JP4721182B2 - Chair - Google Patents

Description

  The present invention relates to a chair capable of tilting an upper part of a backrest.

  A chair is known in which a backrest surface is constructed by spanning a stretched fabric between a pair of upper and lower frames. For example, in the following patent document, the upper part of the backrest surface is supported by the upper frame, and the lower part of the backrest surface is supported by the lower frame. A chair that can form a backrest surface that matches the body shape and spine shape of an individual is disclosed.

  If the upholstery is provided directly on the rigid frame, the rigidity of the frame is transmitted to the seated person and causes a decrease in sitting comfort. In addition, when receiving the load of the seated person, the side of the upholstery tends to bend inward. In order to deal with these events, a back-up material is attached to the back side of the upholstery to act as a buffer to prevent the frame from being felt by operating the leaf spring, and at the same time, the side of the upholstery is retained. Is done.

In the chair described in the following patent document, an elastic body having a substantially square shape in front view divided into two parts up and down is arranged as a back-up material on the back of the stretch fabric, and each is fixed to the upper frame element and the lower frame element, respectively. The upper and lower elastic bodies are connected to each other in such a manner that the free ends close to each other overlap each other and the overlapping portion can be relatively slid up and down. In other words, the vertical dimension of the entire backup material is variable. This is because the distance between the upper and lower ends of the backrest surface changes when only the upper frame is tilted independently.
JP 2002-119390 A

  However, in the case of the above example, the overlapping part of the elastic body is positioned in the middle of the upper and lower ends of the backrest surface, and there is a possibility of giving a foreign body feeling to the seated person's back. There is a need to cover and shield the overlap part by attaching a urethane cushion separately. In addition, since the back-up material is divided into upper and lower pieces and a connecting tool that connects them in a relatively slidable manner is used, the structure becomes complicated and the number of parts tends to increase.

  The present invention made in view of the above problems is intended to realize a backrest that provides a comfortable sitting comfort with a simple configuration.

In order to solve the above-described problems, in the present invention, the separation distance between the upper end portion and the lower end portion of the back frame is variable through tilting with respect to the lower frame portion of the upper frame portion in the back frame, and expansion and contraction between these upper and lower end portions and bridging a freely upholstery in a chair having a backrest constitutes a backrest surface, provided a resin backup material for keeping taut the fabric tension at the edge of the upholstery, the backup The material is interposed between the back frame and the upholstery, and the upholstery is projected forward, with the upper end of the upholstery and backup material at the upper end of the back frame and the lower end of the upholstery and backup material. each is supported at the lower end of the back frame, and, in one of the upper and lower ends of the back frame, and fixed to the back frame upholstery and backup material, other odor , Upholstery backup material while fixed to the back frame was set to be vertically slide to the back frame. If it is such, it is not necessary to divide the backup material into upper and lower pieces, and the structure can be simplified. And the problem that the overlap part of a backup material gives a foreign body feeling to a seated person's back can be eliminated effectively.

  Specifically, the backup material is a thin plate body that can be bent and deformed in the front-rear direction, with the vertical frame paired on the left and right sides and the horizontal frame connecting the vertical frames forming a substantially three-sided or four-sided frame shape when viewed from the front. And If the central portion of the backup material is hollow, it is possible to provide a soft seating comfort without preventing the upholstery under the load of the seated person from being deformed so as to sink back.

  When the upper part of the backrest is tilted backwards and the seated person's back is bent, the seated person's buttocks is naturally separated from the backrest surface. Therefore, while fixing the upper end of the backup material to the upper end of the back frame, while supporting the lower end of the backup material slidably up and down on the lower end of the back frame, the left and right side edges of the upholstery are in the vertical frame, It is considered preferable that the upper edge is held in the horizontal frame in order not to give the occupant an uncomfortable feeling.

  The length of the lumbar support belt is the length of the lumbar support belt when the lumbar support belt is supported by the left and right vertical frames of the back-up material and the occupant leans over the backrest. You may make it not sink back more than the depth which responded.

  A mounting structure between the upholstery and the backup material may be simplified by forming a concave groove on the end face of the backup material and fitting and locking the edge of the upholstery into the concave groove. If the upholstery can be detached from the chair, it contributes to the improvement of maintenance such as replacement of the upholstery and washing.

The backup material is preferably a thin plate body that acts as a leaf spring that presses the tension.

