Seat

Abstract

To stably measure a cardioballistic value of a seating person.SOLUTION: A seat comprises: a pressure sensor (21) which detects a pressure value of pressure applied from the body of a seating person; a piezoelectric sensor (22) which senses a cardioballistic value of the seating person; an action part (26) which pushes out, when the pressure value is within a prescribed range, the piezoelectric sensor (22) in a direction of the body side of the seating person.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a seat provided in a vehicle. [Background technology]

[0002] Patent Document 1 discloses a seat that can stably measure the biological signals of seated occupants even when there are differences in physique between seated occupants, and can improve the accuracy of awakening determination. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-185777 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology such as that of Patent Document 1 has a problem in that it cannot adequately deal with differences in elastic modulus due to the amount of subcutaneous fat in the body part facing the sensor.

[0005] One aspect of the present disclosure has been made in consideration of the above-mentioned problems, and aims to stably measure the ballistocardiogram of a seated person. [Means for solving the problem]

[0006] In order to solve the above problems, the seat according to aspect 1 of the present disclosure includes a pressure sensor that detects the pressure value of the pressure applied by the body of the seated person, a piezoelectric sensor that senses the ballistocardiogram of the seated person, and an operating unit that pushes the piezoelectric sensor toward the body of the seated person when the pressure value is within a predetermined range.

[0007] According to the above configuration, the pressure sensor is used to determine whether the piezoelectric sensor is sufficiently pressed against the body of the seated occupant, and if the pressure is insufficient, the piezoelectric sensor can be controlled to be pushed toward the body, thereby enabling stable measurement of the ballistocardiogram of the seated occupant.

[0008] In the seat according to aspect 2 of the present disclosure, in the above-mentioned aspect 1, the pressure sensor and the piezoelectric sensor are respectively arranged at approximately symmetrical positions in the horizontal direction of the seat, and the operating unit pushes the pressure sensor and the piezoelectric sensor toward the body of the seated occupant to approximately the same extent.

[0009] According to the above configuration, the pressure sensor and the piezoelectric sensor are pushed out at positions that are approximately symmetrical in the horizontal direction of the seat, so that force is applied equally to the left and right sides of the seated occupant's body, thereby preventing discomfort when sitting.

[0010] A seat according to a third aspect of the present disclosure is the seat of the first or second aspect, wherein the operating portion includes a bag that expands when a fluid is injected thereinto and pushes out the piezoelectric sensor.

[0011] According to the above configuration, a configuration can be realized in which the piezoelectric sensor is pushed in the direction of the body of the seated occupant with a relatively simple configuration using the bag.

[0012] A seat according to a fourth aspect of the present disclosure is the seat of the third aspect, wherein the operating portion includes a plurality of the bags that overlap each other.

[0013] The above configuration contributes to improving the durability of the bag.

[0014] In the seat according to aspect 5 of the present disclosure, in the above-mentioned aspect 1 or 2, the pressure sensor and the piezoelectric sensor are provided only at positions within the seat corresponding to one of the areas corresponding to the waist, buttocks, and thighs of the seated person, respectively.

[0015] According to the above configuration, the pressure sensor and the piezoelectric sensor are provided only in a narrow range, which contributes to further reducing the manufacturing cost of the seat.

[0016] In the seat according to aspect 6 of the present disclosure, in the above aspect 1 or 2, the controller associated with the seat performs processing to output a signal to notify information regarding the state of the occupant when the sensing result by the piezoelectric sensor satisfies predetermined conditions regarding the ballistocardiogram of the occupant.

[0017] According to the above configuration, for example, when the sensing result indicates that the driver of the mobile body is feeling drowsy, it is possible to control to output a warning by audio output.

[0018] A seat according to a seventh aspect of the present disclosure is a seat provided in a moving body in the first or second aspect.

[0019] According to the above configuration, even when vibrations are generated due to the movement of the moving body, the piezoelectric sensor is pressed against the moving body, so that the ballistocardiogram of the seated person can be measured stably.

[0020] In the seat according to aspect 8 of the present disclosure, in the above-mentioned aspect 7, the controller associated with the seat performs processing related to the movement of the moving body when the sensing results of the piezoelectric sensor satisfy predetermined conditions related to the ballistocardiogram of the seated occupant.

