Chairs and their backs

Abstract

To disclose a structure for attaching to a back frame while a backrest plate applies tension in a backrest in which the backrest plate is made of a soft material such as elastomer.SOLUTION: A reinforcing member 6, 7 is joined to an upper end part and a lower end part of a backrest plate 5 by insert molding. An upper reinforcing member 6 is connected to an upper support body 9 in a manner not to be separated by using an engaging nail. In a lower reinforcing member 7, a block-shaped lower engaging protrusion 18 is formed and fits in a lower engaging recess 19 of a lower support body 10. By bringing the lower reinforcing member 7 into contact with an outward inner surface of the lower engaging recess 19 from the outside, the lower reinforcing member is temporarily attached to the lower support body 10 while keeping the backrest plate 5 in an expanded state. Therefore, an operator can screw a machine screw 24 in a nut 67 by removing a hand from the backrest plate 5. By using softness of a material, the backrest with excellent cushioning properties and fitness can be provided in a stable quality.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a chair and its backrest, and is particularly suitable for a backrest that is used without a cushioning material and with the backrest board exposed, and a chair equipped with the same. [Background technology]

[0002] The backrest is an important element of a chair, and various innovations have been made to ensure comfort. Key elements in providing comfort to a backrest are fit, cushioning, and softness, so the front of the backrest is made of cushioning material or mesh material is used to support the body. Mesh material has the advantage of being highly breathable, preventing stuffiness.

[0003] When a seated person leans against a chair back, the center line of their upper body is not necessarily aligned with the center line of the backrest. They may lean their upper body to the right or left, or they may twist their body to the right or left while leaning against the backrest and look backwards. In these cases, the pressure (body pressure) caused by the seated person leaning against the backrest acts strongly on the left or right side of the backrest.

[0004] In addition, chair backs are generally rigid enough that they are hardly deformed by the pressure of the seated person, but if the backrest has a rigid structure, when the seated person twists their body, part of the body will come into strong contact with part of the backrest, reducing comfort.

[0005] To address this issue, chairs have been proposed that allow the backrest to bend (torsional deformation) due to the pressure of the seated person, an example of which is disclosed in Patent Document 1. Patent Document 1 relates to an earlier application filed by the applicant of the present application, in which left and right elongated upper support bodies are attached to the top ends of the back support pillars so that they can pivot horizontally against a spring, and the left and right ends of the backrest are connected to the left and right ends of the upper support bodies, so that when the user's weight acts unevenly on either the left or right side, the upper support bodies pivot horizontally, causing the backrest to twist. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-58759 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, the backrest bends (torses) when pressed by the seated person, so when the occupant shifts their upper body to the right or left and leans against the backrest, the backrest follows and deforms accordingly. This allows for the seated person's body movement and provides a softer impact on the body. As a result, comfort is greatly improved.

[0008] There are various types of chair backs, and the type with an exposed back panel made of synthetic resin is also widely known. This type of back has a simple aesthetic that differs from cushioned or mesh types, but because the back panel is often made of a hard synthetic resin such as polypropylene, it is often seen in simple chairs such as pipe chairs, and there are not many examples of it being used in chairs that people use for long periods of time at work, such as office swivel chairs.

[0009] However, even in the case of a type in which the backrest board directly supports the body of the seated person, if the backrest board is made of a material that easily deforms elastically, such as elastomer, or if the backrest board has many holes drilled into it to facilitate elastic deformation, it can maintain a simple appearance while ensuring high cushioning and fit, and can also be used in office swivel chairs.

[0010] The holes also function as patterns, so a high level of design can be achieved by devising the shape of each hole and the overall arrangement pattern. This is a unique advantage that cannot be achieved with cushion-type or mesh-type backrests. Therefore, chairs with exposed backrests are expected to have a wide range of applications in the future.

[0011] While using an exposed flexible backrest in this manner is beneficial to the user, a flexible backrest must be kept under tension in the manufactured state, which can make assembly more difficult.

[0012] The present invention was made against the backdrop of the current situation, and aims to disclose a structure for a chair whose backrest is made of a flexible material, which allows for easy assembly of the backrest in a stretched state. [Means for solving the problem]

[0013] The present invention has many features, and typical examples are specified in each claim. The invention in claim 1 relates to a backrest, and " arrival The backrest is made of a soft material that can bend and deformed by the pressure of the seated person. and a support member to which the upper and lower parts of the backrest plate are attached, A left and right longitudinal reinforcing member made of a material harder than the backrest plate is integrally provided on the upper or lower part or both of the backrest plate, and a connecting portion attached to the support member is provided on both left and right ends of the reinforcing member, The left and right connecting portions of the one or two reinforcing members are provided with temporary engagement portions that apply tension in the left and right direction to the reinforcing members when they are attached to the support member. " The structure is as follows.

[0014] The invention of claim 2 is a development example of claim 1, " The aforementioned Reinforcement member The backrest board It is integrally formed by insert molding. There are " The structure is as follows.

[0015] The invention of claim 3 is a development example of claim 2, " The reinforcing members are provided on the upper and lower parts of the backrest plate,The connecting portions of the upper and lower reinforcing members have an engagement structure that fits into the connecting portions of the support member. and , The connecting portion of one of the upper and lower reinforcing members is fitted into the support member so that it cannot be separated from the support member. in, The connecting portion of the other of the upper and lower reinforcing members has the temporary engagement portion and is temporarily fixed to the support member, and then is permanently fixed with a screw. It is a structure " The structure is as follows.

