JP3417018B2 - Electromagnetic induction system - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electromagnetic induction systems.

[0002]

2. Description of the Related Art Constant monitoring of cardiac radio waves and heartbeats (pulses) is important for effective and safe exercise, and for proper treatment and rehabilitation of patients in hospitals. Is important in.

Therefore, conventionally, a monitoring system including a detection device and a monitoring device has been proposed. In this monitoring system, a heartbeat is detected by a detection device mounted on the chest or shoulders, and the detected heartbeat signal is transmitted to a monitoring device mounted on a wrist or a pocket by electromagnetic induction. The monitoring device receives the heartbeat signal due to this electromagnetic induction with one coil, amplifies the received heartbeat signal with an amplifier circuit, and then displays the heartbeat information or notifies when an abnormal heartbeat occurs. Perform processing.

Therefore, when the detection device of the monitoring system is attached to the human body and the heartbeat detected by the detection device is sent to the monitoring device by electromagnetic induction, the heartbeat can be constantly monitored.

[0005]

However, in such a conventional monitoring system, the monitoring device receives the heartbeat signal transmitted from the detection device by electromagnetic induction by one coil, and the monitoring circuit receives the heartbeat signal. Since the signal is amplified, there is a problem that noise of the amplifier circuit is mixed in the signal, the discriminability with respect to the noise of the received signal is poor, and the accuracy of heartbeat measurement is poor.

That is, as described above, in the monitoring system, the detecting device is usually mounted on the chest or shoulder of the human body, and the monitoring device is mounted on the wrist or pocket. Has a distance of several tens of cm to 1 m, and the monitoring device receives a signal transmitted by electromagnetic induction from the detection device between them with one coil. Therefore, the signal received by the monitoring device may be 1 mV or less, and the monitoring device amplifies this received signal with an amplifier circuit,
The subsequent signal processing is performed.

Therefore, in the monitoring device, the amplifier circuit
It is necessary to amplify the received signal with an amplification factor of 000 times or more, and when the received signal is amplified with such an amplification factor, the electromagnetic induction received signal has no received signal, although the received signal shown in FIG.
As shown in FIG. 1A, an output signal is generated due to noise of the amplifier circuit or the like. As a result, even when there is a received signal as shown in FIG. 11B, the output signal of the amplifier circuit is
As shown in (C), the level of the received signal component approaches the level of the noise component, and the discrimination rate of the received signal component from the noise component deteriorates. Therefore, there is a problem that the accuracy of the heartbeat measurement deteriorates.

Therefore, the present invention provides an electromagnetic induction system having good discrimination of signals against noise by receiving electromagnetic induction signals with two coils and amplifying the difference between the signals received by each coil with an amplifier circuit. It is intended to be provided.

[0009]

An electromagnetic induction system of the present invention comprises a transmitter for transmitting a signal by electromagnetic induction, and a receiver for receiving a signal transmitted by electromagnetic induction from the transmitter, The receiving device receives signals by electromagnetic induction transmitted by the transmitting device in opposite phases to each other.
The above-mentioned object is achieved by providing two coils arranged in the above state and an amplifier circuit for amplifying the difference between the signals received by the two coils.

[0010]

According to the electromagnetic induction system of the present invention , the transmitter transmits the signal by electromagnetic induction. The signal transmitted by the electromagnetic induction from the transmitting apparatus, receiving apparatus, each other
In addition, the two coils arranged to receive signals in opposite phases receive the signals, and the difference between the signals received by the two coils is increased or decreased by the amplifier circuit.

Therefore, since the amplification circuit amplifies the difference between the signals received in the opposite phase, the amplification rate of the amplification circuit is smaller than that of the conventional one in order to obtain the same amplification rate as the conventional one. Therefore, the amplification factor of the noise generated by the amplification circuit can be made smaller than the amplification factor of the signal. As a result, the signal discrimination ratio of the signal with respect to the noise component can be increased, and even when the transmitter and the receiver are at a long distance,
The signal can be reliably discriminated from the noise.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 10 are views showing an embodiment of the electromagnetic induction system of the present invention, which is applied to a monitoring system.

