WO2006057313A1

WO2006057313A1 - Biosignal detector

Info

Publication number: WO2006057313A1
Application number: PCT/JP2005/021608
Authority: WO
Inventors: Etsunori Fujita; Shinichiro Maeda
Original assignee: Delta Tooling Co., Ltd.
Priority date: 2004-11-25
Filing date: 2005-11-24
Publication date: 2006-06-01
Also published as: JPWO2006057313A1

Abstract

The noise signal included in electric signal data itself representing pressure variation detected by a piezoelectric film sensor is reduced to enhance judgment accuracy of the condition of an organism. A pair of piezoelectric film sensors (10, 11) are so spaced at a position near the body surface and at a position away from the body surface and installed at least at one of the seat cushion (110) and the seat back (120). The difference between the output values of the pair of piezoelectric film sensor (10, 11) is outputted. The piezoelectric film sensors (10, 11) detect external vibration noise transmitted from the road surface. However, the vibration of the body surface duo to the pulse, beat and respiration is largely detected by the first piezoelectric film sensor (10) provided near the body surface. Therefore, by measuring the difference between both, the pressure variation due to the biosignal such as the pulse, beat, and respiration can be more accurately determined.

Description

Specification

Biological signal detection device

Technical field

[0001] The present invention is supported by various seats such as a vehicle seat used for transportation equipment such as automobiles, trains, and airplanes, office seats, and seats that are seated by a person at the time of inspection or diagnosis in a hospital. The present invention relates to a biological signal detection device for detecting a biological signal of a human being, for example, a pulse wave, a pulsation, a respiration, etc. of the buttocks and thighs. The present invention relates to a biological signal detection apparatus suitable for performing.

Background art

[0002] To detect the state of a human living body, for example, whether it is an active state (awake state), a sleep state, or the like, conventionally, it is performed by measuring an electroencephalogram and analyzing the electroencephalogram pattern. ing. However, in order to measure an electroencephalogram, it is necessary to attach an electroencephalogram electrode or an electrooculogram electrode to the subject's head, for example, in an environment that restricts the normal operation of the person. It is difficult to evaluate the biological state of various transportation equipment such as automobiles and trains without burdening the driver.

[0003] On the other hand, monitoring the biological state (mental state) of a driver during driving has recently attracted attention as an accident prevention measure. For example, Patent Document 1 and Patent Document 2 include a heartbeat or a pulse. In addition, a technique for monitoring the biological state by analyzing the chaos has been proposed. According to the techniques disclosed in Patent Documents 1 and 2, it is not necessary to attach a powerful device for brain wave measurement to the head, and the biological state of the driver can be easily evaluated. The devices disclosed in Patent Documents 1 and 2 are both thin-film piezoelectric elements (piezoelectric film sensors) in which vibrations of the body surface accompanying the pulsation of the heart are attached to the seating surface of the cushion material constituting the seat cushion. Sensing with

Patent Document 1: Japanese Patent Laid-Open No. 9-308614

Patent Document 2: Japanese Patent Laid-Open No. 10-146321

Disclosure of the invention

Problems to be solved by the invention [0004] In the techniques disclosed in Patent Documents 1 and 2, external vibrations input from the road surface during traveling become noise, and the pressure fluctuation signal obtained by the piezoelectric film sensor force contains a lot of such noise. Therefore, it is extremely difficult to obtain only the pressure fluctuation signal resulting from the vibration of the body surface accompanying the biological signal such as a pulse wave. For this reason, the applicant of the present invention has been able to detect a biological signal using a pressure fluctuation detection sensor typified by a piezoelectric film sensor, while using a noise signal in the obtained pressure fluctuation data. We have developed computing means that reduce as much as possible, and have proposed a technology that makes it possible to more accurately and easily determine various living conditions (such as sleep onset and fatigue) of a person who sits down and sits down (for example, a patent application) 2003-180294, Japanese Patent Application 2003-180296, Japanese Patent Application 2003-180297, Japanese Patent Application 2003-36 3902, Japanese Patent Application 2004-89263).

[0005] However, there is a limit to reducing the influence of noise signals only by improving the calculation means.

