JP2012135455A - Chair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chair which can be comfortably seated without requiring high technical capabilities or labor hours for manufacturing.SOLUTION: A middle part A6 in the chair A1 is provided with: a plurality of vertical crosspiece areas A61 which have wavy shapes, continuously projecting and sinking in a plate thickness direction with a constant cycle in a longitudinal direction; and a plurality of horizontal crosspiece areas A62 constituted by continuing the plurality of vertical crosspiece areas A61, each other. The phase of the continuous wavy shape of the adjacent vertical crosspiece areas A61 is shifted. The chair has a cross-section shape which can be deformed in a direction in which the cycle for projecting and sinking in the plate thickness direction is increased when the load is applied to the plate material A31 in the thickness direction.

Description

  The present invention relates to a chair suitably used for school or office use.

  Conventionally, since this type of chair is often seated for a relatively long time, the seating comfort has been emphasized and various improvements have been made. Recently, as a chair that is very comfortable to sit, a mesh-type chair has been developed in which a load of a seated person is elastically received by a mesh stretched on a frame member (see, for example, Patent Document 1). .

  However, in such a mesh-type chair, it is necessary to stretch the mesh on the frame member with an appropriate tension, the support structure is complicated, and a high technical force is required for the stretching operation.

JP 2007-202591 A

The present invention has been made paying attention to the above-described circumstances, and an object thereof is to provide a comfortable chair without requiring high technical skill and labor for manufacturing.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the chair according to the present invention is a chair in which a seat body and a back plate are supported by a chair body, and at least one of the seat plate and the back plate is supported by the chair body, A plurality of vertical beam regions having a wavy shape in which the intermediate portion protrudes and sinks continuously in the plate thickness direction at a constant period in the front-rear direction; and a plate member having an intermediate portion located on the inner side. A plurality of horizontal beam regions formed by connecting a plurality of vertical beam regions, and the adjacent vertical beam regions have a continuous wave-like phase shifted from each other, and a load is applied to the plate in the thickness direction. It is characterized in that it has a cross-sectional shape that can be deformed in a direction in which the period of protrusion and depression in the plate thickness direction becomes longer.

  If this is the case, the load of the seated person is elastically received by the plate material, so it requires higher technical skills and labor than the conventional frame material with a mesh stretched. Instead, it becomes a comfortable chair. That is, each of the vertical beam members is deformed in a direction in which the period in which the vertical beam member protrudes and sinks in the plate thickness direction while being bent in the thickness direction is increased to receive a seated person's load, and the horizontal beam members that connect the vertical beam members are The movement of the crosspiece is made appropriate. Therefore, the plate material is bent and deformed according to the load of the seated person, and the seating comfort is improved.

  In order to improve air permeability, it is desirable that an opening be formed between the vertical beam region and the horizontal beam region.

  Also, in order to effectively avoid excessive deformation due to twisting around the opening and concentration of load by effectively improving the strength of the opening edge, reinforcing ribs are erected on the back side from the edge of the opening. It is desirable to have it.

  In addition, in order to effectively improve the torsional rigidity of the entire intermediate portion, a reinforcing rib may be erected on the back side from the edge of the vertical beam region.

  And in order to reliably receive the load from the seated person and make it comfortable to sit or drown, the virtual surface connecting the protruding points protruding at a constant cycle in the vertical beam region has a flat plate shape As described above, it is preferable that the intermediate portion is configured in a substantially flat plate shape.

  On the other hand, in order to realize a comfortable sitting comfort while forming a shape according to the sitting posture of the seated person, a virtual surface connecting the protruding points protruding at a constant cycle in the vertical rail region has a curved surface shape. As a result, it is preferable that the intermediate portion has a substantially curved plate shape.

Since the present invention is configured as described above, it is possible to provide a comfortable chair without requiring high technical skill and labor for manufacturing.

1 is an overall perspective view showing a first embodiment of the present invention. The whole perspective view which shows the back side of the embodiment. The top view which shows the seat plate of the embodiment. The perspective view which shows the seat plate of the embodiment. The perspective view which shows the principal part of the same seat board. The other perspective view. II sectional view taken on the line of FIG. II-II sectional view taken on the line. III-III sectional view taken on the line. IV-IV sectional view. The VV sectional view taken on the line. The whole perspective view showing a 2nd embodiment of the present invention. The whole perspective view which shows the back side of the embodiment. The sectional side view of the embodiment. The disassembled perspective view which shows the principal part of 3rd Embodiment of this invention. The side view which shows the chair of the embodiment typically. The whole perspective view showing a 4th embodiment of the present invention.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the present invention is applied to a chair A1 that can be stacked in the vertical direction. This chair A1 is formed by supporting a seat plate A3 and a back plate A4 on a chair body A2.

