The present invention relates to a powered seat for assisting a person to move between seated and standing positions, and vice versa.

BACKGROUND TO THE INVENTION

Elderly and/or disabled people can have difficulty when sitting down in or standing up from a chair. A person in the process of standing up from a chair requires a degree of control over their muscles and overall body weight, to avoid falling. They may also require physical assistance to sit down in a chair in a seated position.

'Riser recliner' or 'lift' chairs are a type of sit-to-stand device that can ease the transition between standing and seated positions. These chairs typically include a powered mechanism which raises the chair squab and tilts it forwards, to aid a person getting up. In some cases, the entire chair is lifted. The basic principle is that there is a reduced distance for a person to cover to reach a standing position from having been sat down. Power is typically provided via the mains, with a back-up battery should the mains power fail.

However, although such chairs do help, standing up from a seated position may still require significant effort, as may sitting down in a controlled manner. From a sitting position, when a riser recliner chair tilts forwards, the transfer of weight from a person's buttocks and legs to their feet is incomplete. A significant degree of effort is still required to stand up, using leg muscles to transfer weight to the feet. On smooth wooden floor, for example, this can be a slipping hazard.

The action of tilting the seat can also impart to the occupant a disconcerting feeling of slipping off the seat, due to shear on the legs. In fact, this can result in injury if the person does slip off the seat, unless prepared to suddenly take their own weight. Furthermore, the arms of the seat dip with the tilting of the chair, making it harder for a person to support their weight with their arms as they try to stand. This also makes it difficult to sit back into the same seat, if it remains tilted forward after having risen. Other problems with existing riser recliner systems relate to built-in footrests. Often, a manual lever is used to release a sprung mechanism and deploy an integrated footrest at the front of the chair, using a scissor-type mechanism. The footrest is then urged forwards and upwards as the chair moves to a reclined position. However, as it rises, the edge of the footrest can dig into a person's legs, which can exert an uncomfortable level of pressure over a small area.

Another feature of some riser recliner chairs is that castors or wheels are provided on the base, including brakes to releasably lock the wheels against rotation. This makes it easier to re-position the chairs, when re-arranging a room, for example. However, the lever used to lock the wheels presents a trip hazard for people walking near the chair.

It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to a first aspect of the present invention, there is provided a powered seat for assisting a person in moving between seated and standing positions, the powered seat comprising

a seat squab having front and rear movable portions, and

a mechanism enabling movement of the seat squab portions between a seated configuration in which the portions are substantially aligned for providing a seat, and a standing configuration in which the rear seat squab portion is higher than the front seat squab portion, and both seat squab portions are tilted forwards at different angles.

This seat significantly changes and improves the manner in which a seated person can be assisted to a near standing position. The rear seat squab portion can be raised and tilted forwards. By separating the front and rear seat squab portions, and raising the rear portion higher than the front portion and tilting it, the seat provides support where it is most needed when standing up. Equally, when the seat has been raised, a user can also use the reverse transition of the seat squab portions to aid in sitting down on or in a seat, e.g. an armchair. In other words, the mechanism can be operated to cause separation of the seat squab portions (when transitioning from the seated configuration to the standing configuration), and to cause convergence of the seat squab portions into a complete seat squab (when transitioning from the standing configuration to the seated configuration).

One of the advantages of this powered seat is that there is no predetermined point where the user has to stand up, or else slip off the seat as it is raised. Whilst the front portion is tilted to incrementally steeper angles, the rear of the seat squab provides continuous support under the user's buttocks for both transitions. This means that the user retains the final decision regarding when to fully transfer their weight to their feet. The degree of effort required to transfer the majority of their weight from the chair to their feet is minimised by the extent to which the rear seat squab portion is raised. In particular, there is less distance to cover between the raised supported position and the standing position, and so the user does not need to expend as much energy to finally stand.

The seat squab portions may be substantially adjacent in the seated configuration, and substantially spaced apart in the standing configuration. This allows a person to be moved from a seated position to a pseudo-standing position much more completely than existing seats. In particular, spacing the portions apart at different heights provides appropriate support for a person's buttocks when they are trying to stand up. It also allows the seat squab to be used as a conventional seat in the seated configuration.

The seat squab portions may be independently tiltable. In other words, the angle of the rear seat squab portion may be changed independently of the angle of the front seat squab portion. The rear portion is tilted forwards in the standing configuration, preferably by an angle of between 70° and 85°. This eases the transfer of a person's weight to their feet without first sliding off the seat squab, and without requiring excessive effort by the person to avoid sliding off. The seat squab portions may have complementary parts or shapes for fitting together in the seated configuration. Preferably, the complementary part of the rear seat squab portion is a projection with a flexible front. The front may then be tethered, for example via a sheet, to part of the powered seat for downward deformation in the standing configuration. In other words, as the seat enters the standing configuration, the sheet is pulled taut and so deforms the shape of the projection.

In the seated position (or configuration), this allows the portions to fit together and form an uninterrupted support surface, in the manner of a conventional seat, and allows the portions to easily separate and converge when changing the seat position. Tethering the front of the rear seat squab portion to a fixed lower point allows the projection to be pulled down when the seat is put into the standing configuration. The tension across the front edge of the rear portion assists a person to transfer their weight onto their feet when standing up.

The rear seat squab portion may be disposed in a region over (or above) the front seat squab portion in the standing configuration. This means that the rear of the seat has been brought forwards sufficiently to bring the user's hips substantially vertically above their knees, minimising the extent of the supported transition to a standing position, for example. This can be achieved by having the rear seat squab portion partially or fully overlying the front seat squab portion, but positioned vertically higher than that portion.

The front seat squab portion may be pivoted between the seated and standing configurations without a front region of that portion substantially moving forwards or rearwards (relative to the front of the chair). This avoids the front portion pushing into the user's legs when standing up or sitting down, which might destabilise them.

A back rest may be provided adjacent to the rear seat squab portion. The back rest may be movable with one of the seat squab portions when the seat is transitioned between seated and standing configurations. The back rest may be adapted to be substantially upright in the standing configuration. The back rest may be reclinable when the seat is in the seated configuration. On operation of the mechanism, the back rest may be automatically brought substantially upright prior to movement of (or separation of) the seat squab portions.

Providing a back rest requires less in the way of sustained postural control on the part of the user. This is appropriate where the seat is being used for relaxation as opposed to physical rehabilitation, for example. Raising the back rest with the seat squab can maintain substantial contact with the seat occupant's back for some of the transition to the standing position, which is more comfortable for the occupant. It also avoids creating a gap between the rear seat squab portion and the back rest. Unlike existing seats which can tilt an entire chair about an axis, maintaining the back rest upright during the transition to a standing position avoids the upper end of the back rest pushing the user off the seat squab before the seat reaches the standing position.

There may be at least one grip portion (or handhold) provided adjacent to the seat squab. The grip portions(s) may be movable with the rear seat squab portion when the seat is transitioned between seated and standing configurations. The grip portions may be adapted to move along a substantially vertical axis. The grip portions may be adapted to be raised and lowered without changing their orientation. Alternatively, the grip portions may tilt forward to substantially the same angle as the rear seat squab portion. Where arm rests are provided as part of the seat, the grip portions may be disposed inwards of those arm rests.

