ULTRASONIC MOTOR PROVIDED WITH MAGNETIC ENCODER

摘要

PURPOSE:To improve accuracy of position and speed control, by arranging first and second tracks magnetized continuously with alternating polarity on the outer circumference of a rotary body and arranging a magnetic encoder while facing with the tracks. CONSTITUTION:A ultrasonic motor comprises a stator 7 and a rotor 3, where the rotor 3 comprises a rotary body 1 arranged on the outer circumferential section of the central shaft 1a and a ring type running member 2 for converting the vibration of the stator 7 into rotary force. A magnetism sensitive element 14 is arranged on a fixing table 9 through a proper gap with respect to the outer circumferential section of the rotor 3. A resin mold magnet 13 arranged on the outer circumferential section of the wall face of the rotor 3 comprises first and second tracks 13b, 13c magnetized continuously with alternating polarity and a non-magnetized groove section 13 between the tracks. The magnetism sensitive element 14 detects variation of flux of the first and second tracks 13b, 13c caused through rotation of the rotor 3 and provides signals to a position control circuit section and a speed control circuit section.