JP2016087061A - Biological information measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of measuring a variation in distance between an electrode and a person, a contact state caused by the person's motion, or the like concurrently with biological information measurement using the electrode.SOLUTION: A biological information measurement device comprises: three biological signal measurement electrodes 01 composed of a first electrode 02 and second electrode 03 that make a pair of differential electrodes provided on a person through an insulator or directly on the person's skin, and a third electrode 04 that is an electrode for inducing intermediate potential; a transmission electrode for transmitting a signal to the person's living body as means for communication through the living body; measurement means for detecting, as an electrocardiographic signal, potential between the pair of differential electrodes taking induced potential at the intermediate electrode as a reference, and means for detecting a signal of the transmission electrode received from the first electrode and second electrode through the living body; and transmission wave generation means for generating a transmission signal to be induced at the transmission electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for measuring biological information in more detail by simultaneously performing biological information measurement and position measurement with an electrode placed facing a person.

  A person's action potential, which is biological information, can be measured by placing an electrode in contact with or in the vicinity of the person. For example, heartbeat measurement based on an electrocardiographic potential is biological information such as a person's state (drowsiness or abnormal occurrence). It is known to be effective as a measurement of

  For example, a technique for measuring a heartbeat of a driver who performs a driving operation by installing a measurement electrode on a steering wheel (steering wheel) of a vehicle and measuring an action potential is disclosed. (For example, see Patent Document 1).

  In Patent Document 1, the driver's heart during driving is measured by measuring the electrocardiographic potential of the vehicle driver from the electrode attached to the steering wheel of the vehicle and the electrode attached to the vehicle seat, and monitoring the heart activity of the driver. It is possible to suppress various inconveniences due to the abnormalities. However, the electrocardiographic potential can be measured when the driver is sitting on the seat and holding the steering wheel, and the driver is inconvenienced and the steering cannot be gripped. When the contact with the body becomes insufficient, the user sits on the seat and holds the steering wheel. However, if noise caused by driving or the external environment is mixed into the electrocardiogram, the inconvenience can be judged. When the electrocardiographic potential information cannot be acquired and the electrocardiographic waveform cannot be measured, there is a problem that the human state cannot be measured in more detail with only the installed electrodes.

  In addition, the technology to detect the state of the operator of the device from the biological information measurement using the electrode has been reported so far, but the distance and contact state between the detection electrode and the body due to the movement of the body accompanying the operation behavior. This greatly affects the reliability of the measurement result output from the apparatus, such as a decrease in the detection signal, the occurrence of S / N degradation, and the inability to perform measurement itself. In order to further improve the reliability of measurement results, a measurement technique is disclosed that combines biometric information measurement using electrodes with a pressure sensor. (See Patent Document 2).

  In Patent Document 2, the electrostatic capacitance between the electrode and the subject is estimated by using a pressure sensor in combination with the capacitance-coupled electrocardiographic waveform measurement, and the level of the electrocardiogram signal that varies depending on the movement of the person is estimated. The reliability of the measurement result is improved by correcting based on the capacitance value.

  However, the ECG measurement result can be corrected from the detection result of the pressure sensor under the condition that a certain pressure is applied to the electrode, so the correction functions when the pressure is not applied or the electrode is touched. do not do. Further, in the capacitive coupling type electrocardiogram measurement, the electrocardiogram can be measured if the electrode and the body are not in contact with each other if they are electrostatically coupled, but there is also a problem that the pressure sensor does not function in this case. In addition, because of the indirect capacitance estimation using a pressure sensor, the correction accuracy may deteriorate due to the influence of the type of clothing of the subject, etc., which is inconvenient for detecting the contact state between the electrode and the subject. It was enough.

JP 2011-24902 A JP 2009-219554 A

  It is an object of the present invention to provide an apparatus capable of measuring living body information using an electrode and simultaneously measuring a contact state generated by a person's movement or a distance change between the electrode and a person.

