Showing papers on "Bimorph published in 1991"

The constituent equations of piezoelectric bimorphs

Abstract: A brief review of applications of piezoelectric bimorphs is presented. The constituent equations which describe the behavior of piezoelectric bimorphs for various mechanical boundary conditions are derived. The internal energy density of infinitesimally small volume elements in thermodynamic equilibrium is calculated in the presence of a voltage on the electrodes, a clamped cantilever beam condition on one side of the beam and a set of three different classical boundary conditions on the other side of the beam. These are a mechanical moment M at the end of the beam, a force F perpendicular to the beam, applied at its tip, and a uniformly distributed body force p. The total internal energy content is calculated by integrating over the entire volume of the beam. Two different beam configurations are considered: parallel polarizations of the two adjoining elements of the beam with an internal electrode; and antiparallel orientation without an internal electrode. The canonical conjugate of the moment is calculated as the angular deflection at the tip of the beam α, while that of the force at the tip is the local vertical deflection δ. The canonical conjugate of the uniform load on the beam is found to be the volume displacement V of the beam. The canonical conjugate of the voltage across the electrodes is the charge on the electrodes. The equations are given in the direct form, with external parameters (M, V), (F, V), and (p, V) as independent variables and also in a linear combination with (M, F, p, V) as variables. These constituent equations can be used to calculate the behavior of the bimorph under any condition that can be described as a linear combination of forces at the tip, moments at the tip and uniform loads on the entire beam. This allows us to use the bimorph as a black box, without having to consider its internal movement or charges.

Surface-mount piezoceramic accelerometer and method for making

Abstract: A piezoceramic accelerometer of the cantilever bending-beam bimorph type is provided with housing structure of straightforward easily-manufactured design. Because of its design features, the accelerometer is comparatively low in cost, rugged, reliable, and inherently low in internal capacitance. Consequently, a self-generated signal of favorable value proportionate to applied acceleration is provided by the accelerometer. The accelerometer provides for use of Surface Mount Technology (SMT), which allows further manufacturing cost reductions in uses of the accelerometer.

Fine scanning mechanism for atomic force microscope

Abstract: fine scanning mechanism for an atomic force microscope includes: a cylindrical piezoelectric element (100); a first probe attaching portion (120) attached to an end-portion (100a) on the side (1023) of a three-dimensionally displaceable portion of the cylindrical piezoelectric element; a first probe (110) attached to the first probe attaching portion (120); a displacement bimorph piezoelectric element attaching portion (220) attached to the end portion on the side of the three-dimensionally displaceable portion of the cylindrical piezoelectric element; a displacement bimorph piezoelectric element (200) attached to the displacement bimorph piezoelectric element attaching portion (220); a cantilever attaching portion (320) attached to an end portion on the side of the one-dimensionally displaceable portion of the displacement bimorph piezoelectric element (200); a cantilever (300) attached to the cantilever attaching portion (320); a second probe attaching portion (420) attached to an end portion (300b) on the side of the distortedly displacement portion of the cantilever; a second probe (410) attached to the second probe attaching portion (420); and a stationary sample tray (500) disposed to confront the second probe

Single crystal domain driven bender actuator

Abstract: A single crystal bender actuator for selectively positioning a movable precision optical or acoustical component is described which comprises a single crystal of barium titanate, barium strontium titanate, barium lead titanate, potassium niobate tantalate, lead titanate-lead magnesium niobate or other material in which a special domain structure can be induced to produce a very high strain bimorph configuration, the single crystal operatively interconnecting support structure and the movable component, and means for selectively applying an electric field of controllable field strength to the crystal.

Network representation for piezoelectric bimorphs

Abstract: The networks associated with the bimorph matrix are presented. The bimorph matrix is diagonalized and eigenvalues and eigenstates are found for the extremes of nonpiezoelectric and strong piezoelectric coupling. A physical interpretation of the eigenvalues and eigenstates is proposed. The bimorph matrix is also diagonalized through elementary operation matrices, which give the matrix in equivalent form. The transformation matrices are of upper triangular form. This transformation yields networks of the simplest possible connection schemes. It is shown that when fewer than the maximum number of boundary conditions are applied, the networks are easily simplified. The networks of the admittance and impedance matrix are presented. >

Bimorph Type Actuators Using Lead Zinc Niobate-Based Ceramics

Abstract: The authors examined the properties of actuators on several kinds of lead zinc niobate-based (PBZM) ceramics. Bimorph type actuators were manufactured from four kinds of PBZM family ceramics, and these ceramics were investigated regarding the properties relevant to actuators, i.e., hysteresis, creep, temperature coefficient, and so on. As a result, it has been found for the PBZM family ceramics that the relative dielectric constant influences the electrostrictive constant, but hardly influences hysteresis, creep, nor the temperature coefficient near room temperature. Therefore, an ideal actuator which has small hysteresis, small creep, and a large electrostrictive constant can be obtained. The actuator which had the best property as an actuator in this examination had about 2%-hysteresis and creep, with a minus 1%-temperature coefficient near room temperature.

