JP2009165663A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chair which realizes a flexural deformation condition having appropriate elasticity of a back shell in accordance with a load by adding different characteristics to each of the regions of the shell and does not make a sitter feel an incongruity as if the waist is unnaturally locally pushed out or can restrain a feeling of incongruity from being given to the sitter. <P>SOLUTION: The chair 1 comprises a backrest 7 having a back shell 71 made mainly of an elastic platelike body made from a resin, and a back supporting rod 6 supporting the backrest 7. The back shell 71 integrally has a back shell upper portion 71T forming a curved surface whose right and left side edge portions are projected forward from the width direction center and a lumbar supporting portion 71L and the back shell lower portion 71U forming a curved surface having a larger curvature than the back shell upper portion 71T. The back shell upper portion 71T and the back shell lower portion 71U are supported on the back supporting rod 6 so as to ensure that the lumbar supporting portion 71L is kept in a relatively forward projected shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, chairs that are suitably used in offices and the like have been known that include a backrest having a resin-made back shell that has a substantially plate shape and a back support rod that supports the back shell.

The back shell generally has a curved surface in which left and right side edges protrude forward from the center in the left-right width direction, and is generally configured to be elastically deformable according to a load. Then, when the seated person leans on the backrest, the lumbar support part that can support the seated person's waist part is supported by the back supporter so that the seated person's waist part can be supported moderately. A mode and a mode which provides a mechanism for exclusive use for making a lumbar support part project forward are considered (for example, refer to the following patent documents 1).
Japanese Patent Laid-Open No. 2003-24175

  If the entire back shell is formed with a curved surface having the same curvature, the rigidity of any part of the back shell will be substantially the same, giving different rigidity and deformation characteristics to each part of the back shell itself. I can't. When a seated person leans on a backrest having such a back shell, it is possible to prevent elastic deformation in the lower side of the back shell that receives a relatively large load, particularly in a direction in which the lumbar support portion is relatively recessed. In order to give the seated person a feeling of moderate hip contact, the above-described modes, that is, a mode in which the lumbar support part is directly supported by the back support rod, or a dedicated mechanism for projecting the lumbar support part forward are provided. Aspects are adopted, but in these aspects, the waist of the seated person is not supported by the elasticity of the back shell, so that the waist is pushed out in an unnatural state locally. Was given to the seated person. In particular, the aspect of providing a dedicated mechanism for projecting the lumbar support part forward also has a demerit that the structure is complicated.

  The present invention has been made paying attention to such a problem, and the main purpose is to provide different characteristics for each part of the back shell, and appropriate elasticity of the back shell according to the load. To provide a chair that realizes a bending deformation state provided with the above and does not give the seated person an uncomfortable feeling that the waist is pushed out in an unnatural state locally or can suppress the giving. is there.

  That is, the chair of the present invention includes a backrest having a back shell mainly composed of a resin-made elastic plate-like body, and a back support rod that supports the back shell. An upper portion of the back shell that forms a curved surface in which the left and right side edges protrude forward from the central portion in the left-right width direction, and a curved surface having a larger curvature than the upper portion of the back shell, and the waist of the seated person A lumbar support portion that can support the lumbar support portion and a back shell lower portion that extends substantially below the lumbar support portion in a curved shape substantially the same as the lumbar support portion, and the lumbar support portion protrudes relatively forward. The back shell upper portion and the back shell lower portion are respectively supported by the back support rod so as to be held in a shape.

  Here, the “back shell lower part” of “a curved shape substantially the same as the lumbar support part” means “the lower part of the back shell where the curvature of the curved surface is the same as the curvature of the lumbar support part” or “the curvature of the curved surface is Although it is different from the curvature of the lumbar support portion, the lower portion of the back shell is larger than the curvature of the upper portion of the back shell.

  In such a case, since the curvature of the curved surface of the lumbar support portion and the lower portion of the back shell is set to be larger than the curvature of the curved surface of the upper portion of the back shell, the lower portion of the lumbar support portion and the lower shell is the upper portion of the back shell. The lower side of the back shell, particularly the lumbar support, which receives a relatively large load when the seated person leans against the backrest having such a back shell, Higher rigidity than the upper part of the shell prevents elastic deformation in the relatively concave direction, while the upper part of the back shell is relatively low in rigidity, so it flexibly elastically follows the movement of the seated person's shoulders. The upper body of the seated person can be evenly supported over the entire back shell. In addition, the back shell upper part and the back shell lower part are supported by the back support rods so that the lumbar support part is held in a shape protruding relatively forward, so that the back shell is entirely in accordance with the load. A state in which the lumbar support portion of the back shell is not supported directly from the rear by other members, in other words, the lumbar portion of the seated person is supported by the elasticity of the back shell itself. If it is an aspect, and the lumbar support part is pressed and supported from behind by another member or mechanism and protrudes forward, the uncomfortable feeling of the waist that can be given to the seated person is eliminated or suppressed, and the naturalness that is comfortable for the seated person It will give you a feeling of waist contact. In addition, a dedicated mechanism for projecting the lumbar support portion relatively forward becomes unnecessary, and simplification of the structure can be effectively achieved.

