Chair

Abstract

This chair is provided with a seat, a backrest, an elastic member, and a support structure. The elastic member is configured to elastically deform in the vertical direction and the first direction by rotation of the backrest, and is configured to apply a restoring force caused by the elastic deformation to the seat and the backrest to return the seat and the backrest to an initial position.

Description

Technical Field

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

[0002] Conventionally, as a chair for office use or the like, a chair having an elastic member that moves the seat rearward as the backrest tilts is known (for example, Patent Document 1).

[0003] In the chair disclosed in Patent Document 1, a leaf spring that deforms as the backrest tilts and applies a restoring force to the backrest is provided on the seat carrier. The leaf spring is supported by two shafts.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: European Patent EP2888975B1 Summary of the Invention

[0007] (I) Technical Problem to be Solved

[0008] However, in the layout of the parts constituting the chair described in Patent Document 1, the portion where the leaf spring is provided is restricted, and there is a problem that it is difficult to sufficiently ensure the elastic deformation amount of the leaf spring.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a chair capable of sufficiently ensuring the elastic deformation amount of the elastic member and obtaining a sufficient restoring force.

[0010] (II) Technical Solution

[0011] A chair according to one embodiment of the present invention comprises: a seat having a lower surface in the up-down direction; a backrest capable of tilting relative to the seat from an initial position; an elastic member having a first end portion and a second end portion, the first end portion being connected to the backrest, the second end portion being located further forward than the first end portion in a first direction intersecting the up-down direction and being connected to the lower surface of the seat; and a supporting structure supporting the lower surface of the seat and the backrest, the supporting structure comprising: a seat supporting shaft portion supporting the seat in a manner that the seat can move relative to the first direction; a back supporting shaft portion extending along the A second direction extending in a direction intersecting the up-down direction and the first direction supports the backrest so as to be rotatable; and a position conversion mechanism supported so as to be rotatable relative to the seat support shaft and the back support shaft, and configured to convert the displacement of the position of the backrest caused by the rotation of the backrest into the displacement of the position of the seat, the elastic component being configured to be elastically deformed in the up-down direction and the first direction by the rotation of the backrest, and the elastic component being configured to apply a restoring force caused by the elastic deformation to the seat and the backrest so as to return the seat and the backrest to the initial position.

[0012] In the chair of the above-mentioned manner, when the occupant is seated on the seat and the occupant presses the backrest backward with his back facing backward in the first direction, the first end of the elastic member moves backward in conjunction with the movement of the backrest backward, and the elastic member is elastically deformed. At this time, the backrest rotates relative to the back support shaft in conjunction with the movement of the backrest backward. A position conversion mechanism provided on the backrest converts the displacement of the position of the backrest caused by the rotation of the backrest into the displacement of the position of the seat. The seat support shaft supported by the position conversion mechanism causes the seat to move backward. The second end of the elastic member connected to the seat also moves backward in the same manner.

[0013] In contrast, when the seated person stands up toward the front in the first direction, the back of the seated person leaves the backrest. At this time, the first end of the elastic member moves forward due to the restoring force of the elastic member after elastic deformation. At this time, the backrest rotates relative to the back support shaft in conjunction with the forward movement of the backrest. The position conversion mechanism provided on the backrest converts the displacement of the position of the backrest caused by the rotation of the backrest into the displacement of the position of the seat. The seat support shaft supported by the position conversion mechanism moves the seat toward the front. The second end of the elastic member connected to the seat also moves toward the front in the same manner.

[0014] In the chair according to the above-described manner, the backrest is not directly supported by the seat, and a position conversion mechanism is interposed between the backrest and the seat. In this way, by interposing the position conversion mechanism between the backrest and the seat, the displacement amount of the seat linked to the rotation of the backrest can be appropriately set. For example, the displacement amount of the seat can be reduced relative to the displacement amount of the backrest, so that the elastic member can be elastically deformed greatly in the vertical direction.

[0015] In addition, since the displacement amount of the seat linked to the rotation of the backrest can be appropriately set, even if the backrest is moved greatly in the first direction, the movement amount of the seat can be adjusted to be smaller than the movement amount of the backrest. Moreover, the elastic deformation amount of the elastic member can be sufficiently ensured, and sufficient restoring force can be obtained. In addition, it is not necessary to extend the elastic member greatly forward in the first direction, and the effect of not extending the elastic member forward of the support structure can also be obtained.

[0016] In the chair according to one embodiment of the present invention, the seat support shaft portion may have: a first shaft portion that extends in the second direction and supports the seat so as to be rotatable; and a second shaft portion that extends in the second direction and supports the seat so as to be rotatable. The backrest support shaft portion has: a third shaft portion that is located below the first shaft portion in the vertical direction, extends in the second direction, and supports the backrest so as to be rotatable. The position conversion mechanism has: a fourth shaft portion that is located below the second shaft portion in the vertical direction and extends in the second direction; a support connector that is rotatably supported by the first shaft portion, rotatably supported by the third shaft portion, and connected to the backrest; and a support link that is rotatably supported by the second shaft portion and rotatably supported by the fourth shaft portion. The support structure has a support for supporting the third shaft portion and the fourth shaft portion. The support connector and the support link are configured to return the seat and the backrest to the initial position by the restoring force of the elastic member.

[0017] In the support structure having such a seat support shaft portion, a backrest support shaft portion, and a position conversion mechanism, the support connector and the seat can rotate relative to each other about the first shaft portion. In other words, the support connector that supports the backrest and the seat can rotate relative to each other about the first shaft portion. The seat and the support link can rotate relative to each other about the second shaft portion. The support connector and the support can rotate relative to each other about the third shaft portion. In other words, the support connector that supports the backrest and the support can rotate relative to each other about the third shaft portion. The backrest and the support connector can rotate relative to each other. The support and the support link can rotate relative to each other about the fourth shaft portion.

[0018] In the chair of the above-mentioned manner, when the seated person is seated on the seat, when the seated person presses the backrest backward with the back facing backward in the first direction, the first end of the elastic member moves backward in conjunction with the movement of the backrest backward, and the elastic member is elastically deformed. At this time, in conjunction with the movement of the backrest backward, the backrest rotates around the third shaft portion supported by the support. The support connector connected to the backrest rotates around the third shaft portion. The support connector supporting the first shaft portion moves the first shaft portion backward. The first shaft portion moves the seat backward. As the seat moves backward, the second shaft portion supporting the seat also moves backward. The support link supporting the second shaft portion rotates around the fourth shaft portion.

[0019] In contrast, when the seated person stands up forward in the first direction, the back of the seated person leaves the backrest. At this time, the first end of the elastic component moves forward due to the restoring force of the elastic component after elastic deformation. At this time, the backrest rotates around the third shaft portion supported on the support in conjunction with the forward movement of the backrest. The supporting connector connected to the backrest rotates around the third shaft portion. The supporting connector supporting the first shaft portion moves the first shaft portion forward. The first shaft portion moves the seat forward. As the seat moves forward, the second shaft portion of the supporting seat also moves forward. The supporting connecting rod supporting the second shaft portion rotates around the fourth shaft portion. As a result, the supporting connector and the supporting connecting rod return the seat and the backrest to their initial positions through the restoring force of the elastic component.

[0020] According to the chair of the above aspect, the above effects can be obtained by the support structure including the first shaft portion, the second shaft portion, the third shaft portion, the fourth shaft portion, the support connector, the support link, and the seat.

[0021] In the chair according to one aspect of the present invention, the elastic member may include a bent portion located between the first end portion and the second end portion.

[0022] According to the chair of the above aspect, a difference can be generated between the position of the first end portion and the position of the second end portion in the vertical direction. Therefore, it is easy to attach the elastic member to both the seat and the backrest.

[0023] In a chair according to one embodiment of the present invention, the first end of the elastic component may be located at the upper end of the elastic component in the up-down direction, the second end of the elastic component may be located at the front end of the elastic component in the first direction, and the elastic component may have a curved portion between the first end and the second end.

[0024] In the chair according to the above-described manner, when the elastic member elastically deforms, elastic deformation occurs at the bending portion located between the first end portion and the second end portion. In other words, the elastic member deforms in such a manner that the angle changes between the direction from the bending portion toward the first end portion and the direction from the bending portion toward the second end portion. Thus, in linkage with the displacement of the backrest, the elastic member is easily flexed. Therefore, the elastic member can be smoothly flexed, and the restoring force can be stably obtained.

[0025] In the chair according to one embodiment of the present invention, it may also be that, when viewed in the second direction, the bending portion has an upper extension portion connected to the first end portion and a front extension portion connected to the second end portion, and the upper extension portion and the front extension portion are connected in an L-shaped manner.

[0026] In the chair according to the above-described manner, in the vertical direction, the first end portion is located above the second end portion. Therefore, when the bending portion bends as the backrest moves backward and downward, the upper extension portion is more likely to deform backward by an amount equal to the length of the upper extension portion compared to the front extension portion. Therefore, the elastic member can be smoothly flexed, and the restoring force can be stably obtained.

[0027] In the chair according to one embodiment of the present invention, it may also be that the elastic member has: an upper region portion, which is located between the first end portion and the upper extension portion and extends in the vertical direction; and a front region portion, which is located between the second end portion and the front extension portion and extends in the first direction, and at least one of the upper region portion and the front region portion is formed in a straight line.

[0028] In the chair according to the above-described manner, since at least one of the upper region portion and the front region portion is formed in a straight line, for the region portion formed in a straight line, it is easy to deform by an amount equal to the length of the region portion. Therefore, the elastic member can be smoothly flexed, and the restoring force can be stably obtained

[0029] In the chair according to one embodiment of the present invention, it may also be that the seat has: a seat main body, which has the lower surface; and a seat bearing member, which is separate from the seat main body, and the seat bearing member supports the seat main body, the first shaft portion, and the second shaft portion, and is connected to the second end portion of the elastic member.

[0030] In the chair according to the above-described manner, a structure in which the elastic member is connected to the seat bearing member can be obtained. The seat bearing member is connected to the backrest via a support structure. In the operation of assembling the components constituting the chair, the operation of first connecting the elastic member and the seat bearing member to each other and then housing the seat bearing member in the seat main body can be performed. Thus, the assembly operation can be simply performed.

[0031] (III) Advantageous Effects

[0032] A chair according to the method of the present invention can fully ensure the elastic deformation amount of the elastic member and obtain sufficient resilience. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. 7 is a perspective view of a chair according to an embodiment of the present invention as viewed obliquely from the front.

[0034] Figure 2 FIG. 11 is an exploded perspective view of a part of a chair according to an embodiment of the present invention, showing a part of the components constituting the seat and the support structure.

[0035] Figure 3 FIG. 15 is a perspective view of a part of the operating mechanism of the seat of a chair according to an embodiment of the present invention.

[0036] Figure 4 FIG. 19 is a perspective view of a part of the operating mechanism inside the support of a part of the support structure of a chair according to an embodiment of the present invention, showing the state where the support cover is removed.

[0037] Figure 5A FIG. 23 is an exploded perspective view of a part of a chair according to an embodiment of the present invention, showing the components constituting the backrest and the support structure respectively.

[0038] Figure 5B FIG. 27 is a perspective view of the elastic member of a chair according to an embodiment of the present invention.

[0039] Figure 6 FIG. 31 is a side view showing a main part of the arm portion of the backrest of a chair according to an embodiment of the present invention in an enlarged manner.

[0040] Figure 7 FIG. 35 is a perspective view of the first seat bearing member of the support structure of a chair according to an embodiment of the present invention.

[0041] Figure 8 FIG. 39 is a perspective view of the second seat bearing member of the support structure of a chair according to an embodiment of the present invention.

[0042] Figure 9 FIG. 43 is a perspective view of the support connector of the support structure of a chair according to an embodiment of the present invention.

[0043] Figure 10 FIG. 47 is a perspective view of the support of the support structure of a chair according to an embodiment of the present invention.

[0044] Figure 11 FIG. 51 is a perspective view of the support cover of the support structure of a chair according to an embodiment of the present invention.

[0045] Figure 12 This is a side view showing the structure formed by locally combining the seat, backrest, and support structure of a chair constituting an embodiment of the present invention, and is a view showing the state where the backrest is disposed at the front limit position.

[0046] Figure 13 This is a side view showing the structure formed by locally combining the seat, backrest, and support structure of a chair constituting an embodiment of the present invention, and is a view showing the state where the backrest is disposed at the rear limit position.

[0047] Figure 14A This is a side view illustrating a method of coupling the arm portion of the backrest of a chair constituting an embodiment of the present invention to a support connector constituting the support structure.

[0048] Figure 14B This is a side view illustrating a method of coupling the arm portion of the backrest of a chair constituting an embodiment of the present invention to a support connector constituting the support structure. Detailed Embodiment

[0049] A chair according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0050] In the following description, the same reference numerals are assigned to structures having the same or similar functions. Also, repeated descriptions of these structures are sometimes omitted. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as in reality.

[0051] In the following description, for the sake of convenience, the direction in which a seated person sitting on the seat 1 in a normal posture faces forward is referred to as "front", and the opposite direction is referred to as "rear". In addition, the up-down and left-right orientations in the following description are consistent with the orientations centered on the seated person when the seated person is sitting on the seat 1 in a normal posture. Further, in the drawings, an arrow FD pointing forward, an arrow BD pointing backward, an arrow UD pointing upward, an arrow DD pointing downward, an arrow RD pointing rightward, and an arrow LD pointing leftward are shown.

[0052] The upward direction UD and the downward direction DD are consistent with the up-down direction (gravity direction).

[0053] The downward direction DD may also be simply referred to as "top view". The upward direction UD and the downward direction DD may also be referred to as the up-down directions UD, DD.

[0054] The front direction FD and the rear direction BD each correspond to a first direction that intersects the up-and-down direction. The front direction FD and the rear direction BD can each be a direction parallel to the horizontal plane, or an inclined direction that is inclined with respect to the horizontal plane. The front direction FD and the rear direction BD may also be referred to as the front-rear directions FD, BD. Herein, the "horizontal plane" refers to a plane orthogonal to the up-and-down direction.