The problems of the present invention are solved by the following configuration.
That is, the present invention provides a pair of differential electrodes, a first electrode, a second electrode, and an electrode for inducing an intermediate potential, which are installed via a person and an insulator or directly on the human skin. Three biological signal measuring electrodes consisting of a third electrode,
A transmitting electrode for transmitting a signal to a living body as a communication means via the human living body;
Measuring means for detecting the potential between the pair of differential electrodes as an electrocardiographic signal with reference to the induced potential of the intermediate electrode, and the transmitting electrode received via the living body from the first electrode and the second electrode Means for detecting the signal;
The present invention relates to a biological information measuring apparatus comprising transmission wave generating means for generating a transmission signal to be induced in the transmission electrode.

  In addition, the present invention relates to the biological information measuring apparatus, characterized in that the third electrode is provided with means for inducing an added signal voltage of an intermediate potential and a transmission signal on the third electrode.

The present invention also includes a proximity sensor electrode that capacitively couples with a person,
A first electrode, a second electrode, and a third electrode that is an electrode for inducing an intermediate potential, which are a pair of differential electrodes, which are directly installed on a person's skin through a person and an insulator. Three biological signal measuring electrodes consisting of:
A proximity sensor circuit capable of measuring the capacitance formed in the proximity sensor electrode as a voltage signal;
Measuring means for detecting the potential between the pair of differential electrodes as an electrocardiogram signal with reference to the induced potential of the intermediate electrode;
It is related with the biological information measuring device characterized by comprising.

Further, according to the present invention, the proximity sensor circuit includes:
It is a proximity sensor circuit which can detect the electrostatic capacitance formed in a proximity sensor electrode as an amplitude modulation signal.

Further, the present invention provides the biological signal measuring electrode,
It is related with the said biometric information measuring device provided with the electrode characterized by the proximity sensor electrode being installed in each circumference | surroundings.

  By setting the frequency of the sine wave transmitted from the third electrode outside the frequency band of the biological information according to the present invention, a biological information measuring device that can simultaneously execute two functions without adding a new electrode. Could be provided.

In addition, it was possible to provide a biological information measuring device capable of simultaneously measuring additional information such as the posture of a person at the time of measuring biological information by measuring biological information using electrodes and measuring a distance between a person and an electrode using a proximity sensor. .
Also,

1 is a configuration diagram of a biological information measuring apparatus according to a first embodiment of the present invention. 1 is a configuration diagram of a biological information measurement circuit unit according to a first embodiment of the present invention. The principle figure which detects the contact state of the electrode concerning the 1st Embodiment of this invention. The relationship figure of the frequency characteristic of the electrocardiogram waveform and transmission sine wave concerning the 1st embodiment of this invention. The block diagram of the biological information measuring device concerning the 2nd embodiment of this invention. The block diagram of the electrostatic capacitance detection circuit concerning the 2nd embodiment of this invention. The relationship figure of the frequency characteristic of the electrocardiogram waveform and proximity data concerning the 2nd embodiment of this invention. The block diagram of the detection process performed within CPU00 concerning 2nd Embodiment of invention.

First, a first embodiment for carrying out the present invention will be described with reference to the drawings.
According to this configuration, the first and second detection electrodes arranged so as to be in contact with or capacitively coupled to the living body of the operator and the third electrode, which is a contact or non-contact that induces a reference potential in the body, are used as biological information. A certain electrocardiogram potential can be measured to detect the operator's state. In addition, a sine wave signal is superimposed on the reference potential output at the time of detecting biological information on the third electrode, and the sine wave is detected from the signals read by the first and second detection electrodes, thereby detecting the detection electrode and the person. The contact state can be detected. For example, even when noise is mixed in the biological information detected from the first and second detection electrodes and effective data cannot be acquired, the contact of the electrodes can be confirmed by detecting the sine wave transmitted from the third electrode. If so, the device can determine that the electrodes are in contact. Note that since the sine wave transmitted from the third electrode has a signal strength artificially induced, the electrode contact signal can be detected because the noise resistance is higher than that of the weak biopotential.

  Since each of the first and second detection electrodes has two functions of detection of biological information and detection of an electrode contact state, it is not necessary to newly add a sensor for detecting the contact state of the electrode. It was possible to obtain a device with a simple configuration.

