Chair and upholstery member mounting structure

Abstract

To provide a chair having a suitable constitution capable of supporting a stretch member on a corner part of an upper frame shape part constituting a backrest; and to provide a fitting structure of the stretch member.SOLUTION: In a chair formed by stretching a stretch member P on an upper frame shape part wa constituting a backrest E: right and left side frame materials 2 and an upper frame material 3 of the upper frame shape part wa include a stretch member fitting groove mz which is opened outward and capable of holding the end of the stretch member P; an open hole ka is provided on a corner part K of the upper frame shape part wa; and the stretch member P includes a locking member p3 capable of passing through the open hole ka from the outside to the inside, and lockable with an opening kc under the open hole ka.SELECTED DRAWING: Figure 31

Description

[Technical Field]

[0001] The present invention relates to a chair and an attachment structure for an upholstery member. [Background technology]

[0002] BACKGROUND ART Chairs have been known that have a backrest in which an upholstery member is stretched over a frame-shaped portion of a back frame (see, for example, Patent Document 1).

[0003] The upholstery of the backrest of this type of chair comprises an upholstery body made mainly of mesh fabric and a strip of synthetic resin sewn to the end of the upholstery body. The strip, together with the end of the upholstery body, is pushed into an upholstery attachment groove formed in the frame, allowing the upholstery to be stably held against the frame.

[0004] However, since most belt-shaped members extend in a substantially straight line, they are difficult to insert into the tension member mounting grooves formed at the corners of the frame-shaped portion.

[0006] The above situation also applies when the upholstery member is supported at the corners of the frame-like portion that constitutes the seat. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-217394 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above-mentioned circumstances, and at least a backrest is provided. Back frame The present invention provides a chair having a suitable structure that allows upholstery members to be supported on corners of the chair, and a mounting structure for the upholstery members. [Means for solving the problem]

[0009] That is, the present invention has the following configuration.

[0010] The invention described in claim 1 is a chair in which an upholstery member is attached to the back frame of the backrest, the back frame having left and right side frame members extending in the vertical direction, and an upper frame member extending in a direction intersecting the left and right side frame members and connecting the upper ends of the left and right side frame members, corners being formed between the left and right side frame members and the upper frame member, the left and right side frame members and the upper frame member having upholstery member mounting grooves that open outward and can hold the ends of the upholstery member, and the corners having through holes that extend diagonally between the outside and inside of the back frame and are positioned gradually inward as they go downward, the upholstery member being: a tension member body mainly made of fabric and capable of forming a backrest surface; a belt-shaped member extending in a substantially straight line, sewn to the outer edge of the tension member body, and held in the tension member mounting grooves of the left and right side frame members and the top frame member; a locking member that passes through the through hole from the outside to the inside and can be locked to the opening of the through hole; The belt-shaped member is not sewn to the portion of the tension member body corresponding to the corner, and the fastening member is formed by a separate member attached to the portion of the tension member body corresponding to the corner, or by folding and laminating a belt-shaped fabric extending from the portion of the tension member body corresponding to the corner. It's a chair.

[0015] Claim 2 The invention described in claim 1 is a chair in which the locking member is an expandable mass and is set to a size that allows it to be temporarily compressed when passing through the through hole.

[0017] Claim 3 The invention described in is an attachment structure for a tension member to a back frame that constitutes a backrest, the back frame having left and right side frame members that extend in the vertical direction, and an upper frame member that extends in a direction that intersects with the left and right side frame members and connects the upper ends of the left and right side frame members, and corners are formed between the left and right side frame members and the upper frame member, and the corners are provided with through holes that extend obliquely so as to penetrate between the outside and inside of the back frame and to be positioned gradually inward as they go downward, and the tension member is a tension member body mainly made of fabric and capable of forming a backrest surface; a belt-shaped member extending in a substantially straight line, sewn to the outer edge of the tension member body, and held in the tension member mounting grooves of the left and right side frame members and the top frame member; a locking member that passes through the through hole from the outside to the inside; the belt-shaped member is not sewn to the portion of the tension member body corresponding to the corner, and the fastening member is formed by a separate member attached to the portion of the tension member body corresponding to the corner, or by folding and laminating a belt-shaped fabric extending from the portion of the tension member body corresponding to the corner,This is an attachment structure for a tension member in which the locking member that passes through the through hole is locked at or near the opening of the through hole and prevented from returning. [Effects of the Invention]

[0018] As described above, according to the present invention, at least the backrest is Back frame This makes it possible to provide a chair having a suitable configuration that allows an upholstery member to be supported on the corners of the chair, and an attachment structure for the upholstery member. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] 15 is a cross-sectional view taken along line AA in FIG. 14. [Figure 16] 15 is a cross-sectional view taken along line BB in FIG. 14. [Figure 17]FIG. [Figure 18] FIG. 4 is a plan view showing the positional relationship between the seat support and the support member (seat body) in the embodiment. [Figure 19] FIG. 4 is a plan view showing the positional relationship between the seat support and the support member (seat body) in the embodiment. [Figure 20] FIG. 4 is a left side view showing the positional relationship between the seat support and the support member (seat body) in the embodiment. [Figure 21] FIG. 4 is a left side view showing the positional relationship between the seat support and the support member (seat body) in the embodiment. [Figure 22] FIG. [Figure 23] FIG. [Figure 24] FIG. [Figure 25] FIG. [Figure 26] FIG. [Figure 27] FIG. [Figure 28] FIG. 4 is a front view illustrating the structure of the tension member in the embodiment. [Figure 29] FIG. 4 is a partially enlarged front view illustrating the structure of the tension member in the embodiment. [Figure 30] Cross-sectional view taken along line CC in Figure 29. [Figure 31] FIG. 2 is a partially enlarged front view of the tension member in the same embodiment, with a portion of the tension member cut away. [Figure 32] FIG. 4 is a partially enlarged plan view of the restriction mechanism in the embodiment. [Figure 33] Cross-sectional view taken along line DD in Figure 32. [Figure 34] FIG. 4 is a partially enlarged perspective view of the restriction mechanism in the embodiment. [Figure 35] A plan view of the lower frame material cover (cover body) in the same embodiment. [Figure 36] Front view of the lower frame material cover (cover body) in the same embodiment. [Figure 37]A bottom view of the lower frame material cover (cover body) in the same embodiment. [Figure 38] A rear view of the lower frame material cover (cover body) in the same embodiment. [Figure 39] Cross-sectional view taken along line EE in FIG. 3. [Figure 40] Cross-sectional view taken along line FF in Figure 3. [Figure 41] A cross-sectional view corresponding to Figure 39 for explaining the posture of the lower frame material cover (cover body) in this embodiment. [Figure 42] A cross-sectional view corresponding to Figure 39 for explaining the posture of the lower frame material cover (cover body) in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, one embodiment of the present invention will be described with reference to FIGS.

[0021] In this embodiment, the present invention is applied to a swivel chair for business use (hereinafter simply referred to as "chair") that is suitable for use in an office or the like.

[0022] The chair comprises legs A, a support base B rotatably supported relative to the legs A, a seat C disposed on the support base B, a backrest E supported via a back support D relative to the support base B so as to be able to tilt backward, and a lumbar support R attached to the backrest E.

[0023] The chair is provided with a tilt-back degree setting mechanism X, which can set the degree to which the backrest E can be tilted backward, between the support base B and the back support D. The chair is also provided with a lower cover body I, which covers the underside of the rotating member x2 that constitutes the tilt-back degree setting mechanism X and the back support D.

