Lens autofocus actuating device

A lens autofocus actuating device, comprising:

• a base comprising an upper surface;
• a guide rail unit disposed on the upper surface of the base;
• a lens carrier, disposed above the base, the lens carrier comprises a protrusion;
• an actuating member, disposed on the upper surface of the base, comprising two electrode terminal pairs and two shape-memory alloy wires, wherein the two electrode terminal pairs each has two electrodes, one of the electrodes in each of the two electrode terminal pairs is electrically connected to each other, the two shape-memory alloy wires are disposed opposite each other, wherein each shape-memory alloy wire is in contact with the protrusion of the lens carrier, and two ends of each shape-memory alloy wire are connected to the electrodes of each group of the electrode terminal pairs, wherein the shape-memory alloy wires are driven by an electric current to produce thermal deformation and then actuate the lens carrier to move relative to the base;
• a plurality of balls divided into groups;
• and
• a shell connected to the base to cover at least the guide rail unit, the lens carrier, and the actuating member;
• wherein the guide rail unit comprises:
• a fixing ring;
• and
• a plurality of position-limiting members disposed vertically on the fixing ring.