  In particular, the back support rod includes an upper back frame that supports the upper portion of the back shell and a lower back frame that supports the lower portion of the back shell, and the upper back frame is pivoted to the lower back frame so that it can be tilted backward. If it is supported, when the occupant puts weight on the upper part of the back shell, the upper back frame tilts backward around the pivot point with the lower back frame, and accordingly the upper part of the back shell The side warps backward, and as a result, the region between the upper part of the back shell and the lower part of the back shell, specifically, the lumbar support part is curved and deformed in a direction that protrudes forward, giving the seated person a good waist feeling. be able to. In addition, when the upper back frame is tilted backward, the back shell is further bent and deformed like a bow, and its elastic return force acts as a force that pulls the upper back frame forward, so that the seated person can turn his back back. When the upper body is lifted away from the drowning, that is, when the upper body is raised, the upper back frame follows the movement and automatically returns to the normal posture before tilting backward. In addition, because the amount of protrusion of the lumbar support part to the front changes depending on the degree of weight applied to the upper part of the back shell, the seated person changes his / her weight application method without operating a dedicated operation part. Thus, it is possible to set the protrusion amount of the lumbar support portion to obtain a desired feeling of waist contact, and it becomes a chair that does not impair practicality while simplifying the structure.

  The back shell is supported by at least one of the upper back frame or the lower back frame so as to be slidable in the height direction, and the portion supported to be slidable is set substantially linearly in the height direction. If it is a thing, by supporting at least one of the upper part of the back shell or the lower part of the back shell on the back support slidably, the curved deformation of the entire back shell can be absorbed by the sliding movement, Smoothly curved and deformed. Moreover, by setting the portion of the back shell that is slidably supported to be substantially linear along the height direction, the slide movement becomes a substantially linear motion, and the back shell slide movement relative to the back support rod is reduced. The operational stability is improved, and the sliding movement can be performed more smoothly, and the curved deformation of the entire back shell can be performed.

  As a specific embodiment, the back shell is configured such that a portion other than the upper portion of the back shell is set to a curved surface having a larger curvature than that of the upper portion of the back shell, and the upper portion of the back shell and the portion other than the upper portion are not allowed. The aspect which has integrally in a height direction via a continuous line is mentioned.

  Further, if the back support rod is arranged only at the substantially central portion in the left-right width direction of the back shell, both side ends of the back shell are in a free state, and the back is a resin plate member. Even if the shell is constructed to have a strength that supports the back load of the seated person, when the load is applied to the left and right ends of the back shell, it can be flexibly bent flexibly according to the load. In this way, twisting deformation of the back shell is allowed, and three-dimensional deformation of the back shell according to how the seated person's weight is applied and the movement of the back is possible.

  As described above, according to the present invention, the curvature of the curved surface of the back shell in plan view can be made different for each part, whereby different rigidity can be given to each part, and the upper body of the seated person can be It can be supported evenly over the entire back shell, realizes a flexural deformation state with appropriate elasticity according to the load, and makes the seated person feel uncomfortable as the waist is pushed out locally in an unnatural state No giving or giving can be suppressed.

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

  As shown in FIGS. 1 to 5, the chair 1 according to the present embodiment has a leg 2, a support base 3 attached to the upper end side of the leg 2 so as to be horizontally pivotable, and a front part supported by the support base 3. A seat receiver 4, a seat 5 attached to the seat receiver 4, a back support rod 6 that pivotally supports the lower end portion of the support base 3 and supports the rear portion of the seat receiver 4, and a backrest 7 attached to the back support rod 6. And so-called swivel chair.

  The leg 2 is composed of a plurality of (five in the illustrated example) leg blades 21 each having a caster at the tip, and leg struts 22 standing from a portion where the base ends of the leg blades 21 are gathered. .

  The support base 3 is integrally bent from the upper wall portion 31 and both side edges of the upper wall portion 31, as shown in FIG. The upper wall portion is made of, for example, a metal having a pair of suspended sidewall portions 32 and a pair of partition walls 33 and 34 functioning as reinforcing ribs provided between the front end portions of the pair of suspended sidewall portions 32. The upper end portion of the leg column 22 is attached to the rear end portion of 31 and supported by the leg column 22. In addition, the partition 33 on the relatively rear side of the pair of partitions 33 and 34 is provided with a retainer guide portion 33a drilled in the thickness direction, and a retainer 912b inserted through the retainer guide portion 33a is used as a coil spring described later. 911 is guided to advance and retreat in the compression advance / retreat direction. The support base 3 has a first support shaft X1 that pivotally supports the back support rod 6 so that the back support rod 6 can be pivoted between the portions of the left and right hanging side wall portions 32 that are slightly rearward from the substantially central portion. Yes. Further, elongated holes 32a for supporting a front frame (not shown) of the seat receiver 4 to be described later are formed in the front end portions of the left and right hanging side wall portions 32 in the thickness direction. The support base 3 is covered with a support base cover body 3c from below so that it cannot be directly seen (see FIG. 3).

