Backrest and chair

Abstract

To provide a backrest and chair capable of preventing interference between armrests (armrest bodies) to be lifted / lowered and a backrest body.SOLUTION: A backrest 4 includes: a backrest body 41 where a seated person leans his / her back against; a backrest support part 24 positioned on a rear side of the backrest body 41 so as to support the backrest body 41; and armrest bodies 71 arranged on outer sides of the backrest body 41 in a width direction so as to be supported in a lifting / lowering possible manner by the backrest support part 24 at a position separated from the backrest body 41. A chair 1 includes the backrest 4.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a backrest and a chair.

Background Art

[0002] As a backrest of a chair, a backrest having a backrest body against which a seated person leans and an armrest provided on the side of the backrest body for the seated person to rest their elbows is known (see, for example, Patent Document 1). In such a backrest, since the armrest is supported by a frame portion provided on the outer periphery of the backrest body, the armrest can be provided in a state close to the backrest body, and the armrest can support the arm of the seated person who is seated and leans against the backrest from a position close to the backrest.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a backrest with an armrest attached, when the armrest moves up and down, the moving armrest may interfere with the backrest body, and the interference between the armrest and the backrest body may lead to damage or deterioration of the backrest body.

[0005] Therefore, an object of the present invention is to provide a backrest and a chair that can prevent interference between a moving armrest (armrest body) and a backrest body.

Means for Solving the Problems

[0006] To achieve the above objective, the backrest according to the present invention comprises: a backrest body having a backrest surface on which a seated person leans their back; a backrest support part supported by a base provided on the leg portion and supporting the backrest body; and an armrest supported by the backrest support part, wherein the armrest comprises an armrest body provided on the outside in the width direction of the backrest surface of the backrest body; and an armrest body support part that supports the armrest body and is supported by the backrest support part. The backrest support portion comprises a lower frame extending in the width direction and connected to the base, a pair of upward extensions provided spaced apart from each other in the width direction and extending upward from one side and the other side of the lower frame in the width direction, and an upper connecting portion connecting the pair of upward extensions above the lower frame, and the backrest body and the armrest body support portion are each supported by the upward extensions. Furthermore, at least a portion of the backrest body and the armrest body support portion are supported by each other within the same vertical range in the upward extension portion. To achieve the above objective, the backrest according to the present invention comprises a backrest body having a backrest surface on which a seated person leans their back, a backrest support portion supported by a support base provided on the leg portion and supporting the backrest body, and an armrest supported by the backrest support portion, wherein the armrest comprises an armrest body provided on the outside in the width direction of the backrest surface of the backrest body, and an armrest body support portion that supports the armrest body and is supported by the backrest support portion, wherein the backrest support portion extends in the width direction and is connected to the support base The lower chair comprises a side frame, a pair of upward extensions spaced apart from each other in the width direction and extending upward from one side and the other side of the lower frame in the width direction, and an upper connecting portion that connects the pair of upward extensions above the lower frame. The backrest body and the armrest body support portion are each supported by the upward extensions, and the backrest body has a bent portion that protrudes forward in the middle of the vertical direction, and a backrest connecting portion below the bent portion that is connected to the upward extensions. In the backrest according to the present invention, at least a portion of the backrest body and the armrest body support portion may be supported by each other within the same vertical range in the upward extension portion. The backrest according to the present invention may have a backrest body with a bent portion that extends forward in the middle of the vertical direction, and a backrest connecting portion below the bent portion that is connected to the upward extension portion. The backrest according to the present invention comprises the backrest body and The aforementioned armrest body support part These may be connected to the upward extension by different fixing members. In the backrest according to the present invention, the armrest body and the armrest body support portion may be separate components.

[0007] Furthermore, the chair according to the present invention is characterized by having the above-mentioned backrest. [Effects of the Invention]

[0014] According to the present invention, interference between the armrest body and the backrest body, which move up and down, can be prevented. [Brief explanation of the drawing]

[0015] [Figure 1]It is a perspective view showing an example of a chair according to an embodiment of the present invention. [Figure 2] It is a front view of a chair according to an embodiment of the present invention. [Figure 3] It is a rear view of a chair according to an embodiment of the present invention. [Figure 4] It is a perspective view showing a connecting structure between a backrest support portion and an outer peripheral frame portion. [Figure 5] It is a perspective view of a backrest support portion. [Figure 6] It is a cross-sectional view taken along line A-A in FIG. 4. [Figure 7] It is a cross-sectional view taken along line B-B in FIG. 4. [Figure 8] It is a cross-sectional view taken along line C-C in FIG. 4. [Figure 9] It is a cross-sectional view taken along line D-D in FIG. 4. [Figure 10] It is a perspective view of the outer peripheral frame portion seen from the obliquely front. [Figure 11] It is a perspective view of the outer peripheral frame portion seen from the obliquely rear. [Figure 12] It is a perspective view of an armrest. [Figure 13] It is an exploded perspective view of an armrest. [Figure 14] It is a perspective view of an armrest main body support portion. [Figure 15] It is a cross-sectional view taken along line E-E in FIG. 14. [Figure 16] It is a cross-sectional view taken along line F-F in FIG. 14. [Figure 17] It is a cross-sectional view taken along line G-G in FIG. 14. [Figure 18] It is a perspective view of an armrest main body. [Figure 19] It is a cross-sectional view taken along line H-H in FIG. 18. [Figure 20] It is a cross-sectional view taken along line I-I in FIG. 12. [Figure 21] It is a perspective view of a rail member.

Mode for Carrying Out the Invention

[0016] Hereinafter, the backrest and chair according to the embodiment of the present invention will be described based on FIGS. 1 to 21. As shown in Figures 1-3, the chair 1 according to this embodiment has a support structure 2, a seat 3, and a backrest 4. In the following description, the direction in which a seated person in chair 1 faces forward is referred to as the front, and the opposite side as the rear. The horizontal direction connecting the front and rear is referred to as the front-to-back direction. The horizontal direction perpendicular to the front-to-back direction is referred to as the width direction. Chair 1 has a symmetrical shape in the width direction. Regarding the width direction, the ends of the width direction relative to the center of the width direction of chair 1 are sometimes referred to as the "outside in the width direction," and the ends of the width direction relative to the center are sometimes referred to as the "inside in the width direction" (see Figures 2 and 3).

