Biosignal measurement system

Abstract

Sensor devices (1a, 1b) respectively comprise: amplification units (102a, 102b) that amplify biological potentials detected by electrodes (101a, 101b); FM transmission units (105a, 105b) that modulate carrier waves in accordance with the biological potentials, and wirelessly transmit the modulated signals to another sensor device; FM reception units (106a, 106b) that demodulate the modulated signals transmitted from the other sensor device and extract information about the biological potentials; reference potential generation units (107a, 107b) that generate reference potentials for the amplification units (102a, 102b); and correction units (1064a, 1064b) that correct the oscillation frequency of a voltage-controlled oscillator used in the demodulation by the FM reception units (106a, 106b).

Description

Technical Field

[0001] The present invention relates to a biological signal measurement system for measuring biological signals such as electrocardiogram signals.

Background Art

[0002] In the measurement of an electrocardiogram, which is a type of biopotential measurement, the potential difference between electrodes arranged on both the left and right sides of the human body is measured. The biological signal measurement system is provided in compression wear or the like worn by a person. In the example of FIG. 22, a device 301 is attached to a portion of the compression wear 302 corresponding to the central part of the body, and an electrode 304 provided to contact the left and right waist portions and the device 301 are connected by a wiring 303 that is laid on the compression wear 302 (Non-Patent Document 1).

[0003] Attaching electrodes to the body of the measurement subject as in the example of FIG. 22 causes great discomfort due to a sense of compression and the trouble of wearing, and generates a sense of aversion in the measurement subject. Therefore, as a location other than the body, for example, attaching electrodes to the limbs is conceivable. However, when attaching electrodes to the right and left hands or the right and left feet of the measurement subject, a wiring for connecting between the left and right electrodes is required, so the activity of the measurement subject may be restricted.

[0004] If the wiring can be eliminated, the discomfort of the measurement subject due to the wiring can be reduced, and the restraint on the body of the measurement subject can be eliminated. When separating the devices without wiring, it is important that the potential measurement reference of the left and right devices is shared. If the reference potentials do not match, the measurement accuracy may deteriorate due to this, and biopotential measurement may become difficult.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] The present invention was made to solve the above problems and aims to provide a biosignal measurement system that can easily measure biopotentials in a configuration that eliminates wiring and separates into two devices. [Means for solving the problem]

[0007] The biosignal measurement system of the present invention comprises a first sensor device configured to be attached to one of the right or left side of a person to be measured, and a second sensor device configured to be attached to the other of the right or left side, wherein each of the first and second sensor devices comprises a first electrode configured to contact the skin of the person to be measured, an amplification unit configured to amplify the biopotential detected by the first electrode, a transmission unit configured to modulate a carrier wave according to the biopotential amplified by the amplification unit and wirelessly transmit the modulated signal to the other sensor device, a reception unit configured to demodulate the modulated signal transmitted from the other sensor device and extract biopotential information, a reference potential generation unit configured to generate a reference potential for the amplification unit based on the biopotential amplified by the amplification unit and the biopotential output from the reception unit, and a correction unit configured to correct at least one of the oscillation frequency of a voltage-controlled oscillator used for modulation by the transmission unit and the oscillation frequency of a voltage-controlled oscillator used for demodulation by the reception unit. [Effects of the Invention]

[0008] According to the present invention, by connecting the first sensor device and the second sensor device via wireless communication, the wiring connecting the first sensor device and the second sensor device can be eliminated. This reduces discomfort to the person being measured due to wiring and eliminates physical constraints on the person being measured. Furthermore, in the present invention, by providing a correction unit, at least one of the oscillation frequencies of the voltage-controlled oscillator used for modulation in the transmitting unit and the oscillation frequencies of the voltage-controlled oscillator used for demodulation in the receiving unit can be corrected. This minimizes the variation in oscillation frequencies between the transmitting unit and the receiving unit caused by external environmental influences, and allows the reference potential for potential measurement of the first sensor device and the second sensor device to be common, thereby improving the accuracy of biopotential measurement. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing the configuration of a biosignal measurement system according to a first embodiment of the present invention. [Figure 2] Figure 2 is a circuit diagram showing the configuration of the amplification unit according to the first embodiment of the present invention. [Figure 3] Figure 3 shows an example of individual differences in the oscillation frequency of a VCO. [Figure 4] Figure 4 shows the basic configuration of the FM receiver according to the first embodiment of the present invention. [Figure 5] Figure 5 shows the basic configuration of the VCO of the FM receiver according to the first embodiment of the present invention. [Figure 6] Figure 6 shows a configuration in which a correction unit is added to the VCO of the FM receiver according to the first embodiment of the present invention. [Figure 7] Figure 7 is a flowchart illustrating the adjustment method for the FM receiver according to the first embodiment of the present invention. [Figure 8] Figure 8 is a block diagram showing another configuration of the biosignal measurement system according to the first embodiment of the present invention. [Figure 9]FIG. 9 is a block diagram showing the configuration of a biological signal measurement system according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing another configuration of a biological signal measurement system according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing the basic configuration of an FM transmitter according to a second embodiment of the present invention. [Figure 12] FIG. 12 is a diagram showing a configuration in which a correction unit is added to the VCO of an FM transmitter according to a second embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart for explaining an adjustment method of an FM transmitter according to a second embodiment of the present invention. [Figure 14] FIG. 14 is a block diagram showing the configuration of a biological signal measurement system according to a third embodiment of the present invention. [Figure 15] FIG. 15 is a block diagram showing another configuration of a biological signal measurement system according to a third embodiment of the present invention. [Figure 16] FIG. 16 is a flowchart for explaining an adjustment method of an FM transmitter and an FM receiver according to a third embodiment of the present invention. [Figure 17] FIG. 17 is a diagram for explaining the effect of a third embodiment of the present invention. [Figure 18] FIG. 18 is a flowchart for explaining another adjustment method of an FM transmitter and an FM receiver according to a third embodiment of the present invention. [Figure 19] FIG. 19 is a block diagram showing the configuration of a biological signal measurement system according to a fourth embodiment of the present invention. [Figure 20] FIG. 20 is a block diagram showing the configuration of a biological signal measurement system according to a fifth embodiment of the present invention. [Figure 21] FIG. 21 is a block diagram showing a configuration example of a computer for realizing a biological signal measurement system according to the first to fifth embodiments of the present invention. [Figure 22] FIG. 22 is a diagram showing the configuration of a conventional biological signal measurement system.

MODE FOR CARRYING OUT THE INVENTION

[0010] [First Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a block diagram showing the configuration of a biosignal measurement system according to this embodiment. The biosignal measurement system consists of a sensor device 1a attached to the right side of the person being measured, a sensor device 1b attached to the left side, and a biosignal generation device 2.

