Showing papers on "Piezoelectric motor published in 2004"

Micro Piezoelectric Ultrasonic Motors

Abstract: This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced; windmill, PZT tube, metal tube, and shear-type motors. Driving principles and motor characteristics are described in comparison with the conventional ultrasonic motors. Motors with 1.5 mm in diameter and 0.8 mN⋅m in torque have been actually developed.

Development of a new standing wave type ultrasonic linear motor

Abstract: We developed a new standing wave type ultrasonic linear motor. The composite stator consists of a metallic plate and two piezoceramic plates bonded to the metallic plate with a spatial phase difference of a half wavelength. The operation principle of the motor was presented with theoretical equations and the feasibility was verified using the finite element method. Experimental fabrication and characterization of a sample motor was performed to confirm the validity of the new structure and the numerical results. The new motor offers identical performance in both forward and backward motions, while maintaining a simple structure and all the characteristic features of an ultrasonic linear motor.

Nonlinear dynamic characteristics of piezoelectric bending actuators under strong applied electric field

Abstract: Dynamic characteristics of piezoelectric bending actuators under low and high electric fields are studied using the asymptotic theory of nonstationary vibrations. The proposed nonlinear model predicts the changes in fundamental resonant frequencies of the piezoelectric cantilever. The predicted resonance amplitude of the tip deflections of the piezoelectric actuators, which increases with the increase in the magnitude of the electric field, well agrees with the experimental results. Additionally, the decrease in the mechanical quality factor with the increase in the electric field, the tip deflection of piezoelectric actuators near resonance frequency,and the amplitude of the tip deflection at the fundamental vibration tone under an applied electric field varying with time have also been obtained using the present model.

Nonlinear static characteristics of piezoelectric bending actuators under strong applied electric field

Abstract: Static behaviors of piezoelectric cantilever actuator under large electric field have been studied and a nonlinear relationship between the tip deflection or blocking force and the strong applied electric field is proposed. It has been shown that as the magnitude of the electric field increases, the tip deflection or blocking force rapidly increases and the difference between experimental results and linear predictions becomes large. However, the nonlinear predictions based on the present model well agrees with the experimental results within a wide range of applied electric field. The results of the analysis are believed to be useful for materials selection and actuator structure design of actuator in actuator fabrication.

Piezoelectric cantilever pressure sensor

Abstract: A piezoelectric cantilever pressure sensor has a substrate and a piezoelectric cantilever having a base portion attached to the substrate and a beam portion suspended over a cavity. The piezoelectric cantilever contains a piezoelectric layer sandwiched between two electrodes and generates a measurable voltage when deformed under pressure. The piezoelectric cantilever pressure sensor can be manufactured at low cost and used in various applications including fingerprint identification devices.

On the Nonlinear Behavior of Piezoelectric Actuators

Abstract: In this paper we present a theoretical and experimental study of the nonlinear behavior of piezoelectric actuators. The nonlinearities are introduced as quadratic terms in the piezoelectric constitutive relations. These relations are employed, together with supporting experimental results, to establish an engineering description of the nonlinearities present in piezoelectric materials. We present a lumped-parameter representation of a system consisting of a piezoactuator driving a mass. The representation is valid in the vicinity of the primary resonance. The resulting nonlinear differential equation of motion is analyzed by the method of harmonic balance to study the effects of nonlinearities on the dynamics of forced vibrations. Experimental measurements of the steady-state mechanical response to harmonic electrical excitation over a range of excitation frequencies and amplitudes quantify the nature and level of nonlinear behavior. The nonlinear behavior, which is mainly evident around the resonant freq...