[0016] The invention of claim 4 is a development example of any one of claims 1 to 3, "The backrest plate has a substantially rectangular shape when viewed from the front, and its upper and lower edges are attached to the support member via the reinforcing member, allowing it to be twisted around a vertical axis." The structure is as follows.

[0017] The invention of claim 5 is an embodiment of claim 4, The support member is a back frame having a left-right longitudinal upper support body, a left-right longitudinal lower support body, and a top-bottom longitudinal back support column, The upper edge portion of the backrest plate is connected to the upper support body via the upper reinforcing member, The lower edge portion of the backrest plate is connected to the lower support body via the lower reinforcing member, The upper support body is attached to the back support column so as to be able to pivot horizontally against elasticity. The structure is as follows.

[0018] The invention of claim 6 is an embodiment of claim 5, "The backrest board is The upper and lower sides The left and right ends are attached to the upper support body and the lower support body via the reinforcing members. The structure is as follows.

[0019] The invention of claim 7 is a development example of any of claims 1 to 6, "The above Reinforcement members Each connecting portion is Material It has a protrusion or recess shape that fits into the front and rear. The structure is as follows.

[0020] The invention of claim 8 is directed to a chair, "A backrest according to any one of claims 1 to 7 This Prepare.” The structure is as follows. [Effects of the Invention]

[0021] In the present invention, by providing a temporary engagement portion at the connecting portion, when assembling the chair by attaching the backrest to the support member, the worker does not need to continue to hold the backrest in a pulled state by hand, but can hold the backrest plate in a taut state (tensioned state), and can perform the permanent fixing work such as screwing with their hands free from the backrest. Therefore, in the present invention, a high-quality chair with a flexible backrest held in a taut state can be assembled with reduced burden on the worker.

[0022] In addition, because the backrest connection is provided on the reinforcing member, no localized load is placed on the backrest board. Therefore, even though the chair has a flexible backrest board, it maintains high durability, improving its commercial value.

[0023] Although two-color molding and adhesive bonding are possible methods for integrating the backrest plate and the reinforcing member, the use of insert molding as in claim 2 has the advantage that the backrest plate and the reinforcing member can be firmly joined using a general mold device, and also has the advantage of stabilizing the quality.

[0024] Also, claims 1By forming the reinforcing member in a longitudinal shape in this manner, the shape retention of the upper and lower edges of the backrest plate can be improved, thereby preventing excessive deformation of the backrest plate and ensuring stability for the seated person.

[0025] Each connecting part can be fixed with fasteners such as screws, but by adopting the configuration of claim 3, one of the upper and lower connecting parts is fixed to the support member by fitting it in, thereby reducing the number of screw fastening points and reducing the effort required for assembly.

[0026] If the backrest board has the flexibility to bend and deform under the pressure of the seated person (body pressure), it will expand and deform to encase the upper body when the seated person leans against it, providing a high level of fit and cushioning.However, in the invention of claim 4, when the seated person twists their upper body while leaning against the backrest, the backrest board can be twisted and deformed to follow the movement of the body, eliminating the feeling of pressure on the seated person's body and ensuring a high level of fit.

[0027] Sometimes a seated person leans their body to the right or left and leans against the backrest, which means that the upper body is in one-sided contact with the backrest, but even in this case, the backrest twists and deforms around its axis, allowing the body to lean back smoothly and without any discomfort. Therefore, even in this case, the seat provides an excellent fit and is comfortable to use.

[0028] The support member can have a variety of structures, but adopting a horizontal H-shaped configuration with support bodies above and below the back support column as in claim 5 has the advantage of being a simple structure yet capable of stably supporting the body with the upper and lower support bodies.

[0029] By connecting the left and right ends of the backrest board to the upper and lower support bodies as in claim 6, the left and right support span of the backrest board can be maximized, which makes it easier for the backrest board to deform to envelop the body of the seated person when they lean against the backrest, thereby improving the fit.

[0030] The connecting part that attaches the backrest to the support member can take various forms, but if a fitting structure consisting of a protrusion or recess is adopted as in claim 7, it is easy to form a temporary engagement part in the connecting part by using the protrusion or recess. Also, since the connecting part of the backrest and the connecting part of the support member fit together in the fully fixed state, the fixed state can be firmly maintained even after assembly, which is preferable. [Brief explanation of the drawings]