First, the structure will be described.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, which is a monitoring system for simultaneously monitoring the pulse of a plurality of subjects (for example, a plurality of patients in a hospital).

In FIG. 1, the monitoring system 1 includes a plurality of shirts 2 for detecting and transmitting a pulse, and a plurality of wristwatches 3 provided in the same number as the shirt 2 for receiving the pulse data transmitted from each shirt 2. The wristwatch 3 includes a receiver 4 that receives the pulse data transmitted by the wristwatch 3, and a monitoring device 5 that centrally manages the biological condition of the patient to whom the shirt 2 is attached based on the pulse data received by the receiver 4. .

The configurations of the shirt 2, the wristwatch 3, the receiver 4 and the monitoring device 5 will be sequentially described below.

<Structure of Shirt 2> As shown in FIG. 2, each shirt 2 is formed in a running shirt form.
It is worn by a plurality of examinees. As shown in FIG. 2, each shirt 2 is provided with a pair of electrodes 10a and 10b at positions on the left and right underarms.
When the shirt 2 is worn on the body of the subject, 10b comes into contact with the skin of the human body wearing the shirt 2 and detects a biosignal (electrocardiographic waveform) emitted from the heart of the subject. An electronic circuit 11 is attached to each hem of each shirt 2, and the electrodes 10a and 10b are connected to the lead wire 12 respectively.
It is connected to the electronic circuit 11 by a and 12b.

As shown in FIG. 3, the electronic circuit 11 includes a detection circuit 13, a transmission circuit 14, a power supply 15, and a power switch 16.
And a transmission coil 17 and the like.

The power supply circuit 15 includes, for example, a battery,
Detection circuit 13 and transmission circuit 1 via power switch 16
Supply power to 4.

The detection circuit 13 includes electrodes 10a, 10
b is connected via lead wires 12a and 12b,
The electrodes 10a and 10b detect the detected biological signal (heartbeat signal).
Is output to the detection circuit 13.

The detection circuit 13 amplifies the biological signal input from the electrodes 10a and 10b and outputs it to the transmission circuit 14,
The transmission circuit 14 converts the biological signal input from the detection circuit 13 into an electromagnetic induction signal and transmits the electromagnetic induction signal from the transmission coil 17.

The biological signal by electromagnetic induction sent from the transmitting coil 17 can be sufficiently detected at a distance of up to about 2 m.

<Structure of Wristwatch 3> Again, the wristwatch 3 shown in FIG. 1 is to be worn on the arm of the subject wearing the shirt 2, and as shown in FIG. Individual receiving coils 21a, 21b, receiving circuit 22, waveform shaping circuit 23, oscillator circuit 24, frequency dividing / timing circuit 25,
RAM (Random Access Memory) 26, ROM (Read O
nly Memory) 27, sound output unit 28, key input unit 29, serial conversion circuit 30, transmission circuit 31, antenna 32, display drive unit 33, display unit 34, and the like.

The receiving coils 21a and 21b are detecting coils for detecting a biological signal by electromagnetic induction transmitted from the transmitting coil 17, and are connected to the receiving circuit 22.

Receiving coils 21a and 21b and receiving circuit 2
2 has a circuit configuration as shown in FIG.

That is, the tuning capacitors Ca and Cb are respectively connected to both ends of each of the receiving coils 21a and 21b, and the both ends of each tuning capacitor Ca and Cb are respectively connected through resistors R1, R2, R3 and R4. Are connected to the positive side input terminal and the negative side input terminal of the differential amplifier OP1 and the differential amplifier OP2.

The positive-side input terminals of the differential amplifier OP1 and the differential amplifier OP2 are commonly connected through the resistors R5 and R6 and are grounded, and the differential amplifiers OP1 and OP2 are also connected. The output of each is resistance R
It is fed back to the minus side input terminal via 7 and the resistor R8.