[0055] The right direction RD and the left direction LD each correspond to a second direction that intersects the up-and-down direction and the first direction. That is, the right direction RD and the left direction LD are directions that intersect the up-and-down direction and the front-rear directions FD, BD. The right direction RD or the left direction LD may also be simply referred to as "side view". The right direction RD and the left direction LD may also be referred to as the left-right directions RD, LD.

[0056] In addition, there are cases where a plane parallel to the front-rear directions FD, BD and the left-right directions RD, LD is referred to as the "horizontal direction" or the "horizontal plane".

[0057] In the description of the chair, "displacement" refers to a change in position in the up-and-down direction, the front-rear direction, and the left-right direction, a change in the distance between two components, a change in the trajectory of the time-dependent movement of the components constituting the chair when observed in the left-right direction, and a change in the angle in the rotational direction about an axis parallel to the left-right direction. In addition, "amount of movement", "amount of displacement", "amount of rotation", and "amount of turning" refer to the "amount" of the above-mentioned "displacement".

[0058] <Chair 100>

[0059] As Figure 1 shown, the chair 100 of the present embodiment has a seat 1, a backrest 2, and a support structure 3. The chair 100 is used in a state where the chair 100 is placed on the ground FS and a seated person is seated on the seat 1.

[0060] The backrest 2 is connected to the seat 1 via the support structure 3 in a manner that enables linkage. In other words, in the structure of the chair 100, the backrest 2 is not directly supported by the seat 1.

[0061] The backrest 2 can move or tilt backward in the tilting range 80 indicated by the symbol 80. The tilting range 80 is the range between the front limit position 81 and the rear limit position 82.

[0062] The front limit position 81 is the position where the seated person is in a state of not pressing the backrest 2 backward in the rear direction BD. That is, the front limit position 81 is the initial position of the backrest 2. The rear limit position 82 is the position of the backrest 2 that has moved the maximum distance backward in the state where the seated person presses the backrest 2 backward in the rear direction BD.

[0063] <Seat 1>

[0064] As Figure 1 , Figure 2 and Figure 3 shown, the seat 1 has a seat main body 4, a seat receiving member 40, and an operating mechanism 5.

[0065] <Seat main body 4>

[0066] The seat main body 4 is a plate-shaped member that elastically supports the buttocks and thighs of the sitter.

[0067] The seat main body 4 is a plate parallel to the front-rear direction FD, BD or a direction inclined with respect to the front-rear direction FD, BD and parallel to the left-right direction RD, LD. The seat main body 4 has a seat plate lower surface 4L facing the downward direction DD and a seat upper surface 4U facing the upward direction UD. The seat plate lower surface 4L faces the ground FS. The seat plate lower surface 4L is an example of the "lower surface". The seat plate upper surface 4U is a curved surface having a three-dimensional shape corresponding to the shape of the buttocks and thighs of the sitter. The seat plate upper surface 4U is covered with a stretching material 4M. As the material constituting the seat main body 4, a known resin material or metal material is used. The material of the stretching material 4M is, for example, a cloth such as a net.

[0068] A support mechanism storage portion 6 and an operating mechanism storage portion 7 are formed on the seat plate lower surface 4L.

[0069] The support mechanism storage portion 6 and the operating mechanism storage portion 7 are each an example of a "recess". In order to distinguish each of the support mechanism storage portion 6 and the operating mechanism storage portion 7, the support mechanism storage portion 6 may be referred to as the "first recess", and the operating mechanism storage portion 7 may be referred to as the "second recess".

[0070] <Support mechanism storage portion 6>

[0071] The support mechanism storage portion 6 is formed substantially at the center of the seat main body 4 in the front-rear direction FD, BD and the left-right direction RD, LD.

[0072] The support mechanism storage portion 6 has a support concave surface 6A formed inside the support mechanism storage portion 6. Four seat receiving fastening holes 6B are formed in the support concave surface 6A. The four seat receiving fastening holes 6B are each, for example, a threaded hole.

[0073] Regarding the depth of the support mechanism storage portion 6 from the seat plate lower surface 4L toward the upward direction UD, the support mechanism storage portion 6 has a depth 6D from the edge portion 6C of the support mechanism storage portion 6 to the support concave surface 6A in the upward direction UD. The depth 6D of the support mechanism storage portion 6 can be appropriately set according to the design of the seat main body 4 and the seat receiving member 40 described later.

[0074] <Operating mechanism storage portion 7>

[0075] The operating mechanism storage part 7 has a rod storage part 7A and a wire storage part 7B.

[0076] In the present embodiment, the rod storage part 7A is formed at a position more forward than the support mechanism storage part 6 in the front direction FD and more to the right than the support mechanism storage part 6 in the right direction RD. The position of the rod storage part 7A is not limited to Figure 2 the position shown. The rod storage part 7A has a rod concave surface 7C formed inside the rod storage part 7A. An axis fixing hole 7D is formed in the rod concave surface 7C. The axis fixing hole 7D is, for example, a threaded hole.

[0077] The wire storage part 7B is, for example, a groove formed in the lower surface 4L of the seat plate. The depth of the operating mechanism storage part 7 from the lower surface 4L of the seat plate toward the upper direction UD is appropriately set according to the sizes of the respective components constituting the operating mechanism 5. In the direction in which the wire storage part 7B extends, the wire storage part 7B has a locally formed bent part and a straight part.

[0078] In Figure 2 the example shown, when viewed in the upper direction UD, the wire storage part 7B is formed in a substantially U-shape. The shape of the wire storage part 7B is set according to the design of the chair 100 considering the position of the rod storage part 7A. For example, according to the position of the rod storage part 7A in the front-rear direction FD, BD and the left-right direction RD, LD, that is, the position of the rod storage part 7A in the horizontal direction, the shape of the wire storage part 7B can be an I-shape or an inverted L-shape. When the shape of the wire storage part 7B is an I-shape, for example, the operating mechanism 5 can be arranged on the lower surface 4L of the seat plate at intervals so as to be arranged in the left-right direction RD, LD with the support structure 3.

[0079] <Seat bearing member 40>

[0080] The seat bearing member 40 forms a part of the seat 1. The seat bearing member 40 is separated from the seat main body 4. In other words, the seat bearing member 40 can be detached from the seat main body 4.

[0081] The structure of the seat bearing member 40 will be described later.

[0082] <Operating mechanism 5>

[0083] As Figure 2 、 Figure 3 and Figure 4 shown, the operating mechanism 5 has an operating part 10, a wire structure body 11, a pressing part 12, an operating part cover 13 and a wire holding claw 14. In addition, Figure 3 shows a state in which the operating part 10 is detached from the lower surface 4L of the seat plate. Figure 4 shows a part of the operating mechanism 5 disposed inside a support seat that forms a part of the support structure 3. InFigure 4 In the figure, the illustration of the support cover is omitted.

[0084] The operating mechanism 5 is housed in the rod housing portion 7A and the wire housing portion 7B in the lower surface 4L of the seat plate. Moreover, a part of the operating mechanism 5 is housed in the support.

[0085] <Operating portion 10>

[0086] The operating portion 10 has a rod support shaft 10A, a rod plate 10B, a wire support portion 10C, and a rod 10D. The operating portion 10 is housed in the rod housing portion 7A.

[0087] <Rod support shaft 10A>

[0088] The rod support shaft 10A extends in the vertical directions UD and DD. The rod support shaft 10A has a threaded groove portion 10E, a rotational support portion 10F, and a head portion 10G. The head portion 10G is located at the end of the rod support shaft 10A in the downward direction DD. The threaded groove portion 10E is threadedly fixed to the shaft fixing hole 7D. Thus, the threaded groove portion 10E is fixed to the operating mechanism housing portion 7. The rod support shaft 10A supports the rod plate 10B so that the rod plate 10B can rotate around the rotational support portion 10F. As the material constituting the rod support shaft 10A, a known resin material or metal material is used.

[0089] <Rod plate 10B>

[0090] The rod plate 10B extends in a direction orthogonal to the vertical directions UD and DD. The rod plate 10B has a support end portion 10H and a rotational end portion 10I. A support shaft hole 10J is formed in the support end portion 10H. The rotational support portion 10F is inserted into the support shaft hole 10J. The diameter of the support shaft hole 10J is smaller than the diameter of the head portion 10G. Thus, the rod plate 10B is prevented from falling off the operating mechanism housing portion 7 in the downward direction DD by the head portion 10G. As the material constituting the rod plate 10B, a known resin material or metal material is used.

[0091] <Wire support portion 10C>

[0092] The wire support portion 10C is a protrusion protruding downward from the rod plate 10B in the direction DD. The wire support portion 10C is located between the support end portion 10H and the rotational end portion 10I in the direction in which the rod plate 10B extends. The wire support portion 10C is fixed to a hole formed in the rod plate 10B.

[0093] <Rod 10D>

[0094] The rod 10D extends in the up-and-down directions UD and DD. The upper end of the rod 10D in the upward direction UD is fixed to the rotating end 10I of the rod plate 10B. The rod 10D is, for example, a part where a seated person operates the operation unit 10 with a finger. The rod 10D can rotate around the rod support shaft 10A. Specifically, the rod 10D can move in a manner that depicts an arc-shaped trajectory in the horizontal direction. The arc-shaped trajectory refers to a part of an arc of a circle centered on the rod support shaft 10A.

[0095] As the material constituting the rod 10D, a known resin material or metal material is used. The rod 10D can be formed of the same component integrally with the rod plate 10B, or can be separated from the rod plate 10B in a manner separate from the rod plate 10B.

[0096] The operation unit 10 having such a structure is housed in the rod housing part 7A. Considering the operability of the operation unit 10 and the chair 100 by the seated person, the position of the operation unit 10, the position and shape of the rod housing part 7A are set.

[0097] If explained based on the lever principle related to the fulcrum, effort point, and load point, in the operation unit 10 having the above structure, the rod support shaft 10A corresponds to the fulcrum, the rod 10D corresponds to the effort point, and the wire support part 10C of the rod plate 10B corresponds to the load point. In the structure utilizing such a lever principle, the rod 10D and the wire support part 10C are in the horizontal direction.

[0098] Regarding the relative positional relationship of the rod support shaft 10A, the rod 10D, and the wire support part 10C in the extending direction of the rod plate 10B, it is appropriately set in consideration of the lever principle and the operability of the chair 100.

[0099] <Wire structure 11>

[0100] The wire structure 11 has an outer tube 11A, an inner wire 11B, a first wire engaging end 11F (first engaging end), and a second wire engaging end 11S (second engaging end). In the front-back directions FD and BD and the left-right directions RD and LD, the wire structure 11 is supported by the wire housing part 7B. The length of the wire structure 11 is set according to the formation pattern of the wire housing part 7B formed on the lower surface 4L of the seat plate and the design of the chair 100.

[0101] <Outer tube 11A>

[0102] The outer tube 11A is, for example, a flexible resin-made cylindrical body. The outer tube 11A has flexibility. A space is formed inside the outer tube 11A. This space extends in the extending direction of the outer tube 11A. The outer tube 11A is housed and fixed in the wire housing part 7B. The wire housing part 7B statically holds the outer tube 11A. As such an outer tube 11A, a known outer tube is used.

[0103] <Inner wire 11B>

[0104] The inner wire 11B has a structure in which, for example, multiple thin metal wires are woven in and has flexibility. The inner wire 11B is located in the inner space of the outer tube 11A and can move relative to the outer tube 11A held by the wire storage portion 7B. In other words, the inner wire 11B can move inside the fixed outer tube 11A while deforming in a manner that extends along the extending direction of the outer tube 11A. As such an inner wire 11B, a known inner wire is used.

[0105] <First wire engaging end 11F>

[0106] The first wire engaging end 11F is connected to the front end (first front end) of the inner wire 11B. Inside the rod storage portion 7A, the first wire engaging end 11F engages with the wire support portion 10C. The first wire engaging end 11F can rotate around the wire support portion 10C. The engaging structure between the first wire engaging end 11F and the wire support portion 10C is not particularly limited. For example, a structure in which the wire support portion 10C and the first wire engaging end 11F each have a hook and the two hooks engage can also be adopted. It can also be that the wire support portion 10C has a small diameter portion with a smaller diameter and a large diameter portion with a diameter larger than that of the small diameter portion, and the first wire engaging end 11F engages with the small diameter portion.

[0107] <Second wire engaging end 11S>

[0108] The second wire engaging end 11S is connected to the front end (second front end) of the inner wire 11B located on the upper surface of the support cover. On the upper surface of the support cover, the second wire engaging end 11S engages with the pressing portion 12.

[0109] <Pressing portion 12>

[0110] As Figure 4 shown, the pressing portion 12 has a pressing body 12A, a pressing support shaft 12B, a pressing engaging portion 12C, and a pressing force generating portion 12G.

[0111] <Pressing body 12A>

[0112] The pressing body 12A has, for example, a substantially triangular shape. The shape of the pressing body 12A is not limited to a substantially triangular shape. As long as it has a pressing support shaft 12B, a pressing engaging portion 12C, and a pressing force generating portion 12G, the shape of the pressing body 12A is appropriately selected. As the material constituting the pressing body 12A, known resin materials and metal materials are used.

[0113] At Figure 4In the example shown, the pressing portion 12 has a thickness in the direction indicated by symbol T, a height in the direction indicated by symbol H, and a length in the direction indicated by symbol L. In the following description, the expressions "thickness direction T", "height direction H", and "length direction L" are sometimes used to describe the pressing portion 12. Additionally, the height direction H is a direction parallel or inclined with respect to the up-down directions UD and DD. The thickness direction T is a direction parallel or inclined with respect to the front-back directions FD and BD. The length direction L is a direction parallel or inclined with respect to the left-right directions RD and LD.

[0114] <Pressing support shaft 12B>

[0115] The pressing support shaft 12B forms a part of the pressing body 12A. The pressing support shaft 12B extends along the thickness direction T. The pressing support shaft 12B supports the pressing body 12A in such a manner that the pressing body 12A can rotate about the pressing support shaft 12B. Additionally, the pressing support shaft 12B can be formed of the same component integrally with the pressing body 12A, or can be separated from the pressing body 12A in a manner that is separate from the pressing body 12A.