The effectiveness of a piezoelectric bimorph actuator to perform mechanical work under various constant loading conditions

Abstract: The equations governing the energy and work relations for a piezoelectric bimorph for various mechanical boundary conditions are derived. The stored energies and external work are calculated for a clamped cantilever bimorph with an antiparallel orientation. The system is subjected to an applied voltage on one side of the beam and three different classical boundary conditions on the other side. These conditions are: a mechanical moment, M, at the end of the beam, a perpendicular force, F, applied at the tip of the beam, and a uniform load, p, across the length of the beam. The stored energies are related to the system through the canonical conjugates of the boundary conditions, namely: an angular deflection, α, a vertical deflection, δ, and a swept volume displacement, V, respectively. Through the use of these relationships the total internal energy supplied to the bimorph is calculated. The work performed by the bimorph on its environment is also calculated. With the stored energies and the work ...

Motor and an optical apparatus having such motor

Abstract: A motor for driving a moving member with respect to a member which serves as a reference of the movement includes at least two first piezoelectric actuators for operating an operating portion thereof such that it is brought into contact with and is moved away from said member, and at least one second piezoelectric actuator operating such that it changes a distance between the plurality of first piezoelectric actuators. At least one of the plurality of first piezoelectric actuators employs a bimorph type piezoelectric element.

Piezoelectric Thin Film Ultrasonic Micromotors

Abstract: Thin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant and breakdown strength of the films lead to high stored energy densities. Evaluation of the film as a bimorph yielded a value of -88 pC/N for the transverse piezoelectric strain coefficient, d31; the relevant electromechanical coupling factor, k31, calculated thereupon was 0.22. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimized prototype micromotors show rotational velocities of 100–300 rpm at drives of 3–5 V.

Adaptive piezoelectric shell structures - Theory and experiments

Abstract: Active "smart" space and mechanical structures with adaptive dynamic characteristics have long been interested in a variety of high-performance systems, e.g. flexible space structures, flexible robots, "smart" machines etc. In this paper, an active adaptive structure made of piezoelectric materials is proposed and evaluated. Electromechanical equations of motion and generalised boundary conditions of a generic piezoelectric shell subjected to mechanical and electrical excitations are derived using Hamilton's principle and the linear piezoelectric theory. The structural adaptivity is achieved by a voltage feedback (open or closed loops) utilising the converse piezoelectric effect. Applications of the theory is demonstrated in a bimorph beam case and a cylindrical shell case. Frequency manipulation of the bimorph beam is studied theoretically and experimentally. Damping control of the cylindrical shell via in-plane membrane forces is also investigated.

Displacement Characteristics of Series-Type Bimorph Actuator under High Applied Voltage

Abstract: Experimental and theoretical studies on the applied voltage-displacement characteristics of a piezoelectric series type bimorph were performed. The displacement increased with an increase in the applied voltage until dielectric breakdown. An electric field higher than its coercive field (Ec) can be applied to the bimorph, because its poling direction is opposite to the field, owing to an electric charge balance between its two layers. On the other hand, the displacement of a parallel-type bimorph fell to zero when the applied voltage per unit length equalled Ec. The series-type bimorph displayed larger displacement and higher reliability than the parallel-type bimorph.

Adaptive optics using curvature sensing

Abstract: An adaptive optics scheme is proposed which uses curvature sensing, a bimorph PZT deformable mirror, a simple extrafocal image splitter and a sensitive, low noise Solid State Photomultiplier array detector. With curvature sensing, the incoming wavefront is described in terms of curvature which can be directly mapped point-by-point to a driven deformable segmented mirror. While other methods such as Hartmann, require time and cost consuming computations, the curvature mirror can be driven in near real-time taking full advantage of the 11 kHz bandwidth of the bimorph mirror. The SSPM is easily configured to any array pattern without loss of performance. The arrangement is particularly suited to large telescopes in the 8 m class for which the wavefront curvature sensor can provide additional useful information to correct for collimation and structural variations as well as the rapid seeing correction.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The effectiveness of a piezoelectric bimorph to perform mechanical work against various spring-type loads

Abstract: The equations governing the energy and work relations for a piezoelectric bimorph working against a spring-type load are derived. A work cycle is assumed in which a piezoelectric bimorph pushes against a spring, compressing it, after which the spring is latched in position, ready to transfer its energy in a process where it can be used. The energy stored in the spring is calculated and related to the electrical energy taken in by the bimorph to enable it to compress the spring. An effectiveness μ is defined as the ratio of the energy transferred by the bimorph and the energy put in by the generator. Three types of springs are considered: a helical spring, attached at the tip to generate a moment M at the tip that depends on the rotation α of the tip; a coil spring, attached at the tip to provide a force F, proportional to the deflection; and a gas spring acting uniformly over the entire length of the bimorph, with a pressure p that is proportional to the displaced volume V. The effectivenesses μM, μF, μP ...

Bimorph moving magnetic head device

Abstract: PURPOSE:To prevent azimuth loss in advance by forming a step difference to a piezoelectric plate and fixing a magnetic head to the step so as to eliminate the tilt in the magnetic head. CONSTITUTION:A magnetic head chip 5 is fixed to a bimorph element 4. A conductive metallic thin plate 3 is inserted and fixed between two piezoelectric plates 1,2 of the bimorth element 4. A step difference 8 is formed at the end of the piezoelectric plate 1 by the method of grinding or the like. The flatness of the step difference 8 is formed to be 2-3 mum or below and the magnetic head 5 is fixed to the step difference 8. Thus, the tilt in the magnetic head is eliminated and the azimuth loss is prevented in advance.

Piezo-electric type grasping device

Abstract: PURPOSE:To convert application of a voltage directly into operation to grasp a hand base body and to reduce the size and the weight of a device through elimination of a drive converting mechanism by a method wherein at least the one of hand base bodies positioned juxtaposition with each other is formed by using a bimorph type piezo-electric element substance. CONSTITUTION:When a voltage is applied between an intermediate electrode 2a and two surface electrode plates 2d and 2e, the one piezo-electric element plate 2b is expanded and the other piezo-electric element plate 2c is contracted. By means of the expansion and contraction difference, the tip side of a band base body 2A (or 2B) formed by using a bimorph type piezo-electric element substance is bend and displaced in a direction in which it approaches or separates away from the other hand base body 2B (or 2A). The bending displacement forms switching operation between grasping and release of a work by means of work grasping parts 3 and 4 on the tip sides of the two hand base bodies 2A and 2B, and grasping and release of the work are effected.

Viscosity measuring apparatus

Abstract: PURPOSE:To make it possible to provide a highly accurate simple apparatus by oscillating a bimorph element in a fluid to be measured so that the impedance of the element indicates the value corresponding to the viscosity of the fluid, and measuring the viscosity by a specified operating expression CONSTITUTION:A viscosity sensor 1 comprising a bimorph element wherein two piezoelectric elements are stuck, a sensor driving circuit 2, a signal converting part 3, an operating part 4 and the like are provided When the sensor 1 is submerged and oscillated in a fluid to be measured, the impedance of the sensor 1 in driving is decreased in response to the viscosity of the fluid The impedance is converted into a data that can be operated in the converting part 3 The impedance is operated in the operating part 4 The result is inputted into the operating expression stored in data memory 9 The viscosity is computed based on viscosity operating data and displayed on a display device 6 Thus, the apparatus characterized by high accuracy and less measuring errors can be manufactured

A tactile sensor for the determination of object positions

Abstract: A tactile sensor has been designed and fabricated for fast and accurate determination of object positions. The sensor is a cantilever beam on which a piezoelectric heterogeneous bimorph and a piezoelectric strain sensor are integrated. Deflection measurements of the bimorph have shown that the bender has a square dependence on the amplitude of the voltage. Deflections as large as 1166 mu m at -6 V were registered for a 2980- mu m-long bimorph. The apparent d/sub 31/ under a bias of 4 V was 108*10/sup -12/ m/V. The large magnitude of deflection was the result of enhanced piezoelectric effect under strong static field. >

Shape control of piezoelectric bimorph mirrors

Abstract: The application of monolithic piezoelectric bimorph deformable mirrors for optical wavefront correction is studied. These mirrors are fabricated from laminations of biaxial piezoelectric polymer sheets. The equations of motion governing flexural and thickness motions are derived from first principles, assuming linearly elastic biaxially-poled laminae. The bimorph is segmented into actuation 'zones' for structural control, providing actuation in terms of distributed moments. It is shown that this actuation strategy provides influence functions with a significantly more localized response (e.g., a higher spatial bandwidth) than point force/displacement actuation for structures having equivalent geometric and material properties. This is due to the bimorph actuation providing a spatial differentiation of the structural response as compared to point force actuation.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Piezoelectric bimorph element and driving method therefor

