A vibration wave motor comprises: an electromechanical conversion element; an elastic body which has a drive surface on which a vibration wave is generated due to vibration of the electromechanical conversion element; and a relative motion member which makes contact with the drive surface of the elastic body and is configured to rotationally drive by the vibration wave, the electromechanical conversion element having a density of from 4.2 to 6.0×10.sup.3 kg/m.sup.3, a plurality of grooves being provided on the drive surface side of the elastic body, and a value of T/(B+C) being within a range of from 1.3 to 2.8 when: depth of at least one groove of the plurality of grooves is defined as T; thickness from a base unit of the groove to a first surface is defined as B; and thickness of the electromechanical conversion element is defined as C.

A control method for a piezoelectric drive device includes a first step of executing first control to decrease a frequency of a drive voltage applied to a piezoelectric vibrator from a predetermined first frequency while acquiring a pickup voltage representing vibration amplitude of the piezoelectric vibrator, and a second step of executing second control to increase the frequency of the drive voltage applied to the piezoelectric vibrator to a second frequency as a frequency of the drive voltage applied before a second time when the pickup voltage is higher from a first time to the second time and the pickup voltage is lower from the second time to a third time.

A method of fabricating an apparatus for piercing an object, the apparatus comprises: a substrate; one or more needles; one or more anchors and one or more piezoelectric actuators. The method comprises the steps of deposit sacrificial layer over the substrate; deposit conducting layer over the sacrificial layer; deposit piezoelectric layer over the conducting layer; etch a geometry of the one or more piezoelectric actuators using a first mask created by lithography process; deposit the one or more needle and one or more anchors using a second mask created by lithography process and a lift-off process; etch the sacrificial layer under the needle and the one or more piezoelectric actuators, wherein the anchors are configured to connect the substrate to the piezoelectric actuators and the one or more piezoelectric actuators are configured to move the one or more needles.

A control device for a vibration actuator includes a detection signal acquisition section adapted to obtain an alternating-current detection signal corresponding to a vibration of the resonator body from the resonator bodies, a phase difference detection section adapted to detect a phase difference between the drive signal and the detection signal with respect to the resonator bodies, a resonator body selection section adapted to select one from the resonator bodies, and a drive signal control section adapted to adjust a frequency of the drive signal so that the phase difference in the resonator body selected comes closer to a target value.

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 control apparatus to control a vibration motor includes a control unit. The vibration motor includes a vibration body and a contact body contacting the vibration body. The control apparatus applies alternating voltages, generated based on pulse width and frequency of pulse signals, to an electro-mechanical energy conversion element of the vibration motor to cause relative movement between the vibration and contact bodies at a target velocity. The pulse width and the frequency are (i) set such that a first steady velocity exceeds the target velocity, before the relative movement starts, and (ii) changed such that a second steady velocity is less than the first steady velocity, after the relative movement starts, and before an actual velocity at a time of the relative movement exceeds the target velocity. The pulse width or the frequency is controlled such that the relative movement is performed at the target velocity.

An optical element driving mechanism is provided. The optical element driving mechanism includes a fixed portion, a movable portion, a first driving assembly, and a positioning element. The movable portion is movably disposed on the fixed portion and comprises an optical element, wherein the optical element moves in the first direction. The first driving assembly is at least partially disposed on the fixed portion. The positioning element is rotatably disposed on the fixed portion or the movable portion, wherein when the first driving assembly is not activated, the positioning element is used to limit the position of the movable portion relative to the fixed portion to a limit position.

An optical system is provided. The optical system includes a first optical module. The first optical module includes a first fixed portion, a first movable portion, a first driving assembly, and a circuit assembly. The first movable portion is used for connecting to a first optical element, and the first movable portion is movably connected to the fixed portion. The first driving assembly is used for driving the first movable portion to move relative to the first fixed portion. The circuit assembly is electrically connected to the first driving assembly.

A controller capable of reducing time required to stop a control target at a target stop position as a final stop position. The controller drives a vibration element including a piezoelectric element by an AC signal to thereby move a contact body in contact with the vibration element relative to the vibration element. The controller controls a pulse duty cycle of a signal converted to the AC signal based on a difference between a target stop position which is a final stop position of the contact body and a current position of the contact body, and an actual speed of the contact body.

Noise produced during phase-difference changes is minimized without decreasing the responsiveness of a vibration-wave motor. A lens-side MCU for a lens barrel controls a drive apparatus that applies a drive voltage to the vibration-wave motor by outputting an A-phase drive signal and a B-phase drive signal thereto. The lens-side MCU uses, for example, a drive-voltage setting unit and a duty-cycle change unit to change the drive voltage. Also, the lens-side MCU is provided with a phase-difference change unit that changes the phase difference between the A-phase drive signal and the B-phase drive signal. When driving the vibration-wave motor, the lens-side MCU changes the drive voltage to V.sub.reg, and when the phase-difference change unit is changing the aforementioned phase difference, the drive voltage is changed to V.sub.1, V.sub.1 being greater than zero and less than V.sub.reg.