[0021] According to the above configuration, for example, when the sensing result indicates that the driver of the mobile body is in a state where he or she is unable to drive, it is possible to control the mobile body to stop on the shoulder of a road or the like. [Effects of the Invention]

[0022] According to one aspect of the present disclosure, the ballistocardiogram of a seated person can be measured stably. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a perspective view showing an example of the appearance of a seat. [Figure 2] FIG. 2 is a diagram showing an example of a seat surface of a seat. [Figure 3] FIG. 2 is a diagram showing an example of a cross-sectional view of a seat surface of a seat. [Figure 4] 1 shows the relationship between the position of the seat where the pressure sensor is provided and the actual measured value of the pressure applied to the pressure sensor. [Figure 5] 1 shows ballistocardiographic signal waveforms sensed by each of the piezoelectric sensors. [Figure 6] 1 shows the Young's modulus of the buttocks of seated occupants with different body types. [Figure 7] This shows the percentage of estimated accuracy of RRI obtained from the sensing results actually measured with each piezoelectric sensor. [Figure 8] 1 is an example of a distribution diagram for explaining the RRI correct answer rate. [Figure 9] 10 is a flowchart showing the flow of processing executed by a seat. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present disclosure will be described in detail below.

[0025] [1. Seat configuration example] 1 is a perspective view showing an example of the appearance of a seat 1 according to the present disclosure. The seat 1 has a seat cushion 11, a seat back 12, and a headrest 13. The seat cushion 11 forms the seat surface of the seat 1, and the seat back 12 and the headrest 13 form the back surface of the seat 1.

[0026] In the following, the seat 1 is described as being installed in a moving body, but is not limited to this and may be installed in a stationary location such as a building. The moving body is described as being a vehicle, but is not limited to this and may be a ship, an airplane, or the like. The seat 1 is not limited to being installed in a driver's seat, but may be installed in a passenger seat.

[0027] The seat 1 also has a pressure sensor 21 shown in Fig. 2, which will be described later, and a piezoelectric sensor 22 and an operating unit 26, which will be shown in Figs. 2 and 3, which will be described later. Each of two areas 14 on the seat surface of the seat 1 shows an example of the position where the pressure sensor 21, the piezoelectric sensor 22, and the operating unit 26 are arranged when viewed from above the seat surface of the seat 1. These members provided in the seat 1 will be described below.

[0028] FIG. 2 is a diagram showing an example of the seat surface of the seat 1. In the example of FIG. 2, pressure sensor 21 is provided in an area corresponding to the left buttocks of a seated occupant sitting on the seat surface, and piezoelectric sensor 22 is provided in an area corresponding to the right buttocks of the seated occupant. That is, pressure sensor 21 and piezoelectric sensor 22 are provided at approximately symmetrical positions in the horizontal direction (left-right direction) of the seat 1. Note that the positions of pressure sensor 21 and piezoelectric sensor 22 may be reversed. Pressure sensor 21 and piezoelectric sensor 22 are usually covered with a cover for the seat 1. Furthermore, in FIG. 2, a frame 29 surrounding pressure sensor 21 and piezoelectric sensor 22 exemplifies the position where an air bag, described later, is provided.

[0029] The pressure sensor 21 detects the pressure value of the pressure applied by the body of the seated occupant. The piezoelectric sensor 22 senses the ballistocardiogram (BCG) of the seated occupant. The piezoelectric sensor 22 is a sensor that utilizes the piezoelectric effect of a piezoelectric element that generates a voltage when subjected to pressure. The pressure value detected by the piezoelectric sensor 22 and a signal indicating the ballistocardiogram sensed by the piezoelectric sensor 22 are supplied to a controller (control unit) 24 that controls the operation of the operating unit 26.

[0030] Furthermore, the controller 24 associated with the seat 1 measures the heartbeat of the seated person by referring to the sensing result supplied from the piezoelectric sensor 22. Furthermore, the controller 24 determines whether or not the sensing result from the piezoelectric sensor 22 satisfies a predetermined condition related to the ballistocardiogram of the seated person, and when it is determined that the predetermined condition is satisfied, performs processing such as outputting a signal to notify that effect.

[0031] When the pressure value detected by the pressure sensor 21 is within a predetermined range, the operation unit 26 performs a process of pushing the pressure sensor 21 and the piezoelectric sensor 22 toward the body of the seated occupant.

