Backrest and chair

Abstract

In a configuration in which the armrest is integrally attached to the backrest, the backrest and the chair having the backrest are made robust. [Solution] The backrest 7 has a lower end connected to the support structure 3 and comprises a pair of left and right upright rods 40 that extend vertically at a position on the left and right outer side of the seat, a pair of left and right armrests 46, an upper connecting rod 45 that extends rearward from a point above the lower end of each of the pair of upright rods 40 and connects the pair of upright rods 40 together, and a lower connecting rod 50 that connects the points below the connection point with the upper connecting rod 45 on each of the pair of upright rods 40 together.

Description

Technical Field

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[0001] The present invention relates to a backrest and a chair.

Background Art

[0002] There is a chair having a pair of armrests connected to both left and right sides of a seat body and a backrest connecting the pair of armrests integrally (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional chair having a pair of armrests and a backrest integrally, there is a problem that the pair of armrests are likely to deform so as to open.

[0005] Therefore, in the present invention, in a configuration in which an armrest portion is provided integrally with a backrest, the backrest and the chair having the backrest are made robust.

Means for Solving the Problems

[0006] The backrest according to the first aspect of the present invention has a lower end portion connected to a support structure, a pair of left and right upright portions extending along the vertical direction at positions outside the left and right directions of the seat, a pair of left and right armrest portions, an upper connecting portion that extends rearward from a position above the lower end portion in each of the pair of upright portions and connects the pair of upright portions, and a lower connecting portion that connects positions below the connection portions of each of the pair of upright portions with the upper connecting portion.

[0007] According to the first embodiment, the upper connecting portion having an armrest cooperates with a pair of upright portions and a lower connecting portion to form a closed loop structure. This allows the displacement of any part of the upper connecting portion, the pair of upright portions, or the lower connecting portion to be restrained by the other parts, making it possible to resist the load applied to a part of the backrest as a whole. Therefore, a robust backrest can be provided.

[0008] A backrest according to a second aspect of the present invention is a backrest according to the first aspect described above, wherein the lower connecting portion may connect the portions of each of the pair of upright portions above the lower end portions.

[0009] According to the second embodiment, the entire backrest can be reinforced in a balanced manner by separating the part connected to the support structure and the part to which the pair of upright parts are connected in the vertical direction.

[0010] A backrest according to a third aspect of the present invention may further include a tensioning material that, in the backrest according to the first or second aspect, is stretched vertically to bridge the gap between the upper connecting portion and the lower connecting portion, covering the upper connecting portion and the lower connecting portion from the seating space side, and forming a load-bearing surface that supports the weight of the seated person.

[0011] According to the third embodiment, the formation of a load-bearing surface allows the seated person to support their body in a more balanced manner than when they directly contact the upper and lower connecting parts.

[0012] A backrest according to a fourth aspect of the present invention is a backrest according to the third aspect described above, wherein the front end of the lower connecting portion may be located in the middle portion of the backrest in the left-right direction, and is positioned in front of the front end of the upper connecting portion.

[0013] According to the fourth embodiment, the upholstery is stretched upwards at the rear between the upper and lower connecting parts. This allows the load-bearing surface to have an appropriate shape that conforms to the shape of the sitter's back, thereby achieving a good seating comfort.

[0014] A backrest according to a fifth aspect of the present invention is a backrest according to any of the first to fourth aspects described above, wherein at least one of the upper connecting portion and the lower connecting portion may be curved or bent so as to be convex to the rear in a plan view.

[0015] According to the fifth embodiment, when a seated person leans against the upholstery, at least one of the upper and lower connecting parts that contact the seated person's back through the upholstery has a shape that conforms to the shape of the back, thus forming a load-bearing surface that better conforms to the shape of the human back. Therefore, a better seating comfort can be achieved.

[0016] A backrest according to a sixth aspect of the present invention is a backrest according to any of the first to fifth aspects described above, wherein the upper connecting portion may extend between the connection portions with each of the pair of upright portions without having a bent portion in a plan view.

[0017] According to the sixth embodiment, the upper connecting portion has a shape that does not have any angular parts on the outside when viewed from above. Therefore, when the backrest comes into contact with an object around the chair, damage to the backrest or the surrounding object can be suppressed.

[0018] A backrest according to a seventh aspect of the present invention may further include a lower end connecting portion that connects the lower ends of the pair of upright portions, in addition to the backrest according to any of the first to sixth aspects described above.

[0019] According to the seventh embodiment, the pair of upright parts are connected to each other not only by the upper connecting part and the lower connecting part but also by the lower end connecting part, making the backrest more robust.

[0020] An eighth aspect of the present invention is a chair comprising a backrest according to any of the first to seventh aspects described above, a support structure and a seat connected to the backrest.

[0021] According to the eighth aspect, a robust chair can be provided.

Advantages of the Invention

[0022] According to the present invention, in the configuration in which the armrest portion is integrally provided with the backrest, the backrest and the chair having the backrest can be made robust.

