JP6617525B2 - Chair - Google Patents

Description

  The present invention relates to a chair suitably used in an office or the like.

  Conventionally, a chair in which a lumbar support is arranged on the backrest is known (see, for example, Patent Document 1).

  By the way, recently, as a backrest structure, a structure including a front frame in which a tension member is stretched and a back frame disposed behind the front frame has been studied.

  However, this type of chair is provided with a lumbar support on the back frame located on the rear side of the front frame, and depending on the position of the front frame, the operational effects of the lumbar support can be suitably obtained. There is a bug that you can not.

JP 2013-094287 A

  The present invention has been made paying attention to the above situation, and it is an object of the present invention to provide a chair having a backrest provided with a lumbar support that favorably supports a seated person.

  That is, the present invention has the following configuration.

The invention according to claim 1 is a chair comprising a backrest on the front side of the back frame, in which a back frame in which a tension member is stretched is disposed so that the position of the back frame can be changed in the front-rear direction. The lumbar support is attached , and the front frame includes left and right side frame portions, an upper frame portion provided between upper ends of the left and right side frame portions, and the left and right side frame portions. A frame body having a lower connecting frame portion provided between the lower ends;
The side frame portion is provided with left and right lower frame portions formed so as to be gradually displaced inward toward the lower side, and the lumbar support has its both ends at the left and right lower frames. It is a chair that is attached to the part .

According to a second aspect of the present invention, the lumbar support includes a lumbar support main body that receives a load of a seated person, and attachment portions that are provided at both ends of the lumbar support main body and are attached to the lower frame portion. The chair according to claim 1.

The invention according to claim 3 is the chair according to claim 1 or 2, wherein an upper end portion and a lower end portion of the front frame are respectively connected to the back frame.

The invention according to claim 4 is the chair according to claim 1, 2, or 3, wherein the front frame has a structure that is more easily deformed than the back frame.

According to a fifth aspect of the present invention, the front frame has a generally U-shape when viewed from the side, and includes a projecting portion that projects most forward in the middle in the vertical direction. The chair according to 3 or 4.

According to a sixth aspect of the present invention, the front frame includes an upper frame portion tilted rearward in a side view and a lower frame portion tilted forward in a side view through a protruding portion protruding forward. A side frame portion is provided, the lumbar support is supported by the lower frame portion, and a part of the lumbar support is disposed at a height position corresponding to the upper frame portion. The chair according to 2, 3, 4 or 5.

  As described above, according to the present invention, a chair having a backrest provided with a lumbar support that favorably supports a seated person can be provided.

The perspective view which shows one Embodiment of this invention. The front view in the embodiment. The rear view in the embodiment. The right view in the same embodiment. The left view in the embodiment. The top view in the embodiment. The bottom view in the embodiment. The partial expansion left view in the same embodiment. The partial enlarged left view explaining the positioning mechanism of the embodiment. The partial enlarged left view explaining the positioning mechanism of the embodiment. The exploded perspective view in the embodiment. The exploded perspective view in the embodiment. The exploded perspective view in the embodiment. The exploded perspective view in the embodiment. The front view in the embodiment. The exploded perspective view in the embodiment. The partial expanded rear view of the front frame in the embodiment. XX sectional drawing in FIG. The exploded perspective view in the embodiment. The exploded perspective view in the embodiment. FIG. 5 is a cross-sectional view taken along line U-U in FIG. The exploded perspective view in the embodiment. The front view which shows the lumbar support of the embodiment. The rear view which shows the lumbar support of the embodiment. The right view which shows the lumbar support of the embodiment. The YY sectional view taken on the line in FIG. ZZ sectional drawing in FIG. The perspective view in the embodiment. The perspective view in the embodiment. The exploded perspective view in the embodiment. The top view in the embodiment. The top view in the embodiment. The top view in the embodiment. VV sectional view taken on the line in the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the present invention is applied to an office swivel chair A suitably used in an office or the like.

  The chair A is supported by a leg B, a support base C that is pivotally supported by the leg B, a seat D disposed on the support base C, and a support base C that can be tilted backward. The backrest structure F and the armrest P attached to the seat D are provided. The backrest structure F is constituted by a back support G that is rotatably supported by the support base C, and a backrest H that is supported by the support base C so as to be able to tilt backward through the back support G. Has been.

  Hereinafter, each structure of this chair A is explained in full detail.

<< Leg B >>
The leg B includes a plurality of leg blades b1 having a caster b3 at the tip and arranged radially, and leg struts b2 erected at the base end portion of the leg blades b1. The leg support b2 has a gas spring (not shown) that can be expanded and contracted in the vertical direction, and supports the support base C so that the position of the support base C can be changed vertically.

<< support base C >>
The support base C is mainly composed of a main frame c1 having a frame shape in plan view. The main frame c1 includes a left and right side block portion c2, a front block portion c3 that connects the front ends of the left and right side block portions c2, and a rear block portion c4 that connects the rear ends of the left and right side block portions c3. It has.

  The side block part c2 is provided with a main shaft j1 extending in the left-right direction. The back support G is rotatably supported with respect to the support base C via the main shaft j1.

  The front block portion c3 is provided with a bearing portion c5 of the front link shaft j2 arranged in a pair on the left and right. The bearing portion c5 of the front link shaft j2 protrudes upward.

  The rear block portion c4 includes a cylindrical portion c6 fixed to the leg support b2 and a rear wall c7 disposed at the rear portion of the cylindrical portion c6. The rear wall c7 constitutes a receiving member N of a backward tilt lock mechanism I, which will be described later. The rear wall c7, which is the receiving member N, has a plurality of recessed engaging portions c8 that are opened rearward. Are provided at intervals in the vertical direction.

<< Seat D >>
The seat D includes a seat receiver d1 having a shell shape and a seat body d2 provided on the seat receiver d1 so that the front-rear position can be changed. The front portion of the seat D is a support base portion via a front link c9. The rear part of the back support G is supported by the support base C via the rear link g4. The seat d1 has a front bearing portion d3 for holding a front connection shaft j3 extending in the left-right direction supported by an upper end portion of the front link c9, and a left-right direction penetrating the rear link g4. A rear bearing portion d4 for holding the extended rear connecting shaft j4 is provided. An armrest P is attached to the seat d1.

  The seat D is configured to move in synchronization with the backward tilting motion of the backrest H by the locking mechanism J. The seat d1 is provided with an operation lever d5 for backward tilt lock for operating the rearward tilt lock mechanism I and an operation lever d6 for lifting and lowering for operating the gas spring of the leg B.

<< Back support G >>
The back support G includes left and right arms g1 that are rotatably supported by the main shaft j1 via a bush g3, and a mounting plate g2 that rigidly connects the rear ends of these arms g1. The back support G is made of metal, and the arm g1 and the mounting plate g2 are joined by welding.

  The left and right arms g1 are paired and extend in the front-rear direction, and are provided with a shaft hole a1 at an intermediate portion in the front-rear direction. The left and right arms g1 are rotatably supported on the main shaft j1 through bushes g3 attached to the shaft holes a1.

