Showing papers on "Piezoelectric motor published in 2001"

Analysis of piezoelectric coupled circular plate

Abstract: This paper deals with the vibration analysis of a circular plate surface bonded by two piezoelectric layers, based on the Kirchhoff plate model. The form of the electric potential field in the piezoelectric layer is assumed such that the Maxwell static electricity equation is satisfied. The validation of the theoretical model is done by comparing the resonant frequencies of the piezoelectric coupled circular plate obtained by the theoretical model and those obtained by finite-element analysis. The mode shape of the electric potential obtained from free vibration analysis is generally shown to be non-uniform in the radial direction in contrast to what is commonly assumed. The piezoelectric layer is shown to have an effect on the frequencies of the host structure. The proposed model for the analysis of a coupled piezoelectric circular plate provides a means to obtain the distribution of electric potential in the piezoelectric layer. The model provides design reference for piezoelectric material application, such as an ultrasonic motor.

Tracking control of piezoelectric actuators

Abstract: This paper deals with a new tracking control method for piezoelectric actuators. When actuating in an open-loop manner, in order to compensate for the creep effect of the piezoelectric transducer as well as hysteresis, a new concept of `voltage creep' is proposed, which is represented by the two parameters V0 and γv. It is shown that these two parameters have the properties of wiping out and congruency, which make it possible to derive parameter values appropriate to control piezoelectric actuators using the Preisach model. Finally, a tracking control experiment of piezoelectric actuators for an arbitrary desired trajectory is performed giving greatly improved results compared to other open-loop actuating methods.

Piezoelectric energy harvester and method

Abstract: A self contained device for harvesting electrical energy from linear and rotary motion has a sensor with amplifiers (104, 106) for tensile stretching of a piezoelectric body (100) with magnification of the applied force. The piezoelectric body is a monolithic plate with surface electrodes (120, 122) covering its top and bottom surfaces.

Method and apparatus for calibrating piezoelectric driver in dual actuator disk drive

Abstract: A method and apparatus are disclosed which are operable to determine a capacitance associated with at least one piezoelectric element in an dual actuator disk drive. The capacitance information is used to adjust a driver used to drive the piezoelectric element. Capacitance is determined by supplying a predetermined current into the piezoelectric element(s) for a predetermined time period. A voltage associated with the piezoelectric element(s) is measured following the predetermined time period. The capacitance of the piezoelectric element(s) is then calculated based on the measured voltage, the current supplied, and the predetermined time period.

Vibratory motors and methods of making and using same

Abstract: A single piezoelectric is excited at a first frequency to cause two vibration modes in a resonator producing a first elliptical motion in a first direction at a selected contacting portion of the resonator that is placed in frictional engagement with a driven element to move the driven element in a first direction. A second frequency excites the same piezoelectric to cause two vibration modes of the resonator producing a second elliptical motion in a second direction at the selected contacting portion to move the driven element in a second direction. The piezoelectric is preloaded in compression by the resonator. Walls of the resonator are stressed past their yield point to maintain the preload. Specially shaped ends on the piezoelectric help preloading. The piezoelectric can send or receive vibratory signals through the driven element to or from sensors to determine the position of the driven element relative to the piezoelectric element or resonator. Conversely, the piezoelectric element can receive vibration or electrical signals passed through the driven element to determine the position of the driven element. The resonator is resiliently urged against the driven element, or vice versa. Plural resonators can drive common driven elements.

Piezoelectric device for injector

Abstract: A piezoelectric device most suitably applicable as a drive source for a fuel injector is disclosed. The piezoelectric device comprises a plurality of piezoelectric layers (11) and a plurality of inner electrode layers (21, 22) stacked alternately with each other. The outer peripheral side surfaces (101, 102) are formed with a pair of outer electrode layers (31, 32) electrically turned on alternately in such a manner that the inner electrode layers (21, 22) located adjacently to each other through the piezoelectric layers (11) have different polarities. Second outer electrode layers (33, 34) configured of a conductive material having a larger breaking elongation than the first outer electrode layers (31, 32), respectively, are formed on a pair of the first outer electrode layers (31, 32).

