The present invention provides a lead-free piezoelectric material having a high piezoelectric constant and a high mechanical quality factor in a wide operating temperature range. The piezoelectric material includes a perovskite-type metal oxide represented by Formula (1):
(Ba.sub.1-xCa.sub.x).sub.a(Ti.sub.1-yZr.sub.y)O.sub.3 (1.00≦a≦1.01, 0.125≦x<0.155, and 0.041≦y≦0.074)
as a main component. The metal oxide contains Mn in a content of 0.12 parts by weight or more and 0.40 parts by weight or less based on 100 parts by weight of the metal oxide on a metal basis.

There is provided a piezoelectric material not containing any lead component, having stable piezoelectric characteristics in an operating temperature range, a high mechanical quality factor, and satisfactory piezoelectric characteristics. The piezoelectric material includes a main component containing a perovskite-type metal oxide that can be expressed using the following general formula (1), and subcomponents containing Mn, Li, and Bi. When the metal oxide is 100 parts by weight, the content of Mn on a metal basis is not less than 0.04 parts by weight and is not greater than 0.36 parts by weight, content α of Li on a metal basis is not less than 0.0013 parts by weight and is not greater than 0.0280 parts by weight, and content β of Bi on a metal basis is not less than 0.042 parts by weight and is not greater than 0.850 parts by weight
(Ba.sub.1-xCa.sub.x).sub.a(Ti.sub.1-y-zZr.sub.ySn.sub.z)O.sub.3  (1)
(in the formula (1), 0.09≦x≦0.30, 0.074<y≦0.085, 0≦z≦0.02, and 0.986≦a≦1.02).

Provided is a piezoelectric material that is free of lead and potassium, has satisfactory insulation property and piezoelectricity, and has a high Curie temperature. The piezoelectric material includes a perovskite-type metal oxide represented by the following general formula (1): General formula (1) (Na.sub.xM.sub.1-y)(Zr.sub.z(Nb.sub.1-wTa.sub.w).sub.y(Ti.sub.1-vSn.sub.v).sub.(1-y-z))O.sub.3 where M represents at least any one of Ba, Sr, and Ca, and relationships of 0.80≦x≦0.95, 0.85≦y≦0.95, 0<z≦0.03, 0≦v<0.2, 0≦w<0.2, and 0.05≦1−y−z≦0.15 are satisfied.

Provided is a lead-free piezoelectric material having satisfactory piezoelectric constant and mechanical quality factor in a device driving temperature range (−30° C. to 50° C.) The piezoelectric material includes a main component containing a perovskite-type metal oxide represented by Formula 1, a first auxiliary component composed of Mn, and a second auxiliary component composed of Bi or Bi and Li. The content of Mn is 0.040 parts by weight or more and 0.500 parts by weight or less based on 100 parts by weight of the metal oxide on a metal basis. The content of Bi is 0.042 parts by weight or more and 0.850 parts by weight or less and the content of Li is 0.028 parts by weight or less (including 0 parts by weight) based on 100 parts by weight of the metal oxide on a metal basis. (Ba.sub.1-xCa.sub.x).sub.a(Ti.sub.1-yZr.sub.y)O.sub.3 . . . (1), wherein, 0.030≦x<0.090, 0.030≦y≦0.080, and 0.9860≦a≦1.0200.

A piezoelectric material which is low in load on the environment, and also satisfies both the requirements of a high piezoelectric constant and a high mechanical quality factor. The piezoelectric material comprises a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O. An average equivalent circle diameter of the crystal grains is not smaller than 1.0 μm and not larger than 10 μm. The crystal grains include crystal grains A each having a first domain with a width of not smaller than 300 nm and not larger than 800 nm, and crystal grains B each having a second domain with a width of not smaller than 20 nm and not larger than 50 nm.

A control apparatus controls driving a vibratory actuator. The control apparatus applies a signal to an electromechanical energy conversion device of a vibrator of the vibratory actuator to excite vibration on the vibrator and cause the vibrator and a driven object contacting the vibrator to move relative to one another by the vibration. If the vibratory actuator decelerates, the control apparatus changes a driving frequency of the signal to a frequency higher than a start-up frequency of the vibratory actuator and a preceding frequency at a deceleration start position. After changing the driving frequency of the signal, the control apparatus controls the signal driving frequency to perform deceleration control and fixes voltage of the signal in a deceleration period in which the vibratory actuator is decelerated.

A vibration actuator includes an electro-mechanical transducer, a vibrating body fixed to the electro-mechanical transducer, the vibrating body being vibrated by applying a voltage to the electro-mechanical transducer, and a driven body contacting the vibrating body. The driven body is frictionally driven by a vibration of the vibrating body. The driven body includes a first extended portion extending from a main body portion of the driven body towards an inside diameter side of the vibrating body, a second extended portion extending from the first extended portion towards the outside diameter side of the vibrating body, and a contact surface provided at a tip of the second extended portion. The contact surface contacts the vibrating body. The first extended portion, the second extended portion, and the contact surface are each capable of elastically deforming in a rotational axis direction of the driven body.

The apparatus consists of a highly conductive contact disc member preferably an annular circular disc that is attached rigidly to a shaft member with a shaft member collar to rotates freely with the shaft member on a pair of bearings (or bushes), in a pair of housing members. The contact disc member has an even number of piezoelectric crystals attached radially to the circumferential contact disc member electrical contacts to form a symmetric array. An equal number of equal massive members are attached to the other ends of the piezoelectric crystals, again to form, a symmetric array about the rotation axis of the shaft member. Each of the massive members has the same weight for balance. Thus, each massive member is held unto the contact disc member's circumference by a piezoelectric crystal. Each massive member has a diametrically opposite massive member that can balance its weight.

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 instability when the speed control is switched between frequency control and pulse width control includes a controller that 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.