  As shown in FIGS. 1 and 2, the chair main body A2 includes left and right bases A21 placed on the floor via the grounding body A211, and left and right front legs A22 extending upward from the front ends of the bases A21. The left and right rear legs A23 extending upward from the rear end of each base A21, the rear frame A24 installed between the upper ends of the rear legs A23, the vicinity of both ends of the rear frame A24, and the front legs A22 The left and right side frames A25 connecting the upper ends, the front frame A26 installed between the front end vicinity portions of these side frames A25, and the left and right back frames A27 extending upward from the upper ends of the rear legs A23. Become. The base A21, the front leg A22, the rear leg A23, the side frame A25, and the back frame A27 are integrally formed by bending a common metal wire, and act on the seat plate A3 and the back plate A4. It is strong enough to receive a load. The seat plate A3 is supported by the left and right side frames A25. Further, in the present embodiment, with the seat plate A3 attached to the chair body A2, a gap that allows the seat plate A3 to bend downward between the front frame A26 and the seat plate A3. Is set to be formed.

  As shown in FIGS. 1 to 4, the seat plate A3 includes a plate material A31 and a mounting body A32 protruding from the lower surface of the plate material A31. In this embodiment, the seat plate A3 is integrally formed with resin. ing.

  As shown in FIGS. 1 to 11, the plate material A31 has a peripheral portion A5 supported by the left and right side frames A25 of the chair body A2, and an intermediate portion A6 located inside the peripheral portion A5. The intermediate portion A6, which is a specific part of the intermediate portion A6, in this embodiment, has a structure including a vertical beam region A61 and a horizontal beam region A62 to be described later.

  As shown in FIGS. 1 to 4, the peripheral edge A5 includes a side edge portion A51 located on both the left and right sides of the intermediate portion A6, a rear edge portion A52 located on the rear side of the intermediate portion A6, and an intermediate portion A6. And a front edge portion A53 located on the front side. The side edge portion A51 is curved downward so as to wrap around the side frame A25. The rear edge portion A52 is curved toward the rear upper side. The front edge portion A53 is curved toward the front lower side.

  Here, the chair according to the present embodiment includes a plurality of vertical beam regions A61 having a wavy shape in which the intermediate portion A6 continuously protrudes and sinks in the thickness direction in the front-rear direction and the plurality of vertical beam regions. A plurality of horizontal beam regions A62 formed by connecting A61s to each other, and the adjacent vertical beam regions A61 are shifted from each other in a continuous wave-like phase, and a load is applied to the plate material A31 in the thickness direction. It has a cross-sectional shape that can be deformed in a direction in which the period of protrusion and depression in the plate thickness direction becomes longer. Hereinafter, the configuration of the intermediate portion A61 will be specifically described.

