Biological signal measurement device and method for controlling biological

Abstract

A biological signal measurement device is provided with: a dry electrode; a member that fixes the electrode in a state in which the electrode is pressed against a living body; and a control main body for measuring a biological signal by means of the electrode, the control main body comprising: a waveform feature extraction unit for extracting a feature quantity from the waveform of the biological signal; and a wearing state determination unit that determines whether or not the wearing state of the electrode is good on the basis of a feature amount extracted from the waveform of the biological signal measured during a period after the elapsed time from the wearing of the electrode on the living body by the member reaches a predetermined time.

Description

TECHNICAL FIELD

[0001] The present application relates to a biological signal measuring apparatus that measures a biological signal by an electrode fixed to a skin surface. BACKGROUND

[0002] A technique is known in which an electrode is fixed to a skin surface of a living body and a biological signal such as an electrocardiogram, an electromyogram, or the like is measured, and this technique is applied to various measuring apparatuses. In such an apparatus, if the contact state of the electrode with the skin surface is not appropriate, the measurement accuracy can be degraded, or the measurement itself can not be performed.

[0003] In Patent Literature 1, the following idea is proposed: in measurement of a standard 12-lead electrocardiogram, before starting recording of the electrocardiogram, it is determined whether noise is mixed, the electrode is erroneously worn, or the electrode is detached, based on the characteristics of the waveforms of the respective leads.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-261723 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present inventors are promoting development of a measuring apparatus of the following type: fixation of an electrode to a skin surface is performed by winding a belt in which a dry electrode is embedded (hereinafter also referred to as "electrode belt") around an arm or a leg. By adopting such a fixation structure of a dry electrode, the following advantages are obtained: since the patient himself / herself can simply perform wearing and removal of the apparatus, it is easy to perform measurement, and since skin rash or the like does not occur, it is easy to perform measurement for a long time while keeping the state of wearing the apparatus unchanged. However, on the contrary, it is expected that if the patient himself / herself performs wearing and removal of the apparatus, the frequency of occurrence of poor wearing increases. Therefore, from the viewpoint of improving the reliability and stability of measurement, it is desirable to have a mechanism that automatically determines the wearing state of the dry electrode and reports to the patient in the case of poor wearing.

[0009] The present inventors, in the course of trial-manufacturing of an electrode belt and repeatedly performing wearing experiments, have learned that, among the causes of occurrence of poor wearing of an electrode, there are two factors: that the electrode does not make proper contact with the skin surface (poor physical connection) and that the skin surface between the electrode and the skin surface is not sufficiently moistened. Furthermore, it has been found that, after a certain period of time has passed after the electrode is worn, the case where the insufficient moistening is eliminated by sweating occurs many times, and there are a certain number of patients in which the skin between the electrode and the skin is not sufficiently moistened even after a period of time has passed.

[0010] In the 12-lead electrocardiogram of Patent Literature 1, since a wet electrode using a conductive gel is generally used, wearing failure due to insufficient wetting is not assumed. Therefore, in a case where the determination method of Patent Literature 1 is simply applied to a device of a dry electrode type, it is not possible to distinguish between insufficient wetting and physical connection failure, and a determination result of wearing failure is outputted in all cases. However, in a case where the cause is insufficient wetting, since the possibility of being eliminated as time passes is high, it is not appropriate to immediately determine wearing failure. On the contrary, in a case of insufficient wetting, since it is not eliminated even if the electrode is re-worn, a result of misleading the patient is caused.

[0011] The present application was completed in view of the above-described actual circumstances, and aims to provide a technology for appropriately making a determination of whether or not a wearing state of an electrode is good, and a report to a user, in a biological signal measurement device that adopts a dry electrode.

[0012] Technical solution for solving the technical problem

[0013] The present disclosure includes a biological signal measurement device that includes a dry electrode, a member that fixes the electrode in a state where the electrode is pressed against a living body, and a control main body that measures a biological signal through the electrode, the control main body having a waveform feature extraction section that extracts a feature amount from a waveform of a biological signal, and a wearing state determination section that determines whether or not a wearing state of the electrode is good, based on a feature amount extracted from a waveform of a biological signal measured in a period after an elapsed time from when the electrode is worn on the living body by the member reaches a predetermined time.

[0014] The predetermined time can be set to a time of 5 minutes or more.

[0015] The waveform feature extraction section can extract a length of a non-signal section in which a state of the biological signal being saturated or zero continues, as the feature amount, and the wearing state determination section can determine that the wearing state is not good in a case where a non-signal section of a length of a predetermined value or more occurs.

[0016] The wearing state determination section can determine that the wearing state is not good before the elapsed time reaches the predetermined time, in a case where a feature amount extracted from a waveform of a biological signal measured in a period before the elapsed time reaches the predetermined time matches a predetermined reference.

[0017] It can also be that the dry electrodes include a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined criterion is that non-signal intervals of a length equal to or greater than a predetermined value do not occur in all of the plurality of electrode pairs during a first period, but non-signal intervals of the length equal to or greater than the predetermined value occur in some of the plurality of electrode pairs during a second period later than the first period.

[0018] It can also be that the dry electrodes include a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined criterion is that non-signal intervals of a length equal to or greater than a predetermined value do not occur in all of the plurality of electrode pairs during a first period, but non-signal intervals of the length equal to or greater than the predetermined value occur in some of the plurality of electrode pairs during a second period later than the first period.

[0019] It can also be that the dry electrodes include a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined criterion is that non-signal intervals of a length equal to or greater than a predetermined value do not occur in all of the plurality of electrode pairs during a first period, but non-signal intervals of the length equal to or greater than the predetermined value occur in some of the plurality of electrode pairs during a second period later than the first period.

[0020] It can also be that the biological signal measurement device further has a reporting section that reports to the user in a case where it is determined by the wearing state determination section that the wearing state is poor.

[0021] It can also be that the wearing state determination section determines a cause of the poor wearing state based on the feature quantity extracted from the waveform of the biological signal, and the reporting section makes the report to the user different depending on the cause of the poor wearing state.

[0022] It can also be that the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the reporting section urges the user to re-wear the electrodes in a case where it is determined by the wearing state determination section that a non-signal interval of a length equal to or greater than a predetermined value occurs.

[0023] It can also be that the waveform feature extraction section extracts an amplitude of a peak included in the biological signal as the feature quantity, and the reporting section urges the user to change a wearing position of the electrodes in a case where it is determined by the wearing state determination section that the amplitude of the peak is smaller than a predetermined amplitude value.

