Abstract: The mechanical differential actuator according to the present invention comprises a mechanical differential having three mechanicals ports. A first transducer with a low impedance is coupled to a first port, a second transducer with a high impedance is coupled to a second port, and the mechanical load is coupled to the third port. The mechanical differential actuator enables controlling a force and a speed at a load coupled thereto through a known relation between the force and the speed. Moreover, the mechanical differential actuator presents a compact structure enabling the transfer of a large force relative to its volume.

Abstract: One embodiment provides a piezoelectric vibrator driving circuit for driving a piezoelectric vibrator, the piezoelectric vibrator having an equivalent circuit in which an LC series resonance circuit, an equivalent resistor Rx connected in series thereto and a damping capacitor Co connected in parallel to them are provided, the driving circuit is configured: to detect a driving current Iz flowing through the entire piezoelectric vibrator; to detect a damping current Iy flowing through the damping capacitor Co; to calculate a series resonance current Ix flowing through the LC series resonance circuit by subtracting the detected damping current Iy from the detected driving current Iz; and to perform a phase adjustment so that a phase difference between the calculated series resonance current Ix and a driving voltage Ve to be applied to the piezoelectric vibrator becomes approximately 0.

Abstract: A substantially spherical rotor can be controlled with accuracy even in a relatively low speed rotation. In controlling rotational motions of a rotor 3 of a spherical ultrasonic motor 1, phases of voltages to be applied to three stators 9a, 9b, 9c are determined to set the direction of a rotation axis of the rotor 3. Frequencies of voltages to be applied to the three stators 9a, 9b, 9c are adjusted to control the rotation speed of the rotor 3. Thereby, control with high accuracy is enabled in a relatively low speed rotation.

Abstract: A driving method for a piezoelectric vibrator including a driving piezoelectric element and a detection piezoelectric element formed of the same material as a material of the driving piezoelectric element, for driving the piezoelectric vibrator by applying, to the driving piezoelectric element, an alternating voltage having a frequency close to a resonance frequency of the piezoelectric vibrator, the driving method including, in the case where it is detected based on variations in output detected from the detection piezoelectric element that at least one of variations in mechanical resistance of the piezoelectric vibrator and variations in piezoelectric characteristic of a piezoelectric element have occurred, applying an alternating voltage adjusted in accordance with the variations in mechanical resistance of the piezoelectric vibrator and/or the variations in piezoelectric characteristic of the piezoelectric element, to thereby adjust an electrical input to the piezoelectric vibrator to suppress variations

Abstract: A device is provided for resonantly driving a micromechanical system, which includes at least one seismic mass supported by spring vibrations, at least one drive for driving the vibration of the seismic mass and at least one element that is motionally coupled to the seismic mass. Furthermore, the device includes at least one detection element for detecting a relational parameter, that changes with the vibration of the seismic mass, between the motionally coupled element and the detection element, the detection element being equipped to cause an interruption of the vibration drive when a predetermined value of the relational parameter is reached.

Abstract: An electromechanical motor includes an actuator assembly and a body to be driven in a driving direction. The actuator assembly has an actuator backing, a first actuator and a second actuator. The actuators are mechanically attached by a respective single attachment to the actuator backing at a first end of the actuators. The actuators have a respective interaction portion constituting a second end opposite to the first end in an actuator direction transverse to the driving direction. The interaction portions are arranged for interaction with an interaction surface of the body by a respective contact area. The actuators include a respective unimorph member arranged for causing a movement of the respective contact area as a response of a respective electrical signal. The respective movements are transverse to the actuator direction, to the driving direction, and to each other.