[0011] Sensor device 1a includes an electrode 101a that contacts the skin on the right side of the person being measured, an amplification unit 102a that amplifies the biopotential detected by electrode 101a, an AD conversion unit 103a that converts the amplified biopotential into digital data, a wireless transmission unit 104a that wirelessly transmits the digital data output from the AD conversion unit 103a to the biosignal generation device 2, and FM (Frequency Modulation) for frequency modulating a carrier wave according to the biopotential amplified by the amplification unit 102a and transmitting the modulated signal to sensor device 1b. The system includes a Modulation) Transmitter 105a, an FM receiver 106a that demodulates the modulated signal transmitted from the sensor device 1b to extract biopotential information, a reference potential generator 107a that generates a reference potential for the amplifier 102a, a power supply 108a that supplies power to the amplifier 102a, the AD converter 103a, the wireless transmitter 104a, the FM transmitter 105a, the FM receiver 106a, and the reference potential generator 107a, a transmitting antenna 109a for wirelessly transmitting the modulated signal output from the FM transmitter 105a to the sensor device 1b, and a receiving antenna 110a for receiving the modulated signal transmitted from the sensor device 1b.

[0012] The sensor device 1b includes an electrode 101b that contacts the skin on the left side of the person being measured, an amplification unit 102b that amplifies the biopotential detected by the electrode 101b, an AD conversion unit 103b that converts the amplified biopotential into digital data, a wireless transmission unit 104b that wirelessly transmits the digital data output from the AD conversion unit 103b to the biosignal generation device 2, an FM transmission unit 105b that frequency modulates a carrier wave according to the biopotential amplified by the amplification unit 102b and transmits the modulated signal to the sensor device 1a, and the signal transmitted from the sensor device 1a The system includes an FM receiving unit 106b that demodulates the modulated signal to extract biopotential information, a reference potential generation unit 107b that generates a reference potential for the amplification unit 102b, a power supply 108b that supplies power to the amplification unit 102b, the AD conversion unit 103b, the wireless transmission unit 104b, the FM transmission unit 105b, the FM receiving unit 106b, and the reference potential generation unit 107b, a transmitting antenna 109b for wirelessly transmitting the modulated signal output from the FM transmission unit 105b to the sensor device 1a, and a receiving antenna 110b for receiving the modulated signal transmitted from the sensor device 1a.

[0013] The biosignal generation device 2 includes a wireless receiving unit 200 that receives digital data transmitted from sensor devices 1a and 1b, a calculation unit 201 that calculates an electrocardiogram signal, and a storage unit 202 that stores the electrocardiogram signal calculated by the calculation unit 201.

[0014] When measuring electrocardiogram signals as biosignals, it is necessary to place multiple electrodes 101a and 101b in positions that surround the heart of the person being measured. For a comfortable measurement site for the person being measured, it is conceivable to attach the sensor devices 1a and 1b to at least two locations on the limbs. By adopting this mounting configuration for the sensor devices 1a and 1b, the feeling of pressure and discomfort caused by wearing clothing can be significantly reduced. Furthermore, this biosignal measurement system can be applied not only to electrocardiograms but also to the measurement of electromyography and electroencephalography.

[0015] In this embodiment, the sensor devices 1a and 1b are, for example, in the shape of gloves, rings, socks, slippers, or wristbands. The person being measured wears the sensor devices 1a and 1b by putting gloves or rings on their right and left hands, respectively. Alternatively, the person being measured wears the sensor devices 1a and 1b by putting socks on their right and left feet, respectively, or by putting slippers on their right and left feet, respectively. Alternatively, the person being measured wears the sensor devices 1a and 1b by putting wristbands on their right and left hands, respectively.

[0016] Various electrodes made of different materials and configurations can be used for electrodes 101a and 101b. These include Ag / AgCl electrodes used in medical applications, conductive cloth electrodes, metal electrodes, and any other suitable material. By using cloth or metal electrodes that do not need to be directly attached to the subject's body, a non-contact electrode configuration where the electrodes are worn over clothing can be achieved, further increasing the subject's freedom of movement.

[0017] Since the biopotential detected by electrodes 101a and 101b is a very weak signal, signal amplification by amplifiers 102a and 102b is necessary. Amplifiers 102a and 102b require high input impedance to reduce the loss of biopotential. Inverting amplifier circuits have a resistance that determines the input impedance, which also affects the gain setting and contributes as thermal noise, thus lowering the signal-to-noise ratio of the biopotential. On the other hand, non-inverting amplifier circuits have the characteristic that noise does not increase easily even with a high input impedance configuration. Therefore, it is effective to use non-inverting amplifier circuits as amplifiers 102a and 102b. Alternatively, a low-pass filter may be provided in amplifiers 102a and 102b.

[0018] When non-inverting amplifier circuits are used as the amplifiers 102a and 102b, it is important that the reference potentials of the two amplifiers 102a and 102b are common. In this embodiment, since the sensor devices 1a and 1b are not connected by wiring, the reference potentials of the amplifiers 102a and 102b may not match, which may lead to a deterioration in measurement accuracy.

[0019] Therefore, in this embodiment, in order to improve the measurement accuracy of the electrocardiogram, biopotential information is transmitted and received between sensor devices 1a and 1b, thereby commonizing the reference potential Vref in the amplification units 102a and 102b of each sensor device 1a and 1b.

[0020] As described later, the biopotential detected by the electrode 101b of sensor device 1b and amplified by the amplification unit 102b is wirelessly transmitted to sensor device 1a by the FM transmission unit 105b. The FM receiver 106a of sensor device 1a demodulates the signal transmitted from sensor device 1b and received by the receiving antenna 110a to extract biopotential information.

[0021] The reference potential generation unit 107a of the sensor device 1a generates a reference potential Vref by calculating the average of the biopotential detected by the electrode 101a and amplified by the amplification unit 102a and the biopotential output from the FM receiver unit 106a (biopotential transmitted from sensor device 1b).

[0022] Figure 2 is a circuit diagram showing an example configuration of the amplifier section 102a. The amplifier section 102a consists of an operational amplifier A1 and resistors R1 and R2. The reference potential Vref is supplied from the reference potential generation unit 107a to one end of resistor R1 of the amplifier section 102a.

[0023] Meanwhile, the biopotential detected by the electrode 101a of sensor device 1a and amplified by the amplification unit 102a is wirelessly transmitted to sensor device 1b by the FM transmission unit 105a. The FM receiver 106b of sensor device 1b demodulates the signal transmitted from sensor device 1a and received by the receiving antenna 110b to extract biopotential information.

[0024] The reference potential generation unit 107b of the sensor device 1b generates a reference potential Vref by calculating the average of the biopotential detected by electrode 101b and amplified by amplifier 102b and the biopotential output from FM receiver 106b (biopotential transmitted from sensor device 1a), and supplies the reference potential Vref to amplifier 102b. The configuration of amplifier 102b is the same as that of amplifier 102a. Each of the reference potential generation units 107a and 107b is preferably configured with, for example, a single-stage operational amplifier.

