Abstract: A flexural wave absorption system includes a base member connected to a beam that may be subject to flexural waves, an arm member, connected to the base, disposed substantially in parallel alignment with the beam, a mass member connected to a distal end of the arm member, a piezoelectric patch, connected to the arm member, that generates electricity in response to a flexural wave propagating through the beam, and a shunting circuit, connected to the piezoelectric patch, that dissipates electricity generated by the piezoelectric patch to absorb the flexural wave.

Abstract: A multi-layer piezoelectric ceramic component includes: a piezoelectric ceramic body having a cuboid shape, having upper and lower surfaces facing in a thickness direction, first and second end surfaces facing in a length direction, and a pair of side surfaces facing in a width direction, and including first and second regions; first internal electrodes in the first region; second internal electrodes in the second region; third internal electrodes in the first and second regions; a first terminal electrode formed on the first end surface and electrically connected to the first internal electrodes; a second terminal electrode formed on the first end surface and electrically connected to the second internal electrodes; a third terminal electrode formed on the second end surface and electrically connected to the third internal electrodes; a first surface electrode formed on the upper surface; and a second surface electrode formed on the lower surface.

Abstract: Disclosed herein are monitoring systems and sensors for physiological measurements. The sensors can be multi-element piezo sensors capable of generating multiple electrical signals, whereby the monitoring systems can receive the multiple electrical signals to analyze the user's vital signs along multiple regions of the user's body. In some examples, the piezo sensor can include one or more corrugations, such as peaks and valleys, to create localized regions with increased mechanical response to force. The sensitivity and resolution of the piezo sensor can be enhanced by further locating electrode sections at the corrugations, where the electrode sections can be electrically isolated and independently operable from other electrode sections. Traces electrically connecting an electrode section to, e.g.

Abstract: Disclosed is a piezoelectric washer intended for an accelerometer sensor having a ceramic body and a conductive electrode on each of two opposing faces, an electrical resistance being to be established between the two conductive electrodes. The ceramic body has, on its outer contour, a resistive path connecting the conductive electrodes to one another with a predetermined length and cross-section of the resistive path according to the resistance to be established between the two conductive electrodes.

Abstract: An inkjet printing head 1 includes an actuator substrate 2 having pressure chambers (cavities) 7, a movable film formation layer 10 including movable films 10A disposed above the pressure chambers 7 and defining top surface portions of the pressure chambers 7, and piezoelectric elements 9 formed above the movable films 10A. Each piezoelectric element 9 includes a lower electrode 11 formed above a movable film 10A, a piezoelectric film 12 formed above the lower electrode 11, and an upper electrode 13 formed above the piezoelectric film 12. The piezoelectric film 12 includes an active portion 12A with an upper surface in contact with a lower surface of an upper electrode 13 and an inactive portion 12B led out in a direction along a front surface of the movable film formation layer 10 from an entire periphery of a side portion of the active portion 12A and having a thickness thinner than that of the active portion 12A.

Abstract: A helical dielectric elastomer actuator (HDEA) can include a first dielectric region comprising an elastomer defining a helix. In an example, a dielectric material can be deposited and a compliant conductive material can be deposited, such as using an additive manufacturing approach, to provide an HDEA. In an example where the HDEA has multiple mechanical degrees of freedom, at least two compliant conductive regions can be located on a first surface of the first dielectric region and at least one compliant conductive region can be located on an opposite second surface of the first dielectric region. For such an example, the at least two compliant conductive regions can be arranged to be energized with respect to the at least one compliant conductive region in a manner providing at least two mechanical degrees of freedom for operation of the HDEA.

Abstract: An oscillator (4) for warping to oscillate due to expansion and contraction of a piezoelectric layer, having a tabular shape and including a substrate and the piezoelectric layer layered on the substrate. A casing (2) has an internal space (2C) accommodating the oscillator (4) and a fixing section (2D) fixing the circumferential edge of the oscillator (4). The casing (2) is conductive of oscillations transmitted from the oscillator (4) via the fixing section (2D) to the outside. A signal input unit (3) receives an audio voltage signal input from a smartphone and applies the signal to the piezoelectric layer. The oscillator (4) has a main surface (4A) having an entire width W1 longer than the entire width of the fixing section (2D) in a direction orthogonal to a direction from the fixing section (2D) to the center of the oscillator (4).

