JPH07271941A - Semiconductor storage medium and non-contact power supply method/device for the medium - Google Patents

Abstract

PURPOSE:To always ensure the stable supply of power even when the relative position relation between the coil of a reader/writer device and the coil of an IC card is varied. CONSTITUTION:A carrier wave is received by a coil 201 from a reader/writer device and rectified by a rectifier 202. Then the rectified carrier is smoothed by a ripple filter 203 and stabilized by a regulator 204. Thus the power voltage VCC is obtained. A reference voltage generator 211 always generates the reference voltage VR of a fixed level, and a comparator 212 compares the divided voltage V' with the voltage VR. The result of this comparison is outputted by a control signal generator 213 as a control signal P. The signal P is transmitted to the reader/writer device via a modulator 220. The reader/writer device increases the carrier energy with V'<VR and then reduces the carrier energy with V'>VR respectively based on the signal P by the feedback control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying a non-contact power supply to a semiconductor storage medium, and more particularly to transmitting electromagnetic wave energy from an external device to the semiconductor storage medium, and based on the electromagnetic wave energy, the semiconductor storage medium The present invention relates to a contactless power supply method for supplying power while maintaining a physically non-contact state between the two by generating a necessary power supply voltage, and a power supply device and a semiconductor storage medium used for implementing this method.

[0002]

2. Description of the Related Art In recent years, IC has been used as a new information storage medium.
Cards are attracting attention. Although the IC card is a card-shaped storage medium that is convenient for carrying, it incorporates a semiconductor storage element and can record extremely large amount of information as compared with a magnetic card or the like. Further, in the IC card with a built-in CPU, since the IC card itself has an arithmetic processing function, it is highly useful for applications requiring a high degree of security.

A reader / writer device is used to write data in and read data from a semiconductor storage medium such as the IC card described above. If the input / output terminal of this reader / writer device is brought into electrical contact with the input / output terminal of the IC card side, the reader / writer device and the IC
Data can be transferred to and from the card. At present, the most commonly used IC cards are those that supply a power source and a clock from the reader / writer device side. In such an IC card, it is not necessary to prepare a battery or a clock generation circuit inside, and therefore, there is an advantage that the size can be easily reduced.

Recently, a method has been proposed in which power is supplied to the IC card from the reader / writer device while the two are physically in a non-contact state, and data is transferred between the two. Has been done. That is,
A first coil provided on the reader / writer device side and an IC
The second coil provided on the card side magnetically or electromagnetically couples the two, and supplies power and clocks and also transfers data. For example, if a predetermined transmission data is superimposed on a carrier wave generated in the reader / writer device to generate a modulated wave and the modulated wave is transmitted to an IC card, the IC card side supplies the power to the modulated wave. , Clock, data can be retrieved.
That is, data is extracted by demodulating the modulated wave, a clock is generated by utilizing the periodicity of the carrier component in the modulated wave, and electric power is extracted based on the electromagnetic wave energy contained in the modulated wave. It is used as a power source. If such a non-contact transfer method is adopted, an external input / output terminal becomes unnecessary and the portability of an IC card or the like is further improved.

[0005]

As described above, when power is supplied from the reader / writer device to the IC card in a contactless manner, power is supplied in the form of electromagnetic wave energy through a pair of coils. Become. That is, on the reader / writer device side, the electromagnetic wave energy generated by the high frequency power amplifier is transmitted from the transmission coil. On the other hand, IC
On the card side, this electromagnetic wave energy is received by the receiving coil, this electromagnetic wave energy is supplied to a rectifier or regulator to obtain DC power, and this is used as a power supply.

The transmission efficiency of such electromagnetic energy greatly depends on the positional relationship between the pair of coils. However, the IC card is usually carried by an individual person, and is generally used by inserting the IC card into a reader / writer device installed at a necessary place to exchange data. Is. Therefore, one IC card is used by being inserted into a plurality of different reader / writer devices. Here, since the positional accuracy of the card loading mechanism in the reader / writer device, the installation position of the coil, and the like inevitably vary from device to device, the coil on the reader / writer device side and the coil on the IC card side do not move relative to each other. It is difficult to keep the position always constant. Moreover, IC
Since the coil built in the card side must be relatively small, even if the relative position to the coil built in the reader / writer device changes slightly, the transmission efficiency of electromagnetic wave energy will change greatly. become.
In addition, there has been proposed a usage form in which data is exchanged only by bringing an IC card close to a reader / writer device. In this case, a change in relative position between a coil on the IC card side and a coil on the reader / writer device side. Will be even greater.

