Chair

Abstract

To provide a structure of a chair in which anyone can properly assemble position adjustment mechanism for performing position adjustment of a backrest and option members.SOLUTION: A chair A is equipped with a height adjustment mechanism x5 as the position adjustment mechanism for performing position adjustment of a head abutment part x2 as an option member for a backrest H. The height adjustment mechanism x5 is characterized by having: a clamp part x3 which is installed in the backrest H; a slider part x4 in which the head abutment part x2 is installed and which is installed to slide relative to the clamp part x3; a top x5a as a slide position holder for keeping the slide position of the slider part x4 for the clamp part x3, an energization spring x5b, and a cam part; and an incorrect installation prevention stopper x5k which allows the installation in normal state of the clamp part x3 and the slider part x4 and which regulates installation in irregular state of the clamp part x3 and the slider part x4.SELECTED DRAWING: Figure 21

Description

[Technical field]

[0001] The present invention relates to a chair having a position adjustment mechanism for adjusting the position of an optional member relative to a backrest. [Background technology]

[0002] An example of a configuration that allows the height position adjustment of a headrest attached to the backrest of a chair is disclosed in Patent Document 1 (Patent Publication No. 5876276). In conventional chairs including that in Patent Document 1, the headrest is an optional component, so the user must attach the headrest to the chair. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5876276 (Claim 1, 0022-0028, Figures 3-6, etc.) Summary of the Invention [Problem to be solved by the invention]

[0004] Headrests in conventional chairs, including the chair disclosed in Patent Document 1, are often configured to be height adjustable, and the headrests are often packaged in parts. For this reason, when a general user who is not normally involved in chair assembly attempts to assemble a headrest on a chair, they are unable to assemble the height adjustment mechanism in the headrest in an appropriate state, and there is a risk that the height adjustment mechanism of the headrest will be damaged. [Means for solving the problem]

[0005] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a configuration for a chair with a position adjustment mechanism for adjusting the position of the backrest and optional components, which allows anyone to correctly assemble the position adjustment mechanism.

[0006] As a result of extensive research by the inventors to solve the above problems, the inventors have come up with the following configuration.

[0007] In other words, the present invention is a chair equipped with an optional component position adjustment mechanism for adjusting the position of an optional component relative to a backrest, wherein the optional component position adjustment mechanism comprises a base attached to the backrest, a slider to which the optional component is attached and which is slidably attached to the base, a slide position holder that maintains the slide position of the slider relative to the base, and an anti-misattachment stopper that allows the base and the slider to be attached in a correct state and prevents the base and the slider from being attached in an incorrect state.

[0008] This makes it possible for anyone to correctly assemble a position adjustment mechanism for adjusting the positions of the backrest and optional components in a chair equipped with the position adjustment mechanism.

[0009] In addition, the slide position holder has a biasing member and a top arranged between the base and the slider, and a cam portion formed on the slider or the base for moving the top in a direction biased by the biasing member and in a direction opposite to the direction biased by the biasing member when the slider is slid relative to the base, and it is preferable that the top has an abutment piece that abuts against the anti-misinstallation stopper on one intersecting edge side that intersects with the cam portion on the surface facing the cam portion.

[0010] It is also preferable that the portion of the top that abuts against the cam portion has an asymmetric shape in the extending direction of the cam portion.

[0011] It is also preferable that a rib is formed on at least one end of the abutting piece of the top, the rib extending in the extending direction of the cam portion.

[0012] As a result, the configuration of the position adjustment mechanism is further simplified, and mistakes in assembling the position adjustment mechanism can be eliminated. Effect of the Invention

[0013] As described above, the configuration of the present invention enables anyone to correctly assemble a position adjustment mechanism for adjusting the positions of a backrest and an optional component. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a front perspective view of the chair according to the embodiment. [Diagram 2] FIG. 2 is a rear perspective view of the chair according to the embodiment. [Diagram 3] FIG. 13 is a front perspective view showing the seat disassembled from the support base with the armrests removed; [Figure 4] FIG. 2 is an enlarged perspective view of the periphery of the support base. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. [Figure 8] 1A is a front perspective view of a pressure plate, and FIG. 1B is a rear perspective view of the pressure plate. [Figure 9] 9 is a schematic cross-sectional view taken along line IX-IX in Fig. 6. (A) is a view before the stopper body is attached, and (B) is a view after the stopper body is attached. [Figure 10] 1A is a front perspective view of a stopper body, and FIG. 1B is a rear perspective view of the stopper body. [Figure 11] FIG. 2 is a front perspective view of the back support; [Figure 12] FIG. 2 is a front perspective view showing the backrest in an exploded state. [Figure 13] FIG. 2 is a rear perspective view showing the backrest in an exploded state. [Figure 14]FIG. 2 is a front view of a first upholstery engagement body (A) and a front view of a second upholstery engagement body (B). [Figure 15] 11 is an explanatory diagram showing an engagement state of a first upholstery engagement body with a back frame. FIG. [Figure 16] A rear perspective view of the back frame and lumbar support. [Figure 17] FIG. [Figure 18] This is the first exploded oblique view of the pelvic operating part. [Figure 19] This is the second exploded oblique view of the pelvic operating part. [Figure 20] FIG. [Figure 21] FIG. 21 is a front perspective view showing the headrest in FIG. 20 in an exploded state. [Figure 22] FIG. 22 is a rear perspective view of FIG. 21. [Diagram 23] FIG. 20 is a front perspective view showing a state in which only the clamp portion is removed from the headrest. [Figure 24] 1A is a rear perspective view of a top of a height adjustment mechanism, and FIG. 1B is a front perspective view of the top of the height adjustment mechanism. [Diagram 25] FIG. 4 is a side view showing the state of the top and the cam surface. [Figure 26] 4 is a cross-sectional view showing the state of a top and a cam surface. FIG. [Figure 27] 11 is a cross-sectional view showing a state in which the piece is prevented from falling out by a stopper. FIG. [Figure 28] 11 is a cross-sectional view showing a state in which an unattached piece is restricted by an erroneous attachment prevention stopper. FIG. [Figure 29] FIG. [Diagram 30] 30 is a rear perspective view showing a state in which the decorative frame is removed from FIG. 29. FIG. [Diagram 31] 13 is an explanatory diagram showing a method of attaching the third upholstery engagement body and the fourth upholstery engagement body to the frame body of the attached upholstery. FIG. [Diagram 32] 13 is a rear view of the upholstery to which the third upholstery engagement body and the fourth upholstery engagement body are attached. [Diagram 33] This shows a front view (A) of the fourth upholstery engagement body, a front view (B) of the fourth upholstery engagement body stretched in the longitudinal direction, a front view (C) of the fourth upholstery engagement body compressed in the longitudinal direction, and a front view (D) of the fourth upholstery engagement body bent in the longitudinal direction. [Diagram 34] FIG. 2 is a front perspective view showing the armrest in a disassembled state. [Diagram 35] FIG. 2 is a rear perspective view showing the armrest in a disassembled state. [Diagram 36] FIG. 2 is a front perspective view showing the elbow rest in an exploded state. [Figure 37] This shows a side view (A) of the main part showing the state when the elbow rest is moved rearward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Figure 38] This shows a side view (A) of the main part showing the state when the elbow rest is moved forward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Figure 39] This shows a side view (A) of the main part showing the state when the elbow rest is moved forward and facing inward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Diagram 40] FIG. 11 is an exploded front perspective view of a modified embodiment of the headrest. [Diagram 41] FIG. 11 is an exploded rear perspective view of a modified embodiment of the headrest. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification, "upper" and "lower", "front" and "rear", and "left" and "right" are defined based on a person sitting on seat D of chair A (in other words, "upper" and "lower", "front" and "rear", and "left" and "right" are defined from the perspective of the person sitting).

[0016] This embodiment illustrates a chair A in which the position adjustment mechanism of the present invention is applied to a height adjustment mechanism x5 of a headrest X (as a headrest position adjustment mechanism) that adjusts the height position of the head contact portion x2 relative to the backrest H.

[0017] 1 to 3, a chair A in this embodiment includes legs B, a support base C rotatably supported by the legs B, a seat D disposed on the support base C, a backrest structure F supported so as to be able to tilt backward with respect to the support base C, a headrest X as an optional member attached to the backrest structure F, and an armrest Y attached to the seat D. The backrest structure F includes a back support G supported by the support base C, and a backrest H supported by the back support G.

