chair

Abstract

To improve, with a simple constitution, comfort of a chair having a backrest with a cushion arranged on the front face of a back shell where multiple ribs are formed.SOLUTION: A chair has a backrest 4 with a back cushion 18 arranged on the front face of a back shell 17, and includes multiple ribs 24, 25 on the front face of the back shell 17. A cover member 30 for blocking an opening 26 between adjacent ribs 24, 25 is interposed between the front face of the back shell 17 and the back cushion 18.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a chair having a backrest with a cushion disposed on the front surface of the back shell. [Background technology]

[0002] 2. Description of the Related Art In chairs having a backrest, a configuration in which a cushion covered with a skin material is provided on the front surface of the backrest is commonly used (see, for example, Patent Documents 1 and 2).

[0003] The chair in Patent Document 1 is equipped with a back outer shell as an exterior part, and a back inner shell equipped with ribs to maintain the rigidity of the back as separate parts, and a cushion is placed on the front surface of the back inner shell. On the other hand, the chair in Patent Document 2 is equipped with many ribs on the front surface of the back outer shell because the back outer shell is a strength member, and a cushion is placed on the front surface of the back outer shell.

[0004] However, the chair of Patent Document 1 is inferior in terms of cost compared to a chair without a back inner shell like Patent Document 2. On the other hand, the chair of Patent Document 2 has a risk that the user feels the presence of the ribs through the cushion, which may adversely affect comfort. Although the above risk can be eliminated by using a cushion that is hard enough to make the presence of the ribs less noticeable, or a thick cushion, there are concerns that the trade-off is discomfort, increased costs, and a thick backrest that mars the appearance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-84856 A [Patent Document 2] JP 2014-90993 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to improve this current situation, and aims to improve the comfort of sitting on a chair having a backrest with a cushion placed on the front side of a back shell on which a number of ribs are formed, using a simple structure. [Means for solving the problem]

[0007] The present invention relates to a chair having a backrest with a cushion placed on the front surface of a back shell, which is provided with a plurality of ribs on the front surface of the back shell, and which has a cover member interposed between the front surface of the back shell and the cushion to cover the openings between adjacent ribs.

[0008] According to the chair of the present invention, by covering the openings between adjacent ribs formed on the front surface of the back shell with a cover member, the presence of the ribs can be made less noticeable to the user, thereby improving the comfort of sitting and the usability with a simple configuration.

[0009] In the chair of the present invention, the cover member may be formed of a plastic sheet, a nonwoven fabric sheet, or cardboard.

[0010] According to this aspect, the cover member can be formed at low cost and light weight, and the seating comfort can be improved without compromising the appearance of the backrest.

[0011] In the chair of the present invention, the cover member is joined to the cushion and has an engaged portion that engages with an engaging portion provided on the front surface of the back shell. do.

[0012] According to this aspect, the cushion and cover member are joined together, for example by sewing or adhesive, and the engageable portion of the cover member is engaged with the engaging portion of the back shell, making it easier to align the cushion and cover member when attaching them to the back shell, improving work efficiency, and preventing the cushion and cover member from shifting out of position during use, thereby maintaining a comfortable sitting experience. Effect of the Invention

[0013] The chair of the present invention can improve the comfort of sitting on a chair having a backrest with a cushion placed on the front surface of a back shell on which a plurality of ribs are formed, with a simple structure. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 shows an embodiment, in which (A) is a front view and (B) is a side view. [Diagram 2] FIG. 13 shows the embodiment, in which (A) is a rear view and (B) is a side view seen from behind with the spine shell exposed. [Diagram 3] FIG. 2 is an exploded perspective view showing the backrest and tilt frame. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 7] 6A is a cross-sectional view taken along line VIIA-VIIA in FIG. 5, and FIG. 6B is a cross-sectional view taken along line VIIB-VIIB in FIG. [Figure 8] 1 is a perspective view showing the lower part of the back shell and the auxiliary plate separated from each other; FIG. [Figure 9] FIG. 13 is a rear view showing the lower part of the spine shell. [Figure 10] 5(A) is a cross-sectional view taken along line VV of FIG. 5, and FIG. [Figure 11] 5A is a cross-sectional view taken along line XIA-XIA in FIG. 5, and FIG. 5B is a cross-sectional view taken along line XIB-XIB in FIG. [Figure 12] 1A is a perspective view of the spine shell with the pressing member removed, and FIG. 1B is a cross-sectional view taken along line XIIB-XIIB in FIG. [Figure 13] FIG. 13 is an exploded perspective view showing the connection state between the back shell and the tilting frame, as viewed from the front with their postures changed relative to each other. [Figure 14] 1 is a perspective view showing the back shell and the tilting frame separated from each other and viewed diagonally from behind. FIG. [Figure 15] 1A is a perspective view showing the tilting frame and the back cover separated from each other, FIG. 1B is a perspective view of the back cover, and FIG. 1C is a partial perspective view of the tilting frame as seen from the front. [Figure 16] 5A is a cross-sectional view taken along line XVIA-XVIA of FIG. 5, and FIG. 5B is a cross-sectional view taken along line XVIB-XVIB of FIG. [Figure 17] 1A and 1B are front views showing the locking mechanism attachment portion, in which (A) shows a state where nothing is attached, (B) shows a state where the locking mechanism is attached, and (C) shows a state where a cover body is attached. [Figure 18] 4 is a perspective view showing a lock mechanism attachment portion and a cover body separated from each other; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Next, an embodiment of the present invention will be described with reference to the drawings. In the following description, the terms "front, back, left and right" are used to specify directions, but these terms "front, back, left and right" are based on a seated person. The front viewing direction is the direction facing the seated person, so the left and right from the front view are opposite to the left and right from the seated person's perspective.

