A seat equipped with means for adjusting posture, and a chair equipped with the seat.

Abstract

To provide a seat part and a chair that make a seated person P's sitting keep his / her posture correct, beautify appearance of the seated person's posture, and can contribute to his / her systemic health.SOLUTION: There are provided a seat part equipped with a groove structure and a chair comprising the seat part. The groove structure has the following features: (1) a depth of the groove structure's region narrowing from an upper surface to a lower surface of the seat part is 6 to 30 mm and the width of the deepest part of the region is 5 to 25 mm; (2) a front side elevation angle of the groove structure's region is 20 to 90 degrees and an elevation angle formed by a cutting surface of a convex structure is 10 to 60 degrees; (3) a thickness from an upper edge to the deepest part of the convex structure in the groove structure's region is 10 to 80 mm and a linear length from the upper edge to the deepest part is 45 to 150 mm; and (4) the groove structure's length is equal to or longer than 15 mm.SELECTED DRAWING: Figure 11

Description

[[Technical Field]]

[0001] The present invention relates to a chair, and specifically relates to a seat provided with posture adjustment means and a chair comprising the same. [[Background Art]]

[0002] Maintaining a correct posture when sitting on a chair is not only aesthetically pleasing, but also reduces fatigue and suppresses the occurrence of lower back pain and stiff shoulders. The present invention relates to a seat provided with posture adjustment means and a chair that maintain a correct sitting posture when seated, and the following background art is cited in relation thereto.

[0003] Patent Document 1 addresses the problem of preventing fatigue caused by blood circulation disorders due to body weight being applied to the tips of the ischial bones when seated, and discloses a chair as illustrated in FIGS. 1 and 2 of Patent Document 1, wherein "four cushions support four positions, namely the left and right thighs and the left and right hips, to distribute body weight (FIG. 1 of Patent Document 1), the ischial bones are held between the front and rear cushions to alleviate blood circulation disorders caused by concentration of body weight on the tips of the ischial bones, and an inclined plate with an inclination angle of approximately 30 degrees makes it easier for the ischial bones to fit between the front and rear cushions (FIG. 2 of Patent Document 1)." However, in the chair disclosed in Patent Document 1, the gap formed by the four cushions widens sharply from the left and right ends toward the midline when a person is seated. With such a structure, although it can prevent the blood circulation disorder that is the problem addressed by Patent Document 1 and allow the sitter to relax temporarily, the lower back of the sitter sways significantly backward when seated, resulting in a "sagging pelvis" posture, making it difficult to form and maintain a correct sitting posture with this structure.

[0004] Patent Document 2 discloses a chair for preventing anterior pelvic tilt. For this purpose, a groove is provided to lower the ischial tuberosity, and a "femoral support" is placed higher directly below the sitter's femur, supporting the sitter's femur with this convex support mechanism. When the sitter's trunk weight is placed on this femoral support, the adjustment function of the posterior thigh muscles is relaxed, and tension in the hip joint, proximal pelvis, psoas major muscle, and iliacus muscle is released, thereby preventing anterior pelvic tilt. However, with a structure that relies on the sitter's weight distribution by such a femoral support, even if anterior pelvic tilt can be prevented, it is difficult to maintain a neutral and correct sitting posture for those who do not have anterior pelvic tilt. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-000401 [Patent Document 2] Japanese Patent Publication No. 2008-29788 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0006] The inventors of this invention define a "correct sitting posture" as "maintaining the same pelvic angle and spinal curvature as in an upright posture" (Takanori Ito et al., Journal of Architecture and Planning, Architectural Institute of Japan, Vol. 81, No. 730, 2573-2583, December 2016, "Verification of Chair Sitting Posture and Repositioning Movement in Multi-Posture Support"), and based on the premise that "maintaining the same pelvic angle and spinal curvature as in an upright posture" is rational, and that "the mobility of the spine and the range of motion of the pelvis influence each other" (Shoko Shiomoto et al., Physical Therapy Science, 26(3):337-340, 2011), they conducted extensive research on a chair that, when seated, maintains the sitter's posture correctly, improves the appearance of the sitter's posture, and contributes to overall health. [Means for solving the problem]

[0007] The inventors of this invention began by aiming to solve the above-mentioned problems by providing a mechanism on the seat surface that causes the sitter's pelvis to be in a predetermined state (seat mechanism). In other words, they diligently studied with the goal of creating a seat mechanism that stabilizes the position of the ischial tuberosities on the seat surface while orienting the pelvis in a predetermined angle direction to form a correct sitting posture. As a result, the inventors came up with the idea of ​​using the state of the sitter's trapezius muscle and inner muscles as the main indicator for finding the conditions under which this correct sitting posture can be formed. They then found conditions under which a correct sitting posture can be formed and maintained in a relaxed state, and furthermore, that the sitter can acquire the correct sitting posture through continuous use. They found a seat with a seat mechanism that can reflect these conditions to the sitter, along with a chair equipped with this seat.

[0008] In other words, the present invention relates to the following seat or chair.

[0009] Figure 1 is a schematic diagram modeling a longitudinal section of the seat obtained by cutting the front and rear of the seat, including the width direction of the groove structure, which is one of the constituent elements of the seat of the present invention, and does not limit the scope of the present invention. Here, "width direction" refers to the direction that connects the front edge and rear edge of the seat in the shortest possible way (for example, I-I' in Figure 4(1), III-III' in Figure 13-1), and "length direction" refers to the direction that connects the left and right sides of the seat in the shortest possible way ( Width direction The "depth direction" or "thickness direction" is the direction that connects the upper and lower surfaces of the seat in the shortest possible way (perpendicular to the width and length directions, and vertically). These various directions are common throughout this specification.

[0010] The seat of the present invention has a region (D in Figure 1) that narrows from the top to the bottom surface of the seat, sandwiched between a notch provided from the top to the bottom surface of the front side of the seat (A in Figure 1) and a notch provided from the upper edge of a convex structure (B in Figure 1) that functions as a buttock support, facing the said notch, and positioned where both ischial tuberosities fit when seated. A pair of these regions are provided on the left and right sides in the longitudinal direction, or a region that drops below the top surface of the seat is continuously provided between the left and right sides in the longitudinal direction, and the bottom surface of the seat is open. , or not open A seat with a groove structure (C in Figure 1) that meets the following conditions (1)-(4).

[0011] (1) The depth (a in Figure 1) of the region (D in Figure 1) in the groove structure (C in Figure 1) that narrows from the upper surface to the lower surface of the seat is 6-30 mm, preferably 10-20 mm; and the width of the deepest part of the region (b in Figure 1) is in the range of 5-25 mm, preferably 10-20 mm.

[0012] (2) The elevation angle (θ in Figure 1) relative to the horizontal plane (0 degrees) above ground, as viewed from the deepest part of the front cut surface formed by the narrowing region (D in Figure 1) of the seat from the upper surface to the lower surface in the groove structure (C in Figure 1), is 20-90 degrees, preferably 30-45 degrees. The elevation angle (φ in Figure 1) relative to the horizontal plane (0 degrees) above ground, as viewed from the deepest part of the cut surface (L in Figure 1) formed by the convex structure (B in Figure 1) in the narrowing region (D in Figure 1), is 35-60 degrees. Within this angle range, it is possible to maintain a state in which not only the trapezius muscles but also the inner muscles of the seated person are working. A more preferable angle range (φ) is 40-55 degrees. By combining these angle ranges θ and φ with the size range described in (1) above, the width of the opening on the upper side of the groove structure (d in Figure 1) can be calculated.

[0013] (3) In the groove structure (C in Figure 1), the region (D in Figure 1) that narrows from the top surface to the bottom surface of the seat, and the straight length of the cut surface (L in Figure 1) from the top edge to the deepest part, corresponding to the thickness (c in Figure 1) from the top edge to the deepest part in the convex structure (B in Figure 1), is 45-150 mm, and it is preferable from the viewpoint of seating comfort, etc., that the straight length be 100 mm or less. The straight length is, in other words, the straight distance. For example, if the cut surface (L in Figure 1) from the top edge to the deepest part is a flat slope, the straight length is the length from the top edge of the slope to the deepest part, and if it is a curved surface, it is the straight length from the top edge of the slope to the deepest part, excluding the curved part. The range of the preferred straight length (L) in the "angle range (φ) that can maintain the function of not only the trapezius muscle but also the inner muscles" is influenced by the height of the person sitting. First, regardless of the sitter's height, the minimum value of the straight length (L) is 45 mm. Also, for heights of 175 cm or less, the minimum value is approximately 55 mm. If it is 60 mm or more, it is possible to maintain the function of the trapezius muscle and inner muscles without considering the sitter's height. Therefore, focusing on the fact that the sitter's height does not need to be considered, a straight length (L) of 55 mm is preferable to 45 mm, and even more preferable is 60 mm or more. However, if the seating comfort due to the effect of the convex structure (presence or absence of discomfort due to the convex structure) is individually considered for each sitter's height, setting the straight length (L) within the range of 45 mm - 55 mm - 60 mm or more according to the expected sitter's height is also within the scope of the present invention. The above thickness (c) is defined by the above angle (φ) and straight length (L).