Brief Description of the Drawings

[0023] [Figure 1] It is a perspective view of the chair 1 according to the embodiment seen from above. [Figure 2] It is a perspective view of the chair 1 according to the embodiment seen from below. [Figure 3] It is a cross-sectional view taken along line III-III of FIG. 6. [Figure 4] It is a cross-sectional view taken along line IV-IV of FIG. 7. [Figure 5] It is a perspective view of the load support member 9 according to the embodiment. [Figure 6] It is a front view of the chair 1 according to the embodiment. [Figure 7] It is a side view of the chair 1 according to the embodiment. [Figure 8] It is a plan view of the chair 1 according to the embodiment. [Figure 9] It is a cross-sectional view taken along line IX-IX of FIG. 8. [Figure 10] It is a cross-sectional view taken along line X-X of FIG. 5. [Figure 11] It is a cross-sectional view taken along line XI-XI of FIG. 5. [Figure 12] It is a rear view showing the middle portion in the left-right direction of the upper connecting rod portion 45 of the embodiment.

Mode for Carrying Out the Invention

[0024] Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplication of these components may be omitted. Furthermore, in the following description, directions such as front, back, up, down, left, and right will be the same as the direction of a person (seatee) seated in a chair in a normal posture. That is, the direction in which the seatee faces forward will be referred to as "front," and the opposite direction will be referred to as "rear." In each figure, the arrow UP indicates upward, the arrow FR indicates forward, and the arrow LH indicates left. In this embodiment, "integrally formed" means that at least a portion of all parts of the object are formed from a single member. That is, when multiple parts are integrally formed, a continuous member is provided for all parts of the object. However, a member other than the single member may be provided for a portion of the object.

[0025] Figure 1 is a perspective view of the chair 1 according to this embodiment, seen from above. As shown in Figure 1, the chair 1 of this embodiment comprises a support structure 3, a seat 5, and a backrest 7. The chair 1 has a seating space S above the seat 5.

[0026] Figure 2 is a perspective view of the chair 1 according to the embodiment, seen from below. Note that in Figures 2 and subsequent figures, the upholstery material 70, which will be described later, may not be shown. As shown in Figures 1 and 2, the support structure 3 comprises a leg 10 and a support base 15.

[0027] The leg body 10 comprises a multi-legged leg 11 and a leg column 12. Each leg of the multi-legged leg 11 is fitted with a caster that can move on the floor. A footrest may be fitted to the multi-legged leg 11. The leg column 12 extends upward from the center of the multi-legged leg 11. The leg column 12 contains a gas spring, which is the lifting mechanism of the chair 1. The gas spring is configured such that an inner cylinder is supported so as to be able to move up and down and rotate relative to an outer cylinder (not shown) provided inside the leg column 12. The support base 15 is connected to the upper end of the leg column 12 (inner cylinder). The support base 15 supports the seat 5 from below. A lever for operating the gas spring is attached to the support base 15.

[0028] The seat 5 supports the buttocks and thighs of the sitter. The seat 5 is indirectly supported by the base 15 of the support structure 3 via the backrest 7. The seat 5 comprises a seat plate 20 that receives the seating load and a cushion 23 positioned above the seat plate 20. The seat plate 20 is formed in a circular or rectangular shape in plan view such that its plan view shape substantially matches the plan view shape of the seat 5. The cushion 23 is positioned along the upper surface of the seat plate 20 and is supported by the seat plate 20. The cushion 23 is positioned so as to overlap the entire seat plate 20 when viewed from above.

[0029] Figure 3 is a cross-sectional view along line III-III in Figure 6. Figure 4 is a cross-sectional view along line IV-IV in Figure 7. As shown in Figures 2 to 4, the seat 5 further comprises a seat plate support member 26. The seat plate support member 26 supports the seat plate 20 from below. The seat plate support member 26 is connected to the seat plate 20 so as to be displaceable in the front-rear direction. The seat plate support member 26 is connected to the seat plate 20 so as not to be displaceable in the up-down and left-right directions.

[0030] As shown in Figures 1 and 2, the backrest 7 is supported by the support structure 3. The backrest 7 has a load-bearing surface 8 that supports the weight of the seated person above the seat 5. The backrest 7 is not tiltable relative to the seat 5. The backrest 7 is formed substantially symmetrically. The backrest 7 comprises a load-bearing member 9 and an upholstery member 70.

[0031] Figure 5 is a perspective view of the load-supporting member 9 according to this embodiment. As shown in Figure 5, the load-supporting member 9 comprises a seating portion 30, a pair of left and right horizontal rod portions 35, a pair of left and right upright rod portions 40, an upper connecting rod portion 45, and a lower connecting rod portion 50.

[0032] As shown in Figures 3 to 5, the seat support portion 30 is coupled to the support structure 3 so as not to be displaceable in the vertical and horizontal directions. The seat support portion 30 is coupled to the seat 5 so as not to be displaceable in the vertical direction. The seat support portion 30 has a lower surface 30l that is supported by the support structure 3 and an upper surface 30u that supports the seat 5 from below. By coupling to the seat plate support member 26 of the seat 5 from below, the seat support portion 30 interposes between the seat 5 and the support base 15, indirectly connecting the seat 5 and the support base 15. The seat support portion 30 comprises an upper wall portion 31 that extends horizontally and a peripheral wall portion 32 that extends downward from the upper wall portion 31. The upper wall portion 31 and the peripheral wall portion 32 are formed integrally.