[0024] The waveform feature extraction section can extract a noise mixing degree of the biological signal as the feature quantity, and the reporting section can urge the user to take a countermeasure for improving wetness between the electrode and the skin surface when the noise mixing degree is determined by the wearing state determination section to be equal to or higher than a predetermined threshold value.

[0025] The control body can have an operation section, and the user can operate the operation section after wearing the electrode. The control body can start counting the elapsed time when the operation section is operated by the user.

[0026] The biological signal can be an ECG (Electrocardiogram) signal.

[0027] The member can be a belt provided with the electrode.

[0028] The belt can be worn on the upper arm of the living body.

[0029] The present disclosure includes a control method of a biological signal measurement device that measures a biological signal by means of a dry electrode. The control method of the biological signal measurement device includes the steps of counting an elapsed time from when the electrode is worn on a living body, extracting a feature quantity from a waveform of the biological signal, and determining whether a wearing state of the electrode is good or not based on the feature quantity extracted from the waveform of the biological signal measured during a period after the elapsed time reaches a predetermined time.

[0030] The present disclosure can be understood as a biological signal measurement device having at least a part of the above-described configuration, or as an electrocardiograph that measures an ECG signal as a biological signal. Alternatively, the present disclosure can be understood as a wearing state determination device that can be mounted on a biological signal measurement device. In addition, the present disclosure can be understood as a wearing state determination method including at least a part of the above-described processing, a control method of a biological signal measurement device, or a program for implementing the method, a storage medium in which the program is non-transitorily stored. Note that the above-described configuration and processing can be combined with each other as much as possible to constitute the present disclosure.

[0031] Effects of Invention

[0032] According to the present disclosure, in a biological signal measurement device that employs a dry electrode, determination of whether a wearing state of an electrode is good or not and reporting to a user can be appropriately performed. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a diagram showing a case where a biological signal measurement device is worn on an upper arm.

[0034] Figure 2 is a plan view of a living body signal measurement device.

[0035] Figure 3 is a perspective view of a living body signal measurement device.

[0036] Figure 4 is a block diagram showing a functional configuration of a control main body.

[0037] Figure 5 is a flowchart showing a flow of a measurement process of an ECG signal.

[0038] Figure 6 is a diagram showing an example of an electrode pair and an ECG signal.

[0039] Figure 7 is a diagram explaining a waveform of an ECG signal and heart rate information.

[0040] Figure 8 is a flowchart showing a flow of a determination process of a wearing state in the first embodiment.

[0041] Figure 9A is a diagram showing an example of an ECG signal waveform measured in a quiet state.

[0042] Figure 9B is a diagram showing an example of an ECG signal waveform that is disturbed due to an influence of physical activity.

[0043] Figure 9C is a diagram showing an example of an ECG signal waveform measured in a case where wearing of an electrode is poor.

[0044] Figure 10 is a flowchart showing a flow of a determination process of a wearing state in the second embodiment.

[0045] Figure 11 is a flowchart showing a flow of a determination process of a wearing state in the third embodiment.

[0046] Figure 12 is a diagram showing an example of a reference when a wearing state is determined in the third embodiment. DETAILED DESCRIPTION

[0047] <APPLICATION EXAMPLE>

[0048] REFERENCE Figure 1 One of application examples of the present application is described.

[0049] The living body signal measurement device 1 is a portable measurement device that is worn on a living body. The living body signal measurement device 1 has a belt 10 provided with one or more dry electrodes 11 and a control body 12 that measures a living body signal via the electrodes 11, as main components.

[0050] The living body signal that is the object of measurement is also called a living body electric signal or a living body potential, and is an electric signal that is generated in conjunction with the activity of a living body. For example, there are an electrocardiogram signal (a minute electric signal that accompanies a beat), an electromyogram signal (a minute electric signal that accompanies the activity of a muscle), an electroencephalogram signal (a minute electric signal that accompanies the activity of a brain), and the like. As the measurement site where the belt 10 is worn, the upper limbs (upper arms, forearms, wrists, hands, fingers), the lower limbs (thighs, shanks, ankles, feet, toes), the head, the neck, the chest, the abdomen, the ears, and the like can be exemplified, and are appropriately selected in accordance with the kind of living body signal that is measured, the measurement algorithm, and the like.

[0051] At the time of measurement, after the user himself or herself has worn the device 1 by winding the belt 10 around the measurement site, measurement is started by pressing a button or the like of the control body 12. At this time, if there is a poor physical connection such as a poor winding method of the belt 10, poor tightness, or the electrodes 11 being raised from the surface of the skin, then correct measurement cannot be performed. Therefore, in such a case, the user needs to be reported to and caused to take a response such as rewearing the belt 10. However, even if the physical connection of the electrodes 11 to the surface of the skin is good, there can be a case where the electric connection between the electrodes 11 and the surface of the skin becomes poor due to insufficient wetness. Therefore, if only the goodness or badness of the electric connection between the electrodes 11 and the surface of the skin is evaluated, then it cannot be distinguished whether the physical connection is poor or the wetness is insufficient, and the user cannot be guided to an appropriate response.

[0052] Therefore, the living body signal measurement device 1 determines the goodness or badness of the wearing state of the electrodes 11 based on a feature quantity that is extracted from the waveform of the living body signal that is measured in a period after the elapsed time from when the electrodes 11 are worn reaches a predetermined time Tw. That is, the determination of the goodness or badness of the wearing state is not performed immediately after the belt 10 is worn, but is performed after a predetermined time Tw has elapsed. Since the wetting of the electrodes 11 and the surface of the skin due to perspiration is expected to occur by providing such a waiting time, it is possible to determine with high accuracy whether the physical connection is poor (that is, whether rewearing is necessary) or not.

[0053] The predetermined time (waiting time) Tw is preferably set to a time of 5 minutes or more and 30 minutes or less. This is because, if a time of this extent elapses in a state where the electrode 11 is worn, a sufficient wet state (that is, a state in which the electrical connection of the electrode 11 and the skin surface is maintained to a degree that enables the measurement of the biological signal and the evaluation of the waveform) can be obtained in almost all users.

[0054] The following describes an embodiment of the present application with a specific configuration example in which the present application is applied to an upper arm electrocardiograph as an example.

[0055] <First Embodiment>

[0056] (Device Configuration)

[0057] Reference Figures 1-3 An embodiment of the present application will be described. Figure 1 is a view showing a case where the biological signal measurement device 1 is worn on the upper arm, Figure 2 is a plan view of the biological signal measurement device 1, Figure 3 is a perspective view of the biological signal measurement device 1.

[0058] The biological signal measurement device 1 of the present embodiment is an upper arm electrocardiograph that is worn on the upper arm of a user (preferably the left upper arm near the heart) and measures an ECG (Electrocardiogram) signal (electrocardiosignal) as a biological signal.

