JP2001007629A - Electronic device, information writer/reader and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in the reception sensitivity, when stacked IC cards are in use. SOLUTION: Interior angles θ of a loop antenna 1, whose elements are wound on a rectangle by 4 turns, are selected to be 90 deg.-α. The constant α is selected to be an arbitrary value which is other than zero. Thus, straight line parts L2, L6, L10 and L14 of upper sides of the rectangle becomes non-parallel, and the electromagnetic coupling of stacked IC cards can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device and an information writing / reading device and method, and more particularly to, for example, stacking a plurality of IC (Integrated Circuit) cards and writing or reading data without contact. In such a case, the present invention relates to an electronic device, an information writing / reading device, and a method for minimizing a decrease in reception efficiency.

[0002]

2. Description of the Related Art In recent years, non-contact IC cards have become widespread and have been introduced into common tickets for transportation such as subways, buses and ferries, or electronic money systems. Writing or reading of data to or from the IC card is performed in a non-contact manner based on the principle of electromagnetic induction.

That is, in a contactless IC card system,
Electromagnetic waves are emitted from a loop antenna built into a reader / writer in an IC card. The radiated electromagnetic waves are received by a loop antenna provided inside the IC card. Thus, communication is performed between the IC card and the reader / writer.

Further, in order to eliminate the need for maintenance of the IC card, the IC card is not provided with a battery, and obtains necessary power from received electromagnetic waves.
Therefore, the IC card needs to receive electromagnetic waves as efficiently as possible.

Generally, as shown in FIG. 1, a loop antenna 1 wound in two or more turns in a rectangular shape as large as possible is provided inside an IC card. The loop antenna 1 receives a signal by causing a resonance circuit to resonate at a carrier frequency (carrier frequency) of an electromagnetic wave radiated from a reader / writer.

[0006] Basically, an IC card is used by only one card, but there are cases where two IC cards are used in a state of being stacked. For example, if the user passes through a commuter pass section and gets off at a station other than the commuter pass section, the user must pay a commuter pass and an IO Card (trademark) (both are composed of IC cards) in order to settle for the crossing section. It is assumed that the leader)
Present to Writer. At this time, the reader / writer or the contactless IC card system to which it is connected recognizes the presented commuter pass section, calculates the distance of the overriding section, and furthermore, based on the Calculate the amount of money and execute a process such as performing the settlement with Iocard.

[0007] When one IC card is presented, of course,
Even when a plurality of IC cards are stacked, it is necessary to efficiently receive electromagnetic waves so that each IC card can perform a desired communication operation.

For example, as shown in FIG. 2, two IC cards each having the loop antenna 1 having the configuration shown in FIG.
When the two cards are overlapped so that both sides are completely overlapped when viewed from above (the two IC cards are overlapped so that one surface faces the back surface of the other). Case), loop antenna 1-1 of one IC card
Are linear conductors L1 to L9 constituting each side of the rectangle are the loop antenna 1- of the other IC card.
The two corresponding linear portions L11 to L19 respectively overlap. At this time, the resonance frequency of the loop antennas 1-1 and 1-2 and the resonance circuit is 1/2 (2) the resonance frequency of one loop antenna 1 (one IC card) ( 1 / √2).

That is, when IC cards are superimposed, coupling occurs between the respective resonance circuits. FIG. 3 shows a schematic equivalent circuit of the resonance circuit in this case. In this example, the loop antenna 1-1 forming the coil of the resonance circuit 13-1 of one of the IC cards includes the linear portions L1 to L4.
(Line portions L5 to L9 are omitted for simplicity)
, And the capacitor 12-1 is connected in parallel to the capacitor 12-1. Terminals 14-1A and 1 of resonance circuit 13-1
The equivalent resistance 11-1 is connected to 4-1B.

Similarly, the resonance circuit 13- of the other IC card
The loop antenna 1-2 constituting the two coils has linear portions L11 to L14 (linear portions L15 to L1).
9 is omitted), which includes a capacitor 12-2.
Are connected in parallel. Terminal 14 of resonance circuit 13-2
-2A and 14-2B are connected to an equivalent resistance 11-2.