  According to the present invention, it is possible to realize a backrest that provides a comfortable sitting comfort with a simple configuration.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 5, the chair according to the present embodiment includes a leg body 4, a base body 2 supported by the leg body 4, a seat 3 disposed on the base body 2, and a horizontal support shaft 16. The backrest 1 pivotally attached to the base 2 is provided, and a synchro-rocking operation in which the seat 3 and the backrest 1 tilt in conjunction with each other is possible.

  More specifically, the leg 4 includes a leg blade 41 on which a plurality of casters are mounted, and a leg column 42 that rises substantially vertically from the center of the leg blade 41. The leg blade 41, the leg column 42, The leg struts 42 can be projected and retracted vertically by extending and contracting a gas spring (not shown) interposed therebetween.

  The base body 2 is fixed to the upper end of the leg column 42, and the height positions of the seat 3 and the backrest 1 can be adjusted through the operation of projecting and retracting the leg column 42. An elastic biasing mechanism (not shown) for biasing the backrest 1 rotating around the horizontal support shaft 16 forward, a fixing mechanism (not shown) for fixing the locking angle of the backrest 1, etc. Built in. The elastic urging mechanism elastically urges the back frame 11 by mounting a coil spring or a gas spring. For example, the fixing mechanism selectively locks the locking angle by engaging a claw with any of a plurality of recesses provided on the back frame 11 side, but the push spring gas spring is used as the elastic biasing mechanism. When the valve is used, the valve can be driven to prohibit the expansion and contraction of the gas spring.

  The seat 3 is formed by mounting a cushion body 32 constituting a seat surface on a seat receiver 31. The cushion body 32 has, for example, a two-layer structure in which a urethane cushion material is superposed on a double raschel mesh made of synthetic fiber, and the lower layer mesh absorbs an impact while ensuring an appropriate elasticity, and the upper layer urethane cushion material. Maintains the stability of the figure. The front end portion of the seat 3 is supported so as to be slidable in the front-rear direction with respect to the base body 2, and the rear end portion of the seat 3 is connected to the lower frame portion 13 of the back frame 11 below via a hinge (not shown). Are attached.

  The backrest 1 is obtained by stretching a tension member 12 constituting the backrest surface S on the front surface of the back frame 11. The back frame 11 includes a lower frame portion 13 connected to the base body 2 so as to be rotatable about a horizontal support shaft 16, and an upper frame portion 14 connected to the upper end of the lower frame portion 13 via a hinge 17. And a reaction force frame portion 15 for supporting the upper frame portion 14 from the rear.

  The lower frame portion 13 is formed by connecting left and right lower frame elements 131 a and 131 b that are spaced apart in the width direction to each other by a rigid horizontal member 132. Both the lower frame elements 131a and 131b and the rigid horizontal member 132 are, for example, metal rigid bodies. The lower frame elements 131a and 131b have a substantially L-shape that extends rearward from the front end where the horizontal support shaft 16 is located in side view and is bent upward at the rear end.

  The upper frame portion 14 is formed by connecting left and right upper frame elements 141 a and 141 b that are spaced apart in the width direction to each other by an elastic horizontal member 142. The upper frame elements 141a and 141b are, for example, metal rigid bodies, while the elastic horizontal member 142 is, for example, an elastic body made of resin. The upper frame elements 141a and 141b have an arcuate shape that extends upward from the lower end where the side view hinge 17 is located while gently curving so as to be somewhat recessed backward, and bulges forward again in the vicinity of the upper end.

  The reaction force frame portion 15 includes the same number of reaction force frame elements 151a and 151b that support the upper frame elements 141a and 141b. One end portions of the reaction force frame elements 151a and 151b are connected to the back surfaces of the upper frame elements 141a and 141b, and the other end portions are connected to the downward surfaces of the lower frame elements 131a and 131b. However, the other end portions of the reaction force frame elements 151a and 151b are not prevented from being fixed to the base 2 that supports the seat 3 or the backrest 1. The reaction force frame elements 151a and 151b are made of an elastic body made of a resin having the same quality as the elastic horizontal member 142, for example. In the present embodiment, the reaction force frame elements 151a and 151b are frame-shaped resin springs that extend along the lower frame elements 131a and 131b and the upper frame elements 141a and 141b in a side view to form a substantially L shape. The width dimension is the same as or slightly narrower than the frame elements 131a, 131b, 141a, 141b, and the front and rear or top and bottom thicknesses are thinner than the frame elements 131a, 131b, 141a, 141b (additionally, the frame elements 131a, 131b, 131 b, 141 a, 141 b, and the thickness is gradually reduced as the distance from the end joined is increased. Thereby, the appearance as if the reaction force frame elements 151a and 151b are part of the back frame 11 branched from the frame elements 131a, 131b, 141a and 141b is formed.