[0016] (1) Overview of the chair First, an overview of the chair will be described mainly with reference to Figures 1 to 6. This embodiment is applied to a swivel chair that is widely used for office use, etc., and the chair comprises a leg device 1 having a leg support made of a gas cylinder, a base 2 fixed to the upper end of the leg support, a seat 3 disposed on the base 2, and a backrest 4 against which a seated person can lean.

[0017] For example, as shown in Fig. 5, a tilting frame 5 having left and right arms 5a is connected to the base 2 so as to be able to tilt backward. Also, as shown in Fig. 1(B), a seat support body 6 to which a seat 3 is fixed is connected to the base 2 so as to be able to move backward, and the seat support body 6 is connected to the arm 5a of the tilting frame 5 so as to be able to rotate relatively. Therefore, the seat 3 moves backward in conjunction with the backrest 4 and tilts slightly backward.

[0018] The seat 3 has a structure in which a cushion is placed on the upper surface of a resin seat inner shell and this is covered with a covering material, and the seat inner shell is fixed to the seat support body 6 directly or via a seat outer shell.

[0019] 1 to 3, the tilting frame 5 has left and right back support columns 7 that are curved upward in an arch shape, and the back support columns 7 and the base 8 are smoothly connected to each other so as to be curved upward when viewed from the front (and rear). The tilting frame 5 has an inward ridge 9, an outward ridge 10, and a rearward ridge 11, and generally forms a triangular cross-sectional shape. Therefore, the tilting frame 5 has a front surface 12 shown in Fig. 3 and an inclined outer peripheral surface 14 and an inclined inner peripheral surface 13 shown in Fig. 2, and the inclined outer peripheral surface 14 and the inclined inner peripheral surface 13 intersect in a mountain shape to reach the rearward ridge 11.

[0020] In addition, the portion of the tilting frame 5 consisting of the base 8 and the back support 7 becomes thinner toward both the left and right ends. Therefore, the inclined outer peripheral surface 14 and the inclined inner peripheral surface 13 are widest in the middle of the left and right parts and become narrower toward both the left and right ends. A back cover 16 is detachably attached to the outer surfaces of the left and right back support 7. Although not shown in the figure, it is possible to remove the back cover 16 and attach an optional armrest to the outer surface of the back support 7. The tilting frame 5 is made of synthetic resin, but it can also be made of aluminum die-cast.

[0021] (2) Backrest configuration 3 to 6, the backrest 4 includes a back shell 17, a back cushion 18 disposed on the front surface of the back shell 17, and a downward-opening bag-shaped covering material 19 that covers the back shell 17 and the back cushion 18. In this embodiment, the backrest 4 is provided symmetrically. That is, the back shell 17, the back cushion 18, and the covering material 19 are provided symmetrically.

[0022] The back shell 17 is made of synthetic resin and has a plate-like back member 20 arranged upright, left and right side members 21 extending forward from the left and right ends of the back member 20, and left and right horizontally elongated upper members 22 and lower members 23 connecting the upper ends or lower ends of the left and right side members 21. The lower member 23 is configured to be connectable to the tilting frame 5 so as to overlap the front faces of the base 8 and the back support 7 of the tilting frame 5.

[0023] 4, etc., a plurality of vertical ribs 24 and horizontal ribs 25 are provided in a lattice pattern on the front surface of the back member 20 so as to face forward, thereby reducing the weight of the back shell 17 while ensuring the strength of the back shell 17. As a result, a large number of openings 26 are formed on the front surface of the back shell 17 between adjacent vertical ribs 24 and between adjacent horizontal ribs 25.

[0024] Also, a lumbar support device 101 for adjusting the support height of the waist of a seated person is attached to the back shell 17. The lumbar support device 101 includes a lumbar support body 102 that contacts the back cushion 18 from behind, an operating lever 103 as an operating tool for moving the lumbar support body 102 up and down, and a locking mechanism 104 that holds the operating lever 103 so that the height can be adjusted freely. The lumbar support body 102 and the locking mechanism 104 are provided on the front side of the back shell 17 (inside the back shell 17), while the operating lever 103 penetrates the back shell 17 and is provided on the back side of the back shell 17. The lumbar support body 102, the operating lever 103, and the locking mechanism 104 are made of synthetic resin.

[0025] 3, 6, etc., a back cushion 18 is disposed on the front surface of the back shell 17, in front of the vertical ribs 24 and horizontal ribs 25. The tips of the vertical ribs 24 and horizontal ribs 25 are provided at positions stepped down from the front surfaces of the side members 21, upper members 22, and lower members 23 to the rear surfaces, and the back cushion 18 fits into the space surrounded by the side members 21, upper members 22, and lower members 23. The back cushion 18 is made of, for example, polyurethane slab urethane.

[0026] A cover member 30 is attached to the upper half of the back surface of the back cushion 18, covering the opening 26 between the vertical ribs 24 and the horizontal ribs 25. The cover member 30 is made of a plastic sheet such as a polypropylene sheet, and is fixed to the back cushion 18 by sewing along the left and right edges and the upper edge of the back surface of the back cushion 18.

[0027] The upper edge of the cover member 30 is provided with a plurality of engagement holes (engaged portions) 30a aligned in the left-right direction. These engagement holes 30a are hooked onto a plurality of engagement protrusions (engaging portions) 31 protruding from the upper front surface of the back shell 17, so that the upper portion of the back cushion 18 is attached to the back shell 17 without being misaligned. The engagement holes 30a of the cover member 30 and the engagement protrusions 31 of the back shell 17 that engage with each other may have a convex-concave relationship inversely. For example, the back shell 17 may be provided with a concave- or hole-shaped engagement portion, and the cover member 30 may be provided with a convex- or claw-shaped engaged portion that engages with the engagement portion.

