Patent Publication Number: US-8991926-B2

Title: Backrest for wheelchair

Description:
RELATED APPLICATIONS 
     The present application claims the benefit of European Patent Application No. 11179224.8, filed on Aug. 29, 2011, which is incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a backrest for a wheelchair provided with an adjustable cushion support, a backrest frame for holding said cushion support and attachment members, for attaching said cushion support to said backrest frame. 
     BACKGROUND OF THE INVENTION 
     Many backrests types are known in the art. Most backrests are attached to a frame and do not allow any adjustment possibilities. Adjustable backrests are also known. For instance, document US 2006/0091706, Christofferson et al. “Seat assembly for wheelchair”, describes a typical seat assembly that can be mounted on various wheelchair bases. The seat assembly enables the seat width and backrest width to be adjusted independently of each other. The backrest has a plurality of open slots, the number and orientation of which contributes to depth, width, and height adjustment of the backrest as well as angular adjustment of lateral supports to permit the backrest to conform to the anatomical curves of a user. A first set of slots is provided for height adjustment of the thoracic support. Further slots are provided for lateral adjustment of the thoracic support. Threaded fasteners provided in adjustment holes are provided for height adjustment of the backrest with respect to a main member. In the disclosed embodiment, all adjustments are made independently, involving time consuming manipulations. Moreover, once a first adjustment has been made with a first member, further adjustments of this first member may be required after another member is adjusted. Finally, in this known wheelchair, the backrest comprises a central part and two lateral parts which are rigid. Therefore, it is not possible to deform these parts so as to adapt the shape of the backrest to the anatomical curves of a user. 
     SUMMARY OF THE INVENTION 
     According to the invention, a backrest for a wheelchair, comprises:
         an adjustable cushion support, for supporting a backrest cushion, said cushion support defining substantially a first plane P 1 ;   a backrest frame, for holding said cushion support, said backrest frame having two substantially parallel first side posts defining substantially a second plane P 2 ;   attachment members, for attaching said cushion support to said backrest frame;   said cushion support comprising two side bars and a plurality of transversally extending and vertically spaced apart flexible straps each interconnecting said two side bars, each strap having length adjustment;   said cushion support comprising at least two connecting plates, each plate being integral with one of said side bars and being provided with at least two parallel adjustment slots, said slots defining an angle α, with said first plane P 1 ;   said attachment members being slidably mounted on said slots, enabling depth, width and angular adjustment of said cushion support on said backrest frame.       

     With such an arrangement, the parallel slots enable adjustment of the position of the cushion support with regard to the backrest frame. Adjustment is thus easier and quicker to perform than standard configurations having separate adjustments. 
     Moreover, the flexible and length-adjustable straps of the cushion support enable separate adjustment of each side bar of said cushion support. Thus, the shape of the cushion support may advantageously be adapted to the morphology of the user. 
     The invention also provides a wheelchair having a backrest according to the above-mentioned characteristics. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by the figures, in which: 
         FIG. 1  illustrates a partially exploded front perspective view of a backrest according to the invention, when connected to a wheelchair seat; 
         FIG. 2  is a partially exploded side view of the backrest of  FIG. 1 ; 
         FIG. 2A  is a sectional view taken along the plane indicated by lines  2 A- 2 A in  FIG. 2 ; 
         FIGS. 3   a  and  3   b  are, respectively, a front view and a side view of the backrest of  FIG. 1 , in a first position of use; 
         FIGS. 4   a  and  4   b  are, respectively, a front view and a side view of the backrest of  FIG. 1 , in a second position of use; 
         FIGS. 5   a  and  5   b  are, respectively, a front view and a side view of the backrest of  FIG. 1 , in a third position of use; 
         FIGS. 6   a  and  6   b  are, respectively, a front view and a side view of the backrest of  FIG. 1 , in a fourth position of use; 
         FIG. 7  is a front view of the backrest of  FIG. 1 , in a fifth position of use; 
         FIG. 8  is a front perspective view of the backrest of  FIG. 1 , showing the complete structure of the cushion support. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     In one exemplary embodiment, the present invention provides a wheelchair that is adjustable in a quick and easy way. In one exemplary embodiment, the present invention provides a backrest that may be manufactured with reasonable equipment requirements in a cost effective way. In one exemplary embodiment, the present invention provides a backrest that may be deformed so as to adapt its shape to the anatomical curves of a user. 
       FIG. 1  illustrates a perspective view of the backrest  1 , when it is connected to the seat frame  2  of a wheelchair. So as to improve the understanding, some components have been shown in exploded view and some other components have been partially removed. Further details of the backrest  1  may also be seen on  FIG. 2 . 
