Patent ID: 7380376

Claim:
A non-slip structure comprising a metal plate lying in a plane and having at least one raised unit, each unit comprising at least two protruding partially spherical portions having the same configuration arranged radially with respect to each other to provide a center section surrounded by said at least two protruding portions, each of said portions being formed by shearing said plate and each portion having two lateral side surfaces and an end surface facing said center section, the bottom edges of said lateral side and end surfaces being connected to said metal plate, whereby no gap or any through hole is produced between said metal plate and said bottom edges of said surfaces, said two lateral side surfaces curving upwardly from the plane of said metal plate and tapering toward each other in the direction of said end surface, said end surface extending between said lateral side surfaces at the highest point of said protruding portion so that each portion has a general fan shape as viewed from the top, each of said portions extending above said metal plate by a height which is less than the thickness of said plate to eliminate a passage through said plate, the lateral side surfaces of adjacent units forming an open drainage path of uniform width extending from said center section.