TW202011876A - Sitting cushion and sitting surface of chair capable of keeping correct sitting posture and providing excellent sitting feeling and stability - Google Patents

Abstract

The present invention provides a sitting cushion, which focuses on a sitting surface for supporting most of the body weight of the sitter and the sitting surface may guide the sitter into a correct sitting posture during sitting, keep the correct sitting posture and provide excellent sitting feeling and stability. The sitting cushion of the present invention is provided with a sitting surface body composed of flexible plate material, wherein the sitting surface body is configured with a sitting deformation portion composed of a plurality of incision lines that are incised along a depth direction. The sitting deformation portion is provided with an ischium supporting portion composed of spiral, concentric, or concentrically polygonal incision lines arranged at the positions corresponding to the ischium of the sitter; and, a hip/rear-thigh supporting portion composed of incision lines arranged as surrounding the outer peripheries of spiral, concentric or concentrically polygonal incision lines.

Description

Cushion for seating and seat surface for chair

The present invention relates to a cushion for seating used on a seating surface such as a chair and the seating surface of a chair, and particularly to a cushion for seating and a chair that can maintain a correct posture (excellent posture) of a seat Seat surface.

In recent years, due to technological innovations such as computers and information communication or changes in life styles, the time spent in seats such as sitting in chairs has been prolonged in work and daily life. Compared with standing upright posture, it is more difficult to maintain the position of the back bone or pelvis in a proper position while sitting in a chair. Therefore, long-term seating postures are prone to problems such as bone skew or low back pain, stiff shoulders, and reduced visceral function, which have a great impact on health. In addition, poor seating posture has also been noted to reduce concentration. Therefore, various posture correctors for taking a correct posture when seated have been proposed.

For example, Patent Document 1 proposes a cushion for holding a pelvis in a normal position, including a back stretching portion, a thoracic/lumbar support portion, and a pelvic receiving portion, which are placed on the backrest and back of a chair Cushions between beams. In addition, Patent Document 2 proposes a pelvic cushion in which the pelvis can be erected to be in a correct posture, and a backrest having an integral standing portion with a seat is proposed. A pelvic cushion that presses the pressing body in the center of the pelvis of the seated person. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2006-95262 [Patent Document 2] Japanese Patent Application Publication No. 2017-113372

[Problems to be solved by the invention] The seat posture of the seated person also has internal factors such as the physical characteristics or health status of the seated person, but it is guided by external factors such as the backrest and seating surface of the seated person, that is, the chair, the floor surface on which the foot is on the ground, etc. lead. Among them, the "seating surface" of the seated object supports about 80% of the weight of the seated person, so the influence of the seat on the seating posture can be described as large. In this regard, the cushions described in Patent Document 1 and Patent Document 2 are all developed with a focus on the seat surface of the “backrest” rather than the seating object, and mainly relate to the structure of the backrest.

Therefore, an object of the present invention is to provide a cushion for seating and a seating surface for a chair that focuses on the "seating surface" that supports most of the weight of the occupant, having a correct seating posture when seated, and maintaining the correct seating The posture, and the seating surface with a good sitting feeling and a sense of stability.

[Means to solve the problem] As a result of careful research to solve the above-mentioned problems, the present inventor found the following situation. The correct seating posture refers to a state where the pelvis P does not fall to the rear side as shown in FIG. 12 and the pelvis P stands (erects). At this time, the center of gravity is located in the supporting base surface G between the pelvis P and the sole of the foot on the floor, which is well balanced and stable. On the other hand, the bad seating posture refers to the posture of the pelvis leaning back toward the back, when the center of gravity becomes behind the pelvis far away from the center of the body, thus forming an unstable posture. Therefore, because he wants to stretch his head forward to achieve balance, he adopts a hunchback posture with bent back bones. Here, in the pelvic forward posture in which the pelvis P tends to the front side, the center of gravity is located in the supporting base plane G, so the balance is more stable than the pelvic posture posture. At this time, if the balance is to be more stable, the entire upper body is turned to the rear side, thereby becoming a posture in which the pelvis P stands (erected). From these situations, it can be known that by guiding the pelvic upright posture or the pelvic forward posture during seating, the correct seating posture can be guided. In addition, it can be seen that the posture of the pelvis is related to the rigidity (hardness) of the seat surface. The greater the rigidity (harder) of the seat surface, the easier it is to be guided into the forward pelvic posture, and the less rigid (softer) the seat surface, the easier it is. Guided to the pelvic posture. However, if you want to guide the pelvic forward posture and choose a rigid and hard seating surface, the hard seating surface has a small contact area when seated, so it is difficult to continue to maintain the pelvic forward posture and the posture remains unstable. From these circumstances, it is considered effective to stabilize the forward tilting position of the pelvis when sitting, to increase the rigidity of the seat surface, and to increase the contact area when sitting. When increasing the contact area during seating, reducing the rigidity (softening) of the seat surface is also considered effective, but if the seat surface is made soft, the angle of the pelvis is not easy to be fixed, and the pelvis is guided backward as described above The posture becomes poor, so the rigidity of the seat surface and the contact area are in a trade-off relationship. Therefore, further research based on this knowledge has found a means to achieve both the rigidity of the seating surface and the contact area, and to achieve the formation and maintenance of the pelvic forward tilt posture, so that the present invention has been completed.

In order to solve the above-mentioned problems, the cushion for seating of the present invention is a cushion for seating provided with a seating surface body composed of a flexible plate-like material, and the seating surface body is provided with a thickness direction A seated deformation part formed by a plurality of cut-in lines cut in, the seated deformation part having: a spiral-shaped, concentric circle-shaped or concentric polygon-shaped cut-in line arranged at a position corresponding to the ischium of the seated person The ischial support portion; and the buttocks/thigh rear support portion configured by the cut-in line and configured to surround the outer circumference of the spiral, concentric or concentric polygonal cut-in line.

As a result, the seated deformed portion formed in the seat surface body is pushed out and deformed downward following the figure or weight of the seated person. Among them, the "ejection deformation" includes: the seated deformation portion under load is pushed out and deformed by sliding the seat surface body downward according to the cut-through line in the thickness direction, and the seated deformation portion under load is based on non- It is pushed out and deformed by flexing downward through the (half-cut) cutting line. When the sitting deformation portion has a ischium support portion and a hip/thigh rear support portion, the ischium support portion disposed at a position corresponding to the seatbone's ischium is guided in such a manner as to guide the seater's pelvis to the correct seat posture The deformation is pushed out, and the buttocks/thigh support placed on the outer circumference of the ischial support will increase the area of contact between the seated body of the seater's buttocks/thigh and stabilize the seat posture, and also improve seating feel. Therefore, since the seated person is guided to the correct seat posture and the seat posture is stabilized, the seated person can maintain the correct seat posture for a long time.