The linear portions L1 to L of the loop antenna 1-1
Reference numeral 4 denotes coupling coefficients M1 to M4 having predetermined values, which are coupled to the linear portions L11 to L14 of the loop antenna 1-2, respectively.

As a result, the value of the inductance component L of the coils (the loop antennas 1-1 and 1-2) of the resonance circuits 13-1 and 13-2 is equal to that of the loop antennas 1-1 and 1-2.
This is equivalent to changing to a single thick conductor, and has the same value as a single case. On the other hand, the resonance circuit 13-
The values of the capacitance components C of the capacitors 12-1 and 12-2 of the capacitors 12-1 and 12-2 are the same.
2 is equivalent to the case of being connected in parallel, and the value (2C) is twice as large as the case of being connected alone. As a result, the resonance circuit 13-
The resonance frequencies of 1, 13-2 are as follows when one IC card is used.
1 / (2π√ (LC)), but when two sheets are stacked, 1 / (2π√ (L · (2C)) = (1 / √2) · 1
/ (2π√ (LC)).

That is, when IC cards are overlaid,
The resonance frequency of the resonance circuit of each IC card deviates from the carrier frequency of the electromagnetic wave by 1 / √2, and the reception efficiency decreases.

For example, as shown in FIG.
As shown in FIG. 5, the resonance frequency of the resonance circuit 13 of the loop antenna 1 and the capacitor 12 wound in four turns with a conductor width of 0.8 mm and a standard interval of 0.4 mm in a 7 mm rectangular shape is 17.5 MHz. , The reception sensitivity characteristic is as shown by a curve A. In the figure,
The vertical axis represents the receiving sensitivity, and the horizontal axis represents the frequency (MHz). As shown in FIG. 2, when two IC cards are overlapped with their respective surfaces facing upward, the resonance frequency of each of the resonance circuits 13-1 and 13-2 is 12.4 MHz.
, And the reception sensitivity characteristic is as shown by a curve B.

Therefore, conventionally, the carrier frequency of the electromagnetic wave radiated from the reader / writer is, for example, 13.56 MHz.
In the case of z, the resonance frequency of the resonance circuit 13 of each IC card is preset to 17.5 MHz higher than the carrier frequency. In this way, as is clear from curves A and B in FIG. 5, electromagnetic waves are received regardless of whether one IC card is used or two IC cards are used in the same direction. be able to.

[0016]

By the way, as shown in FIG. 6, when one IC card is superimposed with its front side up and the other one is with its back side up (two When the IC cards are stacked so that the front surfaces or the back surfaces face each other), the linear portion L1 of the loop antenna 1-1
Is a straight line portion L13 of the loop antenna 1-2, a straight line portion L2 of the loop antenna 1-1 is a straight line portion L12 of the loop antenna 1-2, and a straight line portion L3 of the loop antenna 1-1.
Basically overlap with the linear portion L11 of the loop antenna 1-2, however, the overlap is more complicated than in the case of FIG.

FIG. 7 shows an equivalent circuit of the resonance circuit in this case. In this case, the linear portions L1 to L4 of the loop antenna 1-1 have predetermined values of coupling coefficients M11 to M14.
Then, the linear portions L11 to L14 of the loop antenna 1-2 are
And are respectively combined. At this time, the resonance circuit 13-
The combination of 1,13-2 becomes more complicated. Although the rationale is not always clear, at least as a result of experiments,
The resonance frequencies of the resonance circuits 13-1 and 13-2 are further reduced as compared with the case where they are superposed as shown in FIG. When the resonance circuits 13-1 and 13-2 are configured as shown in FIG. 4, the resonance frequency is 10.5 MHz, and the reception sensitivity characteristic is as shown by a curve C in FIG.

As described above, the method of setting the resonance frequency of the resonance circuit 13 to be higher than the carrier frequency in advance in consideration of the case where a plurality of IC cards are overlapped with each other is performed when the number of IC cards is one and when two IC cards are used. Are sufficiently effective when they are superposed in the same direction as shown in FIG. 2, but are sufficiently effective when they are superimposed in the opposite direction as shown in FIG. Can not be obtained.

