cushion

Abstract

To provide a cushion capable of suppressing displacement of the ischium, and reducing force applied to the ischium.SOLUTION: A cushion according to an embodiment is a cushion 1 constituted of a flexible raw material. The cushion 1 includes a seat part 2 having a hip support part 4 where a user's hip is placed, and a thigh support part 5 where a user's thigh is placed. The hip support part 4 has a pair of ischium support parts 6 aligned along a longitudinal direction as a view from a user seated on the seat part 2. Each ischium support part 6 has a recess 6b hollowed from an upper surface 4b of the hip support part 4 in the state where the ischium is placed. The curvature of each recess 6b is larger than the curvature of the upper surface 4b. The seat part 2 has an inclined plane 7 extending obliquely upward toward the thigh support part 5 from the hip support part 4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a cushion on which a user's buttocks and thighs rest. [Background technology]

[0002] Various cushions on which a user's buttocks and thighs are placed have been known for some time. Japanese Patent Application Laid-Open Publication No. 2020-168583 describes a posture support device equipped with a buttocks support portion. The posture support device includes a buttocks support portion that supports the buttocks of a seated person, a front protrusion that protrudes forward from the buttocks support portion, and an upper protrusion that extends upward from the buttocks support portion. The front protrusion supports the underside of the seated person's thighs. The upper protrusion has a lumbar support portion that supports the iliac region of the seated person's lower back.

[0003] Japanese Patent Application Laid-Open Publication No. 2014-12130 describes a chair cushion. The chair cushion includes a cushion body and a cover. The cushion body includes a seat portion against which the seated person's buttocks come into contact, and a back portion against which the seated person's back comes into contact. The inclination angle of the back portion relative to the seat portion in a side view is between 95° and 110°. The seat portion has two ischial bone-corresponding portions, each of which has a concave surface shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-168583 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-12130 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a user sits on a cushion, they may lean forward or backward. When the user leans forward or backward, the user's sitting bones may shift forward or backward. If the user sits for a long time with the sitting bones shifted, the user may injure their shoulders, neck, or lower back. Furthermore, if high pressure is applied to the sitting bones, the user may injure their buttocks. Therefore, it is necessary to prevent the sitting bones from shifting and reduce the force applied to the sitting bones.

[0006] The present disclosure aims to provide a cushion that can suppress displacement of the ischial bones and reduce the force applied to the ischial bones. [Means for solving the problem]

[0007] A cushion according to one aspect of the present disclosure is made of a flexible material. The cushion includes a seating portion having a buttocks support portion on which a user's buttocks are placed and a thigh support portion on which the user's thighs are placed. The buttocks support portion has a pair of ischial support portions aligned in the left-right direction as seen from a user seated on the seating portion. Each ischial support portion has a recess that is recessed from the upper surface of the buttocks support portion when the ischial bones are placed on it. The curvature of each recess is greater than the curvature of the upper surface. The seating portion has an inclined surface that extends diagonally upward from the buttocks support portion toward the thigh support portion. The shape of each ischial support portion in plan view extends in a long axis direction and a short axis direction intersecting the long axis direction, and the length in the long axis direction is longer than the length in the short axis direction.

[0008] This cushion includes a seating section, which has a buttocks support section and a thigh support section. Because this cushion is made of a flexible material, it can gently support the user's buttocks, which are supported by the buttocks support section, and the user's thighs, which are supported by the thigh support section. The buttocks support section has a pair of ischium support sections aligned in the left-right direction, each of which has a recess recessed from the upper surface of the buttocks support section. Therefore, when the user sits on the seating section, the user's ischium fits into each recess, preventing misalignment of the ischium and reducing the force applied to the ischium. The curvature of each recess is greater than the curvature of the upper surface of the buttocks support section. Therefore, the user's ischium can fit more reliably into the recess with a larger curvature, more reliably preventing misalignment of the ischium when sitting. Furthermore, the seating section has an inclined surface extending diagonally upward from the buttocks support section toward the thigh support section. Therefore, because the height of the buttocks support portion is lower than the height of the thigh support portion, it is possible to prevent the buttocks from shifting forward, and it is possible to more reliably prevent the ischial bones from shifting forward. This reduces the force applied to the ischial bones and also prevents the ischial bones from shifting forward.

[0009] A cushion according to another aspect of the present disclosure is made of a flexible material. The cushion includes a seat having a buttocks support portion on which a user's buttocks are placed and a thigh support portion on which the user's thighs are placed. The buttocks support portion has a pair of ischial support portions aligned in the left-right direction as seen from a user seated on the seat. Each ischial support portion has a through-hole penetrating downward from the upper surface of the buttocks support portion. The seat has an inclined surface extending diagonally upward from the buttocks support portion toward the thigh support portion. The shape of each ischial support portion in plan view extends in a long axis direction and a short axis direction intersecting the long axis direction, and the length in the long axis direction is longer than the length in the short axis direction.

[0010] This cushion includes a seating section, which has a buttocks support section and a thigh support section. Because this cushion is made of a flexible material, it can gently support the user's buttocks, supported by the buttocks support section, and the user's thighs, supported by the thigh support section. The buttocks support section has a pair of ischium support sections aligned laterally, each with a through-hole extending downward from the upper surface of the buttocks support section. Therefore, when the user sits on the seating section, the user's ischium fits into each through-hole, preventing the ischium from shifting and reducing the force applied to the ischium. Furthermore, the seating section has an inclined surface extending diagonally upward from the buttocks support section toward the thigh support section. Therefore, because the height of the buttocks support section is lower than the height of the thigh support section, the buttocks are less likely to shift forward, and the ischium can be more reliably prevented from shifting forward. This reduces the force applied to the ischium and prevents the ischium from shifting forward.

[0011] Each ischial support portion may have a tapered surface located between the inner wall of the through hole that defines the through hole and the upper surface of the buttocks support portion. In this case, the tapered surface between the inner wall of the through hole and the upper surface of the buttocks support portion allows the inner wall of the through hole to smoothly connect to the upper surface of the buttocks support portion via the tapered surface. Therefore, when the user sits on the seat, the ischial bones that enter the through hole can be gently supported by the tapered surface, further reducing the force applied to the ischial bones.

[0012] The cushion may include a lumbar support portion that contacts the user's lumbar region from behind. The lumbar support portion may have a convex sacrum support portion that supports the user's sacrum from behind. In this case, the lumbar support portion contacts the lumbar region of the user seated on the seating portion. At this time, the convex sacrum support portion contacts the user's sacrum, thereby preventing the user's pelvis from shifting downward. Therefore, the user's posture can be maintained appropriately.

[0013] The sacrum support portion may have a protruding surface. The protruding surface may be curved and protrude forward. In this case, the user can more easily feel the force pushing the sacrum forward compared to when the protruding surface is flat.

[0014] The lumbar support portion may have a lumbar support portion above the sacrum support portion that supports the lumbar vertebrae of the user from behind. In this case, the lumbar vertebrae located above the sacrum are supported by the lumbar support portion. Therefore, the lumbar vertebrae of the user seated on the seating portion can be supported, and pelvic misalignment can be more reliably prevented.

[0015] The lumbar support portion may have ilium support portions that support the user's ilium on both the left and right sides of the lumbar support portion as seen from the user seated on the seat. In this case, a pair of iliums located on each of the left and right sides of the lumbar vertebrae are supported by the ilium support portions. Therefore, it is possible to more reliably prevent the user's pelvis from shifting when seated on the seat.

[0016] flat The pair of ischial support parts are shaped like an inverted V in plan view. The ischial bones of a user sitting on the seat also have an inverted V shape in plan view. Therefore, by matching the shape of the pair of ischial support parts to the shape of the user's ischial bones, it is possible to improve the fit of the ischial support parts to the ischial bones while reliably preventing misalignment of the ischial bones.

[0017] The intersecting angle between the extension lines of the pair of long axes may be between 40° and 150°. In this case, the long axes of the ischial support parts can be aligned with the orientation of the ischial bones of a user sitting on the seat, thereby improving the fit of the ischial bones to the ischial support parts.

[0018] The thickness of the thigh support portion when the user is seated on the seat may be thinner than the thickness of the rest of the seat when the user is seated on the seat. In this case, when the user is seated on the seat, the thigh support portion is thinner than the rest of the seat, so the position of the user's thighs can be prevented from rising too much.

[0019] The amount of deformation of the thigh support portion when the user sits on the seat may be greater than the amount of deformation of the portion of the seat other than the thigh support portion when the user sits on the seat. In this case, when the user sits on the seat, the amount of downward deformation of the thigh support portion is greater than the portion of the seat other than the thigh support portion, so the position of the user's thighs can be prevented from rising too much.

[0020] The thigh support portion may have a recess that defines a space between it and the support surface on which the cushion is placed. In this case, when the user places their thighs on the thigh support portion, the thigh support portion easily deforms to reduce the space. This makes it easier for the thigh support portion to deform downward, preventing the thighs from rising and improving seating comfort.

