Clasp utilizing attractive force of permanent magnet

Claim 1

A magnetic fastener comprising: (a) a first fastening element, including a permanent magnet having oppositely facing pole faces of opposite polarity and at least one peripheral edge, said magnet having a hole extending between the first pole face and the second pole face; a first ferromagnetic plate in contact on one face thereof with said first pole face; a first fastening means extending from the other face of said first ferromagnetic plate; a first ferromagnetic rod disposed within and coaxial with said hole and secured to said one face of said first ferromagnetic plate; a magnetic shielding ferromagnetic plate in contact with said second pole face and having an opening passing therethrough, which opening is coaxial with said hole; and a nonmagnetic housing having an edge portion surrounding the at least one peripheral edge of said permanent magnet, inwardly directed extensions on said edge portion for securing said first ferromagnetic plate and said magnetic shielding ferromagnetic plate to said permanent magnet, said extension on the edge portion of said housing adjacent said magnetic shielding ferromagnetic plate extending over said shielding plate and having a protruding rim at its periphery where it joins said edge portion to form a dish-shaped upper surface, and an aperture coaxial with said hole in said upper surface; and (b) a second fastening element detachably engageable with said first fastening element, including a second ferromagnetic plate having a peripheral size smaller than said rim; a second fastening means secured to said second ferromagnetic plate; and a second ferromagnetic rod secured to said second ferromagnetic plate, so that when the first and second fastening elements are engaged, said first ferromagnetic rod projects into said hole and contacts said second ferromagnetic rod and said second ferromagnetic plate contacts said dish-shaped upper surface of said housing within said rim.