[0116] In the present embodiment, the pressing support shaft 12B is supported by a later-described support base cover 65 so as to be rotatable. As long as the pressing body 12A can rotate about the pressing support shaft 12B, the pressing support shaft 12B can also be supported by the support base 60.

[0117] <Pressing engagement portion 12C>

[0118] The pressing engagement portion 12C is formed on the pressing body 12A at a position away from the pressing support shaft 12B in the height direction H. The pressing engagement portion 12C forms a part of the pressing body 12A. The pressing engagement portion 12C has a wire insertion groove 12D and a wire support groove 12E. The wire insertion groove 12D is a groove through which the second wire engagement end 11S is inserted when the second wire engagement end 11S is hooked on the pressing portion 12. The wire support groove 12E is a groove that supports the second wire engagement end 11S.

[0119] <Wire insertion groove 12D>

[0120] The wire insertion groove 12D is formed, for example, to extend from the upper end 12U of the pressing body 12A toward the inside of the pressing body 12A in the height direction H. The depth of the wire insertion groove 12D in the height direction H is not particularly limited, and the wire insertion groove 12D only needs to have a depth sufficient to support the second wire engagement end 11S. The wire insertion groove 12D is located approximately at the center in the thickness direction T.

[0121] <Wire support groove 12E>

[0122] The wire support groove 12E has a shape corresponding to the shape of the second wire engagement end 11S.

[0123] The wire support groove 12E is provided on the surface of the pressing body 12A on the side opposite to the second wire engaging end 11S. The wire support groove 12E is formed to extend toward the inside of the pressing body 12A in the longitudinal direction L or in a direction inclined with respect to the longitudinal direction L. The depth of the wire support groove 12E in the longitudinal direction L is not particularly limited, and the wire support groove 12E only needs to have a depth sufficient to support the second wire engaging end 11S.

[0124] The engaging structure between the pressing engaging portion 12C and the second wire engaging end 11S is not particularly limited. For example, a structure in which the pressing engaging portion 12C and the second wire engaging end 11S each have a hook and the two hooks are engaged can also be adopted.

[0125] <Pressing force generating portion 12G>

[0126] The pressing force generating portion 12G is formed on the pressing body 12A at a position away from the pressing support shaft 12B in the longitudinal direction L. In Figure 4 the example shown, the pressing force generating portion 12G is a surface that is a part of the pressing body 12A. The pressing force generating portion 12G is located below the pressing body 12A in the height direction H.

[0127] If explained based on the lever principle related to the fulcrum, the force point, and the point of action, in the pressing portion 12 having the above structure, the pressing support shaft 12B corresponds to the fulcrum, the pressing engaging portion 12C corresponds to the force point, and the pressing force generating portion 12G corresponds to the point of action. In a structure utilizing such a lever principle, the pressing engaging portion 12C and the pressing force generating portion 12G are located in the height direction H. In other words, the pressing engaging portion 12C and the pressing force generating portion 12G are located in a direction different from the horizontal direction. The relative positional relationship of the pressing support shaft 12B, the pressing engaging portion 12C, and the pressing force generating portion 12G in the height direction H and the longitudinal direction L is appropriately set in consideration of the lever principle and the operability of the chair 100.

[0128] <Operation portion cover 13>

[0129] As Figure 2 shown, the operation portion cover 13 is a portion that is fitted to the rod storage portion 7A. A through hole 13A is formed in the operation portion cover 13. The rod 10D is inserted through the through hole 13A. The shape of the through hole 13A is an arc shape so that the rod 10D can move within an arc-shaped movement range. Using fastening members such as bolts (not shown), the operation portion cover 13 is fastened to the seat main body 4. In a state where the operation portion cover 13 is fitted to the rod storage portion 7A, a part of the rod 10D passing through the through hole 13A protrudes from the lower surface 4L of the seat plate, and the operation portion 10 is stored in the space formed between the operation portion cover 13 and the rod storage portion 7A.

[0130] <Wire holding claw 14>

[0131] The wire holding claw 14 is provided on the lower surface 4L of the seat plate in the extending direction of the groove-shaped wire storage portion 7B. The wire holding claw 14 holds the wire structure 11 disposed within the wire storage portion 7B. The wire holding claw 14 is fixed to the lower surface 4L of the seat plate using fastening members such as bolts (not shown), for example. The wire holding claw 14 shields the opening end portion of the groove-shaped wire storage portion 7B in the downward direction DD at an appropriate position in the horizontal direction. Thereby, the wire holding claw 14 prevents the wire structure 11 from falling off the wire storage portion 7B in the downward direction DD. Additionally, the wire holding claw 14 may be integrally formed with the lower surface 4L of the seat plate.

[0132] <Backrest 2>

[0133] The backrest 2 is tiltable relative to the seat 1.

[0134] As Figure 1 、 Figure 5A 、 Figure 5B And Figure 6 As shown, the backrest 2 has an arm portion 20, a back receiving portion 21, an elastic member 23, an elastic member support portion 24, and a backrest cover 25. The backrest 2 is a portion that supports the back of the seated person. As the materials constituting the arm portion 20, the back receiving portion 21, the elastic member support portion 24, and the backrest cover 25, known resin materials and metal materials are used.

[0135] <Arm portion 20>

[0136] The arm portion 20 is supported by the support structure 3.

[0137] The arm portion 20 is formed in a substantially L-shape when viewed in the right direction RD. The arm portion 20 has a longitudinal arm 20A and a transverse arm 20B. The longitudinal arm 20A is located below the seat main body 4. The longitudinal arm 20A extends in the up-and-down direction UD, DD. The transverse arm 20B extends in the front-and-back direction FD, BD. The longitudinal arm 20A may be formed of the same member integrally with the transverse arm 20B, or may be separated from the transverse arm 20B in a separated manner.

[0138] The longitudinal arm 20A supports the back receiving portion 21. The transverse arm 20B has an arm opening 20C, a first support arm 20F, a second support arm 20S, and a reinforcing arm 20D. The arm opening 20C is an opening through which a part of the elastic member 23 is inserted when the elastic member 23 is mounted on the rear surface of the longitudinal arm 20A facing the back direction BD. The reinforcing arm 20D extends in the left-and-right direction RD, LD. The reinforcing arm 20D is provided between the first support arm 20F and the second support arm 20S. Thereby, the strength of the transverse arm 20B is improved.

[0139] <First support arm 20F>

[0140] The first support arm 20F has a first shaft support hole 26F. The first shaft support hole 26F is provided on the side of the first support arm 20F opposite to the longitudinal arm 20A. In other words, the first shaft support hole 26F is located in front of the first support arm 20F in the forward direction FD. The first support arm 20F is mounted to the rear part of the support via the first shaft support hole 26F. The first support arm 20F has a first arm groove 27F provided between the first shaft support hole 26F and the reinforcement arm 20D. The first arm groove 27F opens toward the left direction LD.

[0141] Figure 6 is an enlarged view showing an enlarged portion indicated by symbol A of Figure 5A . In other words, Figure 6 is a side view partially showing the first support arm 20F as viewed from the second support arm 20S in the right direction RD. The first arm groove 27F has an obliquely opening groove 28A, a front-and-rear extending groove 28B, and a groove inner part 28C. The first arm groove 27F opens toward the left direction LD. In other words, the first arm groove 27F is exposed in the space between the first support arm 20F and the second support arm 20S.

[0142] The obliquely opening groove 28A is formed in the first support arm 20F so as to extend in the groove inclination direction 29A. Here, the groove inclination direction 29A is the direction from the arm upper surface 29T of the first support arm 20F toward the inside of the first support arm 20F. In other words, the groove inclination direction 29A is a direction inclined with respect to the extending direction 20E in which the first support arm 20F extends. The obliquely opening groove 28A opens in the upward direction UD and the left direction LD on the arm upper surface 29T.

[0143] The obliquely opening groove 28A has two obliquely groove walls 28N1, 28N2 facing each other. The width between the two obliquely groove walls 28N1, 28N2 is slightly wider than the diameter of the right arm engaging portion 51J described later. Thus, the obliquely opening groove 28A enables the right arm engaging portion 51J to be inserted between the obliquely groove walls 28N1, 28N2.

[0144] The front-and-rear extending groove 28B is formed in the first support arm 20F so as to be connected to the obliquely opening groove 28A in the groove inclination direction 29A. The front-and-rear extending groove 28B extends in the extending direction 20E. The front-and-rear extending groove 28B opens in the groove inclination direction 29A and the left direction LD.

[0145] The front-and-rear extending groove 28B has two extending groove walls 28M1, 28M2 facing each other. The extending groove wall 28M1 is the surface connected to the obliquely groove wall 28N1. The extending groove wall 28M2 is the surface connected to the obliquely groove wall 28N2.

[0146] The width between the two extending groove walls 28M1 and 28M2 is slightly wider than the diameter of the right arm engaging portion 51J described later. Thus, the front and rear extending groove 28B enables the right arm engaging portion 51J to be inserted between the extending groove walls 28M1 and 28M2.

[0147] The inner part 28C of the groove is the part located at the rearmost of the front and rear extending groove 28B. In other words, the inner part 28C of the groove is the part at the end of the front and rear extending groove 28B in the groove extending direction 29B. The groove extending direction 29B is a direction parallel to the extending direction 20E. The inner part 28C of the groove opens toward the extending direction 20E and the left direction LD.

[0148] The inner part 28C of the groove has a curved surface. The curved surface of the inner part 28C of the groove has a shape along the surface shape of the right arm engaging portion 51J.

[0149] <Second support arm 20S>

[0150] The second support arm 20S has a second shaft support hole 26S. The second shaft support hole 26S is provided on the second support arm 20S on the side opposite to the longitudinal arm 20A. In other words, the second shaft support hole 26S is located in front of the second support arm 20S in the front direction FD. The second support arm 20S is mounted on the rear part of the support via the second shaft support hole 26S. The second support arm 20S has a second arm groove 27S provided between the second shaft support hole 26S and the reinforcing arm 20D. The second arm groove 27S opens toward the right direction RD.

[0151] The second arm groove 27S has an obliquely opening groove 28A, a front and rear extending groove 28B, and an inner part 28C of the groove in the same manner as the first arm groove 27F of the first support arm 20F. The second arm groove 27S opens toward the right direction RD. In other words, the second arm groove 27S is exposed in the space between the first support arm 20F and the second support arm 20S.

[0152] The obliquely opening groove 28A is formed in the second support arm 20S so as to extend in the groove inclined direction 29A. Here, the groove inclined direction 29A is a direction from the arm upper surface 29T of the second support arm 20S toward the inside of the second support arm 20S. In other words, the groove inclined direction 29A is a direction inclined with respect to the extending direction 20E in which the second support arm 20S extends. The obliquely opening groove 28A opens toward the upper direction UD and the right direction RD on the arm upper surface 29T.

[0153] The obliquely opening groove 28A has two obliquely groove walls 28N1 and 28N2 opposed to each other. The width between the two obliquely groove walls 28N1 and 28N2 is slightly wider than the diameter of the left arm engaging portion 51R described later. Thus, the obliquely opening groove 28A enables the left arm engaging portion 51R to be inserted between the obliquely groove walls 28N1 and 28N2.

[0154] The front - rear extending groove 28B is formed in the second support arm 20S in such a manner as to be connected to the obliquely - opening groove 28A in the groove inclination direction 29A. The front - rear extending groove 28B extends in the extending direction 20E. The front - rear extending groove 28B opens toward the groove inclination direction 29A and the right direction RD.

[0155] The front - rear extending groove 28B has two extending groove walls 28M1, 28M2 that face each other. The extending groove wall 28M1 is the surface connected to the oblique groove wall 28N1. The extending groove wall 28M2 is the surface connected to the oblique groove wall 28N2.

[0156] The width between the two extending groove walls 28M1, 28M2 is slightly wider than the diameter of the left - arm engaging portion 51R described later. Thus, the front - rear extending groove 28B can allow the left - arm engaging portion 51R to be inserted between the extending groove walls 28M1, 28M2.

[0157] The inner part 28C of the groove is the part located at the rearmost of the front - rear extending groove 28B. In other words, the inner part 28C of the groove is the part at the end of the front - rear extending groove 28B in the groove extending direction 29B. The groove extending direction 29B is a direction parallel to the extending direction 20E. The inner part 28C of the groove opens toward the extending direction 20E and the right direction RD.

[0158] The inner part 28C of the groove has a curved surface. The curved surface of the inner part 28C of the groove has a shape along the surface shape of the left - arm engaging portion 51R.

[0159] The second arm groove 27S and the first arm groove 27F are in an axially - symmetric relationship with respect to the central axis CL (refer to Figure 1 ) that passes through the center of the chair 100 in the left - right direction RD, LD and extends in the front - rear direction FD, BD.

[0160] <Back - supporting part 21>

[0161] The back - supporting part 21 is located above the longitudinal arm 20A in the up - down direction UD, DD. The back - supporting part 21 is supported by the longitudinal arm 20A.

[0162] The back - supporting part 21 is arranged more rearward than the seat 1 in the rear direction BD. The back - supporting part 21 can tilt relative to the seat 1. The back - supporting part 21 has a back - supporting support part 21A and a back - supporting surface forming part 21B. The back - supporting support part 21A is fastened to the longitudinal arm 20A using fastening members such as bolts (not shown). Thus, the back - supporting support part 21A is supported by the arm part 20. The back - supporting part 21 extends in the up - down direction UD, DD and can tilt in the up - down direction UD, DD in linkage with the rotation of the arm part 20. The material of the tensile material forming the back - supporting surface forming part 21B is, for example, cloth such as a net.

[0163] In addition, the backrest bearing portion 21A can also be integrally formed with the longitudinal arm 20A. A known cushioning member covered with cloth can also be installed on the backrest bearing surface forming portion 21B. The backrest bearing surface forming portion 21B can also be covered with cloth.

