GB2418846A

GB2418846A - Chair incorporating a mechanism to assist rising

Info

Publication number: GB2418846A
Application number: GB0520394A
Authority: GB
Inventors: Alfred William Arthurs
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-10-07
Filing date: 2005-10-07
Publication date: 2006-04-12
Also published as: GB0520394D0; GB0422205D0

Abstract

A chair (100) incorporates a mechanism which may assist a user to rise from the chair. The chair (100) comprises a back (106), a seat (108) and a base (102), wherein the back (106) is attached to the seat (108) at a hinge (110). The mechanism comprises an actuation means, a piston (118) and at least one guide track provided in the base (102). The actuation means is arranged to cause the piston (118) to act on at least one of the seat (108), the hinge (110) or the back (106). The piston (118) is capable of moving the back (108) and the seat (108). The guide track (104) is arranged to control the movement of the seat (108) and the back (106) and the spatial relationship between the seat (108) and the back (106). Also disclosed is a method of assessing a person with physical handicap and determining a preferred relationship to be maintained between parts of the chair while the person rises.

Description

241 8846

CHAIR INCORPORATING MECHANISM TO ASSIST RISING

The present invention relates to a chair incorporating a mechanism to assist rising. In particular, but not exclusively, the invention relates to a chair to assist a physically impaired person to rise from a seated to a standing position.

It will be appreciated that, in various groups within the population, rising from a seated position presents a considerable challenge. In particular, the elderly, infirm or physically disabled often require assistance provided either by a carer or with the use of additional apparatus, for example lifting slings. It will be appreciated that requiring assistance results in a loss of independence, can result in injury to the carer or the subject of the assistance, and takes time, effort and frequently skill in operating any additional apparatus.

Such disadvantages led to the development of chairs which tilt to assist a person seated therein to stand. Most commonly, these chairs are hinged at the front of the chair and are powered by electricity or a hand operated lever to operate a piston situated to the rear of the seat. This lifts the rear of the seat and the back together, maintaining a fixed angle between the seat and the chair back. The user of such a chair is forced to lean forward by the chair back, which makes rising awkward.

An attempt to address this problem is seen in EP 0 780 110, in the name of Le Couviour SA, which discloses a two-piston arrangement powered by a motor or electricity and arranged to pivot a chair around a point to the front of the seat and a point joining the seat to the chair back. However, the arrangement is mechanically complex and places significant load on one of the cylinders.

According to a first aspect of the present invention, there is provided a chair incorporating a mechanism to assist the rising of a user of the chair, the chair comprising a back, a seat and a base, wherein the back is attached to the seat at a hinge, the mechanism comprising an actuation means, a piston and at least one guide track provided in the base, wherein said actuation means is arranged to cause the piston to act on at least one of the seat, the hinge or the back, the piston is capable of moving the back and the seat and the guide track is arranged to control the movement of the seat and the back and the spatial relationship between the seat and the back.

The seat may be hinged to the back at a rear seat edge and is adapted to pivot about a point substantially along the opposing front seat edge. This allows the angle between the seat and the back to vary as the seat is lifted and lowered. It also ensures that the force assisting the user to rise is applied at or around the back of the knees, so that the user does not need to rely on the use of their leg muscles or feet in order to rise.

The chair may further comprise a runner attached to the seat and/or back and arranged to run within the guide track. The runner may comprise a roller. This may be advantageous as it provides a strong, mechanically simple arrangement. Preferably the runner is attached to the back at a point remote from the hinge between the back and the seat. This may provide a compact arrangement whereby the size of the base and the stroke of the piston are kept to a minimum.

Advantageously, the piston comprises a pneumatic piston. This may be advantageous as such pistons are mechanically simple, safe and capable of providing the lifting force required. The piston may alternatively comprise a hydraulic piston.

Advantageously, the actuation means is manually operable. This may be convenient as no power source is required.

The actuation means may comprise a hand and/or foot pump. These provide mechanically simple methods of inputting manual power.