Abstract: The present invention relates to a method of measuring and evaluating rigidity of a target object or mechanical output, such as force, displacement, and mechanical energy generated by a piezoelectric actuator and applied to the target object, according to only a measured value of electric quantity without use of a mechanical sensor, and a method of controlling the piezoelectric actuator, and a device using these methods. Steps of finding equivalent circuit constants of the piezoelectric actuator; applying a voltage to the piezoelectric actuator and measuring electrical quantity flowing into the piezoelectric actuator due to the applied voltage, or applying an electric charge to the piezoelectric actuator and measuring voltage applied to the piezoelectric actuator due to the applied electric charge; and measuring and evaluating one or more of force, displacement, or mechanical energy generated by the piezoelectric actuator and applied to a target object, or rigidity of a target object are included.

Abstract: A method, actuating device, and microsystem device are described for controlling a micromechanical actuator, which has a rechargeable capacitor for generating a mechanical motion of the micromechanical actuator, a memory having a lookup table containing previously computed data of signal shapes for controlling the micromechanical actuator, and a driver circuit having a driver circuit control unit for processing the previously computed data, a power stage for generating the signal shapes, and an output for outputting the signal shapes, corresponding to previously computed data, to the micromechanical actuator's rechargeable capacitor. The micromechanical actuator has a limiting device, between the output of the driver circuit and the micromechanical actuator, which is for limiting a voltage excursion of the signal shapes output by the driver circuit, which are usable for generating the mechanical motion by recharging the micromechanical actuator's rechargeable capacitor.

Abstract: A system and method is provided for determining the capacitance between electrodes of an artificial muscle or dielectric elastomer actuator (DEA). The method comprises measuring the voltage difference between the electrodes of the DEA, the first derivative of that voltage with respect to time, and the total instantaneous current through the DEA, then calculating the capacitance of the DEA as the difference between the total instantaneous current through the DEA and the product of the voltage between the electrodes and an error term, divided by the first derivative of the voltage between the electrodes with respect to time. The capacitance may then be used to derive estimates of the leakage current, charge upon the DEA, and/or the physical state of the DEA, thereby implementing self-sensing to allow closed-loop feedback control of DEA actuation.

Abstract: A control device for an ultrasonic piezoelectric actuator including a first stage supplied by a DC voltage source and including a mechanism forming a second DC voltage above that voltage delivered by the DC voltage source, and a second stage including a mechanism amplifying the second voltage and chopping the voltage obtained by excitation of the actuator with the chopped voltage, under control of a computer. The amplifying mechanism includes an inductor in electrical resonance with the piezoelectric actuator. The inductor is connected to the first stage so as to constitute, during formation of the second voltage, a secondary winding of a transformer forming part of a flyback voltage converter introduced into the first stage to develop the second voltage. The control device may find application to control of a fuel injector in an internal combustion engine.

Abstract: The present invention relates to a method of controlling the speed of rotation of a piezoelectric motor comprising at least one step of determining the variation of the speed of rotation as a function of the frequency of the excitation voltages of the piezoelectric motor for the actual temperature of the piezoelectric material.

Abstract: A control apparatus detects the relative position between a vibration member and a driving-member-side vibration detection portion on the basis of a signal that shows a vibrational state of the vibration member and a signal output from the driving-member-side vibration detection portion, the driving-member-side vibration detection portion being provided on a driving member and detecting a vibration of the driving member.

Abstract: Disclosed is an apparatus for monitoring a material configured to perform one or more functions or for actuating the material. One or more electrodes are coupled to the material. An electronic device is coupled to the one or more electrodes and is configured to detect an electrical characteristic of the material to monitor the material or to apply an electrical stimulus to actuate the material.

Abstract: A semiconductor device applies a hold voltage Vhold to an upper electrode of an electrostatic actuator and a ground voltage to a lower electrode. After the semiconductor device sets the voltage of the lower electrode to a test voltage Vtest, it eliminates the hold voltage Vhold from the upper electrode and places the voltage of the upper electrode in a high impedance state. The potential difference between the upper electrode and the lower electrode is set to Vhold?Vtest=Vmon. Thereafter, the voltage of the lower electrode is returned to the ground voltage. Whether the electrostatic actuator is placed in an open state or in a closed state is determined by measuring the capacitance between the electrodes based on the amount of drop of the voltage of the upper electrode due to capacitance coupling at the time.

