the following detailed description is intended to describe the preferred embodiments that are depicted in the figures . it is to be understood that changes could be made to that which is specifically described and shown that would still fall within the scope of the present invention . referring now to the drawings in detail , wherein like numbered elements refer to like elements throughout , fig1 illustrates a preferred embodiment of backrest assembly of the present invention as it is installed on a wheelchair , generally identified 1 . the backrest assembly , generally identified 2 , is intended and designed by this inventor for use with all standard wheelchairs 1 . the backrest assembly 2 employs a thermoplastic material , such material having a high tensile and impact strength , for the outer shell portion 60 of the assembly 2 . see also fig7 . thermoplastic material is preferred for its light weight and relatively easy formability . it also provides the advantages of good stiffness and strength as well as flame retarding capability . the backrest assembly 2 may also employ a viscoback ™ cushioning system . the viscoback ™ cushioning system combines a high loft cushioning system with memory foam . the cushioning system provides for accommodation of patients with sensitive bony prominences and patients who develop areas of high pressure when they use the wheelchair 1 . the outer shell portion 60 of the assembly 2 is generally in the shape of a generally planar and somewhat rectangular shell exterior 61 and an open interior 62 . the open interior 62 is also generally rectangular and generally follows the contours of the exterior 61 of the shell 60 . it is to be understood , however , that the precise shape of the shell opening 62 is not a limitation of the present invention . the backrest shell 60 may also include a pair of lateral wings 63 , 64 . the lateral wings 63 , 64 each extend at an angle forwardly of the plane of the backrest shell central exterior 61 . see fig4 . the lateral wings , 63 , 64 can be of any shape or size but in the preferred embodiment they are approximately 3 inches wide at their widest . the lateral wings 63 , 64 in the preferred embodiment then arcuately taper in towards the backrest shell central exterior 61 both upwardly and downwardly . see fig5 . in a preferred embodiment of the invention , the backrest hard shell 60 provides support for an infinitely adjustable back support central insert member 70 . this infinitely adjustable back support insert 70 is comprised of a flexible shell 71 , a pair of stays 74 , 75 , and may include a cushioning system 78 as previously alluded to . the flexible shell 71 is configured to fit over the top 65 and the bottom 66 of the wheelchair backrest shell 60 . it is important that the entirety of the backrest hard shell 60 is covered by the flexible shell 70 so that the patient is not exposed to any of the hard backrest shell 60 . the flexible shell 71 has a pair of parallel pockets 72 , 73 that extend from the top of the backrest shell 65 to the bottom of the backrest shell 66 . in the preferred embodiment , the flexible shell 71 is supported by a pair of aluminum stays 74 , 75 that are inserted within the pockets 72 , 73 of the flexible shell 71 . see fig8 . the aluminum stays 74 , 75 should be long enough such that they fully extend between the top 65 and the bottom 66 of the wheelchair backrest shell 60 . it is also to be understood that the stays 74 , 75 need not be constructed of aluminum . the stays 74 , 75 can be constructed of any suitable material that is rigid , yet formable for the stated purpose . in a preferred embodiment , the aluminum stays 74 , 75 are fabricated to be 1½ inch wide and about ⅛ inch thick . see fig1 . the stays 74 , 75 are designed to be flexible enough to be formable by hand but stiff enough such that they stay in position when the wheelchair occupant leans against them . see fig9 . the stays 74 , 75 , in turn , support the cushioning system 78 . generally , the stays , 74 , 75 run through the pockets 72 , 73 and are configured to be parallel to the user &# 39 ; s back . the stays 74 , 75 can then be formed by the user or healthcare provider to accommodate each individual patient &# 39 ; s back . for example , in the case of a person having kyphosis , the front to back curvature of the spine , the stays 74 , 75 can be formed to match the curvature of the patient &# 39 ; s spine or even used as a corrective orthotic for the patient &# 39 ; s back . if kyphosis were the patient &# 39 ; s only back problem , the stays 74 , 75 would most likely be formed using the same radius of curvature . the stays 74 , 75 can also be used to treat or to comfort patients with conditions such as scoliosis , the side to side curvature of the spine . in the case of scoliotic patients , the stays 74 , 75 are normally individually formed to match the contours of each side of the patient &# 39 ; s back relative to the spine . in the experience of this inventor , patients who spend a significant amount of time in a wheelchair may either have or develop scoliosis , kyphosis , or both . it is therefore important to provide an adjustable backrest assembly 2 that allows for different patient needs and conditions , while providing a corrective feature . the inventor is also aware that patients needing wheelchairs 1 come in to different shapes and sizes and envisions a tall version of the above discussed embodiment as well as a bariatric version . the bariatric version of the wheelchair assembly 2 will likely provide more support , perhaps using a stiffer material for the stays 74 , 75 . the bariatric version may also provide a flexible backrest having either wider stays 74 , 75 or even more stays 74 , 75 to accommodate the physical needs of the obese patient . the flexible backrest shell 70 can be held on the rigid backrest shell 60 using any number