DISPLACEMENT MONITORING ELECTRODE STRUCTURE

According to a displacement amount monitoring electrode arrangement of the present invention, in order to keep a constant target amplitude even if a relative relationship between a fixed electrode and a movable electrode changes, there are at least one linear change region in which the change amount of capacitance changes linearly with the displacement of the movable electrode in the predetermined axis direction, and at least one nonlinear change region in which the change amount of the capacitance changes nonlinearly with the displacement of the movable electrode in the predetermined axis direction. The nonlinear change region includes a characteristic in which a change sensitivity of the change amount of the capacitance with respect to the displacement amount of the movable electrode in the predetermined axis direction is greater than that in the linear change region, and a target capacitance change amount of the capacitance when the displacement of the movable electrode in the predetermined axis direction reaches a target displacement amount corresponding to the target amplitude is set in the nonlinear change region.