JP7482941B2 - Posture support device - Google Patents

Description

The present invention relates to a posture-maintaining device.

Patent Document 1 discloses a posture-maintaining device that maintains the correct posture of a seated person. This posture-maintaining device is equipped with a buttocks support section that supports the buttocks of the seated person from below, and a lumbar support section that rises from the rear edge of the buttocks support section. The lumbar support section has a height that allows it to support the lower end of the seated person's waist and back, and is shaped like a roughly rectangular thick plate overall.

JP 2014-12130 A

The above posture retainer has a generally flat front surface (the surface where the waist and back come into contact) of the lumbar support part, making it easy for the seated person to tilt or twist their upper body left or right. However, because this posture retainer cannot stabilize the upper body of the seated person in the correct posture, there is a concern that the seated person may spend long periods of time with their upper body tilted or twisted left or right.

The present invention was developed based on the above circumstances, and its purpose is to keep the upper body of a seated person in the correct posture.

The posture support device of the present invention comprises:
A seat portion,
A backrest portion rising from a rear end portion of the seat portion;
A first support portion that constitutes the backrest portion and abuts against a left-right central portion of a back of a seated person;
A pair of second support parts that constitute the backrest part and are arranged on both left and right sides of the first support part,
The region supported by the first support portion is the entire or a part of the back of the seated person ranging from the upper lumbar vertebrae to the lower thoracic vertebrae,
The upper end of the first support portion is curved so as to bulge obliquely upward and forward ,
The pair of second support parts are adapted to abut against the left and right sides of the back of a seated occupant,
The region supported by the pair of second support parts is the whole or part of the area of the rib cage on the back of the seated person, which corresponds to the area extending from the lower thoracic vertebrae to the middle height of the thoracic vertebrae .

The seated person sits with the center of the back against the first support part and both the left and right sides of the back against the second support part. Since the posture maintaining device of the present invention supports the back of the seated person with three support parts, it is possible to prevent the upper body of the seated person from being tilted or twisted to the left or right, and to maintain the upper body of the seated person in the correct posture.

FIG. 1 is a perspective view of a posture maintaining device according to a first embodiment of the present invention; Front view of posture support device Plan view of the posture support device 3 is a cross-sectional view taken along line A-A in FIG. 2, with the exterior sheet omitted. 3 is a cross-sectional view taken along line B-B in FIG. 2 with the exterior sheet omitted. 3 is a cross-sectional view taken along line CC of FIG. 2 with the exterior sheet omitted. 3 is a cross-sectional view taken along line D-D in FIG. 2, with the exterior sheet omitted. 3 is a cross-sectional view taken along line E-E of FIG. 2 with the exterior sheet omitted. 3 is a cross-sectional view taken along line F-F of FIG. 2, with the exterior sheet omitted. 3 is a cross-sectional view taken along line G-G in FIG. 2 with the exterior sheet omitted. 4 is a cross-sectional view taken along line H-H of FIG. 3, with the exterior sheet omitted. A cross-sectional view of the posture support device taken along line A-A in FIG.

In the present invention, upper ends of the pair of second support parts may be curved so as to bulge obliquely upward and forward.

In the present invention, the pair of second support portions may extend obliquely forward from both left and right side edges of the first support portion.

Example 1
A first embodiment of the present invention will be described below with reference to Figures 1 to 12. In the following description, the front-rear direction is defined as the left in Figures 4 to 6 and 12, and the bottom in Figures 3 and 7 to 10. The up-down direction is defined as the top and bottom directions as they appear in Figures 1, 2, 4 to 6, 11 and 12. The left-right direction is defined as the left and right directions as they appear in Figures 2, 3 and 7 to 11.

The posture support device 10 of this embodiment 1 is symmetrical in shape and function, and is composed of a seat part 11 that supports the buttocks 51 of the seated person 50 from below, and a backrest part 16 that supports the back 52 of the seated person 50 from behind. The seat part 11 and the backrest part 16 are integrated. In this embodiment 1, the "back 52 of the seated person 50" is defined as the back and waist part of the seated person 50 (the back side and side side of the trunk of the upper body).

