Measurement device and vehicle seat having the measurement device

Abstract

[Problem] To facilitate the detection of minute signals without the saturation of the signals, even in a high-noise environment. [Solution] The present measurement device includes: (A) a first bag-like member which receives a first vibration; (B) a second bag-like member which receives a second vibration; and (C) a differential pressure sensor which detects a difference in pressure between a first pressure transmitted from inside of the first bag-like member and a second pressure transmitted from inside of the second bag-like member. The present measurement device is embedded in a vehicle seat, for example.

Description

[Technical Field]

[0001] The present invention relates to a measuring device for measuring a differential pressure and a vehicle seat having the measuring device. [Background technology]

[0002] In recent years, solutions that use various types of sensors to monitor people's activity in indoor and outdoor environments, detect vital signs, and monitor mental and physical states to detect abnormalities in the human body and avoid unforeseen circumstances are becoming more widespread.

[0003] A technology for measuring vital signals using a piezoelectric element on a bed or other device is disclosed in, for example, Patent Document 1, but this technology cannot measure properly when there is body movement or other disturbance vibration. Specifically, when a measuring device using this technology is mounted on a car and the car is traveling, road noise and other factors cause signal saturation, as shown in Figure 1, making it impossible to detect vital signals. In Figure 1, the vertical axis represents signal amplitude [V], and the horizontal axis represents time. In Figure 1, no signal saturation occurs when the car is stopped, but saturation occurs in the output signal of the measuring device while the car is traveling.

[0004] Furthermore, for example, Patent Document 2 focuses on the problem that road noise during driving saturates the output signal of a pressure sensor, making it impossible to detect minute levels of biological information, including heart rate signals. This device addresses this problem by transmitting pressure received by a single pressure fluctuation signal deriving means through two filters with a predetermined transfer function and measuring it with a differential pressure sensor. This technology requires a container of a predetermined size to achieve the predetermined transfer function, separate from the pressure fluctuation signal deriving means and the differential pressure sensor, resulting in a large overall size. Furthermore, adjusting the actual container and tubes to achieve the predetermined transfer function also poses problems.

[0005] Although there is technology that uses piezoelectric sensors to measure vital signs while a vehicle is moving, it does not address the problems described above. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-219341 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-218068 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-42904 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-346109 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, according to one aspect, an object of the present invention is to provide a novel technique for facilitating detection of a weak signal without signal saturation even in a noisy environment. [Means for solving the problem]

[0008] The measuring device of the present invention includes (A) a first bag-shaped member that receives a first vibration, (B) a second bag-shaped member that receives a second vibration, and (C) a differential pressure sensor that detects the differential pressure between a first pressure transmitted from inside the first bag-shaped member and a second pressure transmitted from inside the second bag-shaped member. [Effects of the Invention]

[0009] According to one aspect of the present invention, it becomes easier to detect a weak signal without signal saturation even in a noisy environment. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating the problems of the prior art. [Figure 2] FIG. 2 is a diagram showing an outline of a measurement device according to an embodiment of the present invention. [Figure 3]FIG. 3 is a diagram showing an example of an assumed change over time in the pressure received by the first pad. [Figure 4] FIG. 4 is a diagram showing an example of an assumed change in pressure received by the second pad over time. [Figure 5] FIG. 5 is a diagram showing an example of an assumed change over time in pressure detected by a piezoelectric element of a differential pressure sensor. [Figure 6] FIG. 6 is a diagram showing an example of a signal that is assumed when the detected pressure is amplified by an amplifier. [Figure 7] FIG. 7 is a diagram showing an example of measurement performed by the measurement device according to this embodiment. [Figure 8] FIG. 8 is a diagram showing an assumed example of the measurement results of the first pressure sensor when an active noise canceller is employed. [Figure 9] FIG. 9 is a diagram showing an assumed example of the measurement results of the second pressure sensor when an active noise canceller is employed. [Figure 10] FIG. 10 is a diagram showing an example in which the signal in FIG. 8 is converted into an electrical signal and amplified. [Figure 11] FIG. 11 is a diagram showing an example in which the signal in FIG. 9 is converted into an electrical signal, amplified, and converted into an inverse phase. [Figure 12] FIG. 12 is a diagram showing an example of a signal obtained by adding the signal in FIG. 10 and the signal in FIG. [Figure 13] FIG. 13 is a diagram showing an example of an assumed measurement result of the first pressure sensor when the noise is larger than that in FIG. [Figure 14] FIG. 14 is a diagram showing an example in which the signal in FIG. 13 is converted into an electrical signal and amplified. [Figure 15] FIG. 15 is a perspective view of the appearance of the differential pressure sensor. [Figure 16] FIG. 16 is a perspective view of the differential pressure sensor with the top cover removed. [Figure 17] FIG. 17 is a cross-sectional view of a differential pressure sensor. [Figure 18] FIG. 18 is a diagram showing an example of the overall configuration of the measurement device. [Figure 19]FIG. 19 is a perspective view of a seat of an automobile. [Figure 20] FIG. 20 is a diagram showing an example of the arrangement of the first case in which two pads are arranged side by side and close to each other. [Figure 21] FIG. 21 is a diagram showing an example of a case arrangement in which two pads are stacked so as to be in contact with each other vertically. [Figure 22] FIG. 22 shows an example of a case arrangement in which two pads are arranged vertically and spaced apart so as to overlap each other. [Figure 23] FIG. 23 shows an example of a pad arrangement that makes it difficult to extract vital signals. [Figure 24] FIG. 24 shows an example of a pad arrangement that makes it difficult to extract vital signals. [Figure 25] FIG. 25 is a diagram showing an example of the results of processing the output of the differential pressure sensor with a band-pass filter when traveling at 10 km / h. [Figure 26] FIG. 26 is a diagram showing an example of a pulse wave signal measured by attaching a pulse wave sensor to a fingertip. [Figure 27] FIG. 27 is a diagram showing an example of the results of performing FFT on the signal shown in FIG. [Figure 28] FIG. 28 is a diagram showing an example of the results of performing FFT on the signal shown in FIG. [Figure 29] FIG. 29 is a diagram showing an example of the results of processing the output of the differential pressure sensor with a band-pass filter when traveling at 30 km / h. [Figure 30] FIG. 30 is a diagram showing an example of the results of performing FFT on the signal shown in FIG. [Figure 31] FIG. 31 is a diagram showing an example of the results of processing the output of the differential pressure sensor with a band-pass filter when traveling at 50 km / h. [Figure 32] FIG. 32 is a diagram showing an example of the results of performing FFT on the signal shown in FIG. [Figure 33] FIG. 33 is a diagram showing an example of a mat for evaluating the separation distance of pads. [Figure 34]FIG. 34 is a diagram showing a first pattern of pad arrangement. [Figure 35] FIG. 35 is a diagram showing a second pattern of pad arrangement. [Figure 36] FIG. 36 is a diagram showing a third pattern of pad arrangement. [Figure 37] FIG. 37 is a diagram showing an example of a signal output in the first pattern. [Figure 38] FIG. 38 is a diagram showing an example of a signal output in the second pattern. [Figure 39] FIG. 39 is a diagram showing an example of a signal output in the third pattern. [Figure 40] FIG. 40 is a diagram showing an example of a signal when the gain of the amplifier is reduced compared to the case of FIG. [Figure 41] FIG. 41 is a diagram showing an example of the result of processing the signal of FIG. 37 with a band-pass filter. [Figure 42] FIG. 42 is a diagram showing an example of the result of FFT on the signal of FIG. [Figure 43] FIG. 43 is a diagram showing an example of the result of processing the signal of FIG. 38 with a band-pass filter. [Figure 44] FIG. 44 is a diagram showing an example of the result of FFT on the signal of FIG. [Figure 45] FIG. 45 is a diagram showing an example of the result of processing the signal of FIG. 39 with a band-pass filter. [Figure 46] FIG. 46 is a diagram showing an example of the result of FFT on the signal of FIG. [Figure 47] FIG. 47 is a diagram showing an example of the result of processing the signal of FIG. 40 with a band-pass filter. [Figure 48] FIG. 48 is a diagram showing an example of the result of FFT on the signal of FIG. [Figure 49] FIG. 49 is a diagram for explaining how standard noise is transmitted. [Figure 50] FIG. 50 shows modified examples of pad sizes for dealing with noise from above. [Figure 51] FIG. 51 shows a modified example of the tube for dealing with noise from above. [Figure 52] FIG. 52 is a diagram showing a modified example of the space inside the differential pressure sensor when dealing with noise from above. [Figure 53] FIG. 53 shows modified examples of pad sizes for dealing with noise from below. [Figure 54] FIG. 54 shows a modified example of the tube for dealing with noise from below. [Figure 55] FIG. 55 is a diagram showing a modified example of the space inside the differential pressure sensor when dealing with noise from below. [Figure 56] FIG. 56 is a simplified cross-sectional view of a first modified example of the seat. [Figure 57] FIG. 57 is a simplified cross-sectional view of a second modified example of the seat. [Figure 58] FIG. 58 shows a basic example of pad layout. [Figure 59] FIG. 59 is a diagram showing an example of pad arrangement using a plate. [Figure 60] FIG. 60 is a cross-sectional perspective view of a pad with a plate portion. [Figure 61] FIG. 61 is a diagram showing an example of a pad arrangement using a pad with a plate portion. [Figure 62] FIG. 62 is a diagram showing another example of a pad arrangement using a pad with a plate portion. [Figure 63] FIG. 63 is a diagram showing yet another example of a pad arrangement using a pad with a plate portion. [Figure 64] FIG. 64 shows an example of a configuration in which a plate portion is attached to an integrated pad. [Figure 65] FIG. 65 shows an example of the arrangement of an integrated pad with a plate portion. [Figure 66] FIG. 66 is a diagram showing an example of a pad arrangement using gaps and plates. [Figure 67] FIG. 67 is a diagram showing another example of pad arrangement using gaps and plates. [Figure 68] FIG. 68 is a diagram showing yet another example of pad arrangement using gaps and plates. [Figure 69] FIG. 69 shows the measurement results when the capacitance type differential pressure sensor is configured so as not to measure differential pressure. [Figure 70] FIG. 70 is a diagram showing the measurement state of FIG. [Figure 71] FIG. 71 is a diagram showing the measurement results when the measurement is performed using a capacitance type differential pressure sensor. [Figure 72] FIG. 72 is a diagram showing a typical output mode of the measurement results when the measurement device is mounted on an automobile. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Outline of the embodiment of the present invention] The section on embodiments of the present invention discloses a measurement device for solving the above-mentioned problems. This measurement device includes (a) a first bag-shaped member that receives a first vibration, (b) a second bag-shaped member that receives a second vibration, and (c) a differential pressure sensor that detects the differential pressure between a first pressure transmitted from inside the first bag-shaped member and a second pressure transmitted from inside the second bag-shaped member.