[0014] (4) A pair of these are provided on the left and right sides in the length direction mentioned above. The groove structure described above (C in Figure 1) Between the left and right ends The length (the length itself is not shown) The lengths of each of the two groove structures on the left and right sides described above are It is 15mm or larger.

[0015] One of the requirements for the seat portion of the present invention described above, "having a region in the groove structure that narrows from the upper surface to the lower surface of the seat portion," means that the groove structure has the above-mentioned region. The "region" is the region within the groove structure as defined above, and any part that falls outside this definition is "another region." In the groove structure, other regions may be present further below the above-mentioned region. For example, a region can be provided further below the above-mentioned region, where the front and rear sides face each other with a steeper downward slope than the region where the seat portion narrows, but the invention is not limited to this embodiment. It is possible to use the model shown in Figure 1 as is, but here are two other typical examples shown in Figure 2. One example shown in Figure 2 (Figure 2(1)) is an embodiment in which the bottom plate F is bonded to the entire surface, including directly below the "region D in the groove structure C that narrows from the upper surface to the lower surface of the seat portion," so that the bottom of region D is closed flat, and as a result, region D and the groove structure C overlap. Another example shown in Figure 2 (Figure 2(2)) is one in which another region E is provided directly below region D, with the front and rear walls facing each other vertically. A bottom plate F is bonded to the entire surface directly below this region E, so that the bottom of the other region E is closed flat. In other words, a groove structure C is formed by region D and the other region E. The angle of opposition between the front and rear walls in this other region E can be arbitrarily selected, but this example of vertical opposition is one of the preferred embodiments. The depth of this other region E (a' in Figure 2(2)) is not particularly limited, but 30 mm or less is preferred.

[0016] Figures 2-2 and 2-3, which are longitudinal cross-sectional views similar to those in Figures 1 and 2, list other examples of the shape of the "other region E" of the groove structure C described above, broadly categorized into non-penetrating shapes (left figures) and penetrating or semi-penetrating shapes (right figures). Figures 2-2 ((1)-(5)) and 2-3 ((6)-(9)) are illustrative diagrams. A non-penetrating shape is a shape in which the bottom of the groove structure C is closed with a thick portion in the thickness direction. A penetrating shape is a shape in which the bottom of the groove structure C is open, and a semi-penetrating shape is a shape in which the bottom is only slightly open, or even if closed, the opening is very thin. In each enumerated diagram, the left side of the shaded area corresponds to the front side A of the seat (A1), and the right side corresponds to the convex structure B (B1). The blacked-out area corresponds to the bottom plate F in which the other region E is formed. The plate-like body corresponding to the bottom plate F may be a single plate, or it may be a laminated plate in which multiple single plates are stacked together. Furthermore, the shaded areas and the blacked-out areas may exist as a single, integrated plate. In each figure, the shaded areas are identical (all composed of A1 and B1), but the bottom plate equivalent parts (F1-F9: non-penetrating shape, F1'-F9': penetrating or semi-penetrating shape) differ depending on the parts corresponding to other areas E (E1-E9: non-penetrating shape, E1'-E9': penetrating or semi-penetrating shape). Note that these vertical cross-sectional views are cross-sections of parts with groove structures, so even if the groove structure is a penetrating shape, the bottom plate is connected via a non-penetrating structure.

[0017] In Figure 2-2(1), the non-penetrating shape (E1) is a square groove with a flat, closed bottom, while the penetrating shape (E1') is a form where the bottom of the groove is completely open. In Figure 2-2(2), the non-penetrating shape (E2) is a V-shaped groove, and the semi-penetrating shape (E2') is a form where the valley line of the V-shaped groove opens linearly. In Figure 2-2(3), the non-penetrating shape (E3) is a U-shaped groove, and the semi-penetrating shape (E3') is a form where the bottom of the U-shaped groove opens linearly. In Figure 2-2(4), the non-penetrating shape (E4) is a dovetail groove, and the penetrating shape (E4') is a form where the bottom of the dovetail groove opens directly. In Figure 2-2(5), the non-penetrating shape (E5) is a shape where the central part is raised in a semicircular shape along the length direction of the bottom of the groove structure, and the semi-penetrating shape (E5') is a shape where both ends of the above semicircle open linearly.

[0018] The non-penetrating shape (E6) in Figure 2-3(6) is in the form of a groove whose bottom is closed flat while opposing walls form outward arc walls with respect to each other, and the penetrating shape (E6') is in the form of a groove whose bottom is open while opposing walls form outward arc walls with respect to each other. The non-penetrating shape (E7) of the same (7) is a groove with a hexagonal cross-section whose bottom is closed flat, and the penetrating shape (E7') is a groove with a hexagonal cross-section whose bottom is open. The non-penetrating shape (E8) of the same (8) is a groove with an octagonal cross-section whose bottom is closed flat, and the penetrating shape (E8') is a groove with an octagonal cross-section whose bottom is open. The penetrating shape (E9) of the same (9) is a shape in which the central portion protrudes in a triangular shape along the length direction of the bottom of the groove structure, and the quasi-penetrating shape (E9') is a shape in which both lower ends of the triangular shape are linearly opened.

[0019] One preferred embodiment of the groove structure C described above is exemplified as a form that is recessed below the upper surface of the seat portion in the length direction, has a continuous region that is open on the lower surface side of the seat portion, and has open ends on the left and right side surfaces of the seat portion. Further, another preferred embodiment is exemplified as a form in which another groove portion that divides the seat portion into left and right in the length direction and may have an open bottom is continuously provided connecting from the rear edge to the front edge of the seat portion. By adopting these groove structures with openings, air from the surrounding environment can come into contact with the buttocks and thighs of a seated person, suppressing stuffiness associated with long-time sitting, thereby improving seating comfort. In addition, by adopting these groove structures with openings in combination with "another region E" shown in Figure 2(2) for example, it becomes possible to secure this "another region" as a ventilation means after seating. or not open

[0020] In the convex structure described above, Slope from the upper edge to the deepest part the shape of When seated into which the buttocks fit Curvature is exemplified as one preferred form, and as a typical said shape Curvature a form including an R-curved shape is exemplified. On the surface that receives the buttocks, the R Curvature shape and other Curvature ​By including the shape, the pressure applied to the buttocks of a seated person can be dispersed, and the comfort of sitting can be improved.

[0021] In addition, by rounding the corner of the "notch opening from the upper surface to the lower surface" in the above-mentioned "notch provided from the upper surface to the lower surface of the front side (A in Fig. 1) of the seat portion of the present invention", for example, forming it into a rounded corner, the comfort of the sciatic region during sitting can be improved; and by rounding the corner on the upper surface side of the front edge of the seat portion, for example, forming it into a rounded corner, the comfort of the thighs during sitting can be improved.

[0022] By sitting with the ischium placed in the groove structure provided on the seat portion of the present invention as described above, the seated person can maintain a correct sitting posture.

[0023] The seat portion of the present invention can be used as a part of a chair that employs it as a constituent feature, and can also be used as an independent product by itself. When the seat portion of the present invention is used as an independent product, the effects of the present invention can be exerted by "being placed or fixed on an object to be sat on". Examples of the object to be sat on (hereinafter also referred to as "sitting object") include other height-adjusted chairs, platforms, boxes, and the like. This is an embodiment in which the seat portion of the present invention is placed or fixed on the sitting object, and a user sits thereon for use.