  The seat receiver 4 is disposed above the support base 3 and supported by the support base 3 in a state where a rod-shaped front frame (not shown) provided at the front end is inserted into the long hole 32 a of the support base 3. The chair 1 of this embodiment includes armrests 8 that extend upward from the vicinity of the left and right side edges of the seat 4. The armrest 8 shown in FIG. 1 and the like cannot be adjusted in height, but instead of this, an armrest that can be adjusted in height may be applied. Moreover, the chair which does not have an armrest may be sufficient.

  The seat 5 includes a seat shell 51 that plays a role as a structural member that uniformly supports the load applied to the seat 5, a seat cushion (not shown) provided above the seat shell 51, and a seat cushion that covers the seat cushion. And a cover 52.

  The backrest 7 plays a role as a structural member that uniformly supports the load applied to the backrest 7 and is supported by the back support 6 and a back cushion (not shown) provided in front of the back shell 71. ) And a back cushion cover 72 that covers the back cushion.

  The back shell 71 is mainly composed of a resin elastic plate-like body, and the upper and lower portions protrude rearward from the central portion in the height direction, and the left and right side edge portions protrude forward from the central portion in the left-right width direction. It has a three-dimensional shape. A large number of openings 711 are provided in a region above the lumbar support portion 71L that can support the waist of the seated person in the back shell 71, more specifically, in a region above the center in the height direction of the back shell 71. The opening ratio, which is the ratio of the opening 711 in a predetermined region of the back shell 71, is set so as to gradually increase toward the upper edge and both side edges of the back shell 71. In the following description, the entire region of the back shell 71 provided with the opening 711 is referred to as “back shell upper portion 71T”. That is, as shown in FIG. 4 and the like, the back shell 71 is positioned slightly below the back shell upper portion 71T, the back shell central portion 71S that is the central portion in the height direction of the back shell 71, and the back shell central portion 71S. The lumbar support portion 71L and the back shell lower portion 71U, which is a region below the lumbar support portion 71L, are integrally provided. The curvature of the curved surface in plan view of the back shell central portion 71S, the lumbar support portion 71L, and the back shell lower portion 71U is the same, and this curvature is set larger than the curvature of the curved surface in plan view of the back shell upper portion 71T. Yes. 7 (this figure corresponds to FIG. 5 and is a diagram schematically showing only the back shell 71 in the central longitudinal section in the left-right width direction), and has a relatively large curvature. The central portion 71S, the lumbar support portion 71L, and the back shell lower portion 71U have a curved shape that is continuous with a bow, while the back shell upper portion 71T having a relatively small curvature has a substantially linear shape along the height direction. Become. The back shell central portion 71S and the back shell upper portion 71T are continuous with each other with a discontinuous line 712 as a boundary.

  The lumbar support portion 71L of the back shell 71 is provided with a deformation inducing means 713 that can be partially deformed more easily than the peripheral portion of the lumbar support portion 71L. In the present embodiment, a slit 713a extending in the left-right width direction is applied as the deformation inducing means 713. The number of slits 713a may be singular or plural, and in the present embodiment, a pair of upper and lower slits 713a are provided that are spaced apart from each other in the height direction.

  FIG. 8 shows a state before the back shell upper portion 71T is assembled to the back support rod 6 in order to show the manner of assembling the back shell 71 and the back support rod 6 in the Y region of FIG. As shown in FIG. 4, an engagement portion 714 that protrudes rearward and can be engaged with a slide engagement hole 611 formed at an upper end portion of the upper back frame 61 described later is integrally or integrally provided. ing. In FIG. 8, the opening 711 of the upper back shell 71T is omitted. The engaging portion 714 has a substantially block shape, and has a flange portion 714a integrally at the distal end portion (the end portion on the side away from the back surface of the back shell 71).

  As shown in FIG. 5 and the like, the back shell lower portion 71U is integrally or integrally provided with a supported portion 715 that protrudes rearward and is supported by an upper end portion of a lower frame described later. In the present embodiment, a pair of left and right thin plate-like supported portions 715 are provided on the lower end portion of the back shell lower portion 71 </ b> U, that is, the lower end portion of the back shell 71.

  As shown in FIG. 5 and the like, the back support rod 6 that supports the back shell 71 is a portion of the back shell 71 that is above the lumbar support portion 71L that supports the waist of the seated person. An upper back frame 61 that supports the back shell upper portion 71T and a lower back frame 62 that supports the back shell lower portion 71U are provided, and pivot points between the upper back frame 61 and the lower back frame 62 (third support shaft described later) X3) is set rearward on the lower end side of the back shell 71, and the upper back frame 61 is configured to be tiltable (tilted) with respect to the lower back frame 62 around the pivot point. As shown in FIG. 2, the upper back frame 61 and the lower back frame 62 are covered with an upper back frame cover body 61c and a lower back frame cover body 62c from the rear or below, respectively, so that they cannot be directly seen. .

