Biological signal measuring device and state analysis system

Abstract

The invention relates to a biological signal measuring apparatus and a state analysis system. When viewed from the side surface of a first earmuff (42R) of a biological signal measuring device (14), a straight line which is parallel to the direction in which a headband (40) extends downward and passes through the center of gravity (O1) of a planar region defined by the first earmuff (42R) is defined as a first reference line (LV), and a straight line which is orthogonal to the first reference line (LV) and passes through the center of gravity (O1) is defined as a second reference line (LH). The first position (P3) is located on the front side of the first reference line (LV) and on the lower side of the second reference line (LH).

Description

Technical Field

[0001] The present invention relates to a biological signal measuring device and a state analyzing system. Background Art

[0002] In the past, in various fields including medicine, health, nursing, and sports, it is known that various sensors are used to detect the movement or state of the measured person, and the obtained detection data are used to analyze the various states of the measured person. As an example of this technology, it is known that a brain-computer interface is operated mechanically according to the signal strength of the natural frequency contained in the brain wave signal by pre-analyzing the brain wave signal to identify the natural frequency representing the movement intention, cognitive state, or fatigue state of the measured person.

[0003] As an example of brain wave fluctuations that are highly correlated with motor intentions and are generated at natural frequencies, sensorimotor rhythm event-related desynchronization (hereinafter referred to as SMR-ERD) can be cited. The SMR-ERD is estimated based on, for example, a signal representing the difference between a biological signal measured from an electrode portion disposed on the top of the head and a biological signal measured from an electrode portion disposed on the left motor area (or right motor area) (hereinafter also referred to as an SMR-ERD signal).

[0004] Patent Document 1 discloses an electroencephalogram device that has a ground electrode disposed behind the ear when worn on the head. Thus, by providing the ground electrode at a location on the head that is not easily affected by the bioelectric potential from brain activity, a stable ground potential can be obtained.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-076712

[0008] Non-patent literature

[0009] Non-patent document 1: Biotechnology and Industrial Technology Research Institute (1996) Human Dimension Dataset for Design, Japan Publishing Service, ISBN 4-88922-093-3C3040 P4635E

[0010] Non-patent document 2: Du, et al. "Head-and-Face Anthropometric Survey of Chinese Workers", Annual Occupational Hygiene Society, Vol. 52, No. 8, pp. 773-782, 2008, doi: 10.1093 / annhyg / men056

[0011] Non-patent document 3: Gordon et al., "Anthropometric Survey of USArmyPersonnel:Summary Statistics, Interim Report for 1988, UNITED STATES ARMYNATICKRESEARCH DEVELOPMENT AND ENGINEERING CENTER, Accession Number: ADA209600 Summary of the invention

[0012] Problems to be solved by the invention

[0013] However, the electroencephalogram device disclosed in Patent Document 1 can measure or analyze brain activity, but cannot measure or analyze muscle activity occurring around the head including the masseter muscle and the sternocleidomastoid muscle.

[0014] The present invention has been completed in view of such problems, and its object is to provide a biological signal measuring device and a state analysis system that have a simpler device structure and can perform various measurements or analyses taking into account muscle activities generated around the head.

[0015] Solutions for solving problems

[0016] The biological signal measuring device of the present invention comprises: a headband having an inverted U-shape and being wearable on the head of a person to be measured; a first earmuff provided at one end of the headband and covering one ear of the head when the headband is worn; a second earmuff provided at the other end of the headband and covering the other ear of the head when the headband is worn; a first protruding member extending from a first position of an outer edge of the first earmuff; and a first cover-side electrode portion provided at a front end side of the first protruding member and used for measuring the biological signal of the person to be measured, wherein when a straight line parallel to a direction in which the headband extends downward and passing through a center of gravity of a plane area formed by the first earmuff is defined as a first reference line, and a straight line orthogonal to the first reference line and passing through the center of gravity is defined as a second reference line, the first position is located in front of the first reference line and below the second reference line.

[0017] Furthermore, at least a front end portion of the first protruding member may be provided to extend obliquely forward and inward with respect to the first position.

[0018] In addition, the biological signal measuring device may also include a band side electrode portion, which is mounted on the headband and is used to measure the biological signal of the head, and the biological signal measuring device differentially amplifies and outputs a first biological signal obtained from the band side electrode portion and a second biological signal obtained from the first cover side electrode portion.

[0019] In addition, the biological signal measuring device may also include: a second protruding member extending from a second position on the outer edge of the second earmuff; and a second cover-side electrode portion, provided on the front end side of the second protruding member, for measuring the biological signal of the person being measured. When a straight line parallel to the direction in which the headband extends downward and passes through the center of gravity of the plane area formed by the second earmuff is defined as a third reference line, and a straight line orthogonal to the third reference line and passing through the center of gravity is defined as a fourth reference line, the second position is located behind the third reference line and below the fourth reference line when observed from the side of the second earmuff.

[0020] The state analysis system of the present invention comprises: any one of the above-mentioned biological signal measuring devices; and a state analysis device that performs analysis processing on the biological signal measured by the biological signal measuring device to analyze the movement intention, cognitive state or fatigue state of the subject.