The present invention has been made in view of such a situation, and the receiving efficiency is improved by forming the loop antenna into a shape that makes it difficult to couple the IC card regardless of how the IC cards are overlapped. It does not lower it.

[0020]

According to a first aspect of the present invention, there is provided an electronic device, wherein the loop antenna includes a plurality of electronic devices such that the front surface and at least a part of the front surface face each other, or at least the back surface and the back surface. It is characterized in that the conductors forming the loop antenna are less overlapped when they are overlapped so that they partially face each other.

According to a sixth aspect of the present invention, in the information writing / reading device, the loop antenna may be configured so that the plurality of electronic devices face each other such that the front surface and at least a part of the front surface face each other or at least a part of the back surface faces each other. When overlapping, the plurality of electronic devices configured to reduce the overlap between the conductors constituting the loop antenna are in a state where at least a part of one surface and the other back surface are overlapped. At this time, a writing and reading unit for writing or reading information to or from one of the electronic devices is provided.

According to a seventh aspect of the present invention, there is provided the information writing / reading method, wherein the loop antenna is provided so that the plurality of electronic devices face each other at least partially. When overlapping, the plurality of electronic devices configured to reduce the overlap between the conductors constituting the loop antenna are in a state where at least a part of one surface and the other back surface are overlapped. In some cases, the method includes a writing / reading step of writing / reading information to / from one and the other electronic devices.

In the electronic device according to the first aspect, the information writing / reading device according to the sixth aspect, and the information writing / reading method according to the seventh aspect, the loop antenna includes a plurality of the electronic devices, and When superposed such that at least a part of the front surface is opposed or at least a part of the back surface is opposed, the shape of the loop antenna is such that the conductors constituting the loop antenna have less overlap.

[0024]

FIG. 8 shows a configuration example of a contactless IC card system. The IC card 21 is a batteryless IC card having no battery for power supply. The loop antenna 1 constituting a resonance circuit together with the capacitor 12 receives an electromagnetic wave (shown by a solid line) radiated from the reader / writer 31, converts the received electromagnetic wave into an electric signal, and supplies the electric signal to the IC 22. The internal configuration of the IC 22 will be described later with reference to FIG.

The host computer 41 controls a DPU (Digital Processing Unit) 51 of the reader / writer 31 to write predetermined data to the IC card 21 or to read predetermined data. Further, the host computer 41 processes the read data input from the DPU 51 and displays the read data on a display unit (not shown) as necessary.

The DPU 51 generates control signals for various controls based on a command from the host computer 41, controls the modulation / demodulation circuit 52, generates transmission data corresponding to the command, and supplies the transmission data to the modulation / demodulation circuit 52. .
Further, the DPU 51 generates reproduction data based on response data from the modulation / demodulation circuit 52 and outputs the reproduction data to the host computer 41.

The modulation / demodulation circuit 52 modulates the transmission data input from the DPU 51 and supplies it to the loop antenna 53. The modulation / demodulation circuit 52 also demodulates the modulated wave from the loop antenna 53 and inputs the demodulated data to the DPU 51.
The loop antenna 53 emits an electromagnetic wave corresponding to the modulation signal input from the modulation / demodulation circuit 52.

Next, referring to FIG. 9, the reader / writer 3
1 and the specific configuration of the IC 22 will be described. In this figure, the modulation / demodulation circuit 52 of the reader / writer 31 shown in FIG. 8 is illustrated as an oscillator 52A as a modulation circuit and a demodulation circuit 52B.

The IC 22 connected to the resonance circuit composed of the loop antenna 1 and the capacitor 12 of the IC card 21
The rectifier circuit 71 is provided. The rectifier circuit 71 includes a diode 81, a resistor 82, and a capacitor 83. The rectifier circuit 71 rectifies and smoothes the signal supplied from the loop antenna 1 and supplies a positive level voltage to the regulator 74. The regulator 74 stabilizes the input positive level voltage, converts it into a predetermined level DC voltage, and supplies it to the sequencer 76 and other circuits as a power source.

