Ergonomic support assembly for seating

Abstract

A chair is provided with a seat assembly connected to the base or seat assembly of the chair, the seat assembly providing back support through lower and upper back supports that can effectively move independently, thereby permitting movement of the upper back support in response to movement of the user's thoracic region while maintaining substantially rigid support of the user's pelvo-sacral region via the lower back support. A spine member mounted is mounted to the seat assembly and / or the lower back support by at least one first resilient connection. The spine member is also mounted to the lower back support by at least one second resilient connection above the at least one first resilient connection at a midsection of the spine member. The upper back support mounted above the lower back support.

Description

ERGONOMIC SUPPORT ASSEMBLY FOR SEATINGTechnical Field[oooi] The present disclosure relates to ergonomic seating, and in particular to task and office chairs providing dynamic spinal support.Technical Background

[0002] Ergonomic chairs, such as task and executive office chairs, typically include a singular tall back intended to support the user’s lower spine or entire spine. With the typical prior art ergonomic chair, even when shaped to accommodate the human anatomy, the expectation is that the user will slightly recline when attempting to support their spine with the chair back. Consequently, the user must assume a posture in which their arms are extended forward, requiring the engagement of the muscles in their upper back and shoulders to maintain this position. This results in overuse and fatigue of these muscle groups that then may require symptomatic intervention in the form of armrests to support the fatigued extremities. The use of armrests introduces a new set of problems such as lateral leaning and further sedentariness. Further, when the user is seated in this semi-reclined position, in an attempt to optimize their field of vision for the task at hand, the user tends to position their head anterior of the normal balanced position when standing erect. This results in engagement of the posterior neck and upper back muscles as they attempt to hold the head in an optimal position. An additional consequence is that when the user’s back has the majority of contact and support from the chair back on the mid to upper thoracic region, the user will have a tendency to lever their ischial tuberosities (sit bones) and slide forward on the seat surface. This positioning causes the user’s pelvis to tilt posterior and in turn the lumbar spine assumes a flattened or forward flexed position, placing excess force between the vertebrae with the potential to bulge the gelatinous disc material. This may place debilitating pressure on the nerve roots.

[0003] Commercial attempts to address lumbar spine flattening resulted in the introduction of either a fixed or adjustable lumbar support. These supports tend to address the symptoms of lumbar spine flattening rather than the cause, which is posterior pelvic tilt.Brief Description of the Drawings

[0004] In drawings which illustrate by way of example only embodiments of the present invention,

[0005] FIG. 1 depicts an example office chair in which the support assembly may be employed.

[0006] FIG. 2 illustrates an example seat assembly and example support assembly in a disassembled view.

[0007] FIG. 3 illustrates the support assembly in a partially exploded side view.

[0008] FIGS. 4 and 5 are exploded views of the support assembly, viewed from a front left perspective and back left perspective, respectively.

[0009] FIG. 6 is a cross-sectional view of the view of FIG. 5, taken along a vertical plane bisecting the support assembly.

[0010] FIGS. 7 and 8 are cross-sectional views of the seat assembly with support assembly mounted thereto, again taken along the vertical plane bisecting the support assembly and seat assembly, in which FIG. 7 depicts the seat and support assembly in a first, neutral position, and FIG. 8 depicts the assemblies under a load.[ooii] FIGS. 9 and 10 are enlargements of FIGS. 7 and 8 in the region near the sacral junction of the seat assembly and support assembly.

[0012] FIGS. 11 and 12 are enlargements of FIGS. 7 and 8 corresponding generally to the lumbar region of a user when seated in the chair.

[0013] FIG. 13 illustrates an example spine member, which forms part of the support assembly, in a neutral position.

[0014] FIG. 14 is a cross-sectional view of the illustration of FIG. 13, taken along the plane A-A.

[0015] FIG. 15 illustrates the example spine member under a load, causing torsion in the spine member.

[0016] FIG. 16 is a cross-sectional view of the illustration of FIG. 15, taken along the plane B-B.

[0017] FIGS. 17 and 18 show the example chair of FIG. 1 in perspective and top plan views, respectively, when the chair is (a) in a neutral position; (b) under load, with the upper back support tilted back in response to an extension; (c) and (d) under load, with the upper back support tilted from side to side in response to lateral rotation.Detailed Description

[0018] Some or all of the adverse consequences of prior art ergonomic seating described above may be corrected or mitigated by optimizing support of the user’s pelvis. United States Patent No. 9211013, issued December 15, 2015 and owned by CoreChair Inc., provides one example in which the user’s pelvis is held in a vertical position independent of any support that might be provided for the upper back. Ideally, the user should be able to sit engaged in reference to their work surface with their pelvis optimally supported while the mid to upper back, neck and head are able to effortlessly find a balanced position where agonist and antagonist postural muscle groups harmonize and collectively undergo less imbalanced activity to maintain this posture.