[0021] Effects of the Invention

[0022] According to the present invention, while having a simpler device configuration, various measurements or analyses can be performed taking into account muscle activity occurring around the head. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an overall configuration diagram of a state analysis system according to one embodiment of the present invention.

[0024] Figure 2 yes Figure 1 Front view of the headset shown.

[0025] Figure 3 yes Figure 1 A top view of the headset is shown.

[0026] Figure 4 yes Figure 1 A bottom view of the headset is shown.

[0027] Figure 5 yes Figure 1 Right side view of the headset shown.

[0028] Figure 6 It is a schematic diagram showing the positional relationship of the three electrode parts.

[0029] Figure 7 It is a diagram schematically showing the positional relationship between three electrode units and the target area.

[0030] Figure 8 This is a diagram showing an example of temporal changes in electroencephalogram signals.

[0031] Fig. 9 It is a diagram schematically showing an activation region of the SMR-ERD signal.

[0032] Fig.10 It is a diagram schematically showing a high correlation region of the SMR-ERD signal.

[0033] Fig.11 This is a diagram showing the basis for determining the target area.

[0034] Fig.12 This is a diagram showing a subject wearing headphones as seen from the right side.

[0035] Fig.13 This is a diagram showing a subject wearing headphones as seen from the left side. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the description, the same components are denoted by the same reference numerals as much as possible in the drawings, and repeated descriptions are omitted.

[0037] [Configuration of the State Analysis System 10]

[0038] <Overall structure>

[0039] Figure 1 1 is an overall configuration diagram of a state analysis system 10 of an embodiment of the present invention. The state analysis system 10 functions as a brain-machine interface system (hereinafter referred to as a BMI system) that analyzes the brain wave signals emitted by the subject 12 and assists the movement of the subject 12 based on the analysis results. Specifically, the state analysis system 10 is configured to include: a headset 14 (equivalent to a "biological signal measuring device"), a state analysis device 16, and a movement assisting device 18.

[0040] The headset 14 is configured to measure an electrical signal (i.e., a biological signal) related to the state of the subject 12 when worn on the head H of the subject 12. The headset 14 measures the biological signal via a plurality of electrodes and outputs the obtained biological signal to the state analysis device 16 via wireless communication or wired communication.

[0041] The state analysis device 16 is a computer configured to analyze the state (e.g., movement intention, cognitive state, or fatigue state) of the subject 12 based on the biological signal measured by the headset 14. Specifically, the state analysis device 16 includes an operation unit 22, a prompt unit 23, a sensor controller 24, a processor 26, and a memory 28.

[0042] The operation unit 22 is configured so that various operations can be performed by users including the subject 12 and medical practitioners. The operation unit 22 is, for example, an input device including operation buttons and a microphone, or an output device including a display panel and a speaker.

[0043] The prompting unit 23 is an output device that prompts the subject 12 with information for requesting a quiet state (hereinafter, also referred to as request information) according to an instruction from the processor 26. The prompting unit 23 is composed of, for example, a display panel, a lamp, a speaker, etc. As an example of a method of prompting the request information, guidance based on text or voice, lighting of a lamp, output of various types of sounds, etc. can be listed. It should be noted that the subject of the prompt request information is not limited to the prompting unit 23 of the state analysis device 16, but may also be a person different from the subject 12 (for example, an operator of the state analysis device 16).

[0044] The sensor controller 24 is a control circuit that performs various controls on the headset 14. The sensor controller 24 can perform various signal processing including, for example, synchronous sampling processing of the sensor, low-pass filtering processing, and A / D conversion processing. Thus, the sensor controller 24 acquires an electrical signal (i.e., a biological signal) related to the state of the person being measured 12 at a predetermined sampling interval, and supplies the biological signal to the processor 26. Specifically, the sampling interval can take any value in the range of 0.5 ms to several 100 ms.

[0045] The processor 26 comprehensively controls each unit constituting the state analysis device 16. The processor 26 may be a general-purpose processor including a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), or a dedicated processor including an FPGA (Field Programmable Gate Array) or a GPU (Graphics Processing Unit).

[0046] The memory 28 is a non-transitory storage medium including a ROM (Read Only Memory) and a RAM (Random Access Memory), and stores programs and data necessary for the processor 26 to control each component.

[0047] The motion assisting device 18 is, for example, an actuator that can be worn on a target part (in the example of this figure, arm A) of the subject 12. As an example of the target part, various body parts that perform extension or bending movements, such as hands, feet, fingers, knees, and elbows, can be listed. It should be noted that the motion assisting device 18 is an arbitrary structure and can be excluded from the state analysis system 10 as needed.

[0048] <Configuration of the headphone 14>

[0049] Next, refer to Figure 2 to Figure 6 The configuration of the headphones 14 will be described. Figure 2 yes Figure 1 A front view of the headset 14 is shown. Figure 3 yes Figure 1 A top view of the headset 14 is shown. Figure 4 yes Figure 1 A bottom view of the headset 14 is shown. Figure 5 yes Figure 1 A right side view of the headset 14 is shown.

[0050] Hereinafter, the front-back direction, the left-right direction, and the up-down direction are defined based on the orientation of the head H of the subject 12 wearing the headset 14 correctly. Figure 2 to Figure 5 , five electrode portions EL0 to EL4 are removed. Figure 2 ), but in fact the headphone 14 is used in a state equipped with the electrode parts EL0~EL4.

