Chair and chair operation mechanism

Abstract

To provide an operation mechanism which prevents the position of the components of a chair from varying unless an operation lever is operated.SOLUTION: An operation mechanism h5 for operation of varying the position of the components of a chair A comprises: a main body h5a; an operation lever h5b fitted to the main body h5a rotatably in one direction and the opposite direction; and a stopper member h5c which moves out and in from the main body h5a with the rotation of the operation lever h5b and is engaged with and disengaged from an engaging part h5d provided at a support part h1h disposed at the chair A.SELECTED DRAWING: Figure 39

Description

[Technical field]

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

[0002] Conventionally, chairs equipped with components such as a backrest, a seat, legs, a headrest, and armrests have been known. Taking the backrest as an example, a configuration is known in which the back, to which the upholstery that the back of the seated person comes into contact with is fixed, moves (rocks) back and forth relative to a back frame to switch between support and non-support of the seated person's lower back (Patent Document 1: JP 2017-086669 A). Specifically, the configuration is such that the back can be moved back and forth by rotating an operating lever attached to the lower part of the backrest. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-086669 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional chair exemplified in the above 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, but on the other hand, the back can move back and forth without operating the operating lever. For example, if the back itself is held and pushed back and forth, the link rotates and the back moves back and forth. As such, there is a risk that the back may move unexpectedly, and a solution to this problem was sought. [Means for solving the problem]

[0005] The present invention has been made in consideration of the above circumstances, and has an 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 for performing an operation to change the position of components of a chair, and requires that it comprises a main body, an operating lever attached to the main body so as to be rotatable in one direction and the other direction, and a stopper member which advances and advances from the main body in conjunction with the rotation of the operating lever, and which engages and disengages with a locking portion provided on a support portion arranged on the chair.

[0008] This makes it possible to realize a configuration in which the position of the target component does not change unless the operating lever is operated, thereby preventing the conventional problem, i.e., the component moving unexpectedly.

[0009] It is also preferable that the stopper member is engaged with the engaging portion when the operating lever is in the neutral position or when the operating lever is rotated from the neutral position to a position less than a predetermined position, and 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 equal to or 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, and the components move when the operating lever is rotated.

[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 and 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 includes the operating mechanism, a backrest having a back frame and a back portion connected to the back frame, the operating mechanism being rotatably connected to a first bracket provided on the back portion or a member fixed to the back portion, and rotatably connected to a second bracket provided on the back frame or a member fixed to the back frame, and configured to perform an operation to change the position of the back portion relative to the back frame by rotating the operating lever. This allows for a configuration in which the position of the back portion does not change unless the operating lever is operated.

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

[0013] It is also preferable that the operation mechanisms are provided in pairs at the left and right positions of the back frame. In this way, the configuration in which the operation 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 so that it does not deform diagonally in particular. Effect of the Invention

[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, and therefore it is possible to prevent the component from moving unexpectedly. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a front perspective view of the chair according to the embodiment. [Diagram 2] FIG. 2 is a rear perspective view of the chair according to the embodiment. [Diagram 3]FIG. 13 is a front perspective view showing the seat disassembled from the support base with the armrests removed; [Figure 4] FIG. 2 is an enlarged perspective view of the periphery of the support base. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. [Figure 8] 1A is a front perspective view of a pressure plate, and FIG. 1B is a rear perspective view of the pressure plate. [Figure 9] 9 is a schematic cross-sectional view taken along line IX-IX in Fig. 6. (A) is a view before the stopper body is attached, and (B) is a view after the stopper body is attached. [Figure 10] 1A is a front perspective view of a stopper body, and FIG. 1B is a rear perspective view of the stopper body. [Figure 11] FIG. 2 is a front perspective view of the back support; [Figure 12] FIG. 2 is a front perspective view showing the backrest in an exploded state. [Figure 13] FIG. 2 is a rear perspective view showing the backrest in an exploded state. [Figure 14] FIG. 2 is a front view of a first upholstery engagement body (A) and a front view of a second upholstery engagement body (B). [Figure 15] 11 is an explanatory diagram showing a state in which a first upholstery engagement body is engaged with a back portion. FIG. [Figure 16] FIG. 2 is a rear perspective view of the back and lumbar support. [Figure 17] FIG. [Figure 18] FIG. 1 is an exploded perspective view of the operating mechanism. [Figure 19] FIG. 2 is a second exploded perspective view of the operating mechanism. [Figure 20] FIG. [Figure 21] FIG. 4 is a front perspective view showing a state in which a clamp portion is removed from the headrest. [Figure 22]1A is a rear perspective view of a top of a height adjustment mechanism, and FIG. 1B is a front perspective view of the top of the height adjustment mechanism. [Figure 23] FIG. 4 is a side view showing the state of the top and the cam surface. [Figure 24] 4 is a cross-sectional view showing the state of a top and a cam surface. FIG. [Diagram 25] 11 is a cross-sectional view showing a state in which the piece is prevented from falling out by a stopper. FIG. [Figure 26] 11 is a cross-sectional view showing a state in which an unattached piece is restricted by an erroneous attachment prevention stopper. FIG. [Figure 27] FIG. [Figure 28] 28 is a rear perspective view showing a state in which the decorative frame is removed from FIG. 27. FIG. [Figure 29] 13 is an explanatory diagram showing a method of attaching the third upholstery engagement body and the fourth upholstery engagement body to the frame body of the attached upholstery. FIG. [Diagram 30] 13 is a rear view of the upholstery to which the third upholstery engagement body and the fourth upholstery engagement body are attached. [Diagram 31] This shows a front view (A) of the fourth upholstery engagement body, a front view (B) of the fourth upholstery engagement body stretched in the longitudinal direction, a front view (C) of the fourth upholstery engagement body compressed in the longitudinal direction, and a front view (D) of the fourth upholstery engagement body bent in the longitudinal direction. [Diagram 32] FIG. 2 is a front perspective view showing the armrest in a disassembled state. [Diagram 33] FIG. 2 is a rear perspective view showing the armrest in a disassembled state. [Diagram 34] FIG. 2 is a front perspective view showing the elbow rest in an exploded state. [Diagram 35] This shows a side view (A) of the main part showing the state when the elbow rest is moved rearward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Diagram 36] This shows a side view (A) of the main part showing the state when the elbow rest is moved forward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Figure 37]This shows a side view (A) of the main part showing the state when the elbow rest is moved forward and facing inward, a plan view (B) of the main part, a plan view (C) of the first path, and a plan view (D) of the second path portion. [Figure 38] FIG. 2 is an explanatory diagram for explaining the operation of the backrest of the chair in FIG. [Figure 39] FIG. 2 is an exploded perspective view of the operating mechanism of the chair of FIG. [Diagram 40] 40A, 40B, and 40C are diagrams showing an example of an operating mechanism of the chair of FIG. 1, in which FIG. 40A is a perspective view, FIG. 40B is a front view, and FIG. 40C is a side cross-sectional view. [Diagram 41] 41(A) to 41(F) are explanatory diagrams illustrating the operation of the operating mechanism of the chair in FIG. [Diagram 42] 42(A) to 42(F) are explanatory diagrams illustrating the operation of the operating mechanism of the chair in FIG. [Diagram 43] 2 is an explanatory diagram illustrating a connecting structure between the operating mechanism and the back of the chair in FIG. 1. FIG. [Diagram 44] 44A and 44B are diagrams showing examples of the removal prevention part of the chair in FIG. 1, in which FIG. 44(A) shows the operating mechanism in a state where it is at the front end position within the movable range, and FIG. 44(B) shows the operating mechanism in a state where it is at the rear end position within the movable range. [Diagram 45] 11A and 11B are explanatory diagrams illustrating the attachment and detachment operation of the back portion to the back frame. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0017] This embodiment illustrates a chair A in which the present invention is applied to a connection structure for connecting a seat support d1 as a rotating body to a synchronous 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 with respect to the support base C, a headrest X attached to the backrest structure F, and an armrest Y attached to the seat D. The backrest structure F includes a back support G supported by the support base C, and a backrest H supported by the back support G.

