Abstract:
A wheelchair back assembly is mounted from the vertical post of a wheelchair. The assembly has a back member comprising one or more rigid shells which are mounted by laterally extending adjustable clamping members. These clamping members permit a variety of adjustment angles, height and depth. Further, lateral support members can be independently adjusted to accommodate a particular user.

Description:
CROSS REFERENCE 
     This Patent Application is Based Upon U.S. Provisional Application Ser. No. 60/108,609, filed Nov. 16, 1998. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to adjustable seat backs, and more specifically to a seat back assembly which will accommodate a variety of wheelchair and user widths, and which is easily and simply adjusted with respect to a number of aspects including, for example, the angle of the back relative to the horizontal, and the distance in and out, and up and down of the back relative to the seat and the distance up and down and in and out relative to the seat. Further, the assembly includes lateral support members, which can be independently adjusted on either side in and out to accommodate the needs of a particular user. 
     BACKGROUND OF THE INVENTION 
     Wheelchairs are available in a variety of widths, generally intended to accommodate a variety of users depending both on the user&#39;s size, as well as on the manner in which the wheelchair is used. The needs of someone permanently confined to a wheelchair differ greatly from someone who is using a wheelchair during rehabilitation or recuperation. For example, healthy but impaired people may prefer to have a sports model of a chair with a tighter seating fit. in accordance with the prior art, issues of fit have been complicated by the fact that the wheelchair base, including the seat base and vertical post width come in standard incremental sizes. Accordingly, despite complex inventory issues, wheelchair backs have been provided in incremental sizes intended to accommodate the nearest incremental size chair base. The present invention answers the deficiencies of this system by providing a back, which has incrementally or infinitely adjustability to accommodate a range of standard size chairs and provide for the specific requirements of a variety of users. 
     As a further aspect of the invention, the back assembly provides multiple options with respect to the adjustability relative to the seat and yet which is easily installed and used. Thus, the back assembly mounts on the vertical post or cane of a wheelchair and can be adjusted up and down, in and out, and at various angles relative to the seat. 
     Finally, as a separate aspect of the invention, a back assembly system is provided which allows for a variety of support functions including separately from thoracic support, sacral support, support for the lateral regions of the shoulders, and head support. Means are provided to give adjustable lateral support, which can be varied independently one side of the other, and also according to the angle of the desired support. Thus, in accordance with the invention, a back assembly is provided which generally comprises a base member, mounting hardware, and optionally one or more lateral stabilizers. The base member consists of one or more rigid shells covered with a compressible foam. In the event that multiple shells are used, connecting means are used such as a locking hinge. The mounting hardware includes a first transverse member, which can be adjusted relative to the shell to accommodate varying widths of wheelchair frames. A second member can be adjusted in and out in depth. A pin is attached to the second member and allows the assembly to be pivoted around a transverse axle relative to the clamp in order to provide for a variety of angles of the back. Clamping members are releasably secured to the pin. Finally, the first and second members includes means to provide for incremental adjustment such as for example mating arm members which can have a scalloped camming surface so as to slide into incremental positions of adjustment. In an alternative embodiment, the second member has a sliding connection relative to the first member which may, for example, be provided by a keyway?? or dovetail which allows for longitudinal adjustment while retaining a connection between the members. 
     The back member comprises at least one rigid shell which would constitute a thoracic support but can optionally include additional shells such as a single sacral support, or double lateral sacral supports, corresponding single or double shoulder supports, and a head rest portion. The components may be jointed using a locking hinge, which is easily adjusted into a locked position. The back member is covered with a compressible foam and an outer covering. 