Piezoelectric actuator having minimal displacement drift with temperature and high durability

Abstract: A piezoelectric bending actuator that is insensitive to temperature changes. The actuator includes a pair of piezoelectric layers. One of the layers bends in response to an applied voltage and the other piezoelectric layer flattens in response to an applied voltage. The piezoelectric layers are mounted adjacent to each other. The piezoelectric layers move opposite to each other in response to a change in temperature such that the piezoelectric bending actuator is stable over a range of temperatures. The piezoelectric layers are held in compression between a ring and a retainer. Compressing the piezoelectric layers allows the bending actuator to have a high stroke with improved durability because the discs are kept in compression.

Piezoelectric generators and methods of operating same

Abstract: A piezoelectric power generator (20, 120) comprises plural piezoelectric devices (22, 122); an actuator (24) positioned to impart an excitation to the plural piezoelectric devices (22, 122) in a predefined sequence; and, an electrical conduction system (30) connected to the plural piezoelectric devices for conducting an electrical charge created by the excitation. Preferably the plural piezoelectric devices (22, 122) are arranged in a predetermined relationship relative to the actuator (24) whereby only one of the plural piezoelectric devices (22, 122) is actuated at a time. For example, the plural piezoelectric devices (22, 122) can be arranged in an angular pattern (such as a circular 10 pattern) relative to the actuator (24). Preferably, a rotational speed of the actuator (24) permits an excitation response for a given plural piezoelectric device (22, 122) to essentially fully decay before the given plural piezoelectric device (22, 122) is again excited.

Analytical modeling for the design of a piezoelectric rotating-mode motor

Abstract: This paper deals with the analytical modeling of a rotating-mode motor. The modeling, based on an equivalent electric circuit, is established by using geometrical and electromechanical parameters for the different parts of the motor. It gives electromechanical characteristics and other useful values for motor design. Numerical simulations and measurements from a real transducer validate the analysis.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives

Abstract: A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d/sub 31/ piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 /spl mu/m and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

Tuning-fork-type piezoelectric vibrating reed and tuning-fork-type piezoelectric vibrator

Abstract: A tuning-fork-type piezoelectric resonator element and a tuning-fork-type piezoelectric resonator are provided. The tuning-fork-type piezoelectric resonator element comprises a piezoelectric resonator element body including base and resonating arms extending from one end of base. A support includes a short side connected to the base and a long side extending from one end of the short side along a longitudinal direction of the piezoelectric resonator element body. A mount is provided at the tip of the long side and at the short side.

Coupled-field analysis of piezoelectric beam actuator using FEM

Abstract: This paper aims to present an efficient method to simulate and analyze the structural and electrical chrematistics of piezoelectric beam actuators at the same time. A silicon-based clamp-free beam mounted with a PZT layer on both sides is used for analysis. The couple-field analysis is important for MEMS and the use of FEM to achieve the accurate results and time saving is the trend at this moment. In this study, the harmonic response, resonant frequency of the piezoelectric plate, and the equivalent piezoelectric circuit of the piezoelectric transducer are investigated in this study. The simulated results are compared to the experimental and theoretic values as well.

Ultrasonic probe and ultrasonic diagnosing device

Abstract: A ultrasonic probe formed by arranging a plurality of ultrasonic vibrators each including a piezoelectric layer (2) and a pair of electrodes (7-1, 7-2) provided to sandwich this piezoelectric layer, the piezoelectric layer (2) consisting of a first piezoelectric layer (2-1) disposed on the ultrasonic wave outputting side across a common electrode (8) and a second piezoelectric layer (2-2) disposed on the opposite side, each ultrasonic vibrator having a uniform low-frequency response distribution in a minor-axis direction perpendicular to the arranging direction of the ultrasonic vibrators and having a high high-frequency response distribution at the center in the minor-axis direction, characterized in that the characteristics of the minor-axis-direction frequency and sound pressure of the first piezoelectric layer are complemented by those of the second piezoelectric layer to thereby make uniform frequency characteristics for a minor-axis-direction low frequency.