[0006] Therefore, the present invention reduces the noise signal included in the electrical signal data of the pressure fluctuation detected by the pressure fluctuation detection sensor force such as a piezoelectric film sensor, and further increases the determination accuracy of the biological state, the degree of fatigue, and the like. It is an object of the present invention to provide a biosignal detection device that can perform the above.

Means for solving the problem

[0007] In order to solve the above-described problem, the biological signal detection device of the present invention has a gap between a position close to the body surface and a position spaced apart from at least one of the shift on the seat cushion side and the seat back side. A pair of pressure fluctuation detection sensors disposed,

Differential output means for outputting the difference between the output values of the pair of pressure fluctuation detection sensors.

One of the pair of pressure fluctuation detection sensors is supported by an upper cushion material disposed close to the body surface, and the other is disposed at a lower layer than the upper cushion material. It can be provided in support of the material.

Further, the pair of pressure fluctuation detection sensors can be respectively arranged on the front side and the back side of an arbitrary cushion material.

In addition, it is preferable to use a piezoelectric film sensor as the pressure fluctuation detection sensor. Yes.

Further, the upper-layer cushion material and the lower-layer cushion material are preferably formed from a three-dimensional knitted fabric.

Moreover, it is preferable that the said arbitrary cushioning material is also formed of the solid knitting force. The invention's effect

[0008] According to the present invention, a pair of pressure fluctuation detections disposed at a distance from each other between a position close to the body surface and a position separated from the body surface on at least one of the displacement on the seat cushion side and the seat back side. A sensor is provided, and the difference between the output values of the pair of pressure fluctuation detection sensors is output. For this reason, external vibration noise transmitted from the road surface is detected by each pressure fluctuation detection sensor, but vibrations of the body surface due to pulse waves, pulsations, breathing, etc. are mainly close to the body surface. It is detected by the arranged pressure fluctuation detection sensor. Therefore, by taking the difference between the two, it is possible to more accurately detect pressure fluctuations associated with biological signals such as pulse wave, pulsation, and respiration. The biological signal detection device of the present invention can be used in an environment where external vibration is hardly applied, such as office seats and seats where people are seated during examinations and diagnoses in hospitals. However, since noise due to external vibrations can be effectively reduced, it is particularly suitable as a device that is provided on a vehicle seat such as an automobile and used to determine the occupant's biological state (such as sleep onset and fatigue). The

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic configuration of a seat attached with a biological signal detection device that is helpful in one embodiment of the present invention.

[FIG. 2] FIG. 2 is a diagram showing test results for verifying the appearance of a sleep onset predictive signal in a car running test, (a) is the analysis result of the fingertip volume pulse wave, and (b) is the first result. ( _C ) is the analysis result using the difference between the first and second piezoelectric film sensors.

[FIG. 3] FIG. 3 corresponds to FIG. 2 (a), and is the time-series data of the original waveform of the fingertip volume pulse wave obtained by measuring the fingertip volume pulse wave measuring force before detecting the sleep onset signal.

[FIG. 4] FIG. 4 corresponds to FIG. 2 (b), and is the original waveform time-series data of the first piezoelectric film sensor before the detection of the sleep onset signal. [FIG. 5] FIG. 5 corresponds to FIG. 2 (c), and shows the original waveform time-series data of the difference between the first and second piezoelectric film sensors 10, 11 (difference sensor) before detection of the slumber predictive signal. is there.

[FIG. 6] FIG. 6 corresponds to FIG. 2 (a), and is the original waveform time series data of the finger plethysmogram obtained by detecting the finger plethysmogram at the time of detection of a sleep symptom signal.

[FIG. 7] FIG. 7 corresponds to FIG. 2 (b), and is the original waveform time-series data of the first piezoelectric film sensor at the time of detection of a sleep signal.

[FIG. 8] FIG. 8 corresponds to FIG. 2 (c), and shows the original waveform time-series data of the difference between the first and second piezoelectric film sensors 10, 11 (difference sensor) at the time of detection of a sleep signal. is there.

[FIG. 9] FIG. 9 corresponds to FIG. 2 (a) and shows the original waveform time series data of the finger plethysmogram obtained by detecting the finger plethysmogram after detecting a sleep signal.