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

[0020] (Leg B) The leg B comprises a number of leg blades b2 arranged radially, each having a caster b1 at its tip, and a leg support b3 erected at the base end of each of the leg blades b2. The leg support b3 is extendable in the vertical direction. The leg support b3 has a gas spring (not shown), which supports the support base C so that its position can be changed vertically. The specific shape of the leg B is not particularly limited, and other known configurations can be appropriately adopted.

[0021] (Support base C) FIG. 4 is a perspective view of the peripheral portion of the support base C in FIG. 3. In this embodiment, the support base C is formed in a bottomed box shape. A mounting hole c1 (see FIG. 2) is formed on the rear bottom surface of the support base C. The support base C is attached to the upper part of the leg support b3 by inserting the leg support b3 into the mounting hole c1. In the left-right direction of the support base C, a rotation axis J1 during rocking operation, a synchronous shaft J2 as a rotating shaft, and a locking shaft J3 for locking the first end of the reaction spring c2 during rocking are hung. The second end of the reaction spring c2 is engaged with a reaction spring receiving portion c3 arranged on the support base C. The rotation axis J1, the synchronous shaft J2, and the locking shaft J3 all pass through a link plate c4 arranged between the left and right walls. An arm g1 of the back support G is connected to the rotation axis J1. A seat receiver d1 of seat D is fitted to the synchronous shaft J2 so as to be rotatable around the axis of the synchronous shaft J2. One end of a reaction spring c2 is engaged with the locking shaft J3. The link plate c4 rotates around the rotation shaft J1 as the center of rotation to achieve a locking action. During the locking action of the backrest H, the link plate c4 and the synchronous shaft J2 move the seat D in synchronization with the locking action. In this way, the rotation shaft J1, the synchronous shaft J2, the locking shaft J3, and the link plate c4 form a synchronous locking mechanism, which achieves a synchronous locking action.

[0022] In addition, an arc-shaped long hole c5 is formed in the left and right walls at the front end of the support base C. The shaft body J4 is arranged so as to span the long holes c5 in the left and right direction. The long hole c5 and the shaft body J4 guide the movement of the seat D by the link plate c4 and the synchronous shaft J2 so that the movement is made along a predetermined trajectory when the backrest H is rocked. The shaft body J4 also serves as a part of the forward tilt mechanism of the seat D, which will be described later. A locking force adjustment lever c6 is arranged on the right front part of the support base C to adjust the operating force required for the rocking operation. A locking operation lever c7 is arranged on the left rear part of the support base C to switch the lock on and off at the initial position (standing position) of the rocking operation. The other components of the support base C shown in Figures 3 and 4 are known, so a description thereof will be omitted here.

[0023] (Locus D) As shown in FIG. 3, the seat D includes a seat support d1 as a shell-shaped rotating body, and a seat body d2 and a cushion d3 that are arranged on the seat support d1 so that their front-rear positions can be changed. As shown in FIGS. 5 to 7, a recess d4 with an open bottom is formed on the front part of the bottom surface of the seat support d1. Two protrusions d5 with arcuate bottom surfaces are erected in the recess d4. A shaft body accommodating hole d6 is drilled at the outer side position in the left-right direction of the protrusions d5, and is positioned at the same height position as the height position of the arcuate surface of the protrusions d5. The shaft body J4 is inserted through the left and right shaft body accommodating holes d6. In this state, the upper surface of the shaft body J4 is in contact with the arcuate surface of the protrusions d5. An opening d7 is arranged on the upper surface of the seat support d1 at a planar position that is the outer side of the shaft body accommodating hole d6 in the left-right direction. As shown in the side cross-sectional view of seat D, the spring holder d8 and the spring d9 are housed in the opening d7 on the upper surface of the shaft J4 in the order shown from the side (lower side) of the shaft J4. Also, a pressure plate d10 is attached to the opening d7 to house the spring d9 in a biased state.

[0024] As shown in FIG. 8, the pressing plate d10 is formed in a rectangular shape in a plan view. An upper protrusion d10a that protrudes upward is formed at one end edge portion in the longitudinal direction. A front protrusion d10b that protrudes in the longitudinal direction of the pressing plate d10 is formed at the end face opposite to the end portion on which the upper protrusion d10a is formed. A rear entry portion d7a through which the upper protrusion d10a can pass is formed at the opening d7 of the seat receiver d1, and a fitting hole d7b into which the upper protrusion d10a fits is formed at a position adjacent to the rear entry portion d7a behind the rear entry portion d7a. In addition, a front entry portion d7c into which the front protrusion d10b can enter is formed at a front position of the opening d7. The planar positions of the fitting hole d7b and the front entry portion d7c are aligned with the planar positions of the upper protrusion d10a and the front protrusion d10b of the pressing plate d10. The depth dimension of the rear entry portion d7a is formed to be greater than the longitudinal length dimension of the pressing plate d10.

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

[0026] In this way, the seat support d1 can move back and forth between the top surface height position of the shaft body J4 and the bottom surface height position of the pressure plate d10 within a range where the spring d9 can be compressed, by the shaft body J4 held by the support base C, the spring holder d8 and spring d9 placed on the shaft body J4, and the pressure plate d10. In other words, when the seat occupant applies a downward force (external force) against the biasing force of the spring d9 to the front part of the seat D, the seat D can be tilted forward. When the seat D is tilted forward, the biasing force of the spring d9 increases, and when the external force applied to the seat D is released, the seat D returns to its initial position due to a part of the accumulated biasing force. At this time, the shaft body J4 moves back and forth in an oblique vertical direction along the long hole c5 formed in the support base C.

[0027] As shown in FIG. 5, the central portion of the lower surface of the seat support d1 is provided with a synchronous shaft mounting portion d11, which is a communication portion that communicates the upper surface and the lower surface of the seat support d1. In this embodiment, the synchronous shaft mounting portion d11 has an inclined convex portion d11a as a plurality of inclined surface forming bodies erected toward the lower side of the seat support d1, and an arc-shaped abutment portion d11b as a plurality of abutment portions having an arc-shaped abutment surface. The inclined convex portion d11a and the arc-shaped abutment portion d11b are both formed in a rib shape and are arranged along the length direction of the synchronous shaft mounting portion d11. When mounting the seat support d1 to the synchronous shaft J2, the synchronous shaft J2 is inserted into the synchronous shaft mounting portion d11 along the inclined convex portion d11a, and the outer circumferential surface of the synchronous shaft J2 is abutted against the arc-shaped abutment portion d11b. By bringing the synchro shaft J2 into contact with the arc-shaped contact portion d11b, the seat d1 can be attached to the synchro shaft J2 in an appropriate state.

[0028] FIG. 9 is a cross-sectional view of the main part of the seat d1 attached to the synchronous shaft J2. As is clear from FIG. 9(A), an opening hole d12 communicating with the synchronous shaft mounting part d11 is formed on the upper surface of the seat d1. In this embodiment, the opening hole d12 is disposed at the same longitudinal position as the longitudinal (lateral) position of the synchronous shaft mounting part d11 of the arc-shaped abutment part d11b. The opening hole d12 can also be disposed at a longitudinal position different from the longitudinal (lateral) position of the synchronous shaft mounting part d11 of the arc-shaped abutment part d11b. This opening hole d12 is formed in a shape that intersects with the inclined surface d11x of the inclined protruding part d11a when viewed from the side. More specifically, the inclined protruding part d11a has an inclined surface d11x that extends from a lower surface opening that opens downward and forward to the upper rear. In contrast, the opening hole d12 is formed as an inverted inclined hole that extends from a lower opening that opens downward rearward to an upper frontward direction (inclined in the opposite direction to the inclined surface d11x). As a result, the inclined surface d11x formed by the inclined protrusion d11a and the inner peripheral surface d12x of the opening hole d12 form a V-shape in side view.