  As shown in FIGS. 1 to 11, the intermediate portion A6 is provided with a plurality of vertical beam regions A61 adjacent to each other and adjacent to the vertical beam regions A61. A basic structure is formed in which the slabs are smoothly connected by the horizontal beam region A62. In other words, the horizontal beam region A62 is also formed to intersect / continuously with the vertical beam region A61 so that the adjacent horizontal beam regions A62 are smoothly connected to each other by the vertical beam region A61. I can say that. That is, the intermediate portion A61 has a wave shape that protrudes and sinks in a plate thickness direction that is continuous from the two directions intersecting each other in the plate surface direction, that is, the surface direction of the plate material A31, that is, the front-rear direction and the width direction, at a constant cycle. When the plate material is loaded in the thickness direction, it has a cross-sectional shape that can be deformed so that the period of protrusion and depression in the plate thickness direction becomes longer. More specifically, each vertical beam region A61 is arranged so as to connect two portions of the peripheral edge portion A5 facing each other, and is elastic with a longer path than connecting the two peripheral edge portions A5 with a straight line. It has a shape that can be deformably connected. As shown in FIG. 5 to FIG. 11, each vertical beam region A61 has a wave shape projecting and sinking at a constant cycle in the plate thickness direction, and adjacent vertical beam regions A61 are shifted in phase by a continuous wave-like 180 °. The side edges of the adjacent vertical beam areas A61 are connected via the horizontal beam area. Moreover, as shown in FIGS. 4 and 5, the vertical beam region A61 is configured such that a virtual surface (not shown) that connects the protruding points A61p protruding at a constant period in the vertical beam region A61 has a flat plate shape. Yes. Thereby, the middle part A6 has a substantially flat plate shape. In addition, each vertical beam area A61 is arranged through an opening A64 so as not to overlap with the adjacent vertical beam area A61 in the line of sight from the direction orthogonal to the plate material A31. Side edges of the region A61 are integrated in the crosspiece region. In other words, the vertical beam areas A61 are connected to each other at positions in the thickness direction that are substantially flush with the peripheral edge A5. That is, these openings A64 are intermittently formed between the vertical beam region A61 and the horizontal beam region A62. Each of the vertical beam regions A61 is arranged in parallel with a linear shape as viewed from a direction perpendicular to the plate material A31. As shown in FIGS. 2 and 5 to 11, on the back surface side of the plate material A6, vertical beam ribs A63a are erected from the edge of the vertical beam region A61 to the back surface side. Since the vertical beam rib A63a has the same protruding dimension, the protruding end is wavy like the vertical beam region A61. Further, in the present embodiment, the opening edge rib A63b is also erected from the front and rear edge portions of the opening so as to be continuous with the vertical rail A63a. The opening edge rib A63b also has the same projecting dimension as the vertical rail A63a. The ribs A63a and A63b are erected in a substantially cylindrical shape between the front and rear of the opening by the vertical cross rib A63a and the opening edge A63b.

  As shown in FIGS. 1 and 2, the attachment body A32 is integrally provided on the lower surface of the side edge portion A51. The attachment body A32 has a groove A321 having a C-shaped cross section, and the seat plate A3 is attached to the chair body A2 by engaging the groove A321 with the side frame A25.

  As shown in FIGS. 1 and 2, the back plate A4 is provided with mounting holes A41 that open downward on both side edges. By fitting the mounting holes A41 into the back frame A27, the back plate A4 is provided. Is supported by the chair body A2.

  As described above, the chair A1 according to this embodiment is configured by supporting the seat plate A3 and the back plate A4 on the chair body A2, and the seat plate A3 includes a plurality of seat plates that can be bent in the thickness direction. By having the vertical beam region A61 and the horizontal beam region A62, all or the main part of the seat plate A3 can be manufactured by integral molding with a resin, and the high technical force as in the case where a mesh is stretched on the frame member, There is no need for trouble.

  That is, since each said vertical beam area | region A61 and horizontal beam area | region A62 mainly receives a seated person's load, bending in the thickness direction, the intermediate part A6 can be bent appropriately. Further, by setting the wave undulations and period in the vertical beam region A61 and the horizontal beam region A62 as appropriate, it is possible to make a seat plate A3 having various characteristics and comfortable to sit on. Therefore, it is possible to easily design the seat plate A3 having appropriate elasticity according to the load. In particular, in the above embodiment, the plate material A31 having the peripheral edge portion A5 and the intermediate portion A6 and the mounting body A32 are integrally formed of resin, so that the number of parts can be reduced, and the frame material can be used. Compared with the case where the mesh is stretched, the number of steps required for assembly can be greatly reduced. Further, since the plate material A31 is integrally formed of a resin, the strength is higher than that of the mesh type, and there is little possibility of tearing, cutting, or sliding. That is, since the mesh type is knitted or woven with a thin thread, there is a possibility that the whole may fray, but the plate material A31 of this embodiment is partially damaged as described above. However, it is possible to prevent the damage from spreading to the whole as in the mesh type.

  Moreover, since the opening A64 is three-dimensionally formed between the vertical beam region A61 and the horizontal beam region A62, the air permeability is good.

  Furthermore, in order to effectively avoid excessive deformation due to twisting around the opening A64 and concentration of load by effectively improving the strength of the edge of the opening A64, in this embodiment, the edge from the edge of the opening A64 to the back side. Opening edge ribs A63b as reinforcing ribs are provided upright.

  In addition, in the present embodiment, in order to effectively improve the torsional rigidity of the entire intermediate portion A6, the vertical beam rib A63a as a reinforcing rib is erected on the back side also from the left and right edge portions of the vertical beam region A61.