[FIG. 10] FIG. 10 corresponds to FIG. 2 (b), and is the original waveform time-series data of the first piezoelectric film sensor after the detection of the sleep onset signal.

[FIG. 11] FIG. 11 corresponds to FIG. 2 (c), and the original waveform time-series data of the difference between the first and second piezoelectric film sensors 10 and 11 (difference sensor) after detection of the onset of sleep signal It is.

Explanation of symbols

[0010] 1 Biological signal detection device

10 First piezoelectric film sensor

20 Second piezoelectric film sensor

100 sheets

110 Seat cushion

111 Upper cushion material

112 Lower side cushioning material

120 seat back

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail based on the embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a state in which a biological signal detection device 1 according to an embodiment of the present invention is attached to a vehicle seat 100 such as an automobile. The biological signal detection device 1 includes a pair of (first and second) piezoelectric film sensors 10 and 11 as pressure fluctuation detection sensors. The signal data detected by the piezoelectric film sensors 10 and 11 is transmitted to the arithmetic unit 20, and predetermined data processing is performed. Force that can be used with any pressure fluctuation detection sensor other than the piezoelectric film sensors 10 and 11 The vibration absorption characteristics of the seat cushion 110, etc. that does not feel uncomfortable even if it is attached to the seat cushion 110, etc. For this reason, it is preferable to use a piezoelectric film sensor that is formed into a thin film.

[0012] As the first and second piezoelectric film sensors 10, 11, for example, Tokyo Sensor Co., Ltd., product name: PIEZO FILM LDT series, model number: LDT4-028KZL can be used. As described above, the first and second piezoelectric film sensors 10 and 11 may be provided on either the seat cushion 110 side or the seat back 120 side (including the headrest), or may be provided on both. However, since the seat cushion 110 is always in contact with the human body when seated, it is provided at least on the seat cushion 110 side, and biological displacement that propagates through the buttocks muscle, such as buttocks pulse wave, breathing, pelvic movement or body movement. A configuration for detecting a signal (fluctuation) is preferable. In addition, when mounted on the seat cushion 110 side, for example, it may be arranged only near the sciatic tuberosity, but the posture (sacral posture) where the buttock is shifted forward by long-term seating is taken. May cause the sensor to fall outside the detection range of the sensor, so in addition to the sensor placed near the sciatic nodule, one or more sensors may be placed at a position shifted before or after the sensor. Is possible. This is the same when the seatback 120 is mounted, and can be placed at multiple locations.

[0013] The first and second piezoelectric film sensors 10, 11 are provided at a distance from each other at a position close to the body surface and a position spaced apart from the body surface. For this reason, the pressure fluctuation due to the vibration of the body surface accompanying the biological signal is mainly detected by the first piezoelectric film sensor 10. In FIG. 1, the first piezoelectric film sensor 10 is fixed near the surface of the cushion material 111 on the upper layer side of the seat cushion 110. Although it can be exposed and attached to the surface of the cushion material 111 on the upper layer side, it is preferable that the cushion material 111 is incorporated in a position close to the surface in order to protect the detection surface. On the other hand, the second piezoelectric film sensor 11 is disposed on the back side of the lower cushion material 112 positioned below the upper cushion material 111 and is fixed to the seat surface of the seat cushion 110. The second piezoelectric film sensor 11 is an upper cushion material 1 The force that can be fixed to the back surface of 11 In the second piezoelectric film sensor 11, as described above, the lower-layer cushion material 112 is used so that the biosignal detection data is not the same as that of the first piezoelectric film sensor 10. It is preferable to provide them. Therefore, “spaced between a position close to the body surface and a position spaced apart from each other” means that at least part of the cushion material 111, 112, which performs the cushion function, includes the first and second piezoelectric films. This means that the sensor is positioned between the sensors so that there is a gap between them.