In addition, it is also preferable that the plurality of cutting lines constituting the seating deformation portion of the seating surface body of the seating cushion form a line-symmetrical cutting pattern shape with respect to the center line in the width direction of the seating surface body. As a result, the cut-in lines are arranged symmetrically, so that the deformation of the seated deformation portion with a good balance between the left and the right is performed.

In addition, it is also preferable that among the plurality of cutting lines constituting the seating deformation portion of the seating surface body, the cutting lines constituting the ischial support portion be arranged separately from the center line in the width direction of the seating surface body. Thereby, when the seated person is sitting on the seat surface body, the center of gravity is moved to the left or right, etc., and even in the case where the load applied to the ischial support portion changes left and right, it can be configured to only increase the portion where the load load has increased Push the deformation downward. Therefore, the adaptability of the sitting person's ischium and the ischium supporting portion is improved, the sitting person's ischium can be stably supported, and the correct seating posture can be maintained.

Furthermore, it is also preferable that at least a part of the cutting lines constituting the buttocks/thigh rear support part among the plurality of cutting lines constituting the seating deformation portion of the seating surface body are connected at the center line in the width direction of the seating surface body Configuration. Thereby, the area of contact of the seated person's buttocks/thighs and the seat surface body is greater, the seat posture is stabilized, and the feeling of sitting can also be improved.

In addition, it is also preferable that the plurality of cutting lines constituting the seating deformation portion of the seating surface body be curved lines. Thereby, since the seat surface body is easily pushed out and deformed smoothly, the seat surface body is pushed out and deformed due to the load of the seated person.

In addition, it is also preferable that the plurality of cutting lines constituting the seating deformation portion of the seating surface body pass through the thickness direction of the seating surface body. Thereby, the pushing-out deformation of the seat surface body proceeds more smoothly, so that the pushing-out deformation of the seat surface body following the shape of the seated person is realized.

In addition, it is also preferably a synthetic resin foam having a plate-like material system E hardness (according to JIS K6253) constituting the seat surface body and a hardness of 5 to 80. Thereby, in a state where the seating deformation portion of the seating surface body follows the physique or weight of the seating body to push out the deformation and is guided to the correct seating posture, further deformation of the upper surface of the seating surface body is suppressed, so the angle of the pelvis is fixed , Can maintain a more stable seat posture.

In addition, the cushioning pad for seating of the present invention preferably has a seat surface support body laminated on the lower surface side of the seat surface body. The seat surface support body is synthesized from a softer material than the plate-like material constituting the seat surface body. At least one material selected from the group consisting of a resin foam, a stretchable sheet, and a stretchable mesh sheet. In this way, the amount of deformation of the seat surface body under load can be adjusted by the seat surface support body. In addition, when the seat occupant stands up and becomes unloaded on the cushion, the seat surface support body is pushed back to the deformed portion of the seat surface body. Therefore, the deformation of the seat surface body is easily restored and the surface is formed flat The state can be prepared for the load caused by the next seating.

In addition, it is also preferable that the hardness of the synthetic resin foam constituting the seat surface support is 50 to 400 N (according to JIS K6400-2 A method). By this, those who are suitable as synthetic resin foams constituting the seat surface support are selected.

In addition, the seat surface for a chair of the present invention is a seat surface for a chair provided with a seat surface body composed of a flexible plate-shaped material, and a plurality of cuts cut in the thickness direction are provided on the seat surface body A seating deformation part composed of a wire, the seating deformation part having: a ischial support part composed of a spiral, concentric circle or concentric polygonal cutting line arranged at a position corresponding to the ischium of the seated person; and The buttocks/thigh rear support portion constituted by the cut-in line is arranged so as to surround the outer circumference of the spiral-shaped, concentric-shaped or concentric polygon-shaped cut-in line. As a result, the seated deformed portion formed in the seat surface body is pushed out and deformed downward following the figure or weight of the seated person. When the sitting deformation portion has a ischium support portion and a hip/thigh rear support portion, the ischium support portion disposed at a position corresponding to the seatbone's ischium is guided in such a manner as to guide the seater's pelvis to the correct seat posture The deformation is pushed out, and the buttocks/thigh support placed on the outer circumference of the ischial support will increase the area of contact between the seated body of the seater's buttocks/thigh and stabilize the seat posture, and also improve seating feel. Therefore, it is possible to guide the occupant to the correct seat posture, stabilize the seat posture and maintain the correct seat posture

In addition, it is also preferable that the plurality of cutting lines constituting the seating deformation part of the seating surface body of the chair seating surface form a line-symmetrical cutting pattern shape with respect to the center line in the width direction of the seating surface body; Among the multiple cutting lines of the part, the cutting lines constituting the ischial support part are arranged separately from the center line in the width direction of the seat surface body; among the plural cutting lines constituting the sitting deformation part, constitute the buttocks/thigh support At least a part of the cut-in line is arranged to be connected at the center line in the width direction of the seat surface body; a plurality of cut-in lines pass through the thickness direction of the seat surface body; a seat surface support body is stacked on the lower surface side of the seat surface body The surface support is composed of at least one material selected from the group consisting of a synthetic resin foam that is softer than the plate-shaped material that constitutes the seat surface body, a stretchable sheet, and a stretchable mesh sheet.

[Effect of invention] According to the present invention, it is possible to provide a cushion for seating and a seat surface for a chair having excellent effects as shown below. (1) The seated person can be guided to the correct seat posture, and the seat posture can be stabilized while maintaining the correct seat posture. (2) The contact area with the seating surface body is large, so the stability is high and the sitting feeling is good. (3) The seat surface body is obtained by providing a predetermined cut-in line in the flexible plate-like body, so it can be manufactured simply and inexpensively.

