Abstract:
Seat cushions that prevent a seated handicapped individual from sliding forward on the seat, while preventing the occurrence of decubitus ulcers. The seat a seat cushion includes a resilient body having a generally rectangular shape. The resilient body includes a frontal portion having a front end and a rear end, and which is fabricated from materials having a first density, and a rear portion having a front end and a rear end, and is fabricated from materials having a second density. The first density is substantially higher than the second density. Preferably, the resilient body is fabricated out of a sturdy foam material. Preferably, the seat cushion further includes a protective cover wrapping the resilient body.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 USC 119(e) from U.S. provisional application 61/146,669, filed on Jan. 23, 2009, the disclosure which is incorporated by reference for all purposes as if fully set forth herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to seat cushions used to support individuals in a seated or otherwise reclined position. More particularly, the present invention relates to seat cushions typically used in wheelchairs, which seats structure help preventing a seated handicapped individual from sliding forward on the seat, while preventing the occurrence of decubitus ulcers. 
       BACKGROUND OF THE INVENTION 
       [0003]    Wheelchair seat cushions are designed to perform a number of important functions. A seat cushion should be comfortable and capable of providing proper support for optimal posture and posture control, for a considerable length of time. A seat cushion should create stability and security for the person within the wheelchair. Seat cushions are often designed to help prevent and reduce the incidence of local pressure created by prolonged sitting on the cushion trying to uniformly spread the pressure on the external surface of the seating organs of the individual. 
         [0004]    Many prior art attempts have been made to generally or individually fit the shape of the seat cushion to the anatomical shape of the user. For example, U.S. Pat. No. 4,588,229, given to Eric Jay, provides a seat cushion for the human body which comprises a pad comprising a flexible envelope containing a fluid filling material. 
         [0005]    U.S. Pat. No. 4,819,286, given to David Beauchamp, provides a dry flotation cushion used on wheelchairs and a method for supporting dry flotation cushion used in wheelchairs. The structure includes a substantially rectangular rigid plate for inserting into the fabric covering of a dry flotation cushion for improving the support provided by a plurality of dry flotation cells when the dry flotation cushion is supported on the side frame members of a wheelchair. 
         [0006]    U.S. Pat. No. 7,220,376, given to Thomas Hetzel et al, provides a negative impression of an anatomical portion of a person is captured by forcing the anatomical portion into impression foam to collapse the impression foam into the negative impression. The negative impression is obtained by collapsing the impression foam within the range of constant-force collapse distances, thereby creating the negative impression under conditions which reflect an equally-loaded anatomical portion. This invention is then used to fabricate wheelchair seat cushions. 
         [0007]    U.S. Pat. No. 6,009,578, given to Steve Davis, provides a seat cushion for a wheelchair including a resilient wedge-shaped pad having an upper surface at an incline sloping downwardly from a higher end to a lower end. A plurality of spaced apart gel packs are on the upper surface of the resilient wedge-shaped pad. The gel packs closest to the higher end are of a high density, while other gel packs will decrease in density toward the lower end of the resilient wedge-shaped pad. The seat helps preventing a person from sliding off of the wheelchair. 
         [0008]    The prior art shaped seat cushion are typically expensive to manufacture and do not necessarily address the problem encountered by handicapped individual, such as elderly individuals, that are sliding forwardly on top of the seat and are not able to pull themselves back. Often, a handicapped individual is not even aware of being in a slid seating position. 
         [0009]    Reference is made to  FIG. 2  (prior art), which is a cross-sectioned view showing person  10  properly positioned in wheelchair  20  seating system, on seat cushion  50 . The back of person  10  is supported by back  30  of wheelchair  20 . Pelvis  15  supported by both the lower end of back  30  and the end of seat cushion  50  proximal to back  30 . 
         [0010]    Reference is also made to  FIG. 3  (prior art), which is a cross-sectioned view showing person  10  who has slid forward (in direction  40 ) and thereby improperly positioned in wheelchair  20  seating system, on seat cushion  50 . Pelvis  15  is positioned away from the lower end of back  30  and is and is pointy pressing against seat cushion  50 , thereby causing person  10  to develop decubitus ulcers. Furthermore, the sliding motion cause rubbing of the external surface of pelvis  15  of individual  10 . Furthermore, as person  10  slides on seat cushion  50 , the sliding motion accelerate as vector F H , derived from the weight vector F V  of person  10 , is added to the motion forward in direction  40 . 
