Draw string fitted sheet with curved hem for even tension

A fitted sheet for a mattress;

• said mattress having a volume;
• said mattress having a set of sides, a top, and a bottom;
• said bottom and said sides intersecting to form a set of lower edges;
• each of said lower edges having a midpoint;
• said lower edges intersecting to form a set of lower corners;
• said sheet fashioned with a main chamber to substantially envelope said mattress, and a main opening to allow said mattress to enter said main chamber;
• said main chamber having a variable volume;
• said main opening having a peripheral edge with a hem thereon;
• at least one part or all said hem forming an elongated hollow cavity substantially parallel and adjacent to said sheet edge;
• at least one part or all of said cavity containing at least one drawstring therein encircling said main opening;
• said main opening is forced to a more closed size substantially under said mattress by a first tension force in said drawstring capturing said mattress inside said chamber and causing said main chamber volume to shrink around said mattress;
• said drawstring further generating a second tension force in said sheet as said sheet resists further shrinkage as said chamber volume approaches that of said mattress volume;
• said second tension force is generated in said sheet wherever there is a deviation of said drawstring from a substantially straight path;
• said second tension force holds said sheet in a position substantially enveloping said mattress in such a way as to substantially cover said mattress top, and said sides with all or part of said sheet edge, said hem, and said drawstring in a position adjacent to and substantially within said mattress lower edges;
• a set of portions of said sheet edge supporting said hem containing said drawstring and adjacent to said mattress lower edges having an edge shape means for substantially diverting said drawstring deviation from a straight path toward and distributing said deviation along said set of portions of said sheet edge adjacent to said mattress lower edges whereby said second tension force is substantially generated along said portions of said sheet edge adjacent to said mattress lower edges.

A cover for a substantially prismatic object;

• said prismatic object having a set of rectangular sides, a polygonal top, and a polygonal bottom;
• said prismatic object polygonal top, and said polygonal bottom each having a set of edges, and a set of corners;
• each of said polygonal bottom edges having a midpoint;
• said cover fabricated from a flexible membrane material having at least one edge;
• said cover formed with a chamber to substantially envelope said object;
• said chamber having a variable volume;
• said chamber having an opening formed by said cover edge to allow entrance of said object;
• said cover having at least one flexible tubular member attached adjacent to said edge;
• said tubular member having a diameter;
• said tubular member having a length larger than said tubular member diameter;
• at least one part or all of said tubular member containing at least one drawstring therein;
• said at least one drawstring encircles said chamber opening;
• said at least one drawstring under a first tension force closes said opening restraining said object inside said chamber generating a second tension force in said cover decreasing said volume of said chamber and tightening said cover around said object;
• said second tension force is induced in said cover wherever said at least one drawstring forms a first curve;
• said first curve translated to said at least one drawstring by an edge shape means for substantially directing said first curve to and distributing said first curve along a plurality of said prismatic object bottom edges whereby said cover is held in position by said second tension forces generated substantially adjacent to and along a plurality of said prismatic object polygonal bottom edges.