Chair and operating mechanism of chair

Abstract

Provided is an operating mechanism configured so that the position of a constituent element of a chair is not changed unless an operation lever is operated.　This operation mechanism (h5) operates to change the position of a constituent element of a chair (A). The operation mechanism includes: a body part (h5a); an operation lever (h5b) that is attached to the body part (h5a) so as to be rotatable in one direction and in the reverse direction; and a stopper member (h5c) that advances and enters from the body part (h5a) in conjunction with the rotation of the operation lever (h5b), and that is locked and unlocked by a locking part (h5d) provided in a support part (h1h) disposed on the chair (A).

Description

Chair and chair operating mechanism

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

[0002] Conventionally, chairs have been known that include components such as a backrest, a seat, legs, a headrest, and armrests. Taking a backrest as an example, a known configuration is one in which the back, to which the upholstery that contacts the back of the seated person is fixed, moves (rocks) back and forth relative to a back frame to switch between supporting and not supporting the seated person's lower back (see Patent Document 1: JP 2017-086669 A). Specifically, the configuration allows the back to be moved back and forth by rotating an operating lever attached to the bottom of the backrest.

[0003] Japanese Patent Application Laid-Open No. 2017-086669

[0004] However, in the conventional chair exemplified by the above-mentioned Patent Document 1, the operating mechanism for moving the components (for example, the back of the backrest) has a simple structure that simply rotates a link, making it easy to operate. However, the back can move forward and backward without operating the operating lever. For example, if the back itself is held and pushed forward and backward, the link rotates and the back moves forward and backward. As such, there is a risk of the back moving unexpectedly, and a solution to this problem was sought.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an operating mechanism in which the positions of the components of a chair do not change unless an operating lever is operated.

[0006] The present invention solves the above problems by the means described below.

[0007] The operating mechanism of the present invention is an operating mechanism that performs an operation to change the position of a chair component, and is required to have a main body, an operating lever that is attached to the main body so that it can rotate in one direction and the other direction, and a stopper member that advances and advances from the main body in conjunction with the rotation of the operating lever, and that engages and disengages with a locking portion provided on a support portion arranged on the chair.

[0008] This allows for a configuration in which the position of the target component does not change unless the operating lever is operated, thereby preventing the conventional problem of the component moving unexpectedly.

[0009] Furthermore, it is preferable that the stopper member is locked by the locking portion when the operating lever is in the neutral position or when it is rotated from the neutral position to a position less than a predetermined position, and that the main body is rotated in conjunction with the rotation of the operating lever when the operating lever is rotated from the neutral position to a position greater than the predetermined position. This makes it possible to realize a configuration in which the components do not move unless the operating lever is operated, but which allows the components to move by rotating the operating lever.

[0010] It is also preferable that the stopper member is attached to the main body so as to be movable parallel to the rotation axis of the operating lever but immovable around the axis of the rotation axis, thereby realizing a configuration in which the main body rotates together with the operating lever when the operating lever is rotated beyond a predetermined position.

[0011] The chair according to the present invention comprises the operating mechanism, a back frame, and a backrest having a back connected to the back frame, wherein the operating mechanism is rotatably connected to a first bracket provided on the back or a member fixed to the back, and to a second bracket provided on the back frame or a member fixed to the back frame, and wherein the operating lever is rotated to change the position of the back relative to the back frame. This allows the position of the back to remain unchanged unless the operating lever is operated.

[0012] Preferably, the operating mechanism has a first rotating part that is rotatably connected to the first bracket, and a second rotating part that is provided on the main body with a rotation axis parallel to the rotation axis of the first rotating part and is rotatably connected to the second bracket. In this way, the first bracket, i.e., the back part, can be moved by operating the operating mechanism using the second bracket as a support part.

[0013] It is also preferable that the operating mechanisms are provided in pairs on the left and right sides of the back frame, so that the configuration in which the operating mechanisms are provided on both the left and right sides can support the load applied to the back and maintain the position of the back, particularly preventing it from deforming diagonally.

[0014] According to the present invention, it is possible to realize a chair configured such that the position of the target component does not change unless the operating lever is operated, thereby preventing the component from moving unexpectedly.

[0015] 6A is a front perspective view of the chair in this embodiment. FIG. 6B is a rear perspective view of the chair in this embodiment. FIG. 6C is a front perspective view showing the seat disassembled after the armrests have been removed and the seat has been removed from the support base. FIG. 6D is an enlarged perspective view of the periphery of the support base. FIG. 6E is a bottom perspective view of the seat support. FIG. 6F is a plan view of the seat support. FIG. 6G is a schematic cross-sectional view taken along line VII-VII in FIG. 6. FIG. 6H is a front perspective view of the pressure plate (A) and a rear perspective view of the pressure plate (B). FIG. 6H is a schematic cross-sectional view taken along line IX-IX in FIG. 6. FIG. 6A is a view before the stopper body is attached, and FIG. 6B is a view after the stopper body is attached. FIG. 6A is a front perspective view of the stopper body and a rear perspective view of the stopper body (B). FIG. 6G is a front perspective view of the back support. FIG. 6H is a front perspective view of the backrest disassembled. FIG. 6H is a rear perspective view of the backrest disassembled. FIG. 6H is a front view of the first upholstery engaging body and a front view of the second upholstery engaging body. 27 is an explanatory diagram showing the engagement state of the first upholstery engagement body with the back portion. A rear perspective view of the back portion and the lumbar support. A front view of the lumbar support. A first exploded perspective view of the operation mechanism. A second exploded perspective view of the operation mechanism. A front perspective view of the headrest. A front perspective view showing the state in which the clamp unit has been removed from the headrest. A rear perspective view (A) of the top of the height adjustment mechanism and a front perspective view (B) of the top of the height adjustment mechanism. A side view showing the state of the top and the cam surface. A cross-sectional view showing the state of the top and the cam surface. A cross-sectional view showing the state in which the top is prevented from coming off by the stopper. A cross-sectional view showing the state in which the top in an unattached state is restricted by the stopper for preventing erroneous attachment. A rear perspective view of the headrest. A rear perspective view of the headrest. A rear perspective view showing the state in which the decorative frame has been removed from FIG. 27. An explanatory diagram showing a method of attaching the upholstery to the frame body to which the third upholstery engagement body and the fourth upholstery engagement body have been attached. A back view of the upholstery to which the third upholstery engagement body and the fourth upholstery engagement body have been attached. 1A is a front view of a fourth upholstery engagement body, FIG. 1B is a front view of the fourth upholstery engagement body stretched in the longitudinal direction, FIG. 1C is a front view of the fourth upholstery engagement body compressed in the longitudinal direction, and FIG. 1D is a front view of the fourth upholstery engagement body bent in the longitudinal direction. FIG. 1D is a front perspective view of the fourth upholstery engagement body disassembled. FIG. 1E is a rear perspective view of the fourth upholstery engagement body disassembled. FIG. 1F is a front perspective view of the fourth upholstery engagement body disassembled.40A is a side view of the main part showing the state when the armrest is moved rearward, a plan view of the main part (B), a plan view of the main part (C), and a plan view of the second path section (D). 40A is a side view of the main part showing the state when the armrest is moved forward, a plan view of the main part (B), a plan view of the first path (C), and a plan view of the second path section (D). 40A is a side view of the main part showing the state when the armrest is moved forward and facing inward, a plan view of the main part (B), a plan view of the first path (C), and a plan view of the second path section (D). 40C is an explanatory diagram explaining the operation of the backrest of the chair of FIG. 1. 40B is an exploded perspective view of the operating mechanism of the chair of FIG. 1. 40C is a diagram showing an example of the operating mechanism of the chair of FIG. 1, where FIG. 40A is a perspective view, FIG. 40B is a front view, and FIG. 40C is a side cross-sectional view. Figures 41(A) to 41(F) are explanatory diagrams explaining the operation of the operating mechanism of the chair of Figure 1. Figures 42(A) to 42(F) are explanatory diagrams explaining the operation of the operating mechanism of the chair of Figure 1. An explanatory diagram explaining the connecting structure between the operating mechanism and the back of the chair of Figure 1. Figures showing an example of a detachment restriction part of the chair of Figure 1, where Figure 44(A) is a diagram showing the operating mechanism at the front end position within the movable range, and Figure 44(B) is a diagram showing the operating mechanism at the rear end position within the movable range. An explanatory diagram explaining the attachment and detachment operation of the back to the back frame.

[0016] An embodiment of the present invention will be described below with reference to the drawings. In this specification, "upper", "lower", "front" and "rear", as well as "left" and "right" are defined with reference to a person sitting on a chair seat (in other words, "upper", "lower", "front" and "rear", as well as "left" and "right" as seen from the person sitting on the chair).

[0017] This embodiment illustrates a chair A to which the present invention is applied to a connection structure for connecting a seat support d1 as a rotating body to a synchro shaft J2 as a rotating shaft.

[0018] 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 relative to the support base C, a headrest X attached to the backrest structure F, and armrests 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.

[0019] Each component of this chair A will be described in detail below.

[0020] (Leg B) Leg B comprises a plurality of radially arranged leg blades b2 each having a caster b1 at its tip, and leg supports b3 erected at the base ends of these leg blades b2. The leg supports b3 are extendable in the vertical direction. The leg supports b3 have gas springs (not shown), which support 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 adopted as appropriate.