[0018] Each component of this chair A will be described in detail below.

[0019] (Leg B) The leg B comprises a number of leg blades b2 arranged radially, each having a caster b1 at its tip, and a leg support b3 erected at the base end of each of the leg blades b2. The leg support b3 is extendable in the vertical direction. The leg support b3 has a gas spring (not shown), which supports the support base C so that its position can be changed vertically. The specific shape of the leg B is not particularly limited, and other known configurations can be appropriately adopted.

[0020] (Support base C) FIG. 4 is a perspective view of the peripheral portion of the support base C in FIG. 3. In this embodiment, the support base C is formed in a bottomed box shape. A mounting hole c1 (see FIG. 2) is formed on the rear bottom surface of the support base C. The support base C is attached to the upper part of the leg support b3 by inserting the leg support b3 into the mounting hole c1. In the left-right direction of the support base C, a rotating shaft J1 during rocking operation, a synchronous shaft J2, and a locking shaft J3 for locking the first end of the reaction spring c2 during rocking are hung. The second end of the reaction spring c2 is engaged with a reaction spring receiving portion c3 arranged on the support base C. The rotating shaft J1, the synchronous shaft J2, and the locking shaft J3 all pass through a link plate c4 arranged between the left and right walls. An arm g1 of the back support G is connected to the rotating shaft J1. A seat receiver d1 of seat D is fitted to the synchronous shaft J2 so as to be rotatable around the axis of the synchronous shaft J2. One end of a reaction spring c2 is engaged with the locking shaft J3. The link plate c4 rotates around the rotation shaft J1 as the center of rotation to achieve a locking action. During the locking action of the backrest H, the link plate c4 and the synchronous shaft J2 move the seat D in synchronization with the locking action. In this way, the rotation shaft J1, the synchronous shaft J2, the locking shaft J3, and the link plate c4 form a synchronous locking mechanism, which achieves a synchronous locking action.

[0021] In addition, an arc-shaped long hole c5 is formed in the left and right walls at the front end of the support base C. The shaft body J4 is arranged so as to span the long holes c5 in the left and right direction. The long hole c5 and the shaft body J4 guide the movement of the seat D by the link plate c4 and the synchronous shaft J2 so that the movement is made along a predetermined trajectory when the backrest H is rocked. The shaft body J4 also serves as a part of the forward tilt mechanism of the seat D, which will be described later. A locking force adjustment lever c6 is arranged in the front right part of the support base C to adjust the operating force required for the rocking operation. A locking operation lever c7 is arranged in the rear left part of the support base C to switch the lock on and off at the initial position (standing position) of the rocking operation. The other components of the support base C shown in Figures 3 and 4 are known, so a description thereof will be omitted here.

[0022] (Locus D) As shown in FIG. 3, the seat D includes a seat support d1 as a shell-shaped rotating body, and a seat body d2 and a cushion d3 that are arranged on the seat support d1 so that their front-rear positions can be changed. As shown in FIGS. 5 to 7, a recess d4 with an open bottom is formed in the front part of the bottom surface of the seat support d1. Two protrusions d5 with arcuate bottom surfaces are erected in the recess d4. A shaft body accommodating hole d6 is drilled at the outer side position in the left-right direction of the protrusions d5, and is positioned at the same height position as the height position of the arcuate surface of the protrusions d5. The shaft body J4 is inserted through the left and right shaft body accommodating holes d6. In this state, the upper surface of the shaft body J4 is in contact with the arcuate surface of the protrusions d5. An opening d7 is arranged on the upper surface of the seat support d1 at a planar position that is the outer side of the shaft body accommodating hole d6 in the left-right direction. As shown in the side cross-sectional view of seat D, the spring holder d8 and the spring d9 are housed in the opening d7 on the upper surface of the shaft J4 in the order shown from the side (lower side) of the shaft J4. Also, a pressure plate d10 is attached to the opening d7 to house the spring d9 in a biased state.

[0023] As shown in FIG. 8, the pressing plate d10 is formed in a rectangular shape in a plan view. An upper protrusion d10a that protrudes upward is formed at one end edge portion in the longitudinal direction. A front protrusion d10b that protrudes in the longitudinal direction of the pressing plate d10 is formed at the end face opposite to the end portion on which the upper protrusion d10a is formed. A rear entry portion d7a through which the upper protrusion d10a can pass is formed at the opening d7 of the seat receiver d1, and a fitting hole d7b into which the upper protrusion d10a fits is formed at a position adjacent to the rear entry portion d7a behind the rear entry portion d7a. In addition, a front entry portion d7c into which the front protrusion d10b can enter is formed at a front position of the opening d7. The planar positions of the fitting hole d7b and the front entry portion d7c are aligned with the planar positions of the upper protrusion d10a and the front protrusion d10b of the pressing plate d10. The depth dimension of the rear entry portion d7a is formed to be greater than the longitudinal length dimension of the pressing plate d10.

[0024] After the spring holder d8 and the spring d9 are accommodated in the aforementioned opening d7, the pressing plate d10 is attached to the opening d7 while pressing (compressing) the spring d9 downward with the pressing plate d10. Specifically, the pressing plate d10 is slid backward in a downward open state, and the upper protrusion d10a passes through the fitting hole d7b once, and the pressing plate d10 is moved to a position at the back of the rear entry part d7a until the entire pressing plate d10 is accommodated in the opening d7. After the entire pressing plate d10 is accommodated in the opening d7, the pressing force on the spring d9 is released, and the pressing plate d10 is slid forward, so that the upper protrusion d10a fits into the fitting hole d7b and the front protrusion d10b enters the front entry part d7c, and the pressing plate d10 can be attached to the opening d7 in a state where it is prevented from coming off. In this state, a certain amount of biasing force is generated by the pressure plate d10 on the spring d9, so that the upper protrusion d10a remains engaged with the engagement hole d7b, and the pressure plate d10 will not fall off from the opening d7.

[0025] In this way, the seat support d1 can move back and forth between the top surface height position of the shaft body J4 and the bottom surface height position of the pressure plate d10 within a range where the spring d9 can be compressed, by the shaft body J4 held by the support base C, the spring holder d8 and spring d9 placed on the shaft body J4, and the pressure plate d10. In other words, when the seat occupant applies a downward force (external force) against the biasing force of the spring d9 to the front part of the seat D, the seat D can be tilted forward. When the seat D is tilted forward, the biasing force of the spring d9 increases, and when the external force applied to the seat D is released, the seat D returns to its initial position due to a part of the accumulated biasing force. At this time, the shaft body J4 moves back and forth in an oblique vertical direction along the long hole c5 formed in the support base C.

[0026] As shown in FIG. 5, the central portion of the lower surface of the seat support d1 is provided with a synchronous shaft mounting portion d11, which is a communication portion that communicates the upper surface and the lower surface of the seat support d1. In this embodiment, the synchronous shaft mounting portion d11 has an inclined convex portion d11a as a plurality of inclined surface forming bodies erected toward the lower side of the seat support d1, and an arc-shaped abutment portion d11b as a plurality of abutment portions having an arc-shaped abutment surface. The inclined convex portion d11a and the arc-shaped abutment portion d11b are both formed in a rib shape and are arranged along the length direction of the synchronous shaft mounting portion d11. When mounting the seat support d1 to the synchronous shaft J2, the synchronous shaft J2 is inserted into the synchronous shaft mounting portion d11 along the inclined convex portion d11a, and the outer circumferential surface of the synchronous shaft J2 is abutted against the arc-shaped abutment portion d11b. By bringing the synchro shaft J2 into contact with the arc-shaped contact portion d11b, the seat d1 can be attached to the synchro shaft J2 in an appropriate state.

[0027] FIG. 9 is a cross-sectional view of the main part of the seat d1 attached to the synchronous shaft J2. As is clear from FIG. 9(A), an opening hole d12 communicating with the synchronous shaft mounting part d11 is formed on the upper surface of the seat d1. In this embodiment, the opening hole d12 is disposed at the same longitudinal position as the longitudinal (lateral) position of the synchronous shaft mounting part d11 of the arc-shaped abutment part d11b. The opening hole d12 can also be disposed at a longitudinal position different from the longitudinal (lateral) position of the synchronous shaft mounting part d11 of the arc-shaped abutment part d11b. This opening hole d12 is formed in a shape that intersects with the inclined surface d11x of the inclined protruding part d11a when viewed from the side. More specifically, the inclined protruding part d11a has an inclined surface d11x that extends from a lower surface opening that opens downward and forward to the upper rear. In contrast, the opening hole d12 is formed as an inverted inclined hole that extends from a lower opening that opens downward rearward to an upper frontward direction (inclined in the opposite direction to the inclined surface d11x). As a result, the inclined surface d11x formed by the inclined protrusion d11a and the inner peripheral surface d12x of the opening hole d12 form a V-shape in side view.