[0033] The upper wall portion 31 is the part of the seat support portion 30 that has a lower surface 30l and an upper surface 30u. The upper wall portion 31 is plate-shaped with a rectangular plan view, having one pair of sides extending in the front-to-back direction and the remaining pair of sides extending in the left-to-right direction. The support base 15 is connected to the upper wall portion 31 from below, and the seat plate support member 26 is connected to it from above. The support base 15 and the seat plate support member 26 are fastened to the upper wall portion 31 by a common fastening member.

[0034] The peripheral wall portion 32 extends downward from the outer peripheral edge of the upper wall portion 31. The peripheral wall portion 32 is connected to the outer peripheral edge of the upper wall portion 31 all around. Thus, the peripheral wall portion 32 comprises a pair of left and right side wall portions 32a extending in the front-rear direction, and a front wall portion and a rear wall portion extending in the left-right direction. The seating portion 30 is formed in a box shape with an opening at the bottom. The support base 15 is positioned inside the seating portion 30.

[0035] Figure 6 is a front view of chair 1 according to the embodiment. As shown in Figures 5 and 6, the pair of horizontal rods 35 correspond one-to-one with the pair of side wall portions 32a. The horizontal rods 35 are connected to the side wall portions 32a. The horizontal rods 35 are formed integrally with the seat support portion 30. In this embodiment, the entire horizontal rod 35 is formed integrally with the entire seat support portion 30. The horizontal rods 35 are connected to the intermediate portion in the front-rear direction of each side wall portion 32a. That is, the horizontal rods 35 are connected to a location in the front-rear direction that is spaced apart from the front and rear ends of each side wall portion 32a. The horizontal rods 35 extend outward in the left-right direction from each side wall portion 32a. The horizontal rods 35 extend along the left-right direction in the space below the seat 5. It is preferable that the horizontal rod portion 35 is not in contact with the seat 5, but in configurations such as when the seat plate 20 is not displaced in the front-rear direction relative to the seat plate support member 26, the horizontal rod portion 35 may be in contact with the seat 5. The outer end of the horizontal rod portion 35 is located outside the seat 5 in a plan view.

[0036] The cross-sectional shape of the horizontal rod portion 35 perpendicular to the left-right direction is rectangular, with the front-to-back direction as its longitudinal direction. The upper surface 35u of the horizontal rod portion 35 is connected to the upper surface 30u of the seating portion 30 via a stepped surface 32b provided on the side wall portion 32a that faces outward in the left-right direction. As a result, the upper surface 35u of the horizontal rod portion 35 extends outward in the left-right direction from a position lower than the upper surface 30u of the seating portion 30. Note that the normal direction of the stepped surface 32b does not have to be parallel to the left-right direction; it is sufficient that the normal vector of the stepped surface contains a component that points outward in the left-right direction.

[0037] Figure 7 is a side view of chair 1 according to this embodiment. As shown in Figures 5 and 7, a pair of upright rods 40 correspond one-to-one with a pair of horizontal rods 35. The upright rods 40 are connected to the horizontal rods 35. The upright rods 40 are formed integrally with the horizontal rods 35. In this embodiment, the upright rods 40 are formed integrally with the entire horizontal rods 35. The upright rods 40 have length in the vertical direction. The upright rods 40 have lower ends connected to the left-right outer ends of each horizontal rod 35. The lower ends of the upright rods 40 are indirectly connected to the support structure 3 via the horizontal rods 35 and the seat receiving portions 30. The upright rods 40 are an example of an "upright portion". The upright rods 40 extend upward from their lower ends into the left-right outer space of the seat 5 in a front view. The load-supporting member 9 is smoothly bent so that its outer surface is continuous at the connection point between the horizontal rod portion 35 and the upright rod portion 40. The upright rod portion 40 intersects the seat 5 in a side view from the left and right directions. The upper end of the upright rod portion 40 is within the formation range of the seat support portion 30 in the front-rear direction.

[0038] The cross-sectional shape of the upright rod portion 40 perpendicular to the vertical direction is rectangular, with the front-to-back direction as its longitudinal direction. The upright rod portion 40 has a rectangular cross-sectional shape, which improves its rigidity against loads from vertically above. The upright rod portion 40 comprises a front surface 40f facing forward and an inner surface 40i facing the seating space S. For example, the front surface 40f is defined by the area of ​​the outer surface of the upright rod portion 40 that is visible from the front. The front surface 40f is provided along the entire length of the upright rod portion 40. The inner surface 40i is provided along the entire length of the upright rod portion 40. The inner surface 40i is continuous with the upper surface 35u of the horizontal rod portion 35.

