JP7601679B2 - chair - Google Patents

Description

The present invention relates to a chair.

Chairs that allow options such as a headrest and hangers to be attached to the backrest have been known for some time (see, for example, Patent Document 1).

By the way, many backrests to which options can be attached are equipped with polygonal nuts. The nuts have a polygonal outer periphery and are fitted into a nut fitting hole drilled into a corresponding square hole shape. The options are attached to the backrest by screwing a screw into the nut on the backrest side.

However, with conventional methods, precise alignment of the nut with the nut fitting hole is required to fit a polygonal nut into a square nut fitting hole, making the work difficult to carry out smoothly.

In addition, when arranging polygonal nuts on the frame material of the backrest, it is necessary to provide a square nut-fitting hole in the frame material, which means that the frame material needs to have a certain thickness dimension in the front-to-rear direction. In other words, in conventional chairs, when options can be attached to the backrest, the design freedom to realize a frame material with a reduced thickness dimension in the front-to-rear direction is limited.

Needless to say, the options are not limited to headrests and hangers, as long as they can be attached to the backrest.

JP 2010-099108 A

The present invention was made with the above in mind, and aims to provide a chair with a suitable configuration that allows options to be attached to at least the backrest.

That is, the present invention has the following configuration.

The invention described in claim 1 is a chair in which an option can be attached to the backrest, the backrest being provided with a nut holding recess that is formed with an upper opening portion that opens upward, a lower opening portion that opens downward, and a front opening portion that opens forward and that can hold a nut member, the nut member being provided with a boss portion that is accommodated in the nut holding recess and that has a threaded groove on its inner circumferential surface, and a flange portion that is connected to the boss portion and can engage with a portion that forms the upper opening portion, the option being provided with a screw insertion hole that penetrates in the vertical direction, and the chair being configured so that the option can be attached to the backrest by inserting a screw from below into the screw insertion hole and screwing it into the boss portion.

The invention described in claim 2 is the chair described in claim 1, in which the boss portion is accommodated in the nut holding recess through the front opening.

The invention described in claim 3 is the chair described in claim 1 or 2, in which the option is provided with a movement restriction part that can restrict forward movement by engaging with the backrest.

The invention described in claim 4 is a chair according to claims 1, 2 or 3, in which the backrest is formed by tensioning a tension member that can form a backrest surface against the frame-shaped portion, and the nut holding recess is provided in an upper frame material that extends in the left-right direction and forms the frame-shaped portion.

The invention described in claim 5 is the chair described in claim 4, in which the upper frame material has an outer frame portion in which a tension member mounting groove for mounting the tension member is formed, and an inner frame portion disposed below the outer frame portion, and the nut holding recess is provided in the inner frame portion.

The invention described in claim 6 is the chair described in claims 1, 2, 3, 4, or 5, in which the flange portion extends longitudinally in the left-right direction from the upper end of the boss portion.

The invention described in claim 7 is the chair described in claims 1, 2, 3, 4, 5 or 6, in which the option is a backrest extension member for extending the backrest or a hanger for hanging clothes.

As described above, the present invention can provide a chair with a suitable configuration that allows options to be attached to at least the backrest.

FIG. 1 is a perspective view showing an embodiment of the present invention. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. FIG. 4 is a plan view of the adjustment lever (reaction force adjustment lever) in the embodiment. 9(a) is a cross-sectional view taken along line AA in FIG. FIG. FIG. FIG. FIG. FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. 3 is a cross-sectional view taken along line CC in FIG. 2 . Cross-sectional view taken along line D-D in FIG. FIG. FIG. FIG. FIG. FIG. 16 is an enlarged view of part E in FIG. Cross-sectional view taken along line FF in Figure 19. FIG. FIG.

One embodiment of the present invention will be described below with reference to Figures 1 to 29.

In this embodiment, the present invention is applied to a swivel chair (hereafter simply referred to as "chair") suitable for use in an office or similar setting.

The chair comprises legs A, a support base B which is a support member supported rotatably on the legs A, a seat C placed on the support base B, a backrest E supported on the support base B via a back support (not shown) so as to be able to tilt backward, and a backrest surface extension member F and a hanger G which are options selectively attached to the backrest E.

<<Leg A>>
The leg A includes a plurality of leg blades a1 arranged radially, each having a caster a11 at its tip, and a leg support a2 erected at the base end of the leg blade a1.

The leg support a2 is configured to be extendable and retractable in the vertical direction. The leg support a2 is capable of supporting the support base B so that its vertical position can be changed by a gas spring (not shown).

<<Support Base B>>
The support base B is mainly composed of a support base main body 1 which is integrally formed from synthetic resin. The support base B is attached onto the legs A.