Vibration control of piezoelectric beam-type plates with geometrically nonlinear deformation

Abstract: This paper presents a wavelet-based approach of deformation identification and vibration control of beam-type plates with geometrically nonlinear deflection using piezoelectric sensors and actuators. The identification is performed by transferring the nonlinear equations of identifying deflection into a system of solvable nonlinear algebraic equations in terms of the measurable electric charges and currents on piezoelectric sensors. After that, a control law of negative feedback of the identified signals of deflection and velocity is employed, and the weighted residual method is chosen to determine control voltages applied on the piezoelectric actuators. Due to that the scaling function transform is like a low-pass filter which can automatically filter out high-order signals of vibration or disturbance from the measurement and the controller employed here, this control approach does not lead to the undesired phenomenon of control instability which is generated by the spilling over of high-order signals. Finally, some numerical simulations are carried out to show the efficiency of the proposed approach.

High-Speed Thin Ultrasonic Spindle Motor and Its Application

Abstract: In this paper, we report an ultrasonic motor capable of high-velocity revolution applicable for long continuous high operation as a microfan. This study is a response to the new challenge of developing a new field of applications for an ultrasonic motor. Ultrasonic motors using a longitudinal-flexural coupling-vibration mode of a thin plate with a vibrating piece or step-horn are considered. A stator vibrator consists of a metal plate sandwiched by two thin unipoled piezoelectric ceramic plates, the electrodes of which are not divided, and this ultrasonic motor can be driven by a single ac source. Not only the coupling between a longitudinal vibration and flexural one but also the transformation of a longitudinal vibration velocity by a vibrating piece λ/4 long and step-horn λ/2 long are used. They will be effective at making the rotary speed fast. As a result, an ultrasonic motor 0.55 mm thick rotated a shaft 1.5 mm in diameter over 8,000 rpm under conditions of an applied voltage of 30 Vp-p and an input power of only 0.16 W.

Piezoelectric motors and methods for the production and operation thereof

Abstract: The invention relates to a piezoelectric motor comprising a piezoelectric component that is connected to a resonator and a two-dimensional resonator that interacts with a movable. element, the resonator having principal surfaces that are parallel to each other and that are also identical in shape and size. The invention further relates to methods for producing such piezoelectric motors, wherein the resonators are manufactured by cutting a profiled, extruded bar into lengths or by cutting, preferably by punching, from sheet metal having constant thickness. Finally, this invention relates to a method for exciting such a piezoelectric motor, wherein the excitation frequency or frequencies is/are generated by the control electronics as a function of time in response to the respective peak current and/or in response to the respective phase minimum between current and voltage and/or in response to the change in phase.

Piezoelectric actuator module, motor module and apparatus

Abstract: To provide a highly versatile piezoelectric actuator module that can be made thinner and is easy to handle. A piezoelectric actuator module I0 includes a piezoelectric actuator main body 21 having electrodes, a plurality of signal input terminals 18 A to 18 D whereby a drive signal is inputted from the exterior and supplied to the electrodes, a rotating body 22 that is disposed in substantially the same plane as the piezoelectric actuator main body 21 and is driven and rotatably moved by the piezoelectric actuator main body 21, a casing 15 for accommodating the piezoelectric actuator main body electrically connected to the rotating body 22 and the signal input terminals, and an output shaft 12 which is exposed from the casing 15 and by which the rotational movement transmitted directly or indirectly by the rotating body 22 is outputted to the exterior.