Due to these causes, the magnitude of the electromagnetic wave energy supplied to the IC card side has a certain width. Thus, it is not preferable that the magnitude of the supplied electromagnetic wave energy becomes unstable.
For example, when the relative position of the pair of coils happens to be the position with the highest transmission efficiency, the magnitude of the electromagnetic wave energy supplied to the IC card side becomes the maximum, and an excessive voltage is generated in the coil on the IC card side. However, there is a risk of destroying the elements inside the IC card. However, in order to avoid such a danger, if the electromagnetic wave energy transmitted from the reader / writer device side is set to a size within a safe range, the relative position of the pair of coils happens to have the highest transmission efficiency. When it comes to a bad position, the magnitude of the electromagnetic wave energy supplied to the IC card side becomes the minimum, a sufficient voltage cannot be obtained in the coil on the IC card side, and a normal power supply voltage cannot be obtained. Occurs.

Therefore, according to the present invention, even if the relative positional relationship between the coil on the side of the external device and the coil on the side of the semiconductor storage medium changes, non-contact power supply to the semiconductor storage medium can always be performed so that stable power supply can be performed. The purpose is to provide a method.

[0009]

[Means for Solving the Problems]

(1) A first aspect of the present invention is to transmit electromagnetic wave energy from an external device to a semiconductor storage medium, and generate a power supply voltage required in the semiconductor storage medium based on the electromagnetic wave energy. In a non-contact power supply method that supplies power while physically maintaining a non-contact state, the semiconductor storage medium compares the voltage generated based on the transmitted electromagnetic wave energy with a predetermined reference voltage. Then, the comparison result is transmitted to the external device.On the external device side, when the generated voltage is smaller than the reference voltage, the magnitude of the electromagnetic wave energy to be transmitted is set according to the received comparison result. When the generated voltage is increased and the generated voltage is larger than the reference voltage, control is performed to reduce the magnitude of the electromagnetic wave energy to be transmitted.

(2) A second aspect of the present invention is the above-mentioned first aspect.
In order to carry out the method according to the second aspect, a non-contact power supply device having a function of supplying power to a semiconductor storage medium while maintaining a physically non-contact state by transmitting electromagnetic wave energy. In the semiconductor storage medium, transmitting means for transmitting electromagnetic wave energy to the semiconductor storage medium, receiving means for receiving a predetermined control signal transmitted from the semiconductor storage medium, and the magnitude of the electromagnetic wave energy to be transmitted based on the control signal. And a control means for controlling the height.

(3) A third aspect of the present invention relates to the above-mentioned first aspect.
In order to carry out the method according to the aspect (1), a semiconductor storage medium having a function of generating a necessary power supply voltage based on electromagnetic wave energy transmitted from an external device is generated based on the transmitted electromagnetic wave energy. The generated voltage is smaller than the reference voltage according to the comparison means for comparing the generated voltage with a predetermined reference voltage, and the magnitude of the electromagnetic wave energy to be transmitted to the external device is determined. And a transmitting means for transmitting an instruction to increase and transmitting an instruction to decrease the magnitude of electromagnetic wave energy to be transmitted to the external device when the generated voltage is larger than the reference voltage. .

[0012]

[Operation] In the power supply method according to the present invention, a voltage generated based on electromagnetic wave energy is compared with a predetermined reference voltage on the semiconductor storage medium side, and the comparison result is transmitted to an external device. . Based on this comparison result, the external device side can recognize whether the electromagnetic wave energy currently transmitted is strong or weak, and the magnitude of the electromagnetic wave energy can be adjusted. That is, when the generated voltage in the IC card is smaller than the reference voltage,
The control is performed such that the magnitude of the electromagnetic wave energy to be transmitted is increased, and when the generated voltage is larger than the reference voltage, the magnitude of the electromagnetic wave energy to be transmitted is reduced.
Thus, the magnitude of the electromagnetic wave energy can be feedback-controlled based on the comparison result transmitted from the IC card side, and the relative positional relationship between the coil on the external device side and the coil on the semiconductor storage medium side can be determined. Even in this case, it becomes possible to always supply the electromagnetic wave energy of the optimum size.