[0021] (Support Base C) Figure 4 is a perspective view of the support base C and its surroundings in Figure 3. In this embodiment, the support base C is shaped like a bottomed box. A mounting hole c1 (see Figure 2) is formed in the rear bottom surface of the support base C. The support base C is attached to the top of the leg support b3 by inserting the leg support b3 into the mounting hole c1. A rotation axis J1 during rocking operation, a synchronizer shaft J2 as a pivot shaft, and a locking axis J3 for locking the first end of the reaction spring c2 during rocking span the left and right directions of the support base C. The second end of the reaction spring c2 is engaged with a reaction spring receiving portion c3 disposed on the support base C. The rotation axis J1, the synchronizer shaft J2, and the locking axis J3 all pass through a link plate c4 disposed between the left and right walls. An arm g1 of the back support G is connected to the rotation axis J1. The seat support d1 of seat D is fitted onto the synchronizer shaft J2 so as to be rotatable around the axis of the synchronizer shaft J2. One end of the reaction spring c2 is engaged with the locking shaft J3. The link plate c4 rotates around the rotation axis J1 as the center of rotation, thereby achieving a rocking operation. Furthermore, when the backrest H is rocking, the link plate c4 and the synchronizer shaft J2 move the seat D in synchronization with the rocking operation. In this way, the rotation axis J1, synchronizer shaft J2, locking shaft J3, and link plate c4 form a synchronous locking mechanism, which achieves a synchronous locking operation.

[0022] In addition, arc-shaped elongated holes c5 are formed in the left and right walls of the front end of the support base C. A shaft J4 is disposed so as to span these elongated holes c5 in the left-right direction. The elongated holes c5 and the shaft J4 guide the movement of the seat D via the link plate c4 and the synchronizer shaft J2 so that it moves along a predetermined trajectory when the backrest H is rocked. The shaft J4 also serves as part of the forward tilt mechanism of the seat D, described below. A rocking force adjustment lever c6 is disposed on the front right side of the support base C to adjust the operating force required for the rocking operation. A locking operation lever c7 is disposed on the rear left side of the support base C to switch the lock on and off at the initial position (upright position) of the rocking operation. The other components of the support base C shown in Figures 3 and 4 are known and will not be described here.

[0023] (Seat D) As shown in Figure 3, the seat D includes a shell-shaped pivoting seat support d1, a seat body d2, and a cushion d3, which are mounted on the seat support d1 so that their front-to-back positions can be changed. As shown in Figures 5 to 7, a recess d4 with an open bottom is formed in the front portion of the underside of the seat support d1. Two protrusions d5, each with an arcuate underside, are erected in the recess d4. Shaft body accommodating holes d6 are drilled at the left-right outer positions of the protrusions d5, aligned at the same height as the arcuate surfaces of the protrusions d5. Axles J4 are inserted through the left and right shaft body accommodating holes d6. In this state, the top surfaces of the shafts J4 abut against the arcuate surfaces of the protrusions d5. An opening d7 is provided on the top surface of the seat support d1 at a planar position that is laterally outer of the shaft body accommodating holes d6. As shown in the side cross-sectional view of seat D, the spring holder d8 and spring d9 are housed in the opening d7 on the top surface of the shaft J4 in the order shown from the side (below) of the shaft J4. Also, a pressure plate d10 is attached to the opening d7 to house the spring d9 in a biased state.

[0024] As shown in FIG. 8 , the pressure plate d10 is rectangular in plan view. An upper protrusion d10a protruding upward is formed at one longitudinal edge. A front protrusion d10b protruding in the longitudinal direction of the pressure plate d10 is formed at the end face opposite the end where the upper protrusion d10a is formed. A rear entry portion d7a is formed in the opening d7 of the seat support d1, through which the upper protrusion d10a can pass. A fitting hole d7b into which the upper protrusion d10a fits is formed at a position rearward of and adjacent to the rear entry portion d7a. Furthermore, a front entry portion d7c is formed at a position forward of the opening d7, into which the front protrusion d10b can enter. 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 pressure plate d10. The depth dimension of the rear entry portion d7a is formed to be greater than the longitudinal dimension of the pressure plate d10.

[0025] After the spring holder d8 and spring d9 are accommodated in the aforementioned opening d7, the pressure plate d10 is attached to the opening d7 while pressing (compressing) the spring d9 downward with the pressure plate d10. Specifically, the pressure plate d10 is slid rearward while facing downward, and the upper protrusion d10a passes through the fitting hole d7b. The pressure plate d10 is then moved to the innermost position of the rear entry portion d7a until the entire pressure plate d10 is accommodated in the opening d7. After the entire pressure plate d10 is accommodated in the opening d7, the pressure on the spring d9 is released, and the pressure plate d10 is slid forward. The upper protrusion d10a fits into the fitting hole d7b, and the front protrusion d10b enters the front entry portion d7c, allowing the pressure plate d10 to be attached to the opening d7 in a state where it is prevented from coming off. In this state, the spring d9 is under a predetermined biasing force generated by the pressure plate d10, so the upper protrusion d10a remains engaged with the engagement hole d7b, and the pressure plate d10 will not fall off from the opening d7.

[0026] In this way, the seat support d1 can reciprocate between the height of the upper surface of the shaft J4 and the height of the lower surface of the pressure plate d10 within a range in which the spring d9 can be compressed, using the shaft J4 held by the support base C, the spring holder d8, spring d9, and pressure plate d10 mounted on the shaft J4. In other words, when a seat occupant applies a downward force (external force) to the front part of the seat D against the biasing force of the spring d9, 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, a portion of the accumulated biasing force returns the seat D to its initial position. At this time, the shaft J4 reciprocates diagonally up and down along the elongated hole c5 formed in the support base C.

[0027] As shown in FIG. 5 , a synchronizer shaft mounting portion d11, which is a connecting portion connecting the upper and lower surfaces of the support seat d1, is provided in the center of the lower surface of the support seat d1. In this embodiment, the synchronizer shaft mounting portion d11 has inclined protrusions d11a, which are formed as a plurality of inclined surfaces extending downward from the support seat d1, and arc-shaped abutment portions d11b, which are a plurality of abutment portions each having an arc-shaped abutment surface. Both the inclined protrusions d11a and the arc-shaped abutment portions d11b are formed in a rib shape and are arranged along the length of the synchronizer shaft mounting portion d11. To mount the support seat d1 on the synchronizer shaft J2, the synchronizer shaft J2 is inserted into the synchronizer shaft mounting portion d11 along the inclined protrusions d11a, and the outer circumferential surface of the synchronizer shaft J2 abuts against the arc-shaped abutment portions d11b. By bringing the synchronizer shaft J2 into contact with the arc-shaped contact portion d11b, the seat d1 can be attached to the synchronizer shaft J2 in an appropriate state.

[0028] FIG. 9 is a cross-sectional view of the seat support d1 attached to the synchronizer shaft J2. As shown in FIG. 9A, an opening d12 communicating with the synchronizer shaft mounting portion d11 is formed in the upper surface of the seat support d1. In this embodiment, the opening d12 is disposed at the same longitudinal position (left-right direction) as the arc-shaped abutment portion d11b of the synchronizer shaft mounting portion d11. The opening d12 may also be disposed at a different longitudinal position (left-right direction) from the arc-shaped abutment portion d11b of the synchronizer shaft mounting portion d11. The opening d12 is shaped to intersect with the inclined surface d11x of the inclined protrusion d11a in a side view. More specifically, the inclined protrusion d11a has an inclined surface d11x extending upward and rearward from a lower opening that opens downward and forward. 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 upward 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.

[0029] A first engagement recess d12a is formed on the inner peripheral surface d12x of this 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). Furthermore, as shown in FIG. 9(B), a stopper body d13 is attached to the opening hole d12 to prevent the synchronizer shaft J2 from slipping out when inserted into the synchronizer shaft attachment portion d11. By attaching the stopper body d13 to the opening hole d12 as shown in FIG. 9(B), a seat holder-synchronizer shaft coupling structure 10 is formed as a rotating body coupling structure, and the seat holder d1 is rotatably coupled along the outer peripheral surface of the synchronizer shaft J2.

[0030] As shown in FIG. 10 , the stopper body d13 is formed into a generally L-shaped body in a side view, having an upper portion d13a and an inclined portion d13b. A lattice pattern similar to that on the upper surface of the seat support d1 is formed on the upper surface of the upper portion d13a. A rearward protrusion d13c is formed on the rear side surface of the upper portion d13a as a convex portion for preventing misalignment. The inclined portion d13b is formed at the same inclination as the inner peripheral surface d12x of the opening hole d12 and is formed to be able to enter the opening hole d12. An engaging claw d13d is disposed protruding from the front surface of the inclined portion d13b. The engaging claw d13d is formed in a cantilever shape so that it can be protruded or inserted into the front surface of the inclined portion d13b by elastic deformation. A downward protrusion d13e is formed at the lower end of the inclined portion d13b. The lower surface of the upper portion d13a and the rear surface of the inclined portion d13b form a synchronizer shaft fitting portion d13f having an arc-shaped inner bottom surface.

[0031] The stopper body d13 thus formed is attached by inserting the inclined portion d13b from the upper surface of the seat d1 along the inner circumferential 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 circumferential surface d12x of the opening hole d12 while elastically deforming. When the engagement claw d13d reaches the position of the first engagement recess d12a formed on the inner circumferential surface d12x of the opening hole d12, the elastic deformation of the engagement claw d13d is restored and the engagement claw d13d engages with the first engagement recess d12a, thereby preventing the stopper body d13 from coming loose. In this state, the rearward protrusion d13c also engages with the second engagement recess d12b formed at the opening of the opening hole d12. In other words, the synchronizer shaft J2 can be restricted from moving in two directions, either loosely fitted or released from its fitted state, in the synchronizer shaft fitting portion d13f. The downward protrusion d13e is used as a reinforcing part to reinforce the lower end of the synchronizer shaft fitting part d13f.