[0028] By covering the openings 26 between adjacent vertical ribs 24 and horizontal ribs 25 with the cover member 30, the user can be made less aware of the presence of the vertical ribs 24 and horizontal ribs 25, so that the seating comfort can be improved and the feeling of use can be improved with the simple configuration of interposing the cover member 30 between the front surface of the back shell 17 and the back cushion 18. In addition, even if low-density slab urethane or the like is used for the back cushion 18, the discomfort caused by the vertical ribs 24 and horizontal ribs 25 can be made less noticeable, which has the advantage of reducing costs.

[0029] Furthermore, when a user sitting on the seat 3 leans against the backrest 4, the cover member 30 distributes the force applied to the back surface of the back cushion 18 by the vertical ribs 24 and horizontal ribs 25. This prevents the force from concentrating on the back surface of the back cushion 18 along the rib shape, reducing deterioration of the back cushion 18. The cover member 30 also prevents the rib shape of the ribs 24, 25 from being transferred to the back surface of the back cushion 18, and prevents the rib shape of the ribs 24, 25 from protruding through the upholstery material 19a (skin material 19) through the back cushion 18 even if the elastic force of the back cushion 18 decreases due to aging or the like, thereby maintaining the appearance of the backrest 4.

[0030] In this way, by providing the cover member 30 with the function of preventing the back cushion 18 from shifting out of position and the function of blocking the openings 26 between adjacent vertical ribs 24 and horizontal ribs 25, it is possible to suppress increases in costs without increasing the number of parts.

[0031] A laterally elongated lower edge member 32 made of a plastic sheet is attached by sewing or the like to the lower edge of the back of the back cushion 18. The lower edge member 32 is provided with a plurality of engagement holes 32a aligned in the left-right direction, and these engagement holes 32a are hooked onto a plurality of engagement protrusions 33 protruding from the lower front surface of the back shell 17, so that the lower portion of the back cushion 18 is attached to the back shell 17 without being misaligned.

[0032] In this embodiment, the lower edge member 32 is provided in a horizontally long band shape along the lower edge of the back cushion 18, but the upper edge of the lower edge member 32 may be extended upward so that the lower edge member 32 covers the opening 26 between the vertical rib 24 and the horizontal rib 25 at the lower part of the back shell 17. In this case, the lower edge member 32 may overlap the lumbar support body 102. The lumbar support device 101 is an optional item, and when the lumbar support device 101 is not provided on the backrest 4, the recess (lock mechanism attachment part 46) for accommodating the lock mechanism 104 provided on the front surface of the back shell 17 is covered by the cover body 111 as shown in FIG. 17(C).

[0033] 5 and 7, the left and right edge regions 27a of the back portion 27 of the back shell 17 formed by the back surface of the back member 20 are continuous with the rear end portions 28a of the side portions 28 (the left and right outer surfaces of the side members 21) of the back shell 17. As shown in Fig. 7, in the back shell 17, the left and right edge regions 27a of the back portion 27 are recessed forward so that the rear end portions 28a of the side portions 28 protrude backward.

[0034] An upper edge portion 27b of the back portion 27 is continuous with a rear end portion 29a of an upper surface portion 29 of the back shell 17 formed by the upper surface of the upper member 22. As shown in Figures 6 and 8, the upper member 22 protrudes rearward from an upper portion of the back member 20. In other words, the upper edge portion 27b of the back portion 27 is recessed forward so that the rear end portion 29a of the upper surface portion 29 protrudes rearward.

[0035] In the back shell 17, the left and right ends of the top surface portion 29 are continuous with the upper ends of the side surfaces 28, and the left and right ends of the rear end portion 29a of the top surface portion 29 are continuous with the upper ends of the rear end portions 28a of the side surfaces 28. As a result, the back surface of the back shell 17 is provided with a generally U-shaped ridge portion with a downward opening, where the rear end portions 28a of the left and right side surfaces 28 and the rear end portion 29a of the top surface portion 29 are connected.

[0036] The left and right central regions 27c of the rear portion 27 are located rearward of the rear end regions 28a of the side portions 28 in a side view, and are gently curved from the left and right edge regions 27a toward the left and right central regions 27c, giving the rear portion 27 a convex curve in a rearward direction in a plan view.

[0037] As shown in Figures 6 to 9, the cover material 19 is formed in a bag shape, and the back shell 17 and the back cushion 18 are covered with the bag-shaped cover material 19. The cover material 19 is composed of a cover upholstery material 19a and a back upholstery material 19b, and is formed in a bag shape by sewing together the left and right edge portions and the upper edge portions of the cover upholstery material 19a and the back upholstery material 19b. The stitching portion 19c between the cover upholstery material 19a and the back upholstery material 19b is provided so as to follow the side portion 28 and the upper portion 29 of the back shell 17.

[0038] The covering material 19a is composed of a fabric material 19d and an auxiliary cushion 19e laminated on the back surface of the fabric material 19d. The auxiliary cushion 19e is made of a thin urethane sheet having a thickness of, for example, about 2 to 3 mm, and is laminated on the back surface of the fabric material 19d by sewing or the like.

[0039] The backing material 19b is formed of, for example, a cloth material. The backing material 19b has a hole through which a vertically elongated cylindrical lever guide 105 is inserted, which guides the lever shaft 103a of the operation lever 103 of the lumbar support device 101 in the up-down direction. The lever guide 105 presses the surrounding area of ​​the hole against the back surface portion 27 so as to hide the edge (contour) of the hole in the backing material 19b.

