chair

Abstract

To provide a chair capable of increasing the degree of freedom of a backrest support member and a fixed part in the backrest.SOLUTION: A chair 100 has: a lower structure body 1 installed on a floor surface F; a backrest support member 22 supporting the lower structure body 1; and a backrest 4 supported by the backrest support member 22. The backrest 4 has a backrest body 5 which is fixed to the backrest support member 22, opens downward, and has an opening S2 communicating with a space S1 formed on the back side of the backrest 4; and an upholstery material which is stretched on the backrest body 5 and whose lower end is engaged with the backrest body 5. The backrest body 5 is fixed to the backrest support member 22, forms a load support surface supporting load of a sitter, and has a tabular backrest body 40. The backrest support member 22 is inserted in the opening S2 of the backrest body 5 and is arranged inside the space S1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a chair.

Background Art

[0002] Conventionally, as a chair used for office work or the like, there is known a chair including a lower structure such as a support base, a backrest support member such as a backrest supported by the lower structure, and a backrest supported by the backrest support member. For example, in the chair described in Patent Document 1, the backrest includes a back frame formed in a frame shape and a stretching material stretched on the back frame, and the lower part of the back frame is fixed to the backrest support member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the chair described in Patent Document 1, since the back frame of the backrest is formed in a frame shape, there is a problem that the fixing position of the backrest to the backrest support member is restricted.

[0005] Therefore, the present invention has been made in view of the above circumstances, and provides a chair capable of increasing the degree of freedom of the fixing position of the backrest to the backrest support member.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention employs the following means. In other words, the chair according to the present invention comprises a lower structure installed on the floor, a backrest support member supported by the lower structure, and a backrest supported by the backrest support member. The backrest has a backrest body fixed to the backrest support member, with an opening at its lower end that opens downward and communicates with the space behind the backrest, and a tensioning member stretched over the backrest body, with its lower end locked to the backrest body. The backrest body is fixed to the backrest support member, has a load-bearing surface formed to support the weight of the seated person, and has a plate-shaped backrest body. The backrest support member is inserted through the opening of the backrest body and positioned within the space. The backrest body has a rear extension member in which the opening is formed, and the tensioning material has a front tensioning material portion positioned in front of the backrest body and a rear tensioning material portion positioned behind the backrest body, and the rear extension member has a front tensioning material support portion positioned in front of the backrest support member and having a first locking portion formed therein for the front tensioning material portion to be locked, and a rear tensioning material support portion positioned to the side and rear of the backrest support member and having a second locking portion formed therein for the rear tensioning material portion to be locked. . Furthermore, the chair according to the present invention comprises a lower structure installed on the floor, a backrest support member supported by the lower structure, and a backrest supported by the backrest support member. The backrest has a backrest body fixed to the backrest support member, opening downwards and having an opening formed at its lower part that communicates with the space behind the backrest, and a tensioning member stretched over the backrest body with its lower end locked to the backrest body. The backrest body has a plate-shaped backrest body fixed to the backrest support member, having a load-bearing surface formed to support the weight of the seated person, and a rear extension member that has the opening formed and is fixed to the backrest support member and extends backward. The backrest support member is inserted through the opening of the backrest body and is positioned within the space. Furthermore, the chair according to the present invention comprises a lower structure installed on the floor, a backrest support member supported by the lower structure, and a backrest supported by the backrest support member, wherein the backrest has a backrest body fixed to the backrest support member, opening downwards and having an opening formed at its lower part that communicates with the space behind the backrest, and a tensioning member stretched over the backrest body with its lower end locked to the backrest body, wherein the backrest body has a plate-shaped backrest body fixed to the backrest support member and having a load-bearing surface formed to support the weight of the seated person, and a rear extension member having the opening formed and extending backward, wherein the backrest support member is inserted through the opening of the backrest body and arranged in the space, and the backrest body and the rear extension member are integrally molded. Furthermore, the chair according to the present invention comprises a lower structure installed on the floor, a backrest support member supported by the lower structure, and a backrest supported by the backrest support member, wherein the backrest has a backrest body fixed to the backrest support member, opening downwards and having an opening formed at its lower part that communicates with the space behind the backrest, and a tensioning member stretched over the backrest body with its lower end locked to the backrest body, wherein the backrest body is fixed to the backrest support member and has a plate-shaped backrest body with a load-bearing surface formed to support the weight of the seated person, and a rear extension member with the opening formed and extending backward, wherein the backrest support member is inserted through the opening of the backrest body and arranged in the space, and the rear extension member is fixed to the backrest body.