[0024] The material constituting the seat portion of the present invention is preferably a material that does not cause significant deformation of the shape of the seat portion under the self-weight of the seated person. If this condition is satisfied, one or two or more types of materials can be freely UseIt is possible to use materials such as wood, metal, stone, hard plastic, carbon fiber, urethane, natural leather, synthetic leather, etc., either individually or in combination. For example, urethane can be used in appropriate combinations of chip urethane, medium-density urethane, and high-density urethane, but a preferred embodiment is "Type 1 HB: high-elasticity type block, slab stock, or processed products thereof" or "Type 2 HM: high-elasticity type molded product" selected from "Type 1 LB, MB, HB; Type 2 LM, MM, HM; Type 3 RE" of the "JIS K6401 standard", and "S (severe), V (very severe), or X (extremely severe)" selected from "X, V, S, A, L" of the "Class", and "400 (365-425N), 470 (430-520N), or 600 (525- 650 N) is one example. Note that the above "Type" is a classification based on differences in manufacturing method and rebound elasticity, the "Class" is a classification based on the rate of decrease in 40% compression hardness from the initial hardness measured after a constant load repeated compression test, and the "Grade" is a classification based on hardness at 40% compression.

[0025] The chair of the present invention has the above-mentioned seat portion of the present invention on the seat It is a chair that has been provided.

[0026] Furthermore, the chair of the present invention may also be a chair that includes a backrest in addition to the seat of the present invention. The position, shape, and material of the backrest are not limited as long as the position, shape, and material do not disrupt the posture of the sitter formed by the seat of the present invention when the sitter leans their back against the backrest. The entire backrest may be rigid and have little curvature, for example, a rigid material such as wood or metal may be fixed in place, or it may be a configuration in which flexibility is added that allows it to bend due to the tilting pressure when the sitter leans against it, for example, the part of the backrest that is pressed against the sitter's back may be expandable and contractible due to rubber, springs, knitted fabric, etc.

[0027] For example, if the backrest is provided as a flat surface perpendicular to the seat of the chair, the distance in the width direction between the lower end of the notch provided from the upper edge of the convex structure in the seat of the present invention toward the underside of the seat and the backrest is preferably about 70-150 mm.

[0028] In the chair of the present invention with a backrest, one preferred embodiment is to provide a means for distributing the weight of the sitter, such as a lumbar support structure, at a position on the backrest corresponding to the sitter's posterior superior iliac spine. For example, the backrest surface can be curved so that the area in contact with the sitter's lumbar region (posterior superior iliac spine) is convex when viewed from the sitter's side, thereby creating a lumbar support structure. Alternatively, a lumbar support member can be separately placed and fixed in the area of ​​the backrest surface in contact with the sitter's lumbar region (posterior superior iliac spine). It is also preferable to make such a lumbar support member detachable and to provide an up-and-down position adjustment mechanism on the backrest. Furthermore, when a lumbar support member is provided on the backrest surface, it is preferable that the member has a shape that matches the three-dimensional shape of the sitter's waist. For example, a lumbar support member can be provided with an R-curved surface that can cover the outer diameter curve of the sitter's waist (the part in contact with the lower part of the oblique abdominal muscle). Furthermore, the material of the support member is not particularly limited and can be wood, metal, stone, hard plastic, carbon fiber, urethane, natural leather, synthetic leather, etc., either alone or in combination. For example, urethane can be used in combination of chip urethane, medium-density urethane, and high-density urethane as appropriate, but a preferred embodiment is, as above, "Type 1 HB: High-elasticity type block, slab stock, or processed products thereof" or "Type 2 HM: High-elasticity type molded product" selected from the "Type" of the "JIS K6401 standard", and "S (severe), V (very severe), or X (extremely severe)" selected from the "Class", and "400 (365-425N), 470 (430-520N), or 600 (525- 650 N) is one example.

[0029] As described above, the weight distribution means for the seated person, such as the lumbar support structure, is preferably positioned where the seated person's lumbar region (posterior superior iliac spine) naturally makes contact when seated in the chair of the present invention with a backrest. Specifically, it is preferable that the surface of the area of ​​the weight distribution means for the seated person, such as the lumbar support structure, that contacts the seated person's lumbar region (posterior superior iliac spine), is positioned such that it is projected onto the horizontal plane (0 degrees) above ground at a distance of 20-150 mm in the width direction from the lower end of the notch provided from the upper edge of the convex structure on the seat toward the underside of the seat. The lower limit of 20 mm, which is around 20 mm, is for cases where the seated person is expected to be small, including children, and the upper limit of 150 mm, which is around 150 mm, is for cases where the seated person is expected to be very large. For a standard Japanese adult, approximately 40-130 mm is preferable.

[0030] Furthermore, it is preferable that when the direction in which the seated person's back faces is at an elevation angle of 35-60 degrees, relative to the horizontal plane (0 degrees) above ground, one or more protrusions are provided on the backrest at a position where the seated person's trapezius muscle makes contact. This preferred condition can be met by providing the protrusions within the intersection area of ​​the backrest surface and the extension line in the direction of the upper edge, when the elevation angle from the lower end of the notch provided from the upper edge of the convex structure on the seat toward the underside of the seat is considered to be 35-60 degrees. When the seated person's trapezius muscle is stimulated by the tip of such a protrusion, the tension in the trapezius muscle is relieved, the seated person's unnecessary tension is released, it is possible to prevent shoulder stiffness associated with prolonged sitting, and furthermore, the function of inner muscles other than the trapezius muscle can be promoted. The size, material, and shape of the protrusions described herein are not particularly limited as long as they can exert a massage effect on the trapezius muscle. Typically, one embodiment includes a dome-shaped projection made of a material such as metal, wood, rubber, hard plastic, or stone, with a rounded tip, a base area of ​​50-400 square millimeters, and a height of approximately 10-30 mm, that is hard enough to be pressed into the back.

[0031] A typical embodiment of the chair of the present invention is a chair equipped with a mechanism for maintaining or adjusting the height of the seat when seated (hereinafter also referred to as a "height-adjustable chair"). The mechanism for maintaining or adjusting the height is typically the legs, but is not limited to other mechanisms such as a trapezoidal mechanism or a box-shaped mechanism, as long as it can maintain or adjust the height of the seat when seated. The adjustment can be, for example, an adjustment mechanism for the length of the legs (adjustment by screws, adjustment by a sliding mechanism, etc.), but is not limited to this. It is preferable that the height of the seat is adjusted to a position where the angle of the seated person's knees is approximately 90 degrees (hereinafter also referred to as the "90-degree rule"), and it is preferable that the chair height, seat inclination angle, seat depth, back inclination angle, and other conditions are selected or adjusted so as to satisfy this 90-degree rule. It is preferable that the chair of the present invention is equipped with an adjustment means for satisfying the 90-degree rule. Here, the seat inclination angle is the angle of elevation when viewed straight from the midpoint of the rear edge to the midpoint of the front edge of the seat, with the ground horizontal plane being the seat inclination angle of 0 degrees. The seat depth is the dimension of the perpendicular line from the midpoint of the rear edge of the seat to the front edge. The backrest tilt angle is the angle that the chair's backrest makes with the ground horizontal plane, and is the angle of elevation formed by the backrest when viewed straight from the midpoint of the front edge to the midpoint of the rear edge of the seat. Therefore, if the backrest is tilted along the ground horizontal plane, the backrest tilt angle is 180 degrees, and if the backrest is upright relative to the ground horizontal plane, the backrest tilt angle is 90 degrees.

[0032] Based on the above premise, the seat tilt angle of the chair of the present invention is preferably about 0-5 degrees upward, the seat depth is preferably about 220-430 mm, and the backrest tilt angle is preferably about 90-105 degrees.

[0033] The present invention also includes chairs that are essentially "seat and backrest" and lack height-maintaining or adjustment mechanisms such as legs, essentially resembling a floor chair. In this floor chair-like configuration, similar to the above configuration in which the seat of the present invention is used as an "independent product," it is preferable to place or fix it on a seating surface and use it as a seat.