     Lateral support members (which may be shallow or deep) are provided which can be adjusted in and out and at various angles relative to the back member. A foam covering system is provided which accommodates adjustment of the lateral members relative to the back. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a back perspective view of a wheelchair back assembly in accordance with the present invention in position on the canes of a wheelchair; 
     FIG. 2 is a side-plan view of a two-panel back support having lateral stabilizers; 
     FIG. 3 is a front perspective plan of the two-panel back support of FIG. 2; 
     FIG. 4 is a front-plant view of a three-panel back support having lateral supports; 
     FIG. 5 is a back perspective view of the back support assembly showing an alternative embodiment of the mounting hardware; 
     FIG. 6 is a back perspective view of the back support assembly illustrating the components of the hinge; 
     FIG. 7 is an exploded assembly drawing of the first embodiment of the mounting hardware; 
     FIG. 8 is an assembled drawing of the mounting hardware showing FIG. 7; 
     FIG. 9 is an exploded assembly drawing of an alternative embodiment of the upper cane clamp; 
     FIG. 10 is an assembled view of the cane clamp of FIG. 9; 
     FIG. 11 is an exploded assembly drawing of an alternative embodiment of the lower cane clamp; and 
     FIG. 12 is an assembled drawing of the lower cane clamp of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the invention, a back assembly  10  is provided which generally comprises a base member  15 , mounting hardware  17 , and optionally one or more lateral stabilizers  19 . The base member  15  consists of one or more rigid shells  20  ultimately covered with a compressible foam. By “rigid” it is generally meant that the shell is able to support the load applied by a flaccid adult body and is generally not compressible. A suitable material is ⅛-½ inch compression molded polyvinyl chloride or metal such as aluminum. A locking hinge  24  can be used. Such a hinge provides that the angle between shells can be adjusted and subsequently locked. 
     In the event that multiple shells are used, connecting means are used such as a locking hinge  24 . The hinge assembly fits into a mounting boss  22  and locks by means of screws  23  threaded through spaces  25  into lock washers  27 . The hinge can be locked in any position within a certain range. Further optional rubber disc spacers  55  allow the assembly to dynamically flex in response to lower levels of loading by the user such as would occur during normal use. The mounting hardware assembly  17  includes a first transverse member  26 , which can be adjusted relative to the base to accommodate varying widths. One method of accomplishing this is a slotted connection  28  accommodating a fastener  29  secured to the shell  20 . The member  26  includes a transverse arm  30 . A second mounting member  32  mates with the arm  30  to enable adjustment in and out. A pin  33  is secured to the member  32  to allow the assembly to pivot around a transverse axle relative to a clamp  34  secured to the vertical post. This provides for a variety of angles of the back assembly. The second mounting member  32  can be attached to a receiver  39  formed in a C-shaped split halved clamping member  34 . A spring  42  is fixed to a release tab  35 . A fastener  43  is received in a sleeve  44  which supports a spring  45  and ultimately is captured in the release tab  35 . A transverse fastener  46  holds the two halves of the clamp together alternatively, the first and second mounting members may include a sliding connection such as is achieved by a dovetail engagement  37 . The first and second mounting member includes means to provide for incremental adjustment between them such as for example these mating arm members which have corresponding scalloped camming surfaces  36  so as to slide into incremental positions of adjustment. The clamping members  34  fasten to the vertical posts  40  of a wheelchair. Other attachment means could be used which would include other fasteners. 
     The back member  15  comprises at least one rigid shell  20  comprises a thoracic support  50  optionally having a hand hole  51 , but can optionally include a single lumbar sacral support  53 , or double lateral supports, corresponding single or double shoulder supports  54 , and a head rest portion. The shells  20  preferably include a spinal channel  56  which allows for extra cushioning for vertical protrusions. The components may be jointed using a locking hinge, which is easily adjusted into a locked position. The back member is covered with a compressible foam and an outer covering. 
     Lateral support members  19  are provided which can be adjusted in and out and at various angles relative to the back member. Preferably each shell member  20  has two lateral support members  19 . These include mounting slots  60  with a pin  61  connection to the shell which permits adjustment of the angle relative to the direction of the posts  40  and which allows positioning in and out to make the seating space wider or more narrow. A foam covering system is provided which accommodates adjustment of the lateral members relative to the back. 
     While in accordance with the patent statutes the best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.