Showing papers on "Piezoelectric motor published in 1988"

Precise Positioner Utilizing Rapid Deformations of a Piezoelectric Element

Abstract: This paper describes a new method of precise positioning using piezoelectric elements. The method utilizes the friction force between the object to be moved and the base plane, and the reaction of the inertial force caused by a rapid deformation of a piezoelectric element. The configuration of this positioning mechanism is simple : an element for inertial mass is connected to the object to be moved by a piezoelectric element. Through controlling the rapid deformation of the piezoelectric element, we can control the inertial force, which causes a controlled step-like movement of some nanometers up to some ten-micrometers. Repeating this stepping action, it is possible to move the positioner with a velocity of more than one millimeter per second. Applying a sensor feedback to the mechanism, almost the same resolution and accuracy as the sensor can be achieved in position control. This method of positioning also realizes a remarkably simple 3-axial precise positioning table.

Finite element analysis of piezoelectric transducers

Abstract: A finite element technique for modeling the vibrational behavior of arbitrarily shaped piezoelectric transducers immersed in an acoustic fluid is presented. The elastic and electrical responses of the piezoelectric structure are computed by piezoelectric finite elements, and the wave propagation in the ambient acoustic medium is computed by acoustic finite elements. The acoustic feedback of the surrounding acoustic fluid to the piezoelectric solid is considered. This method makes it possible to analyze piezoelectric devices with respect to their mechanical strains and stresses, electrical fields and displacements, and various integral properties, such as the electric input impedance and the electromechanical coupling coefficient. The application of this method to ultrasonic transducers, especially those used in array antennas, is reported. >

Integrated micromechanical piezoelectric motor

Abstract: Small piezoelectric machines comprised of pairs of cantilever beams covered with a piezoelectric material are driven to perform various mechanical tasks. A robot utilizes a plurality of pairs of these piezoelectrically driven beams to move itself and grab, carry or manipulate other objects.

Driving apparatus for ultrasonic motor

Abstract: A driving apparatus for an ultrasonic motor which generates a driving force by using a piezoelectric member, wherein an oscillation frequency fd is varied so as to follow a driving frequency fm which is particular to a mechanical resonance frequency fro when the mechanical resonance frequency fro varies by influence of environment. For this purpose, current and voltage detectors are provided for respectively detecting the current corresponding to the mechanical vibration of the piezoelectric member and the voltage impressed on the piezoelectric member. The phase difference between the detected current and voltage is detected, and this phase difference is used to drive a variable frequency oscillator so as to maintain the phase difference constant. The output of the variable frequency oscillator is then used to drive the driving circuit for the piezoelectric member of the ultrasonic motor.

Collision detection system for a vehicle

Abstract: A collision detection system for a vehicle comprising an acceleration sensor for sensing the acceleration and deceleration of the vehicle wherein the acceleration sensor is a piezoelectric sensor; signal processing circuit coupled to the piezoelectric sensor for generating a first output when the vehicle deceleration is greater than a predetermined amount. A diagnostic pulse generator is coupled to the piezoelectric sensor for applying a diagnostic pulse to the piezoelectric sensor for distorting the piezoelectric sensor, thereby causing the piezoelectric sensor to generate an electrical output. The electrical output is applied to the signal processing circuit wherein the signal processing circuit produces a second output in response thereto. The piezoelectric sensor is mounted on a pendulum such that when the vehicle accelerates or decelerates, the pendulum moves relative to the vehicle thereby distorting the piezoelectric sensor whereby the piezoelectric sensor produces an output as a function of the distortion. The piezoelectric sensor includes an electrode which is divided into a plurality of electrode segments. At least one of the electrode segments is an output electrode for providing an electrical signal as a function of the distortion of the piezoelectric sensor and at least one of the electrode segments is an input electrode for receiving an electrical signal and distorting the piezoelectric sensor in response thereto.

Ultrasonic linear motors using a multilayered piezoelectric actuator

Abstract: A new type of linear motor using a multilayered piezoelectric actuator has been developed in which a mechanically resonating part slides on a stationary rail. The slider consists of a multilayered piezoelectric actuator and an elastic vibratory fork bonded together. The key to obtaining a smooth movement is to realize a slight shift in the resonance frequency of each leg of the fork so that the moving direction can be controlled by changing the drive frequency.