[0012] With this configuration, it is possible to properly measure the differential pressure between the first pressure caused by the first vibration input through the first bag-shaped member and the second pressure caused by the second vibration input through the second bag-shaped member. For example, if the same noise is present in the first pressure and the second pressure, they are canceled out by the structure of the differential pressure sensor, and if a weak vibration of the object to be measured is present in either bag-shaped member, a weak signal corresponding to the weak vibration of the object to be measured will be detected without saturation.

[0013] The measurement device may further include (d) a first tube connecting the first bag-shaped member and the differential pressure sensor, and (e) a second tube connecting the second bag-shaped member and the differential pressure sensor, allowing the differential pressure sensor to be located at a position away from the first and second bag-shaped members.

[0014] The first bag-shaped member and the second bag-shaped member may be positioned so that they are closely or separately stacked. This is a more preferable configuration for measuring vital signals. In other words, it is effective in canceling noise. If the bag-shaped members are flat, they are more likely to receive vibrations, and if they are stacked, they can be placed in a smaller space. Furthermore, if they are installed on a seat cushion or the like, it is easy to ensure that the same load is applied to both. The first bag-shaped member and the second bag-shaped member may not only be in close contact with each other, but may also be stacked with resin or the like sandwiched between them.

[0015] The first bag-shaped member and the second bag-shaped member may be arranged in close contact or spaced apart, overlapping each other. For example, the first bag-shaped member and the second bag-shaped member may be arranged in layers, with or without a separate material between the two bag-shaped members. This makes it easier to detect weak signals. This allows for more effective noise cancellation.

[0016] Furthermore, the first bag-shaped member and the second bag-shaped member may be flat, and the first bag-shaped member and the second bag-shaped member may be integrated so that the central portions of the flat plates are closely or spaced apart and overlap. If they are integrated, there is no misalignment between the first bag-shaped member and the second bag-shaped member, and it is possible to prevent the relative positions of the first bag-shaped member and the second bag-shaped member from changing during use. The first bag-shaped member and the second bag-shaped member may be closely or spaced apart.

[0017] Furthermore, a plate portion may be provided on at least a portion of the edge of at least one of the first bag-shaped member and the second bag-shaped member. For example, even when the bag-shaped member is embedded in a vehicle seat cushion, sinking of the bag-shaped member due to load can be prevented, making it easier to detect weak signals. Sinking consumes energy, making the signal weaker, but preventing sinking allows for stronger signals to be captured.

[0018] Furthermore, the first bag-shaped member and the second bag-shaped member may be integrated, and an outwardly extending plate portion may be added to at least a portion of the outer periphery of the integrated first and second bag-shaped members. Even if one plate portion is provided for two bag-shaped members, rather than providing a plate portion for each bag-shaped member, sinking of the bag-shaped members due to load can be suppressed.

[0019] Resin may be added to the first bag-shaped member and the second bag-shaped member. For example, resin may be added so as to cover at least one surface of the first bag-shaped member and the second bag-shaped member. The resin can protect the bag-shaped member, regulate its position, and adjust the transmission of vibrations. For example, a resin layer may be provided between the first bag-shaped member and the second bag-shaped member.

[0020] The differential pressure sensor may be a capacitance type differential pressure sensor, a piezo-resistance type differential pressure sensor, or a differential transformer type differential pressure sensor. As such, if the detection target is a signal with a relatively large amplitude, such as body movement, various types of conventional differential pressure sensors can be used.

[0021] On the other hand, the differential pressure sensor may be a differential pressure sensor having a first chamber communicating with the interior of the first bag-shaped member, a second chamber communicating with the interior of the second bag-shaped member, and a vibrating membrane separating the first and second chambers and having a piezoelectric body formed thereon. By employing such a differential pressure sensor, even weak signals such as pulse waves can be detected without signal saturation due to noise.

[0022] In some cases, the first bag-shaped member is placed closer to the object to be measured than the second bag-shaped member. By placing either one of the bag-shaped members closer to the object to be measured, it becomes easier to detect weaker signals.

[0023] The measuring device may further include (d) a signal processing unit that processes signals from the differential pressure sensor, and (e) an output unit that outputs an output signal from the signal processing unit to an external device, thereby enabling appropriate signal processing to be performed on weak signals to be detected.

[0024] The above-mentioned measuring device is installed, for example, in a vehicle seat of an automobile, etc. That is, the vehicle seat has (f) a first bag-shaped member, (g) a second bag-shaped member, and (h) a differential pressure sensor that detects the differential pressure between a first pressure transmitted from inside the first bag-shaped member and a second pressure transmitted from inside the second bag-shaped member, and is arranged inside a portion that comes into contact with a predetermined part of the human body so that the first bag-shaped member is closer to the predetermined part of the human body than the second bag-shaped member.

[0025] The part that comes into contact with the predetermined part of the human body is mainly the seat or back. The seat is suitable for detecting pulse waves, pulse, or breathing from the arteries in the soles of the legs or buttocks, or from the movement of the human body surface, while the back can detect pulse, breathing, etc. from body movement, or from the arteries in the waist or back, or from the movement of the human body surface.

[0026] Furthermore, the first bag-shaped member and the second bag-shaped member may be stacked together, either closely or separately, and provided in the resin material at the portion where the predetermined part of the human body comes into contact. In this way, noise can be more easily canceled out, and weak signals can be more easily detected.

[0027] Furthermore, a component including the first and second bag-shaped members may be disposed in a groove or recess that regulates the positions of the first and second bag-shaped members. In this manner, the first and second bag-shaped members are disposed so as to facilitate detection of weak signals while preventing misalignment. When the sensor is used in a vehicle and the vehicle is running, road noise changes over time. If the bag-shaped members are displaced horizontally or vertically, the signals entering the two bag-shaped members tend to differ.

[0028] A plate with an area larger than that of the second bag-shaped member may be provided below the second bag-shaped member in order to prevent the first and second bag-shaped members from sinking due to the weight of the human body, thereby preventing weak signals from being attenuated.

[0029] Furthermore, a gap may be provided below the plate, or between the second bag-shaped member and the plate, in order to suppress external vibrations from below the gap.

[0030] In addition, the part that comes into contact with the specific part of the human body may be made of foamed resin. This protects the first bag-shaped member while making it easier to receive weak signals. It is also effective in terms of comfort, that is, in reducing discomfort in the buttocks when sitting.

[0031] Various variations of the above-described measuring device may also be employed in vehicle seats. In this way, by providing a differential pressure sensor in a vehicle seat, it is possible to detect the driver's vital signals, etc. Therefore, by analyzing such vital signals, it is possible to determine the driver's stress and health state, and to decide whether to continue driving or take measures to change their mood. For example, if an abnormality is detected in the driver's vital signals, etc., a command to stop the vehicle can be issued to the control circuit that controls the driving, thereby stopping the vehicle and preventing an accident. Furthermore, by recording these vital signals, etc. in a recorder, the driver's health state can be saved as data and provided to police and insurance companies for investigation, which will be useful for investigating the cause of accidents and preventing accidents.

[0032] The above-mentioned matters will be explained more specifically below as a first embodiment and a second embodiment.

[0033] [First embodiment] [Outline of the first embodiment] An overview of a measurement device according to an embodiment of the present invention is shown in Figure 2. Measurement device 100 includes differential pressure sensor 110, first pad 150 and second pad 160 which are fluid-encapsulated bodies, tube 130 connecting differential pressure sensor 110 and first pad 150, and tube 140 connecting differential pressure sensor 110 and second pad 160.

[0034] The differential pressure sensor 110 has a first space 112 and a second space 114 provided within a housing 111, and the first space 112 and the second space 114 are separated by a vibrating membrane (also called a diaphragm) 116. A piezoelectric element 118 is formed on the vibrating membrane 116 (on the surface facing the first space 112 in the example of FIG. 2). A signal line to a signal processing unit is connected to the piezoelectric element 118, and the signal processing unit performs signal processing such as amplification, band-pass filtering, and FFT (Fast Fourier Transformation) on the output signal from the piezoelectric element 118. The piezoelectric element 118 may also be provided on the surface of the vibrating membrane 116 facing the second space 114.