[0034] The seat and chair of the present invention can maintain the sitter's posture correctly, improve the appearance of the sitter's posture, reduce fatigue, and further improve the sitter's sitting posture. [Effects of the Invention]

[0035] The present invention provides a seat that reduces fatigue for the sitter and improves the sitter's sitting posture, as well as a chair that uses this seat. [Brief explanation of the drawing]

[0036] [Figure 1] This drawing models a longitudinal section of the seat, including the width direction of the groove structure, which is one of the constituent elements of the seat of the present invention, obtained by cutting the front and rear of the seat. [Figure 2] These drawings model two representative embodiments ((1), (2)) of the longitudinal section obtained by cutting the front and rear of the seat, including the width direction of the groove structure, which is one of the constituent elements of the seat of the present invention. [Figure 2-2] This is a cross-sectional view of a groove illustrating the shape of the "other region E" portion of the groove structure, which is one of the constituent elements of the seat portion of the present invention, divided into a non-through shape and a through shape or semi-through shape ((1)-(5)). [Figure 2-3] The above diagrams ((6)-(9)) are examples that continue from Figure 2-2. [Figure 3] This diagram illustrates the function of muscles such as the trapezius in relation to the thickness and angle of the convex structure at the rear of the seat. [Figure 3-2] This drawing shows the results of a study on the permissible limits, taking into account the user's height, for the length of the inclined surface of the convex structure at the rear of the seat (the thickness of the convex structure). [Figure 4] This is a perspective view of a seat portion 10, which is one embodiment of the seat portion of the present invention, and an enlarged cross-sectional view of the seat portion near the groove structure, I-I'. [Figure 5] This is a drawing showing several examples of modifications to the seat portion 10. [Figure 6] This is a perspective view of a seat portion 20, which is an example of an embodiment of the seat portion of the present invention. [Figure 7] This is a drawing showing several examples of modifications to the seat portion 20. [Figure 8] This is an exploded assembly diagram of an example of a chair (height-adjustable chair) according to the present invention. [Figure 9] This is a completed drawing of an example of a chair (a chair with height adjustment) according to the present invention. [Figure 10] This is a completed drawing of another embodiment of the chair (height-adjustable chair) of the present invention. [Figure 11] This is a diagram showing the position of a person sitting in the chair of the present invention. [Figure 12] This is a schematic diagram showing the appearance of two types of measuring chairs. [Figure 13-1] This is an overall perspective view of the seat portion 80 of the present invention, used to examine the physical effects on the sitter due to continuous use. [Figure 13-2] Figure 13-1 is a longitudinal cross-sectional view of the seat portion 80 near the groove structure, taken at line III-III'. [Figure 14] This is a photographic drawing showing the backrest position of the seat panel before and after continuous use of the seat portion 80 of the present invention. [Modes for carrying out the invention]

[0037] 1. Example Test (1) Measuring chair Focusing on the relationship between the function of the trapezius muscle and inner muscles and posture, we prepared a measuring chair (hereinafter referred to as the measuring chair) that could adjust the position and angle of the sit bones of the person sitting, and conducted tests.

[0038] This measuring chair was constructed by removing the seat cushion from a single-legged, height-adjustable office chair with a backrest, leaving only the seat support mechanism. A support plate G was then installed on this support mechanism, and a seat capable of adjusting the basic requirements of the present invention was placed on top of it. Three types of materials were used for the seat: wood (plywood laminated wood), thermoplastic elastomer (TPE), and high-rebound urethane foam (yellow urethane). The density (D) of the high-rebound urethane foam was 80 kg / m³. 3The hardness (N) was 450N. This high-rebound urethane foam is included in the "urethane suitable as a seating material" under the "JIS K6401 standard" mentioned above.

[0039] Two different seat shapes were prepared for each of these materials. These are explained with their schematic diagrams shown in Figures 12(1) and (2).

[0040] The seat of the first shape is a seat 60 having a horizontally penetrating groove structure 60C that is continuous in the longitudinal direction and has open ends on the left and right sides of the seat (Figure 12(1)). This groove structure corresponds to groove structure C shown in Figure 1, and is of the type in which the bottom surface of region D is closed by a bottom plate F (no other region E is provided). Figure 12(1) was used by fitting the items in Figure 1 (a) the thickness of the front seat of the groove structure 60C (60a), (b) the elevation angle of the front of the groove structure 60C (corresponding to θ in Figure 1: not shown), (c) the elevation angle of the rear of the groove structure 60C (corresponding to φ in Figure 1: not shown), (d) the vertical length of the slope of the convex structure 60B (thickness of the convex structure 60B (60c)), and (e) the distance between the lower ends of the front and rear cutouts (corresponding to b in Figure 1: not shown)) on a thick base plate 60F, and adjusting them by replacing each component.

[0041] The second type of seat is a seat with a wooden base plate, a left and right convex structure, and left and right thigh rests, as shown in Figure 6 below. Similar to the above, it is a type in which the bottom surface of region D is closed by the base plate (other regions E are not provided). In Figure 12(2), the seat 20 of Figure 6 is shown as an example, but it was used by adjusting the following items ((a) the thickness of the front side of the groove structure of the seat (20a), (b) the elevation angle of the front side of the groove structure (20θ), (c) the elevation angle of the rear side of the groove structure (20φ), (d) the vertical length of the slope of the convex structure (thickness of the convex structure (20c)), the distance between the lower ends of the cuts on the front and rear sides (20b)) by replacing each component.

[0042] The dimensions of the seat sections of both these two types are 400mm in both the vertical (width) and horizontal (length) directions.

[0043] In the measuring chairs 600 and 700, the seats 60 and 20 were positioned on the support plate G as described above, with the bottom plates 60F and 20F, respectively, attached to the seats 60 and 20, positioned so that the rear edges of these bottom plates abut against the support column H1 of the chair's backrest. The distance from the lower end of the notch provided from the upper edge of the convex structure of the seat 60 and 20 toward the underside of the seat, to the position where it abuts against the support column of the backrest, that is, the distance 60γ and 20γ from the lower end of the notch toward the rear edge of the seat surface, was set to 100 mm in all cases as the "distance from the groove structure to the backrest". Furthermore, a massage plate J can be installed as needed at the position on the backrest H where the sitter's trapezius muscles make contact (within the intersection area of ​​the backrest surface and the extension line in the direction of the upper edge, assuming an elevation angle of 35-60 degrees from the lower end of the notch provided from the upper edge of the convex structure on the seat toward the underside of the seat). This massage plate J has five wooden protrusions J1 (cones with a rounded tip, a base of 25 square mm, and a height of 8 mm) in two vertical rows separated by approximately 50 mm, with each row spaced at equal intervals of approximately 10 mm. When the sitter's back rests on the backrest, the areas of the left and right trapezius muscles near the spine come into contact with the protrusions J1 of the massage plate J, thereby providing a massage effect by relaxing the trapezius muscles.

[0044] (2) Examination items In this test, the following items were examined using the measurement chairs described above, each with a wooden seat and a urethane seat. (a) Examination of the thickness of the front side of the seat of the groove structure (b) Examination of the elevation angle (θ) of the front side of the groove structure (c) Examination of the distance between the lower ends of the front and rear cutouts (Figure 1b) (d) Examination of the elevation angle (φ) on the rear side of the groove structure (e) Examination of the length of the slope above and below the convex structure (thickness of the convex structure)

[0045] The above test items [(a)-(c)] and [(d),(e)] will have their test methods and results described separately.

[0046] (3) Regarding the test items [(a)-(c)] (3)-1: Test Method For the above test items (a) and (b), the measurement chair 600 was fixed with a diameter of 60φ at 45 degrees, a thickness of 60c of the convex structure at 45 mm, and the distance (b) between the lower ends of the front and rear cutouts at 20 mm; the measurement chair 700 was fixed with a diameter of 20φ at 45 degrees, a thickness of 20c of the convex structure at 60 mm, and the distance (20b) between the lower ends of the front and rear cutouts at 15 mm. These chairs were used as measurement chairs, and the thickness of the front front of the groove structure, or the elevation angle (θ) of the front of the groove structure, was changed. The study was conducted with one healthy male and one healthy female, both aged 47 years (both with heights in the range of 150-175 cm). Specifically, for these two subjects, the height was adjusted so that the bending angles of both the knees and ankles were 90 degrees, and they were seated in the measurement chair with their ischial tuberosities placed in the groove structure. Next, a load in the direction of gravity was applied to the left and right shoulders separately with approximately equal human force from directly above the subject's shoulders to examine whether the subject could support their own upper body under the conditions of a predetermined measuring chair. If the subject was able to support their upper body, a protrusion was placed on the backrest to stimulate the trapezius muscle, and it was then examined whether the subject could still support their upper body in that state.