[0007] In a chair constructed in this manner, the backrest body is a plate-like structure with a load-bearing surface formed to support the weight of the seated person. Since the backrest support member is inserted through an opening in the backrest body, the backrest support member does not interfere with the backrest body, and its length in the vertical direction can be ensured. Therefore, the upper part of the backrest body can be fixed to the backrest support member, increasing the degree of freedom in the fixing points between the backrest and the backrest support member. Furthermore, since the lower end of the tensioning material is supported by the backrest body and stretched over the backrest body, the tensioning material hides the backrest support member, thus suppressing its exposure. Furthermore, when attaching the upholstery to the backrest body, the front upholstery section is secured to the first locking part of the front upholstery support, and the rear upholstery section is secured to the second locking part of the rear upholstery support. For example, if the upholstery is stapled to the backrest body, the backrest support member is inserted through the opening of the rear overhanging member, which would interfere with the stapling work. In the chair described above, the front upholstery section is secured to the first locking part, and the rear upholstery section is secured to the second locking part, so the work can be carried out without the backrest support member getting in the way.

[0008] Furthermore, in the chair according to the present invention, the widthwise length of the backrest body may be longer than the widthwise length of the backrest support member.

[0009] In a chair constructed in this manner, the backrest body is firmly supported within the upholstery, and the backrest support members are housed within the upholstery, resulting in a good appearance while increasing the tolerance of deformation on both sides of the backrest body in the width direction.

[0012] Furthermore, in the chair according to the present invention, the first locking portion may be recessed upward from the lower surface of the front upholstery portion, and the second locking portion may be recessed upward from the lower surface of the rear upholstery portion.

[0013] In a chair constructed in this manner, the first locking part is recessed upward from the underside of the front upholstery, and the second locking part is recessed upward from the underside of the rear upholstery. Therefore, when molding the rear extension member with resin, the opening, the first locking part, and the second locking part can be cut out in the same direction, resulting in excellent moldability.

[0014] Furthermore, in the chair according to the present invention, the rear extension member has an arched portion formed in an arch shape that protrudes to the rear, and the tip of the arched portion may be spaced apart behind the backrest body.

[0015] In a chair configured in this way, the tip of the arched portion of the rear extension member is positioned spaced apart behind the backrest body. Therefore, when a rearward load is applied to the backrest body, the backrest body can deform freely without being constrained by the arched portion of the rear extension member. [Effects of the Invention]

[0016] According to the chair of the present invention, the degree of freedom in fixing the backrest to the backrest support member can be increased. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view of a chair relating to one embodiment of the present invention, seen from a diagonal front angle. [Figure 2] This is a perspective view from the rear at an angle, showing a chair according to one embodiment of the present invention with the upholstery removed. [Figure 3] This is a disassembled perspective view of a chair according to one embodiment of the present invention. [Figure 4] This is a longitudinal cross-sectional view of a chair according to one embodiment of the present invention. [Figure 5] This is an enlarged view of the upper part of Figure 4. [Figure 6] It is an enlarged view of the lower part of FIG. 4. [Figure 7] It is a perspective view of the rear overhanging member of the chair according to an embodiment of the present invention as seen obliquely from the rear and above. [Figure 8] It is a perspective view of the rear overhanging member of the chair according to an embodiment of the present invention as seen obliquely from the front and below. [Figure 9] It is a horizontal sectional view including the rear overhanging member of the chair according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0018] Hereinafter, referring to FIGS. 1 to 9, a chair according to an embodiment of the present invention will be described. In the following description, for the sake of convenience of explanation, the direction in which the seated person sitting in the normal posture on the seat 17 faces forward is referred to as "front", and the opposite direction is referred to as "rear". Also, the up-down and left-right directions in the following description mean directions that match the directions centered on the seated person when the seated person is sitting in the normal posture on the seat 17. In addition, at appropriate positions in the drawings, an arrow FR indicating the front, an arrow UP indicating the upper side, and an arrow LH indicating the left side are marked.

[0019] As shown in FIG. 1, the chair 100 according to the present embodiment includes a lower structure 1, a seat 17 attached to the upper part of the lower structure 1, a backrest support member 22 (see FIG. 2) attached to the rear part of the lower structure 1, a backrest 4 supported by the backrest support member 22, and armrests 19 extending from both side portions on the lower side of the seat 17 to the upper side of the seat 17, on which the elbows or fingertips of the seated person are placed.

[0020] The lower structure 1 includes legs 10 installed on the floor surface F and a box-shaped support base 15 installed on the upper part of the legs 10.

