Swivel chair

Abstract

This invention aims to create a novel and useful chair, even in a swivel chair with an adjustable seat height, that can cradle the sitter's body and features upholstery shaped to prevent fatigue even when the sitter leans back and sits for extended periods. [Solution] A swivel chair in which a seat 1 is positioned on the upper part of legs 4 so as to be able to move up and down, wherein a backrest 2 is positioned at the rear of the seat 1, and the backrest 2 has an upholstery material 22 that is supported by a back frame 201 which constitutes a back support 21 and receives the weight of the person sitting, and the upholstery material 22 has a back support area S that is recessed at the rear, and the back support area S is configured to have a concave shape with back support surfaces A1 to A4 that face each other on the left and right and up and down.

Description

Technical Field

[0001] The present invention relates to a swivel chair that is preferably used in offices and the like and whose backrest is configured using tension members.

Background Art

[0002] As a swivel chair whose backrest is mainly configured using tension members, for example, the one shown in Patent Document 1 is known.

[0003] This chair is configured by attaching the left and right edges and the upper and lower edges of a film panel to a back frame composed of left and right side frames and upper and lower horizontal frames. The curved surface of the film panel is formed by the curved shapes of the left and right vertical frames and the curved shapes of the upper and lower horizontal frames.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the back support area formed by the above - mentioned film panel has a shape that is concave backward from the left and right back frames in terms of the flat cross - section, while in terms of the longitudinal cross - section, it has a shape that bulges forward from the upper and lower back frames.

[0006] That is, the left and right side frames support the seated person's body so as to wrap it from the left and right, while in the vertical direction, they have a curved shape that bulges forward along the seated person's spine. When the seated person is working, they do not rely on the backrest or receive support near the waist, and when the seated person arches their body, the entire back is supported.

[0007] However, in recent years, the amount of time spent sitting in front of a PC or monitor screen has increased significantly, especially with chairs designed for teleworking or gaming. In such situations, a posture where the body is slightly reclined against the backrest may be more suitable than sitting upright with a straight back, and in fact, the number of users adopting this posture is increasing.

[0008] When using the chair in this posture, the chair described in Patent Document 1 requires the user to lean back against the backrest, which is convex forward in the vertical direction, in order for the back to make contact with the backrest. At the point where the shoulders are in contact with the backrest, the back of the head comes into contact with the backrest, which is facing forward and upward, causing the head to tilt and the user's gaze to be directed towards the ceiling. Therefore, when looking forward, the user must maintain an upright head position while leaning against the backrest, which is a problem as it results in a posture unsuitable for tasks such as staring at a screen in front of you for extended periods.

[0009] In the left-right direction, it has a concave surface that faces forward, so it is shaped to gently conform to the sitter's body. However, since it is simply made by joining three membrane panels together, the adjacent membrane panels at the joints only form a continuous, gently curved surface, and therefore it does not provide a sense of support that sandwiches the sitter's body from both sides.

[0010] In particular, in chairs where the backrest does not have a backing material such as a urethane cushion, and the weight of the sitter is supported by the upholstery and then supported by the back frame, in order to give the upholstery the required shape, some ingenuity is required to make this possible.

[0011] This invention addresses these issues and aims to realize a novel and useful swivel chair that allows the sitter to sit at an appropriate height and easily change direction, and has upholstery that can envelop the sitter's body and prevents fatigue even when the sitter sits for a long time with their body leaning against the backrest. [Means for solving the problem]

[0012] To achieve this objective, the present invention employs the following means.

[0013] In other words, the swivel chair of the present invention is The seat is positioned on top of the legs so that it can be raised and lowered. A backrest is placed at the rear of the seat. The backrest has upholstery that is supported by the back frame that constitutes the back support and bears the weight of the seated person. The upholstery has a recessed back support area at the rear. The back support area has a concave shape with back support surfaces facing each other on the left and right and top and bottom. It is characterized by the following:

[0014] In this way, even if the back support surface is mainly constructed of tension material that bears the weight, the opposing back support surfaces on the left and right and above and below support the sitter's back, while the concave shape that is recessed at the rear envelops the sitter's body. Therefore, compared to shapes where the middle bulges forward along the vertical direction, this improves stability when supporting the back in the vertical and horizontal directions when leaning against the backrest.

[0015] To properly realize the concave shape of the back support surface, it is preferable that the back support surface be a surface facing multiple different directions, and that valley lines are formed to separate the boundaries between adjacent back support surfaces.

[0016] To improve the lateral fit for the seated person, it is preferable that the left and right opposing back support surfaces have a central support surface in between, and that the central support surface has a first valley line that separates it from the left and right support surfaces.

[0017] In order to properly support the lower back of a seated person, it is preferable that the boundary between the lower back support surface and the left and right back support surfaces has a second valley line that is continuous with the first valley line and opens diagonally downward and outward, and that the lower back support surface has a support function that faces diagonally forward and upward between the left and right second valley lines.

[0018] In order to appropriately support the upper back of the seated person, it is preferable that at the boundary between the back upper support surface portion and the left and right back support surface portions, there is a third valley line that is continuous with the first valley line and opens obliquely upward and outward, and the back upper support surface portion located between the left and right third valley lines has an upward support function.

[0019] In order to appropriately realize the multi-faceted surface of the tension member, it is preferable that on the back side along the valley line, there is a tension member drawing-in portion that pulls the tension member backward.

[0020] In order to simplify the configuration of the tension member itself, it is preferable that the tension member is a single continuous piece, and the tension member drawing-in portion is connected to this tension member.

[0021] In order to eliminate the need to configure the tension member drawing-in portion with a separate member, it is preferable that the tension member drawing-in portion is a surplus portion formed by extending the tension member.

[0022] As a specific example, it is preferable that the tension member is partially bent and joined.

[0023] In order to simplify the configuration of the tension member and the tension member drawing-in portion, it is preferable that the tension member is a single continuous piece including the tension member drawing-in portion.

[0024] In order to appropriately attach the tension member to the back frame via the tension member drawing-in portion, it is preferable that the back support has a front back frame and a rear drawing-in receiving portion, and the peripheral edge portion of the tension member is supported by the back frame, and one end portion of the tension member drawing-in portion is supported by the drawing-in receiving portion.