[0014] In addition, the upper-layer cushion material 111 and the lower-layer cushion material 112 are both arranged on the seating surface of the seat cushion 110 in FIG. That is, the upper-layer cushion material 111 and the lower-layer cushion material 112 are independent cushions that can be disposed on the seat surface of the seat cushion 110 as necessary. In this case, the upper-layer cushion material 111 and the lower-layer cushion material 112 may be integrated, or may be configured separately. Further, for example, the lower cushion material 112 may be incorporated into the seat cushion 110! /, And both the upper cushion material 111 and the lower cushion material 112 are incorporated into the seat cushion 110. It is good also as a cushioning material. This is the same when the piezoelectric film sensors 10 and 11 are arranged on the seat back 120 side. The term “lower cushion material” as defined in the claims means to include all cushion materials located in the lower layer than the upper cushion material 111 close to the body surface. “Supported by a sillon material” may be fixed to any cushion material. In FIG. 1, the force with which the second piezoelectric film sensor 11 is fixed to the surface (seat surface) of the cushion material of the seat cushion 110 itself and the lower cushion material 112 is laminated thereon, for example, It may be fixed to the back surface of the cushion material 112.

[0015] Here, as the cushion material 111 on the upper layer side and the cushion material 112 on the lower layer side, it is preferable to use a solid knitted fabric. For example, as disclosed in JP-A-2002-331603, a three-dimensional knitted fabric reciprocates between a pair of ground knitted fabrics spaced apart from each other and the pair of ground knitted fabrics. The knitted fabric has a three-dimensional three-dimensional structure having a large number of connecting yarns to be joined. Such a three-dimensional knitted fabric has moderate elasticity, and exhibits a soft panel characteristic at a single point concentrated load. Obtained when the muscle is pressurized to 30mm or 98mm in diameter Panel characteristics close to load-deflection characteristics (panel characteristics). For this reason, it is suitable for transmitting slight pressure fluctuations of muscles caused by human breathing, heartbeat (pulse wave), body movement, etc.

Each output value obtained from the first and second piezoelectric film sensors 10 and 11 is sent to the calculation unit 20, and the difference between both is taken by the difference output means incorporated in the calculation unit 20. Predetermined data processing is performed using the signal data. Specifically, the differential output means obtains a difference between the output value of the first piezoelectric film sensor 10 and the output value of the second piezoelectric film sensor 11 at every arbitrary sampling period.

[0017] Examples of data processing performed by the calculation unit 20 include data processing for determining a biological state such as a sleep onset sign disclosed in Japanese Patent Application No. 2003-180294 and Japanese Patent Application No. 2004-89263 proposed by the present applicant. Means or a data processing means for quantitatively determining the degree of fatigue disclosed in Japanese Patent Application No. 2003-363902 can be applied.

[0018] Specifically, the former detects the peak value of each period of the original waveform of the signal data obtained by the above-described differential output means force, and from each peak value, the peak value on the upper limit side for each predetermined time range Is calculated as the power value, and the power value is calculated by sliding the slope of the power value with respect to the time axis in the specified time range at the specified slide lap ratio a specified number of times. In addition to obtaining the value slope, the signal data is chaotically analyzed to calculate the maximum Lyapunov exponent, the peak value of each period of the time-series change waveform of the maximum Lyapunov exponent is detected, and the predetermined peak value of the maximum Lyapunov exponent is determined. When the maximum Lyapunov exponent slope is calculated by calculating the slope with respect to the time axis in the time range by a predetermined number of slides at a predetermined slide lap ratio, and when the power value slope suddenly decreases The point is preferably a means for determining, as a sleep predictive signal, a time point when the power value gradient and the maximum Lyapunov exponent gradient stably show a phase difference of about 180 degrees in the time-series signal. The latter is a means for obtaining the integral value by processing the absolute value of the time-series signal when the value slope is obtained as described above, and obtaining the obtained integral value as the degree of fatigue.

Since the signal data obtained from the biological signal detection device of the present embodiment is the difference between the output values of the first and second piezoelectric film sensors 10 and 11, external vibration noise is reduced, and the biological signal is The signal data is more prominently captured, and when used in the data processing means described above, it is possible to more accurately determine the timing of sleep onset and the degree of fatigue. [0020] (Test example)

A seat 100 similar to that shown in Fig. 1 was installed in the passenger seat of the car, traveling on the highway, and the time series fluctuations of the power value gradient and the maximum Lyapunov exponent gradient were obtained, and the appearance of the sleep predictive signal was verified. . The seat 100 is a seat cushion 110 and a seat back 120. A net seat made by Delta Touring Co., Ltd., which is constructed by stretching a three-dimensional knitted fabric on a frame with a low tension of 5% or less, and seats of the seat cushion 110 are used. A second piezoelectric film sensor 11 is fixed to the surface, and a lower layer cushioning material 112 is laminated on the second piezoelectric film sensor 11, and an upper layer cushion that incorporates the first piezoelectric film sensor 10 at a position close to the surface. Material 11 1 was laminated.