The actuation means may be arranged to be operable by a patient seated in the chair. This may be advantageous as it means that the patient does not suffer from a loss of independence. Alternatively or additionally, the actuation means may be operable by a person assisting a patient. This may be advantageous as the person assisting may be more physically able than the patient.

The chair may comprise a power source and said actuation means may be arranged to use the power source. This may be advantageous as the loads involved in moving the chair may be large.

The power source may comprise an on-board power source. The on-board power source may be one or more of the following: a battery, a gas tank, a petrol tank, an oil tank or some other fuel source. Providing an on- board power source may be convenient as the chair need not be attached to an external power source and may therefore be readily relocated.

Alternatively, the power source may be an external power source, for example, mains electricity. This is advantageous as such a source need not be recharged or refuelled.

Preferably, the power source is protected from ingress of moisture. This may be convenient as the chair can then be used for example in a shower cubicle. Indeed, in a preferred embodiment, most or all of the components of the chair are made from water resistant materials.

The guide track may comprise one of the following shapes: an arc, for example a quarter circle arc, a diagonal, some other shape. The arc may arc from bottom to top in a clockwise manner, or may be an "inverted" arc that arcs from bottom to top in an anticlockwise manner. The use of one of these shapes may be advantageous as the shape of the guide track will affect the relationship between the seat and the back during actuation of the mechanism. This means that a guide track of a particular shape may be suited to a person with a particular disability.

The base may comprise at least one side and the guide track may comprise a cut-out portion of one or more of said sides. In a preferred option the base comprises two opposing sides adapted in use to be positioned perpendicular to the surface on which the chair stands.

Preferably a cut-out portion is provided in both sides.

Advantageously, the chair comprises at least one arm. This may make the chair more comfortable to a user.

In some embodiments, the or each arm comprises an adjustment means which is arranged to allow the arm to be adjusted between a first position, wherein said arm is substantially perpendicular to the seat, and a second position, wherein at least a portion of the arm is substantially parallel to the seat. This may be advantageous as in the second position, the arm forms a surface which can be used as a table and/or a 'slide plate' to assist in moving a person from the chair to, for example a bed or wheelchair.

The adjustment means may comprise a hinge. This may provide a mechanically simple means of moving the arm between the first and the second position.

Preferably, the chair comprises wheels. This may be convenient in assisting relocating the chair, and indeed a person seated therein. The wheels may comprise casters and may comprise ball casters. Such casters are convenient as they are strong enough for the intended purpose and a chair comprising such casters may be easy to steer than a chair incorporating disc-shaped trolley wheels.

In what is perhaps a preferred embodiment, the wheels comprise a locking mechanism arranged to lock the wheels. Such wheels therefore have an open state, in which they are free to move, and a locked state, in which they are locked in a stationary condition by the locking mechanism. This may prevent the chair from being moved unintentionally.

Further, the chair may be arranged such that the actuation means may not be actuated unless the wheels are in the locked state. This may be advantageous as, when the mechanism is actuated, the force on the chair due to the weight of a person will become directed towards the back of the chair rather than towards its base; unless the wheels are locked, the chair may roll away from a user at that time, causing them to lose balance.

The locking mechanism may comprise a pneumatic, hydraulic, a magnetic, electric, or manually operable locking mechanism. These provide mechanically simple means for locking the wheels.

The chair may additionally comprise a handle. This may be advantageous as it may assist in relocating the chair.

In a preferred embodiment, the handle comprises one of the following: a bar across the back of the chair, a vertical handle on the back of the chair, two vertical handles positioned to either side of the back of the chair. Such embodiments may be convenient as the chair may be readily steered and tilted, for example to pass over thresholds, by such a handle.

The chair may additionally comprise a seatbelt. The seatbelt may be arranged to pass over the chest and/or waist of a person seated in the chair. This may be advantageous in supporting a person seated in the chair, particularly during actuation of the mechanism.

The chair may further comprise at least one safety bar extending from the at least one arm. This may provide extra support for a person whilst the chair is in use. Preferably there is provided at least one moveable safety bar extending between two arms, and a locking mechanism arranged to lock the safety bar. Such a bar has an open state, in which it can be moved to allow a person to vacate the chair, and a locked state, in which it is locked in a stationary condition by the locking mechanism. This may provide extra security for a person whilst allowing for convenient access or exit.

