Miniaturized Electromagnetic Actuator For Tactile Display Devices With High Spatial Resolution

A recently presented selective electromagnetic actuation technique offered higher spatial resolution by controlling the vibrations of multiple tactile elements using a single coil. In this technique electrical input power is supplied at the mechanical resonance frequencies of individual resonant tactile pixels (taxels). However, the different resonant frequencies designed by varying the dimensions of suspension beams for each taxel lead to different vibration amplitudes, i.e., smaller vibrations for the high-frequency resonator leading to the errors in tactile perception. We present a new structure by varying the strength of millimeter-sized embedded magnets to equalize the amplitude of vibrations. The proposed technique is validated on a 3D printed tactile faceplate with 1-2mm diameter embedded neodymium magnets. The finite element analysis (FEA) on multiphysics model developed for this actuation technique are in close agreement with the optical vibrometry measurement results, which successfully validates the proposed method for equalizing the amplitude of vibrations. The difference in vibration amplitudes with equal size have been reduced by 3 times compared with the proposed unequal magnets.