  As shown in FIGS. 5 and 6, the lower back frame 62 includes a pair of left and right lower back frame bodies 621 arranged on the outer side than both side surfaces of the support base 3, and the pair of lower back frame bodies 621. A rigid connection shaft 622 is provided that is rigidly connected to the lower ends and is disposed below the lower surface of the support base 3.

  Each lower back frame main body 621 is substantially plate-shaped, and has a side view shape that gradually extends obliquely rearward from the lower end portion toward the vicinity of the upper end portion and bends the vicinity of the upper end portion obliquely forward.

  The rigid connection shaft 622 has a rod shape and is fixed in a state of being bridged between the lower end portions of the lower back frame main body 621 by appropriate means such as welding.

  In order to attach such a lower back frame 62 to the support base 3, a pair of left and right lower back frame main bodies 621 are rigidly connected by a rigid connection shaft 622, and the lower portion of each lower back frame main body 621 is located between the vicinity of the lower ends. An insertion hole (not shown) provided in the lower side wall portion 621a of each lower back frame main body 621 and an insertion hole (not shown) provided in the both side wall portions 32 of the support base 3 so as to sandwich the support base 3 therebetween. Is performed by inserting the first support shaft X1 in a state where they are communicated with each other. As a result, the lower back frame 62 and thus the back support rod 6 can rotate with respect to the support base 3 about the first support shaft X1. In the present embodiment, an extension portion 621b that extends forward from the other portion is integrally provided in the vicinity of the lower end portion of each lower back frame main body 621, and an insertion hole 621a is formed in each extension portion 621b. ing. The first support shaft X1 is disposed rearward and upward relative to the rigid connection shaft 622.

  In the chair 1 according to this embodiment, in a state where the lower back frame 62 is attached to the support base 3, the rigid shaft 622 of the lower back frame 62 is the lower surface of the support base 3 (specifically, the lower surface of the hanging side wall portion 32). A coil spring 911 is disposed between the rigid coupling shaft 622 and the support base 3 and generates a reaction force in accordance with the backward tilting motion of the back support rod 6. When the lower back frame 62 is tilted rearward about the first support shaft X1, the rigid shaft 622 biases the coil spring 911 in the direction in which the repulsive force is accumulated.

  Specifically, as shown in FIG. 6, the rigid shaft 622 supports a coil spring receiving portion 911 x provided on one end side of a coil spring 911 described later at the center in the longitudinal direction. The coil spring 911 and the coil spring receiving portion 911x constitute the tilting reaction force adjusting device 9 for adjusting the reaction force when the back support rod 6 is tilted backward.

  As shown in FIGS. 5 and 6, the tilting reaction force adjusting device 9 is at least partially housed in the support base 3, and the reaction force when the back support rod 6 is tilted backward is independent of the seat support 4. And a reaction force adjusting operation unit 92 for adjusting the strength of the reaction force of the reaction force generating unit 91 provided on the side edge front end side of the seat 5. It is.

  More specifically, the reaction force generation unit 91 compresses or compresses the coil spring 911 in conjunction with a coil spring 911 and an adjustment operation provided on one end side of the coil spring 911 and received by the reaction force adjustment operation unit 92. And a compression / decompression unit 912 for decompression. The compression / extension unit 912 is a substantially trapezoidal slider 912a in plan view that moves forward and backward in a direction orthogonal to the compression / extension direction of the coil spring 911 in conjunction with the adjustment operation received by the reaction force adjustment operation unit 92, and the slider 912a and the slider 912a. A retainer 912b having a substantially trapezoidal shape in plan view that moves and supports the coil spring 911 and moves back and forth in the compression / extension direction, and the retainer guide portion 33a that guides the advance / retreat of the retainer 912b in the compression / extension direction. Is. As described above, the retainer guide portion 33a is formed in the partition wall 33 of the support base 3 for supporting the seat receiver 4.

  The reaction force adjusting operation portion 92 includes a rod 921 that extends in the left-right width direction through one of the hanging side wall portions 32 of the support base 3, and a rod 921 that is provided at the distal end portion of the rod 921 and rotates around the rod 921. And an operation grip 922 to be rotated.

  Returning to the description of the lower back frame 62. Each lower back frame main body 621 of the lower back frame 62 is integrally provided with a second extending portion 621c that extends forward from the peripheral portion at a position slightly below the central portion in the height direction. The rear end side of the seat receiver 4 is supported by a second support shaft X2 that is fixed in a state of being bridged between the protruding portions 621c. Furthermore, the supported portion 715 of the back shell 71 is fixed to a portion near the upper end of each lower back frame main body 621 by an appropriate means such as screwing so that the relative angle cannot be changed.

  The upper back frame 61 pivotally supported by the upper end of the lower back frame 62 having such a configuration has a width dimension that is sandwiched between the pair of left and right lower back frame bodies 621 as shown in FIG. In addition, the upper end portion and the lower end portion are formed in a substantially U shape in a side view in which the upper end portion and the lower end portion are protruded rearward from the central portion in the height direction. As shown in FIG. 8, a slide engagement hole 611 in which the engagement portion 714 provided in the back shell upper portion 71T is slidably engageable is formed in the upper end portion of the upper back frame 61. The slide engagement hole 611 is continuously provided above the large hole 611a and the large hole 611a into which the flange 714a of the engagement part 714 can be inserted and removed, and the flange 714a inserted from the large hole 611a. And a small hole 611b that can allow the relative sliding movement of the engaging portion 714 in a state where it cannot be removed. The height dimension of the small hole part 611b is set to be larger than the height dimension of the large hole part 611a, and a margin for relative sliding movement between the slide engagement hole 611 and the engagement part 714 is secured.

