Chair backrest

Abstract

To make a back plate made of elastomer that is usable without blocking a reclining function in a backrest where an upper back frame rotates forward when a back frame device bends and is reclined.SOLUTION: An upper half part of a back plate 18 is fixed to an upper back frame 9 with a screw 34, and the lower half part of the back plate 18 is connected to a lower side member 8a in the state that it can move relatively vertically with respect to the lower side member 8a. Between the back plate 18 and the side members 8a, 9a, slide auxiliary bodies 39, 40 are disposed. The back plate 18 is made of elastomer, has many small holes and can be formed into a ventilation structure, and is excellent in fitness to a sitter because it warps and deforms. The back plate 18 has a certain degree of thickness, but the lower half part of the back plate 18 escapes and moves to the lower side member 8a, so that back frame device smoothly bends.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a backrest of a chair having a reclining function (locking function).

Background Art

[0002] Reclining chairs in which the backrest reclines against elastic means are widely used for office use. In this reclining chair, there is a demand for the user to view the monitor (display) of the personal computer in a comfortable state while taking a relaxed posture with the body reclined.

[0003] In response to this demand, it can be said that the user's head should be kept raised in the reclined state. That is, if the backrest simply reclines, the user's face will change its posture upward, so the line of sight will deviate from the monitor of the personal computer. Moreover, if the head is raised and the face is turned toward the personal computer, the neck and shoulders will be burdened and it is easy to induce stiffness in the neck and shoulders. However, if the user's head is set to be supported in the forward state in the reclined state, the monitor of the personal computer can be viewed without getting tired in the reclined state.

[0004] As a technology for meeting this demand, Patent Document 1 discloses that while the backrest is configured as a high-back specification that also supports the user's head, the middle height portion thereof is configured to be bent and deformed in a side view, and when reclining, the backrest is bent in a crank shape in a side view, thereby relatively raising the user's head when reclining.

[0005] Specifically, in Patent Document 1, a first tilting frame with the upper end of the backrest fixed and a second tilting frame with a lower portion of the backrest fixed are used. The portion between the fixing portions of both tilting frames in the backrest forms a bent portion, and the backrest is bent in a crank shape by utilizing the difference in the rotation fulcrums of both tilting frames.

[0006] On the other hand, Patent Document 2 discloses a technology in which the backrest is configured as a high-back type that supports the user's head, and the upper part where the user's head is supported and the lower base part are bent in a side view. By shifting the pivot point of the tilting frame connected to the upper part of the backrest and the tilting frame with the base fixed in the front-rear direction, the backrest reclines as a whole while the upper part of the backrest tilts forward relative to the base. In any of the patent documents, since the head can be kept in a forward-facing position during reclining, it is beneficial because the monitor of the personal computer placed on the plane can be easily viewed continuously for a long time.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Now, in Patent Document 1, the backrest has a structure in which a mesh material is stretched over a frame structure that is open front and back, and the frame structure is configured to be bent. In this case, since the mesh material originally has flexibility, there are no particular problems even when the frame structure is bent. That is, there is no problem such that the load concentrates on the bent portion of the mesh material and the durability decreases.

[0009] Also, in Patent Document 2, the backrest has a structure in which a cushion material is stretched over a resin back plate, and the cushion material can originally bend freely. Therefore, in this case as well, there are no inconveniences such that the durability of the cushion material decreases due to the bending of the backrest.

[0010] On the other hand, from the perspective of the user's sense of use (softness of body contact, reclining comfort, etc.), the mesh material in Patent Document 1 has the advantage of high breathability. However, since the mesh material simply stretches and deforms, it is difficult to expect a good fit that conforms to the unevenness of the user's back. In contrast, in the case of the cushion type in Patent Document 2, although the cushion material has excellent fit because any part can be recessed, there is a problem of poor breathability. In addition, since a shell-shaped back plate for supporting the cushion material is required, there is also a problem that a simple appearance like a mesh specification cannot be achieved.