[0029] A first engagement recess d12a is formed on the inner peripheral surface d12x of the opening hole d12, and a second engagement recess d12b is formed on the periphery of the opening on the upper surface of the seat holder d1 of the opening hole d12 (see FIG. 6). As shown in FIG. 9(B), a stopper body d13 is attached to the opening hole d12 to prevent the synchronizer shaft J2 inserted into the synchronizer shaft mounting portion d11 from coming off. By attaching the stopper body d13 to the opening hole d12 as shown in FIG. 9(B), a seat holder-synchronizer shaft connection structure 10 is formed as a rotating body connection structure, and the seat holder d1 is rotatably connected along the outer peripheral surface of the synchronizer shaft J2.

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

[0031] The stopper body d13 thus formed is attached by inserting the inclined portion d13b from the upper surface side of the seat d1 along the inner peripheral surface d12x of the opening hole d12. At this time, the engagement claw d13d formed on the front surface of the inclined portion d13b moves along the inner peripheral surface d12x of the opening hole d12 while being elastically deformed. When the engagement claw d13d reaches the position of the first engagement recess d12a formed on the inner peripheral surface d12x of the opening hole d12, the elastic deformation of the engagement claw d13d is restored and the engagement claw d13d is engaged with the first engagement recess d12a, and the stopper body d13 is prevented from coming off. In this state, the rear protrusion d13c is also engaged (engaged) with the second engagement recess d12b formed at the opening of the opening hole d12. That is, the state in which the synchronization shaft J2 is loosely fitted or engaged in the synchronization shaft fitting portion d13f can be released and the movement in two directions is restricted. The downward protrusion d13e is used as a reinforcing portion that reinforces the lower end portion of the synchro shaft fitting portion d13f.

[0032] In this way, even if the seat holder d1 to which the synchronous shaft J2 and the stopper body d13 are attached is pulled upward and a force in the direction of the arrow A in FIG. 9(B) acts, the movement of the seat holder d1 in the direction of the arrow A is restricted by the stopper body d13. This makes it possible to prevent the seat holder d1 from coming off the synchronous shaft J2. If the stopper body d13 is removed from the opening hole d12 of the seat holder d1, the seat holder d1 can be easily removed from the synchronous shaft J2. In this way, the seat holder d1 in this embodiment is advantageous in that it can be attached to and disassembled from the synchronous shaft J2 without using tools. The seat D attached to the synchronous shaft J2 in this way is configured to move in synchronization with the backward tilting movement (rocking movement) of the backrest H by the rotating shaft J1, the link plate c4, and the synchronous shaft J2.

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

[0035] The left and right arms g1 are paired and are plate-like extending in the front-rear direction, with shaft holes g3 disposed in the front portions thereof for inserting and fixing the rotating shaft J1 and the synchronous shaft J2. The left and right arms g1 are supported so as to be rotatable about the rotating shaft J1 inserted and fixed in the shaft holes g3. The rear surface (back surface) of the connecting plate g2 is provided with a plurality of bolt insertion holes (not shown) for inserting a plurality of bolts (not shown). A nut portion g4 is fixed by welding to the front side (front surface) of each bolt insertion hole. In addition, a locking operation lever c7 is rotatably attached to the arm g1.

[0036] (Backrest H) 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 the rear side of the upholstery h3, and an operating mechanism h5 for positioning the back portion h2 in a manner that allows the position of the back portion h2 to be changed in the front-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 is arranged in front of the back frame h1 with the back part h2 covered with upholstery h3 so that the position can be changed in the front-rear direction. With such a configuration of the backrest H, the back part h2 as a whole can be easily elastically deformed, and the back part h2 can be easily given flexibility to envelop the back of the seated person. The entire backrest H can be tilted backward around the 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 installed between the upper ends of the left and right side frame portions h1a, left and right lower frame portions h1c extending forward from the lower ends of the left and right side frame portions h1a, respectively, and a lower connecting portion h1d that connects the left and right lower frame portions h1c to each other and is fastened to a connecting plate g2 of the back support body G. The left and right side frame portions h1a, the upper frame portion h1b, the left and right lower frame portions h1c, and the lower connecting portion h1d are molded from synthetic resin and assembled together.

[0039] The left and right side frame portions h1a of the back frame h1 are each shaped as a member that gradually becomes wider toward the bottom. The side frame portions h1a of the back frame h1 are arranged on the back side of the side portion of the backrest surface that is mainly composed of the upholstery h3 stretched over the back portion h2. The left and right side frame portions h1a are roughly doglegged when viewed from the side and from the front, and the upper and lower portions of the left and right side frame portions h1a are continuous via a bent portion.

[0040] The upper frame portion h1b of the back frame h1 is disposed on the upper back side of the backrest surface, and is a structural frame that connects the upper ends of the side frame portions h1a to each other. The upper frame portion h1b is provided with an element that constitutes an upper connecting portion for attaching the upper end of the back portion h2. That is, the front surface of the upper frame portion h1b is provided with a plurality of recesses h1e and protrusions h1f that open forward in the left-right direction. The bottom surface of the upper frame portion h1b is provided with bolt insertion holes h1g that communicate with each recess h1e.

[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. That is, the left and right lower frame portions h1c are partially located outside the left and right arms g1 of the back support G. In other words, the left and right lower frame portions h1c extend in the front-rear direction, and their front ends extend to both sides of the support base C arranged below the seat D. In addition, a second bracket h1h is provided upright on the lower frame portion h1c.

[0042] (back h2) The back part h2, which is disposed in front of the back frame h1, is attached to the back frame h1 at the upper end and the left and right lower parts. On the back side of the upper end part of the back part h2, a convex part h2a that fits concavely into the concave part h1e formed in the upper frame part h1b of the back frame h1 and a concave part h2b that fits into the convex part h1f are disposed so as to correspond to each of the concave part h1e and the convex part h1f. In addition, an engagement groove h2c is disposed on the back side of the back part h2 to engage the upholstery h3 at a location corresponding to the side frame part h1a and the lower frame part h1c of the back frame h1. A first bracket h2d that is connected to an operating mechanism h5 connected to the back frame h1 is formed on the lower left and right rear parts of the back part h2. That is, the back part h2 is movably connected to the back frame h1 via the operating mechanism h5.

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

[0044] Furthermore, an insertion hole h6c through which the engagement pin KP is inserted is formed in the center of the upper end of the back h2 of the first upholstery engagement body h6. A cut line h6d is formed around the insertion hole h6c so as to surround the insertion hole h6c in an inverted U-shape, allowing localized elastic deformation when the engagement pin KP is inserted into the insertion hole h6c and preventing the first upholstery engagement body h6 from floating up to the upper end of the back h2. A second upholstery engagement body h7 to be inserted into the engagement groove h2c as shown in Fig. 14(B) is attached by sewing to the outer peripheral edge of the side portion and lower end of the upholstery h3.

[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 dimension as the tag T. If the tag T is inserted into the slit h7a and sewn to the upholstery h3, the tag T can be easily attached to a predetermined position on the chair A. The tag T can display the name of the manufacturer or brand of the chair A, a video playback page for explaining how to use the chair A, or a URL for an advertising page or a page for directing to an SNS (social network service).