The planar shape of the seat 11 will be described. As shown in FIG. 3, the rear end support region 12R, which extends from the rear end of the seat 11 to approximately 2/3 of the front in the front-rear direction, is a trapezoid that gradually widens toward the front. The width dimension (left-right dimension) of the seat 11 is maximum in the rear end support region 12R. The outer peripheral edge of the front end support region 12F of the seat 11, which is forward of the rear end support region 12R, is composed of a pair of symmetrical front curved edges 13 and a front edge scoop 14. The front curved edges 13 are connected to both left and right side edges of the rear end support region 12R and form the front edge of the seat 11. The front edge scoop 14 is recessed at an obtuse angle in the left-right center of the seat 11 and connects the left and right front curved edges 13.

The shape of the seat 11 as viewed from the front will now be described. As shown in Figures 2 and 11, the seat 11 is composed of a pair of symmetrical support parts 15 that are curved so that the upper surface side is concave. The seat 11 is higher at the center and both left and right ends in the left-right direction, so that it can stably support the buttocks 51 and bases of the thighs of the seated person 50.

As shown in Figures 1 and 4, the backrest 16 rises upward from the rear end of the seat 11. The backrest 16 is composed of a first support 17 that constitutes the left-right center of the backrest 16, and a pair of symmetrical second support parts 18 that constitute both left and right side edges of the backrest 16. The left and right second support parts 18 extend diagonally forward in a cantilever shape from both left and right side edges of the first support part 17. The left and right second support parts 18 extend in a direction such that the left-right distance between the second support parts 18 gradually increases toward the front in a plan view.

The front surface of the backrest 16 is a support surface 19 that contacts or faces the back 52 of the seated person 50. The shape of the support surface 19 (backrest 16) in front view will be described. As shown in Figures 2 and 11, the lower end support region 20, which extends from the lower end of the backrest 16 to approximately 2/3 of the upper part in the vertical direction (height direction), is approximately trapezoidal in shape, gradually widening upward. The outer periphery of the upper end support region 21 of the backrest 16 above the lower end support region 20 is composed of a pair of upper curved edges 22 and an upper edge scoop 23 that are symmetrical on the left and right. The upper curved edges 22 are connected to both left and right side edges of the lower end support region 20 and form the upper edge of the backrest 16. The upper recess is recessed at an obtuse angle in the left-right center of the backrest 16 and connects the left and right upper curved edges 22.

The upper curved edge 22 is formed only on the outer periphery of the second support portion 18. The upper edge scoop 23 constitutes the entire area of the upper edge of the first support portion 17 and a part of the upper edge of the second support portion 18. The height dimension of the upper edge of the backrest portion 16 is maximum at the upper end of the upper curved edge 22 and minimum at the bottom end of the upper edge scoop 23 (the left-right center of the backrest portion 16). In other words, the bottom end 17L of the upper edge of the first support portion 17 is located at a lower position than the top end 18U of the upper edge of the second support portion 18. The bottom end 17L of the upper edge of the first support portion 17 is located at a higher position than the bottom end (the height at which the backrest portion 16 is at its widest) of the upper curved edge 22 (upper end support region 21). The bottom end of the upper curved edge 22 is at the height at which the backrest portion 16 is at its widest.

As shown in FIG. 2, the width of the backrest 16 is maximum at the upper end of the lower support region 20 (the lower end of the upper curved edge 22). The maximum width of the backrest 16 is set slightly smaller than the maximum width of the seat 11. The width of the backrest 16 is minimum at the lower end 16L of the backrest 16 (lower support region 20) (i.e., the rear end of the seat 11). The distance (width) between the upper ends of the left and right upper curved edges 22 is smaller than the maximum width of the backrest 16. The height of the backrest 16 is set larger than the front-to-rear dimension of the seat 11.