The embodiment of the cushioning pad for seating of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the seat cushion 1 of the first embodiment is formed by laminating a flat seat surface body 2 and a flat seat surface support body 6 on the lower surface side. Here, the up-down direction in this specification refers to the up-down direction in a state where the seating cushion 1 is installed on a chair, floor, etc., that is, the up-down direction in FIG. 1, and the left-right direction in this specification refers to the use of seating The left-right direction in the state where the cushion 1 is used is the same as the width direction of the cushion 1 for seating. In addition, in the use direction of the seat cushion 1, the back side in FIGS. 1 and 5 is the thigh (leg) direction, and the front side is the buttocks direction.

The seating surface body 2 constituting the seating cushion 1 of this embodiment will be described in detail below. As shown in FIGS. 1 to 5, the seating surface body 2 of the seating cushion 1 of the present embodiment is formed of a plate-like material having a predetermined thickness, and the seating surface body 2 is provided with a plurality of cuts penetrating in its thickness direction Line 3. The incision line 3 consists of a spiral ischium support incision line 3a arranged at a position corresponding to the seat bone H of the seated person, and an arc-shaped buttocks/thigh arranged around the outer circumference of the spiral incision line 3a The rear support portion is formed by a cut line 3b. The plurality of cutting lines 3 provided in the seating surface body 2 form a seating deformation portion 4 that pushes out and deforms downward following the weight or shape of the seated person, more specifically, the cutting line is cut by the ischial support portion 3a, the ischial support part 4a is formed, and the buttocks/thigh support part 4b is formed by cutting the line 3b with the buttocks/thigh support part.

The plate-like body forming the seat surface body 2 in the present invention is not particularly limited if it is a flexible material, and a resin foam, a synthetic resin board, and a synthetic wood board are suitable for use. Among them, the resin foam is appropriately selected from the viewpoint of being lightweight and easy to handle, and also easy to perform seam processing. Specifically, for example, polyethylene foam, polyurethane foam, polyolefin foam, or silicone foam is suitable. In addition, in the present invention, the plate-like body forming the seat surface body 2 is suitable for selecting the hardness from the viewpoint of preventing the pelvic backward posture from sitting, guiding the pelvic upright posture or the pelvic forward posture and stably maintaining the posture It is larger than the cushion material used in cushions for general seating. Specifically, the type E hardness measured according to JIS K6253 is preferably 5 to 80, preferably 10 to 70, and particularly preferably 20 to 60. By forming into this hardness range, the deformation of the upper surface of the seat surface body is suppressed when the seating deformation portion 4 is pushed out and deformed downward and guided to the correct seat posture, so the angle of the pelvis is fixed and it is more stable Maintain the seat posture. In this embodiment, as an example, the seat surface body 2 is formed of a polyethylene foam having an E hardness of 40 (in accordance with JIS K6253). The seat deformation body 4 is pushed downward to deform and the upper surface of the seat body 2 is deformed into a shape matching the shape of the seat bone or hip/thigh of the seat person, and the seat body is formed from the viewpoint of supporting the posture of the seat person The thickness of the plate-like body of 2 is preferably 10 mm or more, and more preferably 15 mm to 30 mm.

Next, the ischial support part 4a and the ischial support part cutting line 3a forming the same will be described. FIG. 2 shows the cut line 3a of the ischium support part forming the ischium support part 4a in solid lines among the multiple cut lines 3 provided in the seat surface body 2, and the buttocks forming the buttocks/thigh support part 4b in broken lines/ An explanatory view of the cut line 3b of the thigh rear support part. As shown in FIG. 2, the ischium support portion 4a of the seat surface body 2 is arranged at a position corresponding to the ischium H of the seated person, and is configured to support the ischium H of the seated person. The ischia support portion 4a is formed by a cutting line 3a penetrating in the thickness direction of the seat surface body 2. The ischia support portion 4a in the present embodiment is formed by a pair of spiral ischia support portion cutting lines 3a. As a result of the load caused by the sitting, the ischia support part 4a formed by the ischia support part cut-in line 3a follows the shape of the ischial bone of the seated person and is pushed out downward. As a result, the upper surface of the seat surface body 2 is deformed into The pelvis of the seater is in an upright or forward-leaved state, stably supports the sciatic bone H of the seater, and suppresses backward tilt of the pelvis. The greater the rebound resilience (equivalent to hardness) of the ischium support 4a after being pushed out of deformation, the more pronounced the pelvic recline suppression effect. The rebound resilience after being pushed out of deformation can be adjusted by the pattern of the line 3a cut into the ischial support. The ischium support portion 4a is formed to correspond to the size of the ischium H of the seated person, and is preferably formed with a width in the range of 150 mm to 250 mm as the size in the width direction, and a size in the range of 70 mm to 150 mm as the size in the depth direction, for example. Furthermore, in this embodiment, the pair of spiral cut lines 3a constituting the ischium support portion 4a are preferably arranged as shown in FIG. 2 so that the distance between the two spiral-shaped centers M corresponds to the ischium of the seated person The length L between the most protruding parts of the ischial tuberosity I of H. The length L between the most protruding parts of the ischial tuberosity I changes according to gender or physique, etc. Generally, it is about 80 mm to 140 mm, and the user can also arrange them in a plurality of sizes in advance according to the size of their ischium As an option, it can also be customized according to each user. In addition, the band-shaped portion 5 is formed between the spiral cut line 3a and the adjacent line, but if the interval of the cut line 3a is too narrow, the spiral line becomes denser and the hardness of the ischial support portion 4a becomes smaller (the amount of pushing out deformation becomes larger) ), therefore, the sitting posture becomes unstable, and if the interval between the cut-in lines 3a is too wide, the width of the band 5 becomes too wide, and the ischial support 4a becomes difficult to push out and deform, resulting in poor adaptability to the body From a viewpoint, the width of the band 5 is preferably 5 mm to 50 mm, and preferably 10 mm to 30 mm. In addition, it is preferable that both end portions of the ischium support part cut-in line 3a do not reach the outer peripheral end of the seat body 2 so that the ischium support part 4a does not separate from the seat body 2. Wherein, if the ischial support portion 4a is not separated from the seating surface body 2, the outer end of the ischial support portion cutting line 3a can also reach the outer peripheral end of the seating surface body 2.