[0059] The biological signal measurement device 1 has a band 10, a plurality of electrodes 11 fixed to the band 10, and a control body 12 fixed to the band 10, as main components.

[0060] The band 10 is a member (fixing member) for fixing the electrodes 11 in a state where the electrodes 11 are pressed against a living body. In the present embodiment, a band-shaped band 10 made of a material having flexibility and softness (for example, chemical fiber, silicon, leather, or the like) is used. A fixing mechanism 13 is provided at the lengthwise end portion of the band 10. As shown in Figs. 1 and 2, the biological signal measurement device 1 can be worn on the upper arm by making the band 10 into a ring shape and securing it with the fixing mechanism 13. The fixing mechanism 13 can be any mechanism such as a Velcro, a hook, a connector, a button, a magnet, or the like. Figure 1 and Figure 3 As shown in Figs. 1 and 2, the biological signal measurement device 1 can be worn on the upper arm by making the band 10 into a ring shape and securing it with the fixing mechanism 13. The fixing mechanism 13 can be any mechanism such as a Velcro, a hook, a connector, a button, a magnet, or the like.

[0061] The plurality of electrodes 11 (also referred to as an electrode array) are embedded and fixed to the band 10 in a manner that their contact surface with the living body is exposed to the inner side (living body side) of the band 10. The plurality of electrodes 11 are arranged in a row at equal intervals along the longitudinal direction of the band 10. Thus, when the band 10 is wound around the arm, the electrodes 11 come into contact with different positions around the arm. The number of electrodes 11 can be arbitrarily designed. If the purpose is to measure an ECG signal, at least two electrodes 11 (one electrode pair) are sufficient, and in order to improve the reliability and robustness of the measurement, three or more electrodes 11 can be provided. In the present embodiment, a configuration in which six electrodes 11 (three electrode pairs) are provided is adopted.

[0062] The electrodes 11 are dry metal electrodes. Wet electrodes (gel electrodes, etc.) have problems such as the possibility of causing skin rashes and itching if worn for a long time, low durability, and low maintenance, and in contrast, the dry electrodes 11 do not have such problems. With regard to the living body signal measurement device 1 of the present embodiment, since it is assumed that the ECG signal will be continuously measured for a long time and for 24 hours, it is preferable to use the dry electrodes 11.

[0063] The control body 12 is a processing unit that performs control and signal processing of the living body signal measurement device 1. The control body 12 has, for example, a structure in which a processor, a memory, a battery, and other circuits are mounted inside a housing made of resin or metal. A physical switch and a display can also be provided in the control body 12. Although not shown, the control body 12 is connected to the plurality of electrodes 11 via signal lines.

[0064] (Control Body)

[0065] Figure 4 is a block diagram showing an example of the functional configuration of the control body 12.

[0066] The control body 12 has a measurement electrode selection section 30, an ECG measurement section 20, an ECG signal processing section 21, an ECG heart rate information calculation section 22, an ECG signal quality determination section 23, an AF determination section 24, a storage section 25, a communication section 26, an operation section 27, as a configuration related to measurement of an ECG signal. The measurement electrode selection section 30 selects a pair of electrodes for measurement of an ECG signal. The ECG measurement section 20 is a circuit that amplifies a potential difference between the selected pair of electrodes by a differential amplifier and outputs as an ECG signal. The ECG signal processing section 21 is a section that performs AD conversion and filter processing of an ECG signal, and has an AD conversion section 210 that performs AD conversion of an ECG signal, an electromagnetic noise removal section 211 that removes electromagnetic noise from an ECG signal to improve SN ratio, and a baseline fluctuation removal section 212 that removes baseline fluctuation (fluctuation of low frequency) of an ECG signal. The ECG heart rate information calculation section 22 is a section that extracts various heart rate information from an ECG signal, and has an R wave detection section 220, an RRI calculation section 221, a heart rate fluctuation calculation section 222, a P wave detection section 223. The ECG signal quality determination section 23 is a section that determines whether the quality of an ECG signal is good or not (i.e., whether data with accuracy and reliability suitable for a purpose of diagnosis or the like can be measured or not). The ECG signal quality determination section 23 also has a function as a waveform feature extraction section that extracts a feature quantity of a waveform of an ECG signal, and the extracted feature quantity of a waveform is used in determination processing of a wearing state described later. The AF determination section 24 is a section that detects occurrence of AF (Atrial Fibrillation) or calculates an index related to AF based on heart rate information. The storage section 25 is a nonvolatile memory that stores measured and calculated data. The communication section 26 is a section that performs data communication with an external device (e.g., a user's smartphone, another health device, a home server, or the like) through wireless communication. The operation section 27 is an input interface for a user to perform input operation. The operation section 27 can be a physical button or a touch panel display.

[0067] In addition, as a configuration related to automatic determination of a wearing state of the electrodes 11, the control body 12 has a wearing state determination section 33, a reporting section (notification section) 34. The wearing state determination section 33 is a section that determines whether the wearing state of the electrodes 11 is good or not based on a feature quantity of a waveform of an ECG signal extracted by the ECG signal quality determination section 23. The reporting section 34 is a section that reports a result of determination by the wearing state determination section 33 to a user.

[0068] (ECG signal measurement processing)

[0069] Reference Figures 5-7 The ECG signal measurement processing by the living body signal measurement device 1 will be described. Figure 5is a flowchart showing a flow of a measurement process of an ECG signal, Figure 6 is a diagram showing an example of electrode pairs and an ECG signal, Figure 7 is a diagram explaining a waveform of an ECG signal and heart rate information.

[0070] After the user winds the belt 10 around the upper arm and secures the belt 10 with the fixing mechanism 13, when an operation of instructing the start of measurement is performed by operating the operation section 27, the processor of the control main body 12 starts the measurement process of Figure 5 .

[0071] In step S500, the ECG measurement section 20 measures 3 channels of ECG signals using three sets of electrode pairs. Specifically, by measuring, the electrode selection section 30 selects electrode pairs (two electrodes 11) to be used in the measurement, and a differential amplifier amplifies a potential difference between the selected electrode pairs and imports as an ECG signal (analog voltage signal). By sequentially switching the selected electrode pairs, 3 channels of ECG signals are imported.

[0072] In the present embodiment, as shown in Figure 6 , three sets of electrode pairs are set so that two electrodes 11 that are just opposite each other in a state where the belt 10 is wound around the upper arm are paired with each other. This is because a larger potential difference (that is, an ECG signal with a high SN ratio) can be measured by separating the paired two electrodes 11 from each other. However, the method of setting electrode pairs is not limited thereto. For example, a multiplexer can be used to freely switch the combination of paired electrodes 11. In this case, it is also possible to measure 4 channels or more of ECG signals from the six electrodes 11.