[0028] A first engagement recess d12a is formed on the inner peripheral surface d12x of the opening hole d12, and a second engagement recess d12b is formed on the periphery of the opening on the upper surface of the seat holder d1 of the opening hole d12 (see FIG. 6). As shown in FIG. 9(B), a stopper body d13 is attached to the opening hole d12 to prevent the synchronizer shaft J2 inserted into the synchronizer shaft mounting portion d11 from coming off. By attaching the stopper body d13 to the opening hole d12 as shown in FIG. 9(B), a seat holder-synchronizer shaft connection structure 10 is formed as a rotating body connection structure, and the seat holder d1 is rotatably connected along the outer peripheral surface of the synchronizer shaft J2.

[0029] As shown in FIG. 10, the stopper body d13 is formed in a generally L-shaped body in a side view having an upper portion d13a and an inclined portion d13b. The upper surface of the upper portion d13a is formed with a lattice pattern similar to the lattice pattern on the upper surface of the seat support d1. The rear side surface of the upper portion d13a is formed with a rear protruding portion d13c as a convex portion for preventing positional deviation protruding rearward. The inclined portion d13b is formed with the same inclination as the inner peripheral surface d12x of the opening hole d12, and is formed so as to be able to enter the opening hole d12, and an engagement claw d13d is disposed protruding from the front surface of the inclined portion d13b. The engagement claw d13d is formed in a cantilever shape so as to be able to protrude into the front surface of the inclined portion d13b by elastic deformation. A downward protruding portion d13e is formed at the lower end of the inclined portion d13b. A synchro shaft fitting portion d13f having an arc-shaped inner bottom surface is formed by the lower surface side of the upper portion d13a and the rear surface side of the inclined portion d13b.

[0030] The stopper body d13 thus formed is attached by inserting the inclined portion d13b from the upper surface side of the seat d1 along the inner peripheral surface d12x of the opening hole d12. At this time, the engagement claw d13d formed on the front surface of the inclined portion d13b moves along the inner peripheral surface d12x of the opening hole d12 while being elastically deformed. When the engagement claw d13d reaches the position of the first engagement recess d12a formed on the inner peripheral surface d12x of the opening hole d12, the elastic deformation of the engagement claw d13d is restored and the engagement claw d13d is engaged with the first engagement recess d12a, and the stopper body d13 is prevented from coming off. In this state, the rear protrusion d13c is also engaged (engaged) with the second engagement recess d12b formed at the opening of the opening hole d12. That is, the state in which the synchronization shaft J2 is loosely fitted or engaged in the synchronization shaft fitting portion d13f can be released and the movement in two directions is restricted. The downward protrusion d13e is used as a reinforcing portion that reinforces the lower end portion of the synchro shaft fitting portion d13f.

[0031] In this way, even if the seat holder d1 to which the synchronous shaft J2 and the stopper body d13 are attached is pulled upward and a force in the direction of the arrow A in FIG. 9(B) acts, the movement of the seat holder d1 in the direction of the arrow A is restricted by the stopper body d13. This makes it possible to prevent the seat holder d1 from coming off the synchronous shaft J2. If the stopper body d13 is removed from the opening hole d12 of the seat holder d1, the seat holder d1 can be easily removed from the synchronous shaft J2. In this way, the seat holder d1 in this embodiment is advantageous in that it can be attached to and disassembled from the synchronous shaft J2 without using tools. The seat D attached to the synchronous shaft J2 in this way is configured to move in synchronization with the backward tilting movement (rocking movement) of the backrest H by the rotating shaft J1, the link plate c4, and the synchronous shaft J2.

[0032] (Backrest structure F) The backrest structure F comprises a back support G rotatably supported on a support base C, and a backrest H supported on the support base C via the back support G so as to be able to tilt backward.

[0033] (Back support G) As shown in Fig. 11, the back support G includes left and right arms g1 rotatably supported on a rotation axis J1, and a connecting plate g2 that connects the rear ends of the arms g1. The back support G is made of metal, and the arms g1 and the connecting plate g2 are joined by welding.

[0034] The left and right arms g1 are paired and are plate-like extending in the front-rear direction, with shaft holes g3 disposed in the front portions thereof for inserting and fixing the rotating shaft J1 and the synchronous shaft J2. The left and right arms g1 are supported so as to be rotatable about the rotating shaft J1 inserted and fixed in the shaft holes g3. The rear surface (back surface) of the connecting plate g2 is provided with a plurality of bolt insertion holes (not shown) for inserting a plurality of bolts (not shown). A nut portion g4 is fixed by welding to the front side (front surface) of each bolt insertion hole. In addition, a locking operation lever c7 is rotatably attached to the arm g1.

[0035] (Backrest H) As shown in Figures 12 and 13, the backrest H comprises a back frame h1, a back frame h2 arranged in front of the back frame h1, an upholstery h3 stretched over the back frame h2, a lumbar support h4 attached to the back frame h2 at the rear side of the upholstery h3, and a pelvic operating part h5 which positions the back frame h2 in a manner that allows the position of the back frame h2 to be changed in the front-to-rear direction relative to the back frame h1.

[0036] The backrest H is arranged in front of the back frame h1, with the back frame h2 covered with upholstery h3, so that the position can be changed in the front-rear direction. With such a configuration of the backrest H, the back frame h2 as a whole is easily structured to be easily elastically deformed, and the back frame h2 is easily given flexibility to envelop the back of the seated person. The entire backrest H is designed to be able to tilt backward around a rotation axis J1 provided on the support base C. Specifically, the backrest H is supported rotatably around the rotation axis J1 of the support base C via the back support G.

[0037] (back frame h1) The back frame h1 can tilt backward around a rotation axis J1 provided on the support base C, and includes left and right side frame portions h1a, an upper frame portion h1b installed between the upper ends of the left and right side frame portions h1a, left and right lower frame portions h1c extending forward from the lower ends of the left and right side frame portions h1a, respectively, and a lower connecting portion h1d that connects the left and right lower frame portions h1c to each other and is fastened to a connecting plate g2 of the back support body G. The left and right side frame portions h1a, the upper frame portion h1b, the left and right lower frame portions h1c, and the lower connecting portion h1d are molded from synthetic resin and assembled together.

[0038] The left and right side frame portions h1a of the back frame h1 are each shaped as a member that gradually becomes wider toward the bottom. The side frame portions h1a of the back frame h1 are arranged on the back side of the side portion of the backrest surface that is mainly composed of the upholstery h3 stretched over the back frame h2. The left and right side frame portions h1a are roughly doglegged when viewed from the side and from the front, and the upper and lower portions of the left and right side frame portions h1a are continuous via a bent portion.

[0039] The upper frame portion h1b of the back frame h1 is disposed on the upper back side of the backrest surface, and is a structural frame that connects the upper ends of the side frame portions h1a to each other. The upper frame portion h1b is provided with an element that constitutes an upper connection portion for attaching the upper end of the back frame h2. That is, the front surface of the upper frame portion h1b is provided with a plurality of recesses h1e and protrusions h1f that open forward in the left-right direction. The bottom surface of the upper frame portion h1b is provided with bolt insertion holes h1g that communicate with each recess h1e.

[0040] The left and right lower frame portions h1c of the back frame h1 are continuous with the left and right side frame portions h1a, and their front portions extend from the lower ends of the left and right side frame portions h1a to a position corresponding to the rotation axis J1. That is, the left and right lower frame portions h1c are partially located outside the left and right arms g1 of the back support G. In other words, the left and right lower frame portions h1c extend in the front-rear direction, and their front ends extend to both sides of the support base C arranged below the seat D. In addition, a second bracket h1h is provided upright on the lower frame portion h1c.