As shown in Figures 2 and 3, the support surface 19 is composed of a first support surface 24 constituting the first support section 17, and a pair of symmetrical second support surfaces 28 constituting the second support section 18. The first support surface 24 is disposed in the left-right center of the support surface 19, and forms an elongated rectangular shape overall. As shown in Figure 4, the upper end of the first support surface 24 forms a first upper curved surface 25 that bulges diagonally upward and forward and curves diagonally upward and backward.

As shown in FIG. 4, the lower end 24L of the first support surface 24 smoothly connects to the rear end of the seat 11, which is curved to slope upward toward the rear. The area of the first support surface 24 below the first upper curved surface 25 forms a first receiving surface 27 that is generally flat. The first receiving surface 27 is oriented generally vertically when the posture support device 10 is in use. The vertical dimension of the first receiving surface 27 is approximately 1/2 the total height dimension of the first support surface 24.

The pair of left and right second support surfaces 28 are arranged on the left and right sides of the first support surface 24 of the support surface 19. The second support surfaces 28 extend diagonally forward from both left and right side edges of the first support surface 24. The front edge of the second support surface 28 is curved so as to bulge forward. That is, the front-to-rear dimension of the second support surface 28 (extension dimension from the side edge of the first support surface 24) increases toward the top in the upper end support region 21 of the second support surface 28, and decreases toward the bottom in the lower end support region 20 of the second support surface 28.

The area of the second support surface 28 that is close to the first support surface 24 in the left-right direction is the second receiving surface 29. The second receiving surface 29 is generally planar and generally parallel to the extension direction of the second support portion 18. The peripheral portion of the second support surface 28 that surrounds the second receiving surface 29 from above, the front, and below is curved so as to bulge diagonally forward and inward and then bend diagonally backward.

The upper end of the second support surface 28 forms a second upper curved surface 30 that curves so as to bulge diagonally upward and forward and then bend diagonally upward and backward. The left and right second upper curved surfaces 30 are smoothly connected to the left and right side portions of the first upper curved surface 25. The lower end of the second support surface 28 forms a second lower curved surface 31 that curves so as to bulge diagonally downward and forward.

3 and 11, in a plan view, a pair of regions of the support surface 19 connecting the left and right side edges of the first support surface 24 and the second receiving surface 29 of the second support surface 28 are arc-shaped concave connecting surfaces 32. The pair of connecting surfaces 32 are symmetrical and extend vertically. In a plan view, the curvature of the first support surface 24 (first receiving surface 27) and the curvature of the second support surface 28 (second receiving surface 29) are small values almost close to zero, while the curvature of the connecting surface 32 is large. In front of the backrest portion 16, a roughly trapezoidal holding space 33 that is open forward is formed by being partitioned by the first support surface 24, the left and right second support surfaces 28, and the left and right connecting surfaces 32.

The first receiving surface 27 of the first support part 17 is an area of the first support surface 24 against which the center of the back 52 of the seated person 50 in the left-right direction may come into contact when seated. The second receiving surface 29 of the second support part 18 is an area of the second support surface 28 against which both the left and right sides of the back 52 of the seated person 50 may come into contact when seated. The uppermost end position of the first receiving surface 27 is set at a position lower than the uppermost end position of the second receiving surface 29. The first receiving surface 27 is positioned so as to be sandwiched between a pair of second receiving surfaces 29 in the left-right direction. Therefore, the posture support device 10 can support the back 52 of the seated person 50 at three points by one first receiving surface 27 and a pair of second receiving surfaces 29 on the left and right. These three receiving surfaces 27, 29 have height differences and are spaced apart from each other left and right and are spaced apart from each other front to back.

As shown in FIG. 12, the posture support device 10 is composed of an outer shell member 34, a cushioning material 39, and an exterior sheet 40. The outer shell member 34 is a single member made of hard synthetic resin and has a plate shape with a constant thickness over the entire area. The outer shell member 34 is molded into a curved shape that is roughly L-shaped when viewed from the side. The outer shell member 34 is composed of a seat-constituting plate portion 35 that constitutes the seat portion 11, and a backrest-constituting plate portion 36 that constitutes the backrest portion 16. The seat-constituting plate portion 35 has approximately the same shape as the above-mentioned seat portion 11, and is composed of multiple curved plate portions that are curved to have different curvatures. The backrest-forming plate portion 36 rises upward from the rear end of the seat-forming plate portion 35, and is composed of a first support plate portion 37 that constitutes the first support portion 17, and a pair of symmetrical second support plate portions 38 that constitute the second support portion 18.

