Postural maintenance tool

Abstract

To support a seated person so that his / her posture can become proper.SOLUTION: A postural maintenance tool comprises: a first support part (23) that assumes a concave spherically-curved surface shape capable of supporting the buttocks (42) in a seated state; a front protrusion (24) that protrudes forward from a lower end of the first support part (23) and that can support the downside of a thigh (43); and an upper protrusion (25) that is positioned on the upside of the first support part (23) and that comprises a lumbar part support part (28) assuming a convexly curved shape capable of supporting the iliac part (151) of the lumbar part (44). First scooped-out parts (30) are provided on both the sides of a root part of the upper protrusion (25), respectively.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a posture support device which is placed on the seat of a chair, for example, and which is capable of maintaining a correct posture of a seated person. [Background technology]

[0002] Conventionally, as this type of posture support device, for example, the configuration disclosed in Patent Document 1 has been proposed. In this conventional configuration, the entire posture support device is integrally molded from a thick cushioning material such as polyurethane foam. This posture support device is provided with a seat that bears most of the weight of a seated person. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-254878 A Summary of the Invention [Problem to be solved by the invention]

[0004] In this conventional configuration, it is difficult to stably support the seated occupant, and as a result, it is difficult for the seated occupant to assume a correct posture. The present invention has been made in view of the problems existing in the prior art, and has an object to maintain a correct posture of a seated person. [Means for solving the problem]

[0005] In order to achieve the above-mentioned objective, this posture retainer is equipped with a buttocks support portion capable of supporting the buttocks of a seated person, and an upper protrusion located above the buttocks support portion, the left and right width of the upper protrusion is wider above the base portion where the buttocks support portion joins the upper protrusion, and both left and right sides of the upper protrusion are located forward of the left-right center.

[0006] This configuration allows the seated occupant to maintain correct posture. Effect of the Invention

[0007] The posture support device described above allows a seated person to maintain a correct posture. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view showing the posture maintaining device according to the first embodiment. [Diagram 2] FIG. 2 is a front view of the attitude support device of FIG. 1 . [Diagram 3] FIG. 2 is a plan view of the attitude support device of FIG. 1 . [Figure 4] A cross-sectional view taken along line 4-4 in Figure 2, showing the human skeleton and the state of use. [Diagram 5] FIG. 4 is a front cross-sectional view at the position of the buttocks support portion, showing the state of use. [Figure 6] FIG. 4 is a front cross-sectional view at the position of the thigh support part, showing the state of use. [Figure 7] Cross-sectional view taken along line 7-7 in Figure 2. [Figure 8] Cross-sectional view taken along line 8-8 in Figure 2. [Figure 9] Diagonal rear view of the device in use. [Figure 10] Front view of the main body. [Figure 11] FIG. 4 is a cross-sectional view showing a layered structure of the posture maintaining device. [Figure 12] 12 is a cross-sectional view taken along line 12-12 in FIG. [Figure 13] FIG. 11 is a front view of a main body according to a second embodiment. [Figure 14] FIG. 13 is a perspective view showing a posture maintaining device according to a third embodiment. [Figure 15] FIG. 15 is a rear perspective view of the posture maintaining device of FIG. 14. [Figure 16] FIG. 15 is an exploded perspective view of the attitude maintaining device of FIG. 14 . [Figure 17] FIG. 15 is a front view of the attitude holder of FIG. 14 . [Figure 18] An enlarged cross-sectional view taken along line 18-18 in Figure 17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the posture maintaining device of the embodiment will be described with reference to the drawings. (First embodiment) First, the first embodiment will be described with reference to FIGS.

[0010] As shown in Figures 1 to 3, the posture maintaining device 21 of this embodiment is formed into a generally petal-like shape. The posture maintaining device 21 includes a main body 22 (see Figures 4 and 5) made of a plate material made of hard synthetic resin such as polypropylene. Here, the hard synthetic resin is a foamed material or a solid material that is not foamed, and has a hardness that allows it to stand on its own without deforming under its own weight, for example, a hardness of R50 to R110 on the Rockwell hardness scale.

[0011] As shown in Figures 4 and 5, a concavely curved buttocks support part 23 for supporting the buttocks 42 of a seated person 41 is formed in the center of the posture supporter 21 in the front-rear direction. A front protrusion 24 is formed on the front lower side, which is one end of the posture supporter 21, facing forward. An upper protrusion 25 is formed on the rear upper side, which is the other end of the posture supporter 21, facing upward. As shown in Figures 1 and 2, a pair of first recesses 30 are formed on both left and right sides of the base of the upper protrusion 25 to allow the upper protrusion 25 to bend appropriately in the backward tilting direction.

