Seat cushion

Abstract

A seat cushion comprises a relief portion to selectively provide cushioning to a user's sitz bones received when the user is seated on a seating surface. The selective cushioning provided by the relief portion to the user's sitz bones can be greater than cushioning provided by the remainder of the seat cushion to portions of the user's body other than the sitz bones. The relief portion can be in the form of a pair of relief pockets offset to be depressed below the second surface. A resiliency of the relief pockets is different from a resiliency of areas of the second surface surrounding the relief pocket. The first surface and the second surface of the seat cushion can be contoured so as to form a central core, a relief portion substantially surrounding the central core, and an outer portion defined so as to surround the relief portion.

1 . A seat cushion, comprising:
 a first surface providing a seating surface to sit on; and   a second surface opposite to the first surface, the second surface having a pair of relief pockets,   the relief pockets being configured to provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief pockets, the second surface having variable resiliency such that a resiliency of the relief pockets is different from a resiliency of areas of the second surface surrounding the relief pockets.   
     
     
         2 . The seat cushion of  claim 1 , wherein the relief pockets are adapted to receive a user's weight acting through the user's sitz bones when the user is seated on the seating surface, the relief pockets being deformable in response to the user's weight, the deformation of the relief pockets being greater than a deformation of the areas of the second surface surrounding the relief pockets, when a force equivalent to the user's weight is applied on the areas of the second surface surrounding the relief pockets. 
     
     
         3 . The seat cushion of  claim 2 , wherein the relief pockets have an initial shape when the user is not seated on the seating surface, the resiliency of the relief pockets permitting the relief pockets return to their initial shape once a user seated in the seating surface rises from the seating surface. 
     
     
         4 . The seat cushion of  claim 2 , wherein the areas surrounding the relief pockets have a deformation negligible relative to the deformation of the relief pockets, when the force equivalent to the user's weight is applied on the areas of the second surface surrounding the relief pockets. 
     
     
         5 . The seat cushion of  claim 1 , wherein the seat cushion is fabricated as a unitary piece by molding a polymer material. 
     
     
         6 . The seat cushion of  claim 5 , wherein the polymer material forms a closed-cell foam after fabrication of the seat cushion, the polymer material being ethylene-vinyl acetate. 
     
     
         7 . The seat cushion of  claim 5 , further comprising a plurality of ribs provided on the second surface, the plurality of ribs facilitating flow of polymer material and heat transfer during fabrication. 
     
     
         8 . A seat cushion, comprising:
 a first surface providing a seating surface to sit on;   a second surface opposite to the first surface, the first surface and the second surface each being contoured so as to form:
 a central core defined about a seat axis, 
 a relief portion extending radially around the seat axis so as to substantially surround the central core, the relief portion being configured to receive and provide cushioning to a user's sitz bones received when the user is seated on the seating surface, and 
 an outer portion defined so as to surround the relief portion such that the relief portion is positioned radially between the central core and the outer portion, 
 the relief portion being configured so as to be deformable when a user's weight is supported by the seating surface, the deformation of the relief portion being substantially greater than a deformation of the central core and/or the outer portion when a force equivalent to the user's weight is applied on the central core and/or the outer portion. 
   
     
     
         9 . The seat cushion of  claim 8 , wherein the seat cushion is rotationally symmetric about the seat axis. 
     
     
         10 . The seat cushion of  claim 8 , wherein the relief portion extends a 360 degrees surrounding the seat axis. 
     
     
         11 . The seat cushion of  claim 8 , wherein the seat cushion has a thickness, and the relief portion has a relief portion thickness, the relief portion thickness being between about 20% and about 70% of the thickness of the seat cushion. 
     
     
         12 . The seat cushion of  claim 8 , wherein the seat cushion is contoured such that the first surface corresponding to the corresponding to the central core being concave and a portion of the second surface corresponding to the central core being convex or generally planar when viewed from a plane parallel to the seat axis. 
     