As shown in FIG. 2, the ischium support part incision line 3 a in the present embodiment has a line-symmetrical incision pattern shape with respect to the center line S of the seat surface body 2 in the width direction. As a result, since the cut-in line 3a is arranged symmetrically left and right, the ischium support portion 4a is pushed out and deformed in a balanced manner, and the seatbone of the occupant is stably supported. In addition, as shown in FIGS. 2 and 4(c), the ischium support part cut line 3a in the present embodiment is arranged apart from the center line S of the seat surface body 2 in the width direction. This makes it possible to increase the load only when the load applied to the ischial support portion 4a is changed from side to side when the seated person moves the center of gravity to the left or right while sitting on the seat surface body 2 or the like. The part is pushed out and deformed downward. Therefore, the adaptability of the sitting person's ischium to the ischium supporting portion 4a is improved, and the sitting person's ischium can be stably supported.

In addition, as shown in FIG. 2, the ischium support part 4a and the ischium support part cut line 3a formed in this embodiment are formed into a pair of spiral cut-out pattern shapes, and the spiral shape selection is caused by one curve The spiral pattern is more than two layers, but a spiral cut pattern, a concentric circular pattern, or a concentric polygonal cut pattern other than the shape shown in FIG. 2 may be selected as the cut pattern shape having the same effect as described above. As an example, FIGS. 6 and 7 show other cutting pattern shapes of the cutting line 3a of the ischial support portion. In FIGS. 6 and 7, as in FIG. 2, the solid line represents the ischium support cut-in line 3 a forming the ischium support 4 a, and the broken line represents the hip/thigh forming the hip/thigh rear support 4 b The rear support cuts into the line 3b. For example, FIG. 6(a) shows a pair of spiral cut lines connected to the center line S of the width direction of the seat body 2 as a cut pattern of the ischial support part cut line 3a, and FIG. 6(b) shows a pair of cut patterns. The helical cut into the pattern shape, but the helical shape is composed of a plurality of curves and is not a spiral of one layer, as the ischial support part cut line 3a. In addition, Fig. 6(c) shows that the spiral line is composed of a broken line. In addition, FIG. 6(d) and FIG. 6(e) show an example of a shape in which the ischium support part cut line 3a is formed as a concentric circle cut pattern, and two concentric circles are connected near the center line S in the width direction. Shape cut into pattern shape. In the cut pattern shapes shown in FIGS. 6(d) and 6(e), the ischial support part cut line 3a is not constituted by a pair of cut patterns, and is formed as an integrated cut pattern. In addition, FIG. 7(a) shows an example in which the ischium support part cut line 3a is formed as a pair of concentric circle cut patterns, and FIG. 7(b) shows that the ischium support part cut line 3a is formed by forming a spiral and a concentric circle. A pair of cut patterns formed by combination. In addition, FIGS. 7(c) and 7(d) show an example where the ischium support part incision line 3a is formed into a concentric polygonal incision pattern shape. Among them, the ischium support part cut-in line 3a is preferably formed as a cut-in line penetrating through the thickness direction of the seat surface body 2 so that the ischium support part 4a follows the shape of the seatbone of the seated person to be pushed out and deformed smoothly downward, but it may also be formed It is a half tangent that does not partially or entirely penetrate the thickness direction of the seat surface body 2. For example, if the cut line 3a of the ischial support is a cut pattern that includes concentric circles or concentric polygonal shapes (eg, Figure 6(d), Figure 6(e), and Figure 7(a)~(d)), the cut The thread 3a is partially or entirely formed as a half-tangent line, thereby preventing the ischial support portion 4a from falling out of the seat surface body 2 during use. Among these, if it is formed as a half tangent line, it is preferable to provide a half tangent line on the lower surface side of the seat surface body 2 so that the ischial support portion 4a is easily deformed or pushed out.

Next, the buttocks/thigh support side 4b and the buttocks/thigh support side cutting line 3b forming the same will be described. Fig. 3 shows a cut line 3b of the buttocks/back thigh support forming the buttocks/thigh support 4b in solid lines among the multiple cut lines 3 provided in the seat surface body 2, and a sciatic support formed by broken lines An explanatory view of the line 3a of the ischial support of the portion 4a. As shown in FIG. 3, the buttocks/thigh support 4b of the seat surface body 2 is disposed on the outer periphery of the ischium support 4a, and is configured to support the buttocks and thigh rear of the seated person. The buttocks/thigh rear support portion 4b is formed by a cut line 3b penetrating in the thickness direction of the seat body 2, and the buttocks/thigh rear support portion 4b in this embodiment is formed by surrounding a pair of spiral ischium support portions The cutting line 3a is formed by a plurality of arc-shaped buttocks/thigh rear support cutting lines 3b. In addition, the buttocks/thigh support 4b includes a buttocks support portion 4b2 disposed at a position corresponding to the seated person's buttocks, and a thighs rear support portion 4b1 disposed at a position corresponding to the seated person's thighs. The buttocks/thigh support 4b formed by the buttocks/thigh support cut-in line 3b is pushed out and deformed downward following the shape of the seated person's buttocks and thighs due to the load due to seating Therefore, it is deformed to match the shape of the occupant's body shape to increase the contact area between the occupant's hips/thighs and the seat surface body 2 to stabilize the seat posture and improve the feeling of sitting. The buttocks/thigh-back support portion 4b is formed to correspond to the size of the seated person's buttocks and thighs, preferably, for example, a range of 200 mm to 500 mm in the width direction, and a size of 200 mm to 400 mm in the depth The size of the direction. In addition, a strip 5 is formed between the cut-in line 3b and the adjacent line, but if the interval between the cut-in line 3b is too narrow, the interval between the lines becomes denser and the hardness of the buttocks/thigh support 4b becomes smaller The amount of deformation becomes larger), so the sitting posture becomes unstable. If the interval between the cut-in lines 3b is too wide, the width of the band becomes wider, and the buttocks/thigh support 4b becomes difficult to push out and deform, which may affect the body. From the viewpoint of poor adaptability, 5 mm to 50 mm is preferred, and 10 mm to 30 mm is preferred. In addition, it is preferable that both end portions of the buttocks/thigh rear support cut-in line 3b do not reach the outer peripheral end of the seat surface body 2 so that the buttocks/thigh rear support portion 4b is not separated from the seat surface body 2 Fall off. However, if the buttocks/thigh-back support portion 4b does not separate from the seating surface body 2, one of the end portions of the buttocks/thigh-back support portion cutting line 3b can also reach the outer peripheral end of the seating surface body 2.