[0025] The AD conversion unit 103a of the sensor device 1a converts the biopotential amplified by the amplification unit 102a into digital data. The wireless transmission unit 104a wirelessly transmits the biopotential data output from the AD conversion unit 103a to the biosignal generation device 2.

[0026] Similarly, the AD conversion unit 103b of the sensor device 1b converts the biopotential amplified by the amplification unit 102b into digital data. The wireless transmission unit 104b wirelessly transmits the biopotential data output from the AD conversion unit 103b to the biosignal generation device 2.

[0027] Any wireless communication standard can be applied between the wireless transmitters 104a and 104b and the wireless receiver 200 of the biosignal generator 2, including carrier communication, Wi-Fi (registered trademark), and Bluetooth (registered trademark). When using a short-range communication standard such as Bluetooth, the biosignal generator 2 can be a smartphone or other device that is close to the person being measured. When using Wi-Fi or similar standards, the biosignal generator 2 can be a server or other device.

[0028] The calculation unit 201 of the biosignal generation device 2 calculates the difference between the biopotential transmitted from sensor device 1a and the biopotential transmitted from sensor device 1b as an electrocardiogram signal. The electrocardiogram signal is stored in the memory unit 202.

[0029] Next, the FM transmission and reception between sensor devices 1a and 1b in this embodiment will be described in more detail. The FM transmission unit 105a of sensor device 1a modulates the carrier wave with FM according to the biopotential amplified by the amplification unit 102a and transmits the modulated signal from the transmitting antenna 109a to sensor device 1b. The FM reception unit 106a of sensor device 1a demodulates the modulated signal transmitted from sensor device 1b and received by the receiving antenna 110a to extract biopotential information.

[0030] Similarly, the FM transmitter 105b of sensor device 1b modulates the carrier wave with FM according to the biopotential amplified by the amplifier 102b and transmits the modulated signal from the transmitting antenna 109b to sensor device 1a. The FM receiver 106b of sensor device 1b demodulates the modulated signal transmitted from sensor device 1a and received by the receiving antenna 110b to extract biopotential information.

[0031] In this embodiment, a voltage-controlled oscillator (VCO) is used for FM modulation of the carrier wave in the FM transmitters 105a and 105b, and a phase-locked loop (PLL) is used for demodulation in the FM receivers 106a and 106b. The VCO generally changes its oscillation frequency using a varactor diode whose capacitance changes with voltage. The oscillation frequency f of the VCO is expressed by the following equation and is determined by the resonant frequency due to the inductance L and capacitance C.

[0032]

number

[0033] Capacitance C is often composed of a varactor diode and multiple capacitors. Furthermore, VCOs are also used as components of the PLL in the FM receivers 106a and 106b. Therefore, it is necessary to set the oscillation frequencies of the VCOs in the FM transmitters 105a and 105b and the FM receivers 106a and 106b to be the same.

[0034] However, the oscillation frequency can change due to variations in the precision and individual differences of the VCO components, meaning that the oscillation frequency may differ between the transmitting and receiving sides. Figure 3 shows an example of individual differences in VCO oscillation frequency. Here, the control voltage-oscillation frequency characteristics of five VCOs, VCOs 300-1 to 300-5, are shown. Although all VCOs use the same components in their design and should theoretically exhibit the same control voltage-oscillation frequency characteristics, significant individual differences are observed.

[0035] In the example shown in Figure 3, an offset error of approximately 200 kHz occurs between VCO300-2 and 300-5, which translates to a voltage error of about 1V. Considering that the circuit voltage used in wearable devices is 3V to 5V, this error represents more than 20% of the circuit voltage, which has a very significant impact on the measurement results.

[0036] In this embodiment, the reference potential Vref of the amplification units 102a and 102b is matched by transmitting and receiving biopotentials detected by sensor devices 1a and 1b, thereby improving the measurement accuracy of the electrocardiogram signal. However, if the biopotentials detected by sensor devices 1a and 1b cannot be properly demodulated, the measurement accuracy of the electrocardiogram signal deteriorates significantly, making it extremely important to correct the error in the oscillation frequency of the VCO.

[0037] One possible correction method is to add an offset to the reference potential Vref generated by the reference potential generation units 107a and 107b, or to adjust the slope of the VCO control voltage-oscillation frequency by adjusting the amplification of the reference potential generation units 107a and 107b. However, this correction method uses a first-order correction function, which requires solving for two variables: the slope and intercept of the VCO control voltage-oscillation frequency, making the process complex. Furthermore, to make the slope of the VCO control voltage-oscillation frequency less than 1, an inverting amplifier circuit, for example, is required, but inverting the output causes the noise gain to become greater than the signal gain, increasing the noise.

[0038] Furthermore, when variable resistors are used to adjust the amplification of the reference potential generation units 107a and 107b, the correction may shift over time due to drift caused by changes in time and temperature. Also, if the difference in the oscillation frequencies of the VCOs is large, the control voltage corresponding to the oscillation frequency may saturate at the value of the power supply voltage (GND or VDD), making it impossible to obtain the information needed to calculate the first-order correction function, and thus correction may not be possible.

[0039] Therefore, correcting the VCO's oscillation frequency itself is the solution. Furthermore, as shown in Figure 3, although there are significant individual differences in the VCOs, the rate of change of the oscillation frequency with respect to the control voltage has less individual variation compared to the oscillation frequency offset, and the slope of the control voltage-oscillation frequency is almost constant.

[0040] Therefore, in this embodiment, correction is performed by changing the offset of the oscillation frequency. Specifically, correction units 1064a and 1064b are provided in the VCOs of the FM receiving units 106a and 106b of the sensor devices 1a and 1b.

[0041] Figure 4 shows the basic configuration of the FM receiver 106a. As described above, the FM receiver 106a has a PLL configuration and consists of a VCO 1060a, a phase comparison unit 1061a that compares the phase of the modulated signal Vs received by the receiving antenna 110a with the output signal Vo of the VCO 1060a, a low-pass filter (LPF) 1062a that outputs the result of low-pass filtering of the output signal Ve of the phase comparison unit 1061a as demodulated biopotential, and a correction unit 1064a. The output of the LPF 1062a is input to the VCO 1060a as a control voltage Vctl. The configuration of the FM receiver 106b is the same as that of the FM receiver 106a.

[0042] Note that the configuration in Figure 4 is just one example, and the FM receivers 106a and 106b are not limited to the configuration in Figure 4. For example, an amplifier may be inserted between the LPF 1062a and the VCO 1060a, and the voltage obtained by amplifying the biopotential output from the LPF 1062a may be used as the control voltage Vctl for the VCO 1060a.

