JP3230688B2 - Contactless transfer method of data in semiconductor storage medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact transfer method of data in a semiconductor storage medium, and more particularly to a data transfer method suitable for performing non-contact transfer of data to an IC card.

[0002]

2. Description of the Related Art In recent years, as a new information storage medium, IC
Cards are getting attention. An IC card is a card-shaped storage medium that is convenient in form, but has a built-in semiconductor storage element, and can record a much larger amount of information than a magnetic card or the like. In addition, an IC card with a built-in CPU has a high value of use for applications requiring high security because the IC card itself has an arithmetic processing function.

A reader / writer device is used to write data to and read data from a semiconductor storage medium such as the IC card described above. If the input / output terminal on the reader / writer device is electrically contacted with the input / output terminal on the IC card side, power and clock can be supplied from the reader / writer device to the IC card.
Also, data transfer between the two becomes possible. As a new method for performing data transfer between the two, a method has recently been proposed in which data is transferred while the two are physically in a non-contact state. That is, a coil provided on the reader / writer device side and a coil provided on the IC card side are magnetically coupled to each other so that power and a clock are supplied and data is transferred. If such non-contact data transfer is performed, an external input / output terminal becomes unnecessary, and portability of an IC card or the like becomes more convenient.

[0004]

However, the conventional non-contact transfer method of data in a semiconductor storage medium described above has a problem that bidirectional information transmission through a coil cannot be efficiently performed. Generally, data transfer in a non-contact state is very disadvantageous in that accurate information transfer is performed as compared with data transfer in a state in which electrical contact is secured. That is, in order to perform data transfer in a non-contact state, a data signal is modulated by a carrier wave, and this modulated wave is transmitted from one coil to the other coil by electromagnetic induction, and then demodulated on the modulated wave. Must be performed to extract the data signal. Furthermore, in order to perform bidirectional information transmission, in the conventional method, two coils, a transmission coil and a reception coil, are arranged in both the reader / writer device and the semiconductor storage medium. However, in the case of a semiconductor storage medium such as an IC card, it is necessary to take advantage of the feature that it is a small device that is convenient to carry, and it is difficult to arrange two sets of coils that enable efficient magnetic coupling.

Accordingly, an object of the present invention is to provide a non-contact transfer method of data in a semiconductor storage medium which can efficiently perform bidirectional information transmission via a coil.

[0006]

SUMMARY OF THE INVENTION The present invention provides a semiconductor storage medium and a method for writing / writing data to / from the semiconductor storage medium.
In a method of performing data transfer between a reader / writer device for performing reading and a reader / writer device, a spiral formed on a first plane is provided.
A first coil for transmission, comprising a coil in the shape of
By winding a conductor around the central axis included in the plane of
For receiving having higher reception sensitivity than the first coil.
Of a reader / writer device having a second coil
And a spiral coil formed on the second plane.
Prepare a semiconductor storage medium having a third coil for reception
And the reader / writer device and the semiconductor storage medium,
The first plane and the second plane are almost parallel
A first signal wave corresponding to data transmitted from the reader / writer device to the semiconductor storage medium, and a second signal wave corresponding to data transmitted from the semiconductor storage medium to the reader / writer device, On the reader / writer device side, the first signal wave and the carrier wave are superimposed to generate a modulated wave, the modulated wave is applied to the first coil for transmission, and the load fluctuation generated in the third coil is reduced. The second signal wave is detected by the second coil and the second signal wave is received. On the semiconductor storage medium side, the modulated wave is received by the third coil and the first modulated wave is detected by demodulating the received modulated wave. And a load variation is given to the third coil based on the second signal wave,
The bidirectional data transfer can be performed while the two are physically in a non-contact state . Ma
The center axis of the second coil is directed toward the center of the first coil.
One end of the second coil is connected to the first coil
Use the reader / writer device located on the outer periphery of the
It is something that has been done. In addition, a conductor is attached to a ferrite rod.
A coil having a second coil formed by winding
In this case, a reader / writer device is used.

