Chair with lumbar support device

Abstract

To prevent deterioration of body stability when a lumbar part separates from a backrest in reclining.SOLUTION: Since a rotation fulcrum 7 of a backrest is located below a seat, a space tends to be generated between a user's lumbar part and the backrest in reclining. A lumbar support device 25 includes upper / lower links 27, 28. A lumbar pad 26 is attached to the upper link 27, and the lower link 28 is connected to a bearing boss 51 of a second inclination frame 12 via an arc long hole 53 and a guide pin 52. In reclining, the lumbar support device 25 moves downward relatively to the guide pin 52. Since the arc long hole 53 inclines, a lower member 42 of the lower link 28 is pushed backward and the upper link 27 rotates forward. Thereby, the lumbar pad 26 pushes the backrest 3 forward in reclining.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a chair equipped with a lumbar support device. [Background technology]

[0002] 2. Description of the Related Art In reclining chairs in which the backrest tilts backward against elastic means, it is common to provide a lumbar support device that supports the back and waist of a user from behind via the backrest.

[0003] In reclining chairs, the basic structure for tilting the backrest backward is often a tilting frame connected to a base so that it can be freely tilted backward, and the backrest is attached to the tilting frame.In this case, a lumbar support device is attached to the tilting frame (for example, Patent Document 1).

[0004] There are various backrest structures, such as a synthetic resin shell body covered with cushioning material, or a back frame with openings at the front and back covered with mesh material, and the lumbar support device also has a different structure depending on the structure of the backrest. Patent Document 2 discloses a lumbar support device for a backrest that uses mesh material, in which the lumbar pad is tilted backward together with the backrest, and the degree of backward tilt of the lumbar pad is made greater than the degree of backward tilt of the backrest, thereby loosening the mesh material when reclining. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2008-506486 [Patent Document 2] JP 2008-295515 A Summary of the Invention [Problem to be solved by the invention]

[0006] Now, chairs equipped with lumbar support devices are often so-called swivel chairs, and are widely used for working in offices. In this regard, the manner of working in an office is mostly to operate a personal computer, and in most cases, a desktop personal computer is placed on the desk and the keyboard and mouse are operated, or a laptop computer is placed on the desk and the keys and mouse of the laptop computer are operated.

[0007] When using a computer in the office, not only is the upper body kept upright without leaning against the backrest, but the chair is sometimes reclined and the upper body tilted backwards when using the computer. However, when the backrest is attached to a tilting frame, the rotation fulcrum of the tilting frame is located below the seat, so that when the chair is reclined, the backrest often has a tendency to move away from the seat, which can result in insufficient support for the lower back when reclined.

[0008] The same is true when leaning back to relax; if a gap is created between the lower back and the backrest when reclining, the upper body may not be supported sufficiently, making it difficult to ensure a high level of relaxation.

[0009] The present invention was made in response to such circumstances, and aims to provide a chair with excellent lumbar support function. In this embodiment, many improved configurations are disclosed, but these configurations can be independent inventions. [Means for solving the problem]

[0010] The present invention includes the inventions of each claim. The invention of claim 1 is a generic concept, "The seatback has a backrest that tilts backward against an elastic means, and a lumbar pad that supports the back of the seated person from behind via the backrest. The lumbar pad is configured to move backward together with the backrest in conjunction with the backward tilting of the backrest and to push the backrest forward. The structure is as follows.

[0011] The invention of claim 2 is an example of the development of claim 1. "The lumbar pad has an upper support portion that supports the lumbar region of the seated person and a lower support portion that supports the pelvis of the seated person, and the two are vertically separated from each other." The structure is as follows.

[0012] The invention of claim 3 is an example of the development of claim 2, "The left and right width of the lower support portion is smaller than the left and right width of the upper support portion." The structure is as follows.

[0013] The invention of claim 4 is a development example of claim 2 or 3, "The lower support portion and the upper support portion are connected in series via an intermediate portion that is elastically deformed by elongation or bending in the vertical direction." The structure is as follows.

[0014] The invention of claim 5 is also an example of the development of claim 2 or 3. "When the backrest is tilted backward, the relative advancement amount of the upper support portion is greater than the relative advancement amount of the lower support portion." The structure is as follows.

[0015] The invention of claim 6 is an example of the development of claim 5. "The lumbar pad is rotatably connected to the left and right longitudinal pins of the link that rotates in conjunction with the rearward tilt of the backrest, The link rotates in the front-rear direction about its lower end as a fulcrum, so that the relative advancement amount of the upper support portion is greater than the relative advancement amount of the lower support portion when the backrest is tilted backward. In addition, a position changing device is provided that can adjust the initial position of the link by operating a lever. The structure is as follows.