[0031] [Figure 1] 1A and 1B are external views of a chair according to an embodiment, in which (A) is a perspective view seen from the front, (B) is a side view, (C) is a perspective view seen from the back, and (D) is a plan view. [Figure 2] (A) is a front view with the seat cushion separated, (B) is a perspective view from below, and (C) is a rear view. [Figure 3] (A) is a perspective view of the main elements separated, (B) is a side view of only the backrest (shown in a tilted position relative to the vertical line V), and (C) is a separated perspective view from below. [Figure 4] (A) is a perspective view of the backrest only, seen from behind; (B) is a separate perspective view of the back, seen from the front; (C) is a separate perspective view of the back, seen from behind; and (D) is a partial perspective view of the lower reinforcement body. [Figure 5] (A) is an oblique view of the back with the rear cover removed, (B) is an oblique view of the back as seen from a slightly different direction, similar to (A), (C) is a front oblique view of the center rear cover, and (D) is a front oblique view of the side rear cover. [Figure 6] These figures show the upper connecting structure, where (A) is an oblique view of one corner of the backrest seen from behind, (B) is a separated oblique view of the backrest and the upper reinforcing member, (C) is a separated oblique view of the upper reinforcing member and the upper support body, and (D) is a separated oblique view of the upper support body of the upper reinforcing member and the clip body. [Figure 7] (A) is a front view of the upper part of the backrest plate, (B) is a cross-sectional view of (A) taken along the line B-B, and (C) is a longitudinal side view of the middle part of the upper end of the backrest. [Figure 8]These figures show the structure and connecting structure of the lower part of the backrest, where (A) is a partial oblique view of the lower reinforcing member, (B) is a separated oblique view of the lower reinforcing member and the lower support body, (C) is a partial oblique view of the backrest, and (D) is a partial oblique view of the lower support body. [Figure 9] (A) is a cross-sectional plan view of the end cut at line IXA-IXA in Figure 8(C), (B) is a cross-sectional plan view of the end cut at line IXB-IXB in Figure 8(C), and (C) is a cross-sectional plan view of the end of the backrest cut at the lowest hole in the main support part. [Figure 10] 8(A) is a plan cross-sectional view taken along line XB-XB in FIG. 8(C), (B) is a partial perspective view of the upper reinforcing member seen from below, and (C) is a perspective view of the end of the upper reinforcing member. [Figure 11] (A) is a side cross-sectional view of the backrest cut at the hole immediately to the right of the center line, (B) is an enlarged view of the lower end of (A), and (C) is a longitudinal side cross-sectional view cut at the communicating hole of the lower reinforcement member. DETAILED DESCRIPTION OF THE INVENTION

[0032] Next, an embodiment of the present invention will be described with reference to the drawings. In the following, terms such as front, rear, left and right will be used to specify directions. These The directions are specified as viewed from a normally seated person. The front view direction is the direction facing the seated person.

[0033] (1) Basic structure of the chair First, an overview of the chair will be described. The chair of this embodiment is applied to a swivel chair that is widely used in offices, etc. As shown in Figures 1 and 2, the chair has, as its main components, a seat 1, a backrest 2, a back frame 3 to which the backrest 2 is attached, and a leg assembly 4. The back frame 3 is an example of a support member.

[0034] 4(A) to 4(C), the backrest 2 is composed of a backrest plate 5, an upper reinforcing member 6 overlapping the upper end of the backrest plate from behind, and a lower reinforcing member 7 overlapping the lower part of the backrest plate 5 from behind, and these three components are joined together by insert molding. The backrest plate 5 is made of a soft resin material such as elastomer, and the reinforcing members 6 and 7 are made of a hard synthetic resin material such as polypropylene or polycarbonate.

[0035] On the other hand, the back frame 3 has a back support pillar 8, a left-right long upper support body 9 attached to the upper end of the back support pillar 8 so as to be horizontally rotatable, and a left-right long lower support body 10 integrally provided at the lower end of the back support pillar 8, and is generally formed in an H shape as a whole in a sideways front view. The upper reinforcing member 6 of the backrest 2 is connected to the upper support body 9, and the lower reinforcing member 7 of the backrest 2 is connected to the lower support body 10. The upper support body 9 rotates horizontally against the spring means. Therefore, the horizontal rotation of the upper support body 9 allows the backrest plate 5 to twist.

[0036] As shown in Fig. 1(A), the leg device 4 has a group of branch legs equipped with casters. Also, as shown in Fig. 2(B) and Fig. 3(A), a leg support (gas cylinder) 11 is erected in the center of the leg device 4, a base body 12 is fixed to the leg support 11, and a back frame 3 is connected to the base body 12 so as to be able to tilt rearward. More precisely, as shown in Fig. 3(C), a forward-facing portion 3a is provided integrally with the lower end of the back frame 3, and the forward-facing portion 3a is fixed to a joint member 13, which is connected to the base body 12 via left and right longitudinal support shafts 14 (see Fig. 3(A)) so as to be able to tilt rearward.

[0037] The support shaft 14 is rotatably held on the base body 12 via a torsion bar, which is an example of spring means. Therefore, the chair of this embodiment is a reclining chair in which the backrest 2 tilts backward against the elastic means.

[0038] The seat 1 has a structure in which cushioning material is placed on an inner shell (not shown) and covered with a skin material, and the inner shell is attached to an outer shell 15 shown in Figures 3(A) and 2(B). The outer shell 15 has a structure in which a movable part 15b is attached to a fixed part 15a so that it can slide back and forth, and the fixed part 15a is connected to the base body 12 and the joint member 13 so that it can rotate relatively. Therefore, when the backrest 2 tilts backward, the seat 1 tilts backward in conjunction with the backrest 2 (synchronized).

[0039] 1(C)(D), for example, the upper support body 9 of the back frame 3 extends like an arm from the back support column 8 on both the left and right sides, and in plan view has an overall bow-like (arcuate) shape that is concave forward (bulges backward). On the other hand, the upper reinforcing member 6 that forms the upper end of the backrest 2 is slightly concave forward in plan view, but the degree of concavity is much less than that of the upper support body 9, and both left and right ends of the upper reinforcing member 6 are connected to both left and right ends of the upper support body 9.