New method for multiple-mode shunt damping of structural vibration using a single piezoelectric transducer

Abstract: A new multi-mode semi-active shunt technique for controlling vibration in piezoelectric laminated structures is proposed in this paper. The effect of the ``negative capacitor'' controller is studied theoretically and then validated experimentally on a piezoelectric laminated simply-supported beam. The negative capacitor controller is similar in nature to passive shunt damping techniques, as a single piezoelectric transducer is used to dampen multiple modes. While achieving comparable performance to that of the purely piezoelectric passive shunt schemes, the negative capacitor controller has a number of advantages. It is simpler to implement, less sensitive to environmental variations, and can act as a multiple mode and broadband vibration controller. Experimental resonant amplitudes for the piezoelectric laminated simply-supported beam 1st, 2nd, 3rd, 4th and 5th modes were successfully reduced by 6.1, 16.3, 15.2, 11.7 and 10.2dB.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Design and fabrication of a new traveling wave-type ultrasonic linear motor

Abstract: This paper describes the development of a new traveling wave-type ultrasonic linear motor The motor consists of a metallic stator and two piezoelectric ceramic plates bonded to the stator, thereby eliminating the need for external vibrators The two piezoceramic plates excite two ultrasonic standing waves with a certain phase difference, which convert to a traveling wave when combined together The operation principle of the motor is presented along with the theoretical equations, and the feasibility is verified using the finite element method Based on the finite element analyses, detailed dimensions and boundary conditions are determined for the proper generation of a traveling wave Experimental fabrication and characterization of a sample motor is performed to confirm the numerical results and prove the practical applicability of the new structure The new linear motor presented in this work offers a relatively simple structure compared to traditional traveling wave-types while maintaining all the characteristic features of an ultrasonic motor

Novel Piezoelectric-Based Power Supply for Driving Piezoelectric Actuators Designed for Active Vibration Damping Applications

Abstract: This paper describes a novel step-up DC-AC piezoelectric-based power supply for driving piezoelectric actuators. Piezoelectric actuators have been demonstrated to be very attractive in applications requiring fast response and high actuation force, such as active damping applications. These actuators are commonly installed in self-powered systems (cars, helicopters, aircrafts, satellites, etc.) with limitation in the battery performance, dimensions and maximum weight. Nevertheless, the required driving electrical AC voltage for these actuators is typically in the range of 100 V to 1000 V, quite far from the 9 to 24 V of common batteries. Thus, the use of heavy, large and EMI-noisy electromagnetic transformers becomes necessary which is a drawback for the compact size required. This paper introduces an alternative system for driving piezoelectric actuators using a novel design of piezoelectric transformer, the Transoner®. The proposed solution allows a reduction in size, weight and magnetic noise generation compared to the classical electromagnetic-based systems. The work represents a completely novel approach to the possibilities of piezoelectric transformers for powering high voltage piezoelectric actuators. The solution offers significant advantages in environments requiring high integration, low weight, and low electromagnetic interferences operated with batteries. A circuit configuration capable of converting a 24 V DC input voltage up to 600 Vpp AC output voltage with frequency and magnitude control is implemented. Experimental results are presented for a standard multilayer piezoelectric actuator driven at 100 Vpp within the range of 10 Hz to 500 Hz.

Electric circuit switch for a motor vehicle comprises vibration or audible signal from piezoelectric element used in touch-pad to generate operating signal

Abstract: The circuit includes an operating unit (21), such as a touch pad or touch-screen, comprising a piezoelectric element for generating an operating signal. A response signal is generated by a unit (23) that comprises a device for generating a periodic electrical signal that is connected to the piezoelectric element so that the periodic electrical signal excites vibration. The oscillation produces an audible acoustic signal. The piezoelectric element may be integrated in a vehicle interior. An Independent claim is also included for a method of generating a haptic and/or acoustic signal.