Piezoelectric actuator control apparatus

Abstract: Disclosed herein are a piezoelectric actuator control apparatus comprising a capacitor connected in series with a piezoelectric actuator that has electrodes, and a control device that controls the voltage applied to the piezoelectric actuator such that the voltage of the capacitor will reach a predetermined value, as well as a piezoelectric actuator control apparatus comprising an integrating circuit connected to one electrode of a piezoelectric actuator that has electrodes, and a control device that controls the voltage of the other electrode of the piezoelectric actuator such that the output of the integration circuit will assume a predetermined magnitude.

Piezoelectric brake device

Abstract: A brake device for producing a braking force by pressing a friction member against a member to be braked in response to a deformation produced by applying a DC voltage to a piezoelectric element array including a stack of piezoelectric elements. A plurality of piezoelectic element arrays are coupled by a displacement transmission mechanism such that deformations produced by the piezoelectric element arrays are added together.

Energy-trapping-type piezoelectric resonance device

Abstract: An energy trapping type piezoelectric resonance device utilizing the mode of thickness extensional vibration comprises a plate-shaped body of a piezoelectric material and three or more electrodes provided to be opposed to each other through peizoelectric material layers in the direction of thickness of the body. At least one of the electrodes is provided to be smaller in area than the major surfaces of the body, to be capable of energy trapping.

Ultrasonic lithotresis apparatus

Abstract: A large number of piezoelectric elements are arranged in a mosaic pattern on a spherical surface so that ultrasonic waves generated by the elements converge on a single point. The arrangement of the elements constitutes a transducer. With the transducer applied to a subject through a liquid bag filled with water, ultrasonic shock waves from each piezoelectric element are concentrated on a lithotresis object, or a calculus so as to break it. The ultrasonic shock waves are generated by applying driving impulses (voltage) to each piezoelectric element. In order to locate the calculus, the transducer is coupled to an ultrasonic diagnosis apparatus having a mechanical scanning type ultrasonic probe. The piezoelectric elements have resonance frequencies set such that the piezoelectric element positioned at the center of the transducer has the lowest resonance frequency and the resonance frequency of each piezoelectric element is increased in accordance with its distance from the center. Thus, the frequency range of vibration of the transducer is broadened so that the ultrasonic shock waves become low in negative sound pressure and narrow in pulse width at the point of convergence.

Piezoelectric fuse for projectile with safe and arm mechanism

Abstract: A piezoelectric fuse, and safe and arm mechanism for a small active projectile is dislcosed including a piezoelectric element mounted within the projectile near the leading end thereof with an impact deformable electrically conductive shell spaced from and at least partially surrounding the piezoelectric element and a resilient material substantially filling the space between the piezoelectric element and the shell. Electrical leads connected the detonator to the shell and to a rearward piezoelectric element contact so that upon projectile impact, the shell deforms compressing the piezoelectric element generating a volatge thereacross, and thereafter, the shell makes electrical connection with a piezoelectric element forward contact actuating the detonator. The safe and arm mechanism includes an interrupter located in a "safe" position between the detonator and a lead charge. The interrupter may move from the safe position only upon both sufficient angular velocity and sufficient linear acceleration of the projectile.

Ultrasonic Motors Using Piezoelectric Ceramic Multi-Mode Vibrators

Abstract: The purpose of this paper is to report development of an ultrasonic motor using piezoelectric ceramic multi-mode vibrators of circular or annular plates, in which degenerate horizontal vibration modes of the same or different form are used. Some constructions of the motor and its experimental characteristics are presented. The ultrasonic motor investigated herein shows special merit in its thin construction.