[0025] In order to make the tension member into a three-dimensional shape by drawing-in, it is preferable that the back support has a front upper and lower back frame connected at a rear intermediate portion, and the end portions of the tension member are attached to the upper and lower back frames and the intermediate portion.

[0026] In order to easily and appropriately attach the tension member to the intermediate portion via the tension member drawing-in, it is preferable that with one end portion of the tension member drawing-in portion attached to the tension member and the other end portion attached to the drawing-in receiving portion, the drawing-in receiving portion can be attached to the intermediate portion.

[0027] To facilitate assembly and disassembly, it is preferable that the tensioning material, tensioning material retraction section, and tensioning material retraction receiving section be detachable from the back frame as a single unit.

[0028] Regarding swivel chairs relating to other configurations of the present invention, The seat is positioned on top of the legs so that it can be raised and lowered. The seat has upholstery that is supported by a seat frame that constitutes the seat support and bears the weight of the person sitting on it. The upholstery has a recessed seating support area at the bottom. The seat support area has a concave shape with seat support surfaces facing each other on the left and right and front and back. The seat support surface is a surface that faces multiple different directions. A characteristic feature is that a valley line is formed in the adjacent seat support surface to separate the boundaries.

[0029] In this case, it is preferable that the back side of the valley line has a tension material pull-in section that pulls the tension material downward.

[0030] The present invention is particularly suitable for use in chairs in which the backrest and seat are supported so as to be able to swing back and forth and side to side. [Effects of the Invention]

[0031] Because of the configuration described above, the present invention makes it possible to provide a novel and useful swivel chair that, even if it is a swivel chair, can envelop the body of the sitter and has a shape of upholstery that prevents fatigue even when the sitter sits for a long time with their body leaning back. [Brief explanation of the drawing]

[0032] [Figure 1] A front view of a chair according to one embodiment of the present invention, with the upholstery of the backrest removed. [Figure 2] The same perspective view. [Figure 3] Side view of the same. [Figure 4] The same floor plan. [Figure 5]The same partially exploded view. [Figure 6] An explanatory diagram of the rocking mechanism that makes up the chair. [Figure 7] A diagram illustrating the frame structure of the chair. [Figure 8] A front view showing a chair according to one embodiment of the present invention, with the backrest upholstery attached. [Figure 9] The same perspective view. [Figure 10] Side view of the same. [Figure 11] The same floor plan. [Figure 12] Rear view of the same object. [Figure 13] A diagram illustrating the support surface formed in the backrest of the chair. [Figure 14] Central longitudinal section view in Figure 1. [Figure 15] A diagram showing the procedure for installing the upholstery. [Figure 16] Plan section views corresponding to the three locations in Figure 14. [Figure 17] A diagram showing the seat swaying from side to side. [Figure 18] A diagram showing the seat rocking back and forth. [Figure 19] A diagram showing the seat tilting further backward. [Figure 20] A diagram showing an example of the chair's use. [Figure 21] A diagram illustrating the support function provided by the upholstery material of the chair. [Figure 22] A diagram illustrating the support function provided by the upholstery material of the chair. [Figure 23] A diagram illustrating the support function provided by the upholstery material of the chair. [Figure 24] A figure showing a modified example of the present invention. [Figure 25] A figure illustrating another modification of the present invention. [Figure 26] A figure illustrating yet another modification of the present invention. [Modes for carrying out the invention]

[0033] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0034] Figures 1 to 5 show the chair according to this embodiment with the upholstery material 22 of the backrest 2 removed, Figure 6 is an explanatory diagram of the rocking mechanism that constitutes the chair, and Figure 7 is an explanatory diagram of the frame structure of the chair. Figures 8 to 13 show the chair with the upholstery material 22 of the backrest 2 attached.

[0035] This chair has a backrest 2 positioned at the rear of the seat 1, and the seat 1 is pivotably attached to the legs 4 via a pivoting mechanism 3.

[0036] In this embodiment, when referring to the front-to-back direction, left-to-right direction, and up-and-down direction, the seated person in the chair is used as the reference point.

[0037] The seat 1 consists of a seat support (outer shell) 11, an inner shell 12, and a seat body 13, which is placed on top of the inner shell 12 and is covered with cushioning material and upholstery.

[0038] The legs 4 have casters 42 at the lower end of the leg wings 41, and a leg support column 43 is erected from the center of the leg wings 41. A swing mechanism 3 is attached to a support base 44 provided on the upper end of the leg support column 43. The leg support column 43 is extendable and retractable vertically by a gas spring mechanism (not shown) built inside, and the seat 4 is rotatable around the axis of the leg support column 43. Thus, this chair is configured as a swivel chair with the seat 1 positioned on top of the legs 4 so as to be able to move up and down.

[0039] As shown in Figure 6, the rocking mechanism 3 has an upper base portion 31 and a lower base portion 32 facing each other, the lower base portion 32 is attached to the support base portion 44 of the leg 4, and the seat 1 is attached to the upper base portion 31 via the seat support 11, with a cushioning material 33 interposed between the upper base portion 31 and the lower base portion 32.

[0040] The rocking mechanism 3 allows the upper base portion 31 to tilt relative to the lower base portion 32 in any direction, including the front-to-back and left-to-right directions, up to 360°.

[0041] An example of the rocking mechanism 3 is the configuration shown in Japanese Patent Application Publication No. 2023-053700. In this configuration, the lower base portion 32 is made of a flat surface, and the upper base portion 31 is smoothly curved in a convex shape toward the lower base portion 32. At the reference position, the center of gravity of the upper base portion 31 is located on the center m of the lower base portion 32, at the lowest position. From this reference position, as the mechanism tilts, the center of gravity of the upper base portion 31 rises, and it rolls radially on the lower base portion 32, taking a forward-tilting position in the direction of rolling, and has the function of returning to the reference position from the destination of rolling using gravity. At that time, the upper base portion 32 compresses the cushioning material 33 around the position closest to the lower base portion, and the compression position moves with the rolling motion.

[0042] The rocking mechanism 3 is equipped with a damper mechanism 34 at the position connecting the upper base portion 31 and the lower base portion 32, which can operate in accordance with movement in a 360° direction.

[0043] The damper mechanism 34 is composed of a hole 34a provided in either the upper base portion 31 or the lower base portion 32, a cylindrical member 34b provided in the other and inserted into the hole 34a, and a friction material 34c positioned between the hole 34a and the cylindrical member 34b.