[0021] The projected area of ​​the underside of the cushion may be smaller than the projected area of ​​the cushion in a plan view. In this case, the area of ​​the seating portion in a plan view is larger than the area of ​​the underside of the cushion facing the support surface on which the cushion is placed, so the cushion can be placed on a support surface with a smaller area than the area of ​​the seating portion in a plan view. Therefore, the cushion can be placed on the seat surfaces of various chairs, improving the versatility of the cushion. [Effects of the Invention]

[0022] According to the present disclosure, it is possible to suppress displacement of the ischial bones and reduce the force applied to the ischial bones. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing a cushion according to an embodiment. [Figure 2] FIG. 2 is a plan view showing a cushion according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a front view showing the cushion according to the embodiment. [Figure 5] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 6] FIG. 1 is a diagram showing a schematic diagram of the spine and pelvis of a human body. [Figure 7] 1(a) is a diagram showing a schematic view of the pelvis of the body, and FIG. 1(b) is a diagram showing a schematic view of the spine and pelvis of the body. [Figure 8] 10A is a graph showing the position of the user's ischial bones in a plan view, and FIG. 10B is a graph showing the height position of the user's sacrum. [Figure 9] FIG. 10 is a side view showing a cushion according to a first modified example. [Figure 10] 1(a) is a front view of a seating portion of a cushion according to a first modified example, and (b) is a plan view of a lumbar support portion of the cushion according to the first modified example. [Figure 11] FIG. 10 is a plan view of a seating portion according to a first modified example. [Figure 12] 10(a) is a perspective view showing a cushion according to a second modified example, and FIG. 10(b) is a perspective view showing a cushion according to a third modified example. [Figure 13] FIG. 10 is a perspective view showing a cushion according to a fourth modified example. [Figure 14] FIG. 10 is a plan view showing a cushion according to a fourth modified example. [Figure 15] 15 is a cross-sectional view taken along line CC in FIG. 14. [Figure 16] FIG. 10 is a front view showing a cushion according to a fourth modified example. [Figure 17] FIG. 15 is a cross-sectional view taken along the line DD in FIG. 14. [Figure 18] FIG. 10 is a bottom view showing a cushion according to a fourth modified example. [Figure 19] FIG. 11 is a perspective view showing a cushion according to a fifth modified example. [Figure 20] FIG. 11 is a plan view showing a cushion according to a fifth modified example. [Figure 21] FIG. 13 is a bottom view showing a cushion according to a fifth modified example. [Figure 22] FIG. 10 is a front view showing a cushion according to a fifth modified example. [Figure 23] 21 is a cross-sectional view taken along line EE in FIG. 20. [Figure 24] 10 is an experimental result (measured data) showing the pressure distribution in a comparative example when a user sits on a chair without a cushion. [Figure 25] 1(a) is an experimental result (actual measurement data) showing the pressure distribution in the seating portion and the sacrum support portion when a user sits on the cushion according to Example 1. FIG. 1(b) is an experimental result (actual measurement data) showing the pressure distribution in the seating portion and the sacrum support portion when a user sits on the cushion according to Example 2. [Figure 26] 1(a) is an experimental result (measured data) showing the pressure distribution at the thigh support part when a user sits in a forward-leaning position on the cushion according to Example 3. FIG. 1(b) is an experimental result (measured data) showing the pressure distribution at the thigh support part when a user sits in a forward-leaning position on the cushion according to Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of a cushion according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional proportions and the like are not limited to those shown in the drawings.

[0025] The cushion according to the present disclosure is made of a flexible material. The term "flexible material" refers to a cushioning material that deforms when a body is placed on it and receives a load. The cushion includes a seating portion having a buttocks support portion on which the user's buttocks are placed and a thigh support portion on which the user's thighs are placed.

[0026] "User" refers to a user of the cushion, for example, a person sitting on the cushion. "Buttocks" refers to the protruding part of the lower back of the body, which is the part of the body located below the waist and above the thigh. "Thigh" refers to the part of the thigh from the base of the leg to the knee.

[0027] "Sitting" refers to sitting on the cushion. "Sitting section" refers to the part of the cushion that the buttocks and thighs come into contact with when sitting on the cushion. The buttocks support section has a pair of ischium support sections. "Ischisis" refers to the part of the pelvis that is located at the lowest position when the user is sitting on the seat.

[0028] Fig. 1 is a perspective view showing a cushion 1 according to this embodiment. As shown in Fig. 1, the cushion 1 includes a seating portion 2 extending horizontally and a lumbar support portion 3 extending upward from the seating portion 2. The cushion 1 is made of a flexible material. For example, the cushion 1 is made of urethane foam.

[0029] As an example, the cushion 1 is formed by urethane molding. When the cushion 1 is made of urethane foam and formed by urethane molding, the cushion 1 made of a flexible material can be easily manufactured. The cushion 1 is, for example, a core material that is housed in a fabric cover.

[0030] The flexible material includes, for example, a thermoplastic elastomer. The flexible material may be a material that has enough elasticity to deform in response to the load when a body is placed on it. The flexible material may be a resin (for example, polypropylene, polyester, or polyethylene) that deforms when a body is placed on it and receives a load. The flexible material may be a mesh material. In this way, the type of flexible material can be changed as appropriate.

[0031] The seating portion 2 extends in a first direction D1 and a second direction D2 intersecting the first direction D1. The first direction D1 is the front-to-back direction when viewed from a user seated on the seating portion 2, and the second direction D2 is the left-to-right direction when viewed from a user seated on the seating portion 2. The seating portion 2 has a thickness in a third direction D3 intersecting both the first direction D1 and the second direction D2. For example, the third direction D3 is the vertical direction.

[0032] Hereinafter, the forward direction as seen by a user seated on the seating section 2 may be referred to as the "front," "front side," or "forward," and the opposite direction to the forward direction may be referred to as the "rear," "rear side," or "rearward." However, these directions are used for convenience of explanation and do not limit the position or orientation of each part.

[0033] Fig. 2 is a plan view of the cushion 1. As shown in Figs. 1 and 2, the length A1 of the cushion 1 in the first direction D1 is 30 cm or more and 90 cm or less. Alternatively, the length A1 may be 40 cm or more and 50 cm or less, for example, 45 cm. The length A2 of the cushion 1 in the second direction D2 is, like the length A1, 30 cm or more and 90 cm or less, or 40 cm or more and 50 cm or less, for example, 45 cm.

[0034] The seating section 2 has a buttocks support section 4 on which the user's buttocks are placed, and a thigh support section 5 on which the user's thighs are placed. The buttocks support section 4 and the thigh support section 5 are arranged side by side in the first direction D1. The buttocks support section 4 has a pair of ischium support sections 6 that support the ischial bones of the user seated on the seating section 2.

[0035] The ischial support portion 6 is formed on the upper surface 4b of the buttocks support portion 4 and is recessed relative to the upper surface 4b. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. As shown in FIGS. 2 and 3, the buttocks support portion 4 has a pair of ischial support portions 6 aligned along the second direction D2. The ischial support portion 6 has a recess 6b recessed from the upper surface 4b of the buttocks support portion 4. The recess 6b is defined, for example, by a corner 6c at the boundary with the upper surface 4b and a curved surface 6h located inside the corner 6c in a plan view. The curvature of the recess 6b (curved surface 6h) is greater than the curvature of the upper surface 4b of the buttocks support portion 4. Note that the recess 6b does not have to be exposed. It is sufficient that the recess 6b is recessed from the upper surface 4b of the buttocks support portion 4 when the user's ischial bones are placed on it. For example, the recess 6b may be filled with a material that is more easily recessed than the buttocks support portion 4.

[0036] The shape of the ischial support portion 6 in plan view has a major axis 6d and a minor axis 6f. That is, the ischial support portion 6 extends in both the major axis direction D4, which is the direction in which the major axis 6d extends, and the minor axis direction D5, which is the direction in which the minor axis 6f extends. For example, the shape of the ischial support portion 6 in plan view is oval. As an example, the shape of the ischial support portion 6 in plan view is elliptical. However, the shape of the ischial support portion 6 in plan view is not limited to an oval or elliptical shape, and may be rectangular, rectangular with rounded corners, diamond, or diamond with rounded corners, and can be changed as appropriate.

[0037] An extension line L1 of the long axis 6d of one of the pair of ischial support portions 6 and an extension line L2 of the long axis 6d of the other of the pair of ischial support portions 6 intersect with each other. The intersection angle θ1 between the extension line L1 and the extension line L2 is, for example, 40° or more and 150° or less. The intersection angle θ1 may be 50° or more, 60° or more, 75° or more, or 90° or more. The intersection angle θ1 may also be 135° or less, 120° or less, or 110° or less. For example, the intersection angle θ1 is 100°.

[0038] The intersection P between the extension lines L1 and L2 is located closer to the thigh support section 5 than the pair of ischium support sections 6. The intersection P is located closer to the thigh support section 5 than the center 6g of each ischium support section 6 in a plan view. The intersection P is located on the opposite side of the lumbar support section 3 from the pair of ischium support sections 6. As a result, the pair of ischium support sections 6 have an inverted V shape in a plan view (plan view when the lumbar support section 3 is oriented to be located above the seating section 2).

[0039] The length of the major axis 6d of the ischial support 6 is, for example, 5 cm or more and 10 cm or less. For example, the length of the major axis 6d is 7 cm. The length of the minor axis 6f of the ischial support 6 is, for example, 3 cm or more and 9 cm or less. For example, the length of the minor axis 6f is 5 cm.

[0040] The distance A5 between the centers 6g of the pair of ischial support portions 6 (the center-to-center distance of the pair of ischial support portions 6) is, for example, 7 cm or more and 15 cm or less. As an example, the distance A5 is 10 cm. The positions of the pair of centers 6g in the first direction D1 are, for example, the same as each other. The distance from the lumbar support portion 3 to the center 6g is, for example, 5 cm or more and 15 cm or less. As an example, the distance from the lumbar support portion 3 to the center 6g is 10 cm. When each length and each distance is within the above value range, the user's ischial bones can be more suitably fitted to each of the pair of ischial support portions 6.

[0041] The seating portion 2 has an inclined surface 7 that extends obliquely upward from the buttocks support portion 4 toward the thigh support portion 5. For example, the seating portion 2 has a pair of inclined surfaces 7 aligned along the second direction D2. For example, the inclined surfaces 7 are linear in a cross section along a plane extending in the first direction D1 and the third direction D3. The inclination angle θ2 of the inclined surfaces 7 relative to the lower surface 1b of the cushion 1 is, for example, 5° or more and 15° or less. As an example, the inclination angle θ2 is 10°.

