Two-phase direct-drive motor built into a camcorders zoom lens barrel

In the majority of camcorders zoom lenses are adjusted by drive motors which are outside of lens barrels and reduction gear trains. A built-in direct drive motor housed inside the lens barrels with no protrusions would enable more compact, lighter and cheaper camcorders than conventional ones to be developed. A new motor satisfying such tough requirements is proposed in this paper. The stator (lens barrel shell) and the rotor (variator lens) function as female and male screws, respectively. By sequentially switching the currents in the armature windings buried in the lens barrel shell, the rotor rotates and the lens is moved in the direction of the optical axis