[0012] As shown in Figs. 4 and 5, the buttock support portion 23 has an upper surface curved in the front-rear and left-right directions so as to stably support the buttocks 42 of the seated person 41 from the front-rear and left-right directions, and is generally formed in a concave shape of a substantially spherical curved surface. The lower surface of the buttock support portion 23 is also formed in a spherical curved shape. The lower surfaces of the buttock support portion 23 and the front protrusion portion 24 are formed in a continuous spherical curved shape. As shown in Figs. 1 and 3, a second hollow portion 26 is formed on the front side of the center of the front protrusion portion 24. As shown in Fig. 6, a pair of left and right thigh support portions 27, which are curved in a concave shape when viewed from the front, are formed on both the left and right sides of the front protrusion portion 24, that is, on both sides of the second hollow portion 26, so as to support the lower legs 45 of the seated person 41 in a substantially parallel state. These thigh support portions 27 support the thighs 43 by enveloping them from below. Furthermore, since the thigh support portion 27 has a concave curved shape, it prevents the thighs 43 from opening to the left and right.

[0013] As shown in Figures 2, 7 and 8, the upper protrusion 25 is formed with a pair of left and right lumbar support parts 28, each having an upper part 281 with a convex curved shape and a lower part 282 with a concave curved shape. The upper part 281 with a convex curved shape is formed in each lumbar support part 28 so as to bulge diagonally forward so as to face the inner front. Therefore, as shown in Figures 4 and 5, both sides of the pelvis 151 part of the lumbar part 44 of the seated person 41 can be pushed from the rear toward the inner front while avoiding the spine 152. A third hollowed-out part 29 is formed between the pair of lumbar support parts 28.

[0014] As shown in Fig. 12, thickness t1 of edge 301 of main body 22 at the back of first hollowed-out portion 30 is formed to be thicker than thickness t2 of other portions of main body 22. That is, when lumbar support portion 28 flexes, concentrated stress acts on edge 301 at the back of first hollowed-out portion 30 of main body 22. This stress may cause cracks or the like to occur in edge 301 and its vicinity. In this case, the increase in thickness t1 prevents such cracks.

[0015] 2 and 7, a pair of legs 31 protrude from both sides of the underside of the buttocks support part 23 of the posture maintaining device 21. When the posture maintaining device 21 is placed on an installation surface such as the seat of a chair 100, the posture maintaining device 21 is supported in a stable state on the installation surface via the legs 31 without slipping much. In particular, the legs 31 restrict the lateral movement of the posture maintaining device 21, making it difficult for the upper body of the seated person 41 to tilt left or right.

[0016] 11, a cushioning material 32 made of open-cell foamed polyurethane or the like is attached to the seating side surface of the main body 22. The entire posture support device 21 including the main body 22 and the cushioning material 32 is covered with an exterior sheet 34. This exterior sheet 34 is composed of a surface sheet 341 made of an outer woven or knitted fabric, and a back sheet 342 made of an elastic material such as open-cell EVA (ethylene-vinyl acetate copolymer resin) laminated on the back surface of the surface sheet 341.

[0017] As shown in Fig. 10, a plurality of first holes 33 are formed at intervals in the lower part of the upper protruding part 25 of the main body 22. In this way, the first holes 33 allow moisture due to sweating to escape. Furthermore, when the cushioning material 32 is formed, a part of the cushioning material 32 enters the first holes 33 as shown in Fig. 11. The part of the cushioning material 32 entering the first holes 33 prevents the cushioning material 32 from peeling off from the surface of the main body 22 and from moving on the surface.

[0018] A plurality of small second holes 221 are formed throughout the main body 22. These second holes 221, together with the first holes 33, are intended to release moisture resulting from sweating by the seated occupant. A portion of the cushion material 32 also enters the second holes 221 during molding.