[0040] As shown in Figure 6 etc., a front upholstery edge member 34 and a back upholstery edge member 35 are attached to the lower edge portions of the front upholstery material 19a and the back upholstery material 19b by sewing or the like. The front upholstery edge member 34 is hooked to a locking projection 36 protruding from the back surface of the lower member 23 of the back shell 17. The back upholstery edge member 35 is hooked to a locking projection 42 protruding from an auxiliary plate 41 which is attached to the lower part of the back surface side of the back shell 17 so as to cover the lower member 23.

[0041] As shown in Fig. 5 and Fig. 8, the auxiliary plate 41 is made of synthetic resin, and is provided in the shape of a horizontally long plate that is curved downward convexly in rear view and curved backward convexly in plan view, and is attached to the auxiliary plate holding part 51 provided in a stepped shape at the lower part of the rear part 27 of the back shell 17. At the lower part of the rear part 27 of the back shell 17, a pair of left and right auxiliary plate spindles 52 extending in the left and right direction are provided on the left and right outer sides of the auxiliary plate holding part 51. Meanwhile, the left and right ends of the auxiliary plate 41 are formed with engagement claw parts 43 that fit with the auxiliary plate spindles 52 from the rear side against elasticity. Therefore, the auxiliary plate 41 is provided to be rotatable around the axis of the auxiliary plate spindle 52.

[0042] A pair of left and right engagement holes 53 are provided in the left and right central portion of the auxiliary plate holding portion 51 of the back shell 17. Meanwhile, a pair of left and right locking claw portions 44 corresponding to the left and right engagement holes 53 are provided in the left and right central portion of the auxiliary plate 41. As shown in FIG. 10, the locking claw portion 44 has a substantially V-shaped form in a side view, one of two sides of the V-shape is fixed to the auxiliary plate holding portion 51, while the other side is a free end and is elastically deformable. As shown in FIG. 10(A), by fitting the locking claw portion 44 into the engagement hole 53 of the back shell 17 from the back side, the locking portions 44a provided on the left and right edges of the free end of the locking claw portion 44 engage with the left and right engagement portions 53a provided in the engagement hole 53, and the auxiliary plate 41 is held by the back shell 17.

[0043] When attaching the covering material 19 to the back shell 17, the bag-shaped covering material 19 is placed over the top of the back shell 17, and the lower part of the covering material 19a is wrapped around the lower peripheral edge of the lower member 23 to hook the covering edge member 34 to the locking projection 36. The left and right engagement claws 43 of the auxiliary plate 41 are connected to the auxiliary plate support shaft 52 of the back shell 17, and the lower part of the back covering material 19b is wrapped around the lower peripheral edge of the auxiliary plate 41 to hook the back covering edge member 35 to the locking projection 42, as shown in FIG. 10(B). Thereafter, the auxiliary plate 41 is rotated toward the auxiliary plate holding portion 51 to fit the engagement claws 43 into the engagement holes 53, and the auxiliary plate 41 is fixed to the auxiliary plate holding portion 51 (see FIG. 10(A)). As a result, the covering material 19 is held taut on the back shell 17.

[0044] As shown in Fig. 7, the left and right edge portions 27a of the back portion 27 of the back shell 17 are continuous with the rear end portions 28a of the side portions 28 and are recessed forward, so that the rear end portions 28a of the side portions 28 protrude backward. As a result, the backing material 19b does not come into contact with the forward-facing recessed left and right edge portions 27a of the back portion 27, so that the backing material 19b is likely to have clear corners in the portion covering the boundary between the side portions 28 and the back portion 27 of the back shell 17.

[0045] In addition, in the back shell 17, the upper edge portion 27b of the back surface portion 27 is recessed forward so that the rear end portion 29a of the upper surface portion 29 protrudes backward, and therefore the corners of the lining material 19b are easily visible in the portion of the lining material 19b covering the boundary between the upper surface portion 29 and the back surface portion 27 of the back shell 17. Furthermore, the chair of this embodiment is provided with a pressing member 37 that presses the lining material 19b against the upper edge portion 27b of the back surface portion 27, thereby emphasizing the corners of the lining material 19b along the rear end portion 29a of the upper surface portion 29.

[0046] 1, 2, 6, 11 and 12, etc., a pressing member 37 is provided in the left-right central area of ​​the upper part of the back side of the backrest 4, which presses the back upholstery material 19b (skin material 19) against the upper edge area 27b of the back part 27 of the back shell 17. The pressing member 37 is long from left to right and has a generally L-shaped form in side cross section, and is attached to the upper edge area 27b of the back part 27 with a handle 37a provided on the rear edge protruding downward.

[0047] 11 and 12, the retaining member 37 is attached to an option mounting portion 61 formed in an upward stepped position at the left-right central portion of the upper edge portion 27b of the back surface portion 27 of the back shell 17. The option mounting portion 61 has three engagement holes 62 aligned in the left-right direction and opening forward and backward, a skin material retaining portion 63 protruding rearward below the engagement holes 62, and four screw insertion holes 64 provided between adjacent engagement holes 62 and on the left and right outer sides of the engagement holes 62 and opening in the vertical direction. A nut 66 is disposed in a nut holding portion 65 provided above the screw insertion hole 64 in the upper member 22 of the back shell 17.

[0048] Three engagement claws 38 protrude forward from the upper part of the holding member 37, and engage with engagement holes 62 of the option mounting portion 61. Left and right screw insertion holes 39 open in the vertical direction at the left and right edges of the holding member 37.

