WO2010050175A1

WO2010050175A1 - Chair

Info

Publication number: WO2010050175A1
Application number: PCT/JP2009/005643
Authority: WO
Inventors: 五十嵐僚; 中山健
Original assignee: 株式会社岡村製作所
Priority date: 2008-10-29
Filing date: 2009-10-26
Publication date: 2010-05-06

Abstract

A chair (1), wherein a seat (5) is mounted to a lower structure (4) of the chair so as to be pivotable to both a standby position in which the seat (5) is tilted rearward and upward and a use position in which the seat (5) is held substantially horizontal and wherein the chair (1) is provided with a pressing means for pressing the seat toward the standby position. Armrests (7) are provided on both sides of the seat such that, when the seat is in the standby position, the front ends of the armrests are located forward of a vertical line (V) passing through the center of a mounting shaft (base shaft (6)) for mounting the seat to the lower structure. The relative positions of the seat and the armrests do not change even if the seat and the backrest are tilted, and the seat does not pivot downward when a user sits on the chair with the hands holding the front ends of the armrests. Thus, the chair is convenient to use.

Description

Chair

The present invention relates to a chair in which a seat is provided on a lower structural body of a chair so as to be rotatable between a standby position tilted rearward and a use position that is substantially horizontal. In particular, the present invention relates to a chair in which lower end portions of a backrest are attached to both side portions on the rear side of a seat so as to be able to rotate in the front-rear direction above the seat.
This application claims priority based on Japanese Patent Application Nos. 2008-277533 and 2008-277534 filed in Japan on October 29, 2008, the contents of which are incorporated herein by reference.

As such a chair, there are chairs described in

Patent Documents

1 and 2, for example. Further, as described in Patent Document 3, for example, side pieces on both sides of the lower part of the backrest that is plate-shaped are rotated in the front-rear direction on the support part for the backrest that stands up from both side surfaces of the rear part of the seat. There is a movable chair.

JP 7-124200 A Japanese Patent Laid-Open No. 10-295731 JP-A-48-63856

Since the armrest is horizontally fixed to the upper surface of the leg of the chair, the chair described in the above-mentioned patent document 1 is seated with a hand on the front end of the armrest when the seated person sits on the seat. be able to. However, since the armrest approaches the seat when the seat is tilted upward, if you try to sit down with your hand on the armrest in this state, the arm must be bent into an unnatural shape, Convenience is bad.

In the chair described in Patent Document 2, the rear end of the armrest is attached to the backrest, so if you try to sit down with your hand on the front end of the armrest on a seat that is tilted rearward upward, the load This may cause the seat to rotate downward before it is seated.
In addition, if the backrest is tilted back and forth, the armrest also tilts and the distance from the upper surface of the seat changes, so the elbow cannot be placed on the armrest in a comfortable posture.

In the chair described in the above-mentioned Patent Document 3, the support portions for the backrest that are located on both sides of the seat and the both sides of the backrest that are the attachment portions to the support portions are formed in a thin plate shape. Therefore, it is not possible to attach an armrest or a large backrest with a large vertical dimension that can hang the entire back to the support part for the backrest of such a seat in terms of strength. Have difficulty.
In addition, since the backrest is made of a plate, even if a cushion material is provided on the front, when the seated person leans on the backrest, the backrest should follow the shape of the back and rearwardly. It cannot be bridged sufficiently and a comfortable sitting comfort cannot be obtained.

The present invention has been made in view of the above problems, and even when the seat or the backrest is inclined, the relative position between the armrest and the seat does not change, and when the user sits on the front end of the armrest with his hand. An object of the present invention is to provide an easy-to-use chair in which the seat does not rotate downward.

In addition, the present invention increases the strength of the armrest by forming the armrest integrally with the seat, and the lower portion of the backrest is stably rotated above the rear side portions of the seat on this armrest. To provide a chair that can be comfortably seated and can be comfortably seated by allowing it to bend back enough so that its front surface conforms to the shape of the back when leaning on the backrest. It is aimed.

