Showing papers on "Piezoelectric motor published in 1991"

Piezoelectric ink jet printer head

Abstract: In a piezoelectric ink jet printer head having a laminated piezoelectric layer, actuating voltage is applied between only electrodes corresponding to a selected jetting device. A part of the piezoelectric ceramic layers between the electrodes is deformed in accordance with a slip effect, to jet ink from the selected jetting device. Since the polarization direction of the piezoelectric ceramic layers is almost perfectly perpendicular to the direction of an actuating electric field, the actuating voltage can be reduced. Further, piezoelectric ceramic layers can be stacked to obtain the necessary strength of a laminated piezoelectric element without decreasing the displacement amount. Thus, the reliability of the laminated piezoelectric element is enhanced. Moreover, the insulation of the electrodes is not deteriorated by a short circuit, migration of silver or the like. Such properties as durability and moisture resistance are also enhanced. Therefore, the printer head of the invention requires no components for preventing the deterioration of the insulation needed for prior art printer heads. The printer head can be thus made compact and lightweight, reducing the manufacturing cost.

Piezoelectric shock wave generator

Abstract: A piezoelectric shock wave generator for use in medical equipment includes a plurality of piezoelectric elements being electrically interconnected to operate in parallel and mounted on a common carrier of curved configuration; a coupler medium couples shock waves as generated by these piezoelectric generators into the body of a living being, the improvement includes electrical insulation between the piezoelements being in fluid, ie liquid or gaseous state, in that each piezoelectric element is surrounded by the fluid in any direction towards any other piezoelectric element; the front ends of the piezoelectric elements may be physically separated, so that the coupler fluid and the isolating fluid are the same, and having a common flow space; alternatively, a membrane in front of all said piezoelectric elements provides electrical interconnection between them and physically separates the isolating fluid from the coupler liquid

Dynamic behavior of a piezoelectric beam

Abstract: A piezoelectric vibration can be characterized by the components of its electric equivalent. The dynamic nature of these components, as well as their dependence on the location of the electrodes on a piezoelectric structure, is studied in this article. General equations, based on a decomposition of a known vibration into its eigenmodes, are derived for a flexural vibration. A correction factor for the dynamic and geometric properties of the equivalent components is derived. The mechanical compliance of the beam is shown to depend on the choice of electrode configuration. The behavior far from resonance is also studied. It has been assumed that the mechanical and the piezoelectric properties can be treated as two quasiseparate problems.

Pre-loaded actuator using piezoelectric element

Abstract: Pre-loaded piezoelectric actuators provide improved work piece displacement, frequency of repetition, accuracy and repeatability. Actuators may use a coil spring providing a compressive force adequate to substantially fully compress a laminated piezoelectric element on a non-destructive basis. Upon activation, a pre-loaded actuator delivers a full workpiece drive stroke because piezoelectric element axial compression has previously occurred. Pre-loading methods and pre-loading to damp out element oscillation are also disclosed.

Micro-step XY-stage using piezoelectric tube actuator

Abstract: A novel small and simple mu m-order-step XY-stage has been developed. It consists of a cylindrical piezoelectric actuator fixed at one end to a baseplate, with one electrode inside the tube and two pairs of diametrical electrodes on the outside. A support is attached to the free end. The actuator is powered by a single cosine waveform voltage by friction force. An analysis shows that the trajectory of the substance is determined by the parameter gamma = alpha omega /sup 2//( mu g), which has no relation to its weight, where alpha is the amplitude of the support stroke, omega is the angular frequency of the single wave, mu is the friction coefficient, and g is the gravity. The final displacement of the substance has its maximum at x/sub 5//(2 alpha )=0.626 when gamma =3.76. The actuator drives the substance on the support two-dimensionally. The stroke and direction of movement are controlled with a joystick. >

Design of a piezoelectric exciter/actuator for micro-displacement control: theory and experiment

Abstract: High-precision and high-speed machine operation is very much in demand in modern manufacturing industry. However, mechanical vibrations introduced by various sources can easily disrupt this operation. Thus, vibration isolation and control have become very important in high-precision machine operation. This paper presents an active micro-position control technique using a piezoelectric actuator. A general theory for a piezoelectric actuator subjected to mechanical excitations and feedback voltages is developed. Piezoelectric excitation induced by the converse piezoelectric effect via direct voltage injection is first studied. Then, this electromechanical phenomenon is applied to an active micro-position control by injecting a processed feedback voltage at variable feedback gains into the piezoelectric actuator counteracting the external excitation. The effectiveness of the piezoelectric micro-position attenuation is evaluated analytically and experimentally. The theoretical solutions are compared favourably with the laboratory experimental data.