[0049] The retaining member 37 is fixed to the option mounting part 61 by sandwiching the backing material 19b with left and right screws 40 which are inserted from below through the screw insertion holes 39 and screw insertion holes 64 and screwed into nuts 66. The backing material 19b has holes formed in the locations corresponding to the four screw insertion holes 64 of the option mounting part 61 and the locations corresponding to the three engagement claws 38 of the retaining member 37.

[0050] When attaching the pressing member 37, the engaging claws 38 are engaged with the engaging holes 62 of the option mounting part 61 through the holes in the backing material 19b, and the pressing member 37 is pressed against the option mounting part 61 with the backing material 19b interposed therebetween so that the screw insertion holes 39 are aligned with the screw insertion holes 64 of the option mounting part 61. Then, the screws 40 are screwed into the nuts 66 to secure the pressing member 37 to the option mounting part 61.

[0051] As a result, the upper part of the lining material 19b is pressed against the option mounting portion 61 provided on the upper edge portion 27b by the front edge portion 37b and the upper surface portion 37c of the pressing member 37, so that the corners of the lining material 19b covering the rear end portion 29a of the upper surface portion 29 of the back shell 17 can be clearly defined and emphasized. Note that in the upper edge portion 27b of the back surface portion 27, at the left and right edge portions away from the option mounting portion 61, the lining material 19b is slightly raised from the upper edge portion 27b as shown in Fig. 11(B), but since the upper edge portion 27b is recessed forward, a clear corner appears in the part of the lining material 19b covering the rear end portion 29a of the upper surface portion 29.

[0052] Furthermore, even if the pressing member 37 is not provided, the upper edge portion 27b of the back portion 27 of the back shell 17 is concave forward so that the rear end portion 29a of the top surface portion 29 protrudes rearward, so that the lining material 19b does not come into contact with the upper edge portion 27b, and the corners of the lining material 19b are likely to protrude along the rear end portion 29a of the top surface portion 29 of the back shell 17.

[0053] In this embodiment, the pressing member 37 is provided with a handle 37a that extends downward so that a person can hold it by hand, but it is also possible to attach optional items such as a hanger or a headrest to the option attachment portion 61. The optional items can then be used to press the lining material 19b against the upper edge portion 27b of the back surface portion 27 of the back shell 17, so that the corners of the lining material 19b can be clearly and emphatically brought out along the rear end portion 29a of the upper surface portion 29.

[0054] (3) Connection structure between the back shell and the tilting frame Next, a connecting structure between the back shell 17 and the tilting frame 5 will be described with reference mainly to FIGS.

[0055] For example, as shown in Fig. 13, a main recess 75 that opens forward is formed on the front surface 12 of the base 8 of the tilting frame 5, and a number of reinforcing ribs 76 extending vertically and horizontally are formed inside the main recess 75. Also, a center recess 77 is formed in the left-right intermediate portion of the base 8 (the left-right intermediate portion of the main recess 75) for mounting the rear end of a back angle fixing gas cylinder 33a (see Figs. 1(B) and 2) for fixing the tilting frame 5, which can be tilted backward, at any rearward tilt angle. The center recess 77 is surrounded by ribs.

[0056] As also shown in Figure 13, a pair of left and right positioning protrusions 84 are provided on the lower member 23 of the back shell 17 protruding rearward, while the base 8 of the tilting frame 5 is formed with a positioning hole 78 (see also Figure 16(A)) into which the positioning protrusions 84 fit from the front. The positioning hole 78 is structured to be surrounded by a rib. The positioning protrusion 84 has a fairly large protruding dimension, and fits into the positioning hole 78 with almost no clearance, so that the back shell 17 is attached to the tilting frame 5 in a state where it can firmly support the rearward load.

[0057] Furthermore, a side recess 79 that opens forward and upward is formed at the upper end of the back support column 7 of the tilting frame 5, while a side protrusion 80 that fits snugly into the side recess 79 is formed at the left and right upper ends of the lower member 23 of the back shell 17, and the side protrusion 80 and the side recess 79 are fastened together with a bolt 88 and a nut 89. The positioning protrusion 84 is inclined in substantially the same direction as the axial direction O3 of the back support column 7 (see FIG. 1(B)).

[0058] The side recess 79 and the side protrusion 80 are shaped like a truncated pyramid, and the side protrusion 80 has a horizontal pocket hole 81 in which the nut 89 is held non-rotatably, as well as a bolt insertion hole 82 communicating with the pocket hole 81, while the bottom plate of the side recess 79 has a bolt insertion hole 85.

[0059] As can be seen from Figure 14, the lower part of the side recess 79 of the back support part 7 of the tilting frame 5 is a back recess 83 that opens rearward, and the bolt 88 is inserted from the auxiliary recess 83a that is continuous with the back recess 83 into the bottom plate of the side recess 79.

[0060] The back shell 17 is positioned by the fit between the positioning protrusion 84 and the positioning hole 78, so it is firmly fixed to the tilting frame 5 even when fastened with only the two bolts 88 on the left and right. In addition, since the side protrusion 80 and the side recess 79 are in a truncated triangular pyramid shape, when the bolt 88 is tightened, the side protrusion 80 is firmly attached to the side recess 79. As a result, the back shell 17 is firmly fixed to the tilting frame 5 by the two bolts 88 without any rattling.

[0061] As shown in FIG. 16, in a state in which the back shell 17 and the tilting frame 5 are connected, the back portion 27 (back member 20) of the back shell 17 is disposed above the inclined inner peripheral surface 13 of the tilting frame 5.