Piezoelectric motor with multilayer piezoelectric elements

Abstract: The specification discloses a piezoelectric motor which comprises an actuator and a rotor. The actuator includes a frame which has at least three arms extending from the center of the frame in a radial direction so that tip portions of the arms are situated on the same circumference. The actuator further includes multilayer piezoelectric elements formed by stacking a plurality of piezoelectric sections along a stack axis. The elements are placed respectively between adjacent arms in the frame so as to make the adjacent arms symmetrical to each other in regard to a line passing through the center and perpendicular to the stack axis. The rotor is supported in a freely rotatable manner around an axis passing through the center of the frame. The rotor has an inner wall inscribed with the tip portions of the arms and is rotated with a driving force generated on the tip portions when driving voltages having a predetermined phase difference from each other are applied to the multilayer piezoelectric elements.

Brake actuating device

Abstract: A brake device for producing a braking forces by pressing a friction member (2) against a member (1) to be braked in respect to a deformation produced by applying a DC voltage to a piezoelectric element array including a stack of piezoelectric elements, characterized in that a plurality of piezoelectric element arrays (61,62) are coupled by a displacement transmission mechanism (12) such that deformations produced by the piezoelectric element arrays are added together.

Fiber-optic electric field sensor with piezoelectric body sensor

Abstract: A fibre-optic sensor for measuring a particular directional component of an electric field comprises a piezoelectric body (4) and a glass fiber (5a) which is rigidly connected to the piezoelectric body (4) in a given length section. A crystal class and a crystallographic orientation of the piezoelectric body (4) is selected in such a manner that only the directional component which is parallel to a given body axis (h) of the piezoelectric body (4) causes a change in a length of the glass fiber (a) by means of an inverse piezoelectric effect. The change in length is measured interferometrically. In a preferred embodiment, the piezoelectric body has the shape of a disk, of a plate or of a hollow cylinder.

Method of three-phase winding motor control of rotary motor-driven linear actuators, linear motor-actuated carriages, and similar systems, and apparatus for practicing the same

Abstract: A motor controller for a three-phase rotary electric motor driving a leadscrew or linear electric motor actuated carriage or similar device and in which the controller generates periodic waveforms on all three phases that match the back-emf of the motor to enable smooth moving of the carriage with compensation for nonlinearities in motor parameters and carriage stiffness and damping.

Dynamic motor controller

Abstract: A high performance, lightweight and low cost dynamically controlled motor 10 is disclosed wherein the position control of the motor is accomplished by the use of an electronic braking apparatus 20. The dynamically controlled motor 10 of the present invention includes a standard electric motor 15 controlled by the electronic braking apparatus 20. The electric braking apparatus 20 includes a piezoelectric transducer 50 which can be activated to provide a braking force to the rotor 35. The rotor 35 is rotated to the desired stopping location, then the electronic braking apparatus 20 is activated by activating the piezoelectric transducer 50. The rotor 35 can thereby be held at the desired position.

Piezo electric motor

Abstract: A piezoelectric motor comprising a movable element having a first flat surface, vibration elements formed by combination of at least one twisting vibration member vibrating in a twisting manner and at least one piezoelectric element acting to vibrate the twisting vibration member. The vibration elements have a second flat surface adapted to abut against the first flat surface so that the movable element can be driven by surface contact between the first flat surface and the second flat surface.

Piezoelectric motor having a pivotally mounted annular shaped housing

Abstract: A piezoelectric motor for rotating a shaft formed of a hard material and having a general circular cross-section which drives a load having preselected torque characteristics and a known frictional force which opposes rotation of the shaft and load is shown. The piezoelectric motor includes a piezoelectric translation apparatus which is operatively coupled to the shaft for producing incremental angular rotation thereof. The piezoelectric translation apparatus includes a base plate, an annular-shaped housing and a support pin which passes through an aperture in the housing enabling the support pin to pivotally attach the housing onto the base plate. The piezoelectric translation apparatus further includes a piezoelectric driver assembly having an engaging member, at least one piezoelectric driving element and a compliance means. A control circuit for selectively applying electrical signals to the piezoelectric driving element for expanding and contracting the same is shown. The piezoelectric driving element is responsive the electric signals for applying a driving force on the shaft through the engaging member wherein the driving force applied to the shaft is reacted to the housing against the restoring force applied on the housing by the compliance means.

