JP2011156196A - Biological information detector - Google Patents

Abstract

A biological information detection apparatus capable of acquiring biological information with a simple structure is provided.
A living body information detecting apparatus has a long piezoelectric film that detects a deformation direction of an extension or contraction or a bending deformation of a seat cushion having a predetermined seating direction. The sensor unit 12 is disposed so that the seating direction and the long direction coincide with each other over the position, and includes a sensor unit 12 that detects a change in load, and a calculation unit 70 that calculates biological information based on the change in load.
[Selection] Figure 3

Description

  The present invention relates to a biological information detection apparatus that detects biological information of a seated person sitting on a seat.

  2. Description of the Related Art Conventionally, a biological information detection apparatus that detects biological information including respiration and heartbeat of a living body such as a person or an animal has been used. The biological information detected in this way is used to specify the state of the biological body from which the biological information is detected. Specifically, such biological information is used to determine whether the mental state of the biological body is a relaxed state or to determine whether it is a sleeping state. As techniques for detecting respiration and heartbeat of such a living body, there are those described in Patent Documents 1 and 2, which are cited below.

  In the load detection device described in Patent Document 1, a plurality of load sensors are distributed and arranged on a support that supports a human or animal body. Among these plurality of load sensors, the output of each load sensor, or the output of each of the load sensors selected based on the output of each load sensor and the position where each load sensor is arranged Is used to detect the load and vibration applied to the support.

  The biological information detection device described in Patent Document 2 includes a first vibration detection unit that detects biological information, and a second vibration detector that is disposed through the vibration damping unit so as to face the first vibration detection unit. And a vibration detecting means. The biological information detection apparatus calculates the power spectrum of the first vibration detection means and the power spectrum of the second vibration detection means, and calculates the difference for each frequency. A frequency at which the calculated difference is maximum in a basic heart rate frequency region set in advance is obtained as heart rate information.

Japanese Patent Laid-Open No. 2007-3227 JP 2005-74059 A

  When a large number of load sensors are arranged on the support as in the technique described in Patent Document 1, the output signal lines from the respective load sensors increase, and accordingly, the wiring becomes complicated. For this reason, since the usage amount of wiring increases, member cost increases. In addition, since the total weight of the wiring becomes heavy, fuel consumption increases. In addition, the logic to select from a plurality of load sensors becomes complicated, and a high-performance arithmetic processing device may be required to perform arithmetic processing at high speed, which causes an increase in cost. End up.

  Also in the technique described in Patent Document 2, if the configuration is such that the difference between the power spectrum of the first vibration detection unit and the power spectrum of the second vibration detection unit is calculated for each frequency, the calculation load increases. When performing arithmetic processing at high speed, a high-performance arithmetic processing device may be required. For this reason, it becomes a factor of a cost increase. In addition, since the first vibration detection means, the vibration attenuation means, and the second vibration detection means have a three-layer structure, the wiring becomes complicated and the thickness increases.

  In view of the above problems, an object of the present invention is to provide a biological information detection apparatus capable of acquiring biological information with a simple structure.

  In order to achieve the above object, the biological information detecting apparatus according to the present invention has a characteristic configuration in which a single piezoelectric film that detects a deformation in an expansion / contraction direction or bending with respect to a seat portion in which a seating direction is determined in advance. Is disposed so that the seating direction and the longitudinal direction coincide with each other over a position facing the buttocks of the seated person, and a sensor unit that detects a change in the load, and calculates biological information based on the change in the load And an arithmetic unit.

  With such a characteristic configuration, a bending force easily acts on the piezoelectric film with respect to movement in the seating direction, so that a signal level (for example, output voltage) for the bending force in the seating direction can be increased. Accordingly, it is easy to detect a change in load in the seating direction, so that biological information can be easily acquired. Further, since the sensor unit is composed of one piezoelectric film, the wiring and structure can be simplified, and the calculation process of the calculation unit can be simplified.

  In addition, it is preferable that a pair of the sensor units is disposed so as to face the greater gluteus of the seated person in a plan view of the seat part.

  With such a configuration, the sensor unit and the seated person can be reliably brought into contact with each other via the greater gluteus. Therefore, it is possible to appropriately acquire the biological information of the seated person.

  Here, particularly in the sitting state, the body of the seated person moves in the seating direction due to breathing (the load changes in the seating direction) in many cases. Therefore, as described above, by arranging the sensor unit so that the seating direction and the long direction coincide with each other, the calculation unit allows the breathing information of the seated person according to the change in the load based on the swing in the seating direction. Can be calculated.