Abstract: PURPOSE:To prevent insulator breakdown, deterioration of a displacement characteristic by multiplying the ratio of the thicknesses of a forward electric field applying side piezoelectric plate to a backward electric field applying side piezoelectric plate by specific times as large as the ratio of the electric field value of maximum electric field dependency of piezoelectric constant of the forward plate to coercive electric field value of the reverse plate. CONSTITUTION:In a piezoelectric bimorph element formed in a bimorph structure by boding two piezoelectric plates, piezoelectric d constants of a forward electric field applying side piezoelectric plate 1 and a backward electric field applying side piezoelectric plate 2 are made different, and the ratio of the thicknesses of the plate 1 to the plate 2 is set to 1.2-2.0 times as large as the ratio of the electric field value of maximum electric field dependency of piezoelectric d33 constant of the plate 1 to the coercive electric field value of the plate 2. That is, the thicknesses and materials of the plates 1, 2 are altered, a material having large piezoelectric d constant is used as the plate 1, and the electric field value is so applied that the electric field induction distortion becomes maximum. On the other hand, a piezoelectric material having large coercive electric field value is used as the plate 2 in which its available voltage is limited by the coercive electric field value to obtain a piezoelectric bimorph element having small insulator breakdown and high reliability.

University of Hawaii adaptive optics system: II. Computer simulation

Abstract: A review of computer simulation of a low-order adaptive system based on curvature sensing and a bimorph mirror is given. The system was designed to accurately follow the lowest order Karhunen Loeve modes of the atmosphere. The purpose of the simulation was system design improvement and the determination of system performance limits. The four main areas of the simulation are described; atmospheric simulation, Fresnel propagation, bimorph model, and sensor feedback model. Results are presented and discussed.

Manufacture of multi-morph element

Abstract: PURPOSE:To manufacture a multi-morph high in yield without causing damage to piezoelectric pieces by a method wherein the primary face of the piezoelectric piece opposite to its other pasting primary face is polished so as to make the piezoelectric piece as thin as prescribed for the formation of a bimorph, and the bimorphs are laminated interposing an electrode between them. CONSTITUTION:Piezoelectric pieces 1 and 2 are made to overlap each other making electrodes 3 and 4 butt against each other and pasted together with an adhesive agent or the like. In succession, the primary faces of the piezoelectric pieces 1 and 2 opposite to their pasted primary faces are polished by a double-side lapping machine so as to make the piezoelectric pieces 1 and 2 as thin as prescribed. At this polish processing, the piezoelectric pieces 1 and 2 are made to so function as to reinforce each other, so that they are protected against damage. In result, a bimorph unit 5 is formed, electrodes 6 and 7 are provided to the bimorph unit 5, and the bimorph units 5 are made to overlap each other and pasted together with an adhesive agent. By this setup, a very thin piezoelectric piece can be polished without being damage, so that it can be manufactured high in yield.

Piezo electric device

Abstract: A piezo-electric device such as a piezo bimorph device includes an intermediate plate, a plate-shaped first piezo ceramic element fixed on one surfaces of the intermediate plate, a plate-shaped second piezo ceramic element fixed on the other surface of the intermediate plate, and a lead wire for connecting the first piezo ceramic element with the second piezo ceramic element. The intermediate plate is made of a hardened tool steel containing carbon from 0.6 to 1.5%, or a fine ceramic material.

Multiple axis manipulator

Abstract: PURPOSE:To carry a very small and light weight device safely by connecting a bimorph type piezoelectric element to comprise a multiple axis manipulator. CONSTITUTION:Bimorph type piezoelectric elements 1a, 1b, and 1c are so constructed as to be perpendicular to one another and connected so that three- axis (x, y, z) drive may be possible. A test piece 3 is mounted on the tip of a manipulator. The piezoelectric element is made of a material such as lead titanate zirconate. The element is 10mmX30mm and 0.5mm thick. When a voltage of + or -30V is applied between a middle electrode and an outer wall, about 500mum displacement can be obtained. Power sources 2a, 2b, and 2c are directly connected with the piezoelectric element 1a, 1b, and 1c respectively. The test piece is subject to change in two directions of, x and y axes by changing the output voltage Va of the power source 2a. When operating the manipulator in only one direction of axis, it is necessary to use a correction circuit which generate a drive voltage for one piezoelectric element from a transfer data signal of an orthogonal coordinate system.

