Abstract text

A driver, including: a piezoelectric element extending and contracting upon application of an electrical voltage; a driving member having one end secured to the piezoelectric element; a frictionally coupling member, frictionally coupling the driving member; and a drive circuit, connected with a power supply to activate the piezoelectric element at a predetermined period, including: a charge switching element for connecting an electrode of the piezoelectric element with the power supply, a discharge switching element, and a protective resistor arranged in an electric path between the power supply and the piezoelectric element or between the piezoelectric element and a ground point, wherein a resistance value of the protective resistor is set larger than an ON resistance of the switching element but smaller than a value obtained by dividing one half of the drive period of the switching element by a capacitance of the piezoelectric element, in a predetermined period.