[0046] The following describes how the upholstery h3, which has the first upholstery engaging body h6 and the second upholstery engaging body h7 sewn to the entire outer periphery, is stretched over the back h2. The upholstery h3 encases the back h2 from the front side of the back h2, and the mounting parts h6a and h6b of the first upholstery engaging body h6 at the upper edge of the upholstery h3 are aligned with the convex part h2a and concave part h2b of the back h2, as shown in FIG. 15. At this time, the mounting part h6a is placed in a state where it enters from above the convex part h2a. In this state, the convex part h2a of the back h2 fits into the concave part h1e of the back frame h1, and the concave part h2b of the back h2 fits into the convex part h1f of the back frame h1, and the back h2, the first upholstery engaging body h6, and the back frame h1 are engaged using the engagement pin KP. As a result, the upholstery h3 is clamped in a positioned state by the back frame h1 and the back portion h2, and the upper ends of the back frame h1, back portion h2, and upholstery h3 are integrated. The portion of the upholstery h3 other than the upper end portion is attached by inserting the second upholstery engagement body h7 into the engagement groove h2c formed along the outer peripheral edge of the side and bottom of the back side of the back portion h2. As described 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 Fig. 16, a lumbar support h4 is disposed behind (on the back side) the upholstery h3 stretched over the back h2. The lumbar support h4 is attached to the lower part of the back side of the back h2, bridging the width of the back h2. As shown in Fig. 17, the lumbar support h4 has a retaining portion h4a that abuts and holds the waist of the seated person, and a narrow insertion portion h4b formed at both ends in the width direction. A C-shaped recess h4c is formed in the insertion portion h4b. The lumbar support h4 is attached by inserting the insertion portion h4b into an insertion opening h2e formed in the back h2. A fitting 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 with each other, 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 of the lumbar support h4 and the protruding portion of the back h2 by inserting a flat head screwdriver or the like through the insertion opening h2e between the recessed portion h4c of the lumbar support h4 and the protruding portion of the back 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 h2 to which the lumbar support h4 is attached can change the position of the back h2 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 (first main body) 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 (second main body) h5g. The second bracket h1h includes a locking portion h5d. The main body h5a includes a cylindrical portion h5h and a first rotating shaft h5i. The operation lever h5b includes a gripping portion that stands upright in a direction perpendicular to the shaft body h5j, and is assembled to the main body h5a by inserting the shaft body h5j from the small diameter side of the cylindrical portion h5h. The shaft body h5j is rotatable inside the cylindrical portion h5h.

[0050] An insertion hole h5k is formed in the center of the stopper member h5c. In the present embodiment, the stopper member h5c has concave and convex portions formed at intervals of a predetermined angle (for example, 60 degrees) in the circumferential direction with the insertion hole h5k as the center point. The second bracket h1h on which the locking portion h5d is provided is erected on the lower left and right rear sides of the back frame h1 with the engagement surface facing outward in the left and right direction. An insertion hole h5l is formed in the center of the locking portion h5d. In addition, the locking portion h5d has an engagement surface of the same shape (corresponding shape) as the stopper member h5c, and is paired with the stopper member h5c, and can be engaged with each other by concave and convex. When the engagement surfaces of the stopper member h5c and the locking portion h5d are engaged with each other, the respective insertion holes h5k and the insertion holes h5l communicate with each other with their center points on the same straight line.

[0051] The coil spring h5e and the stopper member h5c are housed in the large diameter side of the cylindrical portion h5h of the main body h5a in the order described. The stopper member h5c is disposed in contact with the other end of the coil spring h5e. In this state, the stopper member h5c is fixed to the screw hole h5m of the operating lever h5b by screwing with the first screw h5f. In addition, the large diameter side opening of the cylindrical portion h5h of the main body h5a is formed with an engagement surface h5n with which the stopper member h5c engages, and the stopper member h5c engages with this engagement surface h5n. The stopper member h5c is in a state of protruding from the large diameter side opening of the cylindrical portion h5h.

[0052] The main body part h5a, in which the operation lever h5b, the coil spring h5e and the stopper member h5c are housed, is assembled in a state in which the exposed part of the stopper member h5c is engaged with the locking part h5d in a concave-convex manner. Then, the second rotation shaft h5o of the main body part (second main body part) h5g is inserted from the inside of the insertion hole h5l of the locking part h5d, and the second screw h5p is screwed into the female screw part h5q formed in the main body part h5a, so that the operation mechanism h5 is attached to the back frame h1. In the operation mechanism h5 thus attached, the stopper member h5c is always biased toward the locking part h5d by the biasing force of the built-in coil spring h5e, and unintended movement of the back part h2 (lumbar support h4) is restricted. As a result, to change the position of the back part h2 relative to the back frame h1, it is necessary to rotate the operation lever h5b of the operation mechanism h5.

[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, and the protrusion amount of the operating lever h5b in the axial direction of the cylindrical portion h5h increases. This compresses the coil spring h5e, reducing the biasing force that presses the stopper member h5c against the locking portion h5d, allowing the operating lever h5b to rotate and releasing the engagement between the stopper member h5c and the locking portion h5d.

[0054] In this manner, when the engagement force between the stopper member h5c and the locking portion h5d is reduced, the rotation of the operation lever h5b allows the stopper member h5c to rotate while sliding the engagement surface between the locking portion h5d and the stopper member h5c. This causes the back part h2 to rotate due to the action of the shaft body h5j formed in the main body part h5a and connected to the first bracket h2d of the back part h2. The operation mechanism h5 in this embodiment can provide three positions, but the number of positions that can be provided by the operation mechanism h5 can be changed as appropriate depending on the design of the engagement surface between the stopper member h5c and the locking portion h5d.

[0055] In addition, a standing wall h5t is erected in a required length range along the outer circumferential surface of the shaft body h5j at a required distance from the radial outside of the shaft body h5j of the main body part (second main body part) h5g. When the back part h2 is in a predetermined position by the operation mechanism h5, the first bracket h2d of the back part h2 is prevented from coming off by the standing wall h5t. When removing the back part h2 from the back frame h1 with the operation mechanism h5 attached, the connection by the pin at the upper end of the back part h2 and the back frame h1 is released, the upper end of the back part h2 is tilted forward, and the back part h2 is pulled out with the forward tilt angle of the back part h2 relative to the back frame h1 set to a predetermined angle. This releases the prevention of the first bracket h2d of the back part h2 from coming off by the standing wall h5t, and the back part h2 can 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 part x1 to the backrest H and a head contact part x2 that is rotatable around a horizontal axis extending in the left-right direction at the upper end of the attachment part x1.

[0057] As shown in Figures 20 and 21, the mounting part x1 is equipped with a clamp part x3 that clamps the upper end part 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 clamp section 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, and is integrated by screwing from the lower surface side of the front side with the backrest H clamped between the first member x3a and the second member x3b. A top housing section (not shown) is formed on the rear 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 section x4. The biasing spring x5b and the top x5a are housed in the top housing section in the order shown, and a part of the top x5a protrudes from the front end of the top housing section. On the rear surface (back face) side of the first member x3a, a guide rail clamping portion x3c is formed along the height direction to clamp in the width direction two rows of guide rails x4a erected along the height direction on the front side of the slider portion x4. The slider portion x4 is capable of sliding 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 piece x5a, a biasing spring x5b, a cam plate x5g, a stopper x5j to prevent disengagement, and a stopper x5k to prevent erroneous installation. The height adjustment mechanism x5 will be described in detail below.

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

[0061] The mountain-shaped portion x5d is disposed at both ends of the frame x5a in the width direction. The inclined surfaces of the mountain-shaped portion x5d are formed to have different inclinations. In this embodiment, the inclination angle of the upper inclined surface of the mountain-shaped portion x5d in the frame x5a mounted in the normal state is steeper than the inclination angle of the lower inclined surface, forming an asymmetric shape. In addition, a U-shaped rib portion x5e with an open upper side of the frame x5a is erected 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 frame x5a is a constant height, and is formed lower than the top height of the mountain-shaped portion x5d. In other words, the rib portion x5e is formed higher except for the top part of the mountain-shaped portion x5d. The inclined rib x5f is erected at the middle position 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 erected in parallel with a required interval in the left-right direction at the front side of the slider part x4 between the two rows of guide rails x4a along the height direction. The cam plate x5g has a plurality of mountain-shaped protrusions x5h erected at equal intervals, and a large protrusion x5i that is taller than the other protrusions x5h is arranged at the lower end of the cam plate x5g. In this embodiment, the inclination surface of the protrusion x5h is asymmetrically shaped such that the inclination angle of the lower inclination surface is larger than the inclination angle of the upper inclination surface, and the protrusions x5h are engaged with the mountain-shaped part x5d of the piece x5a. The inclination angle of the lower inclination surface of the large protrusion x5i is also larger than the inclination angle of the upper right inclination surface.

