Patent ID: 8841981

Claim:
A detachable cover system, comprising: an enclosure having an opening; a cover for covering said opening; a first magnetic structure attached to said enclosure; a second magnetic structure attached to said cover, one of said first magnetic structure or said second magnetic structure comprising a plurality of magnetic sources comprising a first magnetic source having a first polarity and a second magnetic source having a second polarity opposite said first polarity, said first magnetic structure and said second magnetic structure being configured in a first relative alignment position and having a composite magnetic field that produces a composite attract force that causes said first magnetic structure and said second magnetic structure to magnetically attach such that said cover covers said opening; a coil located in proximity to one of said first magnetic structure or said second magnetic structure, said coil being controllable to produce a bias magnetic field that is added to the composite magnetic field while said first magnetic structure and said second magnetic structure are in said first relative alignment position, said adding of the bias magnetic field to the composite magnetic field causing said first magnetic structure and said magnetic structure to produce a repel force that causes magnetic detachment of said first magnetic structure from said second magnetic structure such that said cover no longer covers said opening; and said first magnetic structure and said second magnetic structure are a multi-level magnetic system that produces forces that transition from a net attract force to a net repel force at a transition distance.