[0042] When the inclination angle θ2 is 5° or more and 15° or less, it is possible to make it more difficult for the ischial bones of a user seated on the seating portion 2 to shift forward. Unlike the above example, the inclined surface 7 may have a curved shape in a cross section along a plane extending in the first direction D1 and the third direction D3 (for example, a curved shape that curves so that the inclination angle θ2 increases toward the thigh support portion 5).

[0043] For example, the seating portion 2 has a pair of thigh support portions 5 aligned along the second direction D2 and a convex portion 8 located between the pair of thigh support portions 5. Each of the pair of thigh support portions 5 is located on the front side of the inclined surface 7. For example, the thigh support portions 5 are convex. The backs of the user's thighs are placed on the thigh support portions 5. In other words, the thigh support portions 5 support the backs of the user's thighs. The thigh support portions 5 have, for example, a top portion 5b located at the front end of the inclined surface 7 and a curved portion 5c extending forward and diagonally downward from the top portion 5b.

[0044] The protrusions 8 indicate portions that protrude from the inclined surface 7. For example, in a plan view, the protrusions 8 have a shape that extends along the first direction D1. In a plan view, the width of the protrusions 8 increases toward the front. The height of the protrusions 8 increases toward the center in the second direction D2.

[0045] The protrusion 8 has an apex 8b and an inclined portion 8c extending diagonally downward and forward from the apex 8b. In a plan view, the inclined portion 8c has a triangular shape that widens toward the front. The position of the apex 8b of the protrusion 8 is located behind the position of the apex 5b of the thigh support portion 5.

[0046] Fig. 4 is a front view of the cushion 1. As shown in Figs. 2 to 4, the seating portion 2 has a pair of protrusions 9 located on both ends of the inclined surface 7 in the second direction D2. For example, the protrusions 9 connect the lumbar support portion 3 and the thigh support portion 5 to each other. The protrusions 9 extend along the first direction D1.

[0047] The top 9b of the protrusion 9 is, for example, a curved surface. As an example, the height of the top 9b of the protrusion 9 is higher than the height of the top 5b of the thigh support portion 5. The height of the top 9b of the protrusion 9 may be the same as the height of the top 8b of the protrusion 8. By providing the above-described protrusions 8 and 9, it becomes easier for the user to rest their thighs on each position on both sides of the protrusion 8 in the second direction D2 between the pair of protrusions 9. Note that the shapes of the protrusions 8 and 9 are not limited to the above-mentioned aspects and can be changed as appropriate. Furthermore, the cushion may not have at least one of the protrusions 8 and 9.

[0048] Next, the lumbar support section 3 will be described. For example, the lumbar support section 3 is curved so as to protrude forward toward both ends in the second direction D2. Fig. 5 is a cross-sectional view taken along line BB in Fig. 2. As shown in Figs. 3 to 5, the lumbar support section 3 extends upward from the end (rear end) of the seating section 2 in the first direction D1.

[0049] The lumbar support part 3 has, for example, a general part 10 extending in both the second direction D2 and the third direction D3, and a sacrum support part 11 located in the center of the second direction D2 at the bottom of the general part 10. The general part 10 indicates the part of the lumbar support part 3 other than the sacrum support part 11. The general part 10 has a first part 10b extending upward from the rear end of the buttocks support part 4, and a second part 10c extending upward and diagonally forward from the top end of the first part 10b.

[0050] The thickness of the first portion 10b in the first direction D1 becomes thinner as it goes upward. The first portion 10b is composed of an inner surface 10d that curves rearward and diagonally upward, and an outer surface 10f that curves to bulge outward in the first direction D1. The first portion 10b also has recesses 10g that are recessed along the second direction D2 at both ends in the second direction D2.

[0051] The second portion 10c is located, for example, above the first portion 10b and the sacral support portion 11. The second portion 10c has a lumbar support portion 12 that supports the user's lumbar vertebrae from behind, and an ilium support portion 13 that supports the user's ilium on both sides in the second direction D2 of the lumbar support portion 12. For example, a pair of ilium support portions 13 are provided on both sides of the lumbar support portion 12 in the second direction D2.

[0052] For example, the lumbar support portion 12 is defined by a front end 3b located above the lower back support portion 3 and an inclined surface 3c extending diagonally downward from the front end 3b. Each of the pair of ilium support portions 13 protrudes from both ends in the second direction D2 and also protrudes forward. The lumbar support portion 12 supports the lumbar vertebrae of the user by contacting the lumbar vertebrae from behind. The ilium support portion 13 supports the pair of ilium by facing the user's ilium from both ends in the second direction D2.

[0053] For example, the sacral support portion 11 has a convex shape that protrudes forward. The sacral support portion 11 protrudes forward from the front surface 10h of the general portion 10. As an example, the shape of the sacral support portion 11 when viewed from the front has a major axis 11b and a minor axis 11c. For example, the shape of the sacral support portion 11 when viewed from the front is an oval shape. As an example, the shape of the sacral support portion 11 when viewed from the front is an ellipse shape.

[0054] However, the shape of the sacral support portion 11 as viewed from the front may be a shape other than an oval or ellipse, such as a rectangle, a rounded rectangle, a diamond, or a rounded diamond, and can be modified as appropriate. For example, the upper end 11d of the protruding surface 11g of the sacral support portion 11 is flush with the front surface 10h of the general portion 10. The protruding surface 11g of the sacral support portion 11 protrudes forward from the inner surface 10d of the general portion 10. For example, the protruding surface 11g is inclined forward as it extends upward. As an example, the protruding surface 11g is flat.

[0055] The length of the major axis 11b of the sacrum support part 11 is, for example, 5 cm or more and 15 cm or less. As an example, the length of the major axis 11b is 10 cm. The length of the minor axis 11c of the sacrum support part 11 is, for example, 3 cm or more and 10 cm or less. As an example, the length of the minor axis 11c is 7 cm. Furthermore, the height in the third direction D3 of the center 11h of the sacrum support part 11 relative to the bottom 4c of the buttocks support part 4 is, for example, 5 cm or more and 15 cm or less. As an example, the height of the center 11h is 9 cm or more and 10 cm or less. When the sacrum support part 11 described above abuts against the user's sacrum, the sacrum can be supported by the sacrum support part 11.

[0056] Incidentally, it is desirable that the pelvis of a person sitting on a cushion be horizontal in the left-right direction and stand straight. Fig. 6 is a diagram schematically showing a human spine E1 and pelvis E2. Fig. 7(a) is a diagram schematically showing the pelvis E2. Fig. 7(b) is a diagram schematically showing the spine E1 and pelvis E2 as viewed from the left and right direction of the body.

[0057] 6, 7(a), and 7(b), it is desirable that the imaginary line L3, which is a straight line connecting the protrusion of the ilium E3 and the pubic bone E4, of the body of a person sitting on a cushion extends vertically. If the imaginary line L3 remains tilted for a long period of time, problems such as fatigue, poor posture, and a tendency to gain weight (lower body obesity) may occur.

[0058] Furthermore, from the viewpoint of maintaining good posture, it is desirable to support the rear end of the sacrum E5 and the lower ends of the pair of ischial bones E6 so that they do not shift. Specifically, by preventing the lower ends of the ischial bones E6 from shifting forward and preventing the sacrum E5 from shifting downward, good posture can be maintained and the problems described above can be prevented even when sitting for long periods of time.

[0059] Next, the effects obtained from the cushion 1 according to this embodiment will be described in detail. As shown in Figures 1 and 2, the cushion 1 has a seating section 2, which has a buttocks support section 4 and a thigh support section 5. Because the cushion 1 is made of a flexible material, it can gently support the buttocks of the user supported by the buttocks support section 4 and the thighs of the user supported by the thigh support section 5.

[0060] The buttocks support section 4 has a pair of ischium support sections 6 aligned along the second direction D2 (left-right direction), and each of the pair of ischium support sections 6 has a recess 6b recessed from the upper surface 4b of the buttocks support section 4. Therefore, when the user sits on the seating section 2, the ischium E6 of the user's buttocks fit into each recess 6b, thereby preventing the ischium E6 from shifting and reducing the force applied to the ischium E6. The curvature of each recess 6b is greater than the curvature of the upper surface 4b of the buttocks support section 4. Therefore, the user's ischium E6 can fit more reliably into the recess 6b with a larger curvature, more reliably preventing the ischium E6 from shifting when sitting.

[0061] Furthermore, the seating section 2 has an inclined surface 7 that extends obliquely upward from the buttocks support section 4 toward the thigh support section 5. Therefore, the height of the buttocks support section 4 is lower than the height of the thigh support section 5, which makes it difficult for the buttocks to slip forward and more reliably prevents the ischium E6 from slipping forward. This reduces the force acting on the ischium E6 and prevents the ischium E6 from slipping forward.

[0062] The cushion 1 according to this embodiment includes a lumbar support section 3 that abuts against the user's lumbar region from behind. The lumbar support section 3 has a convex sacrum support section 11 that supports the user's sacrum E5 from behind. Therefore, the lumbar support section 3 abuts against the lumbar region of the user seated on the seating section 2. At this time, the convex sacrum support section 11 abuts against the user's sacrum E5 from behind, thereby preventing the user's pelvis E2 from shifting downward. Therefore, the user's posture can be maintained appropriately.

[0063] In a plan view, each ischial support portion 6 has a shape that extends in a long axis direction D4 and a short axis direction D5 that intersects with the long axis direction D4, and the length of the long axis 6d extending in the long axis direction D4 is longer than the length of the short axis 6f extending in the short axis direction D5. Extension lines L1, L2 of the pair of long axes 6d of the pair of ischial support portions 6 intersect with each other at a position closer to the thigh support portion 5 than the center 6g of the pair of ischial support portions 6. Therefore, in a plan view, the pair of ischial support portions 6 have an inverted V-shape. Furthermore, the ischial bones E6 of a user seated on the seating portion 2 also have an inverted V-shape. Therefore, by matching the shape of the pair of ischial support portions 6 to the shape of the user's ischial bones E6, it is possible to improve the fit of the ischial bones E6 to the ischial support portions 6 while reliably preventing the ischial bones E6 from shifting.

