GB2478851A

GB2478851A - A backrest support assembly suitable for use with a wheelchair tilting platform to support the backrest of a wheelchair

Info

Publication number: GB2478851A
Application number: GB1104521A
Authority: GB
Inventors: Richard Fletcher; John Godwin Walters
Original assignee: Design Specific Ltd
Current assignee: Design Specific Ltd
Priority date: 2010-03-17
Filing date: 2011-03-17
Publication date: 2011-09-21
Anticipated expiration: 2031-03-17
Also published as: GB2478851B; GB201104521D0; GB201004460D0

Abstract

A backrest support assembly 1 for supporting, in use, the backrest of a wheelchair, e.g. when the wheelchair is supported on a wheelchair tilting platform [see Fig. 4], comprises a backrest support 8 adjustably mounted on a stem 10 for height adjustment and/or angular adjustment relative to the stem. The backrest support 8 may be mounted on the stem 10 by a friction locking means, preferably a self-locking friction sleeve to allow continuous height adjustment. The backrest support 8 for the wheelchair backrest may rotate about the axis of the stem , preferably an axis transverse to the stem. An adjustable headrest 22 may be pivotally fitted to the stem 10 of the assembly. The stem 10 of the support assembly may be pivotally coupled to a base, e.g. a back wall of a tilting platform used to tilt a wheelchair. Also disclosed is a backrest support assembly for supporting a wheelchair backrest wherein a backrest support is mounted to a stem by a friction locking sleeve. A further assembly is disclosed in which the stem of the backrest support assembly is pivotally mounted to a base to allow it to be rotated about a horizontal axis.

Description

Backrest Support Assembly The present invention relates to a support for the backrest of a wheelchair, in particular for a wheelchair that is parked on a reclining wheelchair platform.

Wheelchair platforms are used by medical personnel, for example in dental surgeries, to assist in the clinical treatment of wheelchair users. Typically a wheelchair is wheeled onto the platform as far as a back wall will allow and the wheelchair brake is applied. The platform can be tilted backwards to set the patients head, or feet, into a good treatment position for, say, dental or podiatry procedures. An assembly comprising a headrest and/or backrest may help to support the wheelchair and its user. As the patient remains in his or her wheelchair during treatment, manual handling and hoisting can be eliminated.

Wheelchair platforms may also be used for facial work as part of a medical or cosmetic procedure. They may even be used to tilt back a wheelchair user to facilitate hair washing and hairdressing. Such platforms may find use in care homes where many residents rely on wheelchairs for mobility.

Wheelchair platforms are often provided with a backrest support so that the wheelchair and user are supported when the chair is tilted back on the platform. In this position at least some of the weight of the wheelchair user will bear against the backrest of the chair and the backrest support. The backrest support may be cushioned for comfort, especially when used in conjunction with soft back chairs.

The backrest support provided by many reclining wheelchair platforms is fixed in position or only adjustable to a limited degree. Whilst it is possible to use a fixed height support to prevent the wheelchair from moving backwards, the use of a fixed height backrest support for the patient can create problems. Patients can vary widely in height, e.g. from a diminutive elderly lady to a tall, adult male with a sports injury. The backrest support position is likely to be a compromise that is not ideal for all patients.

The present invention seeks to provide an improved backrest support.

When viewed from a first aspect the present invention provides a backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a backrest support mounted on a stem, wherein the height of the backrest support on the stem is adjustable and/or the angle of the backrest support relative to the stem is adjustable.

In accordance with the invention the position of the backrest support can be adjusted in one or more ways, preferably in at least two ways. The backrest support is arranged to adjustably support the backrest of a wheelchair in use.

The height of the backrest support on the stem may be adjusted e.g. depending on the size of the wheelchair, the size of the user, and his/her seated position. The Applicant has found that the best area of a patient's back to provide support is at the shoulder blade region and the height of this can vary by as much as 500 mm depending on the patient. Embodiments of the present invention can ensure that adequate support is provided even for the extremes of the patient stature spectrum by making the height of the backrest support adjustable.

Although the height of the backrest support may be adjusted between one of a limited number of positions, for example by providing a set of spaced locking positions for the backrest support on the stem, this limits the range of movement available. Instead, it is preferable that the height of the backrest support on the stem is continuously adjustable. This means that the height of the backrest support can be adjusted exactly to the requirements of each wheelchair and user. In a preferred set of embodiments the backrest support is slidably mounted on the stem for linear motion so that it can be raised and lowered to any desired position.

However other embodiments may be envisaged, for example the backrest support could be mounted on a telescoping stem, or a screw thread mounting could enable the height of the support to be adjusted.

It is preferable that the backrest support can be locked at a selected height position on the stem. This may be achieved by providing any suitable position locking means. A mechanical lock may be provided. For example, a mounting pin could be unscrewed to allow movement of the support up or down the stem and then screwed into tight engagement with the stem when the position of the support has been selected. However the Applicant has devised a particularly convenient arrangement that allows both for continuous height adjustment of the backrest support and position locking. In a preferred set of embodiments the backrest support is slidably mounted on the stem by a friction locking means, such as a friction locking sleeve. The backrest support can be pushed down or pulled up the stem to a desired height and the friction locking means will ensure that the support is held on the stem at the selected height via a friction grip. Optionally the friction locking means may be self-locking so that height adjustment is quick and simple to carry out with a minimum number of components required. In at least some embodiments there is provided means to tighten and loosen the friction lock. For example a thumb button or lever could be provided to squeeze the friction lock for a tighter grip once the height of the backrest support has been adjusted. Such embodiments may still be relatively simple and cost effective to manufacture, while providing the additional peace of mind of a secure lock and release mechanism.