[0011] In this regard, if an elastic back plate such as an elastomer plate is adopted as a member for supporting the seated person, the back plate can be partially stretched and deformed by making a number of small holes, etc. Therefore, while ensuring breathability and a high fit to the body, a simple appearance like a mesh specification can be created.

[0012] However, since the elastic back plate has a certain thickness, when it is fixed to a bending backrest device, there is a possibility that the elastic force of the back plate becomes a resistance and it becomes difficult for the backrest device to bend. Moreover, if the bent part of the back plate is thinned to form a hinge part, another problem such as a decrease in the durability of the back plate may appear.

[0013] The present invention has been made against such a background, and when adopting a back plate made of an elastic material while making the backrest have a bending structure, it aims to disclose a technology that can ensure smooth bending movement of the backrest device without impairing the functions and durability of the back plate.

Means for Solving the Problem

[0014] The present invention includes various configurations, and typical examples thereof are specified in each claim. Among these, the invention of claim 1 is "a backrest device in which an upper backrest and a lower backrest are connected so as to be bendable in the front-rear direction, and a back plate made of an elastic material disposed on the front surface of the backrest device, The back plate is attached to the upper back frame, lower back frame, or both upper and lower back frames in a state where it can slide partially or entirely in the vertical direction. It has such a configuration.

[0015] The invention of claim 2 is a development example of claim 1, "The back plate is held in a state where it does not move vertically relative to the upper back frame and is held so as to move vertically relative to the lower back frame." It has such a configuration.

[0016] The invention of claim 3 is a development example of claim 1 or 2, "A loop structure for attaching the back plate is formed by the upper back frame and the lower back frame, and the back plate is allowed to be recessed backward by the pressing force of a seated person." It has such a configuration.

[0017] The invention of claim 4 is a development example of claim 3, "The upper back frame and the lower back frame are provided with side members on the left and right in the vertical longitudinal direction, and the upper side member constituting the upper back frame and the lower side member constituting the lower back frame are connected by pins in the vertical longitudinal direction, and a lower slide assist body in the vertical longitudinal direction is arranged between the lower side member or the upper side member or both and the back plate." It has such a configuration.

[0018] The invention of claim 5 is a development example of claim 4, "It includes a lower slide assist body arranged only between the lower side member and the back plate and an upper slide assist body in the vertical longitudinal direction extending across the upper side member and the lower side member, and the upper and lower slide assist bodies are partially overlapped in a front view in a state where they can slide relatively vertically." It has such a configuration.

[0019] The invention of claim 6 is a development example of claim 5, The back plate is integrally fixed to the upper back frame and the upper slide assist body, and the portion of the back plate that overlaps with the lower back frame is connected to the lower back frame so as not to be able to move away forward and to move relatively up and down. The lower slide assist body is fixed to the lower back frame in a state of sliding up and down relative to the back plate and the upper slide assist body. It has such a configuration.

Advantages of the Invention

[0020] In the present invention, since a part or the front part of the back plate slides up and down with respect to the back frame device in conjunction with the bending of the back frame device, a strong load is not applied to a part of the back plate when the back frame device bends, and the backrest can be bent smoothly. That is, the back plate does not hinder the bending of the backrest. And since the back plate does not form a part with weak strength like a hinge part, there is no problem with the support function of the pressing force (body pressure) of the seated person, and while allowing a backward concave deformation due to the body pressure, the seated person can be firmly supported.

[0021] Therefore, the present invention can enjoy the advantages of using a back plate made of an elastic material, ensure high fitness and breathability, and facilitate the bending movement of the backrest. Therefore, a chair that can face the in-flight monitor in a reclined state can be provided in an excellent state in terms of design and function.