Method and apparatus for machining a non-circular workpiece

Abstract: An apparatus for machining a non-circular workpiece wherein a tool is moved by a composite movement given by a linear motor and a piezoelectric actuator. The linear motor is driven by the numerical controller in accordance with the low frequency components of profile data defining a position change of the tool with respect to angular position change of the spindle, while the piezoelectric actuator is driven by the numerical controller in accordance with the high frequency components of the profile data. Further, a positioning error of the tool due to reaction force generated by the piezoelectric actuator is detected by the numerical controller to compensate the high frequency components for the detected positioning error.

Development of piezoelectric cycloid motor

Abstract: The paper proposes a piezoelectric cycloid motor, in which the cycloid gear mechanism is used to convert the expansion and contraction of the piezoelectric actuators into the rotational motion of the motor. Making a prototype of the output characteristics of a prototype were investigated experimentally. The results obtained are as follows. (1) The proposed rotational principle was effective. (2) The measured rotational speed compared well with the values calculated. (3) The maximum output torque was 0.014 Nm for all the rotational speeds; it was 78 percent of the calculated value. The motor rotated steadily and kept its rotational speed for all the rotational speeds even when the load was increased up to its maximum value. (4) The efficiency increased as the rotational speed and the output torque increased, and reached the highest value, 25.5 percent, at 16 r.p.m. within the measuring range of driving frequency. >

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 transformer using single crystal of linbo3

Abstract: A piezoelectric transformer includes a substrate of piezoelectric material, preferably a single crystal of LiNbO 3 . The substrate is uniformly polarized in a selected direction thereof and vibrated in a direction of the length thereof. An input voltage is applied across both sides of a portion of the substrate in a direction of the thickness thereof and thus excites a vibration by way of piezoelectric effect. Thereby another voltage is caused in the direction of the thickness of the substrate in a portion other than the portion to which the input voltage is applied, and taken out as an output voltage. As a result, it is possible to decrease the output impedance to obtain a large load current and thus fully heighten a step-up ratio of the piezoelectric transformer.

Ultrasonic motor utilizing elastic fin rotor

Abstract: A new ultrasonic micromotor, which consists of an ultrasonic vibrator and a rotor with elastic fins, is proposed. The fins convert the ultrasonic vibration into the driving force. A motor, 5 mm in diameter, was fabricated and worked quite well, and its characteristics were also measured. To estimate the specifications of the motor, numerical analysis based on fundamental models of the elastic fin were successfully carried out. The simple structure of this motor suggests the possibility of further miniaturization of the motor. >

Ultrasonic motor driving circuit

Abstract: A driving circuit for an ultrasonic motor is disclosed which utilizes a single transformer. A phase shifter frequency-divides the signal from an oscillator by N and generates a plurality of frequency divide signals having different phases. These divided signals are then used to control the driving of the piezoelectric element used to power the ultrasonic motor.

Piezoelectric modular motor with stator having two active faces - has both faces excited by transducers having two active faces insulated by coaxial element

Abstract: The piezoelectric motor has a stator part (1) having two annular parts (4,5) excited by piezoelectric transducers with two active faces (7,6) which are respectively insulated by a coaxial insulation element (9). The rotor (2) has two annular parts (14,16) arranged symmetrically with respect to the median plane (3). The piezoelectric transducers are constituted by a number of parts which are cut out in a film of piezoelectric material. USE/ADVANTAGE - Motor has improved symmetry which optimises piezoelectric effects produced which makes it suitable for use in medical micro-mechanics.

Linear motion microactuators using piezoelectric thin films

Abstract: Two novel types of microactuators for linear displacements are presented which use piezoelectric thin films for the electrical-to-mechanical energy process. One actuator uses a folded path or meander line geometry to produce tethered linear displacements. The other actuator uses an inertial recoil mechanism in conjunction with an electrostatic clamp to produce incremental stepping motion. Sufficient repetition of the stepping sequence produces virtually unlimited travel range, being limited by practical considerations such as electrical connections. Electromechanical models for both actuators are developed and are used to quantitatively estimate the performance of actuators designed to a particular set of dimensions. Fabrication procedures for making both microactuators have been developed, and the status of the fabrication efforts is presented. >