[0017] The support structure 2 comprises a leg body 21, a leg column 22, and a support base 23. The leg body 21 has a plurality of leg rods 211 arranged radially in a plan view. Each leg rod 211 is provided with a caster 212 that makes contact with the floor surface at its tip. The leg column 22 is erected in the center of the leg body 21. The leg column 22 is telescopic and incorporates a gas spring, and has an outer cylinder 221 fixed to the leg body 21, and an inner cylinder 222 inserted through the outer cylinder 221 and extending above the outer cylinder 221. The inner cylinder 222 is configured to be able to move up and down relative to the outer cylinder 221, and is also configured to be able to rotate relative to the outer cylinder 221.

[0018] The support base 23 is fixed to the upper end of the leg column 22. The seat portion 3 is positioned on the upper part of the support base 23, and the backrest support portion 24 of the backrest 4 is positioned on the rear of the support base 23. The support base 23 supports the backrest support portion 24 in a tiltable (rotatable) manner, and also supports the seat portion 3, which forms the seating surface, in a tiltable manner in conjunction with the backrest support portion 24.

[0019] (Backrest) As shown in Figures 1-4, the backrest 4 includes a backrest body 41 on which the seated person leans their back, a backrest support part 24 located behind the backrest body 41 and supporting the backrest body 41, and an armrest 7 positioned on the outside in the width direction of the backrest body 41 on which the seated person rests their elbows.

[0020] (Backrest support part) As shown in Figures 4-5, the backrest support section 24 has a lower frame 241 connected to the base 23 (see Figures 1-3) and extending rearward from the base 23, and a rear frame 242 extending upward from the rear end of the lower frame 241. The lower frame 241 and the rear frame 242 are integrally formed. The backrest support section 24 has an L-shape when viewed from the side in the width direction.

[0021] The lower frame 241 has a pair of rear extensions 243 that extend in the front-rear direction and are spaced apart in the width direction, and a lower connecting portion 244 that connects the intermediate portions of the pair of rear extensions 243 in the front-rear direction. The front end of one of the pair of rear extensions 243 in the width direction is connected to one side of the base 23 in the width direction, and the front end of the other rear extension 243 in the width direction is connected to the other side of the base 23 in the width direction.

[0022] The rear frame 242 has a pair of upward extensions 245 that extend upward from the rear ends of a pair of rear extensions 243 and gradually toward the front, and an upper connecting portion 246 that connects the upper ends of the pair of upward extensions 245. The upper connecting portion 246 is curved such that the center in the width direction is recessed towards the rear along its entire width.

[0023] The pair of upward extensions 245 are spaced apart in the width direction. One of the pair of upward extensions 245 is located to one side in the width direction of the center of the chair 1, and the other upward extension 245 is located to the other side in the width direction of the center of the chair 1. As a result, the sides of the pair of upward extensions 245 that face each other are on the inside in the width direction, and the sides that are spaced apart from each other are on the outside in the width direction. Each of the pair of upwardly extending portions 245 is formed in a rod shape that extends from the bottom to the top and gradually toward the front, and includes a connecting portion 5 to which the backrest body 41 is fixed, and a protruding plate portion 26 (rear shielding wall) that protrudes outward in the width direction from the rear edge portion 57 of the connecting portion 5.

[0024] As shown in Figure 5, groove-shaped, concave, and perforated sections are appropriately formed in the connecting portion 5. The outer surface of the connecting portion 5 is composed of a connecting portion front surface 51 that generally faces forward, a connecting portion rear surface 52 that generally faces backward, a connecting portion inner surface 53 that generally faces inward in the width direction, and a connecting portion outer surface 54 that generally faces outward in the width direction. "Surface facing the side" or "surface facing the direction" refers to a surface whose normal extends in the direction of the side or direction of the side.

[0025] The rear surface 52 of the connecting portion is formed as a surface that gradually extends forward from the bottom to the top, and gradually extends backward from the outside in the width direction to the inside. The rear surface 52 of the connecting portion is continuous with the rear surface of the upper connecting portion 246 without any corners or steps. The front surface 51 of the connecting portion is formed as a surface that gradually extends forward from the bottom to the top, and gradually extends backward from the outside in the width direction to the inside. The front surface 51 of the connecting portion is approximately parallel to the rear surface 52 of the connecting portion.

[0026] The inner surface 53 of the connecting portion is formed such that the area near the rear end faces slightly rearward from the inward direction in the width direction, while the portion in front of that is formed such that the surface faces inward in the width direction. The outer surface 54 of the connecting portion is formed as a surface that gradually extends inward in the width direction from the rear to the front. The outer surface 54 of the connecting portion is a surface that is substantially perpendicular to the rear surface 52 and the front surface 51 of the connecting portion. The width of the connecting section 5 gradually decreases from the rear to the front.

[0027] The connecting portion 5 has two first holes 55 spaced apart vertically, into which first bolts 61 (see Figures 6 and 7) that fix the backrest body 41 are inserted, and two second holes 56 spaced apart vertically, into which second bolts 62 (see Figures 8 and 9) that fix the armrest body support portion 72 of the armrest 7 are inserted. The two second holes 56 are formed between the two first holes 55.

[0028] As shown in Figures 6 and 7, the connecting portion 5 has two recesses, a front recess 551 that opens to the front and a rear recess 552 located behind the front recess 551 and opening to the rear, spaced apart in the vertical direction. The front recess 551 and the rear recess 552 are arranged side by side in the front-to-back direction via an intermediate plate portion 553. The intermediate plate portion 553 is formed in the shape of a plate with its surface facing the front-to-back direction, and has a hole that penetrates in the front-to-back direction in the central part when viewed from the front. This hole is the first hole portion 55. Returning to Figure 5, the connecting portion 5 has a notch 554 formed in the upper part of the front recess 551 located on the upper side, and is configured so that the inside of the front recess 551 communicates with the upper part of the connecting portion 5 via the notch 554. The notch 554 is located in the upper part of the outer portion in the width direction of the front recess 551.

[0029] As shown in Figures 8 and 9, the connecting portion 5 has two inner recesses 561 that open inward in the width direction, spaced vertically between the two first holes 55 (see Figure 5). In this embodiment, the inner recesses 561 also open to the rear. The bottom surface 562 of the inner recess 561 is formed on a surface that gradually extends outward in the width direction from the front to the rear. The bottom surface 562 of the inner recess 561 is arranged parallel to the outer surface 54 of the connecting portion.