[0013]

The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows a general reader / writer device 100 and an IC.
6 is a block diagram showing a combined state at the time of data transfer with the card 200. FIG. The reader / writer device 100 has a first coil 101 built therein, and the IC card 200 has a second coil 201 built therein. IC card 200
Is usually formed by an individual, but when used for some purpose (for example, when performing a bank transaction), this is inserted into the insertion port of the reader / writer device 100. Then,
By the card loading mechanism in the reader / writer device 100, the inserted IC card 200 is sent to a predetermined position and fixed. In this state, the first coil 101 and the second coil 201 are electromagnetically coupled.
As mentioned above, the relative position of both coils at this time is
It is not always constant and has variations. When both coils are electromagnetically coupled in this way, power and clock are supplied from the reader / writer device 100 to the IC card 200, and data is bidirectionally transferred between them.

FIG. 2 is a block diagram showing the internal structure of the reader / writer device 100. The oscillator 110 has a function of generating a carrier wave C having a predetermined frequency, and the generated carrier wave C is given to the modulator 120. Modulator 120
From the reader / writer device 100 to the IC card 20
The data D1 to be sent to 0 is given, and the modulated wave M is generated by superimposing the information of this data D1 on the carrier wave C. The modulated wave M is power-amplified by the power amplifier 130 and supplied to the first coil 101, and is transmitted from the first coil 101 to the IC card 200 side as an electromagnetic wave. On the other hand, the data D2 to be sent from the IC card 200 to the reader / writer device 100 will be described later.
It is received as a current fluctuation in the first coil 101, and the demodulator 140 detects the data D2 based on this current fluctuation. After all, this reader / writer device 100
The function of transmitting data D1 to the card 200, and I
The IC card 20 has a function of receiving the data D2 transmitted from the C card 200, and further supplies electric power and a clock as electromagnetic wave energy from the first coil 101.
It has a function of supplying 0.

Each of the above constituent elements is a known element provided in a conventional general reader / writer device.
The reader / writer device 100 according to the present invention is characterized in that a power controller 150 is further provided in addition to these constituent elements. The power controller 150 has a function of controlling the power amplification factor in the power amplifier 130. As described later, the signal demodulated by the demodulator 140 includes the control signal P as well as the data D2. Power controller 150
The control signal P is extracted from the demodulation signal based on the carrier wave C generated by the oscillator 110, and the power amplification factor of the power amplifier 130 is controlled based on the control signal P. Specifically, when the control signal P is at the L level, control is performed to gradually increase the power amplification rate, and conversely, when the control signal P is at the H level, the power amplification rate is gradually decreased. Take control. The control operation will be described later.

On the other hand, FIG. 3 is a block diagram showing the internal structure of the IC card 200. The second coil 201 receives the modulated wave M transmitted from the first coil 101 of the reader / writer device 100. The received modulated wave M is
It will be used in three systems: a power system, a clock system, and a data system. Hereinafter, each of these systems will be described in order.

First, the power supply system is composed of a rectifier 202, a ripple filter 203, and a regulator 204. The received modulated wave M (electromagnetic wave energy) is rectified by the rectifier 202, smoothed by the ripple filter 203, and stabilized by the regulator 204. Thus, finally regulator 2
04, the power supply voltage V used inside the IC card
cc is generated and supplied to the CPU / memory 250.

Next, the clock system is constituted by the clock signal generator 240. The clock signal generator 240 has a function of extracting the periodic component (component of the carrier wave C) of the modulated wave M received by the second coil 201 and generating the clock signal CLK based on this. This clock signal CLK is also used by the CPU / memory 2
50.

Finally, the data system is composed of a modulator 220 and a demodulator 230. Demodulator 230
Has a function of demodulating the modulated wave M received by the second coil 201, extracting the data D1 transmitted from the reader / writer device 100 side, and giving this data D1 as received data to the CPU / memory 250. . on the other hand,
The modulator 220 receives data D from the CPU / memory 250.
2 (data to be sent to the reader / writer device 100) is given. In the system of this embodiment, the IC card 20
Information transmission from 0 to the reader / writer device 100 is performed by changing the input impedance of the second coil 201. For example, if a resistance element is connected to the second coil 201 and the resistance value of the resistance element is changed, the input impedance of the second coil 201 changes. As described above, when the input impedance of the coil on the reception side of electromagnetic wave energy changes, the current flowing through the coil on the transmission side of electromagnetic wave energy also changes. Therefore, the variation of the input impedance of the receiving coil can be detected on the transmission side of the electromagnetic wave energy. After all, the electromagnetic energy is
Although the information is transmitted in only one direction from the reader / writer device 100 to the IC card 200, the information from the IC card 200 side (second Fluctuation of the input impedance of the coil 201) can be recognized. In short, the modulator 220 has a function of changing the input impedance of the second coil 201 based on the data D2 to be transmitted to the reader / writer device 100 side.