[0022] When reclining, the body pressure (pressing force) of the seated person acts strongly on the upper half of the backrest. However, in the invention of claim 2, since the upper part of the back plate on which the body pressure of the seated person acts during reclining is fixed to the upper back frame during bending, there is no gap between the outer periphery of the back plate and the inner periphery of the upper back frame (especially the upper ends of the back plate and the upper back frame) during reclining, and the body pressure can be firmly supported. Also, problems with aesthetics due to the generation of gaps or problems such as a shirt getting caught in the gap do not occur. Therefore, it is highly practical.

[0023] In this case, even if the lower end of the back plate moves up and down relative to the lower end of the back frame device, the lower end of the back plate is basically not visible, so there is no problem with aesthetics. When the lower half of the back plate is supported from behind by the lumbar support device, the lower half of the back plate is prevented from moving backward, so that a strong load is prevented from acting on the connecting portion of the back plate with the lower back frame, and there is an advantage that the sliding between the back plate and the lower back frame can be smoothed.

[0024] When the back frame device is formed into a loop structure with an opening in the front and rear as in claim 3, the back plate is allowed to escape and deform (deform so as to bulge) backward, so that the fit can be improved. In particular, when applied to a high-back chair as in the embodiment, it can preferably support the scapula softly.

[0025] When a slide assist is provided as in claim 4, the relative sliding between the back plate and the back frame device can be promoted, and the bending movement of the back frame device can be made even smoother. As the back plate, an elastomer-based soft resin is preferable, but since the elastomer-based soft resin has a large coefficient of friction, it is particularly preferable to provide a slide assist as in claim 4.

[0026] When providing a slide assist, when upper and lower slide assists are adopted and partially overlapped as in claim 5, the portion of the back plate that is continuous with the upper back frame and the lower back frame can be smoothly bent. That is, the back plate can be curved without a sense of incongruity. Therefore, the smoothness of the bending movement of the back frame device can be further promoted, and the deterioration of aesthetics can also be prevented.

[0027] The invention of claim 6 is also a development example of claim 2, but since a slide assist is interposed between the back plate and the lower back frame, the back plate can smoothly escape and move downward during the bending movement of the back frame device. Therefore, the quality of the chair can be improved.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0029] Next, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the terms "front" and "rear", "left" and "right" are used to specify directions, and these directions are defined as the directions seen from a person normally sitting on the chair. The front view is a view seen from the direction facing the seated person.

[0030] (1). Basic Structure of the Chair First, the outline of the chair will be described mainly with reference to FIGS. 1 to 5. This embodiment is applied to a swivel chair frequently used in offices. The chair includes a leg device 1, a seat 2, and a backrest 3 as basic elements. The leg device 1 has a structure in which a leg column 4 made of a gas cylinder is erected at the center of a base having five leg blades, and casters are provided at the tips of the respective leg blades.

[0031] For example, as shown in FIGS. 1(A) and 1(B), a base 5 is fixed to the upper end of the leg column 4, and the lower tips of the left and right first tilting frames 6 are connected to the base 5 by a first reference support shaft 7 (see FIG. 2(A)). For example, as shown in FIG. 1(B), the first tilting frame 6 extends rearward while spreading outward to the left and right from the base 5 and then rises upward, and the portion that rises upward and spreads greatly outward to the left and right constitutes a lower side member 8a of the lower back frame 8.

[0032] The lower ends of the lower side members 8a that constitute the lower back frame 8 are connected by a lower member 8b that is longitudinally long in the left and right directions. That is, the lower back frame 8 is constituted by connecting the rising portions of the left and right first tilting frames 6 with the lower member 8b.

[0033] An upper back frame 9 that constitutes a back frame device integrally with the lower back frame 8 is disposed on the lower back frame 8. The upper back frame 9 is formed in a loop shape by left and right upper side members 9a that are long in the vertical direction, an upper member 9b connected to the upper ends of the upper side members 9a, and a middle member 9c connected to the lower ends of the upper side members 9a.

