Chair

Abstract

To disclose a lumbar support device that is compact and excellent in functionality.SOLUTION: A lumbar support device 18 includes a rotatable drive bracket 20 and a support bracket 21 that overlaps the drive bracket 20 from the front side. The support bracket 21 is connected to a lower member 8b of a lower frame 8 and to a center frame 12, and its posture relative to a backrest 3 is maintained unchanged. At the upper portion of the support bracket 21, a rotor 25 rotated by a handle 24 is disposed, and a support projection 40 provided on the rotor 25 faces an adjustment cam surface 39 of a holder 22. A lumbar pad 19 is vertically long, its lower end is fixed to the support bracket 21 and its upper end is fixed to the drive bracket 20. When the rotor 25 is rotated, a distance between the support projection 40 and the adjustment cam surface 39 changes, and therefore, a retraction allowable amount of the movable part of the lumbar pad 19 changes.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a chair provided with a lumbar support device.

Background Art

[0002] In a reclining chair in which the backrest reclines against elastic means, it is widely practiced to provide a lumbar support device that supports the user's back and waist from behind via the backrest.

[0003] The lumbar support device includes a lumbar pad, and it is also widely practiced to configure the lumbar pad to be movable. Although the lumbar pad often has an adjustable height, Patent Document 1 discloses a lumbar support device in which the front-rear position of the lumbar pad can be adjusted.

[0004] That is, in Patent Document 1, in a chair having a structure in which a mesh material is stretched over a back frame with an opening in the front and rear, a Y-shaped yoke is attached to the left and right side members constituting the back frame and a lower member connected to the lower end thereof, and the lumbar pad is attached to this yoke so that the front-rear position can be adjusted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 1, the lumbar pad is attached to the back frame via a Y-shaped yoke. However, since the yoke has almost the same left-right width as the left-right width of the backrest in terms of its function, the yoke becomes very conspicuous in the rear view of the chair, and some people may feel uncomfortable. In addition, since the back frame needs to have a special structure to attach the yoke, there is also concern that the cost will increase.

[0007] The present invention has been made to improve such a situation.

Means for Solving the Problems

[0008] The present invention includes the inventions of each claim. The invention of claim 1 forms a superordinate concept, and the chair has "a backrest attached to a tilting frame and a lumbar support device that partially supports the flexible backrest member constituting the backrest from behind, The lumbar support device includes a lumbar pad that contacts the backrest member, a drive member that controls the support state of the backrest member by the lumbar pad, and an operating tool for operating the drive member" and is provided with.

[0009] And "the drive member is directly or indirectly connected to the tilting frame, and the drive member allows the lumbar pad to pivot back and forth with its lower end or upper end as a fulcrum, or to move back and forth as a whole" and has such a configuration. In this case, the drive member includes both a mode in which it is connected only to the tilting frame and a mode in which it is also connected to the frame material constituting the backrest.

[0010] The invention of claim 2 is an expanded example of the back 1, "the lumbar pad has a vertically long form with a greater vertical length than the left-right width, and the lower end is at a height position where it can support the pelvis of the seated person, The driving member allows the rubber pad to pivot in the front-rear direction with the lower end as a fulcrum. It has such a configuration.

[0011] The invention of claim 3 is a development example of claim 1 or 2. The driving member has a vertically long form and is connected to a support bracket so as to pivot with the lower part as a fulcrum, and the rubber pad is connected to the driving member. The support bracket is provided with a rotor that rotates around a horizontally long axis, and the driving member forms a control surface facing the outer peripheral surface of the rotor. A plurality of cam surfaces are formed on either the outer peripheral surface of the rotor or the control surface of the driving member, and a support protrusion that selectively abuts on one of the plurality of cam surfaces is formed on the other. It has such a configuration.

[0012] In the present invention, the driving member may be composed of a single member or a plurality of members. In the case of claim 3, there are a method of pushing the driving member backward from the support bracket and a method of pushing the driving member forward from the support bracket. Also, in relation to the backrest member, there are a method in which the rubber pad is always in close contact with the backrest member even in the no-load state and a method in which a gap exists between the rubber pad and the backrest member in the no-load state. These are selected according to the idea of what functions to give to the chair.

