Legless chair

Abstract

To provide a legless chair that can reduce burden on a user in supporting the user's waist and coccyx.SOLUTION: A legless chair 10 includes: a seat part 11 on which a user sits; and a backrest part 12 for supporting the user's back. An opening 31 is formed in a lower part of the backrest part 12, with a waist receiving part 30 provided in the opening 31 for receiving the user's waist from behind. The waist receiving part 30 is rotatable via a rotation mechanism such that an upper part thereof leans frontward. A surface of the front side is formed in a curved shape such that the surface projects toward the user when viewed from lateral side regardless of at which position within a rotatable range the waist receiving part 30 is located.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a seat chair. [Background technology]

[0002] 2. Description of the Related Art Legless chairs have traditionally been used for sitting in Japanese-style rooms, etc. Legless chairs include a seat portion on which a user sits and a backrest portion that supports the user's back.

[0003] Patent Document 1 discloses a legless chair with an opening formed in the lower part of the backrest, in which an auxiliary cushion is provided to support the user's lower back. In this legless chair, the auxiliary cushion is rotatably supported by a shaft provided at its upper part. In this case, the auxiliary cushion rotates by lifting its lower part forward. With this configuration, by rotating the auxiliary cushion and causing it to protrude forward beyond the backrest, the auxiliary cushion can support the user's lower back from behind.

[0004] In the legless chair of Patent Document 1, it is conceivable to use an auxiliary cushion to support the tailbone from behind. In this case, the pelvis is erected, allowing the user to sit with good posture. However, in the legless chair of Patent Document 1, the auxiliary cushion is displaced upward as it rotates forward, making it difficult to support the tailbone from behind with the auxiliary cushion.

[0005] In view of this, Patent Document 2 proposes an auxiliary cushion that is rotatably supported by a shaft provided at its bottom. In this case, the auxiliary cushion rotates by tilting its upper part forward. With this configuration, tilting the auxiliary cushion forward allows the auxiliary cushion to support the user's tailbone from behind. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5753670 [Patent Document 2] Utility Model Registration No. 3205742 Summary of the Invention [Problem to be solved by the invention]

[0007] However, nothing is disclosed about the shape of the auxiliary cushion in the above-mentioned Patent Document 2. In Patent Document 2, it is considered that the auxiliary cushion is formed in the shape of a plate having a predetermined thickness, for example.

[0008] However, if the auxiliary cushion is shaped like a plate, when the upper part of the auxiliary cushion is tilted forward to support the tailbone, the corners of the auxiliary cushion may come into contact with the tailbone, causing the user to feel a localized pressure or discomfort.

[0009] Furthermore, if the auxiliary cushion is shaped like a plate, the corners of the auxiliary cushion may come into contact with the user's lower back when the user uses the cushion to support the lower back, which may cause the user to feel pressure, discomfort, or other strain.

[0010] The present invention has been made in consideration of the above circumstances, and its main object is to provide a chair that can reduce the burden on the user when supporting the user's lower back and coccyx. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a seat chair comprising: a seat on which a user sits; A seat chair comprising: a waist support portion that supports the waist of the user from behind; a rotation mechanism that allows the hip support portion to rotate so that an upper portion of the hip support portion falls forward; The waist support portion is formed so that the front surface thereof has a curved shape that is convex toward the user when viewed from the side, regardless of the position within the rotatable range. [Effects of the Invention]

[0012] The seat chair of the present invention is equipped with a lumbar support portion, which can support the user's lumbar region from behind. The lumbar support portion is also rotatable by a rotation mechanism so that the upper portion of the lumbar support portion can be tilted forward. By rotating the lumbar support portion and tilting the upper portion of the lumbar support portion forward, the lumbar support portion can support the user's tailbone from behind.

[0013] Furthermore, the lumbar support portion is formed so that its front surface has a curved shape that convex toward the user when viewed from the side, regardless of the position within its rotatable range. With this configuration, whether the lumbar support portion is in a position supporting the user's lower back or a position supporting the user's coccyx, the front surface of the lumbar support portion has a curved shape that convex toward the user. Therefore, when the lumbar support portion supports the lower back or the coccyx, it can provide support over a wide range along the curved surface. This reduces the burden on the user when supporting the lower back or coccyx. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] Cross-sectional view of line AA in Figure 3. [Figure 6] 10 is a cross-sectional view showing the chair when the lumbar support portion is at the highest position. FIG. [Figure 7] 10 is a cross-sectional view showing the chair when the lumbar support portion is in the frontmost position. FIG. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing the periphery of the waist support portion of FIG. 7. [Figure 9] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] 1 to 3, the legless chair 10 includes a seat 11 on which a user sits and a backrest 12 that supports the user's back. The seat 11 is formed with cushioning properties and has a rectangular shape in a plan view.