A modulation circuit 72 is connected to a stage subsequent to the rectification circuit 71. The modulation circuit 72 is configured by a series circuit of an impedance element 91 and an FET (Field Effect Transistor) 92, and is connected in parallel with the loop antenna 1 forming the coil of the resonance circuit. FET92 is
It is turned on or off in response to a signal from the sequencer 76, so that the impedance element 91 is inserted in parallel with the loop antenna 1 or not inserted.
Thereby, the loop antenna 53 of the reader / writer 31 is
, The impedance of the circuit electromagnetically coupled via the loop antenna 1 (the load on the loop antenna 53) is changed.

The signal rectified and smoothed by the rectifier circuit 71 is supplied to a high-pass filter (hereinafter, referred to as HPF (High-pass-Filter)) 73 composed of a capacitor 101 and a resistor 102, and a high-frequency component thereof is extracted. The signal is supplied to a demodulation circuit 75. The demodulation circuit 75 demodulates the input high frequency component signal and outputs it to the sequencer 76. The sequencer 76 includes a ROM (Read Only Memory) and a RAM
(Random Access Memory) therein, stores the signal (command) input from the demodulation circuit 75 in the RAM, analyzes the signal in accordance with a program stored in the ROM, and, based on the analyzed result, The data stored in the memory 77 is read as needed. The sequencer 76 further generates a response signal for returning a response corresponding to the command, and supplies the response signal to the modulation circuit 72.

Next, from the reader / writer 31 to the IC card 2
The operation when information is written in No. 1 will be described. The host computer 41 is a DPU 51 of the reader / writer 31.
To instruct the IC card 21 to write predetermined data. The DPU 51 generates a command signal for writing based on a command from the host computer 41, generates transmission data (write data) corresponding to the command, and supplies it to the oscillator 52A. Oscillator 52A
Modulates the amplitude of the oscillation signal based on the input signal, and supplies the modulated signal to the loop antenna 53. Loop antenna 5
Reference numeral 3 radiates an electromagnetic wave corresponding to the input modulation signal.

The resonance frequency of the resonance circuit including the loop antenna 1 and the capacitor 12 of the IC card 21
It is set to a value corresponding to the oscillation frequency (carrier frequency) of A. Therefore, the resonance circuit receives the radiated electromagnetic wave by a resonance operation, converts the received electromagnetic wave into an electric signal, and supplies the electric signal to the IC 22. The converted electric signal is input to the rectifier circuit 71 included in the IC 22. The diode 81 of the rectifier circuit 71 rectifies the input signal,
The capacitor 83 smoothes this, and supplies a positive level voltage,
It is supplied to the regulator 74. The regulator 74 stabilizes the input positive level voltage, converts it into a predetermined level DC voltage, and supplies it to the sequencer 76 and other circuits as a power source.

The signal rectified and smoothed by the rectification circuit 71 is supplied to the HPF 73 via the modulation circuit 72, where the high-frequency component is extracted and supplied to the demodulation circuit 75. The demodulation circuit 75 demodulates the input high frequency component signal and outputs it to the sequencer 76. The sequencer 76 includes a demodulation circuit 7
5 is stored in a RAM, the signal is analyzed according to a program stored in the ROM, and the write data supplied from the demodulation circuit 75 is supplied to the memory 77 based on the analyzed result. Write.

On the other hand, when the command supplied from the demodulation circuit 75 is a read command, the sequencer 76 reads data corresponding to the command from the memory 77. The sequencer 76 turns on or off the FET 92 according to the read data. When the FET 92 is turned on, the impedance element 91 is connected to the loop antenna 1 in parallel, and when the FET 92 is turned off, the parallel connection is released. As a result, the impedance of the load circuit of the loop antenna 53 electromagnetically coupled via the loop antenna 1 is changed according to the read data.

The terminal voltage of the loop antenna 53 changes according to the change in the impedance of the load. The demodulation circuit 52B reads this change to demodulate the read data and outputs it to the DPU 51. The DPU 51 appropriately processes the input read data and outputs the read data to the host computer 41. The host computer 41 includes a DPU 51
The input read data is processed and displayed on a display unit (not shown) as necessary.