[0035] Furthermore, housing 111 is divided into two chambers by vibrating membrane 116. This vibrating membrane 116 forms the side wall, or in this case the bottom surface, of the first chamber corresponding to first space 112, and also forms the side wall, or in this case the top surface, of the second chamber corresponding to second space 114. Therefore, unlike when two separate chambers are provided, the vibrating membrane can be used as both the bottom and top surfaces, which allows the overall size of differential pressure sensor 110 to be reduced and only one pair of vibrating membrane and piezoelectric membrane is required. Housing 111 is cylindrical as shown in FIG. 15, but it may also be a rectangular parallelepiped, a sphere, or the like.

[0036] Furthermore, a first connection part 120 and a second connection part 122 are provided on the housing 111 of the differential pressure sensor 110, and the first connection part 120 is connected to a tube 130, and the second connection part 122 is connected to a tube 140.

[0037] Depending on the arrangement of the differential pressure sensor 110, the first pad 150, and the second pad 160, the tubes 130 and 140 may not be provided, and their lengths may be adjusted.

[0038] The first pad 150 and the second pad 160 are hollow bag-shaped members, and in this embodiment, air is sealed in them as a fluid during use. Therefore, the first pad 150 is in communication with the first space 112 of the differential pressure sensor 110 via the tube 130 and the first connecting portion 120, and vibrations received by the first pad 150 are transmitted to the vibrating membrane 116. Similarly, the second pad 160 is in communication with the second space 114 of the differential pressure sensor 110 via the tube 140 and the second connecting portion 122, and vibrations received by the second pad 160 are transmitted to the vibrating membrane 116. Such pads are also referred to as air mats.

[0039] Furthermore, the external shapes of the first pad 150 and the second pad 160 are thin rectangular parallelepipeds, such as smaller versions of air mattresses or cushions, or circular or oval shapes resembling edible pie dough in plan view, forming hollow bags. The bags are kept under pressure to prevent them from collapsing under the subject's weight. The bags are filled with gas, fluid, or gel and are made of resin that can deform when a load is applied. The two pads are the same size, e.g., 40 mm wide, 40 mm deep, and 5 mm thick.

[0040] That is, the first pad 150 and the second pad 160 are placed in a location where a human body's vital signals (e.g., pulse waves) can be detected, such as a car seat, a desk chair, a bed, a mat, or a wristwatch, and vibrations corresponding to the vital signals are detected along with disturbances such as body movement and road noise.

[0041] In this embodiment, if first pad 150 receives noise and vital signals, and second pad 160 receives only noise, the noise component is mechanically canceled by vibration membrane 116, and only the vital signals are detected by piezoelectric element 118. This prevents the signal output from piezoelectric element 118 from becoming saturated even when there is a lot of noise, making it possible to detect vital signals.

[0042] This principle will be explained schematically in FIGS.

[0043] First, consider the time change in pressure due to vibration received by the first pad 150, as shown in FIG. 3. That is, FIG. 3 illustrates a pressure change in which a high-frequency vital signal component is superimposed on a low-frequency, large-amplitude noise component. Meanwhile, consider the time change in pressure due to vibration received by the second pad 160, as shown in FIG. 4. FIG. 4 illustrates a pressure change caused only by a low-frequency, large-amplitude noise component. When the pressure change shown in FIG. 3 is transmitted to the first space 112 of the differential pressure sensor 110, and the pressure change shown in FIG. 4 is transmitted to the second space 114 of the differential pressure sensor 110, the noise component is canceled out within the differential pressure sensor 110, and the vibrating membrane 116 begins to vibrate with the vital signal component as shown in FIG. 5. When the vibrating membrane 116 vibrates as shown in FIG. 5 and the output of the piezoelectric element 118 is amplified, an electrical signal corresponding to the vital signal can be generated, as shown in FIG. 6.

[0044] In this way, according to the configuration of this embodiment, an electrical signal corresponding to a vital signal can be output without signal saturation occurring, and useful information can be obtained by signal processing of the electrical signal.

[0045] Fig. 7 shows the results of measurements taken when the first pad 150 and the second pad 160 according to this embodiment were placed on the passenger seat of a vehicle and a person's legs were placed on top of them. This example shows measurements taken when the vehicle started moving from a stopped state and traveled at a constant speed of 20 km / h. Except for the initial section at the start of travel, the signal was measured without saturation.

[0046] Note that Figure 1 shows the results of measurements taken under the same conditions as Figure 7, except that the technology in Patent Document 1 was used. As mentioned above, although measurements could be taken when the vehicle was stopped, signal saturation occurred when the vehicle was moving.

[0047] There is also a technology called an active noise canceller, but this technology does not function in a state where there is a lot of noise, as is assumed in this embodiment.

[0048] For example, consider a case where a first pressure sensor detects a pressure change as shown in Figure 8, and a second pressure sensor detects a pressure change as shown in Figure 9. Figure 8 shows a state in which high-frequency vital signal components are superimposed on low-frequency noise components, as shown in Figure 3, but the low-frequency noise components are not as large as in Figure 3. Figure 9 shows a state in which the same low-frequency noise components as in Figure 8 are detected.

[0049] When the pressure change detected by the first pressure sensor is converted into an electrical signal and amplified, a signal like the one shown in Figure 10 is obtained, and when the pressure change detected by the second pressure sensor is converted into an electrical signal, amplified, and converted into an inverse phase, a signal like the one shown in Figure 11 is obtained. By adding these signals, the noise component is canceled out and a high-frequency vital signal component is obtained, as shown in Figure 12.

[0050] However, since the noise component is not so large, the high frequency vital signal component can be obtained, but if the noise component becomes large, the high frequency vital signal component will disappear.

[0051] Specifically, when the first pressure sensor detects a pressure change as shown in Figure 13, converts the pressure change into an electrical signal, and amplifies it with the same amplification factor, a signal as shown in Figure 14 is obtained. That is, part of the signal exceeds the upper and lower limits (here, ±10 V), and high-frequency signal components are lost.

[0052] In contrast to this, if two pads and differential pressure sensor 110 are used as in this embodiment, the noise component can be mechanically cancelled, and the vital signal component can be extracted without saturation.

[0053] In an ideal situation, complete cancellation is possible, but in a real environment, complete cancellation is difficult. Therefore, a differential pressure sensor is used to reduce noise components, prevent saturation, and signal processing is used to extract vital components.

[0054] For example, if the same noise is transmitted to two pads and vital vibrations are transmitted to only one pad, the noise is completely removed by the difference, even though the noise and vital vibrations are at the same frequency, and the vital vibrations are extracted ideally. If the pressures of the two pads are canceled out by the diaphragm inside the sensor, saturation will not occur in the subsequent analog circuitry.

[0055] Furthermore, if the driving voltage of the analog circuit is 3.3V and the vibration amount is expressed in voltage for convenience, if noise equivalent to 10V and a vital equivalent to 1V (total voltage 11V) are applied to one pad, and noise equivalent to 8V and a vital equivalent to 0.8V (total voltage 8.8V) are applied to the other pad, the voltage that is mechanically canceled by the sensor diaphragm is 8.8V, and 2.2V remains uncancelled, which is less than 3.3V, so saturation does not occur in the analog circuit and it is sufficient to extract the remaining vital component of 0.2V.

[0056] [Specific Configuration Example of Differential Pressure Sensor in First Embodiment] Fig. 15 shows a perspective view of the exterior of differential pressure sensor 110. As shown in Fig. 15, differential pressure sensor 110 in this example is roughly cylindrical, with a first connection part 120 (also called an introduction tube) for connecting to tube 130 and a second connection part 122 (also called an introduction tube) for connecting to tube 140 protruding from the cylinder. Top cover 1101 of housing 111 of differential pressure sensor 110 is detachable from housing 111.

[0057] Figure 16 shows the state with top lid 1101 removed. When top lid 1101 is removed, first space 112 (i.e., chamber) appears, and a disk-shaped piezoelectric element 118 is formed at the bottom of first space 112. The two ridges represent solder. A seal member or the like is provided between top lid 1101 and housing 111 to prevent air leakage. The hatched area is the inner wall of the housing.

[0058] 17 shows a cross-sectional view of differential pressure sensor 110 taken along a plane passing through first connecting portion 120 and second connecting portion 122. In this example, piezoelectric element 118 is formed by piezoelectric body 1181 and diaphragm 116. That is, solder 1182 is provided on an electrode of piezoelectric body 1181, and a lead is fixedly connected to it, and diaphragm 116 is the other electrode, and solder 1161 is provided on diaphragm 116, and a lead is connected to it. Diaphragm 116 is a metal disk such as brass, and its edge is supported and fixed by a ring-shaped protrusion provided around the inner wall of housing 111. A plating film, such as copper plating or gold plating, may be applied to improve the wettability of the solder.

[0059] This vibrating membrane 116 is disk-shaped, and a small disk-shaped piezoelectric body 1181 is provided on top of it. It is preferable that the centers of these bodies are aligned. Vibrations occur higher up and down at the center of the vibrating membrane 116, and in order for the piezoelectric body to properly receive these vibrations, detection accuracy is improved if the centers are aligned. In this example, the vibrating membrane 116 has a diameter of 15 mm and a thickness of 0.05 mm, and the piezoelectric body 1181 has a diameter of 12 mm and a thickness of 0.05 mm.

[0060] Since the leads are generally fixed with solder or conductive paste, a metal that can be coated with this conductive adhesive is selected for the diaphragm. Brass is used here. However, diaphragm 116 can also be made of ceramic, nickel alloy, copper-based alloy, stainless steel, etc.

