Chairs and seats – Bottom or back with means to alter contour – Providing support for lower back region
Reexamination Certificate
1998-04-07
2001-02-13
Nelson, Jr., Milton (Department: 3624)
Chairs and seats
Bottom or back with means to alter contour
Providing support for lower back region
C297S284100
Reexamination Certificate
active
06186594
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flexible backrest, in particular but not exclusively a wheelchair backrest, having a contour that can be easily adjusted to the morphology and anthropometry of a user's back.
2. Brief Description of the Prior Art
Manual wheelchairs usually come with conventional sling backrests. Originally, this type of backrest was designed to enable easy folding of the wheelchair. However, some studies have demonstrated that prolonged use thereof may negatively affect user's posture, comfort, function and health (Zollars, J. & Axelson, P. (1993) “
The back support shaping system: an alternative for persons using wheelchairs with sling upholstery
”, Proceedings of the 16
th
Annual RESNA Conference, Las Vegas, RESNA Press, 274-276; Harms, M. (1990) “
Effects of wheelchair design on posture and comfort of users
”, Physiotherapy, 76, 5, 266-271; Bergen, A. & Presperin, J. (1990), “
Positioning for functions: wheelchairs and other assistive technologies
”, Valhalla Rehabilitation Publications Ltd; and Zacharkow, D. (1984), “
Wheelchair posture and pressure sores
”, Springfield, Ill.). In fact, they may cause the spine to curve into a kyphotic geometry and produce a posterior tilting of the pelvis, which can lead to back and neck pain, and even to long-term deformities of the spine and pelvis. Moreover, conventional sling backrests do not provide sufficient lateral trunk support to prevent, manage or correct trunk alignment problems.
Considering these problems, the development of special seating for people with disabilities become important. The technology in seating has rapidly evolved around cushions or combination of rigid interfaces and cushions with great results. There is a general consensus that, from a posture standpoint, they offer some of the best solutions (Valiquette, C. & Audet, J. (1992) “
Pushing the limits of the sling concept: the contoured sling backrest
” Canadian seating and mobility conference, Toronto). Unfortunately, the use of cushions deprives many wheelchair users of the advantages of the sling backrests such as foldability, light weight, low cost and simplicity (Valiquette, C. & Audet J. (1992), “
Pushing the limits of the sling concept: the contoured sling backrest
”, Canadian seating and mobility conference, Toronto; and Zollars J. & Axelson P. (1993), “
The back support shaping system: an alternative for person using wheelchairs with sling upholstery
”, Proceedings of the 16
th
Annual RESNA Conference, Las Vegas: RESNA Press, 274-276).
In this way, adjustable-tension back upholstery was introduced on the market to preserve the sling backrests characteristics while improving the user's posture and comfort. Adjustable-tension back upholstery are foldable and can accommodate lumbar lordosis or kyphosis by the use of adjustable straps. In spite of the improvement, they often give poor lateral trunk support and some adjustments are still missing to maintain neutral pelvic position and lumbar lordosis. Given this context, the conception of a new backrest for wheelchair is worthwhile.
OBJECTS OF THE INVENTION
An object of the present invention is therefore to provide a flexible contour backrest, in particular but not exclusively a wheelchair backrest, which overcomes the above mentioned drawbacks of the prior art.
Another object of the present invention is to provide a flexible contour backrest, in particular but not exclusively a wheelchair backrest, having a contour that can be easily adjusted to fit a plurality of users' back contours in view of (a) suitably supporting the back of these users and (b) improving lateral trunk support.
SUMMARY OF THE INVENTION
More specifically, in accordance with the present invention, there is provided a flexible contour backrest comprising two side posts, and a flexible backrest body extending between the two side posts. The flexible backrest body comprises a plurality of transversally extending and vertically spaced apart flexible straps each interconnecting the two side posts and each having an adjustable length, and a plurality of substantially stiff stays intersecting at least one of the flexible straps. In operation, the contour of the backrest body can be adjusted to the contour of a user's back by adjusting the length of the straps and the shape of the stays.
Also in accordance with the present invention, in a flexible contour backrest comprising two side posts, and a flexible backrest body extending between the two side posts and including two opposite sides attached to the two side posts, respectively, the improvement comprises an elongated curved front face of each side post for receiving the two opposite sides of the flexible backrest body, respectively. This elongated curved front face of each side post has a forwardly bulging section for inducing a depth dimension to the flexible backrest body to fit the posterior lateral contour of a user's back and thereby providing lateral support to the user's trunk.
The present invention further relates to a flexible contour backrest comprising two side posts each comprising an elongated curved front face, and a flexible backrest body extending between the elongated curved front faces of the two side posts. The flexible backrest body comprises (a) a plurality of transversally extending and vertically spaced apart flexible straps each interconnecting the two side posts with elongated curved front faces, and each having an adjustable length, and (b) a plurality of substantially stiff stays intersecting at least one of the flexible straps.
In accordance with preferred embodiments:
the substantially stiff stays are malleable to facilitate adjustment of their shape;
the plurality of transversally extending and vertically spaced apart flexible straps comprises an upper strap, a lower strap, and an intermediate strap situated between the upper and lower strap, and the flexible contour backrest further comprises means for adjusting a vertical position of the intermediate strap on the two side posts;
the transversally extending and vertically spaced apart flexible straps are generally perpendicular to the two side posts, and the substantially stiff stays are generally perpendicular to these straps;
the flexible backrest body comprises elongated pockets for receiving the substantially stiff stays;
the two side posts are mounted on a chair frame, and the flexible contour backrest further comprises mechanical means for adjusting the vertical position of the two side posts on the chair frame; and
the flexible contour backrest comprises mechanical means for varying the distance between the forwardly bulging sections of the elongated curved front faces of the two side posts, in order to adapt the distance between said forwardly bulging sections to the width of the user's trunk.
In accordance with a first alternative embodiment:
the two side posts each comprise an elongated member defining a two-dimensional or three-dimensional curve and having a substantially straight lower end mounted to a chair frame, this substantially straight lower end having a longitudinal geometrical axis;
the mechanical means comprises means for rotating the substantially straight lower end of the curved elongated member on the chair frame about the longitudinal geometrical axis, and means for locking the substantially straight lower end of the curved elongated member on the chair frame in a plurality of different angular positions about the longitudinal geometrical axis; and
the mechanical means further comprises means for axially moving the substantially straight lower end of the curved elongated member about the chair frame and means for locking the substantially straight lower end of the curved elongated member on the chair frame in a plurality of different axial positions.
In accordance with a second alternative embodiment:
the two side posts each comprise an elongated member, and a contour member mounted on the elongated member to define the elongated curved front face of the side post;
the m
Dansereau Jean
Parent Frédéric
Valiquette Claude
Corporation de l'ecole Polytechnique
Jr. Milton Nelson
Merchant & Gould P.C.
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