[0041] (back frame h2) The back frame h2 disposed in front of the back frame h1 is attached to the back frame h1 at the upper end and the lower left and right sides. On the back side of the upper end of the back frame h2, a convex part h2a that fits concavely into the concave part h1e formed in the upper frame part h1b of the back frame h1 and a concave part h2b that fits into the convex part h1f are disposed so as to correspond to the concave part h1e and the convex part h1f. In addition, an engagement groove h2c is disposed on the back side of the back frame h2 for engaging the upholstery h3 at a location corresponding to the side frame part h1a and the lower frame part h1c of the back frame h1. A first bracket h2d that is connected to the pelvic operation part h5 connected to the back frame h1 is formed on the lower left and right rear parts of the back frame h2. That is, the back frame h2 is movably connected to the back frame h1 via the pelvic operation part h5.

[0042] A first upholstery engagement body h6 as shown in FIG. 14(A) is attached to the upper edge of the upholstery h3, which is stretched over the back frame h2, by sewing. The first upholstery engagement body h6 is a long, synthetic resin thin plate material formed to a width dimension approximately equal to the width dimension of the upper end of the back frame h2. The first upholstery engagement body h6 is formed with mounting parts h6a and h6b having openings matching the shapes of the convex part h2a and the concave part h2b at positions corresponding to the convex part h2a and the concave part h2b on the rear side of the upper end of the back frame h2. The mounting part h6a is formed in a shape that opens at the edge in the width direction of the first upholstery engagement body h6, and the mounting part h6b is formed in a through-hole shape for the first upholstery engagement body h6.

[0043] Furthermore, an insertion hole h6c through which the engagement pin KP is inserted is formed in the center of the upper end of the back frame h2 of the first upholstery engagement body h6. A cut line h6d is formed around the insertion hole h6c so as to surround the insertion hole h6c in an inverted U-shape, allowing localized elastic deformation when the engagement pin KP is inserted into the insertion hole h6c and preventing the first upholstery engagement body h6 from floating up to the upper end of the back frame h2. A second upholstery engagement body h7 for insertion into the engagement groove h2c as shown in Fig. 14(B) is attached by sewing to the outer peripheral edge of the side portion and lower end of the upholstery h3.

[0044] In this embodiment, the second upholstery engaging body h7 is formed with a slit h7a for tag positioning. The slit h7a for tag positioning is formed with the same width dimension as the tag T. If the tag T is inserted into the slit h7a and sewn to the upholstery h3, the tag T can be easily attached to a predetermined position on the chair A. The tag T can display the name of the manufacturer or brand of the chair A, a video playback page for explaining how to use the chair A, or a URL for an advertising page or a page for directing to an SNS (social network service).

[0045] The following describes how the upholstery h3, which has the first upholstery engaging body h6 and the second upholstery engaging body h7 sewn to the entire outer periphery, is stretched over the back frame h2. The back frame h2 is wrapped with the upholstery h3 from the front side of the back frame h2, and the mounting parts h6a and h6b of the first upholstery engaging body h6 at the upper edge of the upholstery h3 are aligned with the convex part h2a and the concave part h2b of the back frame h2 as shown in FIG. 15. At this time, the mounting part h6a is placed in a state where it enters from above the convex part h2a. In this state, the convex part h2a of the back frame h2 fits into the concave part h1e of the back frame h1, and the concave part h2b of the back frame h2 fits into the convex part h1f of the back frame h1, and the back frame h2, the first upholstery engaging body h6, and the back frame h1 are engaged using the engagement pin KP. As a result, the upholstery h3 is clamped in a positioned state by the back frame h1 and the back frame h2, and the upper ends of the back frame h1, back frame h2, and upholstery h3 are integrated. The part of the upholstery h3 other than the upper end part is attached by inserting the second upholstery engagement body h7 into the engagement groove h2c formed along the outer periphery of the side and bottom part of the back side of the back frame h2. As mentioned above, the lower part of the back frame h2 is rotatably connected to the back frame h1 via the pelvic operation part h5.

[0046] (Lumbar support h4) As shown in Fig. 16, a lumbar support h4 is disposed behind (on the back side) the upholstery h3 stretched over the back frame h2. The lumbar support h4 is attached to the lower part of the back side of the back frame h2, spanning the width of the back frame h2. As shown in Fig. 17, the lumbar support h4 has a retaining portion h4a that abuts and holds the waist of a seated person, and a narrow insertion portion h4b formed at both ends in the width direction. A C-shaped recess h4c is formed in the insertion portion h4b. The lumbar support h4 is attached by inserting the insertion portion h4b into an insertion opening h2e formed in the back frame h2. A mating protrusion (not shown) that fits into the recess h4c is formed at the back side of this insertion opening h2e. Therefore, by inserting the insertion portion h4b into the insertion opening h2e, the recess h4c of the lumbar support h4 and the mating protrusion of the back frame h2 are engaged with each other, and the lumbar support h4 is attached to the back frame h2 in a state where it is prevented from slipping out.

[0047] The lumbar support h4 attached to the back frame h2 can be released from the recessed portion h4c of the lumbar support h4 and the protruding portion of the back frame h2 by inserting a flat head screwdriver or the like through the insertion opening h2e between the recessed portion h4c of the lumbar support h4 and the protruding portion of the back frame h2. In other words, the lumbar support h4 is detachable from the back frame h2.

[0048] (Pelvic operation part h5) Next, the schematic configuration of the pelvic operation part h5 and the schematic operation by the pelvic operation part h5 will be described. As described above, the back frame h2 to which the lumbar support h4 is attached can change the position of the back frame h2 relative to the back frame h1 by the pelvic operation part h5. As shown in Figs. 18 and 19, the pelvic operation part h5 includes a main body part (first main body part) h5a, an operation lever h5b, a stopper member h5c, a coil spring h5e as a biasing member, a first screw h5f, and a main body part (second main body part) h5g. The second bracket h1h includes a locking part h5d. The main body part h5a is formed with a cylindrical part h5h and a first rotating shaft h5i. The operation lever h5b is formed with a grip part that stands upright in a direction perpendicular to the shaft body h5j, and is assembled to the main body part h5a by inserting the shaft body h5j from the small diameter side of the cylindrical part h5h. The shaft body h5j is rotatable inside the cylindrical portion h5h.

[0049] An insertion hole h5k is formed in the center of the stopper member h5c. In the present embodiment, the stopper member h5c has concave and convex portions formed at intervals of a predetermined angle (for example, 60 degrees) in the circumferential direction with the insertion hole h5k as the center point. The second bracket h1h on which the locking portion h5d is provided is erected on the lower left and right rear sides of the back frame h1 with the engagement surface facing outward in the left and right direction. An insertion hole h5l is formed in the center of the locking portion h5d. In addition, the locking portion h5d has an engagement surface of the same shape (corresponding shape) as the stopper member h5c, and is paired with the stopper member h5c, and can be engaged with each other by concave and convex. When the engagement surfaces of the stopper member h5c and the locking portion h5d are engaged with each other, the respective insertion holes h5k and the insertion holes h5l communicate with each other with their center points on the same straight line.

[0050] The coil spring h5e and the stopper member h5c are housed in the large diameter side of the cylindrical portion h5h of the main body h5a in the order described. The stopper member h5c is disposed in contact with the other end of the coil spring h5e. In this state, the stopper member h5c is fixed to the screw hole h5m of the operating lever h5b by screwing with the first screw h5f. In addition, the large diameter side opening of the cylindrical portion h5h of the main body h5a is formed with an engagement surface h5n with which the stopper member h5c engages, and the stopper member h5c engages with this engagement surface h5n. The stopper member h5c is in a state of protruding from the large diameter side opening of the cylindrical portion h5h.

[0051] The main body part h5a, which houses the operation lever h5b, the coil spring h5e, and the stopper member h5c, is assembled in a state in which the exposed part of the stopper member h5c is engaged with the locking part h5d. Then, the second rotation shaft h5o of the main body part (second main body part) h5g is inserted from the inside of the insertion hole h5l of the locking part h5d, and the second screw h5p is screwed into the female screw part h5q formed in the main body part h5a, so that the pelvic operation part h5 is attached to the back frame h1. In the pelvic operation part h5 attached in this way, the stopper member h5c is always biased toward the locking part h5d by the biasing force of the built-in coil spring h5e, and unintended movement of the back frame h2 (lumbar support h4) is restricted. As a result, to change the position of the back frame h2 relative to the back frame h1, it is necessary to rotate the operation lever h5b of the pelvic operation part h5.