[0040] Therefore, a crescent-shaped space is formed between the upper reinforcing member 6 and the upper support body 9. As mentioned above, the upper reinforcing member 6 of the backrest 2 is made of a synthetic resin such as polypropylene, and the presence of the crescent-shaped space allows it to flex and deform slightly, bulging backward. However, the degree of deformation is not large.

[0041] As shown in Fig. 4(C), upper engagement protrusions 16 are provided on both left and right ends of the upper reinforcing member 6 so as to protrude rearward, while as shown in Fig. 4(B), upper engagement recesses 17 are formed on both left and right ends of the upper support body 9 so as to open forward, and the upper engagement protrusions 16 fit into the upper engagement recesses 17. The upper engagement protrusions 16 and the upper engagement recesses 17 are an example of the upper connecting portion recited in the claims, and details will be described later.

[0042] 4(B) and (C), the lower support body 10 extends like an arm on both the left and right sides from the lower end of the back support column 8, and is curved upward as a whole in a concave shape when viewed from behind, and is also curved forward as a whole in a large concave shape when viewed from above. Therefore, the back frame 3 has an anchor-like shape as a whole.

[0043] 7, the lower end of the backrest 2 is curved so as to bulge downward in front view, and curved so as to be concave forward (bulge backward) in bottom view. Accordingly, the lower reinforcing member 7 is also curved so as to bulge downward (concave upward) in front view (and rear view), and curved so as to be concave forward (bulge backward) in plan view (and bottom view).

[0044] For example, as can be seen from Fig. 4(C), the lower reinforcing member 7 constituting the backrest 2 overlaps the lower support body 10 of the back frame 3 over its entire length. As shown in Fig. 4(D), block-shaped lower engagement protrusions 18 tapering backward are provided on the left and right ends of the lower reinforcing member 7, while lower engagement recesses 19 into which the lower engagement protrusions 18 fit are formed on the left and right ends of the lower support body 10 of the back frame 3, as shown in Fig. 3(D). Screws 24 (see Fig. 3(D)) are inserted into the lower support body 10 from the rear toward the lower engagement recesses 19, and are screwed into the boss bodies 22 to fix the lower reinforcing member 7 (the lower part of the backrest plate 5) to the lower support body 10. The lower engagement protrusions 18 and the lower engagement recesses 19 are an example of a lower connecting portion as defined in the claims, and will be described in detail later.

[0045] The back support pillars 8 and lower support body 10 that make up the back frame 3 are reinforcing members made of, for example, aluminum die-cast parts (resin molded parts can also be used), but because they have many recesses that open toward the rear, the back surface is covered with a center rear cover 20 and left and right side rear covers 21, as shown in Figure 4(C). The center rear cover 20 has bosses 22 that protrude forward, and the bosses 22 are screwed into the lower support body 10. The side rear covers 21 are fixed to the lower support body 10 by using a group of engaging claws 23. An armrest can be attached to the lower support body 10, and the base of the armrest has the same shape as the side rear covers 21.

[0046] 11(A), for example, the backrest 2 is curved in a longitudinal side view so that the portion near the lower end is positioned furthest forward, and the portion positioned furthest forward becomes the lumbar support portion 26, the portion above the lumbar support portion 26 becomes the main support portion 27, and the portion below the lumbar support portion 26 becomes the lower support portion 28. The lumbar support portion 26 has a certain vertical width.

[0047] 2(A), the backrest 2 (backboard 5) is formed so that it is widest around the boundary between the lumbar support portion 26 and the lower support portion 28, and the main support portion 27 is formed in a generally trapezoidal shape with its width narrowing toward the top. Therefore, although the backrest 2 (backboard 5) is roughly rectangular when viewed from the front, it has a downwardly bulging shape as a whole.

[0048] Furthermore, looking at the backrest 2, when viewed from above and from the bottom, the lower end of the lower support portion 28 has a bowed shape that is deeply concave forward, and the apex (ridge) of the lumbar support portion 26 is more gently curved and concave forward than the lower end of the lower support portion 28, and furthermore, the upper end of the main support portion 27 is concave forward with a gentler curvature than the ridge of the lumbar support portion 26, but is nearly flat.

[0049] 1(A), for example, perforations 29, 30, 31 are formed in multiple rows and columns in the backrest plate 5. That is, multiple groups of three rows of perforations 29 are formed in the lumbar support portion 26, groups of six rows of perforations 30 are formed in the main support portion 27, and groups of two rows of perforations 31 are formed in the lower support portion 28. Each of the perforations 29, 30, 31 basically has a vertically long (vertically long) rectangular shape with its height greater than its left-right width, but those located on the periphery may have a non-rectangular shape due to curvature or inclination.

[0050] For example, as shown in Figures 4(A)(C) and 9(C), the left and right sides of the main support portion 27 of the backrest board 5 are formed as thick side frame portions 32 that are padded toward the rear, thereby ensuring the shape retention of the left and right sides of the backrest board 5.

[0051] (2) Fixing structure between the back panel and the upper support body As described above, the upper reinforcing member 6 is integrally joined by insert molding to the back surface of the upper end of the backrest plate 5. As shown in Fig. 6, the upper reinforcing member 6 has a left-right longitudinal shape with a length approximately equal to the left-right width of the upper end of the backrest plate 5, and the above-mentioned upper engaging protrusions 16 are provided on both left and right ends thereof so as to protrude rearward.