<Support base body 1>
The support base main body 1 comprises a foundation bottom structure 11 having a downward surface and attached to the leg support a2, an inclined bottom wall 12 having a downward surface facing diagonally downward and rearward and extending diagonally downward and forward from the front end of the foundation bottom structure 11, a front bottom wall 13 having a downward surface, extending forward from the front end of the inclined bottom wall 12 and inclined so as to gradually position upward as it moves forward, left and right side walls 14 in an upright position extending upward from the left and right ends of the foundation bottom structure 11, the inclined bottom wall 12, and the front bottom wall 13, respectively, and a front wall 15 in an upright position connecting the front ends of the left and right side walls 14.

Inside the support base main body 1, a reaction force generating unit (not shown) is arranged to generate a reaction force for the backrest E, which can tilt backward. The reaction force generating unit is interposed between a reaction force adjustment lever K pivoted to the support base B and a back support (not shown) pivoted to the support base B and connected to the backrest E. The reaction force generating unit is mainly composed of a spring material.

A reaction force adjustment lever K, which is an adjustment lever for adjusting the reaction force of the backrest E, is rotatably supported on the support base B.

<<Reaction force adjustment lever K>>
The reaction force adjustment lever K is rotatably supported on the support base 1. The reaction force adjustment lever K is pivotally supported on the support base 1 so that its longitudinal axis is in the left-right direction. The reaction force adjustment lever K is rotated by the user's hand, and the degree of compression of the spring material that constitutes the reaction force generating part can be adjusted in accordance with the rotation.

The reaction force adjustment lever K is provided with an operating part k1 at the tip, which is one end portion, and is gripped by the user to apply a rotational operating force; an intermediate connecting part k2, which is connected to the operating part k1 with its axis js aligned and has a shape in which the outer diameter dimension decreases with increasing distance from the operating part k1; and a lever base shaft part k3, which is connected to the intermediate connecting part k2 with its axis js aligned and has a retained shaft part k31, which is a part that is pivotally supported on the support base main body 1.

The operating part k1, intermediate connecting part k2, and lever base part k3 that make up the reaction force adjustment lever K are integrally formed from synthetic resin.

<Operation unit k1>
The operation unit k1 includes an operation unit body k11 having a generally cylindrical shape that is open to the outside, and a protrusion k12 that is a mark provided at an end of the operation unit body k11 and extends toward the center of the operation unit body k11. The protrusion k12 is a single protrusion provided from the inner peripheral surface of the operation unit body k11 toward the center of the operation unit body k11.

[Operation unit body k11]
The operation unit body k11 can form a substantially cylindrical space s1 inside. The operation unit body k11 is configured such that the outer peripheral surface of the tip portion k111 is gradually closer to the tip. In addition, the outer peripheral surface of the tip portion k111 of the operation unit body k11 is provided with a plurality of grooves k112 along the axis js to prevent finger slippage.

A mark recess k114 having a width dimension substantially equal to the thickness dimension of the protrusion k12 is formed on the outer peripheral surface of the tip portion k111 of the operating unit main body k11 corresponding to the protrusion k12. In other words, the recess k114 is provided on the outer peripheral surface of the tip portion k111 located directly behind the inner peripheral surface of the operating unit main body k11 from which the protrusion k12 protrudes.

[Protrusion k12]
The protrusion k12 protrudes from the inner peripheral surface of the operation unit main body k11 toward the axis js. The protrusion k12 is in the form of an upright wall extending along the longitudinal direction of the reaction force adjustment lever K. When viewed from the axis js direction, the protrusion k12 has a tip k121 which is a shaped portion that gradually narrows toward the axis js. In this embodiment, the shaped portion that gradually narrows is only present at the tip k121 of the protrusion k12. More specifically, the tip k121 of the protrusion k12 is in the form of a semicircular arc in a side view.

The protrusion k12 has an outward-facing end surface k122 that serves as a marker, located on the outward-facing edge of the operating unit body k11, i.e., outside the opening edge k113 of the operating unit body k11.

<Intermediate connecting portion k2>
The intermediate connecting portion k2 has an outer diameter that gradually decreases from the side having the operating portion k1 toward the side having the lever base portion k3. That is, the intermediate connecting portion k2 has a partial cone shape interposed between the operating portion k1 and the lever base portion k3.

Inside the intermediate connecting part k2, a roughly conical inner space s2 is formed, which is continuous with the cylindrical space s1 of the operating part main body k11. A protrusion k12 provided on the operating part main body k11 is connected to the inner peripheral surface of the tip side portion of the intermediate connecting part k2, i.e., the inner peripheral surface on the operating part k1 side.