  The bush g3 is formed of a synthetic resin and has a cylindrical shape having a flange portion g5 on the outer periphery of the inner end, and is attached to the shaft hole a1 provided in the arm g1 from the inside. In the mounted state, the flange portion g5 of the bush g3 is in contact with the inner side surface of the arm g1. In addition, a positioning projection g6 is provided on the outer surface of the flange portion g5, and the positioning projection g6 is fitted in a positioning hole a2 provided in the arm g1.

  A rear link g4 extending obliquely forward and upward is integrally formed in the vicinity of the shaft hole a1 at the upper edge portion of the left and right arms g1. A shaft hole g41 is formed in the upper end portion of the rear link g4, and a rear connection shaft j4 extending in the left-right direction is penetrated. Both end portions of the rear connecting shaft j4 are engaged with the rear bearing portion d4 of the seat receiver d1. A receiving shaft j5 is installed between the front end portions of the left and right arms g1, and the backrest H is rotated forward via a back support G between the receiving shaft j5 and the front end portion of the support base C. A reaction force mechanism E for moving and energizing is provided. Here, the symbol E is a coil spring constituting the reaction force mechanism E.

  The mounting plate g2 is provided with a plurality of bolt insertion holes h1 through which the plurality of bolts v1 are inserted. A nut portion (not shown) is disposed on the lower surface side of each bolt insertion hole h1. Further, a wire insertion for inserting an operation force transmission wire w provided between a backward tilt lock operation lever d5 provided on the seat D and a later-described reverse tilt lock mechanism I is inserted into the mounting plate g2. A hole e1 is formed.

<< Backrest H >>
The backrest H is provided on the back frame 1, a concealing member 2 provided at the front end of the back frame 1, a front frame 3 disposed on the front side of the back frame 1, and stretched on the front frame 3. The tension member 4, the lumbar support 5 positioned on the back side of the tension member 4 and attached to the front frame 3, and the lumbar support 5 and the front frame 3 that supports the tension member 4 are connected to the back frame 1. And a positioning mechanism 6 for positioning so that the position can be changed in the front-rear direction.

  The backrest H is formed by disposing a front frame 3 with a tension member 4 on the front side of the back frame 1 so that the position of the front frame 3 can be changed in the front-rear direction. With such a backrest H configuration, the front frame 3 is easy to make a structure that is easily elastically deformed as a whole, and the front frame 3 is given flexibility to wrap the back of the seated person. It is easy. The entire backrest H can be tilted backward about a main axis j1 provided on the support base C. Specifically, the backrest H is supported through a back support G so as to be rotatable around the main axis j1 of the support base C.

<Back frame 1>
The back frame 1 performs a backward tilting operation about a main shaft j1 provided on the support base C, and is installed between the left and right side frame portions 1a and upper ends of the left and right side frame portions 1a. The frame portion 1b, the left and right lower frame portions 1c extending forward from the lower ends of the left and right side frame portions 1a, and the left and right lower frame portions 1c are coupled to each other and fixed to the attachment plate g2 of the back support G. And a lower connecting portion 1d. The left and right side frame portions 1a, the upper frame portion 1b, the left and right lower frame portions 1d, and the lower connecting portion 1d are integrally formed of synthetic resin.

  The left and right side frame portions 1a in the back frame 1 are in the form of members that gradually become wider downward. The side frame portion 1 a of the back frame 1 is arranged on the back side of the back portion of the backrest surface mainly composed of the tension member 4 stretched on the front frame 3. Each of the left and right side frame portions 1a has a substantially square shape in a side view and a front view, and the upper frame portion 11 and the lower frame portion 13 are connected to each other via a bent portion 12. Are continuous. In the standing state, the upper frame portion 11 is tilted backward in a side view, and the lower frame portion 13 is tilted forward in a side view.

  The upper frame portion 1b in the back frame 1 is disposed on the upper back side of the backrest surface, and is a structural frame body that connects the upper end portions of the side frame portion 1a. The upper frame portion 1b is provided with elements constituting an upper connection portion for attaching the upper end portion of the front frame 3. That is, a plurality of recessed portions 14 opening forward are provided in the front surface of the upper frame portion 1b at intervals in the left-right direction. Bolt insertion holes h <b> 2 communicating with the respective recessed portions 14 are provided on the bottom surface of the upper frame portion 1 b.

  The left and right lower frame portions 1c in the back frame 1 are continuous to the left and right side frame portions 1a, and the front portion extends from the lower ends of the left and right side frame portions 1a to a position corresponding to the main axis j1. That is, a part of the left and right lower frame portions 1c is located outside the left and right arms g1 of the back support G. In other words, the left and right lower frame portions 1c extend in the front-rear direction, and the front end portions extend to both sides of the support base C disposed below the seat D.

  The left and right lower frame portions 1c are provided with concave portions 15 that open to the front side and the inner side and into which both end portions of the main shaft j1 are inserted. The recessed portion 15 constitutes a portion that accommodates the main shaft j1. A recessed step portion 15 c is formed on the opening end surface on the front end side of the recessed portion 15. The recessed portion 15 is provided therein with a plurality of wall-like mounting ribs 15a that are externally fitted to the bush g3 and spaced in the left-right direction. Each mounting rib 15a is provided with a notch 15b that can receive the bush g3 from the front side.

  The left and right lower frame portions 1c have a curved shape so as to gradually rise rearward in a side view. In addition, the left and right lower frame portions 1c are inclined backward in a side view. The left and right lower frame parts 1c are provided with bearing protrusions 16 having shaft holes a3 constituting the positioning mechanism 6 on the upper surface side in the rear part.

  The lower connecting portion 1d in the back frame 1 is for rigidly connecting the left and right lower frame portions 1c, and an upper plate portion 17 disposed on the mounting plate g2 of the back support G, and the upper plate portion. 17 and a back plate portion 18 that hangs downward from the lower edge. The upper plate portion 17 is provided with a plurality of bolt insertion holes h3, and a bolt v1 inserted through the bolt insertion holes h3 from the upper side is screwed into a nut portion (not shown) on the mounting plate g2 side to thereby attach the back frame 1. Can be fixed to the back support G. In order to insert the operation force transmission wire w provided between the rear tilt lock operation lever d5 provided on the seat D and the rear tilt lock mechanism I into the upper plate portion 17 of the lower connecting portion 1d. Wire insertion hole a4 is formed.

  The side frame portion 1a and the lower frame portion 1c constituting the back frame 1 are integrally continuous so as to form an S shape in a side view. The lower frame portion 13 and the lower frame portion 1c in the side frame portion 1a are formed in a dogleg shape in a side view, and the side frame portion 1a and the lower frame portion 1c are integrated continuously via a bent portion 19. doing.

  The side frame portion 1a and the bent portion 19 are substantially rectangular in cross-sectional view, and are formed so that the front side faces diagonally inward and the rear side faces diagonally outward. . That is, the side frame 1a and the bent portion 19 include an inner inclined surface m1 inclined inward on the front side, and an outer inclined surface m2 inclined outward on the back side. .

  The left and right side frame portions 1a in the back frame 1 described above are structurally connected only by the upper frame portion 1b. That is, the side frame portion 1b and the lower frame portion 1c that are integrally continuous in the vertical direction in the front view and the rear view (hereinafter, the side frame portion 1b and the lower frame portion 1c are collectively referred to as “side frame”). The left and right side frames (1b, 1c) are integrally connected by the upper frame portion 1b. That is, the upper frame portion 1b and the left and right side frames (1b, 1c) form a portion that has a U-shape in a front view. In this embodiment, the left and right side frames (1b, 1c) are integrally connected by the lower connecting portion 1d. However, the lower connecting portion 1d may be a separate body.

<Concealment member 2>
The concealing member 2 is disposed on the front side of the lower frame portion 1c in the back frame 1, and closes the front side of the recessed portion 15 of the lower frame portion 1c. More specifically, the concealing member 2 is made of a synthetic resin. The concealing member main body 21 has a plate shape, and the concealing member main body 21 protrudes from the inner surface of the concealing member main body 21 so as to be directly on the main shaft j1 or in the recess 15. A mounting arm 22 that is indirectly engaged is provided. In this embodiment, the attachment arm 22 is indirectly engaged with the main shaft j1 via the bush g3, and can be fitted onto the bush g3 by utilizing elastic deformation of the member.

  The concealing member main body 21 has a shape that is slightly curved so as to be convex toward the front side, and is set to a size that fits into the recessed step portion 15 c of the recessed portion 15 in the back frame 1. The concealing member main body 21 is set to a thickness dimension such that the outer surface of the concealing member main body 21 is substantially flush with the outer surface of the lower frame portion c1 around the recessed portion 15 when fitted to the recessed stepped portion 15c.

  The mounting arm 22 is a plate-shaped member protruding rearward from the concealing member main body 21 and is externally fitted to the bush g3 while being inserted into a gap sm formed between the mounting ribs 15a of the recessed portion 15. It is. Each mounting arm 22 includes a cutout portion 23 that opens rearward and can receive the bush g3 from the front side. In the cutout portion 23, the inner opening width w1 is set to a value substantially equal to the outer diameter of the bush g3, and the opening width w2 on the opening end side is set to a value smaller than the outer diameter of the bush g3. Therefore, when these attachment arms 22 are pushed into the recessed portions 15 of the lower frame portion 1c, the distal end portions of the attachment arms 22 are temporarily elastically deformed outward and then fitted onto the bush g3. In the mounted state, the concealing member main body 21 is stably held by the recessed step portion 15c. When the concealing member 2 is attached to the recessed portion 15 of the back frame 1, the mounting rib 15a of the recessed portion 15 and the mounting arm 22 of the concealing member 2 are positioned in the axial direction of the main shaft j1, that is, in the left-right direction. Will be arranged mutually.

  In the concealing member 2 having the above configuration, when the back frame 1 is rotated by a backward tilting operation or the like, the outer edge of the concealing member main body 21, that is, mainly the upper and lower end edges are engaged with the recessed step portion 15 c of the back frame 1. It can rotate integrally with the back frame 1.

<Foreground frame 3>
The front frame 3 has an upper end portion and a lower end portion supported by the back frame 1 through connection portions. The front frame 3 has a continuous frame shape when viewed from the front, and a backrest surface is formed by the tension member 4 so as to substantially match the shape of the frame. The front frame 3 is configured to be able to take a front position (f) and a rear position (r) by a positioning mechanism 6 described later. The front frame 3 includes a frame main body K and a plate L attached to the frame main body K. The front frame 3 is made of a material and a shape so as to be easily deformed as compared with the back frame 1, and has a protruding portion 32 that protrudes forward most in the middle. The front frame 3 has a side frame portion 3a that is a substantially U-shaped frame in a side view.

  The frame main body K has a continuous frame shape made of synthetic resin, and includes left and right side frame portions 3a, an upper frame portion 3b provided between upper ends of the left and right side frame portions 3a, A lower connecting frame portion 3c provided between the lower ends of the side frame portions 3a.

  The left and right side frame portions 3a of the front frame 3 are provided with mounting grooves mz for fastening the belt-like member 41 that is the edge of the tension member 4 on the outer surface, and the upper frame portion 31 that is inclined backward in a side view. The lower frame portion 33 inclined forward in a side view is connected via a protruding portion 32 that protrudes most forward. A bearing projection 35 having a shaft hole a <b> 6 that constitutes the positioning mechanism 6 protrudes from the lower ends of the left and right side frame portions 3 a.

  The upper frame portion 31 constituting the side frame portion 3 a is set to a structure that is more flexible than the lower frame portion 33. In other words, the upper frame portion 31 is set to have a structure that is easily elastically deformed rearward with the protruding portion 32 positioned at the upper end of the lower frame portion 33 as a rotation center.

  The lower frame portion 33 constituting the side frame portion 3a is formed so as to be gradually displaced inward downward. In other words, the left and right lower frame portions 33 are arranged so as to form a constricted form in which the separation distance gradually decreases downward. On the front surface of the lower frame portion 33, a recess a5 having a groove shape for positioning the lumbar support 5 is provided.

  The upper frame portion 3b of the front frame 3 is integrally constructed between the upper ends of the left and right side frame portions 3a, and has a curved shape so as to protrude rearward. The upper frame portion 3b is provided with elements constituting an upper connection portion for attaching the upper end portion of the back frame 1. That is, on the back surface of the upper frame portion 3b, projections 36 that fit into the respective recessed portions 14 of the back frame 1 are formed. Each protrusion 36 protrudes rearward and has a screw hole h4 in the vertical direction. After these protrusions 36 are fitted in the recessed portions 14 of the back frame 1, the bolts v4 inserted from below are screwed into the screw holes h4, whereby the upper frame portion 3b of the front frame 3 is screwed. Is fixed to the upper frame portion 1b of the back frame 1. An attachment groove mz for fixing the tension member 4 is provided on the upper surface of the upper frame portion 3b, and both ends are continuous with the attachment groove mz of the side frame portion 3a.

  The lower connecting frame portion 3c in the front frame 3 is constructed between the lower end portions of the left and right side frame portions 3a, and has a curved shape so as to protrude rearward in plan view. The lower connection frame portion 3c is provided with a plurality of boss portions n1 with screw holes for attaching the plate L to the front surface thereof at intervals in the left-right direction.

  The plate L is attached to substantially the entire front surface side of the lower connecting frame portion 3c in the frame body K and a part of the front surface side of the side frame portion 3a, and the lower end side edge portion 41 of the tension member 4 at the lower end portion. Can be supported. The plate L includes a plate main body 3d that covers the front surface of the lower connection frame portion 3c, and both end portions 3e that are integrally provided on both sides of the plate main body 3d.

  The plate body 3d includes a front wall 37 whose upper portion is in contact with the upper portion of the front surface of the lower connection frame portion 3c, and a rear wall 38 which is in contact with the lower portion of the front surface of the lower connection frame portion 3c. .

  The lower portion 37b of the front wall 37 is spaced apart from the front side of the rear wall 38. A mounting groove mz opened downward is formed between the rear wall 38 and the lower portion of the front wall 37, and an edge 41 on the lower end side of the tension member 4 is attached to the mounting groove mz. .

  In the vicinity of the boundary between the upper part 37a and the lower part 37b of the front wall 37, a bolt holding part h5 corresponding to the boss part n1 of the lower connecting frame part 3c is formed. Further, a portion corresponding to the bolt holding portion h5 in the lower portion 37b of the front wall 37 is notched downward so that the bolt v5 is screwed to the boss portion n1 of the lower connecting frame portion 3c through the bolt holding portion h5. A notch 37c is provided.

  Both end portions 3e face the front surface of the lower end portion of the side frame portion 3a via a gap sk. In other words, a gap sk for attaching the lumbar support 5 is formed between the back surface of the both end portions 3 e and the front surface of the side frame portion 3 a in the front frame 3.

  Both end portions 3 e are provided with claw members 39 that are engaging elements for holding the lumbar support 5. At both ends 3e, an upward U-shaped slit s1 is formed, and a portion surrounded by the slit s1 is a claw member 39 that can be elastically deformed in the thickness direction. These claw members 39 are provided with protruding portions (not shown) that are elastically engaged with the claw receiving portions 57 of the lumbar support 5 on the back side thereof.

<Tension member 4>
The tension member 4 has a belt-like member 41 fastened to the periphery of a mesh-like fabric that can form a backrest surface by sewing or the like. The tension member 4 is stretched on the front surface of the front frame 3 by engaging a belt-like member 41 as an edge thereof with an attachment groove mz provided around the front frame 3.

  The tension member 4 is positioned in front of the lumbar support 5. For this reason, the tension member 4 in this embodiment can exhibit a function of restricting the movement of the lumbar support 5 to the front side of the front frame 3, that is, a function of preventing the lumbar support 5 from coming off to the front side of the front frame 3. It has become.

<Lumbar support 5>
The lumbar support 5 is for supporting the seated person's waist from the back side, and in this embodiment, the lumbar support 5 is attached to the front frame 3 on which the tension member 4 is stretched. It is configured to be able to. Here, “retrofitting” does not mean attachment after the stage when the chair A reaches the consumer, but more specifically, after the backrest H provided with the tension member 4 is constructed, This means attachment after the tension member 4 is stretched on the front frame 3.

  The lumbar support 5 is disposed between the left and right side frame portions 3a of the front frame 3 constituting the backrest H. The lumbar support 5 is provided at a lower portion of the front frame 3 which is set to be relatively higher in rigidity than other portions. It is attached. In other words, both ends of the lumbar support 5 are attached to the lower frame portion 33 of the side frame portion 3a. The lower frame portion 33 is set to have relatively high rigidity, and the lumbar support 5 is difficult to come off even when the weight of the seated person is received. That is, the lower frame portion 33 can stably support the lumbar support 5 and can appropriately exhibit the function as the lumbar support 5.

  The lumbar support 5 includes a curved plate-like lumbar support main body 5a that receives a load from the user, and attachment portions 5b provided at both ends of the lumbar support main body 5a, and is integrally formed of synthetic resin. ing.

  The lumbar support main body 5a has a plate shape, and has a substantially horizontal belt-like region 51 whose left and right ends are continuous with the mounting portion 5b, and an upper region 52 extending upward from the upper edge of the belt-like region 51. It is made. The lumbar support main body 5 a includes a lower region 53 that extends downward from the lower edge of the belt-like region 51.

  In other words, the lumbar support main body 5a is located at the middle portion in the left-right direction and has a main portion 54 that is substantially horizontally long in a front view, and the left and right corners of the main portion 54 diagonally downward and outward. And a continuous portion 55 extending toward the front. A mounting portion 5b formed in a strip shape in front view is integrally provided at the extended end of the continuous portion 55. The belt-like region 51 is constituted by a part of the main part 54 and a part of the continuous part 55. The upper region 52 is mainly composed of the upper portion of the main portion 54. The lower region 53 is configured by a part of the continuous portion 55.

  The belt-like region 51 is a portion that extends linearly in the left-right direction when viewed from the front, and the attachment portions 5b are integrally provided over the entire area of both end edges. The belt-like region 51 cooperates with the side frame portion 3a of the front frame 3 and serves as a main portion that receives the load of the seated person. In FIGS. 23 to 25, the band-like region 51 is shaded for easy understanding. The belt-like region 51 connects the left and right attachment portions 5b in a straight line, and provides strength for receiving the load of the seated person as a whole of the lumbar support 5 with these as a main component.

  The upper region 52 is set to a size and a shape such that a space sp is formed between both side edges and the left and right side frame portions 3a of the front frame 3. In other words, the upper region 52 extends upward from the entire upper edge of the belt-like region 51, and has a form in which the left-right width dimension gradually decreases upward. A space sp is formed between both side edges of the upper region 52 and the upper frame portion 31 of the side frame portion 3a. The upper region 52 tends to bend backward when the load of the seated person is received, with the vicinity of the boundary with the belt-like region 51 as the base end.

  The upper region 52 is set to be disposed at a height position corresponding to the upper frame portion 31 of the front frame 3 and is set to be more easily bent in the thickness direction than the belt-like region 51. In this embodiment, the upper region 52 has a hat shape in a front view in which a lower end portion is configured to be horizontally longer than the upper portion. The upper region 52 has a shape curved together with the belt-like region 51 so as to protrude backward in plan view corresponding to the shape of the tension member 4. The upper region 52 has recesses 52a extending in the left-right direction at two upper and lower positions on the back side, and is configured to be easily bent in the thickness direction. The upper region 52 has a shape in which an upper edge portion warps backward in a side view. That is, the upper region 52 is provided with a rear warp 52b at the upper end.

  The lower region 53 extends downward from the lower edge of the belt-like region 51. The lower region 53 is provided between the vicinity of both ends of the lower edge of the belt-like region 51 and the attachment portion 5b. The lower region 53 plays a role of securing the attachment strength between the belt-like region 51 and the attachment portion 5b.

  The attachment portions 5b are provided at both end portions of the lumbar support main body 5a and are attached to the lower frame portion 33 in the side frame portion 3a and both end portions 3e of the plate L. The attachment portion 5b is a long and narrow plate-like member that extends below the belt-like region 51 and the lower region 53 along the lower frame portion 33, and includes a protruding portion 56 that protrudes rearward and forms a rib shape on the back surface. A square hole-shaped claw receiving portion 57 with which the claw member 39 of the plate L is engaged is provided at the lower end portion.

  The attachment portion 5 b is disposed between the front surface of the lower frame portion 33 in the front frame 3 and the back surface of the tension member 4. The attachment portion 5b is attached to the front frame 3 in a state where the tension member 4 is stretched by moving the lumbar support 5 from the back side. That is, the lumbar support 5 is pressed against the back surface of the tension member 4 from the back side of the backrest H, and the attachment portion 5b of the lumbar support 5 is inserted between the tension member 4 and the frame body K. To do. When operated in this way, in the final stage, the protruding portion 56 of the mounting portion 5b is fitted into the recessed portion a5 of the lower frame portion 33, and the claw receiving portion 57 of the mounting portion 5b is connected to the lower frame of the frame main body K. The gap sk between the portion 33 and both end portions 3e of the plate L is interrupted and engaged with the claw member 39 of the plate L. In this way, the attachment portion 5b is located between the lower frame portion 33 and the tension member 4, and the protruding portion 56 and the recessed portion a5, and the claw receiving portion 57 and the claw member 39 are engaged with each other. In this state, the lumbar support 5 is attached so as not to be detached from the front frame 3. In other words, the protrusion 56 and the recessed part a5 constitute a separation preventing element, and the claw receiving part 57 and the claw member 39 constitute an engaging element.

  The separation preventing element is for receiving a load applied to the lumbar support 5, and is provided between the attachment portion 5b and the front frame 3 as a frame. In this embodiment, the separation preventing element is configured by a recessed portion a <b> 5 extending along the longitudinal direction of the front frame 3 and a protruding portion 56 provided on the lumbar support 5.

  The engaging element is for attaching the lumbar support 5 to the front frame 3 which is a frame using elastic deformation of the member. In this embodiment, the engaging element is constituted by a claw member 39 provided on the front frame 3 and a claw receiving portion 57 provided on the lumbar support 5.

  In this embodiment, the positions of the engaging elements (39, 57) and the positions of the separation preventing elements (a5, 56) are arranged separately. The fixing when the lumbar support 5 is attached to the front frame 3 is made to function mainly by the engaging elements (39, 57), and the load on the seated person after the lumbar support 5 is attached to the front frame 3 The resistance is made to function mainly by the separation preventing elements (a5, 56). For this reason, the structure of the attachment part 5b and the front frame 3 can be suitably provided according to a function.

  The front frame 3 is connected to the lower frame of the front frame 3 and the back frame 1 holding the lumbar support 5 as described above, that is, to the lower frame of the front frame 3 and the connection portion of the back frame 1. In contrast, a positioning mechanism 6 capable of selectively positioning at two different positions is provided.

<Positioning mechanism 6>
The positioning mechanism 6 can be positioned by selecting the position of the lower end of the front frame 3 at the front position (f) or the rear position (r). It is configured so that it can be stably positioned at either the position (f) or the rear position (r).

  The positioning mechanism 6 includes left and right links 6 a and 6 b pivotally supported so as to be able to rotate in the front-rear direction with respect to the back frame 1, and rotating ends of the left and right links 6 a and 6 b. And a tip shaft j7 which is a pivot element pivotally connected to the lower end portion. The left and right links 6a and 6b can be rotated only between a front position (a) that is a forward dead center inclined forward and a rear position (c) that is a rear dead center inclined backward. Is set.

  Between the front position (a) and the rear position (c) of the left and right links 6a and 6b, an intermediate position that is a thought point where the direction of the rotational biasing of the left and right links 6a and 6b by the front frame 3 is reversed. (B) is set. In other words, the intermediate position (b) exists between the front position (a) and the rear position (c) in the left and right links 6a and 6b. The upper end portion of the front frame 3 has the left and right links 6a and 6b compared to the amount of elastic deformation of the front frame 3 when the left and right links 6a and 6b are in the front position (a) or the rear position (c). It connects with the upper end part of the back frame 1 so that the amount of elastic deformation of the front frame 3 in the intermediate position (b) may become large.

  The positioning mechanism 6 is provided between the rearwardly inclined portion in the lower part of the back frame 1 and the lower end portion of the front frame 3. The positioning mechanism 6 includes left and right links 6a and 6b provided on the back frame 1 and arranged in pairs on the left and right sides, and the rotating ends of the left and right links 6a and 6b at the lower end of the front frame 3. It is provided with a tip shaft j7 which is a pair of left and right pivoting elements pivoted on both side portions, and an operating lever 6c for directly rotating the left link 6a which is one of the links.

  The left link 6a (located on the left side in front view) is rotated in the front-rear direction by an operating force applied to the operation lever 6c, and includes an inner link member 61 and an outer link member 62. .

  The lower part of the inner link member 61 is in contact with the inner side surface of the bearing protrusion 16 in the back frame 1 and the upper part is in contact with the inner side surface of the bearing protrusion 35 in the front frame 3. The inner link member 61 includes a proximal end shaft j6 that is inserted into the shaft hole a3 of the bearing projection 16 in the back frame 1 and a distal end shaft that is a pivotal element that is inserted into the shaft hole a6 of the bearing projection 35 in the front frame 3. j7 is integrally provided. A bolt insertion hole h <b> 6 is formed at an intermediate position of the inner link member 61.

  The lower part of the outer link member 62 is in contact with the outer surface of the bearing protrusion 16 in the back frame 1 and the upper part thereof is in contact with the outer surface of the bearing protrusion 35 in the front frame 3. A proximal end side fitting hole a7 into which the through end is fitted and a distal end side fitting hole a8 into which the through end of the distal end shaft j7 is fitted are provided. A spacer projection 63 is provided at an intermediate position of the outer link member 62 to keep the distance between the outer link member 62 and the inner link member 61 constant. The spacer protrusion 63 includes a screw hole n2 into which a bolt v6 inserted through the bolt insertion hole h6 is screwed. That is, the inner link member 61 and the outer link member 62 are coupled by screwing the bolt v6 into the screw hole n2.

  The spacer protrusion 63 is configured such that the front edge or the rear edge of the spacer protrusion 63 can come into contact with the front surface or the rear surface of the bearing protrusion 16 in the back frame 1, and the left link 6a is moved from the front position (a) to the rear position ( It has a function of restricting the rotation range so that it can rotate only until c). In this embodiment, as shown in FIGS. 9 and 10, the left link 6a at the front position (a) and the left link 6a at the rear position (c) are centered on the virtual center line ct on the base end axis j6. It is set to be able to take a posture inclined substantially symmetrically.

  On the outer side surface of the base end portion of the outer link member 62, a prismatic boss portion h7 is projected so that the shaft center coincides with the shaft center of the base end side fitting hole a7. The base end portion of the operation lever 6c is fitted to the boss portion h7, and is prevented from coming off from the boss portion h7 by a bolt v7. A ring member 6d is interposed between the peripheral edge of the base end portion of the operation lever 6c and the outer link member 62. The operation lever 6 c connected to the outer link member 62 can rotate integrally with the outer link member 62.

  The right link 6b (located on the right side in the front view) has a configuration similar to that of the left link 6a described above, and the corresponding components are denoted by the same reference numerals and description thereof is omitted.

  The right link 6b is different from the left link 6a in that the outer link member 62 is not provided with an operation lever. Here, the front frame 3 directly operates the operation lever 6c at the lower end thereof, that is, the portion between the left bearing projection 35 and the right bearing projection 35 in the front frame 3 to directly connect the left link 6a. It has rigidity that can transmit the operating force when it is rotated to the right link 6b. For this reason, the operating force of the operating lever 6c attached to the left link 6a is not provided with an operating lever on the right link 6b or a special mechanism for connecting the left and right links 6a, 6b. It is transmitted to the right link 6b through the front frame 3.

