Actuator with position sensor and camera module using same

A camera module comprising:

• a base comprising a step and a positioning rod extending from the step;
• a stationary frame fixed on the base;
• a movable frame received in the stationary frame, the movable frame comprising a resisting surface adjacent to the base, the movable frame defining a through hole;
• a shape memory alloy (SMA) line, the SMA line resisting on the resisting surface, two ends of the SMA line fixed on the stationary frame;
• a guide pole, one end of the guide pole fixed on the base, and the other end of the guide pole extending through the through hole;
• an elastic element being ring shaped and comprising two opposite lugs, each lug defining a positioning hole, the positioning rod extending through the positioning hole of one of the lugs, the guide pole passing through the positioning hole of the other lug;
• a position sensor configured for detecting the position of the movable frame;
• and
• a controller in communication with the position sensor, wherein the controller is configured for supplying current to heat the SMA line to change a length of the SMA line, the SMA line drives the movable frame to move along the guide pole accordingly, the controller is further configured for adjusting the current according to the position of the movable frame detected by the position sensor;
• and
• a lens unit received in the movable frame.