  In particular, in the present embodiment, a virtual surface connecting the protruding points A61p protruding at a constant period in the vertical beam region A61 is a flat plate in order to reliably receive the load from the seated person and to have a comfortable sitting or a comfortable feeling. By forming the shape, the intermediate portion A6 is correctly formed into a flat plate shape.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the present invention is applied to a chair B1 that can be nested in the front-rear direction. This chair B1 is formed by supporting a seat plate B3 and a back plate B4 on a chair body B2.

  12 to 14, the chair body B2 includes left and right front legs B21 having casters B211 at the lower ends, left and right rear legs B22 having casters B221 at the lower ends, the upper ends of the rear legs B22, The left and right side frames B24 that connect the upper ends of the front legs B21, the front frame B25 that is laid between the vicinity of the front ends of these side frames B24, and the rear frame B23 that is laid between the vicinity of the rear ends of these side frames B24 And left and right support frames B26 having a base end portion B28 rotatably supported by the rear frame B23, and left and right back frames B27 extending upward from the upper end of the rear leg B22. The front leg B21 and the side frame B24 are integrally formed by bending a common metal pipe material, and the rear end of the side frame B24 is rigidly connected to the upper end of the rear leg B22 by welding or the like. The front leg B21, the rear leg B22, the side frame B24, the front frame B25, the rear frame B23, the support frame B26, and the back frame B27 are strong enough to receive a load acting on the seat plate B3 and the back plate B4. I have. The seat plate B3 is supported on the front end portion and the rear end portion of the support frame B26, and the use position (U) where the seat plate B3 is substantially horizontal and the seat plate B3 are substantially parallel to the back plate B4. It can be rotated between a flip-up position (not shown). A concave portion B291 is formed in the intermediate portion B29 of the support frame B26, and the concave portion B291 is engaged with the front frame B25 at the use position (U). The distance between the left and right front legs B21 is set smaller than the distance between the left and right rear legs B22, and can be nested with other chairs having the same structure with the seat plate B3 flipped up. It has become.

  As shown in FIGS. 12 to 14, the seat plate B3 includes a plate material B31 and front and rear mounting bodies B32 and B33 protruding from the lower surface of the plate material B31. In this embodiment, the seat plate B3 is made of resin. It is molded integrally.

  As shown in FIGS. 12 to 14, the plate member B31 has a peripheral portion B5 supported by the left and right support frames B26 of the chair body B2, and an intermediate portion B6 positioned inside the peripheral portion B5. The intermediate portion B6 is formed in one piece, and the specific portion of the intermediate portion B6, in this embodiment, the entire region of the intermediate portion B6 has a structure including the vertical beam region or the horizontal beam region.

  As shown in FIGS. 12 to 14, the peripheral edge B5 includes side edge portions B51 located on the left and right sides of the intermediate portion B6, a rear edge portion B52 located on the rear side of the intermediate portion B6, and an intermediate portion B6. And a front edge portion B53 located on the front side.

  The intermediate portion B6 has the same structure as that of the first embodiment, and in FIGS. 12 to 14, the detailed configuration is omitted and the intermediate portion B6 is shown by shading.

  As shown in FIGS. 13 and 14, the attachment bodies B32 and B33 are integrally provided on the lower surfaces of the front edge portion B53 and the rear edge portion B52. The front attachment body B32 is provided at the front edge portion B53 of the peripheral edge portion B5, and the rear attachment body B33 is provided at the rear edge portion B52 of the peripheral edge portion B5. The front end of the support frame B26 is slidably attached to the front mounting body B32 in the front-rear direction, and the rear end of the support frame B26 is detachably attached to the rear mounting body B33. Between the front and rear mounting bodies B32 and B33, the support frame B26 and the intermediate portion B6 of the seat plate B3 are separated by a gap B34, and the gap B34 causes the intermediate portion B6 in the thickness direction. Elastic deformation is allowed.

  As shown in FIGS. 12 to 14, the back plate B4 is provided with mounting holes B41 that open downward on both side edges. By fitting the mounting holes B41 into the back frame B27, the back plate B4 is provided. Is supported by the chair body B2.

  With such a configuration, it can be used in the same manner as a conventional nestable chair, and the seat plate can provide an effect similar to that of the first embodiment described above.

<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to FIGS. 15 and 16.