[0021] The leg section 10 has a multi-legged leg 11 with casters 11a, and a leg column 12 that rises from the center of the multi-legged leg 11 and has a gas spring (not shown) built into it, which is a lifting mechanism. The leg column 12 has an outer cylinder 13 and an inner cylinder 14. The outer cylinder 13 is non-rotatably fitted and supported on the multi-legged leg 11. The lower part of the inner cylinder 14 is supported by the outer cylinder 13 so as to be rotatable in the horizontal direction. The upper part of the inner cylinder 14 is fixed to a support base 15. The support base 15 has a lifting adjustment mechanism for the leg column 12 and a reclining mechanism for the backrest 4 built into it.

[0022] As shown in Figure 3, the backrest support member 22 has an inner member 23 and an outer member 24.

[0023] The inner member 23 has an elongated shape in the vertical direction. The inner member 23 is formed in a flat plate shape. The plate surface of the inner member 23 is oriented approximately in the front-to-back direction.

[0024] As shown in Figure 4, the inner member 23 has an inner upper and lower extension portion 230 and an inner upper overhang portion 236. The inner upper and lower extension portion 230 has an inner curved upper portion 231, an inner curved lower portion 232, an inner lower portion 234, and an inner lower fixing portion 235.

[0025] The inner curved upper section 231 is inclined so as it moves upward, it gradually moves backward. As shown in Figure 3, multiple mounting holes 231a that penetrate in the thickness direction are formed approximately in the center of the inner curved upper section 231 in the width direction (left-right direction), spaced apart in the vertical direction. Multiple mounting holes 231b that penetrate in the thickness direction are formed at both ends of the inner curved upper section 231 in the width direction, spaced apart in the vertical direction. Mounting holes 231d that penetrate in the thickness direction are formed at the top of the inner curved upper section 231.

[0026] The lower inner curve 232 is inclined to gradually move backward as it extends downward from the lower end of the upper inner curve 231. The portion where the lower end of the upper inner curve 231 and the upper end of the lower inner curve 232 are connected has a curved shape that protrudes forward. Mounting holes 232a that penetrate in the thickness direction are formed at both ends of the lower inner curve 232 in the width direction.

[0027] The inner lower section 234 is inclined to gradually move forward as it goes downward from the lower end of the inner curved lower section 232. The portion where the lower end of the inner curved lower section 232 and the upper end of the inner lower section 234 are connected has a curved shape that protrudes rearward. As shown in Figure 6, by curving the portion where the lower end of the inner curved lower section 232 and the upper end of the inner lower section 234 are connected so as to protrude rearward, the rear end 17a of the seat 17 can be positioned rearward, thereby increasing the length of the seat 17 in the front-rear direction.

[0028] The inner lower fixing portion 235 extends downward from the lower end of the inner lower portion 234. The inner lower fixing portion 235 has a plurality of mounting holes 235a that penetrate in the direction of the plate thickness.

[0029] As shown in Figure 5, the inner upper overhang portion 236 extends rearward from the upper end of the inner curved upper portion 231. A mounting recess 236b that is recessed forward is formed on the rear surface 236a of the inner upper overhang portion 236.

[0030] As shown in Figure 3, the outer member 24 covers almost the entire rear surface of the inner member 23. The outer member 24 is wider than the inner member 23 and has an elongated shape in the vertical direction. The outer member 24 is formed in a flat plate shape. The plate surface of the outer member 24 is oriented approximately in the front-to-back direction.

[0031] The outer member 24 has outer upper and lower extensions (upper and lower extensions) 240 and outer upper overhang (upper overhang) 246. The outer upper and lower extensions 240 have outer curved upper part 241, outer curved lower part 242, and outer lower part 244.

[0032] The outer curved upper part 241 is inclined so as it extends upward, it gradually slopes backward. The outer curved upper part 241 is located behind the inner curved upper part 231. As shown in Figure 4, multiple mounting holes 241a are formed approximately in the center of the outer curved upper part 241 in the width direction (left-right direction), recessed from the front to the rear, and spaced apart in the vertical direction. A screw 231c is inserted through the mounting hole 231a of the inner curved upper part 231 of the inner member 23 and screwed into the mounting hole 241a of the outer curved upper part 241 of the outer member 24. This connects the inner member 23 and the outer member 24.

[0033] The outer curved lower section 242 is inclined so as it extends downward from the lower end of the outer curved upper section 241, it gradually slopes backward. The outer curved lower section 242 is located behind the inner curved lower section 232. The portion where the lower end of the outer curved upper section 241 and the upper end of the outer curved lower section 242 are connected has a curved shape that protrudes forward. As shown in Figure 3, the outer curved lower section 242 has a mounting hole 242a that penetrates in the thickness direction of the plate.