The shape of the first support plate portion 37 is substantially the same as the first support portion 17 and the first support surface 24 described above. The height region of the first support plate portion 37 corresponding to the first receiving surface 27 is curved so that it bulges forward as a whole in side view, and is oriented slightly forward from the vertical direction when the posture support device 10 is placed on a horizontal surface. The region of the first support plate portion 37 corresponding to the first upper curved surface 25 is curved so that it bows diagonally upward and backward. The region of the first support plate portion 37 corresponding to the first lower curved portion 26 is curved so that it bulges downward and diagonally downward and backward.

The pair of second support plate portions 38 extend diagonally forward from the generally straight left and right side edges of the first support plate portion 37 in a cantilever shape with the left-right distance between them expanding forward. The shape of the second support plate portion 38 is substantially the same as the second support portion 18 and the second support surface 28 described above. The area of the second support plate portion 38 that corresponds to the second receiving surface 29 is generally flat, and the peripheral portion of the second support plate portion 38 is curved so as to bend diagonally backward.

As shown in FIG. 4, the lower end 36L of the backrest-constituting plate portion 36 is connected to the rear end of the seat-constituting plate portion 35, but only the first support plate portion 37 constitutes the lower end portion 36L of the backrest-constituting plate portion 36. In other words, the first support plate portion 37 is directly connected to the seat-constituting plate portion 35, but the second support plate portion 38 is not directly connected to the seat-constituting plate portion 35, but is connected to the seat-constituting plate portion 35 via the first support plate portion 37.

The outer shell member 34 maintains the overall shape of the posture support device 10 and has the rigidity (shape retention) to stably support the posture of the seated person 50. However, when subjected to a static load caused by the weight of the seated person 50 or a dynamic load caused by a change in the seated posture of the seated person 50, it is designed to be elastically deformable to an extent that does not affect the seated posture. Specifically, the second support plate portion 38 is designed to be elastically displaceable relative to the first support plate portion 37 so as to expand in the left-right direction with both left and right side edges of the first support plate portion 37 as approximate fulcrums.

When the above-mentioned static load or dynamic load is applied, the backrest-constituting plate 36 (backrest 16) can be elastically displaced relative to the seat-constituting plate 35 (seat 11) so as to tilt forward and backward with the lower end 36L (rear end of seat-constituting plate 35) of the backrest-constituting plate 36 as a fulcrum. At this time, the amount of elastic deformation of the backrest-constituting plate 36 (stress generated in the backrest-constituting plate 36) is maximum at the lower end 36L, which is the fulcrum of the elastic deformation, but at least the lower end support region 20 of the first support plate 37 also elastically deforms. The elastic deformation of the lower end support region 20 of the first support plate 37 is preferable as a means of avoiding stress concentration at the lower end 36L of the backrest-constituting plate 36.

However, the second support plate portion 38 protruding from both the left and right side edges of the first support plate portion 37 functions as a reinforcing rib that resists the elastic deformation of the first support plate portion 37. Therefore, as shown in Figures 8 to 10, the protruding dimension from the first support plate portion 37 in the lower end region of the second support plate portion 38 is set to gradually decrease downward. As a result, when the backrest-constituting plate portion 36 elastically displaces in the front-rear direction relative to the seat-constituting plate portion 35, the lower end region of the first support plate portion 37 also elastically curves and deforms. In this embodiment 1, the lower end region of the second support plate portion 38 is defined as the region extending from the lower end portion 38L of the second support plate portion 38 to at least about 1/3 of the height.