The output terminal of the differential amplifier OP1 is connected to the negative input terminal of the differential amplifier OP3 via the resistor R9, and the output terminal of the differential amplifier OP2 is connected to the differential amplifier OP10 via the resistor R10. It is connected to the positive input terminal of OP3.

The differential amplifier OP3 has its output terminal and negative input terminal connected to each other via a feedback resistor R11, and its positive input terminal grounded via a resistor R12. The output terminal of the differential amplifier OP3 is connected to the waveform shaping circuit 23 shown in FIG.

When the transmitting coil 17 of the shirt 2 generates an electromagnetic induction signal in the direction indicated by Z0 in FIG. 5, the receiving coils 21a and 21b generate electromagnetic induction currents in the directions indicated by Ia and Ib in FIG. 5, respectively. It is wound in a direction to generate a reception signal current), and the voltages generated across the capacitors Ca and Cb due to the reception signal currents generated in the reception coils 21a and 21b are differential amplifier OP1 and differential amplifier, respectively. Input to OP2. From the direction of the received signal current in Fig. 5
As is apparent, the operational amplifier OP1 and the differential amplifier OP
The received signals input to 2 have opposite phases. And
Each of the differential amplifier OP1 and the differential amplifier OP2 amplifies the received signal input thereto, and outputs the amplified received signal to the negative-side and positive-side input terminals of the differential amplifier OP3. Therefore, the operational amplifier OP3 outputs the amplified received signal to the waveform forming circuit 23 by amplifying the difference between the received signals input to both input terminals.

That is, the wristwatch 3 receives the biomedical signal from the shirt 2 by the two receiving coils 21a and 21b by electromagnetic induction, the received circuit 22 amplifies the difference between the received biomedical signals, and the waveform shaping circuit 23. Output to.

The waveform shaping circuit 23 waveform-shapes the biomedical signal input from the receiving circuit 22 into, for example, a rectangular wave signal and outputs it to the control section 20. The receiving circuit 22 and the waveform shaping circuit 22 start operating in response to the operation signal supplied from the control unit 20.

The oscillating circuit 24 oscillates a clock signal of a predetermined frequency and inputs it to the frequency dividing / timing circuit 25.

The frequency dividing / timing circuit 25 is the oscillator circuit 2.
The clock signal input from 4 is frequency-divided, various timing signals such as a clock signal are generated and supplied to the control unit 20.

The ROM 27 stores programs for the wristwatch 3, for example, a clock processing program, a biometric monitoring and biometric signal transmission processing program based on biometric signals from the shirt 2, and various system data.

The control section 20 controls each section on the basis of a microprogram stored in advance in the ROM 19 to perform various processes described later.

The RAM 20 is used as a work memory for the control unit 20 and stores various data.
Display register area, clock register area,
It has flag register areas F0 and F1, an identification code register area, a period register area T, and the like. Here, the display register area is a register area for storing the display data displayed on the display unit 34, and the clock register area is
This is a register area that stores current time data that is sequentially updated by the timekeeping process. In addition, the flag register area F0
Stores a flag indicating a pulse signal detection state, and the flag register F1 stores a flag indicating an identification code setting state. The identification code register area is a register that stores identification code data. The identification code is set for each subject and is, for example, an 8-digit numerical code. For example, the identification code of the subject A is "0000000.
1 ”, and the identification code of the subject B is“ 00000010 ”. The cycle register area T is a register for measuring the cycle T of a rectangular wave signal of a heart wave (pulse). In addition,
The identification code data is not limited to the RAM 26, but the ROM 27
Alternatively, it may be stored in a rewritable EEPROM.

The alarm unit 28 has a buzzer and its drive circuit, and generates an alarm sound based on the alarm signal output from the controller 20.

Although not shown, the key input unit 29 is provided with K1 key, K2 key and other keys, and outputs a key input signal corresponding to a key operation to the control unit 20.