Direct current traveling wave motor

Abstract: A direct current traveling wave motor generates motive force by utilizing shear deformation resulting from electrical contact between a rolling element and a layer of material that experiences shear deformation in response to an applied electric field. In a rotary piezoelectric embodiment, rotation of a motor shaft results from the non-uniform electric field intensity around the contacts between rollers surrounding the shaft and an outer race of piezoelectric material that undergoes shear deformation. Rotation occurs as the rollers roll down the faces of piezoelectric shear waves that travel with the rollers. The rollers perform the function of commutators, but without sliding friction, and they eliminate the need for traditional roller bearings. Zero clearance between motor parts results in shaft stiffness that allows precise positioning and high speed operation. The piezoelectric motor has high efficiency because sliding friction is eliminated, eddy currents are not generated, and most of the internally flowing current is local and reactive. Efficiency of the motor exceeds 98%, and its silent, smooth operation is capable of very high speeds. Speed of the motor is controlled by varying the DC potential. The motor may be operated by a battery, it does not require lubrication, and it will operate while flooded with slightly conducting fluids, such as salt water. The scale of the motor can range from miniature for driving a watch to very large for driving an oceangoing ship.

A Small-Size Ultrasonic Linear Motor

Abstract: A new structure for an ultrasonic linear motor using piezoelectric actuators has been developed. The ultrasonic vibrator consists of a metal bar with two legs. The direction of the slider's movement is controlled by changing the polarity of the drive voltage of the multilayered piezoelectric actuator. Typical performance characteristics of the linear motor are a velocity of 1 m/s and a static thrust of 100 gf.

Driving and Controlling of a Watch Device Ultrasonic Motor by Two Phase Pulse Signals

Abstract: A drive and control system of a light-load ultrasonic motor for a watch device is described. The ultrasonic motor is driven with two phase pulse signals having π/2 phase differences and 50% duty cycles. An angular displacement is detected by a rotary encoder and a rotor moves a 6 deg. step per second. The experimental results using the system have proved that the light-load ultrasonic motor can be used as a stable stepping motor for a watch device.

Tunable transducers as smart materials

Abstract: A solid-state tunable transducer has been developed by incorporating an elastically nonlinear material, silicone rubber, into an electroacoustic transducer made from piezoelectric ceramics. The resonant frequency and mechanical Q of the transducer are tuned mechanically by applying a uniaxial compressive stress to the composite. The resonant frequency is tuned electrically by placing a piezoelectric actuator into the composite and varying the magnitude of the DC bias. >

Piezoelectric element driving controller

Abstract: PURPOSE: To provide a piezoelectric element driving controller which controls the amount and speed of deformation of a piezoelectric element without detecting them. CONSTITUTION: A control device includes a piezoelectric element 2, a high- voltage source 1 for driving the piezoelectric element 2, a memory 5 which stores correspondence information between an output from the high voltage source 1 and a deformation amount of the piezoelectric element 2, a control part 4 for controlling the output voltage for driving the piezoelectric element 2 on the basis of the information read from the memory, and a driving voltage generating part 3 for converting the voltage of the high voltage source 1 into a driving voltage for the piezoelectric element 2. COPYRIGHT: (C)1992,JPO&Japio

A fast electro-mechanical clutch element using a piezoelectric multilayer actuator

Abstract: The mechanism described in the paper is one design in a series of monolithically constructed devices designed around flexure hinges. It generates a 30 Newton stall force, with an unrestrained movement of over 110 mu m, derived from a piezoelectric device which only extends by 15 mu m. Although the device cannot be considered as highly efficient, it transforms the output movement up to a level which can be used directly with components produced to moderate degrees of surface finish. The paper describes a prototype device whose purpose is to rapidly clutch a thin metal strip. The paper details the device and shows performance data including speed of response, electrical clutching energy and mechanical performance. The efficient displacement amplification of piezoelectric devices is seen as a gateway to many differing applications, currently dominated by the solenoid. Many potential applications exist in the field of robot actuation.