[0034] As shown in FIG. 4, the lower ends of the upper side members 9a in the upper back frame 9 are connected to the upper ends of the lower side members 8a by a second reference support shaft (pin in the claims) 10 that is longitudinally long in the left and right directions. The middle member 9c of the upper back frame 9 projects rearward, and the upper end of a second tilting frame (center frame) 12 that is long in the vertical direction is connected to the left and right middle portions of the middle member 9c that projects rearward so as to be tiltable rearward by a third reference support shaft 11 that is longitudinally long in the left and right directions.

[0035] As shown in FIG. 4, the lower end portion of the second tilting frame 12 is a bifurcated portion 12a having left and right parts, and the front end (lower end) of the bifurcated portion 12a is connected by a bearing portion 13 (see FIG. 1(B)) provided at the rear end of the base 5.

[0036] Therefore, the first tilting frame 6, the second tilting frame 12, and the backrests 8 and 9 rotate relative to each other while tilting backward as a whole. Specifically, as can be understood from FIG. 2(A), due to the differences in the front-rear positions and vertical heights of the respective reference support shafts 7, 10, and 11, during reclining, the upper backrest 9 rotates forward relative to the lower backrest 8 (and the first tilting frame 6).

[0037] And a toprest device 14 is attached to the upper end of the upper backrest 9. During reclining, since the upper backrest 9 rotates forward relative to the lower backrest 8, in the reclined state, the user's head can be held in a state lifted by the toprest device 14. Therefore, the user of the chair can direct their line of sight naturally at the computer on the desk while relaxing their body and perform computer operations such as keyboard operation and mouse operation.

[0038] Note that the control of the backward tilting of the backrest 3 is performed by a gas cylinder (not shown) disposed between the bifurcated portions 12a of the second tilting frame 12. Further, the chair of the present embodiment has a synchro structure in which the seat 2 moves backward while tilting backward in conjunction with reclining. As shown in FIG. 5, the lower member 8b is fixed to a bracket 15 that projects inward from the left and right first tilting frames 6 with screws 16.

[0039] The lower member 8b is made of synthetic resin, and a reinforcing plate 8c for attaching the lumbar support device is fixed to the rear surface thereof with screws (not shown). Further, a core material (lower reinforcement, lower auxiliary) 17 is integrally formed with the lower member 8b by insert molding, and the core material 17 has an upward portion 17a that enters from the front into the inside of the side member 8a in the lower back frame 8. Note that the core material 17 may be screwed to the lower member 8b.

[0040] The backrest 3 includes a back plate 18 made of a flexible resin material such as an elastomer (PTE), and a stretching material 19 stretched on the front surface of the back plate 18. The back plate 18 is bent and deformed following the bending of the backrest device. The back plate 18 is supported from behind by the lumbar support device 20 shown in FIGS. 1(B) and 1(C). As shown in FIGS. 1(B) and 1(C), a lumbar support column 21 is attached to the second tilting frame 12 so as to be tiltable back and forth, and a lumbar support pad 22 is attached to the lumbar support column 21. The lumbar support pad 22 supports the waist of the seated person (especially around the third lumbar vertebra) from behind through the lower half of the back plate 18.

[0041] (2). Backrest and its basic mounting structure Next, the structure of the back will be described with reference to the drawings from FIG. 6 and below. As described above, the back plate 18 is made of elastomer, and the portion where the body pressure of the seated person is applied is several millimeters thick and has elasticity such that a person can easily bend it in a single state. Further, small holes are provided except for the outer peripheral portion. The small holes are formed in a square shape and arranged in vertical and horizontal alignment, but their shape, size, and arrangement direction can be arbitrarily set.

[0042] For example, as can be understood from FIG. 6(C), the side members 8a and 9a have a substantially triangular flat cross-sectional shape protruding rearward, and an upper and lower longitudinal peripheral groove 23 opening forward is formed inside thereof. The same applies to the front surfaces of the upper member 9b and the lower member 8b. Therefore, the peripheral groove 23 extends over the entire circumference. Thus, the outer peripheral portion of the back plate 18 is formed as a thick portion 24, and a rearward protruding ridge 24a that enters the peripheral groove 23 is formed on the thick portion 24.