[0051] like Figure 2 to Figure 5 As shown, the headphones 14 include a headband 40 , an earmuff 42R (corresponding to a “first earmuff”) provided at the right end of the headband 40 , and an earmuff 42L (corresponding to a “second earmuff”) provided at the left end of the headband 40 .

[0052] The headband 40 is a belt-shaped member having an inverted U-shape and is formed of an insulating material such as resin. The headband 40 is provided with a length adjustment mechanism 44R (equivalent to a "first adjustment mechanism") for adjusting the length of the right side and a length adjustment mechanism 44L (equivalent to a "second adjustment mechanism") for adjusting the length of the left side.

[0053] The length adjustment mechanism 44R is composed of a substantially arc-shaped belt body 46 and a sliding member 48R that is slidable and retractable from the right end of the belt body 46. The length adjustment mechanism 44L is composed of the above-mentioned belt body 46 and a sliding member 48L that is slidable and retractable from the left end of the belt body 46.

[0054] Three holes Mh0, Mh1, and Mh2 are formed on the inner side 50 of the belt body 46. The electrode portion EL0 (equivalent to the "central electrode portion") is detachably provided in the central hole portion Mh0. The electrode portion EL1 (equivalent to the "first electrode portion") is detachably provided in the hole portion Mh1 on the right side. The electrode portion EL2 (equivalent to the "second electrode portion") is detachably provided in the hole portion Mh2 on the left side. The electrode portions EL0 to EL2 are configured to include metal electrodes for acquiring biological signals. As an example of a metal electrode, a silver-silver chloride electrode, a silver electrode, a gold electrode, and a platinum electrode can be listed. In addition, the electrode portions EL0 to EL2 can be composed of only one type of electrode having the same material and thickness, or can be composed of two or more types having different materials or thicknesses.

[0055] Figure 6This is a diagram schematically showing the positional relationship of the three electrode portions EL0 to EL2. This figure shows a state where the curved belt body 46 is horizontally unfolded. The electrode portion EL0 is arranged at a position P0 approximately in the center in the extension direction of the belt body 46. The electrode portion EL1 is arranged at a position P1 located on the right side of the position P0. The electrode portion EL2 is arranged at a position P2 located on the left side of the belt body 46 located at the position P0. Here, if the distance between the two points P0 and P1 is set to D1 (unit: mm), and the distance between the two points P0 and P2 is set to D2 (unit: mm), the relationship D1=D2 is satisfied. Alternatively, it can be any of the size relationships of D1>D2 and D1<D2.

[0056] Position P1 is located within the allowable region 52 set in relation to position P0. The allowable region 52 is a rectangular region within a range of 56.2 to 80.0 mm located on the right side of position P0. That is, distance D1 satisfies the magnitude relationship of 56.2 ≤ D1 ≤ 80.0.

[0057] Position P2 is located in the allowable area 54 set in relation to position P0. This allowable area 54 is a rectangular area within a range of 56.2 to 80.0 mm located on the left side of position P0. That is, distance D2 satisfies the magnitude relationship of 56.2 ≤ D2 ≤ 80.0.

[0058] Return to Figure 2 to Figure 5 The right earmuff 42R is composed of a shell 60R, an ear cup 62R and a protruding member 64R.

[0059] The housing 60R has a bottomed cylindrical shape with an open top, and is formed of an insulating material such as resin. It contains a sensor substrate (not shown). The sensor substrate is mounted with a sensor for acquiring a biological signal of the subject 12 and outputting it to the state analysis device 16 ( Figure 1 The bottom of the housing 60R is swingably connected to the right end of the headband 40 (ie, the front end of the slide member 48R).

[0060] The ear cup 62R has a disk-like shape and is formed of an insulating material such as resin. The ear cup 62R is provided to cover the opening of the housing 60R. An annular concavoconvex portion for positioning the left ear of the subject 12 is formed on the main surface of the ear cup 62R.

[0061] The protruding member 64R has a C-shaped shape and is formed of an insulating material such as resin. The protruding member 64R is provided from the outer edge portion ( Figure 5 A hole portion Mh3 is formed at the front end side of the protruding member 64R. The electrode portion EL3 (equivalent to the "first cover side electrode portion") is detachably provided in the hole portion Mh3.

[0062] On the other hand, the left earmuff 42L includes a housing 60L, an ear cup 62L, and a protruding member 64L, similarly to the right earmuff 42R.

[0063] The housing 60L has a bottomed cylindrical shape with an open top, and is formed of an insulating material such as resin. It contains a sensor substrate (not shown). The sensor substrate is mounted with a sensor for acquiring a biological signal of the subject 12 and outputting it to the state analysis device 16 ( Figure 1 The bottom of the housing 60L is swingably connected to the left end of the headband 40 (ie, the front end of the slide member 48L).

[0064] The ear cup 62L has a disk-like shape and is formed of an insulating material such as resin. The ear cup 62L is provided to cover the opening of the housing 60L. An annular concavoconvex portion for positioning the left ear of the subject 12 is formed on the main surface of the ear cup 62L.