<Lever base shaft portion k3>
The lever base shaft portion k3 includes a retained shaft portion k31 which is connected to the intermediate connecting portion k2 with its axis js aligned and journaled on the support base B, an engaging protrusion k32 which can engage with a protrusion (not shown) for regulating the rotation range provided on the support base B, and a cam portion k33 which can engage with a reaction force generating portion (not shown) arranged inside the support base B.

The retained shaft portion k31 is arranged in a plurality on the lever base shaft portion k3. Of the retained shaft portions k31 arranged on the lever base shaft portion k3, the diameter of the retained shaft portion k31 at the base end is the smallest, and the retained shaft portion k31 at the tip side (operating portion k1 side) is set to be the largest. In other words, the lever base shaft portion k3 is arranged with a plurality of retained shaft portions k31 with different diameters from the base end to the tip side, and the diameter at the tip side is set to be larger than that at the base end side.

The engaging protrusions k32 are arranged at two positions on the left and right of the lever base shaft k3, spaced apart from each other. The engaging protrusions k32 can restrict the range of rotation around the axis js of the reaction force adjustment lever K, which receives the operating force from the user, by engaging with a protrusion for restricting the range of rotation (not shown) provided on the support base B.

The cam portion k31 is disposed at two locations on the left and right of the lever base shaft portion k3, spaced apart.

<<Seat C>>
The seat C includes a seat support c1 and a seat body c2 that is provided on the seat support c1 so that its front-rear position can be changed.

At the bottom of the seat support c1, an operating piece L is pivoted so that it can flap and move, acting on a gas spring (not shown) to expand and contract the leg support a2 in the vertical direction.

The seat body c2 is configured to be able to slide forward and backward relative to the seat support c1.

<<Back support>>
The back support, not shown, is interposed between the support base B and the backrest E. The back support includes a pair of left and right arms that extend in the front-rear direction and are pivotally supported on the support base main body 1 via a main shaft, not shown, and a connecting member that connects the rear portions of the pair of left and right arms. The connecting member is provided with a nut portion to which a screw for attaching the backrest E is screwed. In other words, a backrest attachment portion to which the backrest E is attached is provided at the rear portion of the back support.

A rearward tilt setting lever H that can selectively set the degree of rearward tilt of the backrest E is rotatably supported on the back support.

The back support is covered and concealed by a cover body I that is integrally formed from synthetic resin.

<<Backrest E>>
The backrest E comprises a back frame M attached to the backrest mounting portion of the back support, and a mesh-like stretching member P stretched over the back frame M. The backrest E has a backrest surface pm that supports the back of a seated person from behind, and is formed by the stretching member P mainly made of mesh fabric.

The chair of this embodiment is configured so that optional backrest surface extension members F and hangers G can be selectively attached to the upper frame material 3 of the backrest E.

<Back frame M>
The back frame M comprises left and right side frame members 2 each having a tension member mounting groove mz opening outward, an upper frame member 3 having a tension member mounting groove mz opening upward and connecting the upper parts of the left and right side frame members 2, a lower frame member 4 connecting the lower parts of the left and right side frame members 2, and an intermediate connecting frame member 5 having a tension member mounting groove mz opening downward and connecting the left and right side frame members 2 together while forming an upper cavity sa between the upper frame member 3 and a lower cavity sb between the lower frame member 4.

The left and right side frame members 2, the upper frame member 3, and the lower frame member 4 are integrally molded from synthetic resin. The intermediate connecting frame member 5 is attached to the left and right side frame members 2 with screws.

The back frame M has an upper frame portion w1 that is made up of left and right side frame members 2, an upper frame member 3, and an intermediate connecting frame member 5, forming an upper cavity sa therein, and a lower frame portion w2 that is made up of left and right side frame members 2, a lower frame member 4, and an intermediate connecting frame member 5, forming a lower cavity sb therein.

In this embodiment, the backrest E is configured by tensioning a tensioning member P that can form the backrest surface pm to an upper frame portion w1 that is a frame portion provided on the back frame M.

[Left and right side frame material 2]
The left and right side frame members 2 extend in the vertical direction. On the outer surfaces of the left and right side frame members 2, a tension member attachment groove mz is formed, which continues from the upper end of the side frame member to a height position approximately corresponding to the lower edge of the intermediate connecting frame member 5.

[Upper frame material 3]
The upper frame material 3 extends in the left-right direction. The upper frame material 3 has an outer frame portion 31 in which a tension member mounting groove mz that opens upward for mounting a tension member P is formed, and an inner frame portion 32 disposed below the outer frame portion 31. The upper frame material 3 is provided with a nut holding recess nt in which a nut member J for mounting an option can be held, as will be described in detail later.

