WO2019051535A1

WO2019051535A1 - Chair having adjustable back support

Info

Publication number: WO2019051535A1
Application number: PCT/AU2018/050925
Authority: WO
Inventors: Mark Cohen; Johin UMSEHER
Original assignee: The Tss Group Of Companies Pty Ltd
Priority date: 2017-09-12
Filing date: 2018-08-29
Publication date: 2019-03-21
Also published as: AU2018333271A1

Abstract

The present invention relates generally to the field of chairs for seating and supporting the back of a user. In particular, but not exclusively, the invention relates to ergonomic chairs used in a workplace such as an office, home office, studio or workshop. One aspect of the invention provides an adjustable back support mechanism for a chair comprising: a rod configured to extend transversely across a chair back, and a user back support that is movable by axial rotation of the rod, wherein, in use, upon axial rotation of the rod the back support moves toward or away from the back of a user seated in the chair.

Description

CHAIR HAVING ADJUSTABLE BACK SUPPORT

FIELD OF THE INVENTION

The present invention relates generally to the field of chairs for seating and supporting the back of a user. In particular, but not exclusively, the invention relates to ergonomic chairs used in a workplace such as an office, home office, studio or workshop.

BACKGROUND TO THE INVENTION

The prior art provides many examples of chairs that are ergonomically designed to fit and support a user's body. Many existing chairs are designed to support a user's spine in an optimum fashion, and may be user-adjustable with regard to the position of armrests, incline of the seat, height of the seat and angle of the back. A properly designed and appropriately adjusted chair supports the body up to and about the pelvis whilst allowing the trunk to move as freely. When a user of the chair remains seated for a prolonged period, the natural position of the spine is preferably maintained. To this end, chairs of prior art provide various adjustable lumbar support means which assist in maintaining the natural curvature of the spine.

Some chairs require a complex and expensive adjusting mechanisms which allow adjustment of lumbar support for a user. Quite apart from the expense, adjusting these chairs can be complicated, with many users failing to properly utilize the adjustment means and are therefore denied the advantages offered. It is generally desired for an ergonomic chair to be easily operable so as to allow for rapid adjustment in accordance with ergonomic principles. Proper adjustment allows a user to work efficiently over the period of a working day, and without any of the attendant back pain which often arises over extended periods of being seated.

One example of a prior art chair having adjustable lumbar support means comprises several flexible bands that are strung across the interior cavity of a chair back. The bands can be tensioned or loosened as required, and according to the level of support provided. While somewhat useful, these chairs cannot be easily adjusted and certainly not while the user is seated. Instead, the user must make an adjustment while unseated and then return to the seated position so as assess the effect of the adjustment. Where the effect is more or less than desired, the user must get up again to make further adjustment. This process may need to be repeated many times before a satisfactory result is obtained. These difficulties are compounded where a set is used by multiple users, and any repeated adjustment to suit a different user is simply impractical.

The prior art further provides various aftermarket products which can be applied to an existing chair so as to assist in lumber support. For example, a foam roller may be placed at the rear of the seat pan. Alternatively, a bolster may be strapped to the mid portion of the seat back. Netted frames which attach to a chair back are also popular amongst office workers. These aftermarket products are of a fixed dimension and therefore not adjustable for a particular user's requirements.

It is an aspect of the present invention to overcome or ameliorate or overcome a problem of the prior art by providing a chair having improved adjustable lumbar means. It is another aspect of the invention provide an alternative to prior art adjustable lumbar means.

The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

SUMMARY OF THE INVENTION

After considering this description it will be apparent to one skilled in the art how the invention is implemented in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention. Furthermore, statements of advantages or other aspects apply to specific exemplary embodiments, and not necessarily to all embodiments covered by the claims.

Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to exclude other additives, components, integers or steps. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may.

Throughout this specification, various advantages of the invention are discussed. It is not represented that all embodiments of the invention will have all advantages, or even a single advantage. Some embodiments of the invention may have no advantage whatsoever and represent only a useful alternative to the prior art.