[0017] The backrest 12 is connected to the rear of the seat 11 and is angle adjustable relative to the seat 11. The backrest 12 is formed with cushioning and is rectangular in shape when viewed from the front. The upper part of the backrest 12 forms a head support 14 that supports the user's head. The head support 14 is tiltable forward. The angle of the backrest 12 may not be adjustable.

[0018] As shown in Figure 4, the legless chair 10 has a frame body 20 that forms its framework. The frame body 20 has a seat frame 21 provided inside the seat 11 and a back frame 22 provided inside the backrest 12. The seat frame 21 is integral with the seat 11, and the backrest frame 22 is integral with the backrest 12. The seat frame 21 and the backrest frame 22 are connected via a rotating connector 23. This allows the backrest frame 22 to rotate in the front-to-rear direction relative to the seat frame 21, and this rotation allows the angle of the backrest 12 to be adjusted forward and backward relative to the seat 11.

[0019] The seat frame 21 is formed in a rectangular ring shape from metal pipe material. The backrest frame 22 has a pair of left and right vertical frames 24 extending in the up-down direction, a head support frame 25 spanning the upper ends of each vertical frame 24, and a connecting frame 26 spanning the upper ends of each vertical frame 24. Each of these frames 24 to 26 is formed from metal pipe material. The head support frame 25 is disposed inside the head support portion 14 and is connected to each vertical frame 24 via a pivotable connector 28. This allows the head support frame 25 to pivot forward relative to each vertical frame 24, and this rotation allows the head support portion 14 to tilt forward.

[0020] The seat chair 10 is provided with a lumbar support portion 30 for supporting the user's lumbar region. The configuration of the lumbar support portion 30 will be described below.

[0021] 1 to 3, a rectangular opening 31 is formed in the lower part of the backrest 12 of the chair 10. The opening 31 is formed in the middle part (more specifically, the center part) of the backrest 12 in the left-right direction, and penetrates the backrest 12 in the thickness direction.

[0022] A lumbar support portion 30 is disposed in the opening 31 of the backrest portion 12. The lumbar support portion 30 is formed with cushioning properties and is shaped like a pillow extending in the left-right direction. The width (length in the left-right direction) of the lumbar support portion 30 is approximately the same as the width of the opening 31. The width of the lumbar support portion 30 is 1 / 3 to 2 / 3 of the width of the backrest portion 12.

[0023] As shown in Figures 4 and 5, the frame body 20 has a waist support frame 33 provided inside the waist support section 30. The waist support frame 33 is formed in a U-shape from a metal pipe material. The waist support frame 33 is arranged with the inner area of ​​the U-shape open downward. The waist support frame 33 is connected to a horizontal member 35 provided below it via a connector 36. The horizontal member 35 is formed from a metal square pipe and is bridged across each of the vertical frames 24.

[0024] The connectors 36 are disposed at both ends of the hip support frame 33 and connect the hip support frame 33 to the cross member 35. The connector 36 is a pivotable connector including a well-known ratchet mechanism. The connector 36 has a shaft 36a extending in the left-right direction and a pair of connecting portions 36b, 36c that are pivotable relative to each other via the shaft 36a. Of the pair of connecting portions 36b, 36c, one connecting portion 36b is connected to the hip support frame 33, and the other connecting portion 36c is connected to the cross member 35.

[0025] In the above configuration, the hip support frame 33 extends above the shaft 36a, and the hip support frame 33 is rotatable in the front-to-rear direction around the shaft 36a. In this case, the shaft 36a corresponds to the "rotating shaft," and the hip support frame 33 corresponds to the "support frame." The shaft 36a and the hip support frame 33 together constitute a "rotating mechanism."

[0026] The hip support portion 30 is provided integrally with the hip support frame 33. The hip support portion 30 is rotatable together with the hip support frame 33 around the shaft portion 36a. In this case, the hip support portion 30 is rotatable so that its upper portion falls forward (see the two-dot chain line in FIG. 1). The rotation position of the hip support portion 30 can be adjusted in stages, for example, in 10 to 20 stages. This staged position adjustment is realized by the ratchet mechanism of the connector 36 described above.