Each of the above components is a conventional general IC
It is a well-known element provided in the card. The IC card 200 according to the present invention is characterized in that a reference voltage generator 211, a comparator 212, and a control signal generator 213 are further provided in addition to these components. The reference voltage generator 211 has a function of input voltage V smoothed by ripple filter 203, it generates a predetermined reference voltage V _R on the basis of the voltage V. Here, the reference voltage V
_R is always constant regardless of the magnitude of the input voltage V. Reference voltage generator 2 having such a function
Specifically, 11 can use a constant voltage circuit similar to the regulator 204, and may be constituted by a bandgap constant voltage circuit, for example. On the other hand, the ripple filter 2
03 output voltage V is the resistance element R connected in series with each other.
It is divided by 1 and R2. Then, by the comparator 212, the divided voltage V'and the reference voltage V _R is compared. The comparator 212 gives the information indicating the result of the comparison to the control signal generator 213, and the control signal generator 213 outputs the control signal P corresponding to this comparison result. More specifically, in this embodiment, the result of the comparison, when a divided voltage V'<reference voltage V _R is, L level voltage, the divided voltage V
When ′ ≧ reference voltage V _R , a control signal P that outputs an H level voltage is output. This control signal P is
Like the data D2, it is given to the modulator 220 and is transmitted to the reader / writer device 100 side as a change in the input impedance of the second coil 201.

The configuration of the system of this embodiment has been described above. Next, the operation of power supply in this system will be described. The reader / writer device 100 includes the IC card 2
When power is supplied to 00, the modulated wave M obtained from the modulator 120 is power-amplified by the power amplifier 130 and transmitted from the first coil 101. At this time, the power controller 150 instructs the power amplifier 130 to perform power amplification with a predetermined initial amplification factor. As this initial amplification factor, an average value suitable for reception on the IC card 200 side may be set in advance.

Now, in the IC card 200 supplied with such electromagnetic wave energy, the regulator 204
Generates the power supply voltage Vcc, and the clock signal generator 240 generates the clock signal CLK. Further, a reset process for the CPU / memory 250 is performed as necessary. By the way, as described above, since the electromagnetic wave energy transmitted by the reader / writer device 100 at this point is amplified by the average initial amplification factor, the first coil 101 and the second coil 201 are included. If the electromagnetic coupling efficiency with is less than the average, the electromagnetic wave energy received on the IC card 200 side will be smaller than the original magnitude, and conversely, the coupling efficiency of both coils will be reduced. When it is above the average, the electromagnetic wave energy received on the IC card 200 side becomes larger than the original size. As described above, if the magnitude of the received electromagnetic wave energy is not appropriate, the elements in the IC card may be destroyed or a sufficiently stable power supply voltage cannot be secured. Is.

In the system according to the present invention, the magnitude of electromagnetic wave energy supplied to the IC card 200 can be controlled to be optimum by the following operations. First, the optimum voltage value V1 given to the regulator 204
Predetermine. That is, when the voltage V output from the ripple filter 203 is equal to the optimum voltage V1,
The various circuits in the IC card 200 perform optimum operation, and the purpose of this control operation is to perform control to maintain the voltage V output from the ripple filter 203 at the optimum voltage V1. Become. In this case, the optimum voltage V _{R is set} as the reference voltage V _R generated by the reference voltage generator 211.
It is set to a value equal to the value of the voltage dividing resistance value V'obtained when the voltage dividing 1 is divided by the voltage dividing resistance elements R1 and R2. In other words, when the output voltage V of the ripple filter 203 is equal to the optimum voltage V1, the comparator 212, so that V R ₌ V'made comparison result. As the reference voltage V _R, if you set such values,
The following control becomes possible.