[0016] The invention of claim 7 is an example of the development of claim 1 or 2, "The backrest has a back frame that is open at the front and rear, and an elastomer back panel attached to the back frame, The rigidity of the lower area of ​​the back panel, which is supported by the lumbar pad, is higher than the rigidity of the upper area, and the upper area has an elastic strength that allows it to bend backward due to the pressing force of the seated person. The structure is as follows. Effect of the Invention

[0017] The invention of claim 1 improves comfort by preventing the lower back from floating when reclining, which is caused by the backrest's tilt fulcrum being located behind the rear end of the seat. In particular, when using a PC in a reclining position leaning against the backrest, the body can be stabilized, allowing long hours of work to be done without physical problems such as stiffness or tension in the lower back. Therefore, it is also suitable as an office (work) chair.

[0018] In particular, when applied to a chair with a flexing backrest when reclining, as in the embodiment, the lumbar pad can stably support the lower back while reclining with the head upright, so the user can raise his / her head and look at the monitor on the desk with the lumbar vertebrae stably supported. This is particularly suitable as it allows the user to operate a computer without putting strain on specific parts of the body.

[0019] In claim 2, the lumbar pad can stably support the lumbar spine and pelvis, so the body can be stably supported whether the user is reclining against the backrest or not leaning against the backrest and is in an upright position. This helps to prevent hunched backs by reducing the burden on the lower back.

[0020] More specifically, when in an upright position and not leaning against the backrest, the lower support part supports the pelvis, thereby enabling the user to maintain a stable upright position; on the other hand, when in a reclined position and leaning against the backrest, the lower support part supports the pelvis and the upper support part supports the lumbar vertebrae, thereby enabling the user to maintain a stable upper body position. This well-balanced support configuration allows the body to be maintained stably in both an upright and reclining position, thereby eliminating strain on the lower back in particular and preventing physical injuries.

[0021] Now, the pelvis is a core element of the human skeleton and has a large width from side to side, while the lumbar vertebrae are smaller than the pelvis in width and have flesh spread on both sides of them. However, since the pelvis is a kind of rigid body and is hard, it has a high strength per unit area, whereas the lumbar vertebrae are made up of many vertebrae and have a low strength per unit area, and the flesh spreading on both sides of the lumbar vertebrae also has a low strength per unit area.

[0022] And, by configuring the lower support part narrow and the upper support part wide as in claim 2, the lumbar vertebrae, which have low resistance, can be supported without strain, while the pelvis, which has high resistance, can be supported without strain by the narrow lower support part. Therefore, the lumbar pad can be made as small as possible while still maintaining its support function for the human body.

[0023] The lumbar pad in Patent Document 1 only supports the back of the user and does not support the pelvis, so there is a limit to how much it can improve the stability of the body. In contrast, if the lumbar pad is made up of an upper support part and a lower support part, as described above, it can reliably support the lower back and the pelvis, improving the stability of the body.

[0024] In this case, the lower support part and the upper support part that make up the lumbar pad can be configured separately, but if they are connected in series via an elastically deformable middle part as in claim 4, the lumbar pad becomes a single item, which reduces the handling and assembly work required for storage and transportation. In addition, since the middle part deforms, the upper support part and the lower support part can move freely, improving the fit between the lumbar pad and the person's pelvis or lower back. This prevents the lumbar pad from hitting the pelvis or lower back on one side, improving the comfort of the user.

[0025] As mentioned above, in the present invention, the lumbar pad moves forward relative to the backrest in the reclined position, preventing or suppressing the formation of a gap between the backrest and the body, improving comfort and ease in the reclined position, but in the reclined position, the weight of the upper body is not applied much to the pelvis, but is applied to the backrest and lumbar pad. Therefore, the need to support the pelvis is lower than in the upright position, and the need to fit the back to the backrest over as wide an area as possible is higher.

[0026] In this regard, as in claim 5, when the upper support part is moved forward relative to the lower support part, the back, centered on the lumbar vertebrae and spine, is supported by the backrest with a good fit, so that when the user is reclined, he or she is kept in a position with his or her chest out and back straight, thereby improving comfort.

[0027] And, as in claim 6, by changing the amount of relative advancement by attaching the lower support part and the upper support part to a link, it is possible to realize the relative amount of advancement between the lower support part and the upper support part with a simple structure. Also, in claim 6, since the initial front-rear position of the lumbar pad can be adjusted, the strength of support for the body by the lumbar pad can be adjusted to suit the user's preference.

[0028] The configuration for adjusting the initial position of the lumbar pad is not limited to a configuration for relatively moving the lumbar pad forward by a mechanism other than a link, and various mechanisms can be adopted. In addition to or instead of the configuration for adjusting the initial front-rear position of the lumbar pad, it is also possible to configure the initial height position of the lumbar pad to be adjustable.