Piezoelectric motor and method of exciting an ultrasonic traveling wave to drive the motor

Abstract: A rotary ultrasonic piezoelectric motor is provided and a method of exciting a flexure traveling wave to drive the motor. The motor includes a stator having a piezoelectric ceramic disc polarized in the radial direction and bounded by a top electrode and a segmented bottom electrode. The motor also includes a power source for applying two pairs of alternating voltages to the bottom electrode segments to excite a shear-shear mode vibration in the stator, resulting in a shear-shear mode flexure traveling wave in the stator. The motor further includes a rotor operatively connected to the stator, and the stator is driven to rotate through a frictional force between the rotor and the stator due to the traveling wave deformation of the stator. A linear ultrasonic piezoelectric motor and method of exciting a flexure traveling wave to linearly drive the motor is provided. The motor includes a stator having a rectangular piezoelectric ceramic plate that is polarized in the longitudinal direction. The motor also includes a power source for applying two pairs of alternating voltages to the bottom electrode segments to excite a shear-shear mode vibration in the stator, resulting in a shear-shear mode flexure traveling wave in the stator. The motor further includes a slider operatively connected to the stator, and the stator is driven to move linearly through a frictional force between the slider and the stator due to the traveling wave deformation of the stator.

A cylindrical micro ultrasonic motor using a micro-machined bulk piezoelectric transducer

Abstract: A micro ultrasonic motor using a micro-machined bulk piezoelectric transducer is introduced. A cylindrically shaped bulk piezoelectric transducer, with diameter 0.8 mm and height 2.2 mm, was developed as the stator transducer for a traveling wave type ultrasonic motor. We have fabricated a cylindrical micro ultrasonic motor, with diameter of 2.0 mm and height of 5.9 mm, using the stator transducer. We have also evaluated some characteristics and succeeded in driving the micro ultrasonic motor.

Optimization of the performance of the sandwich piezoelectric ultrasonic transducer

Abstract: The resonance and antiresonance frequency, the effective electromechanical coupling coefficient, and the mechanical quality factor of a sandwich piezoelectric ultrasonic transducer are studied and optimized. The effect of the thickness of thick piezoelectric element electrodes on the transducer performance is analyzed. The effect of the length and position of the piezoelectric elements in the transducer is also studied. It is shown that, although using thick electrodes is beneficial for releasing heat produced by the piezoelectric elements, the effective electromechanical coupling coefficient and the mechanical quality factor are reduced. The length and the position of the piezoelectric elements affect the performances of the transducer. Increasing the length of the piezoelectric elements decreases the mechanical quality factor, but the effective electromechanical coupling coefficient increases. When the length reaches a certain value, the effective electromechanical coupling coefficient reaches a maximum value. When the piezoelectric elements are located at the geometrical center or the displacement node, the effective electromechanical coupling coefficient and the mechanical quality factor are maximized.

Piezoelectric power generation mechanism

Abstract: PROBLEM TO BE SOLVED: To obtain a piezoelectric power generation mechanism generating power with high efficiency for an external driving force by reducing mechanical energy loss between members. SOLUTION: The piezoelectric power generation mechanism comprises a piezoelectric power generation element 1 including a piezoelectric element 1a and a supporting plate 1b bonded with the piezoelectric element 1a, a permanent magnet 2 bonded to the free end 1c of the supporting plate 1b, a movable piece 3 having a ferromagnetic body for attracting the permanent magnet 2 magnetically, and an operating member 4 fixed with the movable piece 3 and being operated externally. When an operating load is applied to the operating member 4, the supporting plate 1b is displaced through magnetic attraction between the permanent magnet 2 and the movable piece 3. When a recovery force induced in the supporting plate 1b exceeds the magnetic attraction, the attraction is released and the piezoelectric power generation element 1 begins to oscillate thus generating power. Mechanical energy loss, e.g. friction, is reduced between members and energy of the operating load is not lost. COPYRIGHT: (C)2006,JPO&NCIPI

Piezoelectric vibrating segment, supporting structure for piezoelectric vibrating segment, piezoelectric vibrator, and piezoelectric vibrating gyroscope

Abstract: Aspects of the invention can provide piezoelectric vibrating segment, a supporting structure for the piezoelectric vibrating segment, piezoelectric vibrator, and the piezoelectric vibrating gyroscope capable of maintaining stable excited vibrations and stable sensing vibrations. The piezoelectric vibrating segment can include a base section, a plurality of excited vibration arms and sensing vibration arms radially extending from the base section in a single plane. A plurality of first beams having elasticity extending from the base section and between the vibration arms and, at least, a first supporting section formed on the tips of the beams can be formed. The excited vibration arms and the sensing vibration arms are provided with electrode patterns formed thereon to be connected to and driven by a semiconductor device. The piezoelectric segment is encapsulated by a container composed of a base member and a lid member to form a piezoelectric vibrator and a piezoelectric vibrating gyroscope, and stable excited vibrations and stable sensing vibrations are maintained.