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

[0064] A method of mounting the piece x5a on the cam plate x5g will be described. When the piece x5a is in the normal state (the opening of the rib portion x5e faces upward), the mountain-shaped portion x5d is slid on the cam surface of the cam plate x5g, and the opening of the rib portion 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 stopper x5k for preventing erroneous mounting and the stopper x5j for preventing slipping out. As shown in Figs. 23 and 24, the convex portion x5h and the mountain-shaped portion x5d constituting the cam surface can be fitted together. Therefore, when the piece x5a is slid on the cam surface against the biasing force of the biasing spring x5b, the piece x5a fits into the convex and concave portions with a clicking sensation at the intervals of the convex portions x5h. 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 abutment portion x2) can be selected. When the top x5a is attached to the cam plate x5g in the normal state, the bottom surface x5l, which is the lowest part of the top x5a formed on a flat surface, abuts against the anti-slip stopper x5j, as shown in Figure 25, so that the top x5a does not come off from the slider portion x4.

[0065] In contrast, when the top x5a is in an incorrect state (the opening of the rib portion x5e faces downward) and the peak portion x5d is attempted to slide on the cam surface of the cam plate x5g, the bottom side wall surface x5m of the rib portion x5e comes into contact with the mis-installation prevention stopper x5k before the peak portion x5d rides on the cam surface of the cam plate x5g, restricting the movement of the top x5a, as shown in Fig. 26. This makes it impossible for the top x5a to enter the cam surface of the cam plate x5g, thereby preventing the clamp portion x3 from being erroneously installed on the slider portion x4.

[0066] As shown in Fig. 27 and Fig. 28, the head contact portion x2 has a frame body x6 and an upholstery x7. As shown in the two rear perspective views, the frame body x6 has an upholstery holding frame x6a that holds the upholstery x7 and a decorative frame x6b that is attached to the rear surface (rear surface) of the upholstery holding frame x6a. A connecting portion x6c with the slider portion x4 is disposed on the upholstery holding frame x6a. This connecting portion x6c can have a known configuration, and therefore will not be described here. A tongue piece x6d is provided around the outer periphery of the upholstery holding frame x6a on the rear surface. There is a gap between this tongue piece x6d and the upholstery holding frame x6a, and the outer periphery of the upholstery x7 (the third upholstery engagement body x7b and the fourth upholstery engagement body x7c) is accommodated and held in this gap (see Fig. 29).

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

[0068] In addition, through holes x7d are formed at regular intervals in the length direction in the width direction center of the fourth upholstery engagement body x7c, but the width direction inner end of the cutout portion x7e does not reach a predetermined width range based on the width direction center line. Therefore, a large plate portion (unprocessed portion) can be left in the width direction center of the fourth upholstery engagement body x7c. This allows a large seam allowance to be provided when sewing the fourth upholstery engagement body x7c to the upholstery main body x7a. In addition, the cutout portion x7e of the fourth upholstery engagement body x7c has a large cutout amount in the length direction at both width direction ends, making it easy to deform when subjected to external forces. In this way, the fourth upholstery engagement body x7c has a large seam allowance to reduce fraying of the upholstery main body x7a, while also being shaped to be easily deformed.

[0069] By adopting such a fourth upholstery engagement body x7c, the fourth upholstery engagement body x7c can be expanded and compressed in the length direction of the fourth upholstery engagement body x7c together with the upholstery main body x7a (Fig. 31(B), (C)). In addition, the fourth upholstery engagement body x7c can be bent in the same plane in the length direction (Fig. 31(D)). Due to these characteristics of the fourth upholstery engagement body x7c, the fourth upholstery engagement body x7c can easily deform even in a curved portion with a small curvature that the second upholstery engagement body h7 could not handle, so the fourth upholstery engagement body x7c can be made to follow the curved portion. By using such a fourth upholstery engagement body x7c, the upholstery main body x7a can be engaged with the fourth upholstery engagement body x7c in the gap between the upholstery holding frame x6a and the tongue piece x6d. This reliably prevents the upholstery main body x7a from protruding from the upholstery holding frame x6a even after long-term use.

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

[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 sliding tube y3, an armrest y4, an operating lever y5, and a height position holding portion y6.

[0072] The seat attachment part y1 has a seat fixing part y1a and a tubular part y1b, and is formed into an L-shape by the seat fixing part y1a and the tubular part y1b, which has an open top surface. A screw hole y1c is arranged in the seat fixing part y1a, which penetrates in the vertical direction, and is attached to the seat D by aligning the screw hole y1c with a screw hole (not shown) formed in the bottom surface of the seat D and fastening a screw y1d from the bottom surface of the screw hole y1c. The tubular part y1b has an open top surface, and houses the height adjustment tube y2 and the slide tube y3 in an assembled state, and the tubular part y1b and the height adjustment tube y2 are fixed by a known method.

[0073] The height-adjusting tube y2 in this embodiment is formed in a shape in which a portion of the required height range is cut out from the bottom of the front half. A plurality of through holes y2b are drilled at regular intervals in the height direction in the rear peripheral surface y2a of the height-adjusting tube y2. As is clear from FIG. 34, two through holes y2b are arranged at the same height position so as to sandwich a rib y2c extending in the height direction from the left and right directions. The rib y2c protrudes from the front side of the rear peripheral surface y2a. A slide tube y3 is inserted into the height-adjusting tube y2 so as to be removable.

[0074] The slide tube y3 has a tube portion y3a inserted into the height adjustment tube y2 and a shell-shaped elbow support portion y3b that supports the elbow pad y4. A front groove y3d extending in the height direction is formed on the front peripheral surface y3c of the tube portion y3a. A rear groove y3f extending in the height direction is formed on the rear peripheral surface y3e of the tube portion y3a. An opening y3g is formed in the lower part of the rear peripheral surface y3e so as to divide the rear groove y3f. The tube portion y3a of the slide tube y3 thus formed is inserted into the height adjustment tube y2 with the rib y2c fitted into the rear groove y3f.

[0075] The height position holding part y6 has a main body y6a, an engagement claw y6b, and a biasing spring y6c. An engagement piece y6d that engages with a front groove y3d formed in the slide tube y3 is formed on the front surface of the main body y6a. The biasing spring y6c and the engagement claw y6b are arranged on the rear surface of the main body y6a in the order described above. That is, the engagement claw y6b is biased in a direction protruding from the rear surface of the main body y6a by the biasing force of the biasing spring y6c arranged between the main body y6a and the engagement piece y6d. The height position holding part y6 thus formed is accommodated from the lower opening of the slide tube y3. The height position holding part y6 is positioned and fixed to the slide tube y3 with the engagement piece y6d engaged with the front groove y3d and the engagement claw y6b exposed from the opening y3g of the slide tube y3. Therefore, when the slide tube y3 is inserted into the height adjustment tube y2 as described above, the engagement claws y6b engage with the two through holes y2b at the same height position, and the slide tube y3 is fixed to the height adjustment tube y2 with the rib y2c inserted into the rear groove y3f.

[0076] The height position holding portion y6 attached to the slide tube y3 and engaged with the height adjustment tube y2 is connected to the operation lever y5 by a wire y7. More specifically, the operation lever y5 is connected to the engagement claw y6b by the wire y7. That is, when the operation lever y5 is rotated by the seat occupant, the engagement claw y6b is slid by the wire y7 in the opposite direction to the direction in which it is biased by the biasing spring y6c. When the seat occupant rotates the operation lever y5, the engagement between the engagement claw y6b and the through hole y2b of the height adjustment tube y2 is released. The seat occupant can lift up a part of the slide tube y3 from the height adjustment tube y2 by lifting the elbow support portion y3b while rotating the operation lever y5.

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

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

[0079] In addition, a resistance imparting body y4k is arranged in a part of the circumferential length range of the inner circumferential surface of the opening y4f of the first holding body y4b, protruding inward of the other guide groove y4j to narrow a predetermined portion of the other guide groove y4j. The resistance imparting body y4k is formed on the first holding body y4b as a spring body having elasticity and a π shape in a plan view, but is not limited to this form and may be formed of, for example, an elastic material. The resistance imparting body y4k can also be formed on the first path body y4a instead of the first holding body y4b. The width dimension of the other guide groove y4j in the range where the resistance imparting body y4k is arranged is narrower than the width dimension of the other guide groove y4j in the range where the resistance imparting body y4k is not arranged. When the movable shaft N1 enters the range in which the resistance imparting body y4k is disposed of the other guide groove y4j, the outer circumferential surface of the movable shaft N1 passes through the range in which the resistance imparting body y4k is disposed while elastically deforming the resistance imparting body y4k, so that the resistance during movement is greater in this range than in other ranges. In this embodiment, the first path body y4a is formed separately from the first holding body y4b and is integrally engaged with the first holding body y4b by an engagement piece y4l formed on the first holding body y4b, but the first path body y4a and the first holding body y4b can also be formed integrally.