Abstract: The present invention is a novel electroactive actuator device provides high active and passive performances for electromechanical and smart systems. The electroactive actuator device is capable of operating in a manner that achieve good passive isolation characteristics, amplifies the stroke displacement per applied voltage, and also enhances the active forces of the electroactive mechanism without weight or size penalties. The electromechanical responses can be transferred to the objective systems using lightweight electrical-mechanical connectors fastened at the center of the piezoelectric actuator elements. When an alternating voltage potential is across the upper and lower electrodes of a piezoelectric actuator element, the center portions of all the piezoelectric actuator elements, as well as the electrical-mechanical connectors attached thereto, reciprocate harmoniously in one direction generating high electroactive forces and dynamic responses.

Abstract: The purpose of the present invention is to realize a flexible display device with a touch sensor that flexibility is maintained in a normal operation as a display; however, rigidity is added to the display device when the touch sensor is used. The representative structure of the invention is, a display device comprising: a touch sensor and a display panel, wherein a laminated body of a first actuator and a second actuator is adhered to the rear surface of the display panel, the first actuator itself can bend when voltage is applied, the second actuator itself can bend when voltage is applied.

Abstract: Described herein is the use of large phase transformational strain in relaxor ferroelectric single crystals for broadband sound generation. The technique exploits the thermo-optical triggering and thus an opto-acoustic effect of ferroelectric phase transformation piezocrystals under mechanical bias conditions.

Abstract: Actuator assemblies, mechanical assemblies including the actuator assemblies, and methods of fabricating the same are disclosed herein. The actuator assemblies include a piezoelectric element having a first side and a second side, a first electrode in electrical communication with the first side, and a second electrode in electrical communication with the second side. The first electrode includes a flexible, electrically conductive membrane. The mechanical assemblies include a first structure, which includes a first interface surface, a second structure, which includes a second interface surface, and the actuator assembly. The actuator assembly is configured to provide a motive force for relative motion between the first structure and the second structure. The methods include defining a first electrode on a first side of a piezoelectric element and defining a second electrode on a second side of the piezoelectric element. The first electrode includes a flexible, electrically conductive membrane.

Abstract: A transducer comprising: at least one piezoelectric layer; a first patterned conductive layer that is patterned with a first opening; a second patterned conductive layer that is patterned with a second opening; wherein at least one piezoelectric layer is between the first and the second patterned conductive layers in a stack; and wherein a position of the first opening is staggered relative to a position of the second opening in the stack to mitigate an occurrence of crack propagation through the layers.

Abstract: An operating characteristic of an information handling system is determined. It is determined whether a cooling configuration of a plurality of piezoelectric cooling fans included at the information handling system is providing a designated level of cooling. A cooling profile is stored at a memory device, the cooling profile including the operating characteristic and the cooling configuration.

Abstract: There is provided a DSR speaker comprising at least a central moving element, a plurality of peripheral flexure benders, each flexure bender comprising at least a pair of electrodes and at least a piezoelectric material layer, the flexure benders being connected to said moving element and being configured to move said moving element along an axis perpendicular to a moving element surface, in response to an electrical stimulus applied to said electrodes, in order to produce sound, and at least a mechanical stopper which is configured to limit the motion of said moving element. Various manufacturing methods are also described.

Abstract: To reduce the driving loss in the diaphragm, and to ensure a good sound output in the wide bandwidth. It includes a circular coil bobbin at least partly disposed between a yoke and a magnet, a coil wound around the coil bobbin, the coil being configured to be moved with the coil bobbin where a driving current is supplied to the coil, a piezoelectric element having one end coupled to one end of the coil bobbin in a movement direction, the piezoelectric element being configured to be expanded and contracted and moved in a direction same as the movement direction where an electric current is supplied to the piezoelectric element, and a diaphragm having an inner circumference part coupled to another end of the piezoelectric element, and a coupled part of the diaphragm to the piezoelectric element and a coupled part of the piezoelectric element to the coil bobbin are positioned on a straight line in the movement direction.

