There are untold types of seating chairs in existance today. Most of them, for one reason or another, do not provide enough of the essential elements needed within a chair to easily hold proper torso angulation and provide long term proper spinal support and positioning. Nor do these chairs allow for the proper relief for certain body areas which would benefit by such relief. Nor do these chairs aid in maintaining or promoting proper body position for prolonged periods of time thereby preventing spinal distortion or possible spinal deformation or pathogenesis. Nor do these chairs give enough body support in the proper weight bearing areas. Nor do these chairs provide comprehensive back support when the seated subject moves about within his seated position for purposes necessary to his daily occupation.
With the use of modern materials and techniques, and also careful analysis of postural needs of the torso for various sitting occupations, these elements can now be incorporated into a type of chair, or similiarily related types of chairs.
There have been endeavors within the handicap and disability health fields to develop custom molding methods and fabricate a chair with designs which will provide some of the above mentioned elements within said chair. For many years, in the field of orthotics, there have been endeavors to take impressions of pertinent human anatomical parts using thin flexible bags filled with small styrofoam pellets or chemically active resin particles. A coalescing force is applied to the beads within the bag using a central vacuum source. This constricts the beads together within the bag thereby keeping them in the shape of the form impressed upon the bag apparatus.
Specifically, various custom molding methods, or variations thereof, have been described in patents by Rogers Jr. in U.S. Pat. No. 4,347,213, Davis in U.S. Pat. No. 4,327,046 and Silverman, U.S. Pat. No. 4,615,856, whereby bags are filled with small pellets to impress an area of human anatomy and then coalesce the image by applying a vacuum to the bag. Rogers Jr. and Silverman form positive molds by applying wet plaster bandages to the impression and waiting for the set of the plaster. Davis uses an active resi system within the particle bag itself which actually solidifies to form the completed seating appliance.
Morton, U.S. Pat. No. 2,847,061, discloses the use of thin rubber cushions moderately inflated with air to allow a subject to sit in and thereby impress their image into the bag . This is done while the subject sits upon strips of meshed fabric coated with a setting material. The fabric impregnated with the setting material is displaced to the desired anatomical shape by the deformation within the impression bag. A positive mold was thereby obtained after the set of the material.
In other previous related technique, Webster, U.S. Pat. No. 3,662,057, uses sheets of moldable thermoplastic materials to directly mold around various human anatomical areas for formation of a splint or cast for healing of traumatized human anatomical parts.