[0019] Next, the operation of the posture maintaining device 21 configured as above will be described. For example, when using the posture retainer 21 while sitting on a chair to perform desk work in an office, the posture retainer 21 is placed on the seat of the chair. In this state, as shown in Figs. 4 to 6 and 9, when a seated person 41 sits on the posture retainer 21, the lower surface of the position spanning from the buttocks support part 23 to the front protrusion part 24 is formed in a spherical curved shape, so that the posture retainer 21 is slightly tilted forward by the weight of the seated person 41, and in this state, the buttocks 42 of the seated person 41 are supported on the spherical concave buttocks support part 23. At this time, the buttocks support part 23 is restricted from tilting in the left and right directions by the left and right legs 31, so that the buttocks support part 23 is relatively stable in the left and right directions.

[0020] In this way, as the posture maintaining device 21 tilts slightly forward, the buttocks 42 of the seated person 41 also tilt slightly forward, so that the pelvis 151 of the seated person 41 is in an upright position, and in this state the buttocks 42 of the seated person 41 are supported on the buttocks support part 23. Since the back muscles are naturally stretched by the upright pelvis 151, the upper body of the seated person does not tilt forward even if the posture maintaining device 21 tilts forward. In addition, both thighs 43 of the seated person 41 are supported in an almost parallel state by the thigh support part 27 having a concave curved shape on the front protruding part 24. Therefore, the lower legs 45 of the seated person are supported in an aligned state.

[0021] Furthermore, as the posture retainer 21 leans forward, the pair of lumbar support parts 28 of the upper protrusion 25 also move forward, so that the pelvis 151 including the ilium in the lumbar region 44 of the seated person 41 is supported so as to be wrapped from the left and right as shown in Figs. 3 and 4. At this time, as shown in Fig. 8, both sides of the lumbar region 44 are supported by being pushed from the rear toward the inside and front by the convexly curved upper parts 281 of the pair of lumbar support parts 28 of the upper protrusion 25. This allows the back muscles of the seated person 41 to naturally stretch without strain, and the seated person 41 is supported in a correct posture while enjoying good seating comfort. Therefore, the seated person 41 can maintain a correct posture for a long time without feeling much fatigue.

[0022] In this case, a pair of first hollows 30 are formed on both sides of the base of the upper protrusion 25 of the posture retainer 21. Therefore, when the seated person 41 leans back in a seated state, the upper protrusion 25 is bent appropriately in the backward tilt direction at the portion narrowed by the first hollow 30, allowing the movement of the seated person 41. Also, when the seated person 41 is overweight or has a large body shape, the first hollow 30 reduces the cramped feeling caused by the body shape, ensuring a comfortable sitting experience. In other words, the first hollow 30 opens up both sides of the base of the upper protrusion 25, i.e., both sides between the buttocks support part 23 and the upper protrusion 25, thereby reducing the cramped feeling of the seated person.

[0023] This posture-maintaining device 21 can be used not only on the seat of a chair, but also on the floor. In other words, since the main body 22 is made of a hard material, it can be used as a chair that can maintain posture.

[0024] The posture-maintaining device 21 may be configured without the front protrusion 24. In this case, the position indicated by the dashed line 101 in FIG. 3 is the front end of the posture-maintaining device 21. In this configuration, for example, when the device is placed on the floor and used as a chair, the thigh support 27 does not restrict the lower limbs 45, and the seated person 41 can easily sit in any posture, such as sitting cross-legged, and the degree of freedom of the lower limbs 45 is increased. However, since the thigh support 27 does not support the lower limbs 45, the effect of keeping the thighs 43 horizontal is slightly reduced, but since the device is on the floor, this is of little concern. The buttocks support 23, on which the legs 31 are formed in the left-right direction, makes it possible to keep the buttocks 42 almost horizontal. For this reason, even if thigh support portion 27 is not provided, buttocks 42 are stably and naturally supported in the front-to-back and left-to-right directions by buttock support portion 23, and both sides of waist 44 are supported by being pushed from the rear toward the inside and front by the convexly curved upper portion 281 of waist support portion 28, so that the upper body of seated person 41 can be supported in a correct posture.

[0025] According to the above-described embodiment, the following effects can be obtained. (1) According to the embodiment described above, the buttocks support portion 23 supporting the buttocks 42 of the seated person 41 is formed in a concave curved shape in the front-rear and left-right directions. Therefore, not only can the buttocks 42 be stably and naturally supported in the front-rear and left-right directions by the buttocks support portion 23, but also the area supporting the buttocks 42 is increased, dispersing body pressure. Therefore, the seated person 41 can maintain a seated state without feeling much fatigue or discomfort.