[0073] In step S501, the ECG signal processing section 21 AD-converts the ECG signal and removes electromagnetic noise and baseline variation by digital signal processing. The removal of electromagnetic noise and baseline variation can use, for example, a band-pass filter, a notch filter, a moving average method, or the like, which is a known noise reduction technique.

[0074] In step S502, the ECG heart rate information calculation section 22 analyzes the imported ECG signal and calculates various heart rate information. The ECG heart rate information calculation section 22 executes the process of step S502 if time series data (waveform data) of a predetermined unit time amount of ECG signals is imported from the ECG signal processing section 21. The unit time is set to, for example, a time of 10 seconds to 600 seconds or so, and in the present embodiment, is set to 60 seconds.

[0075] As shown in Figure 7As shown schematically, the waveform of the ECG signal of 1 heart rate is mainly composed of a P wave, a QRS wave, and a T wave. Note that the QRS wave refers to a waveform in which an upward peak, i.e., an R wave, and downward Q and S waves appearing before and after the R wave are combined. In a normal heart, an electrical stimulus generated in a sinoatrial node is transmitted from an atrium to a ventricle, sequentially causing excitation (contraction) of the atrium and the ventricle, thereby sending blood. The P wave is a waveform corresponding to excitation of the atrium, the QRS wave is a waveform corresponding to excitation of the ventricle, and the T wave is a waveform corresponding to a process of recovery from excitation of the ventricle. In the case of an average adult, the number of heart rates is about 60 to 80 bpm, and thus the time series data of the ECG signal of the unit time (60 seconds) contains about 60 to 80 heart rate waveforms.

[0076] As the heart rate information, there are, for example, an R amplitude (height from a baseline of the R wave), a QRS amplitude (defined, for example, by the sum of the height from the baseline of the R wave and the depth from the baseline of the S wave), a P amplitude (height from a baseline of the P wave), a T amplitude (height from a baseline of the T wave), a P width (time from the start of the P wave to the end of the P wave), a QRS width (time from the start of the Q wave to the end of the S wave), a T width (time from the start of the T wave to the end of the T wave), a PQ time (time from the start of the P wave to the start of the Q wave), a QT time (time from the start of the Q wave to the end of the T wave), an RRI (RR interval; time from the peak of the R wave to the peak of the next R wave), a PPI (PP interval; time from the start of the P wave to the start of the next P wave), a heart rate variation (time variation of the RRI, the PPI), and the like. It is not necessary to calculate all of these heart rate information, and only the necessary heart rate information can be calculated. In addition, heart rate information other than these can be calculated.

[0077] In step S503, the ECG signal quality determination unit 23 evaluates the quality of the unit time amount of the ECG signal introduced in step S501. Any index can be used in the evaluation of the signal quality. For example, the noise, the power (intensity), the baseline variation, and the like of the ECG signal itself can be used as the evaluation index, and the heart rate information calculated in step S502 (also including whether the calculation of the heart rate information was successful) can be used as the evaluation index. In the case where the unit time amount of the ECG signal measured most recently is determined not to satisfy a predetermined quality (is data having a precision and reliability suitable for a diagnostic or the like purpose) (NO in step S504), the unit time amount of the ECG signal and the heart rate information are discarded.

[0078] When the ECG signal of predetermined quality is obtained (YES in step S504), the AF determination section 24 detects the occurrence of AF (atrial fibrillation) based on the heart rate information, or calculates an index related to AF (step S505). The heart rate information calculated in step S502 and the information of AF obtained in step S505 are stored in the storage section 25 together with the information of the measurement time (step S506).

[0079] The measurement processing described above is repeatedly performed per unit time, and 24-hour monitoring of the ECG signal is performed. Figure 5

[0080] (Determination processing of wearing state)

[0081] Figure 8 A flow of the determination processing of the wearing state in the first embodiment is shown.

[0082] After the user winds the band 10 around the upper arm and secures the band 10 with the fixing mechanism 13, if an operation of instructing the start of measurement is performed through the operation section 27, the processor of the control body 12 starts the measurement processing of Figure 5 , and also starts the determination processing of Figure 8 .

[0083] The wearing state determination section 33 of the control body 12 checks that the operation of instructing the start of measurement is performed by the user, and starts counting of the elapsed time Tp from when the electrode 11 is worn (step S100). Note that, in the present embodiment, although the user operation is used as a trigger for the counting of the elapsed time Tp, it can be configured to use an optical / electric / magnetic / physical sensor to check that the band 10 or the electrode 11 is worn on the arm to start the counting of the elapsed time Tp.

[0084] In step S101, the ECG signal quality determination section 23 extracts a feature quantity used in the determination processing of the wearing state from the waveform of the ECG signal per unit time. In the present embodiment, an interval in which the ECG signal is saturated or zero is called a "non-signal interval", and the length of the non-signal interval is used as the feature quantity.

[0085] The non-signal interval is described in detail using Figure 9A , Figure 9B , Figure 9C . Figure 9A An example of the waveform 90 of the ECG signal measured in a quiet state is shown, Figure 9B an example of the waveform 91 of the ECG signal disturbed due to the influence of physical activity is shown, Figure 9C ​An example of a waveform 92 showing an ECG signal measured in a case where the wearing of the electrode 11 is poor is shown. If the electrode 11 is away from the skin surface, the differential voltage of the electrode pair cannot be measured correctly, and the ECG signal is saturated or zero. Thus, in a case where the wearing state of the electrode 11 is poor (physical connection is unstable), as shown in the waveform 92, there is a tendency that a state in which the ECG signal is saturated or zero appears continuously for a certain time. In a case where myoelectric noise is mixed due to the influence of physical activity, as in the waveform 91, the differential voltage is also confused, and although the ECG signal momentarily reaches saturation or zero, the state of saturation or zero does not continue. Therefore, by evaluating the length of the non-signal interval, it is possible to distinguish between poor wearing of the electrode 11 and the influence of physical activity.

[0086] The ECG signal quality determination unit 23 temporarily stores the feature quantity extracted from the ECG signal of each of the three sets of electrode pairs in the storage unit 25. Note that in a case where a non-signal interval appears multiple times in a unit time amount of waveform, the longest time (the longest time of the non-signal interval) among them can be used as the feature quantity.

[0087] In step S102, the wearing state determination unit 33 determines whether the ECG signal used to extract the feature quantity in step S101 is a signal measured in a period after a predetermined time Tw has been reached in the elapsed time Tp. In a case where the elapsed time Tp has not reached the predetermined time Tw (Tp < Tw), the process returns to step S101. In the present embodiment, for example, Tw = 10 minutes is set.