[0032] The operating unit 26 may be configured to push only the piezoelectric sensor 22 toward the body of the seated occupant. More specifically, the air bag described below may be provided only below the piezoelectric sensor 22.

[0033] Fig. 3 is a diagram showing an example of a cross-sectional view of the seat surface of seat 1. In seat 1, an air bladder, which is part of operating unit 26, is provided below piezoelectric sensor 22, i.e., on the side opposite the side where the body of a seated person is positioned. Note that Fig. 3 does not show the mechanism of operating unit 26 that injects air into the air bladder. Furthermore, before air is injected into the air bladder, piezoelectric sensor 22 and the air bladder are arranged inside a recess in the seat surface so that the top surface of piezoelectric sensor 22 forms a substantially flat surface with the seat surface.

[0034] As shown in FIG. 3, when air is injected into the air bag, the air bag expands so as to push the piezoelectric sensor 22 toward the body of the seated occupant.

[0035] An air bag is also provided below pressure sensor 21 in a similar manner. In addition, it is more desirable if the air bag is configured to push pressure sensor 21 and piezoelectric sensor 22 toward the body of the seated occupant to approximately the same extent. Here, a configuration in which pressure sensor 21 and piezoelectric sensor 22 are pushed to approximately the same extent means, for example, a configuration in which approximately the same amount of air is injected into the left and right air bags. The following description will be given assuming that seat 1 has this configuration. Note that the air bags are not limited to a configuration in which there are separate left and right air bags, and pressure sensor 21 and piezoelectric sensor 22 may be arranged above a single air bag.

[0036] 3, two air bags are stacked one above the other, but a configuration in which multiple air bags are stacked is not essential, and a configuration in which three or more air bags are stacked one above the other may also be used. A configuration in which operating unit 26 includes multiple air bags stacked one above the other contributes to improving the durability of the air bags.

[0037] [2. Effect of seats] Next, the effects brought about by the configuration of the seat 1 will be explained in order. Figure 4 shows the relationship between the position of the seat surface where the pressure sensors 21 are provided and the actual measured value of the pressure applied to the pressure sensors 21. The "sensor No." on the horizontal axis of Figure 4 indicates the numbers of the pressure sensors 21 provided at different positions on the seat surface. The pressure sensor 21 of sensor No. 1 is provided behind the knees of the seated person, and the pressure sensor 21 of sensor No. 2 is provided at the thighs of the seated person. The pressure sensor 21 of sensor No. 3 is provided below the buttocks of the seated person, and the pressure sensor 21 of sensor No. 4 is provided above the buttocks of the seated person.

[0038] In the graph of Figure 4, "JF50" indicates that the occupant has a physique that is within 50% of that of a Japanese woman, "JM50" indicates that the occupant has a physique that is within 50% of that of a Japanese man, "AM50" indicates that the occupant has a physique that is within 50% of that of an American man, and "Ave" indicates that the occupant has an average physique of these aforementioned physiques.

[0039] As shown in FIG. 4, the pressure applied to the pressure sensor 21 of sensor No. 3 located below the buttocks was the highest for all seated occupants of any build.

[0040] Fig. 5 shows the signal waveforms of ballistocardiograms sensed by each of the piezoelectric sensors 22 provided at positions approximately symmetrical in the horizontal direction of the seat 1 with respect to the pressure sensor 21 with the aforementioned number. That is, the piezoelectric sensor 22 corresponding to the signal waveform indicated by reference numeral (1) in Fig. 5 is a sensor provided at a position approximately symmetrical to the pressure sensor 21 with sensor No. 1 in Fig. 4. Furthermore, a pressure of the same magnitude as that applied to the pressure sensor 21 with sensor No. 1 is applied to the piezoelectric sensor 22 indicated by reference numeral (1). The same applies to the piezoelectric sensors 22 indicated by reference numerals (2) to (4) in Fig. 5.

[0041] As shown in Fig. 5, the piezoelectric sensor 22 indicated by the symbol (3) to which high pressure was applied detected a signal waveform with a sufficient amplitude, while the other piezoelectric sensors 22 did not detect a signal waveform with a amplitude sufficient for measuring the heart rate. This means that in order for the piezoelectric sensors 22 to perform highly accurate sensing, the body of the seated occupant must be pressed against the piezoelectric sensors 22 with a pressure equal to or greater than a predetermined threshold. Also, the pressure value of 70 g / cm shown in Fig. 4 2 indicates an example of the predetermined threshold value.