  Further, it is preferable that the position facing the collar portion is a position on the rear side in the seating direction of the seat portion.

  With such a configuration, it is possible to appropriately acquire the biological information of the seated person via the buttocks by sitting in the normal seating configuration.

  Moreover, it is preferable that the length of the piezoelectric film in the longitudinal direction is not less than 1/4 and less than 1/2 of the length of the seat portion in the seating direction.

  If it is a piezoelectric film of such a size, the change of a load can fully be detected. Further, when two sensor units are used as a pair, they can be arranged without overlapping each other.

  Further, it is preferable that the piezoelectric film is formed by stretching PVDF, and the sensor unit is formed so that the extending direction and the longitudinal direction coincide with each other.

  In this way, by forming the PVDF stretched direction and the long direction of the sensor unit so as to coincide with each other, it is possible to increase the output voltage that is output when expansion or bending in the long direction occurs. Therefore, since it becomes easy to detect even a minute load change, it is possible to appropriately calculate biological information.

It is a figure which shows the sensor part with which a biological information detection apparatus is provided. It is a figure which shows the outline of the sheet | seat with which a biometric information detection apparatus is provided. It is a figure shown about the example of arrangement | positioning of a sensor part. It is a figure which shows the load added to a sensor part. It is a figure shown about the output signal obtained from a sensor part. It is a figure shown about the output signal obtained from a sensor part. It is a figure shown about the frequency analysis result of the output signal shown by FIG. It is a figure shown about the output signal obtained from a sensor part. It is a figure shown about the frequency analysis result of the output signal shown by FIG.

  Hereinafter, embodiments of the present invention will be described in detail. The biological information detection apparatus 100 according to the present invention has a function of detecting biological information emitted from a living body. The living body corresponds to a life form such as a person or an animal, and the biological information corresponds to the respiration or heartbeat of such a life form. In the following description, an example in the case of detecting a person's breathing and heartbeat using the biological information detection apparatus 100 will be described.

  FIG. 1 is a diagram schematically illustrating the structure of a sensor unit 10 included in the biological information detection apparatus 100. In particular, FIG. 1A shows a perspective view of the sensor unit 10. The sensor unit 10 according to the present embodiment is formed in a long shape and includes an output terminal 20 that outputs an output from the sensor unit 10 to the outside. Here, the sensor unit 10 includes a piezoelectric film 10a (piezoelectric body) (see FIG. 1D). The piezoelectric film 10a can be configured using a polymer piezoelectric material such as polyvinylidene fluoride (PVDF).

  When the piezoelectric film 10a is configured using PVDF, the PVDF is formed by extending in a predetermined direction. And it is suitable to form the sensor part 10 so that the direction where PVDF was extended | stretched and the elongate direction may correspond, when forming the piezoelectric film 10a. By configuring the sensor unit 10 in this manner, it is possible to increase the output voltage that is output when expansion or contraction or bending in the longitudinal direction occurs. Therefore, even a minute load change can be easily detected.

  Such a piezoelectric film 10a detects deformation in the expansion / contraction direction or bending. An output signal (output voltage) is output when a force acts in the expansion / contraction direction as shown in FIG. 1B or when a bending force acts as shown in FIG. Such an output signal (output voltage) is output only at the moment when force (load) is applied to the piezoelectric film 10a. That is, the output voltage is not output in a state where a constant force (load) is continuously applied. In addition, the magnitude of the output voltage that is output when a force (load) is applied is a magnitude corresponding to the strain rate of the piezoelectric film 10a when the force (load) is applied. The strain rate corresponds to the amount of strain per unit time. Since the characteristics of such a piezoelectric film are known, a detailed description thereof will be omitted.

  FIG. 1D shows a partial cross-sectional view of the sensor unit 10. In the cross-sectional view, a pair of electrodes 10b and 10c are disposed so as to sandwich the piezoelectric film 10a at the center portion. As described above, the piezoelectric film 10a is formed in a long shape. Therefore, the amount of expansion / contraction is larger when expanded / contracted in the long direction than when expanded / contracted in the direction orthogonal to the long direction (short direction), and as a result, a large output voltage is output. Similarly, the amount of bending increases when both ends in the long direction are bent closer to each other than when both ends in the short direction approach each other, and as a result, a large output voltage is output.

  Electrodes 10b and 10c are disposed on both the front and back surfaces of the piezoelectric film 10a. Therefore, the piezoelectric film 10a is sandwiched between the pair of electrodes 10b and 10c. The pair of electrodes 10b and 10c are connected to the output terminal 20 described above. For this reason, the output voltage output from the piezoelectric film 10a can be appropriately output to the outside via the output terminal 20.