[0043] And as shown clearly in Fig. 6(C), on the front surface of the thick portion 24 of the back plate 18, a ground attachment groove 25 with a width of about a dozen millimeters and a depth of a few millimeters is formed over the entire circumference, and a substantially plate-shaped edge member 26 is disposed in this ground attachment groove 25. The ground 19 overlaps the front surface of the edge member 26, and the peripheral edge 19a of the ground 19 is engaged with the back surface of the edge member 26, and the ground 19 is sewn to the edge member 26.

[0044] As shown clearly in Fig. 3, the edge member 26 is divided into four parts: an upper part, side parts, and a lower part, and has an overall loop structure. And the edge member 26 has different thicknesses so that the outer side portion of its rear surface droops, and the peripheral edge of the ground 19 is applied to the wall 27 formed by making the thickness different in this way. That is, the ground 19 is positioned by the wall 27.

[0045] Furthermore, on the edge member 26, outwardly hook-shaped locking claws 28 project rearward at appropriate intervals in a plan view, while on the thick portion 24 of the back plate 18, a group of locking holes 29 into which the locking claws 28 are inserted are formed intermittently in the circumferential direction. As shown clearly in Fig. 6(C), on the outer peripheral portion of the thick portion 24 of the back plate 18, a forward rib 30 surrounding the ground 19 is formed over the entire circumference. Therefore, a shallow recess surrounded by the forward rib 30 is formed in the back plate 18. When the edge member 26 to which the ground 19 is attached is fitted into the recess and pushed in, each locking claw 28 is elastically deformed and inserted into the locking hole 29, whereby the ground 19 can be very easily attached to the back plate 18. Note that the attachment of the ground 19 is performed as the last step after attaching the back plate 18 to the back frame device.

[0046] As shown in Fig. 6(D), at the lower end of the back plate 18, the locking hole 29 is formed at a location of a rectangular boss portion 31 protruding rearward. Therefore, as shown in Fig. 5(A), on the front surface of the lower member 8b, a relief recess 32 for allowing the insertion of the boss portion 31 is formed.

[0047] Next, the attachment structure of the back plate 18 to the back frame device will be described. As shown in FIG. 7, the portion of the back plate 18 that overlaps the upper back frame 9 is fixedly attached to the upper back frame 9 by screws 34 and washers 35 so as not to shift. Therefore, a large number of intermittent counterbores 36 into which the heads of the screws 34 fit are formed intermittently in the circumferential direction in the thick portion 24 of the back plate 18. On the other hand, in the circumferential groove 23 of the upper back frame 9, as shown in FIG. 7(A), a group of screw receiving bosses 37 having a front view angular shape into which the screws 34 are screwed are formed. Further, as shown in FIG. 7(B), in the thick portion 24 of the back plate 18, angular boss receiving recesses 38 that fit with the screw receiving bosses 37 are formed.

[0048] (3). Slide structure of the backrest For example, as shown in FIG. 3, between the side portion of the back plate 18 and the back frame device, a lower slide auxiliary body 39 that overlaps only the lower side member 8a in a front view and an upper slide auxiliary body 40 that overlaps both the upper side member 9a and the lower side member 8a are arranged. The upper side member 9a partially overlaps the upper slide auxiliary body 40 in the front-rear direction.

[0049] For example, as shown in FIG. 8, the upper slide auxiliary body 40 and the lower slide auxiliary body 39 are basically in a plate-like form. The upper end of the upper slide auxiliary body 40 is clamped together with the back plate 18 to the lower end portion of the upper side member 9a by screws 34 that fix the back plate 18 to the lower end portion of the upper side member 9a. Therefore, as shown in FIG. 7(B), the portion where the upper end of the upper slide auxiliary body 40 overlaps is not a recess but a land portion 41.