The outer frame portion 31 constitutes the upper portion of the upper frame material 3. The front surface of the outer frame portion 31 forms the portion that is attached to the back surface of the tension member P, i.e., the portion that backs the tension member P.

The inner frame portion 32 constitutes the lower portion of the upper frame material 3. The inner frame portion 32 is located inside the outer frame portion 31. In other words, the inner frame portion 32 is located in a position that is covered by the tension member P when viewed from the front.

The inner frame portion 32 includes a hanging wall 321 that hangs down from the rear of the outer frame portion 31, a lower end wall 322 that extends forward from the lower end of the hanging wall 321, and a number of connecting walls 323 that form upright walls connecting the lower end wall 322 to the outer frame portion 31 and the lower end wall 322 to the hanging wall 321.

The back surface of the hanging wall 321 is generally flush with the back surface of the outer frame portion 31. The bottom end wall 322 is provided at a distance in the up-down direction from the outer frame portion 31. The connecting walls 323 are provided to increase the connection strength between the bottom end wall 322 and the outer frame portion 31, and are provided in multiples at regular intervals in the left-right direction.

The inner frame portion 32 is provided with a nut holding recess nt that is formed with an upper opening portion kh1 that opens upward, a lower opening portion kh2 that opens downward, and a front opening portion kh3 that opens forward and can hold a nut member J. The nut holding recess nt is provided in multiple locations on the inner frame portion 32.

The nut holding recess nt is provided in the lower end wall 322 of the inner frame portion 32. The nut holding recess nt has left and right standing wall portions nt1 and a rear standing wall portion nt2 that connects the rear portions of the left and right standing wall portions nt1. The nut holding recess nt is generally U-shaped and open to the front when viewed from the bottom.

The nut holding recess nt is formed by the left and right upright wall portions nt1 and the rear upright wall portion nt2, which defines an upper opening portion kh1 that opens upward, a lower opening portion kh2 that opens downward, and a front opening portion kh3 that opens forward.

The nut holding recess nt also forms a portion that can form the upper open portion kh1 with the upper edges of the left and right upright wall portions nt1 and the upper edge of the rear upright wall portion nt2, and also forms a flange engaging portion nt3 that can engage with the underside of the flange portion j2 of the nut member J.

A gap sk is formed between the nut holding recess nt and the outer frame portion 31, allowing the flange portion j2 of the nut member J to be accommodated.

In this embodiment, the inner frame portion 32 is provided with four nut holding recesses nt spaced apart in the left-right direction. A pair of nut holding recesses nt located on both the left and right outer sides are used when attaching a backrest surface extension member F for extending the backrest surface pm, and a pair of nut holding recesses nt located on both the left and right inner sides are used when attaching a hanger G for hanging clothes.

The nut member J held in the nut holding recess nt is made of metal. The nut member J has a boss portion j1 that is housed in the enclosed space of the nut holding recess nt and has a thread groove j11 on its inner circumferential surface, and a flange portion j2 that is connected to the boss portion j1 and can engage with a flange portion engagement portion nt3, the lower surface of which forms the upper open portion kh1.

The nut member J is generally T-shaped. That is, the flange portion j2 extends longitudinally outward in the left-right direction from the upper end of the generally cylindrical boss portion j1.

The method of holding the nut member J in the nut holding recess nt provided in the backrest E and attaching the optional backrest surface extension member F and optional hanger G will be described in detail later.

[Bottom frame material 4]
The lower frame member 4 has a portion that connects the lower portions of the left and right side frame members 2 and is connected to the back support member. The lower frame member 4 is provided with a back support member connecting portion 41 that is recessed and open forward, and is adapted to be fitted externally to a backrest mounting portion provided on the back support member and connected thereto.

[Intermediate connecting frame material 5]
The intermediate connecting frame member 5 extends in the left-right direction. The intermediate connecting frame member 5 is installed between the portions of the left and right side frame members 2 that are tilted forward when viewed from the side. The intermediate connecting frame member 5 is separate from the other frame members that make up the back frame M, i.e., the left and right side frame members 2, the upper frame member 3, and the lower frame member 4.

The left and right ends of the intermediate connecting frame material 5 are screwed to the left and right side frame materials 2, respectively. The intermediate connecting frame material 5 has a curved shape that is convex toward the rear in a plan view. The intermediate connecting frame material 5 is formed with a tension member mounting groove mz that opens downward.

<Stretching member P>
The upholstery member P is mainly made of a mesh-like fabric capable of forming the backrest surface pm.

The tension member P is attached to the tension member attachment groove mz provided on the upper frame portion w1 of the back frame M at its peripheral portion. The tension member P is stretched over the front side of the upper frame portion w1 of the back frame M.