This is considered novel and inventive in its own right, and thus when viewed from a second aspect the present invention provides a backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a backrest support slidably mounted on a stem by a friction locking sleeve such that the height of the backrest support can be adjusted by moving the sleeve along the stem and the backrest support can be locked at a desired height position.

Such a friction-based height adjustment and locking system may require fewer mechanical parts than any known height adjustment mechanism. To its advantage it can be quick and simple for a user to operate. The friction locking means, such as a sleeve, may comprise a plain linear bearing to aid the sliding movement. A solid plastic bearing may be used.

Throughout the foregoing description it will be understood that the stem may, of course, comprise one or more stem members. Also the friction locking means, where provided, may have any suitable shape e.g. depending on the shape of the stem member(s) on which it is mounted. The stem and backrest support means may be manufactured from strong, lightweight materials such as stainless steel and/or aluminium.

In addition to the height position of the backrest support being adjustable, it is preferable that the angle of the backrest support relative to the stem is also adjustable. The backrest support preferably rotates about a horizontal axis. Where the stem extends generally vertically, the backrest support preferably rotates about an axis that is transverse to the stem. Thus the backrest support may be swivelled forwards or backwards to accommodate the profile of the wheelchair and its user.

The backrest support is preferably arranged to rotate around its axis through an angular range of up to ± 45° or even more.

Thus in accordance with the invention the backrest support is provided with two degrees of freedom in adjusting its position relative to the stem. The backrest support may also be arranged to swivel about the axis of the stem, thereby providing a third degree of freedom. The stem may be connected to the back wall of a tilting wheelchair platform. The backrest support assembly can provide optimally adjustable positional support for a wheelchair that is in a reclined position on a platform. This will be explained in more detail below.

The backrest support may take any suitable form. It may comprise a support panel or contoured support surface. However it is preferred that the backrest support comprises one or more generally horizontal support members against which the backrest of a wheelchair can be supported. This can ensure that there is adequate space to accommodate any attachments at the back of the wheelchair, such as oxygen bottles. The support member(s) may be concave.

The backrest support may comprise a cushion or pad, which can make the support more comfortable for users of softback wheelchairs. The pad may have a surface area designed to match a significant portion of the back of the wheelchair and its user, so as reduce pressure points and promote comfort. It is preferable that such a cushion or pad is removable so as to better accommodate hardback wheelchairs that do not need padded support. The cushion or pad may be removably attached to one or more horizontal support members as described above.

The backrest support assembly preferably further comprises a headrest. The headrest may be provided by a headrest assembly, either fixedly or removably connected to the backrest support assembly. One suitable type of adjustable headrest assembly is described in GB2453165.

In one set of embodiments the headrest is provided by a headrest assembly that is connected to an upper part of the stem in an adjustable manner. The headrest assembly preferably comprises a headrest and a headrest stem. It is preferred for the headrest to be pivotally mounted to its stem so that it can be tilted at different angles. The headrest stem may be mounted to the main stem of the backrest support assembly in such a way that its height and/or angle can be adjusted. The headrest may therefore be provided with up to three (or even more) degrees of freedom of its own, independent of any adjustment of the backrest support assembly. This enables the headrest position to be adapted to any patient and any desired patient position. For example, the position and angle of the headrest may be adjusted to support the head at an appropriate angle for treatment of the patient by a practitioner.

According to one preferred feature the headrest stem is connected to the main stem by a mounting pin that can be adjusted in position along at least a portion of the length of the headrest stem. Preferably the pin can be moved continuously to different positions along the headrest stem, thereby adjusting how far the headrest stem extends from the main stem of the backrest support assembly. The headrest stem may therefore be extended or retracted as required. For example, the headrest stem may be retracted when the assembly is not in use so that it takes up less space.

According to another preferred feature the headrest stem is pivotally connected to the main stem of the assembly, so that the headrest stem can be tilted forwards and/or backwards independently of the backrest support assembly. The pivotal connection may be provided by a pin mounting the headrest stem to an upper part of the main stem. This may be the same mounting pin that provides for height adjustment as described above. The mounting pin may be screwed down to lock the headrest stem in a particular position.

While the height and angular position of the backrest support, and any headrest (if provided), can be adjusted in a number of ways, the Applicant has recognised that it may be further beneficial for the main stem of the assembly to also be adjustable itself, for example relative to a wheelchair platform to which it is attached.

Movement of the stem can add an additional degree of freedom in positioning the backrest support and/or headrest of the assembly.

In a preferred set of embodiments the backrest support assembly further comprises a base to which the stem is pivotably mounted about a horizontal axis. The base may, for example, connect the stem to the back wall of a tilting wheelchair platform.