[0064] In this embodiment, the intersection angle θ1 between the extension lines L1, L2 of the pair of long axes 6d is 40° or more and 150° or less. This makes it possible to align the long axes 6d of the ischial support parts 6 with the orientation of the ischial bones E6 of a user sitting on the seating part 2, thereby improving the fit of the ischial bones E6 to the ischial support parts 6.

[0065] The lumbar support section 3 has a lumbar support section 12 that supports the lumbar vertebrae of the user from behind above the sacrum support section 11. Therefore, the lumbar vertebrae located above the sacrum E5 are supported by the lumbar support section 12. Therefore, the lumbar vertebrae of the user seated on the seating section 2 can be supported, and displacement of the pelvis E2 can be more reliably suppressed.

[0066] The lumbar support section 3 has ilium support sections 13 that support the ilium E3 of the user on both sides (left and right sides) of the lumbar support section 12 in the second direction D2 as seen from the user seated on the seating section 2. Thus, a pair of iliac bones E3 located on each of the left and right sides of the lumbar vertebrae are supported by the ilium support sections 13. Therefore, it is possible to more reliably suppress displacement of the pelvis E2 of the user seated on the seating section 2.

[0067] Fig. 8(a) is a graph showing the position of a pair of ischial bones E6 of a person in a plan view. Fig. 8(b) is a graph showing the position of a person's sacrum E5 (the position of the part of the sacrum E5 that protrudes backward) when viewed from the front. Fig. 8(a) and Fig. 8(b) each show the results of measurements taken on 10 subjects.

[0068] Figure 8(a) shows the position of the ischial bones E6 when sitting on a square cushion with sides of 40 cm. In the graph of Figure 8(a), the center of the cushion is the origin. The back of the cushion (the surface that the subject's back touches) is located at +20 cm on the vertical axis of Figure 8(a), and the bottom of the vertical axis indicates the front. The horizontal axis of Figure 8(a) indicates the left-right direction.

[0069] As shown in Figure 8(a), the distance between a pair of ischial bones E6 was 10cm to 11cm. Specifically, the average value for female subjects was 10.9cm, and the average value for male subjects was 10.2cm. Furthermore, the average distance in a plan view from the back of the cushion (the surface that the subject's back touches) to the ischial bones was 9.5cm for females and 8.4cm for males.

[0070] As described above, in the cushion 1, the distance between the centers 6g of a pair of ischial support portions 6 is 7 cm or more and 15 cm or less, and the distance from the lumbar support portion 3 to the centers 6g is 5 cm or more and 15 cm or less. In this case, the positions of the ischial support portions 6 and the distance between their centers can be aligned with the positions of the ischial bones E6 of the subject in a plan view, so the positions of the ischial bones E6 of the subject can be fitted to the positions of the ischial support portions 6. Therefore, it is possible to more reliably prevent the ischial bones E6 from shifting.

[0071] FIG. 8(b) is a graph showing the height of the sacrum E5 (the height of the most posteriorly protruding part of the sacrum E5) relative to the bottom 4c of the buttocks support part 4 of a subject seated on the seating part 2. The horizontal axis of FIG. 8(b) indicates the second direction D2, and the vertical axis of FIG. 8(b) indicates the third direction D3. As shown in FIG. 8(b), the height of the sacrum E5 was 6 cm or more and 13.5 cm or less. The average height of the sacrum E5 for female subjects was 8.8 cm, and the average height of the sacrum E5 for male subjects was 9.4 cm.

[0072] In the cushion 1, the height of the center 11h of the sacral support portion 11 relative to the bottom portion 4c is 5 cm or more and 15 cm or less. In this case, the height position of the sacral support portion 11 can be adjusted to the height position of the sacrum E5 described above, so the position of the sacrum E5 of the subject can be fitted to the position of the sacral support portion 11. Therefore, the position of the sacrum E5 can be more reliably fitted to the position of the sacral support portion 11. As a result, displacement of the sacrum E5 can be more reliably suppressed.

[0073] Next, a cushion 21 according to a first modified example will be described. Fig. 9 is a side view of the cushion 21 as viewed from the second direction D2. A portion of the configuration of the cushion 21 is the same as a portion of the configuration of the cushion 1 described above. Therefore, in the following description, descriptions that overlap with the configuration of the cushion 1 will be omitted as appropriate.

[0074] Cushion 21 is made of, for example, urethane foam. As an example, cushion 21 is produced by two-dimensional cutting. Cushion 21 has a plurality of protrusions 21b formed on the surface that comes into contact with the user's body, and a plurality of slits 21c formed on the surface opposite to the surface that comes into contact with the user's body.

[0075] Cushion 21 comprises seating portion 22 and lumbar support portion 23. Seat portion 22 has buttocks support portion 24 on which the user's buttocks are placed, and thigh support portion 25 on which the user's thighs are placed. Seat portion 22 has an inclined surface 29 that extends obliquely upward from buttocks support portion 24 toward thigh support portion 25.

[0076] The seating portion 22 has a plurality of protrusions 21b aligned along both the first direction D1 and the second direction D2, and the plurality of protrusions 21b are arranged in a grid pattern in plan view. The inclined surface 29 is an imaginary surface including the plurality of protrusions 21b, and the height of the inclined surface 29 increases from the buttocks support portion 24 toward the thigh support portion 25.

[0077] The height of convex portion 21b gradually increases from buttocks support portion 24 toward thigh support portion 25. Each of the multiple slits 21c extends along second direction D2. Slit 21c has linear portion 21f extending upward from lower surface 21d of cushion 21, and expanding portion 21g expanding at the upper end of linear portion 21f.

[0078] FIG. 10(a) is a front view of the seating section 22 as viewed from the front. As shown in FIG. 10(a), the seating section 22 has a pair of thigh support sections 25 aligned along the second direction D2. Each of the pair of thigh support sections 25 is formed by a plurality of protrusions 21b. The height of the protrusions 21b in each thigh support section 25 is lower than the height of the protrusions 21b located between the pair of thigh support sections 25 and at both ends of the pair of thigh support sections 25 in the second direction D2. When viewed from the front, the shape of the thigh support section 25 is concave, being recessed more than the other parts. This allows each thigh support section 25 to provide a good fit to the user's thighs.

[0079] The seating portion 22 has, for example, a plurality of upper slits 22b extending along the first direction D1 and aligned along the second direction D2. Each upper slit 22b has, for example, a straight portion 22c extending downward from between the pair of protrusions 21b and an extension portion 22d extending from the lower end of the straight portion 22c.

[0080] For example, a plurality of protrusions 21b are arranged along the second direction D2 between a pair of upper slits 22b arranged along the second direction D2. The plurality of protrusions 21b, for example, configure a protrusion group G1 made up of the plurality of protrusions 21b arranged along the second direction D2. The seating portion 22 has, for example, a plurality of protrusion groups G1.

[0081] This allows the multiple convex portion groups G1 to be deformed independently of one another, and each convex portion 21b deforms to fit the shape of the user's thighs, etc., thereby improving the body pressure distribution of the user's thighs, etc. As an example, three convex portions 21b are lined up between a pair of upper slits 22b. Note that instead of or together with the upper slits 22b, an upper slit extending in the second direction D2 may be formed.

[0082] Fig. 10(b) is a plan view showing lumbar support part 23. As shown in Fig. 9, Fig. 10(a), and Fig. 10(b), lumbar support part 23 has a plurality of protrusions 23b facing forward and a plurality of slits 23c facing the opposite side to the plurality of protrusions 23b. The plurality of protrusions 23b are arranged, for example, in a grid pattern on the front surface of lumbar support part 23.

[0083] The plurality of protrusions 23b are arranged so as to be aligned along the second direction D2 and the third direction D3. The height of the protrusion 23b located at the center of both the second direction D2 and the third direction D3 is the highest, and the height of the protrusions 23b decreases with increasing distance from the protrusion 23b. In other words, the plurality of protrusions 23b as a whole have a quadrangular pyramid shape.

[0084] The multiple slits 23c are arranged in a line along the third direction D3, and each slit 23c extends, for example, linearly along the second direction D2. Slit 23c has linear portion 23f extending forward from rear surface 23d of lumbar support portion 23, and expanding portion 23g expanding at the front end of linear portion 23f.

[0085] The lumbar support portion 23 has a sacrum support portion 31 that protrudes forward. The sacrum support portion 31 is formed by a plurality of convex portions 23b. The amount of protrusion of the convex portions 23b in the sacrum support portion 31 is greater than the amount of protrusion of the convex portions 23b located above and below the sacrum support portion 31. The shape of the sacrum support portion 31 when viewed along the second direction D2 presents a convex shape that protrudes more than other parts. In other words, the sacrum support portion 31 is configured to include the highest (most protruding) convex portion 23b. This allows the sacrum support portion 31 to more reliably support the user's sacrum E5.

[0086] Lumbar support section 23 has lumbar support section 32 that supports the user's lumbar vertebrae from behind. Lumbar support section 32 is formed by protrusions 23b that protrude forward. Lumbar support section 32 is formed, for example, by a plurality of protrusions 23b lined up along second direction D2 at the upper end of lumbar support section 23.

[0087] Lumbar support portion 23 has, for example, a plurality of front slits 23h extending along third direction D3 and aligned along second direction D2. Front slits 23h extend rearward from between a pair of protrusions 23b and have, for example, narrow portions 23j in which the width of front slits 23h narrows toward the rear, and expanding portions 23k that expand at the rear ends of narrow portions 23j.