[0027] Next, the configuration of the lumbar support portion 30 will be described with reference to Fig. 5. For ease of explanation, in Fig. 5, the backrest portion 12 is indicated by a two-dot chain line.

[0028] 5, the lumbar support portion 30 has a plurality of (specifically, two) cushion materials 41, 42 stacked on top of each other, and a cover material 43 that houses the plurality of cushion materials 41, 42. Each of the cushion materials 41, 42 is formed into a plate shape using a cushioning material, such as urethane foam. These cushion materials 41, 42 form a plate-shaped cushion portion 45.

[0029] The cushion section 45 (each of the cushion materials 41, 42) is provided so as to surround the lumbar support frame 33 from the front, above, and behind. As a result, the cushion section 45 has a curved shape that is convex upward, and is housed in this curved state inside the cover material 43. The cushion section 45 also surrounds the entire lumbar support frame 33, the cross member 35, and the connector 36, and is disposed within the cover material 43 across the entire area in the left-right direction.

[0030] The multiple cushion materials 41, 42 include an outer cushion material 41 arranged on the outside and an inner cushion material 42 arranged on the inside. The thickness t1 of the outer cushion material 41 is smaller than the thickness t2 of the inner cushion material 42, and more specifically, is equal to or less than half the thickness t2 of the inner cushion material 42.

[0031] When the direction in which the cushion portion 45 (cushion materials 41, 42) surrounds the lumbar support frame 33 is defined as the frame surrounding direction, the length of the outer cushion material 41 in the frame surrounding direction is longer than that of the inner cushion material 42. The outer cushion material 41 is arranged in an annular shape, so that both ends in the frame surrounding direction are in contact with or close to each other. On the other hand, both ends of the inner cushion material 42 in the frame surrounding direction are located on both sides of the cross member 35 in the front-rear direction and are spaced apart from each other.

[0032] The cover material 43 is formed into a bag shape using fabric or the like. The cover material 43 is placed on the outer surface of the cushion portion 45, so that the surface of the cover material 43, i.e., the surface of the lumbar support portion 30, is curved along the curved shape of the cushion portion 45.

[0033] A plurality of spacers 47, 48 are interposed between the cushion portion 45 and the lumbar support frame 33. Each spacer 47, 48 is formed from a cushioning material, such as urethane foam. Each spacer 47, 48 is formed in the shape of a plate with a predetermined thickness, and its left-right length is the same as that of the cushion portion 45. Each spacer 47, 48 corresponds to a "spacer portion."

[0034] Each of the spacers 47, 48 includes a first spacer 47 and a second spacer 48. The first spacer 47 is provided so as to surround the upper part of the lumbar support frame 33 in a U-shape. The first spacer 47 is disposed so as to be located in front of, above, and behind the lumbar support frame 33. The second spacer 48 is interposed in front of the first spacer 47 between the first spacer 47 and the cushion part 45. The thickness of the second spacer 48 is greater than the thickness of the first spacer 47.

[0035] In the above configuration, only the first spacer 47 is interposed between the lumbar support frame 33 and the cushion portion 45 behind and above the lumbar support frame 33, and the first spacer 47 and the second spacer 48 are interposed between the lumbar support frame 33 and the cushion portion 45 in front of the lumbar support frame 33.

[0036] Next, the rotation range of the lumbar support portion 30 will be described. As described above, the lumbar support portion 30 is rotatable so that its upper portion can be tilted forward. The lumbar support portion 30 is rotatable between a storage position E1 (position shown in FIG. 2) where the entire lumbar support portion 30 is stored in the opening 31, and a frontmost position E2 (position shown in FIG. 7) where the upper portion of the lumbar support portion 30 is tilted furthest forward. When the lumbar support portion 30 is rotated forward from the storage position E1, the lumbar support portion 30 is placed in a state where it protrudes forward more than the backrest portion 12. This allows the protruding lumbar support portion 30 to support the user's lower back and coccyx from behind.