  In this embodiment, the present invention is applied to a chair C1 capable of synchro-rocking, in which the back plate C4 and the seat plate C3 are tilted synchronously at a constant ratio. The chair C1 is formed by supporting a seat plate C3 and a back plate C4 on a chair body C2.

  As shown in FIGS. 15 and 16, the chair body C2 includes a leg C21 having casters C211, a support base C22 supported by the upper end of the leg C21, and a back support supported to be tiltable by the support base C22. A collar C23, a seat support C24 disposed above the back support collar C23 and the support base C22, and a support mechanism C25 for supporting the seat support C24 on the support base C22 and the back support collar C23. . The seat receiver C24 includes an annular seat frame C26, mounting plates C27 provided at four corners of the seat frame C26, and a front connecting portion C28 and a rear connecting portion C29 for connecting to the support mechanism C25. It becomes. Then, a seat plate C3 is placed on the seat frame C26, and the seat plate C3 is supported in a fixed state on the seat frame C26 by a fastening tool such as a bolt (not shown) inserted through the mounting plate C27. . For example, as schematically shown in FIG. 16, the support mechanism C25 includes a front link element C251 having a free end structure for connecting the front connection portion C28 of the seat frame C26 to the front end portion of the support base C22, and a back support rod. And a seat mounting portion C252 which is provided at an intermediate portion of C23 and rotatably supports the rear connection portion C29 of the seat frame C26.

  As shown in FIGS. 15 and 16, the seat plate C3 includes a resin plate material C31 and a buried nut (not shown) provided on the lower surface side of the plate material C31, and is inserted through the mounting plate C27. A fixed fastener is screwed onto the embedded nut.

  As shown in FIGS. 15 and 16, the plate member C31 has a peripheral portion C5 supported by the seat frame C26 of the chair main body C2 and an intermediate portion C6 located inside the peripheral portion C5, and is integrally made of resin. The intermediate portion C6 is formed in a specific portion, and in this embodiment, the entire intermediate portion C6 has a structure including the vertical beam region or the horizontal beam region.

  As shown in FIGS. 15 and 16, the peripheral edge portion C5 includes a side edge portion C51 located on the left and right sides of the intermediate portion C6, a rear edge portion C52 located on the rear side of the intermediate portion C6, and the intermediate portion C6. And a front edge portion C53 located on the front side. The side edge portion C51 is curved downward so as to wrap around the seat frame C26. The rear edge portion C52 is curved rearward and upward. The front edge portion C53 is curved toward the front lower side.

  The intermediate part C6 has the same structure as that of the first embodiment. In FIG. 15, the detailed part is omitted, and the intermediate part C6 is indicated by shading.

  As shown in FIG. 16, the back plate C4 is attached to the upper end portion of the back support rod C23 so that the back plate C4 is supported by the chair body C2, and is integrated with the back support rod C23. It is designed to tilt.

  With such a configuration, the chair can be used in the same manner as a conventional chair that can be synchro-clocked, and the seat plate can achieve an effect according to the first embodiment described above. In particular, in this embodiment, as shown in FIG. 15, the front connecting portion C28 and the rear connecting portion C29 of the seat frame C24 are not structured to connect the left and right sides of the seat frame C26 under the range where the seat plate C3 bends. There is nothing that hinders downward deformation of the seat plate C3. Therefore, it is possible to set a large range in which the seat plate C3 can be deformed.

  In addition, the plate body is not limited to the one that constitutes the seat plate, but may be one that constitutes the back plate, or may be configured integrally with the back plate and the seat plate.

<Fourth embodiment>
That is, the chair D1 according to the present embodiment is obtained by supporting the back seat integrated plate D7 in which the seat plate D3 and the back plate D4 are integrated with the chair body D2.

  That is, as shown in the figure, the back seat integrated plate D7 is provided with a plate material D31 and a mounting body (not shown) protruding from the lower surface of the plate material D31. In this embodiment, the back seat integrated plate D7 is integrally formed of resin. Has been.

  As shown in FIG. 17, the plate material D31 has a peripheral portion D5 supported by the left and right side frames D25 of the chair body D2, and an intermediate portion D6 located inside the peripheral portion D5, and is integrally molded with resin. The specific portion of the intermediate portion D6, in this embodiment, the entire region of the intermediate portion D6 has a structure including the vertical beam region and the horizontal beam region.