Here, the K1 key is a key that reverses a flag register F0 described later to start pulse measurement, and the K2 key is a key that reverses a flag register F1 described later to set an identification code.

As will be described later, the serial conversion circuit 30 converts the pulse data and the identification code data output from the control unit 20 into a serial signal and outputs the serial signal to the transmission circuit 31.

The transmission circuit 31 converts a serial signal consisting of pulse data and identification code data input from the serial conversion circuit 30 into a radio signal, and the antenna 32 outputs the serial signal shown in FIG.
To the receiver 4 shown in FIG.

The display drive section 33 outputs a display drive signal to the display section 34 based on the display data input from the control section 20 to drive the display section 34 for display.

For the display unit 34, for example, a liquid crystal display device is used, and displays the present time, pulse, etc.

<Structures of Receiver 4 and Monitoring Device 5> The receiver 4 and the monitoring device 5 of FIG. 1 are configured as shown in FIG. 7, and the receiver 4 includes an antenna 41, a receiving circuit 42, and a parallel circuit. The conversion circuit 43 and the control unit 44 are provided.

The antenna 41 is the antenna 32 of the wristwatch 3.
The wireless signal of the pulse data and the identification code data by the wireless signal transmitted from is received, and the received pulse data and the identification code data are output to the receiving circuit 42.

The receiving circuit 42 operates in synchronization with the operation signal supplied from the control unit 44, and outputs the serial pulse data and the identification code data input from the antenna 41 to the parallel conversion circuit 43.

The parallel conversion circuit 43 converts the serial pulse data and the identification code data input from the receiving circuit 42 into the pulse data and the identification code data of the parallel signal and inputs them to the control section 44.

The control unit 44 includes a CPU (Central Processi).
ng Unit), a ROM, a RAM, and the like, and controls various parts based on a microprogram stored in advance in the ROM to perform various processes. Further, the control unit 44 outputs the pulse data and the identification code data input from the parallel conversion circuit 43 to the monitoring device 5.

That is, the receiver 4 receives the pulse data and the identification code of each subject transmitted from each wristwatch 3 by the antenna 41, performs signal processing, and then sends them to the monitoring device 5.

Although not shown, the monitor 5 includes a monitor controller, a CRT display device, etc., and the controller 4 of the receiver 4 is provided.
Based on the pulse data and identification code data of a plurality of subjects input from 4, the subject's biological condition is monitored and displayed on a CRT display device, or an alarm is generated when the subject is abnormal. That is, the monitoring device 5 collectively displays the pulse data and the identification codes of a plurality of subjects, which are input from the control unit 44 of the receiver 4, on the CRT display device, and the pulse data is out of the predetermined range. Alarm sound is generated.

Next, the operation of this embodiment will be described.

The monitoring system 1 attaches the shirt 2 and the wrist watch 3 to which the electrodes 10a and 10b are attached to a plurality of patients to be monitored, and turns on the power switch 16 provided on the shirt 2. When the power switch 16 is turned on,
The electrodes 10a, 1 attached to the plurality of shirts 2
0b detects the living body (pulse) of the patient and outputs it to the detection circuit 13. The detection circuit 13 amplifies the pulse signal input from the electrodes 10a and 10b and outputs the amplified pulse signal to the transmission circuit 14, and the transmission circuit 14 converts the input pulse signal into an electromagnetic induction signal and outputs each from the transmission coil 17. Wrist watch worn on the patient 3
Send to.

The wristwatch 3 has a function as a timepiece, and performs a measurement process of measuring a pulse by a pulse signal (heart wave signal) transmitted from the shirt 2 and a transfer process of the measured pulse to the receiver 4. Then, the settings of these processes are set by the K1 key, the K2 key and other keys.

That is, each wristwatch 3 constantly monitors the flag F0 and determines whether the flag F0 is "1", that is, in the pulse measurement mode, as shown in FIG. It is checked whether there is any (step S1). That is, the flag F0 is a flag indicating the mode of the wristwatch 3, and when it is "1", it indicates that it is in the pulse measurement mode.

