Concept of Displacement Sensor Using Resonant Inductive Coupling

This paper presents the concept of a novel displacement sensor based on resonant inductive coupling. Resonant inductive coupling uses two coils or LC circuits similarly to an electromagnetic induction. The electromagnetic induction, that is the principle of transformer, is also an interaction of magnetic fields in usually akilohertz-range. It is used for power transfer and operated with a small gap. A power transmissionwith rather larger gap is possible by using a megahertz-range resonance. Resonant inductive coupling is actively studied in the field of wireless power transfer recently. Meanwhile, some AMB systems need a displacement sensor operating with a large air gap. Thus, the resonant inductive coupling is applied to a displacement sensor. It can achieve high resolution (sub-mm) over a very large distance (10cm). In this paper, the principle of resonant inductive coupling is explained. Several basic results are shown, and these results are evaluated as a displacement sensor.