The cushioning material 39 is attached so as to be layered on the surface of the outer shell member 34 that faces the seated person 50 (the upper surface of the portion that constitutes the seat 11 and the front surface of the portion that constitutes the backrest 16). The cushioning material 39 is made of, for example, urethane foam, and is a member for preventing discomfort caused by the buttocks 51 and back 52 of the seated person 50 hitting the hard outer shell member 34. The thickness of the portion of the cushioning material 39 that corresponds to the first receiving surface 27 is not a constant dimension in the vertical direction, but changes in thickness so that it gradually becomes thicker toward the bottom. As a result, when the posture support device 10 is placed on a horizontal surface, the first receiving surface 27 of the first supporting surface 24 is oriented to rise up approximately vertically.

The exterior sheet 40 is made of cloth and covers the entire outer surface of the outer shell member 34 (the lower surface of the portion that constitutes the seat 11 and the rear surface of the portion that constitutes the backrest 16) and the surface of the cushion material 39 that faces the seated occupant 50 (the upper surface of the portion that constitutes the seat 11 and the front surface of the portion that constitutes the backrest 16). When the outer shell member 34 elastically deforms, the cushion material 39 and the exterior sheet 40 flexibly deform accordingly.

The posture support device 10 can be used by placing it directly on the floor (not shown) or on a chair 53. Figure 12 shows the posture support device being used on a chair. When a seated person 50 sits on the posture support device 10, the buttocks 51 are supported from below by the seat part 11, the upper body trunk is contained within the support space 33, and the back 52 is supported from behind by the backrest part 16. At this time, the part of the back 52 in the left-right central part that corresponds to the lower thoracic vertebrae abuts against the first support surface 24, and the left and right side parts of the back 52 abut against the left and right second support surfaces 28.

At this time, the contact area with the second support surface 28 is higher than the contact area with the first support surface 24 and is further forward than the contact area with the first support surface 24. In other words, the back 52 is supported at multiple locations at different positions in the three-dimensional direction. Also, if the seated occupant 50 is an adult of average build, the contact area with the second support surface 28 is on the back side of the ribs and at a height lower than the shoulder blades.

The posture support device 10 of this embodiment 1 comprises a seat section 11 that supports the buttocks 51 of the seated person 50 from below, and a backrest section 16 that rises from the rear end of the seat section 11 and supports the upper body of the seated person 50 from the back 52 side. The backrest section 16 comprises a first support section 17 that abuts against the left-right center of the back 52 of the seated person 50, and a pair of second support sections 18 that are arranged on both the left and right sides of the first support section 17 and abut against the left and right sides of the back 52 of the seated person 50.

The first support portion 17 supports a relatively low part in the center of the back 52 of the seated person 50 from behind, and the pair of left and right second support portions 18 support the parts of the left and right sides of the back 52 that are higher than the first support portion 17 from the diagonally rearward position. Therefore, the seated person 50 sits with the relatively low part in the center of the back 52 against the first support portion 17 and the relatively high part on the left and right sides of the back 52 against the second support portion 18. The seated person 50 is prevented from tilting the upper body left and right or twisting the upper body left and right because the back 52 is supported by the three support portions 17, 18 at three points spaced apart from each other and at different heights. Therefore, the posture support device 10 of this embodiment 1 can maintain the upper body of the seated person 50 in the correct posture.

The first support section 17 supports a relatively low portion of the back 52 of the seated person 50 (all or part of the range from the upper lumbar vertebrae to the lower thoracic vertebrae), and the second support section 18 supports a relatively high portion of the back 52 (all or part of the portion of the rib cage that corresponds to the lower thoracic vertebrae to the mid-height of the thoracic vertebrae). Therefore, when the seated person 50 leans his/her weight on the backrest section 16, the back 52 is supported at multiple points with different heights. This allows the upper body of the seated person 50 to be kept in a correct posture with the spine properly curved in a side view. Here, the correct posture is a posture in which the thoracic vertebrae are curved so as to bulge backward, the lumbar vertebrae are curved so as to bulge forward, and the sacrum to the coccyx are curved so as to bulge backward.