[0047] For item (c) above, in the measurement chair 600, the 60φ was fixed at 45 degrees, the 60θ at 45 degrees, the thickness of the front of the seat 60a at 15 mm, and the thickness of the convex structure 60c at 45 mm; in the measurement chair 700, the 20φ was fixed at 45 degrees, the 20θ at 45 degrees, the thickness of the front of the seat 20a at 20 mm, and the thickness of the convex structure 20c at 60 mm. These were used as measurement chairs, and the distance between the lower ends of the front and rear cutouts was varied. The study was conducted with one healthy male and one healthy female, both aged 47 years (both with heights in the range of 150-175 cm). Specifically, for these two subjects, the height was adjusted so that the bending angles of both the knees and ankles were 90 degrees, and they were seated in the measurement chair with their ischial tuberosities placed in the groove structure. Next, a load in the direction of gravity was applied to the left and right shoulders separately with approximately equal human force from directly above the subject's shoulders to examine whether the subject could support their own upper body under the conditions of a predetermined measuring chair. If the subject was able to support their upper body, a protrusion was placed on the backrest to stimulate the trapezius muscle, and it was then examined whether the subject could still support their upper body in that state.

[0048] (3)-2: Test results Regarding items (a) and (b) above, it was found that for measurement chairs equipped with wooden, TPE, or yellow urethane seats, a "thickness of the front front of the groove structure" of 6-30 mm was practical, and a thickness of 10-20 mm provided good seating comfort. Furthermore, when the "elevation angle (θ) of the front of the groove structure" was 20-90 degrees, the subject's posture was maintained even when manual load was applied to the shoulders and stimulation was performed with the backrest protrusions. It was found that a value of 30-45 degrees provided even better seating comfort.

[0049] Regarding item (c) above, it was found that the value was 5-25mm for all measurement chairs equipped with wooden, TPE, or yellow urethane seats. When item (c) was less than 5mm or more than 25mm, the posture could not be maintained when manual load was applied to the shoulders while the backrest protrusions were stimulated. It was found that a value of 10-20mm is optimal for maintaining posture when load is applied.

[0050] (4) Regarding the test items [(d), (e)] Two types of studies were conducted for the above test items (d) and (e): the first (d)(e) test and the second (d)(e) test. Here, these will be abbreviated as "the first test" and "the second test," respectively.

[0051] <First (d)(e) Exam> (4)-1-1: Method of the first examination In the measurement chair 600, the angle 60θ was fixed at 45 degrees, the thickness 60a of the front part of the seat was fixed at 15 mm, and the distance (b) between the lower ends of the front and rear cutouts was fixed at 20 mm; in the measurement chair 700, the angle 20θ was fixed at 45 degrees, the thickness 20a of the front part of the seat was fixed at 20 mm, and the distance (20b) between the lower ends of the front and rear cutouts was fixed at 15 mm. These chairs were used as measurement chairs, and the height was adjusted so that the knee and ankle flexion angles of five subjects (healthy individuals) (a 47-year-old female, a 47-year-old male, a 64-year-old female, a 69-year-old female, and a 74-year-old male) were both 90 degrees, and the subjects were seated with their ischial tuberosities in the groove structure. The heights of these five subjects were within the range of 150-175 cm. Next, a load in the direction of gravity was applied from directly above both of the subjects' shoulders with approximately equal human force to the left and right shoulders separately, and it was examined whether the subjects could support their own upper bodies under the specified measurement chair conditions. Then, if the upper body could be supported, protrusions were placed on the backrest to further stimulate the trapezius muscle, and it was examined whether the upper body could still be supported in that state. If the subject was unable to support their upper body and tilted in the direction of the applied force, it indicates that the muscles responsible for supporting the upper body were not effectively working. Conversely, if the subject was able to support their upper body, it indicates that the trapezius muscle or inner muscles were working to support the upper body. If the subject was unable to maintain their posture when the trapezius muscle was stimulated with protrusions, it meant that the muscles working to maintain the upper body were heavily reliant on the trapezius muscle, and maintaining that posture for a long time would cause stiff shoulders, so it could not be considered an ideal sitting posture. If the subject was able to maintain their posture even with stimulation from the protrusions, it indicated that both the trapezius muscle and the inner muscles were working sufficiently. If the inner muscles are working, sitting for long periods of time is less likely to cause stiff shoulders, which is ideal. In this study, subjects were instructed to sit for 30-120 minutes under individual conditions, and the presence and severity of back pain or discomfort (over-tension, stiffness, etc., in the trapezius muscle) was recorded to confirm the above-mentioned assumptions regarding the trapezius muscle and inner muscles. The inner muscles are thought to be the multifidus muscle, iliopsoas muscle, etc.

[0052] (4)-1-2: Results of the first test The results of the first test are shown in Figure 3. Figure 3 is a graph showing the function of muscles such as the trapezius muscle in relation to the thickness and angle of the convex structure at the rear of the seat. The vertical axis is the thickness of the convex structure (a: mm), and the horizontal axis is the elevation angle (φ) at the rear of the groove structure. In the graph in Figure 3, "○" indicates the angle and thickness points using a wooden seat, "△" indicates the angle and thickness points using a TPE seat, and "□" indicates the angle and thickness points using a yellow urethane seat. Each point "○, ​​△, □" represents the aggregated test results of the five subjects mentioned above, and the evaluations of the five subjects have been standardized for each point, classifying them into areas 1-5. This confirms that there is no individual variation in the effect on posture provided by the setting conditions of the present invention. Furthermore, in this test, no difference in the effect of the present invention due to differences in seat material was observed.

[0053] Area 1 represents the area where the length (straight length) of the slope of the convex structure is 55 mm or less. In Area 1, the slope is short, and in all φ areas, it was not possible to support the waist of the subjects, whose height is in the range of 150-175 cm, and the waist escaped from the groove structure, making it impossible to perform a substantial measurement. Area 2 represents the area where the length of the slope of the convex structure is 55 mm or more, and the φ is less than 10 degrees. In Area 2, the subjects were unable to support their upper bodies against the load on their shoulders, indicating that the subjects' trapezius muscles and other muscles were not working. Area 5 represents the area where the length of the slope of the convex structure is 55 mm or more, and the φ exceeds 60 degrees. Similar to Area 2, in Area 5 as well, the subjects had difficulty supporting their upper bodies against the load on their shoulders, indicating that the subjects' trapezius muscles and other muscles were not working. Even if they forced themselves to sit, they would arch their backs, making it inappropriate. Area 3 represents the area where the length of the slope of the convex structure is 55 mm or more, and the φ is between 10 and 35 degrees. In Area 3, subjects were able to support their upper bodies against shoulder loads, but when the trapezius muscle was released by pressing it with the protrusion, they were unable to support their upper bodies. Therefore, in Area 3, it was found that only the trapezius muscle, among the upper body muscles of the subjects, was working in tension to support the upper body. As a result, there is a tendency to slouch even when sitting in Area 3. Area 4 is an area where the length of the inclined surface of the convex structure is 55 mm or more, and the diameter is 35-60 degrees. In Area 4, subjects were able to support their upper bodies against shoulder loads, and they were able to support their upper bodies even when the trapezius muscle was released by pressing it with the protrusion. Therefore, in Area 4, it was found that not only the trapezius muscle, but also the inner muscles were working to support the upper body, and a pelvic angle that allows for maintaining an appropriate sitting posture was maintained.

[0054] Note that in the graph in Figure 3, the vertical axis only shows thicknesses up to 60 mm, but even when the thickness was increased to 80 mm, the results were the same as those for Area 2-5 above.

[0055] <Second (d)(e) Exam> (4)-2-1: Method of the second examination In the second trial, we included subjects with shorter stature to determine the acceptable limits for the length of the inclined surface of the convex structure (the thickness of the convex structure), taking into account the user's height.

[0056] The subjects consisted of a total of nine individuals (height in parentheses): an 8-year-old female (125cm), an 81-year-old female (140cm), a 62-year-old female (153cm), a 70-year-old female (157cm), a 48-year-old female (162cm), a 75-year-old male (163cm), a 48-year-old male (175cm), a 55-year-old male (184cm), and a 12-year-old male (153cm).

[0057] The "Measurement Chair 700" used in the first test was used as the measurement chair, with 20θ fixed at 45 degrees, the thickness of the front part of the seat 20a fixed at 20 mm, the distance between the lower ends of the front and rear cutouts (20b) fixed at 15 mm, and 20φ fixed at 45 degrees. The specific test method was the same as in the first test. Tests were performed on each subject with various lengths of slopes.