According to the present invention, the above-mentioned problems are solved by means of the following items.
(1) The seat is attached to the lower structure of the chair so that the seat can be rotated between a standby position inclined backward and upward and a use position that is substantially horizontal, and the seat is biased toward the standby position. In a chair provided with a biasing means, armrests are provided on both sides of the seat, and when the seat is in the standby position, the front end of the armrest is forward of a vertical line passing through the center of the seat mounting shaft with respect to the lower structure. Provided to be located at

With such a configuration, since the armrest is provided integrally with the seat, even if the seat rotates between the standby position and the use position, the relative position of the armrest with respect to the seat does not change. Therefore, the elbow can be placed on the armrest in a natural state from the standby position to the use position, and the usability of the chair is improved.
In addition, when the seat is in the standby position, the front end of the armrest is positioned in front of the vertical line passing through the center of the seat mounting shaft with respect to the lower structure. When seated, there is no possibility that the seat will rotate downward due to the load, and the seat can be seated with peace of mind.

(2) In the above (1), when the seat is rotated to the use position, the front end portion of the armrest is provided behind the vertical line passing through the center of the seat mounting shaft.

In such a configuration, when the seated person tries to stand up by standing on the front end of the armrest in the use position, a load pushing the armrest is applied behind the vertical line passing through the center of the seat mounting shaft. Therefore, the seat does not incline rearward and upward unexpectedly.

(3) In the above (1) or (2), the front lower part of the seat is attached to the lower structure, and the armrests are provided so as to stand up from the rear side parts of the seat and face the front.

With such a configuration, the front end of the armrest can be easily positioned forward and rearward from the vertical line passing through the center of the seat mounting axis simply by rotating the seat to the standby position and the use position. Can do.

(4) An armrest composed of a backrest pivoting portion facing upward and an armrest extending forward from the upper end of the backrest pivoting portion is integrally cast on both rear side portions of the seat, A forward-facing piece provided at both lower portions of the backrest is attached to the outer surface of the backrest pivot so that the backrest can be rotated in the front-rear direction by a shaft extending in the left-right direction.

With such a configuration, since the armrest is integrally connected to the seat, the strength of the armrest is increased. In addition, since the lower part of the backrest is attached to the pivoting support part facing upward by the front side piece connected to it, even if the backrest has a large vertical dimension, it is stable above the rear side parts of the seat. Can be rotated.

(5) In the above (4), the outer surface of the backrest pivot part is bulged outward so that the attachment part of the forward side piece is located on the outermost side.

With such a configuration, the inner surface of the forward-facing side piece does not come into extensive contact with the outer surface of the load-supporting pivot part, so that a sliding noise is generated when the backrest is rotated, The possibility that scratches are formed on the surface facing the forward side piece is reduced.

(6) In the above (4) or (5), the backrest is connected to the upper and lower ends of a pair of left and right side frames extending in the vertical direction by an upper frame and a lower frame extending in the horizontal direction. The front side is formed in a structure including a back frame having a substantially rectangular frame shape, and forward side pieces are integrally connected to lower portions on both sides of the both side frames.

With such a configuration, the front side piece is integrally connected to the side frame of the back frame having a rectangular frame shape, so the strength of the front side piece is high, and the lower part of the backrest is It can be stably attached to the backrest pivot.

(7) In the above (6), the back frame is stretched by showing a bag-shaped upholstery material having an open lower end.

With such a configuration, when the seated person leans on the backrest, the front portion of the upholstery material is sufficiently easily bent backward along the shape of the back, so that a comfortable sitting comfort can be obtained.

(8) In (7) above, an extension frame facing upward is connected to the upper ends of the left and right side frames of the back frame, and the upper ends of both extension frames are connected by a top frame extending in the left-right direction. Thus, the headrest frame is connected to the upper end of the back frame. Further, the headrest frame and the back frame are stretched by covering them with a bag-like tension material.

With such a configuration, the headrest is formed by the tension member placed on the headrest frame, and the tension material in this portion is bent backward, so that the back of the seated person can be comfortably supported.

According to the present invention, from the standby position to the use position, the elbow can be hung on the armrest in a natural state, and the usability of the chair is improved.
In addition, when the user sits on the front end of the armrest at the standby position, there is no possibility that the seat will rotate downward due to the load, and the user can sit with peace of mind.
Further, even if the backrest has a large vertical dimension, it can be stably rotated above the rear side portions of the seat.