[0043] Figure 5 shows the basic configuration of VCO1060a. VCO1060a consists of a varactor diode D1, capacitors C1 and C2, inductor L1, and amplifier 1065. The capacitance fluctuation component due to the varactor diode D1 and capacitor C1 is C var The constant component of capacitance due to capacitor C2 is C const If the inductance of inductor L1 is L, the oscillation frequency f of VCO1060a is given by the following equation.

[0044]

number

[0045] When the inductance L is changed, the coefficient of the fluctuating component also changes, making it difficult to obtain the desired frequency characteristics. Therefore, capacitance C const It is efficient to change the oscillation frequency f by changing [a specific parameter].

[0046] Figure 6 shows a configuration in which a correction unit 1064a is added to the VCO 1060a. The oscillation frequency f of the VCO 1060a decreases when the capacitance is increased and increases when the capacitance is decreased. Therefore, by providing variable capacitors C3 and C4 in series and parallel with capacitor C1 as the correction unit 1064a, the offset of the oscillation frequency f of the VCO 1060a can be changed.

[0047] The variable capacitances C3 and C4 can be constructed using varactor diodes, MEMS (Micro Electro Mechanical Systems) variable capacitors, or an array of capacitors. In circuit configurations using discrete components, implementation using varactor diodes or MEMS variable capacitors is advantageous because it requires fewer components and is easy to control. On the other hand, when integrating the circuit into an LSI (Large Scale Integration), using a capacitor array as the variable capacitances C3 and C4 is preferable because it is easier to implement. The configuration of the correction unit 1064b is the same as that of the correction unit 1064a.

[0048] It goes without saying that the configurations of the FM receivers 106a and 106b and the correction units 1064a and 1064b are not limited to those shown in Figures 4 to 6, and other circuit configurations that perform similar functions are also acceptable.

[0049] Figure 7 is a flowchart illustrating the adjustment method for the FM receivers 106a and 106b (correction units 1064a and 1064b). First, the operator attempting to adjust the FM receivers 106a and 106b applies a predetermined voltage x [V] to the FM transmitter 105a of the sensor device 1a, modulating the carrier wave according to the voltage x [V] and transmitting the modulated signal from the transmitting antenna 109a to the sensor device 1b (Figure 7, step S100).

[0050] The FM receiver 106b of sensor device 1b demodulates the modulated signal transmitted from sensor device 1a and received by the receiving antenna 110b, and outputs a voltage y[V] (Figure 7, step S101). Due to the error in the VCO of the FM receiver 106b, the voltage y[V] differs from the original x[V]. Therefore, the operator adjusts the value of the variable capacitance of the correction unit 1064b so that the output voltage y[V] of the VCO matches x[V] (Figure 7, step S102). The value of the variable capacitance can be set by the control voltage Vctl2.

[0051] Next, the operator applies a voltage x[V] to the FM transmitter 105b of the sensor device 1b, modulating the carrier wave according to the voltage x[V], and transmitting the modulated signal from the transmitting antenna 109b to the sensor device 1a (Figure 7, step S103).

[0052] The FM receiver 106a of sensor device 1a demodulates the modulated signal transmitted from sensor device 1b and received by the receiving antenna 110a and outputs a voltage y [V] (Figure 7, step S104). The operator adjusts the values ​​of the variable capacitors C3 and C4 of the correction unit 1064a so that the output voltage y [V] of the VCO of the FM receiver 106a matches x [V] (Figure 7, step S105).

[0053] With the above steps complete, the adjustment of the FM receivers 106a and 106b (correction units 1064a and 1064b) is finished, and the oscillation frequency of the VCO has been corrected, so measurement of biological signals can be started. In the example in Figure 7, the FM receiver 106b of sensor device 1b is adjusted first, and then the FM receiver 106a of sensor device 1a is adjusted, but the order can be reversed, or they can be adjusted simultaneously.

[0054] In particular, when performing adjustments simultaneously, it is preferable to use different frequencies for the modulated signal transmitted from sensor device 1a to sensor device 1b and the modulated signal transmitted from sensor device 1b to sensor device 1a. This is because using the same frequency increases the likelihood of mutual interference. By increasing the number of frequencies used, the present invention makes it possible to use not only a paired configuration of sensor devices but also a greater number of sensor devices.

[0055] As in this embodiment, the configuration of providing correction units 1064a and 1064b in the FM receiving units 106a and 106b is particularly suitable when performing human body communication using the body of the person being measured as a transmission path. In the case of general wireless communication that transmits radio waves through the air, there is a possibility of incorrect correction being performed to match unwanted modulated signals flying around in space. Also, the permissible radio wave intensity differs depending on the frequency band. Therefore, there is a risk that the correction may be performed by falling into a frequency band with strict intensity limits due to an error in the oscillation frequency.

[0056] On the other hand, human body communication is less susceptible to external environmental influences. Furthermore, since there is less electric field radiation to the external environment, there is no need to adjust the transmission frequency to a specific frequency as in radio communication. Instead, the oscillation frequency of the VCOs of the FM receivers 106a and 106b only needs to be adjusted to match the transmission frequency of the sensor devices 1a and 1b, allowing for a correction function to be implemented with a simple mechanism.

[0057] Figure 8 shows the configuration of a biosignal measurement system when using human body communication. In the configuration of Figure 8, electrodes 109a' and 110a' that come into contact with the skin on the right side of the person being measured are provided instead of the antennas 109a and 110a in Figure 1. Also, electrodes 109b' and 110b' that come into contact with the skin on the left side of the person being measured are provided instead of the antennas 109b and 110b.

[0058] In the configuration shown in Figure 8, the FM transmitter 105a of the sensor device 1a modulates the carrier wave with FM according to the biopotential amplified by the amplifier 102a, and transmits the modulated signal from the electrode 109a' through the body of the person being measured to the sensor device 1b. The FM receiver 106a demodulates the modulated signal transmitted from the sensor device 1b and received by the electrode 110a' to extract biopotential information.

[0059] Similarly, the FM transmitter 105b of the sensor device 1b modulates the carrier wave with FM in accordance with the biopotential amplified by the amplifier 102b, and transmits the modulated signal from the electrode 109b' through the body of the person being measured to the sensor device 1a. The FM receiver 106b demodulates the modulated signal transmitted from the sensor device 1a and received by the electrode 110b' to extract biopotential information.

[0060] Power for communication accounts for a large portion of the power consumption of sensor devices 1a and 1b. In spatial propagation using radio waves, signal strength attenuates inversely proportional to the square of the propagation distance. On the other hand, in the case of human body communication, the signal attenuation is limited to inversely proportional to the propagation distance. Therefore, by using human body communication, it is possible to transmit data with less transmission power. By transmitting and receiving data via the human body, it is possible to contribute to reducing power consumption.