[0088] After the elapsed time Tp has reached the predetermined time Tw (Tp ≥ Tw), the wearing state determination unit 33 determines whether the wearing state of the electrode 11 is good or not based on the feature quantity extracted from the waveform of the ECG signal (step S103). Specifically, the wearing state determination unit 33 determines that the possibility of electrode lift is high in a case where a non-signal interval of a length of the predetermined value Tth or more appears in the waveform of the ECG signal of at least any one of the electrode pairs, and determines "wearing state: poor". In a case where a non-signal interval of a length of the predetermined value Tth or more is not detected in the ECG signal of all the electrode pairs, it is determined that "wearing state: good". In the present embodiment, for example, Tth = 1 second is set.

[0089] In a case where the wearing state is determined to be poor (step S104), the reporting unit 34 reports to the user and urges to rewrap the belt 10 (step S105). The method of reporting is arbitrary. For example, it is conceivable to sound a warning sound, output a voice message urging to rewrap the belt 10, display a message on a display, report by vibration, light, transmit a message to an external device (a smartphone or the like held by the user), and the like.

[0090] In the determination process of this embodiment, the contact state between the electrode 11 and the skin surface is evaluated not by the ECG signal waveform immediately after the electrode 11 is worn, but by the ECG signal waveform during a predetermined period of time. By waiting for the moisture between the electrode 11 and the skin surface to increase sufficiently due to sweating before measuring and evaluating the ECG signal, measurement defects caused by insufficient moisture can be eliminated as much as possible. Therefore, it is possible to determine with high accuracy physical connection defects such as electrode 11 lifting (that is, the state where the band 10 needs to be rewound).

[0091] (Other features)

[0092] In the above embodiment, the length of the non-signal interval was extracted as a feature quantity of the ECG signal waveform, but other feature quantities can also be used to determine whether the wearing condition is good or bad. Hereinafter, as other examples of feature quantities, (1) peak amplitude and (2) noise mixing degree will be explained.

[0093] (1) Peak amplitude

[0094] Even if the physical connection between electrode 11 and the skin surface is good and ECG signal measurement is possible, if the ECG signal intensity is too weak and the peaks of the R wave, P wave, and T wave are unclear, it will lead to a decrease in the accuracy and reliability of heart rate information, or even failure to acquire heart rate information. Therefore, this is not preferable. In such cases, the situation can be improved by shifting the wearing position of electrode 11 upwards (closer to the shoulder). This is because the ECG signal becomes stronger the closer it is to the heart.

[0095] Therefore, for example, in step S101, the ECG signal quality determination unit 23 extracts the peak amplitude of the R-wave of the ECG signal as a characteristic quantity. Specifically, in the process of determining the wearing status, the peak amplitude of the R-wave of the ECG signal is used as a characteristic quantity. Figure 7 The values ​​of the R amplitude or QRS amplitude are shown. It should be noted that although there are dozens of R waves in the ECG signal waveform per unit time, representative values ​​such as the average, maximum, and minimum amplitudes can be used as characteristic quantities. Then, in step S103, the wearing status determination unit 33 compares the peak amplitude A of the ECG signal with the predetermined amplitude value Ath, and determines "wearing status: poor" if the peak amplitude A is less than the predetermined amplitude value Ath (A < Ath).

[0096] The amplitude value Ath serving as the determination reference can use a fixed value determined in advance, or can be dynamically decided in accordance with the measured ECG signal. The present inventors have obtained the following insight from the results of the test experiments: if the peak of the R wave is more than 3 times the fluctuation of the baseline portion including the P wave and the T wave, the heart rate information can be acquired with good accuracy. Therefore, in the present embodiment, the effective value (root mean square) of the entire ECG signal is regarded as a value corresponding to the fluctuation of the baseline portion, and the determination reference amplitude value Ath is decided as in the following equation.

[0097] Ath = 3 x RMSecg

[0098] Here, RMSecg is the effective value of the entire ECG signal or an interval of a portion thereof.

[0099] (2) Noise mixing degree

[0100] In a case where the physical connection state between the electrode 11 and the skin surface is good and the measurement of the ECG signal is possible, but the wetness between the electrode 11 and the skin surface is still insufficient, a large amount of noise can be mixed in the measured ECG signal, which can result in a decrease in the accuracy and reliability of the heart rate information, or failure to acquire the heart rate information. In that case, the skin can be applied with a skin lotion, a toner, or the electrode 11 can be wetted to eliminate the wetness deficiency.

[0101] Therefore, for example, in step S101, the ECG signal quality determination section 23 extracts the noise mixing degree of the ECG signal as a characteristic quantity. In a waveform in which noise caused by wetness deficiency is mixed in, fluctuations around 1 Hz appear in the baseline portion of the ECG signal. Therefore, for example, the effective value RMSecg of the entire ECG signal or an interval of a portion thereof is calculated, and this value is used as an index ND of the noise mixing degree. In step S103, the wearing state determination section 33 compares the noise mixing degree ND calculated from the ECG signal with a predetermined threshold value NDth, and in a case where the noise mixing degree ND is equal to or greater than the threshold value NDth (ND ≥ NDth), determines that the "wearing state: poor".

[0102] The threshold value NDth serving as the determination reference can use a fixed value determined in advance, or can be dynamically decided in accordance with the measured ECG signal. The present inventors have obtained the following insight from the results of the test experiments: in a waveform in which noise caused by wetness deficiency is mixed in, the effective value RMSecg is the same as or greater than the R amplitude. Therefore, the threshold value NDth can be set to the same degree as the R amplitude or the QRS amplitude, for example.

[0103] <Second Embodiment>

[0104] While it is considered that, as in the first embodiment, by providing a waiting time of a predetermined time Tw, in most cases, the insufficiency of wetness can be eliminated, there can be a certain number of people for whom the wetness between the electrode 11 and the skin will not be sufficient even if a sufficient time has elapsed. In addition, it can also depend on the environment (temperature, humidity, etc.) at the site. If it is a case of insufficiency of wetness as the cause, the condition cannot be improved by rewrapping the belt 10, and it is necessary to apply a skin lotion, a toner, or to wet the electrode to the skin, which is a countermeasure for improving the wetness between the electrode 11 and the skin surface. In addition, as described above, in a case where the amplitude of the peak is small, it is effective to make the wearing position of the electrode 11 close to the heart. Therefore, in the second embodiment, the cause of the badness of the wearing state is discriminated on the basis of the feature quantities extracted from the waveform of the ECG signal, and the report to the user is made different in accordance with the cause of the badness of the wearing state.