[0037] As shown in Figure 6, the rotation range of the lumbar support portion 30 includes a highest position E3 where the lumbar support portion 30 is at its highest position. At this highest position E3, the upper end of the lumbar support portion 30 is at its highest position. When the lumbar support portion 30 is at the highest position E3, it is possible for the lumbar support portion 30 to support the lumbar region of the user from behind. Furthermore, not only when the lumbar support portion 30 is at the highest position E3, but also when it is at a position intermediate between the highest position E3 and the foremost position E2, it is possible for the lumbar support portion 30 to support the lumbar region of the user from behind.

[0038] When the lumbar support portion 30 is at the highest position E3, the height H1 of the frontmost point K1 on the surface of the lumbar support portion 30 from the seat surface 11a of the seat portion 11 is in the range of 90 to 150 mm. More specifically, the height H1 is in the range of 100 to 130 mm.

[0039] Regarding the seat surface 11a of the seat portion 11, since the seat portion 11 of this embodiment has cushioning properties, when a user sits on the seat portion 11, the upper surface of the seat portion 11 sinks downward. Therefore, in this embodiment, the surface of the upper surface of the seat portion 11 that sinks downward and becomes horizontal is defined as the seat surface 11a. In Figure 6, the position of the seat surface 11a is indicated by a two-dot chain line (the same applies to Figure 7).

[0040] Next, a case where the lumbar support portion 30 is in the foremost position E2 will be described. As shown in Fig. 7, when the lumbar support portion 30 is in the foremost position E2, the lumbar support portion 30 can support the user's tailbone from behind. When the lumbar support portion 30 is in the foremost position E2, the height H2 of the foremost point K2 on the surface of the lumbar support portion 30 from the seat surface 11a of the seat portion 11 is in the range of 10 to 80 mm. More specifically, the height H2 is in the range of 30 to 60 mm.

[0041] Next, the shape of the waist support portion 30 will be described.

[0042] As shown in Figures 2, 6, 7, etc., the lumbar support portion 30 has a curved surface shape that convex forward when viewed from the side, regardless of the position within its rotatable range. In other words, the lumbar support portion 30 is formed so that the front surface has a curved surface shape that convex toward the user sitting on the seat portion 11 when viewed from the side, regardless of the position within its rotatable range. Specifically, the lumbar support portion 30 is formed so that the radius of curvature R of the curved surface is 50 to 300 mm within a range W that is 10 mm up and down from the most forward point T of the front surface, regardless of the position within its rotatable range (see Figure 8). More specifically, the lumbar support portion 30 is formed so that the radius of curvature R of the curved surface is 70 to 200 mm within a range W that is 10 mm up and down from the most forward point T of the front surface, regardless of the position within its rotatable range. FIG. 8 shows the case where the hip support portion 30 is at the foremost position E2.

[0043] 9, the waist support portion 30 is formed to a size that allows the entire portion to fit inside an imaginary circle C of diameter D when viewed from the side. In this case, the diameter D is set within a range of 150 to 300 mm, and more specifically, within a range of 180 to 230 mm.

[0044] According to the configuration of this embodiment described above in detail, the following excellent effects can be obtained.

[0045] The chair 10 is equipped with a lumbar support portion 30, which can support the user's lower back from behind. The lumbar support portion 30 is also rotatable so that its upper portion can tilt forward. This allows the lumbar support portion 30 to support the user's tailbone from behind by rotating the lumbar support portion 30 and tilting the upper portion of the lumbar support portion 30 forward.

[0046] Furthermore, the lumbar support portion 30 is formed so that its front surface has a curved shape that convex toward the user when viewed from the side, regardless of the position within its rotatable range. With this configuration, whether the lumbar support portion 30 is in a position supporting the user's lower back or in a position supporting the user's coccyx, the front surface of the lumbar support portion 30 has a curved shape that convex toward the user. Therefore, when the lumbar support portion 30 supports the lower back or the coccyx, it can support along the curved surface. This reduces the burden on the user when supporting the lower back and coccyx.

[0047] The rotation mechanism for rotating the hip support part 30 is configured with a shaft part 36a and a hip support frame 33 that extends above the shaft part 36a and is rotatable forward around the shaft part 36a. The hip support part 30 is provided integrally with the hip support frame 33. This allows the hip support part 30 to rotate so that the upper part falls forward.