[0039] Figure 8 is a plan view of chair 1 according to an embodiment. As shown in Figures 5 and 8, the upper connecting rod 45 connects the upper ends of the pair of upright rods 40. The upper connecting rod 45 is integrally formed along its entire length between the connection points with each of the pair of upright rods 40. The upper connecting rod 45 is integrally formed with the upright rods 40. The upper connecting rod 45 extends rearward from each upright rod 40. In plan view, the upper connecting rod 45 is formed in a U-shape that opens forward and is curved to be convex rearward. The upper connecting rod 45 extends between the connection points with each upright rod 40 without having any bends in plan view. That is, the upper connecting rod 45 is formed along its entire length by either a portion that extends linearly in plan view, a portion that is curved in plan view, or both. The upper connecting rod 45 is positioned to surround the seating space S from both the left and right sides and the rear. In a side view from the left and right directions, the upper connecting rod 45 extends upward and backward from its front end (see Figure 7). The load-supporting member 9 is smoothly bent so that its outer surface is continuous at the connection point between the upright rod 40 and the upper connecting rod 45. The upper connecting rod 45 comprises a pair of left and right armrests 46, a backrest 47, and an extension 48.

[0040] As shown in Figure 5, a pair of armrests 46 correspond one-to-one with a pair of upright rods 40. The armrests 46 have length in the front-rear direction. The armrests 46 have front ends connected to the upper ends of the upright rods 40. The front ends of the pair of armrests 46 are the front ends on both the left and right sides of the upper connecting rod 45. The armrests 46 extend rearward from their front ends in a plan view. The cross-sectional shape of the armrests 46 perpendicular to the front-rear direction is a rectangle with one pair of sides extending vertically and the remaining pair of sides extending horizontally. The left-right outer and upper corners 46a of the armrests 46 are located at the outermost left-right position of the armrests 46 at any position in the front-rear direction of the armrests 46.

[0041] The backrest portion 47 is connected to a pair of armrest portions 46. The backrest portion 47 is formed integrally with the pair of armrest portions 46. The backrest portion 47 extends between the rear ends of the pair of armrest portions 46. The backrest portion 47 extends outward in the left-right direction from the left-right intermediate portion of the upper connecting rod portion 45 located behind the seating space S, and connects to the rear ends of the pair of armrest portions 46. The backrest portion 47 only needs to include the left-right intermediate portion of the upper connecting rod portion 45 and have a region that extends along the left-right direction, and the boundary between the armrest portion 46 and the backrest portion 47 does not need to be uniquely defined. However, for example, if the upper connecting rod portion has a clearly bent portion in a plan view, that bent portion may be used as the boundary between the armrest portion and the backrest portion.

[0042] The cross-sectional shape of the backrest portion 47 perpendicular to the left-right direction is a quadrilateral shape in which one pair of sides extend along the vertical direction and the remaining pair of sides extend upward towards the rear. The upper and rear corner 47a of the backrest portion 47 is the rearmost position of the backrest portion 47 at any position in the front-rear direction of the backrest portion 47. The upper and rear corner 47a in the middle of the backrest portion 47 in the left-right direction is the rear upper end of the upper connecting rod portion 45. The upper and rear corner 47a of the backrest portion 47 is continuous with the outer and upper corner 46a of the armrest portion 46 in the left-right direction. That is, the outer and upper corner 45a in the horizontal direction of the upper connecting rod portion 45 is the edge that is located furthest outward in the horizontal direction of the upper connecting rod portion 45. In this embodiment, the horizontally outer and upper corner 45a of the upper connecting rod portion 45 is located furthest outward in the horizontal direction from the seat 5 and the load-supporting member 9.

[0043] The extension portion 48 extends downward from the middle of the backrest portion 47 in the left-right direction. The entire extension portion 48 is formed integrally with the backrest portion 47. The extension portion 48 extends in the left-right direction along the backrest portion 47. The lower end surface of the extension portion 48 is inclined with respect to the horizontal direction and faces downward and rearward (see Figure 9).

[0044] The upper connecting rod portion 45 comprises an upper surface 45u facing upward and an inner surface 45i facing the seating space S. For example, the upper surface 45u is defined as the area of ​​the outer surface of the upper connecting rod 45 that is visible from above. The upper surface 45u is provided along the entire length of the upper connecting rod 45. That is, the upper surface 45u is provided continuously from the front end of the pair of armrests 46 to the backrest 47. The upper surface 45u is continuous with the front surface 40f of the upright rod 40. In this embodiment, the upper surface 45u is a continuous plane along its entire length, except for the rounded portions on both side edges. The upper surface 45u faces forward and upward. That is, the upper surface 45u faces upward and forward when viewed from the left and right directions (see Figures 6 and 7). The upper surface 45u may also face upward when viewed from the left and right directions. The portion of the upper surface 45u formed on the armrest 46 is the armrest surface on which the seated person rests their arms (including elbows). The armrest surface of this embodiment can support the portion of a seated person's arm from the forearm to the elbow. However, it is sufficient that the armrest surface can support at least the seated person's forearm or elbow. The armrest surface may face upward and inward in the left-right direction, or upward and outward in the left-right direction, when viewed from the front-back direction.

[0045] The inner surface 45i is a concave curved surface that extends in a U-shape in plan view, corresponding to the plan view shape of the upper connecting rod portion 45. The inner surface 45i is provided along the entire length of the upper connecting rod portion 45. That is, the inner surface 45i is provided continuously from the front end of the pair of armrest portions 46 to the backrest portion 47. The inner surface 45i is continuous with the inner surface 40i of the upright rod portion 40. Furthermore, the inner surface 45i is provided continuously from the backrest portion 47 to the extension portion 48. The portion of the inner surface 45i formed on the armrest portion 46 faces inward in the left-right direction when viewed from above (see Figure 8). The portion of the inner surface 45i formed on the backrest portion 47 and the extension portion 48 faces forward when viewed from above (see Figure 8). Of the inner surface 45i, the region located within the formation range of the extension portion 48 in the left-right direction extends forward as it goes downward (see Figure 9).

