A vibration-type actuator capable of suppressing reduction in holding torque or holding force under influence of humidity. A vibration-type actuator 10 includes a vibrating body 2 and a driven body 1. The vibrating body 2 has a piezoelectric element 2c and an elastic body 2b. The driven body 1 is in contact with the vibrating body 2. The vibration-type actuator 10 moves the vibrating body 2 and the driven body 1 relatively to each other by vibration excited to the vibrating body 2. At least one of a first contact portion of the vibrating body 2 and a second contact portion of the driven body 1 includes a stainless-steel sintered body with pores and at least some of the pores are impregnated with a resin.

A vibration actuator includes a vibration element including a piezoelectric element as an electromechanical energy conversion element and an elastic body which is joined to the piezoelectric element, and a driven element which is brought into pressure contact with the elastic body. Driving vibration is excited in the vibration element by applying a drive signal to the piezoelectric element, whereby the vibration element and the driven element are moved relative to each other. The driving vibration is a vibration in which at least n-th-order vibration and 2n-th-order vibration are combined, n being a natural number.

The present invention provides a piezoelectric material not containing lead and potassium, showing satisfactory insulation and piezoelectricity, and having a high Curie temperature. The invention relates to a piezoelectric material includes a main component containing a perovskite-type metal oxide represented by Formula (1): (Na.sub.xBa.sub.1-y)(Nb.sub.yTi.sub.1-y)O.sub.3 (wherein, 0.80x0.94 and 0.83y0.94), and an additive component containing at least one element selected from Mn and Ni, wherein the content of the Ni is 0 mol or more and 0.05 mol or less based on 1 mol of the perovskite-type metal oxide, and the content of the Mn is 0 mol or more and 0.005 mol or less based on 1 mol of the perovskite-type metal oxide.

An ultrasonic vibration application tool equipped with a Langevin type ultrasonic vibrator which is suitably employable for ultrasonic processing devices and which efficiently generates ultrasonic vibration includes: a cylindrical housing having a contact face on a lower or bottom part of an inner surface thereof, and a lower screw part of an outer surface thereof; a bolted Langevin type ultrasonic vibrator comprising a front mass, a rear mass and a polarized piezoelectric element arranged between both masses, in which the front mass comprises a cylindrical tool-holder and a disc-shaped bulging part provided with a contact face for fitting to the contact face of the housing; and a ring-shaped counterweight having an upper screw part on an inner peripheral surface which is screwed with the screw part of the housing.

A vibration drive device that is capable of preventing the controllability from becoming unstable when the speed control is switched between frequency control and pulse width control. A controller controls driving of a vibration actuator by applying an alternating voltage to an electromechanical energy conversion element. A switching pulse is generated by switching a DC voltage. A maximum duty ratio of the switching pulse is determined based on a driving condition of the vibration actuator. The driving of the vibration actuator is controlled by switching between frequency control and pulse width control. A gain for frequency control and a gain for pulse width control are set according to the maximum duty ratio so as to prevent electric power or electric current from exceeding an electric power limit or an electric current limit, set in advance.

A lead-free piezoelectric element that stably operates in a wide operating temperature range contains a lead-free piezoelectric material. The piezoelectric element includes a first electrode, a second electrode, and a piezoelectric material that includes a perovskite-type metal oxide represented by (Ba.sub.1-xCa.sub.x).sub.a(Ti.sub.1-yZr.sub.y)O.sub.3 (1.00a1.01, 0.02x0.30, 0.020y0.095, and yx) as a main component and manganese incorporated in the perovskite-type metal oxide. The manganese content relative to 100 parts by weight of the perovskite-type metal oxide is 0.02 parts by weight or more and 0.40 parts by weight or less on a metal basis.

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 Ti 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.

There are provided a lead- and potassium-free piezoelectric material that has a high Curie temperature and a high mechanical quality factor and is stable in long-term driving and a piezoelectric element including the lead- and potassium-free piezoelectric material. A piezoelectric material containing a perovskite-type metal oxide having the general formula (1): Na.sub.xBa.sub.1-yNb.sub.yZr.sub.1-yO.sub.3 wherein x satisfies 0.85x0.96 and y satisfies 0.90y0.96 and a piezoelectric element including the piezoelectric material. The piezoelectric material may include the perovskite-type metal oxide and Cu, and the Cu content corresponds to 2.00 mol % or less of the amount of the perovskite-type metal oxide.

A barium titanate piezoelectric ceramic having good piezoelectric properties and mechanical strength and a piezoelectric element that includes the ceramic are provided. A method for making a piezoelectric ceramic includes forming a compact composed of an oxide powder containing barium titanate particles, sintering the compact, and decreasing the temperature of the compact after the sintering. The sintering includes (A) increasing the temperature of the compact to a first temperature within a temperature range of a shrinking process of the compact; (B) increasing the temperature of the compact to a second temperature within a temperature range of a liquid phase sintering process of the compact after (A); (C) decreasing the temperature of the compact to a third temperature within the temperature range of the shrinking process of the compact after (B); and (D) retaining the third temperature after (C).

A vibration actuator includes a vibrator including a shaft, an output transmission member penetrated by the shaft, and configured to rotate about the axis of the shall, and a fixed member configured not to move relative to the shaft and configured to move relative to the output transmission member. The fixed member includes a base portion and a projection portion protruding from the base portion to the output transmission member side, the vibration actuator includes a pressure reception member between the base portion and the output transmission member in an axial direction of the shaft, and wherein the projection portion and the output transmission member are in contact with each other in a direction orthogonal to the axial direction of the shaft, and the projection portion and the output transmission member are not in contact with each other in the axial direction of the shaft.