The present invention is predicated at least in part on Applicants finding that an ergonomic chair having an easily adjustable seat back can be provided by a mechanism having an arrangement of rotatable eccentric components configured to adjust back support panels disposed under the user-facing surface of the chair back. Rotation of the eccentric components by manual action of the user results in back support panels being independently movable forward (toward the users back) or backward (away from the users back). By judicious adjustment by the user, the panels may be adjusted so as to support the user's back in an ergonomically desirable position.

Accordingly, in a first aspect, but not necessarily the broadest aspect, the present invention provides an adjustable back support mechanism for a chair comprising: a rod configured to extend transversely across a chair back, and a user back support that is movable by axial rotation of the rod, wherein, in use, upon axial rotation of the rod the back support moves toward or away from the back of a user seated in the chair. The degree to which a back support panel bears against the user's back, or the degree to which the back support panel displaces the user's back way from the seat back can therefore be adjusted according to ergonomic principles.

The present invention is a significant advance over the prior art seat adjustment mechanisms which are complex, or expensive, difficult to operate, or provide limited adjustable support to the back. 100

The present mechanism is reliant on a rod to transfer a rotational force provided by the user into a lateral movement capable of displacing a back support panel in a direction orthogonal to the rod axis. The lateral movement acts to move the back support panel closer toward a seated user, or further away from the user. The skilled may use any mechanical arrangement to

105 translate rotation into lateral movement. In one embodiment of the first aspect, the rod comprises an eccentric portion, and the eccentric portion is in contact with the back support, or is in sufficient proximity so as to be contactable by the back support upon axial rotation of the rod. Typically, the rod is unitary and the eccentric portion being created by forming two bends at the borders of the eccentric portion, with the eccentric portion remaining linear and parallel

1 1 0 to the remainder of the rod. The axes of the rod, and the eccentric portion may be separated by about 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 or 10.0 cm. As will be readily understood, greater separation allows for greater displacement of a back support panel mounted on by the eccentric portion of the rod.

1 15 In one embodiment of the first aspect, the back support is in engagement with the eccentric portion of the rod.

In one embodiment of the first aspect, the engagement is such that upon axial rotation of the rod the back support maintains an orientation facing toward the back of a user.

120

In one embodiment of the first aspect, the back support comprises a front face and a rear face, the rear face comprising an engagement means configured to engage with the eccentric portion of the rod.

125 In one embodiment of the first aspect, the engagement means is a resilient clip configured to snap-fit onto the eccentric portion of the rod. Other means of engagement are contemplated including one or more U-shaped brackets attached to the rear face, and through which the rod extends. The brackets are sized and shaped so as to allow the eccentric portion of the rod to rotate, but nevertheless not provide excessive free play between the eccentric portion of the rod

130 and the back support. To ensure smooth operation, it may be necessary to dispose a small amount of lubricant at the interface between the rod outer surface and the inner surface of the engagement means. Any sticking will result in juddering, as possible even misalignment of the back support panel during rotation of the rod.

135 In one embodiment of the first aspect, the adjustable back support mechanism comprises a cam fitted to the rod, the cam configured such that upon axial rotation of the rod the cam lobe causes the back support to move toward or away from the back of a user. In this embodiment, the cam takes place of the eccentric region of the rod formed by bending the rod. In this embodiment, the back support may require some intrinsic elasticity, resilience or a dedicated spring such that

140 upon the lobe being rotated away from the back support, the back support returns to a retracted position.

As an alternative to an eccentric portion or a cam, a rack and pinion arrangement may be used to provide the lateral movement required. Such a mechanism is more complex than the 145 eccentric portion described supra, and while less preferred nevertheless has utility in the context of the present invention.