[0052] A tapered surface h5r is provided at the base of the shaft h5j of the operating lever h5b along the outer circumferential surface of the shaft h5j. Tapered surfaces h5s are provided at 180 degree intervals along the circumferential direction inside the cylindrical portion h5h of the main body h5a into which the shaft h5j of the operating lever h5b is inserted. When such an operating lever h5b is rotated inside the cylindrical portion h5h, the tapered surface h5r and the tapered surface h5s slide against each other, and the protrusion amount of the operating lever h5b in the axial direction of the cylindrical portion h5h increases. This compresses the coil spring h5e, reducing the biasing force that presses the stopper member h5c against the locking portion h5d, allowing the operating lever h5b to rotate and releasing the engagement between the stopper member h5c and the locking portion h5d.

[0053] In this manner, when the engagement force between the stopper member h5c and the locking portion h5d is reduced, the rotation of the operation lever h5b allows the stopper member h5c to rotate while sliding the engagement surface between the locking portion h5d and the stopper member h5c. This causes the spine frame h2 to rotate due to the action of the shaft body h5j formed on the main body h5a and connected to the first bracket h2d of the spine frame h2. The pelvic operation portion h5 in this embodiment can provide three positions, but the number of positions that can be provided by the pelvic operation portion h5 can be changed as appropriate depending on the design of the engagement surface between the stopper member h5c and the locking portion h5d.

[0054] In addition, a standing wall h5t is erected in a required length range along the outer circumferential surface of the shaft body h5j at a required distance from the radial outside of the shaft body h5j of the main body part (second main body part) h5g. When the spine frame h2 is in a specified position by the pelvic operation part h5, the first bracket h2d of the spine frame h2 is prevented from coming off by the standing wall h5t. When removing the spine frame h2 from the spine frame h1 with the pelvic operation part h5 attached, the connection by the pin at the upper end of the spine frame h1 and the spine frame h2 is released, the upper end of the spine frame h2 is tilted forward, and the spine frame h2 is pulled out with the forward tilt angle of the spine frame h2 relative to the spine frame h1 set to a specified angle. This releases the prevention of the first bracket h2d of the spine frame h2 from coming off by the standing wall h5t, and the spine frame h2 can be removed from the spine frame h1. By setting the positional relationship between the first bracket h2d and the standing wall h5t in this way, the back frame h2 cannot be removed from the back frame h1 within the normal range of use.

[0055] (Headrest X) A headrest X as an optional member is removably attached to the upper end of the backrest H. As shown in Fig. 20, the headrest X has an attachment part x1 to the backrest H and a head contact part x2 which is rotatable around a horizontal axis extending in the left-right direction at the upper end of the attachment part x1.

[0056] As shown in Figures 20 to 23, the mounting portion x1 is equipped with a clamp portion x3 that clamps the upper end of the backrest H, a slider portion x4 that is held so as to be able to slide vertically relative to the clamp portion x3, and a height adjustment mechanism x5 that serves as a headrest position adjustment mechanism (optional component position adjustment mechanism) that adjusts the height position of the head contact portion x2 relative to the backrest H.

[0057] The clamp part x3 as a base has a first member x3a formed with a first locking part x3x that locks onto the upper surface of the upper end of the backrest H, and a second member x3b formed with a second locking part x3y that locks onto the lower surface of the upper end of the backrest H, and is integrated by screwing from the underside of the front face with the backrest H sandwiched between the first locking part x3x and the second locking part x3y. A top housing part x3z is formed on the back side of the first member x3a to house a top x5a, which is part of the height adjustment mechanism x5, and a biasing spring x5b as a biasing member that biases the top x5a toward the slider part x4 as a slider. The spring x5b and the piece x5a are accommodated in the piece accommodating section x3z formed in the bottomed cylinder in the order described above from the inner bottom surface side, and the piece x5a, which is urged by the spring x5b, is accommodated in a state where a part of the piece x5a protrudes from the opening of the piece accommodating section x3z. On the rear (back) surface side of the first member x3a, a guide rail clamping section x3c is formed along the height direction, which clamps in the width direction two rows of guide rails x4a erected along the height direction on the front side of the slider section x4. The slider section x4 is slidably moved while being guided in the height direction by clamping the guide rails x4a between the guide rail clamping section x3c.

[0058] 21 to 24, the height adjustment mechanism x5 in this embodiment includes a piece x5a, a biasing spring x5b, a cam plate x5g as a cam portion, a stopper x5j to prevent slipping out, and a stopper x5k to prevent erroneous installation. The height adjustment mechanism x5 will be described in detail below.

[0059] The piece x5a is formed as a block body made of synthetic resin. Elements of the height adjustment mechanism x5 are formed on one surface of the piece x5a. A spring accommodating hole x5c for accommodating the biasing spring x5b is disposed on the surface of the piece x5a on the side of the clamp portion x3. Since the depth dimension of the spring accommodating hole x5c is sufficiently smaller than the length dimension of the biasing spring x5b, even if the biasing spring x5b is accommodated in the spring accommodating hole x5c, the biasing spring x5b protrudes reliably from the outer surface of the piece x5a. On the surface of the piece x5a opposite the spring accommodating hole x5c, which faces the cam plate x5g, a mountain-shaped portion x5d, two ribs x5e, an inclined rib x5f, and a lower surface rib x5m as a contact piece are formed, which are elements of the height adjustment mechanism x5.

[0060] The mountain-shaped portion x5d is formed at both ends of the frame x5a in the width direction. The slopes from the base to the top of the mountain-shaped portion x5d are formed to have different slopes. In this embodiment, the slope angle of the upper slope of the mountain-shaped portion x5d in the frame x5a accommodated in the frame accommodating portion x3z in the normal state shown in FIG. 24(A) is steeper than the slope angle of the lower slope of the mountain-shaped portion x5d, and the shape is asymmetric in the height position adjustment direction of the head abutment portion x2 (extension direction of the cam plate x5g). In addition, a rib x5e extending in the height position adjustment direction of the head abutment portion x2 is erected on the inner side of the width direction of the two mountain-shaped portions x5d. The height of the rib x5e relative to the block portion of the frame x5a is a constant height and is formed lower than the top height of the mountain-shaped portion x5d. In other words, the rib x5e is formed higher in the portion other than the top of the mountain-shaped portion x5d. The inclined rib x5f is erected at the middle position in the left-right direction of the rib x5e.

[0061] The inclined rib x5f is formed on an inclined plate whose protruding height gradually increases from the upper surface side to the lower surface side of the piece x5a, and the protruding height at the lower end position is equal to the protruding height of the rib x5e. In addition, the lower surface rib x5m is erected at the same protruding height as the rib x5e in an arrangement that connects the ends of the two ribs x5e and one of the inclined ribs x5f (the lower surface side of the piece x5a). In this embodiment, the lower surface rib x5m is erected on the lower edge side, which is the side of one intersecting edge that intersects with the cam plate x5g in the piece x5a, so as to be flush with the lower surface of the piece x5a. As is clear from FIG. 24(A), the two ribs x5e and the lower surface rib x5m, which have the same protruding height, form an inverted U-shaped portion that opens upward. The protruding height of this inverted U-shaped portion is uniform in the inverted U-shaped portion.

[0062] Between the two rows of guide rails x4a on the front side of the slider portion x4, two rows of cam plates x5g are erected in parallel with a required interval in the left-right direction along the height direction. The cam plate x5g has a plurality of convex portions x5h formed in a mountain shape erected at equal intervals, and a large convex portion x5i that is taller than the other convex portions x5h is arranged at the lower end of the cam plate x5g. In this way, the cam plate x5g moves the top x5a in the up-down direction while moving it toward and away from the top x5a in the direction opposite to the direction in which the top x5a is urged by the urging spring x5b. In addition, the upper end of the cam plate x5g is formed into a U-turn portion x5x toward the inside in the width direction. The rib x5e that moves together with the top x5a is positioned so as to abut against this U-turn portion x5x, and functions as a stopper that regulates the lower limit height position of the head abutment portion x2. In this embodiment, the inclined surface of the convex portion x5h has an asymmetrical shape in which the inclination angle of the lower inclined surface is larger than the inclination angle of the upper inclined surface, and fits concavely with the mountain-shaped portion x5d of the piece x5a in the normal state as shown in Figures 25 and 26. Similarly, the inclination angle of the lower inclined surface of the large convex portion x5i is larger than the inclination angle of the upper right inclined surface.