Sensor for the detection of kinetic energy, especially piezoelectric sensor for the detection of dynamic or kinetic energy

Abstract: A piezoelectric sensor having parallel connection of the piezoelectric elements of the piezoelectric membrane of bimorphic construction, by means of which an influence of differences of the electrical characteristics such as, for example, temperature-dependent characteristics of the piezoelectric elements, electrostatic capacitance differences and insulation resistance differences are suppressed, so that, by means of the parallel connection of the piezoelectric elements, the level of the disturbance components which depends on a temperature fluctuation is reduced to half the level which occurs in a traditional sensor in which the piezoelectric elements are connected in series.

Compact micromotion translator

Abstract: The translation device includes first and second plates, one movable relative to the other in response to a plurality of piezoelectric transducers. A flexure is located between the first and second plates and attached to each of them to spring-load the piezoelectric transducers. The driver circuit produces voltages which are balanced and applied to the piezoelectric transducers to produce tilt-free translation of the first plate relative to the second.

End effector actuation with a solid state motor

Abstract: An actuator technology program is in progress to develop miniature motors, joints, and links suitable for modular placement in structures approaching the human hand in size, dexterity and weight. The end-effector device described is a small gripper with tweezer action. This is a first step in a program which will evolve from basic precision miniature grippers to more sophisticated and dextrous multi-jointed end effectors. The gripper can hold objects up to 0.5 in. wide, and it is intended for a circuit-board-level scale of operation. The jaw motor is piezoelectric and works by resonance operation in the longitudinal vibration mode to move a slide plate in a linear fashion. The slide plate is coupled to a mechanism in a 0.5 in./sup 3/-volume housing which converts the linear slide motion to lateral jaw action. The motion will eventually be controlled by linear encoders for position control and one or more strain gages to develop a force servo controller. Motor performance, modeling, and the smaller gripper are described. >

Servo valve with piezoelectric activation as well as piezoelectric control motor

Abstract: Piezoelectric control motor, in particular for the activation in a servo valve, with a piezoelectric element which can be activated by an electric control signal and has a hydrostatic transmission device for the transmission of the movement of the piezoelectric element for preferably acting directly on the hydraulic piston of the servo valve.

Speed controller for piezoelectric motor

Abstract: PURPOSE:To increase the efficiency of a piezoelectric motor in a high speed range and to accurately stabilize the motor in a low speed range by intermittently applying an alternating voltage at the time of operating it at a low speed, and continuously applying the voltage at the time of operating it at a high speed. CONSTITUTION:The voltage of a resonance frequency of a system which includes a piezoelectric element 2 is output from an oscillator 3, and applied through a switching element 4 and a power amplifier 5 to a piezoelectric motor 1. The element 4 intermittently passes an alternating voltage base on the outputs from a low speed motor circuit 9 and a drive pulse generator 10 at the time of operating the motor 1 at a low speed, and continuously passes the voltage based on the output from a high speed mode circuit 8 at the time of operating the motor 1 at a high speed.

Ultrasonic linear motors using piezoelectric actuators

Abstract: A new type of linear motor using a piezoelectric actuator has been developed in which a mechanically resonating part slides on a stationary rail. The slider consists of two bimorphs, or a multilayered piezoelectric actuator with a bonded elastic vibratory fork. The key to obtaining a smooth movement is to realize a slight deviation in the resonance frequency of each leg of the fork so that the moving direction can be controlled by changing the drive frequency.

Ultrasonic oscillator and driver having this oscillator

Abstract: PURPOSE: To oscillate an upper pedestal in any direction by controlling the synthesization of generated oscillation with a platelike piezoelectric laminate body and piezoelectric elements provided there. CONSTITUTION: An oscillator 20 is composed of a piezoelectric laminate member 25 laminated in numerous pieces of platelike piezoelectric elements 21, a piezoelectric element 22, an upper pedestal 23 and a bottom pedestal 24. This piezoelectric elements 21 are laminated into a piezoelectric laminate member 25 so that the direction of polarization may alternately be opposite. The upper pedestal 23 is made of metal, etc., and adhered to the upper surface of the piezoelectric laminate member 25. In the center of the upper surface of the upper pedestal 23 a dome-shaped projection 26 is provided. A piezoelectric laminate body is thus composed of this piezoelectric laminate member 25, the upper pedestal 23 and the bottom pedestal 24. In this way, when the piezoelectric laminate body and the piezoelectric element 22 fitted to it are oscillated, the generated oscillations in longitudinal and transverse directions are synthesized and its synthesized condition is controlled. As a result, the material point on the oscillator performs an elliptical oscillation or a tilting reciprocating oscillation of arbitrary size and aspect and the movable member moves in the specified direction. COPYRIGHT: (C)1990,JPO&Japio

