A vibration actuator difficult to be affected by an external force. A vibration element is held by a shaft. A driven element is held in pressure contact with an elastic body, and a bearing member is joined to the driven element in a manner rotatable about the shaft as a rotational axis. Vibrations excited in the vibration element cause the vibration element and the driven element to rotate relative to each other about the shaft. In the driven element, a connecting portion connects between a main body and a gear provided outside the main body. The degree of freedom of the main body with respect to the bearing member is restricted in other directions than a direction of rotation thereof and a thrust direction of the shaft. The connecting portion has a lower flexural rigidity in a direction parallel to the rotational axis than the main body and the gear.

A piezoelectric driving device includes: a substrate including a fixed portion, and a vibrating body portion which is provided with a piezoelectric element and is supported by the fixed portion; and a contact portion which comes into contact with a driven body, and transmits movement of the vibrating body portion to the driven body, the contact portion is provided at an end portion in the longitudinal direction of the vibrating body portion, and a difference between a distance between the end portion when the contact portion is not pressed against the driven body and a tip end of the contact portion, and a distance between the end portion when the contact portion is pressed against the driven body and the tip end, is smaller than a total amplitude in the longitudinal direction in a case where the vibrating body portion is driven.

An ultrasonic motor includes a vibration section having a piezoelectric element configured to generate vibration by receiving a drive voltage, a driven section, a convex section connected to the vibration section and configured to transmit vibration of the vibration section to the driven section, a drive circuit configured to generate the drive voltage, an encoder configured to detect a movement amount of the driven section, a storage section configured to store a specified voltage value, and a determination section configured to receive position information from the encoder when the driven section starts to move and a voltage value at the time of start up from the drive circuit and to determine that least one of the convex section or the driven section is worn out when the voltage value at the time of start up is larger than the specified voltage value.

A vibration actuator reduced in the manufacturing cost and size thereof without using a magnet. An elastic body of a vibration element includes a base portion joined to an electromechanical energy conversion element, and a pair of contact portions extending from said base portion. The contact portions are brought into pressure contact with a driven element, by elastic deformation, in a third direction orthogonal to both of a first direction of relative motion of the vibration element and the driven element and a second direction as a thickness direction of the conversion element. When driving vibration is excited in the vibration element by applying a predetermined AC voltage to said conversion element, the contact portions apply frictional driving forces to the driven element, for moving the vibration element and the driven element relative to each other in the first direction.

A vibration-type driving apparatus includes a vibrator unit including a vibrator in which vibration is excited by an electro-mechanical energy convertor and a holder configured to hold the vibrator, and a contact body in contact with the vibrator. The vibrator and the contact body move relative to each other when vibration at a frequency higher than an audible range is excited in the vibrator. A predetermined condition is satisfied.

Provided is a vibration actuator including: an electromechanical transduction member that transduces electric power to a mechanical vibration; a transmission member that transmits the vibration from the electromechanical transduction member as a driving force; and an abutting portion that abuts on the transmission member and moves relative to the transmission member in response to the driving force. One of the transmission member and the abutting portion includes pores in its surface contacting the abutting portion or the transmission member at an area occupancy of 2% or higher. In this vibration actuator, the average area of the pores may be 3 m.sup.2 or larger. The other of the transmission member and the abutting portion may include iron in its surface contacting the one.

A vibrator including an electro-mechanical transducer and an elastic body that is fixed to the electro-mechanical transducer and that is provided with a projection, the projection having a hollow structure. The projection includes a contact portion having a first surface at a tip, the first surface being parallel to a first plane, a wall portion projecting towards an opposite side with respect to the electro-mechanical transducer, and a connection portion connecting the wall portion and the contact portion to each other. The connection portion having a spring property, and the contact portion includes a portion of which a cross-sectional area in a second plane that is parallel to the first plane increases as an increase of a distance between the portion and the first surface.

A piezoelectric drive device includes a vibrating body, a support portion formed integrally with the vibrating body, and a piezoelectric element formed of a first electrode film, a piezoelectric body film, and a second electrode film on at least one surface of the vibrating body.

A lens barrel includes an element displaced by application of voltage; an elastic body having a contact surface coming into contact with the element, a drive surface to produce a vibration wave by displacement of the element, and a plurality of grooves; a moving element come into contact with the drive surface and rotated by the vibration wave; an annular ring rotated by rotating of the moving element; and a lens moved in an optical axis direction by rotating of the annular ring; wherein the element mainly contains a material having potassium sodium niobate, potassium niobate, sodium niobate, or barium titanate, wherein a value of [(T/B)W] is in a range of 0.84 to 1.94, where T represents a depth of the groove, B represents a distance from a bottom part of the groove to the contact surface, and W represents a radial width of the elastic body.

An apparatus includes a hollow piezoelectric stator of symmetrical cross-section about two orthogonal axes. The stator includes first outer and inner faces, wherein the first outer face includes a first contact tip; second outer and inner faces; third outer and inner faces; fourth outer and inner faces; and eight electrode portions, wherein one of the eight electrode portions is positioned on each of said faces. A method of moving a rotor along a y-axis relative to an object is disclosed, wherein an orthogonal x-axis direction is normal to an engagement surface of the rotor at a first contact tip of a piezoelectric stator. The method includes positioning a first portion of a preload mechanism in a hollow space of the piezoelectric stator, attaching a second portion to the object, and moving the first contact tip along an elliptical path in an x-y plane to frictionally couple the engagement surface.