         [0011]    Reference is also made to  FIG. 4  (prior art), which is a cross-sectioned view showing person  10  who is seating on wedge seat cushion  52 , which is designed to prevent a seated handicapped individual  10  from sliding forward on seat cushion  52 . Pelvis  15  is positioned away from the lower end of back  30  and is pointy pressing against seat cushion  52 , thereby causing person  10  to develop decubitus ulcers. 
         [0012]    There is a need for and it would be advantageous to have a seat cushion that prevents a seated handicapped individual from sliding forward on the seat, while preventing the occurrence of decubitus ulcers. It would be further advantageous for the seat cushion to be simple and inexpensive to manufacture. 
       SUMMARY OF THE INVENTION 
       [0013]    By way of introduction, the principal intentions of the present invention include providing seat cushions that prevent a seated handicapped individual from sliding forward on the seat, while preventing the occurrence of decubitus ulcers. The seat cushions are made of two or more portions made of resilient materials, such as elastomeric materials, whereas the portion of the cushion distal from the back of the wheelchair is more rigid than the portion of the cushion proximal to the back of the wheelchair. 
         [0014]    According to the teachings of the present invention there is provided a seat cushion for supporting a person seated on a chair, preferably a wheelchair, including a resilient body having a generally rectangular shape. The resilient body includes a frontal portion having a front end and a rear end, and which is fabricated from materials having a first density, and a rear portion having a front end and a rear end, and is fabricated from materials having a second density. The first density is substantially higher than the second density. Preferably, the resilient body is fabricated out of a sturdy foam material. Preferably, the seat cushion further includes a protective cover wrapping the resilient body. 
         [0015]    The frontal portion is disposed distally from the back of the chair, while the rear portion is disposed proximal to the back of the chair. The front end of the rear portion is disposed adjacent to the rear end of the frontal portion. 
         [0016]    Preferably, the rear portion is made of viscoelastic materials, to prevent decubitus ulcers. 
         [0017]    Preferably, the front end of the rear portion is securely attached to the rear end of the frontal portion. Preferably, the seat cushion is securely attached to the back of the chair. 
         [0018]    In variations of the present invention, the seat cushion of the invention further includes one or more intermediate portions, disposed between the frontal portion and the rear portion, wherein all of the portions maintain a gradual decrease in density starting at the front portion and ending at the rear portion. 
         [0019]    In variations of the present invention, the frontal portion of the resilient body includes a divider having third density, wherein the divider laterally subdivides the frontal portion into two generally symmetric sections, wherein each of the symmetric sections facilitates comfort and stability for a respective thigh of the person sitting in the chair. The third density is higher than the first density. 
         [0020]    In variations of the present invention, the frontal portion of the resilient body includes a divider having third density and a top layer having a fourth density, wherein the divider is disposed adjacently above the frontal portion and laterally subdivides the frontal portion into two generally symmetric sections. The top layer is disposed adjacently above the divider, the frontal portion and optionally the rear portion. Each of the symmetric sections facilitates comfort and stability for a respective thigh of the person sitting in the chair. The third density is substantially higher than the first density and preferably, the forth density is lower than the third density. Preferably, the top layer extends to the dimensions of the seat cushion. 
         [0021]    In variations of the present invention, the frontal portion of the resilient body includes a divider having third density and a bottom layer having a fourth density, wherein the divider is disposed adjacently below the frontal portion and laterally subdivides the frontal portion into two generally symmetric sections. The bottom layer is disposed adjacently below the divider, the frontal portion and optionally the rear portion. Each of the symmetric sections facilitates comfort and stability for a respective thigh of the person sitting in the chair. The third density is substantially higher than the first density and preferably, the forth density is higher than the third density. Preferably, the top layer extends to the dimensions of the seat cushion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The present invention will become fully understood from the detailed description given herein below and the accompanying drawings, which are given by way of illustration and example only and thus not limitative of the present invention, and wherein: 
           [0023]      FIG. 1  illustrates a wheelchair with a seat cushion, according to embodiments of the present invention; 
           [0024]      FIG. 2  (prior art) is a cross-sectioned view showing a person properly positioned in a wheelchair seating system; 
           [0025]      FIG. 3  (prior art) is a cross-sectioned view showing a person who has slid forward and thereby improperly positioned in a wheelchair seating system; 
           [0026]      FIG. 4  (prior art) is a cross-sectioned view showing a person who is seating on a wedge seat cushion, which is designed to prevent a seated handicapped individual from sliding forward on the seat; 
           [0027]      FIG. 5  is a perspective view illustration of a seat cushion, according to variations of the present invention; 
           [0028]      FIG. 6  is a cross-sectioned view showing a person properly positioned and held in a wheelchair seating system having the seat cushion shown in  FIG. 5 ; 
           [0029]      FIG. 7  is a graphical chart showing the rigidity of the seat cushion shown in  FIG. 5 , vs. the distance of a position on the seat cushion from its front end; 
           [0030]      FIG. 8  is a perspective view illustration of a seat cushion, according to other variations of the present invention; 
           [0031]      FIG. 9  is a graphical chart showing the rigidity of the seat cushion shown in  FIG. 8 , vs. the distance of a position on the seat cushion from its front end; 
           [0032]      FIG. 10  is a perspective view illustration of a seat cushion, according to another variation of the present invention; 
           [0033]      FIG. 11  is a perspective view illustration of a seat cushion, according to yet another variation of the present invention; 
           [0034]      FIG. 12  is a perspective view illustration of a seat cushion, according to still another variation of the present invention, the seat cushion being in a non-seated state; and 
           [0035]      FIG. 13  is a perspective view illustration of the seat cushion shown in  FIG. 11 , the seat cushion being in a seated state. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred 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. 
         [0037]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The methods and examples provided herein are illustrative only and not intended to be limiting. 
         [0038]    By way of introduction, the principal intentions of the present invention include providing seat cushions that prevent a seated handicapped individual from sliding forward on the seat. 
         [0039]    Reference is now made to the drawings.  FIG. 1  wheelchair  20  with seat cushion  100 , according to variations of the present invention.  FIG. 5  is a perspective view of seat cushion  100  (having the cushion cover removed). Seat cushion  100  has a generally rectangularly shaped body that includes a frontal portion  120  and a rear portion  110 . Frontal portion  120  and rear portion  110  are made of resilient materials, wherein frontal portion  120  is more rigid than rear portion  110 . 
         [0040]    Rear portion  110  has a front end and a rear end, wherein the rear end of rear portion  110  is proximal to back  30  of wheelchair  20  and the front end of rear portion  110  is most distal from back  30  of wheelchair  20 . Frontal portion  120  has a front end and a rear end, wherein the front end of frontal portion  120  is most distal from back  30  of wheelchair  20  and the rear end of frontal portion  120  is most proximal to back  30  of wheelchair  20 . The front end of rear portion  110  is disposed adjacent to the rear end of frontal portion  120  and preferably, securely attached to the rear end of frontal portion  120 . 
         [0041]      FIG. 6  is a cross-sectioned view showing person  10  properly positioned and held in wheelchair  20  seating system, utilizing seat cushion  100 . The back of person  10  is supported by back  30  of wheelchair  20 . Pelvis  15  supported by both the lower end of back  30  and rear portion  110  of seat cushion  100 , disposed proximal to back  30 . Frontal portion  120 , being more rigid than rear portion  110 , further supports pelvis  15  such that frontal portion  120  prevents pelvis  15  from sliding forward (direction  40  in  FIG. 3 ) on seat cushion  100 . 
         [0042]      FIG. 7  is a graphical chart showing the rigidity of seat cushion  100 , vs. the distance of positions on seat cushion  100  from the front end of seat cushion  100 . Part A exemplifies the rigidity of frontal portion  120  and part B exemplifies the rigidity of rear portion  110 . 
         [0043]      FIG. 8  is a perspective view of seat cushion  200  (having the cushion cover removed). Seat cushion  200  has a generally rectangularly shaped body that includes a frontal portion  230 , a middle portion  220  and a rear portion  210 , all of which are made of resilient materials. Frontal portion  230  is more rigid than middle portion  220  and middle portion  220  is more rigid than rear portion  210 . 