[0080] The second path body y4c has one guide groove y4m formed in an S-shape on the rear side, a nut holding portion y4n that holds the nut N1a screwed with the movable shaft N1 that enters the one guide groove y4m and moves within the one guide groove y4m, an opening hole y4o for mounting the operating lever y5, and a mounting portion y4p. One guide groove y4m is formed in an S-shape in a plan view, and is configured so that the initial direction from the rear to the front is approximately the same as one of the directions of the ring shape in the other guide groove y4j. This allows the elbow rest main body y22, which is composed of the second path body y4c, the second holding body y4d, and the elbow rest pad y4e, to move along an S-shaped track that is movable in both the front-rear and left-right directions. In addition, the fixed shaft N2 that enters the one guide groove y4m is formed to be wider than the width dimension of the one guide groove y4m, and an O-ring N2b is disposed between the washer N2a placed on the upper surface of the one guide groove y4m. When the shaft portion N2c of the fixed shaft N2 moves in one guide groove y4m, the elastic deformation of the O-ring N2b prevents rattling in the vertical direction between the shaft portion N2c and the second path body y4c.

[0081] The nut N1a, which is screwed with a male screw portion formed on the small diameter portion of the movable shaft N1, is accommodated in the nut holding portion y4n in a fixed state. An O-ring N1c is disposed between the nut N1a and the washer N1b, and a sliding resistance is applied by the elastic deformation of the O-ring N1c that occurs when the movable shaft N1 rotates around the other guide groove y4j.

[0082] The opening hole y4o is formed on the front peripheral surface of the second path body y4c. The grip portion y5a of the operation lever y5 is inserted into the opening hole y4o. The mounting portion y4p is formed in a plate-like body having an opening that rotatably engages with the rotation shaft y5b arranged on the operation lever y5, and is erected on the upper surface of the second path body y4c in alignment with both ends of the rotation shaft y5b in the longitudinal direction. The opening hole y4o is formed to a height dimension necessary to allow the operation lever y5 to rotate within a predetermined angle range in the vertical direction. A thick portion y5c is formed at the base of the grip portion y5a of the operation lever y5 to close the gap between the opening hole y4o and the grip portion y5a, preventing foreign matter from entering through the gap between the operation lever y5 and the opening hole y4o.

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

[0084] The operating lever y5 is rotatably attached to the second path body y4c as described above. A wire engaging portion y5d is provided on the rotation shaft y5b of the operating lever y5, and a first end of the wire y7 is connected to the wire engaging portion y5d. The wire y7 is pulled into the inside of the slide tube y3 from one guide groove y4m of the second path body y4c, and a second end of the wire y7 is connected to the engaging claw y6b of the height position holding portion y6. By adopting a form in which the rotational movement of the operating lever y5 is transmitted to the height position holding portion y6 by the wire y7 in this way, the operating lever y5 can be disposed on the elbow pad y4e (second path body y4c) that can move back and forth and left and right. In addition, by using one guide groove y4m to route the wire y7 in the elbow pad y4, it is also possible to reduce bending of the wire y7, and the operating lever y5 can be operated smoothly regardless of the position of the elbow pad y4e.

[0085] As shown in FIG. 35 and FIG. 36, when the elbow rest body y22 moves from the rear to the front, the elbow rest body y22 first moves along the S-shape of one guide groove y4m located on the rear side. On the other hand, the movable shaft N1 moving along the other guide groove y4j together with the elbow rest body y22 reaches the place where the resistance imparting body y4k is arranged in the other guide groove y4j (the end face on the front side) and feels resistance. When the elbow rest body y22 moves from the front to the rear, it can move through either side of the ring-shaped other guide groove y4j provided on the front side. By making the other guide groove y4j ring-shaped in this way, the seated person can experience various movement paths of the elbow rest body y22. Also, at this time, the movable shaft N1 moving along the other guide groove y4j together with the elbow rest body y22 moves from the place where the resistance imparting body y4k is arranged in the other guide groove y4j to the place where the resistance imparting body y4k is not arranged, so a sense of resistance is felt at the beginning of the movement, and then the sense of resistance disappears and the movement can be performed.

[0086] The range in which the resistance imparting body y4k is arranged in the other guide groove y4j has a narrower path width than the other parts, and when the movable shaft N1 passes through this range, the resistance imparting body y4k is pushed and spread by the outer periphery of the movable shaft N1 as it passes through. In this way, by elastically deforming the resistance imparting body y4k, a sense of resistance to the movement of the movable shaft N1 can be imparted, which can create a sense of luxury for the chair A and also allows the seated person to easily recognize the current position of the armrest y4 and the direction in which it will move from now on. In this embodiment, since the sliding resistance is imparted by the elastic deformation of the O-ring N1c that occurs when the movable shaft N1 moves around the other guide groove y4j, it is sufficient to provide resistance when the movable shaft N1 moves by providing either the O-ring N1c or the resistance imparting body y4k.

[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, such that the front end of the elbow rest main body y22 first faces outward and gradually faces 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, thereby providing a variety of movement patterns that are different from the simple reciprocating movement trajectory of the elbow rest main body y22 in the prior art.

[0088] Next, the detailed configuration of the operation mechanism h5 and the detailed operation of the operation mechanism h5 will be described. Here, Fig. 38 is an explanatory diagram for explaining the operation of the backrest H, Fig. 38(A) is a left side view, and Fig. 38(B) is a right side view. Note that the operation mechanism h5 will be described taking as an example a case where the position of the back h2 of the backrest H is changed, but is not limited to this, and can be applied as an operation mechanism for performing an operation 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 part h2, which are connected to each other by an upper connecting part hu and a lower connecting part (described later). In addition, the back part h2 can be moved in the front-rear direction relative to the back frame h1 by operating the operating mechanism h5 (specifically, the back part h2 can be moved toward and away from the back frame h1 by swinging with the upper connecting part hu as a fulcrum) (the movable range is appropriately set). This allows the back part h2 to be moved according to each of the sitting postures, the backward leaning posture and the forward leaning posture, so that the support position of the spine (particularly the pelvis) can be suitably adjusted. As an example, the solid lines in FIG. 38(A) and FIG. 38(B) show a state in which the back part h2 has moved to the rear end position relative to the back frame h1, and the broken lines show a state in which the back part h2 has moved to the front end position relative to the back frame h1. As described above, the upper connecting part hu has a simple and easily attachable and detachable structure using a concave-convex fitting.

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

[0091] As described above, the conventional chair described in Patent Document 1 also had a structure in which the back was movable forward and backward. However, because the structure was such that if the back itself was held and pushed forward and backward, the link rotated and the back moved forward and backward, there was a risk that the back would move unexpectedly.

[0092] Chair A having an operating mechanism according to this embodiment is particularly equipped with the following configuration, thereby making it possible to solve the above 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). Also, 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, the operating mechanisms h5 are provided in pairs on the left and right positions of the chair A (specifically, the back frame h1). Meanwhile, as another example of the lower connecting portion, a configuration in which the back h2 and the back frame h1 are connected without the intermediation 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 the 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 each figure, the operation mechanism h5 (h5A) at the left position of the chair A will be described as an example. Note that the operation mechanism h5 (h5B) at the right position of the 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 rotatably connected to the first bracket h2d, and a second rotation part h32 rotatably connected to the second bracket h1h.

[0096] In this embodiment, the first rotating shaft h5i is provided on the first rotating part h31 of the operation mechanism h5, and the first bearing h5v is provided on the first bracket h2d, and the first rotating shaft h5i is rotatably supported by the first bearing h5v. As a result, the operation mechanism h5 is rotatably connected to the first bracket h2d. In this embodiment, a sliding bearing structure is adopted for the first bearing h5v (other configurations may be used). In addition, the first rotating 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 rotating shaft h5i may be provided on the first bracket h2d, the first bearing h5v is provided on the first rotating part h31 of the operation mechanism h5, and the first rotating shaft h5i and the first bearing h5v may be configured to be engaged and disengaged (not shown).