In step S1, when the flag F0 is "1", it is determined that the pulse measuring mode is set, and after the pulse measuring process described later is performed (step S2), the key input unit 29 is scanned, It is checked whether or not a key has been pressed (step S3).

When the flag F0 is not "1" in step S1, it is determined that the pulse measurement mode is not set, and the process proceeds to step S3 to check whether or not the key of the key input unit 29 is pressed (step S3).

In step S3, when the key is not pressed, it is the timing to measure, that is, the frequency division
It is checked whether or not a timing signal has been input from the timing circuit 25 (step S4), and if it is not the timing timing, the contents of the display register of the RAM 26 are transferred to the display drive unit 33, and the display processing for displaying on the display unit 34 is performed to perform the step. The process returns to S1 (step S6).

At step S4, at the timing of the timing, the timing processing for updating the current time data stored in the timing register area of the RAM 26 is performed (step S4).
5) After performing the display process of displaying the result of the clocking process on the display unit 34 (step S6), the process returns to step S1.

When the key is pressed in the above step S3, it is checked whether or not the pressed key is the K1 key (step S7), and when the K1 key is pressed, the flag F0 is inverted (step S8). . That is, by pressing the K1 key, the flag F0 can be inverted and the measurement mode can be set and the measurement mode can be released repeatedly.

When the flag F0 is inverted, a display process for displaying the contents of the display register of the RAM 26 on the display unit 34 is performed (step S6), and the process returns to step S1.

In step S7, if the entered key is not the K1 key, it is checked whether the entered key is the K2 key (step S9). If the K2 key is pressed, the flag F1 is inverted (step S9). S1
0).

The flag F1 is a flag indicating the identification code setting mode, and when it is "1", it indicates the identification code setting mode. Therefore, by pressing the K2 key, the identification code setting mode can be set and released.

When the flag F1 is inverted, the display process is performed (step S6), and the process returns to step S1.

If it is determined in step S9 that the entered key is not the K2 key but another key, it is checked whether the flag F1 is "1", that is, the identification code setting mode (step S11). F1
Is “1”, it is determined that the mode is the identification code setting mode, and the numerical value input from the key input unit 29 is stored in the RAM 2
An identification code setting process for setting an identification code in the identification code register area 6 is performed (step S12).

When the identification code setting process is performed, the display process is performed (step S6), and the process returns to step S1.

When the flag F1 is not "1" in step S11, other processing corresponding to key input, for example, time setting processing is performed (step S1).
3) After performing the display process (step S6), the process returns to step S1 and the same process as described above is performed.

As described above, the wristwatch 3 performs the timekeeping process, and by pressing the K1 key or the K2 key,
It is possible to perform pulse measurement processing and identification code setting processing.

Next, the pulse measuring process in step S2 will be described with reference to the flowchart of the measuring process shown in FIG.

In the pulse measuring process, it is first checked whether or not there is a pulse signal from the shirt 2 (step P1).

When the pulse signal is not received in step P1, the content of the register area T is incremented by "1" and the process is terminated (step P4). That is, by incrementing the content of the register area T at every predetermined timing, the cycle T from the reception of the previous pulse signal to the reception of the current pulse signal is calculated and stored in the register area T.

The pulse signal due to the electromagnetic induction from the shirt 2 is received by the two receiving coils 21a and 21b.
As shown in, the difference between the pulse signal received by the receiving coil 21a and the pulse signal received by the receiving coil 21b is amplified by the differential amplifier OP3 and output to the waveform shaping circuit 23. The waveform shaping circuit 23 waveform-shapes the input pulse signal into a rectangular wave signal and outputs it to the control unit 20. The control unit 20 checks in step P1 whether or not this pulse signal is input.