[0007]

In the data transfer method according to the present invention, the reader / writer device requires two coils, a transmission coil and a reception coil, but the semiconductor storage medium has a single dual-purpose transmission / reception coil. Only coils need be provided. The first signal wave generated by the reader / writer device is transmitted from the transmission coil on a carrier wave and received by the shared coil on the semiconductor storage medium side. On the other hand, the second signal wave generated in the semiconductor storage medium is transmitted to the reader / writer device in the form of a load change occurring in the dual-purpose coil, and is detected by the high-sensitivity receiving coil. As described above, bidirectional data transfer can be efficiently performed by the three coils.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing a reader / writer device 100 and an IC card 200 to which a contactless data transfer method according to the present invention is applied. The reader / writer device 100 has a first coil 110 for transmission and a second coil 110 for reception.
, And the IC card 200 is provided with a third coil 210 for both transmission and reception. As the second coil 120 for reception, a coil having higher reception sensitivity than the first coil 110 for transmission is used. When the reader / writer device 100 and the IC card 200 are in a data transfer state, the first coil 110 and the third coil 2
10 is electromagnetically coupled to the second coil 12
0 and the third coil 210 are electromagnetically coupled. Data transfer between the two is performed via these electromagnetic coupling paths. More specifically, the reader / writer device 1
From 00, power and a clock are supplied to the IC card 200, and a data signal is transmitted and received between the two.

The reader / writer device 100 generates a modulated wave by superimposing a first signal wave containing information on data to be transferred and a carrier wave of a predetermined frequency, and sends the modulated wave to the first coil 110. Give and send. On the other hand, the IC card 200 receives the transmitted modulated wave by the third coil 210, generates power supply power by rectifying the received modulated wave, and extracts a predetermined frequency component from the received modulated wave. A signal wave is detected by generating a clock signal and demodulating the received modulated wave.

FIG. 2 shows an example of the above-mentioned carrier wave, signal wave, and modulation wave. The carrier wave shown in FIG. 2A is an example of a triangular wave for convenience, but a sine wave or a rectangular wave carrier may of course be used. The data to be transmitted is shown in FIG.
It is prepared as a binary signal wave as shown in (b). Fig. 2 (c)
2 is a waveform obtained by modulating the signal wave shown in FIG. 2 (b) with the carrier wave shown in FIG. 2 (a), and is obtained by superimposing the carrier wave and the signal wave. First coil 11
0 is given a modulated wave as shown in FIG. 2C, and the modulated wave is received by the third coil 210 on the IC card 200 side.

The principle of transmitting power, clock, and data from the reader / writer device 100 to the IC card 200 has been described above. Conversely, only data is transmitted in the direction from the IC card 200 to the reader / writer device 100. Is done. However, the carrier propagates only in the direction from the first coil 110 to the third coil 210, and there is no propagation of the carrier in the opposite direction. In order to transmit data from the IC card 200 to the reader / writer device 100,
On the card 200 side, a method of changing the input impedance of the third coil 210 is adopted. For example, when the resistance value of the resistance element connected to the third coil 210 is switched, the current flows through the first coil 110 and the second coil 120 electromagnetically coupled to the third coil 210. The load applied to the current will change. Therefore, the load variation of the third coil 210 generated on the IC card 200 side can be detected by the first coil 110 or the second coil 120 on the reader / writer device 100 side. . However, since the second coil 120 has higher reception sensitivity, detection of a load change is performed by the second coil 120. In this way, if the IC card 200 causes a load change in the third coil 210 based on the second signal wave including information on data to be transferred, the second coil 120 As a result, the second signal wave is detected.

As described above, the load fluctuation of the third coil 210 can be detected by the first coil 110. Therefore, in principle, bidirectional data transfer is possible without using the second coil 120. However, since a modulated wave as shown in FIG. 2 (c) is given to the first coil 110, the load fluctuation component is superimposed on this modulated wave. Generally, since this load fluctuation component (second signal wave) is weaker than the first signal wave shown in FIG. 2B, efficient detection cannot be expected. A feature of the present invention resides in that the second coil 120 is provided as a reception-only coil for detecting a load fluctuation component. The second coil 120 does not need to transmit the modulated wave, and has a higher receiving sensitivity than the first coil 110, so that it is possible to detect load fluctuations efficiently.

FIG. 3 shows an embodiment showing specific shapes and arrangements of three coils used in the present invention. This figure shows the reader / writer device 100 and the IC card 200,
It shows the positional relationship between the three coils when data transfer is performed. Now, a plane XY parallel to the card surface inside the IC card 200 and a plane VW parallel to the plane XY inside the reader / writer device 100 are defined as shown in the figure. In this embodiment, the first coil 110 on the reader / writer device side is a spiral coil formed on the VW plane, and the third coil 210 on the IC card side is a spiral coil formed on the XY plane. Consisting of a coil. Each is formed so as to draw a spiral with the Z axis perpendicular to each plane as the central axis. These spiral coils can be easily formed by a conductive layer printed on a printed circuit board. On the other hand, the second coil 120 on the reader / writer device side is obtained by winding a conductive wire around the coil center axis 121 included in the VW plane, and a ferrite rod is inserted at the position of the coil center axis 121. It is in a state.

