Vehicle seats

Abstract

To provide a vehicle seat that maintains a state of alertness without causing discomfort to the occupant. [Solution] A vehicle seat 1 including a seat cushion 11 and a seat back 12 has a pair of stimulating parts 14 provided on the left and right sides of the seat cushion 11 along the width direction of the vehicle and stimulating the occupant, and a control unit 15 that controls the pair of left and right stimulating parts 14, the control unit 15 controlling the pair of left and right stimulating parts 14 so that the left and right stimulating parts 14 repeatedly apply and remove stimulation alternately on the left and right sides.

Description

Technical Field

[0001] The present invention relates to a vehicle seat.

Background Art

[0002] As this type of vehicle seat, there is known a vehicle seat including a seat cushion, a seat back provided with a pressure-receiving member that supports the back of an occupant, a respiration sensor, an actuator arranged so as to be able to change at least the orientation of the pressure-receiving member left and right, and a control device that controls the actuator. When drowsiness of a driver is detected based on a signal from the respiration sensor, the actuator is driven to change the orientation of the pressure-receiving member left and right (see Patent Document 1). In this conventional technology, when drowsiness of the driver is detected, the actuator is driven to change the orientation of the central portion of the seat back, so that the upper body of the driver is swayed left and right, thereby effectively awakening the driver.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-mentioned conventional technology, although the driver maintains an awake state, the upper body is swayed left and right, so there is a problem of giving the driver a sense of discomfort.

[0005] The problem to be solved by the present invention is to provide a vehicle seat that maintains an awake state without giving a sense of discomfort to the seated person.

Means for Solving the Problems

[0006] The present invention solves the above problem by providing a pair of stimulating parts on the seat cushion of a vehicle seat, which are aligned with the width direction of the vehicle, and by having the pair of stimulating members alternately apply and remove stimulation on the left and right sides. [Effects of the Invention]

[0007] According to the present invention, it is possible to maintain an alert state without causing discomfort to the seated person. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing a vehicle seat according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view along the line II-II in Figure 1. [Figure 3] This graph shows an example of controlling a vehicle seat according to one embodiment of the present invention. [Figure 4] This is a front view showing the pelvis and spine to illustrate the function of a vehicle seat according to one embodiment of the present invention. [Figure 5] This graph shows the effect (subjective evaluation of alertness) of a vehicle seat according to one embodiment of the present invention. [Figure 6] This graph shows the effect of a vehicle seat according to one embodiment of the present invention (evaluation of alertness level by facial expression analysis). [Figure 7] This graph shows the effect (number of blinks) of a vehicle seat according to one embodiment of the present invention. [Figure 8] This is a graph showing the effect (physical fatigue index) of a vehicle seat according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] Hereinafter, examples of embodiments for carrying out the present invention will be described with reference to the drawings. Figure 1 is a configuration diagram showing a vehicle seat 1 according to one embodiment of the present invention, and Figure 2 is a cross-sectional view along the line II-II in Figure 1. Figure 2 is a cross-sectional view of the seat cushion 11 cut in the direction of the arrow II, along a vertical plane containing the cutting line (dotted line) in Figure 1. The vehicle seat 1 of this embodiment is a seat that wakes up the occupant without causing discomfort or maintains an occupant in an awake state without causing discomfort. In the embodiments described below, the present invention will be explained by giving examples of its application to seats in private cars and other passenger cars, as well as buses, trucks and other commercial vehicles, but it can also be applied to seats in ships or aircraft.

[0010] The vehicle seat 1 of this embodiment comprises a seat cushion 11 that primarily contacts the buttocks H of the sitter, a seat back 12 that primarily contacts the back of the sitter, and a headrest 13 that primarily contacts the back of the sitter's head. Although not shown in the figures, the seat cushion 11 and the seat back 12 are each constructed by covering a frame as a structural element with a pad 111 made of cushioning material such as urethane foam and a surface material 112 made of synthetic leather or fabric. The lower part of the frame of the seat back 12 is connected to the rear part of the frame of the seat cushion 11 via a reclining mechanism. As a result, the seat back 12 can be tilted relative to the seat cushion 11 by the reclining mechanism.