[0062] 8 and 9, a bottom surface portion 71 is provided at the lower part of the back surface of the spine shell 17, which extends forward from the lower edge of the auxiliary plate holding portion 51 provided at the lower part of the back surface portion 27 and connects to the upper edge of the lower member 23. The bottom surface portion 71 is provided to extend in the left-right direction, and is curved so that the left-right central portion is downwardly convex.

[0063] Four backward tilt prevention protrusions 72 protruding downward are provided on the bottom surface portion 71. The backward tilt prevention protrusions 72 are provided on the left and right outer sides of the engagement holes 53, two on each side so as to sandwich the positioning protrusion 84 in a plan view. The backward tilt prevention protrusions 72 include an inclined surface portion 73 disposed opposite the inclined inner peripheral surface 13 of the tilting frame 5.

[0064] As shown in Fig. 16(B), when the back shell 17 and the tilting frame 5 are connected, the inclined surface portion 73 of the tilt-prevention protrusion 72 provided on the back shell 17 is disposed opposite the inclined inner peripheral surface 13 of the tilting frame 5, thereby suppressing the backward tilt of the back shell 17 relative to the tilting frame 5 and firmly supporting the rearward load on the back shell 17. As shown in Figs. 2 and 16, when the backrest 4 is viewed from the rear side, the tilt-prevention protrusion 72 and the inward ridge 9 of the tilting frame 5 are hidden by the auxiliary plate 41 covered with the backing material 19b, which provides a good appearance.

[0065] As described above, the back shell 17 is positioned by the engagement of the positioning protrusion 84 with the positioning hole 78. As shown in Fig. 16(A), the upper surface of the positioning protrusion 84 and the top surface of the positioning hole 78 facing the upper surface suppress the forward tilt of the back shell 17 relative to the tilting frame 5, and the lower surface of the positioning protrusion 84 and the bottom surface of the positioning hole 78 facing the lower surface suppress the backward tilt of the back shell 17 relative to the tilting frame 5. In addition, as shown in Fig. 16(B), the backward tilt prevention protrusion 72 disposed opposite the inclined inner peripheral surface 13 of the tilting frame 5 further firmly suppresses the backward tilt of the back shell 17.

[0066] In this way, by sandwiching the tilting frame 5 between the upper and lower protrusions (the positioning protrusion 84 and the backward tilt prevention protrusion 72) provided on the back shell 17, the backward tilt of the back shell 17 relative to the tilting frame 5 is appropriately suppressed. As a result, for example, when a seated person leans against the backrest 4, the backrest 4 and the tilting frame 5 tilt backward and a backward load is applied to the backrest 4, the connection strength between the tilting frame 5 and the back shell 17 can be improved and the durability of the backrest 4 can be improved.

[0067] (4) Back cover mounting structure The tilting frame 5 is formed with side recesses 79 that open forward and back recesses 83 that open backward. Therefore, when the base 8 and back support 7 of the tilting frame 5 are viewed as a whole, the back recess 83 that opens backward is present between the side recesses 79 that open forward and the main recess 75.

[0068] 15(A), the back recess 83 is generally rectangular and tapered so that the cross-sectional area decreases toward the bottom, and a step 97 of a certain width is formed at the opening edge. The step 97 extends to the bottom of the back recess 83.

[0069] The back cover 16 that attaches to the back recess 83 is designed to fit into the step portion 97 of the tilting frame 5, and is attached to the tilting frame 5 by an upward-facing first engagement claw 90, a pair of second engagement claws 91 that fit into the back recess 83 of the back support portion 7, and two third engagement claws 92 that protrude forward below the back recess 83.

[0070] A pair of first engagement holes 93 into which the first engagement claws 90 fit and engage are formed at the upper end of the back support column 7 of the tilting frame 5, a second engagement hole 94 into which the second engagement claws 91 engage after elastic deformation is formed inside the back recess 83 of the back support column 7, and a pair of third engagement holes 95 into which the third engagement claws 92 engage after elastic deformation are formed below the back recess 83. The third engagement holes 95 are formed in the step portion 97.

[0071] The first engagement hole 93 is bag-shaped and opens only rearward, and the first engagement claw 90 engages with the first engagement hole 93 by sliding it upward. Therefore, the upper end of the back cover 16 is held so that it cannot slip upward or be raised backward. On the other hand, the second engagement hole 94 and the third engagement hole 95 open to the front and rear. The pair of second engagement claws 91 have hook portions with different postures, and the directions in which they elastically deform and fall are different. Therefore, there is a high prevention effect against coming off. The hook portions of the pair of third engagement claws 92 face the same direction.

[0072] In addition, an auxiliary protrusion 96 that fits into the third engagement hole 95 is provided below the third engagement claw 92 and protrudes forward. Therefore, the back cover 16 is held by the first engagement claw 90 so as not to move upward, and by the auxiliary protrusion 96 so as not to move downward. Therefore, the back cover 16 is firmly attached without any rattle. In addition, the back cover 16 fits into the step 97 of the tilting frame 5, and the surface of the back cover 16 and the inclined outer peripheral surface 14 of the tilting frame 5 are flush with each other, which provides an aesthetic appearance and makes it difficult to be pulled up.

[0073] Although detailed description is omitted, it is also possible to attach an armrest member to the back recess 83 instead of the back cover 16. In this embodiment, the back recess 83 for attaching the armrest member is used to fasten the back shell 17 to the tilting frame 5 with a bolt 88. That is, the back recess 83 for attaching the armrest 15 is used as a space for arranging the bolt 88 for fixing the back shell 17. Therefore, the head of the bolt 88 is not exposed, which is aesthetically pleasing.