[0050] And, for example, as shown in FIG. 8, the upper slide auxiliary body 40 and the lower slide auxiliary body 39 are arranged such that the upper slide auxiliary body 40 is positioned in the front and the lower slide auxiliary body 39 is positioned in the back. That is, the lower slide auxiliary body 39 overlaps the lower side member 8a, and the upper slide auxiliary body 40 overlaps the lower side member 8a from the front.

[0051] The upward portion 17a of the heartwood 17 also overlaps the lower side member 8a from the front below the upper slide assist member 40. The lower slide assist member 39 is fixed to the lower side member 8a with screws 43 at three locations up and down via resin sleeves 42. Here, a boss body 44 into which the screw 43 is screwed is protruding in the circumferential groove 23 of the lower side member 8a.

[0052] As clearly shown in Fig. 8(C), the sleeve 42 has a flange 42a and is inserted from the front into a rectangular vertical guide hole 45 formed in the back plate 18. And an inward step portion 45a is formed in the outer portion of the guide hole 45, and the flange 42a of the sleeve 42 is placed on the step portion 45a. Therefore, the back plate 18 is held in a non-removable forward direction with respect to the lower side member 8a and is held so as to be able to move up and down relative to the lower side member 8a.

[0053] As clearly shown in Fig. 9, the sleeve 42 is not a complete cylindrical body but the inner part is cut off to form a U shape, but it may be formed as a complete cylindrical body. Also, the flange 42a extends widely on the outside, which corresponds to the fact that the step portion 45a of the guide hole 45 is mainly formed on the outside. That is, since the back plate 18 is pulled to the central side in the left-right direction by the body pressure of the seated person, the step portion 45a of the guide hole 45 and the flange 42a of the sleeve 42 are mainly provided on the outside to prevent removal.

[0054] A U-shaped notch 46 into which the sleeve 42 is non-movably fitted is formed in the lower slide assist member 39 (a hole may be adopted instead of the notch 46). Therefore, the lower slide assist member 39 moves up and down integrally with the lower half of the back plate 18 and the lower side member 8a. On the other hand, a vertical longitudinal long hole (or notch groove) 47 that loosely fits onto the boss body 44 is formed in the upper slide assist member 40. As shown in Fig. 8(B), it is surrounded from above, below, and laterally on the left and right by the long hole 47 and the surrounding frame 47a protruding forward.

[0055] Therefore, the lower half of the back plate 18 and the upper slide auxiliary body 40 are relatively movable in the vertical direction. The upward portion 17a of the core material 17 also overlaps the lower part of the lower slide auxiliary body 39 from the front, and a long hole 47 is also formed in the upward portion 17a of the core material 17. In FIG. 8(A), the upward portion 17a of the core material 17 is arranged behind the lower slide auxiliary body 39, but actually, as shown in FIG. 8(B), the upward portion 17a of the core material 17 overlaps the lower slide auxiliary body 39 from the front.

[0056] As clearly shown in FIG. 9, a frame portion 48 that opens rearward and laterally outward is formed at a portion between the vertically adjacent notches 46 of the lower slide auxiliary body 39, while a U-shaped rearward protrusion 49 that fits into the frame portion 48 is provided on the upper slide auxiliary body 40 and the upward portion 17a of the core material 17.

[0057] Therefore, the sliding of the upper slide auxiliary body 40 and the lower slide auxiliary body 39 is guided by the frame portion 48 and the rearward protrusion 49. Also, the frame portion 48 and the rearward protrusion 49 are responsible for the left - right positioning of the upper slide auxiliary body 40 and the lower slide auxiliary body 39. On the other hand, since the core material 17 is fixed to the lower side member 8a, the rearward protrusion 49 of the core material 17 and the frame portion 48 of the lower slide auxiliary body 39 only perform a positioning function. As can be understood from FIG. 8(B), a deep groove portion 50 into which the frame portion 48 of the lower slide auxiliary body 39 fits is formed in the peripheral groove 23 of the lower side member 8a.