As shown in FIG. 3, the buttocks/thigh rear support cut-in line 3b in this embodiment has a cut-out pattern shape in which a circular arc is arranged symmetrically with respect to a center line S of the seat surface body 2 in the width direction. Thereby, since the cut-in line 3b is arranged symmetrically left and right, the buttocks/thigh rear support portion 4b is pushed out and deformed in a left-right balance, and the buttocks or thighs of the seated person are stably supported. In addition, as shown in FIGS. 3 and 4(c), among the plurality of cut-in lines 3b constituting the buttocks/thigh support 4b in this embodiment, the thigh support 4b1 supporting the back of the thigh is formed The cut-in line is arranged to be connected to the center line S in the width direction of the seat surface body 2. Thereby, the area of contact between the back side of the thigh of the seated person and the seat surface body 2 is increased, the feeling of sitting is improved, and the seat posture can be stabilized.

The buttocks/thigh support 4b shown in this embodiment and the buttocks/thigh support support cut line 3b formed thereon are selected as shown in Fig. 3: the cut pattern is arranged at predetermined intervals to surround the spiral ischium A plurality of curves on the outer periphery of the support part cut-in line 3a are arranged symmetrically with respect to the center line S of the seat surface body 2 in the width direction. Specifically, the shape of the cut pattern is to arrange two C-shaped arcs from the side close to the cut line 3a of the ischium support portion, and is not connected to the inverted C-shaped arc symmetrically arranged with respect to the center line S line On the other hand, the five arc-shaped curves that are separated from the center line S and that are arranged outside the C-shaped arc are connected to the arcs that are symmetrically arranged with respect to the center line S, and as a result, five are arranged. The overall shape is a substantially M-shaped curved cut pattern. As shown above, in this embodiment, the cut-in pattern shape composed of the above-mentioned plural arc-shaped curves is selected, but the cut-in pattern shape other than the shape shown in FIG. 3 may also be selected as having the same as above The effect of the cut into the pattern shape. As an example, FIG. 8 shows another cut pattern shape of the cut line 3b of the buttocks/thigh support. Among them, in FIG. 8, as in FIG. 3, FIG. 3 is a solid line indicating a hip/thigh support 4b cutting line 3b forming a buttock/thigh support 4b, and a sciatic support 4a forming a dashed line. The ischial support cuts into the line 3a. For example, in FIGS. 8(a) and 8(b), the following example is shown: showing a C-shaped arc symmetrically arranged with respect to the center line S of the width direction of the seat surface body 2 near the center line S The shape of the connected cut-in pattern is used as the buttocks/thigh support section cut-in line 3b. In FIG. 8(a), the C-shaped buttocks/thigh support section cut-in line 3b is the front side (buttock support section 4b2) Side) are connected to form two substantially inverted M-shaped curves, and the arc-shaped curves on the back side (thigh back support portion 4b1 side) are respectively connected to form five overall substantially M-shaped curves The curve of Fig. 8(b) shows that three C-shaped buttocks/thigh rear support cut-in lines 3b are connected to only one of the back side (only the thigh rear support 4b1 side) to form a whole A substantially M-shaped curve is formed, and the arc-shaped curves on the back are connected to form three substantially M-shaped curves as a whole. In addition, in FIG. 8(c), it is shown that only a C-shaped arc line is symmetrically arranged, and only one of the back side (thigh back support portion 4b1 side) is connected to form one The overall shape of the cut pattern is a substantially M-shaped curve as the cut line 3b of the buttocks/thigh support. In FIG. 8(d), the structure is almost the same as that of FIG. 8(c), but the cut line is not An example of a curve formed by a polyline. In addition, in FIGS. 8(e) and 8(f), an example of a cutting pattern in which any cutting line is arranged separately from the center line S is shown as a cutting line 3b for the buttocks/thigh support. As shown above, the buttocks/thigh rear support part cut-in line 3b may be formed into a cut-in pattern shape by individually or combining C-shaped or arc-shaped curves or fold lines. In addition, the buttocks/thigh rear support cut-in line 3b is preferably formed as a cut-through line penetrating the thickness direction of the seat surface body 2 so that the buttocks/thigh back support 4b follows the seated hip or thigh shape The deformation is smoothly pushed out from below, but it may be formed as a half-tangent that does not partially or entirely penetrate the thickness direction of the seat body 2. For example, among the buttocks/thigh support 4b, only the part or the entire cut line 3b corresponding to the back side of the thigh back support 4b1 may be formed as a half tangent. In addition, if it is formed as a half tangent line, it is preferable to provide a half tangent line on the lower surface side of the seat surface body 2 so that the buttocks/thigh rear support portion 4b is easily deformed or pushed out.

Next, the seat surface support 6 that constitutes the seat cushion 1 of the present embodiment will be described. The seat surface support 6 of the seat cushion 1 of the present embodiment is a flat cushion material stacked on the lower surface side of the seat surface body 2 described above. The seat surface support 6 also has a function of pushing out deformation of the seat deformation body 4 of the seat surface body 2 located on the upper layer, and adjusting the amount of pushing deformation of the seat surface body 2 (easy deformation degree, that is, appearance hardness) ; When the seated state is released, the seat deformation body 4 pushed out and deformed below the seat body 2 is pushed back upward, and the function of restoring the deformed shape of the seat body 2; and stably supporting the load of the seated person And the function of improving the seating feeling of the seated person. The material constituting the seat surface support body 6 can be pushed out and deformed by the seat deformation body 4 of the seat surface body 2, so the material that is softer and less stiff than the seat surface body 2 or stretchable deformable material is selected The material is appropriately selected from synthetic resin foam, stretchable sheet, and stretchable mesh sheet. Specifically, in the case of a synthetic resin foam, the hardness measured according to the JIS K6400-2 A method is preferably 50 to 400N, preferably 100 to 300N, and particularly preferably 120 to 250N. Since the hardness of the material is in this range, the above-mentioned functions are more effectively exerted. The stretchable sheet or stretchable mesh sheet selected as the seat surface support 6 is not particularly limited as long as it can exhibit the above-mentioned functions, but it is deformed by tensile strength, tensile stress, elongation at break, etc. From the point of view, you can choose the appropriate one. As an example, in this embodiment, the seat support 6 is formed of a polyurethane foam having a hardness of 120 N (according to JIS K6400-2 A method). When the seat surface body 2 and the seat surface support body 6 are released from seating, the seat surface support body 6 is pushed back and restored by the pushing deformation caused by the seat deformation body 4 of the seat surface body 2 Function, it is therefore preferable that the two are in close contact with each other. In addition, it is also possible to perform slits and punchings (openings) in the seat surface support body 6 individually to appropriately adjust the area of the seat surface support body 6 that blocks the pushing-out deformation caused by the seating deformation portion 4 of the seat surface body 2 hardness.