  Here, the pair of electrodes 10b and 10c is formed of a conductor from the usage as an electrode. For this reason, in order to insulate the pair of electrodes 10b, 10c from the outside, the outer portions (upper surface, lower surface, side surfaces, etc.) of the pair of electrodes 10b, 10c are covered with the insulator 10d. An example of such an insulator is polyethylene terephthalate (PET). By covering the pair of electrodes 10b and 10c with such a polyethylene terephthalate, it is possible to appropriately transmit an external load to the piezoelectric film 10a while insulating the pair of electrodes 10b and 10c. Of course, it is naturally possible to use a material other than polyethylene terephthalate as such an insulator.

  In the present embodiment, the biological information detection apparatus 100 is described with an example in the case of detecting a person's breathing and heartbeat as described above. In such a case, it can be applied to, for example, the seat 30 provided in the vehicle. In such a case, the seat cushion 31 (see FIG. 2) of the seat 30 corresponds to the seat portion according to the present invention. When this biological information detection apparatus 100 is applied to a vehicle seat 30, it is possible to detect the breathing and heartbeat of a seated person seated on the vehicle seat 30, and the detected results are appropriately used for the vehicle. It can be used by transmitting it to a device that supports driving. A description of such usage forms is omitted.

  FIG. 2 is a diagram showing an outline of the sheet 30 provided with the biological information detection apparatus 100. The seat 30 includes a seat cushion 31, a seat back 32, and a headrest 33. The seat cushion 31 supports a seated person's buttocks. The seat back 32 functions as a backrest on which a seated person can lean. The headrest 33 has a function of protecting the seated person's head from a load acting on the rear of the vehicle.

  Here, the biological information detecting apparatus 100 according to the present invention is provided in a seat part in which a seating direction is determined in advance. As described above, the seat corresponds to the seat cushion 31 of the seat 30 provided in the vehicle. The seating direction is a direction in which the seated person sits, and is a direction along a virtual line connecting the back and knees of the seated person sitting on the seat cushion 31. The biological information detecting apparatus 100 can be used for the seat cushion 31 in which the seating direction is determined in this way.

  In addition, the sensor unit 10 is disposed so that the seating direction and the long direction coincide with each other over a position where one piezoelectric film 10a faces the buttocks of the seated person. The position facing the seat occupant's buttocks is a position on the rear side of the seat cushion 31 in the seating direction, and corresponds to the portion of the seat cushion 31 in contact with the seat occupant's buttocks. As described above, since the sensor unit 10 can easily detect the deformation in the longitudinal direction, it is possible to appropriately detect a change in the load in the seating direction.

  The sensor unit 10 is disposed so that the direction intersecting the thigh and the longitudinal direction coincide with each other over a position facing the thigh of the seated person sitting on the seat cushion 31. The position facing the thigh of the seated person is the position on the front side of the seat cushion 31 in the seating direction, and corresponds to the part of the seat cushion 31 that contacts the thigh of the seated person. This makes it possible to appropriately detect a change in load in the direction across the thigh.

  Here, as described above, the sensor unit 10 is disposed over the position facing the buttocks of the seated person and also over the position facing the thigh of the seated person. Therefore, in the following description, in order to facilitate understanding, the sensor unit 10 disposed so as to face the above-described buttocks is described with reference numeral 11 and disposed so as to face the thigh. The sensor unit 10 will be described with reference numeral 12.

  FIG. 3 shows a plan view of the seat cushion 31 provided with such sensor portions 11 and 12. FIG. 3 also schematically shows a seated person. Here, as described above, the sensor unit 11 (10) includes the long piezoelectric film 10a. As shown in FIG. 3, it is preferable that the sensor unit 11 is disposed in a pair so as to face the great gluteal muscle of the seated person in a plan view of the seat cushion 31. By arranging the sensor portions 11 as a pair in this way, it is possible to appropriately detect a change in load even when the seated person's body is seated while tilting to the left or right. In such a case, it is preferable that the length of the piezoelectric film 10a in the longitudinal direction is ¼ or more and less than ½ of the length of the seat cushion 31 in the seating direction. By forming the piezoelectric film 10a with such a size, it is possible to dispose the piezoelectric film 10a without overlapping each other while appropriately detecting the load. Of course, a configuration in which only one of them (that is, only one) is provided is also possible.