[0030] The connecting portion 5 has a hole formed therein that penetrates from the bottom surface 562 of the inner recess 561 to the outer surface 54 of the connecting portion. This hole is the second hole 56. The second hole 56 penetrates the connecting portion 5 in an oblique direction that gradually moves forward from the inside to the outside in the width direction. The direction in which the second hole 56 penetrates is along the front surface 51 and rear surface 52 of the connecting portion, and is a first oblique direction that gradually moves forward from the inside to the outside in the width direction. The first diagonal direction indicates a direction that gradually moves forward from the inside to the outside in the width direction, and the opposite direction that gradually moves backward from the outside to the inside in the width direction. The first diagonal direction is approximately horizontal. In the first direction, the side that gradually moves forward from the inside to the outside in the width direction is defined as the outside, and the opposite side that gradually moves backward from the outside to the inside in the width direction is defined as the inside.

[0031] As shown in Figures 5, 8, and 9, the protruding plate portion 26 is formed as a plate that protrudes in a first oblique direction from the rear edge portion 57 of the connecting portion 5, and its surface follows the curvature of the upper connecting portion 246. The rear surface 261 of the protruding plate portion 26 is smoothly continuous with the rear surface 52 of the connecting portion without any steps or bends 462. The front surface 262 of the protruding plate portion 26 is located behind the second hole portion 56. As a result, the protruding plate portion 26 is configured not to interfere with the second hole portion 56. The dimension of the protruding plate portion 26 that protrudes outward in the width direction from the connecting portion 5 decreases from the top to the bottom, and the plate surface has a roughly triangular shape in which the width dimension gradually decreases from the top to the bottom.

[0032] (Backrest body) The backrest body 41 is positioned in front of the rear frame 242 of the backrest support section 24. The backrest body 41 has a rectangular outer frame portion 42 with an opening 421 formed on the inside, and a facing material 43 (see Figures 1-3) that covers the opening 421 and is locked to the outer frame portion 42. In Figure 4, the facing material 43 is omitted. The surface material 43 is made up of a membrane-like material such as mesh or cloth, and is formed to be larger than the front view shape when viewed from the front of the outer frame portion 42, with its outer edge being locked to the outer frame portion 42.

[0033] As shown in Figures 4, 10, and 11, the outer perimeter frame portion 42 has an upper frame portion 44, a lower frame portion 45, and a pair of vertical frame portions 46. The pair of vertical frame sections 46 are spaced apart in the width direction. One of the pair of vertical frame sections 46 is located to one side in the width direction from the center of the chair 1 in the width direction, and the other vertical frame section 46 is located to the other side in the width direction from the center of the chair 1 in the width direction. As a result, the sides of the pair of vertical frame sections 46 that face each other are on the inside in the width direction, and the sides that are spaced apart from each other are on the outside in the width direction.

[0034] The upper frame portion 44 is a member that extends in the width direction, and is curved along its entire width direction such that, in a front view, the center in the width direction protrudes upward, and in a plan view from above, the center in the width direction protrudes backward. The upper frame portion 44 has an upper frame surface material locking groove portion 441 formed therein for locking the upper edge of the surface material 43 (see Figures 1-3). The upper frame surface material locking groove portion 441 is a groove that opens upward and is formed along the entire width direction of the upper frame portion 44. The lower frame portion 45 is a member that extends in the width direction, and is curved along its entire width direction such that the center in the width direction protrudes downward when viewed from the front, and the center in the width direction protrudes backward when viewed from above. The lower frame portion 45 has a lower frame surface material locking groove portion 451 formed therein, which locks the lower edge portion of the surface material 43. The lower frame surface material locking groove portion 451 is a groove that opens downward and is formed over the entire width of the lower frame portion 45.

[0035] Each pair of vertical frame sections 46 has a bent section 462 formed in the middle of the vertical direction. In a side view from the width direction, the pair of vertical frame sections 46 have portions below the bent section 462 that gradually extend forward from the bottom to the top, and portions above the bent section 462 that gradually extend backward from the bottom to the top. In a front view, the pair of vertical frame sections 46 have portions below the bent section 462 that gradually extend outward in the width direction from the bottom to the top, and portions above the bent section 462 that gradually extend inward in the width direction from the bottom to the top. The bent section 462 is located below the vertical center of each of the pair of vertical frame sections 46.

[0036] Each pair of vertical frame sections 46 has a panel locking section 463 (front shielding wall) that locks the panel 43, a backrest connecting section 464 that is formed continuously with the panel locking section 463 and fixed to the backrest support section 24, and a rib 465 that protrudes to the rear from the panel locking section 463.

[0037] The panel locking portion 463 is provided along the entire vertical direction of the vertical frame portion 46, with its upper end connected to the upper frame portion 44 and its lower end connected to the lower frame portion 45. Of the pair of vertical frame portions 46, the panel locking portion 463 of one vertical frame portion 46 has its upper end connected to one end of the upper frame portion 44 in the width direction and its lower end connected to one end of the lower frame portion 45 in the width direction. Of the pair of vertical frame portions 46, the panel locking portion 463 of the other vertical frame portion 46 has its upper end connected to the other end of the upper frame portion 44 in the width direction and its lower end connected to the other end of the lower frame portion 45 in the width direction.

[0038] The panel locking portion 463 has a vertical frame panel locking groove portion 461 formed therein, which locks the side edge of the panel 43. The vertical frame panel locking groove portion 461 is a groove that opens inward in the width direction and is formed over the entire vertical direction. The pair of vertical frame panel locking grooves 461 are continuous with the upper frame panel locking groove 441 and the lower frame panel locking groove 451, respectively. As a result, the outer peripheral frame 42 has grooves formed throughout its entire outer perimeter for locking the panel 43.

[0039] As shown in Figures 10 and 11, the backrest connecting portion 464 is provided on the entire portion of the vertical frame portion 46 below the bent portion 462. The backrest connecting portion 464 is provided on the inside in the width direction of the face material locking portion 463. The lower end of the backrest connecting portion 464 is connected to the lower frame portion 45. The backrest connecting portion 464 has a connecting plate portion 47 that gradually extends inward in the width direction from the rear edge of the portion below the bent portion 462 of the surface material locking portion 463, and a connecting projection portion 48 that protrudes rearward from the connecting plate portion 47.

[0040] The connecting plate portion 47 is formed as an elongated length extending in the vertical direction, and its lower end is connected to the lower frame portion 45. The front surface 471 of the connecting plate portion 47, which faces forward, is a surface that faces slightly inward in the width direction compared to the front side in the front-rear direction, and the rear surface 472 of the connecting plate portion, which faces backward, is a surface that faces slightly outward in the width direction compared to the rear side in the front-rear direction. In a plan view, the connecting plate portion 47 is formed in a shape that follows the lower frame portion 45.