[0046] The lower connecting rod 50 connects the pair of upright rods 40. The lower connecting rod 50 is positioned below the upper connecting rod 45. The lower connecting rod 50 is positioned above the lower end connecting portion 55, which is the lower end connecting portion 55 that connects the lower ends of the pair of upright rods 40, when the pair of horizontal rods 35 and seating portions 30 are referred to as the lower end connecting portion 55. The lower connecting rod 50 is connected to a point above the lower end of the upright rod 40 and below the connection point with the upper connecting rod 45. In other words, the lower connecting rod 50 is connected to the vertically intermediate portion of the upright rod 40. However, the vertically intermediate portion of the upright rod 40 does not have to be equidistant from the upper and lower ends of the upright rod 40. The lower connecting rod portion 50 is formed integrally with the upright rod portion 40. The lower connecting rod portion 50 is positioned above the seat 5 and has a vertical gap with respect to the seat 5 when viewed from the front (see Figure 6). The lower connecting rod portion 50 extends rearward from each upright rod portion 40. The lower connecting rod portion 50 is formed in a U-shape that opens forward when viewed from above and is curved to be convex towards the rear. The lower connecting rod portion 50 extends between the connection points with each upright rod portion 40 without having any bends when viewed from above. The lower connecting rod portion 50 is positioned to surround the seating space S from both the left and right sides and from the rear. When viewed from the left and right sides, the lower connecting rod portion 50 extends rearward from its front end. The front end of the middle section in the left-right direction of the lower connecting rod 50 is located further forward than the front end of the middle section in the left-right direction of the upper connecting rod 45.

[0047] In this embodiment, the load-bearing member 9 is formed from a single component. As a result, the seating portion 30, the pair of horizontal rod portions 35, the pair of upright rod portions 40, and the upper connecting rod portion 45 are integrally formed.

[0048] As shown in Figures 5 and 6, the lower connecting rod portion 50 comprises a downward-facing lower surface 50l and an inner surface 50i facing the seating space S. For example, the lower surface 50l is defined by the area of ​​the outer surface of the lower connecting rod portion 50 that is visible from below. The lower surface 50l is provided along the entire length of the lower connecting rod portion 50. The inner surface 50i is a concave curved surface that extends in a U-shape in plan view, corresponding to the plan view shape of the lower connecting rod portion 50. The inner surface 50i is provided along the entire length of the lower connecting rod portion 50. The inner surface 50i is continuous with the inner surface 40i of the upright rod portion 40. The inner surface 50i is located in the middle of the load-supporting member 9 in the left-right direction, forward of the entire inner surface 45i of the upper connecting rod portion 45 (see Figure 9).

[0049] Figure 9 is a cross-sectional view of the IX-IX line in Figure 8. Figure 10 is a cross-sectional view of the XX line in Figure 5. Figure 11 is a cross-sectional view of the XI-XI line in Figure 5. As shown in Figures 5 and 9 to 12, the load-supporting member 9 has an engagement recess 60 into which the tensioning member 70 engages. The engagement recess 60 comprises an upper engagement recess 61 formed in the upper connecting rod portion 45, a pair of left and right side engagement recesses 62 formed in each upright rod portion 40, and a lower engagement recess 63 formed in the lower connecting rod portion 50. The engagement recess 60 extends continuously in an annular shape.

[0050] As shown in Figures 5, 9, and 10, the upper engagement recess 61 is formed in the upper connecting rod portion 45. The upper engagement recess 61 opens to the upper surface 45u of the upper connecting rod portion 45. The upper engagement recess 61 opens to the edge of the upper surface 45u on the seating space S side. The upper engagement recess 61 extends along the extending direction of the upper connecting rod portion 45. The upper engagement recess 61 is provided continuously along the entire length of the upper connecting rod portion 45. The upper engagement recess 61 includes a pair of left and right armrest engagement recesses 61a located in the armrest portion 46 and a backrest engagement recess 61b located in the backrest portion 47. The armrest engagement recesses 61a and the backrest engagement recesses 61b are in direct communication with each other.

[0051] As shown in Figures 5 and 11, the side engagement recesses 62 are formed in each upright rod portion 40. The side engagement recesses 62 open to the front surface 40f of the upright rod portion 40. The side engagement recesses 62 extend along the direction of extension of the upright rod portion 40. The side engagement recesses 62 extend along the edge of the front surface 40f on the seating space S side. The upper end of the side engagement recess 62 is connected to the end of the upper engagement recess 61. Thus, the side engagement recess 62 is in direct communication with the upper engagement recess 61. The lower end of the side engagement recess 62 opens continuously from the front downwards.