<<Backrest surface expansion member F>>
The backrest surface extension member F is for providing an extended backrest surface fm as a contact surface that can contact the user on the backrest surface pm formed by the backrest E. The backrest surface extension member F in this embodiment is called a "shoulder support" because the user's shoulders can mainly contact the extended backrest surface fm.

The backrest surface extension member F comprises a pad body f1, the front of which is an extended backrest surface fm that can come into contact with the user, and a base body f2 that can support the pad body f1.

The backrest surface extension member F has an upper frame material placement recess fu between the lower part of the base body f2 and the lower end of the pad body f1, which is open to the front and both sides.

The backrest surface extension member F is provided with a movement restriction portion ks located on the rear side of the upper frame material 3 in the backrest E at a position facing the upper frame material arrangement recess fu, and capable of restricting forward movement by engaging with the rear portion of the upper frame material 3.

<Pad body f1>
The pad body f1 comprises a pad body main body f3 attached to a pad body attachment portion f6 provided on the base body f2, and a front cover material f4 covering the front surface and peripheral edge portion of the pad body main body f3.

The pad body f1 has a generally rectangular shape with its long sides extending in the left-right direction when viewed from the front. The pad body f1 has a generally symmetrical shape when viewed from the front. The edges of both the left and right sides of the pad body f1 are gently curved so as to convex outward when viewed from the front. The extended backrest surface fm, which is the front surface of the pad body f1, is set to be generally flush with the backrest surface pm formed by the upholstery member P.

The vertical dimension of the pad body f1 is shorter than the vertical dimension of the base body f2. The position of the upper edge of the pad body f1 is approximately aligned with the position of the upper edge of the base body f2. The shape of the side edge of the pad body f1 in a front view is approximately aligned with the shape of the side edge at the same height position of the base body f2. The lower edge of the pad body f1 is set at a position that approximately abuts against the upper frame material 3.

[Pad body f3]
The pad body main body f3 includes a pad base f31 formed of synthetic resin in the shape of a generally upright plate, and a cushion f32 made of urethane foam attached to the front surface of the pad base f31.

A pair of hook engaging parts f311 are provided at the center of the back side of the pad base f31 in the vertical direction, spaced apart in the left-right direction. The hook engaging parts f311 have engaging holes f314 that are open in the vertical direction.

The hook engaging portion f311 has left and right protruding walls f312 protruding rearward and a connecting wall f313 connecting the rear portions of the left and right protruding walls f312, forming an engaging hole f314 that penetrates in the vertical direction. The hook engaging portion f311 can engage with the base body f2 by inserting a hook f61, which is an engaging portion protruding from the pad body mounting portion f6 of the base body f2, into the engaging hole f314.

The lower part of the rear side of the pad base f31 has left and right fitting protrusions f315 and a central fitting protrusion f316, which serve as engagement parts, at three locations on the left, right and center. Each fitting protrusion f315, f316 is roughly arrow-shaped and protrudes rearward. Each fitting protrusion f315, f316 can engage with a protrusion fitting part f62, which serves as an engagement part, provided on the pad body mounting part f6 of the base body f2. The left and right fitting protrusions f315 are set in a different position from the central fitting protrusion f316. More specifically, the left and right fitting protrusions f315 are set in a position rotated 90 degrees from the central fitting protrusion f316 when viewed from the rear.

[Front skin material f4]
The front skin f4 is made of a fabric having an area larger than the front part of the pad body f3. The edge portion f4e of the front skin f4 can be stored between the pad body f3 and the base body f2 so as not to be visible from the outside. The front skin f4 can form an extended backrest surface fm provided on the backrest surface pm of the upholstery member P.

<Base body f2>
The base body f2 comprises a base plate-shaped portion f5 which is approximately in the shape of an upright plate, a pad body mounting portion f6 which is provided on the front side of the base plate-shaped portion f5 and to which the pad body f1 is attached, an upper frame material mounting portion f7 which is provided below the pad body mounting portion f6 and which is attached to the upper frame material 3 using a screw v1 which is a fastening device, and a rear skin material f9 which covers the peripheral portion and rear surface portion of the base plate-shaped portion f5.

The base plate portion f5, pad body mounting portion f6, and upper frame material mounting portion f7 that constitute the base body f2 are integrally formed from synthetic resin.

In this embodiment, the backrest surface extension member F is configured so that only the rear skin material f9 covering the base plate portion f5 of the base body f2 is visible when viewed from the rear. In other words, the backrest surface extension member F is configured so that no members other than the rear skin material f9 are visible when viewed from the rear.