By arranging the coils having such a shape in the above arrangement, extremely efficient data transfer becomes possible. First coil 110 and third coil 210
Are all spiral-shaped and face in parallel. Therefore, the modulated wave generated in the first coil 110 is efficiently transmitted to the third coil 210. Also,
Since it has a planar spiral shape, it is most suitable for being incorporated in the IC card 200 which is required to have a thin card shape. Ideally, the second coil 120 is arranged at a position that is most suitable for detecting a load change occurring in the third coil 210. As a result of the experiment, the inventor of the present application determined that the coil center axis 121 was oriented in the direction toward the center of the first coil 110, and the one end a of the second coil 120 was located near the outer periphery of the first coil 110. Was found to be optimal. The end a is preferably arranged in a VW plane so as to approach the first coil 110, but the end b may be off the VW plane.

As described above, the present invention has been described based on the illustrated embodiments. However, the present invention is not limited to this embodiment alone, and can be implemented in various other modes. For example, the shape and arrangement of each coil shown in FIG. 3 are shown as an example, and are not limited thereto.
Further, as the second coil 120, a magnetic detection element having a function equivalent to this, for example, a Hall element may be used.

[0016]

As described above, according to the non-contact data transfer method of the present invention, the transmitting and receiving coils are provided on the reader / writer device, and the transmitting / receiving coil is provided on the semiconductor storage medium. Provided, and connect these coils to each other
Since it is arranged in a special positional relationship, it is possible to efficiently perform bidirectional information transmission via the coil.

[Brief description of the drawings]

FIG. 1 shows a reader / writer device 100 and an IC card 20 to which a contactless data transfer method according to the present invention is applied.
FIG.

FIG. 2 is a waveform diagram showing an example of a carrier wave, a signal wave, and a modulated wave used in the non-contact data transfer method according to the present invention.

FIG. 3 is a diagram showing an example of an arrangement of three coils used in a non-contact data transfer method according to the present invention.

[Explanation of symbols]

 Reference Signs List 100 reader / writer device 110 first coil 120 second coil 121 central axis of coil 200 IC card 210 third coil

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-151831 (JP, A) JP-A-1-151832 (JP, A) JP-A-3-9492 (JP, A) JP-A-63-1988 55688 (JP, A) JP-A-63-261489 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06K 17/00

Claims (3)

(57) [Claims] 1. A method for transferring data between a semiconductor storage medium and a reader / writer device for writing / reading data to / from the semiconductor storage medium, comprising: a spiral formed on a first plane Transmission consisting of a coil
And a central axis included in the first plane
And the first coil is wound around a wire.
And a second coil for reception having higher reception sensitivity than the
A reader / writer device for receiving data comprising a spiral coil formed on a second plane.
A semiconductor storage medium having a third coil is prepared, and the reader / writer device and the semiconductor storage medium are
So that the first plane and the second plane are substantially parallel
And generating a first signal wave corresponding to data transmitted from the reader / writer device to the semiconductor storage medium and a second signal wave corresponding to data transmitted from the semiconductor storage medium to the reader / writer device; On the writer device side, the first signal wave and the carrier wave are superimposed to generate a modulated wave, the modulated wave is given to the first coil for transmission, and the load fluctuation generated in the third coil is performed. Is detected by the second coil and the second
The semiconductor storage medium side receives the modulated wave by the third coil, demodulates the received modulated wave, detects the first signal wave, and detects the second signal wave. given load variation to the third coil based on the signal wave while placed in a state of physical non-contact of both, a semiconductor memory, characterized in that to be able to perform bidirectional data transfer A contactless transfer method for data on a medium. 2. The non-contact transfer method according to claim 1, wherein the center axis of the second coil is arranged in a direction toward the center of the first coil, and one end of the second coil is connected to the first coil. Using a reader / writer device located on the outer periphery
Non-contact transfer method of data in a semiconductor memory medium, characterized by. 3. The non-contact transfer method according to claim 1 or 2, is constituted by winding a conductive wire made of ferrite rods
Using a reader / writer device having a second coil
A non-contact transfer method of data in a semiconductor storage medium, characterized in that: