Patent ID: 7656072

Claim:
An actuator comprising: a driving shaft that is vibratable in the shaft direction by a piezoelectric device disposed at one end; and a moving member that is friction-engaged with the driving shaft and moves on the driving shaft by the vibration of the driving shaft, wherein the driving shaft has two flat shaft sliding faces, each being parallel to each other, and the moving member has two flat moving member sliding faces, each being in slide-contact with each of the flat shaft sliding faces, wherein the moving member is friction-engaged with the driving shaft such that the flat shaft sliding faces are clamped by the moving member sliding faces, wherein the moving member includes: a moving member main body having one of the flat moving member sliding faces; a cap member having the other of the flat moving member sliding faces; and a spring that presses the moving member main body and the cap member toward the driving shaft, said spring having at least two points of application for clamping the driving shaft by applying a force on a top surface of the moving member main body and an opposing force on a bottom surface of the cap member so as to press the moving body towards one of said flat shaft sliding faces and the cap member towards the other of said flat shaft sliding faces.