Abstract: An ultrasonic sensor assembly includes a flexible supporting material that has flexibility configured for allowing bending of the supporting material to conform to a cylindrical shape of a pipe. The assembly includes a plurality of operable sensor elements arranged in a matrix formation upon the flexible supporting material. The matrix formation includes a plurality of rows of the sensor elements and a plurality of columns of the sensor elements. The flexible supporting material is configured for placement of the columns of the matrix formation to extend along the elongation of the pipe and the flexible supporting material is configured for placement of the rows of the matrix formation to extend transverse to the elongation of the pipe. The flexible support material is configured to flex for positioning the sensor elements within each row in a respective arc that follows a curve of the cylinder shape of the pipe.

Abstract: The invention relates to a dielectric transducer structure comprising a body of elastomeric material that is provided with an electrode arrangement on each of two boundary surfaces lying oppositely to one another. At least one boundary surface comprises a corrugated area that comprises heights and depths. The aim of the invention is to improve the compliance to elastic deformations of the dielectric transducer structure. To this end, the heights and depths are arranged in both perpendicular directions of the boundary surface.

Abstract: Provided is a multilayer actuator and a display device comprising the same with improved driving displacement that includes, for example, a plurality of electroactive layers, wherein the electroactive layers comprise a ferroelectric polymer, and polarization directions of all electroactive layers are substantially the same.

Abstract: A mobile terminal including a camera module includes a case; a camera module housing, wherein at least a portion of the housing is exposed through an opening in the case; a first lens unit disposed in the housing and having a plurality of lenses configured to focus light received through the exposed portion of the housing; a second lens unit disposed in the housing and configured to magnify an image formed by light passing through the first lens unit as a function of a distance between the first lens unit and the second lens unit; and a moving unit connected to the first lens unit and the second lens unit and configured to move at least one of the first lens unit and the second lens unit in order to adjust the distance between the first lens unit and the second lens unit.

Abstract: A vibrational energy harvester having a base and a piezoelectric transducer formed from a layer of piezoelectric material and extending between a first end at the base and a second end. At least a portion of the piezoelectric transducer is arranged in a back and forth pattern between the first and second ends. A magnetic component provides a magnetic field within which at least a portion of the piezoelectric transducer operates so that it exhibits nonlinear behavior. A biomedical implantable device using the vibration energy harvester can extract energy from heartbeat waveforms (heartbeats) to thereby power a device within the body.

Abstract: An electronic device includes at least one screen. One or more bumpers are moveable between at least a stowed position where the bumper is flush or below the screen and a deployed position where at least a portion of the bumper projects above the screen. One or more sensors detect when the electronic device is subject to one or more drop events. When a drop event is detected, the bumper moves to the deployed position, protecting the screen. In various implementations, the bumper may be moveable by a push-push mechanism or a magnet assisted actuator mechanism. In other implementations, the bumper may include piezoelectric material to which voltage can be applied to move the bumper.

Abstract: An electro-mechanical transducer element is disclosed. The electro-mechanical transducer element includes a first electrode formed on a substrate; an electro-mechanical transducer film formed on at least a part of the first electrode; and a second electrode formed on at least a part of the electro-mechanical transducer film. In at least one cross section of the electro-mechanical transducer film, a film thickness distribution shape is convex to the second electrode side.

Abstract: A transparent lens microphone comprises (a) a refractive eyeglass lens; (b) a sound sensitive coating on an outer surface of the refractive lens; and (c) electrical contacts connected to the sound sensitive coating so as to provide an electrical analog signal representative of an acoustic signal striking the outer surface of the transparent lens microphone.

Abstract: The invention relates to a heart rate measuring apparatus and a method, adapted for measuring a subject's (6) heart rate and/or heart rate variation. The heart rate measuring apparatus (1) comprises a holder (2) adapted for carrying a portion of a body part of the subject (6) lying on or resting against the holder (2), a motion sensor (4) operatively connected to the holder (2), wherein the holder (2) is adapted for being at least partly moveable in a horizontal direction relative to the ground (7), the motion sensor (4) being adapted for measuring a signal generated by a movement of the subject (6) at least partly in the horizontal direction. In this way, a reliable signal is obtained adapted for measuring the heart rate and/or heart rate variation of a subject while keeping the implementation costs low.