  In the above-described human state detection device, all of the sine waves of the biological information measurement and the electrode contact state measurement detect the potential generated at the electrode. In order to operate the two functions simultaneously without affecting each other, the frequency of the sine wave transmitted from the third electrode in the electrode contact state measurement is set outside the frequency band of the biological information. Two functions can be executed simultaneously.

  FIG. 1 shows a configuration diagram of a biological information measuring apparatus which is one of the preferred embodiments of the present invention. The apparatus includes an electrode unit 01 installed facing a person and a signal processing circuit unit 05 for processing a detection signal.

The electrode unit 01 includes a pair of differential electrodes that detect an electrocardiographic potential, a first electrode, a second electrode, and a third electrode that provides an intermediate potential.

  The signal processing circuit unit 05 includes a biological information measurement circuit unit 06 that measures an electrocardiographic potential from the differential potential of the first electrode 02 and the second electrode 03, and a feedback circuit unit 11 that applies an intermediate potential to the third electrode 04. In order to detect the contact state between the electrode and the person, the signals from the transmission wave generation circuit unit 13, the feedback circuit unit 11, and the transmission wave generation circuit unit 13 that generate a sine wave induced in the third electrode 04 are added. A receiving circuit unit 07 that detects a contact state between the adder circuit 12 and the electrode, an adder circuit 08 that adds the electrocardiogram waveform and the electrode contact state signal, a low-pass filter 09 that functions as an anti-aliasing filter, and an analog / digital conversion circuit 10 And a CPU 14 for analyzing the human condition from the electrode contact state and the electrocardiogram waveform.

  FIG. 2 shows a part of a preferable form of the biological information measuring circuit unit 06. The biometric information measurement circuit unit 06 includes the resistance element 15 that converts the charge transfer generated in the first electrode 02 and the second electrode 03 into a voltage, the buffer circuit 16 that buffers the voltage, and the output of the buffer circuit 16, respectively. A receiving circuit unit 07 that detects the contact state of the electrodes, a resistance element 17 that determines an input voltage to the feedback circuit 11, and a differential amplifier circuit 18 that converts the differential voltage to a single end are provided.

  FIG. 3 shows the principle of detecting the contact state of the electrodes. By inducing a sinusoidal voltage on the third electrode 04, an electric field vibration is generated in the near field of a person. By detecting the change in the electric field with the first electrode 02, the contact state between the electrode and the person can be known. In this principle, the third electrode 04 is a transmission electrode, the first electrode 02 is a reception electrode, and a sine wave is transmitted using a person as a medium. Since the sine wave cannot be received if the person and the electrode are separated, the person and the electrode are not in contact. Further, the reception of the second electrode 03 can be the same as that of the first electrode 02.

  FIG. 4 shows the relationship between the frequency of the sine wave output from the transmission wave generating circuit unit 13 and the frequency band of the electrocardiographic waveform. Generally, the frequency band of the electrocardiogram waveform is about 0.05 to 200 Hz. Thus, by setting the frequency of the sine wave output from the transmission wave generating circuit unit 13 high, the overlap of the frequency bands of the two signals is eliminated, and the electrocardiographic waveform of the first electrode 02 and the second electrode 03 is eliminated. Detection and transmission signal reception are simultaneously performed, and it is possible to perform frequency separation in the biological information measurement circuit unit 06 and the reception circuit unit 07.

  Also, due to the frequency separation described above, the frequency band of the feedback voltage that determines the intermediate potential and the frequency band of the sine wave transmitted from the transmission wave generation circuit unit 13 are different in the third electrode 04, so two voltages are added. The addition processing is performed by the circuit 12, and it is possible to simultaneously induce the voltage of the intermediate potential and the voltage of the transmission sine wave with one electrode.

  In addition, since the ECG waveform and the transmission sine wave signal are different in the frequency band in the reception circuit unit 07 and the biological information measurement circuit unit 06, the two signals are added to form one signal. One low-pass filter 09 and one analog / digital conversion circuit 10 need only be installed, and the circuit scale can be reduced.

  Next, a second embodiment for carrying out the present invention will be described with reference to the drawings. The biological information measuring apparatus according to the second aspect of the present invention includes three measurement electrodes including a pair of differential electrodes and an electrode for applying an intermediate potential, and can measure an electrocardiographic potential from the differential electrode with reference to the intermediate potential. At this time, a proximity sensor electrode installed around the differential electrode is provided, the capacitance formed between the person and the electrode can be detected, and the distance from the electrode to the person can be measured.