Preferably, the chair further comprises a foot or leg rest. This may be advantageous as it adds to the comfort of a user of the chair. The foot or leg rest may be adjustable such that the angle of the legs of a person seated in the chair in relation to the seat may be adjusted. This may be advantageous as some physical conditions require the legs to be elevated.

Further, a person using the chair may be more comfortable with elevated legs. Also, the legs may be kept elevated for all or part of the rising motion.

The foot rest may comprise two sections wherein the position of each of said sections is independently variable. This may be advantageous to prevent the foot rest impeding a person during the rising process.

The chair may further comprise a foot or leg rest actuation means, arranged to power the movement of the foot or leg rest. The foot or leg rest actuation means may comprise the actuation means described above or may be a separate actuation means. If a separate foot or leg actuation means is provided, it may take the form of the actuation means described above.

The chair may additionally comprise a head rest. The height of the head rest may be adjustable. This may add to the comfort of a person sitting in the chair.

According to a second aspect of the present invention, there is provided a method of assisting the rising from a chair of a person with predetermined physical limitations comprising determining the preferred relationship between the body parts of that person during rising and controlling the parts of the chair to maintain the preferred relationship during an assisted rising process.

This may be advantageous as the needs of persons with certain disabilities are not met with a mechanism to assist the rising of a person with a different disability. For example, a person with hip trouble requires different support from a person with back trouble.

The method may comprise providing a chair according to the first aspect of the invention and choosing the shape of the guide track according to the physical limitations of the intended user.

Embodiments of the invention are now described by way of example only and with reference to the accompanying Figures, of which: Figure 1 shows a chair according to a first embodiment of the present invention in a first configuration; Figure 2 shows the chair of Figure 1 in a second configuration; Figure 3 shows a schematic diagram of a pneumatic system for use in an embodiment of the present invention; Figures 4a and 4b show a ball caster for use with an embodiment of the present invention in an open and closed state respectively; Figure 5 shows a front view the chair of Figure 1 in a finished form; Figure 6 shows a back view the chair of Figure 1 in a finished form; Figure 7 shows a second embodiment of a chair according to the present invention in a first configuration; Figure 8 shows a second embodiment of a chair according to the present invention in a second configuration; Figure 9 shows a third embodiment of a chair according to the present invention in a first configuration; Figure 10 shows a third embodiment of a chair according to the present invention in a second configuration; Figure 11 shows a fourth embodiment of a chair according to the present invention in a first configuration; Figure 12 shows the fourth embodiment of a chair according to the present invention in a second configuration;.

As is shown in Figures 1 and 2, one embodiment of the present invention comprises a chair 100 which moves between the first configuration shown in Figure 1 and the second configuration shown in Figure 2. The chair 100 comprises a chair base 102 which is a substantially u-shaped structure comprising support plates on two opposing sides and a base all made from sheet aluminium. Each of the side support plates has cut therefrom a guide track 104 which forms an arc-shaped hole in the plate.

Housed within the base 102, there is a substantially vertical chair back frame 106 and a seat frame 108, both of which are substantially rectangular and made of sheet aluminium, reinforced with ribs on the underside so that weights of up to around 25 stone may be supported thereby. Once the back frame 106 and the seat frame 108 are upholstered, they form the back and the seat of the chair respectively.

The seat frame 108 comprises, when positioned for use, a back edge, a front edge and two side edges extending there between. The back frame 106, when positioned for use, has a bottom edge and a top edge and two side edges extending there between. The back edge of the seat frame 108 is attached to the back frame 106 at a hinge 110 running the width of the seat frame 108 at approximately a midpoint of the length of the back frame 106 (as will be appreciated from the ensuing description, the point to which the seat is attached may not be a mid point but should be approximately the length of the seat frame 108 from the base of the back frame 106). Towards the bottom edge on two sides of the back frame 106 there is a runner 112 arranged to project beyond the plane of the back frame 106 in a direction perpendicular to the plane of the back frame 106. The runners 112 are each arranged to run within a guide track 104 such that the movement of the back frame 106 and therefore the seat frame 108 is constrained.

