A piezoelectric drive unit is configured for driving a passive element relative to an active element, wherein the active element includes a resonator with two arms, each extending in parallel to a reference plane and ending in a contact element, which is movable by oscillating movements of the arms and thereby drives the passive element. Each of the arms has, at the outer end of the arm, a protrusion extending inward, toward the other arm, and on at least one of the arms, the respective contact element, arranged at the arm's outer end, extends outward, away from the other arm.

A method of controlling a piezoelectric driving apparatus including a vibration section that has a piezoelectric element and a transmission section that transmits vibration of the vibration section to a driven body, and, by energization of the piezoelectric element, vibrates the vibration section in a combination of longitudinal vibration and bending vibration to cause the transmission section to perform an elliptical motion and to move the driven body by the elliptical motion, the method of controlling the piezoelectric driving apparatus including switching, according to an external force received by the driven body, a drive algorithm of the piezoelectric driving apparatus between a first drive mode in which a separation amplitude, which is an amplitude of the longitudinal vibration, is changed while a feed amplitude, which is an amplitude of the bending vibration, is constant and a second drive mode in which both the feed amplitude and the separation amplitude are changed.

A control method for a piezoelectric motor having a vibrating portion including a piezoelectric element and a transmitting portion transmitting vibration of the vibrating portion to a driven member, and synthesizing longitudinal vibration and flexural vibration by energization of the piezoelectric element to vibrate the vibrating portion and elliptically move the transmitting portion and moving the driven member by the elliptical motion, includes changing an orbit of the elliptical motion according to a load received by the transmitting portion.

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 piezoelectric drive device driving a driven member by a projecting portion provided on one end of a vibrator including a piezoelectric element, includes a fixing portion fixing the piezoelectric drive device, a holding portion holding the vibrator, an urging portion coupled to the fixing portion and urging the holding portion including the vibrator in a direction toward the projecting portion, a weight portion provided at an opposite side to the projecting portion in the holding portion, and an elastic portion placed between the holding portion and the weight portion.

A piezoelectric drive device includes a piezoelectric drive portion which includes a contact portion capable of coming into contact with a driven body and a piezoelectric material, and a drive circuit which drives the piezoelectric drive portion. The drive circuit sets an allowable maximum output torque Tlim or less to an allowable output torque range, sets output torque Td of the piezoelectric drive portion so as to be within the allowable output torque range, and operates the piezoelectric drive portion. The allowable maximum output torque Tlim is expressed by the following Expression (1).
Tlim=r1×μk×Ns×fs  (1)
In the expression, r1 is a distance between a rotation center of the driven body and a contact position of the contact portion, μk is a dynamic friction coefficient between the driven body and the contact portion, Ns is a pressing force by which the contact portion presses the driven body when an operation of the piezoelectric drive portion stops, and fs is a coefficient of 1 or less.

A piezoelectric drive device includes a rotor which has an output section for outputting a rotational force and a transmission section disposed on an outer periphery of the output section, and rotates around a rotational axis, and a vibrating part which has a piezoelectric element, and rotates the rotor due to a deformation of the piezoelectric element. The transmission section has a first portion and a second portion different from each other in position in a radial direction from the output section toward the transmission section, the first portion is coupled to the output section, the second portion is higher in Young's modulus than the first portion, the second portion is higher in mass per unit volume than the first portion, and the vibrating part makes contact with the transmission section at a position overlapping the second portion in a plan view from an axial direction of the rotational axis.

A piezoelectric actuator includes a first piezoelectric element that outputs a first signal when being driven, a second piezoelectric element that outputs a second signal when being driven, a signal combining part that delays phase of the second signal and outputs a composite signal by combination of the second signal and the first signal, and a drive state determination part that determines respective drive states of the first piezoelectric element and the second piezoelectric element based on the composite signal.

A first driving signal is supplied to a first electrode of a vibrating body. A second driving signal is supplied to a second electrode of the vibrating body. A common driving signal is supplied to a common electrode of the vibrating body. A phase of the first driving signal is set changeable with respect to a phase of the common driving signal. A phase of the second driving signal is set changeable with respect to the phase of the common driving signal. Then, it is possible to switch a driving direction of a piezoelectric motor according to which phase of the first driving signal or the second driving signal is varied from the phase of the common driving signal. If the phase is simply changed, a switch is unnecessary. It is possible to reduce a driving circuit in size.

A piezoelectric driving device includes a vibrating portion including a piezoelectric element for driving and a piezoelectric element for detection and vibrating by driving of the piezoelectric element for driving, a drive circuit that generates a drive signal for driving the piezoelectric element for driving, and a detection circuit that detects vibration of the vibrating portion based on a detection signal output from the piezoelectric element for detection with the vibration of the vibrating portion, wherein the piezoelectric element for detection is placed in an area containing a center of the vibrating portion.