  Thus, in the present embodiment, the curved surface is formed by imaginary surfaces connecting the protruding points protruding at a constant period in the vertical beam region, thereby realizing such a curved shape. .

  If it is such, the chair D1 which can implement | achieve comfortable sitting comfort will be implement | achieved, making the shape according to the seating posture of a seated person.

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

  The vertical beam region or the horizontal beam region is not limited to the wave shape as described in the above embodiment. Even if it is wavy, it can be variously changed by shifting the phase by 30 ° or 60 °.

  Further, in the embodiment described above, the case where each belt-like member is wave-shaped and has a constant amplitude and cycle has been described. However, a vertical beam region or a horizontal beam region with different amplitudes and cycles is described. It may be a combination.

  The seat plate may be one in which the upper surface of the plate material is covered with a stretch fabric, or further, a cushion interposed between the stretch fabric and the plate material.

  Further, the material of the plate material is not limited to the resin for molding the chair shell and the like, and an elastomer may be used.

  In the embodiment described above, the entire intermediate portion has a structure provided with the vertical beam region or the horizontal beam region. However, the present invention is not limited to such a structure, and a partial region of the intermediate portion is formed. Only the vertical beam region or the horizontal beam region may be provided. As an example, it is conceivable that the vertical beam region or the horizontal beam region is provided in a plurality of regions in the middle part.

  Of course, the mounting body of the seat plate is not limited to that of the illustrated embodiment, but may be one in which a separate mounting body is attached to the plate material in addition to the one provided integrally with the plate material. .

  The front frame of the first embodiment has a gap between the lower surface of the intermediate portion and the upper surface of the front frame when the intermediate portion is bent in the thickness direction. The lower surface of the part may be in contact with the upper surface of the front frame to limit the downward bending range of the intermediate part.

  In the support frame of the second embodiment, when the intermediate portion is bent in the thickness direction, a gap is still interposed between the lower surface of the intermediate portion and the upper surface of the support frame. The lower surface of the part may be in contact with the upper surface of the support frame to limit the downward bending range of the intermediate part.

  The support mechanism of the third embodiment is such that the front end side of the seat frame is supported by the support base via the front link element, and the rear end side of the seat frame is pivotally supported by the seat mounting portion of the back support rod. However, the present invention is not limited to this, and any suitable one can be used as long as the back plate and the seat plate can be synchronized and tilted at a constant ratio.

  In addition, various changes may be made without departing from the spirit of the present invention.

  The present invention can be used as a chair suitably used for school or office work.

A1, B1, C1, D1 ... Chair A2, B2, C2, D2 ... Chair body A3, B3, C3 ... Seat plate A31, B31, C31, D31 ... Plate material A4, B4, C4 ... Back plate A5, B5, C5, D5 ... Peripheral part A6, B6, C6, D6 ... Intermediate part A61 ... Vertical beam region A61p ... Projection point A62 ... Horizontal beam region A63a ... Reinforcement rib (vertical beam rib)
A63b: Reinforcement rib (opening edge rib)
A64 ... Opening

Claims (6)

A chair having a seat body and a back plate supported on a chair body,
At least one of the seat plate and the back plate is provided with a plate material having a peripheral portion supported by the chair body and an intermediate portion located inside the peripheral portion,
A plurality of vertical beam regions having a wavy shape in which the intermediate portion continuously protrudes and sinks in the plate thickness direction at a constant period in the front-rear direction; and a plurality of horizontal beam regions formed by continuing the vertical beam regions. And the adjacent vertical beam regions are out of phase with each other, and when the plate material is loaded in the thickness direction, it can be deformed in a direction in which the period of protrusion and depression in the plate thickness direction becomes longer. A chair characterized by having a cross-sectional shape.   The chair according to claim 1, wherein an opening is formed between the vertical beam region and the horizontal beam region.   The chair according to claim 2, wherein a reinforcing rib is erected on the back side from the edge of the opening.   The chair according to claim 1 or 2, wherein a reinforcing rib is erected from the edge of the vertical beam region to the back surface side.   The chair according to claim 1, 2, 3 or 4, wherein an imaginary surface connecting protruding points protruding at a constant period in the vertical beam region has a flat plate shape.   The chair according to claim 1, 2, 3, or 4, wherein an imaginary surface connecting protruding points protruding at a constant period in the vertical beam region has a curved surface shape.

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