[0074] (5) Mounting structure of the cover body to the lock mechanism mounting part 4, 17(B), etc., a lock mechanism attachment section 46 to which a lock mechanism 104 of a lumbar support device 101 can be attached is provided at a lower central position on the left and right side of the front surface of the back shell 17. The backrest 4 can be selected to have the lumbar support device 101 or not, and in the case where the lumbar support device 101 is not provided, the lock mechanism attachment section 46 is covered by a cover body 111. The cover body 111 of this embodiment is one aspect of the cover member of the present invention.

[0075] The lock mechanism attachment portion 46 is composed of multiple ribs erected facing forward on the front portion of the rear member 20, and has a frame-shaped rib 47 that is generally vertically elongated and rectangular when viewed from the front, and multiple stepped ribs 48 extending vertically and horizontally that are stepped down within the frame-shaped rib 47. The frame-shaped rib 47 is provided to have approximately the same height as the surrounding vertical ribs 24 and horizontal ribs 25, and the tip end of the frame-shaped rib 47 is connected to the tip end of the surrounding vertical ribs 24 and horizontal ribs 25 in a flush manner.

[0076] In the specification where the lumbar support device 101 is attached to the backrest 4, the lock mechanism 104 having a substantially rectangular frame shape is disposed inside the frame rib 47 and supported by the stepped-down rib 48. The left and right lower corners of the lock mechanism 104 are fitted into engagement parts 49 that open inwardly and upwardly on the left and right sides and are provided at the upper end of the stepped-down rib 48 at positions close to the left and right lower corners of the frame rib 47. In addition, an upwardly protruding flange part 104a provided at the left and right central part of the upper end of the lock mechanism 104 is fixed by a screw 106 inserted into an attachment hole 50a of an attachment surface part 50 provided at the upper end of the stepped-down rib 48 at a position close to the top of the frame rib 47. In this way, the lock mechanism 104 is attached to the lock mechanism attachment part 46 so as not to come off.

[0077] On the other hand, in the case where the lumbar support device 101 is not provided on the backrest 4, as shown in Fig. 17(C) and Fig. 17, a cover body 111 is attached to the lock mechanism attachment portion 46. The cover body 111 has a cover main body 112 in the shape of a substantially rectangular plate that is slightly smaller than the inner circumference of the frame-shaped rib 47 when viewed from the front, a plurality of vertical and horizontal support ribs 113 erected on one surface (rear surface) of the cover main body 112, an upper locking claw 114, and left and right lower locking claws 115.

[0078] The cover body 111 is fitted into the lock mechanism mounting portion 46, and the upper locking claws 114 of the cover body 111 engage with the mounting holes 50a of the lock mechanism mounting portion 46 against elasticity, and the left and right lower locking claws 115 engage with the left and right engagement portions 49 against elasticity. The upper and lower edges of the cover main body 112 and the tips of the support ribs 113 (particularly the support ribs 113 extending in the left-right direction) come into contact with or are close to the tips of the stepped-down ribs 48 (particularly the stepped-down ribs 48 extending in the up-down direction), restricting the movement of the cover body 111 toward the rear member 20. In this way, the cover body 111 is attached to the lock mechanism mounting portion 46 so as to close the opening of the frame-shaped rib 47 so as not to come off.

[0079] That is, the cover body 111 closes the opening between the adjacent ribs 47, 48, and is interposed between the front surface of the back shell 17 and the cushion 18. This makes it difficult for the user to feel the presence of the frame-shaped rib 47 and the stepped-down rib 48, improving the comfort of sitting with a simple configuration and improving the feeling of use.

[0080] (6) Summary 3 and 6, the chair of the above embodiment has a backrest 4 with a back cushion 18 disposed on the front surface of a back shell 17. A plurality of ribs 24, 25 are provided on the front surface of the back shell 17, and a cover member 30 is interposed between the front surface of the back shell 17 and the back cushion 18 to cover an opening 26 between adjacent ribs 24, 25.

[0081] In this way, by covering the opening 26 between the adjacent ribs 24, 25 formed on the front surface of the back shell 17 with the cover member 30, the user can be made less aware of the presence of the ribs 24, 25, thereby improving the comfort of sitting and the usability with a simple configuration.

[0082] In the above embodiment, the cover member 30 is made of a plastic sheet, so that the cover member 30 can be formed at low cost and light weight, and the seating comfort can be improved without impairing the appearance of the backrest 4. The cover member 30 that is interposed between the back cushion 18 and the ribs 24, 25 to close the opening 26 is not limited to a plastic sheet, and can be made of a material that has a smaller compressibility (ease of volume change) than the back cushion 18, such as a nonwoven fabric sheet or cardboard. If a material that has a smaller compressibility than the back cushion 18 and is flexible, such as a plastic sheet, nonwoven fabric sheet, or cardboard, is used as the cover member 30, the cover member 30 can be easily arranged along the shape of the front surface of the back shell 17 (the surface along the tip portions of the ribs 24, 25) even if the front surface is curved.

[0083] As shown in FIGS. 3, 6 and 11, the cover member 30 is joined to the back cushion 18 and has an engagement hole 30a that engages with an engagement protrusion 31 provided on the front surface of the back shell 17.

[0084] According to this configuration, the back cushion 18 and the cover member 30 are joined together, for example, by sewing or gluing, and the engagement hole 30a of the cover member 30 is engaged with the engagement protrusion 31 of the back shell 17, making it easier to align the back cushion 18 and the cover member 30 when attaching them to the back shell 17, improving work efficiency, and preventing the back cushion 18 and the cover member 30 from shifting out of position during use, maintaining a comfortable sitting experience.