Piezoelectric power generation device and piezoelectric ceramics member used therefor

Abstract: In a piezoelectric power generation device and a piezoelectric ceramics member used in the device excellent in its power generation efficiency in which the polarization of piezoelectric ceramics elements is set to the same direction and an extremely thin metallic electrode is sandwiched in between the piezoelectric ceramics elements so that a current output obtained in the piezoelectric power generation device can be improved substantially to about two times as high as a current output obtained by a usual piezoelectric power generation device and the parasitic resonance of the electrode can be prevented, the piezoelectric power generation device generates power by applying a distortion deformation to piezoelectric ceramics members formed in plate shapes The piezoelectric power generation device includes the piezoelectric ceramics members each having the two plate shaped piezoelectric ceramics elements whose polarization is set to the same direction and the extremely thin metallic electrode interposed between the piezoelectric ceramics elements, the piezoelectric ceramics member being formed in a laminar shape by uniting the piezoelectric ceramics elements through the metallic electrode; and the cushion materials for supporting central parts or both end parts of one surfaces of the piezoelectric ceramics members Thus, the piezoelectric power generation device has a soft support structure in which the natural oscillation of the piezoelectric ceramics members is hardly transmitted to other structural members A step part is formed in the piezoelectric ceramics member and the metallic electrode

Piezoelectric power generation mechanism and wireless switch utilizing it

Abstract: PROBLEM TO BE SOLVED: To obtain a piezoelectric power generation mechanism in which energy loss is reduced when an external driving force acts and to generate power with high efficiency for the external driving force. SOLUTION: The piezoelectric power generation mechanism comprises a piezoelectric power generation element 1 including a piezoelectric element 1a and a resiliently deformable supporting plate 1b bonded with the piezoelectric element 1a, and a spring drive section 2 having one fixed end 2a and the other free end 2b. The spring drive section 2 holds the supporting plate 1b of the piezoelectric power generation element 1 fixedly at a fixing point 1c. When an external driving force acts on the free end 2b and then it is released, the spring drive section 2 oscillates. The piezoelectric power generation element 1 oscillates by receiving oscillation from the spring drive section 2, and the supporting plate 1b and the piezoelectric element 1a bend to induce a stress in the piezoelectric element 1a thus generating power. Since oscillation energy is preserves as the potential energy of each spring, self-attenuation of oscillation is retarded and power can be generated efficiently. COPYRIGHT: (C)2006,JPO&NCIPI

Piezoelectric material, manufacturing method thereof, and non-linear piezoelectric element

Abstract: A piezoelectric material is provided that has mobile point defects which are arranged so that the short-range order symmetry is matched with the crystal symmetry of the ferroelectric phase. A large non-linear electrostrain effect is obtained by the reversible domain switching under electric field in the ferroelectric material. Thus, it is possible to provide a piezoelectric material and its element having a large and steep deformation even at low voltage. Its manufacturing method is also disclosed.

Piezoelectric air valve and multiple-type piezoelectric air valve

Abstract: The air valve includes a valve body for controlling operations to open and close the communication between an air pressure chamber and an air outlet, a piezoelectric element for generating driving force in the form of displacements, and a displacement enlarging mechanism for enlarging the small displacements generated by the piezoelectric element by the principle of a pry and applying the enlarged displacements to the valve body. The enlarged displacements cause a large and sufficient gap to be developed between the air pressure chamber and the air outlet when a voltage is applied to the piezoelectric element. When the applying of voltage to the piezoelectric element is stopped, the resetting force of the piezoelectric element itself causes the gap to be closed quickly.