[0044] Furthermore, the rocking mechanism 3 includes a retaining member 35 positioned at the connection point between the upper base portion 31 and the lower base portion 32. This member allows the upper base portion 31 to tilt relative to the lower base portion 32 while restricting its separation from the lower base portion 32.

[0045] The damper mechanism 34 also serves as a rotation stopper, restricting the relative rotational movement of the upper base portion 31 and the lower base portion 32.

[0046] The backrest 2 is supported by a back support rod 5. As shown in Figures 1 to 5, the back support rod 5 is a plate-shaped object with its base end 5a connected to the rear part 11a of the seat support 11, and its upper end 5b side curved upward and rearward, becoming narrower towards the top. A disc-shaped mounting part 51 protrudes forward from the upper end 5b, and a disc-shaped elastic part 52 is attached to this mounting part 51.

[0047] The backrest 2 is constructed by stretching a tensioning material 22 over the back support 21. The back support 21 comprises a roughly frame-shaped back frame 201 and a retraction receiving portion 202. The back frame 201 is composed of an annular upper back frame 211 that forms an opening OP1, an annular lower back frame 212 that forms an opening OP2, and an intermediate portion 213 that connects the upper back frame 211 and the lower back frame 212.

[0048] The upper back frame 211 is composed of left and right front protrusions 211a and 211b that extend vertically while curving to be convex both forward and outward, an upper edge portion 211c that extends horizontally while curving to be convex rearward and upward, and is located in a position continuous with the upper front protrusions 211a and 211b, and is located in a position continuous with the lower front protrusions 211a and 211b, and is located horizontally while curving to be convex rearward and downward.

[0049] The lower back frame 212 is composed of forward projections 212a and 212b that extend vertically while curving to be convex both forward and outward, a lower edge portion 212c that extends horizontally while curving to be convex rearward and downward, and is located below the forward projections 212a and 212b, and is located in a position continuous with the front projections 212a and 212b, and is located above the forward projections 212a and 212b, and is located to be partway across the left and right while curving to be convex rearward and upward.

[0050] The intermediate section 213 is located behind the upper back frame 211 and the lower back frame 212, and has a curved plate shape with a central section that bulges towards the rear and the central section that concaves towards the front. The upper end of the intermediate section 213 and the lower edge 211d of the upper back frame 211 are integrally continuous, and the lower end of the intermediate section 213 and the upper edge 212d of the lower back frame 212 are integrally continuous. Below the intermediate section 213, a disc-shaped mounting portion 213b is provided, protruding downward and towards the rear, and this mounting portion 213b is connected to a disc-shaped elastic portion 52 provided on the upper end 5b of the back support rod 5 described above. The back frame 201 may be constructed by integrally molding the upper back frame 211, the lower back frame 212, and the intermediate section 213, but each may also be molded separately and joined together with screws or the like.

[0051] Although not shown in the figure, the elastic part 52 consists of a roughly disc-shaped front base and a rear base that are in contact with each other in the front-rear direction via an elastic material. The backrest 2 is configured to tilt in any direction around the center due to the oscillating motion of the elastic body 52 relative to the back support rod 5. The specific structure can be the same as the oscillating mechanism 3 of the seat described above, or a simpler configuration that omits the damper mechanism 34, etc.

[0052] When the entire back frame 201, configured in this way, is viewed from the front, as shown in Figure 7(a), the width W1 of the upper back frame 211 and the width W2 of the lower back frame 212 are the same or approximately the same, and the width W3 of the constricted portion of the intermediate section 213 is set to be about 2 / 3 to 3 / 4 of the above widths, so that the entire outer edge forms a gourd shape. The upper front projection 211a and the lower front projection 212a, which form an upper and lower pair on the left side, and the upper front projection 211b and the lower front projection 212b, which form an upper and lower pair on the right side, are positioned in a roughly vertically opposing position with a gap in between, as indicated by arrows T1 and T2, when viewed from the front.

[0053] When the entire back frame 201 is viewed from the side, as shown in Figure 7(b), the protruding ends of the upper forward protrusions 211a and 211b are designated as the first inflection point R1, the recessed end of the rearward-located intermediate portion 213 is designated as the second inflection point R2, and the protruding ends of the lower forward protrusions 212a and 212b are designated as the third inflection point R3. The section between the first inflection point R1 and the third inflection point R3 is recessed to the rear, and the portion above the first inflection point R1 and the portion below the third inflection point R3 are curved backward, resulting in a smooth, continuous shape throughout. On the left side, the upper front projection 211a and the lower front projection 212a, which form an upper and lower pair, and on the right side, the upper front projection 211b and the lower front projection 212b, which form an upper and lower pair, are positioned in a roughly vertically opposing position with a gap in between, as indicated by arrows T1 and T2, whether viewed from the front or the side.

[0054] When the entire back frame 201 is viewed from above, as shown in Figure 4, the direction in which the pair of left and right forward protrusions 211a and 211b located at the top open outwards roughly corresponds to the direction in which the pair of left and right forward protrusions 212a and 212b located at the bottom open outwards.

[0055] As shown in Figure 5, grooves g1, g3, and g2 that open to the rear are continuously formed in a circumferential manner in the region along the outer peripheral edge on the back of the upper back frame 211, the region along the left and right side edges on the back of the intermediate portion 213, and the region along the outer peripheral edge on the back of the lower back frame 212. These grooves g1 to g3 to g2 are for inserting and engaging the insertion parts k1, k3, and k2 provided on their peripheral edges when the tension material 22, shown as dashed lines in Figure 12, is placed over the back frame 201 from the front side and the periphery is folded back to the back side of the back frame 201.

[0056] As shown in Figures 12 and 13, the tensioning material 22 is constructed as a single piece including an upper back support surface A4 positioned in front of the upper back frame 211, a lower back support surface A3 positioned in front of the lower back frame 212, a central back support surface A0 and left and right back support surfaces A1 and A2 positioned in front of the intermediate section 213 in the upper and lower center, and a folded portion A5 and an extended portion A6 positioned in the area that folds back from the side edges of the left and right back support surfaces A3 and A4 and extends to the intermediate section 23. The tensioning material 22 is flexible enough to be unfolded into a planar shape in this manner.

