Patent ID: 7274120
Filing Date: 2007-09-25
Classification: H02K

Abstract:
1. A lens drive unit for performing linear movement of at least one lens element of an optical lens system comprising: an electric motor comprising a hollow cylindrical stator for generating a magnetic field in a cylindrical space and a hollow cylindrical rotor coaxially disposed within said hollow cylindrical stator and capable of rotating relative to said hollow cylindrical stator within said magnetic field; a hollow movable cylindrical member for holding said at least one lens element therein which is mounted for relative rotation in said hollow cylindrical rotor; and a motion transformation mechanism for transforming rotational movement of said hollow cylindrical rotor into a linear movement of said hollow movable cylindrical member, said motion transformation mechanism comprising a helical groove formed on an inner wall surface of said hollow cylindrical rotor and a helical thread formed on an outer surface of said movable cylindrical member which engage with each other so that said hollow movable cylindrical member is forced to undergo a linear movement along an optical axis of said optical system when said hollow cylindrical rotor rotates relative to said hollow movable cylindrical member, and a head-on striking structure provided between one end of said helical groove and said helical thread to restrict said relative rotation of said movable cylindrical member.