The chair 100 further comprises a leg rest 114, comprising a substantially vertical portion against which a person's calves will rest when seated in the chair 100, at the base of which there is a substantially horizontal portion projecting away from the chair 100 on which the person's feet will rest. The rest 114 further comprises a substantially horizontal portion at the top of the vertical portion, projecting towards the chair 100 and fixed in a region of the front edge of the chair seat frame 108 at a hinge 116, about which hinge 116 both the rest 114 and the seat frame 108 can rotate. The hinge 116 is fixed in relation to the base 102 and is arranged such that the angle between the seat frame 108 and the vertical portion of the rest 114 can be altered, in particular such the rest 114 can be raised to elevate the feet of a person sitting in the chair (which may be for comfort or for medical reasons) and also such that the angle of the seat frame 108 with respect to the base 102 can be altered.

The chair 100 further comprises a rod-and-cylinder pneumatic piston 118.

The piston 118 is housed within the base 102 and mounted to a lower region of its frame at a hinge 120 which allows the piston 118 to pivot from the base of its cylinder in a vertical plane. The rod of the piston 118 is connected to a central region of the seat frame 108. The arrangement is such that, in use of the lifting mechanism, the piston 118 acts to raise the back frame 106 and the back edge of the seat frame 108, increasing the minor angle between the back frame 106 and the seat frame 108 whilst the runners 112 run up the guide tracks 104 and the seat frame 108 moves around the hinge 116. The back frame 106 remains substantially vertical and moves forward in relation to the base 102. The rest 114 remains in substantially the same position with respect to the base 102, although the angle between the rest 114 and the seat frame 108 will change.

The chair 100 further comprises four wheels in the form of ball casters 122, at each lower corner of the base 102. The casters 122 are described in greater detail below in relation to Figures 4a and 4b.

The chair 100 further comprises an actuation means comprising a pneumatic system 300 mounted on the back frame 106 (as shown in Figure 6), which is now described with reference to Figure 3. The system comprises a lever 302 attached to a compressor 304 which is fitted to a selector valve 306. The selector valve 306 has two major positions of operation, the first to operate the piston 118 on the chair 100 and the second to control the casters 122. When positioned to operate the piston 118, the selector valve 306 can be positioned such that the seat frame 108 is lowered, i.e. the ram retracts into the cylinder, or raised, i.e. the ram extends, by operation of the lever 302. The lever 302 is arranged to be moved in a reciprocating manner and operates as any conventional pump to pass air through the compressor 304.

In alternative embodiments, the pneumatic system may comprise a foot pump, for example positioned on the base of the back of the chair 100 and a selector valve also positioned on the back of the chair lOO.

With references to Figures 4a and 4b, the casters 122 each comprise a ball 402, preferably a 2-inch rubber ball housed within a plastic cup 404.

The cup 404 comprises an open end and a closed end is shaped such that the ball 402 can be received entirely within the cup 404, but can also protrude from the open end of the cup 404 without being able to pass though the open end. The casters 122 further comprise a pressure chamber 406 which comprises an air inlet point 408, a spring 410 and is bounded by a moveable plate 412 and the inner walls of the closed end of the cup 404. The chamber 406 is arranged such that when air is supplied though the air inlet point 408, the chamber 406 expands by moving the movable plate 412 away from the closed end of the cup 404. The spring 410 also acts to move the plate 412 away from the closed end of the cup 404 and expands with the chamber 406. The moveable plate 412 acts on the ball 402 such that, when the spring 410 is expanded, the ball 402 is forced to protrude though the open end of the cup 404 and the casters 122 are in an open state free to roll. When the spring 410 is contracted, the ball 402 is contained entirely within the cup 404 and the casters 122 are in a locked state, i.e. not free to roll. The chamber 406, in conjunction with the pneumatic system 300 therefore comprises a locking mechanism.

