Patent ID: 7902724

Claim:
An inertial driving actuator comprising: a fixing member; a moving element that is fixed to the fixing member and generates a small displacement by extension and contraction; an oscillation substrate that is fixed to the moving element and is moved linearly and reciprocally by the small displacement; a moving body that is arranged on the oscillation substrate and is moved by inertia with respect to the oscillation substrate upon reciprocal movement of the oscillation substrate; a first electrode formed on a surface of the moving body that faces the oscillation substrate; a second electrode formed on a surface of the oscillation substrate that faces the first electrode, an area of a facing portion of the second electrode and the first electrode changing continuously as the moving body moves; an insulating film present between the first electrode and the second electrode; a frictional force controller that applies a voltage between the first electrode and the second electrode to exert an electrostatic force between them to control a frictional force generated between the oscillation substrate and the moving body, the frictional force controller changing the voltage in response to directions of the reciprocal movement of the oscillation substrate to control a relative movement of the moving body with respect to the oscillation substrate; and a position detector that detects a position of the moving body with respect to the oscillation substrate on the basis of an electrostatic capacitance of the facing portion of the first electrode and the second electrode; wherein a width of the second electrode along a straight line perpendicular to the moving direction of the moving body is substantially equal to that of the first electrode.