  The operation related to the positioning mechanism 6 described above will be described as follows.

  As shown in the imaginary lines in FIGS. 1, 4, 5 and FIGS. 8 to 10, when the left and right links 6 a and 6 b are in the front position (a), the left and right links 6 a and 6 b are connected to the front frame 3. Is urged in a forward tilting direction in response to an elastic repulsive force from the front, and is stably held at the front position (a). In this state, the lower portion of the front frame 3 is held at a position away from the back frame 1 in a side view. From this state, when the operation lever 6c provided on the left link 6a is rotated backward, the left link 6a passes from the front position (a) through the intermediate position (b) to the rear position (c). The lower part of the front frame 3 moves to a position partially covering the back frame 1 in a side view. At this time, the right link 6b follows the movement of the lower end portion of the front frame 3 and rotates from the front position (a) to the rear position (c) through the intermediate position (b). Become. The left and right links 6a and 6b rotate while elastically deforming the projecting portion 32 of the front frame 3 so that the degree of bending of the projecting portion 32 increases, as shown by the solid line in FIG. If (b) is exceeded, the elastic repulsive force for returning the protruding portion 32 in the front frame 3 immediately after that acts as a force for rotating the left and right links 6a, 6b backward. The left and right links 6a and 6b that have received the elastic repulsive force of the front frame 3 are positioned and stably held when they reach the rear position (c) as shown by the solid lines in FIGS. Become.

  As shown by the solid line in FIG. 8, in the state where the left and right links 6 a and 6 b are held at the rear position (c), the front frame 3 has a rear edge portion of the side frame portion 3 a in the front frame 3. It moves to the position which covers the side frame part 1a of the back frame 1 in a side view, and is positioned. In other words, in the state where the left and right links 6a and 6b are held at the rear position (c), the front frame is compared with the state where the left and right links 6a and 6b are held at the front position (a). 3, that is, the side frame portion 3 a, the lower connection frame portion 3 c, and the plate L of the front frame 3 are close to the back frame 1.

  In this embodiment, the upper end portion of the front frame 3 is fixed to the back frame 1 with a bolt v4. For this reason, when the left and right links 6a and 6b rotate from the front position (a) to the rear position (c), the upper end portion of the front frame 3 becomes the rotation center, that is, the base end portion, and hardly moves. The lower end portion of the front frame 3 becomes a rotating end portion and moves rearward. The height position of the rotation end when the left and right links 6a and 6b are at the front position (a) and the height position of the rotation end when the left and right links 6a and 6b are at the rear position (c) are as follows. It is set to be almost the same.

  In this embodiment, when the front frame 3 is in the front position (f), the lumbar support 5 supported by the front frame 3 is such that the belt-like region 51 is positioned in front of the upper region 52 and the front When the frame 3 is in the rear position (r), the upper region 52 is positioned in front of the belt-like region 51. That is, the lumbar support 5 in the case where the front frame 3 is in the rear position (r) takes a posture inclined forward than in the case where the front frame 3 is in the front position (f).

  In addition, the positioning mechanism 6 sets the rotation range of the left and right links 6a and 6b so that the height position of the rotation end at the front position (a) and the height position of the rotation end at the rear position (c). If the left and right links 6a and 6b are in the front position (a) and the rear position (c), the relative position between the side frame portion 3a of the front frame 3 and the lumbar support 5 is different. Can be changed. That is, the side view shape of the front frame 3 is different between the state in which the left and right links 6a and 6b are in the front position (a) and the state in which the left and right links 6a and 6b are in the rear position (c). Will be able to. Specifically, the relative angle between the upper frame portion 31 and the lower frame portion 33 of the side frame portion 3a constituting the front frame 3 (that is, the degree of bending of the protruding portion 32) changes, and the lower frame The relative position between the upper region 52 of the lumbar support 5 supported by the portion 33 and the upper frame portion 31 changes. In other words, the lumbar support 5 is attached to a position where the relative position of the upper region 52 with respect to the upper frame portion 31 changes as the side frame portion 3a of the front frame 3 is deformed.

  For example, the relative angle between the upper frame portion 31 and the lower frame portion 33 in a state where the left and right links 6a and 6b are positioned at the rear position (c), and the left and right links 6a and 6b are the front position (a). It is also possible to make it larger than the relative angle between the upper frame portion 31 and the lower frame portion 33 in the state of being positioned in the position. That is, by rotating the left and right links 6a and 6b from the front position (a) to the rear position (c), the lumbar support 5 performs a forward tilting operation, and the upper region 52 of the lumbar support 5 is moved. In the side view, the upper frame portion 31 is relatively approached. The upper region 52 of the lumbar support 5 when the left and right links 6a and 6b are at the rear position (c) is more tensioned in a no-load state than when the left and right links 6a and 6b are at the front position (a). It approaches the back side of the member 4.

<< Backward tilt lock mechanism I >>
The backward tilt lock mechanism I is for locking the backrest H at a desired rearward tilt position, and is provided between the back support G and the support base C in this embodiment.

  The backward tilt lock mechanism I includes a lock unit M that forms a main part of the rear tilt lock mechanism I on the back support G side, and the engagement member 7 of the lock unit M selectively engages on the support base C side. And a receiving member N having a plurality of engaging portions c8.

  The lock unit M is a lock position (h) that prohibits the backward tilting operation of the backrest structure F (back support G / backrest H) with respect to the support base C, or the free tilting that allows the backrest structure F to tilt backward. The engaging member 7 that can take the position (i), the driving mechanism 8 that drives the engaging member 7 between the lock position (h) and the free position (i), and the driving mechanism 8 and the engaging member 7. And a support member 9 for supporting the.

  The lock unit M is composed of a plurality of parts assembled together on the support member 9, and in the manufacturing stage of the chair A, the lock unit M is assembled on an independent specific manufacturing line and the operation is independently confirmed on the manufacturing line. Can be done. In other words, the lock unit M forms a package in which the engagement member 7 and the drive mechanism 8 are held by the support member 9 that is a basic body, and is configured so as to be directly applicable to other chairs. At the completion stage of the chair A, the first housing 9a constituting the support member 9 of the lock unit M is joined to the back support G by welding.

  Hereinafter, the configuration of the lock unit M will be described in detail.

  The engagement member 7 is a plate-shaped member having a substantially rectangular shape in plan view with an engagement protrusion 71 disposed on the distal end side, and is advanced and retracted in a direction in which the engagement member 7 contacts and separates from the receiving member N. It is supported by. A long hole 72 extending in a direction orthogonal to the advancing / retreating direction is formed in an intermediate portion of the engaging member 7. Further, a protrusion 73 as a spring retainer for engaging the front end of the locking spring 81 is provided at the center of the rear edge of the engaging member 7.

  The drive mechanism 8 engages the lock spring 81 that urges the engagement member 7 in the lock direction, that is, the direction of the engagement portion c8, and the operation force transmitted through the wire w from the operation lever d5 for backward tilt lock. An operation conversion mechanism 82 for converting the combined member 7 into a force for retracting the combined member 7 is provided.