[0041] Two connecting protrusions 48 are provided on each connecting plate portion 47, spaced apart in the vertical direction. As shown in Figure 11, each connecting protrusion 48 has a cylindrical portion 481 that protrudes rearward from the connecting plate portion 47, and a tip plate portion 482 connected to cover the tip (rear end) of the cylindrical portion 481. The tip plate portion 482 is formed in a flat plate shape with its surface facing the front-to-back direction, and a third hole portion 483 is formed in the center of the plate surface, penetrating in the front-to-back direction. As shown in Figures 6 and 7, the connecting projection 48 is shaped to fit from the front into the front recess 551 of the connecting portion 5 of the backrest support portion 24. When the connecting projection 48 is fitted into the front recess 551 of the connecting portion 5 of the backrest support portion 24, the third hole 483 is set to overlap with the first hole 55 of the front recess 551 in the front-rear direction.

[0042] As shown in Figure 11, the rib 465 is provided in the middle of the vertical frame portion 46, including the bent portion 462 and the areas above and below it. The rib 465 is formed in a plate shape with its surface facing the width direction. The lower end of the rib 465 is connected to the side surface of the cylindrical portion 481 of the connecting projection 48 located on the upper side. A notch 466 is formed on the lower side of the rib 465, opening to the rear and downward.

[0043] As shown in Figures 1 and 2, the facing material 43 is stretched across the front of the vertical frame portion 46 so as to cover the inside of the outer peripheral frame portion 42, wrapping around the front surfaces of the upper frame portion 44, the lower frame portion 45 and the pair of vertical frame portions 46, with its outer edges inserted into facing material locking grooves 441, 451, and 461 and locked to the outer peripheral frame portion 42. The surface formed by the facing material 43, against which the seated person leans their back, is designated as the backrest surface 431. The backrest surface 431 is curved such that its center in the width direction is recessed further back than its outer edges in the width direction. The facing material 43 stretched over the outer frame portion 42 is configured to be elastically deformable by a load acting from the front. The outer frame portion 42 is also configured to be elastically deformable by a load acting on the facing material 43.

[0044] The outer frame portion 42 is fixed to the backrest support portion 24 with the facing material 43 attached. The outer frame portion 42 is fixed to the front side of the rear frame 242 of the backrest support portion 24. As shown in Figure 4, the backrest connecting portion 464 of the pair of vertical frame portions 46 is positioned in front of the connecting portion 5 of the upward extension portion 245 of the rear frame 242. The connecting plate portion 47 of the backrest connecting portion 464 has its rear surface 472 in contact with the front surface 51 of the connecting portion 5. The connecting projection 48 of the backrest connecting portion 464 is inserted into the front recess 551 of the connecting portion 5.

[0045] The outer periphery frame portion 42 is connected to the backrest support portion 24 by fastening a first bolt 61, which is inserted through a third hole 483 formed in the tip plate portion 482 of the connecting projection portion 48 of the backrest connecting portion 464 which overlap in the front-rear direction, and a first hole 55 in the front recess 551 of the connecting portion 5 of the backrest support portion 24, with a nut. The ribs 465 of the pair of vertical frame sections 46 have their lower end portions, which are continuous with the upper connecting projection 48, inserted into a notch 554 formed on the upper side of the front recess 551 of the connecting section 5, and the portions above this lower end portion are positioned above the connecting section 5.

[0046] To fix the backrest body 41 to the backrest support part 24, first, the face material 43 is attached to the outer frame part 42. The backrest connecting portions 464 of the pair of vertical frame portions 46 of the outer peripheral frame portion 42 are positioned in front of the connecting portion 5 of the upward extension portion 245 of the rear frame 242. The rear surface 472 of the connecting plate portion 47 of the backrest connecting portion 464 is brought into contact with the front surface 51 of the connecting portion 5. The connecting projection portion 48 of the backrest connecting portion 464 is inserted into the front recess 551 of the connecting portion 5. In this manner, the third hole 483 formed in the tip plate portion 482 of the connecting projection 48 of the backrest connecting portion 464 and the first hole 55 in the front recess 551 of the connecting portion 5 of the backrest support portion 24 overlap in the front-rear direction. The first bolt 61 is inserted through these first hole 55 and third hole 483 and fastened with the nut 63. This connects the backrest body 41 to the backrest support portion 24. The nut 63 may also be fixed inside the connecting projection 48. In this configuration, a recess 27 is formed between the connected backrest support portion 24 and backrest body 41, extending substantially vertically and opening outward in the first diagonal direction, surrounded by the protruding plate portion 26 of the backrest support portion 24, the outer surface 54 of the connecting portion 5, and the surface material locking portion 463 of the vertical frame portion 46 of the backrest body 41. The armrest body support portion 72 of the armrest 7 is inserted into this recess 27.

[0047] (Armrest) As shown in Figures 12 and 13, the armrest 7 includes an armrest body 71 on which a seated person rests their elbows, an armrest body support 72 fixed to the backrest support 24 and supporting the armrest body 71 so that it can be raised and lowered, and a cover member 73 that covers the armrest body support 72.

[0048] As shown in Figures 13 and 14, the armrest body support portion 72 has a front member 74 which is a long, block-shaped member extending substantially vertically, and a rear member 75 which is a long, block-shaped member connected to the rear side of the front member 74 in a direction that extends substantially vertically. The front member 74 and the rear member 75 are each made of a metal such as an aluminum alloy and are connected by fasteners such as bolts (not shown). The armrest body support section 72, to which the front member 74 and the rear member 75 are connected, has a shape that extends in a first diagonal direction when viewed from above.

[0049] The front member 74 has a front connecting portion 741 located inward in the first diagonal direction, and a front protruding piece 742 that protrudes outward in the first diagonal direction from the front portion of the front connecting portion 741. The forward-facing surface of the front connecting portion 741 (referred to as the front surface 741a) and the forward-facing surface of the front protruding piece 742 (referred to as the front surface 742a) are each formed to face slightly inward in the width direction rather than forward in the front-rear direction. The front surface 741a of the front connecting portion 741 and the front surface 742a of the front protruding piece 742 are arranged flush with each other.