In addition, if the height of the upper end of the first support part 17 is made the same as the height of the upper end of the second support part 18, the thoracic vertebrae part of the back 52, which curves to bulge backward, may come into contact with the upper end of the first support part 17, making it difficult for the spine to curve properly. As a countermeasure, the posture support device 10 of this embodiment 1 forms an upper edge scooped part 23 on the upper edge of the backrest part 16, making the height of the upper end of the first support part 17 lower than the upper end of the second support part 18. However, when the upper edge scooped part 23 is formed, a space is created immediately above the first support part 17 (i.e., between the upper ends of the left and right second support parts 18), so that the back 52 cannot be supported immediately above the first support part 17. Therefore, there is a concern that the upper body part of the seated person 50 above the first support part 17 (a relatively low part of the back 52) may bend backward, but the upper body part of the seated person 50 is supported by the second support part 18 on both the left and right sides above the first support part 17, so the seated person 50 can sit with a moderately open chest and relaxed posture.

In addition, when the occupant 50 is seated, the second support portion 18 is elastically displaced diagonally backward due to the pressure from the upper body of the occupant 50, and the elastic restoring force of the second support portion 18 (second support plate portion 38) causes the occupant 50 to feel stronger pressure on both the left and right sides of the back 52 than in the center. This prevents the upper body of the occupant 50 from being tilted left or right or twisted left or right.

The upper end of the second support portion 18 is formed with a second upper curved surface 30 that is curved so that it bends diagonally backward as it goes upward, so that when the upper half of the seated person 50 leans deeply against the backrest portion 16, the upper edge of the second support portion 18 does not dig into the body of the seated person 50, and the seated person 50 can sit deeply on the seat portion 11. By sitting deeply, the left and right sides of the back 52 are firmly pressed against the second support portion 18, so that the upper half of the body can be reliably prevented from twisting left and right. Furthermore, because the upper end of the second support portion 18 does not dig into the body of the seated person 50, the upper part of the back 52 can be bent backward appropriately, so that the seated person 50 can be maintained in the correct posture.

The posture support device 10 also has an outer shell member 34 for maintaining its shape. The outer shell member 34 has a seat-constituting plate portion 35 that constitutes the seat portion 11, and a backrest-constituting plate portion 36 that constitutes the backrest portion 16. The backrest-constituting plate portion 36 is connected to the seat-constituting plate portion 35 so that it can be elastically displaced relative to the seat-constituting plate portion 35, with the lower end portion 36L of the backrest-constituting plate portion 36 acting as an approximate fulcrum. Therefore, when the seated person 50 presses the upper half of the body strongly against the backrest portion 16, the backrest portion 16 is elastically displaced backward relative to the seat portion 11, with the lower end portion 36L acting as an approximate fulcrum.

At this time, if stress is concentrated on the lower end 36L of the backrest-constituting plate part 36, which serves as the fulcrum for the relative elastic displacement, there is a concern that repeated stress concentration will cause deterioration and reduce durability. As a means of avoiding stress concentration on the lower end part 36L of the backrest-constituting plate part 36, it is preferable to elastically deform not only the lower end part 36L of the backrest-constituting plate part 36, but also at least the lower end region of the backrest-constituting plate part 36.

However, the backrest-constituting plate portion 36 is difficult to deform because it is made up of the first support plate portion 37 constituting the first support portion 17 and a pair of left and right second support plate portions 38 that protrude diagonally forward from both left and right side edges of the first support plate portion 37 and constitute the second support portion 18. Therefore, the protruding dimension from the first support plate portion 37 in the lower end region of the second support plate portion 38 is gradually reduced downward. As a result, the backrest-constituting plate portion 36 elastically deforms not only at its lower end portion 36L but also at its lower end region, so that it is possible to prevent stress from concentrating on the lower end portion 36L of the backrest-constituting plate portion 36. In addition, the upper end region of the backrest-constituting plate portion 36 has a higher bending rigidity and is difficult to elastically deform compared to the lower end region, so that the upper body of the seated person 50 can be stably supported.