  An insertion hole penetrating in the left-right width direction (not shown) is formed in the lower end portion of the upper back frame 61, and this insertion hole and the insertion hole 621d provided in the upper end portion of each lower back frame main body 621 are communicated with each other. By inserting the third support shaft X3 in this state, the upper back frame 61 can be tilted backward about the third support shaft X3. In the present embodiment, the third support shaft X <b> 3 is set so as to be arranged rearward on the lower end side of the back shell 71. Further, the upper back frame 61 includes an overhang portion 612 that extends downward from the pivot point (third support shaft X3), and the upper back frame 61 is interposed between the overhang portion 612 and the lower back frame 62. A second coil spring 63 that generates a reaction force in association with the backward tilting operation of the frame 61 is provided. In the present embodiment, in a state where the fourth support shaft X4 is bridged between portions slightly below the bent upper end portion of the pair of left and right lower back frame main bodies 621 of the lower back frame 62. It is fixed, and one end portion of the second coil spring 63 is supported by the fourth support shaft X4, and the other end portion of the second coil spring 63 is supported by the overhang portion 612 of the upper back frame 61.

  With the back shell upper portion 71T and the back shell lower portion 71U supported by the upper end portion of the upper back frame 61 and the upper end portion of the lower back frame 62, respectively, the back shell 71 and the back support rod 6 (specifically, the upper back frame 61). A space is formed between

  Next, the usage method and effect | action of the chair 1 which concerns on this embodiment comprised from each member mentioned above are demonstrated.

  As shown in FIGS. 1 to 5, the chair 1 according to the present embodiment is in a normal state (S) in which the backrest 7 takes a standing posture, and as shown in FIGS. 9 and 10, the backrest 7 is tilted backward. In accordance with the movement, the seat 5 is slid in the direction of sinking backward in a synchronized state (R) in which the seat 5 slides backward, and in the normal state (S) as shown in FIG. 11 and FIG. When the weight is applied to the upper part of the backrest 7, the upper back frame 61 tilts backward about the third support shaft X3, and accordingly, the entire back shell 71 is bent and deformed like a bow in a side view. At least the back tilt state (T) can be taken.

  In the normal state (S), the back shell 71 mainly composed of an elastic plate-like body has a curved shape like a side view bow against its elasticity.

  When a seated person leans the entire back on the backrest 7 with respect to the chair 1 in such a normal state (S), as shown in FIG. While maintaining the relative angle to the lower back frame 62, the back shell 71 tilts backward with the first support shaft X1 as the center. At this time, since the weight of the seated person is applied almost evenly to the entire backrest 7, the upper back frame 61 does not tilt backward with respect to the lower back frame 62, in other words, the upper back frame 61 and the lower back frame. The relative angle with the frame 62 does not change, and the back shell 71 also tilts backward while maintaining substantially the same shape as in the normal state (S). A front frame (not shown) provided at the front end of the seat support 4, the rear end of which is supported by the second support shaft X <b> 2 of the lower back frame 62 in accordance with the backward tilting operation of the back support rod 6. Is slid in the direction of sinking backward while moving in the long hole 32a. As a result, the entire seat 5 supported by the seat receiver 4 slides and moves in the same direction as the seat receiver 4, that is, in the direction of sinking backward (see FIG. 9), and the chair 1 enters the synchro-rocking state (R).

  In the synchro-rocking state (R), the rigid shaft 622 of the lower back frame 62 presses the coil spring 911 in the direction in which the repulsive force is accumulated, so that the seated person separates his back from the backrest 7, that is, When the upper body is raised, the entire back support 6 is automatically returned to the normal posture before being tilted backward by the repulsive force of the coil spring 911. In the present embodiment, the tilting reaction force adjusting device 9 can adjust the reaction force when the backrest 7 is tilted backward. Specifically, when the operation grip 922 is rotated in one of the clockwise and counterclockwise directions (for example, clockwise), the slider 912a moves in a direction approaching the operation grip 922 in conjunction with this, and the slider 912a presses the retainer 912b. Then, the retainer 912b pressed by the slider 912a moves in a direction in which the coil spring 911 is compressed, and the reaction force when the backrest 7 is tilted backward can be increased. On the other hand, if the operation grip 922 is rotated in the reverse direction (for example, counterclockwise), the reaction force when the backrest 7 is tilted backward can be reduced.