The user can hold the grip portion or portions to take some of their weight when preparing to stand from or sit on the seat squab. This makes it safer and easier to make the weight transfer to or from their feet, particularly when the user is frail. Ensuring that the grip portion(s) rise vertically, or substantially vertically and forwards, allows the user to keep hold of the grips without those grips 'falling away' as the chair is raised and (optionally) tilted forwards. Preferably, the grip portions are kept at around the same height relative to the rear seat squab portion whether the seat is raised or lowered. A footrest may be provided below the seat squab. In the seated configuration, the footrest may be movable between stowed and deployed positions. This allows the user to rest their feet on the surface of the footrest, when deployed (i.e. raised). Movement of the footrest may be electrically powered. The footrest may be a conventional footrest. Preferably, the footrest includes a deployment mechanism in accordance with the fifth aspect of the invention. On operation of the mechanism, the footrest may be automatically stowed prior to movement of (or separation of) the seat squab portions.

A control may be provided for operating the mechanism. This allows an occupant of the seat to move it to a standing position when required, or for a person who wishes to sit in the seat to lower it from the standing position once they have transferred some of their weight to the rear seat squab portion. The control may be physically connected to the mechanism, or may be a remote control. The control may be integrated into the seat, to avoid its inadvertent loss or misplacement. The control may allow operation of the footrest and/or back rest, if either or both are provided.

The rear seat squab portion and one or both of the back rest and the grip portion(s) may be moveable as a unit during operation of the mechanism. This allows synchronised (or contemporaneous) movement and tilting of the rear portion, the grip portions and/or the back rest, whilst approximately maintaining their relative positions.

The mechanism for moving the seat squab portions may include a moveable platform connectable to or engageable with the rear seat squab portion. This can cause the rear seat squab portion to separate from or converge with the front seat squab portion during operation of the mechanism. Preferably, when the seat squab portions are separated during use, the mechanism is adapted to move the platform without substantially changing its tilt.

When moving the seat from a seated position to a standing position, the moveable platform may initially not connect or engage the seat squab. This allows both seat squab portions to move together when initially raised. During the transition to the standing position, the moveable platform can bear against the rear seat squab portion, changing its trajectory relative to the front seat squab portion. Continued operation of the mechanism further raises the platform, which ideally keeps the rear seat squab portion at a relatively constant tilt angle. This keeps a substantial component of the user's weight acting through their buttocks and the rear seat squab portion until they are ready to transfer their weight to their legs and stand up.

The mechanism may be a powered lift mechanism. The seat may include a supporting structure. The lift mechanism may comprise:

a first support for the seat squab, the first support having a pivotal connection to a front region of the supporting structure for changing the tilt angle of the first support; a second support for the rear seat squab portion, the second support being pivotally connected to a rear region of the first support, for changing the tilt angle of the second support relative to the first support, and moveable to a region higher than the first support;

an actuator adapted to move the first and second supports;

a control for operating the actuator; and

a lifter engageable with the second support above a predetermined tilt angle of the first support, and adapted to pivot the second support relative to the first support, for in use separating or bringing together the seat squab portions.

The seat may comprise a cover for covering the mechanism. The cover may comprise: a flexible sheet connected at a first end to a back of the powered seat, and connected at a second end to one or more points below the first end,

support means for holding the sheet substantially taut, and

sheet distribution means adapted to redistribute the flexible sheet during operation of the mechanism, for maintaining substantial coverage of the mechanism irrespective of the position of the mechanism.

The seat may comprise a base, an axle and at least one wheel mounted about the axle, and a slot provided through the base, the axle being located in the slot, the slot including a first axle receiving area where the axle is loosely retained, and a second axle receiving area where the axle is restrained against upward movement and the at least one wheel supports the weight of the powered seat, the weight of the powered seat maintaining engagement of the axle in the second receiving area.

The seat may comprise a retractable footrest. The footrest may include deployment means for moving the footrest, and a mechanical linkage comprising

first and second links of substantially equal length, which are pivotally connected to the footrest by joints at different positions,

a third link pivotally connected to each of the first and second links by joints, to connect the first and second links together, and

a fourth link pivotally connected to each of the first and second links by joints, to connect the first and second links together, the fourth link being parallel to the third link and displaced from the third link along the first and second links, each of the third and fourth links crossing the first link and connecting to the second link at one end, and being adapted for connection to the seat at another end, and the extent of each of the third and fourth links between the first and second links being substantially the same, enabling the first and second links to remain substantially parallel in operation.

The powered seat may be provided as part of a chair. For example, it may be fitted to or integrated into a seat or chair. Existing seats and chairs can be retrofitted with the powered seat, and newly manufactured seats and chairs can include the powered seat.

According to a second aspect of the present invention, there is provided a powered lift mechanism for a seat squab of a chair, the seat squab including front and rear portions, and the chair including a supporting structure, the lift mechanism comprising

a first support for the seat squab, the first support having a pivotal connection to a front region of the supporting structure for changing the tilt angle of the first support;

a second support for the rear seat squab portion, the second support being pivotally connected to a rear region of the first support, for changing the tilt angle of the second support relative to the first support, and moveable to a region higher than the first support;

an actuator adapted to move the first and second supports;

a control for operating the actuator; and

a lifter engageable with the second support above a predetermined tilt angle of the first support, and adapted to pivot the second support relative to the first support, for in use separating or bringing together the seat squab portions.

When provided with or as part of a chair, the powered lift mechanism substantially eases the transition between seated and standing positions for a person who might otherwise find the motion strenuous.

During movement from the seated position to the standing position, there are two distinct phases in the transition. Initially, both supports and thus both parts of the seat squab are moved together, rising and tilting forwards. Then, the lifter (for example, a cam) comes to bear against the second support, which in turn bears against the rear seat squab portion. This leads into the second phase of the transition, where the supports and their associated seat squab portions are separated. Thereafter, the rear seat squab portion is moved independently of the front portion, and the rear portion maintains a relatively constant tilt angle (unlike the front portion).

In other words, if the seat portions separate at a predetermined tilt angle of x°, then for support tilt angles closer to the vertical than this, the second support is kept tilted at approximately the same angle as it was when the seat portions separated. Higher tilt angles are steeper as described in the specification, i.e. more vertical, unless specifically described otherwise.

The lifter essentially counter-pivots the second support relative to the first, as the first support continues to pivot about the front of the supporting structure. This creates a Z- shaped arrangement of the two supports, the lifter, and the remainder of the supporting structure (if viewed side-on). Pivoting of the first support tilts the front seat squab portion forward, but the lifter counteracts further forward tilt of the second support as the first support is tilted towards the vertical, thus keeping the rear seat squab portion at around the same tilt angle as at the point of separation of the supports and seat squab portions.

When the actuator has moved the supports to a standing configuration, the rear portion is higher than the front portion, and minimal effort is required on the part of the user to shift their weight completely onto their legs. The rear portion may be moved over the top of the front portion.

The predetermined tilt angle at which the supports separate or converge may be between substantially between 75° and 90°. Preferably, the predetermined tilt angle is approximately 85° to the vertical. The second support may be disposed at an angle of substantially between 70° and 85° to the vertical when engaged with the lifter. Preferably, the angle of the second support is substantially 78° to the vertical, when the actuator is in the standing configuration. The first support may tiltable to an angle substantially between 15° and 45° to the vertical. This keeps the second support (and therefore the rear seat squab portion) relatively horizontal, so that the seat occupant does not accidentally slide or slip off that portion when the mechanism has moved the seat squab portions into their raised positions.

The supports may be tilted at different angles in the standing configuration. The angle of the first support controls the tilt angles of both seat squab portions when they are adjacent and not separated, but only affects the tilt angle of the front seat squab portion when the supports and seat squab portions are spaced apart. The second support controls the angle of the rear seat squab portion, after engaging and separating that rear portion from the front portion. Since the second support and lifter keep the rear portion at a substantially unchanged angle, the angles of the seat squab portions can change independently. The supports may be tiltable forward by extension of the actuator. The supports may be both moveable upward and tiltable forward by extension of the actuator.