[0024] Each component of the chair will be described in detail below.

[0025] <<Legs A>> The leg A includes a plurality of leg blades a1 each having a caster a11 at its tip, and leg supports a2 erected at the base ends of the leg blades a1.

[0026] <<Support base B>> The support base B supports the seat C and backrest E. The support base B is mainly composed of a support base body 1, which is an upwardly open, one-piece molded product made of synthetic resin. The support base body 1 is connected to the upper end of the leg support a2.

[0027] The support base B has a front shaft support portion MS in the shape of an elongated hole that can slidably support the front shaft jk2. The support base B can support the front part of the seat C via the front shaft jk2.

[0028] A reaction force adjustment lever 11 is rotatably supported on the support base main body 1, and can adjust the reaction force against the backward tilting movement of the backrest E by expanding and contracting the reaction force spring HG housed within the support base main body 1.

[0029] <<Location C>> The seat C is disposed on the support base B. The seat C includes a seat support c1 made of synthetic resin, also called an outer shell, a seat body c2 having a seating surface and supported by the seat support c1, and an operating member c3 that is supported on the seat body c2 so as to be movable up and down between an upper position and a lower position, and that can slide the seat body c2 in the front-to-rear direction when in the upper position.

[0030] Between the seat support c1 and the seat body c2, there are provided a plurality of restriction mechanisms V that restrict the range of movement of the seat body c2 in the front-to-rear direction. The restriction mechanisms V are provided at four locations in total, two at the front and two at the back between the seat support c1 and the seat body c2.

[0031] The front part of the seat C is supported movably relative to the support base B via the front axle jk2. The center part of the seat C in the front-to-rear direction is supported on the support base B via the back support member D, which holds the rear axle jk3. The center part of the seat C in the front-to-rear direction is supported rotatably relative to the rear axle jk3.

[0032] <Zauke c1> The seat support c1 has a shell-like shape large enough to support the seat body c2 at its upper portion.

[0033] The seat support c1 has a slightly curved shape with the front part convex toward the rear when viewed from above or from the bottom. The seat support c1 has a curved shape with the rear part convex toward the rear when viewed from above or from the bottom. The seat support c1 has four rounded corners and is generally horizontally rectangular overall.

[0034] As shown in Figures 19 and 21, the seat support c1 can support the seat body c2 so that it can slide back and forth between a front position (F) in which the front part of the seat body c2 protrudes significantly further forward than the front edge of the seat support c1 when viewed from above or from the bottom, and a rear position (N) located behind the front position (F) as shown in Figures 18 and 20.

[0035] The seat support c1 has a seat support body ca that forms a shell-shaped main part capable of supporting the seat body c2 at the top, and four approximately T-shaped retaining projections W that protrude upward from the seat support body ca. The retaining projections W constitute a restriction mechanism V. In this embodiment, the seat support body ca and the retaining projections W are integrally formed from synthetic resin.

[0036] [Base body ca] The seat support main body ca comprises a seat support base c10 having a lower support area L formed on its upper surface that can be attached to the underside of the support member main body c211, a front lower extension wall c11 provided in the left-right center of the front part of the underside of the seat support base c10, left and right lower extension walls c12 provided in pairs on the left and right at the left-right center of the underside of the seat support base c10 and extending downward from both ends of the front lower extension wall c11 toward the rear, and a rear lower extension wall c13 provided in the left-right center of the rear part of the underside of the seat support base c10 and connecting the rear parts of the left and right lower extension walls c12.

[0037] The seat support base c10 has a plurality of exposed ribs extending in the front-rear and left-right directions on its upper surface to ensure rigidity. The upper ends of the ribs erected on the upper surface of the seat support base c10 form a lower support area L that can be brought into contact with and slide against the lower surface of the support member main body c211.

[0038] The lower support area L is a portion against which the lower surface of the support member main body c211 can contact and slide. The lower surface of the support member main body c211 can slide against the lower support area L when the seat body c2 slides in the front-rear direction. The lower support area L has a curved shape so that the center is located lower than the outer parts when viewed from the front and rear.

[0039] Both side edges of the seat holder base c10 extend substantially linearly in the front-rear direction. Upper end portions y1 of both side edges of the seat holder base c10 constitute the uppermost portion of the seat holder main body ca.

[0040] When the seat body c2 is in the rear position (N), the front portion of the upper end y1 at the left and right edge of the seat support base c10 is positioned so as to intersect with the support wall c214 located at the left and right portions cf at the front of the support member c21.

[0041] On the other hand, when the seat body c2 is in the front position (F), the rear portion of the upper end y1 at the left and right edge of the seat support base c10 is positioned so as to intersect with the support wall c214 located at the left and right portions cr at the rear of the support member c21.

[0042] A seat receiving slit cs is provided at the front right portion of the seat receiving base c10, which penetrates vertically and extends in the front-rear direction, in which the operating member c3 is disposed.

[0043] An operating piece CH is pivotally supported on the underside of the front left part of the seat support base c10 in a flapable manner, and acts on a gas spring (not shown) that constitutes the leg support a2, thereby operating the leg support a2 to expand and contract in the vertical direction.

[0044] A rear axle holder ce that can rotatably hold the rear axle jk3 is provided in the center of the lower surface of the seat-receiving base c10 in the front-rear direction. The rear axle holder ce is provided between the left and right lower extension walls c12 of the seat-receiving base c10 in a bottom view.

[0045] [Retaining protrusion W] The retaining projections W constitute the restriction mechanism V. The retaining projections W are erected at four locations on the seat support body ca so as to correspond to the guide portions J provided at four locations on the support member c21. The retaining projections W are erected on the seat support body ca and have a roughly T-shaped appearance when viewed from the front and back.

[0046] The anti-slip protrusion W engages with a guide portion J provided on the support member c21 of the seat body c2, thereby supporting the seat body c2 so that it cannot be separated from the seat holder c1 and positioning the seat body c2 so that it can slide back and forth relative to the seat holder c1.

[0047] The details of the retaining protrusion W that constitutes the restriction mechanism V will be described later.

[0048] <Seat body c2> The seat body c2 is configured to be able to slide in the front-rear direction between a front position (F) and a rear position (N) relative to the seat support c1.

[0049] The seat body c2 comprises a shell-shaped support member c21 whose dimensions in the front-to-back and left-to-right directions are larger than those of the seat support c1, a seat cushion c22 supported by the support member c21 and whose dimensions in the front-to-back and left-to-right directions are larger than those of the support member c21, and a seat upholstery c23 that covers the peripheral edges of the seat cushion c22 and the support member c21 from the outside.

[0050] When the seat body c2 is in the rear position (N), in a plan view or bottom view, the left and right corners cx at the front of the seat support c1 are located further forward than the left and right corners cz at the front of the support member c21.

[0051] In other words, the seat body c2 is configured such that, at the rear position (N), the end y3 at the center of the left-right direction at the front of the support member c21 is located at approximately the same front-to-rear position as the end y4 at the center of the left-right direction at the front of the seat support c1.

[0052] Furthermore, the seat body c2 is configured such that, in the rear position (N), the front end portions y5 of both left and right sides at the front of the support member c21 are positioned rearward of the front end portions y6 of both left and right sides at the front of the seat support c1.

[0053] When the seat body c2 is in the front position (F), the rear edge of the seat holder c1 is located behind the rear edge of the support member c21 in a plan view or a bottom view.

[0054] [Support member c21] The support member c21 is made of synthetic resin and is also called an inner shell. The support member c21 is attached to the underside of the seat cushion c22 and serves to evenly support the weight of the seated person.