After the cushion 1 for seating is formed on a plate-like body such as a resin foam, a THOMSON die having a THOMSON blade forming a plurality of cutting lines 3 is used, and the seat surface body 2 is formed by stamping or other various processing methods. It can be manufactured by stacking it with the seat surface support 6 only. In addition, the seat surface body 2 and the seat surface support body 6 may be laminated together. If the seat surface support body 6 is a stretchable sheet or a stretchable mesh sheet, it is preferably bonded to the seat surface body 2.

Next, referring to FIG. 5, the operation of the cushion 1 for seating according to this embodiment will be described. FIG. 5(a) shows the usage state of the cushion 1 for seating in this embodiment, and FIG. 5(b) shows a cross-sectional view taken along line D-D of FIG. 5(a). As shown in FIG. 5(a), if seated on the seating surface body 2 of the cushion 1 for seating, it is constituted by a cut line 3a of the ischium support portion provided at a position corresponding to the ischium of the seated person The ischia support portion 4a pushes out and deforms downward following the shape of the ischium of the seated person by the load due to seating. As shown in FIG. 5(b), the belt-shaped portion 5 formed between the adjacent cut-in lines 3a slides downward to perform pushing-out deformation. By pushing out and deforming the ischium support portion 4a, the upper surface of the seat surface body 2 stably supports the ischium of the occupant, and is deformed into a shape that can support the pelvis of the occupant in an upright state or a forwardly inclined state. With this, the pelvis of the seated person is restrained from leaning back, and the correct seating posture is maintained. Next, the buttocks/thigh support 4b formed by the buttocks/thigh support cut line 3b follows the shape of the seated person's buttocks and thighs by the load due to seating Push the deformation downward. As shown in FIG. 5(b), the belt-shaped portion 5 formed between the adjacent cut-in lines 3b slides downward to perform the extrusion deformation. By pushing out and deforming the buttocks/thigh support 4b, the upper surface of the seat body 2 stably supports the hips or thighs of the seated person, so that the hips and thighs of the seated person and the seated body 2 The contact area is increased to improve the feeling of sitting. In this way, it is not easy to be tired, and the correct seating posture can be maintained for a long time.

Among them, the seat surface body 2 in this embodiment is formed of a flat plate-shaped body, but it may be formed into a moderately curved shape or a shape formed with irregularities in accordance with the shape of the buttocks or legs. In addition, in the present embodiment, the outer shape of the seat body 2 is rectangular, but any shape such as a circle, an ellipse, or a square can be selected. In addition, the seat surface body 2 may be formed with a plurality of seating deformation portions 4, for example, it may be placed on a bench or bench for use, and the seating deformation portions 4 may be arranged at regular intervals. A plurality of those on the horizontally long seat body 2. In addition, a surface layer formed of a synthetic resin foam or the like may be laminated on the seating surface body 2 within a range that does not impair the function and function of the seating deformation portion 4 of the seating surface body 2 to give a feeling of seating ( Feeling) more improved.

The seat surface 10 for chairs of the second embodiment will be described below. As shown in FIG. 9, the seat surface 10 for a chair according to the second embodiment of the present invention is composed of a laminated flat seat surface body 2 and a flat seat surface support body 6 on the lower surface side. The structures and functions of the seat surface body 2 and the seat surface support body 6 of the seat surface 10 for a chair in the present embodiment are the same as those in the first embodiment described above, and the same effects are obtained. By forming the seat surface of the chair itself to have the same structure as the cushion 1 for seating according to the first embodiment, it is possible to suppress the backward tilt of the pelvis of the seated person and keep the pelvis upright or slightly tilted forward A chair that has the correct seating posture and is not easily fatigued, and can maintain the correct seating posture for a long time. [Example]

The present invention will be described in detail below using examples. The methods for measuring the physical properties of the cushions for seating in the following examples and comparative examples are as follows.

(1) Tilt angle of pelvis Prepare the measuring device shown in Figure 10(a) to measure the tilt angle of the pelvis. The measuring device is a steel tube A that imitates the spine and a hip model C through a universal joint B. In the steel pipe A, a 13 kg flat hammer D is installed at a position 21 cm away from the universal joint B, and a child with a height of 125 cm and a weight of 27 kg (approximately 8 years old) is assumed as a seated person. The attachment position of the steel pipe A to the buttocks model C is formed at a position 70 mm away from the end of the buttocks model C on the back beam side. Among them, as shown in FIG. 10(b), the shape of the seat cushion of JIS S1203 is formed using the hip model C, and the size of the seat cushion is similarly reduced to 70%, and the distance L between the ischial nodules is 80mm. With respect to the upper surface of the cushion for seating, the spine angle caused by the steel pipe A of the measuring device is formed to be vertical (90°), placed on the cushion of the test subject, and obtained The inclination angle θ1 of the upper surface of the buttocks model C serves as the inclination angle of the pelvis. The inclination angle θ1 is 0°, and the pelvic upright posture is evaluated, the inclination angle θ1 is a positive value, the pelvic forward posture is evaluated, and the inclination angle θ1 is a negative value, the pelvic posture is evaluated. (2) Contact area with seat body A sheet pressure distribution measuring device (XSENSOR Technology, model: XSENSOR PX100.36.36.02) with a thickness of about 0.5 mm was laid on the upper surface of the cushion pad of the test object. The spine angle caused by the steel tube A of the above-mentioned measuring device is placed vertically (90°) and placed thereon for 5 minutes, and the seat surface body of the hip model C and the cushion of the test subject is measured The contact area of the upper surface. Among them, the hip model C is the same as the one used in (1) the measurement of the tilt angle of the pelvis.

[Example 1] Prepare a polyethylene foam with a thickness of 20 mm, a width of 40 cm, and a depth of 30 cm [E-hardness 40 according to JIS K6253, product of Asahi Kasei Corporation, model: SUNTEC FOAM Q15], using the cut-in line 3a shown in FIG. 11(a). The cut pattern of 3b forms a cut line through its thickness direction, and a seating surface body is obtained. Polyurethane foam with a thickness of 20 mm, a width of 40 cm, and a depth of 30 cm [hardness 120N according to JIS K6400-2 A method 120 (E hardness 0 according to JIS K6253), Bridgestone Chemical Products Co., Ltd. product, model: Everlight EO] as the lower layer The seat surface support body is formed by stacking the seat surface body and the seat surface support body up and down to obtain the seat cushion of Example 1. The physical properties of the cushion for seating were measured.

