GB2526785A

GB2526785A - Adjustable backrest for a chair

Info

Publication number: GB2526785A
Application number: GB1409329.8A
Authority: GB
Inventors: Tom Suddaby
Original assignee: Specmat Ltd
Current assignee: Specmat Ltd
Priority date: 2014-05-23
Filing date: 2014-05-23
Publication date: 2015-12-09
Also published as: GB201409329D0; WO2015177498A1

Abstract

An adjustable backrest for a chair comprising a second part 32 mounted on a first part 30 wherein the second part 32 comprises a plurality of members 34 joined in series using selectively lockable hinges 40 to form an arcuate profile to support a users spine. The device may be used on a wheelchair and customised to support a users thoracic region. The lockable hinges 40 may be secured by clamping opposed surfaces together using a nut and bolt and may have interlocking profiles with ridges which fit together at discrete angular offsets. There may be a plurality of supports each with adjustable linked members 34 wherein the supports are joined by rigid linkages 62 which include lockable hinges of the same construction. The second part 32 may be arranged so that it extends different distances either side of the first part 30.

Description

TITLE: ADJUSTABLE BACKREST FOR A CHAIR

DESCRIPTION

The present invention relates to an adjustable backrest for a chair, in particular but not exclusively an adjustable backrest for a wheelchair.

There is considerable variation in the size and shape of people's spines and thus it is not surprising that backrests for chairs need to be adjustable in order to offer a good level of support and comfort for a range of different users. Backrest adjustability is of paramount importance to anyone confined to a wheelchair, and particularly anyone with a spinal abnormality or ixuiy, if good posture is to be achieved or encouraged. However, adjusting backrests to individual requirements can be a time consuming task, even for trained specialists. Accordingly, the present invention has been devised with a view to providing a backrest which can be adjusted quickly and easily to individual requirements.

* 25 In accordance with a first aspect of the present invention, there is provided an adjustable ** backrest for a chair (e.g. wheelchair), comprising: a support unit comprising a first part and * a second part mounted on the first part, the second part comprising a plurality of members joined together in series to define a spinal support with a substantially arcuate profile, the * 4.' spinal support being configured to provide lateral support to a user's spine when resting thereagainst, wherein adjacent members are joined together with a lockable hinge arrangement for preventing pivotal movement of one member relative to the other when locked and allowing pivotal movement of one member relative to the other when unlocked to enable the substantially arcuate profile of the spinal support to-be adjusted.

In this way, an adjustable backrest is provided in which the substantially arcuate profile of the spinal support can be adjusted in order to fit snugly against part of a user's body simply by unlocking the lockable hinge arrangement(s) between adjaceit pairs of members and then locking the hinge arrangement(s) once the members have been rotated into a position offering lateral support to the user's spine-The spinal suppbrt may be configured to provide lateral support to a thoracic region of a user's spine shen resting thereagainst. Alternatively, the spinal support may be configured-to provide latb"al support to a cervical region (neck region) or a lumbar region (lower back region) of auser's spine when resting thereagainst.

The second past may be mounted on the first part such that the member are able to extend substantially equally on either lateral side of the first part. Such an/arrangement (hereinafter referred to as "symmetrical mounting") may be appropriate for a ujser who does not have a pronounced sideways curvature of the spine. Alternatively, the second part may be mounted on the first part such that the members are able to extend further ion one lateral side of the first part than on the other, Such an arrangement (hereinafter referred to as * : * "asymmetrical mounting") may be appropriate for a user who has a pronounced sideways curvature of the spine, e.g. due to scoliosis. The second part may be releasatly mounted on the first part such that it is possible to switch between symmetrical mounting and asymmetrical mounting of the second part on the first part. * *0 *

The second part may comprise at least three members, perhaps even at least five members, such as for example seven members, Each member may comprise at least one elongate element. The or each elongate element in one member may be offset relative to the or each elongate element in an adjacent member such that the elongate etelments of adjacent members may be interleaved at the respective lockable hinge arrangement.

