Electrostatic actuator with interdigitated electrode structure

An electrostatic actuator with an interdigitated electrode structure, comprising:

• a substrate;
• a movable rod disposed by aligning its axis with an alignment axis line predetermined on said substrate;
• a movable interdigitated electrode fixed to a coupling point on said movable rod and having a plurality of movable electrode fingers arrayed at intervals in a direction orthogonal to a longitudinal direction of said movable rod, in parallel with the longitudinal direction of said movable rod and in parallel from each other;
• a fixed interdigitated electrode fixed on said substrate and having a plurality of fixed electrode fingers disposed alternately in parallel with said movable electrode fingers and in parallel from each other;
• and
• first and second hinges whose one ends are anchored respectively to first and second supporting points disposed apart from each other on said movable rod and whose other ends are anchored respectively to first and second anchoring points on said substrate;
• wherein
• said movable rod is supported so as to be movable along said alignment axis line;
• said coupling point exists on the same side as said second supporting point as viewed from said first supporting point;
• lengths of said first and second hinges are longer than distances from said first and second anchoring points to which those hinges are anchored to said alignment axis line respectively by |L1| and |L2|;
• positional coordinates of said first and second supporting points in the direction perpendicular to said alignment axis line as coordinate origin reach respectively to L1 and L2 when said hinges are entirely extended respectively in the direction perpendicular to said alignment axis line;
• and an absolute value |Lc| of Lc=L1+(L2−L1)d1/Ls is reduced to be smaller than any distance between the respective movable electrode fingers and the closest fixed electrode finger on the side in the direction represented by a sign of the Lc in the state when said movable rod is aligned with said alignment axis line, where d1 and Ls are the distances respectively from said first supporting point to said coupling point and to said second supporting point.