  The lock spring 81 is of the compression coil type, and is interposed between the engagement member 7 and a rear wall 96 of a second housing 9b described later.

  The motion conversion mechanism 82 includes an operation arm 83 whose base end portion is rotatably supported by the second housing 9b constituting the support member 9 and whose distal end portion is connected to the wire w, and is provided on the operation arm 83. An unlocking spring 86 is provided in which an operating end 86 b that rotates as the operating arm 83 rotates is engaged with the elongated hole 72.

  The operation arm 83 is supported by a shaft j8 provided in the second housing 9b and rotates in the front-rear direction. A shaft hole a9 in which the shaft j8 of the second housing 9b engages is formed at the base end portion. The wire connection part 84 for connecting the front-end | tip of the said wire w to the rotation end part is provided. In addition, a spring attachment portion 85 for attaching the unlocking spring 86 is provided at the base end portion of the operation arm 83. The unlocking spring 86 includes a coiled spring body 86a, one coil end 86b extending from one end of the spring body 86a, and the other coil end 86c extending from the other end of the spring body 86a. In this embodiment, one coil end 86 b forms an operation end 86 b for urging the engagement member 7. The spring mounting portion 85 is provided at the base end portion of the operation arm 83, and a notch portion 85a for accommodating the spring body 86a in alignment with the axis of the shaft hole a9, and the spring body 86a accommodated in the notch portion 85a. And a coil end holding portion 85b for holding the other coil end 86c extending from.

  The support member 9 is a basic structure for unitization so that a plurality of components, that is, the engagement member 7 and the drive mechanism 8 can be handled collectively in the manufacturing stage of the chair A. A first housing 9a that slidably supports the member 7 and a second housing 9b that supports the drive mechanism 8 are provided.

  The first housing 9a has a channel shape opened upward, and includes a bottom wall 91, a front wall 92 extending upward from a front edge of the bottom wall 91, and a rear wall of the bottom wall 91. And a rear wall 93 extending upward from the edge.

  The bottom wall 91 includes a back support G including a window 91a for allowing the operation end 86b of the unlocking spring 86 to pass through, a housing attachment hole 91b for attaching the second housing 9b, and a backward tilting lock mechanism I. And a cover mounting hole 91c for mounting a cover g7 covering the lower surface side of the rear part. A slit s2 extending in the left-right direction is formed in the front wall 91, and the front end side of the engagement member 7 is held in the slit s2 so as to be slidable in the front-rear direction. A slit s3 extending in the left-right direction is formed in the rear wall 92, and the rear end side of the engagement member 7 is held in the slit s3 so as to be slidable in the front-rear direction. That is, the engaging member 7 is held by the first housing 9a so as to be able to advance and retreat in the front-rear direction while penetrating the front wall 92 and the rear wall 93 of the first housing 9a.

  The second housing 9b includes a bottom wall 94, side walls 95 extending upward from the left and right side edges of the bottom wall 94, and a rear wall extending upward from the rear edge of the bottom wall 94. A wall 96 and an attachment rod 97 provided to extend rearward from the upper edge of the rear wall 96 are provided.

  The bottom wall 94 includes a cross rib-shaped shaft j8 that pivotally supports the operation arm 83 of the drive mechanism 8 so as to be horizontally rotatable. That is, the operation arm 83 is rotatably attached to the second housing 9b by engaging the shaft hole a9 of the operation arm 83 holding the unlocking spring 86 with the shaft j8.

  The side wall 95 includes an upward edge 95a that contacts the lower surface of the bottom wall 91 of the first housing 9a, and a forward edge 95c for locking the rear end of the engagement member 7 in the free position (i). When viewed from the side, the shape is generally L-shaped, and an elastic claw 95b that projects into the housing attachment hole 91b of the first housing 9a protrudes from the upward edge portion 95a.

  The rear wall 96 includes a front wall portion 96a facing front and an inclined wall portion 96b facing diagonally forward, and a spring retainer portion 96c for holding the rear end of the locking spring 81 is provided on the front wall portion 96a. ing. A window 96d is formed in the inclined wall portion 96b, and an attachment portion 96e for attaching one end of the tube t holding the wire w to the lower edge portion of the window 96d.

  The mounting rod 97 is in contact with the lower surface of the mounting plate g2 in the back support G, and includes a bolt insertion hole h8 in which a bolt v8 for fixing the second housing 9b to the mounting plate g2 is mounted. ing.

  In this embodiment, the first housing 9a is made of metal, and the second housing 9b is made of synthetic resin. The first and second housings 9b are disposed between the left and right arms g1 of the back support G.

  In the state where the chair A is completed, the first housing 9a is connected to the left and right arms g1 by welding, and also serves as a strength member. Even after the chair A is completed, the second housing 9b that houses the drive mechanism 8 is removed from the back support G and the first housing 9a by removing the bolt v8 and deforming the elastic claw 95b. Be able to.

  The engagement member 7 of the lock unit M configured as described above is selectively engaged with any of the plurality of engagement portions c8 in the receiving member N provided at the rear end of the support base C, thereby The drooping structure F can be locked at a desired rearward tilt position.

  The receiving member N is a wall-like member that also serves as the rear wall c7 of the support base C, and includes a plurality of sets of engaging portions c8 spaced apart in the vertical direction. In this embodiment, the receiving member N includes a pair of left and right engaging portions c8 provided in the upper stage, a pair of left and right engaging parts c8 provided in the middle stage, and a pair of left and right engaging parts provided in the lower stage. And a joint part c8. The pair of left and right engaging portions c8 provided in the upper stage is for locking the backrest H at the initial position shown in FIGS. 1 to 6, and is constituted by a stepped portion having a concave shape. The middle and lower engaging portions c8 are formed by through holes that are recessed.

  Next, the operation of the backward tilt lock mechanism I will be described.

  When the wire w is not pulled by the operation lever d5 for backward tilt locking, the operating arm 83 is held at the front position (j), and the engaging member 7 is moved forward by the urging force of the locking spring 81. It is elastically biased. Therefore, when the engaging member 7 faces the engaging portion c8 of the receiving member N by the rotation of the backrest H, the engaging member 7 moves forward and the engaging portion c8 where the engaging protrusion 71 faces. Will be engaged. In a state where the engagement protrusion 71 is engaged with the engagement portion c8, the backrest H cannot be tilted backward.

  From the state where the back tilt of the backrest H is locked, when the wire w is pulled by the back tilt lock operation lever d5 and the operation for releasing the lock is performed, the operation force is transmitted via the wire w. This is transmitted to the operation arm 83, and the operation arm 83 rotates rearward, that is, toward the rear position (k). As the operation arm 83 pivots rearward, the operation end 86b of the unlocking spring 86 also moves rearward, so that the engagement member 7 is retracted and the engagement protrusion 71 and the engagement portion c8 move. The engagement is released. In a state where the engagement protrusion 71 and the engagement portion c8 are disengaged, the back tilting operation of the backrest H can be freely performed. At this time, the operation lever d5 for backward tilt locking can be fixed in a state in which the wire w is pulled, and in such a case, the seated person can freely lift the backrest H by its own load. Can be tilted.