[0029] Various structures can be used for the backrest in the present invention, but by using an elastomer back panel as in claim 7 and making the rigidity of the lower area supported by the lumbar pad higher than that of the upper area, while setting the elastic strength of the upper area so that it can bend backwards due to the pressure of the seated person, it is possible to ensure a good fit in the upper area (especially while allowing for protruding deformation caused by the shoulder blades), while providing the lower area with appropriate rigidity to provide stable support for the pelvis and lumbar vertebrae.

[0030] If the entire backrest flexes and deforms too much, a high level of fit can be ensured, but physical stability is reduced, and people will unconsciously tense up in an attempt to stabilize their bodies, which can lead to physical disorders such as stiff shoulders, stiff neck, and lower back. However, in claim 7 of the present application, the pelvis and lumbar spine are stabilized, so people will not unconsciously tense up, preventing disorders such as stiffness and tension. [Brief description of the drawings]

[0031] [Figure 1] 1A is a diagram showing an embodiment, in which (A) is an overall perspective view seen from the front, (B) is an overall perspective view seen from the rear, and (C) is a partial front view of the back panel. [Diagram 2] 1A is a perspective view without the back panel and seat cushion, and FIG. 1B is a perspective view showing the frame. [Diagram 3] FIG. 1A is an exploded perspective view showing the framework, and FIG. [Figure 4] 1A is a rear perspective view of the lumbar support device, FIG. 1B is a rear separated perspective view of the lumbar support device, and FIG. 1C is a rear perspective view of a lumbar pad. [Diagram 5] FIG. 2A is a side view of the lumbar support device with some members omitted, and FIG. 2B is an exploded perspective view seen from the front. [Figure 6] (A) is a partially separated side view to explain the movement, and (B) is a front view of the back panel. [Figure 7] (A) is a partially separated side view to explain the movement, and (B) is a front view of the lumbar pad. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the terms front, back, left and right are used to specify directions, but these directions are defined as directions seen from a person normally sitting on the chair. The front view is a view from the direction opposite the seated person.

[0033] (1) Basic structure of the chair First, an overview of the chair will be described mainly with reference to Figures 1 and 2. This embodiment is applied to a swivel chair for office use. The chair has a leg device 1, a seat 2, and a backrest 3 as basic elements. The leg device 1 has a structure in which a leg support 4 made of a gas cylinder is erected in the center of a base having five leg blades, and a caster is provided at the tip of each leg blade.

[0034] For example, as shown in Fig. 2, a base 5 is fixed to the upper end of the leg support 4, and the lower tips of the left and right first tilting frames 6 are connected to the base 5 by a first reference support shaft 7 (see Fig. 3). As shown in Fig. 1(B) , the first tilting frame 6 extends backward while spreading outwardly to the left and right from the base 5, and then stands upright, and the part that stands upright and spreads outwardly to the left and right constitutes the lower side member 8a of the lower back frame 8. In other words, the first tilting frame 6 and the lower back frame 8 partially share members, and the upper part of the first tilting frame 6 constitutes the lower side member 8a of the lower back frame 8.

[0035] The lower ends of the lower side members 8a constituting the lower back frame 8 are connected by the left and right long lower members 8c. That is, the lower back frame 8 is formed by connecting the rising portions of the left and right first tilting frames 6 by the lower members 8c. As shown in Fig. 3, the positioning protrusions 8d protruding from the left and right end faces of the lower members 8c are tightly fitted into the positioning holes 8e provided on the inner surface of the lower side members 8a, and in this state, the two are fastened together by screws.

[0036] An upper back frame 9 is disposed on the lower back frame 8, which is integrated with the lower back frame 8 to form a back frame. The upper back frame 9 is configured in a loop shape with upper left and right side members 9a that are long in the vertical direction, an upper member 9b connected to the upper ends of the upper side members 9a, and a middle member 9c connected to the lower ends of the upper side members 9a.

[0037] The lower ends of the upper side members 9c of the upper back frame 9 are connected to the upper ends of the lower side members 8a by a first reference pin 10 (see the lines in FIG. 3(A)) that runs in the left-right direction. Specifically, as shown in FIG. 3(A), a bifurcated female bearing portion 11a is provided at the lower ends of the left and right side members 9a of the upper back frame 9, and a male bearing portion 11b is provided at the upper ends of the lower side members 8c of the lower back frame 8, and these are connected by the first reference pin 10 that runs in the left-right direction. Therefore, the upper back frame 9 and the lower back frame 8 (the back frames) can bend in the front-rear direction with the first reference pin 10 as a fulcrum.

[0038] The middle member 9c of the upper back frame 9 projects backward, and the upper end of the vertically long second tilting frame (center frame) 12 is connected to the left-right intermediate portion of the backward projecting middle member 9c by a left-right long pin (not shown) so as to be able to tilt backward. As shown in Fig. 2 and Fig. 3(A), a forward bearing protrusion 13a is provided at the upper end of the second tilting frame 12, while downward bearing protrusions 13b are provided at the middle member 9c of the upper back frame 9, sandwiching the forward bearing protrusion 13a from the left and right, and both bearing protrusions 13a, 13b are connected by a second reference pin 13c (see Fig. 6).