[0065] The protruding member 64L has a C-shaped shape and is formed of an insulating material such as resin. The protruding member 64L is provided from the outer edge portion ( Figure 5 A hole Mh4 is formed on the front end side of the protruding member 64L. The electrode portion EL4 (equivalent to the "second cover-side electrode portion") is detachably provided in the hole portion Mh4.

[0066] like Figure 5 As shown, when the headphone 14 is viewed from the right side, the center of gravity position of the plane area formed by the earmuff 42R (more specifically, the housing 60R) is defined as O1. In addition, a straight line parallel to the direction in which the headband 40 extends downward (hereinafter referred to as the first direction) and passing through the center of gravity position O1 is defined as a vertical reference line LV (equivalent to the "first reference line"). In addition, a straight line extending in a direction orthogonal to the first direction (hereinafter referred to as the second direction) and passing through the center of gravity position O1 is defined as a horizontal reference line LH (equivalent to the "second reference line"). In this case, the position P3 is located in front of the vertical reference line LV and below the horizontal reference line LH.

[0067] Similarly, when the headphone 14 is viewed from the left side, the center of gravity position of the plane area formed by the earmuff 42L (more specifically, the housing 60L) is defined as O2. In addition, a straight line parallel to the first direction extending downward from the headband 40 and passing through the center of gravity position O1 is defined as a vertical reference line LV (equivalent to the "third reference line"). In addition, a straight line extending in a second direction orthogonal to the first direction and passing through the center of gravity position O2 is defined as a horizontal reference line LH (equivalent to the "fourth reference line"). In this case, the position P4 is located behind the vertical reference line LV and below the horizontal reference line LH.

[0068] [First effect]

[0069] The state analysis system 10 of this embodiment is configured as described above. Figure 1 to Figure 6 In addition, refer to Figure 7 to Figure 11 A first operation and effect of the headphones 14 constituting a part of the state analysis system 10 will be described.

[0070] <Function>

[0071] Here, it is assumed that the state analysis system 10 is used to identify the individual SMR-ERD frequency (ie, ISF) unique to the subject 12. Here, the "SMR-ERD frequency" refers to the frequency at which the event-related desynchronization (ERD: event-related desynchronisation) as a movement-related response is strong in the α segment of 8Hz to 13Hz of the scalp electroencephalogram measured near the motor cortex. It is known that the SMR-ERD frequency varies from 8Hz to 13Hz for each person. Therefore, in order to make it clear that it is a frequency inherent to an individual, it is sometimes called the individual SMR-ERD frequency (ie, ISF).

[0072] In order to obtain EEG signals containing spectral components of multiple SMR-ERD frequencies, we used Figure 2 to Figure 6 The headphone 14 shown. Before the measurement of the brain wave signal, the subject 12 wears the headphone 14 on his head H. Specifically, the subject 12 holds the headphone 14 with both hands, fixes one earmuff 42R on the right ear, and fixes the other earmuff 42L on the left ear. After that, the subject 12 uses the length adjustment mechanisms 44R and 44L of the headband 40 to adjust the length of the headband 40 so that the inner side surface 50 of the headband 40 fits the surface of the head H. Through this length adjustment, the three electrode parts EL0, EL1, and EL2 are positioned at the same time.

[0073] Figure 7Schematically shows the positional relationship between the three electrode portions EL0 to EL2 and the target areas 70R and 70L. Here, it is assumed that two subjects 12 with different head H sizes wear the same headset 14. For ease of explanation, the heads H1 and H2 of the subjects 12 are shown as ellipses. By positioning the headset 14 as described above, the electrode portion EL0 is arranged on the top of the head regardless of the size of the heads H1 and H2.

[0074] On the other hand, the position of the target area 70R of the right motor area (or the target area 70L of the left motor area) is different depending on the size of the head H1 and H2. The target areas 70R and 70L represent areas where the electroencephalogram signal (i.e., SMR-ERD signal) containing the spectral component at the SMR-ERD frequency can be measured with higher accuracy. Here, the three electrodes EL0 to EL2 satisfy Figure 6 In the case of the positional relationship shown, regardless of the “difference” in the size of the heads H1 , H2 , the electroencephalogram signals in the target areas 70R, 70L are measured simultaneously using the same headphones 14 .

[0075] <Basis of target areas 70R and 70L>

[0076] Next, refer to Figure 8 to Figure 11 For determining Figure 7 The position and size of the target areas 70R and 70L shown in the figure are described below. It should be noted that the inventors obtained brain wave data from 82 subjects in order to independently determine the target areas 70R and 70L, and analyzed the brain wave data. The brain wave data was obtained using a brain wave measuring device that can measure 129 channels of high-density brain waves throughout the head. Through this analysis, the detailed distribution of the activation area of ​​the SMR-ERD signal can be obtained.

[0077] Figure 8 This is a graph showing the temporal changes of the electroencephalogram signal at rest. The horizontal axis of the graph represents time (unit: s), and the vertical axis of the graph represents brain potential (unit: μV). As can be understood from this graph, the electroencephalogram signal has a complex waveform that varies slightly up and down around a reference value.