[0063] Further, on the lower portion of the cam plate x5g, anti-slip stoppers x5j are formed in a direction perpendicular to each other toward the other cam plate x5g. At the lower end position of the cam plate x5g, erroneous installation prevention stoppers x5k are erected parallel to the anti-slip stoppers x5j in the central portion in the width direction of the two rows of cam plates x5g (inner portion of the cam plates x5g). The height of the anti-slip stoppers x5j is formed to be the same as the protruding height of the cam plate x5g at the same height position. The erroneous installation prevention stoppers x5k are formed sufficiently lower than the protruding height of the convex portion x5h and sufficiently narrower than the arrangement interval of the two cam plates x5g.

[0064] A method of mounting the top x5a on the cam plate x5g (a method of mounting the slider part x4 on the clamp part x3) will be described. With the top x5a in the normal state as shown in Figs. 24 and 25, the mountain-shaped part x5d is slid on the cam surface from the lower end of the cam plate x5g. Then, the top x5a can slide upward on the cam plate x5g without interfering with the stopper x5k for preventing erroneous mounting and the stopper x5j due to the opening of the inverted U-shaped part consisting of the rib x5e and the lower surface rib x5m and the inclined surface of the inclined rib x5f. As shown in Figs. 25 and 26, the top x5a mounted on the cam plate x5g in the normal state can be protruded and inserted from the top housing part x3z (can move toward and away from the cam plate x5g) within the protruding height range of the cam plate x5g due to the biasing force of the biasing spring x5b.

[0065] Therefore, when the top x5a is slid on the cam surface of the cam plate x5g against the biasing force of the biasing spring x5b, the top x5a fits into the cam surface of the cam plate x5g with a click feeling at the intervals of the projections x5h. In this embodiment, the slide position holder x5p is composed of the top x5a, the biasing spring x5b, and the cam plate x5g. By selecting the fitting position of the top x5a, the protrusion amount of the slider part x4 from the clamp part x3 (the height position of the head contact part x2 relative to the upper end of the backrest H) can be adjusted. When the rib x5e of the top x5a reaches the position of the U-turn part x5x, further movement of the top x5a in the same direction (movement to bring the head contact part x2 closer to the backrest H) is restricted, and the slider part x4 is restricted to a position where it has a minimum protruding height relative to the clamp part x3. When the top x5a is attached to the cam plate x5g in the normal state, the lower surface x5l, which is the lowest part of the top x5a formed on a flat surface, abuts against the stopper x5j, as shown in Figure 27. This allows the head abutment portion x2 to maintain the maximum height position relative to the backrest H and prevents the slider portion x4 from slipping out of the clamp portion x3.

[0066] In contrast, when the top x5a is in an irregular state (a state in which the state shown in FIG. 24 is inverted upside down so that the opening of the inverted U-shaped portion formed by the rib x5e and the lower rib x5m faces downward: a state in which the clamp part x3 is upside down relative to the slider part x4), the state shown in FIG. 28 is reached, and the top x5a is restricted from entering the cam plate x5g. Specifically, when the top x5d tries to ride up onto the cam surface of the cam plate x5g, the lower rib x5m abuts against the mis-installation prevention stopper x5k, and the top x5a is restricted from entering the cam plate x5g. This makes it impossible for the top x5a to enter the cam surface of the cam plate x5g, and it is possible to prevent the clamp part x3 from being mis-installed on the slider part x4.

[0067] As shown in Figures 29 and 30, the head contact portion x2 includes a frame x6 and an upholstery x7. As shown in the two rear perspective views, the frame x6 includes an upholstery retaining frame x6a that retains the upholstery x7 and a decorative frame x6b that is attached to the rear surface (rear surface) of the upholstery retaining frame x6a. A connecting portion x6c that connects to the slider portion x4 is disposed on the upholstery retaining frame x6a. This connecting portion x6c can have a known configuration, and therefore will not be described here. A tongue piece x6d is provided around the rear surface of the upholstery retaining frame x6a along the outer periphery of the upholstery retaining frame x6a. There is a gap between this tongue piece x6d and the upholstery retaining frame x6a, and the outer periphery of the upholstery x7 (the third upholstery engaging body x7b and the fourth upholstery engaging body x7c) is housed and held in this gap (see Figure 31).

[0068] As shown in FIG. 32, the upholstery x7 in this embodiment is attached by sewing the third upholstery engagement body x7b and the fourth upholstery engagement body x7c along the outer periphery of the upholstery body x7a to the upholstery main body x7a. The third upholstery engagement body x7b is a known structure formed from a simple synthetic resin thin plate material. As shown in FIG. 33, the fourth upholstery engagement body x7c has X-shaped through holes x7d formed at regular intervals along the length direction and has notches x7e aligned with the center parts of the through holes x7d. The notches x7e are formed independently of the through holes x7d from both ends of the fourth upholstery engagement body x7c in the width direction toward the inside in the width direction. In this way, the fourth upholstery engagement body x7c is in a state where the material (base) in the width direction is missing due to the through holes x7d and the notches x7e, so that the through holes x7d and the notches x7e are elastically deformed by an external force.

[0069] In addition, through holes x7d are formed at regular intervals in the length direction in the width direction center of the fourth upholstery engagement body x7c, but the width direction inner end of the cutout portion x7e does not reach a predetermined width range based on the width direction center line. Therefore, a large plate portion (unprocessed portion) can be left in the width direction center of the fourth upholstery engagement body x7c. This allows a large seam allowance to be provided when sewing the fourth upholstery engagement body x7c to the upholstery main body x7a. In addition, the cutout portion x7e of the fourth upholstery engagement body x7c has a large cutout amount in the length direction at both width direction ends, making it easy to deform when subjected to external forces. In this way, the fourth upholstery engagement body x7c has a large seam allowance to reduce fraying of the upholstery main body x7a, while also being shaped to be easily deformed.

[0070] By adopting such a fourth upholstery engagement body x7c, the fourth upholstery engagement body x7c can be expanded and compressed in the length direction of the fourth upholstery engagement body x7c together with the upholstery main body x7a (Fig. 33(B), (C)). In addition, the fourth upholstery engagement body x7c can be bent in the same plane in the length direction (Fig. 33(D)). Due to these characteristics of the fourth upholstery engagement body x7c, the fourth upholstery engagement body x7c can easily deform even in a curved portion with a small curvature that the second upholstery engagement body h7 could not handle, so the fourth upholstery engagement body x7c can be made to follow the curved portion. By using such a fourth upholstery engagement body x7c, the upholstery main body x7a can be engaged with the fourth upholstery engagement body x7c in the gap between the upholstery holding frame x6a and the tongue piece x6d. This reliably prevents the upholstery main body x7a from protruding from the upholstery holding frame x6a even after long-term use.

[0071] In this embodiment, the third upholstery engagement body x7b and the fourth upholstery engagement body x7c are attached along the outer periphery of the upholstery main body x7a as shown in Fig. 32, but it is also possible to adopt a configuration in which only the fourth upholstery engagement body x7c is attached. In short, it is sufficient that the third upholstery engagement body x7b or the fourth upholstery engagement body x7c can be engaged with the entire outer periphery of the upholstery main body x7a in the gap between the upholstery retaining frame x6a and the tongue piece x6d.

[0072] (Armrest Y) In this embodiment, an armrest Y is removably attached to the seat D of the chair A. As shown in Figures 34 and 35, the armrest Y in this embodiment includes a seat attachment portion y1, a height adjustment tube y2, a sliding tube y3, an armrest y4, an operating lever y5, and a height position holding portion y6.

[0073] The seat attachment part y1 has a seat fixing part y1a and a tubular part y1b, and is formed into an L-shape by the seat fixing part y1a and the tubular part y1b, which has an open top surface. A screw hole y1c is arranged in the seat fixing part y1a, which penetrates in the vertical direction, and is attached to the seat D by aligning the screw hole y1c with a screw hole (not shown) formed in the bottom surface of the seat D and fastening a screw y1d from the bottom surface of the screw hole y1c. The tubular part y1b has an open top surface, and houses the height adjustment tube y2 and the slide tube y3 in an assembled state, and the tubular part y1b and the height adjustment tube y2 are fixed by a known method.