[0105] Figure 10 The flow of the determination processing of the wearing state in the second embodiment is shown. The same parts as the determination processing of the first embodiment are labeled with the same step numbers. Hereinafter, the processing different from the first embodiment will be described as the center.

[0106] In step S101, the ECG signal quality determination section 23 extracts three kinds of feature quantities of "length of non-signal interval", "peak amplitude", and "degree of noise mixing" from the ECG signal waveform of the unit time amount. The definition of each feature quantity and the extraction method are the same as in the first embodiment.

[0107] After the elapsed time Tp reaches the predetermined time Tw (step S102), the wearing state determination section 33 checks whether the length of the non-signal interval is less than a predetermined value Tth (step S200), whether the peak amplitude is the predetermined amplitude value Ath or more (step S202), and whether the degree of noise mixing is less than a predetermined threshold value NDth (step S204), respectively. In a case where all of the checks are affirmative, it is judged that "wearing state: good".

[0108] If, in the case where a non-signal section of a length of the predetermined value Tth or more is present (NO in Step S200), it is considered that the cause of the poor wearing is a physical connection failure such as electrode lift, the reporting section 34 urges the user to rewrap the belt 10 (Step S201). In the case where the peak amplitude is smaller than the predetermined amplitude value Ath (NO in Step S202), it is considered that the cause of the poor wearing is that the wearing position of the electrode 11 is away from the heart, and the reporting section 34 urges the user to move the wearing position of the electrode 11 upward (toward the shoulder side) (Step S203). In the case where the noise mixing degree is the predetermined threshold value NDth or more (NO in Step S204), it is considered that the cause of the poor wearing is that the moisture between the electrode 11 and the skin surface is insufficient, and the reporting section 34 urges the application of a moisturizing agent such as a skin lotion (Step S205).

[0109] According to the determination processing of the present embodiment, in addition to the same effects as the first embodiment, it has the advantage that in the case where the insufficient moisture is not eliminated due to the user's constitution, the environment, or the like, or in the case where the peak of the ECG signal is small, it is possible to provide a measurement device that can guide the user to an appropriate countermeasure and is excellent in usability.

[0110] <Third Embodiment>

[0111] In the first and second embodiments, the determination of the wearing state of the electrode 11 is performed after the predetermined time Tw elapses, but it is also possible to report to the user at the time point when the wearing failure is definitely determined before the predetermined time Tw elapses.

[0112] Figure 11 The flow of the determination processing of the wearing state in the third embodiment is shown. The same parts as the determination processing of the first embodiment are labeled with the same step numbers. Hereinafter, the processing different from the first embodiment will be described.

[0113] After the extraction of the characteristic quantities of the ECG signal waveform in Step S101, in Step S300, the wearing state determination section 33 determines whether or not the wearing state of the electrode 11 is good or not on the basis of the characteristic quantities extracted from immediately after the wearing of the electrode 11 to the current time point. In order to distinguish from the determination processing of Step S103, the determination processing of Step S300 is called "early determination processing". In the case where the wearing failure is determined in the early determination processing (Step S301), the reporting is immediately performed and the processing ends (Step S302). In the early determination processing, it is evaluated whether or not the characteristic quantities (values of the characteristic quantities or time changes thereof) extracted in the waveform of the ECG signal measured in the period until the predetermined time Tw is reached by the elapsed time Tp conform to the predetermined criteria. In the case where the wearing failure is not determined in the early determination processing (Step S301, YES), the determination processing of Step S103 is performed. Figure 12 An example of the predetermined criteria is shown.

[0114] (1) Reference 1 is that non-signal intervals of a length of the predetermined value Tth or more occur in all of the three sets of electrode pairs during the first period, but after that, during the second period, non-signal intervals of a length of the predetermined value Tth or more do not occur in a part of the electrode pairs.

[0115] In the case where the skin is dry, the electrical connection of the electrode 11 and the skin can not be smooth immediately after the electrode 11 is worn. In that case, non-signal intervals initially occur in all of the electrode pairs. Then, when the skin becomes wet due to sweating and the electrical connection becomes good, the non-signal intervals generally disappear in all of the electrode pairs. However, if the non-signal intervals disappear in a part of the electrode pairs, while the non-signal intervals still occur in the remaining electrode pairs, the possibility of physical connection failure such as electrode lifting in the remaining electrode pairs is high. Thus, in the case where the reference 1 is satisfied, the wearing state determination section 33 can immediately determine that the wearing is poor, and the reporting section 34 can urge the user to rewrap the belt 10.

[0116] (2) Reference 2 is that non-signal intervals of a length of the predetermined value Tth or more do not occur in all of the three sets of electrode pairs during the first period, but after that, during the second period, non-signal intervals of a length of the predetermined value Tth or more occur in a part of the electrode pairs.

[0117] In the case where the electrode 11 is in contact with the skin surface, the state where the non-signal intervals do not exist does not change to the state where the non-signal intervals exist. In other words, in the case where the change from the state where the non-signal intervals do not exist to the state where the non-signal intervals exist occurs as in the reference 2, the physical connection state between the electrode 11 and the skin surface is unstable, and the possibility of the electrode contact or separation due to the user's posture or body movement is high. Thus, in this case, the wearing state determination section 33 can immediately determine that the wearing is poor, and the reporting section 34 can urge the user to rewrap the belt 10.

[0118] (3) Reference 3 is that the electrode pairs in which the non-signal intervals of a length of the predetermined value Tth or more occur and the electrode pairs in which the non-signal intervals of a length of the predetermined value Tth or more do not occur are mixedly present in the three sets of electrode pairs.

[0119] Since the wet state of the six electrodes 11 is almost the same degree, it generally becomes any one of the following states: all of the three sets of electrode pairs have the non-signal interval, or all of the three sets of electrode pairs do not have the non-signal interval. In other words, as in Reference 3, in a case where the electrode pair having the non-signal interval and the electrode pair not having the non-signal interval are mixed, the possibility of occurrence of the connection failure such as electrode lifting in the electrode pair having the non-signal interval is high. Thus, in this case, the wearing state determination section 33 immediately determines that the wearing is poor, and the reporting section 34 urges the user to re-wind the belt 10. Since Reference 3 enables the determination by only one period of the ECG signal waveform, it is also possible to determine immediately after the electrodes 11 are worn.

[0120] By combining the above-described determination processes, it is possible to determine that the wearing is poor before the elapse of the time Tp reaches the predetermined time Tw in the case where the wearing is definitely determined to be poor, and to urge the user to cope with it. Thus, according to the present embodiment, it is possible to further improve the convenience of the device. Note that, here, the example in which the early determination process is incorporated in the determination flow of the first embodiment is described, but it is also possible to incorporate the early determination process in the determination flow of the second embodiment.