[0021] The upper-layer cushion material 111 is a three-dimensional knitted fabric (product number: 49013D) manufactured by Sumie Textile Co., Ltd., knitted using a double raschel knitting machine, and has the following characteristics.

Material:

Front knitted fabric '·' Polyethylene terephthalate fiber false twist yarn

Back side ground knitted fabric '·' Polyethylene terephthalate fiber false twisted yarn

Connecting yarn Polytrimethylene terephthalate monofilament

Weight: 981gZm ²

Thickness: 10. 66mm

Tensile strength: Vertical '· · 1531NZ50mm, Horizontal' · · 1367NZ50mm

Elongation: Vertical 68%, Horizontal 107%

Constant load elongation (8cm width, 10kg, 10 minutes):

Vertical ... 15. 5%, Horizontal · '· 38. 5%

Residual strain rate (8cm width, 10kg, 10 minutes):

Vertical · · · · (). 9%, horizontal… 1. 1%

Seam strength: Vertical · '· 724Ν, Horizontal ·' · 869Ν

Seam fatigue: Vertical · · · (). 9mm, side · · · ·! _. lmm

[0022] The cushion material 112 on the lower layer side is a three-dimensional knitted fabric (product name: “Space Fabric”) manufactured by Seiren Co., Ltd., and has the following configuration having the following characteristics.

Thickness: 2.5mm Knitted fabric density: 25 whale Z inch, 48 course Z inch

Tensile strength: longitudinal · · · 611¾Ζ50πιπι, transverse ... 118kgZ50mm

Elongation: Vertical · '· 60%, Horizontal ·' · 63%

Constant load elongation: Vertical,.-25%, Horizontal, · · 15%

Residual distortion rate: vertical 1%, horizontal 1%

Tear strength: Vertical ... 37kg, Horizontal ... 37kg

The used piezoelectric film sensors 10 and 11 were all Tokyo Sensor Co., Ltd., product name: PIEZ O FILM LDT series, model number: LDT4-028KZL.

[0024] The results are shown in Fig. 2. The test subjects are healthy Japanese men in their 30s, and the data obtained when the Kotani SA force on the Sanyo Expressway also traveled to Miki SA. For comparison, finger plethysmograms that were not affected by external vibration were also collected and compared with the results of finger plethysmogram analysis. Fig. 2 (a) shows the analysis result of the fingertip volume pulse wave, (b) shows the analysis result using only the data of the first piezoelectric film sensor 10, and (c) shows the first and second piezoelectric films. It is the analysis result using the difference of film sensors 10 and 11.

[0025] As shown in Fig. 2 (a), according to the analysis results of the finger plethysmogram, the power value slope and the maximum Lyapunov exponent slope are approximately 180 degrees between 800 seconds and 1300 seconds. After that, since the fluctuation range of the power value slope becomes smaller, the range from 800 seconds to 1300 seconds can be determined as a sleep onset predictive signal. In addition, it was reported that the subject began to try at this point in the observation by the rear seat observer. Therefore, it is compared with the case where the determination result according to FIG. 2 (a) is assumed to be a correct value and the data obtained only in the first piezoelectric film sensor 10 of FIG. 2 (b) is processed. In Fig. 2 (b), the power value slope suddenly drops after 700 seconds, and further drops after 1200 seconds, after which the fluctuation range of the power value slope becomes smaller. Therefore, if the point at which the power value slope suddenly falls is defined as a predictive of sleep onset, there will be no major contradiction with the judgment result in Fig. 2 (a), but the phase difference of about 180 degrees from the maximum Lyapunov exponent slope. Does not appear clearly. Therefore, in order to make a more accurate determination using the phase difference of approximately 180 degrees between the two as an index, it is not sufficient to use only the data of the first piezoelectric film sensor 10.