Piezoelectric device with feedback sensor

Abstract: A piezoelectric device, such as a piezoelectric fan or microjet generator, for moving a fluid comprising a fluid-moving member having a first piezoelectric (PZT) actuator element coupled thereto to drive or actuate the movable member and a second piezoelectric (PZT) sensing element coupled thereto to provide feedback information related to fluid parameter. The second PZT element also can be used to drive the movable member in conjunction with the first PZT element. The feedback information can be used by a controller to control operation of the piezoelectric device.

Dual stage actuator systems for high density hard disk drives using annular rotary piezoelectric actuators

Abstract: A piezoelectric actuator is disclosed including an annular piezoelectric element and a base. There is a gap along the radial direction of the annular piezoelectric element. One of the two ends, i.e., the fixed end of the said annular element, is connected to the base, while the other end is free. The base is made of piezoelectric materials. Furthermore, the annular element is divided into two or more annular parts along the direction of its circumference by the electrode patterns applied on its two opposite surface and/or its polarization directions. When driving voltages are applied, the actuator can generate roughly a rotary motion around the center of the annular piezoelectric element. The annular rotary actuator could be either a single plate or with multilayer structure. The present invention further relates to a dual stage head positioning actuator system of a hard disk drive with a plurality of disks and a plurality of vertically aligned head sliders mounted on distal ends of a plurality of suspensions via the annular piezoelectric actuators.

Acceleration sensor, an acceleration detection apparatus, and a positioning device

Abstract: An acceleration sensor housed in a confined space can detect rotational acceleration with great accuracy. The acceleration sensor has first and second piezoelectric elements with electrodes for outputting a charge produced by strain deformation. Each of the first and second piezoelectric elements has at least one piezoelectric body and a support block for supporting the piezoelectric body. The electrodes are provided on opposite sides of the piezoelectric body. One surface of the first piezoelectric element and one surface of the second piezoelectric element are substantially parallel to each other.

Electro-luminescent backlighting circuit with multilayer piezoelectric transformer

Abstract: The present invention relates to a multilayer piezoelectric transformer that uses a composite resonant vibration mode for step-up voltage conversion. More specifically, a multilayer piezoelectric transformer is provided using radial and shear vibration modes for step-up voltage conversion applications. Adjacent layers of piezoelectric ceramic act as a constraint on the deformation of one face of the input layers, leading to a gradient in the radial deformation of both the input and output portions. The piezoelectric transformer is used in a circuit for providing electro-luminescent (EL) backlighting.

Test Cases for Modeling and Validation of Structures with Piezoelectric Actuators

Abstract: A set of benchmark test articles were developed to validate techniques for modeling structures containing piezoelectric actuators using commercially available finite element analysis packages. The paper presents the development, modeling, and testing of two structures: an aluminum plate with surface mounted patch actuators and a composite box beam with surface mounted actuators. Three approaches for modeling structures containing piezoelectric actuators using the commercially available packages: MSC/NASTRAN and ANSYS are presented. The approaches, applications, and limitations are discussed. Data for both test articles are compared in terms of frequency response functions from deflection and strain data to input voltage to the actuator. Frequency response function results using the three different analysis approaches provided comparable test/analysis results. It is shown that global versus local behavior of the analytical model and test article must be considered when comparing different approaches. Also, improper bonding of actuators greatly reduces the electrical to mechanical effectiveness of the actuators producing anti-resonance errors.

Piezoelectric acoustic actuator

Abstract: An acoustic actuator comprises a radially poled piezoelectric or electrostrictive drive element which is electroded on its inner and outer faces, and an acoustic diaphragm coupled to the upper surface of the piezoelectric drive element. As a voltage is applied to the electrodes, the piezoelectric drive element expands and contracts in the radial direction and the acoustic diaphragm displaces upward or downward, generating a sound wave. In an alternative embodiment, the piezoelectric or electrostrictive drive element is comprised of several subelements laid end to end and radially poled. In another embodiment, the piezoelectric or electrostrictive drive element is comprised of several subelements laid end to end which are thickness-poled reduced and internally biased oxide wafers of piezoelectric material.

Method of driving a piezoelectric transformer and power source apparatus using the same

Abstract: The invention provides a method of driving a piezoelectric transformer and a power source apparatus using the same. For a circuit for driving a piezoelectric transformer which steps up a voltage input from a primary electrode by a piezoelectric effect to output the stepped up voltage from a secondary electrode, the gradient (linear differential value) of a step-up ratio at the piezoelectric transformer is detected, and the detected gradient is used to control the driving frequency for the piezoelectric transformer so that the driving frequency approaches to the resonant frequency of the piezoelectric transformer.

A new disc-type ultrasonic motor

Abstract: A new approach to establish a design rule for a new disc-type ultrasonic motor (LEMUM) is proposed. In this design rule, an elastic model of lateral elliptical motion induced by exciting piezoelectric ceramics embedded on an elastic metal disc is setup to estimate the frictional driving force between the rotor and stator of the ultrasonic motor. Furthermore, we evaluate the coupled interaction between mechanical vibration and electrical excitation by electrical equivalent circuit analysis. For the confirmation of the proposed design rule, we measure the characteristics of the new disc-type ultrasonic motor. As a consequence, the proposed design rule is very adaptive for disc-type ultrasonic motor.

Surface acoustic wave motor and apparatus having the same

Abstract: A surface acoustic wave motor with high energy efficiency, which may efficiently execute recovery of energy of surface acoustic waves propagated to the ends of piezoelectric substrate and re-excitation by the recovered energy. A comb-shaped electrode having interdigital structure for generating surface acoustic waves and two unidirectional comb-shaped electrodes having interdigital structure for recovering and re-exciting surface acoustic wave energy are arranged on a piezoelectric substrate, and a slider is disposed between the comb-shaped electrode for generating surface acoustic waves and the unidirectional comb-shaped electrodes for recovering and re-exciting surface acoustic wave energy. The surface acoustic wave generated by the comb-shaped electrode is recovered as an electric power by the unidirectional comb-shaped electrode arranged at one end of the piezoelectric substrate, and applied to the unidirectional comb-shaped electrode arranged at the other end thereof to re-excite the piezoelectric substrate.

Surface acoustic wave motor using an energy circulation driving method

Abstract: To reduce the driving power, energy circulation driving method was significantly effective. We fabricated a SAW motor using the energy circulation driving method and measured its driving performance under the condition of large pre-load. From the experimental results, the driving efficiency of 5% or more and driving the SAW motor at the input power below 1 W have been attained for the first time. Furthermore, the energy flow of the stator transducer was calculated by using 8-port f-matrices.

The Design, Fabrication, and Modeling of a Piezoelectric Linear Motor

Abstract: The focus of this research was to create a linear motor that could easily be packaged and still perform the same task of the current DC motor linear device. An incremental linear motor design was decided upon, for its °exibility in which the motor can be designed. To replace the current motor it was necessary to develop a high force, high speed incremental linear motor. To accomplish this task, piezoelectric actuators were utilized to drive the motor due their fast response times and high force capabilities. The desired overall objectives of the research is to create an incremental linear motor with the capability of moving loads up to one hundred pounds and produce a velocity well over one inch per second. To aid the design process a lumped parameter model was created to simulate the motor's performance for any design parameter. Discrepancies occurred between the model and the actual motor performance for loads above 9.1 kilograms (20 pounds). The resulting model, however, was able to produce a good approximation of the motor's performance for the unloaded and lightly loaded cases. The phase one design was limited by time constraints so a relatively low risk design was produced. The resulting incremental linear motor produced a velocity of 4.9 mm/sec (0.2 in/sec) at a drive frequency of 50 Hz. The velocity of the motor was limited by the drive frequency that the ampli ̄ers could produce. The motor was found to produce a respectable stall load of 17 kilograms (38 pounds). The stall load of the phase one design was severely limited by clearance losses. An analysis of the motor's performance was conducted, possible improvements and future work recommendations for a phase two design are presented.