[0121] <Other>

[0122] The above-described embodiments are merely illustrative of the modes of the configuration example of the present application. The present application is not limited to the above-described specific embodiments, and various modifications can be made within the scope of the technical idea thereof. For example, the body part to which the wearing device is attached can be a part other than the upper arm. In addition, as the fixing member for fixing the electrodes 11 in the state where the electrodes 11 are pressed against the living body, in addition to the belt-shaped member that winds the electrodes 11 around the measurement part of the living body in the state where the electrodes 11 contact each other as in the above-described embodiments, a bag-shaped member that wraps in the state of covering the measurement part of the living body, or a ring-shaped member can be used. In addition, the fixing member can have stretchability or deformability in order to correspond to the size (diameter) of the measurement part of the living body. Alternatively, in the case of being made of a material that does not have stretchability, it can have a structure in which the length is adjustable. The number of electrodes 11 can be one or more. The arrangement of the plurality of electrodes 11 need not be in one row, and can be configured in a two-dimensional array. In addition, it can not be equidistant, but can have a deviation in the arrangement interval of the electrodes 11. The electrodes 11 can be integrated with the fixing member (belt 10), or can be a structure different from the fixing member. The control main body 12 can not be fixed to the belt 10. For example, the control main body 12 and the belt 10 can be different structures, and a cable can be used to connect between the control main body 12 and the belt 10 (electrodes 11). The biological signal of the measurement target is not limited to the ECG signal, and can be, for example, an electromyogram signal or an electroencephalogram signal.

[0123] The present specification includes the following disclosure.

[0124] [Para 1]

[0125] A biological signal measurement device (1) includes:

[0126] a dry electrode (11);

[0127] a member (10) that fixes the electrode (11) in a state where the electrode (11) is pressed against a living body; and

[0128] a control body (12) that measures a biological signal through the electrode (11),

[0129] the control body (12) has:

[0130] a waveform feature extraction section (23) that extracts a feature quantity from a waveform of a biological signal; and

[0131] a wearing state determination section (33) that determines whether or not a wearing state of the electrode (11) is good or not, based on a feature quantity extracted from a waveform of a biological signal measured in a period after an elapsed time from when the electrode (11) is worn on the living body by the member (10) reaches a predetermined time.

[0132] [Para 2]

[0133] In the biological signal measurement device (1) described in Para 1,

[0134] the predetermined time is set to a time of 5 minutes or more.

[0135] [Para 3]

[0136] In the biological signal measurement device (1) described in Para 1 or Para 2,

[0137] the waveform feature extraction section (23) extracts, as the feature quantity, a length of a non-signal section in which the biological signal is saturated or zero,

[0138] in a case where a non-signal section of a length of a predetermined value or more occurs, the wearing state determination section (33) determines that the wearing state is not good.

[0139] [Para 4]

[0140] In the biological signal measurement device (1) described in any one of Para 1 to Para 3,

[0141] In a case where a feature quantity extracted in a waveform of a biological signal measured during a period until the elapsed time reaches the predetermined time matches a predetermined reference, the wearing state determination unit (33) determines that the wearing state is poor before the elapsed time reaches the predetermined time.

[0142] [Para 5]

[0143] In the biological signal measuring apparatus (1) according to Para 4,

[0144] The dry electrodes include a plurality of electrode pairs (11, 11),

[0145] The waveform feature extraction unit (23) extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity,

[0146] The predetermined reference is that a non-signal interval of a length equal to or greater than a predetermined value occurs in all of the plurality of electrode pairs (11, 11) during a first period, but the non-signal interval of the length equal to or greater than the predetermined value no longer occurs in a part of the plurality of electrode pairs (11, 11) during a second period later than the first period.

[0147] [Para 6]

[0148] In the biological signal measuring apparatus (1) according to Para 4 or Para 5,

[0149] The dry electrodes include a plurality of electrode pairs (11, 11),

[0150] The waveform feature extraction unit (23) extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity,

[0151] The predetermined reference is that a non-signal interval of a length equal to or greater than a predetermined value does not occur in all of the plurality of electrode pairs (11, 11) during a first period, but the non-signal interval of the length equal to or greater than the predetermined value occurs in a part of the plurality of electrode pairs (11, 11) during a second period later than the first period.

[0152] [Para 7]

[0153] In the biological signal measuring apparatus (1) according to any one of Para 4 to Para 6,

[0154] The dry electrodes include a plurality of electrode pairs (11, 11),

[0155] the waveform feature extraction section (23) extracts, as the feature quantity, a length of a non-signal section in which the biological signal is saturated or zero,

[0156] The predetermined reference is that, among the plurality of electrode pairs (11, 11), an electrode pair (11, 11) in which a non-signal section of a length equal to or greater than a predetermined value occurs and an electrode pair (11, 11) in which a non-signal section of a length equal to or greater than the predetermined value does not occur coexist.

[0157] [Para 8]

[0158] The biological signal measurement device according to any one of Para 1 to Para 7,

[0159] The biological signal measurement device further has a reporting section (34) that reports to the user in a case where it is determined by the wearing state determination section (33) that the wearing state is poor.

[0160] [Para 9]

[0161] The biological signal measurement device (1) according to Para 8,

[0162] The wearing state determination section (33) determines a cause of the poor wearing state based on a feature quantity extracted from a waveform of the biological signal,

[0163] The reporting section (34) differentiates the reporting to the user according to the cause of the poor wearing state.

[0164] [Para 10]

[0165] The biological signal measurement device (1) according to Para 8 or Para 9,

[0166] The waveform feature extraction section (23) extracts, as the feature quantity, a length of a non-signal section in which the biological signal is saturated or zero,

[0167] In a case where it is determined by the wearing state determination section (33) that a non-signal section of a length equal to or greater than a predetermined value occurs, the reporting section (34) urges the user to re-wear the electrode (11).

[0168] [Para 11]

[0169] The biological signal measurement device (1) according to any one of Para 8 to Para 10,

[0170] The waveform feature extraction section (23) extracts, as the feature quantity, an amplitude of a peak included in the biological signal,

[0171] In a case where it is determined by the wearing state determination section (33) that the amplitude of the peak is smaller than a predetermined amplitude value, the reporting section (34) urges the user to change the wearing position of the electrode (11).