[0061] Furthermore, because vibrating membrane 116 vibrates, the reliability of the soldering must be taken into consideration. Vibrations are large at the center of disc-shaped or square vibrating membrane 116 and at the center or vicinity of disc-shaped or square piezoelectric body 1181. This fixing portion is preferably on the periphery of a circle, a square outline, or the periphery or vicinity of the outline, whenever possible.

[0062] The vibrating membrane 116 is fixed to the protrusion near the periphery. Since vibration is suppressed at and near this fixed portion, it is preferable to fix it here. In the figure, a solder connection portion is provided on the protrusion.

[0063] 17, piezoelectric body 1181 has an electrically fixed portion near the convex member (the edge of the piezoelectric body) while avoiding the top of the convex portion. Similarly, vibration membrane 116 has an electrically fixed portion near the outer periphery (edge) on or near the convex portion.

[0064] Although not shown, lead wires extending from solders 1182 and 1161 are connected to a circuit in third space 124 provided in housing 111. When using solder, depending on the material of diaphragm 116 (such as ceramic or stainless steel), a coating of copper or an alloy mainly made of copper, which has good solder wettability, may be formed and the diaphragm 116 may be fixed to this via solder.

[0065] In this example, although the shapes are different, the volume of first space 112 is the same as the volume of second space 114. In other words, diaphragm 116 divides the main internal space of housing 111 into two equal parts.

[0066] The third space 124 is provided separately from the second space 114 below the second space 114, and the third space 124 includes a circuit board 1241 and circuit components 1242 such as an analog amplifier provided on the circuit board 1241.

[0067] Furthermore, since the housing 111 is molded in advance, in consideration of connection with the circuit components 1242 and workability, it is more efficient to provide the leads via solder on the upper side with the top cover removed.

[0068] In this example, to save space, the circuit board 1241 is provided inside the differential pressure sensor 110, but it may also be provided outside the differential pressure sensor 110. The circuit component 1242 is connected to a circuit outside the differential pressure sensor 110 by a lead wire (not shown), and outputs a signal that has been amplified or attenuated by an analog amplifier included in the circuit component 1242.

[0069] As mentioned above, the change in air pressure caused by the vibration transmitted from first connection part 120 is transmitted to diaphragm 116 via first space 112 (i.e., chamber). Similarly, the change in air pressure caused by the vibration transmitted from second connection part 122 is transmitted to diaphragm 116 via second space 114 (i.e., chamber). Diaphragm 116 receives air pressure on both the top and bottom surfaces and is deflected by the difference in the air pressures, and this deflection deforms piezoelectric body 1181, causing an electrical signal corresponding to this deformation to be output.

[0070] [Example of Overall Configuration of Measurement Device in First Embodiment] Fig. 2 shows only an outline of the measurement device 100 to give an overview of this embodiment, but components that process the output signal of the differential pressure sensor 110 (more specifically, the output signal of the piezoelectric element 118) are added to the measurement device 100 in Fig. 2. Fig. 18 shows an example of the overall configuration of the measurement device 100.

[0071] In this embodiment, the device includes a measuring section 210 including a first pad 150 and a second pad 160, and a sensor unit 220 including a differential pressure sensor 110, a circuit component 1242 such as an analog amplifier, and a signal processing device 2210.

[0072] In this example, a first pad 150 and a second pad 160 made of plastic (e.g., polyethylene) and having the same size (width 40 mm, depth 40 mm, thickness 5 mm) are used, and rubber tubes of the same size (inner diameter φ2 mm) are used to connect tube 130 to first pad 150 and tube 140 to second pad 160.

[0073] The measuring section 210 and the sensor unit 220 can be installed in separate locations. The circuit component 1242 may be provided inside the differential pressure sensor 110 as shown in FIG. 16, or may be included in the signal processing device 2210.

[0074] The signal processing device 2210 includes, for example, an amplifier 2211 with adjustable gain, a processing unit 2212, a memory 2213, and an output unit 2214. The processing unit 2212 sets the gain of the amplifier 2211 as necessary. The processing unit 2212 also digitizes the output of the amplifier 2211 and executes a pre-prepared program to perform signal processing such as band-pass filtering and FFT (Fast Fourier Transformation). Predetermined programs and measurement data are stored in the memory 2213. The processing results of the processing unit 2212 are output to an external device via the output unit 2214. The output unit 2214 may be a display device or a printing device in some cases, or may be a wired or wireless communication device in some cases that communicates with an external device.

[0075] In this example, signal processing is performed in signal processing device 2210, but the output signal of circuit component 1242 may be digitized and output to another device, and the other device may perform signal processing. Furthermore, when processing vital signals, a bandpass filter is configured to pass the frequency band of the vital signals, but when processing other signals, other filters may be configured.

[0076] [Example of pad arrangement in the first embodiment] By adopting the first pad 150 and the second pad 160 and combining them with the differential pressure sensor 110, the problem of signal saturation is solved, but by adjusting the pressure transmitted to the first space 112 and the second space 114, i.e., by optimizing the positioning of the first pad 150 and the second pad 160, vital signals can be detected with greater sensitivity.

[0077] As mentioned above, in order to cancel the external noise component, it is preferable to simultaneously transmit the same pressure to the first space 112 and the second space 114. In other words, it is preferable to apply the same noise component to the first pad 150 and the second pad 160, and transmit the pressure of the vital component to one of them.

[0078] In particular, road noise generated while a vehicle such as an automobile is moving can be transmitted directly to the two pads, or the road noise can cause the human body to vibrate (i.e., cause body movement) and be transmitted to the pads. To deal with such cases, it is important to make the body movement applied to the pads uniform and to keep the load (i.e., the weight of the human body) that transmits road noise to the pads stable.

[0079] On the other hand, if the pads are too far apart, differences in the amount of body movement and variations in load will occur, resulting in incomplete cancellation of noise components, making the difference in noise components larger than the vital components and causing signal saturation.

[0080] When the shape, volume (internal volume) and tube length of the two pads are the same, experiments have shown that it is better to place the first pad 150 and the second pad 160 close to each other.

[0081] Before describing the specific arrangement, the axial directions will be defined as shown in Fig. 19. Fig. 19 is a perspective view of an automobile seat, in which the vertical direction of the perspective view is defined as the Z axis, an XY plane is defined relative to a certain plane within seat cushion 4000, the direction facing seat back 4500 is defined as the Y axis, and the direction perpendicular to that is defined as the X axis.

[0082] When the first pad 150 and the second pad 160 are arranged close to each other, there are two cases: a first case in which the pads are arranged side by side in the X-axis direction as shown in FIGS. 19 and 20 , and a second case in which the pads are arranged close to each other by overlapping in the Z-axis direction as shown in FIGS. 21 and 22 . FIG. 21 shows a case in which the first pad 150 and the second pad 160 are arranged so as to be in contact with each other, while FIG. 22 shows a case in which the first pad 150 and the second pad 160 are arranged so as to be spaced apart in the Z-axis direction. In both the cases shown in FIGS. 21 and 22 , the pads are arranged so as to completely overlap in the Z-axis direction, but a slight misalignment is acceptable. In other words, it is effective to arrange the pads so that their approximate centers overlap.

[0083] Experimental results show that the second case stacked on the Z axis is preferable to the first case aligned in the X direction, because there are cases where the sitting position is off and the load of the human body 5000 (e.g., legs) on the pad is different.

[0084] It is even more preferable to have the two pads' outer shapes and centers aligned. This allows for a closer approximation of the noise entering the two pads, making it easier to cancel them out. For example, considering the vehicle's speed and the road's undulations, road noise waveforms vary depending on the location on the road. Therefore, to ensure that essentially the same noise is received by the two pads, it is more accurate to have the outer shapes and centers aligned. In this regard, it is even better to have the two pads provided with grooves to regulate their positions, as shown in Figure 33. When the pad is rectangular in plan view, as shown in Figure 22, a pair of opposing sides are regulated, but grooves may also be provided to regulate the two opposing sides.

[0085] On the other hand, when the pad has a circular or elliptical shape in plan view, recesses may be provided to restrict movement in the X and Y directions.

[0086] On the other hand, in the third case in which the first pad 150 and the second pad 160 are arranged next to each other in the X-axis direction but are spaced apart as shown in FIG. 23, and in the fourth case in which the pads are spaced apart in both the X-axis and Z-axis directions as shown in FIG. 24, it was found that the noise cancellation effect was not obtained and it was difficult to extract vital signals.

[0087] Although not shown, there is also a fifth case in which the elements are arranged close to each other in the Y-axis direction, which is different from FIG. 20, but this is the same as the first case.

[0088] Next, in the case where two pads are closely stacked as shown in FIG. 21, the signals obtained when a certain car is driven at 10 km / h, 30 km / h, and 50 km / h will be explained using FIG. 25 to FIG. 32.

[0089] FIG. 25 shows an example of a bandpass filter output signal measured when traveling at 10 km / h and processed using a bandpass filter that passes 1-3 Hz. Meanwhile, FIG. 26 shows an example of a signal obtained when a pulse wave sensor is attached to a fingertip under the same conditions as FIG. 25. FIG. 25 shows signals of various frequencies superimposed, while FIG. 26 shows a pulse wave repeated at a roughly constant cycle. The vertical axis of both FIG. 25 and FIG. 26 represents the signal amplitude [V], and the horizontal axis represents time [seconds]. To make the figures easier to understand, the DC component is retained.