[0039] 3, the lower end of the second tilting frame 12 is a bifurcated portion 12a having left and right portions, and the bifurcated portion 12a is connected to a bearing bracket 5a provided at the rear end of the base 5 by a second reference shaft 14 that is long on the left and right. Specifically, the bearing bracket 5a has a bearing hole 5b that opens upward, and the second reference shaft 14 is fitted into the bearing hole 5b from above and is prevented from coming off by an upper cover 15 and a side cover 16. Therefore, the first tilting frame 6, the second tilting frame 12, and the back frames 8 and 9 tilt backward as a whole while rotating relatively to each other.

[0040] As shown in Fig. 3(A), a lower center bracket 17 protrudes rearward and downward from the rear end of the base 5, while an upper center bracket 18 protrudes diagonally upward from just above the bifurcated portion 12a of the second tilting frame 12, and these are connected by a back gas cylinder 19. Therefore, by setting the back gas cylinder 19 in a free state or holding it at a desired length, the backrest 3 can be changed to a free reclining state in which it rotates freely, or to an unlocked state in which it is held at a specific angle.

[0041] Although not shown in the figure, a spring is arranged inside the base 5 to provide elastic resistance to the backward tilting of the backrest 3. The seat 2 has a structure in which a seat cushion 2b (see FIG. 2(A)) is stretched over a seat inner shell 2a shown in FIG. 2(A) and covered with upholstery 2c, and the seat inner shell 2a is fixed to the seat outer shell except for its front part.

[0042] The seat outer shell is fixed to an intermediate member 20, a part of which is shown in Fig. 1(A) and Fig. 2(A), and the front part of the intermediate member 20 is connected to the front part of the base 5 by a left-right long support shaft (not shown), and the rear part of the intermediate member 20 is connected to an outward protruding part 6a provided on the first tilting frame 6 by a left-right long shaft (not shown). Therefore, when the backrest 3 tilts backward, the seat 2 tilts backward while descending in conjunction with (synchronizing with) the backrest 3. However, the degree of backward tilt is smaller than that of the backrest 3.

[0043] As shown in Fig. 1(A), the backrest 3 is provided with a back panel 3a made of a flexible resin material such as elastomer, and an upholstery (skin material) 3b stretched over the front surface of the back panel 3a. The back panel 3a is made of a flexible resin material, and as shown in Fig. 1(C) and Fig. 6(B), a number of small holes are provided to allow it to stretch and deform under the pressure of the body. This provides an excellent fit to the body of a person sitting on the chair. When reclining, the upper back frame 9 and the lower back frame 8 rotate relative to each other, but the elastic deformation of the back panel 3a allows the two back frames 8, 9 to rotate relative to each other.

[0044] In this case, as shown in Fig. 6(C), the upper part 3c of the back panel 3a is set to have a weak elastic force that allows the upper part 3c to be stretched by, for example, the user's shoulder blades by increasing the density of the small holes, while the lower part 3e is set to have a smaller density of the small holes, making it difficult to deform. The middle part 3d is made even more difficult to deform than the lower part 3d.

[0045] As shown in Figure 1, an upper rest 21 that supports the head and neck of a seated person is attached to the top end of the backrest 3 in a height-adjustable manner. The upper rest 21 is an optional item, and is attached to the upper member 9b of the upper back frame 9 via a bracket device. When the backrest 3 is reclined, the upper back frame 9 rotates forward relative to the lower back frame 8, but because the head of the seated person is supported by the upper rest 21, the seated person can recline without changing his or her line of sight to the computer monitor on the desk.

[0046] The tilting frame 6 (lower back frame 8) and upper back frame 9 are made of die-cast parts made of light metal such as aluminum or molded parts made of engineering plastic. As can be seen from Fig. 3(B), the side members 8a, 9a of the back frames 8, 9 are formed into grooves that open forward, into which the cover members 22, 23 are fitted and attached. The back panel 3a is fixed to the cover members 22, 23 by insert molding or the like. Furthermore, a resin sheet edge member (not shown) is fixed to the outer periphery of the upholstery 3b by sewing or the like, and the edge member is attached to the back surface of the cover members 22, 23.

[0047] (2) Basic structure of lumbar support device 2, for example, a lumbar support device 25 that supports the back panel 3a from behind is disposed behind the area surrounded by the lower back frame 8. Next, the lumbar support device 25 will be described with reference to Fig. 4 and subsequent drawings.