[0058] (4)-2-2: Results of the second test The results of the second trial are shown in Figure 3-2. In Figure 3-2, the boundary between "Area 4: Trapezius muscle + inner muscle activity area" (optimal area) and Area 1 "Area of ​​difficulty in supporting the body" in Figure 3, which pertains to the first trial, was examined for each subject. In Figure 3-2, the horizontal axis represents the subject's height (cm), and the vertical axis represents the slope length (mm). For each subject, the slope length in the vicinity of the boundary with Area 1, which is within Area 4, is illustrated in relation to the subject's height.

[0059] The results showed that when the slope length was 55 mm (the boundary slope length derived in the first test), a height of 175 cm or less would fall within "Area 4". However, it also became clear that for slightly taller individuals, a slope length of 55 mm made upper body support difficult (placing them in Area 1). Furthermore, considering the average height of Japanese people, it became clear that a slope length of 60 mm or more generally placed individuals within "Area 4". In addition, it became clear that even for short individuals, upper body support became difficult when the slope length was less than 45 mm. In other words, it became clear that even when designing for very short users (around 140 cm or less) or children, the lower limit for the slope length is 45 mm.

[0060] 2. Examples of seat or chair forms of the present invention Figure 4 shows a perspective view (Figure 4(1)) of a seat portion 10, which is one embodiment of the seat portion of the present invention, and a cross-sectional view taken along line I-I' near its groove structure. The reference numerals generally correspond to those in Figure 2(1).

[0061] The flat plate member 10A constituting the seat portion 10 has a curved surface at the front edge 101A of the seat surface, which is one of the surfaces in the thickness direction, with a curved cross-section of R-shape with a bending angle of approximately 90 degrees. The shape of the front edge 101A of the seat surface is not limited to this curved surface, but it is one of the preferred shapes that gives the sitter a smooth sitting experience. The two slide-shaped members 10B1 and 10B2, which correspond to the above-mentioned convex structure, are "right-angled trapezoidal prism members with congruent upper and lower surfaces," if we disregard their role in the present invention, but considering the manner of use, it is more descriptive to describe them as "slide-shaped members" as described above. The sides of the right-angled trapezoid, including both diagonal lines, are slopes 101B1 and 101B2, which function as "slide-shaped members." These slide-shaped members 10B1 and 10B2 fit into the two U-shaped notches of the flat plate member 10A from the front to the back, and this fitting provides groove structures 10C1 and 10C2 in the seat portion 10. The upper part of these seat portions 10 is bonded to the bottom plate 10F across its entire lower surface, so that the bottoms of the groove structures 10C1 and 10C2 are closed flat (no "other areas" are provided).

[0062] The seat portion 10 described above must meet the requirements of the seat portion of the present invention.

[0063] As described above, the longitudinal distance between the two groove structures 10C1 and 10C2 is not particularly limited as long as the "position where the ischial tuberosities fit when seated" is ensured. Depending on individual differences in the distance between the ischial tuberosities, it is also possible to model several typical distances between the ischial tuberosities and provide the two groove structures described above accordingly. Furthermore, in order to flexibly accommodate such individual differences in the distance between the ischial tuberosities, it is possible to set the longitudinal width of each groove structure 10C1 and 10C2 to be longer than the length in which the ischial tuberosities fit, and as will be shown in the alternative embodiment described later, it is also possible to make the groove structures 10C1 and 10C2 continuous in the longitudinal direction. Including this embodiment of "making them continuous in the longitudinal direction", the longitudinal distance 10α between the groove structures 10C1 and 10C2 is preferably about 0 (continuous embodiment) to 150 mm. In other words, the longitudinal distance between the groove structures 10C1 and 10C2 when set to the length in which the ischial tuberosities fit is estimated to be approximately 150 mm at most. Furthermore, the lengthwise width 10β of each groove structure 10C1 and 10C2 is 15 mm or more.

[0064] The groove structures 10C1 and 10C2 are formed by opposing surfaces, one extending from the upper edge to the lower edge on the front edge side of the seat surface, and the other extending from the upper edge to the lower edge on the rear side of the seat surface. The width narrows in the thickness direction from the upper edge to the lower edge, and the width 10b at the lowest point of the seat portion 10 in the thickness direction corresponds to the width of the bottom of the groove structures 10C1 and 10C2. In this embodiment, the thickness 10a of the flat plate member 10A corresponds to the depth of the groove structures 10C1 and 10C2, and is 6-30 mm, preferably 10-20 mm. The width of the deepest part of each of the groove structures 10C1 and 10C2 is in the range of 5-25 mm, preferably 10-20 mm, as described above. The elevation angle 10θ on the front edge side of the seat surface is 20-90 degrees, preferably 30-45 degrees, and the elevation angle 10φ on the rear side of the seat surface is 35-60 degrees, preferably 40-55 degrees. Furthermore, the lengths of slopes 101B1 and 101B2 are 45-150 mm.

[0065] Figure 5 shows several variations of the seat 10 described above. Figure 5(1) is a perspective view of the seat 10, while Figure 5(1)-2 shows a seat 10' in which slide-shaped members 10B1' and 10B2' are used, with the length of the slopes 101B1 and 101B2 being increased (101B1' and 101B2'). The seat 10' has a base plate 10F attached to it, similar to the seat 10. The length of the slopes 101B1 and 101B2 satisfies the above conditions for 10φ and 10c in the present invention. Figure 5(2) shows a seat 10 in which the slide-shaped members 10B1 and 10B2 are replaced with a support for the buttocks when seated, which is continuous with the upper edge of the slide-shaped members. curved surface The seat 10-2 uses a pair of hip support members 10B11 and 10B21, to which 10B111 and 10B211 are added, and in contrast, Figure 5(2)-2 shows its slope or curved surface Figure 5(3) shows the seat 10-2' using a pair of hip support members 10B11'·10B21' which are larger versions of (10B111'·10B211'). In place of the pair of hip support members 10B11·10B21 of the seat 10-2, there is an additional slope or curved surface The seat 10-3 uses hip support members 10B12 and 10B22, which have a gentle and long slope of 10B112 and 10B212 that extends to near the front edge of the seat surface. In contrast, Figure 5(3)-2 shows the seat 10-3' which uses a pair of hip support members 10B12' and 10B22', with a larger slope or curved surface (10B112' and 10B212').

[0066] Figure 6 is a perspective view (Figure 6(1)) of a seat portion 20, which is one embodiment of the seat portion of the present invention. Its reference numerals also generally conform to those of Figure 2(1).

[0067] The seat portion 20 consists of a pair of thigh support members 20A1 and 20A2, and a pair of buttock support members 20B1 and 20B2, placed on a base plate 20F. In each pair of thigh support members 20A1 and buttock support members 20A2 and buttock support members 20B1 and 20B2, the "slope on the rear edge side of the seat surface of the thigh support member and the slope on the front edge side of the seat surface of the buttock support member" face each other, causing the seat portion 20 to narrow from the top surface to the bottom surface, and forming a region where the bottom surface is formed by the base plate 20F, i.e., a groove structure 20C1 and 20C2. The groove structures 20C1 and 20C2 are continuous with the longitudinal groove section 20G in between, and the ends on the side of the seat surface are open. The thigh support members 20A1 and 20A2 are flat plate-type members and are fixed so as to be mirror-symmetric with respect to the center line II-II' connecting the midpoints of the front and rear edges of the seat surface. The surfaces 201B1 and 201B2 of the buttock support members 20B1 and 20B2 on the front edge side of the seat surface have a slope with an elevation angle of 20φ on the side of the center line II-II' of the seat surface, and continuous with this on the side, the cross section is R-shaped with a bending angle of approximately 90 degrees. curved surface , accompanied by. The shape of this buttock support member is one of the preferred forms that provides a smooth seating experience to the sitter. In addition, the surfaces 201A1 and 201A2 of the thigh support members 20A1 and 20A2 on the rear edge side of the seat surface are sloped surfaces with a predetermined angle 20θ that satisfies the requirements of the present invention. Furthermore, along the center line II-II', a vertical groove 20G is formed, with both ends open and the bottom surface formed by the bottom plate 20F.