         [0044]    Rear portion  210  has a front end and a rear end, wherein the rear end of rear portion  210  is proximal to back  30  of wheelchair  20  and the front end of rear portion  210  is most distal from back  30  of wheelchair  20 . Middle portion  220  has a front end and a rear end, wherein the front end of middle portion  220  is most distal from back  30  of wheelchair  20  and the rear end of middle portion  220  is most proximal to back  30  of wheelchair  20 . Frontal portion  230  has a front end and a rear end, wherein the front end of frontal portion  230  is most distal from back  30  of wheelchair  20  and the rear end of frontal portion  230  is most proximal to back  30  of wheelchair  20 . 
         [0045]    The front end of rear portion  210  is disposed adjacent to the rear end of middle portion  220  and preferably, securely attached to the rear end of middle portion  220 . The front end of middle portion  220  is disposed adjacent to the rear end of front portion  230  and preferably, securely attached to the rear end of front portion  230 . 
         [0046]      FIG. 9  is a graphical chart showing the rigidity of seat cushion  200 , vs. the distance of positions on seat cushion  200  from the front end of seat cushion  100 . Part P exemplifies the rigidity of frontal portion  230 , part Q exemplifies the rigidity of middle portion  220  and part R exemplifies the rigidity of rear portion  210 . 
         [0047]    Reference is now made to  FIG. 10 , which is a perspective view of seat cushion  300  (having the cushion cover removed). Seat cushion  300  has a generally rectangularly shaped body that includes frontal portion  320  and rear portion  310 , all of which are made of resilient materials. Frontal portion  320  is more rigid than rear portion  310 . 
         [0048]    Rear portion  310  has a front end and a rear end, wherein the rear end of rear portion  310  is proximal to back  30  of wheelchair  20  and the front end of rear portion  310  is most distal from back  30  of wheelchair  20 . Frontal portion  320  has a front end and a rear end, wherein the front end of frontal portion  320  is most distal from back  30  of wheelchair  20  and the rear end of frontal portion  320  is most proximal to back  30  of wheelchair  20 . The front end of rear portion  310  is disposed adjacent to the rear end of front portion  320  and preferably, securely attached to the rear end of front portion  320 . 
         [0049]    Frontal portion  320  further includes a divider  340 , having a front end and a rear end, wherein divider  340  is more rigid than frontal portion  320 ; wherein the front end of divider  340  is preferably flush with the front end of frontal portion  320 , and the rear end of divider  340  is preferably flush with the rear end of frontal portion  320 . Preferably, divider  340  laterally subdivides frontal portion  320  into two generally symmetric sections  320   a  and  320   b.  Divider  340  further enhances seat cushion  300  such that divider  340  further the sliding forward of a seated individual  10 . 
         [0050]    Reference is now made to  FIG. 11 , which is a perspective view illustration of a seat cushion  400  (having the cushion cover removed), according to another variation of the present invention, seat cushion  400  being in a non-seated state.  FIG. 12  is a perspective view illustration of seat cushion  400  being in a seated state. Seat cushion  400  has a generally rectangularly shaped body that includes frontal portion  420  and rear portion  410 , all of which are made of resilient materials. Frontal portion  420  is more rigid than rear portion  410 . 
         [0051]    Rear portion  410  has a front end and a rear end, wherein the rear end of rear portion  410  is proximal to back  30  of wheelchair  20  and the front end of rear portion  410  is most distal from back  30  of wheelchair  20 . Frontal portion  420  has a top face, a bottom face, a front end and a rear end, wherein the front end of frontal portion  420  is most distal from back  30  of wheelchair  20  and the rear end of frontal portion  420  is most proximal to back  30  of wheelchair  20 . The front end of rear portion  410  is disposed adjacent to the rear end of front portion  420  and preferably, securely attached to the rear end of front portion  420 . 
         [0052]    Seat cushion  400  further includes a divider  440 , which divider  440  is more rigid than frontal portion  420 . Divider  440  is disposed adjacently above frontal portion  420  and a top layer  450 , attached to the top surface frontal portion  420 . Divider  440  is extends from approximately the front end of frontal portion  420  to generally the rear end of frontal portion  420 . Preferably, top layer  450  is less rigid than divider  440 . Preferably, divider  440  is disposed generally at the lateral middle of frontal portion  420 . 