  Even when the operating arm 83 rotates toward the rear position (k), when the friction between the engaging member 7 and the receiving member N is large, the engaging member 7 cannot temporarily move backward. Then, the operation end 86 b of the lock release spring 86 is left in the lock position (h) together with the engagement member 7. In this state, the operation end 86b of the unlocking spring 86 is restricted from moving backward by the engaging member 7 in a state in which the operation end 86b does not move, and the elastic repulsion force in the unlocking direction is increased. In other words, when the operation end 86b of the unlocking spring 86 is left in the locked position (h) together with the engaging member 7, the rearward elastic biasing force by the unlocking spring 86 is exerted on the engaging member 7. Will work. Therefore, at the moment when the friction between the engaging portion c8 and the receiving member N is reduced due to the fine movement of the backrest H, the engaging member 7 is moved backward by the elastic biasing force of the unlocking spring 86, and the lock is released. It will be released.

<< Locking mechanism J >>
The locking mechanism J is for moving the seat D in synchronization with the tilting of the backrest H, and the front portion of the seat receiver d1 can be moved back and forth via the front link c9 at the front end portion of the support base C. In addition to being supported, the rear portion of the seat D is pivotally supported by a rear link g4 provided on the back support G through a rear connecting shaft j4.

  In the locking mechanism J in this embodiment, in the initial state, the front link c9 and the rear link g4 are inclined forward, and the seat D rises as a whole when the backrest H is tilted backward. The so-called weight sensing method is configured as described above.

  As described above, the chair A according to the present embodiment includes the backrest H in which the front frame 3 on which the tension member 4 is stretched is arranged on the front side of the back frame 1 so that the front and rear positions can be changed. . A lumbar support 5 is attached to the front frame 3.

  Therefore, it is possible to provide the chair A including the backrest H provided with the lumbar support 5 that can favorably support the waist portion of the seated person. That is, since the lumbar support 5 is attached to the front frame 3, the seated person can preferably obtain the operational effects of the lumbar support 5 even when the relative position between the front frame 3 and the back frame 1 changes. It has become.

  A lumbar support 5 is attached to the lower part of the front frame 3. For this reason, the lumbar support 5 is attached to a portion of the front frame 3 where the rigidity tends to be relatively high, and the lumbar support 5 can be suitably held with respect to the front frame 3.

  The front frame 3 includes left and right side frame portions 3a, an upper frame portion 3b provided between upper ends of the left and right side frame portions 3a, and a lower connection provided between lower ends of the left and right side frame portions 3a. A frame main body K having a frame portion 3c is provided. The side frame portion 3a includes a lower frame portion 33 formed so as to be gradually displaced inward toward the lower side, and the lumbar support 5 has both ends thereof at the lower frame. It is attached to the portion 33. For this reason, both ends of the lumbar support 5 are attached to the lower frame portion 33, which is a portion where the rigidity tends to be relatively high in the front frame 3, and the lumbar support 5 is suitably held with respect to the front frame 3. Can be done.

  The lumbar support 5 includes a lumbar support main body 5 a that receives a load from a user, and attachment portions 5 b that are provided at both ends of the lumbar support main body 5 a and are attached to the lower frame portion 33. For this reason, the load of the seated person is suitably received by the lumbar support main body 5a, and the attachment portion 5b is attached to the lower frame portion 33, so that the lumbar support 5 is suitably supported by the frame main body K.

  The front frame 3 is formed by connecting the upper end portion and the lower end portion to the back frame 1. Therefore, it is possible to provide a configuration in which the front frame 3 directly receives the seated person's load and the back frame 1 supports the front frame 3 from the rear side.

  With such a backrest H configuration, the front frame 3 is easy to have a soft structure that is relatively easily elastically deformed, and is flexible so that the back of the seated person is wrapped in the front frame 3. It is easy to impart sex.

  The front frame 3 is more easily deformed than the back frame 1. For this reason, it becomes easy to give the front frame 3 the flexibility which wraps a seated person's back part. In addition, since the front frame 3 holds the lumbar support 5, it can not only give a comfortable feeling to the seated person but also suitably support the waist part of the seated person to give the seated person a sense of security. It has become something that can be.

  That is, the front frame 3 is maintained in a state in which a certain degree of flexibility is maintained, that is, a state in which it can be elastically deformed. However, the front frame 3 supports the lumbar support 5 so that the necessary rigidity is secured in cooperation with the lumbar support 5.

  The front frame 3 has a substantially U-shape in a side view with a protruding portion 32 that protrudes most forward in the middle part. For this reason, the tension member 4 stretched on the front frame 3 can be held so as to surround the waist of the seated person from the side.

  The side frame portion 3a is formed by connecting the upper frame portion 31 and the lower frame portion 33 through the projecting portion 32, and the upper frame portion 31 is more easily bent than the lower frame portion 33, and has a lumbar support. The main body 5 a includes an upper region 52 that is easily bent at a height corresponding to the upper frame portion 31. For this reason, the upper frame portion 31 of the side frame portion 3a tilts rearward under the load of the seated person, and the upper region 52 of the lumbar support main body 5a can suitably support the seated person's back.

  The present invention is not limited to the embodiment described in detail above.

  Any means for allowing the front frame to change its position back and forth with respect to the back frame may be used, and is not limited to that shown in the present embodiment.

  Various shapes and structures of the lumbar support are conceivable and are not limited to those shown in the above-described embodiments.

  Various shapes and structures of the front frame and the back frame are conceivable and are not limited to those shown in the above-described embodiments.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Back frame 3 ... Front back frame 4 ... Tension member 5 ... Lumber support H ... Backrest

Claims (6)

A chair comprising a backrest with a front frame on which a tension member is stretched arranged on the front side of the back frame so that the position of the front frame can be changed back and forth,
A lumbar support is attached to the front frame ,
The front frame includes left and right side frame portions, an upper frame portion provided between upper ends of the left and right side frame portions, and a lower connection frame portion provided between lower ends of the left and right side frame portions. It has a frame body with
The side frame portion is provided with left and right lower frame portions formed so as to be gradually displaced inward toward the lower side;
The lumbar support is a chair having both end portions attached to the left and right lower frame portions . 2. The chair according to claim 1, wherein the lumbar support includes a lumbar support main body that receives a load of a seated person, and attachment portions that are provided at both ends of the lumbar support main body and are attached to the lower frame portion. The chair according to claim 1 or 2, wherein an upper end portion and a lower end portion of the front frame are respectively connected to the back frame. The chair according to claim 1, 2, or 3, wherein the front frame has a structure that is more easily deformed than the back frame. The chair according to claim 1, 2, 3, or 4, wherein the front frame has a generally U-shape when viewed from the side, and has a protruding portion that protrudes forward most forward in an intermediate portion in the vertical direction. The front frame includes a side frame part formed by connecting an upper frame part tilted rearward in a side view and a lower frame part tilted forward in a side view through a protruding part protruding forward.
The lumbar support, the is supported by the lower frame portion, the lumbar part of the support, wherein the upper frame part according to claim 1, 2, 3, 4 or which are arranged at a height position corresponding to the 5 The listed chair.

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