The pivotal connection between the base and stem allows the stem to be tilted forwards and/or backwards and thus the backrest support to be moved forwards and/or backwards relative to the back of the wheelchair. This means that all types and sizes of wheelchair can be accommodated, independently of the form of any platform on which the wheelchair is parked. Once the stem has been tilted to move the backrest support assembly forwards or backwards, and the height of the backrest on the stem adjusted as required, to bring the backrest into contact with the wheelchair, then the backrest support itself may be titled relative to the stem to provide fine adjustment of the final support position. The angle of tilt of the backrest support may be adjusted depending on the reclined position of the wheelchair. The seating position of the patient in the wheelchair may change as the chair is tilted back. The backrest support assembly can be adapted dynamically to the patient's position to provide both support and comfort.

Previous proposals for reclining a wheelchair on a platform have not enabled the angle of any backrest support and/or headrest to be adjusted through a large range of angles in addition to the angle of the pivoting platform. Mounting the backrest support on a stem that can be swivelled about its own base can therefore provide unique advantages in terms of optimally adjusting the backrest support and/or headrest. In particular, when the base connects the backrest support assembly to the back wall of a tilting wheelchair platform then the backrest support assembly can be angled independently of the titled position of the platform.

This feature is considered novel and inventive in its own right, and thus when viewed from a further aspect the present invention provides a backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a base and a backrest support mounted on a stem, wherein the stem is pivotally mounted to the base such that it can be rotated about a horizontal axis though an angular range of at least 60°.

As the stem can pivot relative to the base across an angular range of at least 600, it may be tilted forward by 30° or more and back by 300 or more. Preferably the stem is pivotally mounted to the base such that it can be rotated about a horizontal axis though an angular range of at least 90°, so that it may be tilted forward by 45° or more and back by 45° or more. Preferably the range of angular movement of the stem may be up to 100°, 110°, 120°, 130°, 140°, 150°, 1600, 170° or even 1800.

The stem may not tilt forwards and backwards to the same degree.

For safety purposes, the stem may be arranged to tilt backwards only to a limited degree relative to the vertical. The stem may be arranged to tilt backwards from the vertical by up to 450, more preferably up to 50°, further preferably up to 60° and most preferably up to 700. The angle of tilt backwards may match the range of tilting angles achieved when the wheelchair is reclined on a platform. This can ensure that the backrest support assembly can always be placed in an appropriate position for a reclined wheelchair.

Preferably the stem may be arranged to tilt forwards relative to the vertical to a greater degree, for example by up to 50°, 60°, 70°, 80° or nearly 90° from the vertical. The stem and backrest support assembly can therefore be folded down when not in use so as to lie substantially horizontally. This can reduce the storage space required when the assembly is not in use. The ability of the stem to fold down may be particularly advantageous when the assembly is used with a compact wheelchair platform, such as is described in more detail below.

The invention extends to a wheelchair platform comprising a tilting platform for a wheelchair comprising a base to support a wheelchair in use and a back wall, wherein a backrest support assembly as described above is connected to the back wall of the tilting platform. In particular, where the backrest support assembly comprises a stem pivotally mounted to a base then the base of the backrest support assembly may be connected to the back of the tilting platform.

The reclining wheelchair platform may take any suitable form. However there is described below some preferred constructions of a wheelchair platform for use with the backrest support assembly according to all of the aspects and preferred features of the invention as described above.

In one set of embodiments, the wheelchair platform preferably comprises a tilting platform for a wheelchair comprising a base to support the wheelchair in use and a back wall, wherein the platform is pivotably connected between a pair of side supports. Preferably the device further comprises actuating means operable to tilt the platform, wherein the pivot axis for the platform is forward of the back wall and above the base, and wherein the actuating means is forward of the back wall. As the pivot axis for the platform is provided forward of the back wall of the platform and higher than its base, when the base of the platform is tilted back from an initial horizontal position then a lower part of the back wall actually swings forward beneath the pivot axis. The effect is that the centre of gravity of the platform, with the load of the person sat in the wheelchair, is kept forward of the back wall. During tilting of the platform the centre of gravity preferably moves within a limited horizontal range about the pivot axis. The platform and its user is cradled about the pivot axis.

As the pivot axis is provided forward of the back wall of the platform and raised above the base of the platform, it passes through the wheelchair and its user. The wheelchair user therefore feels less of the tilting movement, for example as compared to systems where the platform pivots about a point rearward of the back wall. This helps the wheelchair user to feel secure. A further advantage is that the user can shift his or her weight in the wheelchair in a tilted position of the platform and not feel a disturbing shift in his or her centre of gravity. Such a platform is therefore more comfortable in use.

As the weight of the wheelchair and user is generally kept forwards, the wheelchair platform is more stable overall. The location of the pivot axis provides the apparatus with a degree of self-stabilisation. This means that the need for a stabilising chassis under the platform is reduced. The wheelchair platform can therefore be made lighter and more compact.