[0052] As shown in Figures 5 and 9, the lower engagement recess 63 is formed in the lower connecting rod portion 50. The lower engagement recess 63 opens to the lower surface 50l of the lower connecting rod portion 50. The lower engagement recess 63 extends along the extending direction of the lower connecting rod portion 50. The lower engagement recess 63 extends along the edge of the lower surface 50l on the seating space S side. The lower engagement recess 63 is provided continuously along the entire length of the lower connecting rod portion 50. The end of the lower engagement recess 63 is connected to the lower end of the side engagement recess 62. Thus, the lower engagement recess 63 is in direct communication with the side engagement recess 62.

[0053] As shown in Figures 9 to 11, the load-bearing member 9 is provided with a communication recess 65 that connects the engagement recess 60 and the seating space S. The communication recess 65 is adjacent to the engagement recess 60 from the seating space S side. The communication recess 65 is formed to be stepped down together with the engagement recess 60 with respect to the surface of the load-bearing member 9 from which the engagement recess 60 opens. The communication recess 65 extends along the entire length of the engagement recess 60. The communication recess 65 opens from the surface of the load-bearing member 9 from which the engagement recess 60 opens to the inner surface facing the seating space S side. For example, the portion of the communication recess 65 adjacent to the upper engagement recess 61 opens from the upper surface 45u of the upper connecting rod 45 to the inner surface 45i, and is stepped down downward from the upper surface 45u. As a result, the opening end of the engagement recess 60 is open to the seating space S side through the communication recess 65. Furthermore, the communication recess 65 is formed to be shallower than the engagement recess 60 when the surface in the load-supporting member 9 from which the engagement recess 60 opens is used as a reference.

[0054] As shown in Figures 1 and 5, the tensioning material 70 is stretched over the load-bearing member 9 to form a load-bearing surface 8. The tensioning material 70 is stretched over the load-bearing member 9 so that the load-bearing surface 8 faces the torso of the seated person from the outside in the horizontal direction. The tensioning material 70 is stretched over the upper connecting rod 45, the pair of upright rods 40, and the lower connecting rod 50. The tensioning material 70 is stretched along the vertical direction so as to span between the upper connecting rod 45 and the lower connecting rod 50. The tensioning material 70 extends in a U-shape in plan view between the pair of upright rods 40. The tensioning material 70 comprises a sheet body 71 and an edge material. The sheet body 71 is formed from a sheet material such as mesh fabric, knitted fabric, or cloth. The sheet body 71 is formed by cutting the sheet material into a desired shape. In this embodiment, the sheet body 71 is formed in a rectangular shape, corresponding to the shape of the frame-shaped portion of the load-supporting member 9, which consists of the upper connecting rod portion 45, the pair of upright rod portions 40, and the lower connecting rod portion 50.

[0055] Edge members are attached to the edges of the sheet body 71. The edge members form the edges of the tensioning member 70. For example, the edge members are provided around the entire circumference of the edges of the tensioning member 70. The edge members are made of a material with higher rigidity than the sheet body 71. The tensioning member 70 engages with the engagement recess 60 by inserting the edge members into the engagement recess 60 (see Figures 9 to 12). The edge members are provided on the upper edge 72, the left and right side edges 73, and the lower edge 74 of the tensioning member 70. The upper edge 72 of the tensioning member 70 engages with the upper engagement recess 61. The left and right side edges 73 of the tensioning member 70 engage with the side engagement recess 62. The lower edge 74 of the tensioning member 70 engages with the lower engagement recess 63. The outer peripheral edge of the tensioning member 70 is inserted into the engagement recess 60 around its entire circumference.

[0056] The seat body 71 is pulled out from the engaging recess 60 through the communication recess 65 toward the seating space S. The tensioning material 70 is positioned so that the seat body 71 does not protrude from the surface in which the engaging recess 60 of the load-supporting member 9 opens, as the seat body 71 passes through the communication recess 65. The seat body 71 is positioned so that it does not cover the horizontal outer and upper corner 45a of the upper connecting rod 45, as it is pulled out from the engaging recess 60 toward the seating space S. The tensioning material 70 exposes the majority of the upper surface 45u over its entire length so as to expose the outer edge of the upper surface 45u of the upper connecting rod 45 in a plan view. In this embodiment, the tensioning material 70 exposes the entire portion of the upper surface 45u of the upper connecting rod 45 that is outside the width center in a plan view (opposite side from the seating space S) at all positions in the extending direction of the upper connecting rod 45. The seat body 71 covers the inner surface 45i of the upper connecting rod portion 45, the inner surface 40i of the pair of upright rod portions 40, and the inner surface 50i of the lower connecting rod portion 50 from the seating space S side. The seat body 71 closes the inner space of the frame consisting of the upper connecting rod portion 45, the pair of upright rod portions 40, and the lower connecting rod portion 50 from the seating space S side.

[0057] Here, the portion of the load-supporting member 9 to which the tensioning material 70 is stretched is referred to as the tensioned portion 80. In this embodiment, the tensioned portion 80 is a frame-shaped portion consisting of an upper connecting rod portion 45, a pair of upright rod portions 40, and a lower connecting rod portion 50. The tensioned portion 80 has a through-hole that horizontally connects the seating space S and the space surrounding the chair 1 inside the area enclosed by the upper connecting rod portion 45, the pair of upright rod portions 40, and the lower connecting rod portion 50. The through-hole is closed from the seating space side by the tensioning material 70. The inner region 80a and the outer region 80b in the cross-section of the tensioned portion 80 are defined as follows: The inner region 80a is the region including the end on the horizontal seating space S side. The outer region 80b is the region including the end on the opposite side of the horizontal seating space S.