         [0053]    When an individual  10  seats on top of top layer, top layer  450  presses divider  440  downwardly, against divider  440  and thereby against the top face of front portion  420 . Since top layer  450  is softer than divider  440 , a protrusion  452  is formed in the front section of top layer  450 . Divider  440  further enhances seat cushion  400  as protrusion  452  further prevents the sliding forward of the seated individual  10 . 
         [0054]    Reference is now made to  FIG. 12 , which is a perspective view illustration of a seat cushion  500  (having the cushion cover removed), according to still another variation of the present invention, seat cushion  500  being in a non-seated state.  FIG. 13  is a perspective view illustration of seat cushion  500  being in a seated state. Seat cushion  500  has a generally rectangularly shaped body that includes frontal portion  520  and rear portion  510 , all of which are made of resilient materials. Frontal portion  520  is more rigid than rear portion  510 . 
         [0055]    Rear portion  510  has a front end and a rear end, wherein the rear end of rear portion  510  is proximal to back  30  of wheelchair  20  and the front end of rear portion  510  is most distal from back  30  of wheelchair  20 . Frontal portion  520  has a top face, a bottom face, a front end and a rear end, wherein the front end of frontal portion  520  is most distal from back  30  of wheelchair  20  and the rear end of frontal portion  520  is most proximal to back  30  of wheelchair  20 . The front end of rear portion  510  is disposed adjacent to the rear end of front portion  520  and preferably, securely attached to the rear end of front portion  520 . 
         [0056]    Seat cushion  500  further includes a divider  540 , which divider  540  is more rigid than frontal portion  520 . Divider  540  is disposed adjacently below frontal portion  520  and bottom layer  550 , pressing divider  540  upwards, against the bottom face of front portion  520 . Preferably, bottom layer  550  is more rigid than divider  540 . Preferably, divider  540  is disposed generally at the lateral middle of frontal portion  520 . 
         [0057]    When an individual  10  seats on top of seat cushion  500 , the flat hard top of wheelchair  20  presses bottom layer  550  upwardly, in the general direction  545 . Thereby, bottom layer  550  presses divider  540  upwardly, against the bottom face of front portion  520 . Since front portion  520  is softer than divider  540 , divider  540  pushes the middle section of the bottom face of front portion  520  upwardly, whereby causing the middle section of the top face of front portion  520  upwardly, forming a protrusion  522  of the top face of front portion  520 . Divider  540  further enhances seat cushion  500  as protrusion  522  further prevents the sliding forward of the seated individual  10 . 
         [0058]    In variations of the present invention and according to the preferred embodiment of the present invention, bottom layer  550  is substantially more rigid than divider  540 . At assembly time, divider  540  is pressed upwardly by bottom layer  550 , in the general direction  545 , against the bottom face of front portion  520 . Since front portion  520  is softer than divider  540 , divider  540  pushes the middle section of the bottom face of front portion  520  upwardly, whereby causing the middle section of the top face of front portion  520  upwardly, forming a protrusion  522  of the top face of front portion  520 . All layers are securely attached in that position, for example by glue. 
         [0059]    It should be noted that in other variations of the seat cushion of the present invention, the seat cushion is composed of any number of multiple resilient portions, each having a density that decreases from portion to portion, as the portion is disposed nearer to back  30  of wheelchair  20 . 
         [0060]    It should be noted that the elastic portions of the seat cushion of the present invention can be made of any elastic materials, including, but not limited to, elastomeric materials, for example, viscoelastic materials. 
         [0061]    In variations of the present invention, the rigidity of all portions of seat cushion  500 ,  400 ,  300 ,  200  and/or seat cushion  100  are fitted to the weight range of seated individual  10 . 
         [0062]    In variations of the present invention, more rigid margins are add to the sides of seat cushion  500 ,  400 ,  300 ,  200  and/or seat cushion  100 , to prevent sideways sliding of a seated individual  10 . 
         [0063]    In variations of the present invention, more rigid margins are add to the sides of seat cushion  500 ,  400 ,  300 ,  200  and/or seat cushion  100  are coupled to a chair which is not a wheelchair, to prevent seated individual  10  from sliding off the seat. 
         [0064]    Preferably, seat cushions  100 ,  200 ,  300 ,  400  and/or  500  are securely attached to back  30  of wheelchair  20 . 
         [0065]    The invention being thus described in terms of several embodiments and examples, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art.