[0057] Mounting margins 221 and 222 are provided around the upper back support surface A4 and the lower back support surface A3, which fold back to the back along the contour of the back frame 201, and a mounting margin 223 is provided around the extension A5 along the contour of the intermediate portion 23, and the aforementioned insertion portions k1, k2, and k3 are formed in a strip shape over the required width on the periphery of these mounting margins 221, 222, and 223.

[0058] In this embodiment, the backrest 2 does not use cushioning material such as urethane foam, but is configured so that the upholstery 22 receives the weight of the seated person and transmits it to the back frame 201 for support. Figures 8 to 12 show the state in which the upholstery 22 is attached to the back frame 201, with the upholstery 22 represented by a semi-transparent mesh. Areas with a higher density of mesh are areas where the upholstery 22 or the upholstery retraction section 23 (described later) overlap, and the light transmittance is reduced. In contrast, Figure 13 shows the upholstery 22 as an opaque surface to explain its surface configuration.

[0059] As shown in the partial extract in Figure 9, the material of the tensioning material 22 consists of a mesh 22a formed from a resin material such as polyester, with elastic threads 22b extending laterally sewn in at appropriate positions. The elastic threads 22b consist of filaments thicker than the mesh material of the mesh 22a, and are made of an appropriate resin material such as elastomer, and are configured to have more limited stretchability and strength than the mesh 22a.

[0060] Then, using this tensioning material 22, as shown in Figures 14 and 16, a back support region S consisting of multiple back support surfaces A0 to A4 is formed at a position recessed behind the back frame 201, specifically, at a position recessed behind the reference surface X0 when using a virtual surface X0 that simultaneously contacts the front protrusions 211a, 211b, 212a, and 212b located in front of the back frame 201 as a reference, as roughly indicated by the dashed line in Figure 13.

[0061] The back support surfaces A0 to A4 are formed to face multiple different directions. "Different directions" means that, when these surfaces are approximated as planes, the normal directions of each surface point in different directions. To achieve this configuration, valley lines B11 to B32 are formed at the points where adjacent surfaces intersect, separating the boundaries.

[0062] To explain in more detail, the left and right back support surfaces A1 and A2, which are spaced apart in the left-right direction, face each other on the left and right with the central back support surface A0, which is located midway in the left-right direction, in between. The lower back support surface A3 and upper back support surface A4, which are spaced apart in the up and down direction, face each other on the up and down with the central back support surface A0, which is located midway in the up and down direction, in between. In other words, the back support region S is configured to appear concave when viewed from all four sides.

[0063] To this end, as shown in Figures 8 and 13, first valley lines B11 and B12 are formed at the boundary between the central back support surface A0 and the left and right back support surfaces A1 and A2, extending parallel to each other in the vertical direction. As shown in Figures 11, 16 and 21(b), the left and right back support surfaces A1 and A2 are inclined surfaces that are connected in a direction that faces inward from the surface that extends the central back support surface A0 in the left and right direction.

[0064] Furthermore, as shown in Figures 8 and 13, second valley lines B21 and B22 are formed at the boundary between the lower back support surface A3 and the left and right back support surfaces A1 and A2, extending diagonally forward and downward and outward from the lower ends of the first valley lines B11 and B12. The lower back support surface A3, located between the left and right second valley lines B21 and B22, is an inclined surface that extends diagonally upward relative to the central back support surface A0, as shown in Figures 10, 14 and 21(a).

[0065] Furthermore, as shown in Figures 8 and 13, etc., third valley lines B31 and B32 are formed at the boundary between the upper back support surface A4 and the left and right back support surfaces A1 and A2, extending diagonally forward and upward and outward from the upper ends of the first valley lines B11 and B12. The upper back support surface A4, located between the left and right third valley lines B31 and B32, is an inclined surface that extends diagonally downward relative to the central back support surface A0, as shown in Figures 10, 14 and 21(a).

[0066] The lengths of the first valley lines B11, B12, the second valley lines B21, B22, and the third valley lines B31, B32, as well as the angles between the second valley line B21 (B22) and the first valley line B11 (B12), and the angles between the third valley line B31 (B32) and the first valley line B11 (B12), are set appropriately according to the purpose, use, and required characteristics of the chair. In this case, the second valley line B21 (B22) and the first valley line B11 (B12) may be smoothly continuous, and the third valley line B31 (B32) and the first valley line B11 (B12) may be smoothly continuous.

[0067] As shown in Figure 22(a), the back of a seated person U gradually narrows along the shoulder blades and sternum, then widens towards the buttocks after passing through the waist. Therefore, the second valley lines B21 and B22 are set based on lines that extend diagonally downward and sideways along the waist (lumbar region) U2, which widens from the waist to the buttocks, and the third valley lines B31 and B32 are set based on lines that extend diagonally upward and sideways along the upper back (upper region) U3, which forms an inverted triangle from the lower edges of the left and right shoulder blades to the shoulders. The first valley line B11 (B12) is set at the position connecting the second valley line B21 (B22) and the third valley line B31 (B32).

[0068] Furthermore, in order to clearly form the first valley lines B11, B12, the second valley lines B21, B22, and the third valley lines B31, B32, and to stably maintain their valley shapes, tension material pull-in sections 23 are provided on the back side of each valley line, as shown in Figure 13, etc., to pull the tension material 22 backward.

[0069] The tension material retraction section 23 is composed of a left-side tension material retraction member 231 that constitutes the first retraction area C11, second retraction area C21, and third retraction area C31 along the first valley line B11, second valley line B21, and third valley line B31, and a right-side tension material retraction member 232 that constitutes the first retraction area C12, second retraction area C22, and third retraction area C32 along the first valley line B12, second valley line B22, and third valley line B32. Here, the tension material retraction members 231 and 232 are made of the same material as or of the same type as the tension material 22, but are not limited to such materials. In addition, here, the edges of the tension material retraction members 231 and 232 are folded and sewn to prevent fraying. Of course, as shown in the modified examples below, the tension material retraction section 23 can be configured in other ways.

[0070] Here, as shown in Figures 13 and 14, the first retraction regions C11 and C12 have a rectangular shape with approximately equal width, while the second retraction regions C21 and C22 and the third retraction regions C31 and C32 have a triangular shape that narrows from the base to the tip.