In one embodiment of the first aspect, the adjustable back support mechanism comprises manually operable rotating means configured to axially rotate the rod. The manually operable

150 rotation means may be a handle, a knob, a dial, or a winder. Typically, the rotating means will be fabricated from a material and formed into a shape that allows for easy gripping by the user, and further have surfaces, protuberances, indentations and the like to facilitate pulling, pushing and rotating. In some embodiments of the invention, the user is required to pull the rotation means outwardly to unlock the rotation mechanism, and therefore any shape or material that

155 would allow the rotations means to slip through the hand is to be generally avoided. Given the benefit of the present specification, the skilled person use and other means deemed suitable for the function carried out by the rotation means. For example, in some embodiments the rod itself may form the rotation means with a terminus of the rod being formed into a crank-shape to provide for ease of rotation. A rubber tip may be fitted to the crank-end to allow for any

160 pulling motion required to unlock the rotation mechanism.

In one embodiment of the first aspect, the manually operable rotation means is alternately lockable and unlockable. 165 In one embodiment of the first aspect, the manually operable rotation means is biased toward a locked configuration whereby the rod is not axially rotatable, and is manually operable against the bias so as to assume an unlocked configuration whereby the rod is axially rotatable.

In one embodiment of the first aspect, the back support is elongate and parallel to the axis of 170 the rod. The back support may take the form of a simple panel that is sufficiently thick so as to avoid deformation by a user bearing weight on it, yet not so thick so as to provide excessive bulk or weight to the chair. A strong yet lightweight plastic such as high density polyethylene may be a suitable material for construction.

175 In one embodiment of the first aspect, the back support has an even surface configured to face toward the back of a user.

In one embodiment of the first aspect, the even surface is a planar surface or a curved surface.

180 One function of the surface may be to provide a physical barrier to prevent a portion of a user ' s back sinking into, or sinking too far back into the seat back while reclining. Another function of the surface may be to maintain one portion of the user's spine forward compared to another portion. For example, a surface may extend outwardly so as to sit within the small of a user's back which in turns facilitates correct posture and inhibits slouching in the chair. Another

185 function of the surface may be to ensure the user fits in a more forward position on the chair seat pan, and to therefore encourage the user to place both feet on the floor.

In a second aspect, the present invention provides a substantially rigid portion for a chair back, comprising the adjustable back support mechanism of any embodiment of the first aspect, 190 wherein the substantially rigid portion is configured to support the rod of the adjustable back component in a transverse orientation with reference to a chair back.

In one embodiment of the second aspect, the substantially rigid portion is a frame or a shell. Thus, where a chair back has an internal supporting frame (such as a metal frame) the rod may 195 extend across and be supported by the frame. Many chair backs are devoid of a frame, and instead comprise a relatively strong plastic shell which not only maintains the shape of the seat back but also forms the rear outer surface. The preferred embodiments described infra all have a shell backing on the seat back. In the context of the present invention, the shell is rigid to the extent that it is able to support an adjustment mechanism. In this sense, the term "rigid" should 200 not be taken to mean that the shell cannot be deformed. Many seat back shells may be flexed if compressed from the side regions, or from the top and bottom. However, such flexibility does not prevent the seat back from maintaining the general form of a seat back during use, nor does it prevent the shell from being utilised as an effective support for the adjustment mechanism of the present invention.

205

In one embodiment of the second aspect, the substantially rigid portion comprises a first support configured to support a first rod-end region and a second support configured to support a second rod-end region.

21 0 In one embodiment of the second aspect, the first support and/or the second support is/are an aperture(s) or is/are a recess(es). In some circumstances, the rod may extend through a seat back shell or an internal frame member via an aperture. In some cases the shell or frame member may provide a clip or other engagement means to retain the rod, or may simply a surface provide a surface upon which the rod may securely sit. As will be appreciated, any

215 means of supporting the rod should allow the rod to axially rotate as required to adjust a support panel.

