A lens barrel includes: an electromechanical conversion element; an elastic body having a joining surface, a drive surface, and grooves; a motion member rotating by vibration wave of the drive surface; a rotating ring having a recess part and rotating by rotation of the motion member; a moving ring engaged to the recess part and moving to an optical axis direction by rotation of the rotating ring; and a lens held in the moving ring; wherein the element is made of a material having sodium potassium niobate, potassium niobate, sodium niobate or barium titanate, wherein a value of T/(B+C) is within a range of from 1.3 to 2.8 when: length from the drive surface to a base unit of the groove is defined as T; length from the base unit of the groove to the joining surface is defined as B; and thickness of the element is defined as C.

The invention relates to a piezoelectric motor with bending travelling wave, comprising a rotary shaft (4) connected to a rotor (3), a piezoelectric element (2) attached to a vibrating stator (1), and a decoupling web (5) for attaching the vibrating stator to a mounting (7). The mounting (7) is mechanically connected to a base (9) by means of at least one deformable element (10) and at least one piezoelectric actuator (11), so that the support can be deformed angularly relative to the base in order to rotate the shaft when the vibrating stator is no longer electrically powered. The motor is particularly suitable for applications that require micrometre or nanometre accuracies, for example in positioning tools in industrial processes, precise medical robotics or optical applications.

A vibrator includes an electromechanical transducer which is a piezoelectric ceramic made of sodium-potassium niobate metal oxides and whose temperature characteristics of a relative permittivity is 500 [ppm/° C.] or less in absolute value in a temperature range from −40° C. to 170° C., wherein excitation of the electromechanical transducer produces a vibration wave. Another vibrator includes an electromechanical transducer which is a piezoelectric ceramic made of sodium-potassium niobate metal oxides and whose temperature characteristics of a relative permittivity is 390 [ppm/° C.] or less in absolute value in a temperature range from 0° C. to 60° C., wherein excitation of the electromechanical transducer produces a vibration wave.

A composite motor having high-precision positioning, comprising: a housing (1), a rough positioning assembly, a hollow output shaft (2), a fine positioning assembly, a power switching apparatus and a controller (6). A stepper motor (3) in the rough positioning assembly is responsible for rough positioning of the composite motor, an annular travelling wave ultrasonic motor in the fine positioning assembly is responsible for tail end fine positioning of the composite motor, and the controller (6) implements power output switching between the annular travelling wave ultrasonic motor and the stepper motor (3). The composite motor effectively solves the problem that annular travelling wave ultrasonic motors which operate continuously for a long time have a short service life, and ensures high-precision positioning while also extending motor service life.

A vibration wave motor includes an element configured to be displaced by application of voltage, and an annular elastic body having a bottom surface coming into contact with the element and a drive surface having a groove, configured to drive a moving element by a vibration wave produced on the drive surface by displacement of the element. The element has a density of 4.2 to 6.0×10.sup.3 kg/m.sup.3. 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 bottom surface, and W represents a radial width of the elastic body.

A vibration wave motor includes a vibrator, a contact body to be brought into contact with the vibrator, a shaft fixed to the contact body, and a fixing member configured to fix the contact body and the shaft from the shaft side.

Provided is a piezoelectric ceramics having a gradual change in piezoelectric constant depending on an ambient temperature. Specifically, provided is a single-piece piezoelectric ceramics including as a main component a perovskite-type metal oxide represented by a compositional formula of ABO.sub.3, wherein an A site element in the compositional formula contains Ba and M.sub.1, the M.sub.1 being formed of at least one kind selected from the group consisting of Ca and Bi, wherein a B site element in the compositional formula contains T1 and M.sub.2, the M.sub.2 being formed of at least one kind selected from the group consisting of Zr, Sn, and Hf, wherein concentrations of the M.sub.1 and the M.sub.2 change in at least one direction of the piezoelectric ceramics, and wherein increase and decrease directions of concentration changes of the M.sub.1 and the M.sub.2 are directions opposite to each other.

The lens apparatus includes an optical system, a voltage transformation unit, and an actuator. A first lens unit of the optical system is moved toward the object side during zooming from a wide-angle end to a telephoto end. The voltage transformation unit includes coils. The actuator is configured to be driven by a voltage output from the voltage transformation unit and to move a part of the lens units in the optical system during focusing. The coil is disposed at a position that is separated from a position of a most object-side surface of the optical system at the wide-angle end, toward the image side by a maximum or more moving amount of the first lens unit, and is closer to the object side than a most image-side surface of the optical system at the wide-angle end.

A vibration-type actuator includes a vibrating body including an annular elastic member and an electric-mechanical energy conversion element, and an annular contact body configured to move relative to the vibrating body. The contact body includes a base portion, a support portion annularly extending from the base portion in a radial direction of the contact body, and a friction member provided at the support portion, formed separately from the support portion, and being in contact with the vibrating body. The friction member includes a first part extending in a direction along a central axis of the annular contact body, and a second part extending in the radial direction, the first part and the second part being connected to the support portion. The first part includes a portion that is connected by being either internally or externally fitted to the support portion in the radial direction.

A lead-free piezoelectric material includes perovskite-type metal oxide containing Na, Nb, Ba, Ti, and Mg and indicates excellent piezoelectric properties. The piezoelectric material satisfies the following relational expression (1): 0.430≤a≤0.460, 0.433≤b≤0.479, 0.040≤c≤0.070, 0.0125≤d≤0.0650, 0.0015≤e≤0.0092, 0.9×3e≤c−d≤1.1×3e, a+b+c+d+e=1, where a, b, c, d, and e denote the relative numbers of Na, Nb, Ba, Ti, and Mg atoms, respectively.