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.

A reaction compensation device includes a drive mechanism driving a first movable part with respect to a base, a reaction mass drive mechanism driving a second movable part with respect to the base; and a first relative position sensor measuring a relative position between the first movable part and the base. There is also a second relative position sensor measuring a relative position between the second movable part and the base, a first control system controlling the drive mechanism by taking in a signal outputted from the first relative position sensor as a feedback signal in response to a command value, and a second control system correcting the command value using a correction parameter for adjusting a difference between mass properties of the drive mechanism and reaction mass drive mechanism and for controlling the reaction mass drive mechanism.

A vibration motor includes a first vibrating body including a first projection and a second vibrating body including a second projection, the first vibrating body and the second vibrating body receiving electric power and vibrating to generate a driving force and transmitting the driving force to a driven section, a first coil spring configured to urge the first vibrating body and the second vibrating body in a driving direction and restrict positions of the first vibrating body and the second vibrating body in the driving direction, and a case housing the first vibrating body, the second vibrating body, and the first coil spring. The first vibrating body, the second vibrating body, and the first coil spring are arranged in the driving direction. The number of first coil springs is smaller than the number of first and second vibrating bodies in the urging direction.

A vibration actuator is capable of reducing differences in vibration phase and vibration amplitude without raising a voltage of a drive circuit when driving a contact member using a plurality of vibrators connected in series. The vibration actuator includes a vibrator device and a contact member that moves relative to the vibrator device. The vibrator device includes transformers of which primary coils are connected in series, and vibrators that are respectively connected in parallel to secondary coils of the transformers.

A piezoelectric actuator includes a vibrating section including a piezoelectric element, a distal end face, and a recess opened on the distal end face and a protrusion section including a base that overlaps the recess in plan view of the distal end face and is fixed to the distal end face and a projection that is provided in the base and projects in an opposite direction of the distal end face, the protrusion section transmitting a driving force of the vibrating section to a driven section. In plan view of the distal end face, the projection is disposed within a range of the recess.

A piezoelectric motor includes a piezoelectric actuator, a holding member that holds the piezoelectric actuator, a housing in which the piezoelectric actuator and the holding member are placed, a first positioning pin that positions the holding member and the housing, and a first fixing part that fixes the first positioning pin. In the piezoelectric motor, the first positioning pin is fixed to one of the holding member and the housing, and a first hole portion in which the first positioning pin is placed is provided in the other of the holding member and the housing. The first fixing part fixes relative positions of the first hole portion and the first positioning pin.

A piezoelectric drive device includes a vibrator having a vibrating portion including a piezoelectric element, and a convex portion placed in the vibrating portion, an urging member including a base, a holding portion holding the vibrator, and a spring portion coupled to the base at one end and coupled to the holding portion at another end and urging the convex portion toward a driven unit, wherein d1>d2 in a natural state in which the vibrator is not urged by the urging member, where a separation distance between the one end and the convex portion along directions of the longitudinal direction is d1 and a separation distance between the other end and the convex portion is d2, and |d1−d2| in an urging state in which the vibrator is urged toward the driven unit by the urging member is smaller than |d1−d2| in the natural state.

Provided is a vibration wave driving apparatus comprising: a vibration actuator; and a driven member configured to be driven by the vibration actuator, wherein the vibration actuator includes: a vibrator having an electric-mechanical energy conversion element and an elastic member to which the electric-mechanical energy conversion element is fixed; a pressurizing member configured to pressurize the vibrator; a contacting member configured to pressurizing-contact with the vibrator by pressurizing the vibrator by the pressurizing member and move relative to the vibrator; an outputting member configured to output a driving force to the driven member, the driving force generated by the relative-moving of the contacting member to the vibrator, and wherein the driven member includes an output transmission member configured to hold the outputting member in a direction of the relative-moving with a predetermined spring force.

A vibrating actuator includes a contact body and a vibrating body that vibrates, has an energy conversion element, and has an elastic body in contact with the contact body to move relative to each other from the vibration. The contact body has a base part, a thin plate part, a support part, and a friction member. The thin plate part extends from the base part toward an annular center axis of the base part and the support part is disposed at an end of the thin plate part. The friction member is disposed to the support part as a member separate from the support part and in contact with the elastic body. Density of the friction member is higher than density of the thin plate part. A weight ratio of the thin plate part to a total weight of the friction member and the support part is 0.5 to 1.5.

Provided is a lead-free piezoelectric material reduced in dielectric loss tangent, and achieving both a large piezoelectric constant and a large mechanical quality factor. A piezoelectric material according to at least one embodiment of the present disclosure is a piezoelectric material including a main component formed of a perovskite-type metal oxide represented by the general formula (1): Na.sub.x+s(1−y)(Bi.sub.wBa.sub.1−s−w).sub.1−yNb.sub.yTi.sub.1−yO.sub.3 (where 0.84≤x≤0.92, 0.84≤y≤0.92, 0.002≤(w+s)(1−y)≤0.035, and 0.9≤w/s≤1.1), and a Mn component, wherein the content of the Mn is 0.01 mol % or more and 1.00 mol % or less with respect to the perovskite-type metal oxide.