US Patent 7396167 Lens retracting structure

A lens retracting structure includes a housing, an image-forming lens set moveably supported on two parallel guide rods inside the housing, and a driving mechanism for moving the image-forming lens set along the parallel guide rods between a first position and a second position by means of the engagement of a threaded coupling member of the image-forming lens set with a threaded shaft which is rotatably driven by a motor of the driving mechanism.