[0058] For example, as can be understood from FIG. 8(B), two outwardly hook - shaped locking claws 51 protrude forward on the upper slide auxiliary body 40 and the upward portion 17a of the core material 17, while an engaging long hole 52 into which the locking claws 51 fit is formed on the side portion of the back plate 18. A stepped portion for the locking claws 51 to catch is formed in the engaging long hole 52. Therefore, the back plate 18 is held in a non - removable manner with respect to the lower side member 8a by the locking claws 51 while allowing vertical movement.

[0059] As can be understood from FIG. 7, the portion of the side of the back plate 18 where the guide holes 45 are formed is an upper and lower longitudinal embankment-like portion 53 protruding rearward, and the upper slide assist 40 and the upward portion 17a of the core material 17 overlap the embankment-like portion 53. For example, as shown in FIG. 8(B), both the upper and lower ends of the lower slide assist 39 are fixed to the lower side member 8a with screws 54. Further, as shown in FIG. 7(B), the embankment-like portion 53 is provided with a recess 68 into which a surrounding frame 47a provided on the upper slide assist 40 and the upward portion 17a of the core material 17 is fitted.

[0060] (4). Summary This embodiment has the above configuration. When reclining, the upper back frame 9 rotates forward relative to the lower back frame 8, so that the seated person can hold their head up in the reclined state. Therefore, while taking a relaxed posture with the upper body reclined, the person can operate a laptop on the plane for a long time while preventing shoulder and neck stiffness. And when reclining, the back plate 18 bends in conjunction with the bending movement of the back frame device, and the lower half of the back plate 18 moves downward relatively via the lower back frame 8. Therefore, the back plate 18 does not act as a resistance to the bending movement of the back frame device, and the bending of the back frame device is performed smoothly.

[0061] In the embodiment, the lower half of the back plate 18 is pulled down by the lower slide assist 39 during reclining. However, since the back plate 18 is connected to the lower slide assist 39 at three locations: upper, middle, and lower, the load does not concentrate on a specific part, and the slide of the back plate 18 is performed smoothly.

[0062] Also, since the back plate 18 is made of an elastomer to form a high-back, when the body pressure of the seated person acts strongly, the part of the back plate 18 retreats greatly, providing a high fit. For example, when the scapula of the seated person hits the back plate 18, the part of the back plate 18 where the scapula hits is bent backward, and a fit that is not available with a mesh material can be felt.

[0063] And in this embodiment, the upper slide auxiliary member 40 overlaps with the upper back frame 9 on the lower side member 8a, and the lower slide auxiliary member 39 is fixed to the back plate 18. As a result, the resin upper slide auxiliary member 40 slides relative to the lower side member 8a and the lower slide auxiliary member 39, realizing the downward movement of the lower half of the back plate 18. Since the back plate 18 does not directly slide in contact with the lower side member 8a, even if an elastomer with a large friction coefficient is used as the back plate 18, the lower side member 8a can slide smoothly relative to the back plate 18.

[0064] Also, when the upper slide auxiliary member 40 is overlapped on both the upper side member 9a and the lower side member 8a as in the embodiment, when reclining, the upper slide auxiliary member 40 bends loosely into an arch shape, preventing the back plate 18 from bending sharply at the connecting portion of the upper and lower side members 8a, 9a, and enabling the back plate 18 to be bent smoothly. Therefore, the durability of the back plate 18 can be improved, and the deterioration of aesthetic appearance can also be prevented.

[0065] When the lumbar support device 20 is provided as in the embodiment, it is possible to prevent the lower half of the back plate 18 from retreating due to the body pressure of the seated person, so that it can be ensured that the back plate 18 does not escape downward during reclining.

