Patent Publication Number: US-6219867-B1

Title: Cushion pad with enhanced conformability

Description:
The present invention generally relates to cushions and is more particularly directed to a cushion pad having enhanced conformability. Still more particularly the present invention is directed to a keyboard wrist pad having different zones of lateral movement and conformability. 
     Many cushions or pads for the support of a user are more suitable if the user does not have to slide along the pad in order to accommodate a change of position of a user&#39;s arm, leg or hand. That is, it is preferable that the pad accommodate such movement by lateral movement of the pad surface in contact with the user and or a change in conformability of the pad. This is particularly true in the case of keyboard wrist cushions or pads. 
     A number of cushions have been developed for use along the front edge of a keyboard, which is operated by a user&#39;s fingers or hand, such as in the case of a computer mouse. 
     Proper support is necessary, particularly in conjunction with repetitive computer keyboard operation, in order to prevent a number of medical problems which have been generally known as “carpal tunnel syndrome”. A great number of cushions have been developed which provide layers of cushioning materials, including gels. Many attempts have been made to enlarge the degree of movement of a supported wrist relative to the surface on which the wrist is supported. For example, see U.S. Pat. No. 5,713,544 which utilizes a pad having a layer of stable isomeric block polymer gel, in order to afford supporting a user&#39;s wrist and afford significant motion on the top surface of the pad, with the supported wrist relative to a bottom surface of the pad in a horizontal plane. 
     While greater lateral movement is afforded by a wrist rest assembly as set forth in the hereinabove referenced patent, the use of gels alone is limiting in the amount of lateral movement possible. 
     The present invention is directed to a cushion which provides wide lateral movement support, in addition to providing amusement for the user due to the internal structure of the cushion. 
     SUMMARY OF THE INVENTION 
     A cushion pad in accordance with the present invention generally includes an elastomer having the physical properties of flexibility and compressibility in the range of flexibilities and compressibilities of stable isomeric block polymer gels. The elastomer includes an exterior surface and a cavity therein along with film means for encapsulating the elastomer. The film means includes the physical properties of flexibilities to enable uninhibited flexure and compression of the elastomer by a user. 
     Importantly, means, disposed in the elastomer cavity, is provided for enhancing exterior surface movement of the elastomer upon shear force applied thereto by the user and for enhancing conformity of the pad upon compressive force applied thereto by the user. 
     In one embodiment of the present invention, the means for enhancing exterior surface movement and enhancing conformity of the pad comprises a thixotropic gel disposed in the elastomer cavity. The thixotropic property of the gel enables the gel to become fluid when force is applied and then becomes semisolid again. 
     The combination of the elastomer and thixotropic gel provides best conformity when the elastomer has a thickness, measured between the exterior surface and the cavity of at least about ½ inch to about 2 inches. 
     Further, the film means, elastomer and thixotropic gel may be transparent, thus enabling observance of a decorative object suspended within the thixotropic gel. 
     In another embodiment of the present invention, the means for enhancing exterior surface movement and enhancing conformity of the pad cushion comprises a liquid. In addition, the cushion pad in accordance with the present invention may include a polyurethane film having a thickness of between about 1 mil and about 5 mils. These limitations are important in providing the required physical properties of flexibility to enable uninhibited flexure and compression of the elastomer by a user as hereinabove noted. 
     Still more particularly, the elastomer has a thickness measured between the top surface and the cavity of at least about 1 inch. This thickness is important in establishing the resilient properties of the wrist cushion. With the thickness range as hereinabove cited, the wrist cushion retains the elasticity, resilience and compressibility of the elastomer material, despite the liquid filled cavity. Further, this thickness provides a means for enabling self-sealing in order to prevent the liquid from. leaking or reaching the exterior surface. 
     Accordingly the liquid, or thixotropic, filled cavity enables the wide lateral movement provided by the keyboard wrist cushion in accordance with the present invention. 
     In one embodiment of the present invention, air pockets disposed in the elastomer cavity provide a means for controlling, in combination with the elastomer, the overall compressibility of the wrist cushion. Because the air pockets are compressible, they can be used to modify the compressibility of the liquid, or thixotropic gel-filled cavity, of course, in combination with the elastomer itself. 
     Also, in accordance with the present invention, the film, elastomer and liquid, a thixotropic gel, may be transparent and the wrist cushion further comprises decorative objects suspended in the liquid within the cavity. The transparency enables the visual observation of the decorative objects by the user, particularly when used by the user as hereinabove noted. 
