Magnetic key device

Claim 2

A key device comprising: a retaining member (22, 122) of magnetic material and having a bore therein; a drive member (24); a follower member (26), said drive member (24) being slideably and coaxially engaged with said follower member (26) and said follower member (26) being slideably engaged through the bore in said retaining member (22, 122); a permanent magnet (38) attached to said follower member (26) and attracting said retaining member (22,122) to serve as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member to retain said magnet in position; a spring (28a) interposed between and urging apart said drive (24) and follower (26) members, said spring being compressed upon depression of said drive member to accumulate energy, said magnet snapping away from said retaining member when said accumulated energy overcomes the attraction force of said permanent magnet to said retaining member, and the magnetic attraction of said magnet to said retaining member serving as the sole returning force when said depression force is released, to return said magnet into direct contact with said retaining member.

Claim 3

A key device according to in claim 1 wherein a recess is formed in said retaining member for receiving therein said permanent magnet.

Claim 4

A key device according to claim 1 wherein said drive and follower members include means to limit movement thereof relative to said retaining member.

Claim 5

A key device according to claim 1 including signal generating means spaced from said magnet, said magnet moving toward said signal generating means when snapped away from said retaining member to cause said signal generating means to generate an electrical signal.

Claim 6

A key device according to claim 4 including a projection (44) extending from the center of said magnet (38) on the side thereof remote from said retaining member to concentrate the magnetic flux.

Claim 7

A key device comprising: a retaining member (22, 122) of magnetic material; a drive member (24); a follower member (26) slideably engaged with said drive member (24), said drive member (24) and said follower member (26) being slideably mounted to said retaining member (22, 122) in coaxial relation with each other; a permanent magnet (38) coupled to said follower member (26) for attracting said follower member (26) toward said retaining member (22, 122) and serving as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member (22, 122) to hold said follower member in position; a spring (42) interposed between and urging apart said drive member (24) and follower member (26) and being compressed upon depression of said drive member to accumulate energy; a coil (344) spaced from said follower member (26) and spaced from said magnet (38); said spring (42) being compressed upon depression of said drive member (24) by a predetermined amount, said magnet (38) and follower member (26) snapping away from said retaining member and moving quickly relative to said coil (344) when the energy accumulated in said spring (42) overcomes the attraction force between said magnet and said retaining member the flux variation in said coil due to the displacement of said follower member and permanent magnet being detected as a voltage variation across said coIl, and when said depression force is released, the magnetic attraction of said magnet to said retaining member serving as the sole returning force t o return said magnet into direct contact with said retaining member and to return said follower member back to its inoperative position.

Claim 8

A key device comprising: a retaining member (22, 122) of magnetic material; a drive member (24); a follower member (26) slideably engaged with said drive member (24), said drive member (24) and said follower member (26) being slideably mounted to said retaining member (22, 122) in coaxial relation with each other; a permanent magnet (38) coupled to said follower member (26) for attracting said follower member (26) toward said retaining member (22, 122) and serving as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member (22, 122) to hold said follower member in position; a spring (42) interposed between and urging apart said drive member (24) and follower member (26) and being compressed upon depression of said drive member to accumulate energy; a coil (344) spaced from said follower member (26) and spaced from said magnet (38); said spring (42) being compressed upon depression of said drive member (24) by a predetermined amount, said magnet (38) and follower member (26) snapping away from said retaining member and moving quickly relative to said coil (344) when the energy accumulated in said spring (42) overcomes the attraction force between said magnet and said retaining member the flux variation in said coil due to the displacement of said follower member and permanent magnet being detected as a voltage variation across said coIl, and when said depression force is released, the magnetic attraction of said magnet to said retaining member serving as the sole returning force t o return said magnet into direct contact with said retaining member and to return said follower member back to its inoperative position.

Claim 9

A key device according to claim 6 wherein said coil is disposed so as to oppose said magnet and said follower member in the direction of movement thereof from said retainer member, said magnet snapping toward said coil when said accumulated spring energy overcomes the attraction force between the magnet and the retaining member to close a magnetic field therewith.

Claim 10

A key device according to claim 7 wherein said magnet impacts said coil after it snaps away from said retaining member.

Claim 11

A key device according to claim 6 wherein said coil is disposed around the outer periphery of said retaining member and around said permanent magnet when said key device is inoperative.

Claim 12

A key device according to claim 6 wherein a recess is formed in said retaining member for receiving therein said permanent magnet.