[0052] The portion of the upper reinforcing member 6 excluding the upper engagement protrusion 16 has a base plate 6a that forms the rear surface and first and second horizontal rib plates 6b, 6c that protrude forward from the base plate 6a on the left and right.The space surrounded by the base plate 6a and the upper and lower horizontal rib plates 6b, 6c is divided by a number of vertical rib plates 35, thereby forming a number of reference small chambers 36.

[0053] Furthermore, as shown in Figure 6(C), a lower frame portion 37 is formed in the portion of the upper reinforcing member 6 close to the upper engagement protrusion 16, which is continuous with the upper engagement protrusion 16, the second horizontal rib plate 6c, and the base plate 6a, and the portion surrounded by the lower frame portion 37 forms a side chamber 38.

[0054] 7(B) and (C), an upper thick portion 39 is formed at the upper end of the backrest plate 5 and joined integrally with the upper reinforcing member 6. The upper thick portion 39 fits into the small chambers 37 and 38 of the upper reinforcing member 6, and the upper and lower horizontal rib plates 6b and 6c are embedded in the upper thick portion 39. Then, as shown in FIG. 10(B), a number of first anchor holes 40 that open the reference small chambers 36 downward are formed in the second horizontal rib plate 6c, and the upper thick portion 39 fits into the first anchor holes 40.

[0055] Therefore, the portion of the upper thick portion 39 that fills each reference chamber 37 and the portion located below the second horizontal rib plate 6c are connected at the first anchor holes 40, and the high anchor effect increases the joining strength between the backrest plate 5 and the upper reinforcing member 6. The first anchor holes 40 reach all the way to the base plate 6a.

[0056] 7(B) and (C), the upper thick portion 39 of the backrest plate 5 has a holding portion 39a that wraps around to the back side of the upper part of the upper reinforcing member 6, but as shown in Fig. 6(C), a large number of second anchors 41 that are open at the front and back are formed on the base plate 6a of the upper reinforcing member 6, connecting the main body of the upper thick portion 39 to the holding portion 39a. Therefore, even if a person tries to lift up the holding portion 39a, the holding portion 39a will not lift up and will remain joined to the upper reinforcing member 6.

[0057] As shown in Figure 6(B), upper boss portions 42, roughly rectangular in rear view, protrude rearward and downward from both left and right ends of the upper reinforcing member 6, and upper engaging projections 16 protrude from the upper boss portions 42. The upper boss portions 42 have a recess that opens forward, and the upper thick portion 39 of the backrest plate 5 fills this forward-facing recess.

[0058] 6(B), a surrounding frame portion 43 is formed at the upper corner of the backrest plate 5, surrounding the upper boss portion 42 of the upper reinforcing member 6 from above, below, and from the outside, and the rear surface of the surrounding frame portion 43 overlaps with the front surface of the upper support body 9. As can be seen from FIG. 6(A), the rear surface of the surrounding frame portion 43 on the backrest plate 5 and the rear surface of the upper boss portion 42 on the upper reinforcing member 6 are flush with each other.

[0059] As can be clearly seen in Figure 10(C), a downwardly opening frame-shaped positioning protrusion frame 44 and downwardly facing hook-shaped engaging claws 45 are provided on the upper boss portion 42 of the upper reinforcing member 6 as the upper engaging protrusions 16. The positioning protrusion frame 44 has left and right side plates and an upper plate, and is generally H-shaped when viewed from behind, with an inward protrusion 46 provided on the inner plate.

[0060] As shown in Figures 6(C) and 6(D), the upper support body 9 has a basic trough-like structure that opens forward, with a group of reinforcing ribs 47 arranged inside. Upper engaging recesses 17 are formed on both the left and right ends, and are partitioned by end ribs 48. Thickness reduction portions 49 are formed on the outer sides of the upper engaging recesses 17 to equalize the thickness, and pockets 51 are formed below the upper engaging recesses 17 to form engaging holes 50.

[0061] The pocket portion 51 is open to the front and is inclined so as to become higher toward the rear, and the pocket portion 51 and the upper engagement recess 17 communicate with each other via the engagement hole 50. In other words, because it is not possible to have the engagement hole 50 open downward of the upper reinforcing member 6 from an aesthetic standpoint, the pocket portion 51 is provided in an inclined position, and therefore the engagement hole 50 is formed in the bottom plate of the upper engagement recess 17 in a state that allows for die-cutting.

[0062] The positioning protrusion frame 44 of the upper reinforcing member 6 is sized to fit snugly into the upper engagement recess 17 of the upper support body 9 and not to shift up, down, left, right, or front, or back. The engagement claw 45 is formed at the lower end inside the positioning protrusion frame 44. The tip of the engagement claw 45 forms an upwardly inclined surface 45a, and when the positioning protrusion frame 44 is pressed into the upper engagement recess 17 of the upper support body 9, the engagement claw 45 first deforms so as to rise upward and then returns to its original shape, and the hook portion fits into the engagement hole 50. This holds the upper reinforcing member 6 (and the upper end of the backrest 2) in an inseparable manner to the upper support body 9.

[0063] Furthermore, a forward-opening slit groove 52 is formed in the end rib 48 that constitutes the upper engagement recess 17, and as shown in Figures 6(C) and 6(D) , the claw portions 53a of the clip body 53 are inserted into the slit groove 52 from the inside in the left-right direction. The clip body 53 has a base portion 53b that is located inside the end rib 48, and the claw portions 53a can be inserted into the slit groove 52 by pushing the base portion 53b outward in the left-right direction with the fingertips.