  On the other hand, in the normal state (S), when the seated person intentionally puts weight on the back shell upper portion 71T, the upper back frame 61 of the back support rod 6 is centered on the third support shaft X3 as shown in FIG. As shown in FIG. Along with the backward tilting action of the upper back frame 61, the back shell upper portion 71T of the back shell 71 supported by the upper back frame 61 is acted on by the lower back frame 62 while a force is exerted to warp backward. Since the lower end portion of the back shell 71 tries to stay at the position in the normal state (S) by the lower back frame 62 that does not tilt backward, the back shell 71 is a portion between the back shell upper portion 71T and the back shell lower portion 71U. Is further curved and deformed so as to protrude further forward. In this embodiment, since the lumbar support portion 71L of the back shell 71 is provided with the deformation inducing means 713, specifically, the slit 713a, when the entire back shell 71 is curved and deformed like a bow, the opening height of the slit 713a is set. The lumbar support portion 71L is deformed in the narrowing direction, and as a result, the lumbar support portion 71L protrudes relatively forward as compared to the normal state (S). In this embodiment, the back shell upper portion 71T is engaged with and supported by the upper back frame 61 so as to be relatively slidable in the height direction, and is provided on the back shell upper portion 71T when the upper back frame 61 tilts backward. Further, the engaging portion 714 is relatively slid in the height direction within a range in which the engagement state with respect to the slide engaging hole 611 is not released in the slide engaging hole 611 formed in the upper end portion of the upper back frame 61. The entire back shell 71 can be curved and deformed following the backward tilting action of the upper back frame 61. The chair 1 of the present embodiment has a curved upper surface curvature in the back shell 71 that is smaller than that of the other portions, and is substantially straight along the height direction. Therefore, the sliding movement can be performed smoothly in a stable state.

  With the transition of the chair 1 from the normal state (S) to the back tilt state (T), the overhang portion 612 of the upper back frame 61 is interposed between the overhang portion 612 and the lower back frame 62. The two-coil spring 63 is pressed in the direction in which the repulsive force is accumulated. Therefore, when the occupant moves his back away from the backrest 7, that is, when the upper body is raised, the upper back frame 61 automatically returns to the normal position before the upper back frame 61 is tilted backward by the repulsive force of the second coil spring 63, and the chair 1 is in the back tilt state. The normal state (S) is returned from (T). Further, when the chair 1 shifts from the normal state (S) to the back tilt state (T), the elastic return force of the back shell 71 that is curved and deformed more like a bow than the shape in the normal state (S) causes the upper back frame 61 to be restored. Acts as a force for energizing in the direction of pulling forward. Therefore, when the chair 1 is in the back tilt state (T), if the seated person intentionally puts his / her weight on the lumbar support portion 71L, the biasing force further increases, and the biasing force and the repulsion of the second coil spring 63 are increased. Combined with the force, when the occupant lifts his back from the backrest 7, that is, when the upper body is raised, the upper back frame 61 follows its movement and quickly automatically returns to the normal posture before tilting backward. It will be.

  After the chair 1 is shifted from the normal state (S) to the back tilt state (T), when the seated person puts his / her weight on the entire backrest 7, the upper back frame 61 is rearward of the lower back frame 62. While maintaining the tilted posture, the lower back frame 62 tilts backward about the first support shaft X1. As a result, the chair 1 is in the last tilted state (not shown) that combines the back tilt state (T) and the synchro-rocking state (R). In a similar manner, after the transition from the normal state (S) to the synchro-rocking state (R), when the seater intentionally puts weight on the upper back frame 61, the upper back frame 61 is moved to the third support shaft. It tilts backward with respect to the lower back frame 62 around X3, and becomes a final tilted state combining the synchro-rocking state (R) and the back tilt state (T) (not shown).

  That is, the chair 1 according to the present embodiment has a normal state (S), a synchro-rocking state (R), a back tilt state (T), depending on how a seated person sits, more specifically, how to apply weight. The last tilted state, or an intermediate state that is intermediate between two different states (for example, an intermediate state between a normal state (S) and a synchro-rocking state (R), a normal state (S), and a back tilt state (T) Intermediate state: not shown).

  The chair 1 of the present embodiment includes a tilt braking device A that is provided between the back support rod 6 and the support base 3 so as to selectively allow the tilt motion of the backrest 7. The tilt braking device A supports the lower end portion of the tilt braking device A on the rear end side of the support base 3 so as to be swingable, and the upper end portion of the tilt braking device A is supported on the fourth support shaft X4 of the lower back frame 62. In this embodiment, as shown in FIG. 6, as the tilt braking device A, a substantially cylindrical gas spring main body A1 is housed, and substantially the whole is accommodated in the gas spring main body A1. A well-known gas spring having a piston rod portion (not shown) that advances and retreats as much as possible and functions as a tilt braking portion is applied, and detailed description thereof is omitted.

