Back to results
US 12,712,104 B2Granted
Magnetic systems incorporating electropermanent magnet arrays
AssigneeApple Inc.
InventorsJohn C. DiFonzo, Mitsutoshi Makihata, Jean-Marc Gery
Life of this patent
Estimating the term…
Abstract
Magnetic systems can include a controllable magnet array and a fixed magnetic array. The fixed magnetic array can include an array of permanent magnets having alternating polarization direction transverse to the array. Some controllable magnet arrays can include electropermanent magnets (EPMs) arranged end-to-end, with pole pieces between them aligned to the permanent magnets of the fixed magnet array. Each EPM can include a permanent magnet having a fixed magnetic orientation lateral to the array and antiparallel to the permanent magnet in an adjacent EPM and a switchable magnet whose magnetic orientation can be switched between parallel and antiparallel to the permanent magnet in the EPM.
Claims20
A magnetic system comprising:
- a controllable magnet array comprising a plurality of electropermanent magnets arranged end-to-end, wherein each electropermanent magnet comprises:
- a first permanent magnet disposed proximate to an interface surface and having a fixed magnetic orientation along a longitudinal axis, wherein the fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets are opposite to each other;
- a switchable magnet comprising a core made of a magnetic material and a coil of wire wound around the core along a longitudinal axis of the core, wherein the switchable magnet is positioned on a distal side of the first permanent magnet and spaced apart from the first permanent magnet;
- and
- pole pieces disposed at each longitudinal end of the first permanent magnet and the switchable magnet, the pole pieces being made of a soft magnetic material and extending across end surfaces of the first permanent magnet and the electropermanent magnet, wherein pole pieces are shared between adjacent electropermanent magnets in the controllable magnet array;
- a fixed magnet array comprising an array of second permanent magnets arranged parallel to the interface surface such that each second permanent magnet aligns with one of the pole pieces of the controllable magnet array, wherein adjacent second permanent magnets have fixed magnetic polarizations in opposite directions toward or away from the interface surface;
- and
- a control and driver circuit coupled to each of the coils and configured to supply current pulses to the coils to switch a direction of magnetic polarization of the cores of the electropermanent magnets, thereby switching the electropermanent magnets between an ON state in which a direction of magnetic polarization of the core is parallel to the magnetic polarization of the first permanent magnet and an OFF state in which the direction of magnetic polarization of the core is antiparallel to the magnetic polarization of the first permanent magnet, wherein the control and driver circuit is configured to supply current pulses to different coils independently of each other.
5 more elements
A device comprising:
- a first object having a first interface surface, the first object including an controllable magnet array comprising a plurality of electropermanent magnets arranged end-to-end proximate to the first interface surface, wherein each electropermanent magnet comprises:
- a first permanent magnet disposed proximate to the first interface surface and having a fixed magnetic orientation along a longitudinal axis, wherein the fixed magnetic orientations of the first permanent magnets in adjacent electropermanent magnets are opposite to each other;
- a switchable magnet comprising a core made of a magnetic material and a coil of wire wound around the core along a longitudinal axis of the core, wherein the switchable magnet is positioned on a distal side of the first permanent magnet and spaced apart from the first permanent magnet;
- and
- pole pieces disposed at each longitudinal end of the first permanent magnet and the switchable magnet, the pole pieces being made of a soft magnetic material and extending across end surfaces of the first permanent magnet and the electropermanent magnet, wherein pole pieces are shared between adjacent electropermanent magnets in the controllable magnet array;
- a second object having a second interface surface, the second object being positionable relative to the first object such that the second interface surface abuts the first interface surface,
- the second object including a fixed magnet array comprising an array of second permanent magnets arranged proximate to the second interface surface such that each second permanent magnet aligns with one of the pole pieces of the controllable magnet array, wherein adjacent second permanent magnets have fixed magnetic polarizations in opposite directions toward or away from the interface surface;
- and
- a control and driver circuit coupled to each of the coils and configured to supply current pulses to the coils to switch a direction of magnetic polarization of the cores of the electropermanent magnets, thereby switching the electropermanent magnets between an ON state in which a direction of magnetic polarization of the core is parallel to the magnetic polarization of the first permanent magnet and an OFF state in which the direction of magnetic polarization of the core is antiparallel to the magnetic polarization of the first permanent magnet, wherein the control and driver circuit is configured to supply current pulses to different coils at different times.
6 more elements
A magnetic system comprising:
- a controllable magnet array comprising a plurality of electropermanent magnets placed end-to-end, wherein each electropermanent magnet comprises:
- a first switchable magnet comprising a first core made of a magnetic material and a first coil of wire wound around the first core along a longitudinal axis of the first core, wherein the first switchable magnet is disposed proximate to an interface surface;
- a second switchable magnet comprising a second core made of a magnetic material and a second coil of wire wound around the second core along a longitudinal axis of the second core, wherein the second switchable magnet is positioned on a distal side of the first switchable magnet and spaced apart from the first switchable magnet;
- and
- pole pieces disposed at each longitudinal end of the first switchable magnet and the second switchable magnet, the pole pieces being made of a soft magnetic material and extending across end surfaces of the first switchable magnet and the second switchable magnet, wherein pole pieces are shared between adjacent electropermanent magnets in the controllable magnet array;
- a fixed magnet array comprising an array of permanent magnets arranged parallel to the interface surface such that each permanent magnet aligns with one of the pole pieces of the controllable magnet array, wherein adjacent permanent magnets have magnetic polarizations in opposite directions toward or away from the interface surface;
- and
- a control and driver circuit coupled to each of the first coils and each of the second coils and configured to supply current pulses to the first coils and the second coils, thereby switching the electropermanent magnets among a first ON state in which the magnetic polarizations of the first and second switchable magnets are parallel and in a first longitudinal direction, a second ON state in which the magnetic polarizations of the first and second switchable magnets are parallel and in a second longitudinal direction opposite the first longitudinal direction, and an OFF state in which the magnetic polarizations of the first and second switchable magnets are in antiparallel longitudinal directions.
5 more elements
Dependencies are inferred from the claim text.