[0032] With the synchronizer shaft J2 and stopper body d13 attached in this manner, even if a force is applied in the direction of arrow A in FIG. 9B by pulling the seat support d1 upward, the movement of the seat support d1 in the direction of arrow A is restricted by the stopper body d13. This prevents the seat support d1 from coming off the synchronizer shaft J2. By removing the stopper body d13 from the opening d12 of the seat support d1, the seat support d1 can be easily removed from the synchronizer shaft J2. Thus, the seat support d1 of this embodiment is advantageous in that it can be attached to and disassembled from the synchronizer shaft J2 without the use of tools. The seat D attached to the synchronizer shaft J2 in this manner is configured to move in synchronization with the backward tilting (rocking) movement of the backrest H via the rotating shaft J1, link plate c4, and synchronizer shaft J2.

[0033] (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.

[0034] 11, the back support G includes left and right arms g1 rotatably supported on a rotation axis J1, and a connecting plate g2 connecting 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.

[0035] The left and right arms g1 are paired plates extending in the front-to-rear direction, with shaft holes g3 formed in their front portions for inserting and securing the rotary shaft J1 and synchronizer shaft J2. The left and right arms g1 are supported so as to be rotatable around the rotary shaft J1 inserted and secured in the shaft holes g3. The rear surface (back face) of the connecting plate g2 is provided with a plurality of bolt insertion holes (not shown) for inserting a plurality of bolts (not shown). Nut portions g4 are fixed by welding to the front side (front face) of each bolt insertion hole. A locking operation lever c7 is also rotatably attached to the arm g1.

[0036] 12 and 13, the backrest H includes a back frame h1, a back portion h2 disposed in front of the back frame h1, an upholstery h3 stretched over the back portion h2, a lumbar support h4 attached to the back portion h2 at a position behind the upholstery h3, and an operating mechanism h5 that positions the back portion h2 in a reversible manner in the front-to-rear direction relative to the back frame h1. The operating mechanism h5 can also be applied to mechanisms for changing the positions of other components (seat, legs, headrest, armrests, etc.) (not shown).

[0037] The backrest H has a back portion h2, covered with upholstery h3, arranged in front of a back frame h1 so that its position can be changed in the front-to-rear direction. This configuration of the backrest H makes it easy to give the back portion h2 a structure that is easy to elastically deform as a whole, making it easy to give the back portion h2 flexibility that can envelop the back of a seated person. The entire backrest H can 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.

[0038] (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 bridged 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, and a lower connecting portion h1d connecting the left and right lower frame portions h1c to each other and fastened to a connecting plate g2 of the back support body G. The left and right side frame portions h1a, upper frame portion h1b, left and right lower frame portions h1c, and lower connecting portion h1d are molded from synthetic resin and assembled together.

[0039] The left and right side frame portions h1a of the back frame h1 are each shaped like a member that gradually widens downward. The side frame portions h1a of the back frame h1 are arranged on the backside of the side of the backrest surface, which is mainly composed of upholstery h3 stretched over the back portion h2. The left and right side frame portions h1a are roughly V-shaped 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.

[0040] The upper frame portion h1b of the back frame h1 is located on the upper backside of the backrest surface and is a structural frame that connects the upper ends of the side frame portions h1a. The upper frame portion h1b is provided with elements that form an upper connecting portion for attaching the upper end of the back portion h2. Specifically, the front surface of this upper frame portion h1b is provided with multiple forward-opening recesses h1e and protrusions h1f in the left-right direction. The bottom surface of this upper frame portion h1b is provided with bolt insertion holes h1g that communicate with each recess h1e.

[0041] 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. In other words, parts of the left and right lower frame portions h1c are 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-to-rear direction, with their front ends extending to both sides of the support base C located below the seat D. In addition, a second bracket h1h is erected on the lower frame portion h1c.

[0042] (Back section h2) The back section h2, located in front of the back frame h1, is attached to the back frame h1 at its upper end and left and right lower portions. On the rear side of the upper end of the back section h2, a convex section h2a that fits into a recessed section h1e formed in the upper frame section h1b of the back frame h1 and a concave section h2b that fits into the recessed section h1e and convex section h1f are provided, respectively, so as to correspond to the recessed section h1e and the convex section h1f. Furthermore, on the rear side of the back section h2, an engagement groove h2c is provided for engaging the upholstery h3 at locations corresponding to the side frame section h1a and the lower frame section h1c of the back frame h1. A first bracket h2d is formed on the lower left and right rear portions of the back section h2, and is connected to an operating mechanism h5 connected to the back frame h1. In other words, the back section h2 is movably connected to the back frame h1 via the operating mechanism h5.

[0043] A first upholstery engaging body h6, as shown in Figure 14(A), is attached by sewing to the upper edge of the upholstery h3 stretched over the back portion h2. The first upholstery engaging body h6 is a long, thin sheet of synthetic resin formed to a width approximately equal to the width of the upper end of the back portion h2. The first upholstery engaging body h6 is formed with attachment portions h6a and h6b having openings matching the shapes of the convex portion h2a and concave portion h2b at positions corresponding to the convex portion h2a and concave portion h2b on the rear surface side of the upper end of the back portion h2. The attachment portion h6a is formed in a shape that opens at the widthwise edge of the first upholstery engaging body h6, and the attachment portion h6b is formed in a through-hole shape relative to the first upholstery engaging body h6.

[0044] Furthermore, an insertion hole h6c for inserting the engagement pin KP is formed in the center of the upper end of the back portion h2 of the first upholstery engagement body h6. Furthermore, 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 local elastic deformation when the engagement pin KP is inserted into the insertion hole h6c and preventing the first upholstery engagement body h6 from lifting up to the upper end of the back portion h2. Furthermore, second upholstery engagement bodies h7 for insertion into engagement grooves h2c as shown in Figure 14(B) are attached by sewing to the outer peripheral edges of the side portions and lower end of the upholstery h3.

[0045] 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 as the tag T. By inserting the tag T into the slit h7a and sewing it 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 manufacturer name or brand name of the chair A, a video playback page for instructions on how to use the chair A, or a URL for an advertising page or a link to a page that leads to an SNS (social network service).

[0046] The following describes how the upholstery h3, with the first upholstery engaging element h6 and the second upholstery engaging element h7 sewn around the entire outer periphery, is stretched over the back h2. The upholstery h3 encases the back h2 from the front side of the back h2, and the attachment portions h6a and h6b of the first upholstery engaging element h6 at the upper edge of the upholstery h3 are aligned with the convex portion h2a and concave portion h2b of the back h2, as shown in Figure 15. At this time, the attachment portion h6a is positioned so that it enters from above the convex portion h2a. In this state, the convex portion h2a of the back h2 fits into the concave portion h1e of the spine frame h1, and the concave portion h2b of the back h2 fits into the convex portion h1f of the spine frame h1, and the back h2, the first upholstery engaging element h6, and the spine frame h1 are engaged using the engagement pin KP. As a result, the upholstery h3 is positioned and clamped between the back frame h1 and the back portion h2, and the upper ends of the back frame h1, back portion h2, and upholstery h3 are integrated. The rest of the upholstery h3 is attached by inserting the second upholstery engaging body h7 into the engaging groove h2c formed along the outer periphery of the side and bottom of the back side of the back portion h2. As mentioned above, the lower portion of the back portion h2 is rotatably connected to the back frame h1 via the operating mechanism h5.

[0047] (Lumbar support h4) As shown in Figure 16, a lumbar support h4 is disposed behind (on the back side of) the upholstery h3 stretched over the back portion h2. The lumbar support h4 is attached to the lower back of the back portion h2, spanning the width of the back portion h2. As shown in Figure 17, the lumbar support h4 has a retaining portion h4a that abuts and holds the lower back of the seated person, and narrow insertion portions 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 portion 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 portion h2 are mated, and the lumbar support h4 is attached to the back portion h2 in a state where it is prevented from slipping out.

[0048] The lumbar support h4 attached to the back h2 can be released from the recessed portion h4c by inserting a flathead 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 h2. In other words, the lumbar support h4 is detachable from the back h2.

[0049] (Operation Mechanism h5) Next, the schematic configuration of the operation mechanism h5 and the schematic operation of the operation mechanism h5 will be described. As described above, the back portion h2, to which the lumbar support h4 is attached, can be adjusted in position relative to the back frame h1 by the operation mechanism h5. As shown in FIGS. 18 and 19 , the operation mechanism h5 includes a main body portion (first main body portion) 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 portion (second main body portion) h5g. The second bracket h1h also includes a locking portion h5d. The main body portion h5a includes a cylindrical portion h5h and a first pivot shaft h5i. The operation lever h5b includes a gripping portion that stands perpendicular to the shaft h5j, and is assembled to the main body portion h5a by inserting the shaft h5j from the small diameter side of the cylindrical portion h5h. The shaft h5j is rotatable inside the cylindrical portion h5h.

[0050] An insertion hole h5k is formed in the center of the stopper member h5c. In this embodiment, the stopper member h5c has concave and convex portions formed at intervals of a predetermined angle (e.g., 60 degrees) in the circumferential direction around the insertion hole h5k. 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 surfaces facing outward in the left-right direction. An insertion hole h5l is formed in the center of the locking portion h5d. 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, allowing for concave-convex engagement with each other. When the engagement surfaces of the stopper member h5c and the locking portion h5 are engaged with each other, the respective insertion holes h5k and h5l communicate with each other with their centers aligned on the same straight line.

[0051] A coil spring h5e and a stopper member h5c are housed in the large-diameter side of the cylindrical portion h5h of the main body h5a, in the order shown. 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 a 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 protrudes from the large-diameter side opening of the cylindrical portion h5h.