[0050] On the rearward-facing surface (referred to as the rear surface 741b) of the front connecting portion 741, a first stepped portion 741c is formed in the middle of the first diagonal direction, and the outer portion 741d, which is outward from the first stepped portion 741c in the first diagonal direction, is located in front of the inner portion 741e, which is inward from the first stepped portion 741c in the first diagonal direction. Both the outer portion 741d and the inner portion 741e on the rear surface 741b of the front connecting portion 741 are formed on surfaces that face slightly outward in the width direction rather than towards the rear in the front-rear direction. The rearward-facing surface (referred to as the rear surface 742b) of the front projection piece 742 is formed to face slightly outward in the width direction rather than towards the rear in the front-rear direction. The rear surface 742b of the front projection piece 742 is located in front of the outer portion 741d of the rear surface of the front connecting portion 741. A second step portion 742c is formed between the rear surface 742b of the front projection piece 742 and the rear surface 741b of the front connecting portion 741.

[0051] As shown in Figure 13, the inner side surface of the front connecting portion 741 in the first oblique direction (referred to as the first side surface 741f) is formed on a surface facing inward in the first oblique direction. As shown in Figures 15-17, the front connecting portion 741 has a recessed fourth hole portion 743 formed in the inner portion in the first diagonal direction, opening inward in the first diagonal direction. Screw threads are formed on the circumferential surface of the fourth hole portion 743. Two fourth holes 743 are provided, spaced apart in the vertical direction.

[0052] As shown in Figure 14, the rear member 75 is formed in a flat plate shape. The front-facing surface of the rear member 75 (referred to as the front surface 75a) is formed to face slightly inward in the width direction compared to the front side in the front-rear direction. The rear-facing surface of the rear member 75 (referred to as the rear surface 75b) is formed to face slightly outward in the width direction compared to the rear side in the front-rear direction. The rear member 75 is positioned such that its inner end 75c in the first diagonal direction is located on the first stepped portion 741c of the front member 74, and it protrudes outward in the first diagonal direction from the front connecting portion 741 of the front member 74.

[0053] The rear member 75 includes a rear connecting portion 751 positioned behind the front connecting portion 741 and connected to the front connecting portion 741, and a rear protruding piece 752 positioned outside the rear connecting portion 751 in a first diagonal direction and protruding further outward than the front connecting portion 741 in the first diagonal direction. The front protruding piece 742 and the rear protruding piece 752 are arranged parallel to each other with a gap between them in the front-rear direction. The armrest body support portion 72 has a lifting groove portion 744 formed between the front protruding piece 742 and the rear protruding piece 752, located outward in the first diagonal direction from the front connecting portion 741.

[0054] The front connecting portion 741 of the connected front member 74 and the rear connecting portion 751 of the rear member 75 are combined to form the first base portion 721. The front surface 721a of the first base portion 721 indicates the front surface 741a of the front connecting portion 741, the rear surface 721b of the first base portion 721 indicates the inner portion 741e of the rear surface 741b of the front connecting portion 741 and the rear surface 751b of the rear connecting portion 751, the upper surface 721c of the first base portion 721 indicates the upper surfaces of the front connecting portion 741 and the rear connecting portion 751, and the lower surface 721d of the first base portion 721 indicates the lower surfaces of the front connecting portion 741 and the rear connecting portion 751. In addition, the first inner side surface 721e of the first base portion 721 in the first diagonal direction indicates the first side surface 741f of the front connecting portion 741.

[0055] As shown in Figure 15, two front projection grooves 745 extending in the vertical direction are formed on the rear surface 742b of the front projection piece 742, spaced apart in the vertical direction. The cross-section of the front projection groove 745 is formed in a semi-circular shape. The front projection groove 745 does not reach the upper and lower ends of the front projection piece 742 and is configured not to communicate with the upper and lower parts of each front projection piece 742. The downward-facing end face located at the upper end of each of the two front projection grooves 745 is called the upper end face 745a of the front projection groove, and the upward-facing end face located at the lower end of the front projection groove 745 is called the lower end face 745b of the front projection groove. A first sliding material 761 is attached to the first oblique outer end face and rear face of the front protruding piece 742. The first sliding material 761 is attached in a position that does not interfere with the groove portion 745 of the front protruding piece.

[0056] As shown in Figure 16, two rear projection grooves 755 extending vertically are formed on the front surface 752a of the rear projection piece 752, spaced apart in the vertical direction. The cross-section of the rear projection groove 755 is formed in a semi-circular shape. The rear projection groove 755 is positioned opposite the front projection groove 745. The rear projection groove 755 does not reach the upper and lower ends of the rear projection piece 752 and is configured not to communicate with the upper and lower parts of each rear projection piece 752. The downward-facing end face located at the upper end of each of the two rear projection grooves 755 is called the upper end face 755a of the rear projection groove, and the upward-facing end face located at the lower end of the rear projection groove 755 is called the lower end face 755b of the rear projection groove. A second sliding material 762 is attached to the outer end face and front surface of the rear projection piece 752 in the first oblique direction. The second sliding material 762 is attached in a position that does not interfere with the groove portion 755 of the rear projection piece.

[0057] As shown in Figure 18, the armrest body 71 has an upper rod 711 provided on the upper side and extending in the front-rear direction, and a rear rod 712 provided on the rear side and extending diagonally from the rear end of the upper rod 711 downwards toward the rear. An elbow rest 713 is provided on the upper part of the front portion of the upper rod 711. The rear rod 712 is configured such that the armrest body support portion 72 (see Figure 13) is attached to its inner side in the width direction. The rear rod 712 is formed to be longer in the vertical direction than the armrest body support portion 72. The armrest body 71 has an outer shell armrest body cover portion 714, and the portion that covers the upper rod 711 and the portion that covers the rear rod 712 are formed integrally.

[0058] As shown in Figures 18 and 19, the armrest body cover portion 714 has two armrest body cover grooves 714a and 714b that extend vertically on the inside of the width direction of the portion that covers the rear rod 712, spaced apart in the front-to-back direction. The two armrest body cover grooves 714a and 714b are each longer than the vertical dimension of the armrest body support portion 72. Of the two armrest body cover grooves 714a and 714b, the front groove is designated as the front armrest body cover groove portion 714a, and the rear groove is designated as the rear armrest body cover groove portion 714b.

[0059] As shown in Figure 20, the front projection piece 742 of the armrest body support portion 72 is inserted into the armrest body cover portion 714 of the rear rod 712, passing through the groove portion 714a of the front armrest body cover, and the rear projection piece 752 of the armrest body support portion 72 is inserted into the groove portion 714b of the rear armrest body cover. In this embodiment, the portion of the armrest body cover 714 in which the two armrest body cover grooves 714a and 714b are formed is made of a member that can be attached to and detached from the rest of the body.

