Method of driving vibration actuator, drive device, and image pickup apparatus

A method of controlling a drive device for driving a vibration actuator that includes a vibrating body and a driven body in contact with each other, the method comprising:

• applying a first drive signal and a second drive signal to an electromechanical energy conversion element of the vibrating body;
• acquiring information on a relative position between the vibrating body and the driven body;
• and
• switching the first drive signal and the second drive signal to a third drive signal and a fourth drive signal, respectively, based on the relative position by switching a phase difference between the first drive signal and the second drive signal such that an envelope of a bundle of vibration waves generated based on the third drive signal and the fourth drive signal follows variation of the relative position between the vibrating body and the driven body.

A method of driving a vibration actuator including a vibrating body and a driven body in contact with the each other, the method comprising:

• applying a first drive signal and a second drive signal having a predetermined frequency to an electromechanical energy conversion element of the vibrating body with a fixed phase difference;
• acquiring a speed profile indicative of a relationship between a position and a speed of the driven body with respect to the vibrating body;
• detecting a lowest-speed position at which the speed of the driven body becomes lowest, from the acquired speed profile;
• and
• acquiring information on a relative position between the driven body and the vibrating body, and switching the first drive signal and the second drive signal to a third drive signal and a fourth drive signal, respectively, based on the relative position and the lowest-speed position, by switching a phase difference between the first drive signal and the second drive signal such that an envelope of a bundle of vibration waves generated based on the third drive signal and the fourth drive signal follows variation of the relative position between the vibrating body and the driven body.

A method of driving a vibration actuator including a vibrating body and a driven body in contact with each other, the method comprising:

• applying a first drive signal and a second drive signal having a predetermined frequency to an electromechanical energy conversion element of the vibrating body with a fixed phase difference;
• detecting vibration generated in the vibrating body;
• acquiring a phase difference profile indicative of a relationship between a position of the driven body with respect to the vibrating body, and a phase difference between a signal produced by detecting the vibration and the first drive signal or the second drive signal;
• detecting a lowest-phase difference position at which the phase difference becomes lowest, from the acquired phase difference profile;
• and
• acquiring information on a relative position between the driven body and the vibrating body, and switching the first drive signal and the second drive signal to a third drive signal and a fourth drive signal, respectively, based on the relative position and the lowest-phase difference position, by switching a phase difference between the first drive signal and the second drive signal such that an envelope of a bundle of vibration waves generated based on the third drive signal and the fourth drive signal follows variation of the relative position between the vibrating body and the driven body.