[Base plate portion f5]
The base plate portion f5 has a generally rectangular shape with its elongated sides in the left-right direction in rear view. The edges of the left and right sides of the base plate portion f5 are gently curved so as to convex outward in rear view. The rear surface of the base plate portion f5 is covered with a rear skin material f9.

The front side of the base plate portion f5 is provided with an upper horizontal rib f52 extending in the left-right direction whose tip can abut against the back surface of the pad base f31, and multiple vertical ribs f53 extending in the up-down direction whose tip can abut against the back surface of the pad base f31. The multiple vertical ribs f53 are arranged at intervals in the left-right direction. A lower horizontal rib f54 extending in the left-right direction whose tip can abut against the upper frame material 3 of the backrest E is provided at the lower part of the front side of the base plate portion f5.

In this embodiment, the movement restriction section ks is mainly composed of the components located behind the upper frame member 3, namely the tip of the lower horizontal rib f54 and the tip of the vertical rib f53 located below the lower horizontal rib f54, and can restrict the forward movement of the backrest surface extension member F by engaging with the back surface of the upper frame member 3.

[Pad body mounting part f6]
The pad body mounting portion f6 has a hook f61 protruding at a position corresponding to the hook engagement portion f311 of the pad base f31, and a protruding engagement portion f62 protruding at positions corresponding to the left, right and central engagement protrusions f316 of the pad base f31.

The pad body f1 is attached to the base body f2 by engaging the hook engagement portion f311 with the hook f61 provided on the pad body attachment portion f6, and then engaging the left, right, and center fitting protrusions f315 and f316 with the protrusion fitting portions f62 provided on the pad body attachment portion f6.

[Upper frame mounting part f7]
The upper frame member mounting portion f7 is mainly composed of a portion that protrudes forward from the lower end of the base plate portion f5. The upper frame member mounting portion f7 has an upward surface f71 that extends in the left-right direction and serves as the mounting base surface for the upper frame member 3.

The upper frame member mounting portion f7 has two screw insertion holes h1 that penetrate vertically on the left and right. The backrest surface extension member F is configured to be attached to the upper frame member 3 by screwing a screw v1 inserted into the screw insertion hole h1 into a nut member J arranged in a nut holding recess nt in the upper frame member 3.

The upper frame mounting portion f7 has a protruding wall portion f72 at the upper end of the front portion corresponding to the portion where the screw insertion hole h1 is formed, which can be positioned at the front opening kh3 of the nut holding recess nt provided in the upper frame 3.

A storage groove f8 that is open downward and outward and can store the edge portion f9e of the rear skin f9 is formed in the lower part of the base body f2, i.e., between the upper frame member mounting portion f7 and the base plate-shaped portion f5. A groove forming wall f73 is erected at the rear end of both sides of the upper frame member mounting portion f7 to form the storage groove f8 between the peripheral portion of the base plate-shaped portion f5.

The front surface of the groove forming wall f73 can abut against the rear surface of the upper frame material 3, and also serves as a movement restriction portion ks that can restrict the forward movement of the backrest surface extension member F.

[Rear skin f9]
The rear skin f9 is made of a material having a larger area than the rear surface of the base plate portion f5. The edge portion f9e of the rear skin f9 can be accommodated between the base plate portion f5 and the pad body f1, and can also be accommodated in an accommodating groove f8 provided between the lower peripheral portion of the base plate portion f5 and the upper frame member mounting portion f7.

<< Hanger G >>
The hanger G is for hanging and fastening a user's clothes, etc. The hanger G is attached to the upper frame member 3 of the back frame M.

The hanger G is equipped with a hanger body g1 extending in the left-right direction for hanging clothes, etc., a pair of left and right hanger legs g2 extending downward from the underside of the hanger body g1 and extending forward at the lower part, and a base portion g3 that connects the lower ends of the left and right hanger legs g2 and has an upper frame member attachment portion g7 that is attached to the upper frame member 3.

The base portion g has a base portion main body g4 on which an upper frame material mounting portion g7 is provided, and a standing wall g5 serving as a movement restriction portion ks that is erected at the rear of the base portion main body g4 and can engage with the rear surface of the upper frame material 3.

The upper frame member mounting portion g7 extends in the left-right direction and has an upward surface g71 that serves as the mounting base surface for the upper frame member 3.

The upper frame member mounting portion g7 has two screw insertion holes h2 that penetrate vertically at the left and right. The hanger G is configured to be attached to the upper frame member 3 by screwing the screw v2 inserted into the screw insertion hole h2 into the nut member J arranged in the nut holding recess nt in the upper frame member 3.

The upper frame mounting portion g7 has a protruding wall portion g72 at the upper end of the front portion corresponding to the portion where the screw insertion hole h2 is formed, which can be positioned at the front opening kh3 of the nut holding recess nt provided in the upper frame 3.