  Thus, the chair 1 according to this embodiment sets the curvature of the curved surfaces of the lumbar support portion 71L and the back shell lower portion 71U to be larger than the curvature of the curved surface of the back shell upper portion 71T. 71L and lower back shell portion 71U are relatively stiffer than back shell upper portion 71U, and a relatively large load is received when a seated person leans on backrest 7 having such back shell 71. The lower side of the back shell 71, in particular, the lumbar support portion 71L is prevented from elastically deforming in a relatively recessed direction due to higher rigidity than the back shell upper portion 71T, while the back shell upper portion 71U is relatively low in rigidity. Therefore, it is easy to be elastically deformed flexibly following the movement of the vicinity of the shoulder of the seated person, and the upper body of the seated person can be uniformly supported over the entire back shell 71. . In addition, since the back shell upper portion 71T and the back shell lower portion 71U are supported by the back support rods so that the lumbar support portion 71L is held in a shape that protrudes relatively forward, the back shell 71 depends on the load. In other words, the lumbar support portion 71L is not directly supported from the rear by other members, in other words, the elasticity of the back shell 71 itself. If the lumbar support portion 71L is pressed and supported from behind by another member or mechanism and protrudes forward, the discomfort of the waist that can be given to the seated person is eliminated or suppressed. It will give you a natural and comfortable feeling. Furthermore, a dedicated mechanism for projecting the lumbar support portion 71L relatively forward becomes unnecessary, and simplification of the structure can be effectively achieved.

  In particular, the back support rod 6 includes an upper back frame 61 that supports the back shell upper portion 71T and a lower back frame 62 that supports the back shell lower portion 71U, and the upper back frame 61 can be tilted backward to the lower back frame 62. Therefore, when the seated person puts his / her weight on the back shell upper portion 71T, the upper back frame 61 is located behind the lower back frame 62 around the pivot point (third support shaft X3). As a result, the upper side of the back shell 71 warps backward, and as a result, a region between the back shell upper portion 71T and the back shell lower portion 71U, specifically, the lumbar support portion 71L naturally protrudes forward. It can be curved and deformed in the direction, giving the seated person a good waist contact feeling. In addition, when the upper back frame 61 is tilted backward, the back shell 71 is further bent and deformed like a bow, and the elastic return force acts as a force that urges the upper back frame 61 back to the front. When the back is separated from the backrest, that is, when the upper body is raised, the upper back frame 61 follows the movement and quickly returns automatically. In addition, the amount of forward protrusion of the lumbar support portion 71L also changes depending on the degree of weight applied to the back shell upper portion 71T, so that the seated person can apply his / her own weight without operating the dedicated operation portion separately. By changing it, it is possible to set the protrusion amount of the lumbar support portion 71L that gives a desired feeling of waist contact, and it becomes a chair that does not impair practicality while simplifying the structure.

  Further, since the back shell upper portion 71T is supported by the upper back frame 61 so as to be slidable in the height direction, when the upper back frame 61 tilts backward around the pivot point (third support shaft X3). The back shell upper portion 71T slides and moves in the height direction with respect to the upper back frame 61 to allow the back shell upper portion 71T to bend backward, and the entire back shell 71 is smoothly bent and bent. Since the back shell upper portion 71T supported so as to be slidable is set in a substantially linear shape in the height direction, the slide movement becomes a substantially linear operation, and the back shell relative to the upper back frame 61 is The operational stability of the slide movement of 71 is improved, and the slide movement can be performed more smoothly, and consequently, the entire back shell 71 can be curved and deformed.

  Furthermore, since the back support rod 6 is arranged at the substantially central portion in the left-right width direction of the back shell 71, both side end portions of the back shell 71 are opened, and the torsional deformation of the back shell 71 is allowed. The three-dimensional flexure deformation of the back shell 71 according to how to apply the body weight becomes possible. In the present embodiment, since a plurality of openings 711 are formed in the back shell upper portion 71T, the presence of the plurality of openings 711 enables smooth twist deformation of the back shell upper portion 71T capable of supporting the vicinity of the shoulder of the seated person. Has contributed greatly to the realization of In addition, the smoothness of the upper portion of the back shell 71T is that the opening ratio, which is the ratio of the opening 711 in the predetermined region, is set to gradually increase toward the upper edge and both side edges of the back shell 71. This contributes to the realization of a torsional deformation.

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

  For example, in the above-described embodiment, the back support rod includes a lower back frame and an upper back frame that can be tilted backward with respect to the lower back frame. It may be a back support that cannot change the angle relative to the side. As an example of the back support rod in this case, there is a mode in which the side view is substantially L-shaped and the lower end portion or a portion near the lower end portion is pivotally supported by a support base portion disposed below the seat.