[0048] For example, as shown in Figures 4 and 5, a lumbar support device 25 comprises, as core members, a vertically long, plate-shaped lumbar pad 26, a vertically long upper link 27 to which the lumbar pad 26 is attached, a lower link 28 to which the lower end of the upper link 27 is connected, and a mounting member 29 to which the lower link 28 is rotatably connected, and further comprises, as auxiliary members, an angle adjustment lever 30 and an auxiliary link 31.

[0049] Lumbar pad 26 is made of a synthetic resin such as polypropylene or polyethylene, and comprises a wide upper support portion 26a intended to support the lumbar spine of the seated person, a narrow lower support portion 26b intended to support the pelvis of the seated person, and a trapezoidal intermediate portion 26c connecting the two, with the three portions having roughly the same vertical width (strictly speaking, upper support portion 26a and intermediate portion 26c have approximately the same vertical width, and the vertical width of lower support portion 26b is slightly larger than those of upper support portion 26a), and the horizontal width of lower support portion 26b is approximately 60 to 70% of the horizontal width of upper support portion 26a.

[0050] As shown in Fig. 4(C) and Fig. 7(B), the intermediate portion 26c is easily bent in the front-rear direction by alternately forming open slits 32 that are open on the left and right sides and closed slits 33 that are closed on the left and right sides. Various methods can be used to allow the intermediate portion 26c to bend and deform, such as thinning the intermediate portion 26c, forming multiple V-grooves on the left and right sides, or drilling multiple small holes. In the figures other than Fig. 4(C) and Fig. 7(B), the slits 32 and 33 are not shown and the outer shape is roughly shown.

[0051] The upper link 27 is made, for example, of synthetic resin, and has a trunk 27a formed with an angular cross-section extending to the upper support portion 26a, and a branch portion 27b branching off diagonally forward from the lower portion of the trunk 27a.The upper end of the trunk 27a is connected to the upper support portion 26a of the lumbar pad 26 so that it can rotate relative to the upper end of the branch portion 27b, and the lower support portion 26b is connected to the upper end of the branch portion 27b so that it can rotate relative to the upper end of the trunk 27a.

[0052] That is, first, an upper bearing bracket 34 consisting of a pair of left and right protruding pieces is provided to protrude backwards from the left and right central part of the upper support part 26a of the lumbar pad 26, and this upper bearing bracket 34 is connected to an upper bearing boss 35 provided at the upper end of the trunk 27a of the upper link 27 by a left and right long upper pin 36 (see Figures 4(A) and (B)). Furthermore, a block-shaped lower bearing bracket 37 is provided to protrude from the left and right central part of the lower support part 26b of the lumbar pad 26, approximately at the middle height between the top and bottom, and is connected to a bifurcated lower bearing part 38 provided at the upper end of the branch part 27b of the upper link 27 by a left and right long lower pin 39 (see Figures 4(A) and (B)).

[0053] A stopper 40 is provided at the upper end of the trunk 27a to regulate the rotation angle of the upper support portion 26a of the lumbar pad 26. Although the branch portion 27b of the upper link 27 is fixed to the trunk 27a with a screw or the like, the entire upper link 27 may be formed as a single unit. The upper link 27 may also be made of metal. In this case, various configurations such as a hollow structure or a channel structure may be adopted.

[0054] The lower link 28 is composed of an upper member 41 and a lower member 42 fixed integrally thereto. The upper member 41 is made of synthetic resin or a metal plate, and has a gutter shape with left and right side plates 41a, a front plate 41b, and a lower plate 41c, into which the lower part of the upper link 27 fits. A downward bearing part 43 consisting of left and right downward pieces is formed at the lower end of the upper link 27.

[0055] On the other hand, as shown in Figure 4(B), for example, a recess 44 is formed in the left-right middle part of the lower member 8c that constitutes the lower back frame 8, into which the lower part of the upper member 41 of the lower link 28 fits, and a bearing boss 46 that is sandwiched from the left and right by the downward bearing part 43 of the upper link 27 protrudes rearward into this recess 44, and the bearing boss 46 of the lower member 8c, the downward bearing part 43 of the upper link 27, and the lower parts of the left and right side plates 41a of the upper member 41 of the lower link 28 are connected by a third reference support axis 48 that is long on the left and right.

[0056] Therefore, the upper link 27 and the lower link 28 move backward together with the lower member 8c during reclining, and can rotate relatively to the lower member 8c (and the back frames 8, 9). The front plate 41b of the upper member 41 in the lower link 28 is formed with an escape hole 49 that allows the bearing boss 46 of the lower member 8c to enter inside, and a window hole 50 located above it.

[0057] 5(B), the downward bearing portions 43 of the upper link 27 are stepped down from the left and right outer surfaces of the upper link 27 to reduce their thickness, while the portions 41d of the inner surfaces of the side plates 41a of the upper member 41 of the lower link 28 where the downward bearing portions 43 overlap are increased in thickness. Therefore, the outer surfaces of the upper link 27 can be brought into intimate contact with the inner surfaces of the upper member 41 of the lower link 28.