[0090] Figure 27 shows the results of performing an FFT on the signal shown in Figure 26. In the example of Figure 27, pulse wave peak a can be detected at approximately 1.17 Hz, and the other peaks are its harmonics. Meanwhile, Figure 28 shows the results of performing an FFT on the signal shown in Figure 25. It can be seen that in Figure 28 as well, peak b corresponding to peak a can be detected with a certain degree of intensity. However, noise components are present in the area close to peak b. Note that the vertical axis in Figures 27 and 28 represents power, and the horizontal axis represents frequency [Hz].

[0091] FIG. 29 shows an example of a bandpass filter output signal measured when traveling at 30 km / h and processed with a bandpass filter that passes 1-3 Hz. Note that the DC component is retained for clarity. FIG. 29 is a diagram in the same format as FIGS. 25 and 26. Note that the example signal obtained when a pulse wave sensor is attached to a fingertip under these conditions differs slightly from that shown in FIG. 26, but is omitted because it is the same pulse wave that repeats at a roughly constant cycle. Similarly, the FFT results are omitted.

[0092] Figure 30 shows the results of performing an FFT on the signal shown in Figure 29. In the example of Figure 30, it can be seen that peak c, which corresponds to peak a at approximately 1.17 Hz, can be detected as a large peak. Furthermore, since the noise components have shifted to the higher frequency side compared to the case of Figure 28, peak c is easier to detect. Note that Figure 30 is a diagram in the same format as Figures 27 and 28.

[0093] FIG. 31 shows an example of a bandpass filter output signal measured when traveling at 50 km / h and processed using a bandpass filter that passes 1-3 Hz. Note that the DC component is retained for clarity. FIG. 31 is a diagram in the same format as FIGS. 25 and 26. Note that the example signal obtained when a pulse wave sensor is attached to a fingertip under these conditions differs slightly from that shown in FIG. 26, but is omitted because it is the same pulse wave that repeats at a roughly constant cycle. Similarly, the FFT results are omitted.

[0094] The results of performing an FFT on the signal shown in Fig. 31 are shown in Fig. 32. In the example of Fig. 32, it can be seen that peak d, which corresponds to peak a at approximately 1.17 Hz, can be detected as a large peak. Furthermore, since the noise components have shifted further to the high frequency side compared to the case of Fig. 28, peak d is easier to detect. Note that Fig. 32 is a diagram in the same format as Figs. 27 and 28.

[0095] This shows that the method is highly effective when two pads are closely stacked as shown in Figure 21. Also, the faster the speed, the more the noise components move to the high frequency side, making them easier to detect.

[0096] While it would be ideal if the noise components could be completely canceled, in reality, noise caused by body movement and road noise occur asynchronously, and are not transmitted to the two pads in the same way, so noise components remain in the differential pressure measured at the same time. However, if most of the noise components can be removed, signal saturation can be avoided, and vital signs can be extracted through signal processing.

[0097] Next, the separation distance between the first pad 150 and the second pad 160 is evaluated.

[0098] Figure 33 shows urethane mat 7000, which is the material of the seat cushion for this evaluation. This urethane mat 7000 was placed on seat cushion 4000 shown in Figure 19 in the axial direction as shown in Figure 33. This urethane mat 7000 has a groove 7100 that matches the width of first pad 150 and second pad 160. Measuring unit 210, which includes first pad 150 and second pad 160, is positioned and fixed in the middle of this groove 7100.

[0099] Normally, the urethane mat 7000 is provided in a regulated position within the foam urethane of the seat cushion.

[0100] Here, three patterns shown in Figures 34 to 36 are evaluated. In the first pattern shown in Figure 34, urethane 7200 is provided as the top layer, with first pad 150 and second pad 160 layered underneath, and the thickness of urethane 7200 is, for example, 7 mm. Note that the layer structure of urethane 7200 and first pad 150 and second pad 160 may also be mounted integrally or separably. As mentioned above, the two pads are the same size, for example, 40 mm wide, 40 mm deep, and 5 mm thick.

[0101] 35, a second pattern is shown in which urethane 7200 is provided as the top layer, with first pad 150 provided underneath, and urethane 7300 as a separation layer provided underneath, with second pad 160 provided underneath. The thickness of urethanes 7200 and 7300 is, for example, 10 mm. The layer structures of urethane 7200, first pad 150, urethane 7300, and second pad 160 may be mounted integrally or separably assembled.

[0102] 36 shows a third pattern in which urethane 7200 is provided as the top layer, with first pad 150 provided underneath, and urethane 7400 as a separation layer provided underneath, with second pad 160 provided underneath. Note that the thickness of urethane 7200 is, for example, 10 mm, and the thickness of urethane 7400 is, for example, 20 mm. The layer structures of urethane 7200, first pad 150, urethane 7400, and second pad 160 may be mounted integrally or separably assembled.

[0103] In addition, the top layer of urethane 7200 may not be present.

[0104] An example of the output of the differential pressure sensor 110 (more specifically, the output of the amplifier 2211) when a vehicle employing the first pattern is traveling at 10 km / h is shown in Figure 37. No signal saturation occurs.

[0105] An example of the output of the differential pressure sensor 110 (more specifically, the output of the amplifier 2211) when a car employing the second pattern is traveling at 10 km / h is shown in Figure 38. There is almost no signal saturation.

[0106] An example of the output of differential pressure sensor 110 (more specifically, the output of amplifier 2211) when a vehicle employing the third pattern is traveling at 10 km / h is shown in Figure 39. There is a slight amount of signal saturation. This is thought to be because the thickness of urethane 7400 in the separation layer has increased, weakening the noise component cancellation effect of the two pads.

[0107] Figure 40 shows an example of measurement when the gain of amplifier 2211 is lowered from that in Figure 39. It can be seen that the signal saturation is eliminated because the gain is lowered.

[0108] Next, the results of processing the signals shown in FIGS. 37 to 40 with a band-pass filter of 1 Hz to 3 Hz by the processing unit 2212, and the results of further FFT processing, are shown in FIGS.

[0109] When the signal in Figure 37 is processed with a bandpass filter, a signal like that shown in Figure 41 is obtained. As can be seen from Figure 41, high frequency components have been removed. Figure 42 shows the results of performing an FFT on the signal in Figure 41. In Figure 42, the peak of the pulse wave can be clearly detected as peak e.

[0110] When the signal in Figure 38 is processed with a bandpass filter, a signal like that shown in Figure 43 is obtained. As can be seen from Figure 43, high frequency components have been removed. Figure 44 also shows the results of performing an FFT on the signal in Figure 43. In Figure 44, the peak of the pulse wave can be clearly detected as peak f.

[0111] When the signal in Figure 39 is processed with a bandpass filter, a signal like that shown in Figure 45 is obtained. In Figure 39, signal saturation occurred relatively frequently, but in Figure 45, the high-frequency components have been removed by the bandpass filter, and there are no large amplitude parts. Figure 46 shows the result of performing an FFT on the signal in Figure 45. In Figure 46, the pulse wave peak can be seen as peak g, but it is lower than in Figures 42 and 44. This is due to signal saturation, but it is still possible to detect the pulse wave.

[0112] When the signal in Figure 40 is processed with a bandpass filter, a signal like that shown in Figure 47 is obtained. In Figure 47, the gain of amplifier 2211 is lower than in the other cases, so the amplitude is smaller even at this stage. Figure 48 shows the result of performing an FFT on the signal in Figure 47. In Figure 48, the peak of the pulse wave can also be seen as peak h. This is larger than peak g shown in Figure 46, and it can be seen that the pulse wave can be detected more easily.

[0113] As described above, in both cases, the pulse wave peak can be detected and separated from the noise component. Note that adjusting the gain of amplifier 2211 allows for more appropriate detection of the pulse wave.

[0114] Furthermore, urethane is just one example, and other foamed resin materials or other materials may also be used as cushioning materials. When measuring unit 210 is used in a seat cushion (seat portion) installed in an automobile or the like, it is better to provide measuring unit 210 in the resin used in the cushion, taking into consideration comfort when sitting. Also, measuring unit 210 may be provided in the same resin used in the cushion, and this may be provided in the seat cushion. It is also better to use the same resin used in the cushion for the cushioning material provided between or on the pads shown in FIG. 34.

[0115] [Regarding Modification A of the First Embodiment] In the explanation so far, it has been assumed that the volumes of the first pad 150 and the second pad 160 are the same, the volumes of the first space 112 and the second space 114 in the differential pressure sensor 110 are also the same, and the inner diameters and lengths of the tubes 130 and 140 are also the same. This configuration is effective when the first pad 150 and the second pad 160 are subjected to the same noise (body movement, road noise, etc.) and, for example, the first pad 150 mainly receives vital signals.

[0116] Furthermore, for example, when two pads are stacked as shown in Figure 21, as shown schematically in Figure 49, if the noise from above (downward arrow) received by the upper first pad 150 and the noise from below (upward arrow) received by the lower second pad 160 are equal, the noise from above will be attenuated and transmitted to the lower second pad 160, and the noise from below will also be attenuated and transmitted to the upper first pad 150 in a similar manner, so that overall noise can be easily canceled out by the differential pressure sensor 110, making it possible to properly extract, for example, the vital signal transmitted to the first pad 150.

[0117] However, if the direction in which noise is applied is only from above or only from below, it cannot be said that a volumetrically symmetrical form above and below the dashed dotted line W, as shown in FIG. 49, is preferable.