[0085] As shown in FIG. 17(C), by covering the opening between adjacent ribs 47, 48 formed on the front surface of the back shell 17 with a cover body 111, the user is less likely to feel the presence of the ribs 47, 48, and the simple configuration improves seating comfort and usability.

[0086] 2, the chair of the above embodiment includes a backrest 4 covered with a skin material 19 from at least the side surface portions 28 to the back surface portion 27 of a back shell 17 having a back surface portion 27 extending in the left-right direction and side surface portions 28 extending in a direction intersecting the left-right direction in a plan view. The left and right edge portions 27a of the back surface portion 27 are recessed forward so that rear end portions 28a of the side surface portions 28 of the back shell 17 protrude backward.

[0087] With this configuration, the skin material 19 stretched from the side portion 28 to the back portion 27 of the back shell 17 does not come into contact with the forward-facing concave left and right edge portions 27a of the back portion 27 of the back shell 17 (see FIG. 7), so that the skin material 19 tends to have clear corners in the portions covering the boundaries between the side portions 28 and the back portion 27 of the back shell 17 (portions covering the rear end portions 28a of the side portions 28). By providing corners in the skin material 19 covering the side portions and the back portion of the backrest 4, a firm appearance can be obtained for the backrest 4 when viewed from the back side, improving the design.

[0088] As shown in FIG. 2 , the skin material 19 covers the upper surface portion 29 of the back shell 17 through to the back surface portion 27, and in the back shell 17, the upper edge portion 27b of the back surface portion 27 is recessed forward so that the rear end portion 29a of the upper surface portion 29 protrudes rearward, and the left and right ends of the rear end portion 29a of the upper surface portion 29 are continuous with the upper ends of the rear end portions 28a of the side portions 28.

[0089] With this configuration, the skin 19 can have corners even in the portion covering the boundary between the upper surface portion 29 and the back surface portion 27 of the back shell 17 (the portion covering the rear end portion 29a of the upper surface portion 29). As shown in Fig. 2(A), the skin 19 can have continuous corners from the left and right edges to the upper edge of the back surface of the backrest 4, and the backrest 4 covered with the skin 19 can have an appearance with excellent design.

[0090] 2, 11 and 12, a pressing member 37 for pressing the covering material 19 against the upper edge portion 27b of the back surface portion 27 is provided.

[0091] This configuration emphasizes the corners of the skin 19 covering the rear end 29a of the upper surface 29 of the back shell 17. The retaining member 37 can be realized by, for example, an optional item such as a hanger or a headrest, or a cover member for when no optional item is attached. The retaining member 37 is also provided with a handle 37a on which a person can hang his or her hand.

[0092] As shown in Figure 2 (B) and Figures 6 to 8, the back portion 27 of the spine shell 17 may be configured so that the left and right central regions 27c are located rearward of the rear end regions 28a of the side portions 28 in a side view, and the back portion 27 may be gently curved from the left and right edge regions 27a toward the left and right central regions 27c.

[0093] With this configuration, in the back shell 17, the left and right central regions 27c of the back portion 27 are located rearward of the rear end portions 28a of the side portions 28, and the back portion 27 is given a backward-facing convex curve, so that the above-mentioned corners are formed in the skin material 19 while the portion covering the back portion 27 of the back shell 17 is given a rounded curve, thereby forming a backrest 4 that has a firm appearance while still giving a soft impression.

[0094] The present invention can be embodied in various ways other than the above. For example, the cover member 30 may cover the entire front surface of the back shell 17 (the entire area where the ribs 24, 25 are formed), and the cover member 30 and the lower edge member 32 may be formed from a single sheet. In this case, in a configuration in which the backrest 4 is provided with the lumbar support device 101 as in the above embodiment, the cover member 30 comes into contact with the front surface of the lumbar support body 102. By forming the cover member 30 from a material (such as a plastic sheet, a nonwoven fabric sheet, or cardboard) that produces a smaller frictional force between the cover member 30 and the lumbar support body 102 than the back cushion 18 (such as a urethane sheet), the lumbar support body 102 can be moved up and down smoothly and noise caused by frictional vibration can be reduced, improving the comfort of use.

[0095] The cover member 30 does not have to be joined to the back cushion 18. The extending direction of the ribs is not limited to the up-down direction (vertical ribs 24) or the left-right direction (horizontal ribs), but may be oblique, or may be curved when viewed from the front.

[0096] In addition, an auxiliary plate 41 having a locking protrusion 42 for hooking the back upholstery edge member 35 attached to the lower edge of the back upholstery material 19b of the skin material 19 is rotatably attached to the lower part of the back surface of the back shell 17, but the protrusion for hooking the back upholstery edge member 35 may be integrally formed on the back shell 17. [Explanation of symbols]

[0097] 4 Backrest 17 Back Shell 18 Back cushion (cushion) 19 Skin material 24 Vertical rib (rib) 25 Horizontal rib (rib) 30 Cover member 30a Engagement hole (engaged part) 31 Engagement protrusion (engagement part) 47 Frame rib (rib) 48 Step-down rib (rib) 111 Cover body (cover member)

Claims

1. A chair having a backrest with a cushion disposed on a front surface of a back shell, A plurality of ribs are provided on a front surface of the back shell, A cover member is interposed between the front surface of the back shell and the cushion to close the opening between the adjacent ribs, The cover member is joined to the cushion and has an engaged portion that engages with an engaging portion provided on the front surface of the back shell. chair.

2. The cover member is formed of a plastic sheet, a nonwoven fabric sheet, or cardboard.

2. The chair of claim 1.

3. The cover member is fixed to the cushion by being sewn to an edge portion of the cushion.

3. A chair according to claim 1 or 2.

Images