[0068] The width 20b of the bottom of each groove structure 20C1 and 20C2 is 5-25 mm, preferably 10-20 mm, as described above. The thickness 20a of the thigh support members 20A1 and 20A2 corresponds to the depth of the groove structures 20C1 and 20C2, and is 6-30 mm, preferably 10-20 mm. The length of the slanted side (straight portion) formed by the buttock support members 20B1 and 20B2 is 45-150 mm. The elevation angle 20θ at the bottom of the groove structure of the thigh support members 20A1 and 20A2 is 20-90 degrees, preferably 30-45 degrees, and the elevation angle 20φ at the bottom of the groove structure of the buttock support members 20B1 and 20B2 is 35-60 degrees, preferably 40-55 degrees.

[0069] Figure 7 shows several variations of the seat 20 described above. Figure 7(1) is a perspective view of seat 20-1 in which buttock support members 20B11 and 20B12, which are lower in height (Figure 6:20c), are provided in place of the buttock support members 20B1 and 20B2 of seat 20. In contrast, Figure 7(1)-2 is a perspective view of seat 20-1' in which buttock support members 20B11' and 20B12', which are higher in height (Figure 6:20c), are provided in place of the buttock support members 20B1 and 20B2. Figure 7(2) shows a seat 20-2 that uses buttock support members 20B21 and 20B22, which have the same height as the lower buttock support members 20B11 and 20B12 shown in Figure 7(1), but can be bonded together with the thigh support members 20A1 and 20A2 to form an inclined bridge. Figure 7(2)-2 shows a seat 20-2' that uses taller buttock support members 20B21' and 20B22', which have extension ends 2021B1' and 2021B2', and can be bonded together with the thigh support members 20A1 and 20A2 to form an inclined bridge. Figure 7(3) shows a seat 20-3 that uses buttock support members 20B31 and 20B32, which have the same height as the low buttock support members 20B11 and 20B12 shown in Figure 7(1), but can be formed into an inclined bridge by bonding them together with the thigh support members 20A1 and 20A2, and have longer legs than the extended end parts 2021B1 and 2021B2 shown in Figure 7(2). Figure 7(3)-2 shows a seat 20-3' that uses taller buttock support members 20B31' and 20B32', which have longer leg extensions 2031B1' and 2031B2' and can be bonded together with thigh support members 20A1 and 20A2 to form an inclined bridge, instead of the shorter buttock support members 20B31 and 20B32 with long leg extensions shown in Figure 7(3).

[0070] Figure 8(1) is an exploded assembly diagram of chair 100, which is an example of an embodiment of the chair of the present invention, and Figure 9 is a completed view of chair 100.

[0071] The chair 100 can be manufactured, for example, by fixing the upper part of the seat 10 of the present invention, excluding the bottom plate 10F (hereinafter also referred to as "the upper part of the seat 10"), to the seat fixing part 31 of the chair part 30. The chair part 30 has the external shape of a "heighted chair" except that the upper part of the seat 10 is not fixed, and this height is maintained by four legs 32e, f, g, h. The seat fixing portion 31 of the chair portion 30 is kept approximately horizontal to the ground with sufficient strength to withstand a person sitting on it, thanks to the support force provided by the legs 32e and 32f located directly below the lower surfaces of both ends on the front edge side of the seat, and the engaging and fixing force provided by the engagement and fixing of the square timbers 32g and 32h, respectively, to the outer side edges 32g' and 32h' of the seat fixing portion 31, which are formed by cutting out rectangular notches, located at both corners on the rear edge side of the seat fixing portion 31. The square timbers 32g and 32h are continuous with the legs of the chair portion 30 and constitute part of the backrest portion 33. That is, the square timbers 32g and 32h are connected to each other by three round timbers 34e, 34f and 34g above the seat fixing portion 31, thereby forming the backrest portion 33 of the chair portion 30. In this way, the chair portion 30 maintains a shape similar to that of a "heightened chair with a backrest" while also possessing the strength required of a chair. The lower end of the front edge 101A of the seat portion 10 is fixed to the seat portion 31 of the chair portion 30 so as to form a single smooth surface continuous with the upper end of the front edge 311 of the seat fixing portion 31 of the chair portion 30, and the rear edge of the seat is fixed to the seat fixing portion 31 of the chair portion 30 so as to be in close contact with the square timbers 32g and 32h. The chair 100 is constructed in this manner.

[0072] Figure 10(1) shows a chair 100-2 in which the upper part of the seat portion 10 is provided on the chair portion 40 shown below.

[0073] In this example, the upper part of the seat portion 10 is fixed to the seat fixing portion 31, but it is also possible to fix the seat portion 10, including the base plate 10F, directly to the seat fixing portion 31 to create a configuration similar to a chair 100.

[0074] Furthermore, Figure 10(1) shows an embodiment in which the upper part of the seat portion 10 is fixed to the seat fixing portion 41 of the chair portion 40 described below. In this way, a chair portion can be selected and the seat portion of the present invention can be provided as its seat, to the extent that the requirements of the present invention are met.

[0075] Figure 8(2) is a schematic diagram of the disassembled and assembled chair 200, which is an example of an embodiment of the chair of the present invention, and Figure 10(2) is a completed view.

[0076] The chair 200 can be manufactured, for example, by fixing the parts of the upper part of the seat 20 of the present invention, excluding the bottom plate 20F (hereinafter also referred to as "the upper part of the seat 20"), to the seat fixing part 41 of the chair part 40. The backrest part 43 of the chair part 40 is provided with a backrest plate 44 covering almost its entire surface. This backrest plate 44 can be configured to remain immovable even when a seated person leans against it, or it may have flexibility to flex under the weight of the person leaning against it. In addition, a means for adjusting the vertical position of the backrest plate 44 may be provided by grooves 433 that guide and support both sides of the backrest plate 44 (in Figure 8(2), this means for adjusting the vertical position of the backrest is omitted). A lumbar support plate 431 is provided on the backrest plate 44, slightly below the seating side, at the position where the seated person's posterior superior iliac spine makes contact. This plate has a gently concave arch along its length that forms its front surface. In addition, a group of small protrusions 432, consisting of five rounded small protrusions 4321 arranged vertically in two sets symmetrically with respect to the seated person's midline, is provided from near the center of the height direction of the backrest plate 44 upwards from the center of the width direction. The position of this group of small protrusions 432 is where the seated person's trapezius muscle makes contact when the direction the seated person's back faces is at an elevation angle of 35-60 degrees, relative to the horizontal plane of the ground (0 degrees).

[0077] In this example, the upper part of the seat portion 20 is fixed to the seat fixing portion 41, but it is also possible to fix the seat portion 20, including the base plate 20F, directly to the seat fixing portion 41 to create a configuration similar to a chair 200.

[0078] In any of the above-described embodiments of the chair of the present invention, the method of fixing the chair portion to the seat portion or the upper part thereof is not limited and may be a fixing method using screws, adhesive, etc., or a detachable fitting method, etc.

[0079] Figure 11 is a schematic diagram showing the posture of a person sitting in the chair of the present invention. Figure 11(1) is a schematic diagram of a person sitting in chair 100-2. The person sitting 50 is shown, with their spine and ischial tuberosities (51) simplified. The left and right ischial tuberosities of the person sitting 50 fit into the groove structures 10C1 and 10C2, and the position of the left and right ischial tuberosities is correctly controlled by the internal shape, resulting in a correct posture that is also less tiring. It is thought that by doing this habitually and continuously, it may be possible to correct the posture of the person sitting 50. Figure 11(2) is a schematic diagram of a person sitting in chair 200, and its effect is the same as that of chair 100-2 in (1).

[0080] <Effects of continuous use> A real-world usage test was conducted to examine the posture-correcting effect on seated individuals before and after using the seat of the present invention.

[0081] The seat portion 80 of the present invention used in this practical test is shown in Figures 13-1 and 13-2. Figure 13-1 is an overall perspective view of the seat portion 80, and Figure 13-2 is a longitudinal cross-sectional view of the area near the groove structure at line III-III'.

[0082] The wooden seat 80 is provided with two groove structures 80C1 and 80C2, the bottoms of which are open. The two identically shaped convex structures 80B1 and 80B2 are provided with inclined surfaces 801B1 and 801B2, respectively, and are connected to buttock support members 80B11 and 80B12. The specific dimensions and shape of the seat 80 are as follows.