[0064] Although not shown, the inner plate of the positioning protrusion frame 44 in the upper reinforcement member 6 has a perforated hole through which the claw portion 53a of the clip body 53 passes (it is also possible for the claw portion 53a to break through the inner plate of the positioning protrusion frame 44).

[0065] The claw portion 53a of the clip body 53 is bent in a horizontal U-shape, and once elastically deformed, it enters the cut groove 52, and when it has completely entered the cut groove 52, the U-shaped bent tip surface comes out of the cut groove 52 and hits the outer surface of the end rib 48, so that the clip body 53 cannot come out of the cut groove 52.

[0066] When the clip body 53 is attached to the cut groove 52, the claw portions 53a of the clip body 53 overlap the upper surfaces of the engaging claws 45 of the upper reinforcing member 6. Therefore, the engaging claws 45 of the upper reinforcing member 6 are held by the clip body 53 so as not to move upward. The inward protrusions 46 of the positioning protrusion frame 44 abut or come into close contact with the claw portions 53a of the clip body 53 from the front. Therefore, the clip body 53 is held so as not to be removed forward.

[0067] As shown in Figures 6(C) and (D), an inverted concave void 54 is formed in the upper support body 9 next to the void into which the base 53b of the clip body 53 is inserted, and a hole 54a is formed in the upward recess. This void 54 is for attaching a headrest (not shown).

[0068] (3) Structure for insert molding As shown in Figure 7(A), a group of upper dummy recesses 55 connected to the uppermost perforation 30 is formed at the upper end of the front surface of the backrest plate 5. Also, as shown by parallel diagonal lines in Figures 1(A) and 4(B), a group of side dummy recesses 56 is formed at the left and right sides of the front surface of the backrest plate 5, and a lower dummy recess (not shown) is formed at the lower edge of the front surface of the backrest plate 5. The side dummy recesses 56 and the lower dummy recesses include those that are independent of the perforations 29, 30 and those that are connected to the perforations 29, 30.

[0069] Since the upper reinforcing member 6 is integrally joined to the upper end of the backrest plate 5 from the back side, the upper reinforcing member 6 requires an upper thick portion 39, and it is not possible to form an upper punch hole 30 in the upper thick portion 39. However, in this embodiment, an upper dummy recess 55 that is continuous with the topmost upper punch hole 30 is formed on the front surface of the upper thick portion 39, and its upper end is positioned near the upper end of the backrest plate 5, thereby maintaining the appearance that the upper punch hole 30 is extended near the upper end of the backrest plate 5, thereby achieving both aesthetics and strength.

[0070] 4(A)(C) and 9(C), thick side frame portions 32 are formed on both the left and right sides of the backrest plate 5, and these side frame portions 32 have a certain degree of width, but the above-mentioned side dummy recesses 56 are formed on the front surfaces of the side frame portions 32. The same is true for the lower edge of the backrest plate 5, and a lower dummy recess is formed in the area overlapping with the lower support body 10, extending up to the vicinity of the lower edge of the backrest plate 5.

[0071] In this way, by forming the dummy recesses 55, 56 all around the periphery of the backrest board 5, the group of perforations 29, 30, 31 appears to extend over the entire front surface of the backrest board 5, achieving a unified design. This ensures aesthetic appeal while maintaining the necessary strength for the backrest board 5.

[0072] 7(A) and (B), a through hole 57 that opens forward and backward communicates with the upper end of each upper dummy recess 55. The through hole 57 is formed so that the upper reinforcing member 6 can be firmly pressed and fixed by a pair of molds 58 and 59 that contact and separate when the backrest plate 5 is insert-molded into the upper reinforcing member 6 using the pair of molds 58 and 59, as shown in FIGS.

[0073] That is, as shown in Figures 7(B) and (C), the upper reinforcing member 6 has a base plate 6a and a first horizontally elongated rib plate 6b that is positioned at the height of the upper end of the upper punch hole 30 and protrudes forward from the base plate 6a, and while the base plate 6a is supported by one mold 58, the other mold 59 is formed with a protrusion that is continuous with the part that forms the upper dummy recess 55 and presses the first rib plate 6b of the upper reinforcing member 6, and the part where the protrusion is removed after molding appears as a through hole 57.

[0074] The upper reinforcing member 6 is long and narrow, and the upper thick portion 39 of the backrest plate 5 overlaps both left and right ends, so the left and right ends of the upper reinforcing member 6 cannot be pressed down with a pair of molds 58, 59. For this reason, if the upper reinforcing member 6 is simply placed on one of the molds 58, there is a risk that the upper reinforcing member 6 will float during molding, causing the resin to flow to the back side of the base plate 5a. In contrast, if the upper reinforcing member 6 is pressed down with a pair of molds 58, 59 as in this embodiment, floating is prevented and molding can be performed with high precision.

[0075] Therefore, although the through holes 57 are the result of a technique for precise molding, the group of through holes 57 scattered on the upper end of the backrest board 5 is visible to the human eye, and therefore also has an aesthetic effect of drawing people's attention as an accent pattern. This is one of the advantages of this embodiment.