[0034] As shown in Figure 6, the outer lower section 244 is inclined to gradually move forward as it extends downward from the lower end of the outer curved lower section 242. The portion where the lower end of the outer curved lower section 242 and the upper end of the outer lower section 244 are connected has a curved shape that protrudes rearward. Multiple mounting recesses 244a are formed on the rear surface of the outer lower section 244, which are recessed forward. Mounting holes 244b are formed at the bottom (rearward-facing surface) of the mounting recesses 244a, penetrating through to the front surface of the outer lower section 244.

[0035] As shown in Figure 3, a rear connecting portion 16 is provided at the rear of the support base 15. The rear connecting portion 16 is part of a rotating member that rotates around the axis of a main shaft (not shown) that faces left and right relative to the support base 15. As shown in Figure 6, a bolt 244c is inserted through a mounting recess 244a in the outer lower part 244 of the outer member 24, a mounting hole 235a in the inner lower fixing portion 235 of the inner member 23, and a mounting hole 16a formed in the rear connecting portion 16, and a nut 16b is fastened to the bolt 244c. In this way, the inner member 23 and the outer member 24 are fixed together to the rear connecting portion 16.

[0036] As shown in Figure 3, the rear connecting portion 16 and the lower outer portion 244 of the outer member 24 are covered from the rear by the rear cover 248.

[0037] The outer upper overhang portion 246 extends rearward from the upper end of the outer curved upper portion 241. The width of the outer upper overhang portion 246 is wider than the width of the outer curved upper portion 241. Mounting holes 246h that penetrate in the thickness direction are formed on both sides of the outer upper overhang portion 246 in the left-right direction.

[0038] As shown in Figure 5, the rear surface 246a of the outer upper overhang 246 has multiple recesses 246b that are recessed forward and spaced apart in the left-right direction.

[0039] The recess 246b has a first recess 246c that recesses forward from the rear surface 246a of the outer upper overhang 246, and a second recess 246e that recesses forward from the bottom surface (rear-facing surface) 246d of the first recess 246c. The bottom surface (rear-facing surface) 246f of the second recess 246e has a mounting hole 246g that penetrates to the front surface of the outer upper overhang 246.

[0040] As shown in Figure 2, the backrest 4 comprises a backrest body 5 and a tensioning material 50 (see Figure 1). The backrest body 5 comprises a backrest main body 40 and a rear extension member 30.

[0041] The backrest body 40 is fixed to the backrest support member 22. The backrest body 40 is formed in a flat plate shape. The plate surface of the backrest body 40 is oriented approximately in the front-to-back direction. The length of the backrest body 40 in the width direction (direction LH) is longer than the length of the backrest support member 22 in the width direction (direction LH). The backrest body 40 has a curved upper part 401 of the backrest, a curved lower part 402 of the backrest, and an upper rear overhang 403.

[0042] As shown in Figure 4, the upper curved portion 401 of the back panel is inclined so that it gradually slopes backward as it goes upward. The upper curved portion 401 of the back panel is located in front of the upper curved portion 231. The upper rear overhang portion 403 is located in front of the upper inner overhang portion 236 and above the upper outer overhang portion 246.

[0043] As shown in Figure 3, multiple mounting holes 401a are formed approximately in the center of the upper part 401 of the curved back panel in the width direction (left-right direction), penetrating in the thickness direction, and spaced apart in the vertical and horizontal directions. The mounting holes 401a and the mounting holes 231b of the inner member 23 are connected by fasteners (not shown). As a result, the middle of the backrest body 40 in the vertical direction is fixed to the inner member 23.

[0044] A mounting hole 401b is formed in the center of the upper part 401 of the curved back panel, extending through in the thickness direction. As shown in Figure 5, a screw 401c is inserted through the mounting hole 401b of the upper part 401 of the curved back panel and screwed into the mounting hole 231d of the inner curved upper part 231 of the inner member 23. In this way, the upper part of the backrest body 40 is fixed to the inner member 23.

[0045] Mounting holes 401d are formed on both the left and right sides of the upper part 401 of the curved back plate, penetrating in the thickness direction. Screws 401e are inserted through the mounting holes 401d and screwed into the mounting holes 246h of the outer member 24. In this way, the upper part of the backrest body 40 is fixed to the outer member 24.

[0046] In the backrest body 40, the portion above the part fixed to the inner member 23 by the screw 401c is the upper rear overhang 403. The rear end portion 403a of the upper rear overhang 403 is located slightly behind the outer upper overhang 246 when viewed from the side in direction LH, and is in strong contact with the upper part of the second tensioning material portion 52 of the tensioning material 50, which will be described later.