[0048] The lumbar support portion 30 also has a plate-shaped cushion portion 45 and a cover material 43 that houses the cushion portion 45 and forms the surface of the lumbar support portion 30. The cushion portion 45 is curved so as to surround the lumbar support frame 33 from the front, above, and behind, and is housed in this curved state inside the cover material 43. In this case, since the cover material 43 is arranged along the curved shape of the cushion portion 45, it is possible to easily form the curved shape of the surface of the cover material 43, i.e., the surface of the lumbar support portion 30.

[0049] In order to prevent the lumbar support frame 33 from coming into direct contact with the user, it is preferable that the cushion portion 45 be provided in a ring shape so as to surround the entire lumbar support frame 33. On the other hand, in order to obtain favorable cushioning properties of the lumbar support portion 30, it is necessary to make the cushion portion 45 thick to a certain extent. However, if the thickness of the cushion portion 45 is made thick, it is thought that it will be difficult to provide the cushion portion 45 in a ring shape.

[0050] In view of this, in the above embodiment, the cushion portion 45 is formed with a plurality of cushion materials 41, 42 stacked in the thickness direction. Of the plurality of cushion materials 41, 42, the outer cushion material 41 has a length in the direction surrounding the lumbar support frame 33 that is longer than the inner cushion material 42. In this case, by reducing the thickness of the outer cushion material 41, it is possible to easily arrange the outer cushion material 41 in a circular shape. Therefore, in this case, it is possible to avoid direct contact with the lumbar support frame 33 while ensuring the cushioning properties of the lumbar support portion 30.

[0051] The thickness of the outer cushion material 41 is smaller than the thickness of the inner cushion material 42. This makes it easier to arrange the outer cushion material 41 in an annular shape.

[0052] Spacers 47, 48 are interposed between the lumbar support frame 33 and the cushion portion 45. In this case, by adjusting the positions of the spacers 47, 48 and the thickness of the spacers 47, 48, the curved shape of the cushion portion 45 can be adjusted, and thus the curved shape of the surface of the lumbar support portion 30 can be adjusted. This makes it possible to easily form the surface of the lumbar support portion 30 into a desired curved shape.

[0053] The spacers 47 and 48 are made of a material having cushioning properties, which allows the cushioning properties of the lumbar support portion 30 to be improved while still achieving the above-described effects of the spacers 47 and 48.

[0054] When the lumbar support portion 30 is positioned at the foremost position E2, the height H2 of the forward-most point K2 on the surface of the lumbar support portion 30 from the seat surface 11a of the seat portion 11 is within a range of 10 to 80 mm. In this case, by positioning the lumbar support portion 30 at the foremost position E2, the user's tailbone can be appropriately supported. In order to appropriately support the user's tailbone, it is more preferable that the height H2 be within a range of 30 to 60 mm.

[0055] When the lumbar support portion 30 is positioned at the highest position E3, the height H1 of the forward-most point K1 on the surface of the lumbar support portion 30 from the seat surface 11a of the seat portion 11 is within the range of 90 to 150 mm. In this case, by positioning the lumbar support portion at the highest position E3, the user's lumbar region can be suitably supported. In order to suitably support the user's lumbar region, it is more preferable that the height H1 be within the range of 100 to 130 mm.

[0056] Regardless of the position of the lumbar support 30 within its rotatable range, the radius of curvature R of the curved surface is set to 50 to 300 mm within a range W that is up to 10 mm above and below the forward-most point T on the front surface of the lumbar support 30. This further reduces the burden on the user's lower back and coccyx when supporting them. It is more preferable that the radius of curvature R is set to 70 to 200 mm.

[0057] The lumbar support portion 30 is formed to a size that allows the entire portion to fit inside an imaginary circle C of diameter D when viewed from the side, and the diameter D is set to 150 to 300 mm. In this case, when the lumbar support portion 30 is positioned at the foremost position E2, the lumbar support portion 30 can be prevented from protruding too far forward from the backrest portion 12. This prevents the user from shifting forward and becoming uncomfortable when the lumbar support portion 30 in the foremost position E2 supports the tailbone. Furthermore, to further prevent the user from becoming uncomfortable, it is preferable to set the diameter D of the imaginary circle C to 70 to 200 mm.

[0058] The present invention is not limited to the above-described embodiment, and may be implemented, for example, as follows.

[0059] (1) The dimensional relationship between the outer cushion material 41 and the inner cushion material 42 that constitute the cushion portion 45 does not necessarily have to be limited to that in the above embodiment. For example, the outer cushion material 41 and the inner cushion material 42 may have the same thickness or the same length in the frame surrounding direction. In this case, the outer cushion material 41 and the inner cushion material 42 may use the same cushion material.