[0011] Furthermore, the vehicle seat 1 of this embodiment includes a stimulating unit 14 that provides stimulation to the occupant, and a control unit 15 that controls the stimulating unit 14.

[0012] The stimulator 14 of this embodiment is composed of a pair of air bladders 14R and 14L provided on the seat cushion 11, a pump 141 for supplying and stopping air to the air bladders 14R and 14L, an air pipe 142 connecting the air bladders 14R and 14L to the pump 141, and a pair of valves 143 and 144 provided on the air pipe 142.

[0013] Figure 2 is a cross-sectional view along the line II-II in Figure 1, showing the pad 111 made of cushioning material such as urethane foam and the surface material 112 made of synthetic leather or fabric that constitute the seat cushion 11. In this embodiment, the air bladders 14R and 14L are provided in pairs on the left and right sides along the width direction of the vehicle, at the rear of the seat cushion 11 in the vehicle's longitudinal direction, at positions corresponding to the bones of the seated person's buttocks H (for example, the ischial tuberosity). The pair of left and right air bladders 14R and 14L are interposed between the pad 111 and the surface material 112, respectively, and are capable of expanding and contracting toward the seated person's buttocks.

[0014] As shown in Figure 1, one end of an air pipe 142 is airtightly connected to each of the left and right pairs of air bags 14R and 14L, and the other end of the air pipe 142 is connected to the discharge port of the pump 141 after merging into a single air pipe 142. Valves 143 and 144 are provided on each of the two branched air pipes 142. Each of the valves 143 and 144 in this embodiment is, for example, a three-way valve with a drain function, and is rotatable to an open position that connects the pump 141 to the air bags 14R and 14L, a closed position that blocks the pump 141 from connecting the air bags 14R and 14L, and a drain position that blocks the supply of air from the pump 141 and exhausts the air supplied to the air bags 14R and 14L.

[0015] When the pump 141 is driven and valves 143 and 144 are rotated to the open position, air is supplied to the air bags 14R and 14L via the air pipe 142, causing them to inflate. If the valves 143 and 144 are rotated to the closed position while the pump 141 is still driven, the air bags 14R and 14L remain inflated and the pressure is maintained at a constant level. On the other hand, if the valves 143 and 144 are rotated to the drain position while the pump 141 is still driven, the air in the air bags 14R and 14L is exhausted from the drain ports of valves 143 and 144, causing them to deflate. The pump 141 may be left running, but it may be stopped if air supply to the air bags 14R and 14L is not required.

[0016] The rotational positions of valves 143 and 144 are driven and controlled, for example, by an actuator, and the actuator is controlled by a command signal from control unit 15. Also, by controlling the driving speed of the actuator, the rotational speed of valves 143 and 144 can be controlled. For example, if it is desired to increase the time for supplying air to air bags 14R and 14L to inflate them, the rotational speed of valves 143 and 144 can be decreased. Conversely, if it is desired to decrease the time for inflation, the rotational speed of valves 143 and 144 can be increased. Similarly, if it is desired to increase the time for exhausting air from air bags 14R and 14L to deflate them, the rotational speed of valves 143 and 144 can be decreased. Conversely, if it is desired to decrease the time for exhausting air and deflating, the rotational speed of valves 143 and 144 can be increased. Note that the specific control method for the pair of left and right stimulation units 14 will be described later.

[0017] Also, control unit 15 of the present embodiment is composed of a computer having a CPU, ROM, and RAM, and controls pump 141 and valves 143 and 144 included in stimulation unit 14 according to a program installed in the ROM.

[0018] FIG. 3 is a graph showing an example of control of vehicle seat 1 according to an embodiment of the present invention. In FIG. 3, the vertical axis represents the internal pressure of air bags 14R and 14L, and the horizontal axis represents time. Also, in FIG. 3, the solid pressure diagram represents the internal pressure of the right air bag 14R among the pair of left and right air bags 14R and 14L, and the broken-line pressure diagram represents the internal pressure of the left air bag 14L among the pair of left and right air bags 14R and 14L.