[0055] The support member c21 has a curved shape such that the center portion is positioned lower than the outer portions when viewed from the front and rear.

[0056] The support member c21 has a curved shape such that the front portion is convex forward when viewed from above or from the bottom. The support member c21 has a curved shape such that the rear portion is convex backward when viewed from above or from the bottom. The support member c21 has four rounded corners and is generally rectangular in shape with a horizontally elongated shape as a whole.

[0057] In this embodiment, the degree of curvature of the front portion of the support member c21 is set to be larger than the degree of curvature of the front portion of the seat holder c1. The degree of curvature of the rear portion of the support member c21 is set to be approximately the same as or very similar to the degree of curvature of the rear portion of the seat holder c1.

[0058] That is, the outer edge shape of the front portion of the support member c21 is different from the outer edge shape of the front portion of the seat holder c1, while the outer edge shape of the rear portion of the support member c21 is similar to the outer edge shape of the rear portion of the seat holder c1.

[0059] The support member c21 comprises a support member main body c211 disposed in the center in the front-to-back and left-to-right directions, a peripheral wall portion c213 extending outward from the peripheral portion of the support member main body c211 via a step portion c212 and having a lower surface positioned higher than the lower surface of the support member main body c211, and a support wall c214 provided so as to protrude downward around the entire outer peripheral edge of the peripheral wall portion c213.

[0060] The support member main body c211 is shaped like a relatively flat plate and is flexibly deformed when subjected to the weight of a seated person. The support member main body c211 is provided with a plurality of seat center slits c215 extending in the front-rear direction at the center of the front-rear direction and provided in the left-right direction corresponding to the recesses c222 of the seat cushion c22, a guide portion J extending in the front-rear direction and constituting the restriction mechanism V and with which the retaining protrusion W provided on the seat support c1 can engage, and an operation member holding hole c216 extending in the vertical direction and capable of supporting the operation member c3 so that it can move up and down but cannot slip out downward.

[0061] The guide portion J will be described in detail later.

[0062] The peripheral wall portion c213 is located outside the support member main body c211 and disposed above the support member main body c211. A step portion c212 interposed between the support member main body c211 and the peripheral wall portion c213 is intended to position the peripheral wall portion c213 above the support member main body c211. In this embodiment, the step portion c212 is mainly formed by a wall portion erected on the outer peripheral edge of the support member main body c211.

[0063] The peripheral wall portion c213 is disposed so as to surround the outside of the support member main body c211 in a bottom view. The edge y2 of the seat upholstery c23 is disposed on the lower surface side of the peripheral wall portion c213.

[0064] The support member c21 is surrounded by a peripheral wall portion c213, a step portion c212, and a support wall c214 in an approximately downward U-shape, forming a downwardly open space sr that can accommodate the edge y2 of the seat upholstery c23.

[0065] In addition, hooking pieces cn for hooking the edge y2 of the seat upholstery c23 are provided at the four corners of the peripheral wall c213 and at the center of the front and rear parts in the left-right direction of the peripheral wall c213.

[0066] The support wall c214 is a downwardly protruding wall provided around the entire outer peripheral edge of the support member c21. The support wall c214 is a wall extending downward from the outer peripheral edge of the peripheral wall portion c213.

[0067] The support wall c214 serves to stably hold the peripheral edge G of the seat cushion c22 in cooperation with the seat upholstery c23, and its outer surface sm can be attached to the inner surface sn of the hanging portion c221, which is the inner surface of the seat cushion c22.

[0068] In this embodiment, the support walls c214 located at the front and rear of the support member c21 are set to have vertical dimensions that do not interfere with the seat holder c1. More specifically, the vertical dimensions of the support walls c214 formed over the entire front area of ​​the support member c21 (both the left and right portions cf and the area therebetween) are set shorter than the vertical dimensions of the support walls c214 in other portions.

[0069] The support walls c214 in other portions include the support walls c214 located in the center portion in the front-rear direction on both the left and right sides of the support member c21.

[0070] The left and right side portions cf at the front of the support member c21 (i.e., the left and right corner portions at the front of the support member c21) are set at left-right positions that match the left and right end portions of the seat support main body ca when viewed from the front. The upper end portions y1 at the left and right end portions of the seat support main body ca constitute the uppermost portion of the seat support main body ca.

[0071] In other words, the support wall c214 of the support member c21 extends in the vertical direction as a whole in order to stably hold the peripheral portion G of the seat cushion c22 in cooperation with the seat upholstery c23, but the vertical dimensions of the parts located on both the left and right sides cf at the front are set extremely short so as not to interfere with the upper ends y1 at both side ends of the seat support body ca when the seat body c2 slides in the front-rear direction.

[0072] The support wall c214 of the support member c21 has its vertical dimension set short at the rear left and right side portions cr, similar to the front left and right side portions cf.

[0073] The height of the support walls c214, which are located on both the left and right sides cf at the front of the support member c21 and have a relatively short vertical dimension compared to other parts, gradually returns to its original height so as to gradually increase toward the rear, i.e., the central part in the fore-and-aft direction on both the left and right sides of the support member c21.

[0074] The support walls c214 are located on both the left and right sides cr at the rear of the support member c21 and have a relatively short vertical dimension compared to other parts. The height of the support walls c214 gradually increases toward the central left-right part at the rear end of the support member c21.

[0075] [Seat cushion c22] The seat cushion c22 is made primarily of urethane foam, which is a foam material. A shell-shaped support member c21 is attached to the underside of the seat cushion c22. When viewed from the bottom, the outer edge of the seat cushion c22 has a shape similar to that of the support member c21.

[0076] The seat cushion c22 is shaped so as to be fitted onto the support member c21 from above.

[0077] The seat cushion c22 is larger than the support member c21 in bottom view. In other words, the dimensions of the seat cushion c22 in the front-rear and left-right directions are set to be longer than the dimensions of the support member c21 in the front-rear and left-right directions.

[0078] The seat cushion c22 has a peripheral portion provided with a hanging portion c221 having an inner surface sn that can abut against the outer surface sm of the support wall c214. The hanging portion c221 is a portion that hangs downward on the peripheral portion of the seat cushion c22. The hanging portion c221 is disposed outside the support wall c214.

[0079] The peripheral edge G of the seat cushion c22, including the vertical portion c221, protrudes outward beyond the support member c21. In other words, the peripheral edge G of the seat cushion c22 overhangs the support member c21.

[0080] Furthermore, a plurality of recesses c222 that are open downward are provided in the center of the lower surface of the seat cushion c22 in the front-rear direction, corresponding to the seat center slits c215 provided in the support member c21.

[0081] [Zahari c23] The seat upholstery c23 is mainly made of a stretchable fabric and is capable of covering the upper surface, outer surface, and underside of the peripheral edge G (underside of the hanging portion c221) of the seat cushion c22 from the outside, and also covering the support wall c214 that is provided to hang down from the peripheral edge of the support member c21 from the space sr side.

[0082] The seat upholstery c23 is attached to the seat cushion c22 and the support member c21 in a tensed state by wrapping around the underside of the peripheral edge of the seat cushion c22 and the support member c21 and tightening the end edge y2 with a string member (not shown).

[0083] That is, the edge y2 of the seat upholstery c23 is narrowed in the direction in which the opening formed by the edge y2 becomes smaller (in the direction in which the diameter becomes smaller). After the worker has finished narrowing the edge y2 of the seat upholstery c23, it is disposed below the peripheral wall c213 of the support member c21 and is hooked onto the hook piece cn.