In one embodiment of the second aspect, the substantially rigid portion comprises at least two or at least three of the adjustable back support mechanism of any embodiment of the first

220 aspect. Embodiments having multiple independently adjustable back support mechanisms are preferred for many applications. The human back is supported by the spine, which is comprised of multiple vertebrae allowing for the back to assume any one of many curved profiles while sitting. Some sagittal curvature in the spine is desired, but where the curvature is too little or too great or in the wrong position the use of multiple adjustable panels on a seat back can

225 correct such undesirable spinal configurations.

In a third aspect, the present invention provides a chair back comprising the adjustable back support mechanism of any embodiment of the first aspect, or the substantially rigid portion of any one of any embodiment of the second aspect. In one embodiment of the third aspect, the chair back comprises comfort padding disposed between the back support, and the back of a user when resting against the chair back.

In embodiments of the third aspect that comprise a manually operable rotation means, the 235 manually operable rotation means extends beyond a lateral face of the chair back.

In a fourth aspect, the present invention provides a chair comprising the adjustable back support mechanism of any embodiment of the first aspect, or the substantially rigid portion of a chair back of any embodiment of the second aspect, or the chair back of any embodiment of the third

240 aspect. Typically, the chair will be an office chair and will may have other mechanisms to adjust other parameters. For example, seat height of the present chair may be adjustable to accommodate the variability of user leg lengths. When properly seated, the thigh should be parallel to the floor. Seat pan tilt angle (the relative position of the seat pan compared to level) may be adjusted to provide a positive slope, negative slope, or level. Most users prefer a level

245 seat but others prefer a positive or negative slope for comfort or special needs. The ergonomically designed chair accommodates users with adjustability. The backrest-seat pan angle may be adjustable for individual user preference. The angle between the seat pan and backrest should be adjusted when the user is seated with thighs parallel to the floor and legs properly supported vertically. This angle permits the user to sit slightly forward, straight up,

250 or recline back depending on the type of work performed, support needed, and comfort desired.

Ergonomic armrests are an optional feature of the present chair. Armrests aid in supporting upper extremity weight and thus help maintain comfort, endurance, as well as normal circulation by decreasing static load to muscles contracted to lift and hold limb position during 255 computing. Armrest users report enhanced performance including less fatigue, increased comfort, and better endurance with sustained computing.

It will be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, 260 figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment.

265

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed 270 embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in 275 detail in order not to obscure an understanding of this description.

Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all 280 such changes and modifications as fall within the scope of the invention.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

285 The present invention will now be more fully described by reference to the following non- limiting preferred embodiments.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Turning firstly to FIG. 1, there is shown a partially assembled chair back 10 comprising a main shell panel 15, and three adjustable back support mechanisms 20, 25, 30. Each of the three adjustable back support mechanisms 20, 25, 30 comprises a back support panel 35a, 35b and 35c. Each of the panels 35 a, 35b and 35c is mounted on a rod 40a, 40b and 40c respectively. Extending outside of the main shell panel are manually rotatable dials 45a, 45b and 45c each of which is directly coupled to the rod 40a, 40b, 40c respectively. By way of the coupling, user rotation of a dial 45a, 45b or 45c causes axial rotation of the respective rod 40a, 40b, or 40c. Each rod 40a, 40b, and 40c are independently rotatable.

300

Each of the rods 40a, 40b and 40c comprises an eccentric portion being mainly concealed in this drawing by the support panels 35a, 35b, 35c. However, the left and right shoulders of the eccentric portions can be seen immediately adjacent to the lateral edges of the support panels 35a, 35b and 35c. Drawings more clearly showing the eccentric regions are presented infra in 305 FIGS. 2A and 2B.

It will be apparent that axial rotation of a rod 40a, 40b, or 40c will cause the support panel 35a, 35b or 35c mounted thereon to be moved forward (i.e. out of the plane of the page) or backward (i.e. into the plane of the page).