[0164] <Elastic member 23>

[0165] It is supported on the lower surface 4L of the seat plate of the seat 1. The elastic member 23 is, for example, a known leaf spring. As Figure 5B shown, when observed in the right direction RD, the elastic member 23 is formed in a substantially L-shape. The elastic member 23 has a longitudinal spring portion 23A and a transverse spring portion 23B. As the spring structure constituting the elastic member 23, it is not limited to a leaf spring. Known springs other than leaf springs can be applied to the elastic member 23. The longitudinal spring portion 23A is an example of the "first end portion". The transverse spring portion 23B is an example of the "second end portion". The longitudinal spring portion 23A is the portion connected to the longitudinal arm 20A of the backrest 2. The transverse spring portion 23B is the portion connected to the lower surface 4L of the seat plate of the seat 1. The transverse spring portion 23B is located in a more forward direction FD than the longitudinal spring portion 23A in the front-rear direction FD, BD.

[0166] In addition, in the present embodiment, the longitudinal spring portion 23A constituting the "first end portion" is arranged above the transverse spring portion 23B constituting the "second end portion" in the up-down direction UD, DD. The longitudinal spring portion 23A can also be arranged below the transverse spring portion 23B in the up-down direction UD, DD. In this case, it is preferable that the longitudinal spring portion 23A is supported on a portion of the backrest 2 that is lower than the seat 1.

[0167] The longitudinal spring portion 23A of the elastic member 23 is located at the upper end 23U of the elastic member 23 in the up-down direction UD, DD. The transverse spring portion 23B of the elastic member 23 is located at the front end 23L of the elastic member 23 in the front-rear direction FD, BD. The elastic member 23 has a bent portion 23C located between the longitudinal spring portion 23A and the transverse spring portion 23B.

[0168] A first end hole 23H1 is provided in the longitudinal spring portion 23A. The first end hole 23H1 is a hole through which a fastening member such as a bolt (not shown) passes. The longitudinal spring portion 23A is fastened to the longitudinal arm 20A by the fastening member passing through the first end hole 23H1. A second end hole 23H2 is provided in the transverse spring portion 23B. The second end hole 23H2 is a hole through which a seat bearing fastening member passes. The transverse spring portion 23B is fastened to the seat bearing member 40 by the seat bearing fastening member passing through the second end hole 23H2.

[0169] The bent portion 23C has an upper extension portion 23D connected to the longitudinal spring portion 23A and a front extension portion 23E connected to the transverse spring portion 23B. When viewed in the leftward direction LD, the upper extension portion 23D and the front extension portion 23E are connected in a shape forming an L. Further, in the up-down direction UD, DD, when the longitudinal spring portion 23A is located below the transverse spring portion 23B, the portion of the bent portion 23C connected to the longitudinal spring portion 23A preferably extends downward.

[0170] The elastic member 23 has an upper region portion 23F and a front region portion 23G. The upper region portion 23F is located between the longitudinal spring portion 23A and the upper extension portion 23D. The upper region portion 23F extends along the upward direction UD. The front region portion 23G is located between the transverse spring portion 23B and the front extension portion 23E. The front region portion 23G extends along the forward direction FD. At least one of the upper region portion 23F and the front region portion 23G may be formed in a straight line shape.

[0171] The upper region portion 23F is formed in a straight line shape so as to extend along the upward direction UD or in a direction inclined with respect to the upward direction UD. The front region portion 23G is formed in a straight line shape so as to extend along the forward direction FD or in a direction inclined with respect to the forward direction FD.

[0172] In the present embodiment, the shapes of the upper region portion 23F and the front region portion 23G are both straight line shapes. As a modification example, only the upper region portion 23F may be formed in a straight line shape. Additionally, only the front region portion 23G may be formed in a straight line shape.

[0173] The elastic member 23 having the above structure elastically deforms in the up-down direction UD, DD and the front-rear direction FD, BD by the rotation of the backrest 2. The elastic member 23 is a member that applies the restoring force caused by the elastic deformation to the seat 1 and the backrest 2 to return the seat 1 and the backrest 2 to the front limit position 81. Here, the elastic deformation generated in the elastic member 23 means that the elastic member 23 elastically deforms by the action of the force applied to the elastic member 23. This will be specifically described.

[0174] The state of the chair 100 where the seated person does not press the backrest 2 with the back is set as the initial state.

[0175] The state of the chair 100 where the seated person presses the backrest 2 with the back is set as the tilting state.

[0176] "The elastic member 23 elastically deforms" means that the elastic member 23 elastically deforms in the process of the state of the chair 100 changing from the initial state to the tilting state.

[0177] Here, in a state where the elastic member 23 is assembled to the chair 100, that is, in the initial state, elastic deformation can also be pre-generated in the elastic member 23. In other words, in a state where the elastic member 23 is assembled to the chair 100, the elastic member 23 can also apply a restoring force (initial reaction force) to the members constituting the chair 100.

[0178] <Elastic member support portion 24>

[0179] The elastic member support portion 24 is a member that fixes the longitudinal spring portion 23A to the back surface 21C of the backrest support portion 21A. The elastic member support portion 24 uses fastening members such as bolts (not shown) to fasten the longitudinal spring portion 23A to the back surface 21C of the backrest support portion 21A.

[0180] <Backrest cover 25>

[0181] The backrest cover 25 is fixed to the longitudinal arm 20A so as to cover the elastic member support portion 24 and the longitudinal spring portion 23A. Thus, the elastic member support portion 24 and the longitudinal spring portion 23A are not exposed to the outside of the chair 100. By fastening the backrest cover 25 to the longitudinal arm 20A, the design of the chair 100 is improved.

[0182] <Support structure 3>

[0183] As Figure 1 shown, the support structure 3 supports the lower surface 4L of the seat plate of the seat 1 and the backrest 2. Thus, the support structure 3 supports the chair 100 on the ground FS. In the present embodiment, the support structure 3 supports the seat 1 via the lower surface 4L of the seat plate, but the support structure 3 may also support the seat 1 via a portion other than the lower surface 4L of the seat plate. For example, the support structure 3 may also support the seat 1 via the side surface of the seat 1 in the left - right directions RD, LD.

[0184] The support structure 3 has legs 30 and a shaft support mechanism 50.

[0185] <Legs 30>

[0186] As Figure 1 shown, the legs 30 are provided on the ground FS.

[0187] The legs 30 have multiple legs 31 with a plurality of casters 31a and a leg post 33 that stands up from the central portion of the multiple legs 31 and houses a gas spring 32 as a lifting mechanism. The leg post 33 has an inner cylinder 34 and an outer cylinder 35. The outer cylinder 35 is fitted and supported by the multiple legs 31 in a non - rotatable manner. The lower portion of the inner cylinder 34 can rotate about an axis parallel to the up - down directions UD, DD. In other words, the lower portion of the inner cylinder 34 is supported so as to be able to rotate relative to the outer cylinder 35. The upper portion of the inner cylinder 34 is fixed to the support 60 that constitutes the shaft support mechanism 50.

[0188] As the gas spring 32, a well-known gas spring is used. The gas spring 32 has, for example, a cylinder 32A, a piston 32B, and a locking mechanism 32C. Compressed gas is filled in the cylinder 32A. The piston 32B can move in the cylinder 32A in the up-and-down directions UD and DD. The locking mechanism 32C is a mechanism that fixes the position of the piston 32B in the up-and-down directions UD and DD or releases the fixed state of the position of the piston 32B. Specifically, the locking mechanism 32C has a locking release protrusion 32D that protrudes from the gas spring 32 in the upward direction UD. As Figure 4 shown, the locking release protrusion 32D is in slidable contact with the pressing force generating portion 12G of the pressing portion 12.

[0189] <Specific structure of the seat bearing member 40>

[0190] The seat bearing member 40 is a member that supports the seat main body 4, the first shaft portion 71, and the second shaft portion 72.

[0191] As Figure 2 , Figure 5A , Figure 7 , Figure 8 , Figure 12 and Figure 13 shown, the seat bearing member 40 is received in the support mechanism receiving portion 6 under the seat plate 4L. The size of the support mechanism receiving portion 6 in the front-rear direction FD, BD and the left-right direction RD, LD, that is, the horizontal direction, is set according to the size of the seat bearing member 40. The depth 6D of the support mechanism receiving portion 6 is set to be greater than the height 40H of the seat bearing member 40 in the up-and-down directions UD, DD.

[0192] In other words, the support mechanism receiving portion 6 can receive the seat bearing member 40 inside the support mechanism receiving portion 6. When viewed in the left-right direction RD, LD, the seat bearing member 40 overlaps with the seat main body 4.

[0193] The seat bearing member 40 is composed of a first seat bearing member 41 and a second seat bearing member 42.

[0194] The first seat bearing member 41 and the second seat bearing member 42 are each composed of a metal plate. For example, the first seat bearing member 41 and the second seat bearing member 42 are respectively formed by well-known sheet metal processing. As long as it is composed of a strength member having sufficient strength to support a sitter sitting on the seat 1, the type of material forming the seat bearing member 40 or the thickness of the metal plate is not particularly limited.

[0195] <First seat bearing member 41>

[0196] The first seat bearing member 41 has a first plate main body 41A, a first right plate portion 41B, and a first left plate portion 41C.

[0197] The first seat-bearing body 41A extends parallel to the front-rear direction FD, BD, or a direction inclined with respect to the front-rear direction FD, BD. The first seat-bearing body 41A is connected to the first right plate portion 41B and the first left plate portion 41C in the left-right direction RD, LD. Four through holes 41D are provided in the first seat-bearing body 41A. The positions of the four through holes 41D in the first seat-bearing body 41A correspond one-to-one with the positions of the four seat-bearing fastening holes 6B formed in the support recess surface 6A. Using fastening members such as bolts (not shown), the first seat-bearing body 41A is fastened to the support mechanism housing portion 6 and fixed to the seat body 4.

[0198] As a fixing structure for fixing the first seat-bearing member 41 to the seat body 4, for example, a known fixing structure using screws is adopted. In addition, the fixing structure is not limited to screw fixing.

[0199] The first right plate portion 41B is a portion that extends downward in the DD direction from the right end portion 41E of the first seat-bearing body 41A in the right direction RD. A first right front hole 41G and a first right rear hole 41H are formed in the first right plate portion 41B. In the front-rear direction FD, BD, the first right front hole 41G is a hole provided at a position more forward than the first right rear hole 41H. In other words, in the front-rear direction FD, BD, the first right rear hole 41H is a hole provided at a position more rearward than the first right front hole 41G.

[0200] The first left plate portion 41C is a portion that extends downward in the DD direction from the left end portion 41F of the first seat-bearing body 41A in the left direction LD. A first left front hole 41I and a first left rear hole 41J are formed in the first left plate portion 41C. In the front-rear direction FD, BD, the first left front hole 41I is a hole provided at a position more forward than the first left rear hole 41J. In other words, in the front-rear direction FD, BD, the first left rear hole 41J is a hole provided at a position more rearward than the first left front hole 41I.

[0201] A first seat-bearing space 41K is formed between the first right plate portion 41B and the first left plate portion 41C in the left-right direction RD, LD. In other words, the first seat-bearing member 41 is formed in a substantially C-shaped form that opens downward in the DD direction. A second seat-bearing member 42 is disposed in the first seat-bearing space 41K. The distance between the first right plate portion 41B and the first left plate portion 41C in the left-right direction RD, LD is greater than the distance between the second right plate portion 42B and the second left plate portion 42C of the second seat-bearing member 42.

[0202] <Second seat-bearing member 42>

[0203] The second seat-bearing member 42 has a second plate body 42A, a second right plate portion 42B, and a second left plate portion 42C.

[0204] The second plate body 42A extends parallel to the front-rear direction FD, BD, or a direction inclined with respect to the front-rear direction FD, BD. The second plate body 42A is connected to the second right plate portion 42B and the second left plate portion 42C in the left-right direction RD, LD. The second plate body 42A is fixed to the elastic member 23 using fastening members such as bolts (not shown). An arm fixing hole 42K is formed in the second plate body 42A. The arm fixing hole 42K is a threaded hole for fixing the lateral spring portion 23B of the elastic member 23 to the seat receiving member 40.

[0205] The second right plate portion 42B is a portion that extends upward in the up direction UD from the right end portion 42E of the second plate body 42A in the right direction RD. A second right front hole 42G and a second right rear hole 42H are formed in the second right plate portion 42B. In the front-rear direction FD, BD, the second right front hole 42G is a hole provided at a position more forward than the second right rear hole 42H. In other words, in the front-rear direction FD, BD, the second right rear hole 42H is a hole provided at a position more rearward than the second right front hole 42G.

[0206] The second left plate portion 42C is a portion that extends upward in the up direction UD from the left end portion 42F of the second plate body 42A in the left direction LD. A second left front hole 42I and a second left rear hole 42J are formed in the second left plate portion 42C. In the front-rear direction FD, BD, the second left front hole 42I is a hole provided at a position more forward than the second left rear hole 42J. In other words, in the front-rear direction FD, BD, the second left rear hole 42J is a hole provided at a position more rearward than the second left front hole 42I.

[0207] A second seat receiving space 42L is formed between the second right plate portion 42B and the second left plate portion 42C in the left-right direction RD, LD. In other words, the second seat receiving space 42L is formed in a substantially C-shaped configuration that opens upward in the up direction UD.

[0208] As Figure 12 and Figure 13 shown, the seat receiving member 40 is constituted by combining the first seat receiving member 41 and the second seat receiving member 42 in such a manner that the first plate body 41A and the second plate body 42A face each other. In this configuration, the front ends of the second right plate portion 42B and the second left plate portion 42C come into contact with the first plate body 41A, thereby defining a gap between the first seat receiving member 41 and the second seat receiving member 42. This gap is an elastic member insertion hole 43 into which the lateral spring portion 23B of the elastic member 23 is inserted. In other words, the elastic member insertion hole 43 is a hole that communicates with a space common to the first seat receiving space 41K and the second seat receiving space 42L. The elastic member 23 inserted through the elastic member insertion hole 43 into the interior of the seat receiving member 40 reaches the second seat receiving space 42L and is fixed to the second plate body 42A.

[0209] With the lateral spring portion 23B inserted into the elastic member insertion hole 43, the seat bearing fastening member 44 passes through the second end hole 23H2 of the lateral spring portion 23B and is threadedly fastened to the arm fixing hole 42K. Thus, the lateral spring portion 23B is connected to the second seat bearing member 42. The seat bearing fastening member 44 is, for example, a known bolt.

