This paper reviews recent developments of ultrasonic motors using piezoelectric resonant vibrations. Following the historical background, ultrasonic motors using standing and traveling waves are introduced. Driving principles and motor characteristics are explained in comparison with conventional electromagnetic motors. After a brief discussion on speed and thrust calculation, finally, reliability issues of ultrasonic motors are described.
In office equipment such as printers and floppy disk drives, market research indicates that tiny motors smaller than 1 cm3 would be in large demand over the next ten years. However, using the conventional electromagnetic motor structure, it is rather difficult to produce a motor with sufficient energy efficiency. Piezoelectric ultrasonic motors, whose efficiency is insensitive to size, are superior in the mm-size motor area. There is today a large variety designs exploiting motion obtainable from the inverse piezoelectric effect. Ultrasonic piezoelectric motors have a very special place among such devices .These motors achieve high speed and drive forces, while still permitting the moving part to be positioned with very high accuracy. Such characteristics make these motors of great interest for many companies who make precision devices for which these drives are, in many cases, irreplaceable.
In office equipment such as printers and floppy disk drives, market research indicates that tiny motors smaller than 1 cm3 would be in large demand over the next ten years. However, using the conventional electromagnetic motor structure, it is rather difficult to produce a motor with sufficient energy efficiency. Piezoelectric ultrasonic motors, whose efficiency is insensitive to size, are superior in the mm-size motor area. There is today a large variety designs exploiting motion obtainable from the inverse piezoelectric effect. Ultrasonic piezoelectric motors have a very special place among such devices .These motors achieve high speed and drive forces, while still permitting the moving part to be positioned with very high accuracy. Such characteristics make these motors of great interest for many companies who make precision devices for which these drives are, in many cases, irreplaceable.