[0013] Claim 4 is a development example of claim 3. The rubber pad is in a state where it entirely overlaps the backrest member even in the no-load state, and when it retracts, it shifts to a state where a gap is created between at least a part of the rubber pad and the backrest member in the no-load state. It is provided with a spring that biases the driving member in the direction of forward rotation. It has such a configuration.

[0014] The invention of claim 5 is a development example of claim 3. The lower part of the backrest member is a curved portion that bulges forward such that the portion that contacts the pelvis of the seated person is located at the front end in a vertical front view, and the lumbar pad is arranged to extend upward from the apex of the curved portion in the backrest member. The lumbar pad is connected to the drive member and the support bracket so as to pivot back and forth about its lower end as a fulcrum, and while the backrest member is fixedly supported at the lower part of the lumbar pad, the movable part of the lumbar pad pivots in the front-rear direction. It is configured as described above.

[0015] The invention according to claim 6 is a development example of claim 5. The lumbar pad is provided with weakening means for facilitating bending deformation or buckling deformation in a side view, and the weakening means is a slit formed in multiple stages. It is configured as described above.

[0016] The invention according to claim 7 is a development example of claim 4. The backrest has a back frame with a front-rear opening having left and right longitudinal lower members that constitute its lower end, and a back plate attached to the back frame. On the other hand, The tilting frame includes a center frame arranged at the left and right middle part in a front view. The support bracket is connected to the center frame and the lower member. It is configured as described above.

[0017] The invention according to claim 8 is a development example of claim 7. It is set such that when the backrest reclines, the relative posture in a side view between the support bracket and the backrest changes. The back plate is connected to be vertically movable with respect to the lower member and non-separable in the front-rear direction, and the deformation of the back plate by the back-and-forth movement of the lumbar pad is allowed by the relative movement of the back plate with respect to the lower member. On the other hand, The support bracket of the lumbar support device is set to tilt backward or forward relative to the center frame when the backrest reclines. It is configured as such.

Advantages of the Invention

[0018] In the present invention, since the drive member constituting the lumbar support device is attached to the tilting frame constituting the back, it is superior in stability compared to the case where it is attached only to the components of the backrest as in Patent Document 1. Therefore, it is also superior in the support control function of the backrest member.

[0019] In Patent Document 1, the lower part of the yoke is elastically deformed. However, when connected to the tilting frame as in the present invention, the drive member and the like can be stably supported, so that the support strength can be improved and the dimensional stability can also be improved. Since there is no need to change the structure of the backrest, it is possible to suppress cost increase. Since the wide yoke used in Patent Document 1 becomes unnecessary, it can also contribute to compactification. Furthermore, since there is no need to greatly modify the design of the backrest, the versatility is also high.

[0020] In the configuration of Claim 2, there is an advantage that the prominence of the lumbar pad can be suppressed. In the lumbar support device, a large left - right width is not required for the support mechanism part such as the drive member and it can be slimmed down, so that the whole lumbar support device can be made compact and slim. When the chair is provided with a center frame and a back column, the lumbar support device can be arranged between the center frame and the back column, so that the exposure can be suppressed and the aesthetic feeling can also be improved.

[0021] When a cam mechanism is adopted as the adjusting means as in Claim 3, the backward load acting due to body pressure can be firmly supported. Also, although the rotor can be adjusted by intermittent rotation, since the handle for rotating the rotor can be grasped by a person to apply torque, there is no problem such as over - applying force and over - moving like a lever, and the adjustment of the lumbar pad can be accurately performed.

[0022] As described above, in the relationship between the lumbar pad and the backrest member, there are a mode in which the entire lumbar pad is always in close contact, and a mode in which a gap is formed between at least a part of the lumbar pad and the backrest member in the unloaded state. In the latter mode, while firmly supporting the waist in the neutral state with the body upright, the pushing-up feeling can be eliminated and a comfortable state can be ensured in the reclining state.

[0023] And in the latter mode, if the drive member is retracted to the limit, there may be a state where the cams do not mesh, and then, so to speak, a phenomenon where the backrest member relaxes may occur. In this regard, if a spring is provided as in claim 4, the spring can push the lumbar pad in the forward direction and keep the backrest member in a stretched state.

[0024] In the configuration of claim 5, the pelvis of the seated person can be firmly supported in the neutral state to reduce the burden on the body, and high comfort can be ensured in the reclining state. In the configuration of claim 6, the deformation of the lumbar pad can be promoted to improve the adhesion and fitness to the body of the seated person.