FIG. 10 shows the IC card 21 shown in FIGS.
1 shows a configuration example of a loop antenna 1 incorporated therein, and portions corresponding to those in the conventional case are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The loop antenna 1 shown in FIG. 10 has a rectangular basic shape and is wound in four turns. The values of the inner angles θ of the four angles are all 90 ° −α in any winding. That is, the straight line portion L1
And the straight portion L2, the straight portion L2 and the straight portion L3, the straight portion L3 and the straight portion L4, and the straight angles L4 and the straight portion L5.
All are 90 ° -α. Here, the value of the constant α can be set to any positive or negative value other than 0. As a result, on each side of the square, each straight line portion is in a non-parallel state. For example, on the upper side of the square,
The straight portions L2, L6, L10, and L14 are in a state of being non-parallel to each other.

The terminals 14-A and 14-B are connected to the IC 22. By configuring the loop antenna 1 in such a shape, the two IC cards 21 are superimposed in the same direction as shown in FIG.
As shown in (1), in any case of the superposition in the opposite direction, the linear portions of the loop antenna 1 are hardly coupled (when viewed from above, the overlapping portions of the linear portions are reduced), and the reception is reduced. A decrease in efficiency can be suppressed.

As a result, communication is performed in any of the case where one IC card 21 is used, the case where two IC cards 21 are stacked in the same direction, and the case where two IC cards 21 are stacked in the opposite direction. , A sufficient receiving sensitivity can be obtained.

The shape of the loop antenna 1 described above can be further applied to a shape (regular polygon) as shown in FIG.

FIG. 11A shows the shape of the loop antenna 1 when the basic shape is a triangle. The value of the interior angle θ ₁ of the triangle is calculated according to the following equation (1).

Θ ₁ = 60−α ₁ (1) FIG. 11B shows the shape of the loop antenna 1 when the basic shape is a quadrangle. The value of the interior angle θ ₂ of the rectangle is calculated according to the following equation (2).

Θ ₂ = 90−α ₂ (2) Further, FIG. 11C shows the shape of the loop antenna 1 when the basic shape is a pentagon. The value of the internal angle θ ₃ of the pentagon is calculated according to the following equation (3).

Θ ₃ = 108−α ₃ (3) Accordingly, if the basic shape is an n-gon, the loop antenna 1
In the case of, the value of the interior angle θ ₄ of the n-sided polygon is calculated according to the following equation (4).

Θ ₄ = ((180 ° (n−2)) / n−α ₄ (4) where the values of the constants α _{1 to} α ₄ in the above equations (1) to (4) are , Can be set to any positive or negative value other than 0. If the value of n is made sufficiently large, as shown in FIG.
Can be configured.

In the above-mentioned example, the basic shape is a regular polygon, but it may be a parallelogram or an oval shape. Further, as shown in FIG.
The loop antenna 1 may be eccentric. Furthermore, the constant α
May be changed for each side.

FIG. 13 shows another example of the configuration of the loop antenna 1. In this example, in the loop antenna 1 wound in six turns in a rectangular shape, the value of the internal angle θ is all 90 ° −α, and the capacitor 12 forming the coil of the resonance circuit includes the terminals 14 -A, 14-B, not terminal 1
4-A and a terminal 1 provided in the middle of the loop antenna 1
Connected between 4-C. That is, in this example,
The loop antenna 1 is divided into two by the terminal 14-C.

FIG. 14 shows an equivalent circuit in this case. Loop antenna 1 (linear portions L21 to L21 for simplicity)
26) are divided into loop antennas 1-A and 1-B by a terminal 14-C.
The loop antenna 1-A has linear portions L21 to L23, and the loop antenna 1-B has linear portions L24 to L26. Further, a capacitor 12 is connected in parallel to the loop antenna 1-B. The resonance circuit 111 includes a loop antenna 1-B and a capacitor 12, and its resonance frequency is determined by a carrier frequency.