  In addition, as shown in FIG. 3, the sensor unit 12 (10) is also preferably disposed in a pair so as to intersect the thigh muscles of the seated person in a plan view of the seat cushion 31. By arranging the sensor portions 12a as a pair in this way, it is possible to appropriately detect a change in load even when the seated person's body is seated while tilting to the left or right. In such a case, it is preferable that the length of the piezoelectric film 10a in the longitudinal direction is ¼ or more and less than ½ of the length in the direction orthogonal to the seating direction of the seat cushion 31. By forming the piezoelectric film 10a with such a size, it is possible to dispose the piezoelectric film 10a without overlapping each other while appropriately detecting the load. Of course, it is also possible to adopt a configuration in which only one (that is, only one) is disposed.

  Here, as described above, the sensor units 11 and 12 are configured to include the piezoelectric film 10a, and output an output voltage when there is a change in the load applied to the piezoelectric film 10a. This output voltage is transmitted to the arithmetic unit 70. The calculation unit 70 calculates biological information based on the change in load. The change in the load corresponds to the change in the output voltage transmitted from the sensor units 11 and 12 as described above. In this embodiment, the biological information corresponds to the breathing and heartbeat of the seated person. Therefore, the calculation unit 70 calculates the breathing information of the seated person according to the change in the load, and calculates heart rate information. The respiration information is the respiration rate within a predetermined time. The heart rate information is a heart rate within a predetermined time. Of course, it is also possible to calculate in the form of each period and frequency.

  FIG. 4 shows the form of the load applied to the sensor units 11 and 12 when the seated person sits on the seat cushion 31 in which the sensor units 11 and 12 are arranged as described above. FIG. 4A shows a form in the case of detecting a seated person's heartbeat. In FIG. 4 (a), an arrow indicated by a symbol S indicates a load based on a heartbeat received from a seated person's buttocks. In such a case, a heartbeat corresponding to the blood flow flowing through the buttocks (that is, a heartbeat corresponding to the contraction of the blood vessels in the buttocks) is detected. Moreover, the arrow shown with the code | symbol T has shown the load based on the heartbeat which receives from a seated person's thigh. In such a case, a heartbeat corresponding to the blood flow flowing through the thigh (that is, a heartbeat corresponding to the contraction of blood vessels in the thigh) is detected.

  FIG. 4B shows a form in the case where the breathing of the seated person is detected. In FIG.4 (b), the arrow shown with the code | symbol U has shown the load based on the respiration received from a seated person's buttocks. Here, when a person breathes, the body shakes in response to the breathing. Due to this shaking, a load is applied to the sensor unit 11 provided to face the collar unit. Thus, the sensor unit 11 can detect respiration as well as the heartbeat of the seated person.

  Next, a description will be given using the output detected by the biological information detection apparatus 100. FIG. 5 shows an output voltage obtained from one of the pair of sensor portions 11 disposed to face the collar portion. The horizontal axis is time, and the vertical axis is output voltage. The output voltage shown in FIG. 5 includes changes in the load related to the breathing and heartbeat of the seated person. In FIG. 5, the amplitude with a period of about 3 seconds is a change in load due to respiration. An amplitude with a period of about 1 second is a change in load due to a heartbeat.

  For reference, FIG. 6 shows the result when the seated person stops breathing and detects a change in load due to heartbeat. As described above, a change in load due to a heartbeat can be confirmed with a period of about 1 second. However, normally, the occupant does not stop breathing while driving the vehicle. In addition, as shown in FIG. 5, since the cycle related to the heartbeat is superimposed on the cycle related to respiration, it is necessary to consider the cycle of respiration in order to calculate the cycle related to the heartbeat. For this reason, the calculation performed by the calculation unit 70 becomes complicated. Therefore, the sensor unit 11 disposed facing the buttocks is suitable mainly for detecting a load due to respiration.

  FIG. 7 shows a waveform obtained by frequency analysis of the waveform related to the output voltage shown in FIG. In FIG. 7, the horizontal axis represents frequency and the vertical axis represents intensity. The frequency analysis this time was performed using Fast Fourier Transform (FFT). Since the fast Fourier transform is a known technique, description thereof is omitted. Here, for example, when the vehicle is traveling at a speed of 30 to 50 km per hour, a vibration of 4 to 7 Hz is mainly transmitted to the human body as a traveling noise received from a road or the like. For this reason, as shown in FIG. 7, the resonance frequency of the human body is superimposed. Therefore, also from this result, it can be seen that the sensor unit 11 disposed so as to face the buttocks as described above is suitable mainly for detecting a load due to respiration.