[0047] The lower curved portion 402 of the back plate is inclined to gradually move backward as it extends downward from the lower end of the upper curved portion 401 of the back plate. The lower curved portion 402 of the back plate is located in front of the outer curved portion 242 of the outer member 24. The portion where the lower end of the upper curved portion 401 of the back plate and the upper end of the lower curved portion 402 of the back plate are connected has a curved shape that protrudes forward.

[0048] Multiple mounting holes 402a are formed in the lower part 402 of the curved back plate, spaced apart in the left-right direction and penetrating in the thickness direction of the plate. Screws 402b are inserted through the mounting holes 402a and screwed into the mounting holes 232a of the inner member 23. In this way, the lower part of the backrest body 40 is fixed to the inner member 23.

[0049] As shown in Figure 6, the lower end of the curved lower part 402 of the backrest is inserted from above between a pair of locking pieces 311a of the lower annular portion 31 of the rear overhanging member 30 and is held in place by the pair of locking pieces 311a. This restricts the movement of the backrest body 40 in the front-rear direction and downward.

[0050] The front surfaces of the upper curved part 401 and the lower curved part 402 of the backrest are load-bearing surfaces 40a (see Figure 4) that receive the load from the seated person's back.

[0051] As shown in Figure 2, the rear overhang member 30 is fixed to the lower part of the outer member 24 and extends rearward from the outer member 24.

[0052] As shown in Figures 7 and 8, the rear overhanging member 30 has a lower annular portion 31, an upper arch portion (arch-shaped portion) 32, a central connecting portion 33, and a pair of side connecting portions 34.

[0053] The lower annular portion 31 is formed in an annular shape when viewed from above. The lower annular portion 31 has a front edge portion (front tension member support portion) 311 and a curved portion (rear tension member support portion) 312.

[0054] As shown in Figure 9, the front edge 311 has a curved shape with the center in the width direction (left-right direction) slightly bulging backward. The front edge 311 is positioned behind the rear end 17a of the seat 17 with a gap. The front edge 311 is positioned in front of the backrest support member 22 with a gap.

[0055] As shown in Figure 7, a pair of upward-extending locking pieces 311a are provided at the center of the width direction of the front edge portion 311. The pair of upward-extending locking pieces 311a are spaced apart in the front-rear direction. The upward-extending locking pieces 311a are inclined upward as they are directed forward.

[0056] The curved section 312 has a semi-circular shape in plan view. The curved section 312 has a shape that bulges towards the rear. The center of the curved section 312 in the width direction is the first lower overhang (lower overhang) 313 that protrudes furthest to the rear. The tip of the curved section 312 is connected to the left and right ends of the front edge 311. As shown in Figure 9, the curved section 312 is positioned with gaps to the sides and rear of the backrest support member 22.

[0057] As shown in Figure 8, a first locking groove (first locking portion) 316a is formed on the lower surface of the leading edge portion 311, recessed upwards. The first locking groove 316a is formed along the extending direction of the leading edge portion 311. A second locking groove (second locking portion) 316b is formed on the lower surface of the curved portion 312, recessed upwards. The second locking groove 316b is formed along the extending direction of the curved portion 312. The first locking groove 316a and the second locking groove 316b are formed in a continuous annular shape.

[0058] The upper arch section 32 is positioned above the lower annular section 31. In plan view, the upper arch section 32 is formed in a roughly semi-circular shape. The upper arch section 32 is formed in an arch shape that convex towards the rear. The center of the upper arch section 32 in the width direction is the second lower overhang section (lower overhang section) 321, which protrudes furthest to the rear. As shown in Figure 6, the second lower overhang section 321 is positioned above and behind the first lower overhang section 313. As shown in Figure 2, the tip of the upper arch section 32 is positioned forward of the tip of the curved section 312. As shown in Figure 2, the tip of the upper arch section 32 is positioned behind the lower curved section 402 of the back plate with a small gap.

[0059] As shown in Figure 7, the central connecting section 33 connects the first lower overhang 313 of the lower annular section 31 and the second lower overhang 321 of the upper arch section 32. The central connecting section 33 has an upper upright section 331, a forward extension section 332, and a fixing piece section 333.

[0060] The upper upright portion 331 extends upward from the first lower overhang portion 313 of the lower annular portion 31. The forward extension portion 332 extends forward from the second lower overhang portion 321 of the upper arch portion 32. The upper end of the upper upright portion 331 is connected to the forward extension portion 332. The fixing piece portion 333 is provided at the front end of the forward extension portion 332.

[0061] As shown in Figure 6, the fixing piece 333 has a mounting hole 333a that penetrates in the front-rear direction. A bolt 333b is inserted from the mounting hole 333a of the fixing piece 333 to the mounting hole 242a of the outer curved lower part 242 of the outer member 24, and a nut 242b is fastened to the bolt 333b. In this way, the rear overhanging member 30 is connected to the outer member 24.