of design contingencies , but low cost and simplicity are high priorities in this field . in the preferred embodiment shown in fig2 hook and loop type fastening straps , generally identified 76 , are used to hold the flexible shell 70 on the backrest 60 . the use of such hook and loop type fastening straps 76 allows the user to remove the flexible shell 70 quickly and easily for cleaning and reconfiguration . in the preferred embodiment , the rigid shell 60 of the backrest assembly 2 is held in place at the top using a combination of angle brackets 20 , 21 and chair hooks 40 , 41 , and at the bottom using a pair pivot arms 30 , 31 . the angle brackets 20 , 21 are attached to the backrest shell 60 . it should be noted that the angle brackets 20 , 21 offer a continuous aperture for mounting the angle brackets 20 , 21 to the backrest shell 60 . the chair hooks , 40 , 41 are attached to the upright wheelchair canes 10 , 11 . there are several possible types of chair hooks but two will be discussed here . the regular chair hook 70 , 71 provides three mounting apertures . each mounting position corresponds to approximately 5 ° of recline relative to the vertical . the regular chair hook 40 , 41 provides for approximately 10 ° of recline . a long chair hook ( not shown ) can provide up to 20 ° of recline . to attach the assembly 2 to the wheelchair 1 , the angle bracket 20 , 21 is simply attached to the chair hook 40 , 41 using a fastener of most any type . it should be noted that one should consider the amount of recline afforded the patient at this stage . the backrest shell 60 is also attached to the wheelchair canes 10 , 11 further down on the canes 10 , 11 using pivot arms 30 , 31 . the pivot arms 30 , 31 , are designed to support the backrest shell 60 regardless of the angle of recline of the backrest shell 60 . the pivot arms 30 , 31 also offer a continuous aperture such that they can be mounted on the backrest shell 60 anywhere along their length . the importance in having the continuous apertures for mounting the backrest shell 60 using the angle brackets and pivot arms is that wheelchair producers have built many different sizes of wheelchairs over the years , but most of them can be accommodated by permitting the installer to adjust the width of the aforementioned attachments . yet another embodiment of the device of the present invention incorporates a device comprised of a lower clip 32 and an upper locking clip 42 attached to the wheelchair cane 10 . see fig2 and 5 . the user of the wheechair 1 first pulls the lower clip 32 over the pivot arm 31 . the user then positions the upper locking clip 42 on the chair hook 40 . the upper locking clip 42 has a locking slide mechanism that snaps downwardly onto the chair hook 40 when urged downwardly by the user . this system provides a quick release mechanism for the easy removal and reattachment of the wheelchair backrest assembly 2 . yet another important feature of the present invention is the ease with which one can modify an existing wheelchair 1 having a web or sling - type support and customize that wheelchair 1 using the present invention . the present invention provides an assembly procedure involving only a few steps . first , the sling back ( not shown ) is removed from the wheelchair 1 . second , the upper chair hooks 40 , 41 are mounted to the angle brackets 20 , 21 . third , the lower pivot arms 30 , 31 are mounted to the backrest shell 60 and pivot arms 30 , 31 are mounted on the wheelchair canes 10 , 11 . fifth , the backrest 60 is placed in the wheelchair 1 . lastly , the angle brackets 20 , 21 are adjusted so that the chair hooks 40 , 41 fit squarely over the wheelchair canes 10 , 1 land the hard shell 60 is pressed firmly into the chair hooks 40 , 41 . a device designed to improve the life of wheelchair users has been disclosed . the device of the present invention provides a wheelchair backrest that can be quickly and easily installed on an existing wheelchair . it also provides for an individually tailored orthotic backrest designed to fit the curvature of each patient &# 39 ; s back . the present invention also provides for a wheelchair backrest that can recline up to 20 ° as such is desired or required . lastly , the present invention provides for a wheelchair backrest that can be manually adjusted . further , it is not the inventor &# 39 ; s intention to limit use of this invention solely to wheelchairs . the inventor of the product envisions a line of products employing the present invention to include office chairs and even chairs for the home . although i have very specifically described the preferred embodiments of the invention herein , it is to be understood that changes can be made to the improvements disclosed without departing from the scope of the invention . therefore , it is to be understood that the scope of the invention is not to be overly limited by the specification and the drawings , but is to be determined by the broadest possible interpretation of the claims .
a wheelchair backrest assembly is attachable to a wheelchair to replace the standard web or sling - type back . the backrest assembly is comprised of a rectangular frame having a central opening defined within it , the rectangular frame has sides curved forwardly to accommodate users of various sizes and shapes . a plurality of support members are attached to the frame and mountable to the upright cane portions of the wheelchair . the front portion of the rectangular frame , or that portion facing the wheelchair user , is covered by a cushioned pad , the back of which has a plurality of pockets designed to accommodate formable stays . the shape of each stay may be molded by hand and should be of a material resilient enough to withstand frequent reforming and yet should be strong enough such that when a user reclines against the backrest , the stays remain in place .