[0097] Further, a second rotating shaft h5o is provided on the second rotating part 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 rotating shaft h5o is rotatably supported by the second bearing h5l. As a result, the operation mechanism h5 is rotatably connected to the second bracket h1h. In this embodiment, a sliding bearing structure is adopted for the second bearing h5l (other configurations may also be used). As a modified example, the second rotating shaft h5o may be provided on the second bracket h1h, and the second bearing h5l may be provided on the second rotating part h32 of the operation mechanism h5 (not shown).

[0098] As shown in Fig. 39 and Fig. 40(A) to Fig. 40(C), the operation mechanism h5 includes a main body part h5a, an operation lever h5b attached to the main body part h5a so as to be rotatable in one direction (arrow FD direction) and the opposite direction (arrow RD direction), and a stopper member h5c that advances and advances from the main body part h5a in conjunction with the rotation of the operation lever h5b and is engaged and disengaged with a locking part h5d provided on the second bracket h1h. Here, in the main body part h5a, the above-mentioned first rotation shaft h5i and second rotation shaft h5o are arranged in parallel to each other (i.e., their respective central axes are arranged in parallel). In this embodiment, the first rotation part h31 and the second rotation part h32 are arranged so that the first rotation part h31 moves from the rear to the front when the operation lever h5b is rotated from the rear to the front. Specifically, the first pivot part h31 connected to the back h2 (first bracket h2d) is positioned at a relatively higher position, and the second pivot part h32 connected to the back frame h1 (second bracket h1h) is positioned at a relatively lower position.

[0099] In addition, the operation mechanism h5 has an operation lever h5b attached to a main body h5a (first cylindrical part h5ha) so as to be rotatable coaxially with the second rotation axis h5o of the second rotation part h32. At this time, 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 part h32 and immovable around the axis of the second rotation axis h5o. As an example, the outer peripheral shape of the stopper member h5c in front view (i.e., the shape when viewed in a direction parallel to the central axis of the second rotation axis h5o, which is the moving direction) is formed into a star shape (including an approximately star shape) or a gear shape (including an approximately gear angle shape) having uneven parts on the outer peripheral surface. However, the shape is not limited to this, and may be formed into an elliptical shape, an oval shape, or a polygonal shape (including an approximately polygonal shape). On the other hand, the inner circumferential 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 in a corresponding engagement shape (i.e., a shape that allows parallel movement 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 circumferential surface (entry position of the stopper member h5c) is formed in a corresponding engagement shape (i.e., a shape that allows parallel movement but does not allow movement around the axis). However, regarding the engagement structure between the stopper member h5c and the locking portion h5d, the rotational force transmitted from the operation lever h5b to the stopper member h5c generates slippage with respect to the locking portion h5d according to the amount of advancement (pulling in) of the stopper member h5c into the main body portion h5a, and the stopper member h5c is made movable around the axis while advancing into the main body portion h5a against the biasing force, so that the convex portion of the stopper member h5c is formed into a tapered surface (including a curved surface) that is tapered toward the tip and in the circumferential direction. In addition, by providing this structure, an effect is created in which the user can get a clicking sensation when moving the back portion h2 by operating the operation lever h5b. Note that the switching position of the operation mechanism h5 can be set to any multiple stages by setting the number of concave and convex portions provided on the outer circumferential surface of the stopper member h5c (as an example, in this embodiment, the setting is three stages of the front stage, the middle stage, and the rear stage, 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 when 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 (for example, 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), and is formed into a surface shape that causes the operation lever h5b to move in a direction away from the main body portion h5a when the operation lever h5b is rotated in either direction from the neutral position. The biasing member h5e is arranged in the second cylindrical portion h5hb of the main body portion h5a in a state where it is sandwiched between the stopper member h5c fixed to the operation lever h5b and the partition portion h5hc of the main body portion h5a and generates a biasing force (elastic force). According to this, when the operation lever h5b is rotated from the neutral position (FD direction, RD direction), the tapered surfaces h5r and h5s slide against each other, and the operation lever h5b moves in a direction advancing (moving away) from the main body portion h5a, and the stopper member h5c moves in a direction advancing (pulling in) into the main body portion h5a. At this time, the biasing member h5e is compressed by the stopper member h5c and the partition portion h5hc, generating a biasing force (elastic force) that tries to return. 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 biasing force, and the operating lever h5b moves in the direction of entering the main body portion h5a, and the stopper member h5c moves in the direction of exiting from the main body portion h5a, and the operating lever h5b returns to the neutral position.

[0101] The operation mechanism h5 is provided with a rotation force transmission part h28 that transmits the rotation force of the operation lever h5b to the main body part h5a when the operation lever h5b is rotated to a predetermined position or more in either direction (FD direction, RD direction) relative to the main body part h5a. As an example, the rotation force transmission part h28 is configured with 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 it is rotated from the neutral position to a position less than the predetermined position, and that can come into contact with each other when the operation lever h5b is rotated to the predetermined position or more. The protrusion h28a is provided on the inner peripheral surface of the main body part h5a (first cylindrical part 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 part h5a may be adopted). 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 abut against each other, and the force rotating the operating lever h5b is transmitted to the main body portion h5a, so that the main body portion h5a rotates (together with the operating lever h5b).

[0102] The movement of the back h2 in the chair A having the above configuration will be described. Note that, although the explanation will be given taking the operation mechanism h5A as an example, the chair A according to this embodiment is provided with a pair of operation mechanisms h5 (h5A, h5B) at the left and right positions, so that the same operation is also performed simultaneously on the operation 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 arrow FD, and Figures 41(A), 41(C), and 41(E) are views from the front (viewed from a direction parallel to the first rotation axis h5i and the second rotation axis h5o), while Figures 41(B), 41(D), and 41(F) are views from the side (viewed from a direction perpendicular to the first rotation axis h5i and the second rotation axis h5o).

[0104] First, as shown in Fig. 41(A) and Fig. 41(B), when the operating lever h5b is in the neutral position (when the operating lever h5b is not operated), the stopper member h5c is biased in a direction advancing from the main body part h5a (in a direction to abut against the locking part h5d provided around the second bearing h5l of the second bracket h1h) by the biasing force (resilient force) of the biasing member h5e of the neutral position return part h24. As a result, the stopper member h5c is locked by the locking part h5d, and the rotation of the main body part h5a is restricted. In this state, even if the back part h2 itself is held and pushed back and forth, the operating mechanism h5 will not rotate due to the pushing force, and the back part h2 will not move back and 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 part h5a slide against each other, while the operating lever h5b moves in a direction advancing (moving away) from the main body part h5a (direction of arrow OD) and the stopper member h5c moves in a direction advancing (pulling in) into the main body part 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 part h5a is restricted is maintained.

[0106] Next, as shown in Fig. 41(E) and Fig. 41(F), when the operating lever h5b is rotated from the neutral position to a predetermined position or more (i.e., the amount of rotation is a predetermined angle or more), the protrusion h28a of the main body part h5a (first cylindrical part h5ha) and the groove h28b of the operating lever h5b come into contact with each other, and the force to rotate the operating lever h5b is transmitted to the main body part h5a. At this time, the sliding contact between the tapered surfaces h5r and h5s stops, and the operation lever h5b stops moving forward from the main body part h5a. Meanwhile, the stopper member h5c fixed to the operating lever h5b is rotated, causing slippage with respect to the locking part h5d, and the stopper member h5c moves around the axis while advancing a small amount further into the main body part h5a against the biasing force. That is, the stopper member h5c and the locking portion h5d are released from the engagement state, so that the main body portion h5a can rotate (rotate together with the operation lever h5b). Therefore, the main body portion h5a rotates in conjunction with the rotation of the operation lever h5b, and the first rotation portion h31 moves in an arc (in the direction of the arrow TD). If the operation of the operation lever h5b (the operation of rotating it in the direction of the arrow FD) is stopped from this state, the operation lever h5b rotates in the opposite direction (direction of the RD) and moves in a direction entering the main body portion h5a due to the action of the neutral position return portion h24 described above, and the stopper member h5c moves in a direction exiting from the main body portion h5a, and the operation lever h5b returns to the neutral position.