[0088] For example, a plurality of protrusions 23b are arranged along the second direction D2 between a pair of front slits 23h arranged along the second direction D2. The plurality of protrusions 23b includes, for example, a protrusion group G2 made up of a plurality of protrusions 23b arranged along the second direction D2. The lumbar support portion 23, for example, constitutes a plurality of protrusion groups G2.

[0089] This allows the multiple convex portion groups G2 to be deformed independently of one another, and each convex portion 23b deforms to fit the shape of the user's back or waist, thereby improving the body pressure distribution of the user's back, waist, etc. As an example, three convex portions 23b are lined up between a pair of front slits 23h. Note that instead of or together with the front slits 23h, a front slit extending in the second direction D2 may be formed.

[0090] Fig. 11 is a plan view showing a schematic view of the seating portion 22. For ease of understanding, the protrusions 21b are not shown in Fig. 11. As shown in Fig. 11, the buttocks support portion 24 has a pair of ischial support portions 26 aligned along the second direction D2. The ischial support portions 26 are formed on the upper surface 24b of the buttocks support portion 24, and are formed in the shape of slits on the upper surface 24b.

[0091] The ischial support portion 26 has a slit 27 that is recessed relative to the upper surface 24b. The presence of the slit 27 makes the ischial support portion 26 more likely to recess than the other portions of the buttocks support portion 24 other than the ischial support portion 26. The amount of deformation of the ischial support portion 26 is greater than the amount of deformation of the other portions of the buttocks support portion 24 other than the ischial support portion 26, and therefore the curvature of the ischial support portion 26 when recessed is greater than the curvature of the upper surface 24b.

[0092] For example, ischium support portion 26 has an oval shape in a plan view. The overall shape and position of ischium support portion 26 in a plan view are, for example, the same as the shape and position of ischium support portion 6 in a plan view. ischium support portion 26 has a plurality of slits 27 extending in directions inclined in both first direction D1 and second direction D2, and deformable portions 28 located between the plurality of slits 27. Because deformable portions 28 are located between the plurality of slits 27, they are more easily deformed than portions of buttocks support portion 24 other than deformable portions 28.

[0093] For example, the slit 27 penetrates the seating portion 22 in the third direction D3. The ischial support portion 26 has, for example, a pair of slits 27. The pair of slits 27 extend parallel to each other. As an example, the slit 27 has a curved portion 27b that curves in a wave shape and expansion portions 27c that expand at both ends of the curved portion 27b. The expansion portions 27c expand in an arc shape at the ends of the curved portion 27b, for example.

[0094] In the above example, the ischial support portion 26 has a pair of slits 27 that extend parallel to each other. However, the pair of slits 27 do not have to extend parallel to each other. Also, the ischial support portion 26 may have only one slit 27. In this way, the orientation and number of slits 27 are not particularly limited.

[0095] In the cushion 21 configured as described above, when the user sits on the seating portion 22, each of the pair of ischial support portions 26 has a recess that is recessed from the upper surface 24b of the buttocks support portion 24. The curvature of this recess is greater than the curvature of the upper surface 24b of the buttocks support portion 24. Therefore, the user's ischial bones E6 can be more reliably inserted into the recesses of the ischial support portions 26, which have a greater curvature, and this more reliably prevents the ischial bones E6 from shifting when the user is seated, thereby achieving the same effects as the cushion 1 described above.

[0096] Next, a cushion 41 according to a second modification will be described with reference to Fig. 12(a). As shown in Fig. 12(a), the cushion 41 differs from the cushion 1 in that it does not have a lumbar support portion 12 or an ilium support portion 13. The lumbar support portion 43 of the cushion 41 has a convex portion 44 that becomes higher toward the center in the second direction D2, and a convex sacrum support portion 11 that protrudes forward from a front surface 44b of the convex portion 44.

[0097] Furthermore, a cushion 51 according to a third modification will be described with reference to Fig. 12(b). As shown in Fig. 12(b), cushion 51 differs from cushion 1 in that it does not have a lumbar support portion 3. Cushion 51 has the aforementioned seating portion 2 and a protruding portion 52 that protrudes from the rear end of seating portion 2. The upper surface of protruding portion 52 is, for example, a curved surface.

[0098] Next, a cushion 61 according to a fourth modified example will be described. Fig. 13 is a perspective view showing the cushion 61. Fig. 14 is a plan view showing the cushion 61. Fig. 15 is a cross-sectional view taken along line CC in Fig. 14. Fig. 16 is a front view showing the cushion 61. Fig. 17 is a cross-sectional view taken along line DD in Fig. 14. Fig. 18 is a bottom view showing the cushion 61.

[0099] As shown in FIG. 13, the cushion 61 includes a seating portion 62. The seating portion 62 includes a buttocks support portion 64 and a thigh support portion 65. The seating portion 62 includes a pair of thigh support portions 65 aligned along the second direction D2. The pair of thigh support portions 65 are, for example, provided at positions spaced apart from each other. The user's pair of thighs are placed on each of the pair of thigh support portions 65. The buttocks support portion 64 includes a pair of ischium support portions 66. Unlike the ischium support portions 6 of the cushion 1 described above, each ischium support portion 66 does not include a recess 6b. Each ischium support portion 66 includes a through-hole 66b. The through-hole 66b passes downward from the upper surface 64b of the buttocks support portion 64. Note that the through-holes 66b do not have to be exposed. For example, the through-holes 66b may be filled with a material that is more likely to sink than the portions of the buttocks support portion 64 other than the ischial support portion 66.

[0100] 14, the shape of the through-hole 66b in plan view may be similar to the shape of the ischial support portion 6 in plan view of the cushion 1 described above. As an example, the shape of the through-hole 66b in plan view is an oval (or elliptical) shape. The position of the through-hole 66b is, for example, the same as the position of the recess 6b of the cushion 1 described above.

[0101] The seating portion 62 is formed with an air vent 62a. The air vent 62a penetrates downward from the upper surface 64b of the buttocks support portion 64 or the upper surface of the thigh support portion 65. The upper end of the inner wall defining the air vent 62a may be rounded and chamfered. In a plan view, multiple air vents 62a may be arranged in a line from rear to front. For example, in a plan view (a plan view when the lumbar support portion 73 is oriented to be located above the seating portion 62), multiple (six, for example) air vents 62a may be arranged on both sides (left and right sides) in the second direction D2.

[0102] As an example, three air vents 62a are arranged on each side in the second direction D2. For example, two air vents 62a are aligned along the second direction D2, and the distance between the two air vents 62a aligned along the second direction D2 increases from the buttocks support portion 64 toward the thigh support portion 65. As an example, the multiple air vents 62a are arranged to form a V-shape in a plan view. For example, in the cushion 61, the through-holes 66b are formed by urethane molding, and the air vents 62a are formed by punching. In this case, the mold used to manufacture the cushion 61 does not need a portion for forming the air vents 62a, and the shape of the mold can be simplified. Furthermore, when liquid urethane is molded using the mold, an escape route for air in the liquid urethane is ensured, resulting in a clean finish for the cushion 61.

[0103] 15 is a cross-sectional view of cushion 61 taken along a plane extending in first direction D1 and third direction D3. For example, the thickness of thigh support section 65 when a user sits on seat 62 is thinner than the thickness of the rest of seat 62 when the user sits on seat 62. In this case, thigh support section 65 deforms under load so as to become thinner than the rest of seat 62. For example, the amount of deformation of thigh support section 65 when a user sits on seat 62 is greater than the amount of deformation of the rest of seat 62 when the user sits on seat 62. In this case, thigh support section 65 is more likely to deform under load than the rest of seat 62 when the user sits on seat 62.

[0104] For example, when the user sits on seat 62, thigh support section 65 deforms more than inclined surface 7 when the user sits on seat 62. When the user sits on seat 62, thigh support section 65 may deform so that the inclination angle θ2 decreases from inclined surface 7 toward the front end of thigh support section 65. Furthermore, when no load is applied, thigh support section 65 may be thinner than the thickness of the rest of seat 62. In this case, as with the above, it is possible to prevent the user's thighs from rising too much.

[0105] Each thigh support portion 65 has a recess 65d recessed in the thickness direction of the cushion 61. The cushion 61 has a pair of recesses 65d, and for example, the pair of recesses 65d are provided at positions spaced apart from each other. The depth of the recesses 65d increases with increasing distance from the buttocks support portion 64 (toward the front). For example, the thigh support portion 65 has the recess 65d that defines a space B between itself and the support surface S on which the cushion 61 is placed.

[0106] The recess 65d is formed, for example, in the lower surface 61b of the cushion 61. The outer edge of the recess 65d is located on the lower surface 61b. The thickness of the portion of the thigh support portion 65 where the recess 65d is formed may be thinner than the thickness of the portion of the seating portion 62 other than the thigh support portion 65. As an example, the space B defined between the recess 65d and the placement surface S is formed so as to expand from the rear to the front. The cross section of the space B perpendicular to the first direction D1 may expand from the rear to the front. As an example, the outer edge of the recess 65d may be located on both the lower surface 61b and the inclined portion 65f.

[0107] As shown in FIG. 13, cushion 61 has a general portion 70 and a lumbar support portion 73. Lumbar support portion 73 has a convex portion 74 that becomes higher toward the center in second direction D2, and a convex sacrum support portion 71 that protrudes forward from a front surface 70h of general portion 70. As an example, convex portion 74 and convex portion 9 are continuous. As shown in FIG. 16, the entire lumbar support portion 73 may have an inverted U-shape when viewed in first direction D1.

[0108] 16 and 17, the sacrum support portion 71 has a protruding surface 71a. The protruding surface 71a has a curved surface that protrudes forward. For example, when viewed along the second direction D2, the protruding surface 71a may have a curved surface that protrudes forward from the front surface 70h. The height of the protruding surface 71a from the front surface 70h may increase from the outer edge of the protruding surface 71a toward the inside of the protruding surface 71a.