Bimorph type actuator

Abstract: PURPOSE:To enable high-order resonance to be suppressed by changing polling voltage depending upon parts so that each part has a different piezoelectric constant. CONSTITUTION:In manufacturing a piezoelectric ceramic bimorph, for the conditions of polarization inside the ceramics after baking, the directions of polarizations are different in each domain as shown in figure (a), and the spontaneous polarization and the piezoelectric effect generated by those negate each other as a whole. If polling voltage is applied to this from outside, it brings the conditions that the directions of polarizations in each domain are equal as shown in figure (b), and piezoelectric effect occurs. And the arrangement condition of polarizations in each domain of the piezoelectric ceramics is proportioned to external application voltage, that is, polling voltage, so piezoelectric constant is also proportioned to the polling voltage.

Flexible robot arm driven by bimorph type piezoelectric element and control method thereof

Abstract: PURPOSE:To properly perform displacement control of the tip of a flexible arm by using a bimorph type piezoelectric element as an actuator. CONSTITUTION:The position and displacement speed of the tip part of an arm 11 is detected by a sensor 15. A positive or negative voltage is fed to bimorph type piezoelectric elements 12, 13 which are in the vicinity of the fixed part of the arm 11 and provided on both faces of the arm 11 with a command sent from a microcomputor 20 and the position of the tip part of the arm 11 is controlled in the specific position.

Electroacoustic transducer element and devices, with piezoelectric polymer bimorph, especially for producing a loudspeaker with a linear-type radiation diagram

Abstract: The invention supplies a novel electroacoustic transducer element, capable of exhibiting an impedance value of the same order as that of conventional loudspeakers (typically 4 to 8 Ohm), allowing direct matching to the elements of a sound reproduction system (amplifier, filters, etc.). The element consists of two symmetric quadrangular membranes (11, 12), arranged face to face, two opposite edges (13, 14) of which are embedded together, and spaced apart by spacers (15) in the mid-parts, the said membranes each being formed by a film (11, 12) made of piezoelectric polymer material, metallised on its two faces (111, 112, 121, 122), the two metallised films (11, 12) being excited in phase opposition by the same modulated electrical source. Preferential application to the production of linear loudspeakers, with one or more frequency-specialised elements.

The efficiency to convert electrical to mechanical energy of a piezoelectric on silicon bimorph micromotor

Abstract: It is shown that the effectiveness of a heterogeneous bimorph in converting electrical energy into mechanical work is a function of the piezoelectric coupling factor, the thickness ratio and the elastic compliance ratio between the nonpiezoelectric and piezoelectric material comprising the bimorph. It is found that the heterogeneous bimorph has the largest effectiveness in performing work against a constant load applied as a moment. Effectiveness of the bimorph in performing work against a constant load applied as a force at the free end is larger than that of an applied pressure. >

Optical scanning recorder

Abstract: PURPOSE:To preclude deterioration in picture quality due to a surface tilt by providing a deviation quantity correcting means which shifts the position of a light source or a partial position of a light converging means according to information on a deviation quantity. CONSTITUTION:A collimator lens driving device 101 applies a specific voltage to bimorph type piezoelectric elements 111 and 112 according to the surface tilt quantity of a polygon mirror 4. The bimorph type piezoelectric elements 111 and 112 are bent and displaced as shown by an arrow A to displace a collimator lens 2 as shown by an arrow A, thereby controlling the position of a light spot on a photosensitive film 7 in a subscanning direction. An optical component driving device 101, on the other hand, applies a specific voltage to bimorph type piezoelectric elements 114 and 115 according to the quantity of defocusing pertaining to main scanning. The bimorph type piezoelectric elements 114 and 115 are bent and displaced as shown by an arrow B to displace the collimator lens 2 as shown by the arrow B, thereby eliminating the defocusing. Consequently, the deterioration in picture quality due to the defocusing and a pitch irregularity in the subscanning direction is precluded.

Optical switch using bimorph piezoelectric element

Abstract: PURPOSE:To easily realize the 1:N optical switch by controlling the voltages applied to the bimorph piezoelectric elements and moving an optical fiber directly. CONSTITUTION:When the connection of an optical fiber 17 on a movable base 13 is switched from an optical fiber 152 on a fixed base 11 to an optical fiber 153, the voltages applied to the bimorph piezoelectric elements 21 and 25 are controlled and the movable base 13 is moved so that the optical axis of the optical fiber 17 is aligned with the optical axis of the optical fiber 153. Then electromagnetic actuators 551 and 552 are driven to insert pins 531 and 532 into holes 512 and 516 and the movable base 13 is fixed. In such a case, the bimorph piezoelectric elements are variable in deformation quantity with the applied voltage, and the base is moved through a plunger by controlling the applied voltages to perform 1:n switching between the optical fibers. Thus, the 1:n switching with low insertion loss is enabled by the simple constitution.