  FIG. 8 shows an output voltage obtained from one of the pair of sensor units 12 arranged to face the thigh. The horizontal axis is time, and the vertical axis is output voltage. The output voltage shown in FIG. 8 corresponds to a change in the load related to the seated person's heartbeat. Since shaking due to breathing is difficult to be transmitted to the thigh, only the load related to the heartbeat is detected. Similar to the output voltage obtained by the pair of sensor portions 11 disposed to face the above-described collar portion, an amplitude having a period of about 1 second is obtained.

  FIG. 9 shows a waveform obtained by performing frequency analysis of the waveform related to the output voltage shown in FIG. In FIG. 9, the horizontal axis represents frequency and the vertical axis represents intensity. In addition, the frequency analysis of FIG. 9 is also performed using the fast Fourier transform similarly to FIG. In the waveform shown in FIG. 9, it can be seen that, unlike the waveform shown in FIG. 7, the intensity of the output voltage in the region of the resonance frequency of the human body of about 4 to 7 Hz is small. Therefore, the sensor unit 12 disposed facing the thigh is suitable for detecting a load due to a heartbeat.

[Other Embodiments]
In the above-described embodiment, an example in which the biological information detection device 100 is applied to the seat 30 provided in the vehicle has been described. However, the scope of application of the present invention is not limited to this. Of course, it can be applied to other sheets 30.

  In the above-described embodiment, the sensor unit 11 has been described as being disposed in a pair so as to face the gluteal muscle of the seated person in a plan view of the seat cushion 31. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to arrange only one of the left and right sides so as to face the gluteal muscle of the seated person.

  In the above-described embodiment, the sensor unit 12 is described as being disposed in a pair so as to intersect the thigh muscles of the seated person in the plan view of the seat cushion 31. However, the scope of application of the present invention is not limited to this. Of course, it is possible to arrange only one of the left and right sides so as to intersect the thigh muscle of the seated person.

  In the above-described embodiment, the sensor unit 12 has been described as being disposed so that the direction intersecting the thigh and the longitudinal direction coincide with each other over the position facing the thigh of the seated person. However, the scope of application of the present invention is not limited to this. Of course, the sensor unit 12 may not be disposed at a position facing the thigh.

  In the above-described embodiment, the calculation unit 70 has been described as calculating the breathing information of the seated person according to the change in the load based on the swing in the seating direction. However, the scope of application of the present invention is not limited to this. It is naturally possible to calculate heart rate information together with the breathing information of the seated person.

  In the above embodiment, the position where the sensor unit 11 is disposed is described as the position on the rear side of the seat cushion 31 in the seating direction. However, the scope of application of the present invention is not limited to this. Needless to say, the sensor unit 11 can also be disposed on the front side of the seat cushion 31 in the seating direction.

  In the embodiment described above, the length in the longitudinal direction of the piezoelectric film 10 a included in the sensor unit 11 has been described as being ¼ or more and less than ½ of the length of the seat cushion 31 in the seating direction. Further, it has been described that the length in the longitudinal direction of the piezoelectric film 10 a included in the sensor unit 12 is not less than ¼ and less than ½ of the length in the direction orthogonal to the seating direction of the seat cushion 31. However, the scope of application of the present invention is not limited to this. Of course, the length in the longitudinal direction of the piezoelectric film 10a may be different from the above.

  The present invention can be used in a biological information detection device that detects biological information of a seated person sitting on a seat.

DESCRIPTION OF SYMBOLS 10: Sensor part 11: Sensor part 12: Sensor part 30: Seat 31: Seat cushion 32: Seat back 33: Headrest 70: Calculation part 100: Biological information detection apparatus

Claims (6)

For seats that have a predetermined seating direction,
A single long piezoelectric film that detects deformation in the direction of expansion or contraction or bending is arranged with the seating direction and the long direction coincided with each other across the position facing the buttocks of the seated person to detect changes in the load. A sensor unit to
A calculation unit for calculating biological information based on the change in the load;
A biological information detection apparatus comprising:   The biological information detection device according to claim 1, wherein the sensor unit is disposed in a pair so as to face the greater gluteus of the seated person in a plan view of the seat.   The biological information detection apparatus according to claim 1, wherein the calculation unit calculates the breathing information of the seated person according to a change in load based on the swing in the seating direction.   The living body information detecting device according to any one of claims 1 to 3, wherein a position facing the flange portion is a position on a rear side of the seat portion in the seating direction.   The biological information detection apparatus according to any one of claims 1 to 4, wherein a length of the piezoelectric film in a longitudinal direction is ¼ or more and less than ½ of a length of the seat portion in a seating direction.   The living body according to any one of claims 1 to 5, wherein the piezoelectric film is formed by stretching PVDF, and the sensor unit is formed so that the extending direction and the longitudinal direction coincide with each other. Information detection device.

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