[0109] The projected area of ​​the underside 61b of the cushion 61 is smaller than the projected area of ​​the cushion 61 in a plan view. For example, as shown in Fig. 15, when viewed in the second direction D2, the inclined portion 65f of the thigh support portion 65 extends rearward and diagonally downward from the apex 65e of the thigh support portion 65. That is, the inclined portion 65f is inclined toward the center of the cushion 61 in the first direction D1 as it approaches the underside 61b. The apex 65e is located, for example, at the front end of the cushion 61.

[0110] When viewed in the second direction D2, the outer surface 70f constituting the first portion 70b of the general portion 70 is inclined toward the center of the cushion 61 in the first direction D1 as it approaches the lower surface 61b. As shown in FIG. 16 , when viewed in the first direction D1, the cushion 61 has an inclined portion 9c that inclines toward the center of the cushion 61 in the second direction D2 as it approaches from the top 9b toward the lower surface 61b. The cushion 61 has, for example, a pair of inclined portions 9c aligned along the second direction D2. The top 9b may be located at an end of the cushion 61 in the second direction D2. As an example, the cushion 61 has a boat-like shape that bulges outward as it moves away from the lower surface 61b.

[0111] Note that thigh support portion 65 does not necessarily have to have recess 65d. At least a portion of thigh support portion 65 may be made of a material that is more easily deformed by a load than the material of the portion of seat portion 62 other than thigh support portion 65.

[0112] Next, the effects obtained from the cushion 61 according to the fourth modification will be described. As shown in Fig. 13, the buttocks support portion 64 has a pair of ischium support portions 66 aligned along the second direction D2 (left-right direction). Each ischium support portion 66 has a through-hole 66b that penetrates downward from the upper surface 64b of the buttocks support portion 64. Therefore, when the user sits on the seat portion 62, the ischium E6 (see Fig. 6) of the user's buttocks fits into each through-hole 66b, thereby preventing the ischium E6 from shifting and reducing the force applied to the ischium E6.

[0113] 17, in the fourth modified example, the sacrum support portion 71 has a protruding surface 71a. The protruding surface 71a is curved and protrudes forward. Therefore, compared to when the protruding surface of the sacrum support portion is flat, the user can feel a force pushing the sacrum E5 (see FIG. 6) forward.

[0114] As described above, the thickness of the thigh support portion 65 when the user is seated on the seat 62 may be thinner than the thickness of the portion of the seat 62 other than the thigh support portion 65 when the user is seated on the seat 62. In this case, when the user is seated on the seat 62, the thigh support portion 65 becomes thinner than the portion of the seat 62 other than the thigh support portion 65, so the position of the user's thighs can be prevented from rising too much. Therefore, pressure on the seated user is more easily distributed from the buttocks to the thighs, so the pressure on the buttocks of the seated user can be reduced.

[0115] As described above, the amount of deformation of the thigh support section 65 when the user sits on the seating section 62 may be larger than the amount of deformation of the other parts of the seating section 62 other than the thigh support section 65 when the user sits on the seating section 62. In this case, when the user sits on the seating section 62, the amount of downward deformation of the thigh support section 65 is larger than that of the other parts of the seating section 62 other than the thigh support section 65, so the position of the user's thighs can be prevented from rising too much. Therefore, pressure on the seated user is more easily distributed from the buttocks to the thighs, and the pressure on the buttocks of the seated user can be reduced.

[0116] As shown in FIG. 15 , the thigh support portion 65 has a recess 65d recessed in the thickness direction of the cushion 61. This allows the thigh support portion 65 to deform more easily than the other portions of the seating portion 62. This allows the thigh support portion 65 to move downward more easily when the thigh is placed on the thigh support portion 65, making it difficult for the thigh to rise, reducing the user's discomfort. The depth of the recess 65d of the thigh support portion 65 increases with increasing distance from the buttocks support portion 64. That is, the depth of the recess 65d of the thigh support portion 65 increases toward the front as viewed from the user seated on the seating portion 62. This allows the front portion of the thigh support portion 65 to deform downward more easily than the buttocks support portion 64, more reliably preventing the thigh from rising. This reduces the user's discomfort and improves the comfort of sitting on the cushion 61.

[0117] Thigh support portion 65 has a recess 65d that defines a space B between it and the support surface S on which cushion 61 is placed. When the user's thighs are placed on thigh support portion 65, thigh support portion 65 easily deforms so as to reduce space B. This makes it easier to deform thigh support portion 65 downward, preventing the thighs from rising and improving sitting comfort. Furthermore, by thigh support portion 65 sinking so as to reduce space B, the user can feel as if their thighs are being embraced by thigh support portion 65.

[0118] As described above, in the fourth modified example, recess 65d is formed so that space B defined between recess 65d and placement surface S expands from the rear to the front. When a user sits on seat 62, thigh support portion 65 can more easily deform its front portion due to space B expanding from the rear to the front. For example, part of the outer edge of recess 65d is located on lower surface 61b. In this case, thigh support portion 65 can be easily sunk using the outer edge of recess 65d located on lower surface 61b as a fulcrum.

[0119] As described above, in the fourth modified example, the projected area of ​​the lower surface 61b of the cushion 61 is smaller than the projected area of ​​the cushion 61 in a planar view. In this case, the area of ​​the seating portion 62 in a planar view is larger than the area of ​​the lower surface 61b of the cushion 61 facing the support surface S on which the cushion 61 is placed, so the cushion 61 can be placed on the support surface S having an area smaller than the area of ​​the seating portion 62 in a planar view. Therefore, the cushion 61 can be placed on the seat surfaces of various chairs, improving the versatility of the cushion 61.

[0120] As described above, in the fourth modified example, the top portion 65e is located at the front end of the cushion 61. The inclined portion 65f is inclined from the top portion 65e toward the bottom surface 61b so as to move toward the center of the cushion 61 in the second direction D2. When the user sits on the seating portion 62, the thigh support portion 65 deforms, for example, so that the entire thigh support portion 65 bends downward. In this case, the user's thighs are gently supported by the thigh support portion 65 that has deformed so that the entire portion bends downward.

[0121] 14, in the fourth modified example, ventilation holes 62a are formed in the seating portion 62. The ventilation holes 62a pass downward from the upper surface 64b of the buttocks support portion 64 or the upper surface of the thigh support portion 65. This prevents stuffiness between the seating portion 62 and the buttocks or thighs of the user.

[0122] As shown in Fig. 16, the entire lumbar support portion 73 may have an inverted U-shape when viewed in the first direction D1. In this case, the lumbar support portion 73 can be made less likely to break than the lumbar support portion 43 shown in Fig. 12(a) in which the convex portion 44 protrudes locally. Furthermore, the shape is simpler than the cushion 1 shown in Fig. 1, and therefore the cushion 61 can be manufactured more easily.

[0123] Next, a cushion 81 according to a fifth modified example will be described. Fig. 19 is a perspective view showing the cushion 81. Fig. 20 is a plan view showing the cushion 81. Fig. 21 is a bottom view showing the cushion 81. Fig. 22 is a front view showing the cushion 81. Fig. 23 is a cross-sectional view taken along line EE in Fig. 20. As shown in Figs. 19 to 23, the cushion 81 differs from the cushion 61 in that it includes an ischial support portion 86 that is different from the ischial support portion 66, and a sacral support portion 91 that is different from the sacral support portion 71.

[0124] In the cushion 81, the buttocks support portion 64 has a pair of ischium support portions 86. Each ischium support portion 86 has a through hole 86b that passes downward from the upper surface 64b of the buttocks support portion 64. Each ischium support portion 86 has a tapered surface 86h that is located between an inner wall 86c that defines the through hole 86b and the upper surface 64b of the buttocks support portion 64. The ischium support portions 86 differ from the ischium support portions 66 of the cushion 61 in that they have tapered surfaces 86h.

[0125] As shown in FIGS. 20 and 21, the through hole 86b in plan view is smaller than the through hole 66b of the cushion 61 described above. The shape of the through hole 86b is, for example, similar to the through hole 66b. As an example, the shape of the through hole 86b in plan view is an oval (or elliptical) shape. An inner wall 86c defining the through hole 86b connects the lower surface 61b and the tapered surface 86h to each other. The end of the inner wall 86c on the lower surface 61b side may be rounded and chamfered. The end of the inner wall 86c on the tapered surface 86h side may be rounded and chamfered.

[0126] The tapered surface 86h connects the inner wall 86c and the upper surface 64b to each other. The tapered surface 86h forms a recess that is recessed into the upper surface 64b. The tapered surface 86h is inclined so that the diameter of the opening end of the tapered surface 86h increases toward the upper surface 64b. In a plan view, the area of ​​the tapered surface 86h may be larger than the area of ​​the through hole 86b. The tapered surface 86h may include a curved surface 86e that is a chamfered portion such that the opening end of the tapered surface 86h is rounded.

[0127] The shape of the tapered surface 86h in plan view may be similar to the shape of the ischial support portion 6 in plan view of the cushion 1 described above. As an example, the shape of the tapered surface 86h in plan view is an oval (or elliptical) shape. The position of the tapered surface 86h is, for example, the same as the position of the recess 6b of the cushion 1 described above.

[0128] In the cushion 81, the lumbar support portion 73 has a convex sacrum support portion 91 that protrudes forward from the front surface 70h of the general portion 70. The sacrum support portion 91 has a curved protruding surface 91a that protrudes forward and a recessed portion 91b that is recessed rearward from the protruding surface 91a. The sacrum support portion 91 differs from the sacrum support portion 71 of the cushion 61 in that it has the recessed portion 91b.