Abstract: An opening at a first carbon fiber sheet is provided, the opening extending through the sheet from a first major surface to a second major surface, the opening defining two sides and a first end of a rectangular flap, a second end of the flap remaining rooted in the first carbon fiber sheet. A piezoelectric transducer is bonded to the first carbon fiber sheet, the transducer proximate to the second end of the flap. A controller including a signal generator is coupled to the piezoelectric transducer, the piezoelectric transducer to excite sympathetic vibration of the flap.

Abstract: A piezoelectric fan includes a vibration plate one end of which in a length direction is supported in a fixed manner and the other end of which in the length direction is a free end; and piezoelectric elements, attached on at least one of front and back surfaces of the vibration plate. In an intermediate portion of the vibration plate in the length direction, a right-angle bent portion is provided, and a plurality of divided blades are defined by slits in an area of the vibration plate extending from the free end to a position located a predetermined distance from the bent portion toward the free end. The piezoelectric element is attached on the portion of the vibration plate between the fixed end and the bent portion. Hence, variations in resonant frequency among the blades are reduced and the blades are efficiently excited using a common piezoelectric element.

Abstract: The disclosure relates to a system for providing feedback signals to input signals provided to an electronic device is provided. The system comprises: a display; an input device; an input module to detect activation of the input device; and a input module to generate a feedback signal for the electronic device based on signals from the input module. In system, the input device is a transducer. The transducer may be a piezoelectric element and the input module may cause the transducer to vibrate upon receiving an activation signal from the input module.

Abstract: In some embodiments, circuits for ultrasonic transducer element arrays are provided. In some embodiments, a circuit described herein comprises a first layer for receiving a transducer element array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends for receiving ground electrodes of the transducer elements and second ends electrically connected to the ground.

Abstract: A piezoelectric vibration element capable of reducing occurrence of unnecessary vibration, and a piezoelectric vibration device and a portable terminal using the same are disclosed. The piezoelectric vibration element includes a plurality of electrode layers and a plurality of piezoelectric layers being stacked along a first direction, the piezoelectric vibration element having two surfaces that face each other to be at intervals in the first direction, and vibrating in bending mode in the first direction with an amplitude varying along a second direction perpendicular to the first direction according to input of an electric signal, one of the two surfaces having such a shape that a central portion thereof in a third direction perpendicular to the first direction and the second direction protrudes as compared with opposite end portions thereof in the third direction.

Abstract: There is provided a method for manufacturing a piezoelectric element, the method having a step of polarizing the fired piezoelectric body while fixing at least two positions in a direction perpendicular to the polarization direction. The method is a means for obtaining a piezoelectric element provided with a thin and flat fired piezoelectric body with no warpage.

Abstract: A throat microphone includes a cantilevered piezoelectric device 1 having a fixed end 11 supported by a base 3 and a free end with an anchor 4 fixed thereto. The piezoelectric device 1 vibrates to output audio signals in response to vibrations of a throat. The fixed end is attached to the base 3 such that the piezoelectric device 1 vibrates parallel to the surface of the base 3. A gap is defined between the anchor 4 and the base 3. The gap is provided with a vibration absorber 5.

Abstract: A transparent lens microphone comprises (a) a refractive lens; (b) a sound sensitive coating on an outer surface of the refractive lens; and (c) electrical contacts connected to the sound sensitive coating so as to provide an electrical analog signal representative of an acoustic signal striking the outer surface of the transparent lens microphone.

Abstract: Methods, systems, and apparatuses are described for cooling electronic devices. The electrical device includes an integrated circuit die (IC) having opposing first and second surfaces, a plurality of interconnects on the second surface of the IC die that enable the IC die to be coupled to a substrate, and a flexural plate wave device. The flexural plate wave device is configured to generate a stream of air to flow across the electrical device to cool the IC die during operation of the IC die.

Abstract: Provided is a vibration-type driving apparatus comprising a vibrating body including an electro-mechanical energy conversion element and an elastic body to which the electro-mechanical energy conversion element is joined; and a flexible printed board connected to the electro-mechanical energy conversion element, wherein the flexible printed board includes a first region bonded to at least the location of an antinode portion of vibration of the vibrating body and a second region that is adjacent to the first region and that is not bonded to the electro-mechanical energy conversion element; the boundary portion between the first region and the second region is located at a node portion of the vibration of the vibrating body; and a gap is present between the second region and the vibrating body.

