Patent ID: 7665914

Claim:
An iris diaphragm actuator, comprising: a magnetic position sensing structure comprising a magnetic element and a magnetic sensor relatively disposed; a driving element coupled to the magnetic element or the magnetic sensor for changing a distance and an angle between the magnetic element and the magnetic sensor so as to obtain a substantially linear relation between a magnetic flux sensed by the magnetic sensor and a position of the magnetic element; and a light intercepting element connected to the driving element, wherein the magnetic sensor has a magnetic flux density sensing region and the magnetic flux sensed in the magnetic flux density sensing region is estimated by a following equation: φ=∫ B·dA=BA cos θ (1) wherein φ is the magnetic flux, B is a magnetic flux density vector, dA is a unit area vector of the magnetic flux density sensing region, and θ is the angle between the magnetic flux density sensing region and the magnetic flux density vector.