On the other hand, data obtained from the first and second piezoelectric film sensors 10 and 11 in FIG. The difference between the power value slope and the maximum Lyapunov exponent slope has a phase difference of about 180 degrees almost simultaneously with Fig. 2 (a). In addition, when compared with Fig. 2 (b), the numerical range of the power value slope (vertical axis), which is set appropriately to understand the trend of time series change, is greater than that of Fig. 2 (b). 2 (c) is one digit less. In other words, when only the power value gradient is observed, the force that can detect the behavior of the biological signal as described above can be reduced as shown in Fig. 2 (b). The fact that a similar time-series change in the power value slope can be seen means that the baseline fluctuation of the high-frequency vibration input from the road surface is not included in Fig. 2 (c). Therefore, by using the difference between the first and second piezoelectric film sensors 10 and 11, both the slope of the power value and the slope of the maximum Lyapunov exponent are not affected by the noise caused by external vibration during running, and a sign of sleep onset. It was proved that signals indicating changes in biological conditions such as can be captured more accurately.

[0027] In addition, the original waveform time series data used when obtaining each time series change of FIG. 2 was compared. Fig. 3, Fig. 6 and Fig. 9 correspond to Fig. 2 (a), and are the original waveform time series data of the fingertip volume pulse wave obtained from the fingertip volume pulse wave measuring device. Fig. 7 and Fig. 10 correspond to Fig. 2 (b) and are the original waveform time series data of the first piezoelectric film sensor 10 (detection sensor). Fig. 5, Fig. 8 and Fig. 11 show Fig. 2 This corresponds to (c) and is the original waveform time-series data of the difference between the first and second piezoelectric film sensors 10, 11 (difference sensor). Figures 6 to 8 show the data from 900 seconds to 1100 seconds when the sleep onset signal was captured. Figures 3 to 5 show the data before the sleep onset signal was captured, and Fig. 9 FIG. 11 shows data after the sleep signal is captured.

[0028] First, in the range where the sleep onset symptom signal is generated, comparing FIG. 7 and FIG. 8, the data of FIG. The overall amplitude has decreased, and the high-frequency vibrations input from the road surface have been greatly reduced. When compared with the original waveform time series data, the time series waveform of the fingertip plethysmogram shown in Fig. 6 is closer. The In particular, the waveform in the vicinity of 920 to 1000 seconds in FIG. 8 shows a trend of change similar to the waveform in the vicinity of 900 to 980 seconds of the fingertip volume pulse wave in FIG. It was found that biosignals can be detected with higher accuracy by using the difference between film sensors 10 and 11. Data before detection of sleep onset signal in Fig. 3 to Fig. 5 and Fig. 9 to Fig. 11 The same can be said for the data after the detection of the onset of sleep signal. FIG. 5 is compared to FIG. 4 and FIG. 11 is compared to FIG. 9 fingertips It approaches the data of plethysmogram, and it is very powerful.

Claims

The scope of the claims

[1] A pair of pressure fluctuation detection sensors disposed at a distance between a position close to the body surface and a position separated from the body surface on at least one of the displacement on the seat cushion side and the seat back side;

And a difference output means for outputting a difference between the output values of the pair of pressure fluctuation detection sensors.

[2] One of the pair of pressure fluctuation detection sensors is supported by an upper cushion material disposed close to the body surface, and the other is a lower layer disposed below the upper cushion material. 2. The biological signal detection device according to claim 1, wherein the biological signal detection device is supported by a side cushion material.

[3] The biological signal detection device according to claim 1, wherein the pair of pressure fluctuation detection sensors are respectively arranged on a front surface side and a back surface side of an arbitrary cushion material.

4. The pressure fluctuation detection sensor is a piezoelectric film sensor.

The biological signal detection device according to claim 1, wherein the deviation is 1.

5. The biosignal detection device according to claim 2, wherein the upper layer side cushion material and the lower layer side cushion material are formed from a three-dimensional knitted fabric.

6. The biological signal detection device according to claim 3, wherein the biological signal detection device is formed of the arbitrary cushion material.