[0058] Figure 12 is a rear view showing the middle portion in the left-right direction of the upper connecting rod portion 45 of the embodiment. As shown in Figures 9 and 12, the tensioned portion 80 comprises an inner projection 81 provided in the inner region 80a and a handle portion 82 provided in the outer region 80b. In the extending direction of the tensioned portion 80, the formation ranges of the inner projection 81 and the handle portion 82 overlap with each other. However, the formation ranges of the inner projection 81 and the handle portion 82 do not have to coincide with each other, and the formation range of one of the inner projection 81 and the handle portion 82 may be wider than the formation range of the other.

[0059] The handgrip portion 82 is positioned so as viewed from the seating space S that it overlaps with the upholstery material 70. The handgrip portion 82 is convex in the cross-section of the upholstery portion 80 so that the user can grip it with their fingers from the inside of the upholstery portion 80. The handgrip portion 82 protrudes inward from the upholstery portion 80 in the cross-section. The handgrip portion 82 becomes thinner from the base to the tip in the cross-section of the upholstery portion 80. The handgrip portion 82 extends in the direction of extension of the upholstery portion 80 so as to be convex downward when viewed horizontally from the surrounding space of the chair 1.

[0060] The inner projection 81 is located between the handle portion 82 and the tensioning material 70. In the cross-section of the tensioning portion 80, the inner projection 81 protrudes inward from the tensioning portion 80 beyond the outer region 80b. In this embodiment, since the handle portion 82 is provided in the outer region 80b, the inner projection 81 protrudes inward from the tensioning portion 80 beyond the handle portion 82. In the cross-section of the tensioning portion 80, the inner projection 81 extends with a substantially constant thickness from the base end to the tip. The inner projection 81 extends in the direction of extension of the tensioning portion 80. The inner projection 81 extends along the back surface of the sheet body 71. The inner projection 81 is spaced apart from the handle portion 82 on the side closer to the sheet body 71. As a result, the tensioning portion 80 has a recess 83 that opens inward. The recess 83 receives the fingertips of fingers hooked onto the handle portion 82.

[0061] In this embodiment, the inner projection 81 is an extension 48. That is, in this embodiment, the inner projection 81 and the handgrip 82 are provided in the middle of the upper connecting rod 45 in the left-right direction. The inner projection 81 protrudes downward from the front of the backrest 47. The inner projection 81 has a front surface 81f facing the seating space S. The front surface 81f is part of the inner surface 45i of the upper connecting rod 45 and is inclined with respect to the vertical direction so as it goes downward, it extends forward. The handgrip 82 protrudes downward from the rear of the backrest 47. The handgrip 82 extends in the left-right direction along the backrest 47. Because the inner projection 81 and the handgrip 82 protrude downward from the backrest 47, they have a convex shape when viewed from the front-rear direction. The recess 83 opens to the lower surface of the upper connecting rod 45.

[0062] As described above, the backrest 7 of this embodiment includes a pair of left and right upright rods 40 extending vertically at the outer positions of the seat 5 in the left-right direction, an upper connecting rod 45 having a pair of left and right armrests 46, an upper connecting rod 45 extending rearward from a point above the lower end of each of the pair of upright rods 40 and connecting the pair of upright rods 40 together, and a lower connecting rod 50 connecting the points below the connection point with the upper connecting rod 45 on each of the pair of upright rods 40. With this configuration, the upper connecting rod 45 having the armrests 46 cooperates with the pair of upright rods 40 and the lower connecting rod 50 to form a closed loop structure. This allows the displacement of any part of the upper connecting rod 45, the pair of upright rods 40, and the lower connecting rod 50 to be restrained by the other parts, making it possible to resist the load applied to a part of the backrest 7 as a whole. Therefore, a robust backrest 7 can be provided.

[0063] The lower connecting rod 50 connects the portions of the pair of upright rods 40 above their respective lower ends. With this configuration, the portion connected to the support structure 3 and the portion where the pair of upright rods 40 are connected are spaced apart in the vertical direction, thereby providing balanced reinforcement to the entire backrest 7.

[0064] The backrest 7 further includes a tensioning material 70 that is stretched vertically across the upper connecting rod 45 and the lower connecting rod 50, covering the upper connecting rod 45 and the lower connecting rod 50 from the seating space S side, and forming a load-bearing surface 8 that supports the weight of the sitter. With this configuration, the formation of the load-bearing surface 8 allows the sitter to support their body in a more balanced manner than when the sitter's body is directly against the upper connecting rod 45 and the lower connecting rod 50.

[0065] In the middle section of the backrest 7 in the left-right direction, the front end of the lower connecting rod 50 is positioned in front of the front end of the upper connecting rod 45. With this configuration, the upholstery material 70 is stretched upwards towards the rear between the upper connecting rod 45 and the lower connecting rod 50. This allows the load-bearing surface 8 to have an appropriate shape that conforms to the shape of the sitter's back, resulting in a comfortable seating experience.