[0071] In order to accurately achieve the positions of each valley line B11 to B32 with respect to the back frame 201, the tension material pull-in section 23, as shown in Figures 15(a) and (c), has a sewing line 23a set at the end where the edge treatment is applied on one end, sewn to the tension material 22, and a pull-in line 23b set at the end where the edge treatment is applied on the other end, attached to the resin tension material receiving section 202. For the end treatment of the tension material pull-in members 231 and 232, as shown in Figure 15(d), the ends of the tension material pull-in members 231 and 232 are folded inward and sewn with first threads 231x and 232x, and then applied to the position that will become the valley line of the tension material 22 and sewn to the tension material 22 with second threads 231y and 232y. The ends of the tension material pull-in members 231 and 232 are folded inward, so that the folded ends of the tension material pull-in members 231 and 232 and the first threads 231x and 232x are not visible from the side indicated by the arrow in the figure.

[0072] The retraction receiving section 202 serves as a joint for easily attaching the tension material retraction section 23 to the intermediate section 213 that constitutes the back frame 201. It is plate-shaped, and recessed grooves 202a (see Figure 15(c)) are formed on both edges in the width direction toward the back side, into which the retraction lines 23b of the aforementioned tension material retraction members 231 and 232 can be fitted and attached. This retraction receiving section 202 can be attached with a single touch to the mounting section 213a (see Figures 15(a) and (c)) provided on the front surface of the intermediate section 213 that constitutes the back frame 201 via an engagement part (not shown), and a predetermined retraction state can be reliably achieved throughout the tension material 22 via the tension material retraction section 23.

[0073] Figures 14 and 16 show the tension member 22 before retraction with a dashed line (P) and the tension member 24 after retraction with a solid line (Q). By retracting the tension member 22, each of the back support surfaces A0 to A4 shown in Figures 13, 14, and 16(b) is formed in a position recessed from the back frame 201. The position of the tension member 2(P) before retraction basically coincides with the dashed line X0 mentioned above.

[0074] As shown in Figures 12, 15, and 16, the upper corresponding position 221 of the tensioning material 22, which is positioned to cover the opening OP1 of the upper back frame 211, is attached by inserting the insertion part k1 into the groove g1 at a position where it is wrapped around the front protrusions 211a, 211b and the back edge 212 of the upper back frame 211. The lower corresponding position 222 of the tensioning material 22, which is positioned to cover the opening OP2 of the lower frame 212, is attached by inserting the insertion part k2 into the groove g2 at a position where it is wrapped around the front protrusions 221a, 221b and the back edge 211 of the back frame 22.

[0075] On the other hand, the intermediate corresponding position 223 of the tensioning material 2, which is located between the upper back frame 211 and the lower back frame 212 and corresponds to the intermediate section 213, is, as shown in Figure 16(b), not surrounded by frames on either side, with only the intermediate section 213 located behind it at a distance. For this reason, the intermediate corresponding position 223 is provided with an intermediate position widening section 224, which is folded back in a U-shape and then extends backward, and the insertion section k3 at the end of this extension is inserted into the groove g3 on the back of the intermediate section 213 to attach it. In other words, both sides of the intermediate corresponding position 223, including the intermediate position widening portion 224, are folded back along the arrows T1 and T2 shown in Figures 7(a) and (b), as shown in Figures 1 to 4, Figures 8 to 11, etc., in a shape that follows the shape of the flat cross-section of the upper and lower forward protruding edges 211a-212a (211b-212b). This forms a series of folded portions A5 that are connected vertically in a partially bag-like shape without an internal frame, and an extension portion A6 is stretched from this folded portion A5 toward the intermediate portion 213 of the back frame 20.

[0076] As mentioned above, the tensioning material 22 is flexible and can be unfolded into a flat shape, and the folded portion A5 is not formed by resin molding or the like.

[0077] Even though the tensioning material 22 is flexible, as mentioned above, the direction in which the pair of left and right forward protrusions 211a and 211b located at the top open outwards is roughly corresponding to the direction in which the pair of left and right forward protrusions 212a and 212b located at the bottom open outwards. As a result, the folded portion A5 extending vertically is taut with as little twisting as possible.

[0078] The folded portion A5, combined with the support it receives from the extended portion A6 to prevent sagging, forms a three-dimensional support surface in the space on both sides of the frame width W3 shown in Figure 7 when viewed from the front, due to tension, even without immediate backing from the frame. It then appropriately supports the sitter's body while flexibly deforming in response to the load applied by the sitter.

[0079] The extension A6 is formed in such a way that, when viewed from the side in Figure 10, it substantially covers the spatial region (more precisely, the spatial region slightly inside that region) enclosed by the frame line including the inflection points R1, R2, and R3 shown in Figure 7(b). It is preferable that the extension A6 is stretched in a substantially planar shape within this region, but it may also be stretched in a curved planar shape.

[0080] One procedure for installing the tensioning material 2 is to first attach the pull-in receiving portion 202, which is integrated with the tensioning material 22, to the base portion 213a provided in the middle portion 213 of the back frame 201, as shown in Figure 15(a), and then insert the insertion portions k1, k2, and k3 provided on the periphery of the tensioning material 22 into the grooves g1, g2, and g3 of the back frame 201, as shown in Figures 15(b) and 16(a) to (c). Of course, it is also possible to first insert the insertion portions k1, k2, and k3 provided on the periphery of the tensioning material 22 into the grooves g1, g2, and g3 of the back frame 201, as shown in Figures 15(b) and 16(a) to (c), and then attach the pull-in receiving portion 202 to the base portion 213a provided in the middle portion 213 of the back frame 201, as shown in Figure 15(a). In this case, as shown in Figure 12, the issue can be addressed by inserting fingers through openings OP1 and OP2 from the back side of the back frame 201 and attaching the retraction receiving portion 202 to the base portion 213a of the intermediate portion 213 of the back frame 201.

[0081] This chair has a rocking mechanism 3 located between the seat 1 and the legs 4, which allows the seat 1 to rock in any direction of 360°, including forward, backward, left, and right, as shown in Figures 17 and 18. Furthermore, an elastic part 52 located between the back support rod 5 and the back frame 201 allows the backrest 2 to rock relative to the seat 1, around the center of the elastic part 52, as shown in Figure 19. Therefore, when a seated person U leans back against the backrest 2 and shifts their center of gravity backward, the seat 1 tilts backward while lifting the center of gravity, causing the backrest 2 to tilt backward as well (for example, at an angle θ1), and then the backrest 2 tilts further backward (for example, at an angle θ2), as shown in Figure 19. Of course, depending on how it is used, the tilts of θ1 and θ2 may occur in reverse or simultaneously.