This control operation will be described with reference to the graph of FIG. In this graph, the horizontal axis represents the time axis and the vertical axis represents the voltage, and the output voltage V of the ripple filter 203 is shown.
And the divided voltage V ′ obtained by dividing the voltage
And the voltage values of and are shown over time. Here, for convenience, the comparison process in the comparator 212 will be performed every predetermined period T. First, in the comparison processing at time t1, as shown in the graph, since a V'<V _R, as described above, the control signal generator 213
The control signal P output by is at L level. This control signal P is transmitted by the modulator 220 to the reader / writer device 100.
To the power controller 150 via the demodulator 140.
Be transmitted to. The power controller 150 performs control such that the power amplification factor in the power amplifier 130 is gradually increased when the control signal P is at the L level. For this reason,
The electromagnetic wave energy transmitted from the first coil 101 gradually increases. This is the reason why both the voltages V and V'increase from the time (t1 + d) in the graph of FIG. The time d is a delay time from when the level of the control signal P is inverted to L until when the voltages V and V ′ actually start increasing.

Then, in the comparison process at time t2,
As shown in the graph, since a V'> V _R, the control signal P output from the control signal generator 213 H
Invert to level. Then, the power controller 150 performs control such that the power amplification factor in the power amplifier 130 is gradually reduced when the control signal P is at the H level, so the electromagnetic wave energy transmitted from the first coil 101 is gradually increased. Becoming smaller. Therefore, the time (t2
From + d), both the voltages V and V'decrease. Further, in the comparison processing at time t3, V ′ is again set.
<Since a V _R, the control signal P output by the control signal generator 213 is inverted to L level, the power controller 150
Controls to gradually increase the power amplification factor of the power amplifier 130. Therefore, the first coil 10
The electromagnetic wave energy transmitted from 1 gradually increases, and from time (t3 + d), both the voltages V and V'increase. Further, in the comparative process at time t4, again, V'> V _R, and the control signal P output by the control signal generator 213 is inverted to H level, the power controller 1
The control unit 50 controls to gradually reduce the power amplification factor of the power amplifier 130. Therefore, the electromagnetic wave energy transmitted from the first coil 101 gradually decreases, and both the voltages V and V ′ decrease from time (t4 + d). Thereafter, feedback control is performed by this repetition, and the output voltage V of the ripple filter 203 fluctuates up and down around the optimum value V1. In the graph of FIG. 4, for convenience of explanation, the width of this vertical fluctuation is drawn to be considerably large. Can be maintained at an optimum value V1.

By the way, as shown in FIG.
The modulator 220 must transmit the data D2 together with the control signal P to the reader / writer device 100. Moreover, it is necessary to carry the data D1 sent from the reader / writer device 100 to the IC card 200 side on a single information transmission path formed between the reader / writer device 100 and the IC card 200. Therefore, in practice, it is necessary to divide this information transmission path in time and allocate it to the three of the data D1, D2 and the control signal P. The diagram under the heading "Time Allocation" at the bottom of the graph in FIG. 4 is an example of this time allocation. In this example, time is divided into predetermined cycles T, and this one cycle T is further divided into the first half cycle T.
The first half period T1 is assigned to the transmission of the control signal P, and the second half period T2 is assigned to the transmission of the data D1 and D2. Moreover, regarding the latter half period T2, the data D1 is transmitted within the odd-numbered period T, and the data D2 is transmitted within the even-numbered period T, so that bidirectional data transmission is performed alternately. There is.

The waveform shown under the heading "Modulated wave M" shows an example of the actual modulated wave M when such time allocation is performed. In this figure, the portion of each second half cycle T2 is described as "X", but a bit represented by "H" or "L" corresponding to actual data is located in this portion. . On the other hand, the level (“H” or “L”) of the control signal P is shown as it is in the portion of each first half period T1. Therefore, in the reader / writer device 100, in order to extract only the control signal P from the signal demodulated by the demodulator 140 by the power controller 150, as shown in the bottom column of FIG.
At each timing such as δ, time t2 + δ, time t3 + δ, time t4 + δ, it suffices to detect whether the signal level is “L” or “H”. Here, δ is a delay time provided for surely reading the value of the control signal P, and may be set to a value such as the first half period T1 / 2, for example. As shown in FIG. 2, the power controller 150 is supplied with the carrier wave C from the oscillator 110, and
In the card 200, the clock signal CLK is generated based on this carrier wave C. Therefore, the carrier wave C is
The power controller 150 is a signal that provides common clock information in this system.
Timing of extracting the control signal P (time t1 described above
+ Δ, t2 + δ, ...) Can be obtained. of course,
The carrier wave C is also used to obtain the timing of transmitting the data D1 and the timing of extracting the data D2.