[Comparative Example 1] A polyethylene foam with a thickness of 20 mm, a width of 40 cm, and a depth of 30 cm [E-hardness 40 according to JIS K6253, product of Asahi Kasei Corporation, model: SUNTEC FOAM Q15] was prepared, and it was directly formed as a seat body without applying a cutting line. A polyurethane foam with a thickness of 20 mm, a width of 40 cm, and a depth of 30 cm [hardness 120N according to JIS K6400-2 A method 120 (E hardness 0 according to JIS K6253), Bridgestone Chemical Products Co., Ltd. product, model: Everlight EO] as the lower layer The seat surface support body, and the seat surface body and the seat surface support body are stacked up and down to obtain a cushion for seating of Comparative Example 1. The physical properties of the cushion for seating were measured.

[Comparative Example 2] Prepare polyurethane foam with a thickness of 20 mm, a width of 40 cm, and a depth of 30 cm [hardness 250N of JIS K6400-2 A method (E hardness 0 according to JIS K6253), Bridgestone Chemical Products Co., Ltd. product, model: Everlight GS] The cut-in line is applied to directly form a seat body. A polyurethane foam having the same material and size as the seat surface body was formed as a lower seat surface support body, and the seat surface body and the seat surface support body were stacked up and down to obtain a cushion for seating of Comparative Example 2. The physical properties of the cushion for seating were measured.

[Example 2] In Example 1, for the polyurethane foam constituting the lower seat support, except for the hardness of 250N (E hardness 0 according to JIS K6253) using JIS K6400-2 A method, Bridgestone Chemical Products Co., Ltd. products 3. Model: Except for Everlight GS, in the same manner as in Example 1, the cushion for seating of Example 2 was obtained. The physical properties of the cushion for seating were measured.

[Example 3] Example 2 is obtained in the same manner as Example 2 except that the polyethylene foam constituting the seat surface body is E hardness 23 according to JIS K6253, product of Asahi Kasei Corporation, model: SUNTEC FOAM Q25. The cushion for seating of Example 3. The physical properties of the cushion for seating were measured.

[Example 4] With regard to Example 2, the cushioning pad for seating of Example 4 was obtained in the same manner as in Example 2 except that the cutting patterns of the cutting lines 3a and 3b formed on the seat surface body were formed as shown in FIG. 11(b). The physical properties of the cushion for seating were measured.

[Example 5] With respect to Example 3, the cushioning pad for seating of Example 5 was obtained in the same manner as in Example 3, except that the cutting patterns of the cutting lines 3a and 3b formed on the seat body were formed as shown in FIG. 11(b). The physical properties of the cushion for seating were measured.

[Example 6] Example 1 is obtained in the same manner as Example 1 except that the polyethylene foam constituting the seat surface body is used in accordance with JIS K6253 E hardness 23, Asahi Kasei Co., Ltd. product, model: SUNTEC FOAM Q25. The cushion for seating of Example 6. The physical properties of the cushion for seating were measured.

[Example 7] With respect to Example 1, the cushioning pad for seating of Example 7 was obtained in the same manner as in Example 1 except that the cutting patterns of the cutting lines 3a and 3b formed on the seat surface body were formed as shown in FIG. 11(b). The physical properties of the cushion for seating were measured.

[Example 8] With respect to Example 6, the cushioning pad for seating of Example 8 was obtained in the same manner as in Example 6 except that the cutting patterns of the cutting lines 3a and 3b formed on the seat surface body were formed as shown in FIG. 11(b). The physical properties of the cushion for seating were measured.

Table 1 shows the results of Examples 1 to 5, respectively, and Table 2 shows the results of Examples 6 to 8 and Comparative Examples 1 to 2. Among them, in each table, in order to clarify the relationship between the hardness of the synthetic resin foam forming the seat surface body and the hardness of the synthetic resin foam forming the seat surface support body, it is mainly used as a seat surface support body. The hardness of the polyurethane foam used is the hardness obtained by the JIS K6400-2 A method and the E hardness according to JIS K6253.

[Table 1]

[Table 2]

From the comparison between Examples 1 to 8 and Comparative Example 1, the seat deformation body is formed by providing cut lines 3a and 3b on the seat surface body, and the inclination angle θ1 of the upper surface of the hip model becomes a positive value, showing that the pelvis remains upright or slightly In the forward leaning state, the contact area on one side is greatly increased. In addition, in the conventional cushion pad of Comparative Example 2 composed only of a soft urethane foam, it is found that the inclination angle θ1 becomes a negative value, and the pelvis leans backward to deteriorate the sitting posture.

Comparison of each of Examples 1 and 7, Examples 2 and 4, Examples 3 and 5, and Examples 6 and 8, among the cut patterns obtained by the cut lines 3 (3a, 3b), for the buttocks / The thigh rear support part cut-in line 3b is not provided near the center line in the width direction of the seat surface body, but is formed in a pattern shape divided at the central portion, thereby showing an increase in contact area.

In addition, according to the comparison of each of Examples 1 and 6, Examples 2 and 3, Examples 4 and 5, and Examples 7 and 8, a seating surface with a seated deformation portion due to the cut-in lines 3a and 3b is provided In the range of hardness of the synthetic resin foam used in this example, the inclination angle θ1 is a positive value, so it is easy to adopt the pelvic forward leaning posture, even if the seat surface body material with low hardness is selected, it shows one side Keep the pelvis leaning forward while increasing the contact area.

In addition, from the comparison of each of Examples 1 and 2, Examples 6 and 3, Examples 7 and 4, and Examples 8 and 5, it can be seen that if the hardness of the seat surface support body becomes larger, the seat surface body will face the seating deformation portion The rebound force of the push-out deformation becomes larger, so the amount of push-out deformation of the seated deformation portion becomes smaller, and the inclination angle θ1 becomes a larger positive value, and the suppression effect of the pelvic backward tilt posture is greater. In addition, by selecting a material with a small hardness and softness of the seat surface support body, it is shown that while the tilt angle θ1 remains positive (while maintaining the pelvic forward tilt posture), the contact area in the seat surface body 2 is greatly increased. That is, it can be seen that by selecting the hardness of the material that constitutes the seat surface support of the lower layer, the contact area with the seat surface body 2 can be adjusted, and the sense of stability or seating of the cushion 1 can be improved.