The first support surface 24 of the first support portion 17 facing the back 52 and the second support surface 28 of the second support portion 18 facing the back 52 are connected via a pair of left and right connecting surfaces 32, and the curvature of the first support surface 24 and the curvature of the second support surface 28 are set smaller than the curvature of the connecting surface 32 in a plan view. With this configuration, the back 52 does not come into contact with the connecting surface 32, which has a larger curvature, so the upper body of the seated occupant 50 can be stably supported at three points: the first support surface 24 and the pair of left and right second support surfaces 28.

<Other Examples>
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention.
(1) In the above embodiment, the posture support device has a seat portion and a backrest portion formed as one unit. However, the posture support device may be formed by assembling the seat portion and the backrest portion as separate members.
(2) In the above embodiment, the upper end of the second support portion is curved so as to bend diagonally backward as it extends upward. However, the upper end of the second support portion may not be curved.
(3) In the above embodiment, the backrest-constituting plate portion is formed integrally with the first support plate portion and the second support plate portion, but the backrest-constituting plate portion may also be formed by assembling the first support plate portion and the second support plate portion which are separate members.
(4) In the above embodiment, the protruding dimension from the first support plate portion in the lower end region of the second support plate portion gradually decreases toward the bottom, but the protruding dimension from the first support plate portion in the lower end region of the second support plate portion may be generally constant in the vertical direction.
(5) In the above embodiment, the seat portion and the backrest are elastically displaceable relative to each other. However, the seat portion and the backrest may not be displaceable relative to each other.
(6) In the above embodiment, the first and second support surfaces are connected via a connecting surface with a large curvature, and the back of the seated person is supported at three points spaced apart from each other on the left and right sides, but this is not limited to the above. The curvature of the connecting surface may be made smaller than that of the first embodiment, and the back may be supported in a continuous area in the left-right direction from the second support surface on the left to the second support surface on the right. Even in this case, it is possible to prevent the upper body of the seated person from being tilted or twisted to the left or right.
(7) In the above embodiment, an upper edge hollow is formed on the upper edge of the first support part to leave a space near the upper part of the first support part (between the upper ends of the left and right second support parts), but the height of the upper end of the first support part and the height of the upper end of the second support part may be made approximately the same height without forming an upper edge hollow. Even if the upper edge of such a backrest part is at a constant height over a wide range, if the degree of backward inclination of the area of the upper edge of the backrest part corresponding to the upper end of the first support part is made deeper than the upper end of the second support part, it is possible to prevent the left-right center of the back from strongly hitting the upper edge of the backrest part when the back is bent backward.

LIST OF SYMBOLS 10: Posture maintaining device 11: Seat 16: Backrest 17: First support section 18: Second support section 17L: Lowermost end section at upper edge section of first support section 18U: Uppermost end section at upper edge section of second support section 24: First support surface 28: Second support surface 32: Joint surface 35: Seat constituent plate section 36: Backrest constituent plate section 36L: Lower end section of backrest constituent plate section 37: First support plate section 38: Second support plate section 50: Seated person 51: Buttocks 52: Back

Claims (3)

A seat portion,
A backrest portion rising from a rear end portion of the seat portion;
A first support portion that constitutes the backrest portion and abuts against a left-right central portion of a back of a seated person;
A pair of second support parts that constitute the backrest part and are arranged on both left and right sides of the first support part,
The region supported by the first support portion is the entire or a part of the back of the seated person ranging from the upper lumbar vertebrae to the lower thoracic vertebrae,
The upper end of the first support portion is curved so as to bulge obliquely upward and forward ,
The pair of second support parts are adapted to abut against the left and right sides of the back of a seated occupant,
A posture maintaining device in which the region supported by the pair of second support parts corresponds to the whole or part of the region of the rib cage on the back of a seated person, ranging from the lower thoracic vertebrae to the middle height of the thoracic vertebrae . 2. The posture maintaining device according to claim 1, wherein upper ends of the pair of second support parts are curved so as to bulge obliquely upward and forward. 3. The posture maintaining device according to claim 1, wherein the pair of second support parts extend obliquely forward from both left and right side edges of the first support part .

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