When selector valve 306 is positioned to operate the casters 122, the pneumatic system 300 can act to supply air through the inlet point 408 and expand the chamber 406, thereby allowing the chair 100 to roll on the casters 122. The selector valve 306 can also be positioned to allow the chamber 410 to vent under the weight of the chair, bringing the open ends of the cups 404 into contact with the floor and preventing the chair from being rolled. The pneumatic system 300 is controlled by air valves arranged such that the piston 118 may not be operated unless the casters 122 are in a locked state.

In alternative embodiments, the casters 122 may be mounted on pneumatic cylinders such that their height, and therefore the height of the chair can be altered. In such embodiments, the chair 100 may comprise blocks in each corner which rest on the ground, stabilising the chair, when the pneumatic cylinders are exhausted and are held above the ground when air is supplied to the cylinders.

Figures 5 and 6 show the chair 100 upholstered and ready for use. The chair 100 has been covered in padding and a removable, washable fabric.

A seat belt 500, similar to the seatbelt of a car, has been added to secure a person in the chair 100. The chair 100 further comprises a handle by way of a pair of handles 600 attached to the back frame 106 and which extends across the width of the back frame 106 to the rear of the chair 100 and which enables the chair 100 to be rolled by a person standing behind the chair 100.

In alternative embodiments, the seat belt 500 may take other forms and may, for example, comprise support straps arranged to support either side of the upper body of a person seated in the chair 100.

In use, the chair 100 may be operated as follows. First, a patient is seated on the covering over the seat frame 108 with their back against the covering of the upper portion of the back frame 106, with the piston 118 fully retracted and the balls 402 of the casters 122 protruding from the cups 404. The seatbelt 500 is fastened and the chair 100 can be rolled by a person pushing against the handles 600.

The selector valve 306 is then moved to allow the chamber 410 of the casters 122 to vent under the weight of the chair, bringing the open end of the cups 404 into contact with the floor and preventing the chair 100 from being rolled.

The selector valve 306 is then moved to a position such that the chair 100 may be raised and the lever 302 is moved in a reciprocating manner (usually by an assistant to the patient), causing air to enter the pneumatic system 300 and push the ram out of the cylinder of the piston 118. The end of the ram acts on the seat frame 108 raising the back frame 1()6 and the back of the seat frame 108, increasing the minor angle between the back frame 106 and the seat frame 108 whilst the runners 112 run up the guide tracks 104, the seat frame 108 rotates around the hinge 116 and the piston 118 rotates about its hinge 120. The back frame 106 remains substantially vertical and moves forward in relation to the base 102. The seat frame 108 tilts upwards towards the back and a patient seated thereon is supported against their back and thighs as they are raised into a standing or near standing position. The rest 114 remains in substantially the same position with respect to the base 102, although the angle between the rest 114 and the seat frame 108 will change. The seat belt 500 may then be unfastened and the patient may move away from the chair 100.

The operation may be carried out in reverse to allow a supported sittingdown movement by moving the selector valve 306 to the position such that reciprocating the lever 302 causes the piston 118 to retract. The casters 122 may then be operated by the pneumatic system 300 such that the balls 402 protrude beyond the open ends of cups 404 and the chair 100 may be rolled.

Some other embodiments, or variations on the above embodiment are now described with reference to Figures 7 to 10.

Figures 7 and 8 show an embodiment of a chair 100' similar to that shown in Figures 1 and 2. Like parts are labelled with like numbers and will not be explained in detail. However, the guide track 104' is, in this embodiment, a linear diagonal track. This means that, as the piston 118 operates to raise the chair, the back frame 108 inclines away from the vertical to the rear of the chair 100', i.e. a patient sitting within the chair lOO' is leant back as the chair 100' is raised, as shown in Figure 8.

This may be useful to patients with poor balance, weak muscles, Parkinson's disease and/or humpedfarched backs.

Further, as shown in Figure 7, the leg rest 114 has been rotated about the hinge 116 to assume an elevated position. The leg rest 114 is locked into position such that a person may rest their legs on the rest 114 while seated in the chair 100'.

