NECS
TECHNOLOGY
Repulsive Magnetic Actuator (RMA)
between two like-poled magnets facing each other, along with the
Lorentz force generated when current flows through a coil.
RMA Installation Structure and Vibration
The lower magnet–coil assembly is mounted to the device’s bottom frame or directly to the PCB, while the upper magnet is mounted to the top frame or a vibration plate, maintaining a constant air gap. With like poles facing each other, a repulsive force acts between the two magnets, helping maintain the designed gap and providing a consistent preload. The upper and lower structures are connected via a suspension system. When voltage is applied to the coil, the resulting electromagnetic (Lorentz) force drives vibration by pushing or pulling the upper structure.
Input Sensing
A magnetic field exists between the two magnets in the RMA. When external interaction changes the gap between them, the magnetic flux through the coil changes and generates an induced electromotive force. Any change in the magnet-to-magnet distance caused by a finger touch, a press through a cover lens, or interaction with nearby materials such as plastic or metal produces an induced voltage signal that can be used as sensing data.
With this built-in sensing capability, the RMA can replace separate touch or pressure sensors used as haptic triggers in a wide range of electronic devices.
Vibration for Haptics and Sound Implementation
The RMA is a repulsive magnetic actuator in which two magnets are arranged with like poles (e.g., N–N or S–S) facing each other, creating a baseline repulsive force. The lower magnet–coil assembly (input side) is rigidly fixed to the base structure, while the upper magnet (output side), without a coil, is bonded to a vibration plate/structure using a high-temperature-resistant adhesive.
During operation, applying a voltage to the coil causes current to flow, generating an electromagnetic (Lorentz) force that modulates the net magnetic force between the two magnets. This enables precise control of the actuator’s push–pull force and vibration amplitude.
By tailoring the amplitude, waveform, and duration of the input voltage, the actuator can deliver both sophisticated haptic feedback and audio output as intended by the developer.