The supports and lifter may together be adapted to enable the rear seat squab portion to separate from or converge with the front seat squab portion during operation of the powered lift mechanism.

The lifter may be pivotally connected to a rear region of the support. Preferably, the lifter is pivotally connected about an axis parallel the pivotal connection of the support. Alternatively, the lifter may be provided separately to the support, for example moved by the actuator (or a separate actuator) at a rate which engages or disengages the second support at a given height of the supports.

When the supports are spaced apart during use, the second support may be movable without substantially changing its tilt. In other words, the lifter may be adapted to pivot the second support in an opposite direction to pivoting of the first support. This substantially maintains the tilt angle of the second support despite increased tilt of the first support. This helps to ensure that the user remains stably seated during the second phase of the transition, rather than sliding off if the tilt angle of the second support also continued to increase. In side profile in the standing configuration, the supports have an approximately Z- shaped conformation, relative to a horizontal plane of the frame. In other words, the second support is the upper bar of the Z conformation, the first support is the diagonal bar of the Z conformation, and part of the frame is the lower bar of the Z conformation.

The powered lift mechanism is preferably provided as part of (or integrated into) a seat or chair having a seat squab with discrete front and rear portions. The portions should be arranged to corresponding to the positions of the relevant mechanism components, and can thus be moved independently by the mechanism.

The chair may further include a back rest. There may be a reclining mechanism for moving the back rest between reclined and upright positions. The control may be adapted to use the reclining mechanism to bring the back rest substantially upright prior to moving the seat squab portions. This has the same benefits as described with respect to the first aspect of the invention.

The chair may include a retractable footrest with a deployment mechanism for moving the footrest between stowed and deployed positions. Preferably, the footrest accords to the fifth aspect of the invention. The control may be adapted to use the deployment mechanism to stow the footrest prior to moving the seat squab portions. This has the same benefits as described with respect to the first aspect of the invention.

According to a third aspect of the present invention, there is provided a chair comprising a seat squab lifting mechanism, and a cover for covering the lifting mechanism, the cover comprising

a flexible sheet connected at a first end to a back of the chair, and connected at a second end to one or more points below the first end,

support means for holding the sheet substantially taut, and

sheet distribution means adapted to redistribute the flexible sheet during operation of the lifting mechanism, for maintaining substantial coverage of the lifting mechanism irrespective of the position of the lifting mechanism. The cover hides the mechanism from sight for improved aesthetics, but also avoids children easily reaching into the mechanism, for example, where they could trap their fingers. Advantageously, redistribution of the sheet occurs essentially in tandem with operation of the lifting mechanism, so that manual intervention to rearrange the sheet is not necessary. In other words, redistribution of the sheet is a passive process, occurring as a result of the transition of the chair into a new configuration.

The sheet may have a length substantially similar to the vertical height of the lifting mechanism from the ground in the standing configuration. This ensures the lifting mechanism remains covered regardless of its position or configuration.

The sheet may be integrated into the back of the chair. For example, the sheet may form an outer layer of the back of the chair. The first and second ends may be connected along axes which are substantially parallel. This avoids rucking in the sheet.

There may be at least two bars arranged across the back of the chair, and the sheet may be passed around the bars. This can hold the sheet relatively taut, rather than having it pooled under the chair in the seated configuration, for example. Where the bars contact the sheet, they preferably have a low coefficient of friction. The bars may be provided substantially parallel to each other and to the ends of the flexible sheet. The flexible sheet may pass around an underside of one bar and a top of the other bar for forming a pulley system.

Providing bars across the rear side of the chair supports formation of a pulley system. Substantially frictionless interaction between the bars and sheet is preferred to avoid wear on the sheet, through repeated raising and lowering of the chair, and thus rubbing of the sheet against the bars. The sheet may, instead of the bars (or additionally to them), include a material having a low coefficient of friction. By arranging the sheet in an elongated "S", as part of a pulley system, raising or lowering the chair inherently redistributes the sheet as needed to maintain coverage of the lift mechanism of the chair. Redistribution of the sheet is done relative to the positions of the bars, since the sheet passes around them. This means that a fixed length of sheet can be used. This fixed length covers the mechanism in both seated and standing configurations, despite the standing configuration having an increased area requiring coverage.

The second end of the sheet may be connected below the first end using a resilient sprung connection, thus linking the second end of the cover to the one or more points. The end of the sheet can therefore move in response to the seat being raised, which pulls the upper end of the sheet upwards. Neglecting extensibility of the sheet, this pulls on the lower end of the sheet. By having the lower end connected to an extendible connection, the connection adopts the needed extension so that the sheet can be of fixed length but still redistributed to the degree required in order to maintain coverage of the lift mechanism, when in the standing configuration.

There may be a third bar connected to the upper bar about the flexible sheet. The third bar may include a resilient sprung connection for connection to a point above the upper and third bars. Alternatively, the upper bar may have a resilient sprung connection at its ends, connected to the chair.

This allows the ends of the flexible sheet to each be fixed in place, and for the distribution or shape of the sheet to be changed relative to the back of the chair. The sheet passes between the upper and third bars, or just around the top of the upper bar if no third bar is provided. Raising the chair pulls the top end of the sheet upwards as the back of the chair rises, which correspondingly extends the spring(s) in the connection to allow the sheet to adopt a new arrangement. Where bars are provided, one or more of them may each include a roller. Each roller may extend along and be rotatable about its respective bar. This minimises friction wear on the flexible sheet by aiding its redistribution via rotation of the rollers, instead of passing over static surfaces. It will be appreciated that, whilst the cover is predominantly described with respect to the transition of a chair from a seated configuration to a standing configuration, the reverse transition substantially restores the cover to its original arrangement in the seated configuration. The lifting mechanism in the chair may accord to the second aspect of the invention.

According to a fourth aspect of the present invention, there is provided a wheeled chair comprising

a base, an axle and at least one wheel mounted about the axle, and a slot provided through the base, the axle being located in the slot,

the slot including a first axle receiving area where the axle is loosely retained, and a second axle receiving area where the axle is restrained against upward movement and the at least one wheel supports the weight of the chair, the weight of the chair maintaining engagement of the axle in the second receiving area.

The axle may be movable between the axle receiving areas by tilting the base about an axis parallel to and displaced from the axle. The chair can be quickly and easily converted between rolling and static arrangements by tilting it forwards or backwards, to position the axle and wheels in the first or second area as desired. There is no foot-operable lever for locking the wheels against rotation, and so no trip hazard for a person walking in the vicinity of the chair. In other words, the mechanism for conversion between rolling or static arrangements of the axle is self- contained, so that there is nothing protruding from the base. This is particularly helpful if used in a nursing/care home, for example.

The axle receiving areas may be at different ends of the slot. The first axle receiving area may be disposed higher than the second axle receiving area.

There may be two slots of the same shape and provided at the same relative position on opposite sides of the base.

The at least one wheel may be located inside the base for concealment, which is more aesthetically pleasing.

Each end of the slots may face upwards in use. In other words, part of the base will provide a reaction force from above when in contact with the axle. This is minimal when the axle is in a longer portion or length of the or each slot (i.e. the first axle receiving area), since the wheels are floating, but substantial when the axle is in a shorter portion or length of the slot (i.e. the second axle receiving area) and the wheels are load-bearing. The or each slot may have a substantially U-shaped, V-shaped or J-shaped cross- section.

Using J-shaped slots, for example, supports conversion of the base between load- bearing and non-load-bearing configurations. Tilting the base on the ground at an angle about one end moves the wheels into a short length of the J slot, and levelling the base then traps the axle in that length so that the wheels engage the ground to the exclusion of other parts (when the base is substantially horizontal). To revert to the non-load- bearing configuration of the wheels, the base can be tilted on the ground in the opposite direction to the original tilt about the other end, and then levelled again, so that the axle is disposed in the longer length of the J slot.