The or each lockable hinge arrangement may comprise a clamping mechanism which urges at least one pair of opposing surfaces of adjacent members together when 1ccking the lockable hinge arrangement. For example, the clamping mechanism my comprse a bolt, extending through registered apertures in the opposing surfaces of the adjacent members, the bolt having a screw thread which engages a nut configured to urge the surfaces tgether on rotation of the bolt relative to the nut. The pair of opposing surfaces may ha&e profiles which are configured to interfit and prevent rotation of one surface relative to the other when the opposing surfaces abut. The intertitting profiles may be configured to fit together at discrete angular offsets. Such profiles would allow the adjacent members to be locked iS together at pre-set angular displacements.

The backrest may comprise an additional support unit defining an additional spinal support. The additional support unit may have some or all of the features define above for the aforementioned support unit. The additional support unit may be mounted on the first part of the support unit via a rigid linkage, The secondary support unit may be coupled to : *". 20 one end of the rigid linkage by a lockable hinge arrangement for prevening pivotal S.. * movement of the additional support unit relative to the rigid linkage when locked and allowing pivotal movement of the additional support unit relative to the rigid liLkage when unlocked. The first part of the support unit may be coupled to the other end of the rigid : . linkage by a lockable hinge arrangement for preventing pivotal movement of thç first part of

S

S (p

the support unit relative to the rigid linkage when locked and allowing pivotal movement of the first part of the support unit relative to the rigid linkage when unlocked.

The lockable hinge arrangements at either end of the rigid linkage may be configured to allow the support unit and additional support unit to be positioned relative to each other to fit the contours of a. user's spine such that the spinal support and additional spinal support are both able to support simultaneously a corresponding part of a user's spine. The or each lockable hinge arrangement may comprise a clamping mechanism which urges opposing surfaces of the rigid linkage and respecive support unit together when locking the lockable hinge arrangement. For example, the clamping mechanism my comprise a bolt, extending through registered apertures in the opposing surfaces of the rigid linkage and respective support unit, the bolt having a screw thread which engages a nut configured to urge the surfaces together on rotation of the bolt relative to the nut. The opposing surfaces may have profiles which are configured to intei-fit and prevent rotation of one surface relative to the other when the opposing surfaces abut. The interfitting profiles may be configured to fit together at discrete angular offsets. Such profiles would allow the rigid linkage and respective support unit to be locked together at pre-set angular displacements.

At least one additional linkage may be provided between the additional support unit and the first part of the support unit to prevent pivotal movement of the additional support unit relative to the first part of the support unit when the lockable hinge arrangements at each end of the rigid linkage are unlocked. The at least one additional linkage may be rigid and be pivotally coupled to the additional support unit and the first part of the support unit.

In this way, the pivot points between the rigid linkage, the at least one additional linkage, the first part of the support unit and the additional support unit may define a parallelogram which shears as the additional support unit moves relative to the first part of the support unit 1⁄2 when the Lockable hinge arrangements at each end of the rigid linkage are unlocked.

In accordance with another aspect of the present invention, there is provided a chair comprising a body with a seat portion and a back portion, the back portion comprising a backrest in accordance with the first aspect of the inventioti The back portion may include a frame which is attached to the first part of the support unit of the backrest. The chair may be a wheelchair.

BRIEF DESCRIPTION OF DRAWINGS

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure I is a perspective view of an adjustable backrest embodying the present nvention; Figure 2 is a side view of the adjustable backrest of Figure 1; Figure 3 is a plan view of the adjustable backrest of Figure 1; Figure 4 is an exploded view showing detaiL of one support unit of the adjustat$e backrest ofFigure 1; Figure 5 is a side view of an upper section of the adjustable backrest of Figure 1; and Figure 6 is an exploded view of the adjustable backrest of Figure 1.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENT

: ** 20 Figures 1-6 show an adjustable backrest 10 (and detailed views of parts thereof) for use

I

* r with a wheelchair (not shown).