[0061] As described above, in this embodiment, the oscillation frequencies of the VCOs of the FM receivers 106a and 106b can be corrected, so that the variation in the oscillation frequencies of the FM transmitters 105a and 105b and the FM receivers 106a and 106b caused by external environmental influences can be minimized, and the reference potential for potential measurement of the sensor devices 1a and 1b can be made common, thereby improving the measurement accuracy of biopotential. In this embodiment, it is not necessary to specify the exact oscillation frequencies of the FM transmitter of one sensor device and the FM receiver of the other sensor device, and it is sufficient to match the oscillation frequencies of the FM transmitter and FM receiver, so that correction can be achieved at low cost with a simple circuit.

[0062] [Second Example] In the configurations shown in Figures 1 and 8, correction units 1064a and 1064b are provided in the VCOs of the FM receiving units 106a and 106b of the sensor devices 1a and 1b. However, the correction units may also be provided in the VCOs of the FM transmitting units 105a and 105b. Figure 9 shows the configuration in Figure 1 where correction units 1054a and 1054b are provided in the VCOs of the FM transmitting units 105a and 105b, and Figure 10 shows the configuration in Figure 8 where correction units 1054a and 1054b are provided in the VCOs of the FM transmitting units 105a and 105b.

[0063] Figure 11 shows the basic configuration of the FM transmitter 105a in the configurations shown in Figures 9 and 10. The FM transmitter 105a consists of a VCO 1050a, a crystal oscillator 1051a that outputs a carrier wave Vc, a phase comparison unit 1052a that compares the phase of the carrier wave Vc with the output signal Vo of the VCO 1050a, an LPF 1053a that outputs the result of low-pass filtering of the output signal Ve of the phase comparison unit 1052a, and a correction unit 1054a. The signal obtained by mixing the output signal of the LPF 1053a and the biopotential Vs2 amplified by the amplification unit 102a is input to the VCO 1050a as a control voltage Vctl. The output signal Vo of the VCO 1050a is output to the transmitting antenna 109a or electrode 109a' as a modulated signal. The configuration of the FM transmitter 105b is the same as that of the FM transmitter 105a.

[0064] Note that the configuration in Figure 11 is just one example, and the FM transmitters 105a and 105b are not limited to the configuration in Figure 11. For example, an amplifier may be inserted between the VCO 1050a and the transmitting antenna 109a or electrode 109a' to amplify the modulated signal. Alternatively, frequency dividers may be inserted between the crystal oscillator 1051a and the phase comparison unit 1052a, and between the VCO 1050a and the phase comparison unit 1052a.

[0065] Figure 12 shows the configuration with the correction unit 1054a added to the VCO 1050a. The configuration of the VCO 1050a is the same as that of the VCO 1060a, and the configuration of the correction unit 1054a is the same as that of the correction unit 1064a, so the explanation is omitted. The configuration of the correction unit 1054b is the same as that of the correction unit 1054a.

[0066] Figure 13 is a flowchart illustrating the adjustment method for the FM transmitters 105a and 105b (correction units 1054a and 1054b) of this embodiment. First, an operator attempting to adjust the FM transmitters 105a and 105b applies a predetermined voltage x [V] to the FM transmitter 105a of the sensor device 1a, modulating the carrier wave according to the voltage x [V], and transmitting the modulated signal from the transmitting antenna 109a or electrode 109a' to the sensor device 1b (Figure 13, step S200).

[0067] The FM receiver 106b of sensor device 1b demodulates the modulated signal transmitted from sensor device 1a and received by the receiving antenna 110b or electrode 110b' and outputs a voltage y [V] (Figure 13, step S201). The operator adjusts the values ​​of the variable capacitors C3 and C4 of the correction unit 1054a of FM transmitter 105a so that the output voltage y [V] of the FM receiver 106b matches x [V] (Figure 13, step S202). The values ​​of the variable capacitors can be set by the control voltage Vctl2.

[0068] Next, the operator applies a voltage x[V] to the FM transmitter 105b of the sensor device 1b, modulating the carrier wave with FM according to the voltage x[V], and causing the modulated signal to be transmitted from the transmitting antenna 109b or electrode 109b' to the sensor device 1a (Figure 13, step S203).

[0069] The FM receiver 106a of sensor device 1a demodulates the modulated signal transmitted from sensor device 1b and received by the receiving antenna 110a or electrode 110a' and outputs a voltage y [V] (Figure 13, step S204). The operator adjusts the value of the variable capacitance of the correction unit 1054b of FM transmitter 105b so that the output voltage y [V] of the FM receiver 106a matches x [V] (Figure 13, step S205).

[0070] With the above steps complete, the adjustment of the FM transmitters 105a and 105b (correction units 1054a and 1054b) is finished, and the oscillation frequency of the VCO has been corrected, so measurement of biological signals can be started. In the example in Figure 13, the FM transmitter 105a of sensor device 1a is adjusted first, and then the FM transmitter 105b of sensor device 1b is adjusted, but the order may be reversed, or they may be adjusted simultaneously. As explained in the first embodiment, it is preferable that the modulated signal transmitted from sensor device 1a to sensor device 1b and the modulated signal transmitted from sensor device 1b to sensor device 1a have different frequencies.

[0071] [Third embodiment] In the first and second embodiments, the correction unit is provided in either the FM transmission unit or the FM reception unit, but it is also possible to provide the correction unit in both the FM transmission unit and the FM reception unit.

[0072] Figure 14 is a block diagram showing the configuration of the biosignal measurement system according to this embodiment. The configuration of the FM receivers 106a and 106b is as described in the first embodiment, and the configuration of the FM transmitters 105a and 105b is as described in the second embodiment. Figure 15 shows the configuration of the biosignal measurement system when using human body communication.

[0073] This embodiment increases the correction amount when correction cannot be completed using the methods of the first and second embodiments. Due to the variation range of the variable capacitance of the correction units 1054a, 1054b, 1064a, and 1064b, and variations in the modulators and demodulators, it may not be possible to obtain a sufficient correction amount. Therefore, in this embodiment, in addition to the correction units 1064a and 1064b of the FM receiver units 106a and 106b, correction units 1054a and 1054b are also added to the FM transmitter units 105a and 105b.

[0074] Figure 16 is a flowchart illustrating the adjustment method for the FM transmitters 105a, 105b and FM receivers 106a, 106b (correction units 1054a, 1054b, 1064a, 1064b) in this embodiment. This flowchart shows the case where the correction of sensor device 1b is insufficient.

[0075] First, the operator applies a predetermined voltage x1 [V] to the FM transmitter 105a of the sensor device 1a, modulating the carrier wave with FM according to the voltage x1 [V], and causing the modulated signal to be transmitted from the transmitting antenna 109a or electrode 109a' to the sensor device 1b (Figure 16, step S300).

[0076] The FM receiver 106b of sensor device 1b demodulates the modulated signal transmitted from sensor device 1a and received by the receiving antenna 110b or electrode 110b' and outputs a voltage y1 [V] (Figure 16, step S301). The operator adjusts the value of the variable capacitance of the correction unit 1064b so that the output voltage y1 [V] of the FM receiver 106b matches x1 [V] (Figure 16, step S302).