<<How to install the option (backrest extension part F)>>
In the chair of this embodiment, a mounting structure that makes it easy to mount options to the backrest E is applied. Hereinafter, a method of mounting the options to the upper frame material 3 of the backrest E will be described using the backrest surface extension member F as a specific example.

First, the nut member J is held in the nut holding recess nt that is open to the front and provided in the upper frame member 3. A tension member P is pre-attached to the front side of the upper frame portion w1 of the back frame M.

The worker passes the roughly T-shaped nut member J through the upper cavity sa surrounded by the upper frame portion w1 from the rear to the front, and then holds the nut member J in the nut holding recess nt that is open to the front.

The boss portion j1 of the nut member J is accommodated in the nut holding recess nt through the front open portion kh3. The flange portion j2 of the nut member J is accommodated in the gap sk between the nut holding recess nt and the outer frame portion 31. The flange portion j2 of the nut member J engages with the flange portion engagement portion nt3, which is the portion that forms the upper open portion kh1 in the nut holding recess nt, and cannot move downward. In other words, the nut member J is provisionally positioned relative to the upper frame material 3 by having the boss portion j1 accommodated in the nut holding recess nt and the flange portion j2 disposed in the gap sk.

Next, the backrest surface extension member F is moved from rear to front so that the upper frame material placement recess fu is positioned so that it surrounds the upper frame material 3.

Then, a screw v1 is inserted from the bottom to the top through the screw insertion hole h1 provided in the upper frame material mounting portion f7 of the backrest surface extension member F, and the screw v1 is screwed into the boss portion j1 of the nut member J. By screwing the screw v1 into the nut member J, the upper frame material mounting portion f7 of the backrest surface extension member F and the inner frame portion 32 of the upper frame material 3 are tightened.

The above attachment method allows the backrest surface extension member F to be attached to the upper frame material 3 of the backrest E.

The nut holding recess nt provided in the upper frame material 3 is open in the forward and vertical directions, making it easy for the worker to attach (temporarily place) the nut member J. The worker can properly hold the nut member J in the nut holding recess nt by simply feeling the inner frame portion 32 of the upper frame material 3 from the back side of the backrest E, without having to closely check the nut holding recess nt, which is covered by the upholstery member P and difficult to see.

The backrest surface extension member F is also provided with a movement restriction portion ks that can restrict forward movement. Therefore, even if the backrest surface extension member F is pressed forward, the nut member J cannot move forward from the nut holding recess nt that is open to the front side.

The above-described embodiment can provide a chair having an operating unit main body k11 with a generally cylindrical outer shape that is less complicated, and a reaction force adjustment lever K that can optimally perform the indicator function of indicating the rotational position by the protruding portion k12.

In addition, with the above-described embodiment, the nut member J can be held in the nut holding recess nt that is open upward, downward, and forward, so that a chair having a suitable configuration can be provided in which options such as a backrest surface extension member F can be attached to the backrest E.

In the above-described embodiment, a backrest surface extension member F is attached to the upper frame member 3 of the backrest E. The backrest surface extension member F is configured so that only the rear skin material f9 covering the base plate portion f5 can be seen when viewed from behind, so that a favorable appearance can be achieved when viewed from behind based on the rear skin material f9.

As explained above, the chair according to this embodiment is capable of mounting optional backrest extension members F and hangers G (hereinafter simply referred to as "options") to the backrest E.

The backrest E is provided with an upper opening kh1 that opens upward, a lower opening kh2 that opens downward, and a front opening kh3 that opens forward, and is provided with a nut holding recess nt that can hold the nut member J.

The nut member J has a boss portion j1 that is accommodated in the nut holding recess nt and has a thread groove j11 on its inner circumferential surface, and a flange portion j2 that can engage with a flange portion engagement portion nt3 that is connected to the boss portion j1 and forms the upper open portion kh1.

The option is provided with screw insertion holes h1, h2 that penetrate in the vertical direction, and the option can be attached to the backrest E by inserting screws v1, v2 from below through the screw insertion holes h1, h2 and screwing them into the boss portion j1.

Therefore, this embodiment can provide a chair with a suitable configuration that allows options to be attached to the backrest E.

In other words, the nut member J can be held in the nut holding recess nt that is open only in the up-down and forward directions in the backrest E. Therefore, in this embodiment, the work of holding the nut member J in the nut holding recess nt can be carried out smoothly, which contributes to reducing the time it takes for a worker to install the nut member J. In other words, the chair of this embodiment can provide a suitable optional mounting structure for the backrest E.