Abstract: A control apparatus is configured to control an actuator, which moves one driven member by a plurality of vibrators, by supplying two alternating-current signals to each vibrator of the actuator. The control apparatus includes a controller configured to acquire a speed characteristic of the driven member corresponding to the frequency of the alternating-current signal with respect to the vibrator(s) based on the acquired speed and the frequency of the alternating-current signal supplied to the vibrator(s) at the time of the acquisition of the speed, and reduce a difference in the characteristic among the plurality of vibrators by adjusting at least one of an amplitude of an alternating-current signal to be supplied to the vibrator, a frequency of an alternating-current signal to be supplied to the vibrator, and a phase difference between two alternating-current signals to be supplied to the vibrator, based on the acquired characteristic.

Abstract: To provide a piezo-electric actuator drive circuit capable of efficiently driving a piezo-electric actuator. The present invention is a piezo-electric actuator drive circuit (3) for driving a piezo-electric actuator (2) in which a drive voltage is applied to polarizing sections (4a, 4b), and includes a high voltage power supply (14), a high-side switching element (16), a low-side switching element (18), and a switching element control circuit (12) for applying a voltage pulse to polarizing sections and driving the piezo-electric actuator by switching between a voltage-applied period in which only the high-side switching element is in a conductive state, a floating period in which both the high-side switching element and the low-side switching element are in a nonconductive state, and a grounded period in which only the low-side switching element is in a conducting state.

Abstract: Provided is a control apparatus of a vibration-type actuator for generating an elliptical motion of contact portions by a common alternating current signal including a frequency determining unit for setting a frequency of the alternating current signal. The frequency determining unit sets the frequency of the alternating current signal for changing an ellipticity of the elliptical motion, within a frequency range such that ellipticity changing frequency ranges set for the vibrators are overlapped, and the ellipticity changing frequency ranges are set for the vibrators as frequency ranges between an upper limit and a lower limit, such that the lower limit is a maximum resonant frequency at a time of changing the ellipticity, and the upper limit is larger than the lower limit and is a maximum frequency for the relative movement of the driving member.

Abstract: The present invention relates to a method of controlling the speed of rotation of a piezoelectric motor comprising at least one step of determining the variation of the speed of rotation as a function of the frequency of the excitation voltages of the piezoelectric motor for the actual temperature of the piezoelectric material.

Abstract: Some embodiments regard a method comprising: generating a current according to a movement of the MEMS device; the movement is controlled by a control signal; generating a peak voltage according to the current; and adjusting the control signal when the peak voltage is out of a predetermined range.

Abstract: The disclosure pertains to a method of charging or discharging a capacitive element, such as a piezoelectric crystal. The disclosure also pertains to a device that implements charging of a capacitive element according to said method. The device comprises a bipolar buck-boost converter, whereby a capacitive element can be charged with both positive and negative voltages. The discharge of the capacitive element is provided with energy recovery and feedback to the device's power supply.

Abstract: In a discharge process of the solid body actuator (2), a current that discharges the solid body actuator (2) loaded with electrical energy is detected. A switching element (6) is switched from an open position to a closed position to short circuit the solid body actuator (2) for removal of electrical energy from the solid body actuator (2) through the switching element (6) depending on the current falling below a threshold of the current, wherein the magnitude of the threshold is specified.

Abstract: A method for operating an electrostatic drive having a stator electrode and an actuator electrode which are designed as multilayer electrodes having subunits includes: predeflecting the actuator electrode with respect to the stator electrode from its non-energized starting position into a first end position by applying a first potential to the first stator electrode subunit, and applying a second potential which is different from the first potential to the first actuator electrode subunit, and applying a third potential which is different from the first potential and the second potential, to the second stator electrode subunit and to the second actuator electrode subunit.