     The decorative objects can be moved within the cavity and liquid, a thixotropic gel, by compression forces applied to the cushion by the user. This movement is enhanced when used in combination with air pockets in the cavity. 
     Further, in accordance with the present invention, the elastomer includes a plurality of cavities therein, each of which may include a decorative object. In addition, at least one of the elastomeric cavities may be connected with another cavity for enabling movement of the decorative objects within the liquid from one cavity to another by compressive forces applied to the cushion by the user. In addition, multiple cavities enable general control of the resiliency of the cushion. 
     In yet another embodiment of the present invention, a keyboard wrist pad is provided which includes an elastomer having the physical properties of flexibility and compressibility in the range or flexibilities and compressibilities of stable elastomeric block polymer gels, the elastomer has a top surface and means defining a plurality of cavities therein, for controlling lateral top surface movement of different zones of said elastomer upon shear force applied thereto by a user. 
     Film means are provided for encapsulating said elastomer, said film means having physical properties of flexibility to enable uninhibited flexure and compression of said elastomer by the user. 
     Importantly, thixotropic or liquid means, disposed in each of the elastomer cavities is provided for enhancing the lateral top surface movement of said elastomer upon shear force applied thereto by the user and for enhancing conformity of the pad upon compressive force applied thereto by the user. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention may be more clearly understood with reference to the following detailed description in conjunction with the appended drawings, of which: 
     FIG. 1 is a perspective view of the present invention; 
     FIG. 2 is a cross sectional view of the cushion shown in FIG. 1 taken along the line  2 — 2  showing in cross section any elastomer encapsulated by a film, with the elastomer having a cavity therein, which is liquid filled; and 
     FIG. 3 is a cross sectional view of the cushion shown in FIG. 1 taken along the line  3 — 3  showing a plurality of interconnected separate elastomer cavities along with a decorative object which may be moved from one cavity to another, as shown in dash line, by compressive forces from a user&#39;s wrist. 
    
    
     DETAILED DESCRIPTION 
     With reference to FIG. 1, there is shown a cushion pad  10  in accordance with the present invention, which, as is more particularly shown in FIG. 2, includes an elastomer  14  and a film  16  which provides a means for encapsulating the elastomer. 
     In a generally elongate configuration, as shown in the Figures, the pad is suitable for a keyboard wrist pad. It should be appreciated, however, that other pad shapes (not shown) may be utilized depending on the intended use of the pad. 
     A cavity  20  formed within the elastomer  14 , may include either a thixotropic gel or a liquid which provides a means for enhancing lateral exterior or top surface  26  movement (as indicated by arrows  30 ,  32 ) upon shear force applied to the surface  26  by a user and enhancing conformity of the pad  10  upon compressive force applied to the surface  26  by the user. 
     Encapsulation of the elastomer is important for providing a desired textured surface as well as preventing any leakage of plasticizing oil which may be utilized in the elastomer. 
     The elastomer  14  may be of any suitable type such as, for example, a stable isomeric block polymer gel similar to the gel described in U.S. Pat. No. 3,676,387. This patent is incorporated herewith in its entirety for the purpose of describing a suitable type of gel for incorporation into the present invention. 
     Generally, the gels are of polymer-oil combinations. Specifically, the elastomer  14  has the physical properties of flexibility and compressibility in the range of flexibilities and compressibilities of the stable elastomer block polymer gels such as set forth in U.S. Pat. No. 3,676,387. 
     With reference to FIGS. 2 and 3, the transparent film  16  may be of urethane, or polyurethane film, which encapsulates the transparent elastomer  14 . The film  16  thickness as hereinabove noted is preferably between about 1 mil and about 5 mils in order to encapsulate the elastomer  14 , yet have a resiliency which enables free gel-like movement, or compression, or depression of the elastomer  14  by a user&#39;s wrist  36 . See FIG.  3 . 
     That is, the film  16  has physical properties of flexibility because of its thickness to enable uninhibited flexure and compression of the elastomer  14  by the user  36 . Film  16  thickness beyond this range has not been found to be effective in maintaining the gel-like property of the elastomer  14  while providing encapsulation of the elastomer  14 . 
     As hereinabove noted, the elastomer  14  includes a cavity  20  which is filled with thixotropic gel, a colloid, or a liquid  22 , preferably an oil, such as, for example, a mineral oil. The colloid may be a suspension of solids in liquid or an emulsion of two liquids which have properties suitable for enhancing conformity of the pad  10  upon compressive force applied thereto by the user. 
