Patent ID: 7969063

Claim:
A driver, comprising: a piezoelectric element extending and contracting upon application of an electrical voltage; a driving member having one end secured to the piezoelectric element, and being able to reciprocate in an axial direction by a extending and contracting movement of the piezoelectric element; a frictionally coupling member, frictionally coupling the driving member and being caused to slide against the driving member by reciprocating movement of the driving member; and a drive circuit connected with a power supply and applying a voltage generated by the power supply to the piezoelectric element at a predetermined drive period, wherein the drive circuit includes: a charge switching element for connecting an electrode of the piezoelectric element with the power supply, a discharge switching element for grounding the electrode of the piezoelectric element, and a protective resistor arranged in at least either an electric path between the power supply and the piezoelectric element or an electric path 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.