[0062] As shown in Figure 7, the side connecting portion 34 connects the portion of the lower annular portion 31 to the left of the first lower overhang portion 313 and the portion of the upper arch portion 32 to the left of the second lower overhang portion 321. This ensures that the distance between the lower annular portion 31 and the upper arch portion 32 does not change.

[0063] The side connecting portion 34 connects the portion of the lower annular portion 31 to the right of the first lower overhang portion 313 and the portion of the upper arch portion 32 to the right of the second lower overhang portion 321. This ensures that the distance between the lower annular portion 31 and the upper arch portion 32 does not change.

[0064] As shown in Figure 9, in the rear overhanging member 30, the annular interior of the lower annular portion 31 and the portion enclosed by the upper arch portion 32, as well as the inner portion of the upper arch portion 32, are formed as an opening S2 that penetrates vertically. As shown in Figure 2, the opening S2 communicates with the space S1 behind the backrest 4. The backrest support member 22 is inserted through the opening S2 and positioned within the space S1.

[0065] In this way, the rear overhang member 30 is configured as a separate component from the inner member 23, the outer member 24, and the backrest body 40. This allows the amount of rearward overhang of the first lower overhang 313 and the second lower overhang 321 to be appropriately set regardless of the shape of the inner member 23, the outer member 24, and the backrest body 40.

[0066] As shown in Figure 1, the upholstery material 50 is stretched over the backrest body 5 (see Figure 2) and covers the backrest body 5. The upholstery material 50 is made of fabric such as mesh.

[0067] The tensioning material 50 has a first tensioning section (front tensioning section) 51 located at the front and a second tensioning section (rear tensioning section) 52 located at the rear. The first tensioning section 51 and the second tensioning section 52 are continuous at both left and right ends and the upper end, and the lower end is open, forming a bag shape.

[0068] As shown in Figure 4, the first tension member 51 is stretched along the front surface of the backrest body 40. As shown in Figure 6, an insertion member 512 is provided at the lower end of the first tension member 51. The insertion member 512 and the lower end of the first tension member 51 to which the insertion member 512 is attached are inserted into and locked into the first locking groove 316a of the front edge 311 of the rear extension member 30. In this way, the lower end of the first tension member 51 is fixed to the rear extension member 30.

[0069] As shown in Figure 4, the second tension member 52 is stretched behind the outer member 24. As shown in Figure 5, the upper part 521 of the second tension member (rear surface of the tension member) 52 is positioned along the recess 246b of the outer member 24. A retaining member 53 is positioned behind the upper part 521 of the second tension member 52. The retaining member 53 has a shape that opens to the rear. The upper part 521 of the second tension member 52 is sandwiched in the front-rear direction between the recess 246b of the outer member 24 and the retaining member 53. A mounting hole 53a is formed in the retaining member 53 that penetrates in the front-rear direction. A screw 53b is inserted through the mounting hole 53a of the retaining member 53 and the through hole formed in the second tension member 52, and screwed into the mounting hole 246g of the outer member 24. In this way, the upper part 521 of the second tension member 52 is fixed to the outer member 24. A cap 54 is fitted to the rear of the retaining member 53.

[0070] As shown in Figure 4, the lower part 522 of the second tension member 52 is bent forward when it comes into contact with (supports) the second lower overhang 321 of the rear overhang member 30, and then bent further forward when it comes into contact with (supports) the first lower overhang 313.

[0071] The rear surface portion 523 of the tensioning material between the upper portion 521 and the lower portion 522 of the second tensioning material portion 52 is positioned behind the outer upper and lower extension portions 240 of the outer member 24, leaving a space S1.

[0072] As shown in Figure 6, an insertion member 512 is provided at the lower end of the second tension member 52. The insertion member 512 and the lower end of the second tension member 52 to which the insertion member 512 is attached are inserted into and locked into the second locking groove 316b of the curved portion 312 of the rear overhang member 30. In this way, the lower end of the second tension member 52 is fixed to the rear overhang member 30.

[0073] A space in the front-rear direction is formed between the locking groove 316 and the second lower protruding portion 321, and since the locking groove 316 is located below the second lower protruding portion 321, no tension acts on the insertion member 521 that would cause it to pull out vertically downward from the locking groove 316.

[0074] In the chair 100 configured in this way, the backrest body 40 is plate-shaped with a load-bearing surface 40a formed thereon that supports the weight of the seated person. Since the backrest support member 22 is inserted through the opening S2 of the rear extension member 30, the backrest support member 22 does not interfere with the rear extension member 30, and the length of the backrest support member 22 in the vertical direction can be secured. Therefore, the upper part of the backrest body 40 can be fixed to the backrest support member 22, and the degree of freedom of the fixing point between the backrest 4 and the backrest support member 22 can be increased.