It is a side view when one embodiment of the chair of the present invention is shown and the seat is in the standby position. FIG. 2 is a side view of the chair shown in FIG. 1 when the seat is in a use position where the seat is substantially horizontal. It is a side view when the backrest of the chair shown in FIG. 1 is tilted backward. It is the perspective view which looked at the back frame and the upholstery material covered on this from diagonally backward.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of the chair of the present invention.
This chair includes a lower structure 4 in which a pedestal 2 is erected at the center of a base 1 of a disk, and a support base 3 is attached to the upper end of the pedestal 2.

In some cases, the height of the pedestal 2 can be adjusted by gas sobring (not shown).
The support base 3 has a shape that expands in a substantially triangular shape from the upper end of the pedestal 2 toward the front in a plan view and a side view.

A front lower portion of the seat 5 is supported at the front end portion of the support base 3 via a base shaft 6 (an attachment shaft of the seat 5 with respect to the lower structure 4) extending in the left-right direction. As shown in FIGS. 2 and 3, the stand-by position tilted rearward and upward and the use position tilted slightly rearward and downward can be rotated around the base shaft 6.

A pair of left and

right armrests

7, 7 are integrally formed on the rear portions on both sides of the seat 5.
Each armrest 7 stands from both sides of the rear portion of the seat 5. Further, the rear portion of each armrest 7 includes a backrest pivot support portion 7a having a semicircular arc-shaped or fan-shaped curved surface 8 in a side view protruding rearward around a support shaft 11 of a backrest 9 described later, and the backrest. It consists of an upward arc-shaped elbow rest 7b that extends forward from the upper part of the pivot 7a, and the overall shape forms a substantially forward-facing triangle in a side view that converges toward the front and upper side.

The dimensions of the elbow rest 7b in the front-rear direction are set so that the front end thereof is positioned forward of the vertical line V passing through the center of the base shaft 6 that is the mounting shaft of the seat 5 in the standby position shown in FIG. In addition, as shown in FIG. 2, when the seat 5 is in the use position, the front end portion of the elbow rest 7b is set behind the vertical line V, that is, slightly behind the base shaft 6. Has been.

The front end portion of the forward side piece 10 extending forward from the lower portions on both sides of the backrest 9 is supported on the outer surface of the backrest pivot support portion 7a of the left and

right armrests

7 and 7 slightly forward. It is supported via a shaft 11. The backrest 9 can rotate with respect to the seat 5 and the armrest 7 around the support shaft 11 between the standing position shown in FIG. 2 and the rearward tilt position shown in FIG. It should be noted that the mounting surface of the forward side piece 10 is the outermost surface of the backrest pivot part 7a so that the inner surface of the forward side piece 10 does not come into wide contact with the outer side surface of the backrest pivot part 7a. It bulges outward to be located.

A portion of the lower portion of the backrest 9 facing the back surface of the backrest pivot portion 7a is formed as an arcuate concave curved surface 12 having a shape substantially corresponding to the curved surface 8 of the rear surface of the backrest pivot portion 7a. The backrest 9 can be rotated about the support shaft 11 with the surfaces close to each other. Between the center part in the left-right direction of the lower frame 20 to be described later in the backrest 9 and the upper surface of the front end portion of the support base 3, a gas spring or a compression spring that urges the backrest 9 in the standing direction is provided. One urging means 13 is provided.

Further, in the support base 3, second urging means 14 that can assist the seated person to stand by urging the seat 5 toward the standby position is provided.
The second urging means 14 is connected to, for example, a rubber torsion unit 15 whose axis extends in the left-right direction, and is directed to the rear side, which is urged counterclockwise in a side view in FIG. The lower end is supported by the first link 16 and a shaft extending in the left-right direction at the tip of the first link 16, and the upper end extends in the left-right direction on the lower surface of the intermediate portion in the front-rear direction of the seat 5. It consists of a second link 17 that is supported via a shaft and faces obliquely rearward and upward.

Since the armrest 7 is formed integrally with the seat 5, even if the seat 5 rotates between the standby position and the use position or the backrest 9 is inclined, the relative position of the armrest 7 with respect to the seat 5 remains unchanged. It does not change. Therefore, the elbow can be hung on the armrest 7 in a natural state from the standby position to the use position, and the usability of the chair is improved.

Further, when the seat 5 is in the standby position, the front end portion of the armrest 7b in the armrest 7 is positioned in front of the vertical line V passing through the center of the base shaft 6 to which the seat 5 is attached. In this case, when the user sits on the front end portion of the elbow rest 7b, the seat 5 is not likely to rotate downward due to the load, and can be seated with peace of mind.

