Patent ID: 7956513

Claim:
A driving method for a driving device comprising an electro-mechanical transducer having first and second end portions opposite to each other in an expansion/contraction direction, a stationary member coupled to the first end portion of said electro-mechanical transducer, a vibration friction portion mounted to the second end portion of said electro-mechanical transducer, and a moving portion frictionally coupled to said vibration friction portion so as to be movable in the expansion/contraction direction of said electro-mechanical transducer, said driving method driving said moving portion due to expansion/contraction of said electro-mechanical transducer, said driving method comprising: equalizing a constant expanding speed of said electro-mechanical transducer with a constant contracting speed of said electro-mechanical transducer; and setting a constant rest time interval after one of contraction of said electro-mechanical transducer and expansion of said electro-mechanical transducer, thereby moving said moving portion in one of an expansion direction and a contraction direction of said electro-mechanical transducer, wherein, when driving said moving portion in the expansion direction of said electro-mechanical transducer, said driving method comprises: a1) expanding said electro-mechanical transducer at the constant expanding speed to make said vibration friction portion displace in the expansion direction of said electro-mechanical transducer at the constant expanding speed; b1) immediately after performing the expanding, contracting said electro-mechanical transducer at the constant contracting speed to make said vibration friction portion displace in the contraction direction of said electro-mechanical transducer at the constant contracting speed; and c1) immediately after performing the contracting, making said vibration friction portion rest for the constant rest time interval without driving said electro-mechanical transducer, wherein said driving method repeats the above steps a1) through c1), thereby generating, as a drive pulse, a triangular wave pulse with a rest portion.