The support frame may include feet which ground the base when the wheels are in the floating configuration. The feet may be made of rubber or another high grip material. This prevents accidental sliding of the chair on a smooth floor, e.g. wood floor. The feet may be provided in corners of the frame. The feet may be adjustable to level the base in a conventional manner. For example, the feet may each be linked to the base via screw-threaded connections.

According to a fifth aspect of the present invention, there is provided a retractable footrest for a chair, the footrest comprising deployment means for moving the footrest, and a mechanical linkage comprising:

first and second links of substantially equal length, which are spaced apart and pivotally connected to the footrest by joints at different positions,

a third link pivotally connected to each of the first and second links by joints, to connect the first and second links together, and

a fourth link pivotally connected to each of the first and second links by joints, to connect the first and second links together, the fourth link being parallel to the third link and spaced apart from the third link along the first and second links, each of the third and fourth links crossing the first link and connecting to the second link at one end, and being adapted for connection to the chair at another end, and

the extent of each of the third and fourth links between the first and second links being substantially the same, enabling the first and second links to remain substantially parallel in operation.

This type of footrest mechanism is much improved over existing chairs with scissor- type linkages. The mechanical linkage in the present invention ensures that the angle at which the footrest is deployed more closely matches the hinge point of a typical person's legs about their knees, so that the footrest itself remains substantially flat against their calves during deployment. This improves comfort, and is less likely to cause injury such as bruising in an elderly user, for example. The deployment means may comprise an actuator (or an extendible arm). The actuator may be arranged to deploy the footrest when extended, and to retract the footrest when contracted. Using an actuator allows the footrest to be deployed or retracted to a custom position, so that the footrest can be comfortably positioned according to individual requirements.

A control may be provided and connected to the actuator for use in deploying and retracting the footrest. Where the control is an electronic control, it minimises the effort required on the part of the user to stow the footrest. There may be two of the mechanical linkages, each connected to the footrest. Preferably, the linkages are provided at either end of the footrest. This provides stability to the footrest when supporting a user's feet, so that the load is between the linkages and does not tilt the footrest to one side. Alternatively, one mechanical linkage could be disposed centrally relative to the footrest, and connected to either side of the centre of the footrest.

One or both of the first and second links may be non-linear. One or both of the first and second links may include a bend at the respective joints where they connect to the fourth link. One or both of the third and fourth links may be non-linear. One or both of the third and fourth links may include a bend at the respective joints where they connect to the first link.

The ends of the third and fourth links may be pivotally connected to the chair at different positions. The third and fourth links may connect to the chair at positions forward (relative to the chair) of the joints connected the various links together. The footrest may be provided as part of a chair.

According to a sixth aspect of the invention, there is provided a chair comprising one or more of:

a powered seat according to the first aspect of the invention;

a powered lift mechanism according to the second aspect of the invention, and optionally a cover according to the third aspect of the invention;

a wheeled chair according to the fourth aspect of the invention;

a retractable footrest according to the fifth aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

Figure 1 A shows a front view of an embodiment of a chair with a powered seat, in a seated configuration;

Figure IB shows a side view of the chair of Figure 1 A, at a stage of transition between seated and standing configurations;

Figure 1C shows a side view of the chair of Figure 1A, at a further stage of transition between seated and standing configurations; Figure ID shows a front view of the chair of Figure 1 A, in a standing configuration;

Figure 2 shows a perspective view of an embodiment of a seat lifting mechanism and a footrest deployment mechanism for a chair;

Figure 3A shows a side view of the lifting mechanism of Figure 2 in a seated configuration;

Figure 3B shows cutaway side view of Figure 2, hiding some foreground components for clarity, illustrating a portion of the lifting mechanism;

Figure 3C shows a side view of the lifting mechanism of Figure 3 A transitioning between a seated configuration and a standing configuration; Figure 3D shows a cutaway side view of Figure 3C, illustrating the lifting mechanism portion shown in Figure 3B;

Figure 3E shows a side view of the lifting mechanism of Figure 3 A further transitioning between a seated configuration and a standing configuration;

Figure 3F shows a cutaway side view of Figure 3E, illustrating the lifting mechanism portion shown in Figures 3B and 3D;

Figure 3G shows a side view of the lifting mechanism of Figure 2 in a standing configuration;

Figure 4 A shows a side view of a powered armchair with a lifting mechanism, in a standing configuration; Figure 4B shows a perspective view of a seat squab of the powered armchair of Figure 4A, transitioning between seated and standing configurations;

Figure 5 A shows a side view of the footrest deployment mechanism of Figure 2 in a stowed position; Figure 5B shows a side view of the footrest deployment mechanism of Figure 5 A transitioning between stowed and deployed positions; Figure 5C shows a side view of the footrest deployment mechanism of Figure 5 A in a deployed position;

Figure 6 A shows a perspective view of parts of a cover for a lifting mechanism of a chair;

Figure 6B shows a side view of a first type of mechanism for the cover of Figure 6A;

Figure 6C shows a side view of a second type of mechanism for a cover similar to that of Figure 6 A;

Figure 7A shows an underside perspective view of a wheeled chair base; and

Figure 7B shows a second underside perspective view of the wheeled chair base of Figure 7A.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figures 1 A to ID, an embodiment of a chair with a powered seat is indicated generally at 1. The chair 1 includes a seat squab with a movable front portion 2a and a movable rear portion 2b. The chair 1 also includes a back rest 3, side panels 4, grip portions 5, and a footrest 6. One of the grip portions 5 has an in-built controller or electronic device 5a. The grip portions 5, back rest 3 and seat squab are connected together to move as a unit, independently of the rest of the chair. A powered lift mechanism (not shown) is included in the chair 1, and described later with respect to Figures 2 to 3G.

The chair 1 is shown in a seated configuration in Figure 1 A and is shown in a standing configuration in Figure ID. Intermediary stages in the transition between these configurations are shown in Figures IB and 1C. The transition is effected via the controller, which operates the lift mechanism.

In the seated configuration, upper surfaces of the seat squab portions 2a, 2b are substantially aligned to provide a single support surface, as seen in Figure 1 A. The lift mechanism initially raises and pivots forward both of the seat squab portions 2a, 2b, along with the back rest 3 and grip portions 5. At a particular elevation, the rear seat squab portion 2b separates from the front portion 2a. One means of doing this is described in detail for Figures 2 to 3G.

The front portion 2a is rotated forwards, whilst the rear portion 2b, back rest 3 and grip portions 5 remain at around the same tilt angle as when the rear portion 2b separated from the front portion 2a. The rear portion 2b, back rest 3 and grip portions 5 are moved forward during elevation. In the standing position, the height of the rear portion 2b has approached hip height for the user. The rear portion 2b is angled forward no more than 20 degrees, whilst the front portion 2a is angled through nearly 90 degrees and is closer to the vertical. A gap 2c is created by virtue of separation of the seat squab portions 2a, 2b. Referring to Figure 2, an embodiment of a powered lift system for moving parts of a chair is indicated generally at 10. For clarity, elements of a chair such as a seat squab are not shown attached to the system 10. However, it will be appreciated that the chair includes a seat squab amongst other features, for example as described earlier for Figures 1 A to ID, and later with respect to Figures 4A and 4B.

The system 10 has two main configurations (or positions). The first configuration is a seated configuration, where the system 10 and associated seat squab are arranged suitably for a person to sit in the chair. The second configuration is a standing configuration, where the system 10 and associated seat squab are arranged for supporting a person in a nearly upright stance. Figure 2 shows the seated configuration of the system 10.