As mentioned above, it is preferable that the pivot axis for the platform is positioned such that in use the centre of gravity of the tilting platform with its wheelchair load moves within a limited range laterally of the pivot axis. Preferably the platform can be tilted by up to 450, more preferably up to 50°, further preferably up to 60° and most preferably up to 70° from the horizontal. The increased stability of the apparatus therefore allows for a larger range of tilting movement than is usually possible in currently available wheelchair platforms. The increased range of tilting angles may also mean that a person working on the wheelchair user does not have to adjust the height of his stool.

The Applicant has appreciated that it is particularly advantageous for such a wheelchair platform to include a backrest support assembly as described above with respect to the various aspects and preferred features of the invention, as the multiple degrees of freedom in the movement and adjustment of the backrest support position can help the backrest support to be adapted to a patient's position across the full range of tilting angles of the platform. This is also true of the adjustable headrest, where provided in conjunction with the backrest support assembly.

Tilting angles up to 70° are also advantageous as this allows for the provision of a recovery position wherein a patient's body and legs are placed higher than the patient's head to encourage blood flow. For example, when treating a dental patient the tilt angle may be 45-50° during normal use with an angle of up to 60 or 70° reserved for recovery and resuscitation.

These advantages may be enhanced when the actuating means for the tilting motion is also positioned forward of the back wall of the platform, i.e. adjacent the base of the platform. This further increases stability as the weight of the actuating means, which can represent a substantial fraction of the overall weight, is concentrated through the same floor area as the weight of the tilting platform.

Furthermore this helps to make the apparatus compact, for example as compared to wheelchair platforms which have the actuating means behind the back wall of the platform. The wheelchair platform may therefore take up less floor space in operation as well as being easier to store. This can be particularly important in clinical environments where there may be multiple pieces of medical equipment in the room and the medical personnel need plenty of space to circulate.

The actuating means can be positioned so as to maximise the space-saving layout of the machine. Preferably there is provided a pair of actuating means, one at or in each of the side supports. The actuating means can therefore contribute to the weight of the side supports, which provide a stable frame for the pivotally mounted platform therebetween. With such an arrangement there is even less of a need to provide a supporting chassis which passes beneath the base of the platform. The two side supports alone can provide a stable footprint on the floor. Without a chassis the base of the platform may be lowered closer to the floor. Furthermore the weight of a conventional support chassis can be removed so the apparatus is lighter and easier to transport.

Such embodiments therefore provide a more compact wheelchair platform with the main components clustered around the platform itself, preferably at the sides of the platform. The position of the pivot axis and of the actuating means promotes self-stabilisation so that a supporting chassis extending beneath the base of the platform is not necessarily required for stabilisation. The wheelchair platform can comprise fewer parts and be made smaller and lighter than known models.

The actuating means could be provided below the base of the platform so as to minimise the lateral space taken up in addition to the footprint of the platform itself.

However, this may require the base of the platform to be raised above the floor with ramping required to manoeuvre a wheelchair on to the platform. Or the base of the platform may need to be shaped, e.g. with a recess, to accommodate the actuating means. As mentioned above, it is therefore preferred that the actuating means is positioned at the side(s) of the platform, preferably within the side support(s). This is advantageous as it means that the actuating means is not taking up any space beneath the platform. At least part of the base of the platform may therefore be arranged to contact the floor in its lowered position without any need to accommodate the actuating means. This maximises the range of movement of the platform and gives design freedom. -11 -

The actuating means can be any mechanical or electromechanical device capable of providing a force to tilt the platform. For example, lever arms, telescopic rods, lifting jacks or cams may be used. The actuating means may be manually operable but preferably it is electrically controlled, for example using an electric motor, for ease of operation by both clinicians and patients. A preferred actuating means comprises a hydraulic ram. A hydraulic actuating means advantageously provides a smooth motion and quiet operation. A control pad for the hydraulics may be provided on one of the side supports for easy access. A remote control is also preferably provided, e.g. a radio frequency controller. The actuating means can be mains or battery operated. A rechargeable battery may be used.

In order to help keep the apparatus compact, and for ease of cleaning, each actuating means e.g. hydraulic ram is preferably provided within one of the side supports. It is further preferred that the actuating means do not extend outside the side supports, even during operation. The hydraulic pump is preferably located within the back wall of the platform. One or more batteries may also be provided within the back wall of the platform. The actuating system is therefore fully enclosed.

In some currently available products the actuating means, such as hydraulic rams, are located behind the back wall of the wheelchair platform so that there is space for the ram to extend and push the platform up about its pivot. In other products a hydraulic ram is provided beneath the base of the platform, again with space for the ram to extend so as to push up the platform from below. A hydraulic piston will provide more power when pushing as it has the full volume of fluid behind the ram.

However the Applicant has realised that the space required by a hydraulic actuator in operation may be reduced by preferably arranging for the ram to move from an extended position when the platform is lowered to the floor to a retracted position when tilting the platform up from the floor. In other words the hydraulic actuator is arranged to pull the platform round its pivot rather than to push. This is in complete reverse to conventional hydraulic operation.

The wheelchair platform may comprise a tilting platform for a wheelchair that is pivotably connected between a pair side supports and hydraulic actuating means operably connected to the platform such the platform is tilted up from a horizontal position when the actuating ram is retracted from an extended position. According to this arrangement the hydraulic actuator is preferably fully extended when the platform is horizontal, i.e. in the machine's default and storage position, and then retracted when the machine is operating to tilt the platform. This means that the actuator takes up less space in operation rather than more, as is the norm. This helps to keep the apparatus compact at all times.