[0084] The peripheral portion G of the seat cushion c22, particularly the vertical portion c221 of the seat cushion c22 located outside the support wall c214, is subjected to a pulling force in the direction of the edge y2 by the tensioned seat upholstery c23, and is tightly attached to the support wall c214 and stably supported.

[0085] In particular, in this embodiment, the degree of curvature of the front part of the support member c21 is set to be greater than the degree of curvature of the front part of the seat support c1, making it easier for the seat upholstery c23 to wrap around the peripheral portion G of the seat cushion c22 in a balanced manner while suppressing the appearance of wrinkles, etc.

[0086] That is, because the left and right corners cz of the support member c21 are less angular than the corners cx of the seat support c1, the seat upholstery c23 is less likely to cause an imbalance in squeezing pressure on the peripheral edge G of the seat cushion c22, even when its edge y2 is squeezed into a substantially annular shape on the bottom side of the support member c21. As a result, the seat body c2 of this embodiment is configured to be less likely to wrinkle on the outer surface of the seat cushion c22.

[0087] Furthermore, on the inner surface of the seat upholstery c23, the support wall c214 of the support member c21 provides a favorable backing and support for the vertical portion c221 of the peripheral portion G of the seat cushion c22, and the presence of the support wall c214 also makes it less likely that unevenness will appear on the seat cushion c22 due to tension in the seat upholstery c23.

[0088] In addition, the lower edge of the support wall c214 is pressed against the seat upholstery c23. As a result, gathered wrinkles that occur at the edge y2 of the seat upholstery c23 are effectively blocked by the lower edge of the support wall c214, making it less likely to affect the seat cushion c22.

[0089] Therefore, in this embodiment of the seat C, when viewed from the front side, the visible surface of the seat body c2 located near the upper end of the seat support c1 is made to look good with the appearance of unevenness, wrinkles, etc. suppressed.

[0090] In other words, the seat body c2 in this embodiment is configured so that the lower end portion is clearly visible when viewed from the front.

[0091] <Operating member c3> The operating member c3 is supported on the seat body c2 so as to be movable up and down between an upper position and a lower position. The lower end portion, which is the operating end of the operating member c3, is exposed below the seat support c1 through the seat support slit cs.

[0092] When no load is applied, the operating member c3 is positioned at the lower position due to the biasing force of the seat cushion c22. The operating member c3 can be moved to the upper position by the user's operating force against the biasing force of the seat cushion c22.

[0093] When the operating member c3 is in the lower position, it can position the seat body c2 at a predetermined position on the seat support c1. On the other hand, when the operating member c3 is in the upper position, it can release the restriction on the seat body c2 from the seat support c1, allowing the seat body c2 to slide in the forward and backward directions relative to the seat support c1.

[0094] <Regulatory mechanism V> The restriction mechanisms V are disposed at four locations, on the left and right sides of the front and rear sides of the seat holder c1 and the support member c21. Each of the four restriction mechanisms V is mainly composed of a retaining protrusion W on the seat holder c1 and a guide portion J provided on the support member c21 and extending in the front-to-rear direction with which the retaining protrusion W can be engaged so as to be movable relative to and unable to be released.

[0095] [Retaining protrusion W] The retaining projection W has a columnar upright portion w1 extending in the vertical direction and a retaining portion w2 provided at the tip of the upright portion w1 and set to have a width dimension greater than that of the upright portion w1. The retaining projection W is generally T-shaped when viewed from the front or rear.

[0096] The standing portion w1 has a rectangular prism shape, and its base end is integrally connected to the seat receiving base c10.

[0097] The retaining portion w2 is a generally rectangular block having a longitudinal axis in the left-right direction. The center of the retaining portion w2 in the left-right direction is integrally connected to the upper end of the standing portion w1.

[0098] When an occupant is seated on seat C and slides the seat body c2 in the forward / backward direction, the support member body c211 flexes and deforms, and the undersides of the left and right ends of the retaining portion w2 can slide against the upper surfaces of the left and right longitudinal portions j2 of the corresponding guide portion J.

[0099] [Information Department J] The guide portions J are provided at four front and rear corners of the support member main body c211. The guide portion J includes a guide slit j1 that extends in the front-rear direction and can guide the standing portion w1 to be relatively movable in the front-rear direction, left and right side portions j2 that are provided adjacent to the left and right sides along the guide slit j1 and can engage with the lower surfaces of the retaining portions w2, and a standing wall portion j3 that surrounds the guide slit j1 and the side portions j2.

[0100] The longitudinal portion j2 includes a longitudinal portion main body j21 extending in the front-rear direction and a convex portion j22 protruding from the longitudinal portion main body j21.

[0101] The main body j21 of the side portion is generally plate-shaped and extends in the front-rear direction.

[0102] The convex portion j22 is capable of sliding against the underside of the retaining portion w2 of the retaining projection W. The convex portion j22 is provided on each of the left and right side portions j2. The convex portion j22 is approximately semicircular in cross section and has a rail-like shape extending in the front-rear direction. Two convex portions j22 are provided on the side portion main body j21 so as to be parallel to each other.

[0103] In addition, the lubricant such as grease can be suitably accumulated between the convex portions j22 that are provided parallel to the main body j21 of the side portion.

[0104] The inventors discovered a problem with conventional chairs: "When the seat body is slid forward and backward, abnormal noise may be generated due to some parts sliding against each other." After searching for a solution to this problem, the inventors discovered that "when the seat body is in an unloaded state with no seat occupant present, the retaining portion of the retaining protrusion and the lining portion of the guide portion are not tightly engaged. However, when a seat occupant sits on the seat body, the retaining portion and the lining portion may become tightly engaged due to the flexural deformation of the support member body." The inventors then discovered that "when the retaining portion and the lining portion become tightly engaged, abnormal noise may be generated."

[0105] In this embodiment, a convex portion j22 is provided on the longitudinal portion j2 of the guide portion J that constitutes the restriction mechanism V. Therefore, even when a seat occupant slides the seat body c2 in the front-rear direction while seated on the seat C, the longitudinal portion j2 and the convex portion j22 only come into point contact with the underside of the retaining portion w2, and noise and poor sliding caused by surface contact are suitably avoided.

[0106] Therefore, the configuration of the regulating mechanism V in this embodiment not only makes it less likely to produce abnormal noise that can occur when the seat body c2 slides, but also allows the seat body c2 to slide smoothly relative to the seat support c1.

[0107] <<Back support D>> The back support D is interposed between the support base B and the backrest E, and between the support base B and the seat C. The back support D is provided with a rear axle jk3 extending in the left-right direction and engaging with a rear axle holding portion ce provided in the seat support c1 of the seat C.

[0108] The back support body D comprises a pair of left and right arms d1 in the form of an upright plate extending in the front-to-rear direction and pivotally supported on the support base main body 1 of the support base B via the main shaft jk1, a connecting member d2 in the form of an upright plate connecting the rear portions of the pair of left and right arms d1, a rear shaft jk3 extending in the left-to-right direction and supported on a portion of the pair of left and right arms d1 forward of the main shaft jk1, a pair of left and right receiving shaft support members d3 arranged closer to the center in the left-to-right direction than the pair of left and right arms d1 and whose upper portions are connected to the rear shaft jk3, and a receiving shaft d4 connected between the lower portions of the pair of left and right receiving shaft support members d3.