Abstract: A self-tuning vibration absorber including a carrier rod assembly having operatively connected thereto a mounting mechanism for mounting the carrier rod assembly to a primary system and a hollow shafted motorized tuning mechanism for tuning a phase difference between vibration of the primary system and vibration of the carrier rod assembly to 90 degrees, the carrier rod assembly further including a detecting mechanism for detecting the vibration of the primary system and the vibration of the carrier rod assembly, and a controller in electrical connection with the detecting mechanism and the tuning means for controlling the tuning mechanism based on the vibration of the primary system and the vibration of the carrier rod assembly detected. A method of vibration dampening, a method of controlling a self-tuning vibration absorber, and a method of reducing hunting motion in railcars.

Abstract: A control circuit is provided for a vibration-type actuator that generates a vibration wave in a vibrating member by applying an alternating voltage, and relatively rotates a moving member contacting protrusions of the vibrating member. The control circuit includes a feedback control circuit and a repetitive compensator. The feedback control circuit subjects the vibration-type actuator to feedback control based on a deviation between a relative speed between the moving member and the vibrating member and a command speed or a deviation between a relative position between the moving member and the vibrating member and a command position. The repetitive compensator provides a repetitive period that is set to T/(an integral multiple of fs), where T is a period of rotation of the moving member, and fs is a spatial frequency of a speed deviation based on a contact area distribution between the protrusions and the moving member.

Abstract: In order to provide a driving device that is capable of eliminating sticking of a movable member due to nonuse, the driving device includes a drive shaft that reciprocates in axial directions with expansion and contraction of an electromechanical transducer element, a movable member that frictionally engages with the drive shaft, and a drive circuit that inputs drive voltage into the electromechanical transducer element, the drive circuit outputting drive operation pattern voltage having a frequency (fd1?) lower than a resonance frequency (fr) of the electromechanical transducer element and lower than a frequency (fd1) that maximizes moving velocity of the movable member and sticking elimination pattern voltage having a frequency lower than the frequency (fd1?) of the drive operation pattern voltage and in vicinity of a frequency (fd2) that maximizes thrust acting on the movable member.

Abstract: A driving unit of a vibration-type actuator includes a command unit, a change making unit, an AC signal generating unit, and a filter unit. The command unit outputs a command signal that directs at least one of a frequency, an amplitude, and a phase difference of an AC signal. The change making unit makes a change to the command signal and outputs the command signal. The AC signal generating unit generates a generated AC signal in which at least one of a frequency, an amplitude, and a phase difference of the generated AC signal is modulated in accordance with the output of the change making unit. The filter unit selectively dampens a frequency component, of at least one of the output signal of the change making unit and an output signal of the AC signal generating unit, that excites vibration other than vibration in a predetermined vibration mode.

Abstract: Provided is a Micro-Electro-Mechanical Systems (MEMS) device for actuating a gimbaled element, the device including a symmetric electromagnetic actuator for actuating one degree of freedom (DOF) and a symmetric electrostatic actuator for actuating the second degree of freedom.

Abstract: There is provided a drive control device including: a wiring board connected to an actuator; two driver ICs each having a plurality of common signal input terminals and selection signal input terminals arranged in one direction; and a control section transmitting a plurality of types of common signals and selection signals to the two driver ICs, respectively, in which the two driver ICs are disposed to face to each other on the wiring board so that the common signal input terminals in the respective driver ICs are each arranged in reverse directions to each other, and the paired common signal input terminals that are disposed in the one direction in the same order when counted from one side are wired respectively.

Abstract: According to one embodiment, a method of driving an electrostatic actuator includes a first electrode provided on a substrate, a second electrode arranged above the first electrode to be movable in a vertical direction, and an insulating film provided between the first electrode and the second electrode, includes boosting a power supply voltage to generate a driving voltage of the electrostatic actuator, and applying the driving voltage to each of the first electrode and the second electrode when setting the electrostatic actuator in an up state.