[0172] [Para 12]

[0173] In the biological signal measurement device (1) according to any one of Para 8 to Para 11,

[0174] The waveform feature extraction section (23) extracts a noise mixing degree of the biological signal as the feature quantity,

[0175] In a case where it is determined by the wearing state determination section (33) that the noise mixing degree is a predetermined threshold value or more, the reporting section (34) urges the user to take a countermeasure for improving the wetness between the electrode (11) and the skin surface.

[0176] [Para 13]

[0177] In the biological signal measurement device (1) according to any one of Para 1 to Para 12,

[0178] The control body (12) has an operation section (27) that is operated by the user after the electrode (11) is worn,

[0179] In a case where the operation of the operation section (27) is performed by the user, the control body (12) starts the counting of the elapsed time.

[0180] [Para 14]

[0181] In the biological signal measurement device (1) according to any one of Para 1 to Para 13,

[0182] The biological signal is an ECG (Electrocardiogram) signal.

[0183] [Para 15]

[0184] In the biological signal measurement device according to any one of Para 1 to Para 14,

[0185] The member (10) is a belt (10) provided with the electrode (11).

[0186] [Para 16]

[0187] In the biological signal measurement device (1) according to Para 15,

[0188] The belt (10) is worn on the upper arm of the living body.

[0189] [Para 17]

[0190] A control method of a biological signal measurement device (1) that measures a biological signal through a dry electrode (11), the control method having the steps of:

[0191] counting an elapsed time from when the electrode (11) is worn on a living body;

[0192] extracting a feature quantity from a waveform of the biological signal; and

[0193] determining whether or not the wearing state of the electrode (11) is good or not based on the feature quantity extracted in the waveform of the biological signal measured in a period after the elapsed time reaches a predetermined time.

[0194] Explanation of Reference Signs

[0195] 1: Biological signal measurement device, 10: strap, 11: electrode, 12: control body, 13: fixing mechanism.

Claims

1. A biological signal measurement apparatus comprising: a dry electrode; a member that fixes the electrode in a state in which the electrode is pressed against a living body; and a control body that measures a biological signal via the electrode, the control body having: a waveform feature extraction section that extracts a feature quantity from a waveform of the biological signal; and a wearing state determination section that determines whether or not a wearing state of the electrode is good or not based on the feature quantity extracted from the waveform of the biological signal measured in a period after an elapsed time from when the electrode is worn on the living body by the member reaches a predetermined time.

2. The biological signal measurement apparatus according to claim 1, wherein the predetermined time is set to a time of 5 minutes or more.

3. The biological signal measurement apparatus according to claim 1 or 2, wherein the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the wearing state determination section determines that the wearing state is not good in a case where a non-signal interval of a length of a predetermined value or more occurs.

4. The biological signal measurement apparatus according to any one of claims 1 to 3, wherein the wearing state determination section determines that the wearing state is not good before the elapsed time reaches the predetermined time in a case where a feature quantity extracted from a waveform of the biological signal measured in a period before the elapsed time reaches the predetermined time conforms to a predetermined reference.

5. The biological signal measurement apparatus according to claim 4, wherein the dry electrode includes a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined reference is that a non-signal interval of a length of a predetermined value occurs in all of the plurality of electrode pairs in a first period, but the non-signal interval of the length of the predetermined value no longer occurs in a part of the plurality of electrode pairs in a second period later than the first period.

6. The biological signal measurement apparatus according to claim 4 or 5, wherein the dry electrode includes a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined reference is that a non-signal interval of a length of a predetermined value does not occur in all of the plurality of electrode pairs in a first period, but the non-signal interval of the length of the predetermined value occurs in a part of the plurality of electrode pairs in a second period later than the first period.

7. The biological signal measurement apparatus according to any one of claims 4 to 6, wherein the dry electrode includes a plurality of electrode pairs, the waveform feature extraction section extracts a length of a non-signal interval in which the biological signal is saturated or zero as the feature quantity, and the predetermined reference is that a non-signal interval of a length of a predetermined value occurs in all of the plurality of electrode pairs in a first period, but the non-signal interval of the length of the predetermined value does not occur in a part of the plurality of electrode pairs in a second period later than the first period. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The predetermined reference is that, among the plurality of electrode pairs, an electrode pair in which a non-signal section of a length equal to or greater than a predetermined value occurs and an electrode pair in which a non-signal section of a length equal to or greater than the predetermined value does not occur are mixed.

8. The biological signal measuring apparatus according to any one of claims 1 to 7, wherein The biological signal measuring apparatus further has a reporting section that reports to the user in a case where the wearing state is determined to be poor by the wearing state determining section.

9. The biological signal measuring apparatus according to claim 8, wherein The wearing state determining section discriminates a cause of the poor wearing state based on a feature quantity extracted from the waveform of the biological signal, The reporting section makes the report to the user different depending on the cause of the poor wearing state.

10. The biological signal measuring apparatus according to claim 8 or 9, wherein The waveform feature extracting section extracts a length of a non-signal section in which the biological signal is saturated or zero as the feature quantity, In a case where a non-signal section of a length equal to or greater than a predetermined value is determined to have occurred by the wearing state determining section, the reporting section urges the user to re-wear the electrode.

11. The biological signal measuring apparatus according to any one of claims 8 to 10, wherein The waveform feature extracting section extracts an amplitude of a peak included in the biological signal as the feature quantity, In a case where the amplitude of the peak is determined to be smaller than a predetermined amplitude value by the wearing state determining section, the reporting section urges the user to change a wearing position of the electrode.

12. The biological signal measuring apparatus according to any one of claims 8 to 11, wherein The waveform feature extracting section extracts a noise mixing degree of the biological signal as the feature quantity, In a case where the noise mixing degree is determined to be equal to or greater than a predetermined threshold value by the wearing state determining section, the reporting section urges the user to a countermeasure for improving wetness between the electrode and the skin surface.

13. The biological signal measuring apparatus according to any one of claims 1 to 12, wherein The control body has an operation section that is operated by the user after the electrode is worn, In a case where the operation section is operated by the user, the control body starts counting of the elapsed time.

14. The biological signal measuring apparatus according to any one of claims 1 to 13, wherein The biological signal is an ECG (Electrocardiogram) signal.

15. The biological signal measuring apparatus according to any one of claims 1 to 14, wherein The member is a belt provided with the electrode.

16. The biological signal measuring apparatus according to claim 15, wherein The belt is worn on the upper arm of the living body.

17. A control method of a biological signal measuring apparatus that measures a biological signal by an electrode of a dry type, the control method having the steps of: counting an elapsed time from when the electrode is worn on a living body; extracting a feature quantity from a waveform of the biological signal; and based on the feature quantity extracted from the waveform of the biological signal measured during the period after the elapsed time reaches the predetermined time, determining whether the wearing state of the electrode is good or not.

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