detected by a pickup coil.

FIG. 5 is a diagram illustrating a configuration example of a reader / writer device according to a conventional example.

[Explanation of symbols]

1. Oscillator, 2. Modulator, 3. Power control circuit, 4. Amplifier, 5. Coupler, 6. Impedance conversion circuit, 7. Loop antenna, 8. Demodulator, 9.・ Pickup coil, 10 ・ ・ Rectifier,
11 A / D converter, 12 Control unit, 21
..Input end, 22..output end, 23-26..attenuator, SW1-SW4..switch, 31..diode, 32..condenser,

Claims (1)

[Claims] A non-contact communication device that generates a magnetic field from a loop antenna and communicates with a mobile information communication body in a non-contact manner, wherein: a pickup coil for detecting a magnetic field generated from the loop antenna; Adjusting means for adjusting the level of the magnetic field generated from the loop antenna to a predetermined level based on the level.