The system 10 is powered by a power source (not shown). Mains power is used in this embodiment. The system 10 can use batteries in an alternate embodiment, or can use a combination of mains and battery power. Typically, a transformer and any other required electronics can be housed in space beneath the chair, as required.

The powered system 10 includes a frame as a support structure, indicated generally at 12. The frame 12 has various elements for supporting parts of the chair, and supports the seat squab in a position above the ground. The frame 12 includes a base with feet 12b connected to respective side elements 12c. In this embodiment, there are two side elements 12c at either side of the frame, and two feet 12b at ends of the respective side elements 12c. The feet 12b are connected to the side elements 12c via conventional screw-threaded connections in this embodiment. Bars 12d are connected to and extend upwards from each of the side elements 12c, for connection to side portions of the chair (not shown). Support sections 12e are provided inwardly of each side element 12c.

The frame 12 includes three actuators (or extendible arms) 14, 16, 18, which are used to control movement of different elements of the system 10 as described below. All three actuators 14, 16, 18 are electrically powered in this embodiment.

The first actuator 14 is part of a footrest deployment mechanism. This is later described in detail with respect to Figures 5A to 5C. Ends of the first actuator 14 are connected to front and rear cross elements 14a, 14b. The rear cross element 14b is connected to the frame 12 in this embodiment. The front cross element 14a forms part of a footrest support for a cushion, extendible forward relative to the frame 12. The first actuator 14 is arranged so that it extends in a plane substantially parallel to the side elements 12c. In this embodiment, first actuator 14 is angled upwardly from the rear cross element 14b to the front cross element 14a.

The second actuator 16 is part of a back rest control mechanism for reclining the back of the chair. The degree to which the second actuator 16 is extended affects the recline angle of the back of the chair. Brackets 20 are provided on either side of the frame 12. The back of the chair can be attached to the brackets 20. Arms 22 extend forwards from the respective brackets 20. The second actuator 16 is arranged so that it extends in a plane substantially parallel to the side elements 12c. The second actuator 16 is connected to one of the bracket-arm pairs 20, 22. Specifically, a lower end of the second actuator 16 is connected to the base of one of the arms 22, around the level of the side elements 12c in the seated configuration of the system 10. An upper end of the second actuator 16 is connected to a lower portion of the bracket 20 paired with that arm 22. The second actuator 16 is arranged to extend from the base of its connected arm 22 upward to the bracket 20.

The arms 22 each include an attachment region 22a for connection of a grip portion (not shown). The arms 22 are also each indirectly connected to the third actuator 18 via the frame 12. This allows the grip portions to be raised and lowered together with the remainder of the chair.

The third actuator 18 is part of a seat lifting mechanism. This mechanism is needed to move the chair between seated and standing configurations. The third actuator 18 is arranged so that it extends in a plane substantially parallel to the side elements 12c. A front cross element 18a is provided between the support sections 12e at the front of the system 10. A lower end of the third actuator 18 is pivotally connected to the front cross element 18a.

A moveable support 26 for the seat squab is connected to the support sections 12e. The support 26 is open in the middle to allow extension of the third actuator 18 therethrough. The connections need to be sufficiently robust for bearing the weight of a person sitting in the chair, atop the seat squab (not shown). The support 26 is pivotable via extension of the third actuator 18. In this embodiment, a front edge of the support 26 is approximately at a pivot axis of the support 26. A rear cross element 18b is provided as a rear edge of the support 26. An upper end of the third actuator 18 is connected to the rear cross element 18b.

A moveable platform (or second support) 28, for lifting the rear portion of the seat squab, is pivotally connected on part of the seat squab support 26. The platform 28 is disposed in the rearward half of the support 26, atop the support 26. In this embodiment, the platform 28 is formed from two separate parts, on either side of the support 26. Each part of the platform 28 includes front and rear side projections for engaging and moving a rear portion of a seat squab independently of a front portion of the same seat squab. The support 26 and platform 28 are each moveable via extension or contraction of the third actuator 18. Movement of the support 26 by the third actuator 18 is guided by the pivotable frontal connection of the support 26, and guide elements 26a which connect the support 26 to the frame 12.

It will be appreciated that the mechanism can be used to effect transitions of the system 10 from either of the seated and standing configurations to the other. It will also be appreciated that, for successful operation of the third actuator 18 and seat lifting mechanism, the seat squab of the chair must be provided in two separable front and rear portions. This is of course not essential for other elements of the system 10, such as the footrest deployment mechanism.

Input by a user to effect the transition from being seated to standing, or from standing to being seated, is done via the controller. In some embodiments, the controller may have input means for controlling other parts of the chair, e.g. a back rest or footrest. The controller is connected to the actuators 14, 16, 18 for manually controlling them. A processor is included in the controller to electronically limit operation of the actuators 14, 16, 18 relative to each other. In this embodiment, this prevents the chair from being raised to a standing position before the footrest has been stowed and the backrest has been moved upright. Seat lifting mechanism

Referring to Figures 3 A to 3G, the seat lifting mechanism is shown at various stages of its operation. In Figure 3A, a seated configuration of the system 10 is shown. The actuator 18 is in a contracted position. The support 26 and platform 28 are both disposed at an angle of around 113° to the vertical. In other words, the support 26 and platform 28 both slope rearwards, towards the back of the chair. The brackets 20 and arms 22 for the grip portions also slope rearwards. It will be appreciated that the seat squab atop the support 26 and platform 28 may not have uniform thickness, and so that apparent slope of the seat squab may not match the slope of the support 26 and platform 28 in the seated configuration. The same point is equally applicable to the grip portions attached to the arms 22. Figure 3B shows the system 10 in the same configuration as Figure 3 A. On the near side, a cam (or lifter) 30 is pivotally connected to the support 26 via pivot 30a. The cam 30 is also connected to a tie rod 32 (visible in Figure 3A, hidden in Figure 3B), which is connected to the front of the system 10. A similar cam and tie rod arrangement is provided on the other side of the system 10 for bearing against the other part of the platform 28. It will be appreciated that, if the platform 28 is provided as one contiguous component, a single cam and tie rod may be used to effect raising and lowering of the platform 28 and associated rear seat squab portion. It will be appreciated that, in place of a cam or lifter, any suitable lifting means can be used to engage the platform (or second support) 28 at a given tilt angle or given height thereof.

Figure 3C shows the seat lifting mechanism at an intermediary stage between the seated and standing configurations, with the third actuator 18 partially extended. In this embodiment, the support 26 and platform 28 have together been raised to a tilt angle of 86° from the vertical. The arrangement of the cam 30 and tie rod 32 relative to the support 26, particularly the respective pivot points, enable the cam 30 to rotate relative to the support 26 when the third actuator 18 is operated. When transitioning into the standing configuration, this corresponds to the cam 30 coming into contact with the platform 28. In use, the cam 30 essentially counter-pivots about an axis substantially parallel to the pivot axis of the platform.

Figure 3D shows the cam 30 is at substantially the same angle as the platform 28 at the stage illustrated in Figure 3C, and is now in contact with the platform 28. The front- most arm 22 is hidden for clarity. A tie rod 32' for a cam on the far side (not shown) is visible. The brackets 20 are each in a substantially upright position, and so the back of the chair is also substantially upright. Figure 3E shows the seat lifting mechanism at an intermediary stage between the seated and standing configurations, with the third actuator 18 extended slightly further relative to the arrangement in Figure 3C. The platform 28 has been raised and separated from the support 26 by the cam 30. This occurs before the transition to the standing configuration is complete. This consequently causes the rear seat squab portion to separate from and become raised relative to the front seat squab portion. In this embodiment, the support 26 has now pivoted to a tilt angle of 80° from the vertical. In contrast, due to the cam 30, the platform 28 has remained at approximately the same angle as before separation, now at 85° from the vertical.