[0129] As shown in FIG. 22, the recessed portion 91b extends in the third direction D3 and the second direction D2. For example, the length of the recessed portion 91b in the third direction D3 is longer than the length (width) of the recessed portion 91b in the second direction D2. The shape of the recessed portion 91b when viewed from the first direction D1 may be a groove shape (or an elliptical shape) extending in the third direction D3. The recessed portion 91b includes a bottom surface 91c and an inner side surface 91d that connects the bottom surface 91c and the protruding surface 91a to each other. When viewed from the first direction D1, the inner side surface 91d has an annular shape that surrounds the bottom surface 91c. The inner side surface 91d may include a rounded surface that connects the bottom surface 91c and the protruding surface 91a to each other.

[0130] 20, in a plan view, the bottom surface 91c is curved so as to recess rearward as it becomes farther away from the end of the recessed portion 91b in the second direction D2. The curvature of the bottom surface 91c in a plan view may be the same as the curvature of the protruding surface 91a in a plan view.

[0131] 23, in a cross section (side cross section) perpendicular to the second direction D2, the bottom surface 91c curves to recess rearward as it moves away from the end of the recessed portion 91b in the third direction D3. The curvature of the bottom surface 91c in the side cross section may be the same as the curvature of the protruding surface 91a in the side cross section.

[0132] The recessed portion 91b is a portion into which the user's sacrum E5 (see FIG. 6) fits. The length (width) of the recessed portion 91b in the second direction D2 is, for example, 1 cm or more and 3 cm or less. As an example, the length of the recessed portion 91b in the second direction D2 is 2 cm. The length of the recessed portion 91b in the third direction D3 is, for example, 5 cm or more and 9 cm or less. As an example, the length of the recessed portion 91b in the third direction D3 is 7 cm. The depth of the recessed portion 91b in the first direction D1 is, for example, 0.5 cm or more and 1.5 cm or less. As an example, the depth of the recessed portion 91b in the first direction D1 is 1 cm. However, the depth of the recessed portion 91b in the first direction D1 is not limited to the above numerical value and may be 1.5 cm or more. Furthermore, the recessed portion 91b may penetrate the sacrum support portion 91 in the first direction D1. Furthermore, the recessed portion 91b may penetrate the lower back support portion 73 in the first direction D1.

[0133] Next, the effects obtained from the cushion 81 according to the fifth modification will be described. As shown in Fig. 19, each ischium support portion 86 has a tapered surface 86h located between an inner wall 86c of the through hole 86b that defines the through hole 86b and the upper surface 64b of the buttocks support portion 64. Therefore, the tapered surface 86h is provided between the inner wall 86c of the through hole 86b and the upper surface 64b of the buttocks support portion 64, so that the inner wall 86c of the through hole 86b smoothly connects to the upper surface 64b of the buttocks support portion 64 via the tapered surface 86h. Therefore, when the user sits on the seat portion 62, the ischium E6 that has entered the through hole 86b can be gently supported by the tapered surface 86h, further reducing the force acting on the ischium E6.

[0134] The sacrum support portion 91 has a protruding surface 91a that protrudes forward and a recessed portion 91b that recesses rearward from the protruding surface 91a. Therefore, the user's sacrum E5 can be supported by the protruding surface 91a while the sacrum E5 can fit into the recessed portion 91b. Therefore, the sacrum E5 is supported from both sides of the recessed portion 91b and pressure on the sacrum E5 can be reduced, so that excessive pressure on the sacrum E5 can be prevented and the sacrum E5 can be gently supported.

[0135] The recessed portion 91b may extend in the third direction D3 and the second direction D2. As shown in Fig. 20, in a plan view, the bottom surface 91c may be curved so as to recess backward as it becomes farther away from the end of the recessed portion 91b in the second direction D2. In this case, the rearward curvature of the bottom surface 91c in a plan view can further relieve pressure on the sacrum E5.

[0136] 23, in a cross section perpendicular to the second direction D2, the bottom surface 91c may be curved so as to recess backward as it becomes farther away from the end of the recess 91b in the third direction D3. In this case, the recess 91b is curved backward in a side view, which can further relieve pressure on the sacrum E5.

[0137] The above describes the embodiment and first to fifth modified examples of the cushion according to the present disclosure. However, the present disclosure is not limited to the above-described embodiment or the first to fifth modified examples, and further modifications may be made within the scope of the gist of the claims. In other words, the shape, size, number, material, and arrangement of each part of the cushion are not limited to the above-described embodiment or various modified examples, and further modifications may be made within the scope of the above-described gist. For example, the cushion according to the present disclosure may be a combination of two or more of the above-described embodiment, the first to fifth modified examples, and various modified examples described below.

[0138] For example, in the above-described embodiment and modified example, a cushion including a seat portion and a lumbar support portion has been described. However, the height of the lumbar support portion can be changed as appropriate. For example, the height of the upper end of the lumbar support portion may be the height of the user's back, the height of the user's shoulders, or the height of the user's head, and is not particularly limited. In this case, the cushion can be used as a chair, such as a gaming chair.

[0139] For example, the cushion may have a foldable lumbar support portion relative to the seat portion. In this case, the cushion can be used as an office chair, a reclining chair, or a full-flat seat. The cushion may also be a seat used in transportation machinery such as automobiles, railroad cars, or aircraft.

[0140] Furthermore, for example, a hard support member may be provided below the seating portion. In this case, the seating portion is less likely to deform, allowing the seating portion to more firmly support the user's buttocks and thighs. A hard support member may be provided at the rear of the lumbar support portion. In this case, the lumbar support portion is less likely to deform, allowing the lumbar support portion to more firmly support the user's lumbar region. The support member may be made of, for example, chipboard or hard resin. The seating portion and the lumbar support portion may be connected to each other by the support member. In this case, too, the cushion can be used as a cushion for a chair such as an office chair.

[0141] The lumbar support portion and the sacral support portion do not have to be integral. For example, the sacral support portion may be detachably joined to the lumbar support portion. For example, the sacral support portion is detachably attached to the lumbar support portion by a joining member. In this case, the sacral support portion joined to the lumbar support portion of one cushion via the joining member is detached, and the sacral support portion is attached to the lumbar support portion of another cushion different from the one cushion. In this way, it is possible to attach and detach the sacral support portion to the lumbar support portions of various cushions. The above-mentioned joining member may be, for example, a hook-and-loop fastener, a hook, or a button, and the type of joining member is not particularly limited.

[0142] In the first modified example described above, cushion 21 made of two-dimensionally cut urethane foam was described as an example of a flexible material. For example, cushion 21 may have a soft layer and a hard layer. For example, cushion 21 may have convex portions 21b and 23b made of a soft layer, and the layer below convex portion 21b and the layer behind lumbar support portion 23 made of a hard layer. In this case, the user's buttocks, thighs, back, and waist can be more firmly supported.

[0143] The inclination angle θ2 of the inclined surface 7 shown in Figures 3 and 15 may be equal to or greater than 0° and less than 5°. In the cushion according to the present disclosure, the upper surface of the seating portion may be parallel to the lower surface of the seating portion. In other words, the seating portion of the cushion according to the present disclosure does not need to have an inclined surface extending obliquely upward from the buttocks support portion toward the thigh support portion.

[0144] As shown in Figures 18 and 21, the above-described modified examples illustrate cushions 61 and 81 that include a pair of thigh support portions 65, each having a recess 65d, and the pair of recesses 65d are provided at positions spaced apart from each other. However, the shape and configuration of the thigh support portion are not limited to the above examples. For example, the cushion may have a single recess that includes the pair of thigh support portions 65. In other words, the pair of thigh support portions 65 may share a single recess. In this case, the pair of recesses 65d described above are connected to each other and formed as a single recess.

[0145] In the above-described modified example, a cushion including an ischial support portion, an inclined portion, and a sacrum support portion was exemplified. However, the cushion may not include an ischial support portion, and may include, for example, only a sacrum support portion 91. In this case, the sacrum support portion 91 has a protruding surface 91a that protrudes forward and a recessed portion 91b that recesses rearward from the protruding surface 91a. Therefore, the user's sacrum E5 can be supported by the protruding surface 91a while the sacrum E5 can fit into the recessed portion 91b, thereby achieving the same effect as the cushion 81 described above.

[0146] Furthermore, the cushion may not have at least one of the inclined portion and the sacrum support portion, and may, for example, be a cushion having only a pair of thigh support portions 65. In this case, each of the pair of thigh support portions 65 has a recess 65d recessed in the thickness direction of the cushion. Therefore, each thigh support portion 65 can be made more easily deformable than the portions of the seating portion other than the thigh support portions 65, thereby achieving the same effect as the cushion 61 described above.

[0147] (Example) Next, a comparative example without a cushion and examples of cushions according to Examples 1, 2, 3, and 4 will be described. Note that the present invention is not limited to the examples described below. In the experiments according to the examples, the pressure distribution of the body pressure applied to a user seated on each cushion or chair was measured, and the maximum pressure and average pressure were calculated. Note that the pressure distribution was measured using a pressure distribution measurement device manufactured by Xsensor.

[0148] The cushion according to Example 1 includes a portion corresponding to sacral support portion 71 of cushion 61, as illustrated in FIG. 13. The cushion according to Example 2 includes a portion corresponding to sacral support portion 91 of cushion 81, as illustrated in FIG. 19. That is, the cushion according to Example 2 differs from the cushion according to Example 1 in that it includes recessed portion 91b. The cushion according to Example 3 includes a portion corresponding to thigh support portion 5 of cushion 1, as illustrated in FIG. 1. The cushion according to Example 4 includes a portion corresponding to thigh support portion 65 of cushion 61, as illustrated in FIG. 13. That is, the cushion according to Example 4 differs from the cushion according to Example 3 in that it includes recessed portion 65d.