Measuring instrument for contact load

Abstract: PURPOSE:To measure with high accuracy and high efficiency by providing an ultrasonic transmitter and an ultrasonic receiver respectively on the contact part of two adjacent objects. CONSTITUTION:A piezoelectric exciter 1 is mounted on a metal part 2 at the end of a block drum 012 for a printing machine. The ultrasonic wave 4 is generated by this piezoelectric exciter 1 furnished with an input from a signal generator 3. The ultrasonic wave 4 generated from the piezoelectric exciter 1 is received by a piezoelectric sensor 5 which is mounted on the metal part 6 at the end of a press drum 013. An output from this piezoelectric sensor 5 is supplied to an indicator 9 through an amplifier 7 and a filter 8. A contact load between the press drums 012 and 013 can be estimated by an indication on the indicator 9.

Accelerometer for blast monitoring

Abstract: An accelerometer for blast monitoring comprises at least one piezoelectric transducer having a piezoelectric membrane attached along the edge thereof to the sidewall of a suitable container and mounted for free movement in such container for generating a high impedance electrical output signal upon deformation of the piezoelectric membrance by vibration during a blast, a high to low impedance converter connected to the piezoelectric membrane for converting the high output impedance of the piezoelectric membrane into a low impedance signal for transmission through long cables to recording equipment, and means for encapsulating the piezoelectric transducer and converter into epoxy or other solid material to minimize response of the transducer to surrounding acoustic signals.

Method of driving piezoelectric motor, piezoelectric motor and head driver for disk storage device

Abstract: PURPOSE: To conduct stable fine displacement even by the use of very small voltage, and to improve the accuracy of final positioning by applying DC voltage having mutually reversed polarity to a pair of piezoelectric elements. CONSTITUTION: When AC voltage having phase difference is applied to a pair of piezoelectric elements 2, 3 of a piezoelectric driving unit 1, a driver 6 conducts an elliptic periphery motion, and a body to be driven 7 can be displaced and driven. When DC voltage having mutually reversed polarity is applied to a pair of the piezoelectric elements 2, 3, on the other hand, fine drive is enabled. Accordingly, the body to be driven 7 is displaced and driven largely by AC drive at the time of normalcy, and AC drive is changed over to DC drive at the time of final positioning, thus improving the accuracy of positioning. COPYRIGHT: (C)1990,JPO&Japio

Manufacture of piezoelectric actuator

Abstract: PURPOSE:To form the area of expansion and contraction oscillation correctly, by a method wherein the piezoelectric sheet is polarized in each neighboring first electrode area located before (after) bonding the piezoelectric sheet and a conductive elastic body, thereafter, the piezoelectric sheet is separated between electrodes CONSTITUTION:A cushion sheet 29 is laid on a stator stand 37, supporting a rotary shaft 35 rotatably, then, a piezoelectric actuator, made by bonding a piezoelectric oscillating piece 25 and a conductive elastic sheet 20, is attached onto the sheet 29 to form a stator while an annular slider 41 is superposed and the slider is fixed to the rotary shaft 35 to form a rotor, whereby a piezoelectric motor is constituted In the piezoelectric actuator, split electrodes 13, 17 are arranged on the conductive elastic sheet 29 with predetermined correct positional relation by a method wherein the elastic sheet 29 is bonded to the piezoelectric oscillating piece 25 and, thereafter, a piezoelectric sheet 11 is cut and separated into every individual split electrodes 13, 17 As a result, troublesome process is unnecessary and the manufacture of the piezoelectric actuator is simplified