Patent ID: 7090636

Claim:
A keeper-shield assembly for housing a magnet, said keeper-shield assembly comprising: a keeper-shield having a central axis and comprising a material substantially permeable to a magnet flux; a first cavity in said keeper-shield, said cavity comprising an inner side wail and a base, and said cavity being adapted to accept a core; a core located within said cavity and lining at least part of said inner side wall of said cavity, said core having a second cavity adapted to retractably receive a magnet; a magnet comprising a front and a rear face, said magnet slidably mounted in said second cavity; a lip at an open end of said keeper-shield, said lip extending from an inner side wall of said keeper-shield toward said central axis of said keeper-shield; one or more resilient members configured to contribute a force against said magnet; and a movable actuator extending through said base and configured to contribute a force against said magnet, wherein said movable actuator and said one or more resilient members cooperate to move a portion of said magnet from said retracted position to a position outside of said inner cavity; and wherein said keeper-shield is sufficiently thick so that a magnetic flux density is less than about 100 gauss at a distance of about 2 centimeters from said keeper-shield when said magnet is in a retracted position.