[0118] When noise is coming only from above or when noise from above is dominant, it is preferable to have a configuration in which the volume inside the first pad 150b is smaller than the volume inside the second pad 160b, as shown in Figure 50. This ensures that noise from above is transmitted equally from the first pad 150b to the second pad 160b. The pad volume can be adjusted by changing the height, width, length, etc. of the pad. The pad shape can be any shape, such as a rectangular parallelepiped, cylinder, triangular prism, square prism, elliptical cylinder, sphere, or ellipsoid. Furthermore, pads of these shapes can be placed side by side, or the shape can be divided into two by providing a threshold in the middle.

[0119] Also, instead of changing the volume of the pad as in Figure 50, a configuration may be adopted in which the volume inside tube 140b is greater than the volume inside tube 130b, as shown in Figure 51. Even in this case, the same effect as in Figure 50 can be obtained. The volume inside the tube can be adjusted by changing the diameter and length of the tube.

[0120] Furthermore, unlike Figures 50 and 51, the volume ratio within differential pressure sensor 110b is changed as shown in Figure 52. That is, a configuration in which the volume of first space 112b is smaller than the volume of second space 114b may be used. The same effects as those in Figures 50 and 51 can be obtained. Note that while Figure 15 shows a cylindrical differential pressure sensor 110, it may also be shaped as a rectangular parallelepiped, triangular prism, square prism, elliptical cylinder, or the like.

[0121] Conversely, if noise is coming only from below, or if noise from below is dominant, it is preferable to have a configuration in which the volume inside the first pad 150c is greater than the volume inside the second pad 160c, as shown in Figure 53. In this way, noise from below is transmitted equally from the second pad 160c to the first pad 150c. The method for adjusting the pads is the same as that described above.

[0122] Instead of changing the volume of the pad as in Figure 53, it is also possible to adopt a configuration in which the volume inside tube 130c is greater than the volume inside tube 140c, as shown in Figure 54. Even in this case, the same effect as in Figure 53 can be obtained. The method of adjusting the tube is the same as that described above.

[0123] Furthermore, unlike Figures 53 and 54, the volume ratio within the differential pressure sensor 110c may be changed, i.e., the volume of the first space 112c may be greater than the volume of the second space 114c, as shown in Figure 55. This provides the same effects as those shown in Figures 53 and 54.

[0124] [Regarding Modification B in the First Embodiment] Regarding the pad arrangement described above, an example was shown in which a cushioning material such as urethane is placed on top of the first pad 150 provided on the upper side, but in the case of seats in automobiles and the like, the cushioning material such as urethane is covered with cloth, so there are cases in which a cushioning material is not placed on top of the first pad 150 provided on the upper side.

[0125] For example, a simplified cross-sectional view of a seat is shown in Figure 56. In Figure 56, the seat includes a seat back 4500 and a seat cushion 4000. The seat cushion 4000 is covered with a cloth 4100, and its lower portion is fixed to a metal part 6000. The first pad 150 and the second pad 160 are arranged so as to be stacked one on top of the other, with the upper side of the first pad 150 in contact with the cloth 4100 and the lower side in contact with the second pad 160. The first pad 150 and the second pad 160 are connected to a sensor unit 220 via tubes 130 and 140. The sensor unit 220 is connected to cables 4200, including a power cable, and the cables 4200 are drawn out from the seat cushion 4000.

[0126] Not only the first pad 150 and the second pad 160 , but also the tubes 130 and 140 and the sensor unit 220 are embedded in the seat cushion 4000 .

[0127] Here, as explained in FIG. 33, a groove or recess may be provided to regulate the position, and the electrode may be provided therein.

[0128] Furthermore, as shown in the simplified cross-sectional view of Figure 57, the first pad 150 and the second pad 160 may be arranged so that they are stacked with a separating layer in between, or the upper side of the first pad 150 may be arranged so that it contacts the cloth 4100.

[0129] In this case, a layered body of pads with urethane 7400 separating layers provided between the pads may be prepared in advance, and this may be provided in the position regulating portion of the groove or recess.

[0130] In order to suppress the influence of noise, it is preferable that the first pad 150, the second pad 160, the tubes 130 and 140, and the sensor unit 220 are embedded in the seat cushion 4000 so as not to come into contact with the metal part 6000. It is also preferable that the cables 4200 do not come into contact with the metal part 6000.

[0131] The cushioning material inside the seat is, for example, hard urethane, and the case of sensor unit 220 may be embedded in this hard urethane, or the case of sensor unit 220 may be wrapped in another material (for example, soft urethane) and then embedded in the hard urethane.

[0132] The structure inside the case of the sensor unit 220 is also preferably vibration-proof, and the differential pressure sensor 110 and signal processing device 2210 are preferably fixed onto a base substrate placed on vibration-proof pillars made of rubber, resin, etc. Furthermore, the vibration-proof pillars, differential pressure sensor 110, and signal processing device 2210 are fixed with screws or adhesive.

[0133] [Regarding Modification C of the First Embodiment] As shown in FIG. 20 , measurements can be performed by arranging the first pad 150 and the second pad 160 horizontally, or by stacking the first pad 150 and the second pad 160 without fixing them together. However, fixing the first pad 150 and the second pad 160 to each other prevents changes in the relative positions between the pads, enhancing noise cancellation effects. Furthermore, by providing grooves or recesses as shown in FIG. 33 and arranging the first pad 150 and the second pad 160 in the grooves or recesses, changes in the positions of the two pads can be suppressed, regardless of whether they are fixed or not. Instead of using grooves or recesses as shown in FIG. 33 , a space may be formed inside the seat cushion 4000 to fit the sizes of the two pads, as shown in FIG. 58 , to strengthen mechanical fixation.

[0134] This example incorporates further innovations to more efficiently capture vital signals (e.g., pulse waves). More specifically, it prevents the vibrations containing vital signals from being weakened by the energy of the sinking caused by the two pads sinking when a person stands on them (i.e., sits on them).

[0135] For example, FIG. 59 shows a first example for this purpose. Note that the configuration beyond the tubes 130 and 140 is omitted in FIGS. 59 to 68. In the example of FIG. 59, a first pad 150 and a second pad 160 are arranged vertically stacked in a seat cushion 4000, and a plate 4600 having a larger area than the first pad 150 and the second pad 160 is arranged below the second pad 160 to suppress sinking. The plate 4600 is made of plastic or metal and is harder than the first pad 150 and the second pad 160, for example. The plate 4600 may have any shape, such as a circle or a square. By providing such a plate 4600, a fixed end effect is achieved, which prevents sinking below the plate 4600.

[0136] Alternatively, a configuration may be adopted in which the pad has the effect of a plate 4600. An example of such a configuration is shown in FIG. 60. FIG. 60 is a perspective view of an oval pad (first pad 150 in this example) cut at its center. That is, a plate portion 155 for suppressing sinking is added to the outer periphery of first pad 150. First pad 150 and plate portion 155 may be integrally formed, or plate portion 155 may be bonded to first pad 150 afterward. In the latter case, for example, the inner diameter of plate portion 155 may be formed smaller than the outer diameter of first pad 150, and the overlapping portions may be bonded. The outer diameter of plate portion 155 may be any shape, such as circular or rectangular.

[0137] When using such a first pad 150 with a plate portion 155, the arrangement is as shown in Fig. 61, for example. That is, the second pad 160 is arranged under the first pad 150 with the plate portion 155 in the seat cushion 4000. In this way, the plate portion 155 can prevent the first pad 150 and the second pad 160 from sinking.

[0138] 62, a plate portion 165 may be added to the second pad 160. That is, the second pad 160 with the plate portion 165 is placed on top of the first pad 150 in the seat cushion 4000. In this way, the plate portion 165 can also prevent the first pad 150 and the second pad 160 from sinking.

[0139] Furthermore, as shown in FIG. 63, a first pad 150 with a plate portion 155 and a second pad 160 with a plate portion 165 may be arranged in a stacked manner within the seat cushion 4000.

[0140] Furthermore, when the first pad 150 and the second pad 160 are integrally formed, a plate portion may be further added to the integrally formed pad. An example of such a configuration is shown in FIG. 64. FIG. 64 is a perspective view of an oval pad (here, the first pad 150 and the second pad) cut at its center. That is, the first pad 150 and the second pad 160 are integrated and separated by a partition wall 157, and a plate portion 167 for suppressing sinking is added to the outer periphery of the integrally formed pad. Such a plate portion 167 may also be integrally formed with the first pad 150 and the second pad 160, or may be bonded to the integrally formed pad afterward. In the latter case, for example, the inner diameter of the plate portion 167 may be formed smaller than the outer diameter of the integrally formed pad, and the overlapping portions may be bonded. The outer shape of the plate portion 167 may be any shape, such as circular or rectangular.

[0141] When such an integrated pad with plate portion 167 is used, the arrangement is as shown in Fig. 65, for example. That is, the integrated pad with plate portion 167 (first pad 150 and second pad 160) is arranged inside seat cushion 4000. In this way, plate portion 167 can prevent the integrated pad from sinking.

[0142] Furthermore, disturbance vibrations from below may be suppressed by providing a gap in seat cushion 4000. For example, as shown in Fig. 66, first pad 150 and second pad 160 are arranged in a stacked manner within seat cushion 4000, and plate 4600 is arranged below second pad 160, with gap 4700 further provided below plate 4600. Fig. 66 shows an example in which the width of gap 4700 is wider than the widths of first pad 150 and second pad 160, but it is sufficient to provide a gap of an appropriate size for further suppressing disturbance vibrations.