     The backrest  1  comprises two main parts, i.e. a cushion support  10  supporting a backrest cushion (not shown) and a backrest frame  20  holding said cushion support  10 . The backrest cushion may be made with foam or other soft material to provide more comfort for the user. A covering may also be provided. The cushion support  10  is attached to the backrest frame  20  by means of attachment members  3 . In the illustrated embodiment, said attachment members  3  consist in bolts or screws adapted to be threadedly received in a series of threaded holes  25  formed inside two side posts  21   a  and  21   b  of the backrest frame  20 . Said side posts  21   a  and  21   b  are linked at their lower ends by a connection profile  21   c  so as to form a first U-shape element  21  defining approximately a plane P 2 . Said first U-shape element  21  is removably connected to a second U-shape element  22  comprising two side posts  22   a  and  22   b  linked at their upper ends by a connection profile  22   c,  said second U-shape element  22  defining a plane P 3  close to and approximately parallel to the plane P 2 . Said elements  21  and  22  may for instance be clamped together by using upper clamping elements  23   a,    23   b  and lower clamping elements  24   a,    24   b  positioned respectively in the upper part and in the lower part of each side post  22   a  and  22   b.  Each clamping elements  23   a,    23   b  and  24   a,    24   b  may consist for instance in a plate bent at its two side ends so as to define an internal space inside which one of said side posts  22   a  or  22   b  and corresponding side post  21   a  or  21   b  are tightly disposed. As illustrated in  FIGS. 1 and 2 , when the elements  21  and  22  are connected together, the upper clamping elements  23   a,    23   b  may advantageously be positioned along the side posts  21   a  and  21   b  respectively so as to cover a section of said side posts  21   a  and  21   b  comprising the threaded holes  25 . Accordingly, corresponding holes  26  are formed in said upper clamping elements  23   a,    23   b  so that said holes  25  and  26  are axially aligned when said elements  21  and  22  are connected together. 
     As shown in greater details in  FIG. 8 , the cushion support  10  comprises two side bars  11   a  and  11   b  and a plurality of transversally extending and vertically spaced apart flexible straps  14 , each strap  14  interconnecting said two side bars  11   a  and  11   b  and each strap  14  being adjustable in length. In adjusting the length of said straps, the tension of said straps may be changed in conformity with the user&#39;s need. In one preferred embodiment (not shown). The adjustable length of the straps  14  may be provided by Velcro (registered trademark) fasteners provided on one side of the straps  14  and in complementary Velcro (registered trademark) fasteners provided on the other side of the straps  14 . The side bars  11   a  and  11   b  may be straight or, as illustrated in  FIGS. 1 and 2 , may be formed by two straight end sections linked to a straight middle section so that said end sections are inclined with regard to the middle section. In the position of use of the backrest  1 , the middle sections of the side bars  11   a  and  11   b  will be advantageously positioned so as to be parallel in a plane P 1 . The cushion support  10  comprises also two connecting plates  12   a  and  12   b,  each plate  12   a  and  12   b  being integral with one of said side bars  11   a  and  11   b  and being provided with two parallel adjustment slots  13 . In a further embodiment (not shown) of the invention, said plates  12   a  and  12   b  may also comprise a greater number of slots  13 . The slots  13  of each plates  12   a  and  12   b  are advantageously aligned in a plane forming with the plane P 1  an angle α, α&gt;0, said angle α lying preferably between 30° and 60°, and more preferably, being approximately equal to 45°. Said slots  13  may have a length lying between 10 mm and 50 mm, and, preferably, a length approximately equal to 35 mm when said angle α is approximately equal to 45°. 
     To adjust the depth and angular position of the cushion support  10  with regard to the backrest frame  20 , the attachment members  3 , i.e. bolts or screws, are slidably mounted on the adjustment slots  13 . Adjustment may be made in a very simple and quick way. When the bolts or screws  3  are slightly loosened, that is to say enough to allow the bolts or screws  3  to slide inside the slots  13 , but not enough to allow complete removal of the cushion support  10  from the backrest frame  20 , the plates  12   a  and  12   b,  together with the side bars  11   a  and  11   b,  may be independently moved backward, forward or inclined and adjusted along a position allowing a maximum comfort for the user. In order to change the position of the bolts or screws  3  inside the slots  13 , said slots  13  should advantageously be large enough to allow said bolts or screws to pivot as a group in said slots without being removed from said slots. Once an appropriate position is reached, the plates  12   a  and  12   b  are secured with the bolts or screws  3  against the clamping elements  23   a  and  23   b  respectively. This operation simultaneously allows securing said clamping elements  23   a  and  23   b  against the side posts  21   a  and  21   b  respectively. In this way, the cushion support  10  is firmly held against the backrest frame  20 . The position of the cushion support  10  with regard to the backrest frame  20  may also be modified in height by introducing the bolts or screws  3  in other holes  25  and  26  as illustrated in dotted lines in  FIGS. 1 and 2 . 
     The slots  13  enable a very wide choice of potential positions. Some examples of said potential positions are illustrated in  FIGS. 3   a ,  3   b ,  4   a ,  4   b ,  5   a ,  5   b ,  6   a ,  6   b  and  7 . In the above mentioned Figures, the slots  13  may be defined as a straight segment extending between a proximal end  13   p  and a distal end  13   d,  said proximal end  13   p  being closer to the plane P 1  than the distal end  13   d.  In addition, the two slots  13 , respectively an upper slot  13 ′ and a lower slot  13 ″, of each plate  12   a  and  12   b  are aligned in a plane forming with the plane P 1  an angle approximately equal to 45°. This specific configuration permits a simultaneous and similar change of the depth position of the cushion support  10  with regard to the backrest frame  20  and of the width of the cushion support  10 . Said depth position may be defined by the distance between the plane P 1  and the plane P 2  and said width may be defined by the distance between the middle sections of the side bars  11   a  and  11   b.    