[0058] 5(B), the lower member 42 of the lower link 28 has left and right side plates 42a, a front plate 42b, and an upper plate 42c, while the mount member 29 has a bearing boss 51 that protrudes forward and is sandwiched between the left and right side plates 42a of the lower member 42 of the lower link 28, and the left and right side plates 42a of the lower member 42 and the bearing boss 51 are connected by a guide pin 52. In this case, the left and right side plates 42a of the lower member 42 have arc-shaped elongated holes 53 that are recessed forward in a side view, and the guide pin 52 is inserted through the arc-shaped elongated holes 53.

[0059] 2, the second tilting frame 12 has left and right side panels and a back panel and is shaped like a trough that opens forward, and a mount member 29 is fixed with screws to the interior of the frame directly above the upper center bracket 18. The mount member 29 is a synthetic resin product or a die-cast product, but the bearing boss 51 may be formed integrally with the second tilting frame 12 without providing a mount member 29 separate from the second tilting frame 12.

[0060] (3) Lumbar pad front / rear position adjustment mechanism As shown in Figure 4 (B), the angle adjustment lever 30 has a pair of left and right ring portions 30a that sandwich the lower part of the upper member 41 of the lower link 28 from the left and right, and an operating piece that is integrally connected to the rear ends of the left and right ring portions 30a, and the ring portions 30a are connected to the upper member 41 of the lower link 28, the downward bearing portion 43 of the upper link 27, and the bearing boss 46 of the lower member 8c by the already-mentioned third reference support shaft 48.

[0061] The ring portion 30a of the angle adjustment lever 30 is fitted into an outward recess 54 formed on the outer surface of the upper member 41 of the lower link 28, and as shown in Figure 5(A), a number of arc-shaped engagement recesses 55 are formed continuously in the circumferential direction on the upper outer periphery of the ring portion 30a, while a stopper recess 56 narrowed in an arc shape is formed at the upper and front part of the recess 54 of the upper member 41 of the lower link 28, and a stopper pin 57 made of an elastic material such as rubber is fitted into this stopper recess 56. In this case, the stopper pin 57 is set to face one of the arc-shaped engagement recesses 55 formed in the ring portion 30a of the angle adjustment lever 30.

[0062] In other words, the ring portion 30a of the angle adjustment lever 30 is adapted to rotate by elastically deforming the stopper pin 57, and the relative position of the angle adjustment lever 30 and the lower link 28 is maintained by the stopper pin 57 fitting into the stopper recess 56 and one of the arc-shaped engagement recesses 55.

[0063] Furthermore, as shown in FIG. 5, for example, an outwardly protruding connecting pin 58 is provided at the front end of the group of arc-shaped engagement recesses 55 of the ring portion 30a of the angle adjustment lever 30, and this connecting pin 58 and the upper member 41 of the lower link 28 are connected by an auxiliary link 31.

[0064] That is, the auxiliary link 31 is composed of a pair of left and right link rods and a joint pin 31a connecting their upper ends, and the lower ends of the left and right link rods are connected and fitted to connecting pins 58, respectively, and the joint pin 31a is inserted into an elongated hole 59 formed in the upper member 41 of the lower link 28. Note that the joint pin 31a is fixed to one of the link rods in advance, and after the joint pin 31a is inserted into the upper member 41 of the lower link 28, the other link rod is fixed to the joint pin 31a.

[0065] The long hole 59 is inclined so as to move backward as it goes upward. Therefore, when the angle adjustment lever 30 is rotated left from the state shown in Fig. 5(A), the auxiliary link 31 moves down and the lower link 28 is pushed backward by the joint pin 31a. Therefore, the lumbar pad 26 moves backward. In this way, the initial front-rear position of the lumbar pad 26 (the initial posture of the links 27, 28) can be adjusted by rotating the angle adjustment lever 30. As shown in Figs. 4(B) and 5(B), a relief groove 60 is formed in the lower end of the upper link 27 to allow rotation of the joint pin 31a.

[0066] (4) Summary Next, the movement of the chair will be described. First, the basic movement during reclining will be described. As shown in Fig. 6, the first tilting frame 6 and the lower back frame 8 tilt backward around the first reference support shaft 7, the second tilting frame 12 tilts backward around the second reference support shaft 14, the upper back frame 9 and the lower back frame 8 rotate relatively in a side view around the first reference pin 10, and the upper back frame 9 and the second tilting frame 12 rotate relatively around the second reference pin 13c.

[0067] Since the first reference shaft 7 and the second reference shaft 14 are offset from each other in the front-rear direction and the second reference pin 13c is located below and behind the first reference pin 10, the angle θ1 that the upper back frame 9 makes with the line segment connecting the first reference shaft 7 and the first reference pin 10 decreases in proportion to the increase in the reclining angle θ2. Therefore, the backrest 3 as a whole tilts backward, while the upper back frame 9 rises relative to the lower back frame 8.