[0078] Fig. 9This is a diagram schematically showing the activation area 72L of the SMR-ERD signal. Each point within the circular area in this figure represents the measurement position of the electroencephalogram signal at the head H. The three points surrounded by squares represent the C3 position, Cz position, and C4 position in the international 10-20 method from left to right. Each point surrounded by a triangle corresponds to a measurement position that is determined to be activated based on the relationship with the electroencephalogram signal obtained at the C3 position. That is, the closed curve enveloping all the triangles defines an area that is approximately the activation amount at the C3 position (hereinafter referred to as "activation area 72L").

[0079] For example, in the time period when the ERD value at the C3 position is positive, (ERD value - standard deviation) at the C3 position is used as a threshold value, and when the ERD value at each measurement position exceeds the threshold value, it is determined to belong to the activation area 72L. Here, the number of samples of the subjects 12 is N = 82, and the ERD value is calculated based on the average value (N = 82) of the central value obtained from the time series data of each subject 12.

[0080] Fig.10 This is a diagram schematically showing the high correlation area 74L of the SMR-ERD signal. Each point within the circular area in this figure represents the measurement position of the electroencephalogram signal at the head H. The three points surrounded by squares represent the C3 position, Cz position, and C4 position in the international 10-20 method from left to right. Each point surrounded by a circle corresponds to a measurement position that is determined to have high time correlation based on the relationship with the electroencephalogram signal acquired at the C3 position. That is, the closed curve that envelops all circles defines an area that is similar to the time series signal at the C3 position (hereinafter referred to as the "high correlation area 74L").

[0081] For example, in the time period when the ERD value at the C3 position is positive, the correlation coefficient between the time series data of the ERD value at the C3 position and the time series data of the ERD value at each measurement position is obtained, and when it exceeds a predetermined threshold value (for example, 0.55), it is determined that it belongs to the high correlation area 74L. Here, the number of samples of the subjects 12 is N=82, and the correlation coefficient is calculated based on the average value (N=82) of each value obtained for each subject 12.

[0082] Fig.11 This figure is equivalent to Fig. 9 and Fig.10A partial enlarged view of the C3 position in . Each point surrounded by a triangle corresponds to a measurement position belonging to the activation area 72L, and each point surrounded by a circle corresponds to a measurement position belonging to the high correlation area 74L. That is, each point surrounded by both the triangle and the circle belongs to the overlapping area between the activation area 72L and the high correlation area 74L (i.e., the target area 70L). As can be understood from this figure, the target area 70L has a circular shape with a diameter of 50 mm (radius 25 mm) centered on the C3 position. In this way, the inventors determined that an SMR-ERD signal can be acquired by configuring the electrode portion EL2 in the circular target area 70L with a diameter of 50 mm.

[0083] It should be noted that in Figures 9 to 11 In the example, the relationship between the target area 70L on the left and the C3 position is described, and the relationship between the target area 70R on the right and the C4 position is the same. The reason is that the left-right symmetry of brain function can be basically observed with respect to the SMR-ERD frequency. Similarly to the above, the inventors have determined that the SMR-ERD signal can be measured by configuring the electrode portion EL1 in the circular target area 70R with a diameter of 50 mm.

[0084] <Basis for Arrangement of Electrode Sections EL0 to EL2>

[0085] Next, the basis for determining the arrangement of the electrode portions EL0 to EL2 that can correspond to various heads H is described. In the above-mentioned non-patent document 1, the dimension data of the "arc length between the tragus and the top of the head" of Japanese people was measured for a total of 500 people, including 250 males and 250 females aged 18 to 88 years old. In the above-mentioned non-patent document 2, the dimension data of the "arc length between the tragus and the top of the head" of Chinese people was measured for a total of 3000 people, including 2026 males and 974 females aged 18 to 66 years old. In the above-mentioned non-patent document 3, the dimension data of the "arc length between the tragus and the top of the head" of Americans was measured for a total of 3982 people, including 1774 males and 2208 females aged 18 to 88 years old. The arc length between the tragus and the top of the head is the length from the tragus point on one side through the top of the head to the tragus point on the other side, and is measured in a manner perpendicular to the ear-eye plane. In addition, this length is measured using a tape measure while the person being measured is sitting on a chair.

[0086] As described in the above-mentioned non-patent document 1, the minimum value of the arc length between the tragus and the top of the head in the human body size DB of Japanese people is 316 mm, and the maximum value is 405 mm. If the electrode parts EL1 and EL2 are present in the range (i.e., the target areas 70R and 70L) where the SMR-ERD signal can be measured for both the maximum value and the minimum value, the SMR-ERD signal can be measured even for the intermediate value.

[0087] This time, we will focus on the area with a radius of 25mm centered on C3 (or C4). Before calculating this area, find the distance between Cz and C3 in the International 10-International 20 method. According to the definition of the International 10-International 20 method, the distance between Cz and C3 is equivalent to 20% of the total arc length of the top of the head between the tragus. In other words, the minimum value of the distance between Cz and C3 is 316×0.2=63.2mm, and the maximum value is 405mm×0.2=81.0mm.