[0077] Next, the operator applies a predetermined voltage x2 [V] to the FM transmitter 105b of the sensor device 1b, modulating the carrier wave according to the voltage x2 [V], and transmitting the modulated signal from the transmitting antenna 109b or electrode 109b' to the sensor device 1a (Figure 16, step S303).

[0078] The FM receiver 106a of sensor device 1a demodulates the modulated signal transmitted from sensor device 1b and received by the receiving antenna 110a or electrode 110a' and outputs a voltage y2 [V] (Figure 16, step S304). The operator adjusts the values ​​of the variable capacitors C3 and C4 of the correction unit 1064a so that the output voltage y2 [V] of the FM receiver 106a matches x2 [V] (Figure 16, step S305). As described in the first embodiment, the adjustments in steps S300 to S302 and the adjustments in steps S303 to S305 may be performed simultaneously.

[0079] Here, even if the value of the variable capacitance of the correction unit 1064b is adjusted, the output voltages y1[V] and x1[V] of the FM receiver unit 106b do not match, and the correction is not completed. The operator applies a predetermined arbitrary voltage α2[V] to the FM transmitter unit 105b of the sensor device 1b, which has not been corrected, and modulates the carrier wave according to the voltage α2[V], causing the modulated signal to be transmitted from the transmitting antenna 109b or electrode 109b' to the sensor device 1a (Figure 16, step S306).

[0080] The FM receiver 106a of sensor device 1a demodulates the modulated signal transmitted from sensor device 1b and received by the receiving antenna 110a or electrode 110a' and outputs a voltage β2 [V] (Figure 16, step S307).

[0081] If the output voltage β2[V] of the FM receiver 106a is above a certain threshold voltage Vth[V], the operator adjusts the VCO 1050a of the FM transmitter 105a to increase its oscillation frequency, that is, to decrease the values ​​of the variable capacitors C3 and C4 of the correction unit 1054a. Conversely, if the output voltage β2[V] of the FM receiver 106a is below the threshold voltage Vth[V], the operator adjusts the VCO 1050a to decrease its oscillation frequency, that is, to increase the values ​​of the variable capacitors C3 and C4 of the correction unit 1054a (Figure 16, step S308). The threshold voltage Vth can be, for example, Vdd / 2 (where Vdd is the power supply voltage).

[0082] The correction amount of the correction unit 1054a at this time may be the maximum selectable amount. If the correction amounts for transmission and reception are all equal, the correction amount of the correction unit 1054a can be changed to the maximum amount, thus eliminating the need for numerous repetitive adjustment operations and simplifying the adjustment process. The processing in steps S309 to S311 in Figure 16 is the same as in steps S300 to S302.

[0083] With the above steps complete, the adjustments to the FM transmitters 105a and 105b and the FM receivers 106a and 106b (correction units 1054a, 1054b, 1064a, and 1064b) are finished, and the oscillation frequency of the VCO has been corrected, so we can start measuring biological signals.

[0084] Assume that the control voltage-oscillation frequency characteristics of the VCO of the FM receiver 106b of sensor device 1b are in the range of f2H to f2L as shown in Figure 17, and the control voltage-oscillation frequency characteristics of the VCO of the FM transmitter 105a of sensor device 1a are in the range of f1H to f1L. In this case, even if the oscillation frequency f2 of the VCO of the FM receiver 106b is adjusted to the lower limit value f2L by the correction unit 1064b, it will not reach the oscillation frequency f1 of the VCO of the FM transmitter 105a of sensor device 1a.

[0085] However, by adjusting the oscillation frequency f1 of the VCO of the FM transmitter 105a to the upper limit value f1H using the correction unit 1054a, the upper limit value f1H falls within the correction range of the sensor device 1b, thus enabling complete correction. The same logic applies to correction even if the relative magnitudes of the frequencies differ.

[0086] According to this embodiment, by providing correction units in both the FM transmitting unit and the FM receiving unit, the amount of correction in both the FM transmitting unit and the FM receiving unit can be reduced. Capacitance C explained in equation (2) const If you correct it too much, capacitance C const and C var The ratio between the two can be disrupted, potentially causing a shift in the slope of the VCO control voltage-oscillation frequency characteristic between the FM transmitter and FM receiver. This embodiment makes it possible to suppress such a shift in slope.

[0087] If, even after adjusting the variable capacitance value of the correction unit 1064a, the output voltages y2[V] and x2[V] of the FM receiver unit 106a do not match and the correction is not completed, the adjustment described in Figure 18 should be performed. The processing of steps S300 to S305 in Figure 18 is as described in Figure 16.

[0088] The operator applies a predetermined voltage α1 [V] to the FM transmitter 105a of the sensor device 1a whose correction has not been completed, modulates the carrier wave according to the voltage α1 [V], and transmits the modulated signal from the transmitting antenna 109a or electrode 109a' to the sensor device 1b (Figure 18, step S312).

[0089] The FM receiver 106b of sensor device 1b demodulates the modulated signal transmitted from sensor device 1a and received by the receiving antenna 110b or electrode 110b' and outputs a voltage β1 [V] (Figure 18, step S313).

[0090] If the output voltage β1[V] of the FM receiver 106b is greater than or equal to the threshold voltage Vth[V], the operator adjusts the VCO oscillation frequency of the FM transmitter 105b in the direction of increasing it, that is, by decreasing the value of the variable capacitance of the correction unit 1054b. Also, if the output voltage β1[V] of the FM receiver 106b is less than the threshold voltage Vth[V], the operator adjusts the VCO oscillation frequency of the FM transmitter 105b in the direction of decreasing it, that is, by increasing the value of the variable capacitance of the correction unit 1054b (Figure 18, step S314). The processing in steps S315 to S317 in Figure 18 is the same as in steps S303 to S305.

[0091] [Fourth embodiment] In the first to third embodiments, a biosignal generator 2 is provided separately from the sensor devices 1a and 1b, but the configuration of the biosignal generator 2 may be implemented in either sensor device 1a or 1b. Figure 19 is a block diagram showing the configuration of the biosignal measurement system in this embodiment.

[0092] In the configuration shown in Figure 19, the wireless transmitter 104b of the sensor device 1b is unnecessary. The wireless receiver 200 provided on the sensor device 1b receives biopotential data transmitted from the sensor device 1a. The calculation unit 201 calculates the difference between the biopotential transmitted from the sensor device 1a and the biopotential output from the AD conversion unit 103b as an electrocardiogram signal. The electrocardiogram signal is stored in the memory unit 202.

[0093] In this embodiment, since there is no need to provide a biosignal generator 2 separately from the sensor devices 1a and 1b, the person being measured does not need to carry the biosignal generator 2 with them, thus improving the convenience of the person being measured.