  According to this configuration, in the case of capacitance-coupled electrocardiography where an electrode is installed on a person via an insulator, the amplitude of the detection signal changes when the capacitance formed by the person and the electrode changes. However, the change in capacitance at this time is mainly caused by the change in the distance between the electrode and the person. This distance change is detected by a capacitive proximity sensor, and the biometric information is gain-corrected based on the detected value, thereby enabling stable detection.

  Also, if the distance between the electrode and the person is more than a certain distance, the S / N deterioration occurs and the electrocardiographic waveform cannot be measured. In the case of an electrocardiograph only device, the situation cannot be judged, and a signal that does not contain valid information may be processed and misrecognized, but the present invention measures from the proximity sensor value. It is possible to recognize that there is no person in the possible range, and it is possible to reduce the possibility that the apparatus analyzes and misrecognizes information that does not include electrocardiogram data.

  Even in the electrocardiogram measurement method in which the electrode is directly in contact with the skin, contact non-contact can be recognized from the information of the proximity sensor. Can be reduced.

  FIG. 5 shows a configuration diagram of a human state detection apparatus which is one of the preferred embodiments of the present invention. The apparatus includes an electrode unit 201 installed facing a person and a signal processing circuit unit 206 that processes a detection signal.

  The electrode unit 201 includes a proximity sensor electrode unit 202, a pair of differential electrodes for detecting an electrocardiogram potential, a first electrode 203, a second electrode 204, and a third electrode 205 for applying an intermediate potential.

  The signal processing circuit unit 206 includes a proximity sensor signal processing circuit unit 207 that converts the capacitance formed in the proximity sensor electrode unit 202 into a voltage value, and a differential potential between the first electrode 203 and the second electrode 204. A biological information measurement circuit unit 208 that measures the electric potential, a feedback circuit 209 that applies an intermediate potential to the third electrode 205, and an output voltage and an electrocardiographic potential of the proximity sensor signal processing circuit unit 207 that are detection signals of the proximity sensor. From an addition circuit 210 that adds two signals of output voltage of a certain biological information measurement circuit unit 208, a low-pass filter 211 that functions as an anti-aliasing filter, an analog / digital conversion circuit 212, proximity data, and an electrocardiogram waveform, A CPU 213 that performs digital processing such as radio wave type gain correction and human condition analysis is provided.

  FIG. 6 shows one preferred form of the proximity sensor signal processing circuit unit 207. The proximity sensor signal processing circuit unit 207 includes a filter circuit unit 214 and a digital / analog conversion circuit 215 that converts a digital signal from the CPU 213 into an analog signal.

  The proximity sensor electrode unit 202 is connected to the filter circuit unit 214 built in the proximity sensor signal processing circuit unit 207, and the capacitance formed between the person and the proximity sensor electrode unit 202 is the filter circuit unit 214. It functions as a part of the component.

  The sine wave output from the digital / analog conversion circuit 215 is input to the filter circuit unit 214. The sine wave data is output from the CPU 213 to the digital / analog conversion circuit 215 as digital data. The filtered sine wave signal is output to the adder circuit 210.

  When the capacitance formed between the proximity sensor electrode unit 202 and the person changes, the cutoff frequency of the filter circuit unit 214 changes. By setting the sine wave input to the filter circuit unit 214 to a value higher than the cut-off frequency, the sine wave amplitude after the filter process increases and decreases with the change in the cut-off frequency. In this case, the distance information between the person and the proximity sensor electrode is detected as information obtained by AM modulation using a sine wave as a reference frequency.

  In the configuration of the present invention, two data of the output of the proximity sensor signal processing circuit unit 207 which is AM-modulated proximity data and the output of the biological information measurement circuit unit 208 which is an electrocardiographic potential are added and processed by the adding circuit 210. Is converted into a digital signal. By adding the two signals into one signal, it is sufficient to install one low-pass filter circuit 211 and an analog / digital conversion circuit 212 for the anti-aliasing filter, and the circuit scale can be reduced.