[0068] In other words, when reclining, the reference axes 7, 14 are misaligned forward and backward, and the first reference pin 10 and the second reference pin 13c are misaligned up and down and forward and backward, so the rearward tilt angle θ3 of the second tilting frame 12 is smaller than the rearward tilt angle θ2 of the first tilting frame 6 and the lower back frame 8. As a result, the upper support part 26a is pushed upward by the second tilting frame 12 and moves backward, causing the upper back frame 9 to rise relative to the lower back frame 8.

[0069] As a result, when reclining, the user's head position is prevented from changing when viewed from the side, and the user can face the computer monitor on the desk. When the upper rest 21 is used as in the embodiment, the head (or neck) can be stably supported, which contributes to reducing the burden on the neck and shoulders.

[0070] That is, the seated person can view the computer monitor at an appropriate angle with his / her head resting against the upper rest 21, which reduces strain on the neck and shoulders and allows the person to work on the computer while maintaining a comfortable state. If the height of the upper rest 21 can be adjusted as in the embodiment, this is particularly preferable because it allows the head to be held in an optimal position.

[0071] Next, the movement of the lumbar support device 25 will be described with reference to Fig. 6. The lumbar support device 25 is attached to the lower member 8c and the second tilting frame 12, and therefore moves backward together with the backrest 3 during reclining.

[0072] In this case, the third reference axis 48 rotates around the first reference axis 7 as a fulcrum, so that the lumbar support device 25 rotates together with the lower member 8c. However, as described above, since the rearward tilt angle θ3 of the second tilting frame 12 is smaller than the rearward tilt angle θ2 of the first tilting frame 6 and the lower back frame 8, the lumbar support device 25 tries to move downward relative to the guide pin 52. However, since the guide pin 52 is fitted into the arc-shaped long hole 53 of the lumbar support device 25, the lumbar support device 25 is allowed to move downward relative to the guide pin 52.

[0073] As shown in Fig. 7(A), the profile of the arc-shaped long hole 53 is inclined so as to deviate rearward from the rotation locus 61 of the third reference shaft 48 and the rotation locus 62 of the guide pin 52 as it goes up, so that the lower member 42 of the lower link 28 is pushed rearward when the lumbar support device 25 descends relative to the guide pin 52. Therefore, the lumbar support device 25 rotates leftward with the third reference shaft 48 as a fulcrum in the left side view of Fig. 7(A), and as a result, the lumbar pad 26 moves forward. Therefore, in this embodiment, the guide pin 52 and the arc-shaped long hole 53 constitute a forward movement guide means for the lumbar pad.

[0074] Because the first reference axis 7, which is the pivot point for the backrest 3, is located below the seat 2 and halfway between the front and rear, the backrest 3 tends to move away from the seat 2 when reclining, and therefore a gap tends to form between the user's lower back and the backrest 3 when reclining. This tendency can be corrected to some extent by moving the seat 2 back when reclining, but since there is a limit to how far the seat 2 can be moved back, the reality is that the occurrence of a gap cannot be completely prevented.

[0075] However, in this embodiment, the lumbar pad 26 moves forward relatively when reclining, and the lower part of the backrest 3 (backboard 3a) is pushed forward by the lumbar pad 26 when reclining, so that the user's lower back can be supported even in the reclined state. As a result, the stability of the body in the reclined state is ensured, and comfort can be improved (problems such as stiffness and tension can be prevented).

[0076] As in the embodiment, when the lumbar pad 26 is configured to have the upper support portion 26a as a lumbar support portion and the lower support portion 26b as a pelvis support portion, there is an advantage that the stability of the body can be significantly improved, particularly when performing work such as operating a computer in an upright position without leaning against the backrest 3. As in the embodiment, when the upper support portion 26a and the lower support portion 26b of the lumbar pad 26 are rotatably connected to the upper link 27, the fit of the upper support portion 26a and the lower support portion 26b to the body of the user can be improved, which is preferable.

[0077] Although the upper support portion 26a and the lower support portion 26b of the lumbar pad 26 can be separated, it is preferable to connect them with the deformable middle portion 26c as in the embodiment, since this reduces the handling and assembly work for storage. In addition, the middle portion 26c also has a body support function, which is advantageous in that it can contribute to improving the stability of the body.

[0078] In this embodiment, the initial front-rear position of the lumbar pad 26 (initial angle of the links 27, 28) can be adjusted by operating the angle adjustment lever 30, so that the support state can be realized according to the user's preference. Also, the degree of pressure by the lumbar pad 26 may change in the shipping state due to an error in the installation of the back panel 3a, but in this embodiment, the error in the installation of the back panel 3a, etc. can also be corrected. The lumbar pad 26 may be in contact with the backrest 3 from the beginning of reclining, or may be set to come into contact with the backrest 3 halfway through reclining.