[0019] Control unit 15 of the present embodiment controls the pair of left and right stimulation units 14 so that the pair of left and right stimulation units alternately repeat the application and removal of stimulation. Specifically, as shown in FIG. 3, control unit 15 of the present embodiment controls the rotational positions of the two valves 143 and 144 so that the pair of left and right air bags 14R and 14L alternately repeat inflation (application of stimulation) and contraction (removal of stimulation), thereby controlling the inflation and contraction operations of the pair of left and right air bags 14R and 14L. This will be described in more detail below.

[0020] As shown in FIG. 3, for the right airbag 14R, as shown in the solid-line pressure diagram, taking time t0 → t1 → t3 → t4 → t6 as a unit cycle (one cycle), the pressure is increased (inflated) from time t0 to t1, the pressure is maintained (inflation is maintained) from time t1 to t3, the pressure is decreased (contracted) from time t3 to t4, and the pressure is maintained (contraction is maintained) from time t4 to t6. While driving the pump 141, the rotation position of the valve 144 corresponding to the right airbag 14R is controlled. That is, at time t0 → t1, the valve 144 is rotated to the open position to supply the air from the pump 141 to the right airbag 14R. At time t1 → t3, the valve 144 is rotated to the closed position to block the supply and exhaust of air to the airbag 14R. At time t3 → t4, the valve 144 is rotated to the drain position to exhaust the air from the airbag 14R. At time t4 → t6, the pump 141 is stopped to stop the supply of air to the airbag 14R.

[0021] On the other hand, for the left airbag 14L, as shown in the dashed-line pressure diagram in FIG. 3, taking time t2 → t5 → t7 → t8 → t9 as a unit cycle (one cycle), the pressure is increased (inflated) from time t2 to t5, the pressure is maintained (inflation is maintained) from time t5 to t7, the pressure is decreased (contracted) from time t7 to t8, and the pressure is maintained (contraction is maintained) from time t8 to t9. While driving the pump 141, the rotation position of the valve 143 corresponding to the left airbag 14L is controlled. That is, at time t2 → t5, the valve 143 is rotated to the open position to supply the air from the pump 141 to the right airbag 14L. At time t5 → t7, the valve 143 is rotated to the closed position to block the supply and exhaust of air to the airbag 14L. At time t7 → t8, the valve 143 is rotated to the drain position to exhaust the air from the airbag 14L. At time t8 → t9, the pump 141 is stopped to stop the supply of air to the airbag 14L.

[0022] Furthermore, the control unit 15 of this embodiment controls the inflation time t0-t1 of the right air bladder 14R to be longer than the depressurization time t3-t4. In other words, the depressurization speed of the air bladder 14R is controlled to be larger than the inflation speed. This is equivalent to setting a larger speed for removing stimulation from the right buttock H of the seated person compared to the speed for applying stimulation. The control unit 15 of this embodiment also performs similar control for the left air bladder 14L. That is, the inflation time t2-t5 of the left air bladder 14L is controlled to be longer than the depressurization time t7-t8. In other words, the depressurization speed of the air bladder 14L is controlled to be larger than the inflation speed. This is equivalent to setting a larger speed for removing stimulation from the left buttock H of the seated person compared to the speed for applying stimulation.

[0023] Furthermore, the control unit 15 of this embodiment controls the system so that the period during which one of the left and right pair of stimulators 14 begins to remove the stimulus overlaps in time with the period during which the other of the left and right pair of stimulators 14 begins to apply the stimulus. That is, in the pressure diagram of Figure 3, the time t3 to t4 during which the right air bag 14R is depressurized (contracted) corresponds to the period during which one of the left and right pair of stimulators 14 begins to remove the stimulus, and the time t2 to t5 during which the left air bag 14L is depressurized (inflated) corresponds to the period during which the other of the left and right pair of stimulators 14 begins to apply the stimulus. The control unit 15 of this embodiment controls the system so that the time t3 to t4 during which the right air bag 14R is depressurized (contracted) and the time t2 to t5 during which the left air bag 14L is depressurized (inflated) overlap in time t2 to t4 on the horizontal time axis.