Figures 9 and 10 shown an embodiment of a chair 100" similar to that show in figures 1 and 2 like parts are labelled with like numbers. In this embodiment, the chair incorporates one 'standard' arm 900 and one folding arm 902. The folding arm 902 comprises a solid plate-like member incorporating an adjustment means in the form of a piano hinge 904. The hinge 904 is arranged to run parallel to the plane of the seat frame 108 and perpendicular to the plane of the back frame 106, approximately level with the top of the seat (i.e. the upholstered seat frame 108). In Figure 9, the folding arm 902 is shown in a first position, wherein said arm 902 is substantially perpendicular to the seat frame 108 and the back frame 106. In the first position, the folding arm 902 is arranged such that a patient sitting in the chair can rest their forearm on the arm 902.

Figure 10 shows the folding arm 902 in the second position, wherein the folding arm 902 is folded about the hinge 904. A portion of the arm 902 is substantially parallel to the plane of the seat frame 108. The folded portion forms a platform, extending in the plane of the seat frame 108 away from the side of the chair 100". The folding arm 902 may be used as a table or a 'slide plate' to assist in moving a physically incapacitated person into a wheel chair or bed. In some embodiments, the arm may be arranged to rest on on the edge of the chair, bed, etc to which a person is moving as the hinge 904 may not then need to be sufficiently strong to support the weight of a person.

In this embodiment, the hinge 904 is rotated using manual pressure, being resistant or stiff to remain in set positions. In alternative embodiments, a catch or some other locking means may be used to maintain the arm in the first and/or second position.

The chair 100" further comprises a head rest 502, which may be raised or lowered to suit a person seated in the chair.

In alternative embodiments, an arm may comprise a hollow box-like structure with a lid. The arm may contain a tray for example for eating off or may provide storage space.

Figures l1 and 12 show an embodiment of a chair 101 similar to that shown in Figures 1 and 2. Like parts are labelled with like numbers and will not be explained in detail. However, the guide track 104" is, in this embodiment, an inverted arc. This means that, as the piston 118 operates to raise the chair, the back frame 108 inclines away from the vertical to the rear of the chair 101, i.e. a patient sitting within the chair 100' is leant back as the chair lot is slightly raised, as shown in Figure 12, ending in a reclined position. This may be useful to patients who wish to recline in a chair, for example to rest. The leg rest 114 could then be raised to add to their comfort.

The skilled person will appreciate that elements described or illustrated in relation to one embodiment may be relevant to other embodiments.

Claims

1. A chair incorporating a mechanism to assist the rising of a user of the chair, the chair comprising a back, a seat and a base, wherein the back is attached to the seat at a hinge, the mechanism comprising an actuation means, a piston and at least one guide track provided in the base, wherein said actuation means is arranged to cause the piston to act on at least one of the seat, the hinge or the back, the piston is capable of moving the back and the seat and the guide track is arranged to control the movement of the seat and the back and the spatial relationship between the seat and the back.

2. A chair according to claim 1 wherein the piston comprises a pneumatic piston.

3. A chair according to claim 1 wherein the piston comprises a hydraulic piston.

4. A chair according to any one of the preceding claims wherein the actuation means is manually operable.

5. A chair according to any one of the preceding claims wherein the actuation means comprises a hand and/or foot pump.

6. A chair according to any one of the preceding claims wherein the actuation means is arranged to be operable by a patient seated in the chair.

7. A chair according to any one of claims 1 to 5 wherein the actuation means is operable by a person assisting a patient.

8. A chair according to any one of claims 1 to 3, 6 or 7 when dependent on claims 1 to 3 wherein the chair comprises a power source and said actuation means is arranged to use the power source.

9. A chair according to claim 8 wherein the power source comprises an onboard power source.

10. A chair according to claim 9 wherein the on-board power source is one or more of the following: a battery, a gas tank, a petrol tank, an oil tank or some other fuel source.

11. A chair according to claim 8 wherein the power source is an external power source.

12. A chair according to claim 11 wherein the external power source is mains electricity.

13. A chair according to any one of claims 8 to 11 wherein the power source is protected from ingress of moisture.

14. A chair according to any one of the preceding claims wherein most or all of the components of the chair are made from water resistant materials.