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

[0108] On the other hand, Fig. 42(A) to Fig. 42(F) show the case where the operating lever h5b of the operating mechanism h5A is rotated in the direction of the arrow RD, Fig. 42(A), Fig. 42(C), and Fig. 42(E) are views from the front (viewed from a direction parallel to the first rotating shaft h5i and the second rotating shaft h5o), and Fig. 42(B), Fig. 42(D), and Fig. 42(F) are views from the side (viewed from a direction perpendicular to the first rotating shaft h5i and the second rotating shaft h5o). Note that in the case of Fig. 42(A) to Fig. 42(F), the operation is the same as that in Fig. 41(A) to Fig. 41(F) except that the rotating direction of the operating lever h5b and the main body part h5a is reversed (repeated explanation will be omitted).

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

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

[0111] As 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 the operating mechanism h5, i.e., the first pivot shaft h5i is directly fixed 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 shaft h5i and the second rotation shaft 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 operation 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 formed with a cross-sectional shape of a letter C (or a letter U) by an integral structure (or a separate structure) with the back part h2 using an elastic resin material, and 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 part 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 part h30. The first rotating shaft h5i is formed with a cross-sectional shape of a hollow cylinder (or may be a solid column). In this embodiment, the first bearing h5v and the first rotating shaft h5i are configured to be engaged and disengaged by a snap-fit ​​structure in which the first bearing h5v is elastically deformed. This allows for a configuration in which the back portion h2 can be attached and detached from the back frame h1 extremely simply and in a short time, and in which no rattling 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 includes a disengagement prevention unit h60 that prevents the first bearing h5v and the first rotating shaft h5i from engaging or disengaging (referring to a state in which the engagement is released and one is disengaged from the other) when the back h2 is connected to the back frame h1 and the operating mechanism h5 (i.e., the engaged first bearing h5v and the first rotating shaft h5i) are positioned at least at the front end of the movable range. Fig. 44 shows an example of the configuration of the disengagement prevention unit h60, with Fig. 44(A) showing the operating mechanism h5 at the front end position within the movable range and Fig. 44(B) showing the operating mechanism h5 at the rear end position within the movable range.

[0116] As shown in FIG. 44(A), the separation prevention part h60 is configured to prevent the first bearing h5v from being disengaged from the first rotating shaft h5i by a predetermined angle θ degrees when the angle between the opening direction of the first opening h13 and the opening direction of the second opening h23 deviates from 180 degrees, which is the same line, by a predetermined angle θ degrees. With this arrangement, even if the back part h2 is pulled in the direction of the arrow DD relative to the operating mechanism h5, the first bracket h2d (predetermined part) abuts against the operating mechanism h5 (abutment member), so that the engagement between the first bearing h5v and the first rotating shaft h5i is not released. As an example, θ is set to 20 degrees, but is not limited thereto. The angle θ may be set so that the separation prevention by the separation prevention part h60 acts from a position before the operating mechanism h5 reaches the front end position within the movable range.

[0117] As an example, the abutment member provided on the operation mechanism h5 is composed of two walls (first wall h5ta, second wall h5tb) spaced apart and arranged to sandwich the first rotating shaft h5i in the axial direction. 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 by a simple configuration using a configuration for engaging and disengaging the first bearing h5v and the first rotating shaft h5i. However, this configuration is not limited to this. Note that, when the other example described above (lower connecting portion without the lower operation 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 from the back frame h1 very simply 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] In this embodiment, as shown in Fig. 44(B), the configuration is such that the same action as above can be obtained even when the operating mechanism h5 (i.e., the engaged first bearing h5v and the first rotating shaft h5i) are positioned at the rear end within the 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 the movable range.

[0120] On the other hand, when attaching or detaching the back part h2 to or from the back frame h1, the detachment restriction by the detachment restriction part h60 should not be applied. Specifically, as shown in FIG. 45, the connection between the back part h2 and the back frame h1 at the upper connecting part hu is released, and the back part 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 on the same straight line, or a position where the angle θ with respect to 180 degrees is an angle that does not cause detachment restriction (0 degrees < θ < 20 degrees in the above example). When the back part h2 is moved (rotated) to the predetermined position, the first bearing h5v and the first rotation shaft h5i can be engaged and disengaged, so that the back part h2 can be attached or detached from the back frame h1. In contrast, when the back portion h2 is not moved (rotated) to the above-mentioned specified position, the first bearing h5v and the first rotating shaft h5i cannot be engaged or disengaged, and therefore the back portion 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. Therefore, it is possible to prevent the component from moving unexpectedly when the operating lever is not being operated.

[0122] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. In particular, the operating mechanism has been described by taking the back of the backrest as an example of a target component of a chair, but is not limited thereto, and can be applied as an operating mechanism for other components (seat, legs, headrest, armrests, etc.).

[0123] In addition, 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 part 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, the present invention can also be applied to a configuration in which an operating mechanism is not interposed, i.e., a configuration in which the back part is directly connected to the back frame. [Explanation of symbols]

[0124] A: Chair B: Legs b1: Caster, b2: Leg wing, b3: Leg support C: Support base c1: mounting hole, c2: reaction spring, c3: reaction spring support, c4: link plate, c5: long hole, c6: Locking force adjustment lever, c7: Locking operation lever D: za d1: seat support, d2: seat body, d3: cushion, d4: recess, d5: protrusion, d6: shaft receiving hole, d7: opening, d8: spring holder, d9: spring, d10: pressure plate, d11: synchronous shaft mounting part, d12: opening hole, d13: Stopper body F: Backrest structure G: Back support g1: arm, g2: connecting plate, g3: shaft hole, g4: nut H: Backrest h1: back frame, h2: back, h3: upholstery, h4: lumbar support, h5: operating mechanism, h6: first upholstery engagement body, h7: second upholstery engagement body J1: Rotating shaft, J2: Synchro shaft, J3 Locking shaft, J4: Shaft body T: Tag X: Headrest x1: Mounting part, x2: Head contact part, x3: Clamp part, x4: Slider part, x5: Height adjustment mechanism, x6: Frame, x7: Upholstery Y: Armrest y1: Seat mounting part, y2: Height adjustment tube, y3: Slide tube, y4: Armrest, y5: Operating lever, y6: Height position holding part, y7: Wire, y21: Elbow support part, y22: Elbow rest body 10: Seat-synchronized shaft connection structure (rotating body connection structure)

Claims

1. An operating mechanism for changing the position of components of a chair, The chair has a main body, an operating lever attached to the main body so as to be rotatable 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 is engaged and disengaged with a locking portion provided on a support portion disposed on the chair. An operating mechanism characterized by:

2. When the operating lever is in a neutral position or when the operating lever is rotated from the neutral position to a position less than a predetermined position, the stopper member is engaged with the engaging portion, When the operating lever is rotated from a neutral position to a predetermined position or more, the main body is rotated in accordance with the rotation of the operating lever.

2. The operating mechanism according to claim 1,

3. The stopper member is attached to the main body so as to be movable parallel to the rotation axis of the operating lever and so as to be immovable around the axis of the rotation axis.

2. The operating mechanism according to claim 1,

4. The operating lever has a neutral position return portion 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 portion.

2. The operating mechanism according to claim 1,

5. An operating mechanism according to any one of claims 1 to 4; A backrest having a back frame and a back portion connected to the back frame, 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 is configured to perform an operation to change the position of the back portion relative to the back frame by rotating the operating lever. A chair characterized by:

6. The operation mechanism includes a first rotation part that is rotatably connected to the first bracket, and a second rotation part that is provided on the main body part with a rotation axis parallel to a rotation axis of the first rotation part and is rotatably connected to the second bracket.

6. The chair according to claim 5,

7. The operation mechanisms are provided in pairs at left and right positions on the back frame.

6. The chair according to claim 5,

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