[0052] The main body portion h5a, which houses the operating lever h5b, coil spring h5e, and stopper member h5c, is assembled with the exposed portion of the stopper member h5c engaged with the locking portion h5d. The operating mechanism h5 is then attached to the back frame h1 by inserting the second pivot shaft h5o of the main body portion (second main body portion) h5g into the insertion hole h5l of the locking portion h5d from the inside and threading the second screw h5p into the female thread portion h5q formed on the main body portion h5a. When the operating mechanism h5 is attached in this manner, the stopper member h5c is constantly biased toward the locking portion h5d by the biasing force of the built-in coil spring h5e, restricting unintended movement of the back portion h2 (lumbar support h4). This requires rotating the operating lever h5b of the operating mechanism h5 to change the position of the back portion h2 relative to the back frame h1.

[0053] 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, increasing the amount of protrusion of the operating lever h5b in the axial direction of the cylindrical portion h5h. This compresses the coil spring h5e, reducing the biasing force pressing the stopper member h5c against the locking portion h5d, allowing the operating lever h5b to rotate and disengaging the stopper member h5c from the locking portion h5d.

[0054] With the engagement force between the stopper member h5c and the locking portion h5d reduced in this manner, rotation of the operating lever h5b causes the engagement surfaces of the locking portion h5d and the stopper member h5c to slide, allowing the stopper member h5c to rotate. This causes the spine h2 to rotate due to the action of the shaft h5j formed on the main body h5a and connected to the first bracket h2d of the spine h2. The operating mechanism h5 in this embodiment can provide three positions, but the number of positions that can be provided by the operating mechanism h5 can be changed as needed by changing the design of the engagement surfaces of the stopper member h5c and the locking portion h5d.

[0055] Furthermore, an upright wall h5t is provided at a required distance radially outward from the shaft h5j of the main body (second main body) h5g, extending over a required length along the outer peripheral surface of the shaft h5j. When the back portion h2 is positioned as required by the operating mechanism h5, the upright wall h5t prevents the first bracket h2d of the back portion h2 from coming loose. To remove the back portion h2 from the back frame h1 with the operating mechanism h5 attached, the pinned connection between the back frame h1 and the upper end of the back portion h2 is released, the upper end of the back portion h2 is tilted forward, and the back h2 is pulled out with the forward tilt angle of the back portion h2 relative to the back frame h1 set to a predetermined angle. This releases the upright wall h5t from preventing the first bracket h2d of the back portion h2 from coming loose, allowing the back portion h2 to be removed from the back frame h1. By setting the positional relationship between the first bracket h2d and the standing wall h5t in this way, the back portion h2 cannot be removed from the back frame h1 within the normal range of use.

[0056] (Headrest X) A headrest X is detachably attached to the upper end of the backrest H. As shown in Fig. 20 , the headrest X has an attachment portion x1 to the backrest H and a head contact portion x2 that is rotatable around a horizontal axis extending in the left-right direction at the upper end of the attachment portion x1.

[0057] As shown in Figures 20 and 21, the mounting part x1 includes a clamp part x3 that clamps the upper end of the backrest H, a slider part x4 that is held so as to be able to slide vertically relative to the clamp part x3, and a height adjustment mechanism x5 that adjusts the height position of the head contact part x2 relative to the backrest H.

[0058] The clamping portion x3 has a first member x3a that contacts the upper surface of the upper end of the backrest H and a second member x3b that contacts the lower surface of the upper end of the backrest H. The first member x3a and the second member x3b are integrated by screwing them together from the underside of the front surface while clamping the backrest H. A top housing portion (not shown) is formed on the back side of the first member x3a to house the top x5a, which is part of the height adjustment mechanism x5, and the biasing spring x5b that biases the top x5a toward the slider portion x4. The biasing spring x5b and the top x5a are housed in the top housing portion in the order shown, and a portion of the top x5a protrudes from the front end of the top housing portion. A guide rail clamping portion x3c is formed on the rear surface (back face) of the first member x3a along the height direction. The guide rail clamping portion x3c clamps two rows of guide rails x4a, which are provided on the front surface of the slider portion x4 along the height direction. The slider portion x4 is slidable in the height direction by clamping the guide rails x4a between the guide rail clamping portion x3c.

[0059] 22, the height adjustment mechanism x5 in this embodiment includes a top x5a, a biasing spring x5b, a cam plate x5g, a stopper x5j to prevent disengagement, and a stopper x5k to prevent incorrect installation. The height adjustment mechanism x5 will be described in detail below.

[0060] The top x5a is a rectangular block made of synthetic resin, with elements of the height adjustment mechanism x5 formed on one surface. A spring hole x5c for accommodating the biasing spring x5b is provided on the surface of the top x5a facing the clamp portion x3. The depth of the spring hole x5c is sufficiently smaller than the length of the biasing spring x5b, so that even when the biasing spring x5b is accommodated in the spring hole x5c, the biasing spring x5b protrudes reliably from the outer surface of the top x5a. The surface of the top x5a opposite the spring hole x5c is formed with a mountain-shaped portion x5d, a rib portion x5e, and an inclined rib x5f, which are elements of the height adjustment mechanism x5.

[0061] The mountain-shaped portions x5d are disposed at both widthwise ends of the link x5a. The sloped surfaces of the mountain-shaped portions x5d are formed with different slopes. In this embodiment, when the link x5a is properly attached, the slope angle of the upper sloped surface of the mountain-shaped portion x5d is steeper than the slope angle of the lower sloped surface, resulting in an asymmetrical shape. Furthermore, a U-shaped rib portion x5e with an open upper side is provided on the link x5a to complement the space between the two mountain-shaped portions x5d. The height of the rib portion x5e relative to the block portion of the link x5a is constant and is lower than the peak height of the mountain-shaped portion x5d. In other words, the rib portion x5e is higher except at the peak of the mountain-shaped portion x5d. The sloped rib x5f is provided at the midpoint of the rib portion x5e in the left-right direction.

[0062] As shown in Figures 20, 21, 23, and 24, two rows of cam plates x5g are arranged parallel to each other and spaced apart from each other in the left-right direction between the two rows of guide rails x4a on the front side of the slider portion x4. Each cam plate x5g has a plurality of equally spaced, mountain-shaped protrusions x5h, and a large protrusion x5i, taller than the other protrusions x5h, is located at the lower end of the cam plate x5g. In this embodiment, the inclination angle of the lower inclined surface of the large protrusion x5h is asymmetrical, with the inclination angle of the upper inclined surface being greater than that of the lower inclined surface, allowing for concave-convex engagement with the mountain-shaped portion x5d of the block x5a. The inclination angle of the lower inclined surface of the large protrusion x5i is also greater than that of the upper inclined surface.

[0063] Further, anti-slip stoppers x5j are formed on the lower portions of the cam plates x5g in directions perpendicular to each other toward the other cam plate x5g. Mis-installation prevention stoppers x5k are erected parallel to the anti-slip stoppers x5j at the center of the width direction of the two rows of cam plates x5g at the lower end positions of the cam plates x5g. The height of the anti-slip stoppers x5j is formed to be the same as the height of the cam plates x5g at the same height position. The mis-installation prevention stoppers x5k are formed sufficiently lower than the protruding height of the convex portions x5h.

[0064] The method of attaching the piece x5a to the cam plate x5g will now be described. When the piece x5a is in the normal position (with the opening of the rib x5e facing upward), the angled portion x5d slides along the cam surface of the cam plate x5g. The opening of the rib x5e and the inclined surface of the inclined rib x5f allow the piece x5a to slide upward on the cam plate x5g without interfering with the mis-installation prevention stopper x5k and the slip-out prevention stopper x5j. As shown in Figures 23 and 24, the convex portions x5h and the angled portions x5d that form the cam surface are interlocking. Therefore, when the piece x5a slides along the cam surface against the biasing force of the biasing spring x5b, the piece x5a engages with the convex and concave portions at the intervals of the convex portions x5h with a click. By selecting the fitting position of the piece x5a, the amount of protrusion of the slider portion x4 from the clamp portion x3 (the height position of the head contact portion x2) can be selected. When the top x5a is attached to the cam plate x5g in the normal state, the bottom surface x5l of the top x5a, which is formed on a flat surface, abuts against the stopper x5j to prevent the top x5a from coming off the slider portion x4, as shown in Figure 25.

[0065] On the other hand, if the angled portion x5d is attempted to slide on the cam surface of the cam plate x5g with the top x5a in an incorrect position (with the opening of the rib x5e facing downward), the bottom wall surface x5m of the rib x5e abuts against the mis-installation prevention stopper x5k before the angled portion x5d climbs onto the cam surface of the cam plate x5g, restricting the movement of the top x5a, as shown in Figure 26. This prevents the top x5a from entering the cam surface of the cam plate x5g, thereby preventing the clamp x3 from being erroneously installed on the slider x4.

[0066] As shown in Figures 27 and 28, the head-contact portion x2 includes a frame x6 and upholstery x7. As shown in the two rear perspective views, the frame x6 includes an upholstery-holding frame x6a that holds the upholstery x7 and a decorative frame x6b that is attached to the rear (back) surface of the upholstery-holding frame x6a. The upholstery-holding frame x6a is provided with a connecting portion x6c that connects to the slider portion x4. This connecting portion x6c can have a known structure, and therefore will not be described here. A tongue x6d is provided around the rear surface of the upholstery-holding frame x6a, running along the outer periphery of the upholstery-holding frame x6a. A gap is formed between the tongue x6d and the upholstery-holding 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 29).

[0067] As shown in Figure 30, the upholstery x7 in this embodiment has an upholstery main body x7a and a third upholstery engaging body x7b and a fourth upholstery engaging body x7c attached by sewing along the outer edge of the upholstery main body x7a. The third upholstery engaging body x7b has a well-known structure formed from a simple thin sheet of synthetic resin. As shown in Figure 31, the fourth upholstery engaging body x7c has X-shaped through-holes x7d formed at regular intervals along its length, and notches x7e aligned with the centers of each through-hole x7d. The notches x7e are formed independently of the through-holes x7d from both widthwise ends of the fourth upholstery engaging body x7c toward the inside in the widthwise direction.