[0026] (2) The thighs 43 of the seated person 41 are stably supported from below over a wide area by the two thigh support parts 27 on the left and right sides of the front protrusion 24, and the lower legs 45 are naturally aligned. In addition, the thigh support parts 27 have a concave curved shape, which prevents the thighs 43 from opening to the left and right. Therefore, as in the above, body pressure is distributed, and the seated state can be maintained without feeling fatigue, and the pelvis 151 of the seated person 41 can be kept horizontal without tilting. Therefore, as shown in FIG. 5, the spine 152 can be naturally held upright in the left and right direction.

[0027] (3) The body 22 of the posture holder 21 is made of a hard plate material. Therefore, unlike the conventional configuration in which the entire posture holder 21 is made of a thick elastic material such as a cushion material, the thighs 43 and the waist 44 can be firmly supported at the waist support part 28 without causing large elastic deformation like the thick elastic material, and the posture holding effect can be improved. If the seated person 41 loses his / her posture, the posture holder 21 hardly deforms, so the seated person 41 can immediately return to the correct posture. And, by maintaining the posture correctly, the muscles that maintain the posture are used and can be trained, so that the correct posture can be naturally maintained even when the posture holder 21 is not used. Also, in the conventional configuration in which the entire posture holder is made of a cushion material, when the posture holder is placed on a chair, the seat surface becomes high due to its thickness, making it difficult to use. In contrast, in this embodiment, the main body 22 is formed from hard resin, and therefore, unlike the conventional configuration, the thickness of the posture maintaining device 21 can be made thin, and there is almost no problem in using the posture maintaining device 21 on the chair 100.

[0028] (4) Since the underside from the buttock support part 23 to the front protruding part 24 has a spherical curved surface with a large radius of curvature in the front-rear direction, the posture maintaining device 21 is inclined forward when the seated person 41 is seated. Therefore, the pelvis 151 of the seated person 41 is supported in an upright position, and the seated person 41 assumes a posture with his / her back muscles naturally straight. In this position, the pelvis 151 including the ilium is supported by the lumbar support part 28 of the upper protruding part 25 on both sides of the spine 152 in the lumbar region 44, so that the lumbar region 44 is supported in a manner that the pelvis 151 is pushed forward from the left and right diagonally behind, and the lumbar region 44 is supported in a manner that the lumbar region 44 is wrapped.

[0029] As a result, the lumbar region of the seated person 41 is also pushed forward, and as shown in Figures 4 and 5, the seated person 41, coupled with the stable support of the buttocks 42 and both thighs 43, stands up naturally in an ideal S-curve shape so that the upper body, i.e., the spine 152, does not tilt left or right and is in a correct posture. Moreover, the legs 31 provide stability in the left and right direction of the posture holder 21, suppressing the tilt of the upper body and allowing the seated person 41 to maintain a correct posture. Therefore, even if the spine 152 of the seated person 41 is distorted left or right or has a tendency to slouch, the body is supported in the correct state and the upper body of the seated person 41 naturally stretches in an appropriate posture with left and right neutral.

[0030] This reduces the burden on the lower back of the seated person 41, and the seated person 41 can comfortably maintain a correct posture with his or her back straightened while relaxing, and the burden on the lower back 44 and lower limbs 45 can be reduced, reducing the sense of fatigue, even if the seated person 41 sits for a long time. Incidentally, it is possible to straighten the back by directly pushing the spine 152 and lumbar vertebrae of the seated person 41 forward without using the posture retainer 21, but in such a case, the seated person 41 feels pain and discomfort, making it difficult to maintain a seated position for a long time. Even if the seated person 41 has a lumbar curve forward, the lower back 44 is supported by the lower back support part 28, and the pelvis 151 and spine 152 are supported in a manner that they are wrapped around them, reducing the burden on the lower back 44 and allowing the seated person 41 to relax.

[0031] (5) The bottom surfaces of the buttocks support portion 23 and the front protruding portion 24 are formed in a spherical curved shape with a large radius of curvature in the left-right direction, so that the posture maintaining device 21 is allowed to tilt to a certain extent in the left-right direction. Therefore, the seated person 41 can gently tilt his / her upper body to the left or right and avoid feeling cramped.

[0032] (6) The legs 31 are provided on both sides of the lower surface of the buttocks support part 23 of the posture support device 21. Therefore, the posture support device 21 can be placed in a stable state on the seat of the chair 100, for example, without slipping or excessively tilting to the left or right.