[0060] As shown in Figures 19 and 20, a rail member 77 is provided inside the armrest body cover portion 714 of the rear rod 712, which engages with the armrest body support portion 72 so as to be movable relative to it in the vertical direction. The rail member 77 is formed such that its vertical dimension is slightly smaller than the vertical dimension of the rear rod 712, and is longer than the vertical dimension of the armrest body support portion 72. As shown in Figures 19-21, the rail member 77 has a rod-shaped second base portion 771 extending in the vertical direction, and a protruding ridge portion 772 that protrudes inward in a first diagonal direction from the entire vertical direction of the second base portion 771. The protruding ridge portion 772 protrudes inward in a first diagonal direction from the middle portion in the front-rear direction of the second base portion 771. The front-facing surface of the protruding portion 772 (referred to as the front surface 772a) is formed to face slightly inward in the width direction compared to the front side in the front-rear direction. The rear-facing surface of the protruding portion 772 (referred to as the rear surface 772b) is formed to face slightly outward in the width direction compared to the rear side in the front-rear direction. The front surface 772a and the rear surface 772b of the protruding portion 772 are parallel to each other.

[0061] A groove portion 772c is formed on the front surface 772a of the protruding portion 772, extending over the entire vertical direction. The cross-section of the groove portion 772c is formed in an arc shape. A rear groove portion 772d is formed on the rear surface 772b of the protruding portion 772, extending over the entire vertical direction. The cross-section of the rear groove portion 772d is formed in an arc shape.

[0062] The rail member 77 is positioned inside the armrest body cover portion 714 so as to overlap with the two armrest body cover grooves 714a and 714b. As shown in Figure 20, the protruding portion 772 of the rail member 77 is inserted into the lifting groove 744 between the front protruding piece 742 and the rear protruding piece 752 of the armrest body support portion 72, which is inserted inside the armrest body cover portion 714 of the rear rod 712 through the armrest body cover grooves 714a and 714b. The second base portion 771 of the rail member 77 is in contact with the tip surfaces of the front protruding piece 742 and the rear protruding piece 752 via the sliding materials 761 and 762.

[0063] The front surface 772a of the protruding portion 772 faces the rear surface 742b of the front protruding piece 742 with a gap between them. The front groove portion 772c of the protruding portion 772a of the protruding portion 772 faces each of the two front protruding piece groove portions 745 of the rear surface 742b of the front protruding piece 742. A cylindrical front retaining member 763, extending in the vertical direction, is provided between the front groove portion 772c of the protruding ridge portion and each of the two front protruding groove portions 745. The surface of the front retaining member 763 is formed as a sliding surface.

[0064] The front retaining member 763 is formed to be slightly shorter in length than the length of the front protruding groove portion 745, and its front half is inserted into each of the two front protruding groove portions 745. The front retaining member 763 inserted into the front protruding groove portion 745 has its vertical displacement relative to the front protruding piece 742 restricted by the upper end face 745a and the lower end face 745b of the front protruding groove portion 745. The rear half of the front retaining member 763 is inserted into the front groove portion 772c of the protruding portion 772. The front retaining member 763 inserted into the front groove portion 772c of the protruding portion is configured to be relatively displaceable in the vertical direction relative to the protruding portion 772 along the front groove portion 772c of the protruding portion.

[0065] The rear surface 772b of the protruding portion 772 faces the front surface 752a of the rear protruding piece 752 with a gap between them. The rear groove portion 772d of the protruding portion 772b of the protruding portion 772 faces each of the two rear protruding piece groove portions 755 on the front surface 752a of the rear protruding piece 752. A cylindrical rear retaining member 764, extending in the vertical direction, is provided between the rear groove portion 772d of the protruding ridge portion and each of the two rear protruding flank groove portions 755. The surface of the rear retaining member 764 is formed as a sliding surface. A cylindrical rear retaining member 764, extending in the vertical direction, is provided between the front groove portion 772c of the protruding ridge and each of the two rear protruding groove portions 755. The surface of the rear retaining member 764 is formed as a sliding surface.

[0066] The rear retaining member 764 is formed to be slightly shorter in length than the length of the rear protruding groove portion 755, with its front half inserted into each of the two rear protruding groove portions 755. The rear retaining member 764 inserted into the rear protruding groove portion 755 has its vertical displacement relative to the rear protruding piece 752 restricted by the upper end face 755a and the lower end face 755b of the rear protruding groove portion 755. The rear half of the rear anti-dislodgement member 764 is inserted into the rear groove portion 772d of the protruding portion 772. The rear anti-dislodgement member 764 inserted into the rear groove portion 772d of the protruding portion is configured to be relatively displaceable in the vertical direction along the protruding portion 772 and the rear groove portion 772d of the protruding portion.

[0067] In this configuration, the armrest body 71 is configured to move up and down relative to the armrest body support 72, with the protruding portion 772 of the rail member 77 inserted into the lifting groove portion 744 of the armrest body support 72. A front retaining member is provided between the protruding portion 772 of the rail member 77 and the front protruding piece 742 of the armrest body support 72, and a rear retaining member is provided between the protruding portion 772 of the rail member 77 and the rear protruding piece 752 of the armrest body support 72, thereby preventing the armrest body support 72 from separating from the rail member 77 and coming out of the armrest body 71. Although not shown in the figures, a height adjustment mechanism of a known structure is provided to restrain the armrest body 71 at a desired height.

[0068] As shown in Figures 12 and 13, the cover member 73 covers the first base portion 721 of the armrest body support portion 72. The cover member 73 is formed in a cylindrical shape and is arranged to open in a first oblique direction. The cover member 73 has a front plate portion 731 that covers the front surface 721a of the first base portion 721, a rear plate portion 732 that covers the rear surface 721b of the first base portion 721, an upper plate portion 733 that covers the upper surface 721c of the first base portion 721, and a lower plate portion 734 that covers the lower surface 721d of the first base portion 721.

[0069] The front plate portion 731 has an upper end positioned above the upper surface 721c of the first base portion 721, and a lower end positioned below the lower surface 721d of the first base portion 721. The first diagonal inner end of the front plate portion 731 is positioned to overlap with the first side surface 721e of the first base portion 721. The first diagonal outer edge of the front plate portion 731 is positioned to overlap with the first diagonal outer edge of the first base portion 721. On the front surface 731a of the front plate portion 731, a front plate step portion 731b extending vertically is formed in the middle of the first diagonal direction. The outer portion 731c of the front plate portion 731c, which is outward in the first diagonal direction from the front plate step portion 731b, is located in front of the inner portion 731d, which is inward in the first diagonal direction from the front plate step portion 731b.