[0068] Furthermore, through holes x7d are formed at regular intervals along the length in the widthwise center of the fourth upholstery engaging body x7c, but the widthwise inner ends of the cutouts x7e do not extend beyond a predetermined width range based on the widthwise centerline. This allows a large plate portion (unfinished portion) to remain in the widthwise center of the fourth upholstery engaging body x7c. This allows for a large seam allowance when sewing the fourth upholstery engaging body x7c to the upholstery main body x7a. Furthermore, the cutouts x7e of the fourth upholstery engaging body x7c have a large cutout length at both widthwise ends, making it more susceptible to deformation under external forces. In this way, the fourth upholstery engaging body x7c has a large seam allowance, reducing fraying of the upholstery main body x7a while also allowing for easy deformation.

[0069] By employing such a fourth upholstery engaging body x7c, the fourth upholstery engaging body x7c can be expanded and compressed in the longitudinal direction of the fourth upholstery engaging body x7c together with the upholstery main body x7a ( Figures 31(B) and (C) ). Furthermore, the fourth upholstery engaging body x7c can be bent in the same plane in the longitudinal direction ( Figure 31(D) ). These characteristics of the fourth upholstery engaging body x7c allow the fourth upholstery engaging body x7c to easily deform, even in curved sections with small curvatures that the second upholstery engaging body h7 could not accommodate, and thus the fourth upholstery engaging body x7c can be made to follow the curved section. Using such a fourth upholstery engaging body x7c, the upholstery main body x7a, together with the fourth upholstery engaging body x7c, can be engaged with 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 over long periods of use.

[0070] In this embodiment, the third upholstery engaging body x7b and the fourth upholstery engaging body x7c are attached along the outer peripheral edge of the upholstery main body x7a as shown in Figure 30, but it is also possible to adopt a configuration in which only the fourth upholstery engaging body x7c is attached. The point is that it is sufficient if the third upholstery engaging body x7b or the fourth upholstery engaging body x7c can be engaged with the gap between the upholstery holding frame x6a and the tongue piece x6d along the entire outer peripheral edge of the upholstery main body x7a.

[0071] (Armrest Y) In this embodiment, an armrest Y is detachably attached to the seat D of the chair A. As shown in Figures 32 and 33, the armrest Y in this embodiment includes a seat attachment portion y1, a height adjustment tube y2, a slide tube y3, an armrest y4, an operating lever y5, and a height position holding portion y6.

[0072] The seat mounting portion y1 has a seat fixing portion y1a and a cylindrical portion y1b, and is formed into an L-shape by the seat fixing portion y1a and the cylindrical portion y1b, which has an open top surface. A screw hole y1c that penetrates in the vertical direction is arranged in the seat fixing portion y1a, and the screw hole y1c is aligned with a screw hole (not shown) formed in the underside of the seat D, and the seat mounting portion y1 is attached to the seat D by a screw y1d that is fastened from the underside of the screw hole y1c. The cylindrical portion y1b has an open top surface, and houses the height adjustment cylinder y2 and slide cylinder y3 in an assembled state, and the cylindrical portion y1b and the height adjustment cylinder y2 are fixed by a known method.

[0073] In this embodiment, the height-adjustable tube y2 is formed with a cutout in the required height range 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-adjustable tube y2. As is clear from FIG. 34 , two through-holes y2b are arranged at the same height position, sandwiching a rib y2c extending in the height direction from the left and right. The rib y2c protrudes from the front side of the rear peripheral surface y2a. A slide tube y3 is removably inserted into the height-adjustable tube y2.

[0074] The sliding tube y3 has a tube portion y3a inserted into the height-adjusting tube y2 and a shell-shaped elbow support portion y3b that supports the elbow rest y4. A front groove y3d extending in the height direction is formed in the front peripheral surface y3c of the tube portion y3a. A rear groove y3f extending in the height direction is formed in 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, dividing the rear groove y3f. The tube portion y3a of the sliding tube y3 thus formed is inserted into the height-adjusting tube y2 with the rib y2c fitted into the rear groove y3f.

[0075] The height position retaining portion y6 includes a main body y6a, an engagement claw y6b, and a biasing spring y6c. An engagement piece y6d is formed on the front surface of the main body y6a, which engages with a front groove y3d formed in the slide tube y3. Furthermore, a biasing spring y6c and an engagement claw y6b are arranged on the rear surface of the main body y6a in the order shown. 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 claw y6b. The height position retaining portion y6 thus formed is received through the lower opening of the slide tube y3. The height position retaining portion 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, and the slide tube y3 is fixed to the height adjustment tube y2 with the rib y2c entering the rear groove y3f.

[0076] The height position holding portion y6, which is attached to the sliding tube y3 and engaged with the height adjustment tube y2 in this manner, is connected to the operating lever y5 by a wire y7. More specifically, the operating lever y5 is connected to the engagement pawl y6b by the wire y7. That is, when the operating lever y5 is rotated by the seat occupant, the engagement pawl y6b slides in the opposite direction to the direction of the biasing force of the spring y6c via the wire y7. When the seat occupant rotates the operating lever y5, the engagement pawl y6b is disengaged from the through-hole y2b of the height adjustment tube y2. By lifting the elbow support portion y3b while rotating the operating lever y5, the seat occupant can lift a portion of the sliding tube y3 from the height adjustment tube y2.

[0077] As shown in Figure 34, the elbow rest y4 is composed of an elbow rest receiving portion y21, which is formed by stacking a first path member y4a and a first holder y4b in the vertical direction, and an elbow rest main body y22, which is formed by stacking a second path member y4c, a second holder y4d, and an elbow rest pad y4e in the vertical direction. The elbow rest main body y22 is slidable in the front-to-rear direction relative to the elbow rest receiving portion y21. One guide groove y4m is formed on the rear side of the elbow rest main body y22, and the fixed shaft N2 fixed to the elbow rest receiving portion y21 enters into one guide groove y4m. The other guide groove y4j is formed on the front side of the elbow rest receiving portion y21, and the movable shaft N1, which is a shoulder screw fixed to the nut holder y4n of the elbow rest y4, enters into the other guide groove y4j.

[0078] The first path member y4a includes a main body y4g having an opening y4f formed therein, an island portion forming member y4h having a planar area smaller than that of the opening y4f in the central portion of the opening y4f, and a holding member y4i for holding the island portion forming member y4h in a floating state in the planar central portion of the opening y4f. As shown in the figure, the main body y4g and the island portion forming member y4h form a ring-shaped (approximately square-shaped) other guide groove y4j. The holding member y4i is formed in a substantially U-shape to avoid the planar position of the other guide groove y4j within a required height range.

[0079] Additionally, a resistance-providing body y4k is disposed within a partial circumferential length range of the inner circumferential surface of the opening y4f of the first holder y4b. The resistance-providing body y4k protrudes inward from the other guide groove y4j to narrow a predetermined portion of the other guide groove y4j. The resistance-providing body y4k is formed on the first holder y4b as a resilient spring body having a π-shape in a plan view, but is not limited to this form and may be formed, for example, from an elastic material. The resistance-providing body y4k may also be formed on the first path body y4a instead of the first holder y4b. The width of the other guide groove y4j in the area where the resistance-providing body y4k is disposed is narrower than the width of the other guide groove y4j in the area where the resistance-providing body y4k is not disposed. When the movable shaft N1 enters the range in which the resistance imparting body y4k is disposed of in the other guide groove y4j, the outer peripheral 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 than in other ranges. In this embodiment, the first path body y4a is formed separately from the first holder y4b and is integrally engaged with the first holder y4b by an engaging piece y4l formed on the first holder y4b, but the first path body y4a and the first holder y4b can also be formed integrally.

[0080] The second path member y4c includes a guide groove y4m formed in an S-shape at the rear, a nut holder y4n for holding a nut N1a threadedly engaged with the movable shaft N1 that enters the guide groove y4m and moves within the guide groove y4m, and an opening y4o and a mounting portion y4p for mounting the operating lever y5. The guide groove y4m is S-shaped in a plan view, with its initial direction from rear to front substantially matching one of the ring-shaped directions of the other guide groove y4j. This allows the elbow rest main body y22, consisting of the second path member y4c, the second holder y4d, and the elbow pad y4e, to move along an S-shaped path in both the front-rear and left-right directions. The fixed shaft N2 that enters the guide groove y4m is wider than the guide groove y4m, and an O-ring N2b is disposed between the fixed shaft N2 and a washer N2a placed on the top surface of the 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.

[0081] The nut holder y4n houses a nut N1a, which is threaded onto a male thread formed on the small diameter portion of the movable shaft N1. An O-ring N1c is disposed between the nut N1a and the washer N1b, and sliding resistance is applied by elastic deformation of the O-ring N1c that occurs when the movable shaft N1 moves around the other guide groove y4j.

[0082] The opening y4o is formed in the front peripheral surface of the second path body y4c. The grip portion y5a of the operating lever y5 is inserted into the opening 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 operating lever y5, and is erected on the upper surface of the second path body y4c in alignment with both longitudinal ends of the rotation shaft y5b. The opening y4o is formed to a height dimension necessary to allow the operating lever y5 to rotate up and down within a predetermined angular range. A thick portion y5c is formed at the base of the grip portion y5a of the operating lever y5 to close the gap between the opening y4o and the grip portion y5a, preventing foreign matter from entering through the gap between the operating lever y5 and the opening y4o.

[0083] The second holder y4d is formed in a flat plate shape. A plurality of engagement pieces y4r are formed on the outer periphery of the second holder y4d, and engage with engagement portions y4q formed on the second path member y4c. By engaging the engagement pieces y4r of the second holder y4d with the engagement portions y4q of the second path member y4c, the upper surface of the second path member y4c is closed, preventing the intrusion of foreign matter into the second path member y4c. An elbow support pad y4e is removably attached to the upper surface of the second holder y4d by a known method.