Adjustable backrest 10 comprises upper, middle and lower support units 12, 14, 16 * mounted between upper and lower frame sections iS, 20 of a chair (not shown). Each support unit 12, 14, 16 comprises a first part 30 and a second part 32 which is releasably mounted on the * etc * S. first part 30, e.g. with bolts 33. The second part 32 comprises a plurality of members 34, joined together in series to define a spinal support surface 36 with a substantially arcuate profile. The spinal support surface 36 extends to each lateral side of the first part 30, and is configured to provide lateral support to a user's spine when resting against the backrest 10. Adjacent pairs of members 34 are each joined together with a lockable hinge arrangement 40 for preventing pivotal movement of one member 34 relative tc the other member 34 about respective pivot axis 42 when locked, whilst allowing pivotal movement of one member relative to the other about respective pivot axis 42 when unlocked. Pivotal movement of the members 34 about their respective pivot axes 42 when their respective hinge arrangements 40 are unlocked allows the substantially arcuate profile of the spinal support surface 36 to be adjusted to fit snugly against a user's spine.

Each member 34 comprises either two or three elongate elements 50 which are spaced apart such that the elongate elements 5') of adjacent members are interleaved at the respective lockable hinge arrangement 40. Each lockable hinge arrangement 40 comprises a threaded bolt 52 and a corresponding nut 54. The threaded bolt 52 extends through registered apertures 54 in opposing surfaces 56, 57 of elongate members 50 of adjacent pairs of members 34. When screwed into its nut 54, the bolt 52 urges the opposing surfices 56. 57 together when locking the lockable hinge arrangement 40. The opposing surfaces 56, 57 have profiles (e.g. a series of radial ridges and grooves) which are configured to interfit and prevent rotation of one surface relative to the other whilst the opposing surfaces 56, 57 abut against each other.

The upper and middle support units 12, 14 are coupled together via a pair of rigid linkages 60, 62. (The middle and lower support units 14, 16 are also coupled together via a pair of rigid linkages 60, 62 in the same way as the upper and middle support units 12, 14, but only the latter will be described in detail). One end of each rigid linkage 60, 62 is pivotally coupled a with a releasable locking arrangement 64 to the first part 30 of the upper support unit 12, and the other end of each rigid linkage 60, 62 is pivotally coupled with a releasable locking arrangement 64 to the first part 30 of the middle support unit 14, thereby defining four paralleL pivot axes 66.

67, 68, 69. The four parallel pivot axes 66, 67, 68, 69 form the corners of a parallelogram pattern which shears as the middle support unit 14 moves relative to the upper support unit 12 as depicted by arrow "A" when the releasable locking arrangements 64 are unlocked. In this way, the position of the middle support unit 14 may be advanced or retracted relative to the upper support unit 12 to correspond to the contcurs of a user's spine. Once the relative positions of the upper and middle support units 12, 14 have been set, they may be secured by locking the releasable locking arrangements 64. The releasable locking arrangements 64 work in the same way as the lockable hinge arrangements 40, and thus each includes a threaded bolt and nut (not shown) which, on tightening, applies a clamping action to opposing surfaces of the linkages 60, 62 and the first parts 30 of the upper and middle support units 12, 14 to prevent relative movement.