     
         13 . The seat cushion of  claim 8 , wherein the seat cushion is contoured such that the first surface of the seat cushion at a location corresponding to the relief portion being generally convex and the second surface of the seat cushion at a location corresponding to the relief portion being generally convex when viewed from a plane parallel to the seat axis. 
     
     
         14 . The seat cushion of  claim 8 , wherein the relief portion having a relief portion width, and the seat cushion has a representative dimension, the relief portion width being between about 20% and about 70% of the representative dimension. 
     
     
         15 . The seat cushion of  claim 14 , wherein the seat cushion is disc-shaped and the representative dimension is a radius. 
     
     
         16 . A seat cushion, comprising:
 a first surface providing a seating surface to sit on;   a second surface opposite to the first surface, the second surface having a relief portion,   the relief portion being shaped and sized to selectively provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief portion,   the selective cushioning provided by the relief portion to the user's sitz bones being greater than cushioning provided by areas other than the relief portion to portions of the user's body other than the sitz bones that are in contact with the seating surface.   
     
     
         17 . The seat cushion of  claim 16 , wherein the relief portion occupies an area of between about 10% and about 50% of a total surface area of the second surface. 
     
     
         18 . The seat cushion of  claim 16 , wherein the relief portion comprises a pair of relief pockets separated by a relief pocket spacing, the relief pockets having a generally asymmetrically shape, the relief pocket spacing corresponding to an average sitz bone spacing of an adult male or female user. 
     
     
         19 . The seat cushion of  claim 18 , wherein the relief pockets are of a size configured to accommodate a standard deviation of about +/−1 inch relative to the average sitz bone spacing of an adult male or female user. 
     
     
         20 . The seat cushion of  claim 18 , wherein the relief pockets have a depth of between about 5% and about 50% of an overall depth of the seat cushion, and a width of between about 5% and about 50% of an overall width of the seat cushion. 
     
     
         21 . The seat cushion of  claim 18 , wherein the relief pockets have a thickness of between about 20% and about 70% of an overall thickness of the seat cushion. 
     
     
         22 . The seat cushion of  claim 21 , wherein the thickness of the relief pockets being variable whereby, the thickness of the relief pockets being greater near a back edge of the seat cushion than the thickness of the relief pockets near a front edge of the seat cushion. 
     
     
         23 . The seat cushion according to  claim 21 , wherein the seat cushion is supported by and/or connected to a seat pan of a pivot seat, the seat cushion having a front edge that contacts a portion of a user's thigh when a user is seated thereon, and the front edge of the seat cushion extending past a front edge of the seat pan, the front edge of the seat cushion being cantilevered relative to the seat pan. 
     
     
         24 . The seat cushion of  claim 23 , wherein a substantial portion of the seat cushion is resilient with respect to the seat pan. 
     
     
         25 . The seat cushion of  claim 23 , further comprising a one or more connectors located on the second surface of the seat cushion to permit connection of the seat cushion to the seat pan. 
     
     
         26 . The seat cushion of  claim 23 , wherein the seat pan has a first surface contoured so as to generally conform to a contour of the second surface of the seat cushion. 
     
     
         27 . The seat cushion of  claim 26 , wherein the seat pan has a seat pan depth and a seat pan width, and the seat cushion has a seat cushion depth and a seat cushion width, wherein the seat pan width generally equals the seat cushion width, and the seat pan depth is generally less than the seat cushion depth. 
     
     
         28 . The seat cushion of  claim 27 , wherein a difference between the seat cushion depth and the seat pan depth being equal to an offset distance. 
     
     
         29 . The seat cushion of  claim 28 , wherein the offset distance is generally constant along a widthwise direction between a right edge and a left edge of the seat cushion, the right edge and the left edge each being lateral to the front edge of the seat cushion. 
     
     
         30 . The seat cushion of  claim 23 , wherein the seat pan has a generally planar first surface, and the seat cushion has a generally non-planar second surface.