Actuator

An actuator having a rotation central axis, the actuator comprising:

• a frame having an insulative property;
• a pair of movable comb electrodes spaced apart from each other, each of the pair of movable comb electrodes having a side surface and being provided with at least one set of first electrode teeth which are arranged side by side with a predetermined interval on the side surface thereof;
• a movable portion provided between the pair of movable comb electrodes;
• a pair of supporting portions provided on the frame for supporting the pair of movable comb electrodes and the movable portion;
• at least one pair of fixed comb electrodes provided on the frame at the positions which respectively correspond to the pair of movable comb electrodes, each of the at least one pair of fixed comb electrodes being provided with one set of second electrode teeth which are arranged side by side with a predetermined interval so as to be cooperatively associated with the first electrode teeth of the corresponding movable comb electrode;
• at least one pair of first elastic connecting portions which respectively connect the pair of movable comb electrodes to the pair of supporting portions so that each of the movable comb electrodes can rotate around the rotation central axis of the actuator with respect to the corresponding supporting portion;
• and
• at least one pair of second elastic connecting portions which respectively connect the movable portion to the pair of movable comb electrodes so that the movable portion can rotate around the rotation central axis of the actuator in accordance with the rotation of the movable comb electrodes,
• wherein each of the pair of movable comb electrodes is driven by means of Coulomb force generated by applying an alternating voltage between each of the fixed comb electrodes and the corresponding movable comb electrode, whereby the movable portion rotate, and
• wherein the first electrode teeth of each of the pair of movable comb electrodes and the second electrode teeth of each of the corresponding at least one pair of fixed comb electrodes are configured so that at least a part of the first electrode teeth of each of the movable comb electrodes overlaps with a part of the second electrode teeth of the corresponding fixed comb electrode in a state where no alternating voltage is applied therebetween.