[0082] Conversely, this chair is also capable of moving the backrest 2 forward from the reference position together with the seat 1, as shown in Figure 18, by the rocking mechanism 3 (for example, by an angle of -θ).

[0083] Figure 20 shows an example of how this chair can be used. First, this chair uses upholstery material 22 to form a three-dimensional back support area S that is recessed backward in the backrest 2. As a result, a user (sitter) U can sit down and place their body in the back support area S formed in the recess. From this position, by leaning their weight against the backrest 2, the backrest 2 tilts backward due to the rocking of the seat 1 or the behavior of the elastic part 3, allowing the user to sit in front of a wall-mounted large monitor MT or the like and operate a keyboard or other control unit AC that is within reach.

[0084] In this configuration, the chair provides a comfortable fit to the sitter U from all sides by positioning the sitter U's body between the vertically opposing upper and lower back support surfaces A3 and A4 as shown in Figure 21(a), and between the horizontally opposing left and right back support surfaces A1 and A2 as shown in Figures 21(b) and (c).

[0085] Furthermore, when this chair is used with the backrest 2 reclined, as shown in Figure 21(a), the upper back support surface A4 is inclined in the upright direction relative to the central back support surface A0. As a result, the area U3 from the scapula to the shoulder of the seated person U makes contact with the chair further forward than the extension of the central back support surface A0. Therefore, the upper body of the seated person U is raised, and they can comfortably assume a posture where their gaze E is directed horizontally or slightly upward without consciously raising their head U1 while leaning against the backrest 2.

[0086] When the seated person U leans backward from the position shown in Figure 21, the pelvis tilts backward and the body opens up, as indicated by the arrows at both ends. Since the upper body does not follow the movement of the pelvis, although the load is distributed, it opens locally and the load of the upper body tends to be placed as a load on the joint around the fifth lumbar vertebra U5 shown in Figure 21(a2), just above the pelvis. Conventional chairs with lumbar support LS support the fifth lumbar vertebra U5 of the S-shaped spine forward, so the load on the backrest 2 is distributed, but it does not support the load upward.

[0087] In contrast, in this embodiment, the chair allows the sitter U to align the second valley lines B21 and B22 with the area that widens from the waist to the buttocks, making it easier for the lower back to fit against the back support surface A3 as shown in Figure 21(a). When the backrest 2 is tilted backward, as shown in Figure 22(c), the back support surface A3 located between the left and right first valley lines B21 and B22 pushes upward with a resistance force F1 around the so-called thoracolumbar transition area U6. This prevents the load from concentrating around the fifth lumbar vertebra U5 of the sitter U, distributes the weight (resistance force from the seat surface) F0 on the seat 1, and has the effect of reducing the feeling of pressure and fatigue experienced by the sitter U from the seat 1.

[0088] Generally, the upper body of a seated person moves relative to their lower body with the thoracolumbar junction U6 as the pivot point. The thoracolumbar junction U6 is a common area for everyone, and since it is a gently sloping area above the fifth cervical vertebra U5, it can be appropriately supported by the upward-facing lower back support surface A3, even if there are differences in the seated person's physique, compared to when the fifth cervical vertebra U5 is supported at a single point with conventional lumbar support.

[0089] Furthermore, as shown in Figure 22(b), when the user is seated, the area U3 from the left and right scapulae to the shoulders, which forms an inverted triangle shape, is positioned opposite the upper back support surface A4 of the backrest 2. Therefore, if the area U3 from below the scapulae to the shoulders, as shown in Figure 22(a), leans against the upper back support surface A4 along the third valley lines B31 and B32 shown in Figure 13, the area U3ga from the scapulae to the shoulders is pushed upward diagonally by the upper back support surface A4 with a counterforce F2. This also prevents the load from concentrating around the fifth lumbar vertebra U5 of the seated person U, and distributes the load on the seat 1 (counterforce from the seat surface) F0, thereby reducing the feeling of pressure and sitting fatigue experienced by the seated person U.

[0090] In addition, at the intermediate corresponding position 223 of the upholstery material 2, a frameless folded portion A5 is formed on both the left and right edges, along with the intermediate position widening portion 224, connecting the upper and lower protruding portions. Therefore, even if the seated person U leans to the side with their elbow U7 on it as shown in Figure 23(a), or leans against the backrest 2 with their arm U8 behind them as shown in Figure 23(b), or crosses their arms U9 in front of them as shown in Figure 23(c), and their elbow U7 or arm U8 comes into contact with the folded portion A5, the upholstery material 22 of the folded portion A5 elastically flexes and deforms to conform to the seated person U's posture, while appropriately supporting the seated person U under the necessary tension.

[0091] Therefore, as shown in Figure 20, this chair is extremely suitable for tasks such as long-term PC operation where the sitter U leans back against the backrest 2, continuously views the screen MT in front, and moves their hands and arms. Of course, since this posture does not strain the body, it is also suitable for relaxing, resting, or taking a nap when not working.

[0092] Even when comparing the chair of the present invention with conventional cushion-type chairs, the three-dimensional shape of the upholstery material 22 is created in the upholstery material insertion section 23. Therefore, the shape of the backrest can be adjusted to the skeleton even before sitting down, and the softness of the mesh when the sitter leans against it can be adjusted to the muscles. In this respect, it differs from conventional chairs that use a core material to adjust to the skeleton and a cushion to adjust to the muscles, and is also fundamentally different from conventional chairs that simply have upholstery material attached.

[0093] Furthermore, the left and right side edges of the back-to-back correspondence position 223 are folded back together with the intermediate widening section 224 and supported by the intermediate section 213 of the back frame 201. This forms a folded section A5 that creates a partially pocket-like three-dimensional shape on the left and right side edges, ensuring strength while creating a frameless support structure that does not have a core material inside. Therefore, it is fundamentally different from conventional chairs with a frameless structure where the side edges of the upholstery material 22 are simply cut off.