[0109] <Left and right arms d1> The left and right arms d1 are made of metal and have left and right arm bodies d11 extending in the front-to-rear direction, forming an upright wall shape. The left and right arms d1 are disposed outside the left and right side walls 14 of the support base body d1.

[0110] The left and right arms d1 are equipped with left and right arm bodies d11 that extend in the front-to-rear direction and can support the main shaft jk1 at their front ends, left and right front arm portions d12 that extend diagonally upward and forward from the front ends of the left and right arm bodies d11 and support the rear shaft jk3 that engages with the seat C at its upper end, and a main shaft insertion hole d13 that is provided between the left and right arm bodies d11 and the left and right front arm portions d12 and penetrates in the left-to-right direction and can hold the main shaft jk1.

[0111] The left and right arm bodies d11 extend in a substantially straight line in the front-to-rear direction. The rear portions of the left and right arm bodies d11 are connected by a connecting member d2. The rear ends of the left and right arms d11 protrude rearward beyond the connecting member d2, and the protruding portions dt can be fitted into the back support member connecting portions 41 provided on the lower frame member 4 of the backrest E.

[0112] Axial holes (not shown) that penetrate in the left-right direction are provided in front of the portions of the left and right arm bodies d11 where the connecting members d2 are fastened, and rearward tilt degree setting levers x1 are rotatably supported in these axial holes.

[0113] <Connection member d2> The connecting member d2 is made of metal and has an upright plate shape that extends in the left-right direction. The left and right ends of the connecting member d2 are rigidly connected to the inner sides of the left and right arms d1 by welding.

[0114] The connecting member d2 is provided with a nut portion nt to which a screw v for attaching the backrest E is screwed.

[0115] In addition, the back support body D has a backrest mounting portion formed in an H-shape when viewed from above or below, which is formed by the rear portions of the left and right arms d1 and a connecting member d2 connecting the rear portions of the left and right arms d1.

[0116] <Rear axis jk3> The rear axle jk3 extends in the left-right direction and is connected to the upper ends of the left and right front arm portions d12.

[0117] <Left and right bearing shaft support members d3> The left and right bearing shaft support members d3 support the bearing shaft d4 that is pressed by the reaction spring HG. The left and right bearing shaft support members d3 rigidly connect both ends of the bearing shaft d4 at their lower ends.

[0118] <Bearing axis d4> The receiving shaft d4 extends in the left-right direction and is disposed inside the support base main body 1. The receiving shaft d4 is a portion that directly receives the biasing force of the reaction spring HG disposed in the support base B.

[0119] <<Lower cover body I>> The lower cover body I is a single-piece molded product made of synthetic resin and attached to the back support body D. The lower cover body I includes left and right arm cover portions i1 that cover the front portions of the pair of left and right arms d1 from below, a rear cover portion i2 that is connected to the rear end portions of the left and right arm cover portions i1 and covers the area behind the support base B from below, and a rear engagement claw i3 that stands upright from the rear end edge of the rear cover portion i2 and engages with the upper end edge while contacting the back surface of the connecting member d2 of the back support body D in the left-right center.

[0120] The arm cover portion i1 is provided at its upper end in the center in the front-rear direction with a front engagement claw i11 that engages with the upper ends of the pair of left and right arms d1.

[0121] The rear cover portion i2 covers and conceals the rotary member x2 disposed between the rear portions of the pair of left and right arms d1 so that it cannot be seen from the outside.

[0122] The upper end of the rear engagement claw i3 is hooked onto the upper edge of the connecting member d2 and is sandwiched between the lower frame member 4 of the back frame M and the connecting member d2.

[0123] The lower cover body I is suitably attached to the spine support body D in a manner that makes it difficult for it to come off, since the front engagement claws i11 and the rear engagement claws i3 engage with corresponding portions of the spine support body D.

[0124] <<Rearward tilt degree setting mechanism X>> The backward tilt degree setting mechanism X allows the user to select from two or more backward tilt degrees of the backrest E, which is supported so as to be able to tilt backward relative to the support base B via the back support body D, by operating it.

[0125] The rearward tilt degree setting mechanism X comprises a rearward tilt degree setting lever x1 rotatably supported on the back support D, and a rotating member x2 rotatably attached to the rearward tilt degree setting lever x1 and having a plurality of contact surfaces corresponding to a plurality of rearward tilt degrees.

[0126] <<Backrest E>> The backrest E comprises a back frame M, which is the backrest base and has a screw insertion hole h and is attached to the back support D with a screw v; a lower frame material cover Q, which is a cover body that is made of a separate member from the back frame M and covers the lower frame material 4, which is the lower base part of the back frame M, from above; and a mesh-like tension member P that is stretched over the back frame M.

[0127] <Back frame M> The back frame M comprises left and right side frame members 2 each having a tension member mounting groove mz opening outward, an upper frame member 3 having a tension member mounting groove mz opening upward and connecting the upper parts of the left and right side frame members 2, a lower frame member 4 connecting the lower parts of the left and right side frame members 2, and an intermediate connecting frame member 5 having a tension member mounting groove mz opening downward and connecting the left and right side frame members 2 together while forming an upper cavity sa between the upper frame member 3 and a lower cavity sb between the lower frame member 4.

[0128] In this embodiment, the left and right side frame members 2, the upper frame member 3, the lower frame member 4, and the intermediate connecting frame member 5 that constitute the back frame M are integrally molded from synthetic resin.

[0129] The back frame M comprises an upper frame-shaped portion wa having an upper cavity sa formed therein by left and right side frame members 2 which are first frame members extending in a predetermined direction, i.e., the up-and-down direction, an upper frame member 3 which is a second frame member connected to the left and right side frame members 2 and extending in the left-right direction, which is a direction intersecting the left and right side frame members 2, and an intermediate connecting frame member 5 which extends in the left-right direction, and a lower frame-shaped portion wb having a lower cavity sb formed therein by the left and right side frame members 2, the lower frame member 4, and the intermediate connecting frame member 5.

[0130] Corners K are formed between the left and right side frame members 2 and the upper frame member 3 that constitute the upper frame-shaped portion wa.

[0131] The backrest E has a tensioning member P that can form the backrest surface pm stretched only on the upper frame-shaped portion wa provided on the back frame M. On the other hand, the tensioning member P is not stretched on the lower frame-shaped portion wb.

[0132] [Left and right side frame material 2] The left and right side frame members 2 extend in the vertical direction. The left and right side frame members 2 have a bent portion 23 in the middle in the vertical direction, and are generally V-shaped in side view.

[0133] On the outer surfaces of the left and right side frame members 2, tension member mounting grooves mz are formed, which continue from the upper ends of the side frame members 2 to a height position that roughly corresponds to the lower edges of the intermediate connecting frame member 5. A tension member P is stretched between the left and right side frame members 2 that extend in the vertical direction.

[0134] The left and right side frame members 2 are provided with an outer frame portion 21 having a tension member mounting groove mz opened outward, and an inner frame portion 22 located inside the outer frame portion 21 and with its front portion located further rearward than the front portion of the outer frame portion 21.

[0135] A lumbar support holding portion N is provided in the vertical middle portion of the left and right side frame members 2, which is at a height position corresponding to the waist of the seated person, more specifically, in the vertical middle portion of the inner frame portion 22 of the left and right side frame members 2, which can hold the lumbar support R in a manner that allows its vertical position to be changed.

[0136] [Top frame material 3] The upper frame member 3 extends in the left-right direction and includes an outer frame portion 31 having an upwardly open tension member mounting groove mz formed therein for mounting the tension member P, and an inner frame portion 32 disposed below the outer frame portion 31.