Nano-positioning system using linear ultrasonic motor with "shaking beam"

Abstract: In this paper the ultrasonic linear motor based on shaking beam and nano-positioning mechanical system were investigated. The advantages of the ultrasonic linear motor are high resolution, no magnetic noise generation due to the DC characteristics of the piezoelectric device, high servo rigidity, high holding torque and none additional brake system. It was confirmed that ultrasonic linear motor is suitable for nano-motion positioning with various speeds at close-loop control. The ultrasonic linear motor based on shaking beam was described and the nano-positioning systems using the ultrasonic linear motor were investigated.

Characteristic analysis of an ultrasonic micromotor using a 3 mm diameter piezoelectric rod

Abstract: Smart systems and devices generally use certain microstructures, e.g.?rod-?and strip-shaped structures. In this paper, a miniaturized piezoelectric rod is analysed using the finite element method (FEM) and a laser scanning vibrometer (LSV). The effects of some factors, including the detailed structure, material parameters and input voltage, on the resonant frequencies and vibration behaviors of a piezoelectric rod are studied. On the basis of experimental results, the vibration modes of the piezoelectric rod can be made available for use in fabricating an ultrasonic micromotor or piezoelectric actuators of other types. The prototype motor fabricated here has a maximum output torque of 410??N?m for a stainless steel stator and 360??N?m for a copper stator.

Modelling of the travelling wave piezoelectric motor stator: an integrated review and new perspective

Abstract: Articles from different areas which are closely related to the modelling of the stator of travelling wave ultrasonic motors (TWUMs) are reviewed in this work. Thus, important issues relevant to this problem are identified from the areas of vibration of annular plates, laminated plate theories, and modelling of piezoelectric transducers. From this integrated point of view, it becomes clear that there are some very important issues yet to be addressed in the modelling of TWUMs. Firstly, the influence of material properties and stator dimensions on output efficiency, electromechanical coupling coefficients (EMCC) and maximum output energy is to be investigated in more detail. Secondly, the modelling of the electric potential field (by explicitly including the charge equation) for TWUMs seems to be a must for better prediction of displacements and electric fields close to the resonance, as suggested by some recent works [1]. Moreover, the improvement of current models by using shear deformation (or higher order) laminated plate theories (LPTs) in conjunction with approximated methods of solution are discussed. In addition to analytical models, those works using Finite Element and Finite difference Methods (FEM and FDM) for the modelling and simulation of the TWUM stator dynamics are reviewed.

Performance comparison and modeling of PZN, PMN, and PZT stacked actuators in a levered flexure mechanism

Abstract: This article presents a theoretical and experimental assessment of a translation stage design based on a piezoelectric actuator and levering mechanism. This mechanism incorporates stacked piezoelectric actuators of dimensions 5×5×5 mm3 with each stack made from ten plates of 0.5 mm thickness pushing against a symmetric lever design with an ideal amplification of 6.05:1. Three different stacks made from PZN, PMN, and PZT were tested in a nominally similar mechanism to produce displacements of 101, 104, and 33 μm, respectively. Because of their different elastic moduli, the fundamental resonances with each respective device were 670, 729, and 759 Hz. Lagrange analysis of a lumped model of the mechanism is used to estimate the fundamental mode natural frequency of the system while a model for “lost motion” is also presented. This system has been assembled and evaluated experimentally to assess the validity of the models. In general, these models are shown to provide a reasonable estimate of the mechanism performance in terms of lost motion while predicting higher values for the fundamental frequency. The deviations from the model are consistent with the uncertainties associated with rigid body assumptions and the unknown compliances of assembly interfaces and suggest directions for future research in the modeling of such systems.