[0075] Furthermore, since the lower end of the tensioning material 50 is supported by the rear overhanging member 30 and tensioned onto the backrest body 40, the tensioning material 50 hides the backrest support member 22, thereby suppressing the exposure of the backrest support member 22.

[0076] Furthermore, since the backrest body 40 is a flat plate-shaped member with its surface oriented in the front-to-back direction, a large load-bearing surface 40a can be secured, and the rigidity of the backrest body 40 can be increased.

[0077] Furthermore, the length of the backrest body 40 in the width direction (direction LH) is longer than the length of the backrest support member 22 in the width direction (direction LH). This allows the backrest body 40 to be firmly supported within the upholstery material 50, while also housing the backrest support member 22 within the upholstery material 50, resulting in a good appearance, and increasing the tolerance of deformation on both sides of the backrest body 40 in the width direction.

[0078] Furthermore, when attaching the upholstery material 50 to the backrest body 40, the first upholstery portion 51 is locked into the first locking groove 316a of the front edge portion 311 of the rear extension member 30, and the second upholstery portion 52 is locked into the second locking groove 316b of the curved portion 312 of the rear extension member 30. For example, if the upholstery material 50 were to be stapled to the backrest body 40, the backrest support member 22 would get in the way of the stapling work because it is inserted through the opening S2 of the rear extension member 30. In the chair 100 described above, the first upholstery portion 51 is locked into the first locking groove 316a and the second upholstery portion 52 is locked into the second locking groove 316b, so the work can be performed without the backrest support member 22 getting in the way.

[0079] Furthermore, the first locking groove 316a is recessed upward from the lower surface of the first tensioning member 51, and the second locking groove 316b is recessed upward from the lower surface of the second tensioning member 52. Therefore, when molding the rear overhanging member 30 with resin, the opening S2, the first locking groove 316a, and the second locking groove 316b can be cut out in the same direction, resulting in excellent moldability.

[0080] Furthermore, the tip of the upper arch portion 32 of the rear overhang member 30 is positioned spaced apart behind the backrest body 40. Therefore, when a rearward load is applied to the backrest body 40, the backrest body 40 can deform freely without being constrained by the upper arch portion 32 of the rear overhang member 30.

[0081] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[0082] For example, in the embodiment shown above, the backrest body 40 is formed in a flat plate shape, but slits or the like may be formed therein. Alternatively, the backrest body may be constructed by connecting multiple flat plate-shaped members vertically and horizontally, as long as the whole is flat.

[0083] Furthermore, in the embodiment shown above, the tip of the upper arch portion 32 of the rear overhang member 30 is positioned spaced apart behind the backrest body 40, but the present invention is not limited thereto. The tip of the upper arch portion 32 of the rear overhang member 30 may be in contact with or fixed to the backrest body 40. When the tip of the upper arch portion 32 of the rear overhang member 30 is fixed to the backrest body 40, the rigidity of the backrest body 5 is improved, and it can resist a load acting on the backrest body 40 as a single unit.

[0084] Furthermore, in the embodiment described above, the backrest body 40 and the rear extension member 30 are constructed as separate parts and connected to the backrest support member 22, but the present invention is not limited to this. The backrest body 40 and the rear extension member 30 may be molded as a single unit from a material such as resin.

[0085] Furthermore, in the embodiment shown above, the first locking groove 316a and the second locking groove 316b are recessed upward from the lower surface of the rear overhanging member 30, but the present invention is not limited thereto. The shapes of the first locking portion and the second locking portion can be appropriately set, for example, by forming the first locking groove 316a to recess forward from the rear surface of the front edge portion 311, and the second locking groove 316b to recess outward from the inner circumferential surface of the curved portion 312.

[0086] Furthermore, in the embodiment shown above, the rear overhang member 30 is connected to the outer member 24, but the present invention is not limited thereto. The rear overhang member 30 may also be connected to the inner member 23, or the front edge portion 311 of the rear overhang member 30 and the lower curved portion 402 of the backrest body 40 may be connected to the backrest support member 22. In addition, the rear overhang member 30 may be fixed to the backrest body 40. That is, the rear overhang member 30 only needs to be supported by at least one of the backrest support member 22 and the backrest body 40.

[0087] Alternatively, a cover member may be attached to close the opening S2 of the rear overhang member 30 from below.