* .. 0 * * . *.. . * 0***** * . * * -*** * * ** * * * *** **. *

Claims

ISClaims: 1. An adjustable backrest for a chair (e.g. wheelchair), comprising: a support unit comprising a first part and a second part mounted on the first part, the second part comprising a plurality of members joined together in series to define a spinal support with a substantially arcuate profile, the spinal support being configured to provide lateral Support to a user's spine when resting thereagainst, wherein adjacent members are joined together with a lockable hinge arrangement for preventing pivotal movement of one member reltive to the other when locked and allowing pivotal movement of one member relative to the Mher when unlocked to enable the substantially arcuate profile of the spinal support to be adjusted.
2. An adjustable back rest according to claim 1, in which the spinal support is configured to provide lateral support to a thoracic region of a user's spine shen resting thereagainst. /
3. An adjustable back rest according to claim 1 or claim 2. in which the seond part is mounted on the first part such that the members are able to extend substantial1r equally on either lateral side of the first part.
4. An adjustable back rest according to claim I or claim 2, in which the second part is mounted on the first part such that the members are able to extend flirther on one lateral side of the first part than on the other.
5. An adjustable back rest according to any preceding claim, in which the econd part is * releasably mounted on the first part such that it is possible to switch between a first configuration where the members are able to extend substantially equally 09 either lateral * side of the first part when the second part is mounted on the first part, !and a second configuration where that the members are able to extend thither on one lateraJ side of the ** * .** I * * **S 4'first part than on the other when the second part is mounted on the first part.An adjustable back rest according to any preceding claim, in which the or each lockable hinge arrangement comprises a clamping mechanism which urges at least one pair of opposing surfaces of adjacent members together when locking the lockable hinge arrangement.7. An adjustable back rest according to claim 6, in which the pair of opposing surfaces have profiles which are configured to interfit and prevent rotation of one surface rlative to the other when the opposing surfaces abut.8. An adjustable back rest according to claim 7, in which the interfitting prfiles are configured to fit together at discrete angular offsets.9. An adjustable back rest according to any preceding claim, further comprising an additional support unit defining an additional spinal support.10. An adjustable back rest according to claim 9, in which the additional support unit comprises a first part and a second part mounted on the first part, the secnd part comprising a plurality of members joined together in series to define the additioia1 spinal support with a substantially arcuate profile, the spinal support being configured to provide lateral support to a user's spine when resting thereagainst, wherein adjacent merfibers are joined together with a lockable hinge arrangement for preventing pivotal movement of one member relative to the other when locked and allowing pivotal movement of on member relative to the other when unlocked to enable the substantially arcuate profile of the additional spinal support to be adjusted.11. An adjustable back rest according to claim 9 or claim 10. in which the dditional U..support unit is mounted on the first part of the support unit via a rigid linkage.12. An adjustable back rest according to claim 11, in which the secondary support unit is * ... I * tScoupled to one end of the rigid linkage by a lockable hinge arrangement for preventing pivotal movement of the additional support unit relative to the rigid linkage when locked and allowing pivotal movement of the additional support unit relative to the rigid linkage when unlocked.13. An adjustable back rest according to claim 12, in which the first part of the support unit is coupled to the other end of the rigid linkage by a lockable hinge arrangement for preventing pivotal movement of the first part of the support unit relative to the rigid linkage when locked and allowing pivotal movement of the first part of the support unit relative to the rigid linkage when unlocked.14. An adjustable back rest according to claim 13, in which the lockable hinge arrangements at either end of the rigid linkage are configured to allow the support unit and additional support unit to be positioned relative to each other such that the spinal support and additional spinal support are able to support simultaneously a corresponding part of a user's spine.15. An adjustable back rest according to claim 13, in which each lockable hinge arrangement comprises a clamping mechanism which urges opposing surfaces of the rigid linkage and respective support unit together when locking the lockable hinge arrangement.16. An adjustable back rest according to claim 1 5, in which the opposing surihees have profiles which are configured to interfi: and prevent rotation of one surface relative to the other when the opposing surfaces abut.* r * a 17. An adjustable back rest according to any one of claims 13 to 16, ifirther comprising *.*. at least one additional linkage between the additional support unit and the first part of the *** support unit to prevent pivotal movement of the additional support unit relative to the first part of the support unit when the lockable hinge arrangements at each end of the rigid * * * *** * e linkage are unlocked.IS. An adjustable back rest according to claim 17, in which the at least one additional linkage is rigid and is pivotally coupled to the additional support unit and the first part of the support unit. * .* * * * *** **...*. * . * * ****.**S *5 S. * *5SS *S.