[0019] Still, it is sometimes desirable to provide a taller back support that allows contact to the upper thoracic region. Such support should be independent of the pelvic support, while still accommodating the natural shape of the human anatomy as it transitions from the pelvis into the natural lordotic curve of the lumbar spine and then the kyphotic presentation of the thoracic spine. Prior art tall back ergonomic chairs, which typically provide support for the thoracic region with a substantially one-piece back that supports the pelvis as well, tend to impede the user’s natural spinal movements such as flexion, extension, and lateral rotation.

[0020] Accordingly, the present disclosure provides a support assembly for a user’s back that respects the structural and biomechanical differences between the movement of the pelvis relative to the movement of the spine. As will be appreciated from the example embodiments discussed below, an ergonomic chair back includes a two-part support system in which the user’s pelvis is supported in an upright neutral position and the user’s upperback is able to move independently, permitting the natural movements of extension, flexion and lateral rotation while also providing contiguous support along the user’s ascending spine.

[0021] Examples and embodiments of the support assembly are described with reference to the accompanying figures. Turning first to FIGS. 1 and 2, a chair 10 may include a typical wheeled or stationary chair base 50 and seat assembly 100. The seat assembly 100 may take different configurations, including prior art configurations such as that depicted in the CoreChair patent mentioned above. If the chair 10 is intended to swivel, the seat assembly may be mounted on a spindle 52 that is inserted into a cooperating shaft provided on the chair base 50. A separate, back assembly 200 (referred to as the “support assembly” in this disclosure), providing back support for the user, is mounted to the seat assembly 100. Preferably, the support assembly 200 is adjustably mounted so that the seat depth can be adjusted (e.g., by altering the position of the support assembly 200 with respect to the seat assembly 100). To this end, in the illustrated example embodiment, the support assembly 200 is connected to a support frame 210 terminating in a connecting portion for mounting in or on the seat assembly. As can be better seen in FIGS. 3-5, in this particular illustrated example, the support frame 210 comprises a solid metal or tubular metal frame and a connecting portion comprising a fork 212 that is inserted into the seat assembly 100. The fork 212 is toothed or serrated so that it may cooperate with a corresponding adjustment mechanism (not shown) provided within the seat assembly so that the support assembly 200 may be moved fore and aft with respect to the seat assembly 100 to provide an individualized fit to the user’s pelvic region, enabling the pelvis to be held in an upright position. User adjustment controls 110 for the adjustment mechanism are typically provided underneath the seat assembly 100 within easy reach of the user when seated. Any suitable adjustment mechanism may be employed.

[0022] The support assembly 200, best seen in FIGS. 3 to 12, comprises a spine member 220 which, when in place on a chair 10, extends generally from the user’s sacral region to their thoracic region. The spine member 220 is an elongated member curved generally as illustrated in the accompanying drawings, with a lower portion of the spine member 220 curving convexly (with respect to the seat assembly 100) around the user’s sacral regionthrough an inflection point 222 and extending along the user’s lumbar-thoracic region, then inclining slightly away (with respect to the seat assembly 100) at the upper portion, which corresponds to the user’s thoracic region. An upper back shell 240 is mounted at an upper end of the spine member 220 to provide support to the user’s thoracic region. The vertical position of the upper back shell 240 on the spine member may be adjusted using a height adjustment mechanism 242, such as a cam fastening system permitting either infinite or indexed adjustment; but otherwise, the upper back shell 240 is fixed in position on the spine member 220. A lower back shell 250 is mounted separately to the support assembly 200 in movable relation to the spine member 220, as will be discussed further below. Both the upper and lower back shells 240, 250 may be cushioned or padded; as shown in the drawings, upper and lower support pads 244, 254 are mounted to the corresponding shells 240, 250 and may be contoured to provide further ergonomic support and comfort. The pads 244, 254 may be mounted to the shells using any suitable means, and may or may not be removable. The upper back shell 240 and upper support pad 244 may be considered the upper back support of the chair 10, while the lower back shell 250 and lower support pad 254 provide the lower back support.