[0033] (7) The first recesses 30 are formed on both sides of the base of the upper protrusion 25. Therefore, even if the body 22 of the posture holder 21 is made of hard synthetic resin, when the seated person 41 sits on the buttocks support part 23 and leans back, applying a load in the backward direction to the upper protrusion 25, the upper protrusion 25 can be bent. This contributes to the seated person 41 maintaining a correct posture and reducing fatigue. That is, since the body 22 of the posture holder 21 is made of hard synthetic resin, the posture holder 21 has rigidity and hardness, and although the change in shape is small, deformation of required parts can be ensured. Therefore, the posture holder 21 can effectively exert its original function and contribute to maintaining a relaxed posture without strain.

[0034] (8) In addition, because the buttocks support portion 23 is formed in a concave spherical curved shape, the base portion of the upper protrusion 25 continuing upward from the buttocks support portion 23 is also formed in a concave spherical curved shape similar to that of the buttocks support portion 23. Therefore, unlike this embodiment, if the first hollowed-out portion 30 is not formed, the upper protrusion 25 would be hard and would be difficult to bend backward. However, in this embodiment, as described above, the first hollowed-out portions 30 are formed on both sides of the base portion of the upper protrusion 25, so that the difficulty in bending is eliminated, and the upper protrusion 25 can appropriately respond to the body movements of the seated occupant 41.

[0035] (9) The first recesses 30 are formed on both sides of the base of the upper protrusion 25, and the recesses are open, which prevents the seated occupant 41 from feeling cramped. In contrast, if the recesses 30 are not formed, the buttocks of the seated occupant 41 may come into contact with the recesses if the occupant is large, resulting in a cramped feeling.

[0036] (10) The formation of the first to third recesses 30, 26, and 29 can reduce the weight of the entire posture maintaining device 21. (11) As described above, the third recess 29 is formed between the lumbar support parts 28. Therefore, when the seated person 41 leans backward or leans back heavily, the spine of the seated person 41 can be prevented from hitting the upper protruding part 25. Therefore, discomfort in such a case can be avoided.

[0037] (12) Four hollows are formed by the first hollow 30, the second hollow 26, and the third hollow 29. Therefore, the posture maintaining device 21 as a whole has a petal shape, and can have an excellent design.

[0038] (13) The edge 301 of the first hollowed-out portion 30 is formed to be thicker than other portions. Therefore, even if a large stress is applied to the first hollowed-out portion 30 due to deformation caused by tilting of the upper protruding portion 25, the risk of the edge 301 of the first hollowed-out portion 30 being damaged can be reduced.

[0039] (14) The cushion material 32 is provided on the seating side surface of the main body 22. Therefore, the cushion material 32 has an elastic effect and a shock-absorbing effect, so that the seating comfort can be maintained. (15) The entire posture support device 21 is covered with an exterior sheet 34. This allows the posture support device 21 to maintain its overall appearance beautiful.

[0040] Second embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 13. In the second and subsequent embodiments and modifications, differences from the first embodiment will be mainly described.

[0041] 13, the first hole 33 and the second hole 221 of the main body 22 as in the first embodiment are not provided. Therefore, in the second embodiment, the main body 22 can be easily molded.

[0042] Third embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the second and third recessed portions 26 and 29 are formed to be shallower than in the first embodiment.

[0043] Moreover, a single-layer exterior sheet 51 made of EVA is adhered to the seating surface side of the main body 22 made of a hard material such as polypropylene using an elastomeric adhesive. As shown in Figures 16 and 18, a fold 511 is formed on the periphery of the exterior sheet 51, and the exterior sheet 51 is adhered to the seating surface of the main body 22 with the fold 511 fitted into the periphery of the main body 22. The back and bottom surfaces of the main body 22 are exposed. The exterior sheet 51 is made of a porous material that is flexible, elastic, and breathable.

[0044] A plurality of holes 52 are formed in the upper protruding portion 25. As shown in Fig. 18, each hole 52 is composed of a hole 521 in the main body 22 and a hole 522 in the exterior sheet 51, and the hole 521 in the exterior sheet 51 is formed larger than the hole 521 in the main body 22. Therefore, the inner peripheral edge of the hole 522 in the exterior sheet 51 protrudes toward the hole center beyond the inner peripheral edge of the hole 521 in the main body 22, so that the inner peripheral edge of the hole 521 in the main body 22 does not come into contact with the seated person 41.