[0149] FIG. 24 shows experimental results (measured data) showing the pressure distribution of a comparative example in which a user sat on a chair without a cushion. For ease of understanding, the pressure distribution of a seated user is shown against a black background in FIG. 24 and the measured data in FIGS. 25(a), 25(b), 26(a), and 26(b) described below. In the pressure distribution, areas where high pressure was applied to the user are shown in black, while areas where low pressure was applied to the user are shown in white. In FIG. 24, the left side shows the area corresponding to the ischial bones, and the right side shows the area corresponding to the thighs. As shown in FIG. 24, the comparative example showed a high pressure distribution overall, with pressure concentrated particularly on the user's ischial bones. In the comparative example of FIG. 24, the user experienced a maximum pressure of 167.6 mmHg and an average pressure of 45.8 mmHg.

[0150] FIG. 25(a) shows experimental results (measured data) illustrating the pressure distribution in Example 1. In Example 1, the pressure distribution was measured when a user sat on the cushion according to Example 1. FIG. 25(b) shows experimental results (measured data) illustrating the pressure distribution in Example 2. In Example 2, the pressure distribution was measured when a user sat on the cushion according to Example 2. FIGS. 25(a) and 25(b) show an area X1 corresponding to the sacrum, an area corresponding to the thighs, and an area corresponding to the ischium located between area X1 and the area corresponding to the thighs.

[0151] As shown in Figures 25(a) and 25(b), in Examples 1 and 2, the areas of high pressure were reduced compared to the comparative example in Figure 24, and it was found that the pressure applied to the user's ischial bones was dispersed. In Example 1, the maximum pressure applied to the user was 95.5 mmHg, with an average of 38.7 mmHg. In Example 2, the maximum pressure applied to the user was 100.3 mmHg, with an average of 34.0 mmHg. From the above, it was confirmed that the cushions according to Examples 1 and 2 can disperse the pressure applied to the user's ischial bones.

[0152] It was found that the areas of high pressure were further reduced in Example 2 compared to Example 1, and the pressure applied to the user's sacrum E5 was more dispersed. In area X1 corresponding to sacrum E5 in Example 1, a maximum pressure of 95.5 mmHg and an average pressure of 42.2 mmHg were applied to the user. In area X1 corresponding to sacrum E5 in Example 2, a maximum pressure of 100.3 mmHg and an average pressure of 35.6 mmHg were applied to the user.

[0153] In region X2 on the central side of region X1 corresponding to sacrum E5 in Example 1, an average pressure of 55.0 mmHg was applied to the user. In region X2 on the central side of region X1 corresponding to sacrum E5 in Example 2, an average pressure of 33.1 mmHg was applied to the user. From the above, it was confirmed that the cushion of Example 2, in which the sacrum support portion has a portion corresponding to recessed portion 91b, can better distribute the pressure applied to the sacrum E5.

[0154] FIG. 26(a) shows experimental results (measured data) showing the pressure distribution in Example 3. In Example 3, the pressure distribution was measured when a user sat on the cushion according to Example 3 in a forward-leaning position. FIG. 26(b) shows experimental results (measured data) showing the pressure distribution in Example 4. In Example 4, the pressure distribution was measured when a user sat on the cushion according to Example 4 in a forward-leaning position. FIGS. 26(a) and 26(b) show the pressure distribution in the region corresponding to the thighs.

[0155] 26(a) and 26(b), Example 4 shows a further reduction in the areas of high pressure compared to Example 3, and it was found that the pressure applied to the user's thighs can be further dispersed. In Example 3, the maximum pressure applied to the user was 94.3 mmHg, with an average pressure of 44.8 mmHg. In Example 4, the maximum pressure applied to the user was 83.8 mmHg, with an average pressure of 41.8 mmHg. From the above, it was confirmed that the cushion of Example 4, in which the thigh support portion has a portion corresponding to recess 65d, can more significantly disperse the pressure applied to the thighs. [Explanation of symbols]

[0156] 1...Cushion, 1b...Bottom surface, 2...Seating area, 3...Lumber support area, 3b...Front end, 3c...Slanted surface, 4...Buttock support area, 4b...Top surface, 4c...Bottom part, 5...Thigh support area, 5b...Top part, 5c...Curved part, 6...Ichial bone support area, 6b...Concave part, 6c...Corner part, 6d...Long axis, 6f...Short axis, 6g...Center , 6h...Curved surface, 7...Slanted surface, 8...Convex part, 8b...Top part, 8c...Slanted part, 9...Protrusion part, 9b...Top part, 9c...Slanted part, 10...General part, 10b...First part, 10c...Second part, 10d...Inner surface, 10f...Outer surface, 10g...Concave part, 10h...Front surface, 11...Sacral support part, 11b...Long axis, 11 c...short axis, 11d...upper end, 11g...protruding surface, 11h...center, 12...lumbar support portion, 13...iliac support portion, 21...cushion, 21b...convex portion, 21c...slit, 21d...lower surface, 21f...straight portion, 21g...extended portion, 22...seating portion, 22b...upper slit, 22c...straight portion, 22d...extended portion, 23...lumbar support portion, 23b...convex portion, 23c...slit, 23d...rear surface, 23f...straight portion, 23g...extended portion, 23h...front slit, 23j...narrow portion, 23k...extended portion, 24...buttock support portion, 24b...upper surface, 25...thigh support portion, 26...ischium support portion, 27...slit slit, 27b...curved portion, 27c...expansion portion, 28...deformed portion, 29...inclined surface, 31...sacrum support portion, 32...lumbar support portion, 41...cushion, 43...lumbar support portion, 44...convex portion, 44b...front surface, 51...cushion, 52...protruding portion, 61...cushion, 61b...underside, 62...seating portion, 62a...ventilation hole, 64...buttocks support portion, 64b...upper surface, 65...thigh support portion, 65d...recess, 65e...top, 65f...inclined portion, 66...ischium support portion, 66b...through hole, 70...general portion, 70b...first portion, 70f...outer surface, 70h...front surface, 71...sacrum support portion, 71a...protruding surface , 73...lumbar support portion, 74...convex portion, 86...ischial support portion, 86b...through hole, 86c...inner wall, 86e...curved surface, 86h...tapered surface, 91...sacrum support portion, 91a...protruding surface, 91b...depression portion, 91c...bottom surface, 91d...inner surface, B...space, D1...first direction, D2...second direction, D3...third direction, D4...long axis direction, D5...short axis direction, E1...spine, E2...pelvis, E3...ilium, E4...pubis, E5...sacrum, E6...ischial bone, G1, G2...group of convex portions, L1, L2...extension line, L3...imaginary line, P...intersection portion, S...placing surface, X1, X2...area, θ1...intersection angle, θ2...inclination angle.

Claims

1. A cushion made of a flexible material, The seat includes a buttocks support portion on which a user's buttocks are placed, and a thigh support portion on which the user's thighs are placed, the buttocks support portion has a pair of ischial support portions aligned along the left-right direction as seen from the user seated on the seat portion, Each of the ischial support portions has a recess that is recessed from the upper surface of the buttock support portion when the ischial bone is placed on it, the curvature of each recess is greater than the curvature of the upper surface; the seating portion has an inclined surface extending obliquely upward from the buttocks support portion toward the thigh support portion, The shape of each of the ischial support portions in a plan view extends in a long axis direction and a short axis direction intersecting the long axis direction, and the length in the long axis direction is longer than the length in the short axis direction, Extension lines of the pair of long axes of the pair of ischial support portions intersect with each other at a position closer to the thigh support portion than the pair of ischial support portions. cushion.

2. A cushion made of a flexible material, The seat includes a buttocks support portion on which a user's buttocks are placed, and a thigh support portion on which the user's thighs are placed, the buttocks support portion has a pair of ischial support portions aligned along the left-right direction as seen from the user seated on the seat portion, Each of the ischial support portions has a through-hole that passes downward from an upper surface of the buttock support portion, the seating portion has an inclined surface extending obliquely upward from the buttocks support portion toward the thigh support portion, The shape of each of the ischial support portions in a plan view extends in a long axis direction and a short axis direction intersecting the long axis direction, and the length in the long axis direction is longer than the length in the short axis direction, Extension lines of the pair of long axes of the pair of ischial support portions intersect with each other at a position closer to the thigh support portion than the pair of ischial support portions. cushion.

3. Each of the ischial support portions has a tapered surface located between an inner wall of the through hole defining the through hole and an upper surface of the buttock support portion. The cushion of claim 2.

4. a lumbar support part that contacts the lumbar part of the user from behind, The lumbar support portion has a convex sacrum support portion that supports the user's sacrum from behind. A cushion according to any one of claims 1 to 3.

5. the sacral support portion has a protruding surface; The protruding surface has a curved surface shape that protrudes forward. The cushion of claim 4.

6. The lumbar support portion has a lumbar support portion that supports the lumbar vertebrae of the user from behind above the sacral support portion.

6. The cushion according to claim 4 or 5.

7. The lumbar support portion has an ilium support portion that supports the ilium of the user on both the left and right sides of the lumbar support portion as seen from the user seated on the seat portion. The cushion of claim 6.

8. The intersection angle between the extension lines of the pair of long axes is 40° or more and 150° or less. A cushion according to any one of claims 1 to 7.

9. the thickness of the thigh support portion when the user is seated on the seat is thinner than the thickness of a portion of the seat other than the thigh support portion when the user is seated on the seat; A cushion according to any one of claims 1 to 8.

10. a deformation amount of the thigh support portion when the user sits on the seating portion is larger than a deformation amount of a portion of the seating portion other than the thigh support portion when the user sits on the seating portion; A cushion according to any one of claims 1 to 9.

11. The thigh support portion has a recess that defines a space between the thigh support portion and a support surface on which the cushion is placed.

11. The cushion according to claim 9 or 10.

12. The projected area of ​​the lower surface of the cushion is smaller than the projected area of ​​the cushion in a plan view. A cushion according to any one of claims 1 to 11.

Images