[0094] As described above, the chair of this embodiment is A swivel chair in which a seat 1 is positioned on top of the legs 4 so as to be able to move up and down, A backrest 2 is placed at the rear of seat 1. The backrest 2 has a tensioned material 22 that is supported by the back frame 201 which constitutes the back support 21 and receives the weight of the seated person U. The tensioning material 22 has a recessed back support area S at the rear, The back support region S has a concave shape with back support surfaces A1 to A4 facing each other on the left and right and top and bottom.

[0095] With this shape of upholstery material 22, even if the back support surfaces A1 to A4 are made of upholstery material 22 that bears the weight, the concave shape of the rearward-recessed back support area S envelops the body of the sitter U. Therefore, compared to conventional swivel chairs in which the central back support surface bulges forward along the vertical direction, the stability of the sitter U when leaning against the backrest 2 can be improved.

[0096] In particular, the concave shape having upper and lower back support surfaces A3 and A4 facing each other allows the sitter U to lean against the backrest 2, and by placing the upper back support surface A4 against the area U3 of the back from the shoulder blades to the shoulder joint, the head U1 is raised, making it easier to assume a forward-facing posture. Moreover, the lower back support surface A3 faces the upper back support surface A4, causing it to be relatively upward, and by placing the thoracolumbar transition area U6 of the sitter U against this position, the load is supported, thus distributing the weight on the seat 1 and reducing the reaction force, pressure, and sitting fatigue experienced by the sitter U from the seat 1.

[0097] Furthermore, the back support area S is composed of back support surfaces A1 to A4 that face each other left and right and up and down, and supports the body of the seated person U by sandwiching it between them, making it easier for the backrest surface to fit the body of the seated person U.

[0098] Therefore, this chair can be suitably used as a swivel chair that does not cause fatigue even when used for long periods of time with the sitter U leaning back against the backrest 2, without consciously having to regulate their posture.

[0099] Furthermore, the back support surfaces A0 to A4 of this embodiment are surfaces facing multiple different directions, and valley lines B11 to B32 are formed between adjacent back support surfaces to separate them.

[0100] In this way, the three-dimensional shape of the backrest 2 can be constructed by a multifaceted combination of planes, and a concave shape can be appropriately realized in which the back support surfaces A1 to A4 tilt toward the central back support surface A0 of the backrest 2.

[0101] Specifically, the left and right back support surfaces A1 and A2, which face each other, are separated by the central back support surface A0, and first valley lines B11 and B12 are formed between the left and right back support surfaces A1 and A2 and the central back support surface A0, dividing the boundary.

[0102] In this way, the left and right support surfaces A1 and A2 bend and face the central support surface A0 at the boundary of the first valley lines B11 and B12, effectively supporting the seated person U by sandwiching their body from both sides.

[0103] Furthermore, at the boundary between the lower back support surface A3 and the left and right back support surfaces A1 and A2, there are second valley lines B21 and B22 that are continuous with the first valley lines B11 and B12 and open diagonally downward and outward, and between the left and right second valley lines B21 and B22, the lower back support surface A3 has a support function that faces diagonally forward and upward.

[0104] Therefore, if the seat is positioned so that the lower back support surface A3 supports the thoracolumbar transition area U6 from below, the weight on the seat 1 is distributed, reducing the reaction force F0 received by the sitter from the seat 1, the resulting pressure, and sitting fatigue.

[0105] Furthermore, at the boundary between the upper back support surface A4 and the left and right back support surfaces A1 and A2, there are third valley lines B31 and B32 that are continuous with the first valley lines B11 and B12 and open diagonally upward and outward, and the upper back support surface A4 has an upward support function between the left and right third valley lines B31 and B32.

[0106] Therefore, by tilting the backrest 2 backward so that the upper back support surface A4, located between the left and right third valley lines B31 and B32, faces diagonally upward, and by sitting in a way that supports the area U3 above the shoulder blades from below, the weight on the seat 1 is distributed, and the reaction force F0 received by the sitter from the seat 1, the resulting pressure, and sitting fatigue are reduced.

[0107] Furthermore, along the valley lines B11 to B32, a tension material pull-in section 23 is provided on the back side to pull the tension material 22 backward.

[0108] If one attempts to create a multifaceted surface with valley lines B11 to B32 simply by pulling the perimeter of the upholstery material 22 with the back frame 20, it becomes difficult to shape due to the upholstery material 22's tendency to become flat, and the high degree of freedom of movement of the upholstery material 22 when it shakes often results in insufficient support. In contrast, in this embodiment, a tension material pull-in section 23 is provided on the back side along the valley lines B11 to B32 to pull the upholstery material 22 backward. This makes it easier to create the three-dimensional shape of the backrest 2 and to adjust the tension, allowing for appropriate support by restricting the movement of the upholstery material 2 when the seated person U's body shakes.

[0109] In particular, the tensioning material 22 in this embodiment is a single continuous piece, and the tensioning material pull-in section 23 is connected to this tensioning material 22, so there is no need to join multiple tensioning materials 22 together. Furthermore, because the tensioning material pull-in section 23 is used in combination, the tensioning material 2 itself can be made into a single piece, but the necessary three-dimensional shape can be achieved.

[0110] The back support 21 has a front back frame 201 and a rear retraction receiving portion 202, with the peripheral edge of the tension material 22 being supported by the back frame 201 and one end of the tension material retraction portion 23 being supported by the retraction receiving portion 202.

[0111] In this way, the peripheral edge of the tensioning material 22 and the tensioning material insertion portion 23 can be properly stretched to the back support 21, thereby realizing the three-dimensional shape of the tensioning material 22.

[0112] In particular, the back frame 201 constituting the back support 21 of this embodiment has the front upper and lower back frames 211 and 212 connected at the rear intermediate section 213, and the ends of the tensioning material 22 are attached to the upper and lower back frames 211 and 212 and the intermediate section 213.

[0113] Therefore, the tensioning material 22 can be stretched in an appropriate three-dimensional manner in the front-to-back direction.

[0114] In this case, the tension material retraction section 23 is detachable from the rear intermediate section 213, and with one end of the tension material retraction section 23 attached to the rear retraction receiving section 202, the retraction receiving section 202 is attached to the rear intermediate section 213.

[0115] Therefore, the tensioning material retraction section 23 can be easily attached to the rear intermediate section 213 with a single touch.