[0137] The end accommodating spaces zs for the tensioning members P formed by the tensioning member mounting grooves mz of the upper frame member 3 are connected to the end accommodating spaces zs for the tensioning members P formed by the tensioning member mounting grooves mz of the left and right side frame members 2. In other words, end accommodating spaces zs are also formed in the corners K provided between the upper frame member 3 and the left and right side frame members 2.

[0138] [Configuration of corner K] At the corner K of the back frame M, a through hole ka is provided that penetrates between the outside of the upper frame-shaped portion wa, i.e., the external space side that is not surrounded by the upper frame-shaped portion wa, and the inside, i.e., the upper cavity sa side that is surrounded by the upper frame-shaped portion wa.

[0139] The through-hole ka is provided in the center in the thickness direction in the front-rear direction at the corner K. The through-hole ka extends obliquely so as to be positioned gradually inward as it goes downward.

[0140] The through-hole ka has an upper opening kb located on the external space side not surrounded by the upper frame-shaped portion wa, and a lower opening kc located on the upper cavity sa side surrounded by the upper frame-shaped portion wa. The upper opening kb is provided in a position facing the end accommodating space zs, and the lower opening kc is provided in a position facing the locking member arrangement area ks provided at the bottom of the front side of the corner portion K.

[0141] An upwardly recessed recess hc is formed in the lower part of the outer frame portion 31 of the upper frame member 3 in the portion corresponding to the corner K. The spatial area created by the upwardly recessed recess hc is a locking member arrangement area ks in which a locking member p3 provided on the tension member P is arranged. Note that the locking member p3 arranged in the locking member arrangement area ks is made almost invisible by the tension member main body p1 stretched on the front side of the upper frame-shaped portion wa.

[0142] A locking member p3 provided on the upholstery member P is inserted from the outside to the inside into the through holes ka provided in the left and right corners K of the back frame M. After passing through the through holes ka, all or at least a part of the locking member p3 inserted into the through holes ka is prevented from slipping out, i.e., from returning, by the opening kc below, and is arranged in the locking member arrangement area ks.

[0143] [Bottom frame material 4] The lower frame member 4 has a portion that connects the lower portions of the left and right side frame members 2 and is connected to the back support member D. In addition, the lower frame member 4 has a fitting frame portion 4w formed on the upper surface side into which the lower frame member cover Q is fitted.

[0144] The lower frame material 4 comprises a lower outer wall 4a having an outer surface facing downward, left and right side outer walls 4b rising from both sides of the lower outer wall 4a and having outer surface portions facing laterally, and a rear outer wall 4c extending upward from the rear end edge of the center of the left and right sides of the lower outer wall 4a and having outer surface portions facing rearward.

[0145] The lower frame member 4 has a fitting frame portion 4w surrounded by the left and right front end portions e1 of the lower outer wall 4a, the front end portions e2 and upper end portions e3 of the left and right side outer walls 4b, the upper end portion e4 of the rear outer wall 4c, and the front end portion e5 of the horizontal rib 2a. The fitting frame portion 4w is adapted to fit the lower frame member cover Q.

[0146] The horizontal rib 2a is a plate-like member extending forward from the lower end of the left and right side frame members 2, with its front end e5 located above the lower frame member 4.

[0147] The lower frame material 4 has left and right arm connecting portions 41, which are recessed and open to the front and fit onto the rear ends of the left and right arms d1, within an area surrounded by the lower outer wall 4a, left and right side outer walls 4b, and rear outer wall 4c.

[0148] The left and right arm connecting portions 41 are composed of a lower outer wall 4a, left and right intermediate upright walls 4d erected from the lower outer wall 4a, and upper wall portions 4e extending inward from the upper ends of the left and right intermediate upright walls 4d.

[0149] Next, the recess U provided in the lower frame member 4 will be described.

[0150] The recess U comprises a rear wall u1, which is a screw engagement wall having a screw insertion hole h drilled therethrough and into which the head vt of the screw v can engage; an upright wall u2, which is a front wall located rearward of the rear wall u1 and forward of the opening uk; a peripheral wall u3 extending in the front-to-rear direction and whose inner surface faces the storage space sd; and an intermediate wall u4 extending in the front-to-rear direction and having a surface facing the screw storage space sd, which connects the outer end of the upright wall u2 and the inner end of the rear wall u1.

[0151] The rearward surface of the rear wall u1 constitutes a positioning portion that positions the head vt of the screw v. The rear walls u1, each having a screw insertion hole h through which the screw v is inserted, are provided in pairs on the left and right. The rear wall u1 has a screw insertion hole h that penetrates in the front-to-rear direction at its center. The frontward surface, which is the opposite surface of the rear wall u1, abuts against the back surface of the connecting member d2 of the spine support body D. In other words, the rear wall u1 serves both as a positioning wall for the head vt of the screw v and as an engagement wall for the connecting member d2 of the spine support body D.

[0152] The upright wall u2 is provided inside the rear wall u1 provided on the left and right sides when viewed from the rear. The upright wall u2 is elongated in the left-right direction and arranged in a position approximately parallel to the rear wall u1. The rear surface of the upright wall u2 forms a surface that is visible when viewed from the rear. The upright wall u2 is set to be approximately flush with the outer surface of the concealing body main body q21 in the concealing body q2 in the lower frame material cover Q that has passed through the passage hole u32.

[0153] The peripheral wall u3 has an inner peripheral surface that faces in a direction approximately perpendicular to the front-to-rear direction. The rear end of the peripheral wall u3 extends to the rear outer wall 4c, and an opening uk is formed in the rear outer wall 4c. The peripheral wall u3 is configured to include an upper wall portion u31 located on the upper side. The upper wall portion u31 has a pair of through holes u32 on the left and right at a position corresponding to the screw accommodating space sd. The through holes u32 are formed in the vertical direction at a position facing the screw accommodating space sd, allowing the concealing body q2 of the lower frame material cover Q to pass through.

[0154] In other words, the recess U is located in the left-right center of the lower frame material 4 and is open to the rear. A screw accommodating space sd is formed in the recess U, which can accommodate the head vt of the screw v for connecting the back frame M to the back support D. The screw v is inserted through the opening uk from the rear of the lower frame material 4. The recess U is recessed forward when viewed from the rear side.

[0155] [Intermediate connection frame material 5] The intermediate connecting frame member 5 extends in the left-right direction and is installed between the portions of the left and right side frame members 2 that are tilted forward when viewed from the side. The intermediate connection frame member 5 has a curved shape that is convex toward the rear in a plan view. The intermediate connection frame member 5 is formed with a tension member mounting groove mz that opens downward.

[0156] <<Bottom Frame Material Cover Q>> The lower frame cover Q covers the upper side of the lower frame 4 of the back frame M, which is the lower base portion of the backrest base.

[0157] The lower frame material cover Q is configured to be detachable from the spine frame M. When the head vt of the screw v is positioned on the rear wall u1, which is a positioning portion provided on the lower frame material 4, the lower frame material cover Q is attached to the correct attachment position on the spine frame M, i.e., the position where it fits into the fitting frame portion 4w.

[0158] The lower frame material cover Q is configured so that it can properly fit into the mating frame portion 4w provided on the lower frame material 4 when the head vt of the screw v for connecting the back frame M and the back support body D is properly positioned by the rear surface of the rear wall u1 of the lower frame material 4.