[0024] Furthermore, in this embodiment, the control unit 15 controls the right air bag 14R so that the internal pressure of the air bag 14R remains constant from time t1 to t3, and controls the left air bag 14L so that the internal pressure of the air bag 14L remains constant from time t5 to t7.

[0025] Next, I will explain the mechanism of action. Figure 4 is a front view showing the pelvis H2 and spine H1 to illustrate the operation of a vehicle seat according to one embodiment of the present invention. When a occupant, such as a driver, sits in the vehicle seat 1 of this embodiment, the pair of left and right stimulating parts 14, i.e., the pair of left and right air bladders 14R and 14L, provided on the seat cushion 11, are both in a contracted state, as shown in the center figure of the same figure.

[0026] From this state, when the seated person turns on an operating switch (not shown) to activate the control unit 15, the control unit 15 drives the pump 141 and controls the rotational positions of the two valves 143 and 144, supplying air alternately to the left and right pair of air bladders 14R and 14L, causing them to inflate and deflate alternately. When the right air bladder 14R inflates and the left air bladder 14L deflates, the right side of the pelvis H2 is lifted and the left side of the pelvis H2 is relatively lowered, as shown in the left diagram of Figure 4, causing the spine to curve. Conversely, when the left air bladder 14L inflates and the right air bladder 14R deflates, the left side of the pelvis H2 is lifted and the right side of the pelvis H2 is relatively lowered, as shown in the right diagram of Figure 4, causing the spine to curve in the opposite direction to that shown in the left diagram of the same figure.

[0027] Applying and removing such alternating left-right stimulation, for example at intervals of 5 to 60 seconds, stimulates the spine (vertebral column), including the spinal cord, by causing it to curve, thus providing an awakening effect to the seated person. In addition, when a seated person maintains a seated posture, their own weight causes water to seep out of the intervertebral discs, leading to a loss of elasticity in the discs and increased strain on the muscles, resulting in fatigue. However, by applying and removing alternating left-right stimulation with the vehicle seat 1 of this embodiment, the spine (vertebral column), including the spinal cord, curves, allowing the seeped water to return to the intervertebral discs, restoring their elasticity and thus reducing fatigue.

[0028] Next, we will describe the experiments and results regarding the embodiments and comparative examples of the present invention. A monotonous simulated driving task was prepared, and 13 subjects (10 men and 3 women) operated the vehicle according to the simulated driving task for 60 minutes. On the first day, under conditions where stimulation by the stimulator 14 was not applied or removed, the 13 subjects operated the vehicle according to the same simulated driving task for 60 minutes at the same time, place, and temperature. On the second day, under conditions where stimulation by the stimulator 14 was applied and removed, the 13 subjects operated the vehicle according to the same simulated driving task for 60 minutes at the same time, place, and temperature. At this time, the target pressure to the air bags 14R and 14L was set to 400 Pa, and the driving cycle was set to 20 seconds.

[0029] Figure 5 shows the results of subjective assessments of alertness by 13 subjects while driving, conducted at 10-minute intervals. Figure 5 is a graph showing the effect (subjective assessment of alertness) of a vehicle seat according to one embodiment of the present invention. Subjective alertness was assessed on a 6-point scale from 0 to 5, with drowsiness levels being evaluated. The vertical axis shows the average drowsiness level of the 13 subjects, with higher numbers indicating stronger drowsiness. The horizontal axis shows the 60-minute driving time, with subjective assessments conducted at 10-minute intervals. The results of the experiment conducted on day 1 are presented as a comparative example of the present invention, and the results of the experiment conducted on day 2 are presented as an embodiment of the present invention.

[0030] In the comparative example (no stimulation) shown in Figure 5, a tendency for drowsiness to continuously increase was observed from 30 to 60 minutes after the start of driving. In contrast, in the example (with stimulation), drowsiness peaked 40 minutes after the start of driving, but thereafter, a tendency for drowsiness to decrease was observed. Furthermore, when a t-test (p=0.05) was performed on 10 of the 13 subjects, a significant difference was confirmed between the example (with stimulation) and the comparative example (no stimulation) for 7 subjects.