[0084] The operating lever y5 is rotatably attached to the second path member y4c as described above. A wire engaging portion y5d is disposed on the rotation axis y5b of the operating lever y5, and a first end of a wire y7 is connected to the wire engaging portion y5d. The wire y7 is pulled into the slide tube y3 through one of the guide grooves y4m of the second path member y4c, and its second end is connected to the engaging claw y6b of the height position retainer y6. By adopting a configuration in which the rotational movement of the operating lever y5 is transmitted to the height position retainer y6 via the wire y7, the operating lever y5 can be disposed on the elbow rest pad y4e (second path member y4c) that can move back and forth and left and right. Furthermore, by utilizing one of the guide grooves y4m to route the wire y7 in the elbow rest y4, bending of the wire y7 can be reduced, allowing smooth operation of the operating lever y5 regardless of the position of the elbow rest pad y4e.

[0085] As shown in Figures 35 and 36, when the elbow rest main body y22 moves from rear to front, it first moves along the S-shape of one of the guide grooves y4m located on the rear side. Meanwhile, the movable shaft N1, which moves along the other guide groove y4j together with the elbow rest main body y22, reaches the location (the front end face) of the other guide groove y4j where the resistance-providing member y4k is located, providing a sense of resistance. When the elbow rest main body y22 moves from front to rear, it can move along either side of the ring-shaped other guide groove y4j located on the front side. By making the other guide groove y4j ring-shaped, the seat occupant can experience a variety of movement paths for the elbow rest main body y22. Furthermore, as the movable shaft N1 moves along the other guide groove y4j together with the elbow rest main body y22, it moves from the location where the resistance-providing member y4k is located to the location where it is not located, providing a sense of resistance at the beginning of its movement, after which the resistance disappears and the occupant can move.

[0086] The area in the other guide groove y4j where the resistance-providing body y4k is disposed has a narrower path width than the other areas, and as the movable shaft N1 passes through this area, the outer periphery of the movable shaft N1 pushes the resistance-providing body y4k apart as it passes. By elastically deforming the resistance-providing body y4k in this manner, a sense of resistance to the movement of the movable shaft N1 can be imparted, contributing to the luxurious feel of the chair A and allowing the seated person to easily recognize the current position of the armrest y4 and the direction of future movement. In this embodiment, 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. Therefore, it is sufficient to provide resistance to the movement of the movable shaft N1 by providing either the O-ring N1c or the resistance-providing body y4k.

[0087] As shown in Figures 35 to 37, in this embodiment, when the elbow rest main body y22 is moved from the rear to the front, it follows a movement trajectory along one of the S-shaped guide grooves y4m, with the front end of the elbow rest main body y22 first pointing outward and gradually pointing inward, and when moved from the front to the rear, it can follow either of the ring-shaped paths of the other guide groove y4j, so that a variety of movement patterns can be provided, unlike the simple reciprocating movement trajectory of the elbow rest main body y22 in prior art.

[0088] Next, a detailed configuration of the operation mechanism h5 and a detailed operation performed by the operation mechanism h5 will be described. Here, Fig. 38 is an explanatory diagram illustrating the operation of the backrest H, with Fig. 38(A) being a left side view and Fig. 38(B) being a right side view. Note that the operation mechanism h5 will be described using an example in which the position of the back h2 of the backrest H is changed, but this is not limited thereto, and it can also be applied as an operation mechanism for operating to change the positions of other components (seat D, legs B, headrest X, armrest Y, etc.) (i.e., moving the components within a set movable range).

[0089] As described above, the backrest H includes a back frame h1 and a back portion h2, which are interconnected by an upper connector hu and a lower connector (described below). The back portion h2 can be moved forward and backward relative to the back frame h1 by operating the operating mechanism h5 (specifically, by swinging toward and away from the back frame h1 using the upper connector hu as a fulcrum) (the range of movement is appropriately set). This allows the back portion h2 to be moved to suit the respective sitting positions, including the leaning back and leaning forward postures, thereby optimally adjusting the support position of the spine (particularly the pelvis). As an example, the solid lines in Figures 38(A) and 38(B) indicate the state in which the back portion h2 has moved to its rear end position relative to the back frame h1, while the dashed lines indicate the state in which the back portion h2 has moved to its front end position relative to the back frame h1. As described above, the upper connector hu employs a simple, easily attachable and detachable structure based on a concave-convex fit.

[0090] As an example, the back frame h1 is formed using a resin material (although this is not a limitation), and the back portion h2 is formed in a frame shape, a plate shape, or the like using an elastic resin material (although this is not a limitation), and the upholstery h3 stretched over the back portion h2 is made of a so-called mesh-type, cushion-type, or other seat fabric made of synthetic fibers or the like (although this is not a limitation).

[0091] As mentioned above, the conventional chair described in Patent Document 1 also has a structure in which the back can move forward and backward. However, because the structure is such that if the back itself is held and pushed forward and backward, the link rotates and the back moves forward and backward, there is a risk that the back may move unexpectedly.

[0092] The chair A having the operating mechanism according to this embodiment is particularly equipped with the following configuration, thereby making it possible to solve the above-mentioned problems.

[0093] As an example of the lower connecting portion, a first bracket h2d is provided on the back h2 (or may be a member fixed to the back h2). Furthermore, a second bracket h1h serving as a support is provided on the back frame h1 (or may be a member fixed to the back frame h1). An operating mechanism h5 is rotatably connected to the first bracket h2d and the second bracket h1h. As shown in FIG. 2 , a pair of operating mechanisms h5 are provided on the left and right sides of the chair A (specifically, the back frame h1). Meanwhile, as another example of the lower connecting portion, a configuration may be adopted in which the back h2 and the back frame h1 are connected without the intermediary of the operating mechanism h5 (not shown).

[0094] Next, the operation mechanism h5 will be described in detail. Here, FIG. 39 is an exploded perspective view of the operation mechanism h5 (hereinafter, the first main body portion h5a and the second main body portion h5g may be described as the main body portion h5a in an assembled state). Also, FIG. 40(A) is a perspective view of the operation mechanism h5, FIG. 40(B) is a front view thereof, and FIG. 40(C) is a side cross-sectional view thereof. In all figures, the operation mechanism h5 (h5A) located on the left side of chair A will be described as an example. Note that the operation mechanism h5 (h5B) located on the right side of chair A is configured symmetrically with the operation mechanism h5 (h5A). Note that the first bracket h2d and the second bracket h1h are also configured symmetrically with each other.

[0095] The operation mechanism h5 includes a first rotation part h31 that is rotatably connected to the first bracket h2d, and a second rotation part h32 that is rotatably connected to the second bracket h1h.

[0096] In this embodiment, a first pivot shaft h5i is provided on the first pivot portion h31 of the operation mechanism h5, and a first bearing h5v is provided on the first bracket h2d, so that the first pivot shaft h5i is rotatably supported by the first bearing h5v. This allows the operation mechanism h5 to be rotatably connected to the first bracket h2d. In this embodiment, a plain bearing structure is employed for the first bearing h5v (although other structures may also be employed). Furthermore, the first pivot shaft h5i and the first bearing h5v are configured to be easily engaged and disengaged (details will be described later). As a modified example, the first pivot shaft h5i may be provided on the first bracket h2d, the first bearing h5v is provided on the first pivot portion h31 of the operation mechanism h5, and the first pivot shaft h5i and the first bearing h5v may be configured to be easily engaged and disengaged (not shown).

[0097] Furthermore, a second rotation shaft h5o is provided on the second rotation portion h32 of the operation mechanism h5, and a second bearing (the aforementioned insertion hole) h5l is provided on the second bracket h1h, and the second rotation shaft h5o is rotatably supported by the second bearing h5l. This allows the operation mechanism h5 to be rotatably connected to the second bracket h1h. In this embodiment, a plain bearing structure is employed for the second bearing h5l (although other configurations may also be used). As a modified example, the second rotation shaft h5o may be provided on the second bracket h1h, and the second bearing h5l may be provided on the second rotation portion h32 of the operation mechanism h5 (not shown).

[0098] As shown in Figures 39 and 40(A) to 40(C), the operating mechanism h5 includes a main body h5a, an operating lever h5b rotatably attached to the main body h5a in one direction (the direction of arrow FD) and the opposite direction (the direction of arrow RD), and a stopper member h5c that advances and advances from the main body h5a in conjunction with the rotation of the operating lever h5b and engages and disengages with a locking portion h5d provided on the second bracket h1h. In this embodiment, the first and second rotation shafts h5i and h5o are arranged parallel to each other (i.e., their respective central axes are parallel). In this embodiment, the first and second rotation shafts h31 and h32 are arranged so that the first rotation shaft h31 moves forward when the operating lever h5b is rotated forward. Specifically, the first pivoting part h31 connected to the back h2 (first bracket h2d) is positioned relatively higher, and the second pivoting part h32 connected to the back frame h1 (second bracket h1h) is positioned relatively lower.