[0023] The lower back shell 250, which is contoured to support the user’s sacral and pelvic regions, is mounted between the spine member 220 and support frame 210. The lower back shell 250 includes a lower portion that curves around the user’s pelvo-sacral region and is dimensioned to fit within the corresponding curvature of the spine member. The support provided by this curvature promotes anterior rotation of the pelvis, and allows for the lumbar spine to assume a more natural lordotic curve. The support frame 210 also includes a bent or curved portion that curves around the user’s pelvo-sacral region, and is dimensioned to fit within the corresponding curvature of the lower back shell 250 and the spine member 220. The spine member 220, lower back shell 250, and support frame 210 are connected to each other by a first resilient fastening mechanism that permits some degree of movement between the spine member 220 and the lower back shell 250, while retaining the lower back shell 250 and support frame 210 in relatively fixed relation to each other. The degree of movement will depend on the stiffness or resilience of the mechanism. In the illustrated example, this is accomplished by fasteners (e.g. bolts 262) passing through the spine member 220, lower back shell 250, and support frame 210 near the lower end of thespine member 220 and support frame 210, with resilient bearing discs 264, 266 (formed of a resilient or elastic material) or other resilient or elastic members, such as springs or washers, sandwiching the spine member 220. These resilient members 264, 266 may compress wholly or partially in response to a load, thereby permitting the spine member 220 to move with respect to the lower back shell, which in turn is rigidly connected to the support frame 210. Additionally, the lower back shell 250 may be connected to the support frame 210 at one or more other locations besides the lower end. For instance, as can be seen in FIGS. 11 and 12, a further fastener such as a bolt 268 rigidly connects the lower back shell 250 and support frame 210 through corresponding bores at a point proximate to an upper end of the support frame 210.

[0024] The spine member 220 is also resiliently connected to the lower back shell 250 and / or support frame 210 at a position generally corresponding to the user’s lumbar region in a manner that likewise permits the spine member 220 to move with respect to the lower back shell 250. Again, the degree of movement depends on the stiffness or resilience of the connection. In the illustrated example, this second resilient connection is provided with a control spring 270 mounted on a connecting screw 272. The screw 272 passes through a countersunk bore in the spine member 220 and is held in fixed position with respect to the spine member by washers or caps. As best seen in FIGS. 11 and 12, the screw 272 projects through a corresponding port 258 in the lower back shell 250. In this example, the port 258 is provided in a generally thickened portion of the lower back shell 250 and the screw 270 projects into a recess in this thickened portion, thereby preventing the screw 270 from protruding into any padding or cushioning provided on the lower back shell 250. The thickened portion of the lower back shell 250 may also be engaged by the upper end of the support frame 210; as seen in the drawings, in this example the upper end of the support frame 210 is likewise provided with a port 214 sized to receive a projecting portion of the lower back shell 250. The control spring 270 is mounted onto the projecting portion of the screw 272 within the recess, and held in place with a cap 274. The countersunk bore in the spine member 220 may be covered with a plug 276. Both the spine member 220 and lower back shell 250 may be provided with cooperating shields 226, 256 that extend above, and optionally to the sides and below, the connecting screw to protect the connection area fromdebris, as well as to protect the user from accidental injury as the spine member and lower back shell move with respect to each other.

[0025] When the support assembly 200 is in a neutral position, as shown in FIGS. 7, 9, and 11 , the control spring 270 at the upper connection between the spine member 220 and the lower back shell 250 is in a relaxed or partially relaxed state (i.e., not fully compressed). The resilient bearing discs 264, 266 at the lower connection are likewise in what may be considered a neutral state, subject to some compression. In response to the user’s movement, force exerted on the upper back shell 240 causes the upper portion of the spine member 220 to move in unison with the upper back shell 240, to which it is fixed. As the spine member 220 is rigid, this causes the resilient bearing discs 264, 266 to compress unevenly in response to the movement of the spine member 220 with respect to the lower back shell 250 and support frame 210, compressing the bearing discs 264, 266 in the forward direction while permitting some relaxation or expansion of the discs in the rear. At the same time, movement of the spine member 220 away from the lower back shell 250 and support frame 210 increases the spacing between the spine member 220 and the lower back shell 250, thereby retracting the connecting screw 272 towards the rear and causing compression of the control spring 270, providing some resistance to the movement of the spine member 220. This provides smooth action while the user leans back against the upper back shell 240 and pad 244. Because the support frame 210 and lower back shell 250 are substantially rigid, the user’s pelvo-sacral region is provided with firm support even when the spine member 220 is moved backwards, or the support assembly 200 as a whole is moved fore or aft with respect to the seat assembly 100. The control spring 270 and connecting screw 272 may be replaced with another suitable resilient or elastic connector that provides resistance to the user’s movement while also permitting relative motion of the upper back shell 240 and spine member 220 with respect to the lower back shell 250 and support frame 210. The degree of resistance provided may be tuned by selecting the characteristics of the spring 270 or other resilient member.