[0083] The depth 80a of the lower narrow region within the groove structure of the seat is 15 mm; the width 80b of the deepest part of the lower narrow region within the groove structure of the seat is 20 mm; the depth 80c from the upper edge of the convex structure of the seat to the deepest part of the lower narrow region is 45 mm; the width of the seat is 300 mm; the length 80j of the front edge of the seat surface is 360 mm; the upper depth 80k of the convex structure 80B1 is 55 mm; the sleeve length 80n of the hip support member 80B11 is 80 mm; the width of the thigh support portion is 155 mm; the front elevation angle 80θ of the groove structure is 30 degrees; and the rear elevation angle 80φ is 45 degrees.

[0084] The seat portion 80 was placed on a chair without a backrest, with the front edge 81 of the seat portion 80 overlapping the front edge of the chair. The subject (a woman in her 70s) was asked to sit on the chair so that her ischial tuberosities fit into the groove structures 80C1 and 80C2. This was continued for approximately 4 hours each day for 4 weeks. Figure 14 shows images of the subject's back as she sat before and after the start of the experiment, taken with her permission. Figure 14(1) shows the image before the start of the experiment, and Figure 14(2) shows the image 4 weeks after the start of the experiment. Before the start of the experiment, her upper body was tilted to the left and she had a hunched back, but it can be seen that the leftward tilt and hunched back were corrected after 4 weeks. The corrective effect of using the seat portion of the present invention on sitting posture was observed. [Explanation of Symbols]

[0085] Seat:10,10',10-2,10-2',10-3,10-3',20,20-1, 20-1', 20-2, 20-2', 20-3, 20-3', 60, 80 Front part of the seat: A, A1 Flat plate members: 10A, 80A Thigh support members: 20A1, 20A2 Rear edge side of the seat: 201A1, 201A2 Seat front edge 101A, 81 Seat convex structure: B, B1, 60B, 80B1, 80B2 Slide-type components: 10B1, 10B2, 10B1', 10B2' Slopes: 101B1, 101B2, 101B1', 101B2', 801B1, 801B2 Buttock support members: 10B11, 10B21, 10B11', 10B21', 10B12, 10B22, 10B12', 10B22', 20B1, 20B2, 20B11, 20B12, 20B11', 20B12', 20B21, 20B22, 20B21', 20B22', 20B31, 20B32, 20B31', 20B32', 80B11, 80B12 Extension tip: 2021B1, 2021B2, 2021B1', 2021B2', 20 31B1,2031B2,2031B1',2031B2' Front edge side of the seat: 201B1, 201B2 curved surface :10B111,10B211,10B111',10B211',10B112,10B212,10B112',10B212' Groove structure of the seat: C, 10C1, 10C2, 20C1, 20C2, 60C Lower narrow region within the groove structure of the seat: D Depth of the lower narrow region within the groove structure of the seat: a, 10a, 20a, 60a, 80a Width of the deepest part of the narrowest lower region within the groove structure of the seat: b, 10b, 20b, 80b Depth from the upper edge of the convex structure of the seat to the deepest part of the narrow lower region: c, 10c, 20c, 60c, 80c Width of the opening on the upper side of the groove structure of the seat: d Seat width: 80i Length of the front edge of the seat: 80j Top depth of convex structure: 80k Sleeve length of the hip support member: 80n Width of the thigh support section: 80m Front elevation angles of the groove structure in the seat: θ, 10θ, 20θ, 80θ Rear elevation angle of the groove structure in the seat: φ, 10φ, 20φ, 80φ Other regions within the groove structure of the seat: E, E1, E1', E2, E2', E3, E3', E4, E4', E5, E5', E6, E6', E7, E7', E8, E8', E9, E9' Depth of other regions: a' Longitudinal distance between groove structures: 10α, 80α Width in the longitudinal direction of the groove structure: 10β, 80β Seat bottom plate: F, 10F, 20F, 60F, F1, F1', F2, F2', F3, F3', F4, F4', F5, F5', F6, F6', F7, F7', F8, F8', F9, F9' Vertical groove: 20G Massage board: J Massage plate protrusion: J1 Cutting surface of the convex structure of the seat: L Chair part:30,40 Seat fixing part: 31, 41 Seat front edge: 311 Lateral outer edge 32g', 32h' Backrest section: 33, 43, H Round material: 34e, 34f, 34g Backrest: 44 Waist support plate: 431 Groove section: 433 Small protrusion group: 432 Small protrusions: 4321 Seated: 50 Spine and pelvis: 51 Chairs: 100, 100-2,200 Chair legs: 32e, 32f, 32g, 32h Measuring chairs: 600, 700 Distance from groove structure to backrest: 60γ, 20γ

Claims

1. A seat for forming a correct sitting posture by stabilizing the position of the sitter's ischial tuberosities and orienting the pelvis to a predetermined angle, by sitting with the sitter's ischial tuberosities fitted into the groove structure of the seat, which is made of a material that maintains the shape of the region described in (1) below when the sitter sits; (1) In the groove structure described above, the depth of the region that narrows from the upper surface to the lower surface of the seat is 10-20 mm, and the width of the deepest part of this region is 10-20 mm. (2) The elevation angle relative to the horizontal plane (0 degrees) of the ground, as viewed from the deepest part of the front cut surface formed in the area that narrows from the upper surface to the lower surface of the seat in the groove structure described above, is 30-45 degrees, and the elevation angle relative to the horizontal plane (0 degrees) of the ground, as viewed from the deepest part of the cut surface formed in the convex structure described above in the narrowed area, is 40-55 degrees. (3) In the groove structure described above, the straight length of the cut surface from the upper edge to the deepest part in the convex structure in the region where the width narrows from the upper surface to the lower surface of the seat is 60-100 mm. (4) The length between the left and right ends of each of the pair of groove structures provided on the left and right sides in the longitudinal direction is 15 mm or more when considering the length of each of the pair of groove structures; Seat area.

2. The material constituting the seat is one or a combination of materials selected from wood, metal, stone, hard plastic, carbon fiber, and urethane, and the urethane is specified in JIS K6401 standard as follows (a), (b), and (c): (a) Type: Type 1 HB, which is a high-elasticity type block, slab stock, or processed product thereof, or Type 2 HM, which is a high-elasticity type molded product; (b) Class: S (harsh), V (very harsh), or X (extremely harsh); (c) Grades are: 400 (365-425N), 470 (430-520N), or 600 (525-650N); The seat portion according to claim 1, wherein the urethane conforms to the requirements.

3. The seat according to claim 1, wherein below the deepest part of the region in the groove structure of the seat that narrows from the top surface to the bottom surface of the seat, there is a region where the front and rear sides face each other with a steeper downward slope than the aforementioned narrow region.

4. The seat portion according to claim 1, wherein the groove structure is continuous in the longitudinal direction and its ends are open on the left and right sides of the seat portion.

5. The seat according to claim 1, wherein the seat is divided into left and right sections in the longitudinal direction, and other grooves, which are open at the bottom or closed at the bottom, are continuously provided from the rear edge to the front edge of the seat.

6. The seat according to claim 1, wherein the notched surface in the convex structure of the seat has a slope with an elevation angle of 40-55 degrees on the center line side connecting the midpoint of the front edge and rear edge of the seat surface on the notched surface, and R-curved shapes that fit the buttocks when seated are formed on both sides continuous therewith.

7. A chair having a seat portion as described in any one of claims 1 to 6 as its seat surface.

8. The chair according to claim 7, wherein a mechanism is provided to maintain or adjust the height of the seat when sitting.

9. The chair according to claim 8, wherein a mechanism for maintaining or adjusting the height of the seat when sitting is provided as a leg.

10. The chair according to claim 7, further comprising a backrest.

11. The chair according to claim 10, wherein a means for distributing the weight of a seated person is provided on the backrest at a position where the seated person's posterior superior iliac spine makes contact, and the means for distributing the weight is provided at a distance of 20-150 mm in the width (front-to-back) direction from the lower end of the cut surface of the convex structure on the seat, and is projected onto the ground horizontal plane (0 degrees).

12. The chair according to claim 10, wherein, when the direction in which the seated person's back faces is at an elevation angle of 35-60 degrees with respect to the horizontal plane of the ground (0 degrees), one or more protrusions are provided on the backrest at a position where the seated person's trapezius muscle makes contact, and the position where the trapezius muscle makes contact is within the intersection area of ​​the backrest surface and the extension line from the lower end of the cut surface of the convex structure on the seat towards the upper edge, when the elevation angle from the lower end of the cut surface of the convex structure on the seat is considered to be 35-60 degrees.

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