[0045] As shown in FIG. 15, a plurality of anti-slip pads 53 made of a material with a high coefficient of friction are attached to the bottom surface of the front projection 25 and the lower ends of the legs 31. The third embodiment has the following advantages.

[0046] (16) The posture maintaining device 21 is constructed by covering the seating side of the main body 22 with a single-layer exterior sheet 51, so that the number of parts is small and the structure is simple. In addition, since the back and bottom surfaces of the main body 22 are exposed, the exterior sheet 51 can be small, and it is easy to cover the main body 22 with the exterior sheet 51. Therefore, the posture maintaining device 21 can be manufactured at low cost.

[0047] (Example of change) This embodiment can be modified as follows. The buttocks support part 23 of the posture maintaining device 21 may be formed in a shape other than a spherical curved shape, such as a flat surface, a cylindrical concave shape, or a concave curved shape. In this case, the effect of the buttocks support part 23 stably supporting the buttocks 42 in the front-rear and left-right directions is weakened. However, in the left-right direction, the thighs 43 are restricted by the thigh support part 27 having a concave curved shape, and the buttocks 42 are also stabilized by the influence. Therefore, the seated person 41 is supported by the waist support part 28 by pushing both sides of the waist 44 from the rear toward the inside and front, while keeping the pelvis 151 horizontal. As described above, even if the buttocks support part 23 of the posture maintaining device 21 is formed in a shape other than a spherical curved shape, the posture of the seated person 41 can be supported in a correct state.

[0048] Cushioning material 32 is provided on both the seating side and the opposite side of the main body 22. The cushioning material 32 may be omitted. The exterior sheet 34 may be omitted.

[0049] Both the cushioning material 32 and the exterior sheet 34 may be omitted. In other words, the posture maintaining device 21 may be configured to include only the main body 22. The legs 31 on the bottom surface of the posture maintaining device 21 may be omitted, and the bottom surface may be made flat.

[0050] The first recess 30 at the base of the lumbar support portion 28 is provided on only one of the left and right sides. Do not form any hollow parts other than the first hollow part 30. If the third hollow part 29 is not formed, the pair of lumbar support parts 28 will be connected and will appear to be one piece, but because the lumbar support parts 28 protrude forward, the continuous central part can hold both sides of the lumbar part 44 without hitting the spine 152 or either side of it, so that in effect there is a pair.

[0051] The buttocks support portion 23 is formed linearly in one direction, either the front-rear direction or the left-right direction. The main body 22 is made of FRP (fiberglass reinforced plastic), which is plastic reinforced with glass fibers. [Explanation of symbols]

[0052] 21...posture maintaining device, 22...main body, 23...buttocks support portion, 24...front protrusion, 25...upper protrusion, 26...second hollow, 27...thigh support portion, 28...lumbar support portion, 29...third hollow, 30...first hollow, 301...edge, 31...leg, 32...cushioning material, 34...outer seat, 41...occupant, 42...buttocks, 43...thighs, 44...lumbar, 45...lower limbs, 52...spine, t1...thickness of edge, t2...thickness of other parts.

Claims

1. The seat includes a buttocks support portion capable of supporting the buttocks of a seated person and an upper protrusion portion located above the buttocks support portion, The width of the upper protrusion is wider above the base than at the base where the upper protrusion is attached to the buttocks support part. The upper protrusion is located forward of the left and right side portions from the center portion in the left and right direction, The lower surface of the buttocks support portion is formed into a curved surface that is convex downward in the front-to-rear direction.

2. The seat includes a buttocks support portion capable of supporting the buttocks of a seated person and an upper protrusion portion located above the buttocks support portion, The width of the upper protrusion is wider above the base than at the base where the upper protrusion is attached to the buttocks support part. The upper protrusion is located forward of the left and right side portions from the center portion in the left and right direction, The lower surface of the buttocks support portion is formed into a downwardly convex spherical curved shape.

3. 3. The posture support device according to claim 1, wherein the upper protrusion is formed with a pair of lumbar support parts capable of supporting both sides of the lumbar region of a seated person from behind.

4. 4. The posture maintaining device according to claim 1, further comprising a thigh support part having a concave shape protruding from one end side of the buttock support part and capable of supporting the lower sides of both thighs.

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