[0025] In the invention of claim 7, since the backrest and the tilting frame can be connected via the lumbar support device, the stability of the backrest can be improved. Further, since the drive member is connected to the lower member constituting the backrest, it is in a state where the lumbar support device is attached to the backrest to some extent, so the relationship between the backrest member and the lumbar pad can be tightened to promote the stabilization of quality.

[0026] In the invention of claim 8, since the back plate can be displaced in the vertical direction, it can be pushed out by the lumbar pad without damaging the back plate. Further, in the invention of claim 8, for example, when reclining, the backrest tilts forward relative to the tilting frame, so that the user can recline with the head raised to easily perform computer operations. However, in claim 8, since the drive member rotates relative to the tilting frame, it is possible to prevent the hitting feeling from changing due to reclining.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying out the Invention

[0028] Next, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the words "front", "rear", "left", and "right" are used to specify directions, but these directions are defined as the directions seen from a person sitting on the chair in a normal manner. The front view is a view seen from the direction facing the seated person.

[0029] (1). Basic structure of the chair First, the outline of the chair will be described mainly with reference to FIGS. 1 and 2. This embodiment is applied to a swivel chair for an office. The chair includes 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 at the center of a base having five leg blades, and casters are provided at the tips of the respective leg blades.

[0030] For example, as shown in FIG. 1(B), a base 5 is fixed to the upper end of the leg support 4, and the lower ends of the left and right first tilting frames 6 are connected to the base 5 by a first reference support shaft 7 (see FIG. 2(C)). As shown in FIG. 1(B), the first tilting frame 6 extends backward while spreading outward to the left and right from the base 5 and then rises upward, and the portion that rises upward and spreads greatly outward to the left and right constitutes the lower side member 8a of the lower back frame 8. That is, the first tilting frame 6 and the lower back frame 8 partially share members, and the upper part of the first tilting frame 6 is the lower side member 8a of the lower back frame 8.

[0031] The lower ends of the lower side members 8a that constitute the lower back frame 8 are connected by a lower member 8b that is long in the left - right direction. That is, the lower back frame 8 is constituted by connecting the rising portions of the left and right first tilting frames 6 with the lower member 8b. As shown in FIG. 2(A), a boss portion 8c is provided on the inner surface of the lower side member 8a, and the left and right side portions of the lower member 8b are fixed to the boss portion 8c with screws.

[0032] On the lower back frame 8, an upper back frame 9 that forms a back frame integrally with the lower back frame 8 is arranged. The upper back frame 9 is formed in a loop shape by left and right upper 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.

[0033] The lower end of the upper side member 9a of the upper spine frame 9 is connected to the upper end of the lower side member 8a by a second reference pin 10 (Figure 2(C)) that is long in the left and right directions. Therefore, the upper spine frame 9 and the lower spine frame 8 (the spine frame) can bend in the front-to-rear direction with the second reference pin 10 as a fulcrum.

[0034] The middle member 9c of the upper back frame 9 protrudes rearward, and the upper end of a vertically long center frame 12 is connected to the left-right middle part of the rearward protruding middle member 9c by a third reference pin 11 that is long in the left-right direction so as to be able to tilt rearward.

[0035] As shown in Fig. 1(C), the lower end of the center frame 12 is a bifurcated portion 12a having left and right portions, and the bifurcated portion 12a is connected to a bearing bracket provided at the rear end of the base 5 by a fourth reference pin (not shown) on the left and right long sides. Therefore, the first tilting frame 6, the center frame 12, and the back frames 8 and 9 rotate relatively to each other and tilt backward as a whole. The tilting of the backrest 3 is controlled by a gas cylinder unit 13 shown in Fig. 2(C).

[0036] Although not shown in the figure, a spring is arranged inside the base 5 to provide elastic resistance to the backward tilting movement of the backrest 3. The seat 2 has a structure in which a seat cushion is stretched over a seat inner shell and covered with upholstery, and the seat inner shell is fixed to a seat outer shell 14 (see Figures 1(B) and 2(C)) except for its front part.

[0037] The rear part of the seat outer shell 14 is connected to the outward protruding part 6a provided on the first tilting frame 6, and the front part of the seat outer shell 17 is connected to the base 5 so as to be slidable back and forth. Therefore, when the backrest 3 tilts backward, the seat 2 tilts backward while descending in sync with the backrest 3. However, the degree of backward tilt is smaller than that of the backrest 3.