Furthermore, if a nut retaining recess nt is formed in the upper frame material 3 of the backrest E, options can be attached. This allows for excellent freedom in designing the upper frame material 3, which is a frame material with a reduced front-to-back dimension (front-to-back width). Since the upper frame material 3 is a part that is easily visible to the user, if the upper frame material 3 has a reduced front-to-back dimension, it can contribute to the creation of an excellent appearance.

The boss portion j1 of the nut member J is accommodated in the nut retaining recess nt through the front opening kh3.

Therefore, the worker can easily attach the nut member J to the nut holding recess nt by using the front open portion kh3.

In particular, in this embodiment, the backrest E is formed by tensioning a tension member P that can form the backrest surface pm to the upper frame portion w1, which is a frame portion. The nut holding recess nt is provided in the upper frame material 3 that extends in the left-right direction and forms the upper frame portion w1.

For this reason, the worker must attach the nut member J to the nut holding recess nt of the upper frame material 3 from the rear side of the backrest E through the cavity (upper cavity sa) of the upper frame-shaped portion w1 so as not to be obstructed by the upholstery member P. However, with the configuration according to this embodiment, the nut member J can be easily attached without precise alignment with the nut holding recess nt.

The option is equipped with a movement restriction part ks that can restrict forward movement by engaging with the backrest E.

As a result, even if a strong external force acts on the option, the nut member J held in the nut holding recess nt is maintained in the appropriate position without jumping out of the nut holding recess nt toward the front opening kh3.

The upper frame material 3 has an outer frame portion 31 in which a tension member mounting groove mz for mounting the tension member P is formed, and an inner frame portion 32 arranged below the outer frame portion 31. The inner frame portion 31 is provided with a nut holding recess nt.

As a result, the nut holding recess nt can be covered and hidden by the tension member P when viewed from the front side, and is disposed in a suitable position that is not easily noticeable from the outside.

The flange j2 of the nut member J extends longitudinally in the left-right direction from the upper end of the boss j1. Therefore, even if the thickness dimension of the upper frame material 3 in the front-to-rear direction is short, it is easy to secure a foothold that can support the flange j2 from below, and it can be suitably engaged with the upper frame material 3.

Optional items include a backrest extension member F for extending the backrest surface pm or a hanger G for hanging clothes.

As a result, the backrest extension member F or hanger G can improve convenience for users of the chair.

The present invention is not limited to the embodiments described above.

The backrest may have any configuration. In other words, the backrest is not limited to the one in which a tension member is stretched over a frame-shaped portion as shown in the above-mentioned embodiment, but may have a backrest body mainly made of synthetic resin, for example.

The option may be anything that can be attached to the backrest for use. The option is not limited to the backrest surface extension member and hanger as shown in the above embodiment, but may be, for example, a headrest.

The nut member may have any shape as long as it has a boss portion and a flange portion, and the specific shape of the nut member may be varied without departing from the spirit of the present invention.

The optional movement restriction part can be any part that can restrict forward movement by engaging with the backrest.

The specific configuration of each part is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

E...Backrest F...Backrest extension member (optional)
G…Hanger (optional)
nt... Nut holding recess J... Nut member j1... Boss portion j2... Flange portion

Claims (7)

A chair in which an option can be attached to the backrest,
The backrest is provided with a nut holding recess that is formed with an upper opening portion that is open upward, a lower opening portion that is open downward, and a front opening portion that is open forward and that can hold a nut member,
the nut member includes a boss portion that is accommodated in the nut holding recess and has a thread groove on an inner peripheral surface thereof, and a flange portion that is connected to the boss portion and can engage with a portion that forms the upper opening portion,
The option is provided with a screw insertion hole penetrating in the vertical direction,
The chair is configured so that the option can be attached to the backrest by screwing a screw inserted into the screw insertion hole from below into the boss portion. The chair of claim 1, wherein the boss portion is accommodated in the nut retaining recess through the front opening. A chair according to claim 1 or 2, wherein the option is provided with a movement restriction part that can restrict forward movement by engaging with the backrest. The backrest is provided with a tension member that can form a backrest surface and is tensioned against the frame-shaped portion,
4. The chair according to claim 1, 2 or 3, wherein the nut holding recess is provided in an upper frame member extending in the left-right direction and constituting the frame-shaped portion. The upper frame member has an outer frame portion in which a tension member mounting groove for mounting the tension member is formed, and an inner frame portion disposed below the outer frame portion,
5. The chair of claim 4, wherein said inner frame portion is provided with said nut retaining recesses. A chair according to claim 1, 2, 3, 4 or 5, in which the flange portion extends longitudinally in the left-right direction from the upper end of the boss portion. A chair according to claim 1, 2, 3, 4, 5 or 6, wherein the option is a backrest extension member for extending the backrest or a hanger for hanging clothes.

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