Apple Inc.
Scanning motor with built-in magnetic stiffness

Abstract:

Scanning apparatus includes a rotor, including a permanent magnet, which is configured to rotate about an axis. A stator includes a magnetic core, which is configured to generate a static magnetic field in a vicinity of the rotor and defines an equilibrium angle of rotation of the rotor, at which the permanent magnet is aligned with the static component of the magnetic field. At least one coil is wound on the magnetic core so that when the coil driven with an AC electrical current at a selected frequency, the stator generate a time-alternating magnetic field, which causes the rotor to oscillate on the axis at the selected frequency about the equilibrium angle.