     Thus, when all bolts or screws  3  are aligned with the proximal ends  13   p  of the slots  13 , as illustrated in  FIGS. 3   a  and  3   b , the planes P 1  and P 2  are approximately parallel and the cushion support  10  is positioned in its less wide position, the distance d 1  between the planes P 1  and P 2  and the distance I 1  between the side bars  11   a  and  11   b  being minimum. 
     On the contrary, when all bolts or screws  3  are aligned with the distal ends  13   d  of the slots  13 , as illustrated in  FIGS. 4   a  and  4   b , the planes P 1  and P 2  stay approximately parallel but the cushion support  10  is positioned in its widest position, the distance d 2  between the planes P 1  and P 2  and the distance I 2  between the side bars  11   a  and  11   b  being maximum. 
     In the configuration illustrated in  FIGS. 5   a  and  5   b , the bolts or screws  3  received in the upper slots  13 ′ are closer to the distal ends  13   d  than to the proximal ends  13   p  of said upper slots  13 ′ and, inversely, the bolts or screws  3  received in the lower slots  13 ″ are closer to the proximal ends  13   p  than to the distal ends  13   d  of said lower slots  13 ″. Thus, in this configuration, the plane P 1  is inclined forward with regard to the plane P 2 , said plane P 1  forming an angle β 1  with said plane P 2  and the distance I 3  separating the upper sections of the side bars  11   a  and  11   b  being higher than the distance I 4  separating the lower sections of the side bars  11   a  and  11   b.  This configuration is well adapted for a man, because a man is generally broad-shouldered and has thin hips. 
     In the configuration illustrated in  FIGS. 6   a  and  6   b , the bolts or screws  3  received in the upper slots  13 ′ are closer to the proximal ends  13   p  than to the distal ends  13   d  of said upper slots  13 ′ and, inversely, the bolts or screws  3  received in the lower slots  13 ″ are closer to the distal ends  13   d  than to the proximal ends  13   p  of said lower slots  13 ″. Thus, in this configuration, the plane P 1  is inclined backward with regard to the plane P 2 , said plane P 1  forming an angle β 2  with said plane P 2  and the distance I 5  separating the upper sections of the side bars  11   a  and  11   b  being lower than the distance I 6  separating the lower sections of the side bars  11   a  and  11   b . This configuration is well adapted for a woman, because a woman is generally thin-shouldered and has broad hips. 
     In the configuration illustrated in  FIG. 7 , the bolts or screws  3  received respectively in the upper slot  13 ′ of the side bar  11   b  and in the lower slot  13 ″ of the side bar  11   a  are closer to the proximal ends  13   p  than to the distal ends  13   d  of said upper and lower slots and, inversely, the bolts or screws  3  received respectively in the lower slots  13 ″ of the side bar  11   b  and in the upper slot  13 ′ of the side bar  11   a  are closer to the distal ends  13   d  than to the proximal ends  13   p  of said lower and upper slots. Thus, in this configuration, the plane P 1  is inclined sideways with regard to the plane P 2  and the distance I 7  separating the upper sections of the side bars  11   a  and  11   b  being approximately equal to the distance I 8  separating the lower sections of the side bars  11   a  and  11   b.  This configuration is well adapted for a person suffering of scoliosis. 
     In the illustrated embodiment of  FIGS. 1 and 2 , the backrest frame  20  is pivotally connected to the seat frame  2  around the axis  29 . In particular, two arms  27   a  and  27   b  extending in a direction approximately perpendicular to the plane P 2  and integral with, respectively, the side posts  21   a  and  21   b  are pivotally connected to corresponding arms  4   a  and  4   b  of the seat frame  4 , said arms  4   a  and  4   b  extending in a direction close to the vertical or slightly inclined with regard to the vertical. In order to modify the inclination of the backrest frame  20  with regard to the seat frame  2 , a gas piston (not shown) fixedly connected to the seat frame  2  may be connected at its free end to a connecting structure  28  positioned underneath and in the center of the connection profile  21   c  of the backrest frame  20 . 
     The above detailed description with reference to the drawings illustrates rather than limit the invention. There are numerous alternatives, which fall within the scope of the appended claims. For instance, the clamps and holder members are shown with screws and nuts. Other types of fastening means may also be used without departing from the invention. 
     The word “comprising” does not exclude the presence of other elements or steps than those listed in a claim. The word “a” or “an” preceding an element or step does not exclude the presence of a plurality of such elements or steps. The mere fact that respective dependent claims define respective additional features, does not exclude a combination of additional features, which corresponds to a combination of dependent claims.