31 0

The panels 35a, 35b, and 35c and the rods 40a, 40b and 40c are disposed within a cavity of the chair back, the cavity defined at least in part by the main shell portion 15. A layer of padding (not shown) is typically disposed over the panels 35a, 35b and 35c, with a layer of fabric or leather (not shown) disposed over the padding layer. Accordingly, in use, when a user is seated 315 in a chair having the supports mechanisms 20, 25, 30, the user's back contacts the fabric or leather of the seat back and is supported in the lumbar region by the padding and support panels 35a, 35b, 35c.

Referring now to FIGS. 2 A and 2B, there is more clearly shown the configuration of the rod 320 40 of the adjustment mechanism. The rod 40 has a first linear end region 50, and second liner end region 55. Two bends in the bar form an eccentric portion 60. It will be noted that the first end region 50 of the rod is slightly longer that the second end region 55. The further length of the first region is provided so as to allow for engagement with the manually adjustable dial 45 (not shown in the drawing) by way of protrusions 65. The respective lengths of the regions 50, 325 55 are such that the eccentric portion 60 sits centrally to and extending transversely across a chair back. FIGS. 2C, 2D, and 2E more clearly show the back support panels 35. It will be noted that the panel 35 has a planar front face 70, the face 70 intended to apply even pressure to a small region 330 of the user's back. On the rear side of the support panel 35 there extends a clip 75 which is resilient (typically fabricated integrally with panel 35 from a resilient polymer) and dimensions so as to snap onto the eccentric portion 60 of the rod 40. As shown on the ghosted outline 75 of FIG. 2E the clip 75 extends parallel to the longitudinal axis of the panel 35 and for the entire length thereof.

335

Upon axial rotation of the rod 40, the panel 35 is moved forward or backward (i.e. having a vector orthogonal to the longitudinal axis of the eccentric portion 60), depending on the direction of rotation. The engagement of the clip 75 with the rod 40 is such that the eccentric portion 60 is rotatable within the clip 75 such that the orientation of the support panel 3 remains

340 substantially unchanged as the rod 40 is axially rotated. It is generally preferred that the panel face 70 retains a generally vertical orientation so as to bear against a user's back (which is typically generally vertical when seated). Accordingly, as the rod 40 is axially rotated by a user, the support panel 35 remains generally vertically orientated while moving forward or back along a vector orthogonal to the eccentric portion 60. In this way, the user is able to adjust

345 the degree to which the panel 35 extends toward his/her back and can carefully adjust the degree of extension whilst actually sitting and resting against the chair back.

Perspective views of the partially assembled chair back is shown in FIGS. 3 A and 3B, and demonstrating the arrangement of rods 40a, 40b, 40c and panels 35 a, 35b, 35c where the panels

350 are in the same retracted positions. It will be noted that the rods 40a, 40b, 40c have been axially rotated to a position such that the eccentric portions (not marked in this drawing for clarity reasons) are at their lowest possible point. In this circumstance, the support panels 35a, 35b, 35c are disposed slightly forward from the axes of the eccentric regions. It should be noted that the support panels are not shown in FIG. 3 A so as to show more clearly the position of the

355 eccentric portions of the rods.

This perspective view shows how the respective ends of the rods 40a, 40b, and 40c are supported in their positions and transverse orientations across the shell 15. The shell 15 has a series of recesses, three of which are marked 80. Each recess 80 has a paired recess directly 360 opposed (not visible in this drawing). The recesses 80 support the rods 40a, 40b, 40c and allow for axial rotation thereof.

The recess may include an aperture allowing for the terminus of a rod 40a, 40b, 40c to pass through the shell 15 wall. This arrangement occurs at the recesses adjacent to the dials 45a, 365 45b, 45c given the need for the dials 45a, 45b, 45c to directly couple with the rods 40a, 40b, 40c respectively.

Comparative reference is made to FIGS. 4 A and 4B, which are identical to the drawings of FIGS. 3A and 3B respectively, with the exception of the rod 40a having been axially rotated

370 90 degrees clockwise from the position shown in FIGS. 3A and 3B. This axial rotation was effected by the rotation of the dial 45a 90 degrees clockwise from the position of dial 45a shown in FIGS 3A and 3B. This rotation causes the support panel 35a to retract behind the axes of the first and second rod regions, and therefore away from the user. The support panels 35b and 35c remain in position, slightly in front of the axes of the first and second regions of

375 rods 40b and 40c respectively. It should be noted that the support panels are not shown in FIG.