[0074] The height-adjusting tube y2 in this embodiment is formed in a shape in which a portion of the required height range is cut out from the bottom of the front half. A plurality of through holes y2b are drilled at regular intervals in the height direction in the rear peripheral surface y2a of the height-adjusting tube y2. As is clear from FIG. 36, two through holes y2b are arranged at the same height position so as to sandwich a rib y2c extending in the height direction from the left and right directions. The rib y2c is in a state of protruding from the front side of the rear peripheral surface y2a. A slide tube y3 is inserted into the height-adjusting tube y2 so as to be removable.

[0075] The slide tube y3 has a tube portion y3a inserted into the height adjustment tube y2 and a shell-shaped elbow support portion y3b that supports the elbow pad y4. A front groove y3d extending in the height direction is formed on the front peripheral surface y3c of the tube portion y3a. A rear groove y3f extending in the height direction is formed on the rear peripheral surface y3e of the tube portion y3a. An opening y3g is formed in the lower part of the rear peripheral surface y3e so as to divide the rear groove y3f. The tube portion y3a of the slide tube y3 thus formed is inserted into the height adjustment tube y2 with the rib y2c fitted into the rear groove y3f.

[0076] The height position holding part y6 has a main body y6a, an engagement claw y6b, and a biasing spring y6c. An engagement piece y6d that engages with a front groove y3d formed in the slide tube y3 is formed on the front surface of the main body y6a. The biasing spring y6c and the engagement claw y6b are arranged on the rear surface of the main body y6a in the order described above. That is, the engagement claw y6b is biased in a direction protruding from the rear surface of the main body y6a by the biasing force of the biasing spring y6c arranged between the main body y6a and the engagement piece y6d. The height position holding part y6 thus formed is accommodated from the lower opening of the slide tube y3. The height position holding part y6 is positioned and fixed to the slide tube y3 with the engagement piece y6d engaged with the front groove y3d and the engagement claw y6b exposed from the opening y3g of the slide tube y3. Therefore, when the slide tube y3 is inserted into the height adjustment tube y2 as described above, the engagement claws y6b engage with the two through holes y2b at the same height position, and the slide tube y3 is fixed to the height adjustment tube y2 with the rib y2c inserted into the rear groove y3f.

[0077] The height position holding portion y6 attached to the slide tube y3 and engaged with the height adjustment tube y2 is connected to the operation lever y5 by a wire y7. More specifically, the operation lever y5 is connected to the engagement claw y6b by the wire y7. That is, when the operation lever y5 is rotated by the seat occupant, the engagement claw y6b is slid by the wire y7 in the opposite direction to the direction in which it is biased by the biasing spring y6c. When the seat occupant rotates the operation lever y5, the engagement between the engagement claw y6b and the through hole y2b of the height adjustment tube y2 is released. The seat occupant can lift up a part of the slide tube y3 from the height adjustment tube y2 by lifting the elbow support portion y3b while rotating the operation lever y5.

[0078] As shown in Fig. 36, the elbow pad y4 is composed of an elbow pad receiving portion y21 formed by stacking a first path body y4a and a first holding body y4b in the vertical direction, and an elbow pad main body y22 formed by stacking a second path body y4c, a second holding body y4d, and an elbow pad pad y4e in the vertical direction. The elbow pad main body y22 can slide in the front-rear direction relative to the elbow pad receiving portion y21. One guide groove y4m is formed on the rear side of the elbow pad main body y22, and the fixed shaft N2 fixed to the elbow pad receiving portion y21 enters one guide groove y4m. The other guide groove y4j is formed on the front side of the elbow pad receiving portion y21, and the movable shaft N1, which is a shoulder screw fixed to the nut holding portion y4n of the elbow pad y4, enters the other guide groove y4j.

[0079] The first path body y4a has a main body y4g in which an opening y4f is formed, an island forming body y4h having a planar area smaller than that of the opening y4f at the center of the opening y4f, and a holding member y4i for holding the island forming body y4h in a floating state at the planar center of the opening y4f. As shown in the figure, the main body y4g and the island forming body y4h form a ring-shaped (approximately square-shaped) other guide groove y4j. The holding member y4i is formed in a substantially U-shape that avoids the planar position of the other guide groove y4j within a required height range.

[0080] In addition, a resistance imparting body y4k is arranged in a part of the circumferential length range of the inner circumferential surface of the opening y4f of the first holding body y4b, protruding inward of the other guide groove y4j to narrow a predetermined portion of the other guide groove y4j. The resistance imparting body y4k is formed on the first holding body y4b as a spring body having elasticity and a π shape in a plan view, but is not limited to this form and may be formed of, for example, an elastic material. The resistance imparting body y4k can also be formed on the first path body y4a instead of the first holding body y4b. The width dimension of the other guide groove y4j in the range where the resistance imparting body y4k is arranged is narrower than the width dimension of the other guide groove y4j in the range where the resistance imparting body y4k is not arranged. When the movable shaft N1 enters the range in which the resistance imparting body y4k is disposed of the other guide groove y4j, the outer circumferential surface of the movable shaft N1 passes through the range in which the resistance imparting body y4k is disposed while elastically deforming the resistance imparting body y4k, so that the resistance during movement is greater in this range than in other ranges. In this embodiment, the first path body y4a is formed separately from the first holding body y4b and is integrally engaged with the first holding body y4b by an engagement piece y4l formed on the first holding body y4b, but the first path body y4a and the first holding body y4b can also be formed integrally.

[0081] The second path body y4c has one guide groove y4m formed in an S-shape on the rear side, a nut holding portion y4n that holds the nut N1a screwed with the movable shaft N1 that enters the one guide groove y4m and moves within the one guide groove y4m, an opening hole y4o for mounting the operating lever y5, and a mounting portion y4p. One guide groove y4m is formed in an S-shape in a plan view, and is configured so that the initial direction from the rear to the front is approximately the same as one of the directions of the ring shape in the other guide groove y4j. This allows the elbow rest main body y22, which is composed of the second path body y4c, the second holding body y4d, and the elbow rest pad y4e, to move along an S-shaped track that is movable in both the front-rear and left-right directions. In addition, the fixed shaft N2 that enters the one guide groove y4m is formed to be wider than the width dimension of the one guide groove y4m, and an O-ring N2b is disposed between the washer N2a placed on the upper surface of the one guide groove y4m. When the shaft portion N2c of the fixed shaft N2 moves in one guide groove y4m, the elastic deformation of the O-ring N2b prevents rattling in the vertical direction between the shaft portion N2c and the second path body y4c.

[0082] The nut N1a, which is screwed with a male screw portion formed on the small diameter portion of the movable shaft N1, is accommodated in the nut holding portion y4n in a fixed state. An O-ring N1c is disposed between the nut N1a and the washer N1b, and a sliding resistance is applied by the elastic deformation of the O-ring N1c that occurs when the movable shaft N1 rotates around the other guide groove y4j.

[0083] The opening hole y4o is formed on the front peripheral surface of the second path body y4c. The grip portion y5a of the operation lever y5 is inserted into the opening hole y4o. The mounting portion y4p is formed in a plate-like body having an opening that rotatably engages with the rotation shaft y5b arranged on the operation lever y5, and is erected on the upper surface of the second path body y4c in alignment with both ends of the rotation shaft y5b in the longitudinal direction. The opening hole y4o is formed to a height dimension necessary to allow the operation lever y5 to rotate within a predetermined angle range in the vertical direction. A thick portion y5c is formed at the base of the grip portion y5a of the operation lever y5 to close the gap between the opening hole y4o and the grip portion y5a, preventing foreign matter from entering through the gap between the operation lever y5 and the opening hole y4o.

[0084] The second holding body y4d is formed in a flat plate shape. A plurality of engagement pieces y4r are formed on the outer periphery of the second holding body y4d to engage with the engagement parts y4q formed on the second path body y4c. By engaging the engagement pieces y4r of the second holding body y4d with the engagement parts y4q of the second path body y4c, the upper surface of the second path body y4c is closed, preventing the intrusion of foreign matter into the second path body y4c. In addition, an elbow pad y4e is removably attached to the upper surface of the second holding body y4d by a known method.