The present invention is not limited to the above-mentioned embodiments, and includes technically within the scope of the invention without departing from the gist of the invention described in the patent application.

1: cushion for seating 10: Seat for chair 2: Seat body 3: cut line 3a: Cut line of ischial support 3b: Hip/thigh rear support cut-in line 4: Seat deformation 4a: ischial support 4b: hip/thigh support 4b1: Thigh rear support 4b2: hip support 5: Strip 6: Seat support S: the center line of the seat body in the width direction P: pelvis G: Support base surface H: Ischia I: ischial tuberosity L: length between ischial tuberosity M: Line passing through the center of the spiral A: Steel pipe B: Universal connector C: hip model D: Hammer

FIG. 1 is an exploded perspective view schematically showing the structure of a seat cushion in the first embodiment of the present invention. FIG. 2 is a plan view (a view from the upper side) illustrating the ischial support part in the seat cushion of FIG. 1. Fig. 3 is a plan view illustrating the buttocks/thigh rear support portion of the seat cushion of Fig. 1. 4 is a cross-sectional view of (a) A-A line, (b) B-B cross-sectional view, and (c) C-C cross-sectional view of FIGS. 2 and 3. Fig. 5 is a perspective view of (a) a use state of the seating cushion of Fig. 1 and (b) a cross-sectional view taken along line D-D. FIG. 6 is a diagram showing other patterns that mainly form a cut line of the ischial support part among the sitting deformation parts. FIG. 7 is a diagram showing other patterns that mainly form a cut line of the ischial support part among the sitting deformation parts. FIG. 8 is a diagram showing other patterns that mainly form a cut line of the buttocks/thigh rear support portion among the seated deformation portions. 9 is a perspective view schematically showing the structure of a seat surface for a chair in a second embodiment of the present invention. FIG. 10 is a diagram showing (a) a schematic diagram of an evaluation device and (b) a diagram showing the hip side of a hip model in the evaluation device used in the evaluation test in Examples and Comparative Examples. FIG. 11 is a diagram showing a pattern of a cut line of a seat surface body of a cushion for seating created in an example. Fig. 12 is an explanatory diagram showing an excellent sitting posture.

1: cushion for seating

2: Seat body

3: cut line

3a: Cut line of ischial support

3b: Hip/thigh rear support cut-in line

4: Seat deformation

4a: ischial support

4b: hip/thigh support

6: Seat support

Claims (15)

A cushion for seating is a cushion for seating provided with a seating surface body formed of a flexible plate-like material, and is characterized by: The seating surface body is provided with a seating deformation portion composed of a plurality of cutting lines cut in the thickness direction thereof, The aforementioned seating deformation portion has: A sciatic support composed of a spiral, concentric circular or concentric polygonal cutting line arranged at a position corresponding to the seatbone of the seated person; and The buttocks/thigh rear support portion constituted by the cut-in line is arranged so as to surround the outer circumference of the spiral-shaped, concentric-shaped or concentric polygon-shaped cut-in line. The cushion for seating according to claim 1, wherein the plurality of cutting lines constituting the sitting deformation portion have a line-symmetric cutting pattern shape with respect to a center line in the width direction of the seating surface body. The cushion for seating according to claim 2, wherein among the plurality of cutting lines constituting the sitting deformation portion, the cutting lines constituting the ischial support portion are arranged separately from the center line in the width direction of the seating surface body. The cushion for seating according to claim 2, wherein, among the plurality of cutting lines constituting the sitting deformation portion, at least a part of the cutting lines constituting the buttocks/thigh rear support portion are within the width of the seat surface body The center lines of the directions are arranged to be connected. The cushioning pad for seating according to any one of claims 1 to 4, wherein the plurality of cutting lines constituting the seating deformation part are curved lines. The cushioning pad for seating according to any one of claims 1 to 4, wherein the plurality of cutting lines are through the thickness direction of the seating surface body. The cushioning pad for seating according to any one of claims 1 to 4, wherein the plate-like material constituting the seat surface body is a synthetic resin foam having an E hardness (according to JIS K6253) and a hardness of 5 to 80. The cushion for seating according to any one of claims 1 to 4, which has a seat surface support body stacked on the lower surface side of the seat surface body, and the seat surface support body is formed from a plate-like shape that constitutes the seat surface body The material is made of at least one material selected from the group consisting of a synthetic resin foam having a softer material, a stretchable sheet, and a stretchable mesh sheet. The cushioning pad for seating according to claim 8, wherein the hardness of the synthetic resin foam constituting the seat surface support is 50 to 400 N (according to JIS K6400-2 A method). A seat surface for a chair is a seat surface for a chair provided with a seat surface body composed of a flexible plate-shaped material, and is characterized by: The seating surface body is provided with a seating deformation portion composed of a plurality of cutting lines cut in the thickness direction thereof, The aforementioned seating deformation portion has: A sciatic support composed of a spiral, concentric circular or concentric polygonal cutting line arranged at a position corresponding to the seatbone of the seated person; and The buttocks/thigh rear support portion constituted by the cut-in line is arranged so as to surround the outer circumference of the spiral-shaped, concentric-shaped or concentric polygon-shaped cut-in line. The seating surface for a chair according to claim 10, wherein the plurality of cutting lines constituting the seating deformation portion have a line-symmetric cutting pattern shape with respect to a center line in the width direction of the seating surface body. The seat surface for a chair according to claim 11, wherein among the plurality of cutting lines constituting the sitting deformation portion, the cutting lines constituting the ischial support portion are arranged separately from a center line in the width direction of the seat surface body. The seat surface for a chair according to claim 11, wherein at least a part of the cut lines constituting the buttocks/thigh rear support portion in the plurality of cut lines constituting the seated deformation portion are in the width direction of the seat surface body The centerline of the is connected. The seat surface for a chair according to any one of claims 10 to 13, wherein the plurality of cut-in lines pass through the thickness direction of the seat surface body. The seat surface for a chair according to any one of claims 10 to 13, wherein a seat surface support body is stacked on the lower surface side of the seat surface body, and the seat surface support body is formed from a plate-like material that constitutes the seat surface body At least one material selected from the group consisting of a softer synthetic resin foam, an elastic sheet, and an elastic mesh sheet.

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