As described above, in the wristwatch 3, the pulse signal sent from the shirt 2 as the electromagnetic induction signal is received by the two receiving coils 21a and 21b.
Since the difference between the pulse signals received by a and 21b is amplified, as shown in FIG.
Even if the pulse signal (the signal waveform shown in (A) and (B) in FIG. 10) received by is small, these receiving coils 21a, 2
When the difference between the received pulse signals of 1b is amplified by the differential amplifier OP3, the amplified pulse signal SS is shown in FIG. 10 without increasing the amplification factor of the differential amplifier OP3 as in the conventional case.
As shown in (C), a large amplification factor can be obtained and the noise Sn generated in the receiving circuit 22 can be reduced.

As a result, the noise Sn of the output pulse signal SS
It is possible to increase the signal discrimination rate with respect to the pulse signal and to accurately detect the pulse signal.

The pulse signal thus detected is input to the control unit 20, and when the signal is detected in step P1 of FIG. 9, the pulse is calculated (step P2). That is, the cycle T from the previous pulse signal to the current pulse signal is measured by the register area T, and the pulse is calculated based on this cycle.

When the pulse is calculated, the calculated pulse data and the identification code are transmitted (step P3). That is, the control unit 20 outputs the pulse data and the identification code to the serial conversion circuit 30, converts the serial data into a serial signal in the serial conversion circuit 30, and then transmits the wireless signal from the transmission circuit 31 via the antenna 32. After the transmission, the register area T of the RAM 26 is cleared to prepare for the calculation of the next cycle T.

Then, the receiver 4 receives the pulse data and the radio signal of the identification code transmitted from each wristwatch 3 by the antenna 41, converts them into parallel signals, and outputs them to the monitoring device 5.

The monitoring device 5 collectively displays the received pulse data of a plurality of subjects on the CRT display device for each identification code, and monitors the pulse data of each subject based on the identification code to obtain the pulse data. When is outside a predetermined range, an alarm sound is generated.

As described above, in the monitoring system 1 of the present embodiment, the electrodes 10a and 10b of the shirt 2 worn on the human body detect the pulse as the biological signal, and the detected pulse signal is applied to the wristwatch 3 by electromagnetic induction. Send. The wristwatch 3 receives the pulse signal transmitted by electromagnetic induction by the two receiving coils 21 a and 21 b, and the two receiving coils 21 a and 21 b are received.
The receiving circuit 2 receives the difference between the pulse signals received by a and 21b.
It is amplified by the differential amplifier OP3 of 2.

Therefore, the pulse signal is supplied to the differential amplifier OP3.
The amplification factor of the differential amplifier OP can be made smaller than the conventional amplification factor, and the amplification factor of noise generated when amplifying a pulse is made smaller than that of the pulse signal. You can As a result, the signal discrimination ratio of the pulse signal with respect to the noise component can be increased, and even when the shirt 2 and the wristwatch 3 are at a long distance, the pulse signal can be discriminated from the noise to perform accurate living body monitoring. .

Although the above embodiment is applied to the case where the pulse data is constantly monitored, the present invention is not limited to this. For example, every 30 seconds or every 1 minute, a predetermined time is determined. You may make it measure and monitor.

In the above embodiment, pulse data is monitored as the biometric data to be monitored, but the invention is not limited to this. For example, cardiac radio wave data or blood pressure data,
Alternatively, it may be body temperature data or the like, or a plurality of pieces of biometric data may be detected and transmitted by electromagnetic induction in a time division manner, for example.

Further, in the above embodiment, the monitoring device 5 generates an alarm sound when the pulse exceeds the set range, but the alarm unit 28 of the wristwatch 3 may generate an alarm sound. .

Further, not only detection and monitoring of biometric data,
The present invention can be applied to any device that sends and receives signals, information and the like by electromagnetic induction.