[0143] 67, a gap 4750 may be provided between the second pad 160 and the plate 4600. The width of the gap 4750 is narrower than the widths of the first pad 150 and the second pad 160, but this is to prevent the first pad 150 and the second pad 160 from falling into the gap 4750. Therefore, the size of the gap 4750 is arbitrary as long as the first pad 150 and the second pad 160 can be prevented from falling into the gap 4750 by another method. Even with this pad arrangement, it is possible to suppress disturbances from below.

[0144] In Fig. 66, plate 4600 is provided directly below second pad 160, but a configuration such as that shown in Fig. 68 may be adopted to obtain a damping effect for suppressing disturbance vibrations from further below. That is, a layer of high-resilience resin 4800 may be provided between second pad 160 and plate 4600. In this example, a gap 4700 is also provided below plate 4600, making it possible to suppress disturbance vibrations from further below.

[0145] By adopting such a configuration example, vital signals can be detected more easily.

[0146] Although an example of forming the first pad 150 and the second pad 160 as one unit has been shown, they may be bonded together with an adhesive, with adhesive tape, or wrapped or wrapped with tape or a sheet. Also, the plate portions 155, 165, and 167 may be attached to only a portion of the edge of the pad, rather than to the entire edge.

[0147] [Second embodiment] In the first embodiment, a differential pressure sensor 110 using a piezoelectric element 118 was used to detect weak vital signals such as pulse waves, but when capturing relatively large vibrations such as body movement, the sensitivity is too high, and saturation can occur, making it difficult to distinguish between noise and body movement.

[0148] In this embodiment, in order to detect relatively large vibrations such as body movement, a different differential pressure sensor from that used in the first embodiment is employed. More specifically, a differential pressure sensor such as a conventional capacitance type differential pressure sensor, a piezo-resistance type differential pressure sensor, or a differential transformer type differential pressure sensor may be employed.

[0149] A capacitance-type differential pressure sensor has a first fixed electrode provided, for example, on the first glass, a second fixed electrode provided, for example, on the second glass, and a movable electrode made of, for example, silicon, provided between the first glass and the second glass.When the movable electrode deforms due to the differential pressure between a first pressure applied from the first glass side and a second pressure applied from the second glass side, the change in capacitance that occurs in response to the deformation is converted into an electrical signal.

[0150] A piezo-resistive differential pressure sensor is a differential pressure sensor that utilizes the piezo-resistive effect of gauge resistors formed on the surface of a silicon diaphragm by diffusion or ion implantation, and converts changes in electrical resistance into an electrical signal.

[0151] A differential transformer-type differential pressure sensor uses a differential transformer-based displacement sensor. This displacement sensor has secondary coils on both sides of a primary coil, and a metal core slidably positioned between the primary and secondary coils. When the primary coil is excited with an AC current, an induced voltage is generated in the two secondary coils via the core. When the core is located in the center of the primary coil, the difference in the induced voltages between the two secondary coils is zero. On the other hand, when the core moves toward one of the secondary coils, a difference in the induced voltages between the two secondary coils occurs in proportion to the displacement. Based on this principle, if the core is configured to slide between the primary and secondary coils in response to the differential pressure between the first and second pressures, the differential pressure can be detected as the difference in induced voltages corresponding to the core's displacement. Such differential transformer-type displacement sensors are well known and are disclosed, for example, in Japanese Patent Application Laid-Open Nos. 9-113203 and 6-77065.

[0152] Even if the various differential pressure sensors of this embodiment are employed, relatively large vibrations such as body movement can be measured by adopting the same other configurations as in the first embodiment. That is, road noise and the like imparted to the first pad 150 and the second pad 160 are largely mechanically canceled when detecting the differential pressure, but vibrations such as body movement, which are relatively smaller than road noise and the like, are transmitted mainly from the pad closer to the human body and are detected and output by the various differential pressure sensors. Because road noise and the like are mechanically canceled, the problem of saturation does not occur. Even if some road noise and the like remains, they may be separated using a filter, FFT, or the like as long as the frequency band of the noise is different from the frequency band of body movement and the like.

[0153] For example, Figures 69 and 71 show the measurement results obtained while a vehicle was traveling at 50 km / h using a capacitance differential pressure sensor. In Figures 69 and 71, the vertical axis represents amplitude [V] and the horizontal axis represents time [s]. The pads were arranged as shown in Figure 34, for example.

[0154] FIG. 69 shows the measurement results when, as shown in FIG. 70, the first pad 150 closest to the human body is connected to the capacitance-type differential pressure sensor 1110 via the tube 130, but the second pad 160 and the tube 140 are removed, and the second connection portion 1122 of the capacitance-type differential pressure sensor 1110 is sealed to prevent differential pressure detection. When the sensor is prevented from functioning as a differential pressure sensor in this way, partial saturation occurs, and the sensor is buried in noise, making it impossible to detect body movement. On the other hand, FIG. 71 shows the measurement results when the second pad 160 is connected to the capacitance-type differential pressure sensor 1110 via the tube 140. With this configuration, even when the capacitance-type differential pressure sensor 1110 is used, vibrations due to body movement can be detected in the area indicated by the arrow.

[0155] The various aspects described in the first embodiment can be applied as they are to the arrangement of the first pads 150 and the second pads 160.

[0156] [Application example] When the output unit 2214 included in the signal processing device 2210 is a short-range wireless communication device (e.g., a communication device conforming to a standard such as Bluetooth (registered trademark)) and the measuring device 100 is implemented in a vehicle such as an automobile, as shown schematically in FIG. 72, the measurement results of the measuring device may be transmitted from the signal processing device 2210 included in the sensor unit 220 to a mobile terminal 8000 such as a smartphone, to a car navigation system 8100, or to another vehicle-mounted unit 8200.

[0157] The mobile terminal 8000, such as a smartphone, may display the measurement results or further analysis results to provide the user with information such as their health condition. Similarly, the car navigation system 8100 may display the measurement results or further analysis results. Furthermore, the in-vehicle unit 8200 may display the measurement results or further analysis results and control the vehicle based on the results. The mobile terminal 8000 may be a wearable device such as a smart watch or smart glasses.

[0158] 72 shows an example in which the measurement results are transmitted to another device via wireless communication, but the sensor unit 220 may be connected via a wired connection to the car navigation system 8100 or the in-vehicle unit 8200. In some cases, a USB (Universal Serial Bus) connector or the like may be provided on the sensor unit 220, so that the sensor unit 220 can be connected to a mobile terminal 8000 such as a smartphone via a USB cable.

[0159] Furthermore, instead of embedding the measuring device 100 in the seat cushion 4000, it may be mounted in a separate cushion placed on top of the seat cushion 4000. In this way, even if the cushion is attached later, it will be possible to perform measurements using the measuring device 100 according to this embodiment. In this case, a rechargeable battery may be built into the cushion and charged to supply power to the measuring device 100, or power may be supplied from the automobile via a cable or the like. Measurement results may be output wirelessly or via a wired connection.

[0160] Furthermore, the device can be mounted not only on car seats but also on seats for wheelchairs and other devices. It can also be applied to mobile beds and the like. If the device is mounted inside a movable cushion rather than the fixed seat cushion 4000 described above, it can be used in a variety of situations. Furthermore, while it has been shown that it is possible to detect vital signs and body movements, it can also be applied to monitoring weak low-frequency vibrations in structures such as bridges and buildings, and weak low-frequency vibrations from conveyors, motors, and the like used in production facilities, by using a differential pressure sensor and first and second pads (i.e., air mattresses) to cancel out large noises and obtain small signals of interest.

[0161] Although the embodiments of the present invention have been described above, the present invention is not limited to these. For example, the functional configuration examples are merely examples, and even if the device configuration is different, it is sufficient if the same functions can be realized overall. Some of the functions of the processing unit 2212 of the signal processing device 2210 may be realized by a program executed by a microprocessor, or all of them may be implemented by a dedicated circuit.

[0162] Although the above example mainly shows the extraction of vital signals from the soles of the legs, vital signals may be extracted from other parts of the body. In particular, if the first pad 150 and the second pad can be positioned near arteries, it becomes easier to extract vital signals. Also, while the example shows the use of air as the fluid, other gases or liquids may also be used. Furthermore, body movement can be detected from a wider variety of body parts.

[0163] The above-described embodiments disclose at least the following points.

[0164] The measuring device according to the first aspect of this embodiment has (A) a first bag-shaped member that receives a first vibration, (B) a second bag-shaped member that receives a second vibration, and (C) a differential pressure sensor having a first space that communicates with the first bag-shaped member, a second space that communicates with the second bag-shaped member, and a vibration membrane that separates the first space and the second space and has a piezoelectric body formed thereon.

[0165] It is possible to properly measure the differential pressure between the first pressure caused by the first vibration input through the first bag-shaped member and the second pressure caused by the second vibration input through the second bag-shaped member. For example, if the same noise is present in the first pressure and the second pressure, they are canceled by the vibrating membrane, and if the vibration of the object to be measured is present in either bag-shaped member, a signal corresponding to the vibration of the object to be measured is output as an electrical signal by the piezoelectric element. This makes it possible to avoid saturation of the output signal caused by noise.

[0166] The measurement device may further include (D) a first tube connecting the first bag-shaped member and the first space of the differential pressure sensor, and (E) a second tube connecting the second bag-shaped member and the second space of the differential pressure sensor, allowing the differential pressure sensor to be located at a position away from the first and second bag-shaped members.

