Ultrasonic piezomotor equipped with a piezoelectric rotary encoder

An ultrasonic piezomotor with a piezoelectric rotary encoder for rotation angle detection was developed. To control a piezomotor, a simple detector is required, as well as increasing reliability. To satisfy this requirement, a piezomotor with a piezoelectric rotary encoder, using a single piezoelectric ceramic ring plate, was built. This piezomotor rotor is composed of a lining, a spring, and a piezoelectric rotary encoder. The phase difference between waves in the stator and waves detected by the piezoelectric rotary encoder is in proportion to a rotation angle. This proportional relation enables the piezomotor to detect a rotation angle. Interpolating the phase difference, incremental pulses are generated. As a result of applying this piezomotor to printer-scanner systems, great reductions in thickness were achieved without affecting reliability