[0070] The rear plate portion 732 has an upper end positioned above the upper surface 721c of the first base portion 721 and a lower end positioned below the lower surface 721d of the first base portion 721. The first diagonal inner end of the front plate portion 731 is positioned to overlap with the first side surface 721e of the first base portion 721. The first diagonal outer edge of the front plate portion 731 is positioned to overlap with the first diagonal outer edge of the first base portion 721.

[0071] The upper plate portion 733 has its front edge connected to the upper edge of the front plate portion 731 and its rear edge connected to the upper edge of the rear plate portion 732. The first diagonal outer edge of the upper plate portion 733 is positioned to overlap with the vicinity of the first diagonal outer edge of the first base portion 721. The upper plate portion 733 protrudes inward in the width direction compared to the front plate portion 731 and the rear plate portion 732. The portion of the upper plate portion 733 that protrudes inward in the width direction compared to the front plate portion 731 and the rear plate portion 732 is called the protruding plate portion 733b. The protruding plate portion 733b protrudes inward in the width direction compared to the first base portion 721. Multiple upper ribs 735 are formed on the lower side of the upper plate portion 733, protruding downward from the lower surface of the upper plate portion 733. The lower ends of the upper ribs 735 are configured to abut against the upper surface 721c of the first base portion 721.

[0072] The lower plate portion 734 has its front edge connected to the lower edge of the front plate portion 731 and its rear edge connected to the lower edge of the rear plate portion 732. The outer edge of the lower plate portion 734 in the width direction is positioned to overlap with the vicinity of the outer edge of the first base portion 721 in the width direction. The inner edge of the lower plate portion 734 in the width direction is positioned to overlap with the lower side of the first side surface 721e of the first base portion 721. On the upper side of the lower plate portion 734, there are a plurality of lower ribs 736 that protrude upward from the upper surface of the lower plate portion 734, and an inner plate portion 737 provided above the lower ribs 736. The inner plate portion 737 has its plate surface facing approximately vertically, with its front edge connected to the front plate portion 731 and its rear edge connected to the rear plate portion 732. The upper surface of the inner plate portion 737 is configured to abut against the lower surface 721d of the first base portion 721.

[0073] The armrest 7 is connected to the armrest body 71, with the armrest body support 72 and the armrest body 71 connected, and the cover member 73 attached to the first base 721 of the armrest body support 72, and the armrest body support 72 is fixed to the backrest support 24. In the following description, it is assumed that the armrest body support 72 and the armrest body 71 are connected, and the cover member 73 is attached to the first base 721 of the armrest body support 72. Furthermore, the armrest 7 is fixed to the backrest support 24 after the backrest body 41 is fixed to the backrest support 24, by inserting the armrest body support 72 and cover member 73 into a recess 27 between the backrest support 24 and the backrest body 41, which are connected to each other. As described above, the recess 27 is surrounded by the protruding plate portion 26 of the backrest support 24, the outer surface 54 of the connecting portion 5, and the surface material locking portion 463 of the vertical frame portion 46 of the backrest body 41, and opens outward in the first diagonal direction.

[0074] As shown in Figures 8 and 9, in order to fix the armrest 7 to the backrest support 24, first, the inner portion of the armrest body support 72 in the first diagonal direction is inserted into the recess 27. At this time, the armrest 7 is inserted into the recess 27 such that the two upper and lower fourth holes 743 of the armrest body support portion 72 overlap with the two upper and lower second holes 56 of the connecting portion 5 in the first diagonal direction. Then, the first side surface 721e of the first base portion 721 is brought into contact with the outer surface 54 of the connecting portion 5 of the backrest support portion 24, and the first diagonal inner edges of the front plate portion 731, rear plate portion 732, and lower plate portion 734 (see Figure 13) of the cover member 73 are brought into contact with the outer surface 54 of the connecting portion. The protruding plate portion 733b of the upper plate portion 733 of the cover member 73 is positioned above the connecting portion 5, and the lower surface of the protruding plate portion 733b is brought into contact with the upper surface of the connecting portion 5. The inner portion 731d of the front surface 731a of the front plate portion 731 of the cover member 73 is brought into contact with the rear surface of the surface material locking portion 463 of the vertical frame portion 46 of the backrest body 41.

[0075] The connecting portion 5 and the armrest body support portion 72 are located on the rear side of the surface material 43, and the second hole 56 of the connecting portion 5 and the fourth hole 743 of the armrest body support portion 72 open in an oblique direction that faces forward rather than outward in the width direction. The opening direction of the second hole 56 and the fourth hole 743 is aligned with the backrest body 41. Furthermore, the opening direction of the second hole 56 and the fourth hole 743 is in a direction that approaches the backrest surface 431 from the inside to the outside in the width direction. The second bolt 62 is inserted into the second hole 56 and the fourth hole 743 from the inside to the outside in the width direction. Therefore, the second bolt 62 is configured to be inserted into the second hole 56 and the fourth hole 743 from the side that is spaced away from the backrest surface 431 to the side that is close to the backrest surface 431. The armrest body support portion 72 is fixed to the backrest support portion 24 by inserting the second bolt 62 through the second hole 56 and the fourth hole 743 from the inside in the width direction and fastening it with a nut. At this time, the front surface 51 of the connecting portion and the inner portion 731d of the front surface 731a of the front plate portion 731 of the cover member 73 are arranged substantially flush with each other.

[0076] The armrest support portion 72 and the cover member 73 are sandwiched from the front and back by the protruding plate portion 26 of the backrest support portion 24 and the surface material locking portion 463 of the vertical frame portion 46, and the connection portion between the armrest support portion 72 and the cover member 73 and the connecting portion 5 is covered. The outer end of the surface material locking portion 463 of the vertical frame portion 46 in the width direction is positioned along the front plate step portion 731b of the front plate portion 731 of the cover member 73, and is in contact with the front plate step portion 731b from the inside in the width direction. As a result, the cover member 73 and the vertical frame portion 46 are prevented from shifting in the width direction.

