POSITION DETECTING DEVICE AND LENS DEVICE USING THE SAME

摘要

Specifically provided are a position detecting device, which can accurately detect an absolute rotation angle of a movable section, and a lens device using such position detecting device. The position detecting device is provided with a magnet (11), and a non-contact magnetic sensor (12) provided with a magnetoresistance effect element wherein an electrical resistance value changes with respect to an external magnetic field.  Of the magnet (11) and the magnetic sensor (12), one is a movable section and the other is a fixed section.  The movable section is rotatably supported.  The magnetoresistance effect element is composed of a laminated structure of a fixed magnetic layer wherein a magnetization direction is fixed, and a free magnetic layer which is formed on the fixed magnetic layer with a nonmagnetic layer therebetween and has a magnetization direction variable with respect to the external magnetic field.  When the movable section rotates, the absolute rotation angle of the movable section can be detected by an output obtained based on an electric resistance change of the magnetoresistance effect element due to an angle change of a horizontal magnetic field which flows into the magnetic sensor (12).