  The periphery of the hinge 17 that pivotally attaches the lower frame elements 131a and 131b and the upper frame elements 141a and 141b to each other, specifically, from the rear end to the vicinity of the upper end of the lower frame elements 131a and 131b and the lower ends of the upper frame elements 141a and 141b. In the vicinity, a curved shape is formed such that the front surface of the side view frame bulges forward. As already described, also in the vicinity of the upper ends of the upper frame elements 141a and 141b, a curved shape is formed such that the front surface of the side view frame bulges forward. Accordingly, the tension member 12 is stretched so as to be bridged over the curved portions of the lower frame elements 131a and 131b and the upper frame elements 141a and 141b.

  The tension member 12 is mainly composed of a tension fabric 121 rich in stretchability. The upholstery 121 is made of, for example, a double raschel mesh made of synthetic fiber and an elastic yarn such as an elastomer yarn, and has both strength and cushioning properties. The upholstery 121 is formed by stitching the front and back fabrics of a mesh fabric that can be stretched and deformed three-dimensionally by double raschel knitting, and the appearance (color, pattern, gloss, etc.) on the front and back sides is different. The upper side and the left and right sides of the upholstery 121 are retained by the backup material 122. As shown in FIG. 10, in the backup material 122, the vertical frames 122a and 122b and the horizontal frame 122c connecting both the vertical frames 122a and 122b form a three-sided frame shape or a four-sided frame shape when viewed from the front, A thin plate body made of, for example, resin that can be bent and deformed in the front-rear direction, in particular, the left and right sides of the upholstery 121 are prevented from bending inward, and the upholstery 121 is kept stretched. The backup material 122 in the illustrated example has a substantially three-sided frame shape in front view in which the upper ends of the left and right vertical frames 122a and 122b are connected to each other via a horizontal frame 122c.

  The upper end portion of the backup material 122 is supported on the upper end portion of the back frame 11. In the present embodiment, through holes 122x are made in the upper ends of the vertical frames 122a and 122b of the backup material 122, and fastening devices 191 such as screws or pins are inserted into the through holes 122x, and the upper ends of the upper frame elements 141a and 141b. It is fixed to the part. On the other hand, the lower end portion of the backup material 122 is supported by the lower end portion of the back frame 11. In the present embodiment, long holes 122y extending in the vertical direction are formed in the lower ends of the vertical frames 122a and 122b of the backup material 122 and portions slightly below the middle, and fasteners such as screws or pins are provided in the long holes 122y. 192 is inserted and fixed to the lower end and the upper end of the lower frame elements 131a and 131b. The upper end portion of the backup material 122 is fixed to the upper frame elements 141a and 141b, but the lower end portion can slide up and down with respect to the lower frame elements 131a and 131b.

  Between the upper end portion of the back frame 11 and the vicinity of the hinge 17 is curved so as to be recessed rearward in a side view, and an intermediate portion of the vertical frames 122a and 122b is provided with a room where it can bend and deform backward. The elastic horizontal member 142 forming the upper side of the back frame 11 is also curved so as to be recessed rearward in plan view, and provides a room for the horizontal frame 122c to bend and deform backward.

  The upper end portion of the tension member 12 is mounted and supported on the left and right upper frame elements 141a and 141b, and the lower end portion is mounted and supported on the left and right lower frame elements 131a and 131b. When the upholstery 121 is installed on the back frame 11, the upper edge of the upholstery 121 is attached to the horizontal frame 122 c of the backup material 122, and the left and right side edges of the upholstery 121 are attached to the vertical frames 122 a and 122 b of the backup material 122. . Specifically, as shown in FIGS. 10 and 11, the groove 122z is formed on the peripheral end surface of the backup material 122, that is, the upper end surface of the horizontal frame 122c and the outer end surfaces of the left and right vertical frames 122a and 122b, respectively. The three edges of the upholstery 121 are fitted into the groove 122z and locked. For example, a resin edge member 121x having a long thin plate shape is attached to the three edge portions of the upholstery 121 in advance (by sewing, adhesion, welding, or the like). Further, the lower edge of the upholstery 121 is fixed to a predetermined portion of the lower frame portion 13. In the illustrated example, a bracket 121 y is attached to the lower edge of the upholstery 121, and the bracket 121 y is fixed to the rigid horizontal member 132 of the lower frame portion 13 using a bolt 193 or the like.