[0066] In this embodiment, the back plate 18 moves relative to the flange 42a of the sleeve 42. By making the sleeve 42 of a resin with a small friction coefficient such as POM resin, the relative movement can be smoothed. Also, when the slide auxiliary members 39, 40 are formed with the frame portion 48 and the rearward protrusion 49 as in the embodiment, the relative slide can be smoothed. Using the upward portion 17a of the core material 17 as in the embodiment can stably hold the lower slide auxiliary member 39, which is preferable.

[0067] As described above, embodiments of the present invention have been explained. However, the present invention can be embodied in various other ways. For example, it can also be applied to a type in which the back plate is exposed without using the tension fabric. Further, it is also possible to fix or insert-mold guide members made of hard resin or metal on the back surfaces of the left and right side portions of the back plate, and hold this guide member slidably by the lower side member. Furthermore, by fixing or insert-molding a reinforcing plate in an appropriate vertical range centered on the bent portion of the back plate 18, it is also possible to make the bending of the back plate smooth.

[0068] In the embodiment, it has a middle member and has a loop structure, but it may be a downward-opening U-shape. Further, it is also possible to form the back frame device into a loop structure that is open front and back, and fix this to the tilting frame. In the embodiment, when reclining, the upper back frame tilts forward relative to the lower back frame. Conversely, it can also be applied to a type in which the upper back frame tilts backward relative to the lower back frame during reclining.

Industrial Applicability

[0069] The present invention can be embodied in a chair backrest. Therefore, it can be used industrially.

Explanation of Reference Numerals

[0070] 3 Backrest 6 First tilting frame that also serves as a lower frame body 7 First reference support shaft 8 Lower back frame that constitutes the back frame device 8a Lower side member 8b Lower member 9 Upper back frame that constitutes the back frame device 9a Upper side member 10 Second reference support shaft 11 Third reference support shaft 12 Second tilting frame 14 Toprest device 17 Core material (lower auxiliary body) 17a Upward portion 18 Back plate 19 Tension fabric 20 Lamber support device 23 Circumferential groove 24 Thick part of the back plate 26 Edge member 34 Screw for fixing the back plate 36 Countersunk hole 37 Screw receiving boss 39 Lower slide assist body 40 Upper slide assist body 42 Sleeve 43 Screw 44 Boss body 45 Guide hole 47 Long hole

Claims

1. The book has a back frame device in which an upper back frame and a lower back frame are connected so as to be bendable in the front-rear direction, and a back plate made of an elastic material and overlapped on the front surface of the back frame device, The back plate is attached in a state where a part or the whole of the back plate can slide up and down relative to the upper back frame, the lower back frame, or both the upper and lower back frames. Chair backrest.

2. The back plate is held in a state in which it does not move up and down relative to the upper back frame, and is held so as to move up and down relative to the lower back frame. A chair back according to claim 1.

3. The upper and lower back frames form a loop structure to which the back panel is attached, and the back panel is allowed to be recessed backward by the pressing force of a seated person. A chair back according to claim 1 or 2.

4. The upper spine frame and the lower spine frame have left and right side members in the vertical direction, and the upper side member constituting the upper spine frame and the lower side member constituting the lower spine frame are connected by left and right longitudinal pins, And, an upper and lower longitudinal slide auxiliary body is disposed between the lower side member or the upper side member or both and the back plate. A chair back according to claim 3.

5. The seat includes a lower slide auxiliary body arranged only between the lower side member and the back plate, and an upper slide auxiliary body extending vertically across the upper side member and the lower side member, and the upper and lower slide auxiliary bodies partially overlap each other in a front view in a state in which they can slide vertically relative to each other. A chair back according to claim 4.

6. The back plate is fixed integrally to the upper back frame and the upper slide auxiliary body, and a portion of the back plate overlapping the lower back frame is connected to the lower back frame so as to be movable up and down relative to the lower back frame without being separated forward, The lower slide auxiliary body is fixed to the lower back frame in a state in which it can slide up and down relative to the back plate and the upper slide auxiliary body. A chair back according to claim 5.

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