Figure 3F shows the cam 30 is supporting the platform 28 at the stage illustrated in Figure 3E. The arm 22 on the far side is visible, and as in Figure 3E, the attachment region 22a of each arm 22 is being raised during the transition. At full extension of the third actuator 18, the system 10 reaches its standing configuration as shown in Figure 3G. Whilst the support 26 is now angled at 33° from the vertical, the platform 28 is angled at 78° from the vertical. This ensures that the tilt angle of the rear seat squab portion is not substantially different from its tilt angle at the point of separation from the support (which was 86° from the vertical). An approximate Z-arrangement of the platform 28 and support 26 relative to the frame is also visible. The angle of the rear seat squab portion therefore remains suitable for providing continuing support to the seated user until they choose to stand independently of the chair. The footrest remains stowed as in the other Figures 3 A to 3F, and is neither deployable in this configuration, nor during the transition between configurations.

As shown in Figure 3G, the front edge of the support 26 has not moved forward relative to the remainder of the system 10 in this embodiment. Of course, due to the thickness of a front seat squab portion on the support 26, that portion may jut forward slightly relative to the seated configuration. Furthermore, the platform 28 has moved forward relative to its initial position (in the seated configuration) of the system 10. Both of these features help the seat to closely mimic human anatomical requirements since, in standing up, a user's knees remain in substantially the same position as when seated, but their hips move upwards and forwards relative to their knees, in order to subsequently support their own weight. The manner in which this transfer happens in the user's body is thus closely approximated by the system 10 to provide an effective aid for standing up from or sitting down in a chair including the system 10.

Referring also to Figures 4A and 4B, an embodiment of an armchair with a powered seat is indicated generally at 110. The features and operation of the powered seat is substantially similar to the system 10 described with respect to Figures 3A to 3G. Additional features are now described.

The armchair 110 includes a back rest 112, a rear seat squab portion 114a adjacent to the back, and a front seat squab portion 114b forward of the rear seat squab portion 114a. The portions 114a, 114b may equivalently be referenced as rear and front seat segments respectively. The back rest 1 12 is reclinable in the seated configuration, and on operation of the mechanism, the back rest 112 is brought substantially upright prior to moving the seat squab portions 114a, 114b. The back rest is not reclinable in the standing configuration of the chair 110. The back rest moves upwards or downwards at the same time as the rear seat squab portion during operation of the mechanism.

The portions 114a, 114b are each cushioned. In this embodiment, the front cushion 114b is rotated to overlie the front of the footrest in the standing configuration. The portions 114a, 114b are shown as separate (or non-contiguous) support surfaces, spaced apart from each other in the standing configuration illustrated in Figure 4A. It will be appreciated that, in the seated configuration, the portions 114a, 114b form a substantially uninterrupted support surface in a common plane, suitable for sitting on. However, in the standing configuration, the rear portion 114a is a separate tier supporting a person's buttocks, rather than the full length of their thighs, which is only possible in combination with the front portion 114b. In other words, the front and rear portions 114b, 114a are disposed in different planes in the standing configuration of the system 10. The rear portion 114a has a flexible projection 116, and the front portion 114b has a correspondingly shaped recess 118. The projection 116 and recess 118 abut one another in the seated configuration, providing a substantially coplanar support surface. The projection 116 is shaped in the form of an overhang to allow it to lift free from the recess 118 when the chair transitions into the standing configuration. An underside of the projection 116 is angled rearwards at around 45 degrees in this embodiment.

A tether 120 is connected at one end along the projection 116. The other end of the tether is connected in a region below the projection 116. When the chair 110 is approaching the standing configuration, the tether 120 is pulled taut before full extension of the third actuator 18. This in turn exerts a downward force on a front edge of the projection 116. The projection 116 is deformable, being a cushion, and this deforms the overhang, causing the front edge to become firmer. Consequently, when the user decides to stand up and exerts a force on the rear portion 114a and projection 116, less of the applied force compresses the cushion, making it easier to stand up. In some embodiments, the tether 120 includes a stretchable material, to tension the front edge gradually.

The size and angle of the underside of the projection 116 is selected to maximise the effectiveness of this deformability. In some embodiments, it is preferable to have the underside of the projection 116 angled in the range 30° to 60°. This angle affects the relative depth of the projection 116. A steeper angled projection 116 gives a firmer support, since the edge of the projection 116 being deformed is closer to the main body of the rear seat portion. Therefore the degree of support required can be tailored or customised for a given user by providing seat squab portions with a suitably sized and angled projection 116 for the rear seat squab portion, and correspondingly shaped/angled complementary dock or recess in the front portion.

In some other embodiments, the material of or within the rear seat squab portion can be selected to provide a firmer or softer support. For example, a denser material would provide firmer support. The material may be provided at portions of the projection which provide support during the process of a person standing up. Other portions of the seat squab can be made of another less firm/dense material. This allows the seat squab to provide full support where needed during movement of the seat squab, and in a raised configuration, but ensures that the seat squab is comfortable to sit on when provided in a seated arrangement.

Grip portions 122 are provided on either side of the chair 110. These portions 122 move upwards or downwards at the same time as the back rest and rear seat squab portion 114a, during operation of the mechanism. In this embodiment, the rear seat squab portion 114a approaches the same height as the grip portions 122 in the standing configuration of the chair. This corresponds to the approximate position of a person's hands relative to their buttocks when in a standing position, with their arms by their sides, making it more comfortable to use their arms to assist in standing up. It will be appreciated that the transition of the chair 110 between configurations is a multi-phase sequence. For the transition to the standing configuration of the chair 110 (from the seated configuration), the controller is used to initiate the ascension sequence. First, the support 26 is pivoted forward via the third actuator 18, raising both portions of the seat squab at the same time. The cam 30 then engages the platform 28, and raises the rear portion 114a independently of the front portion 114b. The tilt angle of the portions 114a, 114b thus also become independent of one another. Further extension of the third actuator 18 continues to pivot the support 26, whilst the platform 28 does not tilt substantially further. The platform 28 is translated both further upwards and forwards relative to the frame after separation from the support 26, until the third actuator 18 reaches its maximum extension. Part of the platform 28 comes to lie over the front of the support 26. In other words, the rear seat squab portion is substantially above the front seat squab portion in the standing configuration, or substantially vertically overlies it.

In the standing configuration of this embodiment, an upper surface of the rear seat squab portion is tilted forwards around 10° from the horizontal. In contrast, an upper surface of the front seat squab portion is tilted forwards around 57° from the horizontal. In other embodiments, the tilt angle of the front portion may be greater or lesser than this.

For the transition to the seating configuration (from the standing configuration), the above steps operate in reverse. The third actuator 18 contracts, lowering the platform 28 and moving it rearwards. The support 26 is also rotated rearwards, and the platform 28 comes into contact with the support 26, before then reaching the seated configuration at a minimum extension of the third actuator 18. This allows the seat squab portions 114a, 114b to converge. The seat squab in the embodiments described is divided (or bisected) into front and rear portions. The size and shape of the divided or bisected parts do not need to be the same. It will be appreciated that the dimensions of the chair 110, including the seat squab portions 114a, 114b, the height of the chair 110, and the footrest and back rest 112, may be customised for a particular user, depending on their height or the length of their legs, for example.

It will also be appreciated that the term 'chair' is used to broadly mean any seat suitable for a person to sit on. This includes armchairs, settees, sofas and stools, as well as seats in vehicles (such as cars, buses, planes and trains), amongst others. The powered seat may be built into a new chair, or retrofitted to an existing chair.