[0088] As described above, the radius of the target area 70R, 70L is 25 mm, so in the case of the head H having the smallest size, the measurement position can be within the range of 63.2 mm ± 25 mm = 38.2 to 88.2 mm. On the other hand, in the case of the head H having the largest size, the measurement position can be within the range of 81.0 mm ± 25 mm = 56.0 to 106.0 mm. In this way, by setting the measurement position within the range of 56.0 to 88.2 mm, which is the intersection of the above two ranges, it is possible to measure SMR to ERD signals for most Japanese people.

[0089] In the above example, a method of determining a preferred measurement range when Japanese are used as a population is shown, but a preferred measurement range for other populations (eg, Chinese, Americans) can be calculated by the same method.

[0090] As described in the above-mentioned non-patent document 2, the minimum value of the arc length between the tragus and the top of the head in the human body size DB of the Chinese is 275 mm, and the maximum value is 406 mm. Regarding the distance between Cz and C3, the minimum value is 275×0.2=55.0 mm, and the maximum value is 406 mm×0.2=81.2 mm. In the case of a head H with the smallest size, the measurement position can be in the range of 55.0 mm±25 mm=30.0 to 80.0 mm, and in the case of a head H with the largest size, the measurement position can be in the range of 81.2 mm±25 mm=56.2 to 106.2 mm. In this way, by setting the measurement position in the range of 56.2 to 80.0 mm, which is the intersection of the above two ranges, the SMR-ERD signal can be measured for most Chinese people.

[0091] As described in the above-mentioned non-patent document 3, the minimum value of the arc length between the tragus and the top of the head in the human body size DB of Americans is 298 mm, and the maximum value is 392 mm. Regarding the distance between Cz and C3, the minimum value is 298×0.2=59.6 mm, and the maximum value is 392 mm×0.2=78.4 mm. In the case of a head H with the smallest size, the measurement position can be within the range of 59.6 mm±25 mm=34.6~84.6 mm, and in the case of a head H with the largest size, the measurement position can be within the range of 78.4 mm±25 mm=53.4~103.4 mm. In this way, by setting the measurement position within the range of 53.4~84.6 mm, which is the intersection of the above two ranges, the SMR-ERD signal can be measured for most Americans.

[0092] Based on the above considerations, the intersection of the range of 56.2 to 80.0 mm (which is the intersection of [1] 56.0 to 88.2 mm (for Japanese), [2] 56.2 to 80.0 mm (for Chinese), and [3] 53.4 to 84.6 mm (for Americans) is used. Figure 6 By setting the measurement position within the allowable area 52, 54), the SMR-ERD signal can be measured for most adults.

[0093] <Effect>

[0094] As described above, the state analysis system 10 of the present embodiment comprises: a biological signal measuring device (here, a headset 14) for measuring the biological signal of the subject 12; and a state analysis device 16 for performing analysis processing on the biological signal measured by the headset 14 to analyze the movement intention, cognitive state or fatigue state of the subject 12.

[0095] The headset 14 includes a headband 40 having an inverted U-shape and wearable on the head H of the subject 12, and a plurality of electrode portions attached to the headband 40 for measuring biological signals of the head H. The plurality of electrode portions are composed of a central electrode portion (herein, the electrode portion EL0) disposed at a central position P0 in the extending direction of the headband 40, a first electrode portion (herein, the electrode portion EL1) disposed at a position P1 away from the position P0 by a predetermined distance D1 toward one end of the headband 40, and a second electrode portion (herein, the electrode portion EL2) disposed at a position P2 away from the position P0 by a predetermined distance D2 toward the other end of the headband 40. The predetermined distances D1 and D2 are any values ​​between 56.2 and 80.0 mm.

[0096] In this way, since the electrodes EL0 to EL2 are arranged in a positional relationship that takes into account the deviation in the size of the head H of the person being measured 12, by positioning the electrode EL0 at the top of the head, the remaining electrodes EL1 and EL2 can be simultaneously arranged in the desired target areas 70R and 70L. As a result, there is no need to provide a mechanism for adjusting the positions of the electrodes EL0 to EL2, and the device configuration is simpler, while the reduction in the measurement accuracy of the SMR-ERD signal caused by the deviation in the size of the head H can be suppressed.

[0097] In addition, the headphones 14 may further include: a first earmuff (here, the earmuff 42R) provided at one end of the headband 40 to cover one ear of the head H when the headband 40 is worn; and a second earmuff (here, the earmuff 42L) provided at the other end of the headband 40 to cover the other ear of the head H when the headband 40 is worn. By covering both ears with the pair of earmuffs 42R and 42L, the headband 40 can be positioned at least in the front-rear direction.

[0098] In addition, the headband 40 may include a length adjustment mechanism 44R that adjusts the length from the electrode portion EL1 to the earmuff 42R, and a length adjustment mechanism 44L that adjusts the length from the electrode portion EL2 to the earmuff 42L. After covering both ears with the pair of earmuffs 42R and 42L, the length of the headband 40 can be adjusted using the pair of length adjustment mechanisms 44R and 44L, so that the headband 40 can be further positioned in the left-right direction.

[0099] Furthermore, the plurality of electrode portions may include two or more electrode portions having different thicknesses, and the two or more electrode portions may be configured to be detachable from the headband 40. Thus, the biological signal can be measured while the electrode portion is replaced as needed, and a decrease in the measurement accuracy of the SMR-ERD signal caused by the difference in the thickness of the electrode portion can be suppressed.