[0038] As can be understood from FIGS. 1(A) and 1(B), the backrest 3 includes a back plate 3a made of a flexible resin material such as an elastomer, and a stretched fabric (skin material) 3b stretched on the front surface of the back plate 3a. The back plate 3a is an example of the backrest member described on the back plate 3a. The back plate 3a is made of a flexible resin material and, as shown in FIG. 1(B), allows elongation and deformation due to the pressing force of the body by making a large number of small holes. Therefore, it has excellent fitness for the body of a seated person.

[0039] As shown in FIGS. 1(A) and 1(B), an upper rest 15 for supporting the head and neck of the seated person is attached to the upper end of the backrest 3 so that its height can be adjusted. The upper rest 15 is an optional item. When the backrest 3 reclines, as described above, the upper back frame 9 rotates forward relative to the lower back frame 8. However, since the head of the seated person is supported by the upper rest 15, it is possible to recline without changing the line of sight to the monitor of the personal computer on the plane.

[0040] The tilting frame 6 (lower back frame 8) and the upper back frame 9 are made of die-cast products of light metals such as aluminum or molded products of engineering plastics. The back plate 3a is fixed to the upper back frame 9 and is held in a non-separable state in the front-rear direction and slidable in the vertical direction with respect to the lower back frame 8. Therefore, relative rotation between the upper back frame 9 and the lower back frame 8 during reclining is allowed.

[0041] A lumbar support device 18 is arranged between the center frame 12 and the back plate 3a. Hereinafter, the lumbar support device 18 will be described with reference to the drawings from FIG. 3 and below.

[0042] (2). Basic Structure of Lumbar Support Device For example, as shown in FIG. 6(B), the rubber support device 18 includes, as a main member, a vertically long plate-shaped rubber pad 19, a drive bracket 20 to which the upper end of the rubber pad 19 is connected, a support bracket 21 that overlaps the drive bracket 20 from the front, and a holder 22 that is fitted and disposed inside the support bracket 21 from the front. On the upper part of the support bracket 21, left and right handles 24 and a rotor 25 are attached. The drive bracket 20 and the holder 22 are examples of the drive members described in the claims, and the center frame 12 is an example of a tilting frame.

[0043] The drive bracket 20 has a trough-like shape that is long vertically and open forward, and at the rear, it is provided with a rearward projecting portion 20a that enters the inside of the center frame 12. That is, as shown in FIG. 7(B), the center frame 12 has a trough-like shape with a forward opening groove formed long vertically and is bent in the middle, but the drive bracket 20 is provided with a rearward projecting portion 20a that enters the space of the center frame 12. The drive bracket 20 is in a state where it can rotate back and forth as a whole, and the rearward projecting portion 20a enters the space of the center frame 12.

[0044] As can be understood from FIG. 7, the portion of the drive bracket 20 above the rearward projecting portion 20a is located in front of the center frame 12, and the upper end of the rubber pad 19 is connected to the upper end of the drive bracket 20 with screws 26a via a connector 26. The connector 26 is fitted into a forward opening pocket portion 27 provided in the rubber pad 19 from the front. The contact portion between the pocket portion 27 and the connector 26 is formed in an arc shape in side view. Therefore, the rubber pad 19 can rotate back and forth with the connector 26 as a fulcrum. A pedestal portion 28 into which the screw 26a is screwed is provided at the upper end of the drive bracket 20.

[0045] As shown in Fig. 7, the rubber pad 19 has a vertically elongated shape with rounded upper and lower ends, and horizontally elongated slits 30 extending across the entire left - right length are formed in multiple stages between the upper and lower parts. The upper and lower parts sandwiching the slits 30 are connected by a U - shaped bridge 31 that is U - shaped in side view from the back. Therefore, the rubber pad 19 can be easily bent and deformed, and can also be stretched and deformed in the vertical direction. A vertically elongated slit 30a communicating with the horizontally elongated slit 30 is also provided.

