Patent ID: 8068167

Claim:
A shape memory alloy actuator driving device for expanding and contracting a shape memory alloy member by increasing and decreasing a temperature of the shape memory alloy member through application and suspending application of a drive current from a driving circuit to the shape memory alloy member to displace a driven member linked to the shape memory alloy member to an intended position, the shape memory alloy actuator driving device comprising: a constant current source for applying a predetermined constant current to the shape memory alloy member, as a retrieval signal; a detector for detecting a voltage between terminals of the shape memory alloy member by the retrieval signal; and a controller for comparing a detection result of the detector, with a target voltage value to be calculated based on a target resistance value of the shape memory alloy member corresponding to the intended displaced position of the driven member, and a value of the constant current, and causing the driving circuit to output, to the shape memory alloy member, a drive current that makes the detection result substantially equal to the target voltage value, wherein the driving circuit includes a switching element for switching over between a current to be outputted from a variable current source in the driving circuit, and the retrieval signal to be outputted from the constant current source to apply the switched current to the shape memory alloy member, and the controller controls a value of the current to be outputted from the variable current source in such a manner that the detection result of the detector is substantially equal to the target voltage value, and causes the detector to detect the terminal voltage of the shape memory alloy member during a time when the switching element is switched to the constant current source.