Furthermore, the front end portion of the forward side piece 10 extending forward from the lower portions on both sides of the backrest 9 is attached to the backrest pivot support portion 7a standing from the rear side portions of the seat 5 via the support shaft 11, and the backrest is mounted. The opposing surfaces of the pivot portion 7a and the lower portion of the backrest 9 are an arc-shaped or fan-shaped curved surface 8 and an arc-shaped concave curved surface 12 with the support shaft 11 as the center. 7 can be largely tilted backward without interfering with 7. In addition, since the lower part of the backrest 9 is firmly supported by the backrest pivot support portion 7a of the armrest 7 that is integrated with the seat 5, even if the backrest 9 has a large vertical dimension, it can be rotated stably and smoothly. Can be supported.

As shown in FIG. 4, the backrest 9 connects the upper ends of a pair of left and right side frames 18, 18 that extend in the vertical direction by an upper frame 19 that extends in the left-right direction. The lower ends are connected by a lower frame 20 extending in the left-right direction, and the intermediate portions in the left-right direction of the upper frame 19 and the lower frame 20 are further extended in the vertical direction located behind the both side frames 18, 18. A back frame 22, which is formed by connecting with a frame 21, has a vertically rectangular frame shape.

The back frame 22 is integrally formed of a synthetic resin material having moderate elasticity. It is preferable to add reinforcing fibers such as glass fibers and carbon fibers to the synthetic resin material.

The lower portions of the side frames 18 and 18 and the lower portion of the intermediate frame 21 have an arcuate curved shape in which the center of curvature is located forward in a side view, and the upper frame 19 and the lower frame 20 are in a plan view. The intermediate portion is in a curved shape located behind the both side portions. Thereby, the lower part of the backrest 9 is separated rearward from the rear ends of the seat 5 and the armrest 7, and when the backrest 9 rotates, it is prevented from interfering with the rear ends of the seat 5 and the armrest 7. The range of rotation of the drooping 9 to the rear can be increased.

It is preferable that the curvature centers of the curved shapes of the lower portions of the side frames 18 and 18 and the lower portion of the intermediate frame 21 coincide with the support shaft 11 of the backrest 9.

The intermediate frame 21 is more easily elastically deformed than other parts by forming it thinner than other frame components in the back frame 22. Therefore, the intermediate frame 21 can be elastically deformed rearward when a load is applied to the front portion of the upholstery material 26 described later.

The rearward displacement amount of the intermediate frame 21 with respect to the both side frames 18, 18 is set so as to increase as it goes downward.

The left and right forward side pieces 10 described above are formed integrally with the lower portions of the side frames 18 and 18.

Extending

frames

23 and 23 are provided at the upper ends of the side frames 18 and 18 so as to face upward and bend so that the intermediate portion is positioned forward of the upper and lower portions in a side view. A headrest frame 25 formed by connecting the upper ends of both extension frames 23 and 23 with a top frame 24 extending in the left-right direction is integrally provided on the upper end of the back frame 22.

As shown in FIG. 4, the back frame 22 and the headrest frame 25 are stretched by covering the frame with a stretchable bag-like tension member 26 having an opening at the lower end and lower portions on both sides. Has been.

The upholstery material 26 includes a headrest cover portion 27 that covers the headrest frame 25 and a backrest cover portion 28 that covers the back frame 22, and the fabrics are different from each other. Further, the fabric of the front surface portion 27a and the rear surface portion 27b in the headrest cover portion 27 and the fabric of the front surface portion 28a and the rear surface portion 28b in the backrest cover portion 28 are also made different from each other.

The fabrics of the headrest cover portion 27 and the backrest cover portion 28 are both mesh materials, but the fabric of at least the front surface portion 27a of the headrest cover portion 27 is more stretchable than the fabric of at least the front surface portion 28a of the backrest cover portion 28. It is made of a rich mesh material.

Further, the fabric of at least the front surface portion 27a of the headrest covering portion 27 is a rough and low density mesh material, and the fabric of at least the front surface portion 28a of the backrest covering portion 28 is a fine mesh material with a high density. .