4A so as to show more clearly the position of the eccentric portions of the rods.

In the arrangement shown in FIGS. 3A and 3B, the lower region of the user's back is provided with even support by virtue of the aligned panels 35a, 35b, 35c. In the arrangement shown in 380 FIGS. 3A and 3B, the panel 35a is retracted and therefore does not bear against and support.

The upper part of the user' s lower back. Accordingly, the upper part of the user' s lower back region is permitted to sink a little further into the seat back, while the lower parts of the user's lower back region is maintained slightly forward.

385 In some circumstances, the user may which to extend the panel 35a forwards, and may do so by axial rotation of the rod 40a 90 degrees in a clockwise direction. In that arrangement, the upper part of the user's lower back region is maintained in a slightly forward position relative to the lower parts of the user's lower back region.

390 As will be appreciated, the ability to selectively dispose the support panels 35a, 35b and 35c at varying proximity to selected parts of a user's back permits for customized support of the back according to ergonomic principles. Given the ability of the rods 40a, 40b and 40c to freely axially rotate in adjusting the support 395 panels 35a, 35b, 35c, a locking mechanism is provided for each rod such that once properly set the rod is prevented from further rotation. It is preferable that the locking mechanism is actuatable by the user while the user is in a sitting position such that any adjustment is immediately felt by the user. To this end, the preferred embodiment of the drawings provides for dials 45a, 45b, 45c which are unlocked by the user simply holding the dial and pulling 400 outwardly, and then locked by pushing or allowing the dial to return to the locked position.

Reference is made to FIG. 5 showing an exploded view of a single locking mechanism. The dial 45 has a barrel 100 extending therefrom, and having annually arranged teeth 105 at the free end. An axial bore (not shown) extends through the dial 45 and barrel 100. The dial 45

405 and barrel 100 are mounted on the first linear end region 50 of the rod 45, with the borehole having longitudinal recesses to snugly accept the protrusions 65. The protrusions 65 prevent the dial 45 and barrel 100 rotating relative to the first linear end region 50, such that manual rotation of the dial 45 is directly translated into proportional axial rotation of the first linear end region 50. An axial aperture 110 extends into a recess 115 in the face of the dial 45. A

41 0 compression spring 120 is inserted over the terminus of first linear end region 50 and a pin 125 pushed into the axial aperture 110 so as to (i) secure the compression spring 120 and (ii) secure the dial 45 and barrel 100 to the first linear end region. The torsion spring bias the barrel 100 and teeth 105 toward a complementary formation 130 moulded into a side region of the shell 15. The teeth 105 are accepted into and engage with the complementary formation 130 and

415 prevent rotation of the first linear and region 50 and therefore also the entire rod. Thus, the panel attached to the eccentric portion of the rod is locked in position and is generally immovable against any pressure exerted thereon by a user reclining against the seat back. The compression spring exerts force continuously against the dial 45 and barrel 100 thereby ensuring that the teeth 105 remain firmly engaged with the complementary formation 130.

420

Where adjustment is required, the user manually pulls the dial 45 outwardly (generally to the left, as drawn) and in doing so compresses the compression spring 120 and also disengages the teeth 105 from the complementary formation 130. While the user manually maintains the dial 45 in this pulled-out positions he/she may rotate the dial as need. When the desired adjustment 425 has been made, the user simply released grip on the dial 45 and allows the spring to expand thereby urging the dial 45 and barrel 100 to the right (as drawn), and therefore re-engage the teeth 105 with the complementary formation 130 so as lock the rod against any further rotation.