[0026] Further, the spine member 220 may be manufactured of a material that permits some lateral torsion of the spine member around the midsection, proximate to the second resilient connection, in response to lateral rotation of the user’s thoracic region while seated. Theupper portion spine member 220 corresponding to the thoracic region may also be capable of inclining back in response to applied force when the user leans against the upper back support. In the example embodiment, the spine member 220 is manufactured of Ultramid® B3UG4 polyamide, available from BASF SE (see UREplastics- rubber.basf.com / global / en / performance_polymers / products / ultramid / 30045737.html). To facilitate torsion, the spine member 220 comprises a curved C-channel with a proportionally thicker base wall 230 and thinner sidewalls 232, with longitudinal ribs 234 projecting along its interior as can be seen in FIGS. 13 to 16. The longitudinal ribs 234 generally decrease in density and / or number from the thoracic region to the lumbar / sacral region, with the arrangement of ribs 234 varying around the point of attachment between the spine member 220 and the lower back shell 250. The region of the spine member 220 below the attachment point (indicated as region 5 in FIG. 13), is not subject to the same loads as the thoracic region (region T) of the spine member 220, which is affected by torsion and other movement in the user’s thoracic region when the user leans against the upper back support and moves from side to side, thereby applying force to the spine member 220 via the upper back support. FIGS. 13 and 14 illustrate the spine member 220 in a neutral position, while FIGS. 15 and 16 illustrate the spine member 220 when it is subject to torsion, such as in the case where the seated user twists their upper back (the thoracic region) to the right side.

[0027] The effect of the combination of the resilient connections between the spine member 220 - upper back shell 240 and the support frame 210 - lower back shell 250 and the composition and structure of the spine member 220 can be appreciated in FIGS. 17 and 18, which illustrate how the assembled support assembly may respond to the user’s movement leaning back as in (b), or twisting from left side to right side as in (c) and (d), compared to the neutral position in (a). With this combination of resilient connections and spine member 220, the user is provided with substantially continuous surface contact along the lumbar and thoracic curvatures of the user’s spine. The relative independence of the lower and upper back shells 240, 250 provides both a firm, stationary support of the pelvic region and a dynamic response to natural flexion and torsion in the upper back.

[0028] There is thus provided a motion support mechanism, for example for an office chair back, which when secured to a chair seat provides support of the seated user’s back andallows secure support for the user’s pelvis while allowing the user’s upper back to extend and rotate while supported. The motion support mechanism allows for a two-part back support where both parts are secured to the seat by way of a heavy bar, for example made of metal, that allows fore and aft adjustment to vary fit for different body types and sizes. Two support pads for the upper and lower back are connected by way of a flexible spine that connects to the heavy bar at the bottom of the bar, at the top of the lower support pad and top of the bar and then continues upward to secure the upper support pad where it includes a mechanism that allows vertical adjustment of the upper support pad. The combined effect allows for secure stable positioning of the user’s pelvis while allowing the user’s mid to upper back to be supported by the upper support pad, where this upper support pad is allowed to extend and twist allowing natural movements of the human seated body.

[0029] When this support assembly is attached to a CoreChair™ ergonomic chair, it will complement the active seating feature of the seat pan and mechanism of the CoreChair chair, allowing movement in all directions while maintaining optimal seating posture. In some embodiments, the support assembly may be retrofitted to other commercial seating using any suitable attachment mechanism.