[0116] Furthermore, although this embodiment primarily uses only the upholstery material 2 to construct the backrest 2, it can be suitably applied to swivel chairs in which the backrest 2 and seat 1 are supported so as to be able to swing back and forth and side to side, due to its appropriate support function.

[0117] Although one embodiment of the present invention has been described above, the specific configuration of each part is not limited to the embodiment described above.

[0118] For example, as shown in Figures 24(a) and 24(b), the tension material retraction portion 23 may be an excess portion formed by extending the tension material 22.

[0119] In this way, the tension material insertion section 23 and the tension material 22 can be configured as a single, integrated unit.

[0120] Furthermore, as shown in Figures 24(a) and 24(b), the excess portion may be formed by partially folding and joining the tensioning material 22.

[0121] In this way, a tension material pull-in portion 23 can be formed in the bending direction.

[0122] Furthermore, as shown in 24(b), the tensioning material 22 may be a single continuous piece including the tensioning material pull-in section 23.

[0123] This method allows for a further reduction in the number of parts.

[0124] Furthermore, as shown in Figure 24(b), it is also effective to construct the tensioning material from multiple pieces rather than a single piece. Figures 25(a) and (b) show that the back support surfaces A0 to A4 are constructed by connecting different tensioning materials 22(0) to 22(4), and valley lines B11 to B32 are formed at the boundaries of each support surface A0 to A4.

[0125] In this way, the direction of the elastic thread 22b (see Figure 9) sewn into each tensioning material can be made different for each tensioning material (each support surface), making it possible to individually set the elasticity and tensile strength of the backrest 2 for each position and direction of the support surface.

[0126] Furthermore, the above configuration is not limited to backrests; it is also effective when applied to seats. Figure 26 shows an example of this.

[0127] The seat 1 is positioned on the upper part of the legs so as to be able to move up and down, and the seat 1 has an upholstery material 1022 that is supported by a seat frame 1201 which constitutes the seat support and receives the weight of the person sitting on it, The upholstery material 1022 has a recessed seat support area S' at the bottom, The seat support region S' has a concave shape with seat support surfaces D1 to D4 facing each other on the left and right or front and back. The seat support surfaces D1 to D4 are surfaces facing in multiple different directions. This is a swivel chair in which valley lines H11 to H32 are formed between adjacent seat support surfaces D1 to D4, separating the boundaries.

[0128] On the back side of the valley lines H11 to H32, there is a tension material pull-in section 1023 that pulls the tension material 1022 downward.

[0129] Even with this configuration, the same effects and advantages as those of the above embodiment are achieved. [Explanation of symbols]

[0130] 1…za 2...backrest 21...back support 22...Tension material 23...Tension material insertion section 201…Back to back S…back support area A0…Back center support for the face A1, A2... Back and left / right support for the face A3…Back support for the face A4… Back support for face B11, B12... Valley Line 1 B21, B22... Valley Line 2 B31, B32... Third Valley Line U... seated

Claims

1. A swivel chair in which the seat is positioned on top of the legs so that it can be raised and lowered, A backrest is placed at the rear of the seat. The aforementioned backrest has a tensioned material that is supported by a back frame that constitutes a back support and bears the weight of the seated person. The aforementioned tensioning material has a rearward recessed back support region, The aforementioned back support region has a concave shape with back support surfaces facing each other on the left and right and up and down. A swivel chair characterized by the following features.

2. The swivel chair according to claim 1, wherein the back support surface is a surface facing multiple different directions, and a valley line is formed between adjacent back support surfaces to separate the boundaries.

3. The swivel chair according to claim 2, wherein the left and right opposing back support surfaces are sandwiched in the middle by a back central support surface, and a first valley line is formed between the back left and right support surfaces and the back central support surface to divide the boundary.

4. The swivel chair according to claim 2, wherein the boundary between the lower back support surface and the left and right back support surfaces has a second valley line that is continuous with the first valley line and opens diagonally downward and outward, and the lower back support surface has a support function that faces diagonally forward and upward between the left and right second valley lines.

5. The swivel chair according to claim 2, wherein the boundary between the upper back support surface and the left and right back support surfaces has a third valley line that is continuous with the first valley line and opens diagonally upward and outward, and the upper back support surface located between the left and right third valley lines has an upward support function.

6. The swivel chair according to claim 2, further comprising a tension material retraction section on its back side along the aforementioned valley line for pulling the tension material backward.

7. The swivel chair according to claim 6, wherein the upholstery material is a single continuous piece, and an upholstery material retraction section is connected to this upholstery material.

8. The swivel chair according to claim 6, wherein the tension material retraction portion is an excess portion formed by stretching the tension material.

9. The swivel chair according to claim 8, wherein the excess portion is formed by partially folding and joining the upholstery material.

10. The swivel chair according to claim 6, wherein the upholstery material is a single continuous piece including the upholstery material retraction section.

11. The swivel chair according to claim 6, wherein the back support has a front back frame and a rear retraction receiving portion, the peripheral edge of the upholstery is supported by the back frame, and one end of the upholstery retraction portion is supported by the retraction receiving portion.

12. The swivel chair according to claim 11, wherein the back support is formed by connecting the front upper and lower back frames at the rear middle section, and the ends of the upholstery material are attached to the upper and lower back frames and the middle section.

13. The swivel chair according to claim 12, wherein one end of the tensioning material retraction section is attached to the tensioning material, and the other end is attached to the retraction receiving section, and the retraction receiving section can be attached to the intermediate section.

14. The swivel chair according to claim 13, wherein the upholstery material, the upholstery material retraction section, and the upholstery material retraction receiving section are detachably attached to the back frame as a single unit.

15. The seat is positioned on top of the legs so that it can be raised and lowered. The seat has upholstery that is supported by a seat frame that constitutes the seat support and bears the weight of the person sitting on it. The aforementioned tensioning material has a recessed seating support area at the bottom, The aforementioned seat support region has a concave shape with seat support surfaces facing each other on the left and right and front and rear sides. The aforementioned seat support surface is a surface facing multiple different directions, A swivel chair characterized by having a valley line formed in the adjacent seat support surfaces to separate them.

16. The swivel chair according to claim 11, wherein the back side of the valley line has a tension material pull-in section for pulling the tension material downward.

17. The swivel chair according to any one of claims 1 to 16, wherein the backrest and seat are supported so as to be able to swing forward, backward, left, and right.

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