Apple Inc.
Double helix actuator with magnetic sections having alternating polarities

Abstract:

A double helix actuator is disclosed that includes a double helix coil wound around a movable proof mass that is enclosed within a magnetic structure. The double helix coil and the magnetic structure are arranged relative to each other so that the magnetic field generated by the entirety of the double helix coil contributes to a linear force direction of the actuator. The double helix actuator produces a greater linear force density compared to traditional racetrack coil actuators, where only a portion of the coil contributes to the linear force. The double helix actuator also produces torque in addition to linear force which allows the double helix to provide unique haptic sensations in a variety of applications.