[0100] [Second effect]

[0101] Next, in addition to the above Figure 1 to Figure 6 In addition, refer to Fig.12 and Fig.13 A second operation and effect of the headphones 14 constituting a part of the state analysis system 10 will be described.

[0102] <Function>

[0103] Before measuring the biological signal, the subject 12 wears the headphones 14 on his / her head H. Specifically, the subject 12 holds the headphones 14 with both hands, fixes one earmuff 42R to the right ear, and fixes the other earmuff 42L to the left ear.

[0104] Fig.12 This is a diagram of the subject 12 wearing the headset 14 as viewed from the right side. The contact portion is pressed by the elastic force of the protruding member 64R provided on the earmuff 42R, and the electrode portion EL3 is fixed to the front lower portion of the right ear. Thus, for example, an electrical signal related to muscle activity generated around the head H including the masseter muscle and the sternocleidomastoid muscle can be measured.

[0105] Fig.13 This is a diagram of the subject 12 wearing the headset 14 as viewed from the left side. The contact portion is pressed by the elastic force of the protruding member 64L provided on the earmuff 42L, and the electrode portion EL4 is fixed to the lower part behind the left ear. The ground potential (or earth potential) can be obtained from the electrode portion EL4 by taking advantage of the fact that the part behind the ear is not easily affected by the biological potential from brain activity.

[0106] The state analysis system 10 can perform various measurements or analyses while the subject 12 is wearing the headphones 14 .

[0107] [1] For example, the electrode EL3 may be used as a reference electrode and the electrode EL4 may be used as a ground electrode. In this case, the headphone 14 may output a differential amplified signal of the electrical signals from the other electrode portions EL0 to EL2 and the electrical signal from the electrode portion EL3. Thus, when muscle activity occurs, the potential change can be superimposed on the other measurement channels (electrode portions EL0 to EL2) in the form of phase inversion through the above-mentioned differential amplification.

[0108] In particular, if the range of potential changes caused by brain activity and muscle activity is considered to be very different, muscle activity can be more explicitly introduced as a "signal". On the contrary, when muscle activity is captured as "noise" of brain activity, the accuracy of brain activity analysis can be improved by excluding the interval where muscle activity occurs from the analysis object.

[0109] [2] Conversely, the electrode portion EL3 may be used as a ground electrode and the electrode portion EL4 may be used as a reference electrode. In this case, the headphone 14 may output a differential amplified signal of the electrical signals from the other electrode portions EL0 to EL2 and the electrical signal from the electrode portion EL4. In this way, the potential change caused by the muscle activity generated around the head H can be superimposed on other measurement channels.

[0110] [3] In addition, the state analysis device 16 may perform analysis processing related to muscle activity generated around the head H separately from the analysis of brain activity. Examples of analysis processing include (A) quantification of the tension state of the subject 12, (B) determination of whether the subject 12 is in a resting state, and (C) determination of the target interval for electroencephalogram analysis.

[0111] <Effect>

[0112] As described above, the biological signal measuring device (here, the headset 14) of the present embodiment includes: a headband 40 having an inverted U-shape and capable of being worn on the head H of the subject 12; a first earmuff (here, the earmuff 42R) provided at one end of the headband 40 and covering one ear of the head H when the headband 40 is worn; a second earmuff (here, the earmuff 42L) provided at the other end of the headband 40 and covering the other ear of the head H when the headband 40 is worn; a first protruding member (here, the protruding member 64R) extending from the position P3 of the outer edge of the earmuff 42R; and a first cover-side electrode portion (here, the electrode portion EL3) provided at the front end side of the protruding member 64R and used to measure the biological signal of the subject 12.

[0113] When observing from the side of the earmuff 42R, a straight line parallel to the direction in which the headband 40 extends downward and passes through the center of gravity position O1 of the plane area formed by the earmuff 42R is defined as a first reference line (here, the vertical reference line LV), and a straight line orthogonal to the vertical reference line HV and passing through the center of gravity position O2 is defined as a second reference line (here, the horizontal reference line LH), position P3 is located on the front side of the vertical reference line LV and on the lower side of the horizontal reference line LH.

[0114] In this way, since the position P3 located at the base end side of the protruding member 64R is located at the front side of the vertical reference line LV and the bottom side of the horizontal reference line LH, the electrode portion EL3 located at the front end side of the protruding member 64R is fixed to the front lower part of one ear of the head H by covering both ears with the pair of earmuffs 42R and 42L. Thus, a biological signal related to muscle activity generated around the head H including the masseter muscle and the sternocleidomastoid muscle can be measured, and various measurements and analyses can be performed in consideration of muscle activity.

[0115] In addition, at least the front end of the protruding member 64R may be extended obliquely forward and inward relative to the position P3. Thus, the electrode portion EL3 located on the front end side of the protruding member 64R can easily contact the head H (more specifically, the lower part in front of the ear).

[0116] In addition, the headset 14 may further include a band-side electrode portion (here, the electrode portions EL0 to EL2), which is mounted on the headband 40 and is used to measure the biological signal of the head H, and differentially amplify and output the first biological signal obtained from the electrode portions EL0 to EL2 and the second biological signal obtained from the electrode portion EL3. Thus, when muscle activity occurs, the potential change can be superimposed on the other electrode portions EL0 to EL2 in the form of phase inversion through differential amplification.