When one IC card 21 having such a loop antenna 1 is used, or when two IC cards 21 are used in an overlapping manner so as to have a resonance frequency close to a carrier frequency, the resonance circuit 111 is used. Receives the electromagnetic waves efficiently by resonating in response to the emitted electromagnetic waves. This state is called a resonance mode. In the resonance mode, the loop antenna 1-A does not resonate with the electromagnetic wave and functions as an electric wire connecting the resonance circuit 111 and the equivalent resistance 11.

On the other hand, when the plurality of IC cards 21 are used in an overlapping manner such that the resonance frequency is largely separated from the carrier frequency, the resonance circuit 111 does not resonate with the radiated electromagnetic wave and the loop antenna 1 The whole (loop antennas 1-A and 1-B) receives the electromagnetic wave. This state is called a transformer mode. In the transformer mode, the loop antenna 1 and the loop antenna 53 operate as a transformer having no iron core. At this time, the reception sensitivity is lower than in the resonance mode,
In any frequency band, a certain level of reception sensitivity can be obtained.

As described above, in the example shown in FIG. 13, the resonance mode and the transformer mode are selectively used depending on the degree of overlap or the number of overlaps, in addition to the invention of the angle of the inner angle θ of the loop antenna 1. The decrease can be suppressed more effectively.

Next, the loop antenna 1 according to the present invention is integrated with an IC.
FIG. 15 shows a measurement result of the communication distance when applied to the card 21. In the figure, the vertical axis represents the IC card 21
And the communication distance (mm) between the reader / writer 31 and the horizontal axis represents the angle (degree) of the inner angle θ of the loop antenna 1. When one IC card 21 is used, when the inner angle θ of the loop antenna 1 is 90 °, the communication distance is about 106 mm.
When the internal angle θ is 89.85 °, the communication distance is about 1
When the internal angle θ is 89.7 °, the communication distance is about 97 mm. When the internal angle θ is 89.4 °, the communication distance is about 94 mm. That is, as the value of the internal angle θ decreases, the communication distance decreases.

On the other hand, when two IC cards 21 are used in an inverted manner as shown in FIG. 6, when the inner angle θ of the loop antenna 1 is 90 °, the communication distance is about 62 mm. When the internal angle θ is 89.85 °, the communication distance is approximately 76 mm, when the internal angle θ is 89.7 °, the communication distance is approximately 88 mm, and when the internal angle θ is 89.4 °, the communication distance is approximately 98 mm. That is, as the value of the internal angle θ decreases, the communication distance increases.

From the above results, in this example, by setting the inner angle θ of the loop antenna 1 to about 89.5 ° (the values of the constants α _{1 to} α _{4 in} the above equations (1) to (4) are set to 0). .
5), even when two IC cards 21 are used in a stacked manner, a decrease in the receiving sensitivity can be suppressed, and the same receiving sensitivity as when one IC card 21 is used can be obtained. In addition, even when two or more IC cards 21 are used in an overlapping manner, the above-described concept is effective, and the reduction of the receiving efficiency can be suppressed as much as possible for any overlapping. it can.

Therefore, by utilizing the present invention, it is possible to easily configure an anticollision system in which the IC cards 21 are used in an overlapping manner.

In the above description, the loop antenna 1 wound in four turns or six turns has been described as an example, but the number of turns can be arbitrarily set. Furthermore, the loop antenna 1 is provided on the IC card 21,
The present invention can also be applied to card-shaped (plate-shaped) electronic devices other than IC cards.

In this specification, the term “system” refers to an entire device including a plurality of devices and means.

[0058]

As described above, according to the electronic device according to the first aspect, the information writing / reading device according to the sixth aspect, and the information writing / reading method according to the seventh aspect, a plurality of electronic devices are provided. In a case where the surfaces of the loop antenna are overlapped with each other so that at least a part of the front surface and the front surface face each other or at least a part of the rear surface faces each other, the shape of the loop antenna is reduced. Therefore, the receiving sensitivity can be ensured and the data can be written or read out in a non-contact manner, not only when it is used alone but also when it is used by being superposed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a loop antenna 1. FIG.