The disposition of the dials 45a, 45b and 45c in a vertical manner allows a user to 430 subconsciously select the correct dial to adjust the seat for a required part of the back. For example, a user requiring more support in an upper region of the back will naturally reach behind to the upper dial 45a), while for a lower region the user's hand will intuitively move downwardly and adjust dial 45c.

435

Claims

CLAIMS:

1. An adjustable back support mechanism for a chair comprising: a rod configured to extend transversely across a chair back, and

440 a user back support that is movable by axial rotation of the rod, wherein, in use, upon axial rotation of the rod the back support moves toward or away from the back of a user seated in the chair.

2. The adjustable back support mechanism of claim 1 , wherein the rod comprises an 445 eccentric portion, and the eccentric portion is in contact with the back support, or is in

sufficient proximity so as to be contactable by the back support upon axial rotation of the rod.

3. The adjustable back support mechanism of claim 2, wherein the back support is in engagement with the eccentric portion of the rod.

450

4. The adjustable back support mechanism of claim 3, wherein the engagement is such that upon axial rotation of the rod the back support maintains an orientation facing toward the back of a user.

455 5. The adjustable back support mechanism of any one of claims 1 to 4, wherein the back support comprises a front face and a rear face, the rear face comprising an engagement means configured to engage with the eccentric portion of the rod.

6. The adjustable back support mechanism of claim 5, wherein the engagement means is 460 a resilient clip configured to snap-fit onto the eccentric portion of the rod.

7. The adjustable back support mechanism of claim 1 or claim 4, comprising a cam fitted to the rod, the cam configured such that upon axial rotation of the rod the cam lobe

465 causes the back support to move toward or away from the back of a user.

8. The adjustable back support mechanism of any one of claims 1 to 7, comprising manually operable rotating means configured to axially rotate the rod.

470 9. The adjustable back support mechanism of claim 8 wherein the manually operable rotation means is a handle, a knob, a dial, or a winder.

10. The adjustable back support mechanism of claim 8 or claim 9, wherein the manually operable rotation means is alternately lockable and unlockable.

475

11. The adjustable back support mechanism of claim 10, wherein the manually operable rotation means is biased toward a locked configuration whereby the rod is not axially rotatable, and is manually operable against the bias so as to assume an unlocked configuration whereby the rod is axially rotatable.

480

12. The adjustable back support mechanism of any one of claims 1 to 11 , wherein the back support is elongate and parallel to the axis of the rod.

13. The adjustable back support mechanism of any one of claims 1 to 12, wherein the 485 back support has an even surface configured to face toward the back of a user.

14. The adjustable back support mechanism of claim 13, wherein the even surface is a planar surface or a curved surface.

490 15. A substantially rigid portion for a chair back, comprising the adjustable back support mechanism of any one of claims 1 to 14, wherein the substantially rigid portion is configured to support the rod of the adjustable back component in a transverse orientation with reference to a chair back.

495 16. The substantially rigid portion of claim 12, which is a frame or a shell.

17. The substantially rigid portion of claim 15 or claim 16, comprising a first support configured to support a first rod-end region and a second support configured to support a second rod-end region.

500

18. The substantially rigid portion of claim 17, wherein the first support and/or the second support is/are an aperture(s) or is/are a recess(es).

19. The substantially rigid portion of any one of claims 15 to 18, comprising at least two 505 or at least three of the adjustable back support mechanism of any one of claims 1 to 14.

20. A chair back comprising the adjustable back support mechanism of any one of claims 1 to 14, or the substantially rigid portion of any one of claims 15 to 19.

51 0 21. The chair back of claim 20, comprising comfort padding disposed between the back support, and the back of a user when resting against the chair back.

22. The chair back of claim 20 or claim 21 , wherein where a manually operable rotation means is present, the manually operable rotation means extends beyond a lateral face of the 515 chair back.

23. A chair comprising the adjustable back support mechanism of any one of claims 1 to 14, or the substantially rigid portion of a chair back of any one of claims 15 to 19, or the chair back of any one of claims 20 to 22.