Zoom driving actuator and position control method for zoom driving

A zoom actuator, said zoom actuator comprising:

• a first carrier having a first lens attached thereto and movable along an optical axis;
• a second carrier having a second lens attached thereto, said second carrier being capable of moving anterior or posterior to the first carrier along the optical axis;
• a housing enclosing the first and second carriers;
• a first magnet attached to the first carrier;
• a second magnet attached to the second carrier;
• a first coil unit mounted to the housing and facing the first magnet;
• a second coil unit mounted to the housing and facing the second magnet;
• and
• a plurality of balls;
• with at least one of said plurality of balls positioned between the housing and the first carrier;
• and at least one of said plurality of balls positioned between the housing and the second carrier, and
• wherein the first carrier comprises:
• a first mount equipped with the first lens;
• a first support fitted on the first mount, either left or right thereto;
• said first support extending longer along the optical axis than the first mount;
• a first rail formed on the first support;
• and
• a second rail formed on a region of the first mount unfitted with the first support, and
• wherein the second carrier comprises:
• a second mount equipped with the second lens;
• a second support fitted on a side of the second mount, either to the left or right thereof, but opposite the side the first support is fitted thereon, said second support extending longer than the second mount in a direction opposite to the first carrier along the optical axis;
• a third rail formed on the second support;
• and
• a fourth rail formed on a region of the second mount unfitted with the second support, and
• wherein said plurality of balls are arranged so that a physical support of the first carrier or the second carrier is in a trapezoidal shape.