[0210] In the present embodiment, as an example, an attachment structure is adopted in which the lateral spring portion 23B is connected to the seat bearing member 40 by the seat bearing fastening member 44. As long as the lateral spring portion 23B can be connected to the seat bearing member 40, the attachment structure is not limited to Figure 12 and Figure 13 the structure shown. The position where the attachment structure is provided on the seat bearing member 40 is not limited.

[0211] <Shaft support mechanism 50>

[0212] As shown in Figure 1 、 Figure 4 、 Figure 5A and Figures 9 - 11 the shaft support mechanism 50 includes a seat support shaft portion 50A, a back support shaft portion 50B, a position conversion mechanism 50C, a support 60, a support cover 65, and a rotation restricting pin 75.

[0213] The seat support shaft portion 50A supports the seat 1 so that the seat 1 can move relative to the front - rear directions FD, BD. The back support shaft portion 50B extends in the left - right directions RD, LD and supports the backrest 2 so that it can rotate. The position conversion mechanism 50C is supported so that it can rotate relative to the seat support shaft portion 50A and the back support shaft portion 50B. The position conversion mechanism 50C is configured to convert the displacement of the position of the backrest 2 caused by the rotation of the backrest 2 into the displacement of the position of the seat 1.

[0214] The position conversion mechanism 50C mechanically connects the backrest 2 and the seat 1. As long as the position conversion mechanism 50C is configured to convert the displacement of the position of the backrest 2 caused by the rotation of the backrest 2 into the displacement of the position of the seat 1, the structure of the position conversion mechanism 50C is not limited to the present embodiment.

[0215] The seat support shaft portion 50A has a first shaft portion 71 that supports the seat 1 so that it can rotate and a second shaft portion 72 that supports the seat 1 so that it can rotate.

[0216] The back support shaft portion 50B is located below the first shaft portion 71 in the up - down directions UD, DD. The back support shaft portion 50B is a third shaft portion 73 that supports the backrest 2 so that it can rotate.

[0217] The position conversion mechanism 50C includes a fourth shaft portion 74, a support connector 51, and a support link 55. The fourth shaft portion 74 is located below the second shaft portion 72 in the up-down direction UD, DD. The support connector 51 is rotatably supported by the first shaft portion 71, rotatably supported by the third shaft portion 73, and connected to the backrest 2. The support link 55 is rotatably supported by the second shaft portion 72 and rotatably supported by the fourth shaft portion 74. The support connector 51 and the support link 55 are configured to return the seat 1 and the backrest 2 to the front limit position 81 by the restoring force of the elastic member 23.

[0218] The support connector 51 and the support link 55 are each formed of a metal plate. For example, the support connector 51 and the support link 55 are respectively formed by known sheet metal processing. As long as they are formed of strength members having sufficient strength to support the sitter sitting on the seat 1, the type of material forming the support connector 51 and the support link 55 or the thickness of the metal plate is not particularly limited.

[0219] <Support connector 51>

[0220] As Figure 9 、 Figure 12 and Figure 13 shown, the support connector 51 has a connector connection plate portion 51A, a connector right plate portion 51B, and a connector left plate portion 51C.

[0221] The connector connection plate portion 51A extends parallel to the up-down direction UD, DD or a direction inclined with respect to the up-down direction UD, DD. The connector connection plate portion 51A is connected to the connector right plate portion 51B and the connector left plate portion 51C in the left-right direction RD, LD.

[0222] The support connector 51 is rotatably supported by the first shaft portion 71 and the third shaft portion 73, respectively. The support connector 51 supports the arm portion 20. The support connector 51 can be detached from and attached to the arm portion 20. The support connector 51 is an example of an "arm support portion".

[0223] The connector right plate portion 51B is a portion extending forward in the forward direction FD from the right end portion 52 of the connector connection plate portion 51A in the right direction RD. The connector right plate portion 51B has an upper right plate portion 51D, a lower right plate portion 51E, and a right connection plate portion 51F. The right connection plate portion 51F connects the upper right plate portion 51D and the lower right plate portion 51E. In the up-down direction UD, DD, the upper right plate portion 51D is located above the lower right plate portion 51E. A connector upper right hole 51G is formed in the upper right plate portion 51D. A connector lower right hole 51H is formed in the lower right plate portion 51E. The upper right plate portion 51D is a portion that is rotatably supported by the first shaft portion 71 and is an example of a "first connector support portion". The lower right plate portion 51E is a portion that is rotatably supported by the third shaft portion 73 and is an example of a "second connector support portion".

[0224] An arm engaging portion 51J that protrudes in the right direction RD from the right outer side surface 51I of the connector right plate portion 51B is formed in the connector right plate portion 51B. The arm engaging portion 51J has a circular shape in a cross section orthogonal to the left-right direction RD, LD. The arm engaging portion 51J is an example of an "arm engaging portion". The arm engaging portion 51J is a portion that engages with the first arm groove 27F of the first support arm 20F when connecting the support connector 51 and the first support arm 20F.

[0225] In addition, the lower right plate portion 51E has a right long hole 51K. The right long hole 51K is located between the connector connection plate portion 51A and the connector lower right hole 51H in the front-rear direction FD, BD. The right long hole 51K extends in the up-down direction UD, DD or in a direction inclined with respect to the up-down direction UD, DD. The right long hole 51K is a portion into which the rotation restricting pin 75 is inserted.

[0226] The connector left plate portion 51C is a portion extending forward in the forward direction FD from the left end portion 53 of the connector connection plate portion 51A in the left direction LD. The connector left plate portion 51C has an upper left plate portion 51L, a lower left plate portion 51M, and a left connection plate portion 51N. The left connection plate portion 51N connects the upper left plate portion 51L and the lower left plate portion 51M. In the up-down direction UD, DD, the upper left plate portion 51L is located above the lower left plate portion 51M. A connector upper left hole 51O is formed in the upper left plate portion 51L. A connector lower left hole 51P is formed in the lower left plate portion 51M. The upper left plate portion 51L is a portion that is rotatably supported by the first shaft portion 71 and is an example of a "first connector support portion". The lower left plate portion 51M is a portion that is rotatably supported by the third shaft portion 73 and is an example of a "second connector support portion".

[0227] On the left plate portion 51C of the connector, an arm engaging portion 51R is formed which protrudes in the left direction LD from the left outer side surface 51Q of the left plate portion 51C of the connector. The arm engaging portion 51R has a circular shape in a cross-section orthogonal to the left-right direction RD and LD. The arm engaging portion 51R is an example of the "arm engaging portion". The arm engaging portion 51R is a portion that engages with the second arm groove 27S of the second support arm 20S when connecting the support connector 51 and the second support arm 20S.

[0228] In addition, a left elongated hole 51S is formed in the lower left plate portion 51M. The left elongated hole 51S is located between the connector connecting plate portion 51A and the connector lower left hole 51P in the front-back direction FD and BD. The left elongated hole 51S extends in the up-down direction UD and DD or in a direction inclined with respect to the up-down direction UD and DD. The left elongated hole 51S is a portion into which the rotation restricting pin 75 is inserted.

[0229] The support connector 51 has a cutout portion 51X formed between the upper right plate portion 51D and the lower right plate portion 51E. Similarly, a cutout portion 51Y is formed between the upper left plate portion 51L and the lower left plate portion 51M. The cutout portions 51X and 51Y are formed in a substantially U-shaped configuration when viewed in the left-right direction RD and LD.

[0230] A connector space 51T is formed between the connector right plate portion 51B and the connector left plate portion 51C in the left-right direction RD and LD. Inside the connector space 51T, a first seat bearing member 41, a second seat bearing member 42, a support link 55, and a support 60 are arranged. The distance between the connector right plate portion 51B and the connector left plate portion 51C in the left-right direction RD and LD is greater than the distance between the first right plate portion 41B and the first left plate portion 41C of the first seat bearing member 41.

[0231] <Support link 55>

[0232] As Figure 12 and Figure 13 shown, the shaft support mechanism 50 has two support links 55. Specifically, the shaft support mechanism 50 has a right support link 56 located on the right side and a left support link 57 located on the left side in the left-right direction RD and LD. The right support link 56 and the left support link 57 are portions parallel to the up-down direction UD and DD or a direction inclined with respect to the up-down direction UD and DD.

[0233] The right support link 56 extends parallel to the vertical direction UD, DD or a direction inclined with respect to the vertical direction UD, DD. A link upper right hole 56U and a link lower right hole 56L are formed in the right support link 56. In the vertical direction UD, DD, the link upper right hole 56U is located above the link lower right hole 56L. The link upper right hole 56U is a part supported to be rotatable relative to the second shaft portion 72 and is an example of the "first link support portion". The link lower right hole 56L is a part supported to be rotatable relative to the fourth shaft portion 74 and is an example of the "second link support portion".

[0234] The left support link 57 extends parallel to the vertical direction UD, DD or a direction inclined with respect to the vertical direction UD, DD. A link upper left hole 57U and a link lower left hole 57L are formed in the left support link 57. In the vertical direction UD, DD, the link upper left hole 57U is located above the link lower left hole 57L. The link upper left hole 57U is a part supported to be rotatable relative to the second shaft portion 72 and is an example of the "first link support portion". The link lower left hole 57L is a part supported to be rotatable relative to the fourth shaft portion 74 and is an example of the "second link support portion".

[0235] <Support 60>

[0236] As Figure 10 、 Figure 12 And Figure 13 As shown, the support 60 has a box shape provided at the upper part of the leg 30. Specifically, the box shape of the support 60 extends parallel to the front - rear direction FD, BD or a direction inclined with respect to the front - rear direction FD, BD, has a width in the left - right direction RD, LD, and has a thickness in the vertical direction UD, DD. The support 60 supports the third shaft portion 73 and the fourth shaft portion 74 in a state of being provided at the upper part of the leg 30.

[0237] In the vertical direction UD, DD, the support 60 has a support lower surface 61 and a support upper surface 62. The support lower surface 61 forms the lower surface of the box shape. The support upper surface 62 forms the upper surface of the box shape.

[0238] In the left - right direction RD, LD, the support 60 has a support right side portion 63 and a support left side portion 64. The support right side portion 63 and the support left side portion 64 form two side surfaces of the box shape.

[0239] The support lower surface 61 extends parallel to a direction inclined with respect to the front - rear direction FD, BD. The support lower surface 61 is connected to the support right side portion 63 and the support left side portion 64. A leg connection portion 61A for connecting the outer cylinder 35 of the leg 30 is provided on the support lower surface 61. In other words, the support 60 is supported by the leg 30 via the leg connection portion 61A.

[0240] On the upper surface 62 of the support, a support opening 62A that opens upward in the upward direction UD is formed. A support cover 65 is disposed on the upper surface 62 of the support so as to cover the support opening 62A.

[0241] On the right side portion 63 of the support, a right link support portion 63A is formed. On the right side portion 63 of the support, a right front hole 63B, a right rear hole 63C, and a right central hole 63D of the support are formed. The right rear hole 63C of the support is formed in the right link support portion 63A. The right link support portion 63A is a portion that is recessed leftward in the left direction LD from the right side portion 63 of the support. The right link support portion 63A opens in the upward direction UD, the rear direction BD, and the right direction RD. That is, the right link support portion 63A is a concave portion that houses a part of the right support link 56 in such a manner that the right link support portion 63A can tilt in the rear direction BD. For example, in a state where the right support link 56 is supported by the right link support portion 63A, a configuration in which the right support link 56 does not protrude from the right side portion 63 of the support in the right direction RD may also be employed.

[0242] In the front-rear direction FD, BD, the right central hole 63D of the support is located between the right front hole 63B and the right rear hole 63C of the support. The right front hole 63B of the support is a portion that supports the third shaft portion 73 so as to be rotatable. The right rear hole 63C of the support is a portion that supports the fourth shaft portion 74 so as to be rotatable. The right central hole 63D of the support is a portion that supports the rotation restricting pin 75.

[0243] On the left side portion 64 of the support, a left link support portion 64A is formed. On the left side portion 64 of the support, a left front hole 64B, a left rear hole 64C, and a left central hole 64D of the support are formed. The left rear hole 64C of the support is formed in the left link support portion 64A. The left link support portion 64A is a portion that is recessed rightward in the right direction RD from the left side portion 64 of the support. The left link support portion 64A opens in the upward direction UD, the rear direction BD, and the left direction LD. That is, the left link support portion 64A is a concave portion that houses a part of the left support link 57 in such a manner that the left link support portion 64A can tilt in the rear direction BD. For example, in a state where the left support link 57 is supported by the left link support portion 64A, a configuration in which the left support link 57 does not protrude from the left side portion 64 of the support in the left direction LD may also be employed.

[0244] In other words, in the left-right direction RD, LD, the distance between the concave surface of the right link support portion 63A that faces the right direction RD and the concave surface of the left link support portion 64A that faces the left direction LD is smaller than the distance between the right side portion 63 and the left side portion 64 of the support.

[0245] In the front-rear directions FD, BD, the left central hole 64D of the support is located between the left front hole 64B and the left rear hole 64C of the support. The left front hole 64B of the support is a portion that supports the third shaft portion 73 so as to be rotatable. The left rear hole 64C of the support is a portion that supports the fourth shaft portion 74 so as to be rotatable. The left central hole 64D of the support is a portion that supports the rotation restricting pin 75.

[0246] An axial support mechanism 50 for the leg column 33 is built inside the support 60.

[0247] Moreover, as Figure 4 shown, a locking release protrusion 32D of the gas spring 32 and a part of a pressing main body 12A of the pressing portion 12 are located inside the support 60. Specifically, a pressing force generating portion 12G that constitutes the pressing portion 12 is located inside the support 60. In other words, inside the support 60, the locking release protrusion 32D and the pressing force generating portion 12G can slide relative to each other.

[0248] <Support cover 65>

[0249] As Figure 11 shown, the support cover 65 has a substantially plate-like shape. The support cover 65 is a component provided on the upper surface 62 of the support so as to cover the support opening 62A. The support cover 65 has a front cover portion 66 and a rear cover portion 67. According to the shapes of a right link support portion 63A and a left link support portion 64A formed on the support 60, the width of the rear cover portion 67 in the left-right directions RD, LD is smaller than the width of the front cover portion 66. The support cover 65 does not expose the internal structure of the support 60 externally.