The mesh material has a weaving date or stitch direction extending in the left-right direction at the front surface portion 27a of the headrest cover portion 27 and the front surface portion 28a of the backrest cover portion 28, and the rear surface portion 27b and the backrest cover portion 28 of the headrest cover portion 27. The rear surface portion 28b extends in the vertical direction. That is, these mesh materials expand and contract in the horizontal direction at the

front surface portions

27a and 28a, and expand and contract in the vertical direction at the

rear surface portions

27b and 28b.

Further, as described above, the front surface portion 28a of the back cover portion 28 is a fine mesh mesh material having a fine mesh and having a soft surface with low translucency or low transparency. The rear surface portion 28b of the cover portion 28 is a mesh material having a low density and a coarse mesh, and is made of a mesh material having high translucency or high transparency.
As the fabric of the front surface portion 28a, it is preferable to use a molding fiber in which short fibers are sandwiched between a plurality of elastic yarns.

Further, the front portion 27a and the rear surface portion 27b in the headrest cover portion 27, and the front portion 28a and the rear surface portion 28b in the backrest cover portion 28 are not only made of materials but also different in color, thereby improving the design. is there.

The upholstery material 26 is formed not only by covering the back frame 22 and the like formed in a bag shape, but also by the

front portions

27a, 28a and the

rear surface portions

27b, 28b of the upholstery material 26 separated from each other in the front and back directions. The headrest frame 25 and the back frame 22 may be sandwiched from the front and back, and the peripheral portions of the

front surface portions

27a and 28a and the

rear surface portions

27b and 28b may be bound to each other, resulting in a bag shape.

The lower end portion of the upholstery material 26 projects the left and right

forward side pieces

10 and 10 forward from the lower openings on both sides, and the lower end portions of the front surface portion 28a and the rear surface portion 28b are connected to each other in the back frame 22. Below the lower frame 20, they are attached to the lower end of the lower frame 20 by being connected to each other by hooking fasteners, hooks, fasteners and other connecting means (all not shown).

When the headrest is not required, the headrest cover portion 27 in the headrest frame 25 and the upholstery material 26 may be omitted.

In the backrest 9 having the above-described configuration, the intermediate portions of the upper frame 19 and the lower frame 20 are connected to each other by an intermediate frame 21 extending in the vertical direction located behind the both side frames 18, 18. An intermediate portion of the rear surface portion 26 b of the upholstery material 26 is bulged rearward by the frame 21. Therefore, when the seated person falls on the backrest 9, the front surface portion 28a of the upholstery material 26 does not come into contact with the rear surface portion 28b, and the resistance force of the upholstery material 26 does not fluctuate extremely during the process. In addition, as the front surface portion 28a of the upholstery material 26 extends, the rear surface portion 28b also expands, and the extended amount of the rear surface portion 28b increases the amount of recess in the rear of the front surface portion 28a. A feeling of sitting can be obtained.

Further, since the upper frame 19 and the lower frame 20 have a curved shape in which the intermediate portion is located behind the both side portions in plan view, the intermediate frame 21 is spaced farther rearward than the both side frames 18 and 18. Can do. Therefore, the above effect can be further enhanced, the thickness of the backrest 9 in the front-rear direction can be increased, and the backrest 9 can be given a high-class feeling.

Furthermore, a headrest having a characteristic shape can be easily formed integrally with the back frame 22 by the headrest frame 25 and the headrest cover portion 27 of the bag-like upholstery material 26 shown in the headrest frame 25.

The upholstery material 26 has the fabrics of the

front surface portions

27a and 28a and the

rear surface portions

27b and 28b different from each other as described above. Therefore, even when they are formed of a mesh material, the occurrence of moire patterns is prevented. sell. In addition, the upholstery material 26 can exhibit an appropriate amount of bending, and the surface of the upholstery material 26 can have flexibility. Moreover, sufficient air permeability and elasticity can be imparted to the upholstery material 26 without reducing its translucency or transparency.

As described above, when the rearward displacement amount of the intermediate frame 21 with respect to the both side frames 18 and 18 is increased toward the lower side, the material, dimensions, etc. are the same in any part in the vertical direction. By simply showing the tension member 26 to the back frame 22, the initial tension of the tension member 26 in the lower part of the backrest 9 can be made larger than the initial tension of the tensioner 26 in the upper part of the backrest 9. Thereby, when the seated person falls on the backrest 9, the upholstery material 26 on the backrest 9 on which the upper part of the back hits has a weak tension and is deeply recessed backward. On the other hand, the upholstery material 26 under the backrest 9 where the lower back part and the temporary part hit from the lower part of the back has a strong tension and strongly supports the body. As a result, a comfortable seating feeling can be given to the seated person.

