Chairs and seats – Rest for knee – leg – or foot – Connected to chair or seat for relative movement
Utility Patent
1998-02-19
2001-01-02
Barfield, Anthony D. (Department: 3636)
Chairs and seats
Rest for knee, leg, or foot
Connected to chair or seat for relative movement
C297S423400, C297SDIG003, C297SDIG004
Utility Patent
active
06168238
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to chairs, especially wheelchairs, and to attachments for such chairs.
BACKGROUND TO AND SUMMARY OF THE INVENTION
In essence, the present invention provides an active calf support, for a person sitting in a chair, i.e. a support which applies a pressure varying with time to regions of the calf, for stimulation of venous return in the lower limb. The applicants believe that such an active calf support has not previously been proposed.
Beds having a plurality of cushion members, e.g. transverse tubes, which are sequentially inflatable, are today well known. They are used for patients who are inactive or not sufficiently active to turn themselves regularly in bed, and who therefore run the risk of bed sores. The sequential inflation of the cushion members applies intermittent pressure to the skin, thereby reducing or preventing the formation of bed sores. An example of such a bed is the present applicants' GB-A-1595417. The present applicants have also sold active seats for particularly wheelchairs, which have a plurality of cushions members in the form of tubes extending from the front to the back of the chair, the chair carrying an air pump and a controller for sequentially inflating and deflating the tubes, as described in WO94/07396 and U.S. Pat. No. 5,277,414.
The present inventors have now realised that the provision of an active calf support will have beneficial effects for a person who is seated for long periods in a chair, such as a wheelchair. Because of the relative inactivity of such a person, and because they cannot easily exercise their legs, there is a tendency for poor circulation of the blood in the lower leg. The present invention provides means to ameliorate this, and particularly to stimulate venous return in the lower leg or lower legs.
It is mentioned that inflatable pads which are strapped around the calf are believed to be known, as also are boots containing inflatable pads which contact the lower leg. It seems that these are intended to be used by an active person, who desires massage of the muscles of the lower leg, and are intended to be used with the lower leg in a vertical position.
NL 7901599 discloses a chair with a tilting calf massaging cushion which is driven by a motor via an eccentric.
According to the present invention in one aspect, there is provided a chair having a seat and a calf support extending forwardly away from the seat, the calf support comprising a plurality of inflatable cushion members providing a support surface for at least one calf of a person sitting in the chair, the chair being provided with control means for inflating and deflating the cushion members in a predetermined sequence.
The cushion members may be any suitable size and shape. Tubes extending transversely to the direction of a leg of a person sitting in the chair (herein called “the forward direction”) are preferred. The cushion members are preferably in an array extending in the forward direction, and preferably there are at least three, more preferably at least four cushion members in the array in the forward direction. For practical reasons, relating to the construction of transverse tubes and the requirement for inflation and deflation, an array of four tubes in the forward direction is most suitable.
The length of each cushion member in the forward direction, e.g. the width of a tube whose longitudinal direction is transverse to the forward direction, is preferably in the range 40 mm to 100 mm, more preferably 60 mm to 100 mm.
When there are at least three cushion members in the array in the forward direction, the control means for sequentially inflating and deflating the cushion members is preferably arranged to inflate and deflate the cushion members in a sequence such that a pressure wave travels upwardly along the lower leg of the person sitting in the chair, i.e. towards the trunk of the person. The effect of inflation and deflation of the cushion members in itself stimulates venous return and improves muscle tone, by encouraging the normal physiological processes in the lower leg, and the provision of a pressure wave moving upwardly along the leg, may, it is thought, further encourage venous flow. Suitable control systems for inflating and deflating the cushion members in the desired sequence are known, for example, from the patent specifications mentioned above and from GB-A-2183471 and GB-A-2238237.
The calf support may be mounted on the chair so as to be movable between two positions, i.e. a stowage position in which it is at or close to vertical and essentially does not support the calf of a person seated in the chair and a use position in which the surface of the cushion members which contact the calf extends in the forward direction at an angle of at least 45° to the vertical, preferably at least 60° to the vertical.
The calf support may have an attachment portion, e.g. a frame portion which is releasably attachable to the chair, particularly to the frame of a wheelchair, and a support member for the cushion members which is movable, e.g. rotatable about an axis, relative to the frame portion, to bring the cushion members from the stowage position to the use position. The cushion members may be adjustable in the forward direction along the support member. The angle of the support surface to the vertical in the use position may be adjustable.
It will be understood that the active calf support provided by the present invention uses the weight of the lower leg of the user, to provide pressure at the interface between the lower leg and the cushion members when inflated. When deflated, the cushion members are preferably be vented to atmosphere, so that they apply only a residual pressure to the calf, permitting free circulation in the lower leg.
The cushion members preferably have a sufficient width, transverse to the forward direction, to accommodate both legs of the person in the chair. The cushion members may be suitably contoured in both the forward direction and the transverse direction, to provide a comfortable support for the user.
The present invention in another aspect provides a calf support attachment for a chair, e.g. a wheelchair, comprising a plurality of inflatable cushion members, a support for the cushion members supporting them so that they provide a support surface suitable for at least one calf of a person, and attachment means for mounting the attachment to a chair so that a person sitting on the chair can rest a calf of a leg extending away from the chair seat on the inflatable cushion member. Particularly, when intended for a wheelchair, the attachment means preferably is constituted by a frame portion securable to the wheelchair frame. Preferably the attachment includes a means for adjustably supporting the cushion support at a predetermined angle relative to the vertical. Preferably the cushion support additionally has a stowage position in which the cushion members substantially do not support the lower leg of a user.
Preferred and optional features of the calf support attachment of the invention are discussed above.
REFERENCES:
patent: 3261031 (1966-07-01), Gates
patent: 3936893 (1976-02-01), Anderson et al.
patent: 4017118 (1977-04-01), Cawley
patent: 4745647 (1988-05-01), Goodwin
patent: 4795214 (1989-01-01), Holdt
patent: 4962552 (1990-10-01), Hasty
patent: 4966413 (1990-10-01), Palarski
patent: 5022385 (1991-06-01), Harza
patent: 5277414 (1994-01-01), Binnen
patent: 5433506 (1995-07-01), Jensen
patent: 1 595 417 (1981-08-01), None
patent: 2 183 471 (1987-06-01), None
patent: 2 238 237 (1991-05-01), None
patent: 7901599 (1980-09-01), None
patent: WO 92/02200 (1992-02-01), None
patent: WO 94/07396 (1994-04-01), None
“Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society”, vol. 13:1991, Oct. 31-Nov. 3, 1991, 1932-1933.
Barfield Anthony D.
Larson & Taylor PLC
Pegasus Egerton Limited
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