In order to increase the power available from the hydraulic actuator when the ram is being pulled back into the cylinder, preferably the diameter of the ram is made small compared to the diameter of the cylinder, so as to maxim ise the annulus of fluid around the ram. A thinner ram than usual may therefore be used.

Each actuating ram is preferably positioned such that in its extended state it fits within one of the side supports. Thus during operation the ram retracts into its cylinder inside the side support. In a preferred embodiment the hydraulic rams are operably connected to a back wall of the platform. In order for retraction of the rams to tilt the platform, the rams are preferably located forward of the back wall and below the pivot axis. As the rams retract, the back wall is pulled forward beneath the pivot so that the base of the platform swings up. The result is a cradling motion around the pivot.

Preferably the side supports do not extend behind the back wall of the platform when in the horizontal position. It is also preferable that the side supports only extend along a portion of the base of the platform. The side supports may only extend along about 30%, 40%, 50%, 60% or 70% of the length of the base. The space taken up by the apparatus is therefore preferably dictated by the platform itself.

Preferably the wheelchair platform is mobile, for example using wheels or an air cushion to ride across the floor. This allows the platform to be moved to one side of a room when not in use, or transferred between different rooms. It also facilitates movement of the platform for cleaning, which is especially important in a clinical environment. However the issue of storage whilst not in use remains a problem, whether the platform is mobile or not. The Applicant has devised a unique solution to this problem. In order to reduce the space taken up by the apparatus when not in use, it is preferred that at least a portion of the tilting platform is hinged so as to allow the platform to be folded when not in use.

The wheelchair platform may comprise a pivotably mounted platform for a wheelchair, wherein at least a portion of the platform is hinged so as to allow the platform to be folded when not in use. Accordingly the platform may be folded up into a compact unit which may then be stored under a worktop or other surface.

The folded unit may also be easier to transport and manoeuvre through doors and into small spaces. It should be understood that what is meant is a portion of the 1 0 platform which supports a wheelchair in use, rather than a ramp portion which is folded up and down only to help wheelchair entry to the platform.

Preferably the base of the platform is hinged such that it can be folded back on itself. This can greatly reduce the footprint of the machine, for example to an area 1 5 smaller than that normally taken up by a wheelchair.

The hinged base portion may represent about 30%, 40% or 50% of the area of the base. Preferably the base is hinged about halfway along its length, alternatively up to 2/3 of its length forward of the back wall, so as to allow between 1/3 and half of the base to be folded over when the platform is not in use. Preferably the hinge in the base is arranged to coincide with the forward end of the side supports. The forward portion of the base may therefore be folded over into the area between the side supports to minimise the size of the machine. Preferably the forward portion of the base can be pivoted over to rest the front edge of the platform base on a rear portion of the platform base.

The platform base may comprises means for locking the hinged portion in its open and/or folded configuration. This can provide stability when the base is opened out ready to receive a wheelchair, and safety when the base is folded over for transport, storage, etc. The back wall may itself comprise a hinged portion. However, it is preferred that the backrest support assembly is pivotally connected to the back wall of the platform so as to allow the assembly to fold down on top of the folded base, as is described above. The assembly may comprise both a hinged backrest support -14-portion and a hinged headrest portion. The headrest may fold down independently of the backrest support assembly. Alternatively or additionally, the headrest and/or backrest may be removable. However, to facilitate deployment of the wheelchair platform it is preferred that the hinged portion(s) can be simply folded up and down.

The hinged portion(s) of the backrest and/or headrest assembly may also be locked into position.

It is a preferred feature that the platform base is wider at its front end than at the rear. Preferably the platform has a flared base profile. Any side walls will therefore curve outwardly towards the front of the base. This allows for easier access of the wheelchair to the platform. A curved trajectory for access to the platform is possible.

Although rear stabilisers may not be necessary for low wheelchair loads and/or small tilting angles, one or more stabilising arm(s) are preferably connected at the rear of the side supports. The stabilising arm(s) may be retractable, for example being rotatable relative to the side supports to come into contact with the floor behind the platform. They can help to prevent the apparatus from tipping over as the platform is tilted back.

According to another preferred feature the wheelchair platform is provided with castors, preferably ball castor units. Preferably the ball castor units are retractable.

This means that the platform may be lowered completely into contact with the floor for stability when the platform is in use. The wheelchair platform preferably comprises means for providing and releasing compressed air for raising and lowering the apparatus. A suitable ball castor assembly that is retractable is described in GB2454933. When the ball castors are lowered, the wheelchair platform can be moved in any direction, unlike a wheeled device. Movement of the wheelchair platform is also facilitated by its light and compact construction.