     The thixotropic gel may be any suitable thixotropic gel such as, for example, described in U.S. Pat. No. 4,200,561, which is incorporated herewith in it&#39;s entirety for the purpose of describing suitable thixotropic gels. The gel or liquid  22  filled cavity  20  enhances the lateral top surface movement indicated by the arrows  30 ,  32  by a shear force in the direction of arrows  30 ,  32  applied to the top surface  26  of the cushion  10 . A thixotropic gel provides unique properties for the pad  10  because of its being a semisolid colloid when undisturbed, but flowing readily when subjected to stress. 
     An elastomer, a thickness indicated by the arrow  40 , between the cavity  20  and the top surface  26 , is greater than about ½ inch to about 2 inches in order to maintain the flexibility and compressibility of the cushion  14 . Utilizing an elastomer having a width of about 3 to about 5 inches, a user&#39;s wrist can be laterally moved up to about 1 to 2 inches without slipping from the top surface  26 . 
     In addition, an elastomer of this thickness provides a self-sealing feature. If the elastomer is punctured or ruptured in some manner, its resiliency causes closure of the puncture or rupture in order to prevent leakage of the liquid  22  or seepage of the thixotropic gel. 
     The compressibility of the cushion may be further enhanced by providing air pockets  42  within the cavity  20 . Because these air pockets are compressible, the overall feel compressibility and flexure properties of the cushion  10  may be modified. These air pockets take up between about 25% and about 75% of the total volume of the cavity  20 . A desirable air pocket volume is about 50% of the total volume. 
     In order to provide zonal control of cushion  10  resiliency, the cushion  10  may include multiple cavities  20 ,  44 ,  46  as shown in FIG. 3, corresponding air pockets  50 ,  52  being present in the cavities  44 ,  46  and separated from one another by constricted, narrowing or isthmus areas  56 ,  58 . By incorporation of different size air pockets  42 ,  50 ,  52 , zonal compressibility properties may be provided across the cushion  10 . 
     Further, the control of lateral movement of the cushion  10  surface  26  is controlled by the size of the various cavities  42 ,  50 ,  52 . That is, a center portion  64  may have greater lateral motion than side portions, or zones,  66 ,  68 . This is important in providing a controlled lateral wrist movement afforded by the cushion  10  when disposed in front of the keyboard, not shown, to facilitate the striking of certain keys (not shown). Such control may also be afforded by utilizing different liquids or thixotropic gels in the various cavities  42 ,  50 ,  52 . 
     In accordance with the present invention, if the cavities are not interconnected liquid may be used in one or more of the cavities  42 ,  50 ,  52  along with the thixotropic gel in others of the cavities  42 ,  50 ,  52 . 
     Yet another feature of the present invention is shown and illustrated in FIGS. 2 and 3. By utilizing a transparent urethane film  16 , elastomer  14  and liquid  22 , the viewing of the decorative object  70  disposed and suspended within the liquid  22  can be realized. 
     Movement of the decorative object  70  within the liquid  20  or, for that matter, within the liquid  72 ,  74  disposed within the cavities  44 ,  46 , respectively, through the isthmus  56 ,  58 , can be actualized by compressive forces supplied to the cushion top surface  26 , at the center zone  64 , or side zone  66 ,  68  by the wrist  36 . 
     Thus, movement of the user&#39;s wrist  36 , when in an operative compressive relationship with the cushion  10  and providing shear forces thereon to cause lateral movement, also causes a movement of a decorative object  70  within the cavity  20  or between the cavities  20 ,  44 ,  46 , with such movement being further enhanced by the air pockets  42 ,  50 ,  52  disposed respectively in the cavities  20 ,  44 ,  46 . This feature is also available with the proper selection of the thixotropic gel. 
     Alternatively, the liquid or gel  22  may be semi-translucent with opaque swirls or the like therein in order to provide a different visual effect. 
     The process of forming the cushion  10  is through the process set forth in U.S. Pat. No. 5,679,193 entitled, METHOD OF MANUFACTURING A GEL CUSHION; U.S. Pat. No. 5,756,184 entitled, GEL CUSHION; and in U.S. patent application Ser. No. 08/856,775 filed May 15, 1997 entitled, CUSHION MANUFACTURING METHOD. Both of these referenced patents and the application are incorporated herewith in their entirety by this reference thereto, for illustrating the manner in which the gel cushion in accordance with the present invention may be manufactured. 
     Although there has been hereinabove described a keyboard wrist cushion in accordance with the present invention, for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention as defined in the appended claims.