[0085] The operating lever y5 is rotatably attached to the second path body y4c as described above. A wire engaging portion y5d is provided on the rotation shaft y5b of the operating lever y5, and a first end of the wire y7 is connected to the wire engaging portion y5d. The wire y7 is pulled into the inside of the slide tube y3 from one guide groove y4m of the second path body y4c, and a second end of the wire y7 is connected to the engaging claw y6b of the height position holding portion y6. By adopting a form in which the rotational movement of the operating lever y5 is transmitted to the height position holding portion y6 by the wire y7 in this way, the operating lever y5 can be disposed on the elbow pad y4e (second path body y4c) that can move back and forth and left and right. In addition, by using one guide groove y4m to route the wire y7 in the elbow pad y4, it is also possible to reduce bending of the wire y7, and the operating lever y5 can be operated smoothly regardless of the position of the elbow pad y4e.

[0086] As shown in FIG. 37 and FIG. 38, when the elbow rest body y22 moves from the rear to the front, the elbow rest body y22 first moves along the S-shape of one guide groove y4m located on the rear side. On the other hand, the movable shaft N1 moving along the other guide groove y4j together with the elbow rest body y22 reaches the place where the resistance imparting body y4k is arranged in the other guide groove y4j (the front end face) and feels resistance. When the elbow rest body y22 moves from the front to the rear, it can move through either side of the ring-shaped other guide groove y4j provided on the front side. In this way, by making the other guide groove y4j ring-shaped, the seated person can experience various movement paths of the elbow rest body y22. Also, at this time, the movable shaft N1 moving along the other guide groove y4j together with the elbow rest body y22 moves from the place where the resistance imparting body y4k is arranged in the other guide groove y4j to the place where the resistance imparting body y4k is not arranged, so a sense of resistance is felt at the beginning of the movement, and then the sense of resistance disappears and the movement can be performed.

[0087] The range in which the resistance imparting body y4k is arranged in the other guide groove y4j has a narrower path width than the other parts, and when the movable shaft N1 passes through this range, the resistance imparting body y4k is pushed and spread by the outer periphery of the movable shaft N1 as it passes through. In this way, by elastically deforming the resistance imparting body y4k, a sense of resistance to the movement of the movable shaft N1 can be imparted, which can create a sense of luxury for the chair A and also allows the seated person to easily recognize the current position of the armrest y4 and the direction in which it will move from now on. In this embodiment, since the sliding resistance is imparted by the elastic deformation of the O-ring N1c that occurs when the movable shaft N1 moves around the other guide groove y4j, it is sufficient to provide resistance when the movable shaft N1 moves by providing either the O-ring N1c or the resistance imparting body y4k.

[0088] As shown in Figures 37 to 39, in this embodiment, when the elbow rest main body y22 is moved from rear to front, it follows a movement trajectory along one of the S-shaped guide grooves y4m, such that the front end of the elbow rest main body y22 first faces outward and gradually faces inward, and when moved from front to rear, it can follow either of the ring-shaped paths of the other guide groove y4j, thereby providing a variety of movement patterns that are different from the simple reciprocating movement trajectory of the elbow rest main body y22 in the prior art.

[0089] As described above, the configuration of the chair A to which the present invention is applied has been described, but the technical scope of the present invention is not limited to the above embodiment. In the above embodiment, the urging spring x5b and the top x5a are accommodated in the top accommodating portion x3z formed in the clamp portion x3, and the cam plate x5g, the stopper x5j, and the erroneous installation prevention stopper x5k are formed in the slider portion x4 of the headrest X, but the present invention is not limited to this embodiment. As shown in Figs. 40 and 41, the urging spring x5b and the top x5a are accommodated in the top accommodating portion x4z formed in the slider portion x4. In addition, a cam plate x3g is formed as a cam portion on the rear surface (back surface) of the first member x3a of the clamp portion x3, a stopper x3j is formed at the upper end position of the cam plate x3g, and a stopper x3k is formed on the lower surface of the cam plate x3g.

[0090] 40 and 41, the amount of protrusion of the slider part x4 from the clamp part x3 can be maintained by the slide position holder x5p (not shown in FIGS. 40 and 41) consisting of the piece x5a, the biasing spring x5b, and the cam plate x3g. This is also advantageous in that the cam plate x3g is not exposed when the amount of protrusion of the slider part x4 from the clamp part x3 is large or small, improving the appearance of the chair A. When the amount of pull-out of the slider part x4 from the clamp part x3 is continuously increased, the upper inclined surface of the mountain-shaped part x5d of the piece x5a in the normal mounting state (the state shown in FIG. 40) abuts against the stopper x3j, preventing the slider part x4 from coming off the clamp part x3. Furthermore, when the clamp portion x3 is in an incorrect position relative to the slider portion x4 (when only the clamp portion x3 is upside down as shown in Figures 40 and 41), the anti-mis-installation stopper x3k abuts against the underside of the frame accommodating portion x4z shown in Figure 40, thereby preventing the clamp portion x3 from being installed on the slider portion x4.

[0091] In the present embodiment, the present invention has been described by taking as an example the chair A equipped with the height adjustment mechanism x5 of the headrest X with the head contact portion x2 as the optional member, but the optional member in the present invention is not limited to the head contact portion x2. Another optional member may be a hanger for hanging a coat or the like on the upper end of the backrest H.

[0092] Furthermore, any combination of the forms described in this specification may be adopted as an embodiment of the present invention. [Explanation of symbols]

[0093] A: Chair B: Legs b1: Caster, b2: Leg wing, b3: Leg support C: Support base c1: mounting hole, c2: reaction spring, c3: reaction spring support, c4: link plate, c5: long hole, c6: Locking force adjustment lever, c7: Locking operation lever D: za d1: seat support, d2: seat body, d3: cushion, d4: recess, d5: protrusion, d6: shaft receiving hole, d7: opening, d8: spring holder, d9: spring, d10: pressure plate, d11: synchronous shaft mounting part, d12: opening hole, d13: Stopper body F: Backrest structure G: Back support g1: arm, g2: connecting plate, g3: shaft hole, g4: nut H: Backrest h1: back frame, h2: back frame, h3: upholstery, h4 lumbar support, h5: Pelvic operation part, h6: First upholstery engagement body, h7: Second upholstery engagement body J1: Rotating shaft, J2: Synchro shaft, J3 Locking shaft, J4: Shaft body T: Tag X: Headrest x1: mounting part, x2: head contact part, x3: clamp part (base part), x3a: first member, x3b: second member, x3c: guide rail clamping portion, x3g: cam plate (cam portion), x3j: Anti-slip stopper, x3k: Mis-insertion prevention stopper, x3x: First locking part, x3y: second locking portion, x3z: link housing portion, x4: slider portion (slider), x4a: guide rail, x4z: frame storage section, x5: height adjustment mechanism, x5a: frame, x5b: biasing spring (biasing member), x5c: spring accommodation hole, x5d: mountain-shaped portion, x5e: rib, x5f: inclined rib, x5g: cam plate (cam part), x5h: convex part, x5i: Large convex part, x5j: Stopper to prevent slipping out, x5k: Stopper to prevent incorrect installation, x5l: bottom, x5m: bottom rib (contact piece), x5p: slide position holder, x5x: U-turn section, x6: frame, x7: upholstery Y: Armrest y1: Seat mounting part, y2: Height adjustment tube, y3: Slide tube, y4: Armrest, y5: Operating lever, y6: Height position holding part, y7: Wire, y21: Elbow support part, y22: Elbow rest body 10: Seat-synchronizing shaft connection structure

Claims

1. A chair having an optional component position adjustment mechanism for adjusting the position of an optional component relative to a backrest, The optional member position adjustment mechanism includes: a base attached to the backrest; a slider to which the optional member is attached and which is slidably mounted relative to the base; a slide position holder for maintaining a slide position of the slider relative to the base; a stopper for preventing an incorrect attachment that allows the base and the slider to be attached in a correct state and prevents the base and the slider from being attached in an incorrect state.

2. The slide position holder includes: a biasing member and a top disposed between the base and the slider; a cam portion formed on the slider or the base portion, the cam portion moving the top in a direction in which the top is biased by the biasing member and in a direction opposite to the direction in which the top is biased by the biasing member when the slider is slid relative to the base portion, The chair according to claim 1, characterized in that the frame has an abutment piece that abuts against the mis-installation prevention stopper on one of the intersecting edges that intersect with the cam portion on the surface facing the cam portion.

3. 3. The chair according to claim 2, wherein the contact portion of the top with the cam portion has an asymmetrical shape in the extending direction of the cam portion.

4. 4. The chair according to claim 2 or 3, wherein a rib is formed on at least one end of the abutment piece of the top, the rib extending in the extension direction of the cam portion.

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