[0159] The lower frame material cover Q comprises a lower frame material cover main body q1 which covers the upper surface side of the lower frame material 4, which is the lower base portion; a concealing body q2 which protrudes downward from the center of the front-to-back direction of the lower frame material cover main body q1 and engages with the rear of the head vt of the screw v, thereby concealing the head vt of the screw v so that it cannot be seen from the outside, i.e., from the rear; and a pair of left and right front cover portions q3 which extend downward from the front end of the lower frame material cover main body q1 and cover the left and right front sides of the lower frame material 4.

[0160] <Bottom frame cover body q1> The lower frame material cover body q1 is in the form of a plate extending in the front-rear and left-right directions.

[0161] The lower frame material cover body q1 has a cover side end t3 corresponding to the upper end e3 of the left and right side outer walls 4b that constitute the fitting frame portion 4w, a cover central rear end t4 that corresponds to the upper end e4 of the rear outer wall 4c that constitutes the fitting frame portion 4w, and cover left and right rear end t5 that correspond to the front end e5 of the horizontal rib 2a that constitutes the fitting frame portion 4w.

[0162] On both sides of the rear of the lower frame cover body q1, there are vertically extending cylindrical positioning protrusions q11 whose lower ends can abut against the upper surfaces of the lower horizontal ribs 4r provided on both sides of the lower frame 4.

[0163] The left and right rear edges of the lower frame cover body q1, i.e., the left and right rear end portions t5 of the cover, are provided with engaging protrusions q12 that can engage with the front end portions e5 of the horizontal ribs 2a that form the fitting frame portion 4w.

[0164] <Concealed body q2> The concealing body q2 comprises a concealing body main body q21 which is a protruding piece hanging down from the lower frame material cover main body q1 and has a rear side which can be seen, and a head engaging portion q22 which is provided on the front side of the concealing body main body q21 and whose front end can engage with the head VT of the screw V.

[0165] The concealing members q2 are provided in pairs on the left and right sides in correspondence with the screws v inserted into the screw insertion holes h in the inner wall u1 of the recess U.

[0166] [Covered body q21] The concealing body main body q21 is a plate-like member that is elongated in the vertical and horizontal directions, and the lower edge is formed in a substantially semicircular shape.

[0167] [Head engaging part q22] The head engagement portion q22 is a plate-shaped member that is elongated in the vertical and front-to-back directions, with its upper end connected to the lower frame material cover main body q1 and its rear end connected to the concealing body main body q21.

[0168] <Front cover part q3> The front cover portion q3 has a generally triangular shape that gradually narrows downward.

[0169] The front cover portion q3 has a cover lower end portion t1 corresponding to the left and right front end portions e1 of the lower outer wall 4a that constitutes the fitting frame portion 4w, and a cover front end portion t2 corresponding to the front end portions e2 of the left and right side outer walls 4b that constitute the fitting frame portion 4w.

[0170] [Verification function for screws v based on the position of the lower frame material cover Q] The lower frame material cover Q is configured so that when the screw v is inserted into the screw insertion hole h and the head vt of the screw v is not positioned on the rear surface of the rear wall u1, which is the positioning portion, the concealing body q2 cannot conceal the head vt of the screw v so that it cannot be seen from the outside.

[0171] As shown in Figure 41, if the head vt of the screw v is not properly threaded into the rear wall u1, the lower end of the concealing body q2 will engage with the upper end of the head vt. As a result, the concealing body q2 will not be able to descend to the correct position on the rear side of the rear wall u1, and the peripheral end of the lower frame material cover body q1 that should be fitted into the fitting frame portion 4w will not be able to move to the specified position. An operator who visually observes this state will be able to notice that the screw v is not properly threaded into the screw insertion hole h (the threading state is insufficient; the screw v is not fully screwed in).

[0172] Furthermore, if the screw v is not inserted into the screw insertion hole h, the lower frame material cover Q will not be positioned in the specified position on the lower frame material 4 and will become loose, so a gap sk of a certain width may occur between the edge of the lower frame material cover main body q1 and the base of the backrest.

[0173] As shown in Figure 42, if an attempt is made to attach the spine frame M to the spine support D without inserting the screw v into the screw insertion hole h, the lower frame material cover Q will not be able to stabilize in the desired position, and will clearly shift forward and backward. As a result, the peripheral edge of the lower frame material cover body q1 will become loose relative to the fitting frame portion 4w (a gap sk will easily appear). An operator who visually observes this state will be able to notice that the screw v has not been inserted into the screw insertion hole h.

[0174] <Upholstery material P> The upholstery member P comprises an upholstery member main body p1 which is mainly made of mesh-like fabric and can form the backrest surface pm; a band-shaped member p2 which is a held member attached to the outer edge of the upholstery member main body p1 and held in the upholstery member mounting groove mz provided in the left and right side frame members 2, the upper frame member 3, and the intermediate connecting frame member 5; and a locking member p3 which passes through the through hole ka of the corner K of the back frame M from the outside to the inside and can be locked into the lower opening kc of the through hole ka.

[0175] The tension member main body p1 is stretched on the front side of the upper frame-shaped portion wa of the back frame M and has a substantially rectangular shape when viewed from the front.

[0176] The strip-shaped member p2 is press-fit into the tension member mounting groove mz together with the end of the tension member main body p1 during assembly. The strip-shaped member p2 is attached to the outer edge of the tension member main body p1 so as to roughly correspond to the roughly linear portions of the left and right side frame members 2, the upper frame member 3, and the intermediate connecting frame member 5 in a front view. The strip-shaped member p2 is made of synthetic resin and extends roughly linearly in a front view, sewn to the tension member main body p1.

[0177] The belt-shaped member p2 is not sewn to the upholstery member main body p1 in the portion corresponding to the corner K of the back frame M.

[0178] The locking member p3 is inserted into the through hole ka of the corner K, and thereafter can be locked into the lower opening kc of the through hole ka facing the upper cavity sa.

[0179] The locking member p3 is formed from a piece of fabric pa in the shape of a protrusion or strip, which is integrally extended from the upholstery member main body p1.

[0180] The fastening member p3 is formed by folding and laminating a piece of fabric pa in the shape of a protrusion or strip that extends integrally from the upholstery member main body p1. More specifically, the fastening member p3 is formed by folding back the strip-shaped fabric portion pa extending from the upholstery member main body p1 once or multiple times, and then sewing the folded-back portions together to maintain the block-like shape (laminated state) that appears when the fabric is folded back.

[0181] The locking member p3 has an expandable mass shape. The locking member p3 is set to a shape that is temporarily compressed when passing through the through hole ka. After passing through the through hole ka, the locking member p3 is released from the state in which it was pinched and compressed by the through hole ka, and returns to a shape that is more expanded than when it passed through the inside of the through hole ka.

[0182] In the tension member P of this embodiment, the locking member p3 that has passed through the through-hole ka of the corner K is unlikely to return through the through-hole ka. Therefore, the portion of the tension member P that corresponds to the corner K has a suitable configuration that makes it difficult for it to come off the corner K.

[0183] <<Lumbar Support R>> The lumbar support R is supported by the backrest E in a detachable manner.

[0184] The lumbar support R is installed between the left and right side frame members 2 so that its position can be changed in the vertical direction. The lumbar support R is located behind the tension member P and is capable of supporting the lower back of a seated person.

[0185] The lumbar support R comprises a lumbar base RB, which is a single component that is spanned between the left and right side frame members 2 of the backrest E so that its position can be changed in the vertical direction, and a pair of left and right lumbar pads RP that are supported on the lumbar base RB so that their position can be changed in the horizontal direction.