[0030] It should be understood that this description is not intended to be limiting, and that the examples contemplated herein include all alternatives, modifications, and equivalents as would be appreciated by the person skilled in the art, and are included within the scope of the accompanying claims. For example, although the various examples and embodiments described herein were described in relation to a task or office chair, they may be applied to seating for other purposes. Further, while the examples and embodiments described herein depict a two-piece back support for the user, with a discrete upper and lower back shell 240, 250 and associated support pads 244, 254, those skilled in the art will appreciate that a single shell may be provided instead. In one such implementation, only a lower back shell 250 is provided, with the same resilient connection between the spine member 220 (which need not extend through the thoracic region) and the support frame 210 and lower back shell 250. In another implementation, the upper and lower back shell 240, 250 are connected. For instance, the upper and lower back shell 240, 250 may be connected with a further resilient connection that permits the upper back shell 240 to twist with respect to thelower back shell 250 as illustrated in FIGS. 17 and 18, while providing a substantially continuous support for the user’s back. Alternatively, the upper and lower back shells 240, 250 may be integrated into a unitary shell, with the junction between the upper and lower portions of the shell being formed of a suitably flexible material to permit lateral torsion between the upper and lower portions so that the upper portion of the shell can move with the natural movement of the user’s back, while the lower portion of the shell remains relatively static to continue supporting the user’s pelvis.

[0031] Although the features and elements of the various examples or embodiments may be described as being in particular combinations, the person of ordinary skill in the art will appreciate which features or elements can be used alone, without the other features and elements of the embodiments, or in various combinations with or without other features and elements disclosed herein. Further, individual features or variations described in respect of one example or embodiment in this disclosure can be used with other examples or embodiments mentioned herein, as would be understood by the person skilled in the art.

[0032] The examples and embodiments are presented only by way of example and are not meant to limit the scope of the subject matter described herein. Each example embodiment presented above may be combined, in whole or in part, with the other examples. Further, variations of these examples will be apparent to those in the art and are considered to be within the scope of the subject matter described herein. Some steps or acts in a process or method may be reordered or omitted, and features and aspects described in respect of one embodiment may be incorporated into other described embodiments.

Claims

CLAIMS1. A chair, comprising: a base; a seat assembly; a support assembly providing back support mounted in fixed relation to the seat assembly, the support assembly comprising a lower back support and an upper back support; a spine member mounted to the seat assembly and / or the lower back support by at least one first resilient connection at or proximate to a first end of the spine member and to the lower back support by at least one second resilient connection above the at least one first resilient connection at a midsection of the spine member, the upper back support mounted at or proximate to a second end of the spine, a position of the spine and upper back support being movable with respect to the lower back support and seat assembly in dependence on a stiffness of the at least one first resilient connection and / or at least one second resilient connection.

2. The chair of claim 1 , wherein the spine member comprises an elongated member having a convex curvature in a lower portion of the spine member.

3. The chair of claim 2, wherein the spine member comprises a C-channel having a base wall and sidewalls, and a plurality of longitudinal ribs extending along the interior of the C- channel.

4. The chair of claim 1 , wherein the support assembly further comprises a support frame connected to the lower back support.

5. The chair of claim 4, wherein the spine member is mounted to the support frame and the lower back support by the at least one first resilient connection, the spine member being movable with respect to the support frame as well as the lower back support and the seat assembly.

6. The chair of claim 5, wherein the spine member is mounted to the lower back support by the at least one second resilient connection.

7. The chair of claim 6, wherein the support frame is rigidly attached to the lower back support.

8. The chair of claim 1 , wherein an upper portion of the spine member undergoes movement in response to a force applied above the at least one second resilient connection.

9. The chair of claim 8, wherein the movement comprises a lateral torsion.

10. The chair of either claim 8 or 9, wherein the applied force results from a user leaning against the upper back support.

11. The chair of either claim 8 or 9, wherein a lower portion of the spine member below the at least one first resilient connection remains static with respect to the upper portion of the spine member when the upper portion of the spine member undergoes movement in response to the applied force.

12. The chair of either claim 8 or 9, wherein the upper portion of the spine member back support moves substantially independently of the lower back support.

13. The chair of claim 1 , wherein the lower back support comprises a lower back shell mounted in fixed relation to the seat assembly and a cushion mounted to the lower back shell.

14. The chair of claim 13, wherein the upper back support comprises an upper back shell mounted at or proximate to the second end of the spine member, and a cushion mounted to the upper back shell.

15. The chair of claim 14, wherein the upper back shell and the lower back shell are comprised in a unitary shell.

16. The chair of claim 1, further comprising a headrest mounted to the spine member, the headrest positioned above the upper back support.

17. The chair of claim 1 , wherein the upper back support comprises a headrest.

18. The chair of claim 1 , wherein the at least one first resilient connection comprises at least one resilient bearing between the spine member and the seat assembly and / or the spine and the lower back support.

19. The chair of claim 1 , wherein the at least one second resilient connection comprises a spring-mounted connection.

20. The chair of claim 1 , wherein the support assembly is movable with respect to the seat assembly.

Images