[0077] As shown in Figure 2, the armrest body support portion 72 and the cover member 73 protrude outward in the width direction from the backrest body 41, and the armrest body 71 supported by the armrest body support portion is spaced apart from the backrest body 41 and located outward in the width direction from the outer peripheral frame portion 42. The upper rod 711 of the armrest body 71 extends in the front-rear direction. The armrest portion 713 of the upper rod 711 of the armrest body 71 is located in front of the backrest body 41 and is therefore spaced apart from the backrest body 41. Alternatively, the backrest body 41 may be fixed to the backrest support part 24 after the armrest 7 has been fixed to the backrest support part 24.

[0078] Next, the function and effects of the backrest and chair according to the above-described embodiment will be explained with reference to the drawings. In the backrest 4 and chair 1 according to the above-described embodiment, the armrest body 71 is supported by the backrest support 24 so as to be able to move up and down at a position separated from the backrest body 41, thereby preventing the armrest body 71 from interfering with the backrest body 41 when the armrest body 71 is moved up or down.

[0079] Furthermore, because the backrest support section 24 is supported by an armrest body support section 72 that supports the armrest body 71 so that it can be raised and lowered, the lifting mechanism for raising and lowering the armrest body 71 can be provided in the armrest body support section 72 instead of the backrest support section 24. As a result, the backrest support section 24 can have a simpler structure compared to the case where the lifting mechanism is provided in the backrest support section 24.

[0080] Furthermore, the backrest support portion 24 has a connecting portion 5 to which the armrest body support portion 72 is connected in a state where it is in contact with the armrest body support portion 72 from the outside in the width direction, thereby enabling a firm connection between the armrest body support portion 72 and the backrest support portion 24.

[0081] Furthermore, the armrest body support portion 72 is provided on the rear side of the backrest body 41, and the backrest body 41 has a protruding plate portion 26 that is integrally provided on the front side of the connecting portion 5 and the armrest body support portion 72. As a result, the connecting portion between the connecting portion 5 and the armrest body support portion 72 is not exposed on the front side by the protruding plate portion 26, thereby improving the design of the backrest 4.

[0082] Furthermore, since the backrest support portion 24 has a rear shielding wall that protrudes outward in the width direction from the rear edge portion 57 of the connecting portion 5, the connecting portion between the connecting portion 5 and the armrest body support portion 72 is not exposed on the rear side by the rear shielding wall, thereby improving the design of the backrest 4.

[0083] Furthermore, the backrest body 41 has an outer frame portion 42 and a surface material 43 that is stretched over the outer frame portion 42 and covers the outer edge of the outer frame portion 42. This prevents the armrest body 71 from interfering with the surface material 43 of the backrest body 41 when the armrest body 71 is raised or lowered, even if the surface material 43 of the backrest body 41 covers the outer edge of the outer frame portion 42.

[0084] Although embodiments of the backrest and chair according to the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate without departing from its spirit. For example, in the above embodiment, an armrest body support part 72 is provided that is supported by the backrest support part 24 and supports the armrest body 71 so that it can be raised and lowered, but the armrest body 71 may be directly supported by the backrest support part 24. Furthermore, in the above embodiment, the backrest support portion 24 is provided with a connecting portion 5 to which the armrest body support portion 72 is connected in a state where it is in contact with the outside in the width direction, but such a connecting portion 5 is not required.

[0085] Furthermore, in the above embodiment, the armrest body support portion 72 is provided on the rear side of the backrest body 41, and the backrest body 41 has a protruding plate portion 26 that is integrally provided on the front side of the connecting portion 5 and the armrest body support portion 72, but such a protruding plate portion 26 is not required.

[0086] Furthermore, in the above embodiment, the backrest support portion 24 is provided with a surface material locking portion 463 that protrudes outward in the width direction from the rear edge portion 57 of the connecting portion 5, but such a surface material locking portion 463 is not required.

[0087] Furthermore, in the above embodiment, the backrest body 41 has an outer peripheral frame portion 42 and a surface material 43 that is stretched over the outer peripheral frame portion 42 and covers the outer edge of the outer peripheral frame portion 42, but the shape of the backrest body may be other than that described above. [Explanation of Symbols]

[0088] 1 chair 2 Support structure 4 Backrest 5 Connecting part 7 Armrest 24 Backrest support part 26 Projecting plate part (rear shielding wall) 41 Backrest Body 42 Outer frame section 43. Surface material 57 Trailing edge 62 Second bolt 71 Armrest body 72 Armrest main support part 431 Backrest 463 Surface material locking part (front shielding wall)

Claims

1. A backrest body having a backrest surface on which a seated person leans their back, A backrest support section, which is supported by a base provided on the legs and supports the backrest body, It has an armrest supported by the aforementioned backrest support, The aforementioned armrest is An armrest body provided on the outer side in the width direction of the backrest surface of the aforementioned backrest body, It has an armrest body support part that supports the armrest body and is supported by the backrest support part, The aforementioned backrest support part is, A lower frame extending in the width direction and connected to the support base, A pair of upwardly extending portions are provided spaced apart from each other in the width direction, and extend upward from one side and the other side in the width direction of the lower frame, It has an upper connecting portion that connects the pair of upward extensions above the lower frame, The backrest body and the armrest body support portion are each supported by the upward extension portion. At least a portion of the backrest body and the armrest body support portion are supported by each other within the same vertical range in the upward extension portion of the backrest.

2. A backrest body having a backrest surface on which a seated person leans their back, A backrest support section, which is supported by a base provided on the legs and supports the backrest body, It has an armrest supported by the aforementioned backrest support, The aforementioned armrest is An armrest body provided on the outer side in the width direction of the backrest surface of the aforementioned backrest body, It has an armrest body support part that supports the armrest body and is supported by the backrest support part, The aforementioned backrest support part is, A lower frame extending in the width direction and connected to the support base, A pair of upwardly extending portions are provided spaced apart from each other in the width direction, and extend upward from one side and the other side in the width direction of the lower frame, It has an upper connecting portion that connects the pair of upward extensions above the lower frame, The backrest body and the armrest body support portion are each supported by the upward extension portion. The backrest body has a bent portion that protrudes forward in the middle of the vertical direction, and a backrest connecting portion below the bent portion that is connected to the upward extension portion.

3. The backrest according to claim 1, wherein the backrest body has a bent portion that protrudes forward in the middle of the vertical direction, and a backrest connecting portion below the bent portion that is connected to the upward extension portion.

4. The backrest according to any one of claims 1 to 3, wherein the backrest body and the armrest body support portion are each connected to the upward extension portion by different fixing members.

5. The backrest according to any one of claims 1 to 4, wherein the armrest body and the armrest body support are separate components.

6. A chair having a backrest as described in any one of claims 1 to 5.

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