[0186] The lumbar support R of this embodiment can be attached to the backrest E afterwards, or removed from the backrest E, by temporarily bending the components.

[0187] The above-described embodiment makes it possible to provide a chair having a configuration in which the concealing member q2 protruding from the lower frame material cover Q can effectively prevent the appearance from being spoiled due to the screw v being visible.

[0188] Furthermore, with the above-described embodiment, the seat body c2 can be slid back and forth in an appropriate manner relative to the seat support c1, and a seat body c2 can be obtained that has a stably mounted seat cushion c22 that is larger than the support member c21, and a chair with excellent design freedom can be provided that can form a suitable appearance for the peripheral portion G of the seat body c2, in particular, a suitable apparent appearance for the front lower end portion of the seat body c2.

[0189] Furthermore, the above-described embodiment makes it possible to provide a chair having a suitable configuration in which the upholstery member P can be supported on the corner portion K of the upper frame-shaped portion wa of the backrest E.

[0190] Furthermore, with the above-described embodiment, it is possible to provide a chair having a configuration that allows the seat body c2 to move back and forth appropriately relative to the seat support c1 and that can appropriately suppress the phenomenon of abnormal noise occurring when the seat body c2 and the seat support c1 slide against each other.

[0191] As described above, the chair according to this embodiment has the upholstery member P stretched over the upper frame portion wa, which is a frame portion that constitutes the backrest E.

[0192] The upper frame-shaped portion wa has left and right side frame members 2 which are first frame members extending in the vertical direction, and an upper frame member 3 which is a second frame member connected to the left and right side frame members 2 and extending in the left-right direction which is a direction intersecting the left and right side frame members 2, and a corner portion K is formed between the left and right side frame members 2 and the upper frame member 3.

[0193] The left and right side frame members 2 and the upper frame member 3 are open outward and have tension member mounting grooves mz that can hold the ends of the tension member P, and the corners K are provided with through holes ka that penetrate between the outside and the inside of the upper frame-shaped portion wa, and the tension member P passes through the through holes ka from the outside to the inside and is equipped with locking members p3 that can be locked in the lower opening kc, which is the opening of the through holes ka.

[0194] Therefore, this embodiment can provide a chair having a suitable configuration that can support the upholstery member P at least at the corner K of the upper frame-shaped portion wa that constitutes the backrest E, and an attachment structure for the upholstery member P.

[0195] That is, a through hole ka is provided in the corner K of the back frame M that constitutes the backrest E. Then, a locking member p3 provided on the upholstery member P is passed through the through hole ka of the corner K. Therefore, with this embodiment, it is possible to provide a chair that can firmly support the end of the upholstery member P against the corner K, that is, a chair that prevents the end of the upholstery member P from easily slipping out of the corner K.

[0196] The upholstery member P comprises an upholstery member main body p1 which is mainly made of fabric and can form the backrest surface pm, and a belt-shaped member p2 which is a held member attached to the outer edge of the upholstery member main body p1 and held in the upholstery member mounting groove mz, and the locking member p3 is formed from fabric extending from the upholstery member main body p1.

[0197] Therefore, there is no need to provide a new separate member for providing the locking member p3, and an increase in the number of parts is appropriately suppressed.

[0198] The strip-shaped member p2 extends in a substantially straight line and is sewn to the outer edge of the tension member main body p1.

[0199] Therefore, the outer edge of the tension member main body p1 is suitably held in the tension member mounting groove mz together with the belt-shaped member p2.

[0200] The fastening member p3 is formed by folding and laminating a strip-shaped fabric pa that extends integrally from the upholstery member main body p1.

[0201] Therefore, the locking member p3 can have a suitable configuration that can be temporarily compressed and deformed when passing through the through hole ka without increasing the number of parts.

[0202] The locking member p3 is an expandable block, and is set to a size that allows it to be temporarily compressed when passing through the through-hole ka.

[0203] Therefore, the locking member p3 has a suitable structure that can be engaged with the lower opening kc of the through hole ka by expanding after passing through the through hole ka.

[0204] The present invention is not limited to the above-described embodiment.

[0206] The frame-shaped portion has a first frame member extending in a predetermined direction and a second frame member connected to the first frame member and extending in a direction intersecting the first frame member, and a corner is formed between the first frame member and the second frame member. In other words, the frame-shaped portion is not limited to a frame structure that is continuous around the entire periphery, but may have at least an L-shaped configuration.

[0207] The through-holes are provided at the corners and may be any shape that passes through from one side to the other, and it goes without saying that the specific shapes thereof may take various forms.

[0208] The locking member may be any member capable of performing the function of locking at the opening of the through hole or the vicinity of the through hole, and its specific shape, structure, material and composition may be appropriately set within the scope of the present invention.

[0209] The locking member may be formed as a separate member attached to the tension member body.

[0210] Furthermore, the specific configuration of each part is not limited to the above embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0211] E...backrest 2...Left and right side frame members (first frame members) 3...Upper frame material (second frame material) K...Corner 6a...Through hole P... tension member p3…Locking member wa...Upper frame part (frame part)

Claims

1. A chair in which a tension member is stretched on the back frame of a backrest, The back frame has left and right side frame members extending in the vertical direction, and an upper frame member extending in a direction intersecting the left and right side frame members and connecting the upper ends of the left and right side frame members, and corners are formed between the left and right side frame members and the upper frame member, The left and right side frame members and the top frame member are provided with tension member mounting grooves that open outward and can hold the ends of the tension members, A through hole is provided at the corner portion, the through hole extending obliquely so as to penetrate between the outer and inner sides of the back frame and to be gradually positioned inward toward the bottom, The upholstery member comprises an upholstery member main body mainly made of fabric and capable of forming a backrest surface, a belt-shaped member extending in a substantially straight line and sewn to the outer edge of the upholstery member main body and held in the upholstery member mounting grooves of the left and right side frame members and the top frame member, and a locking member that passes through the through hole from the outside to the inside and can be locked in the opening of the through hole, The belt-shaped member is not sewn to the portion of the upholstery member body that corresponds to the corner portion, A chair in which the locking member is a separate member attached to the part of the upholstery member body corresponding to the corner, or is formed by folding and stacking a strip of fabric extending from the part of the upholstery member body corresponding to the corner.

2. 2. The chair according to claim 1, wherein the locking member is an expandable mass having a size set so that it is temporarily compressed when passing through the through hole.

3. A mounting structure for a tension member to a back frame constituting a backrest, The back frame has left and right side frame members extending in the vertical direction, and an upper frame member extending in a direction intersecting the left and right side frame members and connecting the upper ends of the left and right side frame members, and corners are formed between the left and right side frame members and the upper frame member, The corner portion is provided with a through-hole extending obliquely so as to penetrate between the outer and inner sides of the back frame and to be gradually positioned inward toward the bottom, The upholstery member comprises an upholstery member main body mainly made of fabric and capable of forming a backrest surface, a belt-shaped member extending in a substantially straight line and sewn to the outer edge of the upholstery member main body and held in the upholstery member mounting grooves of the left and right side frame members and the top frame member, and a locking member passing through the through hole from the outside to the inside, The belt-shaped member is not sewn to the portion of the upholstery member body that corresponds to the corner portion, the fastening member is formed by a separate member attached to a portion of the tension member body corresponding to the corner, or by folding and laminating a strip of fabric extending from the portion of the tension member body corresponding to the corner, An attachment structure for a tension member in which the locking member that passes through the through hole is locked at or near the opening of the through hole and prevented from returning.

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