  Moreover, in the said embodiment, the back shell upper part 71T is engaged with the upper back frame 61 so that a slide movement is possible in a height direction as a slide engagement mechanism which accept | permits the relative slide movement of a back shell and a back support rod. However, instead of this, the lower back frame may be supported in a state in which the lower back frame is slidably engaged with the back support rod (lower back frame) in the height direction. Alternatively, both the upper and lower portions of the back shell may be supported in a state of being engaged with each other so as to be slidable in the height direction. That is, a mode in which a slide engagement mechanism that allows relative sliding movement between the back shell and the back support rod is provided only between the upper back frame and the back shell, or provided only between the lower back frame and the back shell. Any of these modes, or a mode provided between each back frame and the back shell, may be used. Furthermore, the slidable distance may be appropriately changed according to the specifications. In the said embodiment, although the aspect which engages an engaging part with an engagement hole was illustrated, it may replace with an engagement hole and may apply an engagement groove | channel. In addition, as a slide engagement mechanism, an engagement concave portion such as an engagement hole or an engagement groove is integrally provided on the back shell side, and an engagement convex portion capable of sliding engagement with the engagement concave portion is provided on the back frame side. Aspects may be adopted. As an example, as shown in FIG. 13, a pocket-shaped engaging recess 714 ′ opening only downward is integrally provided on the back surface of the back shell 71 (upper shell upper portion), while a back support rod (upper back frame 61 is provided. ) Is provided with an upward engaging engagement convex portion 611 ′ having an L shape in side view that can be inserted from below, and the engagement convex portion 714 ′ By reducing the amount of squeezing of the engagement recess 714 ′ with respect to the engagement protrusion 611 ′ within a range in which the engagement state between the portion 611 ′ and the engagement recess 714 ′ is not released, the back shell 71 can be A mode in which the frame 61) can slide in the height direction is mentioned. In this case, the engaging concave portion and the engaging convex portion can be engaged with each other by dropping the back shell into the back support rod from above, and the assembling work can be easily performed.

  Moreover, it is good also as an aspect which respectively arranged the back support rod which consists of an upper back frame and a lower back frame in the both-sides edge part of a back shell, or both site | part vicinity parts. That is, the chair may be provided with a plurality of sets (including three or more sets) of back support rods composed of an upper back frame and a lower back frame.

  Moreover, it is good also as an aspect which respectively arranged the back support rod which consists of an upper back frame and a lower back frame in the both-sides edge part of a back shell, or both site | part vicinity parts. That is, the chair may be provided with a plurality of sets (including three or more sets) of back support rods composed of an upper back frame and a lower back frame.

  In the above embodiment, the back shell is exemplified by the lumbar support portion and the curved surface of the lower portion of the back shell that are set to have substantially the same curvature. However, the present invention is not limited to this, and the curvature of the curved surface of the lower portion of the back shell The back shell may be different from the curvature of the curved surface of the support portion while being set larger than the curvature of the curved surface of the upper portion of the back shell.

  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.

The whole figure which looked at the chair concerning one embodiment of the present invention from the slanting front. The whole figure which looked at the chair concerning the embodiment from the slanting back. The side view of the chair in a normal state in the embodiment. The rear view of the chair in a normal state in the embodiment. Action explanatory drawing which abbreviate | omits and shows FIG. The X direction arrow line view in FIG. The figure which is a part of FIG. 5, and shows only a back shell typically in the left-right width direction center longitudinal cross-section. The figure which shows typically the assembly | attachment aspect of the back shell and back support rod in the Y area | region of FIG. The figure which shows the chair in a synchro-rocking state in the embodiment corresponding to FIG. The figure which shows the chair in a synchro-rocking state in the embodiment corresponding to FIG. The figure which shows the chair in a back tilt state in the same embodiment corresponding to FIG. The figure which shows the chair in a back tilt state in the embodiment corresponding to FIG. The figure which shows typically the modification of the slide engagement mechanism in the embodiment corresponding to FIG.5 and FIG.12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chair 6 ... Back support rod 61 ... Upper back frame 62 ... Lower back frame 7 ... Backrest 71 ... Back shell 71U ... Lower part (lower back shell)
71T… Upper part (back shell upper part)
71S ... Central part (back shell central part)
71L ... Lumber support part 712 ... Discontinuous line X3 ... Pivoting point (third spindle)

Claims (5)

A chair having a backrest having a back shell mainly composed of a resin-made elastic plate-like body, and a back support rod supporting the back shell;
The back shell forms a curved surface with a curved surface with left and right side edges projecting forward from the center in the lateral width direction; and a curved surface with a larger curvature than the back shell upper part; and The lumbar support part that can support the lumbar part of the seated person and the back shell lower part that extends substantially below the lumbar support part in a curved shape substantially the same as the lumbar support part, and the lumbar support part is relatively A chair characterized in that the back shell upper portion and the back shell lower portion are supported by the back support rod so as to be held in a shape protruding forward. The back support rod includes an upper back frame that supports the upper portion of the back shell and a lower back frame that supports the lower portion of the back shell, and the upper back frame is pivotally supported by the lower back frame so as to be able to tilt backward. The chair according to claim 1, wherein The back shell is supported by at least one of the upper back frame or the lower back frame so as to be slidable in the height direction, and the portion supported to be slidable is set substantially linearly in the height direction. The chair according to claim 2 which is a thing. The back shell is configured such that a portion other than the upper portion of the back shell is set to a curved surface having a larger curvature than the upper portion of the back shell, and the upper portion of the back shell and the portion other than the upper portion are arranged in a height direction via a discontinuous line. The chair according to claim 1, 2, or 3, which is integral with the chair. The chair according to claim 1, 2, 3, or 4, wherein the back support rod is disposed only at a substantially central portion in a lateral width direction of the back shell.

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