[0046] The support bracket 21 also has a gutter - like basic form that opens forward. At the lower part, a lower bulging part 21a that fits into the rearward - projecting part 20a of the drive bracket 20 is formed, and at the upper part, an upper bulging part 21b that projects rearward is formed. Then, the rotor 25 is arranged in the space formed by the upper bulging part 21b, and is connected to the handles 24 arranged on the left and right outer sides by a common first support shaft 32. The handle 24 is fixed to the first support shaft 32 with screws 32a. Therefore, the handle 24 and the rotor 25 rotate integrally.

[0047] As shown in Fig. 3(B) and Fig. 6(A), a relief hole 35 through which the upper bulging part 21b of the support bracket 21 penetrates is formed in the bottom plate of the drive bracket 20. Therefore, the rotational operation of the handle 24 is performed on the rear side of the drive bracket 20.

[0048] As shown in Fig. 6(A) and Fig. 8, the upper ends of the left and right side plates constituting the support bracket 21 are connected to locking pieces 36 that project rearward from the lower part of the rubber pad 19. That is, a bearing groove 37 that opens upward is formed on the outer surface of the locking piece 36, and the inward - projecting projection 38 at the upper end of the support bracket 21 is fitted into the bearing groove 37 from above. The upper part of the bearing groove 37 is constricted.

[0049] And the inward protrusion 38 is in a plate-like form. As shown clearly in Fig. 8, by directing the opening direction of the bearing groove 37 obliquely rearward, the inward protrusion 38 is set to be inserted into the bearing groove 37 in a posture where the support bracket 21 is rotated forward from the use posture, so that it is held in a non-removable manner in the use posture. Therefore, the rubber pad 19 and the support bracket 21 are relatively rotatable and held in a non-removable manner.

[0050] As shown in Fig. 6(A), the holder 22 has a substantially arcuate form in side view. While entering the inside of the support bracket 21, the upper end and the lower end are fixed to the drive bracket 20 by screws 33. As shown in Fig. 6(B), on the inner bottom surface of the drive bracket 20, a pedestal portion 34 where the support bracket 22 overlaps is formed. The pedestal portion 34 is formed with a space for fitting a nut (not shown). The same applies to the pedestal portion 28 for connecting the rubber pad 19.

[0051] (3). Forward and backward movement mechanism And on the rear surface of the holder 22, a plurality of (4 stages) adjusting cam surfaces 39 are formed in which the distance from the axis of the rotor 25 gradually increases upward. The rotor 25 is provided with support protrusions 40 that contact an arbitrary adjusting cam surface 39. Since the holder 22 is fixed to the drive bracket 20, when the rotor 25 rotates, the distance between the rotor 25 and the holder 22 changes, and the allowable tilting dimension of the drive bracket 20 changes. Since the upper end of the rubber pad 19 is fixed to the drive bracket 20, the allowable tilting dimension of the rubber pad 19 with its lower end as the fulcrum also changes.

[0052] Specifically, as the rotor 25 rotates clockwise as shown by the solid line in Fig. 5(B), the distance between the rotor 25 and the holder 22 widens, and the allowable tilting dimension of the holder 22 and the drive bracket 20 increases. When the rotor 25 rotates counterclockwise as shown by the dotted arrow, the allowable tilting dimension of the holder 22 and the drive bracket 20 decreases.

[0053] The rotor 25 is preferably held in a desired posture. Therefore, in the present embodiment, as shown in FIG. 3(D), on the inner back surface of the support bracket 21, a posture holding cam rib 46 is formed on the opposite side of the adjustment cam surface 39 of the holder 22 across the axis of the rotor 25. As shown in FIG. 3(E), a cylindrical elastic body 47 that contacts the posture holding cam rib 46 is disposed between the rotor 25 and the posture holding cam rib 46.

[0054] Since the elastic body 47 is fitted into the hollow portion provided in the rotor 25, it is held in a non-detachable manner. Further, as shown in FIG. 3(E), the rotor 25 is provided with a rearward opening (for contacting the posture holding cam rib 46) for exposing the elastic body 47 to the rear side. Further, the rotor 25 is provided with left and right arc-shaped ribs 48, and the posture holding cam rib 46 is sandwiched between the left and right arc-shaped ribs 48.

[0055] A recess is formed in the posture holding cam rib 46 corresponding to the plurality of adjustment cam surfaces 39. When the elastic body 47 enters one of the recesses, the relative postures of the rotor 25, the holder 22, and the support bracket 21 are held. Further, since the elastic body 47 is compressed and deformed when the rotor 25 rotates, a click feeling can be given to the seated person when the seated person rotates the handle 24. Therefore, the seated person can accurately control the rotation of the handle 24.

