| 摘要 |
PURPOSE:To drive a driven member at high speed by causing a current larger than a specified constant current to flow through an electromechanical transducer when the specified constant current is made to flow through the electromechanical transducer and the driven member is not moved while surpassing the frictional coupling with a driving member when the driven member is shifted together with the driving member. CONSTITUTION:When a zoom lens-barrel 11 is moved together with a driving shaft 13, a constant current is made to flow as a driving signal transmitted over a piezoelectric element 18 as an electromechanical transducer. When the zoom lens-barrel 11 is not shifted while surpassing the frictional coupling with the driving shaft 13, on the other hand, a large current is made to flow through the piezoelectric element 18, and the piezoelectric element 18 quickly generates expansion displacement in the thickness direction. Accordingly, since the driving signal current can be controlled, ringing vibrations can be inhibited, thus driving the zoom lens-barrel 11 at high speed. |