[0099] The operating mechanism h5 has an operating lever h5b attached to a main body h5a (first cylindrical portion h5ha) so as to be rotatable coaxially with the second rotation axis h5o of the second rotation portion h32. A stopper member h5c is attached to the main body h5a so as to be movable parallel to the second rotation axis h5o of the second rotation portion h32 but immovable around the axis of the second rotation axis h5o. As an example, the outer peripheral shape of the stopper member h5c in a front view (i.e., the shape when viewed parallel to the central axis of the second rotation axis h5o, which is the direction of movement) is formed into a star shape (including an approximately star shape) or a gear shape (including an approximately gear-shaped shape) having concave and convex portions on the outer peripheral surface. However, the shape is not limited thereto and may be an elliptical shape, an oval shape, or a polygonal shape (including an approximately polygonal shape). On the other hand, the inner peripheral surface (storage position of the stopper member h5c) of the main body portion h5a (second cylindrical portion h5hb) in which the stopper member h5c is stored is formed into a corresponding engaging shape (i.e., a shape that allows movement in parallel but does not allow movement around the axis). Also, the locking portion h5d of the second bracket h1h to which the stopper member h5c is locked (and unlocked) is formed so that the stopper member h5c can enter to an extent that it is locked, and its inner peripheral surface (entry position of the stopper member h5c) is formed into a corresponding engaging shape (i.e., a shape that allows movement in parallel but does not allow movement around the axis). However, with regard to the engagement structure between the stopper member h5c and the locking portion h5d, the rotational force transmitted from the operating lever h5b to the stopper member h5c generates slippage relative to the locking portion h5d depending on the amount of insertion (retraction) of the stopper member h5c into the main body portion h5a, allowing the stopper member h5c to move about its axis while inserting into the main body portion h5a against the biasing force. The convex portion of the stopper member h5c is formed with a tapered surface (including a curved surface) that tapers toward the tip and in the circumferential direction. This structure also provides a clicking sensation to the user when moving the spine portion h2 by operating the operating lever h5b. The switching position of the operating mechanism h5 can be set to any number of positions by adjusting the number of concave and convex portions provided on the outer peripheral surface of the stopper member h5c (for example, in this embodiment, three positions are set: front, middle, and rear positions, but this is not limited thereto).

[0100] The operation mechanism h5 also includes a neutral position return portion h24 that returns the operation lever h5b to a neutral position regardless of whether the operation lever h5b is rotated in either direction (FD direction or RD direction) relative to the main body portion h5a. As an example, the neutral position return portion h24 includes a biasing member (e.g., a coil spring) h5e and tapered surfaces (including curved surfaces) h5r and h5s that can slide against each other. The tapered surface h5r is provided on the outer peripheral surface of the operation lever h5b, and the tapered surface h5s is provided on the inner peripheral surface of the main body portion h5a (first cylindrical portion h5ha). These surfaces are shaped to move the operation lever h5b away from the main body portion h5a regardless of whether the operation lever h5b is rotated from the neutral position. The biasing member h5e is disposed within the second cylindrical portion h5hb of the main body portion h5a, sandwiched between a stopper member h5c fixed to the operating lever h5b and a partition portion h5hc of the main body portion h5a, generating a biasing force (resilient force). When the operating lever h5b is rotated from its neutral position (in the FD and RD directions), the tapered surfaces h5r and h5s slide against each other, causing the operating lever h5b to move in a direction away from (away from) the main body portion h5a and the stopper member h5c to move in a direction toward (retract into) the main body portion h5a. At this time, the biasing member h5e is compressed between the stopper member h5c and the partition portion h5hc, generating a biasing force (resilient force) that tends to return the biasing member h5e to its original position. Therefore, when the operation (rotation) of the operating lever h5b is stopped, the tapered surfaces h5r and h5s slide against each other due to the spring force, causing the operating lever h5b to move in the direction of entering the main body portion h5a and the stopper member h5c to move in the direction of exiting the main body portion h5a, and the operating lever h5b returns to its neutral position.

[0101] The operation mechanism h5 also includes a rotational force transmission unit h28 that transmits the rotational force of the operation lever h5b to the main body h5a when the operation lever h5b is rotated beyond a predetermined position in either direction (FD direction, RD direction) relative to the main body h5a. As an example, the rotational force transmission unit h28 includes a protrusion h28a and a groove h28b that do not come into contact with each other when the operation lever h5b is in a neutral position or when rotated from the neutral position to a position less than the predetermined position, but that can come into contact with each other when the operation lever h5b is rotated beyond the predetermined position. The protrusion h28a is provided on the inner peripheral surface of the main body h5a (first cylindrical portion h5ha), and the groove h28b is provided on the outer peripheral surface of the operation lever h5b (note that a configuration in which the protrusion h28a is provided on the operation lever h5b and the groove h28b is provided on the main body h5a may also be used). According to this, when the operating lever h5b is rotated beyond a predetermined position (FD direction, RD direction), the protrusion h28a and the groove h28b come into contact with each other, and the force that rotates the operating lever h5b is transmitted to the main body part h5a, causing the main body part h5a to rotate (rotate together with the operating lever h5b).

[0102] The movement of the back h2 of the chair A having the above configuration will be described. Note that, although the explanation will be given using the operating mechanism h5A as an example, since the chair A according to this embodiment is provided with a pair of operating mechanisms h5 (h5A, h5B) on the left and right, the same operation is also performed simultaneously on the operating mechanism h5B.

[0103] Here, Figures 41(A) to 41(F) show the case where the operating lever h5b of the operating mechanism h5A is rotated in the direction of the arrow FD, and Figures 41(A), 41(C), and 41(E) are views viewed from the front (viewed from a direction parallel to the first rotating axis h5i and the second rotating axis h5o), and Figures 41(B), 41(D), and 41(F) are views viewed from the side (viewed from a direction perpendicular to the first rotating axis h5i and the second rotating axis h5o).

[0104] First, as shown in Figures 41(A) and 41(B), when the operating lever h5b is in the neutral position (when the operating lever h5b is not being operated), the biasing force (resilient force) of the biasing member h5e of the neutral position return portion h24 biases the stopper member h5c in a direction of advancing from the main body portion h5a (in a direction of abutting against the locking portion h5d provided around the second bearing h5l of the second bracket h1h). As a result, the stopper member h5c is locked by the locking portion h5d, and rotation of the main body portion h5a is restricted. In this state, even if the back portion h2 itself is held and pushed back or forth, the pushing force does not rotate the operating mechanism h5, and therefore the back portion h2 does not move back or forth.

[0105] 41(C) and 41(D), when the operating lever h5b is rotated from the neutral position to less than a predetermined position (i.e., the amount of rotation is less than a predetermined angle), the tapered surface h5r of the operating lever h5b and the tapered surface h5s of the main body portion h5a slide against each other, and the operating lever h5b moves in the direction of advancing (moving away) from the main body portion h5a (direction of arrow OD), while the stopper member h5c moves in the direction of advancing (pulling into) the main body portion h5a (direction of arrow ID). At this time, the stopper member h5c is locked by the locking portion h5d, and the state in which the rotation of the main body portion h5a is restricted is maintained.

[0106] 41(E) and 41(F), when the operating lever h5b is rotated from the neutral position to a predetermined position or more (i.e., the rotation amount is a predetermined angle or more), the protrusion h28a of the main body portion h5a (first cylindrical portion h5ha) and the groove h28b of the operating lever h5b come into contact with each other, and the force rotating the operating lever h5b is transmitted to the main body portion h5a. At this time, the tapered surfaces h5r and h5s stop sliding against each other, and the operating lever h5b stops moving forward from the main body portion h5a. Meanwhile, as the stopper member h5c fixed to the operating lever h5b is rotated, slippage occurs with respect to the locking portion h5d, and the stopper member h5c moves about the axis while advancing a small amount further into the main body portion h5a against the biasing force. That is, the stopper member h5c and the locking portion h5d are disengaged, allowing the main body h5a to rotate (together with the operating lever h5b). Accordingly, the main body h5a rotates in conjunction with the rotation of the operating lever h5b, causing the first rotation portion h31 to move in an arc (in the direction of the arrow TD). If the operation of the operating lever h5b (the operation of rotating it in the direction of the arrow FD) is stopped from this state, the neutral position return portion h24 acts to move the operating lever h5b in the opposite direction (direction RD) while moving in a direction toward the main body h5a, and the stopper member h5c moves in a direction toward the main body h5a, returning the operating lever h5b to the neutral position.

[0107] In this way, by rotating the operating lever h5b of the operating mechanism h5A (h5B is operated in the same way) from rear to front (FD direction) within the movable range, the first rotating part h31 can be moved from rear to front. Therefore, the second bracket h1h to which the first rotating part h31 is connected can be moved from rear to front, and the back part h2 can be moved from rear to front relative to the back frame h1 (specifically, moved forward by swinging around the upper connecting part hu as a fulcrum).

[0108] 42(A) to 42(F) show the case where the operating lever h5b of the operating mechanism h5A is rotated in the direction of arrow RD, with Figs. 42(A), 42(C), and 42(E) being views from the front (viewed from a direction parallel to the first rotation axis h5i and the second rotation axis h5o), and Figs. 42(B), 42(D), and 42(F) being views from the side (viewed from a direction perpendicular to the first rotation axis h5i and the second rotation axis h5o). Note that the operations shown in Figs. 42(A) to 42(F) are the same as those shown in Figs. 41(A) to 41(F) except that the rotation directions of the operating lever h5b and the main body h5a are opposite to those shown in Figs. 41(A) to 41(F) (repeated explanation will be omitted).

[0109] In this way, by rotating the operating lever h5b of the operating mechanism h5A (h5B is operated in the same way) from front to rear (RD direction) within the movable range, the first rotating part h31 can be moved from front to rear. Therefore, the second bracket h1h to which the first rotating part h31 is connected can be moved from front to rear, and the back part h2 can be moved from front to rear relative to the back frame h1 (specifically, moved rearward by swinging around the upper connecting part hu as a fulcrum).

[0110] On the other hand, when the operating lever h5b is not operated, the operating lever h5b can be maintained in the neutral position as described above. In other words, the movement of the operating mechanism h5 can be kept restricted, and the position of the back h2 can be kept unchanged. Therefore, a configuration can be realized that can solve the problems of conventional chairs, that is, a configuration in which the back h2 does not move unless the operating lever h5b is operated, and the back h2 moves by rotating the operating lever h5b, thereby preventing the back h2 from moving unexpectedly.