Abstract: An electro-mechanical actuator includes a comb drive and a deformable connector. The comb drive has a first capacitor plate and a second capacitor plate. The capacitor plates have teeth capable of inter-digitating. The deformable connector is configured to apply a mechanical restoring force to the first capacitor plate. The deformable connector is configured to restore the first capacitor plate to be at an equilibrium rest position in response to no control voltage being applied across the capacitor. The comb drive is more engaged at the equilibrium rest position than at a mechanical stability threshold of the comb drive. The capacitor plates are disengaged at the equilibrium rest position.

Abstract: A flywheel system has an approximately toroidal flywheel rotor having an outer radius, the flywheel rotor positioned around and bound to a hub by stringers, the stringers each of a radius slightly smaller than the outer radius of the flywheel rotor. The hub is suspended from a motor-generator by a flexible shaft or rigid shaft with flexible joint, the flywheel rotor having a mass, substantially all of the mass of the flywheel rotor comprising fibers, the fibers in large part movable relative to each other. The motor-generator is suspended from a damped gimbal, and the flywheel rotor and motor-generator are within a chamber evacuatable to vacuum. An electrostatic motor/generator can also be within the same vacuum as the flywheel.

Abstract: An orthotic device comprises a flexible support structure comprising at least one surface for contacting a body part of a user, a plurality of pressure sensors configured for coupling to a microcontroller, and a plurality of displacement regions. Each region defines a portion of said flexible support structure, wherein each portion includes at least one sensor disposed on or below the at least one surface and at least one electrically deformable unit. Each unit comprises at least one electroactive material and is configured for coupling to the microcontroller and to a power source. The device is dynamically adjustable to change its shape and support properties, when an electrical voltage is applied to the electroactive material under the control of a microcontroller.

Abstract: An actuator is provided with a conductive polymer film portion, an electrode, and an electrolyte portion, and by detecting a waveform of a current that flows upon application of a voltage between the conductive polymer film portion and the electrode, a displacement amount of the actuator is detected so that based on the displacement amount thus detected, a voltage is applied to the conductive polymer film portion so that the displacement amount of the actuator is adjusted.

Abstract: A driving device includes an electro-mechanical transducer having first and second end portions opposite to each other in an expansion/contraction direction, a stationary member coupled to the first end portion of the electro-mechanical transducer, a vibration friction portion mounted to the second end portion of the electro-mechanical transducer, and a moving portion frictionally coupled to the vibration friction portion, whereby moving the moving portion in the expansion/contraction direction of the electro-mechanical transducer. The moving portion is driven by equalizing a constant expanding speed of the electro-mechanical transducer with a constant contracting speed of the electro-mechanical transducer and by setting a constant rest time interval after one of contraction of the electro-mechanical transducer and expansion of the electro-mechanical transducer.

Abstract: Methods, systems, and apparatus, for drop ejection, specifically, for driving drop ejectors using n-type double-diffused metal oxide semiconductor (NDMOS) transistors with sputtered piezoelectric transducers. In general, in one aspect, an apparatus includes a n-type double-diffused metal oxide semiconductor transistor. The apparatus also includes a piezoelectric transducer. A first surface of the piezoelectric transducer is coupled to the n-type double-diffused metal oxide semiconductor transistor. The apparatus also includes a first waveform generator configured to generate an ejector waveform to apply to a second surface of the piezoelectric transducer. The ejector waveform includes at least a positive pulse and a negative pulse. The apparatus also includes a second waveform generator configured to generate a control waveform to apply to the n-type double-diffused metal oxide semiconductor transistor to selectively actuate the piezoelectric transducer.

Abstract: An inertial driving actuator includes a fixing member, a moving element that is fixed to the fixing member and generates a small displacement by extension and contraction, an oscillation substrate that is fixed to the moving element and is moved linearly reciprocally by the small displacement, and a moving body that is moved by reciprocal movement of the oscillation substrate. The moving body has a first electrode. The oscillation substrate has a second electrode, the area of the facing portion of the second electrode and the first electrode changing continuously as the moving body moves. The actuator further includes a frictional force controller that controls a frictional force generated between the oscillation substrate and moving body, and a position detector that detects the position of the moving body on the basis of the electrostatic capacitance of the facing portion of the first electrode and the second electrode.

