Abstract: An embodiment of the invention is a particular arrangement of permanent magnets that generates a higher strength and more uniform magnetic field than existing permanent magnet arrangements for a voice coil motor. The permanent magnet arrangement of an embodiment is based on the Halbach arrangement of permanent magnets. The increased magnetic field strength and uniformity allows for a voice coil motor that is both capable of higher frequency actuations as well as more uniform force over the full stroke of the actuation.

Abstract: An improved magnetic decoupler with a magnetic field shape, strength and gradient optimized for releasing security tags, such as an antitheft device of the type described above. Due to the structure of the magnetic decoupler, it contains less ferrous material than prior art decouplers heretofore employed. Reduction in size of the magnetic decoupler, along with improved magnetic strength, derive from the magnet assembly including magnets arranged with orientations that increase axial magnetic field gradient by superposition of the magnetic fields of each magnet.

Abstract: An improved magnetic decoupler with a magnetic field shape, strength and gradient optimized for releasing security tags, such as an antitheft device of the type described above. Due to the structure of the magnetic decoupler, it contains less ferrous material than prior art decouplers heretofore employed. Reduction in size of the magnetic decoupler, along with improved magnetic strength, derive from the magnet assembly including magnets arranged with orientations in quadrature to increase axial magnetic field gradient within the decoupler cavity by superposition of the magnetic fields of each magnet.