[0111] In another embodiment, the chair A may be configured so that the back h2 does not move back and forth relative to the back frame h1 without providing an operating mechanism h5, i.e., the first pivot axis h5i is fixed directly to the back frame h1 (not shown).

[0112] Next, the connection structure between the operating mechanism h5 and the back h2 will be described in detail. Here, Fig. 43 is a cross-sectional view (viewed from a direction parallel to the first rotation axis h5i and the second rotation axis h5o) for explaining the connection structure between the operating mechanism h5 and the back h2.

[0113] As described above, the first rotating shaft h5i is provided on the first rotating part h31 of the operating mechanism h5, the first bearing h5v is provided on the first bracket h2d, and the first rotating shaft h5i and the first bearing h5v are configured to be engageable and disengageable.

[0114] Specifically, as shown in FIG. 43 , the first bearing h5v is made of an elastic resin material and is integrally formed with the back portion h2 (or may be a separate structure) to have a C-shaped (or U-shaped) cross section. The first bearing h5v has a first opening h13 through which the first rotating shaft h5i can enter and exit in a direction perpendicular to its central axis. Meanwhile, the operating mechanism h5 is provided with a housing portion h30 having a second opening h23 through which the first bearing h5v can enter and exit, and the first rotating shaft h5i is disposed within the housing portion h30. The first rotating shaft h5i has a hollow cylindrical (or may be a solid columnar) cross section. In this embodiment, the first bearing h5v and the first rotating shaft h5i are configured to be engageable and disengageable with each other via a snap-fit ​​structure that allows the first bearing h5v to elastically deform. This allows the back portion h2 to be attached and detached from the back frame h1 extremely easily and in a short time, and also allows for a configuration in which no rattle occurs when the back portion h2 is moved relative to the back frame h1 by the operating mechanism h5.

[0115] Furthermore, the chair A according to this embodiment is provided with a disengagement restriction unit h60 that restricts engagement and disengagement (referring to a state in which one is disengaged from the other) between the first bearing h5v and the first rotating shaft h5i when the back h2 is connected to the back frame h1 and the operating mechanism h5 (i.e., the engaged first bearing h5v and first rotating shaft h5i) is positioned at least at the front end within its movable range. Fig. 44 is a diagram showing an example of the configuration of the disengagement restriction unit h60, with Fig. 44(A) illustrating a state in which the operating mechanism h5 is at the front end position within its movable range, and Fig. 44(B) illustrating a state in which the operating mechanism h5 is at the rear end position within its movable range.

[0116] As shown in FIG. 44A , the detachment prevention portion h60 is configured such that an abutment member provided on the operating mechanism h5 abuts against a predetermined portion of the first bracket h2d when the angle between the opening direction of the first opening h13 and the opening direction of the second opening h23 deviates by a predetermined angle θ degrees from 180 degrees, which is the collinear angle. This configuration prevents disengagement between the first bearing h5v and the first pivot shaft h5i, even when the back portion h2 is pulled in the direction of arrow DD relative to the operating mechanism h5. Therefore, the first bracket h2d (predetermined portion) abuts against the operating mechanism h5 (abutment member), preventing disengagement between the first bearing h5v and the first pivot shaft h5i. As an example, θ is set to 20 degrees, but this is not limiting. The angle θ may be set so that the detachment prevention portion h60 acts to prevent disengagement from a position before the operating mechanism h5 reaches the front end position within its movable range.

[0117] As an example, the abutment member provided on the operating mechanism h5 is composed of two walls (a first wall h5ta and a second wall h5tb) spaced apart and arranged parallel to the axial direction and sandwiching the first pivot shaft h5i. Meanwhile, the predetermined portion of the first bracket h2d is composed of the outer surface h5va of the first bearing h5v. In this way, the disengagement prevention portion h60 is realized with a simple configuration by utilizing a configuration that engages and disengages the first bearing h5v and the first pivot shaft h5i. However, this configuration is not limited to this. Note that, if the other example described above (a lower connecting portion that does not interpose the lower operating mechanism h5) is adopted, the abutment member may be provided on the back frame h1 (not shown).

[0118] According to the above configuration, it is possible to realize a configuration in which the back portion h2 can be attached and detached to and from the back frame h1 extremely easily and in a short time, and it is also possible to prevent the back portion h2 from coming off the back frame h1 even if an unintended force is applied when the back portion h2 is moved relative to the back frame h1 by the operating mechanism h5. In this embodiment, the detachment prevention portion h60 can be realized with a simple configuration by utilizing the configuration in which the first bearing h5v and the first rotating shaft h5i are engaged and disengaged.

[0119] 44(B), the present embodiment is configured to obtain the same effect as above even when the operating mechanism h5 (i.e., the engaged first bearing h5v and first rotating shaft h5i) is positioned at the rear end of its movable range. Also, similar to the above, the angle θ may be set so that the separation restriction by the separation restriction part h60 acts from a position before the operating mechanism h5 reaches the rear end position within its movable range.

[0120] On the other hand, when attaching or detaching the back portion h2 to or from the back frame h1, the detachment restriction by the detachment restriction portion h60 can be prevented. Specifically, as shown in FIG. 45 , the connection between the back portion h2 and the back frame h1 at the upper connecting portion hu is released, and the back portion h2 is moved (rotated) to a predetermined position forward relative to the back frame h1 (at this time, the central axis of the first rotation shaft h5i serves as the fulcrum). In this case, the predetermined position is a position where the angle between the opening direction of the first opening h13 and the opening direction of the second opening h23 is 180 degrees, so that they are on the same straight line, or a position where the angle θ relative to 180 degrees is an angle that does not cause detachment restriction (in the above example, 0 degrees < θ < 20 degrees). When the back portion h2 has been moved (rotated) to the predetermined position, the first bearing h5v and the first rotation shaft h5i can be engaged and disengaged, allowing the back portion h2 to be attached or detached from the back frame h1. In contrast, when the back h2 is not moved (rotated) to the above-mentioned specified position, the first bearing h5v and the first pivot shaft h5i cannot be engaged or disengaged, and therefore the back h2 cannot be attached or detached from the back frame h1.

[0121] As described above, according to the present invention, it is possible to realize a chair configured such that the position of a component (for example, the back of the backrest) does not change unless the operating lever is operated, thereby preventing the component from moving unexpectedly when the operating lever is not being operated.

[0122] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention. In particular, the operating mechanism has been described using the back of the backrest as an example of the chair's target component, but is not limited to this and can be applied as an operating mechanism for other components (seat, legs, headrest, armrests, etc.).

[0123] Furthermore, as an example of the lower connecting part, a configuration in which an operating mechanism is interposed, i.e., a configuration in which the back is connected to an operating mechanism supported and fixed to the back frame, has been described as an example, but this is not limited to this, and as another example, it can also be applied to a configuration in which no operating mechanism is interposed, i.e., a configuration in which the back is connected directly to the back frame.

[0124] A: Chair B: Leg b1: Caster, b2: Leg blade, b3: Leg support C: Support base c1: Mounting hole, c2: Reaction spring, c3: Reaction spring receiver, c4: Link plate, c5: Slot, c6: Rocking force adjustment lever, c7: Rocking operation lever D: Seat d1: Seat receiver, d2: Seat body, d3: Cushion, d4: Recess, d5: Protrusion, d6: Shaft accommodating hole, d7: Opening, d8: Spring holder, d9: Spring, d10: Pressure plate, d11: Synchro 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 part H: Backrest h1: back frame, h2: back, h3: upholstery, h4 lumbar support, h5: operating mechanism, h6: first upholstery engaging body, h7: second upholstery engaging body J1: rotation axis, J2: synchro shaft, J3 locking axis, J4: shaft body T: tag X: headrest x1: attachment part, x2: head contact part, x3: clamp part, x4: slider part, x5: height adjustment mechanism, x6: frame body, 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: armrest receiving part, y22: armrest body 10: seat receiving-synchronized shaft connecting structure (rotating body connecting structure)

Claims

1. An operating mechanism for changing the position of chair components, comprising: a main body; an operating lever attached to said main body so as to be rotatable in one direction and the other direction; and a stopper member which advances and advances from said main body in conjunction with the rotation of said operating lever and which engages and disengages with a locking portion provided on a support portion disposed on said chair.

2. An operating mechanism as described in claim 1, characterized in that when the operating lever is in the neutral position or when it is rotated from the neutral position to a position less than a specified position, the stopper member is engaged with the engaging portion, and when the operating lever is rotated from the neutral position to a position greater than the specified position, the main body is rotated in conjunction with the rotation of the operating lever.

3. The operating mechanism according to claim 1, characterized in that the stopper member is attached to the main body so as to be movable parallel to the rotation axis of the operating lever and immovable around the axis of the rotation axis.

4. An operating mechanism as claimed in claim 1, characterized in that it has a neutral position return part which returns the operating lever to a neutral position regardless of the direction in which the operating lever is rotated relative to the main body.

5. A chair comprising: an operating mechanism as defined in any one of claims 1 to 4; and a backrest having a back frame and a back portion connected to the back frame, wherein the operating mechanism is rotatably connected to a first bracket provided on the back portion or a member fixed to the back portion, and is rotatably connected to a second bracket provided on the back frame or a member fixed to the back frame, and wherein the operating mechanism is configured to change the position of the back portion relative to the back frame by rotating the operating lever.

6. A chair as described in claim 5, characterized in that said operating mechanism comprises a first rotating part rotatably connected to said first bracket, and a second rotating part rotatably connected to said second bracket, said second rotating part being provided on said main body with a rotation axis parallel to the rotation axis of said first rotating part.

7. A chair as claimed in claim 5, characterized in that the operating mechanisms are provided in a pair on the left and right sides of the back frame.

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