[0167] The internal volume of the first bag-shaped member and the first space (including the internal volume of the tube if there is a tube) and the internal volume of the second bag-shaped member and the second space (including the internal volume of the tube if there is a tube) may be the same or may be different in some cases.

[0168] Furthermore, the differential pressure sensor described above may further include an amplifier for the output signal of the piezoelectric element, which contributes to the miniaturization of the measuring device.

[0169] Furthermore, in the measuring device, the first bag-shaped member and the second bag-shaped member may be positioned so as to overlap each other. This is a more preferable configuration for measuring vital signals. In other words, it is effective in canceling noise. If the bag-shaped members are flat, they are more likely to receive vibrations, and if they are overlapped, they can be placed in a smaller space. Furthermore, if they are installed on a seat cushion or the like, it is easy to ensure that the same load is applied to both.

[0170] Furthermore, when the bag-shaped members are arranged one on top of the other, a separator may be provided between the first bag-shaped member and the second bag-shaped member to provide a predetermined separation distance, in order to adjust the separation distance according to the environment.

[0171] Furthermore, when the bag-shaped members are arranged one on top of the other, the first bag-shaped member may be arranged closer to the object to be measured than the second bag-shaped member, in order to receive more vital signals from the first bag-shaped member.

[0172] The measuring device may further include (F) a signal processing unit that processes signals from the differential pressure sensor, and (G) an output unit that outputs the output signal of the signal processing unit to an external device. With this configuration, it becomes possible to appropriately extract minute signals such as vital signs.

[0173] Instead of a differential pressure sensor including a piezoelectric body, a differential pressure sensor including a MEMS (Micro Electro Mechanical Systems) may be used.

[0174] The vehicle seat according to this embodiment includes (A) a first bag-shaped member (which may be a fluid-filled body containing a fluid), a second bag-shaped member (which may be a fluid-filled body containing a fluid), a first space communicating with the first bag-shaped member, a second space communicating with the second bag-shaped member, and a differential pressure sensor having a vibration membrane separating the first space from the second space and having a piezoelectric body formed thereon. The first bag-shaped member is then placed inside a portion of the vehicle seat that will come into contact with a predetermined part of the human body, overlapping the second bag-shaped member so that the first bag-shaped member is closer to the predetermined part of the human body than the second bag-shaped member. This arrangement allows the vital signs of a person seated in the vehicle seat to be properly extracted.

[0175] The portion against which the predetermined part of the human body comes into contact may be the seat portion of the vehicle seat. However, it may be another portion. Also, the first bag-shaped member and the second bag-shaped member may be stacked and provided in the resin material of the seat portion. Furthermore, the portion against which the predetermined part of the human body comes into contact may be made of foamed resin.

[0176] The measuring device according to the second aspect of this embodiment includes (A) a first air mattress that receives a first vibration, (B) a second air mattress that is stacked so that its center coincides with the center of the first air mattress when viewed in a plane and that receives a second vibration, (C) a first space that communicates with the first air mattress and a second space that communicates with the second air mattress, and (D) a sensor that detects vibrations in the first space and the second space.

[0177] It is also possible to provide a laminate including the first air mat and the second air mat in the groove or recess that regulates the positions of the first air mat and the second air mat.

[0178] In this case, the groove or recess may be provided in the seat cushion or in the material of the seat cushion. The sensor may be a pressure sensor or a differential pressure sensor. Furthermore, the first and second air mats may be stacked in close contact with each other.

[0179] Furthermore, a measuring device according to a third aspect of this embodiment includes a housing having an inner wall that defines a space, a vibration membrane that divides the space into a first space and a second space and vibrates toward the first space and the second space in response to a first vibration transmitted to the first space and a second vibration transmitted to the second space, and a differential pressure sensor having a piezoelectric body provided on one side of the vibration membrane.

[0180] The vibrating membrane may be made of metal.

[0181] The housing may have a protrusion provided on the inner wall thereof, a vibration membrane provided so as to overlap the protrusion, and an electrical connection provided on the vibration membrane at a portion overlapping the protrusion or in the vicinity thereof.

[0182] The housing is formed by resin molding, and a removable top cover is fitted to the top of the first space of the housing, and the electrical connection part of the vibration membrane may be provided on the surface of the vibration membrane on the top cover side.

[0183] A third space may be provided below the second space, and circuit components of an analog amplifier may be provided therein.

[0184] Such a configuration is not limited to the matters described in the embodiment, and may be implemented in other configurations that provide substantially the same effects.

Claims

1. a first bag-shaped member that receives the first vibration; a second bag-shaped member that receives the second vibration; a differential pressure sensor including a first space communicating with the first bag-shaped member, a second space communicating with the second bag-shaped member, and an element for detecting a differential pressure between a first pressure transmitted from the inside of the first bag-shaped member to the first space and a second pressure transmitted from the inside of the second bag-shaped member to the second space; a signal processing unit that processes the signal from the differential pressure sensor to extract a vital signal of the human body; A measuring device having:

2. a first tube connecting the first bag-shaped member and the first space of the differential pressure sensor; a second tube connecting the second bag-shaped member and the second space of the differential pressure sensor; The measurement device of claim 1 further comprising:

3. The first bag-shaped member and the second bag-shaped member are positioned so as to be closely or separately stacked. The measuring device according to claim 1 or 2.

4. The first bag-shaped member and the second bag-shaped member are arranged in close contact with each other or spaced apart from each other. The measuring device according to claim 1 or 2.

5. the first bag-shaped member and the second bag-shaped member are flat, The first bag-shaped member and the second bag-shaped member are integrated together such that the central portions of the flat plates are closely or separately overlapped. The measuring device according to claim 1 or 2.

6. A plate portion is provided on at least a part of the edge of at least one of the first bag-shaped member and the second bag-shaped member.

6. The measuring device according to claim 1.

7. the first bag-shaped member and the second bag-shaped member are integrated, An outwardly extending plate portion is added to at least a portion of the outer periphery of the integrated first and second bag-shaped members.

6. The measuring device according to claim 1.

8. Resin is added to the first bag-shaped member and the second bag-shaped member.

8. The measuring device according to claim 1.

9. A resin is added so as to cover at least one surface of the first bag-shaped member and the second bag-shaped member.

8. The measuring device according to claim 1.

10. The differential pressure sensor Capacitive differential pressure sensor, piezo-resistive differential pressure sensor, or differential transformer differential pressure sensor 10. The measuring device according to claim 1.

11. The differential pressure sensor The differential pressure sensor further includes a vibration membrane that separates the first space from the second space and has a piezoelectric body formed thereon.

10. The measuring device according to claim 1.

12. The first bag-shaped member is disposed closer to the human body, which is the object to be measured, than the second bag-shaped member.

12. The measuring device according to claim 1.

13. an output unit that outputs the output signal of the signal processing unit to an external device; 13. The measurement device according to claim 1, further comprising:

14. a first bag-shaped member; a second bag-shaped member; a differential pressure sensor including a first space communicating with the first bag-shaped member, a second space communicating with the second bag-shaped member, and an element for detecting a differential pressure between a first pressure transmitted from the inside of the first bag-shaped member to the first space and a second pressure transmitted from the inside of the second bag-shaped member to the second space; a signal processing unit that processes the signal from the differential pressure sensor to extract a vital signal of the human body; and The first bag-shaped member is disposed inside the portion that comes into contact with the predetermined part of the human body so as to be closer to the predetermined part of the human body than the second bag-shaped member. Vehicle seat.

15. The part that the predetermined part of the human body comes into contact with is the seat part or the back part.

15. The vehicle seat according to claim 14.

16. 16. The vehicle seat according to claim 14, wherein the first bag-shaped member and the second bag-shaped member are stacked together, either closely or spaced apart, and are provided in a resin material in a portion that comes into contact with a predetermined part of the human body.

17. A member including the first bag-shaped member and the second bag-shaped member is disposed in a groove or a recess that regulates the positions of the first bag-shaped member and the second bag-shaped member.

16. The vehicle seat according to claim 14 or 15.

18. 18. The vehicle seat according to claim 14, wherein a plate having an area larger than that of the second bag-shaped member is provided below the second bag-shaped member.

19. A gap is provided below the plate 19. The vehicle seat of claim 18.

20. A gap is provided between the second bag-shaped member and the plate.

19. The vehicle seat of claim 18.

21. 21. The vehicle seat according to claim 14, wherein the portion against which the predetermined part of the human body comes into contact is made of a foam resin.

22. a first bag-shaped member that receives the first vibration; a second bag-shaped member that receives the second vibration; a differential pressure sensor including a first space communicating with the first bag-shaped member, a second space communicating with the second bag-shaped member, and a vibration membrane separating the first space from the second space and having a piezoelectric body formed thereon; a signal processing unit that processes the signal from the differential pressure sensor to extract a vital signal of the human body; A measuring device having:

23. a first tube connecting the first bag-shaped member and a first space of the differential pressure sensor; a second tube connecting the second bag-shaped member and the second space of the differential pressure sensor; 23. The measurement device of claim 22, further comprising:

24. The differential pressure sensor further includes an amplifier for the output signal of the piezoelectric element.

24. The measuring device according to claim 22 or 23.

25. 25. The measuring device according to claim 22, wherein the first bag-shaped member and the second bag-shaped member are positioned so as to be overlapped with each other.

26. The first bag-shaped member is disposed closer to the human body, which is the object to be measured, than the second bag-shaped member.

26. The measuring device according to claim 24 or 25.

27. an output unit that outputs the output signal of the signal processing unit to an external device; 27. The measurement device of any one of claims 22 to 26, further comprising:

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