[0056] It is necessary to hold a stopper function so that the rotor 25 does not rotate beyond the limit. The stopper function is borne by the arc-shaped rib 48. That is, the rotation of the rotor 25 is restricted when the arc-shaped rib 48 contacts the upper and lower portions of the inner bottom surface of the support bracket 21 on both sides of the posture holding cam rib 46.

[0057] (4). Relationship with the frame body, etc. As can be understood from, for example, FIG. 6, the drive bracket 20 and the support bracket 21 are provided with forward portions 20c and 21c that overlap each other, and a second support shaft 41 extending in the left - right longitudinal direction is inserted through the forward portion 20c of the drive bracket 20 and the forward portion 21c of the support bracket 21. The second support shaft 41 is inserted through left - and - right joint brackets 42 fixed to the lower member 8b of the lower frame body 8.

[0058] That is, the second support shaft 41 is connected to the joint bracket 42 via left - and - right bushes 43 and a center bearing 44. The center bearing 44 overlaps the upper surface of the lower member 8b in the lower frame body 8, and a lateral pin 44a provided at its lower part penetrates positioning holes 45 provided in the left - and - right joint brackets 42. Therefore, the support bracket 21 and the drive bracket 20 are connected to the lower member 8b of the lower frame body 8 by the second support shaft 41.

[0059] For example, as shown in FIG. 4, the portion of the upper surface of the lower member 8b in the lower frame body 8 where the joint bracket 42 overlaps is bent in a side view. For this reason, the lower piece of the joint bracket 42 is also bent in a side view and is fixed to the lower member 8b by two screws 50. As shown in FIG. 6(B), a tapped hole 51 with a forward opening is provided in the center bearing 44, and a screw (not shown) is screwed into the tapped hole 51 to hold the second support shaft 41 so that it cannot shift left - and - right.

[0060] For example, as shown in FIG. 7(B), a forward bearing boss 52 is integrally formed on the inner surface of the bent portion of the center frame 12, and a connecting shaft 53 is inserted through the bearing boss 52 with both its left - and - right end portions exposed. The bearing boss 52 is sandwiched between the lower parts of the support bracket 21 and the drive bracket 20.

[0061] Then, as shown in FIG. 3(B), a long groove 54 into which the exposed portion of the connecting shaft 53 enters is formed on the inner surface of the lower part of the support bracket 21. The long groove 54 is gently curved so as to be recessed toward the front side. Since the rotation of the support bracket 21 is restricted by the second support shaft 41 and the connecting shaft 53, it is held non-rotatable. On the other hand, the center frame 12 and the backrest 3 rotate relative to each other during reclining, and this relative rotation is allowed by the connecting shaft 53 sliding in the long groove 54.

[0062] For example, as shown in FIGS. 8(A) and (C), the upper end of the rearward projecting portion 21a of the support bracket 21 is the lower step portion 60, and left and right lower spring receivers 61 are projectingly provided on the lower step portion 60. On the other hand, inside the drive bracket 20, an upper step portion 62 facing the lower step portion 60 of the support bracket 21 is formed, and left and right upper spring receivers 63 are formed on the upper step portion 62, and a pair of springs (compression coil springs) 64 are held non-displaceably by the upper and lower spring receivers 61 and 63.

[0063] As can be easily understood from FIG. 4, since the step portions 60 and 62 of the support bracket 21 and the drive bracket 20 are located behind the second support shaft 41, the drive bracket 20 is urged in the forward rotation direction by the spring 64 as shown by the arrows 65 and 66 in FIG. 5.

[0064] (5). Summary As can be understood from FIG. 2(C), the back plate 3a is curved in a state of bulging forward in a side view (longitudinal side view) so that the lower part thereof (the part supporting the pelvis of the seated person) becomes the vertex portion 55 located most forward. Also, the portion of the back plate 3a below the vertex portion 55 rapidly retreats backward, and the portion above the vertex portion 55 is gently curved in a longitudinal side view and is set to follow the human back. That is, a lumbar support portion 56 is formed on the back plate 3a. And the lumbar pad 19 is arranged on the back plate 3a so as to overlap the lumbar support portion 56 from the rear.