[0031] Furthermore, while the 13 subjects were driving, their facial expressions were captured by a camera, and a third party observed the facial expression images to determine their drowsiness level and blinking frequency through facial expression rating.

[0032] Figure 6 is a graph showing the effect of a vehicle seat according to one embodiment of the present invention (evaluation of alertness level by facial expression analysis). The level of alertness was evaluated on a 5-point scale from 1 to 5, based on drowsiness levels. The vertical axis shows the average drowsiness level based on facial expression ratings conducted on 13 subjects, with higher numbers indicating greater drowsiness. The horizontal axis shows a 60-minute driving time, with facial expression ratings conducted at 10-minute intervals. The results of the experiment conducted on day 1 are presented as a comparative example of the present invention, and the results of the experiment conducted on day 2 are presented as an embodiment of the present invention.

[0033] As shown in Figure 6, it was confirmed that the drowsiness level was lower in the example where stimulation was applied and removed for most of the time from the start to the end of driving compared to the comparative example where stimulation was not applied and removed. In other words, it is thought that the alertness-maintaining effect of the present invention is being demonstrated. However, in the example shown in Figure 5, a peak in drowsiness was observed 40 minutes after the start of driving, but such a trend was not observed in the facial expression rating shown in Figure 6. Furthermore, when a t-test (p=0.05) was performed on 6 of the 13 subjects, a significant difference was confirmed between the example (with stimulation) and the comparative example (without stimulation) for 2 subjects.

[0034] Figure 7 is a graph showing the effect (number of blinks) of a vehicle seat according to one embodiment of the present invention. The vertical axis shows the average number of blinks for each of the 13 subjects measured from images captured by a camera. The horizontal axis shows the driving time of 60 minutes, and facial expression ratings were taken at 10-minute intervals. The results of the experiment conducted on the first day are shown as a comparative example of the present invention, and the results of the experiment conducted on the second day are shown as an embodiment of the present invention. Between 10 and 40 minutes from the start of driving, it was observed that the embodiment had a lower number of blinks and a higher level of alertness compared to the comparative example.

[0035] Figure 8 is a graph showing the effect (physical fatigue index) of a vehicle seat according to one embodiment of the present invention. The vertical axis shows the average physical fatigue index of each of the 13 subjects measured. The horizontal axis shows the 60-minute driving time, measured at 10-minute intervals. The results of the experiment conducted on the first day are shown as the comparative example of the present invention, and the results of the experiment conducted on the second day are shown as the embodiment of the present invention. As shown in Figure 8, it was confirmed that the physical fatigue index was lower in the embodiment compared to the comparative example for the entire time from the start to the end of driving. Furthermore, when a t-test (p=0.05) was performed on 11 of the 13 subjects, a significant difference was confirmed between the embodiment (with stimulation) and the comparative example (without stimulation) for 7 subjects.

[0036] As described above, the vehicle seat 1 of this embodiment includes a seat cushion 11 and a seat back 12, and has a pair of stimulating parts 14 provided on the left and right sides of the seat cushion 11 along the vehicle width direction to stimulate the occupant, and a control unit 15 that controls the pair of left and right stimulating parts 14. The control unit 15 controls the pair of left and right stimulating parts 14 so that they alternately apply and remove stimulation to the left and right sides. Thus, instead of swaying the upper body from side to side to maintain the occupant's alert state as in the prior art, the pelvis is tilted alternately to the left and right to curve the spine (vertebral column) H1. This curvature of the spine H1 promotes pressure distribution on the intervertebral discs with less discomfort and reduces fatigue load. Furthermore, this curvature of the spine H1 stimulates the nerves passing through the spine H1, thereby waking the occupant or maintaining the occupant's alert state.

[0037] Furthermore, in the vehicle seat 1 of this embodiment, the pair of left and right stimulating parts 14 are positioned behind the seat cushion 11 in the vehicle's front-to-rear direction, so that the stimulating parts 14 can stimulate the occupant's pelvis H2, thereby curving the spine H1 in the simplest and most efficient way.