[0076] (4) Structure of the lower part of the backrest As shown in Figures 11(B) and (C), the backrest plate 5 has a lower overlapping portion 5b that overlaps the front and underside of the lower reinforcing member 7, while as shown in Figures 4(D) and 8(A), the lower reinforcing member 7 has a channel-like shape that opens toward the rear, and its interior is divided into a number of small chambers 63 by one horizontal rib 61 and a number of vertical ribs 62.

[0077] Then, a plurality of third anchor holes 64 are drilled in the front plate (bottom) of each small chamber 63, and the resin of the backrest plate 5 is poured into the small chamber 63 through the third anchor holes 64. Therefore, as shown in Figure 11 (C), the anchor portions 5c filling the small chambers 63 of the lower reinforcing member 7 are connected to the lower overlapping portion 5b of the backrest plate 5. Therefore, the lower side portion of the backrest plate 5 is firmly joined to the lower reinforcing member 7.

[0078] The anchor portion 5c is exposed facing rearward (see, for example, FIG. 8(C)). As clearly shown in FIGS. 11(B) and 11(C), the upper surface of the lower reinforcing member 7 is also exposed. The exposed portion of the lower reinforcing member 7 is in close contact with one of the molds 58 during insert molding.

[0079] The upper reinforcing member 6 is designed to allow a slight bending deformation when used as a chair, so it is held down by a pair of molds 58, 59 to allow for accurate insert molding. However, the lower reinforcing member 7 is designed to allow for elastic deformation. To do It has unexpectedly high rigidity. Also, because it is curved in front view and plan view, the resin does not get wrapped around due to bending deformation during molding. Furthermore, it can be fixed to one mold 58 using the screws 24 mentioned above. Therefore, there is no need to hold the lower reinforcing member 7 with the other mold 59 during molding, and therefore no through holes are created due to molding.

[0080] For example, as shown in Figures 8(A), (B), and (C), lower engagement protrusions 18 in the form of truncated pyramids are provided on both left and right ends of the lower reinforcing member 7, while lower engagement recesses 19 into which the lower engagement protrusions 18 fit are provided at the leading ends of the left and right lower support bodies 10 as shown in Figure 8(B) and (D), and screws 24 inserted into the lower engagement recesses 19 from behind are threaded into nuts 67 built into the lower engagement protrusions 18. Because the lower engagement protrusions 18 and the lower engagement recesses 19 are tapered, the four surfaces are tightly attached by screwing in the screws 24, and the components are firmly fixed without any rattle.

[0081] 8(A) to 8(C), because the lower engagement protrusion 18 has a quadrangular pyramid shape, the upper engagement protrusion 16 has an inward-facing side surface 18a, but as shown in Fig. 8(D), the lower engagement recess 19 has an outward-facing inner side surface 19a that overlaps with the inward-facing side surface 18a when the lower engagement protrusion 18 is inserted from the front. Then, as shown in Fig. 9(A), the inward-facing side surface 18a of the lower engagement protrusion 18 abuts against the outward-facing inner side surface 19a of the lower engagement recess 19 from the outside in the left-right direction.

[0082] Therefore, when assembling the chair, Lower reinforcement member 7 When the lower reinforcing member 7 is stretched slightly in the left-right direction against its elasticity to apply left-right tension to the backrest board 5, and the lower engaging projections 18 of the lower reinforcing member 7 are fitted into the left-right lower engaging recesses 19 of the lower support body 10 from the front, the lower reinforcing member 7 is temporarily held attached to the lower support body 10 even if the user releases it, due to the engagement between the inward-facing side surface 18a and the outward-facing inside surface 19a. This makes it easy to screw in the screws 24.

[0083] Therefore, in this embodiment, the inward side surface 18a of the lower engagement projection 18 and the outward inner side surface 19a of the lower engagement recess 19 are Working together Alternatively, it can be said that the lower engagement protrusion 18 and the lower engagement recess 19 constitute a temporary engagement portion. When the lower engagement protrusion 18 is temporarily engaged with the lower engagement recess 19, a weakened gap is formed between the tip surface of the lower engagement protrusion 18 and the bottom surface of the lower engagement recess 19, and the two are tightly fitted together by screwing in the screw 24.

[0084] As shown in Figures 8(B) and (C), an outward-facing auxiliary protrusion 69 is provided on the outer surface of the lower engagement protrusion 18, while as shown in Figure 8(B), an auxiliary engagement hole 70 into which the auxiliary protrusion 69 fits is provided on the outer surface of the lower engagement recess 19.

[0085] The backrest board 5 can be extended left and right. been Because Lower support body 10 When temporarily held in place, the lower engaging projection 18 tends to rotate around the tip of the lower engaging projection 18 as a fulcrum, as shown by arrow 71 in FIG. 9(A), in an attempt to return to its original position. However, as can be seen from FIG. 10(A), the auxiliary projection 69 gets caught in the auxiliary engaging hole 70, and the elastic restoring force prevents the lower engaging projection 18 from returning to its original position.

[0086] 8(B) and (C), the lower engaging projection 18 has an outwardly opening pocket 68 that holds the nut 67 so that it cannot rotate, and a dummy cavity 72 into which the tip of the screw 24 fits is also open outward and communicates with the pocket 68. When insert-molding the backrest panel 5, a dummy nut (not shown) that fits into the dummy cavity 72 and the pocket 68 is attached, and a screw inserted into one of the molds 58 is screwed into the dummy nut, thereby firmly fixing the lower reinforcing member 7 to one of the molds. Because resin does not flow into the location of the dummy nut, a dummy cavity 72 that allows the screw 24 to be screwed in is formed.