[0060] Furthermore, the cushion portion 45 does not necessarily have to be formed by a plurality of cushion materials 41 and 42, but may be formed by a single cushion material.

[0061] (2) It is not necessary to use the first spacer 47 and the second spacer 48 as the spacer portion interposed between the lumbar support frame 33 and the cushion portion 45. The size, number, arrangement position, etc. of the interposed spacer portion may be determined appropriately according to the curved shape of the cushion portion 45.

[0062] (3) The spacers 47 and 48 do not necessarily have to be made of a material having cushioning properties. For example, the spacers 47 and 48 may be made of a hard resin, a metal material, or a wood material.

[0063] (4) In the above embodiment, the rotation mechanism for rotating the hip support portion 30 is configured to include the shaft portion 36a (corresponding to the rotation axis) and the hip support frame 33 (corresponding to the support frame), but the rotation mechanism for the hip support portion 30 is not necessarily limited to this configuration. For example, the rotation mechanism for the hip support portion 30 may be configured to include a link mechanism.

[0064] (5) In the above embodiment, the lumbar support portion 30 is provided in the opening 31 formed in the lower part of the backrest 12, but the method of providing the lumbar support portion 30 is not necessarily limited to this. For example, the lower end position of the backrest 12 may be set higher than in the above embodiment to form an opening area between the backrest 12 and the seat 11, and the lumbar support portion may be provided in that opening area. In this case, it is possible to make the left-right length of the lumbar support portion the same as the left-right length of the backrest 12 (and seat 11).

[0065] (6) In the above embodiment, the seat 11 and the backrest 12 have cushioning properties, but at least one of the seat 11 and the backrest 12 may not have cushioning properties. For example, if the seat 11 is made of a wood material and does not have cushioning properties, the upper surface of the seat 11 serves as the seating surface of the seat 11. [Explanation of symbols]

[0066] 10...chair, 11...seat portion, 12...backrest portion, 30...lumbar support portion, 33...lumbar support frame as support frame, 36a...axis portion as pivot axis, 41...outer cushion material, 42...inner cushion material, 45...cushion portion, 47...first spacer as spacer portion, 48...second spacer as spacer portion.

Claims

1. a seat on which a user sits; A seat chair comprising: a waist support portion that supports the waist of the user from behind; a rotation mechanism that allows the hip support portion to rotate so that an upper portion of the hip support portion falls forward; The lumbar support portion is formed so that the front surface has a curved shape that is convex toward the user when viewed from the side, regardless of the position within the rotatable range.

2. The rotation mechanism includes: A rotation axis; a support frame extending above the pivot shaft and pivotable forward about the pivot shaft; the lumbar support portion is provided integrally with the support frame, and includes a plate-shaped cushion portion and a cover material that houses the cushion portion and forms a surface of the lumbar support portion, 2. The chair according to claim 1, wherein the cushion portion is accommodated inside the cover material in a curved state so as to surround the support frame from the front, above, and behind.

3. The cushion portion is formed by a plurality of cushion materials stacked in a thickness direction, 3. The legless chair according to claim 2, wherein the outer cushioning material of the plurality of cushioning materials is longer in the surrounding direction than the inner cushioning material.

4. The chair according to claim 2 or 3, further comprising a spacer portion interposed between the support frame and the cushion portion.

5. The rotatable range of the hip support portion includes a frontmost position where an upper portion of the hip support portion is tilted furthest forward, A chair as described in any one of claims 1 to 3, wherein when the lumbar support portion is located in the forward-most position, the forward-most point on the surface of the lumbar support portion has a height dimension from the seat surface of the seat portion within the range of 10 to 80 mm.

6. The rotatable range of the hip support portion includes a highest position where the hip support portion has a highest height position, The chair of claim 5, wherein when the lumbar support portion is positioned at the highest position, the forward-most point on the surface of the lumbar support portion has a height dimension from the seat surface of the seat portion within the range of 90 to 150 mm.

7. A chair as described in any one of claims 1 to 3, wherein, regardless of the position of the lumbar support portion within the rotatable range, the radius of curvature of the curved shape is 50 to 300 mm within a range of 10 mm vertically from the most forward point on the front surface of the lumbar support portion.

Images