[0042] 6 shows the Young's modulus of the buttocks of seated persons sub1 to sub5 with different physiques. Piezoelectric sensor 22 is located near the buttocks when the seated persons are seated. In many cases, the more subcutaneous fat there is, the softer the body surface is, and therefore the lower the Young's modulus, while the more muscular the person is, the harder the body surface is, and therefore the higher the Young's modulus.

[0043] FIG. 7 also shows the percentage of RRI estimation accuracy obtained from the sensing results actually measured by each piezoelectric sensor 22 corresponding to the seated persons sub1 to sub5. The higher the RRI estimation accuracy, the higher the RRI accuracy rate in FIG. 6. It is desirable that the percentage of RRI estimation accuracy is 0.8 or higher. In FIG. 7, "S1_raw" corresponds to the sensing result of the piezoelectric sensor 22 provided at a position closer to the inner side of the seated person's buttocks, and "S2_raw" corresponds to the sensing result of the piezoelectric sensor 22 provided at a position closer to the outer side of the seated person's buttocks.

[0044] The above-mentioned "RRI accuracy rate" will now be explained. FIG. 8 is an example of a distribution diagram for explaining the RRI accuracy rate. The horizontal axis of FIG. 8 indicates the ratio of each RRI to the average value (mean RRI) of ballistocardiogram RRIs over a predetermined period, and the vertical axis indicates the number of times each ratio value was achieved. From another perspective, FIG. 8 shows the distribution of "RRI / mean(RRI)." Here, the denominator "mean(RRI)" means the average value of RRI over a predetermined period, and the numerator "RRI" means the value of each target RRI. Furthermore, the above-mentioned predetermined period is not limited to a specific time and may be, for example, 5 minutes or 30 minutes.

[0045] When the value of the ratio is close to 1, the target RRI value is close to the average value and therefore highly reliable, whereas when the value of the ratio is significantly different from 1, the target RRI value is unreliable. In measuring heart rate, it is possible to improve measurement accuracy by excluding or adjusting RRI values ​​with low reliability.

[0046] The RRI accuracy rate refers to the percentage of RRIs measured over a predetermined period in which the ratio value falls within a predetermined range. Typically, the predetermined range is defined as a certain range with the ratio value of 1 at its center. Also, box 27 in Figure 8 is an example of the predetermined range, and indicates a range in which the ratio value is 0.95 to 1.05.

[0047] For example, in FIG. 8, an RRI accuracy rate of 50% means that the value of the ratio corresponding to 50% of the RRIs measured in a predetermined period falls within the range of frame 27.

[0048] Furthermore, when calculating the heart rate of a seated occupant, if the target RRI value is within the predetermined range, the controller 24 may use the RRI value as is, and if the target RRI is outside the predetermined range, the controller 24 may use the most recently measured RRI value.

[0049] In another embodiment, the ratio value used by the controller 24 when calculating the RRI accuracy rate may be the ratio value of the currently measured RRI to the most recently measured RRI. In this configuration, a distribution diagram corresponding to FIG. 8 shows the distribution of "RRI(k) / RRI(k-1)". Here, the denominator "RRI(k-1)" means the RRI value measured the k-1th time, which is the most recent time after the kth time, and the numerator "RRI(k)" means the RRI value measured the current kth time.

[0050] In addition, the controller 24 may use the current RRI measurement value y(k) and the most recent estimated value x(k-1) as the RRI value used to calculate the heart rate, and use a new estimated value x(k) calculated using the following formula: x(k)=w*y(k)+(1-w)*x(k-1) Here, w is a weighting coefficient according to the variance value in the distribution map, and can take a value of 0≦w≦1. The initial value x(0) on which the estimated value x is based may be calculated by the controller 24, for example, by cepstrum analysis. The controller 24 may reset the initial value x(0) every time the main power supply of the mobile object is turned on, or may reset it at predetermined intervals.

[0051] 7, each rectangle indicates the range of the top 75% to 25% of RRI estimation accuracy, and the horizontal line within the rectangle indicates the median of the RRI estimation accuracy. Furthermore, the lines extending above and below each rectangle indicate the range from the maximum to the minimum of the RRI estimation accuracy.