[0079] In this embodiment, the structure of the lumbar pad 26 and the front-rear position adjustment devices (30, 31) are disclosed, but these are novel and not conventional, and can be considered as an independent invention.

[0080] As in the embodiment, by using the links 27, 28 and the arc-shaped long hole 53 as the attachment means for the lumbar pad 26, the lumbar pad 26 can be moved relatively with a simple structure. The upper link 27 can be bent in an L-shape when viewed from the side, but by forming it in a bifurcated shape as in the embodiment, the rotation range of the upper support part 26a and the lower support part 26b can be increased, improving the fit to the body.

[0081] As mentioned above, the lower part 3d of the back panel 3a is less likely to deform due to the small hole density, but since the lumbar pad 26 is located on the lower part 3d of the back panel 3a, the lower part 3d of the back panel 3a is not excessively deformed by the lumbar pad 26, and the user's lower back and pelvis can be stably supported. Therefore, the pelvis can be firmly supported by the lower support part 26b, especially in an upright position. Therefore, the person's body can be stably supported whether in a reclined or non-reclined state, and disorders such as stiffness and tension can be prevented.

[0082] Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, the backrest is not limited to the elastomer type, and specifications in which a cushion is placed on the front of a resin inner shell, or specifications in which a mesh material is attached to the back frame, etc. can be adopted. When using a back panel made of elastomer (soft resin), its strength (elastic deformation rate) can be made uniform throughout. A form without small holes can also be adopted.

[0083] The mechanism for relatively moving the lumbar pad forward when reclining is not limited to the link mechanism of the embodiment, and may be a cam mechanism or a cylinder mechanism. The present invention may also be applied to chairs with non-flexible backrests. In the case of a non-flexible backrest, when the backrest is attached to a back support, a lumbar support device may be attached to the back support. [Industrial Applicability]

[0084] The present invention can be embodied in a chair equipped with a lumbar support device, and therefore has industrial applicability. [Explanation of symbols]

[0085] 1 leg device 2nd seat 3. Backrest 3a backboard 5. Bass 6. First tilting frame that also serves as the lower back frame 7 1st reference support shaft 8 Lower back frame 8c Lower Member 9 Upper back frame 10 First reference pin 12 Second tilting frame 13c Second reference pin 14 2nd reference support shaft 25 Lumbar support device 26 Lumbar Pad 26a Upper support part 26b Lower support part 26c middle part 27 Top link 28 Bottom link 29 Mounting material 30 Angle adjustment lever 31 Auxiliary Links 41 Upper member of lower link 42 Lower member of the lower link 44 Lower member recess 46 Bearing boss 48 3rd reference support shaft 51 Bearing boss 52 Guide pin 53 Arc-shaped slot 55 Circular engagement recess 56 Stopper recess 57 Stopper pin 59 Slot

Claims

1. The seat includes a backrest that tilts backward against an elastic means, and a lumbar pad that supports the back of a seated person from behind via the backrest, The lumbar pad is configured to move backward together with the backrest in conjunction with the rearward tilting of the backrest and to push the backrest forward. Chair with lumbar support.

2. The lumbar pad includes an upper support portion for supporting the lumbar region of the seated person and a lower support portion for supporting the pelvis of the seated person, the upper support portion and the lower support portion being spaced apart from each other in the vertical direction.

2. A chair with a lumbar support device according to claim 1.

3. The left and right width of the lower support portion is smaller than the left and right width of the upper support portion. A chair with a lumbar support device according to claim 2.

4. The lower support portion and the upper support portion are continuously connected via an intermediate portion that is elastically stretched or bent in the vertical direction. A chair with a lumbar support device according to claim 2 or 3.

5. When the backrest is tilted backward, the relative advancement amount of the upper support portion is larger than the relative advancement amount of the lower support portion. A chair with a lumbar support device according to claim 2 or 3.

6. The lumbar pad is rotatably connected to a link that rotates in conjunction with the rearward tilting of the backrest via a pin on each of the left and right longitudinal ends, The link rotates in the front-rear direction about its lower end as a fulcrum, so that the relative advancement amount of the upper support portion is greater than the relative advancement amount of the lower support portion when the backrest is tilted backward. Further, a posture changing device is provided that can adjust the initial posture of the link by operating a lever. A chair with a lumbar support device according to claim 5.

7. The backrest has a back frame that is open at the front and rear, and an elastomer back panel attached to the back frame, The rigidity of the lower area of ​​the back panel supported by the lumbar pad is higher than the rigidity of the upper area, and the upper area has an elastic strength that allows it to be depressed backward by the pressing force of a seated person.

3. A chair with a lumbar support device according to claim 1 or 2.

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