15. A chair according to any one of the preceding claims wherein the guide track comprises one of the following shapes: an arc, a quarter circle arc or a diagonal.

16. A chair according to any one of the preceding claims wherein the base comprises at least one side and the guide track comprises a cut-out portion of one or more of said sides.

17. A chair according to any one of the preceding claims wherein the base comprises two opposing sides adapted in use to be positioned perpendicular to the surface on which the chair stands.

18. A chair according to claim 17 wherein a cut-out portion is provided in both sides.

19. A chair according to any one of the preceding claims wherein the chair further comprises a runner attached to the seat and/or back and arranged to run within the guide track.

20. A chair according to claim 19 wherein the runner comprises a roller.

21. A chair according to any one of the preceding claims wherein the chair comprises at least one arm.

22. A chair according to claim 21 wherein the or each arm comprises an adjustment means which is arranged to allow the arm to be adjusted between a first position, wherein said arm is substantially perpendicular to the seat, and a second position, wherein at least a portion of the arm is substantially parallel to the seat.

23. A chair according to claim 22 wherein the adjustment means comprises a hinge.

24. A chair according to any one of the preceding claims wherein the chair comprises wheels.

25. A chair according to claim 24 wherein the wheels comprise casters.

26. A chair according to claim 25 wherein the casters comprise ball casters.

27. A chair according to any one of claims 24 to 26 wherein the wheels comprise a locking mechanism arranged to lock the wheels.

28. A chair according to claim 27 wherein the chair is arranged such that the actuation means can not be actuated unless the wheels are in the locked state.

29. A chair according to either claim 27 or claim 28 wherein the locking mechanism comprises a pneumatic, hydraulic, a magnetic, electric, or manually operable locking mechanism.

30. A chair according to any one of the preceding claims wherein the chair additionally comprises a handle.

31. A chair according to claim 30 wherein the handle comprises one of the following: a bar across the back of the chair, a vertical handle on the back of the chair, two vertical handles positioned to either side of the back of the chair.

32. A chair according to any one of the preceding claims wherein the chair additionally comprises a seatbelt.

33. A chair according to claim 32 wherein the seatbelt is arranged to pass over the chest and/or waist of a person seated in the chair.

34. A chair according to any one of the preceding claims wherein the chair further comprises a foot or leg rest.

35. A chair according to claim 34 wherein the foot or leg rest is adjustable such that the angle of the legs of a person seated in the chair in relation to the seat may be adjusted.

36. A chair according to either claim 34 or claim 35 wherein the chair further comprises a foot or leg rest actuation means, arranged to power the movement of the foot or leg rest.

37. A chair according to claim 36 wherein the foot or leg rest actuation means comprises the actuation means of any one of claims 1 to 35 or is a separate actuation means.

38. A chair according to claim 37 wherein the separate foot or leg actuation means takes the form of the actuation means of any one of claims 1 to 35.

39. A chair according to any one of the preceding claims wherein the chair additionally comprises a head rest.

40. A chair according to claim 39 wherein the height of the head rest is

adjustable.

41. A chair according to any one of the preceding claims wherein the seat is hinged to the back at a rear seat edge and is adapted to pivot about a point substantially along the opposing front seat edge.

42. A chair according to either of claims 19 or 20 wherein the runner is attached to the back at a point remote from the hinge between the back and the seat.

43. A method of assisting the rising from a chair of a person with predetermined physical limitations comprising determining the preferred relationship between the body parts of that person during rising and controlling the parts of the chair to maintain the preferred relationship during an assisted rising process.

44. The method according to claim 41 further comprising providing a chair according to any one of claims 1 to 40 and choosing the shape of the guide track according to the physical limitations of the intended user.

45. A chair substantially as described herein and with reference to the accompanying Figures 1 to 12.

46. A method of assisting the rising from a chair of a person with predetermined limitations substantially as described herein and with reference to the accompanying Figures 1 to 12.