Abstract: A driver for a piezoelectric actuator includes a pulse width modulator and an output amplifier packaged as a single semiconductor device, preferably on a single semiconductor die. The driver includes a first boost converter that supplies power to the output amplifier, which preferably has programmable gain. A second amplifier, for driving the gate of a switching transistor in the first boost converter, is powered by a second boost converter. The piezoelectric actuator provides tactile feedback for the keyboard or the display in a battery operated electronic device.

Abstract: A torsional MEMS device is disclosed. The torsional MEMS device includes a support structure, a platform, and at least two hinges, which connects the platform to the support structure. The platform has an active area and a non-active area. A plurality of sacrificial elements is disposed in the non-active area. If the resonant frequency of the torsional MEMS device is less than a predetermined standard resonant frequency of the torsional MEMS device, at least one sacrificial element is removed to reduce the total mass of the torsional MEMS device, and so as to increase the resonant frequency of the torsional MEMS device.

Abstract: A method, computer readable medium, and system for controlling velocity of an at least partially resonant actuator system in accordance with embodiments of the present invention includes determining with an actuator controller computing device a sequence of full bridge and half bridge outputs to control an output velocity of an at least partially resonant actuator device. The actuator controller computing device controls a driver system to output a driving signal based on the determined sequence of full bridge and half bridge outputs. The driver system provides the driving signal to the at least one at least partially resonant actuator device.

Abstract: A method, computer readable medium, and a system for reducing power consumption of an at least partially resonant actuator system includes adjusting a driving system with an actuator controller computing device configured to provide a driving signal including a delay interval during a transition in the driving signal. The driving system provides the driving signal with the delay interval to an at least one partially resonant actuator device.

Abstract: An ultrasonic motor device includes: an ultrasonic motor that moves an object; a detecting unit that detects movement of the object; and a control unit that drives the ultrasonic motor according to a first driving signal before detection of the movement of the object, and drives the ultrasonic motor according to a second driving signal, which is different from the first driving signal, after detection of the movement of the object.

Abstract: The present invention relates to a single-stage zero-current switching driving circuit for ultrasonic motor, which comprises: a buck-boost converter and a zero-current switching resonant inverter. The driving circuit according to the present invention integrates the buck-boost converter and the resonant inverter into a single-stage structure, so that the buck-boost converter and the resonant inverter share an active switch and a trigger signal, and therefore, the circuit is simplified and the loss caused by stage switching is reduced. Moreover, the buck-boost converter operates in a discontinuous-conduction mode (DCM), which allows the circuit to have high power factor, and enables the active switch to be capable of zero-current switching (ZCS), so that the loss caused by switching is largely reduced. In the driving circuit according to the present invention, there's no interaction of power between the buck-boost converter and the resonant inverter, so that the two circuits can be analyzed individually.

Abstract: Provided is a driving device having an electromechanical transducer, a driving member, a moving member and a driving circuit. The driving circuit outputs a driving voltage at a frequency lower than that where the driving speed of the moving member is at maximum, and changes the drive frequency of the driving voltage so that the drive frequency has a negative correlative relationship with the ambient ten aperature. The change rate of the drive frequency to a change of the ambient temperature in the negative correlative relationship is larger than a change rate of a frequency where the driving speed of the moving member is at maximum to an increase of the ambient temperature, and the change rate permits the driving speed of the moving member to increase when the ambient temperature increases.