The needs of hygiene are of significant importance in a clinical setting. Where, as is preferred, the actuating means are provided within the side supports, the working mechanism is preferably enclosed. The other operational components such as hydraulic pump, batteries, etc. are preferably provided in a cavity in the back wall of the platform. The wheelchair platform is therefore easy to clean and more hygienic than machines which have exposed working parts, such as hydraulic rams behind or below the platform. For the same reasons it is preferred that the platform is made from sheet metal, preferably with a sintered powder coating. The platform may be formed from an L-shaped piece of sheet metal so as to minimise the number of parts and surfaces which can harbour bacteria. A single hinged portion may be provided in the platform base so to reduce the potential for dirt collection in the hinge.

It will be appreciated that the backrest support assembly described herein is not limited to use with reclining wheelchair platforms and may find use in supporting 1 0 wheelchairs and even seated persons in other situations.

Some preferred embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the components of a backrest support assembly in accordance with an embodiment of the present invention; Figure 2 is an enlarged view of part of the backrest support assembly; Figures 3a to 3d show the backrest support assembly adjusted to different positions; Figure 4 is a perspective view of a wheelchair platform; and Figures 5a and Sb show the wheelchair platform in a folded configuration.

There is shown in Figures 1 to 3 a backrest support assembly 1 generally comprising a backrest support portion 2 and a stem portion 4. The backrest support portion 2 comprises a backrest support member 6 to which there is shown attached a support pad 8. The support pad 8 may be removable. The backrest support member 6 is articulated such that the forward part carrying the pad 8 can be tilted forwards or backwards to adjust the angle of the pad 8.

The stem portion 4 comprises a pair of upright stems 10 connected to a common base 12. The backrest support member 6 is slidably mounted on the upright stems 10. As can be seen from Figure 2, the two parallel stems 10 pass through apertures 14, 15 provided in the backrest support member 6. Polymer bearing rings 16 are provided in the apertures 14, 15. The backrest support portion 6 is held at a particular height on the stems 10 by a friction lock. A thumb button 18 is provided for the friction lock.

It is also seen from Figure 2 that the apertures 15 receiving the stem 10 on the leftside are made wider than the apertures 14 receiving the stem lOon the rightside. The degree of play provided by the widened apertures 15 allows the polymer bearings 16 on that side to float' so that the lateral spacing between the stems 10 may be adjusted to accommodate any changes in parallelism.

Turning back to Figure 1, it can be seen that a headrest assembly 20 is mounted at the upper end of the stem portion 4. The headrest assembly 20 generally comprises a headrest pad 22 and a headrest stem 24. The headrest pad 22 is pivotally connected at the top of the stem 24 with a locking wheel 26. The headrest pad 22 can be tilted to a desired angle and then locked into position.

The headrest stem 24 comprises a continuous aperture 28 along most of its length.

A mounting pin 30 passes through the aperture 28 to connect the headrest stem 24 to a mount 32 at the top of the main stems 10. The mounting pin 30 can be loosened and its position along the aperture 28 adjusted to allow the headrest stem 24 to be extended or retracted. Furthermore, the headrest stem 24 can be tilted relative to the mount 32 by pivoting it about the mounting pin 30. A locking wheel 33 is provided to fix the mounting pin 30 and stem 24 in position.

As is shown schematically in Figure 1, the stem portion 4 is pivotally mounted to the base 12. The stem portion 4 may therefore be tilted forwards or backwards.

Movement of the stem portion 4 is effected by a worm and wheel assembly 34 in thebasel2.

The various degrees of freedom of the backrest support assembly 1 can be seen in Figures 3a to 3d. Figures 3a and 3b show how the height of the backrest support portion 2 on the stem portion 4 can be adjusted, namely by sliding the backrest support member 6 up and down on the stems 10. Furthermore, it can be seen that the backrest support pad 8 can be pivoted relative to the backrest support member 6. The backrest support portion 2 is therefore provided with at least two degrees of freedom in its position.

It is also seen from Figures 3a and 3b how the headrest assembly 20 can be adjusted. Firstly, the headrest stem 24 can be moved up or down relative to the mount 32 provided at the top of the main stem portion 4, to extend or retract the headrest assembly 20. Secondly, the headrest stem 24 can be pivoted about the mounting pin 30 passing through the mount 32, so as to tilt the whole headrest assembly 20 forwards or backwards relative to the main stem portion 4. Thirdly, the headrest pad 22 can be swivelled back and forth.

Figures 3c and 3d show how, in addition, the stem portion 4 of the backrest support assembly 1 can be pivoted backwards and forwards about a horizontal axis passing 1 5 through the base 1 2. The overall tilting motion of the backrest support assembly 1 can be combined with any number of the different height and/or angle adjustments described above. The final position of both the backrest support pad 8 and the headrest pad 22 can therefore be controlled to a very high degree.

Figures 4 and 5 show an example of a wheelchair platform 100 that may be provided with the backrest support assembly 1 of Figures 1 to 3 instead of the one shown. The wheelchair platform 100 comprises a tilting platform 200 which supports a wheelchair in use (not shown). The platform 200 is generally L-shaped with a substantially horizontal base portion 40 which can support the load of a wheelchair and a substantially vertical back wall 60. The base portion 40 comprises a floor on which the wheels of a chair can rest and side walls to guide the wheels laterally. Attached to the back waIl 60 is a backrest and headrest assembly 70. The backrest and headrest assembly 70 has some features in common with the assembly 1 described above. However, it does not provide as much freedom of adjustment and can advantageously be replaced with the assembly 1 instead.

