Patent ID: 7576456

Claim:
A linear actuator having: a rectangular tubular-shaped movable element in which a driving coil is wound around an outer peripheral surface of a rectangular tubular-shaped coil frame in a peripheral direction thereof; and an anchoring element in which left and right outer yokes are disposed perpendicularly, left and right magnets are attached to inner sides of the left and right outer yokes so as to face left and right perpendicular edges of the driving coil with a fixed gap, and left and right inner yokes are disposed inside the movable element so that they are disposed opposite the left and right magnets between which left and right perpendicular edges of the movable element are disposed; wherein an excitation current of the driving coil is controlled, whereby the movable element is moved in linear fashion in a direction of a central axial line of the movable element, the linear actuator comprising: a support plate that extends along the central axial line between the left and right inner yokes inside the coil frame and that is attached to the inner yokes so that they form an H-shaped structure; a linear guide that is disposed inside the coil frame, and that supports the movable element so as to allow movement along the central axial line thereof; a load attaching member attached to an inner peripheral surface of the coil frame; and a position detecting mechanism disposed inside the coil frame in order to detect a movement position of the movable element; wherein the linear guide has a linear guide rail anchored to a surface of the support plate, and a linear guide block that can be moved linearly along the linear guide rail and is anchored to an upper surface formed on the load attaching member; the position detecting mechanism has a light-emitting part attached to an inner peripheral surface of an upper edge of the coil frame, and a light-receiving part mounted on a circuit substrate attached to an upper surface of the horizontal support plate; when the linear actuator is cut in a plane perpendicular to the central axial line of the movable element, the linear guide rail is positioned on the central axial line; and the load attaching member, linear guide, support plate, and position detecting mechanism are linearly arranged; and a center of gravity of the movable element and a center of the linear guide are matched with one another.