  Generally speaking, a backup material 122 is disposed on the front surface of the back frame 11, and a tension fabric 121 is disposed on the front surface of the backup material 122. At this time, the back-up material 122 acts as a leaf spring and presses the upholstery 121 forward to project it. The upper end and the lower end of the upholstery 121 are fixed to the upper and lower ends of the back frame 11, respectively. The upper end of the upholstery 121 is indirectly fixed to the upper frame elements 141a and 141b via the backup material 122, and the lower end of the upholstery 121 is fixed directly to the lower frame elements 131a and 131b without using the backup material 122. Has been.

  Incidentally, the lumbar support belt 18 can be bridged over the tension member 12 and at a height position corresponding to the waist of the seated person. Even when the seated person leans on the backrest surface S, the portion over which the lumbar support belt 18 is bridged does not sink backward beyond the depth corresponding to the length of the lumbar support belt 18. Both ends of the lumbar support belt 18 are attached to and supported by the left and right vertical frames 122a and 122b of the backup material 122 via an appropriate support structure (not shown). However, it does not prevent the both ends of the lumbar support belt 18 from being supported by the left and right upper frame elements 141a and 141b or the lower frame elements 131a and 131b.

  The chair of the present embodiment can perform a synchro-rocking operation in which the seat 3 and the backrest 1 are tilted in conjunction with each other. As shown in FIG. 6, in the synchro-rocking operation, the backrest 1 tilts back and forth as the entire back frame 11 rotates around the horizontal support shaft 16. At the same time, the rear end of the seat 3 swings up and down in conjunction with the back frame 11, and the front end of the seat 3 slides back and forth.

  In addition, the chair of the present embodiment follows the movement of turning back, stretching hands, twisting the body while the seated person is seated, only the upper left half of the backrest surface S, Alternatively, it is possible to move only the right half backward. In the upper frame portion 14 that supports the upper portion of the backrest surface S, the upper frame elements 141a and 141b that make a pair on the left and right sides move back and forth independently of each other. That is, the left upper frame element 141a is connected to the left lower frame element 131a via the hinge 17, and the right upper frame element 141b is connected to the right lower frame element 131b via the hinge 17, The frame elements 141a and 141b can be individually rotated.

  As shown in FIG. 7, when the upper frame elements 141a and 141b are tilted rearward around the hinge 17, the tension member 12 comes into contact with the curved portions of the lower frame elements 131a and 131b and the upper frame elements 141a and 141b. As the area gradually increases and the distance between the upper end and the lower end of the back frame 11 increases, the upholstery 121 extends vertically while increasing the tension. At the same time, the lower end portion of the backup material 122 is relatively displaced in the vertical direction with respect to the lower frame elements 131a and 131b within the dimension range of the long hole 122y. At the same time, the reaction force frame elements 151a and 151b are deformed so as to widen the angle to accumulate the reaction force, and elastically bias the front frame elements 141a and 141b back to the original positions, that is, forward.

  If one of the upper frame elements 141a (141b) is displaced in the front-rear direction relative to the other upper frame element 141b (141a), as shown in FIGS. The shape of can be changed three-dimensionally. In this operation, the lower frame portion 13 is not necessarily driven. Further, since the lower frame elements 131a and 131b that make a pair on the left and right are rigidly connected via the rigid horizontal member 132, the lower frame elements 131a and 131b always move integrally. Therefore, the lower part of the backrest surface S and the part below the seated person's lower back always maintain a constant shape.

  When one of the upper frame elements 141a and 141b moves back and forth relative to the other as the seated person moves, the distance between the left and right upper frame elements 141a and 141b increases. At that time, the elastic horizontal member 142 is elastically deformed to cope with an increase in the separation distance between the upper frame elements 141a and 141b. The elastic horizontal member 142 of the present embodiment connects the upper end portions of the upper frame elements 141a and 141b to each other and is assembled in a curved shape that is recessed backward in plan view. The front and rear thicknesses of the elastic horizontal member 142 are gradually reduced from the both ends connected to the upper frame elements 141a and 141b toward the center in the width direction, and the middle portion is relatively smaller than the both ends. It is easy to deform. This is for avoiding the concentration of the load at the connection point between the upper frame elements 141a and 141b and the elastic horizontal member 142.

  Here, it supplements regarding the connection aspect of upper frame element 141a, 141b and the elastic horizontal member 142. FIG. The upper frame elements 141a and 141b have joint ends protruding at the upper ends that are close to each other at the upper ends, and both ends of the elastic horizontal member 142 are connected to the joint ends. As shown in FIG. 12, one of the joint end portions of the upper frame elements 141a and 141b and both end portions of the elastic horizontal member 142 facing each other (in the illustrated example, the upper frame elements 141a and 141b side) has a convex portion. 141x protrudes, and the other side (in the illustrated example, the elastic horizontal member 142 side) is formed with a recess 142x to construct a fitting structure in which the projection 141x is fitted into the recess 142x. Then, the bolts 194 are screwed in from the direction intersecting with the fitting direction, and the peripheral wall of the convex portion 141x and the concave portion 142x is screwed and tightened, so that the joint end portions of the upper frame elements 141a and 141b and the elastic horizontal mount The end of the material 142 is coupled. In the illustrated example, a bolt 194 is screwed in from the front, and the bolt 194 is substantially concealed by a tension member 12 that is stretched on the back frame 11.

  When one of the upper frame elements 141a and 141b moves back and forth relatively with respect to the other, the elastic horizontal member 142 is deformed so as to reduce the curvature and extends the distance between both ends.

  In addition, the load of the seated person received by the backrest surface S acts on the upper frame elements 141a and 141b via the tension member 12, and tries to cause the upper frame elements 141a and 141b to fall inwardly on the hinge 17. Burdening. For the purpose of canceling and reducing such a load, the elastic horizontal member 142 is assembled in a state of exerting an initial elastic force that separates the upper frame elements 141a and 141b in the width direction.

  However, the upper frame elements 141a and 141b on both the left and right sides can be tilted together. In that case, for example, stretching that greatly warps the back of the seated person is possible.

  According to the present embodiment, the separation distance between the upper end portion and the lower end portion of the back frame 11 is variable through the rotation of the upper frame portion 14 around the hinge 17, and the stretchable stretch 121 is provided between the upper and lower end portions. In the chair having the backrest 1 that forms the backrest surface S across the backrest surface S, a back-up material 122 is provided on the edge of the upholstery 121 to keep the upholstery 121 in a stretched state. The upper end of the back frame 11 is supported by the upper end of the back frame 11 (or the upper frame elements 141a and 141b), and the lower end of the backup material 122 is supported by the lower end of the back frame 11 (or the lower frame elements 131a and 131b). In addition, since at least one of the upper end portion or the lower end portion of the backup material 122 can be slid vertically with respect to the upper end portion or the lower end portion of the back frame 11, Well without Wakata the up member 122 above and below the piece, may aim to simplify the structure. And the problem that the overlap part of the backup material in the existing chair gives a foreign object feeling to a seated person's back can be solved effectively.

  The backup material 122 can be bent and deformed in the front-rear direction in which the vertical frames 122a and 122b paired on the left and right sides and the horizontal frame 122c connecting the vertical frames 122a and 122b form a substantially three-sided frame shape or a four-sided frame shape when viewed from the front. Since it is a thin plate body and the central portion of the backup material 122 is hollow, it is possible to provide a soft sitting comfort without preventing the upholstery 121 receiving the load of the seated person from being deformed so as to sink backward.

  When the upper part of the backrest 1 is tilted backward and the seated person's back is warped, the seated person's buttocks is naturally separated from the backrest surface S in a natural posture. Accordingly, the upper end portion of the backup material 122 is fixed to the upper end portion of the back frame 11 and the lower end portion of the backup material 122 is supported by the lower end portion of the back frame 11 so as to be slidable up and down. The side edges are held in the vertical frames 122a and 122b, and the upper edge is held in the horizontal frame 122c, so that an uncomfortable feeling is not given to the seated person.

  The left and right vertical frames 122a and 122b of the backup material 122 support both sides of the lumbar support belt 18, and the lumbar support belt 18 is bridged when the seated person leans on the backrest surface S. The part does not sink backward beyond the depth corresponding to the length of the lumbar support belt 18.

  A concave groove 122z is formed on the end surface of the backup material 122, and the edge of the tension fabric 121 is fitted into the concave groove 122z to be locked, whereby the mounting structure of the tension material 121 and the backup material 122 is simplified. In addition, the upholstery 121 can be appropriately detached from the chair, which contributes to the improvement of maintainability such as replacement of the upholstery 121 and washing.

