Ultrasonic motors using shear-type piezoelectric ceramics

The shear piezoelectric constant value for d₁₅ has a higher value compared with constant d₃₁ or d₃₃. Also, the value of the shear electromechanical coupling coefficient k₁₅ is bigger than that of k₃₁ or k₃₃. A design for an ultrasonic motor based on the shear coefficients has the potential for superior performance, relative to conventional d₃₁ and d₃₃ based ones. Thus, this paper presents ring type, tube type, disk type and rod type piezoelectric ceramic elements, which use the d₁₅ shear piezoelectric constant effect. The application methods and driving mechanism of the typical ultrasonic motors which use the shear piezoelectric ceramic elements are analyzed. The applications of shear piezoelectric ceramic elements accords with the requirements of the development trends of ultrasonic motors, such as large strain and miniaturization.