FIG. 2 is a diagram illustrating overlap of loop antennas 1;

FIG. 3 is a diagram showing an equivalent circuit of the loop antennas 1-1 and 1-2 of FIG.

FIG. 4 is a diagram illustrating a loop antenna 1;

FIG. 5 is a diagram illustrating reception sensitivity.

FIG. 6 is a diagram illustrating overlapping of loop antennas 1;

FIG. 7 is a diagram illustrating an equivalent circuit of the loop antennas 1-1 and 1-2 of FIG. 7;

FIG. 8 is a block diagram showing a configuration example of a contactless IC card system to which the present invention is applied.

FIG. 9 is a circuit diagram showing a configuration example of an IC 22 in FIG. 8;

FIG. 10 is a diagram illustrating a loop antenna 1.

FIG. 11 is a diagram illustrating the shape of the loop antenna 1.

FIG. 12 is a diagram illustrating a loop antenna 1.

FIG. 13 is another diagram illustrating the loop antenna 1. FIG.

FIG. 14 is a diagram showing an equivalent circuit of the loop antenna 1 of FIG.

FIG. 15 is a diagram illustrating a communication distance.

[Explanation of symbols]

1 loop antenna, 11 equivalent resistance, 12 capacitor, 14 terminals, 21 IC card, 22 I
C, 31 reader / writer, 41 host computer, 51 DPU, 52A oscillator, 52B demodulator, 53 loop antenna, 71 rectifier,
72 modulation circuit, 39 HPF, 74 regulator,
75 demodulation circuit, 76 sequencer, 77 memory, 81 diode, 82 resistor, 83 capacitor, 91 impedance element, 92 FET,
101 capacitor, 102 resistor, 111 resonance circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Nakamura 5432 Toyoshina, Toyoshina-cho, Minamiazumi-gun, Nagano Prefecture Sony Digital Products Co., Ltd. F-term (reference) AB12 AC06 AC09 AC11 AE00 BA02

Claims (7)

[Claims] 1. A substantially plate-shaped electronic device including a loop antenna, wherein the loop antenna is configured such that a plurality of the electronic devices are arranged such that at least a part of the surface is opposed to a surface thereof, or
An electronic device having a shape in which the overlap between conductors constituting the loop antenna is reduced when the back surface is overlapped so that at least a part of the back surface faces each other. 2. The electron according to claim 1, wherein the loop antenna has a polygon as a basic shape, and the plurality of conductors forming each side of the polygon are non-parallel. apparatus. 3. The polygon as the basic shape is a regular polygon, the number of corners of the regular polygon is n, and a predetermined constant is α.
2. The electronic device according to claim 1, wherein the internal angle of the polygon is (180 ° (n−2)) / n−α. 4. The apparatus according to claim 1, further comprising a transmitting / receiving means for transmitting / receiving a signal via said loop antenna.
An electronic device according to claim 1. 5. The electronic device according to claim 1, wherein the electronic device is an IC card. 6. A writing and reading device for writing or reading information to or from a substantially plate-shaped electronic device including a loop antenna, wherein the loop antenna includes a plurality of electronic devices each having a surface and at least a part of a surface thereof. To face each other, or
In the case where the back surface and the back surface are overlapped so that at least a part of the back surface is opposed to each other, the plurality of electronic devices having a shape in which the conductors constituting the loop antenna have a small overlap are formed on one surface and the other back surface. An information writing / reading device, comprising: a writing / reading unit that writes or reads information to or from the one and the other electronic devices when at least a part of the electronic devices is in an overlapped state. 7. An information writing / reading method of a writing / reading device for writing / reading information to / from a substantially plate-shaped electronic device including a loop antenna, wherein the loop antenna includes a plurality of the electronic devices on a surface thereof. So that at least a part of them faces each other, or
In the case where the back surface and the back surface are overlapped so that at least a part of the back surface is opposed to each other, the plurality of electronic devices having a shape in which the conductors constituting the loop antenna have a small overlap are formed on one surface and the other back surface. Writing or reading information to or from one of the electronic devices when at least a part of the electronic devices is in an overlapped state.