The platform 200 is pivotably connected between a pair of side supports 80. The pivot points 90 are positioned on the side panels 80 above the base wall of the platform 200 and in front of the back wall 60 of the platform 200. The platform 200 can therefore be tilted about an axis connecting the two pivot points 90.

The supporting side panels 80 are placed one on each side of the platform 200, extending from the back wall 60 along a portion of the length of the base 40. The side support panels 80 are connected beneath the platform 200 by a base plate 110 that is smaller than the floor area of the platform base 40. The base plate 110 may comprise a sandwich construction of a wooden board between metal plates. The base plate 110 can be used to guide and hide electrical wires and hydraulic hoses.

The side supports 80 provide an anchor point for a pair of hydraulic actuators 112.

The hydraulic actuators 112 act below the pivots 90. The ram of each hydraulic actuator 112 is operably connected to the back wall 60 of the platform 200 through a radial slot 114 in the side panel 80. The radial slots 114 define the extent of tilting motion available to the platform 200. When the platform is in the horizontal position, the rams of the actuators 112 are in their extended condition. The radial slots 114 are designed to give the base 40 a maximum tilting angle of 70° from the horizontal when the rams are retracted.

A front portion 116 of the platform base 40 is hinged so as to allow the platform 200 to be folded when not in use. The front portion 116 is wider at the end remote from the hinge 118 to allow for easy access of wheelchairs. The front portion 116 provides the base 40 with a flared profile so that a curved trajectory for access to the platform 200 is possible.

Sensitive strip switches 122 are attached to the upper edge of each side support panel 80. Should any person actuate these switches, whilst the platform 200 is being lowered, the platform 200 will immediately stop its motion and move upwards a short distance to release any person or object. Strip switches 122 mounted on the underside of the front and side edges of the hinged portion 116 of the platform base 40 also produce a similar action when operated. These switches 122 can therefore detect when an object is trapped below the platform 200.

When the platform 200 is in the loading position, the base 40 is generally horizontal but is inclined at a very slight angle downward from the back wall 60. The front edge of the base portion 40 does not rest on the floor so as to provide clearance for the strip sensors 122 mounted underneath. Feet (not shown) may be attached underneath the base 40 close to its front edge to ensure that the sensors 122 are kept at a minimum distance from the floor and do not trigger when the base 40 is lowered normally. However the front portion 116 of the base 40 is still close enough to the floor that a wheelchair can be bumped up onto the base 40 to gain access to the platform 200.

The electrical system is based on 24V DC. This supply is normally taken from batteries contained within the platform 200, in a cavity within the back wall 60. The batteries (not shown) can be charged from a remote charger that may be plugged into the platform 200. Power may also be taken from a remote 24V supply such as a mains socket. A hydraulic pump is also provided in the cavity in the back wall 60.

The hydraulic pump is operated on 24V with its direction of rotation determining the 1 5 flow direction of the hydraulic fluid. The hydraulic actuators 112 are controlled by a programmable computer chip through relays on a circuit board provided in one of the side panels 80. Control circuitry and hydraulic pipes pass underneath the platform 200 but are covered by the base plate 110 so that they do not trail on the floor.

The platform 100 is moved on retractable ball castor units 124 mounted at either end of the side panels 80 and at the corners of the base plate 110. The castors 124 are ejected to support the platform 100 by low pressure air supplied by a compressor and retracted by dumping the compressed air. The compressor is provided in one of the side panels 80. Pneumatic air supply lines pass beneath the platform 200 in the space covered by the base plate 110. There may be provided a plug connection to an external supply of compressed air, for example in a dental surgery.

Stability of the platform 100 is ensured by deploying two rear stabilisers 130. The stabilisers 130 are attached one to each side support panel 80 using a vertical axis hinged joint. For storage the stabilisers 130 can be rotated to a position behind the platform 200 (see Figure 5b). A foot 132 is attached to each stabiliser 130 at its distal end to come into contact with the floor when the platform is lowered ready for use. As the stabilisers 130 fold across the back wall 6, they prevent any -20 -inadvertent tilting motion of the platform 200 until they have been extended rearwardly into position.

Turning to Figures 5a and 5b, it can be seen how the platform 100 is folded up when not in use. The front portion 116 of the platform base 40 is hinged along a line coinciding with the front ends of the side panels 80. This allows the front portion 116 of the platform 200 to be rotated back so as to rest on the main portion of the platform base 40 between the side panels 80. The backrest and headrest assembly 70 can be pivoted about a horizontal axis where it is hingedly connected to the back wall 60 of the platform 200. Where the backrest support assembly 1 is provided instead of the assembly 70 shown, its base 12 may be connected to the back wall 60 of the platform 200. Forward rotation of the assembly 1 relative to the base 12 will then cause the assembly ito fold down into a storage position, as is shown for the assembly 70. The back rest support 134 conveniently fits down between the hinged portion 116 of the base 40 and the back wall 60. The head rest 136 is pivotally connected to the assembly 70 and can be folded back on top of the backrest support 134. A very compact unit is thereby achieved, with all the components generally folded within the volume of the L-shaped platform 200.