[0250] A cover opening 68 and a mechanism support portion 69 are provided on the upper surface of the front cover portion 66. The cover opening 68 penetrates the front cover portion 66. The mechanism support portion 69 has a pressing main body support portion 69A, two side walls 69B, an outer tube fixing portion 69C, and an inner wire insertion portion 69D. The pressing main body support portion 69A is provided between the two side walls 69B. The pressing main body support portion 69A is a portion that supports a pressing support shaft 12B of the pressing portion 12.

[0251] That is to say, in a state where the support cover 65 is attached to the support 60, the support cover 65 supports the pressing portion 12 so as to be rotatable.

[0252] In a state where the pressing support shaft 12B is supported by the pressing main body support portion 69A, a part of the pressing portion 12 passes through the cover opening 68 and is exposed in a space above the front cover portion 66. When observed in the front-rear directions FD, BD, the pressing main body support portion 69A overlaps with the two side walls 69B. That is to say, when observed in the front-rear directions FD, BD, the two side walls 69B prevent the pressing main body support portion 69A from being exposed.

[0253] The outer tube fixing portion 69C is provided between the two side walls 69B. The outer tube fixing portion 69C is a portion that fixes the end of the outer tube 11A shown in Figure 4 . Thus, the state where the outer tube does not move from the seat cover 65 is maintained.

[0254] The inner wire insertion portion 69D is provided between the two side walls 69B. The inner wire insertion portion 69D is a concave portion or a hole portion through which the inner wire 11B passes. The inner wire 11B can move relative to the outer tube 11A through the inner wire insertion portion 69D.

[0255] That is to say, the seat cover 65 not only prevents the internal structure of the seat 60 from being exposed on the appearance, but also forms a part of the support mechanism for the wire structure body 11 and the pressing portion 12.

[0256] <The first shaft portion 71, the second shaft portion 72, the third shaft portion 73, the fourth shaft portion 74, and the rotation restricting pin 75>

[0257] As shown in Figure 5A , the first shaft portion 71, the second shaft portion 72, the third shaft portion 73, the fourth shaft portion 74, and the rotation restricting pin 75 extend along the left - right direction RD, LD respectively. Each of such shaft portions and pins is, for example, a shaft composed of a known solid rod - shaped member. A hole is formed at a portion rotatably connected to each of these four shaft portions. A bearing may also be disposed between each of the four shaft portions and the hole. Each of the four shaft portions is, for example, composed of a known metal rod. As long as it is composed of a strength member having sufficient strength to support the sitter sitting on the seat 1, the type of material forming each of the four shaft portions or the diameter of the metal rod is not particularly limited.

[0258] In the present embodiment, the case where the first shaft portion 71, the second shaft portion 72, the third shaft portion 73, the fourth shaft portion 74, and the rotation restricting pin 75 are each a solid rod - shaped member has been described. The above - mentioned shaft portions and pins are not limited to solid rod - shaped members. For example, a hollow rod - shaped member can also be applied to the above - mentioned shaft portions and pins.

[0259] <The specific structure of the shaft support mechanism 50>

[0260] Refer to Figure 5A , Figure 6 , Figure 9 , Figure 12 and Figure 13 to describe the specific structure and operation of the shaft support mechanism 50. In Figure 12 and Figure 13 , the seat receiving member 40 fixed to the seat 1 is shown, but the seat 1 is omitted. Figure 12 It shows the state where the backrest receiving portion 21 is located at the front limit position 81 within the tilting range 80 of the backrest receiving portion 21. Figure 13The figure shows a state where the back support portion 21 is located at the rear limit position 82 within the tilting range 80 of the back support portion 21 .

[0261] <Support Structure by First Shaft Portion 71>

[0262] In the direction in which the first shaft portion 71 extends, the upper left plate portion 51L of the supporting connector 51, the first left plate portion 41C of the first seat supporting component 41, the second left plate portion 42C of the second seat supporting component 42, the second right plate portion 42B of the second seat supporting component 42, the first right plate portion 41B of the first seat supporting component 41, and the upper right plate portion 51D of the supporting connector 51 are arranged in sequence from the upper left plate portion 51L of the supporting connector 51 toward the right direction RD.

[0263] Two adjacent members among the above-mentioned members supported by the first shaft portion 71 may be separated so as not to contact each other. For example, a spacer such as a resin may be disposed between the two members.

[0264] The first shaft portion 71 passes through the first right front hole 41G and the first left front hole 41I of the first seat receiving component 41, the second right front hole 42G and the second left front hole 42I of the second seat receiving component 42, and the connector upper right hole 51G and the connector upper left hole 51O of the supporting connector 51. In order to prevent the first shaft portion 71 from falling out of these six holes, for example, C-shaped rings may be engaged at both ends of the first shaft portion 71 in the left-right directions RD and LD. In addition, a large-diameter portion having a diameter larger than the diameters of the six holes may be provided at one end of the first shaft portion 71, and a C-shaped ring may be engaged with the other end of the first shaft portion 71. The structure for preventing the first shaft portion 71 from falling out is not particularly limited.

[0265] As a structure for preventing the first shaft portion 71 from falling off, for example, a structure using rivets can also be adopted. That is, one side of the first shaft portion 71 has a head, and the other side of the first shaft portion 71 has a straight portion. In this case, the diameter of the head is larger than the diameter of the hole through which the first shaft portion 71 is inserted. Specifically, after the straight portion of the first shaft portion 71 is passed through the hole, the straight portion is deformed by riveting (Japanese: 加締める). As a result, in the first shaft portion 71, a large diameter portion is formed on the side opposite to the head. The large diameter portion is larger than the diameter of the hole through which the first shaft portion 71 is inserted.

[0266] The first shaft portion 71 is a rod-shaped member that penetrates through the six holes described above. The first shaft portion 71 does not necessarily have to be a single rod-shaped member. The first shaft portion 71 may also be composed of a pair of shaft portions that share the same axis and are separated from each other. In this case, one of the pair of shaft portions penetrates through the first right front hole 41G of the first seat bearing member 41, the second right front hole 42G of the second seat bearing member 42, and the connector upper right hole 51G of the support connector 51. The other of the pair of shaft portions penetrates through the first left front hole 41I of the first seat bearing member 41, the second left front hole 42I of the second seat bearing member 42, and the connector upper left hole 51O of the support connector 51.

[0267] The first shaft portion 71 supports the seat bearing member 40 fixed to the seat 1 so as to be rotatable.

[0268] The first shaft portion 71 supports the support connector 51 so as to be rotatable independently of the seat bearing member 40. In other words, the seat bearing member 40 and the support connector 51 can rotate relative to the first shaft portion 71.

[0269] The first shaft portion 71 moves in the front-back directions FD, BD as the seat 1 moves in the front-back directions FD, BD.

[0270] <Support structure based on the second shaft portion 72>

[0271] In the direction in which the second shaft portion 72 extends, from the left support link 57 toward the right direction RD, the left support link 57, the first left plate portion 41C of the first seat bearing member 41, the second left plate portion 42C of the second seat bearing member 42, the second right plate portion 42B of the second seat bearing member 42, the first right plate portion 41B of the first seat bearing member 41, and the right support link 56 are arranged in sequence toward the right direction RD.

[0272] Two adjacent components among the components supported by the second shaft portion 72 may also be separated in a non-contact manner. For example, a spacer such as resin may be disposed between the two components.

[0273] The second shaft portion 72 penetrates through the first right rear hole 41H and the first left rear hole 41J of the first seat bearing member 41, the second right rear hole 42H and the second left rear hole 42J of the second seat bearing member 42, the link upper right hole 56U of the right support link 56, and the link upper left hole 57U of the left support link 57. In order to prevent the second shaft portion 72 from falling out of these six holes, for example, C-rings may be engaged with both ends of the second shaft portion 72 in the right-left directions RD, LD. Alternatively, a large-diameter portion having a diameter larger than the diameter of the six holes may be provided at one end of the second shaft portion 72, and the C-ring may be engaged with the other end of the second shaft portion 72. The structure for preventing the second shaft portion 72 from falling out is not particularly limited.

[0274] As a structure for preventing the second shaft portion 72 from falling off, for example, a structure using a rivet can also be adopted. That is, one side of the second shaft portion 72 has a head, and the other side of the second shaft portion 72 has a straight portion. In this case, the diameter of the head is larger than the diameter of the hole through which the second shaft portion 72 is inserted. Specifically, after passing the straight portion of the second shaft portion 72 through the hole, the straight portion is riveted to deform the straight portion. Thus, in the second shaft portion 72, a large-diameter portion is formed on the side opposite to the head. The large-diameter portion is larger than the diameter of the hole through which the second shaft portion 72 is inserted.

[0275] The second shaft portion 72 is a rod-shaped member that penetrates the above six holes. The second shaft portion 72 does not necessarily have to be a single rod-shaped member. The second shaft portion 72 can also be composed of a pair of shaft portions that share the same axis and are separated from each other. In this case, one of the pair of shaft portions penetrates the first right rear hole 41H of the first seat bearing member 41, the second right rear hole 42H of the second seat bearing member 42, and the link upper right hole 56U of the right support link 56. The other of the pair of shaft portions penetrates the first left rear hole 41J of the first seat bearing member 41, the second left rear hole 42J of the second seat bearing member 42, and the link upper left hole 57U of the left support link 57.

[0276] The second shaft portion 72 supports the seat bearing member 40 fixed to the seat 1 so as to be rotatable.

[0277] The second shaft portion 72 supports the support link 55 independently of the seat bearing member 40 so as to be rotatable. In other words, the seat bearing member 40 and the support link 55 can rotate relative to the second shaft portion 72.

[0278] The second shaft portion 72 moves in the front-back directions FD, BD as the seat 1 moves in the front-back directions FD, BD.

[0279] <Support structure based on the third shaft portion 73>

[0280] In the direction in which the third shaft portion 73 extends, the second support arm 20S, the lower left plate portion 51M of the support connector 51, the left side portion 64 of the support, the right side portion 63 of the support, the lower right plate portion 51E of the support connector 51, and the first support arm 20F are arranged in order from the second support arm 20S toward the right direction RD.

[0281] Two adjacent components among the above components supported by the third shaft portion 73 can also be separated from each other in a non-contact manner. For example, a spacer such as resin can be arranged between the two components.

[0282] The third shaft portion 73 is statically supported by the support 60.

[0283] The third shaft portion 73 penetrates through a first shaft support hole 26F of the first support arm 20F, a second shaft support hole 26S of the second support arm 20S, a connector lower right hole 51H and a connector lower left hole 51P of the support connector 51, and a support right front hole 63B and a support left front hole 64B of the support 60. The third shaft portion 73 is fastened to the first support arm 20F and the second support arm 20S using fastening members such as bolts (not shown).

[0284] The third shaft portion 73 is a rod-shaped member that penetrates through the above six holes. The third shaft portion 73 does not necessarily have to be a single rod-shaped member. The third shaft portion 73 may also be composed of a pair of shaft portions that share the same axis and are separated from each other. In this case, one of the pair of shaft portions penetrates through the first shaft support hole 26F of the first support arm 20F, the connector lower right hole 51H of the support connector 51, and the support right front hole 63B of the support 60. The other of the pair of shaft portions penetrates through the second shaft support hole 26S of the second support arm 20S, the connector lower left hole 51P of the support connector 51, and the support left front hole 64B of the support 60.

[0285] The third shaft portion 73 supports the support connector 51 and the cross arm 20B so as to be rotatable relative to the support 60. Thereby, the support connector 51 can tilt about the third shaft portion 73 relative to the front-rear direction FD, BD in a manner linked to the rotation of the arm portion 20.

[0286] Moreover, the third shaft portion 73 is located below the first shaft portion 71 in the up-down direction UD, DD.

[0287] <Support Structure Based on the Fourth Shaft Portion 74>

[0288] In the direction in which the fourth shaft portion 74 extends, from the left support link 57 toward the right direction RD, the left support link 57, the left link support portion 64A of the support 60, the right link support portion 63A of the support 60, and the right support link 56 are arranged in sequence toward the right direction RD.

[0289] Two adjacent components among the above components supported by the fourth shaft portion 74 may also be separated from each other in a non-contact manner. For example, a spacer such as resin may be disposed between the two components.

[0290] The fourth shaft portion 74 is statically supported by the support 60.

[0291] The fourth shaft portion 74 penetrates through the lower right connecting rod hole 56L of the right support connecting rod 56, the lower left connecting rod hole 57L of the left support connecting rod 57, the right rear support hole 63C of the support 60, and the left rear support hole 64C of the support 60. In order to prevent the fourth shaft portion 74 from falling out of these four holes, C-shaped rings, for example, can be engaged with both ends of the fourth shaft portion 74 in the left-right directions RD and LD. Additionally, a large-diameter portion having a diameter larger than the diameters of the four holes can be provided at one end of the fourth shaft portion 74, and a C-shaped ring can be engaged with the other end of the fourth shaft portion 74. The structure for preventing the fourth shaft portion 74 from falling out is not particularly limited.

[0292] As a structure for preventing the fourth shaft portion 74 from falling out, for example, a structure using a rivet can also be adopted. That is, one side of the fourth shaft portion 74 has a head, and the other side of the fourth shaft portion 74 has a straight portion. In this case, the diameter of the head is larger than the diameter of the hole through which the fourth shaft portion 74 passes. Specifically, after passing the straight portion of the fourth shaft portion 74 through the hole, the straight portion is riveted to cause the straight portion to deform. As a result, a large-diameter portion is formed on the fourth shaft portion 74 on the side opposite to the head. The large-diameter portion is larger than the diameter of the hole through which the fourth shaft portion 74 passes.

[0293] The fourth shaft portion 74 is a rod-shaped member that penetrates through the above four holes. The fourth shaft portion 74 does not necessarily have to be a single rod-shaped member. The fourth shaft portion 74 can also be composed of a pair of shaft portions that share the same axis and are separated from each other. In this case, one of the pair of shaft portions penetrates through the lower right connecting rod hole 56L of the right support connecting rod 56 and the right rear support hole 63C of the support 60. The other of the pair of shaft portions penetrates through the lower left connecting rod hole 57L of the left support connecting rod 57 and the left rear support hole 64C of the support 60.