It will further be appreciated that the above description has been made to describe the core features of the invention, and that that an exhaustive description of the supporting framework has not been undertaken. The exemplary illustrations in the Figures show one exemplary embodiment of a framework suitable for enabling different aspects of the present invention. The framework may be adapted as needed to suit a particular size or shape of seat or chair.

Footrest deployment mechanism

Referring now to Figures 2 and 5 A to 5C, an embodiment of a deployment mechanism for a chair footrest is indicated generally at 210. It will be appreciated that, in the following description, the mechanism is used in both deploying a footrest from a chair and retracting or stowing a footrest back into a chair. As with Figure 2, elements of the chair to which the mechanism 210 belongs are omitted for clarity.

A footrest support 212 is provided at the front of the chair. A footrest cushion (not shown) is attached to the front of the support 212. The first actuator 14 is connected to the support 212. Extension of the actuator 14 deploys or retracts the support 212 and footrest cushion. The mechanism 210 further includes two substantially identical mechanical linkages which connect the support 212 to the frame 12. Each mechanical linkage includes parallel first and second links (or bars) 214, 216. In the linkage visible in Figures 5A to 5C, the links 214, 216 are the same length. Each of the links 214, 216 is connected to the support at one end via different respective pivots 214a, 216a. Equivalent links 214, 216 are shown in Figure 2 on the other side of the footrest support 212. The links 214, 216 are spaced apart from each other by a distance, to allow space for rotation during deployment/storage of the footrest.

Parallel third and fourth links (or bars) 218, 220 each connect to the first and second links 214, 216 at different respective pivots (or joints) 222. The third link 218 is pivotally connected at one end 218a to the adjacent support section 12e. The third link 218 is pivotally connected at another end to an end region of the second link 216. The third link 218 crosses and is pivotally connected at a point along its length to the first link 214.

The fourth link 220 is pivotally connected at one end 220a to the adjacent support section 12e. The fourth link 220 is pivotally connected at another end to a mid-region of the second link 216. The fourth link 220 crosses and is pivotally connected at a point along its length to the first link 214.

Note that the pivots for the upper ends of the third and fourth links 218, 220 are the only pivots which rotate but do not translate (relative to the frame) when the footrest mechanism is operated. The remaining pivots and joints all undergo rotation and translation during deployment or retraction of the footrest.

The first and second links 214, 216 each have straight lengths, parallel with each other, extending away from the support 212 towards the rear of the chair. At the joints 222 with the fourth link 220, both of the first and second links 214, 216 become angled (or bend) further towards the horizontal, whilst remaining straight and mutually parallel.

The third and fourth links 218, 220 each have straight lengths, parallel with each other, extending downwardly at an angle from the support section 12e. At the joints 222 with the first link 214, both of the third and fourth links 218, 220 become angled (or bend) further towards the vertical, remaining substantially mutually parallel. After the respective curved sections, the third and fourth links 218, 220 continue with straight, parallel lengths until connecting to the second link 216 at respective joints 222, 222' . Joints 222 oppose each other, as do joints 222'. This arrangement connects the first and second links 214, 216 together, so that they remain mutually parallel irrespective of the state of deployment of the footrest. The region defined by the four joints 222 and associated lengths of the links 214, 216, 218, 220 forms a parallelogram when viewed side-on. This is equivalent to the linkages being oriented in a plane substantially parallel to the side elements 12c. It will be appreciated that the exact arrangement may be a special form of parallelogram such as a rhombus.

In use, from a stowed position of the footrest, the first actuator 14 is extended via operation of a controller. The actuator 14 bears against the footrest support 212 via an arm 224, and moves it forward from the chair. In Figure 5C, the maximum angle of the footrest support 212 is 53° from the vertical, sloping from the chair down towards the ground. It will be appreciated that other embodiments of the footrest may provide for other maximum slope angles, depending on the properties of the linkages, and within the limitations of the parallelogram arrangement.

The path along which the footrest support 212 and attached cushion moves and pivots is determined by the mechanical linkages. The joint 222 between the second and third links 216, 218, i.e. the distal joint 222, limits the motion of the second link 216 relative to the first link 214. In particular, it limits the degree and rate of separation of the opposing joints 222', and mediates pivoting of the first and third links 214, 218 about its opposing joint 222. This controls the angle of the footrest as it is deployed via the mechanism, so that it is deployed about an axis that runs approximately along the front edge of the seat squab of the chair, and thus the axis is approximately coincident to the hinge axes of the knees of a person seated normally in the chair.

Further operation of the controller to retract the footrest moves the footrest back towards the chair and into a stowed position. If a footrest mechanism is incorporated in a chair having a seat lifting mechanism, the footrest is automatically stowed (if deployed) prior to operation of the seat lifting mechanism.

It will be appreciated that the controller in this embodiment is electronic, and electronically connected to the actuator 14 which controls deployment of the footrest. However, in other embodiments, the controller may be a conventional manual release lever connected to a corresponding spring-loaded mechanism for deploying the footrest, with one or more mechanical linkages as described above. To retract the footrest from a deployed position, suitable downward force can be exerted by the user's legs, and a conventional retention or latch mechanism used to secure the footrest in a stowed position.

Cover for the seat lifting mechanism

Referring mainly to Figures 6A to 6C, an embodiment of a cover for a seat lifting mechanism of a chair is indicated generally at 310. The schematics of the cover are for clarity shown in isolation from most component parts of a chair and the seat lifting mechanism.

The cover 310 is at one end connected to a back rest 312 of the chair. In this embodiment, the connection is stitching. However, it will be appreciated that other conventional means of connecting the cover are possible, and that the cover may be integrated into the back rest itself. In this embodiment, the cover 310 is connected along one edge 310a to a mid-region of the back rest 312. In other embodiments, the connection may be at the top or bottom of the back rest 312. The cover 310 includes a flexible sheet 314. The sheet 314 is made from a fabric material in this embodiment. It will be appreciated that the sheet 314 can be made from other suitable materials, plastic for example. The sheet 314 covers a seat lifting mechanism at the rear of a chair. The sheet 314 can be redistributed to maintain coverage of that mechanism whether the seat is in a lowered (seated) configuration, or in a raised (standing) configuration. The length of the sheet 314 is greater than the vertical distance between its connection to the back rest 312 and the ground.

With reference to Figure 6B, one mechanism for redistributing the sheet 314 includes a spring 316. A lower end of the sheet 314 is connected to a region below the back rest 312 by the spring 316. The spring 316 is resilient and is connected to the frame 12 of the chair in this embodiment of the mechanism.

Bars are provided at different heights between the spring 316 and back rest 312. In this embodiment, the bars include cylindrical rollers 318, 320 which engage the sheet 314. Each roller 318, 320 is substantially horizontal and connected to parts of the frame 12 across the chair; see Figure 4 A, for example. The rollers 318, 320 are also substantially parallel to the ends of the sheet 314a. The lower roller 318 is displaced further rearwards than the upper roller 320. The rollers 318, 320 each have smooth surfaces.

Each roller 318, 320 can rotate on its longitudinal axis to minimise wear on the sheet 314 during redistribution of the sheet 314. This essentially corresponds to rotation about the respective bar. The sheet 314 passes around an underside of the lower roller 318, and around a top side of the upper roller 320. This creates a pulley system.