Abstract: The present invention relates to an actuator for moving a rigid element, e.g. an optical element such as minor, the element being mechanically coupled to a frame with a bendable coupling, wherein actuator elements are mounted on said coupling between the frame and element, the coupling and actuator elements being adapted to provide a movement to the element when subject to signal from a signal generator.

Abstract: A piezoelectric multiplexer includes an actuator and multiple piezo-morph beams. The actuator includes an actuator conducting head and an actuator stem, and each piezo-morph beam includes a conducting beam contact head and a beam stem manufactured out of piezo-morph material. A control voltage is selectively applied to electrical contacts coupled to the beam stems to create a piezoelectric effect that bends the selected piezo-morph beam and creates an electrical connection between its contact head and the conducting head of the actuator. A control circuit with a controller signals which piezo-morph beam to connect to the actuator. This multi-piezo-morph-beam piezoelectric multiplexer can be affixed to the electrical terminals of different electrical components (e.g., a transistor) to create an electrical cell that can be manufactured on a semiconductor chip or in a microelectromechanical system (MEMS) device.

Abstract: An actuator includes a multi-layer part having a multilayered piezoelectric part comprising a plurality of piezoelectric bodies and an electrode part connected to the multilayered piezoelectric part, and a support part displaceably supporting the multi-layer part. The multilayered piezoelectric part is polled in the same direction. One of the piezoelectric bodies expands or contracts in an opposite direction to another piezoelectric body.

Abstract: Described herein are transducers and their fabrication. The transducers convert between mechanical and electrical energy. Some transducers of the present invention include a pre-strained polymer. The pre-strain improves the conversion between electrical and mechanical energy. The present invention provides methods for fabricating electromechanical devices including one or more electroactive polymers.

Abstract: A piezoelectric actuator includes a stacked body composed of internal electrodes and piezoelectric layers which are stacked on each other; and a surface electrode disposed on at least one of main surfaces of the stacked body so as to be electrically connected to the internal electrodes. The internal electrodes each includes a first electrode and a second electrode. The stacked body has an active section in which the first electrodes and the second electrodes of the internal electrodes are arranged so as to overlap each other in a stacking direction thereof, and an inactive section which is every section of the stacked body other than the active section. An internal electrode placed on a one-main-surface side of the internal electrodes is configured so that its end part situated near a boundary between the active section and the inactive section is curved toward the other main surface.

Abstract: A piezo valve is actuated by way of at least one actuator which is formed by a piezoelectric bender transducer (12) having two piezo actuators (14, 16). An actuating method has the steps of generating an actuator control signal (out), which can be output at either one of the two piezo actuators (14, 16), depending on at least one actuating control signal (in), of detecting an electric measurement quantity at one of the piezo actuators (14, 16) which is currently not controlled (16), and of generating a vibration damping signal (fb) on the basis of the detected measurement quantity and use thereof for active vibration damping for the currently controlled piezo actuator (14).

Abstract: An energy harvesting device capable of harvesting multiple forms of energy. The device includes a base, a piezoelectric cantilever, and a carbon nanotube film. The piezoelectric cantilever includes a piezoelectric layer disposed between a top electrode and a bottom electrode. A proximate end of the piezoelectric cantilever is supported by the base. The base does not support a distal end of the piezoelectric cantilever. The piezoelectric cantilever is capable of converting vibration energy into electrical power. The carbon nanotube film is capable of absorbing electromagnetic radiation and thermal radiation, and thereafter transmitting heat to the piezoelectric layer. The piezoelectric layer is mechanically deformed in response to said heating, thereby generating electrical power.

Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.

Abstract: Inertial sensor having a body with first and second cavities on opposite sides thereof, a sensing element in the first cavity, electronic circuitry in the second cavity, electrical conductors interconnecting the sensing element and the circuitry, and leads connected electrically to the circuitry and extending from the body for mounting the sensor and making connections with the circuitry.