Although the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this embodiment and can be implemented in various other modes. In particular, in the above-described embodiment, the example in which the reader / writer device 100 supplies power to the IC card 200 has been described.
INDUSTRIAL APPLICABILITY The present invention can be widely applied to the case where power is supplied to a semiconductor storage medium from some external device. Further, the "time allocation" shown in FIG. 4 shows a simple example for convenience of description, and any other allocation may be performed.

[0029]

As described above, according to the non-contact power supply method for the semiconductor storage medium of the present invention, the magnitude of the electromagnetic wave energy supplied is feedback-controlled, so that the coil on the external device side and the semiconductor storage medium are controlled. Even if the relative positional relationship with the coil on the side fluctuates, stable power supply can always be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a combined state during data transfer between a general reader / writer device 100 and an IC card 200.

FIG. 2 is a block diagram showing an internal configuration of a reader / writer device 100 according to the present invention.

FIG. 3 is a block diagram showing an internal configuration of an IC card 200 according to the present invention.

4 is a graph showing an operation of a power supply system in the IC card 200 shown in FIG.

[Explanation of symbols]

 100 ... Reader / Writer Device 101 ... First Coil 110 ... Oscillator 120 ... Modulator 130 ... Power Amplifier 140 ... Demodulator 150 ... Power Controller 200 ... IC Card 201 ... Second Coil 202 ... Rectifier 203 ... Ripple Filter 204 ... Regulator 211 ... Reference voltage generator 212 ... Comparator 213 ... Control signal generator 220 ... Modulator 230 ... Demodulator 240 ... Clock signal generator 250 ... CPU / memory C ... Carrier wave CLK ... Clock signal D1 ... From reader / writer device to IC Transmission data to card D2 ... Transmission data from IC card to reader / writer device M ... Modulation wave P ... Control signal R1, R2 ... Voltage dividing resistance element T ... Predetermined cycle T1 ... First half cycle T2 assigned to control signal P ... The second half cycle assigned to the data D1 and D2 V ... The ripple filter 2 3 the output voltage V'... divided voltage Vcc ... supply voltage

Claims (3)

[Claims] 1. An electromagnetic wave energy is transmitted from an external device to a semiconductor storage medium, and a necessary power supply voltage is generated in the semiconductor storage medium on the basis of the electromagnetic wave energy, so that the two are physically separated from each other. In a non-contact power supply method for supplying power while maintaining a contact state, on the semiconductor storage medium side, a voltage generated based on the transmitted electromagnetic wave energy is compared with a predetermined reference voltage, and the comparison result Is transmitted to the external device, on the external device side, according to the received comparison result,
When the generated voltage is smaller than the reference voltage, the magnitude of the electromagnetic wave energy to be transmitted is increased, and when the generated voltage is larger than the reference voltage, the magnitude of the electromagnetic wave energy to be transmitted is decreased. A non-contact power supply method to a semiconductor storage medium, characterized by performing such control. 2. A non-contact power supply device having a function of supplying power to a semiconductor storage medium while maintaining a physically non-contact state by transmitting electromagnetic wave energy. A wave sending unit that sends electromagnetic wave energy to the receiving unit, a receiving unit that receives a predetermined control signal sent from the semiconductor storage medium, and a magnitude of the electromagnetic wave energy sent based on the control signal. A contactless power supply device for a semiconductor storage medium, comprising: a control unit. 3. In a semiconductor storage medium having a function of generating a necessary power supply voltage based on electromagnetic wave energy transmitted from an external device, a voltage generated based on the transmitted electromagnetic wave energy is set to a predetermined value. Comparing means for comparing with the reference voltage, and, in accordance with the comparison result, an instruction to increase the magnitude of electromagnetic wave energy to be transmitted to the external device when the generated voltage is smaller than the reference voltage. Send
When the generated voltage is higher than the reference voltage, a transmission unit that transmits an instruction to reduce the magnitude of the electromagnetic wave energy to be transmitted to the external device, a semiconductor memory. Medium.