From a seated configuration of the chair, operation of the seat lifting mechanism moves the back rest 312 upwards, pulling on the sheet 314. The sheet 314 is pulled taut and the spring 316 is then extended by virtue of the same pulling force. As the chair and back rest 312 continue to rise, the sheet 314 passes around each roller 318, 320 and stretches the spring 316 accordingly, until the chair is in the standing configuration. The redistributed sheet still shrouds the lifting mechanism from view, and from direct facile access without moving the sheet 314 aside. This occurs as a passive operation by virtue of the elevation of the chair via the lifting mechanism. Lowering the chair in the reverse operation to the seated configuration allows the spring 316 to relax and contract to its default length. This keeps the sheet 314 relatively taut as the chair is lowered. The cover maintains substantial coverage of the back of the chair without covering the sides and/or front seat portion of the chair. The length of the sheet 314 is selected so that, in the standing configuration, the spring 316 is not sufficiently extended to meet the upper roller 320. It will be appreciated that the spacing between the rollers 318, 320 affects the length of sheet 314 required.

In some embodiments, one of the rollers can be rigidly connected to and moveable with the back rest 312, when the lifting mechanism is used to raise or lower the chair. This may be the roller furthest rearwards on the chair, which in the current embodiment is the lower roller 318. This affects the rate of sheet redistribution, but the sheet 314 still maintains substantial coverage of the lifting mechanism. With reference to Figure 6C, another mechanism for redistributing the sheet 314 is shown. The mechanism is similar to the mechanism of Figure 6B, but differs as follows.

The mechanism of Figure 6C includes a resilient spring 316, connected to a pair of upper rollers 320, 322. The rollers 320, 322 are connected together by brackets (not shown) at either end. The spring 316 connects to the brackets. A lower end of the sheet 314 is connected to a region below the back rest 312. A lower roller 318 is also provided. The sheet 314 passes around a lower side of the lower roller 318, and between the pair of upper rollers 320, 322.

Again, from a seated configuration of the chair, operation of the seat lifting mechanism moves the back rest 312 upwards, pulling on the sheet 314. The sheet 314 is fixed at both ends, so redistribution of the sheet 314 requires movement of the pair of rollers 320, 322 in this embodiment. As the fixed upper end of the sheet is pulled upwards with the back rest, the sheet 314 is pulled taut and a downward pull is exerted on the pair of upper rollers 320, 322. This causes extension of the spring 316, as the rollers 320, 322 are pulled downwards. The sheet 314 is relatively inextensible so that the spring 316 is stretched in preference to the sheet 314. Lowering the chair in the reverse operation to the seated configuration allows the spring 316 to relax and contract to its default length. This again keeps the sheet 314 relatively taut as the chair is lowered.

It will be appreciated that the spring is not limited to being a coil spring, for example. Rather, the spring is any resilient, elastically deformable connection between the sheet and a point or region below the back rest.

The sheet may be extensible in some embodiments, in which case the sheet is pulled taut and then passes around the rollers as above, with the extension being by virtue of stretching of the sheet. In such embodiments, the sheet is only stretched to an extent that allows it to remain within its elastic limit.

Note that Figures 6A to 6C are schematics only, and that the relative dimensions of the sheet 314 and spacing between the rollers 318, 320, 322 may not be to scale. Wheeled chair base

Referring to Figures 7 A and 7B, an embodiment of a wheeled chair base is indicated generally at 410. The base 410 can be connected under, or incorporated into, a chair (not shown).

The base 410 includes a frame 412 and a surface (or platform) 414 for connection to a chair. The surface 414 is fixed to the frame 412 by fixing means, such as screws. The outer edges of the surface 414 extend beyond the outer edges of the frame 412. In this embodiment, the surface 414 is substantially rectangular.

The frame 412 includes four feet 412a for bearing the weight of a chair and user when a chair is immobile on the ground. The feet 412a are adjustably connected to the frame 412 via screw-threaded connections. The feet 412a are provided at corners of the frame 412.

Axle supports 416 are spaced apart from each other on two opposing sides of the frame 412. The supports 416 each include a J-shaped slot 416a. This means that a cross- section of each slot 416a has a 'J' shape. An axle 418 is mounted through each of the slots 416a, orthogonal to the sides of the frame 412 connected to the axle supports 416. Two wheels 420 are provided on the axle 418. The wheels 420 have a diameter substantially less than the height of the surface 414 above the ground, when the base 410 is on the ground. This ensures that the wheels can be fully accommodated in the frame 412 and beneath surface 414.

In other embodiments, substantially slots of U-shaped cross-section can be used. One terminus of each U shape needs to lie closer to the surface than the other, and the wheels 420 need to be of sufficient diameter to be load-bearing at the lower termini, but non- load-bearing at the upper termini of those U shapes.

Each J-shaped slot 416a has a first closed end (or terminus) 417a and a second closed end (or terminus) 417b. The ends 417a, 417b are 'closed' with respect to the axle 418, so that the axle 418 cannot exit the slots through those ends. There is a path for the axle 418 to pass from one of the ends 417a, 417b to the other, along the J shapes of the slots 416a. In this embodiment, the path in each slot 416a includes a horizontal lengthjoined at either end to different vertical lengths leading to the respective ends 417a, 417b. Each first end 417a is nearer the surface 414 than its respective second end 417b. In other words, each first end 417a is higher than the corresponding second end 417b in use, relative to the ground. When the axle 418 is located in the portion of the J shapes under the first ends 417a and a load is applied, the axle 418 is a floating axle and the wheels 420 are not load-bearing, and the axle 418 can retreat towards first end 417a and the surface 414. In this case, the feet 412a are load-bearing and support the chair on the ground.

When the axle 418 is located in the portion of the J shapes under the second ends 417b and a load is applied, the axle 418 engages the second ends 417b and the wheels 420 cannot fully retreat towards the surface 414. This means that the wheels 420 become load-bearing, rather than the feet 412a, in a rolling configuration of the base 410.

The slots 416a are provided at the same relative distance from the front of the base 410. The slots 416a mirror each other across the frame 412 so that the axle 418 remains substantially orthogonal to the aforementioned sides of the frame 416 when moved between the termini of the slots 416a. The slots 416a are provided in parallel planes in this embodiment.

The slots 416a are arranged vertically. In other embodiments, the slots may deviate from the vertical, but should be sufficiently vertical to avoid impeding movement of the axle between the termini of the slots 416a.

In use, the feet 412a support the chair and base 410 on the ground when the chair is not being moved. In this embodiment, the base is oriented so that the first ends 417a are closest to the front of the chair, and the second ends 417b are closest to the back of the chair.

To put the base 410 (and axle 418) into a rolling configuration, the base 410 is tilted rearwards about the two feet 412a at the rear of the chair. This corresponds to tilting about an axis substantially parallel to the axle 418. The axle 418 passes along the slots 416a away from the first ends 417a, and towards the second ends 417b. The base 410 is then levelled out to trap the axle 418 at the second ends 417b by the applied load of the base and chair, making the wheels 420 load-bearing on the ground. The chair can then be wheeled to a new position in a room.

Once in the new position, the base 410 is tilted forwards about the two feet 412a at the front of the chair. This corresponds to tilting about another axis substantially parallel to the axle 418, but on the other side of the axle 418. The axle 418 passes back along the slots 416a away from the second ends 417b, and towards the first ends 417a. The base 410 is levelled out, and the axle 418 returns to a floating configuration.

The axle 418 is at the first ends 417a in the floating configuration in this embodiment, but the first ends 417a may be disposed higher than the axle 418, as long as the wheels can be enclosed by the frame 412 and surface 414 without becoming load-bearing.

It will be appreciated that the base 410 may be connected in another orientation in other embodiments. For example, the base 410 may be connected in an orientation which is rotated 180° relative to the embodiment described, so that the base 410 enters the rolling configuration when tilted forward. In this case, the base 410 would need to be tilted forwards to enter the rolling configuration, and tilted rearwards to subsequently revert to the floating configuration.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.