[0066] The upper connecting rod 45 and the lower connecting rod 50 are curved so as to be convex towards the rear in a plan view. With this configuration, when a seated person leans against the upholstery 70, the upper connecting rod 45 and the lower connecting rod 50 that come into contact with the back through the upholstery 70 have a shape that conforms to the shape of the back, thus forming a load-bearing surface 8 that better conforms to the shape of the human back. Therefore, a better seating comfort can be achieved.

[0067] The upper connecting rod portion 45 extends between the connection points with each of the pair of upright rod portions 40 without having any bends in a plan view. With this configuration, the upper connecting rod portion 45 has a shape that does not have any angular parts on the outside in a plan view. Therefore, when the backrest 7 comes into contact with an object around the chair 1, damage to the backrest 7 or the surrounding object can be suppressed.

[0068] The backrest 7 further includes a lower end connecting portion 55 consisting of a pair of horizontal rods 35 and a seat support portion 30 that connect the lower ends of a pair of upright rods 40. The lower connecting rod 50 is located above the lower end connecting portion 55. With this configuration, the pair of upright rods 40 are connected to each other not only by the upper connecting rod 45 and the lower connecting rod 50 but also by the lower end connecting portion 55, making the backrest 7 more robust.

[0069] It should be noted that the present invention is not limited to the embodiments described above with reference to the drawings, and various modifications are conceivable within its technical scope. For example, in the above embodiment, the horizontal rod portion 35, the upright rod portion 40, the upper connecting rod portion 45, and the lower connecting rod portion 50 of the load-supporting member 9 are formed in a rod shape (for example, a rod shape or a cylindrical shape), but these rod-shaped members may be replaced with plate-shaped members.

[0070] In the above embodiment, the tensioning material 70 is stretched over the entire tensioned section 80, but the configuration is not limited to this. That is, the tensioning material may be stretched over only a part of the tensioned section. For example, the tensioning material may be stretched over only the upper connecting rod and the lower connecting rod, leaving a gap between them and the pair of upright rods.

[0071] In the above embodiment, the upper connecting rod 45 is curved so as to be convex to the rear in a plan view, but the configuration is not limited to this. The upper connecting rod may be bent so as to be convex to the rear in a plan view, for example, at the boundary between the armrest and the backrest.

[0072] In the above embodiment, the lower end of the upright rod portion 40 is indirectly connected to the support structure 3 via the horizontal rod portion 35 and the seat receiving portion 30, but the configuration is not limited to this. The lower end of the upright rod portion may be connected to a seat supported by the support structure. In other words, the lower end of the upright rod portion may be indirectly connected to the support structure via a seat.

[0073] In the above embodiment, the horizontal rod portion 35 is connected to the support structure 3 via the seat support portion 30, but the configuration is not limited to this. The horizontal rod portion may be directly connected to the left and right outer surfaces of the support structure without going through the seat support portion. Also, if the left and right width of the support structure is approximately equal to or greater than the left and right width of the seat, the upright rod portion may be directly connected to the support structure without going through the horizontal portion and the seat support portion.

[0074] In the above embodiment, the lower connecting rod 50 is positioned above the seat 5, but the configuration is not limited to this. For example, the lower connecting rod may be positioned horizontally outward from the seat. In this case, it is desirable that the lower connecting rod has a horizontal gap with respect to the seat in a plan view.

[0075] Furthermore, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0076] 1…Chair 3...Support structure 5…za 7...backrest 8...Load supporting surface 40…Erection rod part (erecting part) 45...Upper connecting rod part (upper connecting part) 46…Armrest 47...Backrest 50...Lower connecting rod part (lower connecting part) 55…Lower end connection part 70…Tension material

Claims

1. Having a lower end connected to a support structure, a pair of left and right upright portions extending vertically at a position on the left and right outer side of the seat, It has a pair of left and right armrests, and an upper connecting portion that extends rearward from a point above the lower end of each of the pair of upright portions and connects the pair of upright portions together, A lower connecting portion connects the points below the connection point with the upper connecting portion in each of the pair of upright portions, A backrest equipped with [a specific feature].

2. The lower connecting portion connects the portions of each of the pair of upright portions above the lower end. The backrest according to claim 1.

3. The device further comprises a tensioning material stretched vertically across the upper and lower connecting portions, covering the upper and lower connecting portions from the seating space side, and forming a load-bearing surface that supports the weight of the seated person. The backrest according to claim 1 or claim 2.

4. In the middle section of the backrest in the left-right direction, the front end of the lower connecting portion is located in front of the front end of the upper connecting portion. The backrest according to claim 3.

5. At least one of the upper connecting portion and the lower connecting portion is curved or bent so as to be convex to the rear in a plan view. The backrest according to claim 1 or claim 2.

6. The upper connecting portion extends between the connection points with each of the pair of upright portions without having any bends in a plan view. The backrest according to claim 5.

7. The pair of upright portions further comprises lower end connecting portions that connect the lower ends of the pair of upright portions. The backrest according to claim 1 or claim 2.

8. The backrest described in claim 1, The support structure and the seat connected to the backrest, A chair equipped with [a specific feature / feature].

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