[0065] In the invention of the present application, since the support bracket 21 is held immovable relative to the backrest 3, the lower end of the lumbar pad 19 is always held in a fixed position. Therefore, in the neutral state where the seated person stands upright, the pelvis of the seated person is supported by the back plate 18 via the lumbar pad 19. For this reason, it has excellent postural stability. And, in the lumbar pad 19, the portion above the lower part fixed to the support bracket 21 is a movable part that can be tilted backward and deformed.

[0066] And, in the state where the handle 24 is rotated counterclockwise until the end in the state of FIG. 5, the support protrusion 40 of the rotor 25 is in contact with the first-stage adjustment cam surface 39, and since the holder 22 and the drive bracket 20 are in a fully forward-tilted state, the lumbar pad 19 overlaps with the back plate 18 over its entire height.

[0067] Next, when the handle 24 is rotated clockwise, the distance between the support protrusion 40 of the rotor 25 and the adjustment cam surface 39 gradually increases. Therefore, the amount by which the movable part of the lumbar pad 19 can tilt backward (flex and deform) increases. Therefore, when the seated person leans on the backrest 3, the amount by which the upper body sinks backward increases.

[0068] That is, in the present embodiment, instead of forcibly rotating the drive bracket 20 and the lumbar pad 19 by rotating the handle 24, the allowable amount by which the drive bracket 20 and the lumbar pad 19 can rotate (recede) backward is changed. Since the drive bracket 20 is biased in the forward-tilt direction by the spring 64, externally, the back plate 18 is always held in a taut state without loosening. Therefore, when a gap is created between the rotor 25 and the adjustment cam surface 39 by rotating the handle 24, the lumbar pad 19 and the back plate 18 first recede against the spring 64 and then are held in a predetermined support state.

[0069] Ultimately, in this embodiment, instead of the lumbar pad 19 protruding the back plate 18, with the entire movable part of the lumbar pad 19 overlapping the back plate 18 as the reference state, the support state of the seated person is changed by retracting the movable part of the lumbar pad 19 from this reference state, which is a unique function not found in the prior art. Since the lumbar pad 19 is always supported by the spring 64, even if there is a gap between the support protrusion 40 of the rotor 25 and the adjustment cam surface 39, the upper body of the seated person does not jerk backward during reclining, and the seated person can be gently supported.

[0070] In the embodiment, since the movable part of the lumbar pad 19 can be easily bent and deformed, smooth deformation of the back plate 3a can be realized. That is, while firmly supporting the pelvis of the seated person, the movable part of the lumbar support part 56 can be deformed to fit the body of the seated person, realizing high fitness.

[0071] When the seated person performs tasks such as computer work, there can be work in a neutral state with the upper body upright and work in a reclined state. In this embodiment, by turning the hand backward and operating the handle 24, the desired support state can be easily enjoyed.

[0072] As described above, since the support bracket 21 is also connected to the lower member 8b of the lower frame 8, the support bracket 21 can be stably held and the back plate 18 can be firmly held in the desired state. Also, although members such as the drive bracket 20 and the support bracket 21 form one unit, after fixing the unit to the lower member 8b with screws 50, the unit can be connected to the center frame 12 by fitting the support bracket 21 into the connecting shaft 53, thus reducing the labor of the chair assembly work.

[0073] Also, as shown in FIG. 2(C), since the drive bracket 20 forms a substantially S-shaped configuration so as to branch from the center frame 12 and extend upward, an integrated feeling between the drive bracket 20 and the back plate 3a is created, which is excellent in aesthetic sense. Further, the drive bracket 20 is within the left and right width of the center frame 12, and furthermore, members such as the support bracket 21 are within the left and right width of the drive bracket 20. Therefore, the lumbar support device 18 is compact as a whole and looks good.

[0074] As described above, the embodiments of the present invention have been described, but the present invention can be embodied in various other ways. For example, it is also possible to form adjustment cam surfaces on the rotor in multiple stages and provide support protrusions on the holder. The lumbar pad can also adopt a shape with a left and right longitudinal shape or a circular shape. The operating tool may be an up-and-down pivoting lever.

