OPTICAL IMAGE STABILISATION

摘要

A camera apparatus capable of providing optical image stabilisation comprises: a support structure; a camera unit comprising an image sensor and a lens system; a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt; and a plurality of SMA actuators. A sensor arrangement, whose output is used as the basis for generating drive signals, is mounted on the camera unit. A control circuit generates drive signals for the SMA actuators, by deriving closed-loop control signals representative of a desired degree of variation in the power of the drive signals from the output signals of the sensor arrangement without dependence on any measurement of the resistance of the SMA actuators, and generating the drive signals with powers that varies from a set-point power in correspondence with the closed-loop control signal.