[0117] Furthermore, when the headphone 14 further includes a second protruding member (here, the protruding member 64L) extending from a position P4 of the outer edge of the earmuff 42L, and a second cover-side electrode portion (here, the electrode portion EL4) provided on the front end side of the protruding member 64L and used to measure the biological signal of the subject 12, the position P4 may be located at a position behind the vertical reference line LV and below the horizontal reference line LH. By covering both ears with a pair of earmuffs 42R and 42L, the electrode portion EL4 located at the front end side of the protruding member 64L is fixed to the lower part behind the other ear of the head H. By utilizing the fact that the part behind the ear is not easily affected by the biological potential from brain activity, the ground potential (or earth potential) can be obtained from the electrode portion EL4.

[0118] [Variation 3]

[0119] It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be freely modified without departing from the gist of the present invention. Alternatively, each configuration can be arbitrarily combined within the scope that does not cause technical contradictions.

[0120] In the above-mentioned embodiment, the ideal arrangement of the electrode parts EL0 to EL2 is derived based on the activation range of the SMR-ERD signal obtained by analysis using the human body size database described in non-patent documents 1 to 3. If other signals are targeted, it is assumed that the activation range is different depending on the characteristics of the signal. In this case, based on the activation range obtained by analysis, the same analysis method can be used to set the measurement range applicable to most humans.

[0121] In the above embodiment, although the protruding member 64R is fixed to the front side of the earmuff 42R and the protruding member 64L is fixed to the rear side of the earmuff 42R, the present invention is not limited to this embodiment. For example, the protruding member 64R may be fixed to the rear side of the earmuff 42R and the protruding member 64L may be fixed to the front side of the earmuff 42R. In addition, at least one of the protruding members 64R and 64L may be omitted.

[0122] In the above embodiment, the protruding members 64R and 64L are fixed to the ear cups 42R and 42L, but the protruding members 64R and 64L may be movable in the circumferential direction relative to the ear cups 42R and 42L. This makes it easy to adjust the contact position (i.e., the measurement position) of the electrodes EL3 and EL4.

[0123] In the above-mentioned embodiment, the case where the state analysis device 16 performs the analysis of the biological signal and the control of the motion assisting device 18 is used as an example for explanation, but the system configuration is not limited to this. For example, it can be configured such that the analysis unit and the control unit are separately provided, and the necessary data can be exchanged with each other through wired communication or wireless communication. In this case, the analysis process can be performed by a cloud-based or locally deployed server device. In particular, when the server device is a cloud-based type, the server device can also be a computer group that constructs a distributed system.

[0124] Description of Reference Numerals

[0125] 10: state analysis system; 12: person being measured; 14: headphones (biological signal measuring device); 16: state analysis device; 40: headband; 42R, 42L: earmuffs; EL0: electrode part (central electrode part); EL1: electrode part (first electrode part); EL2: electrode part (second electrode part); EL3: electrode part (first electrode part on the cover side); EL4: electrode part (second electrode part on the cover side); H, H1, H2: head.

Claims

1. A biological signal measuring device, comprising: A headband having an inverted U-shape and being wearable on the head of the person being measured; A first earmuff, provided at one end of the headband, and covering one ear of the head when the headband is worn; A second earmuff, provided at the other end of the headband, covering the other ear of the head when the headband is worn; a first protruding member extending from a first position on an outer edge of the first earmuff; as well as The first cover-side electrode portion is provided at the front end side of the first protruding member and is used to measure the biological signal of the subject. When viewed from the side of the first earmuff, When a straight line parallel to the direction in which the headband extends downward and passes through the center of gravity of the plane area formed by the first earmuff is defined as a first reference line, and a straight line orthogonal to the first reference line and passing through the center of gravity is defined as a second reference line, The first position is located in front of the first reference line and below the second reference line.

2. The biological signal measuring device according to claim 1, wherein: At least a front end portion of the first protruding member is provided to extend obliquely forward and inward relative to the first position.

3. The biological signal measuring device according to claim 1, wherein: It also includes a band-side electrode portion, which is mounted on the headband and is used to measure a biological signal of the head. The biological signal measuring device differentially amplifies a first biological signal acquired from the belt-side electrode portion and a second biological signal acquired from the first mask-side electrode portion, and outputs the amplified signals.

4. The biological signal measuring device according to claim 1, wherein: Also available: a second protruding member extending from a second position on an outer edge of the second earmuff; and The second cover-side electrode portion is provided at the front end side of the second protruding member and is used to measure the biological signal of the subject. When observing from the side of the second earmuff, a straight line parallel to the direction in which the headband extends downward and passes through the center of gravity of the plane area formed by the second earmuff is defined as a third reference line, and a straight line orthogonal to the third reference line and passing through the center of gravity is defined as a fourth reference line. The second position is located behind the third reference line and below the fourth reference line.

5. A state analysis system comprising: The biological signal measuring device according to any one of claims 1 to 4; and The state analysis device performs analysis processing on the biological signal measured by the biological signal measuring device to analyze the movement intention, cognitive state or fatigue state of the subject.

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