[0052] As shown in Figs. 6 and 7, the higher the value of Young's modulus on the surface of the seated occupant's body, the higher the RRI estimation accuracy and the RRI accuracy rate.

[0053] As described above, it is desirable to press the body against the piezoelectric sensor 22 with a certain amount of pressure or more, and it is also desirable for the Young's modulus of the body surface to be high. The seat 1 is configured so that the operating unit 26 presses the piezoelectric sensor 22 against the body, so that even if the occupant's physique varies, the seat 1 can compensate for the necessary pressure to compress the body and increase the Young's modulus. This allows for improved accuracy in measuring heart rate without providing pressure sensors 21 and piezoelectric sensors 22 over a wide area of ​​the seat.

[0054] [3. Seat treatment example] Next, we will explain the flow of the process executed by the seat 1. Figure 9 is a flowchart showing the flow of the process in this example.

[0055] In S101, the controller 24 determines whether the pressure sensor 21 detects a pressure value within a predetermined range. Here, the predetermined range is not limited to a specific range and may be, for example, 1 to 70 g / cm. 2 However, the lower limit of the predetermined range is at least a value greater than 0. The unit of pressure defining the predetermined range may be Pa (Pascal), etc.

[0056] When controller 24 determines that pressure sensor 21 has detected the pressure (S101: YES), in S102, controller 24 controls operation unit 26 to inject air into the air bag and push pressure sensor 21 and piezoelectric sensor 22 toward the body of the seated occupant. This causes pressure sensor 21 and piezoelectric sensor 22 to be pressed more firmly against the body of the seated occupant. The amount of air injected into the air bag may be a predetermined amount, or may be an amount corresponding to the pressure value detected by pressure sensor 21.

[0057] On the other hand, when the controller 24 determines that the pressure sensor 21 has detected a pressure greater than the upper limit of the predetermined range (S101: NO), it executes the process of S103 without injecting air into the air bag, because it can be assumed that the piezoelectric sensor 22 is sufficiently pressed against the body of the seated occupant.

[0058] If the pressure value detected by the pressure sensor 21 is smaller than the lower limit of the predetermined range, or if the pressure sensor 21 does not detect any pressure, the controller 24 determines that no one is seated in the seat 1, and continues to make the judgment in S101 until the pressure sensor 21 detects a pressure value equal to or greater than the lower limit of the predetermined range.

[0059] In S103 , the controller 24 acquires the sensing result supplied from the piezoelectric sensor 22 .

[0060] In S104, the controller 24 refers to the acquired sensing results, calculates the RRI of the seated occupant, and measures the heart rate.

[0061] In S105, the controller 24 determines whether the sensing result by the piezoelectric sensor 22 satisfies a predetermined condition related to the ballistocardiogram of the seated occupant. Here, the case where the sensing result by the piezoelectric sensor 22 satisfies the predetermined condition means that the heart rate of the seated occupant calculated based on the sensing result indicates that an abnormality has occurred in the seated occupant. For example, the case where the number of heartbeats of the seated occupant in a predetermined period of time is below a lower limit or above an upper limit, or the case where the number of heartbeats has changed by more than a reference value.

[0062] When the controller 24 determines that the sensing result by the piezoelectric sensor 22 satisfies the predetermined condition (S105: YES), the controller 24 performs predetermined processing such as notifying the seated occupant of the fact in S106. Here, the controller 24 may perform the following exemplary processing as the predetermined processing, which involves outputting a signal for notifying information regarding the state of the seated occupant. - Processing to output audio, video, light or text to notify the seated person that they are experiencing drowsiness, excitement or fatigue Processing to output a control signal and operate the seat 1 or other moving parts of the vehicle in order to notify the seat occupant that drowsiness, excitement, fatigue, etc. is occurring - Processing to send information indicating that an abnormality has occurred to a seated person to a specified contact point via radio communication, etc. Furthermore, the controller 24 may perform the following exemplary process related to the movement of the moving object as the predetermined process in S106. - Processing to stop a moving object on the shoulder of a road, etc. -Processing to reduce the speed of moving objects - Processing to move a mobile object to a designated location such as a hospital or home In addition, when predetermined conditions regarding the ballistocardiogram of the seated person are satisfied, the controller 24 may perform, as the predetermined processing, both the above-mentioned processing of outputting a signal to notify information regarding the state of the seated person and the above-mentioned processing regarding the movement of the moving body.