[0094] In the example shown in Figure 19, the configuration of the biosignal generator 2 is provided on sensor device 1b, but it goes without saying that it could also be provided on sensor device 1a. Furthermore, while the configuration in Figure 19 shows an example where this embodiment is applied to the configuration in Figure 1, this embodiment may also be applied to the configurations in Figures 8 to 10, 14, and 15.

[0095] [Fifth Example] In the first to fourth embodiments, adjustments are made wirelessly even during the adjustment period before the start of measurement of biological signals. However, wired connection parts may be provided on the sensor devices 1a and 1b, and adjustments may be made via wired communication. Figure 20 is a block diagram showing the configuration of the biological signal measurement system in this embodiment.

[0096] Sensor device 1a includes an electrode 101a, an amplification unit 102a, an AD conversion unit 103a, a wireless transmission unit 104a, an FM transmission unit 105a, an FM reception unit 106a, a reference potential generation unit 107a, a power supply 108a, a transmitting antenna 109a, a receiving antenna 110a, and wired connection units 111a and 112a for wired communication with sensor device 1b.

[0097] Sensor device 1b includes an electrode 101b, an amplification unit 102b, an AD conversion unit 103b, a wireless transmission unit 104b, an FM transmission unit 105b, an FM reception unit 106b, a reference potential generation unit 107b, a power supply 108b, a transmitting antenna 109b, a receiving antenna 110b, and wired connection units 111b and 112b for wired communication with sensor device 1a.

[0098] According to this embodiment, for example, sensor devices 1a and 1b can be wired together and adjusted within a case that houses a pair of sensor devices 1a and 1b. The power supplies 108a and 108b for sensor devices 1a and 1b are batteries, and a device for charging the batteries is required. Therefore, when sensor devices 1a and 1b are placed in the charging case, the wired connection parts 111a and 112b are connected by wiring inside the charging case at the same time as the batteries are charged, and the wired connection parts 111b and 112a are connected.

[0099] The adjustment method differs from the first to fourth embodiments in that the wireless communication in steps S100, S103 in Figure 7, steps S200, S203 in Figure 13, steps S300, S303, S306, S309 in Figure 16, and steps S300, S303, S312, S315 in Figure 18 is replaced with wired communication.

[0100] The configuration in Figure 20 shows an example where this embodiment is applied to the configuration in Figure 1, but this embodiment may also be applied to the configurations in Figures 8 to 10, 14, 15, and 19. Furthermore, sensor devices 1a and 1b may be connected by wiring without using a charging case.

[0101] The arithmetic unit 201 and storage unit 202 described in the first to fifth embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 21.

[0102] The computer comprises a CPU 400, a storage device 401, and an interface device (I / F) 402. Hardware such as the wireless receiver 200 is connected to the I / F 402. A program for implementing the method of the present invention is stored in the storage device 401. The CPU 400 executes the processing described in the first to fifth embodiments according to the program stored in the storage device 401. In addition, at least a part of the arithmetic unit 201 may be configured with hardware logic such as an FPGA (field-programmable gate array).

[0103] Some or all of the above examples may also be described as follows, but are not limited to the following:

[0104] (Note 1) The biosignal measurement system of the present invention comprises a first sensor device configured to be attached to one of the right and left sides of a person to be measured, and a second sensor device configured to be attached to the other of the right and left sides, wherein each of the first and second sensor devices comprises a first electrode configured to contact the skin of the person to be measured, an amplification unit configured to amplify the biopotential detected by the first electrode, a transmission unit configured to modulate a carrier wave in accordance with the biopotential amplified by the amplification unit and wirelessly transmit the modulated signal to the other sensor device, a receiving unit configured to demodulate the modulated signal transmitted from the other sensor device and extract biopotential information, a reference potential generation unit configured to generate a reference potential of the amplification unit based on the biopotential amplified by the amplification unit and the biopotential output from the receiving unit, and a correction unit configured to correct at least one of the oscillation frequency of the voltage-controlled oscillator used for modulation of the transmission unit and the oscillation frequency of the voltage-controlled oscillator used for demodulation of the receiving unit.

[0105] (Note 2) In the biosignal measurement system described in Note 1, each of the first sensor device and the second sensor device further comprises a transmitting antenna for wirelessly transmitting the modulated signal output from the transmitting unit to the other sensor device, and a receiving antenna for receiving the modulated signal transmitted from the other sensor device.

[0106] (Note 3) In the biosignal measurement system described in Note 1, each of the first sensor device and the second sensor device further comprises a second electrode for transmitting the modulated signal output from the transmitting unit to the other sensor device via the body of the person being measured, and a third electrode for receiving the modulated signal from the other sensor device via the body of the person being measured.

[0107] (Note 4) In the biosignal measurement system described in Note 1, the correction unit is equipped with a variable capacitor capable of changing at least one of the oscillation frequency of the voltage-controlled oscillator used for modulation of the transmitting unit and the oscillation frequency of the voltage-controlled oscillator used for demodulation of the receiving unit.

[0108] (Note 5) In the biosignal measurement system described in Note 1, each of the first sensor device and the second sensor device further comprises a first wired connection part for connecting the transmitting part of its own sensor device to the receiving part of the other sensor device by wire, and a second wired connection part for connecting the receiving part of its own sensor device to the transmitting part of the other sensor device by wire.

[0109] (Appendix 6) In the biosignal measurement system described in any one of Appendices 1 to 5, the correction unit of the first sensor device and the second sensor device is provided to correct the oscillation frequency of the voltage-controlled oscillator used for demodulating the receiving unit of its own sensor device, and the oscillation frequency of the voltage-controlled oscillator used for demodulating the receiving unit of its own sensor device is adjusted by the correction unit of its own sensor device so that the first potential given to the transmitting unit of the other sensor device for modulating the carrier wave matches the second potential output from the receiving unit of its own sensor device in response to the modulated signal transmitted from the other sensor device.

[0110] (Note 7) In the biosignal measurement system described in any one of Notes 1 to 5, the correction unit of the first sensor device and the second sensor device is provided to correct the oscillation frequency of the voltage-controlled oscillator used to modulate the transmitting unit of its own sensor device, and the oscillation frequency of the voltage-controlled oscillator used to modulate the transmitting unit of its own sensor device is adjusted by the correction unit of its own sensor device so that the first potential given to the transmitting unit of its own sensor device to modulate the carrier wave matches the second potential output from the receiving unit of the other sensor device in response to the modulated signal transmitted from its own sensor device.