As described above, the amount of the rearward displacement of the intermediate frame 21 with respect to the side frames 18 and 18 is partially different in the vertical direction, so that the material and shape of the bag-like upholstery material 26 are partially changed in the vertical direction. The tension of the upholstery material 26 when it is attached to the back frame 22 can be partially varied in the vertical direction without changing the position.
Therefore, the tension of the tension member 26 in the portion is increased or decreased by increasing or decreasing the amount of displacement of the desired height portion of the backrest as desired. be able to.

The present invention is not limited to the above embodiment.
For example, in the above-described embodiment, the armrest 7 is integrally connected to both rear side portions of the seat 5, but a separate armrest may be attached to the seat 5 by an appropriate fixing means. The attachment position can also be, for example, the middle of the seat 5 in the front-rear direction.

In the above-described embodiment, an example in which the seat 5 is applied to a chair that rotates from a rearward-facing standby position to a use position that is substantially horizontal has been described. The present invention can also be applied to a chair fixed to the chair.

As described above, according to the chair of the present invention, the elbow can be hung on the armrest in a natural state from the standby position to the use position, and the usability of the chair is improved.
In addition, when the user sits on the front end of the armrest at the standby position, there is no possibility that the seat will rotate downward due to the load, and the seat can be seated safely.
Further, even if the backrest has a large vertical dimension, it can be stably rotated above the rear side portions of the seat.

1 base, 2 pedestals, 3 support bases, 4 lower components, 5 seats, 6 bases, 7 armrests, 7a backrest pivot support, 7b armrests, 8 curved surfaces, 9 backrests, 10 forward side pieces, 11 support shaft, 12 concave curved surface, 13 first urging means, 14 second urging means, 15 rubber torsion unit, 16 first link, 17 second link, 18 side frame, 19 upper frame, 20 lower part Frame, 21 intermediate frame, 22 back frame, 23 extension frame, 24 top frame, 25 headrest frame, 26 upholstery material, 27 headrest cover, 27a front surface, 27b rear surface, 28 backrest cover, 28a front surface, 28b Rear surface, V vertical line

Claims

A biasing means for biasing the seat toward the standby position is attached to the lower structure of the chair so that the seat can be pivoted between a standby position that tilts rearward and upward and a use position that is substantially horizontal. In the chair that was set up,
A chair provided with armrests on both sides of the seat so that when the seat is in the standby position, the front end of the armrest is positioned forward of a vertical line passing through the center of the seat mounting shaft with respect to the lower structure. .
The chair according to claim 1, wherein when the seat is rotated to the use position, the front end portion of the armrest is located behind the vertical line passing through the center of the seat mounting shaft.
The chair according to claim 1 or 2, wherein the front lower part of the seat is attached to the lower structural body, and the armrests are provided so as to stand up from both sides of the rear of the seat and face forward.
On both sides of the back of the seat, an armrest comprising a backrest pivot part facing upward and a hitting part extending forward from the upper end of the backrest pivot part is integrally connected, and the backrest The chair according to claim 1, wherein forward-side pieces provided at lower portions on both sides of the backrest are attached to an outer surface of the pivot portion so that the backrest can be rotated in the front-rear direction by a shaft extending in the left-right direction.
The chair according to claim 4, wherein the outer side surface of the backrest pivot part is bulged outward so that the attachment portion of the forward side piece is located on the outermost side.
The back shape is formed by connecting the upper ends and the lower ends of a pair of left and right side frames extending in the vertical direction with an upper frame and a lower frame extending in the horizontal direction, and the front shape is a substantially rectangular frame shape. The chair according to claim 4 or 5, further comprising a back frame that is formed, and front side pieces integrally connected to lower portions of both side frames.
The chair according to claim 6, wherein a bag-like upholstery material having a lower end is opened on the back frame.
A headrest frame is attached to the upper end of the back frame by connecting an extension frame facing upward to the upper ends of the left and right side frames of the back frame and connecting the upper ends of both extension frames with a top frame extending in the left-right direction. The chair according to claim 7, wherein a bag-like upholstery material is shown on the headrest frame and the back frame.