[0294] The fourth shaft portion 74 supports the right support connecting rod 56 and the left support connecting rod 57 so as to be rotatable relative to the support 60. In other words, the support connecting rod 55 can rotate around the fourth shaft portion 74 so that the inclination deflection between the direction in which the support connecting rod 55 extends and the up-down directions UD and DD changes. Moreover, the fourth shaft portion 74 is located more rearward in the front-rear directions FD and BD than the third shaft portion 73.

[0295] <Rotation limiting pin 75>

[0296] The rotation limiting pin 75 is statically supported by the support 60. Specifically, the rotation limiting pin 75 passes through the right central hole 63D and the left central hole 64D of the support 60, the right elongated hole 51K of the connector right plate portion 51B, and the left elongated hole 51S of the connector left plate portion 51C. In order to prevent the rotation limiting pin 75 from falling out of these four holes, for example, C-shaped rings can be engaged with both ends of the rotation limiting pin 75 in the left-right directions RD and LD. Alternatively, a large-diameter portion having a diameter larger than the diameters of the four holes can be provided at one end of the rotation limiting pin 75, and the C-shaped ring can be engaged with the other end of the rotation limiting pin 75. The structure for preventing the rotation limiting pin 75 from falling out is not particularly limited. In the following description, the right elongated hole 51K and the left elongated hole 51S may sometimes be simply referred to as the elongated hole 51Z.

[0297] According to the shape of the elongated hole 51Z in the up-down directions UD and DD, the tilting range 80 of the back bearing portion 21 in the front-back directions FD and BD is defined. In other words, as the support connector 51 rotates, the position of the rotation limiting pin 75 relative to the elongated hole 51Z changes. For example, as Figure 12 shown, when the rotation limiting pin 75 is located at the lower part of the elongated hole 51Z, in the tilting range 80, the back bearing portion 21 is located at the front limit position 81. Conversely, as Figure 13 shown, when the rotation limiting pin 75 is located at the upper part of the elongated hole 51Z, in the tilting range 80, the back bearing portion 21 is located at the rear position. Thus, the tilting range 80 of the back bearing portion 21 is defined by the elongated hole 51Z.

[0298] <Combined structure of the support connector 51 and the arm portion 20>

[0299] As Figure 5A 、 Figure 6 and Figure 9 shown, the right arm engaging portion 51J of the support connector 51 is fitted into the first arm groove 27F of the first support arm 20F. Similarly, the left arm engaging portion 51R of the support connector 51 is fitted into the second arm groove 27S of the second support arm 20S. Thereby, the support connector 51 is connected to the arm portion 20.

[0300] In such a connection structure, the position of the first shaft support hole 26F coincides with the position of the lower right hole 51H of the connector, and the position of the second shaft support hole 26S coincides with the position of the lower left hole 51P of the connector.

[0301] <Method of combining the support connector 51 and the arm portion 20>

[0302] Next, with reference to Figure 6 、 Figure 14A and Figure 14B , a method of combining the arm portion 20 and the support connector 51 will be described. Figure 14A andFigure 14B corresponding to Figure 6 . In Figure 14A and Figure 14B In the example shown, the extending direction 20E in which the first support arm 20F extends is inclined with respect to the front-back direction FD, BD, but the extending direction 20E does not necessarily need to be inclined with respect to the front-back direction FD, BD. As long as the support connector 51 can be easily coupled to the arm portion 20, the extending direction 20E can be parallel to the front-back direction FD, BD or can be parallel to the up-down direction UD, DD.

[0303] First, as Figure 14A shown, the support connector 51 is inserted into the space between the first support arm 20F and the second support arm 20S, and the right arm engaging portion 51J is inserted into the oblique opening groove 28A of the first arm groove 27F, and the left arm engaging portion 51R is inserted into the oblique opening groove 28A of the second arm groove 27S.

[0304] The right arm engaging portion 51J moves in the oblique opening groove 28A of the first support arm 20F toward the groove inclination direction 29A. Inside the oblique opening groove 28A, the right arm engaging portion 51J faces the two oblique groove walls 28N1, 28N2 respectively and moves inside the oblique opening groove 28A. The right arm engaging portion 51J sometimes contacts the two oblique groove walls 28N1, 28N2 respectively. That is, the two oblique groove walls 28N1, 28N2 respectively guide the right arm engaging portion 51J, restrict the moving direction of the right arm engaging portion 51J, and cause the right arm engaging portion 51J to move toward the groove inclination direction 29A. After that, the right arm engaging portion 51J reaches the end of the oblique opening groove 28A in the groove inclination direction 29A, that is, the front-back extending groove 28B of the first support arm 20F.

[0305] At the same moment as the movement of the right arm engaging portion 51J in the oblique opening groove 28A, the left arm engaging portion 51R moves in the oblique opening groove 28A of the second support arm 20S toward the groove inclination direction 29A. Inside the oblique opening groove 28A, the left arm engaging portion 51R faces the two oblique groove walls 28N1, 28N2 respectively and moves inside the oblique opening groove 28A. The right arm engaging portion 51J sometimes contacts the two oblique groove walls 28N1, 28N2 respectively. That is, the two oblique groove walls 28N1, 28N2 respectively guide the left arm engaging portion 51R, restrict the moving direction of the left arm engaging portion 51R, and cause the left arm engaging portion 51R to move toward the groove inclination direction 29A. After that, the left arm engaging portion 51R reaches the end of the oblique opening groove 28A in the groove inclination direction 29A, that is, the front-back extending groove 28B of the second support arm 20S.

[0306] Next, the right arm engaging portion 51J moves in the front-rear extending groove 28B of the first support arm 20F in the groove extending direction 29B. Inside the front-rear extending groove 28B, the right arm engaging portion 51J faces the two extending groove walls 28M1 and 28M2 respectively and moves inside the front-rear extending groove 28B. The right arm engaging portion 51J sometimes contacts the two extending groove walls 28M1 and 28M2 respectively. That is to say, the two extending groove walls 28M1 and 28M2 guide the right arm engaging portion 51J respectively, restrict the moving direction of the right arm engaging portion 51J, and make the right arm engaging portion 51J move in the groove extending direction 29B. After that, the right arm engaging portion 51J reaches the end of the front-rear extending groove 28B in the groove extending direction 29B, that is, Figure 6 the groove inner part 28C of the first support arm 20F shown. In a state where the right arm engaging portion 51J contacts the groove inner part 28C of the first support arm 20F, the right arm engaging portion 51J is positioned with the first support arm 20F. In other words, the support connector 51 is connected to the first support arm 20F. In this state, the first shaft support hole 26F and the third shaft portion 73 of the first support arm 20F are fixed. Thereby, the first support arm 20F can rotate around the third shaft portion 73.

[0307] At the same time as the movement of the left arm engaging portion 51R in the front-rear extending groove 28B, the left arm engaging portion 51R moves in the front-rear extending groove 28B of the second support arm 20S in the groove extending direction 29B. Inside the front-rear extending groove 28B, the left arm engaging portion 51R faces the two extending groove walls 28M1 and 28M2 respectively and moves inside the front-rear extending groove 28B. The left arm engaging portion 51R sometimes contacts the two extending groove walls 28M1 and 28M2 respectively. That is to say, the two extending groove walls 28M1 and 28M2 guide the left arm engaging portion 51R respectively, restrict the moving direction of the left arm engaging portion 51R, and make the left arm engaging portion 51R move in the groove extending direction 29B. After that, the left arm engaging portion 51R reaches the end of the front-rear extending groove 28B in the groove extending direction 29B, that is, Figure 6 the groove inner part 28C of the second support arm 20S shown. In a state where the left arm engaging portion 51R contacts the groove inner part 28C of the second support arm 20S, the left arm engaging portion 51R is positioned with the second support arm 20S. In other words, the support connector 51 is connected to the second support arm 20S. In this state, the second shaft support hole 26S and the third shaft portion 73 of the second support arm 20S are fixed. Thereby, the second support arm 20S can rotate around the third shaft portion 73.

[0308] Thus, when the positional relationships of the arm portion 20 with respect to the front-back direction FD, BD and the up-down direction UD, DD of the support connector 51 are determined, the positional relationships of the elastic member support portion 24 integrated with the arm portion with respect to the front-back direction FD, BD and the up-down direction UD, DD of the seat receiving member 40 supported by the support connector 51 are determined. In this state, the elastic member 23 is connected to the elastic member support portion 24 and the seat receiving member 40. At this time, it is preferable to set the shape of the elastic member 23 in such a way that an initial reaction force is generated in the elastic member 23. For example, it is preferable to set the shape of the elastic member 23 in such a way that the angle formed between the longitudinal spring portion 23A and the lateral spring portion 23B, which is L-shaped in side view, changes.

[0309] In other words, in the state where the assembly of the arm portion 20 and the support connector 51 is completed, the elastic member 23 is attached to the arm portion 20. In this case, since deformation (initial reaction force) is generated in the elastic member 23, the elastic member 23 can be preferably attached to the arm portion 20.

[0310] By the above-described coupling method, the arm portion 20 having the first support arm 20F and the second support arm 20S can be connected to the support connector 51. Conversely, by releasing the fixed state of the first shaft support hole 26F and the second shaft support hole 26S with respect to the third shaft portion 73 and removing the right arm engaging portion 51J from the first arm groove 27F and the left arm engaging portion 51R from the second arm groove 27S, the support connector 51 can be removed from the arm portion 20.

[0311] That is, in the above-described coupling structure, the support connector 51 can be detached from and attached to the arm portion 20.

[0312] <Distance relationship among the first shaft portion 71, the second shaft portion 72, the third shaft portion 73, and the fourth shaft portion 74>

[0313] In the direction from the first shaft portion 71 toward the third shaft portion 73, the distance between the first shaft portion 71 and the third shaft portion 73 is defined as the first distance L1.

[0314] In the direction from the second shaft portion 72 toward the fourth shaft portion 74, the distance between the second shaft portion 72 and the fourth shaft portion 74 is defined as the second distance L2. Here, the first distance L1 is larger than the second distance L2.

[0315] <Positional relationship of the support link 55 with respect to the first shaft portion 71 and the third shaft portion 73>

[0316] The support link 55 having such a structure is located at a position more rearward than the first shaft portion 71 and the third shaft portion 73 in the front-back direction FD, BD. In other words, the support link 55 is located between the first shaft portion 71 and the back receiving portion 21, or between the third shaft portion 73 and the back receiving portion 21.

[0317] <Function of the elastic member 23 and the supporting structure 3>

[0318] In the chair 100 of the present embodiment, when the seated person sits on the seat 1 and the seated person presses the backrest 2 with the back in the rear direction BD, the longitudinal spring portion 23A of the elastic member 23 moves in the rear direction BD in conjunction with the movement of the backrest 2 in the rear direction BD, and the elastic member 23 is elastically deformed. At this time, in conjunction with the movement of the backrest 2 in the rear direction BD, the backrest 2 rotates relative to the back support shaft portion 50B. The position conversion mechanism 50C provided in the backrest 2 converts the displacement of the position of the backrest 2 caused by the rotation of the backrest 2 into the displacement of the position of the seat 1. The seat support shaft portion 50A supported by the position conversion mechanism 50C moves the seat 1 in the rear direction BD. The transverse spring portion 23B of the elastic member 23 connected to the seat 1 also moves in the rear direction BD in the same manner.

[0319] On the other hand, if the seated person stands up in the forward direction FD, the back of the seated person leaves the backrest 2. At this time, the longitudinal spring portion 23A of the elastic member 23 moves in the forward direction FD due to the restoring force of the elastically deformed elastic member 23. At this time, the backrest 2 rotates relative to the back support shaft portion 50B in conjunction with the movement of the backrest 2 in the forward direction FD. The position conversion mechanism 50C provided on the backrest 2 converts the displacement of the position of the backrest 2 caused by the rotation of the backrest 2 into the displacement of the position of the seat 1. The seat support shaft portion 50A supported by the position conversion mechanism 50C moves the seat 1 in the forward direction FD. The transverse spring portion 23B of the elastic member 23 connected to the seat 1 also moves in the forward direction FD in the same manner.

[0320] Next, the operation of the support structure 3 including the seat support shaft portion 50A, the back support shaft portion 50B, and the position conversion mechanism 50C will be described in detail.

[0321] When the seat occupant is seated on the seat 1, when the seat occupant presses the backrest 2 with his / her back in the rear direction BD, the longitudinal spring portion 23A of the elastic member 23 moves in the rear direction BD in conjunction with the movement of the backrest 2 in the rear direction BD, and the elastic member 23 is elastically deformed. At this time, in conjunction with the movement of the backrest 2 in the rear direction BD, the backrest 2 rotates around the third shaft portion 73 supported by the support 60. The support connector 51 connected to the backrest 2 rotates around the third shaft portion 73. The support connector 51 supporting the first shaft portion 71 moves the first shaft portion 71 in the rear direction BD. The first shaft portion 71 moves the seat 1 in the rear direction BD. As the seat 1 moves in the rear direction BD, the second shaft portion 72 supporting the seat 1 also moves in the rear direction BD. The support link 55 supporting the second shaft portion 72 rotates around the fourth shaft portion 74.

[0322] On the contrary, if the seated person gets up in the forward direction FD, the back of the seated person leaves the backrest 2. At this time, due to the restoring force of the elastically deformed elastic member 23, the longitudinal spring portion 23A of the elastic member 23 moves in the forward direction FD. At this time, in linkage with the movement of the backrest 2 in the forward direction FD, the backrest 2 rotates about the third shaft portion 73 supported by the support 60. The support connector 51 connected to the backrest 2 rotates about the third shaft portion 73. The support connector 51 supporting the first shaft portion 71 moves the first shaft portion 71 in the forward direction FD. The first shaft portion 71 moves the seat 1 in the forward direction FD. As the seat 1 is moved in the forward direction FD, the second shaft portion 72 supporting the seat 1 also moves in the forward direction FD. The support link 55 supporting the second shaft portion 72 rotates about the fourth shaft portion 74. Thus, the support connector 51 and the support link 55 return the seat 1 and the backrest 2 to the front limit position 81 by the restoring force of the elastic member 23.