[0111] (Note 8) In the biosignal measurement system described in any one of Notes 1 to 5, the correction unit of the first sensor device and the second sensor device each comprises a first correction unit configured to correct the oscillation frequency of a voltage-controlled oscillator used for demodulation of the receiving unit of its own sensor device, and a second correction unit configured to correct the oscillation frequency of a voltage-controlled oscillator used for modulation of the transmitting unit of its own sensor device, wherein the first potential given to the transmitting unit of the other sensor device for modulating the carrier wave matches the second potential output from the receiving unit of its own sensor device in response to the modulated signal transmitted from the other sensor device. The present invention is characterized in that, when the first potential and the second potential do not match, and a third potential is applied to the transmitting unit of the sensor device to modulate the carrier wave, the oscillation frequency of the voltage-controlled oscillator used to modulate the transmitting unit of the other sensor device is adjusted by the second correction unit of the other sensor device according to the comparison result between a fourth potential output from the receiving unit of the other sensor device in response to the modulated signal transmitted from the sensor device and a predetermined threshold voltage. [Industrial applicability]

[0112] This invention can be applied to techniques for measuring biological signals. [Explanation of Symbols]

[0113] 1a,1b...Sensor device, 2...Biosignal generation device, 101a,101b,109a',109b',110a',110b'...Electrodes, 102a,102b...Amplifier unit, 103a,103b...AD conversion unit, 104a,104b...Wireless transmission unit, 105a,105b...FM transmission unit, 106a,106b...FM receiver unit, 107a,107b...Reference potential generation unit, 108a,108b...Power supply, 109a,10 9b...Transmitting antenna, 110a, 110b...Receiving antenna, 111a, 111b, 112a, 112b...Wired connection section, 200...Wireless receiving section, 201...Calculation section, 202...Memory section, 1051a...Crystal oscillator, 1060a...VCO, 1052a, 1061a...Phase comparison section, 1053a, 1062a...Low-pass filter, 1063a...Amplification section, 1054a, 1054b, 1064a, 1064b...Correction section.

Claims

1. A first sensor device configured to be attached to either the right or left side of the person being measured, The system includes a second sensor device configured to be attached to the other of the right and left portions, Each of the first sensor device and the second sensor device is, A first electrode configured to come into contact with the skin of the person being measured, An amplification unit configured to amplify the biopotential detected by the first electrode, A transmitting unit configured to modulate a carrier wave in accordance with the biopotential amplified by the amplification unit and wirelessly transmit the modulated signal to the other sensor device, A receiving unit configured to demodulate the modulated signal transmitted from the other sensor device and extract bioelectric potential information, A reference potential generation unit is configured to generate a reference potential of the amplification unit by calculating the average of the biopotential amplified by the amplification unit and the biopotential output from the receiving unit, A biosignal measurement system characterized by comprising a correction unit configured to correct at least one of the oscillation frequency of a voltage-controlled oscillator used for modulation in the transmitting unit and the oscillation frequency of a voltage-controlled oscillator used for demodulation in the receiving unit.

2. In the biological signal measurement system according to claim 1, Each of the first sensor device and the second sensor device is, A transmitting antenna for wirelessly transmitting the modulated signal output from the transmitting unit to the other sensor device, A biosignal measurement system further comprising a receiving antenna for receiving a modulated signal transmitted from another sensor device.

3. In the biological signal measurement system according to claim 1, Each of the first sensor device and the second sensor device is, A second electrode for transmitting the modulated signal output from the transmitting unit to the other sensor device via the body of the person being measured, A biosignal measurement system further comprising a third electrode for receiving a modulated signal from another sensor device via the body of the person being measured.

4. In the biological signal measurement system according to claim 1, The biosignal measurement system is characterized in that the correction unit includes a variable capacitor capable of changing at least one of the oscillation frequencies of the voltage-controlled oscillator used for modulation in the transmitting unit and the oscillation frequencies of the voltage-controlled oscillator used for demodulation in the receiving unit.

5. In the biological signal measurement system according to claim 1, Each of the first sensor device and the second sensor device is, A first wired connection unit for connecting the transmitting unit of its own sensor device and the receiving unit of the other sensor device by wire, A biosignal measurement system further comprising a second wired connection unit for connecting the receiving unit of its own sensor device and the transmitting unit of the other sensor device by wire.

6. In the biosignal measurement system according to any one of claims 1 to 5, The correction unit of the first sensor device and the second sensor device is provided to correct the oscillation frequency of the voltage-controlled oscillator used for demodulation of the receiving unit of its own sensor device. A biosignal measurement system characterized in that the correction unit of its own sensor device adjusts the oscillation frequency of a voltage-controlled oscillator used for demodulation of the receiver of its own sensor device so that a first potential given to the transmitter of the other sensor device to modulate the carrier wave matches a second potential output from the receiver of its own sensor device in response to a modulated signal transmitted from the other sensor device.

7. In the biosignal measurement system according to any one of claims 1 to 5, The correction unit of the first sensor device and the second sensor device is provided to correct the oscillation frequency of the voltage-controlled oscillator used for modulation of the transmission unit of its own sensor device. A biosignal measurement system characterized in that the correction unit of its own sensor device adjusts the oscillation frequency of a voltage-controlled oscillator used for modulation of the transmitter of its own sensor device so that a first potential given to the transmitter of its own sensor device for modulating the carrier wave matches a second potential output from the receiver of the other sensor device in response to a modulated signal transmitted from its own sensor device.

8. In the biosignal measurement system according to any one of claims 1 to 5, Each of the correction units of the first sensor device and the second sensor device comprises a first correction unit configured to correct the oscillation frequency of the voltage-controlled oscillator used for demodulation of the receiving unit of its own sensor device, and a second correction unit configured to correct the oscillation frequency of the voltage-controlled oscillator used for modulation of the transmitting unit of its own sensor device. The first correction unit of its own sensor device adjusts the oscillation frequency of the voltage-controlled oscillator used for demodulation of the receiver of its own sensor device so that the first potential supplied to the transmitter of the other sensor device for modulating the carrier wave matches the second potential output from the receiver of its own sensor device in response to the modulated signal transmitted from the other sensor device. Furthermore, in the event that the first potential and the second potential do not match, and a third potential is applied to the transmitting unit of its own sensor device to modulate the carrier wave, the second correction unit of the other sensor device adjusts the oscillation frequency of the voltage-controlled oscillator used for modulation of the transmitting unit of the other sensor device according to the comparison result between the fourth potential output from the receiving unit of the other sensor device in response to the modulated signal transmitted from its own sensor device and a predetermined threshold voltage, thereby enabling the measurement of a biosignal.

9. A first sensor device configured to be attached to either the right or left side of the person being measured, The system includes a second sensor device configured to be attached to the other of the right and left portions, Each of the first sensor device and the second sensor device is, A first electrode configured to come into contact with the skin of the person being measured, An amplification unit configured to amplify the biopotential detected by the first electrode, A transmitting unit configured to modulate a carrier wave in accordance with the biopotential amplified by the amplification unit and wirelessly transmit the modulated signal to the other sensor device, A receiving unit configured to demodulate the modulated signal transmitted from the other sensor device and extract bioelectric potential information, A reference potential generation unit is configured to generate a reference potential of the amplification unit by calculating the average of the biopotential amplified by the amplification unit and the biopotential output from the receiving unit, A biosignal measurement system equipped with the following features.

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