V-stack piezoelectric actuator

Abstract: Aeroelastic control of wings by means of a distributed, trailing-edge control surface is of interest with regards to maneuvers, gust alleviation, and flutter suppression. The use of high energy density, piezoelectric materials as motors provides an appealing solution to this problem. A comparative analysis of the state of the art actuators is currently being conducted. A new piezoelectric actuator design is presented. This actuator meets the requirements for trailing edge flap actuation in both stroke and force. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties while displaying linearity over a wide range of stroke. The V-Stack Piezoelectric Actuator, consists of a base, a lever, two piezoelectric stacks, and a pre-tensioning element. The work is performed alternately by the two stacks, placed on both sides of the lever. Pre-tensioning can be readily applied using a torque wrench, obviating the need for elastic elements and this is for the benefit of the stiffness of the actuator. The characteristics of the actuator are easily modified by changing the base or the stacks. A prototype was constructed and tested experimentally to validate the theoretical model.

Drive mechanism employing electromechanical transducer

Abstract: An actuator using the vibration caused by a piezoelectric element. The actuator includes: a base; a vibratory rod bonded to the base; an piezoelectric element bonded to the vibratory rod; and a contact body for contacting frictionally with the vibratory rod under an suitable frictional force exerting therebetween. The piezoelectric element is charged and discharged, so that the piezoelectric element is transformed in one direction relatively fast and in opposite direction relatively slow, and so that the contact body is driven along the vibratory rod in a set direction.

Piezoelectric vibrator unit, liquid jet head, manufacturing method of piezoelectric vibrator unit, and manufacturing method of liquid jet head

Abstract: In a piezoelectric vibrator unit (4) provided with a plurality of piezoelectric vibrators (29) each having internal electrodes (32,33) and piezoelectric material layers (31) laminated alternately, a free end part (23a) of an outermost layer (31a) of a piezoelectric vibrator is trimmed to form a partial recess, thereby adjusting a natural vibration period of the piezoelectric vibrator. The vibrator unit is preferably part of a liquid jet unit such as in ink jet printing heads.

Method and apparatus for controlling piezoelectric vibratory parts feeder

Abstract: An apparatus for controlling a piezoelectric vibratory parts feeder comprises a piezoelectric vibrating unit provided with a piezoelectric vibrating element that vibrates at a predetermined frequency, a bowl adapted to discharge parts accommodated therein by means of the piezoelectric vibrating unit, a driving circuit for driving the piezoelectric vibrating element, and a control unit for outputting a driving signal to the driving circuit to cause a predetermined driving. The control is performed by idling the driving of the piezoelectric vibrating element temporarily at every predetermined driving cycles thereof and controlling the vibration of the piezoelectric vibrating element based on a signal obtained therefrom by its piezoelectric effect during the idling period, for instance, based on a phase difference between a waveform of this signal and the driving signal of the driving circuit.