[0323] In the chair 100 according to the present embodiment, the backrest 2 is not directly supported by the seat 1, and the position conversion mechanism 50C is interposed between the backrest 2 and the seat 1. In this way, by interposing the position conversion mechanism 50C between the backrest 2 and the seat 1, the displacement amount of the seat 1 linked to the rotation of the backrest 2 can be appropriately set. For example, the displacement amount of the seat 1 can be reduced relative to the displacement amount of the backrest 2, so that the elastic member 23 can be elastically deformed greatly in the up-down directions UD and DD.

[0324] In addition, since the displacement amount of the seat 1 linked to the rotation of the backrest 2 can be appropriately set, even if the backrest 2 is moved greatly in the front-back directions FD and BD, the movement amount of the seat 1 can be adjusted to be smaller than the movement amount of the backrest 2. Moreover, the elastic deformation amount of the elastic member 23 can be sufficiently ensured, and sufficient restoring force can be obtained. In addition, the elastic member 23 does not need to extend greatly in the forward direction FD, and the effect that the elastic member 23 does not need to extend in front of the support structure 3 can be obtained.

[0325] In the chair 100 according to the present embodiment, the above effects can be obtained by the support structure 3 having the first shaft portion 71, the second shaft portion 72, the third shaft portion 73, the fourth shaft portion 74, the support connector 51, the support link 55, and the support 60.

[0326] In the chair 100 according to the present embodiment, the elastic member 23 has a bent portion 23C located between the longitudinal spring portion 23A and the transverse spring portion 23B. A difference can be generated between the position of the longitudinal spring portion 23A and the position of the transverse spring portion 23B in the up-down directions UD and DD. Therefore, it is easy to mount the elastic member 23 on both the seat 1 and the backrest 2.

[0327] In the chair 100 according to the present embodiment, when the elastic member 23 undergoes elastic deformation, elastic deformation occurs at the bending portion 23C located between the longitudinal spring portion 23A and the transverse spring portion 23B. In other words, the elastic member 23 deforms in such a manner that the angle changes between the direction from the bending portion 23C toward the longitudinal spring portion 23A and the direction from the bending portion 23C toward the transverse spring portion 23B. Thereby, it is easy to flex the elastic member 23 in linkage with the displacement of the backrest 2. Therefore, the elastic member 23 can be flexed smoothly, and the restoring force can be stably obtained.

[0328] In the chair 100 according to the present embodiment, in the vertical directions UD and DD, the longitudinal spring portion 23A is located above the transverse spring portion 23B. Therefore, when the bending portion 23C bends as the backrest 2 is displaced rearward and downward, the upper extension portion 23D is more likely to deform rearward in the direction BD by an amount corresponding to the length of the upper extension portion 23D compared to the front extension portion 23E. Therefore, the elastic member 23 can be flexed smoothly, and the restoring force can be stably obtained.

[0329] In the chair 100 according to the present embodiment, at least one of the upper region portion 23F and the front region portion 23G is formed in a linear shape. Therefore, for the region portion formed in a linear shape, it is easy to deform by an amount corresponding to the length of the region portion. Therefore, the elastic member 23 can be flexed smoothly, and the restoring force can be stably obtained.

[0330] In the chair 100 according to the present embodiment, a structure in which the elastic member 23 is connected to the seat receiving member 40 can be obtained. The seat receiving member 40 is connected to the backrest 2 via the support structure 3. In the operation of assembling the components constituting the chair 100, an operation such as first connecting the elastic member 23 and the seat receiving member 40 to each other and then housing the seat receiving member 40 in the seat main body 4 can be performed. Thereby, the assembly operation can be simply performed.

[0331] <Method of adjusting the height of the seat 1 using the operating mechanism 5>

[0332] Next, a method of adjusting the height of the seat 1 using the operating mechanism 5 will be described.

[0333] The method of adjusting the height of the seat 1 is performed through the following steps.

[0334] [1] Step 1: By rotating the rod 10D by the seated person, the locked state of the gas spring 32 is released.

[0335] [2] Step 2: Lowering of the seat in the downward direction DD or raising of the seat in the upward direction UD

[0336] [3] Step 3: Lowering of the seat in the downward direction DD or raising of the seat in the upward direction UD

[0337] Next, Steps 1 to 3 described above will be sequentially described.

[0338] <Step 1>

[0339] First, in the initial state of the chair 100, the position of the seat 1 is fixed. Specifically, in the gas spring 32 that constitutes the chair 100, the lock release protrusion 32D is not pressed. Therefore, the locking mechanism 32C fixes the position of the piston 32B in the vertical directions UD and DD, that is, the position of the seat 1 is fixed. In this state, Step 1 is performed.

[0340] While being seated on the chair 100, the seated person uses a finger to move the lever 10D shown in Figure 3 the rotational operation direction 85. As a result, the lever 10D rotates around the lever support shaft 10A, and the wire support portion 10C of the lever plate 10B rotates in the rotational operation direction 85. At this time, a moment based on the lever principle is generated, and a force larger than the force applied by the seated person to the lever 10D acts on the wire support portion 10C. This force acts on the first wire engagement end 11F connected to the wire support portion 10C and the inner wire 11B connected to the first wire engagement end 11F, and the inner wire 11B moves in the stretching direction 86.

[0341] As Figure 4 shown, as the inner wire 11B moves, the second wire engagement end 11S connected to the inner wire 11B moves in the stretching direction 86. Further, the pressing engagement portion 12C engaged with the second wire engagement end 11S moves in the stretching direction 86. As a result, the pressing force generation portion 12G rotates around the pressing support shaft 12B in the rotational pressing direction 87. At this time, a moment based on the lever principle is generated, and a force larger than the tensile force applied to the inner wire 11B in the stretching direction 86 acts on the pressing force generation portion 12G. This force presses the lock release protrusion 32D of the gas spring 32 in the downward direction DD. Thereby, the locked state of the gas spring 32 is released.

[0342] <Step 2>

[0343] When the lock release protrusion 32D is pressed, the fixed state of the position of the locking mechanism 32C is released. In a state where the fixed state of the position of the locking mechanism 32C is released, an upward force that moves the piston 32B in the upward direction UD is generated by the action of the compressed gas filled in the cylinder 32A of the gas spring 32. In this state, the seated person adjusts the height of the seat 1.

[0344] In order to lower the seat 1 in the downward direction DD, the seated person presses the seat 1 in the downward direction DD using their body weight or the like. Specifically, by making the pressing force larger than the upward force of the gas spring 32, the seat 1 can be easily lowered.

[0345] In order to raise the seat 1 in the upward direction UD, the seated person does not apply a force to the seat 1, and by utilizing the upward force of the gas spring 32, the seat 1 can be easily raised.

[0346] <Step 3>

[0347] The operator releases the rotation of the release lever 10D in the rotation operation direction 85. Thereby, the pressing state of the lock release protrusion 32D is released. The locking mechanism 32C fixes the piston 32B in the gas spring 32. Thereby, the position of the seat 1 is fixed.

[0348] <Effect obtained by the operating mechanism 5>

[0349] In the chair 100 provided with the above-described operating mechanism 5, the gas spring 32 can be operated using the wire structure 11. That is, it is not necessary to use a rod operation as in the prior art. In particular, since the flexible wire structure 11 is used, even if there are essential components constituting the chair 100 in the layout of the components disposed on the lower surface 4L of the seat plate, the configuration of the wire structure 11 can be freely set so as to avoid the essential components. That is, regarding the layout of the lower surface 4L of the seat plate, the degree of freedom in the arrangement of the lever 10D is increased.

[0350] Furthermore, moments based on the lever principle are generated at two locations. Therefore, the sitter can easily adjust the height of the gas spring 32 with a small force.

[0351] Conventionally, the locking state of the gas spring is released by lifting a rod located below the lower surface of the plate, and the height of the seat is adjusted. For example, when lowering the position of the seat, the direction in which the rod is lifted is different from the vertical direction in which the seat moves. Therefore, there is a problem of low operability.

[0352] In contrast, according to the present embodiment, the rotation operation direction 85 of the lever 10D is the horizontal direction. That is, by moving the lever 10D in a direction orthogonal to the vertical directions UD and DD of the seat 1, the force generated by the lever 10D operated in the horizontal direction can be transmitted to the gas spring 32 by utilizing the moments generated at two locations, and the height of the seat 1 can be adjusted.

[0353] In addition, in the conventional configuration using a rod, the rod protrudes from the support structure 3 in the left - right directions RD and LD. In this case, there is a problem of a decrease in the designability of the chair 100.

[0354] In contrast, according to the present embodiment, since a rod is not used, the designability of the chair 100 as viewed from the left - right directions RD and LD can be improved.

[0355] In addition, in the conventional configuration using a rod, the rod is operated away from the lower surface 4L of the seat plate. Therefore, when the sitter operates the rod, it is necessary to stretch the fingers into the space below the lower surface 4L of the seat plate and grope with the hand to confirm the position of the rod. Therefore, the operability is low.

[0356] In contrast, according to the present embodiment, when the seated person operates the operating lever 10D, while placing a finger on the shape of the lower surface 4L of the seat plate, the position of the lever 10D is confirmed, and the lever 10D is operated. In other words, the lower surface 4L of the seat plate functions as a guiding surface for guiding the movement of the finger, and the operability of the lever 10D is improved.

[0357] Moreover, the wire structure 11 is composed of an outer tube 11A, an inner wire 11B, a first wire engaging end 11F, and a second wire engaging end 11S. The wire structure 11 is a unit. By simply removing the operation part cover 13, removing the first wire engaging end 11F from the wire support part 10C, and removing the second wire engaging end 11S from the pressing engagement part 12C, the wire structure 11 can be removed from the chair 100. Therefore, the replacement operation of the wire structure 11 can be easily performed.

[0358] Moreover, the operating mechanism 5 has a lever 10D that can rotate in the rotational operation direction 85. Therefore, the size of the operating mechanism 5 that rotates the lever 10D expands in the front-back direction FD, BD and the left-right direction RD, LD, but becomes thinner in the up-down direction UD, DD. That is, it is not necessary to increase the size of the operating mechanism 5 in the up-down direction UD, DD of the seat main body 4 which is a plate-like member, and the thickness of the seat main body 4 can be reduced.

[0359] Although the preferred embodiments of the present invention have been described, it should be understood that these are exemplary examples of the present invention and should not be regarded as limiting. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the present invention. Therefore, the present invention should not be regarded as limited by the foregoing description, but is limited by the claims.

[0360] In addition, in the above-described embodiment, the chair 100 without armrests has been described. When the chair 100 is provided with armrests, the armrests extend upward in the UD direction from both side portions on the lower side of the seat 1. The armrests support the elbows and the front ends of the arms of the seated person.

[0361] Description of reference numerals

[0362] 1 ··· Seat

[0363] 2 ··· Backrest

[0364] 3 ··· Support structure

[0365] 4 ··· Seat main body

[0366] 5 ··· Operating mechanism

[0367] 23 ··· Elastic member

[0368] 100 ··· Chair.

Claims

1. A chair, comprising: a seat having a lower surface in the vertical direction; a backrest that can tilt relative to the seat from an initial position; an elastic member having a first end and a second end, the first end being connected to the backrest, and the second end being located more forward than the first end in a first direction intersecting the vertical direction and being connected to the lower surface of the seat; and a support structure that supports the lower surface of the seat and the backrest, the support structure having: a seat support shaft portion that supports the seat in such a manner that the seat can move relative to the first direction; a back support shaft portion that extends in a second direction intersecting the vertical direction and the first direction and supports the backrest so as to be rotatable; and a position conversion mechanism that is supported so as to be rotatable relative to the seat support shaft portion and the back support shaft portion and is configured to convert the displacement of the position of the backrest caused by the rotation of the backrest into the displacement of the position of the seat, the elastic member being configured to elastically deform in the vertical direction and the first direction by the rotation of the backrest, the elastic member being configured to apply a restoring force caused by the elastic deformation to the seat and the backrest to return the seat and the backrest to the initial position.

2. The chair according to claim 1, wherein: the seat support shaft portion has: a first shaft portion that extends in the second direction and supports the seat so as to be rotatable; and a second shaft portion that extends in the second direction and supports the seat so as to be rotatable, the back support shaft portion has: a third shaft portion that is located lower than the first shaft portion in the vertical direction, extends in the second direction, and supports the backrest so as to be rotatable, the position conversion mechanism has: a fourth shaft portion that is located lower than the second shaft portion in the vertical direction and extends in the second direction; a support connector that is supported rotatably on the first shaft portion, supported rotatably on the third shaft portion, and connected to the backrest; and a support link that is supported rotatably on the second shaft portion and supported rotatably on the fourth shaft portion, the support structure having a support for supporting the third shaft portion and the fourth shaft portion, the support connector and the support link being configured to return the seat and the backrest to the initial position by the restoring force of the elastic member.

3. The chair according to claim 1, wherein: the elastic member has a bent portion located between the first end and the second end.

4. The chair according to claim 1, wherein: the first end of the elastic member is located at the upper end of the elastic member in the vertical direction, the second end of the elastic member is located at the front end of the elastic member in the first direction, the elastic member has a bent portion located between the first end and the second end.

5. The chair according to claim 4, wherein: When observed in the second direction, the bent portion has an upper extension portion connected to the first end portion and a front extension portion connected to the second end portion. The upper extension portion and the front extension portion are connected in a manner that forms an L shape.

6. The chair according to claim 5, wherein: The elastic member has: An upper region portion, which is located between the first end portion and the upper extension portion and extends in the up-and-down direction; and A front region portion, which is located between the second end portion and the front extension portion and extends in the first direction. At least one of the upper region portion and the front region portion is formed in a straight line shape.

7. The chair according to claim 2, wherein: The seat has: A seat main body, which has the lower surface; and A seat bearing member, which is separated from the seat main body. The seat bearing member supports the seat main body, the first shaft portion, and the second shaft portion, and is connected to the second end portion of the elastic member.

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