[0063] [4. Modifications] The configuration of operating unit 26 is not limited to a configuration in which air is injected into an air bag, but may be a configuration in which a fluid other than air is injected into the bag. Here, the fluid may be a gas other than air, a liquid, or a powder or granular material such as a large number of beads. The shape of the bag is also not limited.

[0064] Furthermore, the configuration of the operating unit 26 is not limited to a configuration in which a fluid is injected into a bag, but may be a configuration in which, for example, an actuator or a spring is used to push the piezoelectric sensor 22, etc., toward the body of the seated occupant. In this case, the configuration in which the pressure sensor 21 and the piezoelectric sensor 22 are pushed to approximately the same extent means, for example, that the pressure sensor 21 and the piezoelectric sensor 22 are pushed by approximately the same distance or by approximately the same force.

[0065] Furthermore, the pressure sensor 21 and the piezoelectric sensor 22 are not limited to being provided on the seat surface of the seat 1, but may be provided on the back surface, or on both the seat surface and the back surface. From another perspective, in the description of the seat surface of the seat 1 according to the present disclosure, the "seat surface" may be read as the "back surface" or "seat surface or back surface." Note that the seat 1 does not necessarily have to have both a seat surface and a back surface, and may have only one of them. Furthermore, a bed or mattress, etc., that is provided with the pressure sensor 21 and the piezoelectric sensor 22, similar to the seat 1, is also included in the present disclosure.

[0066] In one embodiment, the pressure sensor 21 and the piezoelectric sensor 22 may be provided only in positions corresponding to any one of the areas corresponding to the lower back, buttocks, and thighs of the seated person within the area of ​​the seat 1. According to this configuration, providing the pressure sensor 21 and the piezoelectric sensor 22 only in a narrow area contributes to further reducing the manufacturing cost of the seat 1.

[0067] [5. Software implementation example] The functions of the controller 24 (hereinafter referred to as the "device") provided in the moving body of the present disclosure can be realized by a program for causing a computer to function as the device, and a program for causing a computer to function as each control block of the device.

[0068] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0069] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0070] In addition, some or all of the functions of each of the control blocks can be realized by logic circuits. For example, integrated circuits in which logic circuits that function as each of the control blocks are formed are also included in the scope of the present disclosure. In addition, the functions of each of the control blocks can also be realized by, for example, a quantum computer.

[0071] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0072] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0073] 1 seat 21 Pressure Sensor 22 Piezoelectric Sensor 24 Controller 26 Operating unit

Claims

1. a pressure sensor that detects a pressure value applied by the body of a seated occupant; a piezoelectric sensor for sensing ballistocardiogram of the seated occupant; an operating unit that pushes the piezoelectric sensor toward the body of the seated occupant when the pressure value is within a predetermined range; A seat equipped with:

2. the pressure sensor and the piezoelectric sensor are provided at positions approximately symmetrical to each other in a horizontal direction of the seat, The operating unit The seat according to claim 1 , wherein the pressure sensor and the piezoelectric sensor are pushed toward the body of the seated occupant to approximately the same extent.

3. 3. The seat according to claim 1, wherein the operating portion includes a bag that expands when a fluid is injected thereinto and pushes out the piezoelectric sensor.

4. The seat according to claim 3 , wherein the active portion comprises a plurality of the bags overlapping each other.

5. The pressure sensor and the piezoelectric sensor are The seat according to claim 1 or 2, wherein the seat cover is provided only at a position corresponding to one of the areas corresponding to the waist, buttocks, and thighs of the seated person, respectively.

6. Further comprising a controller; 3. The seat according to claim 1, wherein when the sensing result by the piezoelectric sensor satisfies a predetermined condition regarding the ballistocardiogram of the seated occupant, a signal is output to notify information regarding the state of the seated occupant.

7. 3. The seat according to claim 1, wherein the seat is provided on a moving body.

8. Further comprising a controller; The seat according to claim 7 , wherein when the sensing result of the piezoelectric sensor satisfies a predetermined condition related to the ballistocardiogram of the seated occupant, processing related to the movement of the moving object is performed.

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