[0087] It is preferable to apply tension to the backrest board 5 in the vertical direction as well, but since it is structurally difficult to strongly stretch the backrest board 5 in the vertical direction, it is reasonable to apply tension in the vertical direction by pulling it in using the tapered surfaces of the lower engagement protrusion 18 and the lower engagement recess 19.

[0088] For example, as shown in Figures 8(A) and 8(B), upward protrusions 7a are provided on both the left and right ends of the lower reinforcing member 7, extending to the sides of the lumbar support portion 26. As can be seen from Figures 1(A) and 1(C), for example, the upward protrusions 7a support the sides of the lumbar support portion 26 on the backrest plate 5. Therefore, even if the pressing force of the seated person acts on the lumbar support portion 26, the lumbar support portion 26 will not deform excessively. In other words, both the left and right ends of the lumbar support portion 26 are firmly supported by the upward protrusions 7a.

[0089] As shown in Figure 8(B), the portion of the lower reinforcing member 7 where the lower engagement protrusion 18 is provided has a slightly stepped recess 73, and as shown in Figure 8(D), the lower support body 10 has a rib 74 that fits into the recess 73 of the lower reinforcing member 7 (see also Figure 10(A)).

[0090] In this embodiment, the upper connecting portion is held inseparably by itself on the upper support body, and a temporary engagement portion is provided on the lower connecting portion, but the reverse relationship is also possible. In the reverse case, the lower connecting portion is connected first, and then the upper connecting portion is connected and permanently fixed with screws. It is also possible to provide temporary engagement portions on both the upper and lower connecting portions.

[0091] Although the backrest in the embodiment is generally rectangular, it may be circular or elliptical. In the case of a rectangular shape, it may be formed into a trapezoid whose width narrows downward. As the temporary engagement portion, it is also possible to form a protrusion on the side surface facing inward from the engagement protrusion, and form an engagement hole on the inner surface of the engagement recess. Alternatively, it is also possible to form an engagement recess on the side surface facing inward from the engagement protrusion, and form an engagement protrusion on the inner surface of the engagement recess.

[0092] In the embodiment, a back frame is used as a support member for the backrest, but a shell-shaped structure can also be used. When using a back frame, a rectangular shape having left and right side members can also be used. [Industrial Applicability]

[0093] The present invention can be embodied in a chair back, and therefore has industrial applicability. [Explanation of symbols]

[0094] 2 backrest 3 Back frame as an example of a support member 5 Backrest board 6 Upper reinforcement member 7 Lower reinforcement member 7a Upward protruding part 8 back support 9 Upper support body 10 Lower support body 16 Upper engagement protrusion constituting the upper connecting portion 17 Upper engagement recess constituting the upper connecting portion 18 Lower engagement protrusion constituting the lower connecting portion 18a Inward side surface constituting the temporary engagement portion 19a Outward-facing inner surface constituting the temporary engagement portion 24 bis 39 Upper thick wall part 44 Positioning protrusion frame constituting the upper engagement protrusion 45 Upper engagement protrusion and engagement claw 67 Nut 69 Auxiliary projection 70 Auxiliary engagement hole

Claims

1. A seatback comprising a backrest plate made of a soft material that can be flexibly deformed by the pressure of a seated person, and support members to which the upper and lower parts of the backrest plate are attached, A left and right longitudinal reinforcing member made of a material harder than the backrest plate is integrally provided on the upper or lower part or both of the backrest plate, and a connecting portion attached to the support member is provided on both left and right ends of the reinforcing member, The left and right connecting portions of the one or two reinforcing members are provided with temporary engagement portions that apply tension in the left and right direction to the reinforcing members when the reinforcing members are attached to the support member. Chair back.

2. The reinforcing member is integrally formed on the backrest plate by insert molding.

2. The chair back of claim 1.

3. The reinforcing members are provided at the upper and lower parts of the backrest board, and each connecting part of the upper and lower reinforcing members has an engaging structure that fits into the connecting part of the support member, The connecting portion of one of the upper and lower reinforcing members is held in an inseparable manner by fitting to the support member, The connecting portion of the other of the upper and lower reinforcing members has the temporary engagement portion and is temporarily fastened to the support member and then permanently fixed with a screw.

3. The chair back of claim 2.

4. The backrest plate has a substantially rectangular shape when viewed from the front, and its upper and lower sides are attached to the support member via the reinforcing member, and is allowed to twist and deform around a vertical axis. A chair back according to any one of claims 1 to 3.

5. The support member is a back frame having a left-right longitudinal upper support body, a left-right longitudinal lower support body, and a top-bottom longitudinal back support column, The upper edge portion of the backrest plate is connected to the upper support body via the upper reinforcing member, The lower edge portion of the backrest plate is connected to the lower support body via the lower reinforcing member, The upper support body is attached to the back support column so as to be horizontally pivotable against elasticity.

5. The chair back according to claim 4.

6. The backrest plate is attached to the upper support body and the lower support body at the left and right ends of the upper and lower sides via the reinforcing members, respectively. A chair back according to claim 5.

7. Each connecting portion of the reinforcing member has a shape of a protrusion or a recess that fits into the support member from the front-rear direction. A chair back according to any one of claims 1 to 6.

8. A chair comprising the backrest according to any one of claims 1 to 7.

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