Camera lens actuation apparatus

摘要

A camera lens actuation apparatus for driving motion of a camera lens 6 supported on a support structure 2 by a suspension system 10. The apparatus incorporates a subassembly comprising SMA wire 42 connected to at least one mounting member 32,33 which is mounted to the support structure. At least one pair of lengths of SMA wire are held in tension between the camera lens element and the support structure at respective acute angles to the optical axis applying a tensional force having a component along the optical axis. The lengths of SMA wire in the pair are held at angle as viewed along the optical axis. There may be plural pairs with a balanced arrangement in which the forces generated have no net component perpendicular to the optical axis and generate no net torque around any axis perpendicular to the optical axis. The SMA wire has a diameter of no more than 35 microns A control circuit controls heating of the SMA wire in response to a measure of its resistance.