  In general, the frequency band of the electrocardiogram waveform is about 0.05 to 200 Hz, and the frequency band of the proximity information is a low frequency region from 0 Hz which is a direct current component when considering human operation. If the two signals are simply added, the signal bands overlap, and the signals after digital data conversion cannot be separated. However, in the configuration of the present invention, since the proximity information is AM-modulated to a sine wave that is a reference frequency arbitrarily set, addition processing is performed in an analog signal state by setting the reference frequency outside the frequency band of the electrocardiogram waveform. Even if it performs, an electrocardiogram waveform and proximity information can be acquired by performing frequency band separation processing after digital conversion. FIG. 7 shows a relationship diagram of frequency characteristics.

  FIG. 8 shows a processing configuration of the detection method of the AM-modulated proximity sensor signal in the CPU 213 according to the present embodiment. Note that this processing is all digital signal processing. The AM modulated signal is processed by a bandpass filter block 216 that passes the reference signal band, and then multiplied by a multiplication processing block 217. The detection circuit multiplies the sine wave signal output to the digital / analog conversion circuit 215. The multiplied signal is finally processed by the integration processing block 218, so that demodulated proximity sensor data can be obtained.

01 ... Electrode unit 02 ... First electrode 03 ... Second detection electrode 04 ... Third detection electrode 05 ... Signal processing circuit unit 06 ... Biological information measurement circuit unit 07 ...・ Receiving circuit unit 08... Addition circuit 09 .. low pass filter 10... Analog / digital conversion circuit unit 11... Feedback circuit unit 12... Adding circuit 13. ..CPU
DESCRIPTION OF SYMBOLS 15 ... Resistance element 16 ... Buffer circuit 17 ... Resistance element 18 ... Differential amplifier circuit

201 ... Electrode unit 202 ... Proximity sensor electrode unit 203 ... First electrode 204 ... Second electrode 205 ... Third electrode 206 ... Signal processing circuit unit 207 ... Proximity sensor signal processing circuit unit 208 ... biological information measurement circuit unit 209 ... feedback circuit unit 210 ... addition circuit 211 ... low pass filter circuit 212 ... analog / digital conversion circuit 213 ... CPU
214 ... Filter circuit unit 215 ... Digital / analog conversion circuit 216 ... Band pass filter block 217 ... Multiplication processing block 218 ... Integration processing block

Claims (5)

A first electrode, a second electrode, and a third electrode that is an electrode for inducing an intermediate potential, which are a pair of differential electrodes, which are directly installed on a person's skin through a person and an insulator. Three biological signal measuring electrodes consisting of:
A transmitting electrode for transmitting a signal to a living body as a communication means via the human living body;
Measuring means for detecting the potential between the pair of differential electrodes as an electrocardiographic signal with reference to the induced potential of the intermediate electrode, and the transmitting electrode received via the living body from the first electrode and the second electrode Means for detecting the signal;
A biological information measuring device comprising: a transmission wave generating means for generating a transmission signal to be induced in the transmission electrode. 3. The biological information measuring apparatus according to claim 2, further comprising means for inducing an added signal voltage of an intermediate potential and a transmission signal in the third electrode. A proximity sensor electrode that capacitively couples with a person;
A first electrode, a second electrode, and a third electrode that is an electrode for inducing an intermediate potential, which are a pair of differential electrodes, which are directly installed on a person's skin through a person and an insulator. Three biological signal measuring electrodes consisting of:
A proximity sensor circuit capable of measuring the capacitance formed in the proximity sensor electrode as a voltage signal;
Measuring means for detecting the potential between the pair of differential electrodes as an electrocardiogram signal with reference to the induced potential of the intermediate electrode;
A biological information measuring device comprising: The proximity sensor circuit includes:
4. The biological information measuring device according to claim 3, wherein the biological information measuring device is a proximity sensor circuit capable of detecting an electrostatic capacitance formed on the proximity sensor electrode as an amplitude modulation signal. The biological signal measurement electrode is:
5. The biological information measuring device according to claim 3, further comprising an electrode characterized in that proximity sensor electrodes are provided around each of the electrodes.