Abstract: A piezoelectric drive element includes piezoelectric layers, electrode layers between the piezoelectric layers, and electrode layers as the surfaces of the laminated layers. The piezoelectric layers are arranged on the upper side and on the lower side with reference to the center in the thickness direction, and are polarized in opposite directions. The thicknesses of piezoelectric layers at the center which have the least displacement are the thickest. The thicknesses of the piezoelectric layers above and under the thickest piezoelectric layers decrease gradually in an outward direction. A piezoelectric sound-generating body is constructed by affixing the piezoelectric driving element to a support plate and supporting the piezoelectric driving element with a frame.

Abstract: A piezoelectric multiplexer includes an actuator and multiple bimorph beams. The actuator includes an actuator conducting head and an actuator stem, and each bimorph beam includes a conducting beam contact head and a beam stem manufactured out of bimorph material. A control voltage is selectively applied to electrical contacts coupled to the beam stems to create a piezoelectric effect that bends the selected bimorph beam and creates an electrical connection between its contact head and the conducting head of the actuator. A control circuit with a controller signals which bimorph beam to connect to the actuator. This multi-bimorph-beam piezoelectric multiplexer can be affixed to the electrical terminals of different electrical components (e.g., a transistor) to create an electrical cell that can be manufactured on a semiconductor chip or in a microelectromechanical system (MEMS) device.

Abstract: A reconfigurable bi-stable device includes an elastically deformable panel laterally disposed between and connected to one or more mounting members directly or indirectly connected to opposing ends of the panel, with the panel maintained under compressive force along at least one vector extending between the opposing ends. The compressive force deforms the panel into a one of two stable deformed positions, with the device disposed such that the panel may be moved between each of the two stable deformed positions by application of manual force to one of two opposing faces of the panel. A first shape memory alloy (SMA) or piezo actuator member is connected to the panel, the actuator member being capable of moving the panel from a first one of the two stable deformed positions to a second one of the two stable deformed positions.

Abstract: The present invention relates to a piezoelectric bimorph switch, specifically a cantilever (single clamped beam) switch, which can be actively opened and closed. Piezoelectric bimorph switch are known from the prior art. Such a switch may be regarded as an actuator. Actuators are regarded as a subdivision of transducers. They are devices, which transform an input signal (mainly an electrical signal) into motion. Electrical motors, pneumatic actuators, hydraulic pistons, relays, comb drive, piezoelectric actuators, thermal bimorphs, Digital Micromirror Devices and electroactive polymers are some examples of such actuators. The switch of the invention comprises piezoelectric stack layers (121, 122), which form a symmetrical stack, wherein an electric field is always applied in the same direction as the poling direction of the piezoelectric layers.

Abstract: The present invention provides a sensor system for measuring an elastic modulus and a shear modulus and a method for using the sensor system to evaluate a tissue by determining the presence of and/or characterizing abnormal growths. The method involves applying a set of forces of different magnitudes to one or more locations of tissue, detecting the corresponding displacements due to said applied forces, determining the forces acting on those locations of tissue which are a combination of forces from the applied voltages and the countering forces from tissue deformation, obtaining the elastic modulus and/or shear modulus for a plurality of locations, and determining abnormal growth invasiveness, malignancy or the presence of a tumor from said elastic and/or shear moduli.

Abstract: A synthetic jet apparatus including a series of generally parallel spaced-apart bimorph piezoelectric plates defining first and second sets of fluid chambers. The chambers of the second set of fluid chambers are interleaved with the chambers of the first set of fluid chambers. The first and second sets of fluid chambers are in fluid communication with sources of first and second fluids, respectively, the source of the first fluid being separate from the source of the second fluid. The bimorph plates are operable to alternately draw the first fluid from its source into the first set of fluid chambers while expelling the second fluid from the second set of fluid chambers, and then expel the first fluid from the first set of fluid chambers back into its source while drawing the second fluid from its source into the second set of fluid chambers.

Abstract: In an optical deflector including a mirror, a movable frame supporting the mirror, a support body surrounding the movable frame, and a first group of piezoelectric actuators and a second group of piezoelectric actuators alternating with the first group of piezoelectric actuators, a driver combines first and second original saw-tooth waves having the same waveform into first saw-tooth waves, and applies a first drive voltage having the first saw-tooth waves to the first group of piezoelectric actuators. The driver applies a second drive voltage having second saw-tooth waves opposite in phase with the first saw-tooth waves to the second group of piezoelectric actuators.