Design of a Linear High Precision Ultrasonic Piezoelectric Motor

Abstract: BAUER, MARKUS GEORG. Design of a Linear High Precision Ultrasonic Piezoelectric Motor. (Under the direction of Dr. Thomas A.Dow.) To understand the operating principles of linear ultrasonic piezoelectric motors, a motor made by Nanomotion Ltd. was examined and a model of the driving process was developed. A new motor has been designed that uses the same driving process but improves resolution, speed, efficiency and especially controllability. All designs involve at least two independently driven piezoelectric elements, one generating the normal load at the interface and the second generating the tangential driving force. The greatest challenges in developing this motor are 1) the actuator needs to have two different mode shapes at nearly the same frequency and 2) each mode shape must be exclusively excited by one actuator and not by the other. The quality of the operation of the motor directly depends on how well the excitation of both vibrations can be separated. Finite element analysis (FEA) has been used to model the actuator and predict the dynamic properties of a future prototype. The model includes all significant features that have to be considered such as the anisotropy of the piezoelectric material, the exact properties and the dimensions of the actuators (including all joints). Several prototypes have been built, and the resulting mode shapes and natural frequencies have been measured and compared to the computer models. The design concepts as well as the modeling techniques have been iteratively improved. Open loop testing has shown that the motor generates slideway motion such that the steady state slideway velocity is proportional to the excitation voltage. To fully characterize the motor and to demonstrate its full potential for positioning tasks, the motor has been tested in a closed loop control system. Despite saturation of the control input and nonlinearities in dynamics of the motor-slideway system, it was shown that a simple feedback control system using proportional gain or proportional-integrating control algorithms can be used to achieve a stable responsive positioning system. DESIGN OF A LINEAR HIGH PRECISION ULTRASONIC PIEZOELECTRIC MOTOR

Piezoelectric actuator with insulating member separate from piezoelectric device

Abstract: In a piezoelectric actuator 1 using a laminated piezoelectric device 10 having a plurality of layered piezoelectric layers, a metal case 2 is provided on the outside of the side surface of the piezoelectric device 10 . An insulating member 4 made of a piece separate from the piezoelectric device 10 is provided between the piezoelectric device 10 and the case 2.

Piezoelectric motor and a disk drive using same

Abstract: A piezoelectric motor (100) of a linear contact type contains one or more actuators (150 and 151) placed about a rotor (140). Each actuator (150) contains at least one piezoelectric vibrator (120) with a working end (133) urged against the rotor (140). Periodic oscillations of each vibrator (120 and 121) cause compressions of the rotor (140) not exceeding its natural elastic compression limit so after its compression the rotor (140) fully restores its initial cylindrical shape. Such elastic compressions ensure longer operational life of the motor. In another embodiment, each actuator (200) has a laminated design with at least two vibrators (221 and 222) separated by an isolator (223). The isolator extends beyond the vibrators and has appropriate hardness to engage with the rotor (240). A rotor of laminated design is also described to achieve the optimum hardness relative to the hardness of the actuators. The hardness of the vibrator edge is about 5x107 N/cm2 and is much higher than the hardness of the rotor being about 2x106 N/cm2. A disk drive is described as one of the most advantageous applications of the motor of the invention to drive optical and magnetic disks such as in a CD-ROM drive etc.

Piezoelectric actuator and information storage device

Abstract: A piezoelectric actuator capable of providing a large displacement with a low drive voltage, reducing a size and a weight, providing an excellent impact resistance, and being manufactured with high accuracy and low cost, and an information storage device of high recording density having the piezoelectric actuator incorporated therein; the piezoelectric actuator, comprising a hinge plate (220) formed of a center part (221), two side parts (222) extending from both ends of the center part (221) symmetrically with respect to a point, and two arm parts (223) extending from both ends of the center part (221) symmetrically with respect to a point and asymmetrically with respect to a line and a piezoelectric element (210) allowing two arm parts (223) to move apart from and close to each other.

Acoustic imaging systems adaptable for use with low drive voltages

Abstract: Acoustic imaging systems are provided. A representative acoustic imaging system includes a transducer (402) that incorporates a backing and an acoustic element (412) extending from the backing. The acoustic element includes a piezoelectric element (404) and a de-matching layer (410). The de-matching layer is arranged between the backing and the piezoelectric element and exhibits an acoustic impedance greater than that of the piezoelectric element. The piezoelectric element exhibits a thickness that is less than one-half of a wavelength to be generated by the piezoelectric element. Methods also are provided.