Highly accurate rotation-angle sensors using amorphous star-shaped cores

A new highly accurate rotation-angle sensor is presented using an amorphous star-shaped-core multivibrator bridge combined with a multi-pole ring magnet. A zero-drift angle was 0.0013° for a rotation-angle sensor with 40-pair zero-magnetostrictive amorphous-wire cores assembled around a 40-pole magnetized ferrite ring magnet into a star shape, which compensates irregular distributions of the field strength generated from each pole and cancells almost all external disturbance fields. Therefore, it is possible to construct a rotary encoder using the 40-pair star-shaped core which generates more than 10⁵pulses utilizing the clock pulse of a micro-computer, A new accurate torque sensor is constituted using a pair of the rotation-angle sensors.