[0088] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of Symbols]

[0089] 4 Backrest 5. Backrest 17 seats 22 Backrest support member 23 Inner components 24 Outer component 30 Rear overhang member 32 Upper arch section (arch-shaped section) 40 Backrest Body 40a Load bearing surface 50 Upholstery 51 First upholstery part (front upholstery part) 52 Second upholstery part (rear upholstery part) 53 Retaining member 100 chairs 201 Vertical extension part 202 Upper overhang 203 Lower overhang 240 Outer upper and lower extensions 246 Outer upper protrusion 246b recess 311 Front edge (front upholstery support part) 312 Curved part (rear upholstery support part) 313 First lower overhang 321 Second lower overhang 316a First locking groove (first locking part) 316b Second locking groove (second locking part) S1 space S2 opening

Claims

1. A substructure installed on the floor surface, A backrest support member supported by the aforementioned lower structure, The backrest is supported by the aforementioned backrest support member, The aforementioned backrest is, A backrest body fixed to the aforementioned backrest support member, with an opening formed at its lower part that opens downward and communicates with the space behind the backrest, It has a tensioning member that is stretched over the backrest and whose lower end is locked to the backrest, The aforementioned backrest body is It is fixed to the aforementioned backrest support member, has a load-bearing surface formed to support the weight of the seated person, and has a plate-shaped backrest body, The backrest support member is inserted through the opening of the backrest body and positioned within the space. The aforementioned backrest body is It has a rearward protruding member in which the aforementioned opening is formed, The aforementioned upholstery material is The front tensioning material portion is positioned in front of the aforementioned backrest body, It has a rear tensioning member positioned behind the backrest body, The aforementioned rearward protruding member is A front tension member support portion is positioned in front of the backrest support member and has a first locking portion formed therein, into which the front tension member portion is locked. A chair having a rear tensioning support portion positioned to the side and rear of the backrest support member, with a second locking portion formed therein, into which the rear tensioning portion is locked.

2. A lower structure installed on the floor surface, A backrest support member supported by the aforementioned lower structure, The backrest is supported by the aforementioned backrest support member, The aforementioned backrest is, A backrest body fixed to the aforementioned backrest support member, with an opening formed at its lower part that opens downward and communicates with the space behind the backrest, It has a tensioning member that is stretched over the backrest and whose lower end is locked to the backrest, The aforementioned backrest body is A plate-shaped backrest body is fixed to the aforementioned backrest support member, and has a load-bearing surface that supports the weight of the seated person. The opening is formed and includes a rear extension member that is fixed to the back support member and extends backward, The chair is provided with the backrest support member inserted through the opening of the backrest body and positioned within the space.

3. A lower structure installed on the floor surface, A backrest support member supported by the aforementioned lower structure, The backrest is supported by the aforementioned backrest support member, The aforementioned backrest is, A backrest body fixed to the aforementioned backrest support member, with an opening formed at its lower part that opens downward and communicates with the space behind the backrest, It has a tensioning member that is stretched over the backrest and whose lower end is locked to the backrest, The aforementioned backrest body is A plate-shaped backrest body is fixed to the aforementioned backrest support member, and has a load-bearing surface that supports the weight of the seated person. The aforementioned opening is formed and includes a rearward-extending member that protrudes to the rear, The aforementioned backrest support member is inserted through the opening of the backrest body and positioned within the space. The chair is formed in which the backrest body and the rear extension member are integrally molded.

4. A lower structure installed on the floor surface, A backrest support member supported by the aforementioned lower structure, The backrest is supported by the aforementioned backrest support member, The aforementioned backrest is, A backrest body fixed to the aforementioned backrest support member, with an opening formed at its lower part that opens downward and communicates with the space behind the backrest, It has a tensioning member that is stretched over the backrest and whose lower end is locked to the backrest, The aforementioned backrest body is A plate-shaped backrest body is fixed to the aforementioned backrest support member, and has a load-bearing surface that supports the weight of the seated person. The aforementioned opening is formed and includes a rearward-extending member that protrudes to the rear, The aforementioned backrest support member is inserted through the opening of the backrest body and positioned within the space. The rear extension member is fixed to the backrest body of the chair.

5. The chair according to any one of claims 1 to 4, wherein the length in the width direction of the backrest body is longer than the length in the width direction of the backrest support member.

6. The first locking portion is recessed upward from the lower surface of the front tensioning portion. The chair according to claim 1, wherein the second locking portion is recessed upward from the lower surface of the rear upholstery portion.

7. The aforementioned rearward overhanging member has an arch-shaped portion that is formed in an arch shape that protrudes to the rear, The chair according to claim 1 or 2, wherein the tip of the arched portion is positioned spaced apart behind the backrest body.

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