US Patent 9310584 Lens driving apparatus

A lens driving apparatus includes a housing, a lens holder mounted on a base of the housing and moveable along an optical axis, a stationary guide member provided on the base, and a moveable guide member provided on and moveable with the lens holder, wherein the moveable guide member is frictionally engaged with the stationary guide member and slidable therealong when the lens holder is activated. The apparatus further include a plurality of magnets with magnetization direction lying on a plane perpendicular to the optical axis, a coil disposed adjacent and parallel to the magnets, and a position encoder provided on the lens holder or the support for close loop control of the movement of the lens holder.