Abstract: A vibration-type motor controller controls a driving speed of a vibration-type motor relatively moving a vibrating body in which a vibration is excited by an electromechanical energy conversion element 20 to which a first frequency signal and a second frequency signal having a phase difference are applied, and a contacting body which contacts the vibrating body. The vibration-type motor controller includes a speed controller 1 configured to alternately switch a frequency control which changes frequencies of the first and second frequency signals while fixing the phase difference and a phase difference control which changes the phase difference while fixing the frequency so that at least one of a plurality of frequency controls or a plurality of phase difference controls are included to increase and decrease the driving speed of the vibration-type motor.

Abstract: An ultrasonic motor in which driving signals of two phases are applied to a vibrator having a driving member in contact with a driven member to simultaneously generate a longitudinal vibration and a flexural vibration, thereby generating an elliptic vibration in the vibrator, and the driving member frictionally drives the driven member upon obtaining a driving force from the elliptic vibration, is configured as follows. Namely, the ultrasonic motor includes a driving phase difference switching unit which switches a driving phase difference serving as a phase difference between the driving signals of the two phases, and changes a switching cycle of the driving phase difference.

Abstract: A method, computer readable medium, and system for controlling velocity of at least partially resonant actuator system includes obtaining at an actuator controller computing system a selected operating velocity within an operational velocity range for at least one of one or more at least partially resonant actuator devices. A width of one or more pulses of a driving signal for the at least one of one or more at least partially resonant actuator devices is adjusted with the actuator controller computing system based on the selected operating velocity. The driving signal with the adjusted width of the one or more pulses is provided with the actuator controller computing system to obtain the selected operating velocity at the at least one of the one or more at least partially resonant actuator devices.

Abstract: An apparatus, system and method for controlling drive patterns is disclosed. A digital engine for controlling drive patterns may include a profile controller to program characteristics of one or more drive patterns for one or more piezoelectric actuators. The digital engine may further include a register array to store profile information for the one or more drive patterns. Each drive pattern may comprise a plurality of pulses with each pulse having a slope. The digital engine may also include a digital pattern generator to generate the one or more drive patterns based upon the profile information stored in the register array. The digital engine may further include a slope shaping circuit to modify one or more signals based upon an input from the digital pattern generator.

Abstract: An ultrasonic motor driving method, which drives the piezoelectric elements into two-two or three-three groups; within two-two group, one of the output terminals of the first and second piezoelectric elements are connected to the first and third nodes respectively, and the other terminals of the first and second piezoelectric elements are both connected to the second node which is the common ground terminal, the adjacent piezoelectric elements in one two-two group are polarized in sequence of “++??”. Within three-three group, one of the output terminals of the first to third piezoelectric elements are connected to the first to third nodes respectively, and the other terminals of the first to third piezoelectric elements are all connected to the fourth node which is the common ground terminal, all piezoelectric elements are polarized in forward direction.

Abstract: A method for driving an ultrasonic motor having an actuator section includes: a step of starting the ultrasonic motor by applying an AC voltage with a first frequency to the actuator section; a voltage detection step of detecting a voltage generated at the actuator section while lowering a driving frequency from the first frequency to a second frequency at which the ultrasonic motor stops; a starting step of starting the ultrasonic motor with a third frequency; and a driving step of changing the driving frequency from the third frequency to a lower frequency such that the driving frequency has a value within an operation frequency range, wherein the operation frequency range is within a range on a higher frequency side than the driving frequency at which a maximum voltage is detected in the voltage detection step.

Abstract: Abnormal noise generated while driving a piezoelectric actuator is prevented. A pulse-generation circuit is capable of selectively generating a displacement pulse and a stationary pulse as a drive pulse for application to a piezoelectric element, the displacement pulse having a duty ratio for causing a lens to be displaced by a predetermined step width, and the stationary pulse having a duty ratio for causing the lens to remain stationary in a current position. The pulse-generation circuit controls the production of the drive pulse continuously for a plurality of times within the servo control cycle, causes the displacement pulse to be produced when the remainder of a required amount of displacement is equal to or greater than a threshold value, and causes the stationary pulse to be continuously produced until the initiation of the next servo control cycle when the remainder is less than the threshold value.