[0075] As a back type, there is one in which a backrest is attached to a back support column arranged at the left and right center portions. In this case, the lumbar support device may be attached to the back support column. Also, there is one in which a backrest is attached to the left and right tilting frames. In this case, it is possible to stretch a stay between the left and right tilting frames and attach the lumbar support device to this stay. The backrest member may be a mesh material. Further, the present invention can also be applied to a backrest in which a cushion is stretched on an inner shell that can be flexibly deformed.

[0076] Also, as a movable mode of the lumbar pad, it is also possible to move the entire lumbar pad back and forth or pivot the movable part back and forth with the upper end as a fulcrum. Further, the drive member may be a bell crank lever method, a parallel link method, or a screw method that rotates around an axial center in the front-rear direction. In the case of the embodiment, it is also possible to integrally provide the holder 22 on the drive bracket 20.

Industrial Applicability

[0077] The present invention can be embodied in a chair. Therefore, it can be used industrially.

Explanation of Reference Numerals

[0078] Pin 1 device 3 backrests 3a back plate (backrest member) 12 center frame 18 lumbar support device 19 lumbar pad 20 drive bracket (drive member) 21 support bracket 22 holder (drive member) 24 handle 25 rotor 39 adjustment cam surface 40 support protrusion 41 second support shaft 42 joint bracket 46 posture holding cam rib 47 elastic body 53 connecting shaft 54 long groove 56 lumbar support part 64 spring

Claims

1. A chair comprising a backrest attached to a tilting frame and a lumbar support device that partially supports the flexible backrest member constituting the backrest from behind. The lumbar support device includes a lumbar pad that contacts the backrest member, a drive member that controls the support state of the backrest member by the lumbar pad, and an operating tool for operating the drive member. The drive member is directly or indirectly connected to the tilting frame, and the drive member allows the lumbar pad to pivot back and forth with its lower end or upper end as a fulcrum, or allows the entire lumbar pad to move back and forth. Chair.

2. The lumbar pad has a vertically elongated shape with a greater vertical length than its lateral width, and the lower end is at a height position capable of supporting the pelvis of the seated person. The drive member allows the lumbar pad to pivot back and forth with its lower end as a fulcrum. The chair according to Claim 1.

3. The drive member has a vertically elongated shape and is connected to a support bracket so as to pivot about its lower part as a fulcrum, and the lumbar pad is connected to the drive member. The support bracket is provided with a rotor that rotates about a horizontally elongated axis, and the drive member forms a control surface facing the outer peripheral surface of the rotor. A plurality of cam surfaces are formed on either the outer peripheral surface of the rotor or the control surface of the drive member, and a support protrusion that selectively contacts one of the plurality of cam surfaces is formed on the other. The chair according to Claim 1 or 2.

4. The lumbar pad is configured to transition from a state where it entirely overlaps the backrest member even in a no-load state to a state where a gap is created between at least a part of the lumbar pad and the backrest member in the no-load state when it retracts. The chair is provided with a spring that biases the drive member in the forward rotation direction. The chair according to Claim 3.

5. The lower part of the backrest member has a forwardly bulging curved portion such that the portion contacting the pelvis of the seated person is located at the front in a longitudinal front view, and the lumbar pad is arranged to extend upward from the apex of the curved portion of the backrest member. The lumbar pad is connected to the drive member and the support bracket so as to pivot back and forth with the lower end thereof as a fulcrum, and with the backrest member fixedly supported at the lower part of the lumbar pad, the movable part of the lumbar pad pivots in the front-back direction. The chair according to claim 3.

6. The lumbar pad is provided with weakening means for facilitating bending deformation or buckling deformation in a side view, and the weakening means is a slit formed in multiple stages. The chair according to claim 5.

7. The backrest has a back frame with a front-back opening having left and right longitudinal lower members constituting the lower end thereof, and a back plate attached to the back frame. The tilting frame includes a center frame disposed at a left-right intermediate portion in a front view. The support bracket is connected to the center frame and the lower member. The chair according to claim 4.

8. It is set such that when the backrest reclines, the relative posture in a side view between the support bracket and the backrest changes. The back plate is connected to the lower member so as to be vertically movable and non-separable in the front-back direction, and the deformation of the back plate due to the back-and-forth movement of the lumbar pad is allowed by the relative movement of the back plate with respect to the lower member. The support bracket of the lumbar support device is set to tilt backward or forward relative to the center frame when the backrest reclines. The chair according to claim 7.

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