  The back frame 11 is vertically divided into an upper frame portion 14 and a lower frame portion 13, and the upper frame portion 14 is rotatably connected to the lower frame portion 13 via a hinge 17. A rocking operation that tilts the entire body integrally and a backrest surface deformation operation that tilts only the upper portion of the backrest surface S can be selectively performed. Of course, it is also possible to simultaneously cause the rocking motion and the backrest deformation motion, and the seated person can take various postures while sitting.

  The present invention is not limited to the embodiment described in detail above. In particular, it does not prevent the upper end portion of the backup material from being vertically slidable with respect to the upper end portion of the back frame. For example, a long hole extending in the vertical direction is formed in the upper end portion of the backup material, and a fastening tool such as a screw or a pin is inserted into the long hole to be fixed to the upper end portion (or upper frame element) of the back frame. Thus, the upper end portion of the backup material is supported so as to be slidable relative to each other. In this case, it is also conceivable to directly fix the upper end of the tension fabric to the upper end of the back frame without using a backup material. Further, the lower end portion of the backup material may be fixed to the lower end portion (or the lower frame element) of the back frame or slidable up and down with respect to the lower end portion of the back frame.

  As illustrated in FIG. 13, the upper frame elements 141a and 141b may be pivotally connected to the base 2 without pivoting to the lower frame elements 131a and 131b.

  The upholstery constituting the backrest surface is not limited to the double raschel mesh. For example, an elastomer resin material may be used as long as it is a flexible face material.

  Other specific configurations, processing procedures, and the like can be variously modified without departing from the spirit of the present invention.

The perspective view which looked at the chair of one embodiment of the present invention from the front side. The perspective view which looked at the chair from the back side. The side view of the chair. Rear view of the chair The top view of the chair. The side view which shows the synchro-rocking operation | movement of the chair. The side view which shows the state which displaced the upper frame element of the chair back. The perspective view which shows the backrest surface deformation | transformation operation | movement of a figure chair. The top view which shows the backrest surface deformation | transformation operation | movement of the chair. The principal part disassembled perspective view which shows the tension place and back-up material of the chair. The principal part plane sectional view which shows the aspect of the mounting to the backup material of the tension place of the chair. The principal part plane sectional view which shows the aspect of a connection with the upper frame element of the same chair, and an elastic horizontal member. The side view which shows the chair which concerns on one modification of this invention.

Explanation of symbols

S ... Backrest 1 ... Backrest 11 ... Back frame 121 ... Upholstery 122 ... Backup material 122a, 122b ... Vertical frame 122c ... Horizontal frame 122z ... Groove 131 ... Lower frame portion 141 ... Upper frame portion 17 ... Hinge 18 ... Lumber support belt

Claims (6)

The separation distance between the upper and lower ends of the back frame is variable through tilting of the upper frame with respect to the lower frame of the back frame. A chair comprising a backrest comprising:
Resin back-up material is provided to keep the upholstery at the edge of the upholstery , and this back-up material is interposed between the back frame and the upholstery to project the upholstery forward. ,
The upper end portion of the upholstery and the backup material to the upper end of the back frame, is supported respectively lower portion of the upholstery and the backup material to the lower end of the back frame,
In addition , the tension material and the backup material are fixed to the back frame on one of the upper end portion and the lower end portion of the back frame, and on the other hand, the backup material is fixed to the back frame while the tension material is fixed to the back frame. A chair that is slidable up and down. 2. The backup material is a thin plate body that is deformable by bending in the front-rear direction, with the vertical frame paired on the left and right sides and the horizontal frame connecting the vertical frames forming a substantially three-sided frame shape or a four-sided frame shape when viewed from the front. The listed chair. While fixing the upper end of the backup material to the upper end of the back frame, the lower end of the backup material is supported by the lower end of the back frame so as to be slidable up and down,
The chair according to claim 2, wherein left and right side edges of the upholstery are held in a vertical frame and an upper edge is held in a horizontal frame. The chair according to claim 2 or 3, wherein both sides of the lumbar support belt are supported on the left and right vertical frames of the backup material. The chair according to claim 1, 2, 3 or 4, wherein a concave groove is formed on an end surface of the backup material, and an edge of the upholstery is fitted into the concave groove and locked. The chair according to claim 1, 2, 3, 4 or 5 , wherein the backup material is a thin plate body that acts as a leaf spring that presses the tension .

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