[0086]

According to the electromagnetic induction system of the present invention , the amplification circuit amplifies the difference between the signals received in the opposite phase, so that the amplification rate of the amplification circuit can be increased to obtain the same amplification rate as the conventional one. The amplification factor can be made smaller than the conventional amplification factor, and the amplification factor of noise generated by the amplification circuit can be made smaller than the amplification factor of the signal. As a result, the signal discrimination ratio of the signal with respect to the noise component can be increased, and the signal can be reliably discriminated from the noise even when the transmitter and the receiver are located at a long distance.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a monitoring system of the present invention.

FIG. 2 is a diagram showing a configuration of the shirt shown in FIG.

FIG. 3 is a circuit configuration diagram of the electronic circuit of FIG.

FIG. 4 is a circuit block diagram of the wristwatch shown in FIG.

5 is a detailed circuit diagram of the receiving circuit of FIG.

6 is a diagram showing a memory configuration of the RAM of FIG.

7 is a diagram showing a circuit configuration of a receiver and a monitoring circuit of FIG.

8 is a flowchart showing the overall operation of the wristwatch shown in FIG.

9 is a flowchart showing detailed processing of the measurement processing of FIG.

10 is a diagram showing a pulse signal (A) and (B) received by the receiving coil of the wristwatch of FIG. 1 and a pulse signal (C) obtained by amplifying the difference between the pulse signals.

FIG. 11 is a diagram showing an output signal (A) of the amplifier circuit when there is no electromagnetic induction signal of the conventional monitoring system and an output signal (C) of the amplifier circuit when the input signal (B) is input.

[Explanation of symbols] 1 monitoring system 2 shirt 3 watches 4 receiver 5 monitoring equipment 10a, 10b electrodes 11 electronic circuits 13 Detection circuit 14 Transmitter circuit 15 power supply 16 power switch 17 Transmit coil 20 Control unit 21a, 21b receiving coil 22 Receiver circuit 23 Waveform shaping circuit 24 oscillator circuits 25 frequency division / timing circuit 26 RAM 27 ROM 28 Bulletin Club 29 Key input section 30 Serial conversion circuit 31 Transmitter circuit 32 antenna 33 display drive 34 Display Ca, Cb tuning capacitor R1 to R12 resistance OP1, OP2, OP3 differential amplifier 41 antenna 42 Receiver circuit 43 Parallel conversion circuit 44 Control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) A61B 5/00 A61B 5/0245 A61B 5/04

Claims (5)

(57) [Claims] 1. An electromagnetic induction system comprising: a transmitting device for transmitting a signal by electromagnetic induction; and a receiving device for receiving a signal transmitted from the transmitting device by electromagnetic induction, the receiving device comprising: Two coils arranged in a state where they receive signals by electromagnetic induction transmitted by the transmitter in opposite phases to each other , and an amplifier circuit for amplifying a difference between signals received by the two coils are provided. An electromagnetic induction system characterized in that 2. A living body detection device which is attached to a human body, detects a biological signal, and transmits the detected biological signal by electromagnetic induction, and a receiving device which receives the biological signal transmitted from the biological detection device by electromagnetic induction. An electromagnetic induction system comprising: a monitoring unit having a monitoring unit configured to monitor a state of a human body based on a biological signal received by the receiving unit, wherein the receiving unit is the living body detecting device. They are placed so that they receive the biological signals from the electromagnetic induction transmitted by
Electromagnetic induction system comprising: the two coils, an amplifying circuit for amplifying the difference between the biological signals received by the two coils, the that. 3. The living body detection device is at least the heart of the human body.
The electromagnetic induction according to claim 2, wherein the beat is detected.
system. 4. The electromagnetic induction system according to claim 1 , wherein the amplifier circuit is a differential amplifier. 5. The amplifier circuit comprises :
A first operation for differentially amplifying a signal received by one coil.
Differential amplification of the signal received by the amplifier and the other coil
Connect the positive input terminal to the second operational amplifier in common.
The first operational amplifier and the second operational amplifier.
Third operational amplifier that further differentially amplifies the output of the amplifier
2. A differential amplifier including:
The electromagnetic induction system according to claim 4.