[0038] Furthermore, in the vehicle seat 1 of this embodiment, the pair of left and right stimulating parts 14 are positioned to correspond to the bones of the seated person's buttocks, so that the stimulating parts 14 can stimulate the seated person's pelvis H2, thereby curving the spine H1 in the simplest and most efficient way.

[0039] Furthermore, in the vehicle seat 1 of this embodiment, the control unit 15 controls the pair of left and right stimulators 14 such that the speed at which the stimulus is removed is greater than the speed at which the stimulus is applied, so that the spine H1 can move easily and the spine H1 can be curved in the simplest and most efficient way.

[0040] Furthermore, in the vehicle seat 1 of this embodiment, the control unit 15 controls the left and right pair of stimulators 14 such that the period t3 to t4 during which one of the left and right pair of stimulators 14 begins to remove the stimulus and the period t2 to t5 during which the other of the left and right pair of stimulators 14 begins to apply the stimulus overlap in time. This allows for continuous stimulation of the occupant's pelvis H2 and continuous curvature of the spine H1.

[0041] Furthermore, in the vehicle seat 1 of this embodiment, the control unit 15 controls the pair of left and right stimulators 14 so as to maintain the intensity of the stimulus at a constant level t1 to t3 from the time the stimulus is applied until it is removed, thereby mitigating discomfort from the stimulus to the occupant.

[0042] In the embodiments described above, an air bladder was exemplified as a member that provides and removes stimulation to the seated person. However, the stimulating part 14 of the present invention is not limited to this, and a member that can extend and retract toward the seated person's buttocks H may be used. Also, in the embodiments described above, a pair of left and right air bladder 14R and 14L were provided at the rear of the seat cushion 11, but they may be provided on the seat back 12 as long as the seated person's pelvis H2 can be stimulated. Furthermore, in the embodiments described above, a pair of left and right air bladder 14R and 14L were exemplified as a member that provides and removes stimulation to the seated person. However, the stimulating part 14 of the present invention is not limited to this, and a single oscillating member may stimulate the seated person's buttocks alternately on the left and right sides. In addition, in the embodiments described above, a pair of valves 143 and 144 were exemplified as members constituting the stimulating part 14. However, the stimulating part 14 of the present invention is not limited to this, and a single valve or three or more valves may stimulate the seated person's buttocks alternately on the left and right sides. [Explanation of Symbols]

[0043] 1... Vehicle seats 11…Seat cushion 111... Pad 112…Skin material 12... Seat back 13…Headrest 14...Stimulation part 14R, 14L... Air bladder 141... Pump 142... Air tube 143,144… valves 15…Control Unit H...Buttocks H1…Spine H2...Pelvis

Claims

1. In a vehicle seat including a seat cushion and a seat back, A pair of stimulating parts are provided on the seat cushion along the width direction of the vehicle, and stimulate the occupant. It has a control unit that controls the pair of left and right stimulators, The control unit controls the pair of left and right stimulators so that they alternately apply and remove stimuli from the left and right sides, respectively, for a vehicle seat.

2. The vehicle seat according to claim 1, wherein the pair of left and right stimulating parts are arranged at the rear of the seat cushion in the vehicle's front-to-rear direction.

3. The vehicle seat according to claim 1 or 2, wherein the pair of left and right stimulating parts are positioned to correspond to the bones of the seated person's buttocks.

4. The vehicle seat according to claim 1 or 2, wherein the control unit controls the pair of left and right stimulators such that the speed at which the stimulus is removed is greater than the speed at which the stimulus is applied.

5. The vehicle seat according to claim 1 or 2, wherein the control unit controls the left and right pair of stimulators such that the period during which one of the left and right pair of stimulators begins to remove the stimulus overlaps in time with the period during which the other of the left and right pair of stimulators begins to apply the stimulus.

6. The vehicle seat according to claim 1 or 2, wherein the control unit controls the pair of left and right stimulators to maintain a constant intensity of the stimulus from the time the stimulus is applied until it is removed.

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