Although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.

Claims

-21 -Claims 1. A backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a backrest support mounted on a stem, wherein the height of the backrest support on the stem is adjustable and/or the angle of the backrest support relative to the stem is adjustable.
2. A backrest support assembly as claimed in claim 1, wherein the height of the backrest support on the stem is continuously adjustable.
3. A backrest support assembly as claimed in claim 1 or 2, wherein the backrest support is slidably mounted on the stem such that it can be raised and lowered to a desired position.
4. A backrest support assembly as claimed in claim 1, 2 or 3, wherein the backrest support can be locked at a selected height position on the stem.
5. A backrest support assembly as claimed in any preceding claim, wherein the backrest support is slidably mounted on the stem by a friction locking means.
6. A backrest support assembly as claimed in claim 5, wherein the friction locking means is self-locking.
7. A backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a backrest support slidably mounted on a stem by a friction locking sleeve such that the height of the backrest support can be adjusted by moving the sleeve along the stem and the backrest support can be locked at a desired height position.
8. A backrest support assembly as claimed in any preceding claim, wherein the backrest support is rotatable about the axis of the stem.
9. A backrest support assembly as claimed in any preceding claim, wherein the backrest support is rotatable about an axis transverse to the stem.

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10. A backrest support assembly as claimed in claim 9, wherein the backrest support can be swivelled forwards and/or backwards about the axis.
11. A backrest support assembly as claimed in any of claims 8, 9 or 10, wherein the backrest support is arranged to rotate around the axis through an angular range of up to ± 45° or greater.
12. A backrest support assembly as claimed in any preceding claim, wherein the backrest support comprises one or more generally horizontal support members against which the backrest of a wheelchair can be supported.
13. A backrest support assembly as claimed in any preceding claim, further comprising a headrest.
14. A backrest support assembly as claimed in claim 13, wherein the headrest is provided by a headrest assembly that is connected to an upper part of the stem in an adjustable manner.
15. A backrest support assembly as claimed in claim 14, wherein the headrest assembly comprises a headrest stem and the headrest is pivotally mounted on the headrest stem.
16. A backrest support assembly as claimed in claim 14 or 15, wherein the headrest assembly comprises a headrest stem connected to the stem of the backrest support assembly in an adjustable manner such that its height and/or angle can be adjusted.
17. A backrest support assembly as claimed in claim 14, 15 or 16, wherein the headrest assembly comprises a headrest stem connected to the stem of the backrest support assembly such that it can be extended or retracted as required.
18. A backrest support assembly as claimed in any of claims 14 to 17, wherein the headrest assembly comprises a headrest stem pivotally connected to the stem of the backrest support assembly.

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19. A backrest support assembly as claimed in any preceding claim, wherein the backrest support assembly further comprises a base to which the stem is pivotably mounted about a horizontal axis.
20. A backrest support assembly as claimed in claim 19, wherein the stem can be rotated about the horizontal axis though an angular range of at least 60°.
21. A backrest support assembly for supporting, in use, the backrest of a wheelchair, the assembly comprising a base and a backrest support mounted on a stem, wherein the stem is pivotally mounted to the base such that it can be rotated about a horizontal axis though an angular range of at least 60°.
22. A backrest support assembly as claimed in claim 20 or 21, wherein the stem can be rotated about the horizontal axis though an angular range of at least 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, or 180°.
23. A backrest support assembly as claimed in claim 20, 21 or 22, wherein the stem is arranged such it can be rotated backwards relative to the vertical through a limited angle of up to 30°, 45°, 50°, 60°, or 70°.
24. A backrest support assembly as claimed in any of claims 20 to 23, wherein the stem is arranged such it can be rotated forwards relative to the vertical through an angle of up to 50°, 60°, 70°, 80°, or 90°.
25. A wheelchair platform comprising a backrest support assembly as claimed in any preceding claim, wherein the backrest support is arranged to adjustably support the backrest of a wheelchair during use of the platform.
26. A wheelchair platform comprising a tilting platform for a wheelchair comprising a platform base to support a wheelchair in use and a back wall, wherein a backrest support assembly as claimed in any of claims 1 to 24 is connected to the back wall of the tilting platform.

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27. A wheelchair platform as claimed in claim 16, wherein the stem of the backrest support assembly is pivotally mounted to a or the base that is connected to the back wall of the tilting platform.
28. A wheelchair platform as claimed in any of claims 25 to 27, further comprising actuating means operable to tilt the platform.
29. A wheelchair platform as claimed in claim 28, wherein the actuating means is positioned forward of the back wall of the platform and below the pivot axis of the platform.
30. A wheelchair platform as claimed in claim 28 or 29, wherein the actuating means comprises a hydraulic ram arranged such that the ram moves from an extended position when the platform is lowered to the floor to a retracted position when the platform is tilted back.
31. A wheelchair platform as claimed in any of claims 25 to 30, wherein at least a portion of the platform base which supports a wheelchair in use is hinged so as to allow the platform to be folded when not in use.
32. A backrest support assembly substantially as hereinbefore described with reference to Figures 1 to 3.
33. A wheelchair platform substantially as hereinbefore described with reference to Figures 4 and 5.