Multi-degree-of motion freedom ultrasonic piezoelectric actuator

Abstract: Two prototypes of two-degree-of motion freedom ultrasonic piezoelectric actuators as well as linear actuators were constructed. Their fundamental characteristics were measured. Several three-degree-of motion freedom actuators are proposed. >

Driving method of piezoelectric bimorph element and piezoelectric bimorph element

Abstract: PURPOSE:To obtain the large amount of displacement by a method wherein a larger electric field is applied to a piezoelectric bimorph element to drive the element utilizing that in the case an electric field of the intensity of an electric field, which is applied to individual piezoelectric material layers, is applied in the polarization direction and the opposite direction to the polarization direction, the applying electric field is distributed small. CONSTITUTION:When the thickness of a piezoelectric ceramic layer 2 on one side of piezoelectric ceramic layers 2 and 3 is assumed (t1), the coercive field intensity of a piezoelectric material constituting the layer 2 is assumed Ec, the minimum of the product EcXt1=Vc of the thickness (t1) and the intensity Ec is assumed V1, the thickness of the other piezoelectric ceramic layer 3 is assumed (t2), the coercive filed intensity of a piezoelectric material constituting the layer 3 is assumed Ec and the minimum of the product EcXt2=Vc of the thickness (t2) and the intensity Ec is assumed V2, a voltage of V1+V2 or higher is applied to a piezoelectric bimorph element 1. Thereby, the large amount of displacement can be obtained.

Method of producing a displacement device.

Abstract: A device for magnifying displacement of a piezoelectric element (1) at a printing head is proposed. The displacement of the column shape piezoelectric element (1) due to applied voltage is transmitted to a contact member (5) and is magnified via a displacement magnifying mechanism (6, 7, 8, 10) to drive a printing wire (11) connected to the displacement magnifying mechanism. A temperature compensating member (12) is disposed between a frame (3) supporting the piezoelectric element (1) and the piezoelectric element (1) and/or between the contact member (5) and the piezoelectric element (1), and gives a preload to the piezoelectric element (1) to fixingly support the piezoelectric element (1) between the frame (2, 3) and the contact member (5). The temperature compensating member is plastically deformed to compensate for the deformation of the piezoelectric element (1) due to the temperature change.

Appts. for measurement of force effect in mechanically loader machine part - involves piezoelectric converter fitted in hole of machine part and set in oscillation, the alterations of which are moulded

Abstract: Using the reciprocal effect of a first piezoelectric converter set in oscillation, the oscillation alterations produced by the force effects are measured. This measurement is done by means of a 2nd piezoelectric converter placed in contact with the 1st and as voltage alteration. The oscillation alteration is measured as amplitude and/or frequency alteration, and the 1st piezoelectric convertor is set in resonance oscillation. The piezoelectric converters are of quartz, a titanate, partic. lead zirconate or barium titanate or a beta-polyvinylidene fluoride. The 1st piezoelectric convertor is connected to a regulatable voltage source and is in contact with the 2nd such convertor which is connected to a voltage measurement appts. USE/ADVANTAGE - Used to measure force effect in a mechanically loaded machine part by measuring static signals with piezoelectric convertors without having to take into consideration drive conditions which tend to falsify the measurement values.

Piezoelectric resonator and its production

Abstract: PURPOSE: To realize the small sized piezoelectric resonator in which spurious vibration based on spread vibration mode is hardly caused in the case of the piezoelectric resonator utilizing the vibration mode for a vibrated apex having a resonance point at a lower frequency band than that of the spread vibration mode. CONSTITUTION: A component reducing the piezoelectricity is diffused from at least one major side of a square piezoelectric plate A to an area in the vicinity of a center of the square piezoelectric plate of a piezoelectric resonator 17. Polarization is applied so that the direction of polarization oaf four areas 7-10 partitioned by two diagonal lines 6a, 6b of the square is opposite in the broadwise direction among adjacent areas. A couple of resonance electrodes 15, 16 are formed to both the entire major sides of the piezoelectric plate A. COPYRIGHT: (C)1993,JPO&Japio

Dynamic characteristic and control of a high-polymar piezoelectric actuator.

Abstract: A new simple method for controlling end point motions of a high-polymar piezoelectric actuator is presented. The method aims at controlling tip motion by directly computing the input voltage. A numerical inversion of Laplace transform is used to obtain the results in the time domain. The results show the effectiveness of the method for the control of a high-polymar piezoelectric actuator.

Cylindrical piezoelectric ceramics and laminated piezoelectric motor

Abstract: PURPOSE:To obtain a low voltage drive cylindrical piezoelectric ceramics and piezoelectric motor, which can be assembled easily, by connecting each unit of a plurality of split electrodes at a first inner electrode section to a common external electrode, and connecting every other layer of continuous electrodes at a second inner electrode section to a second common external electrode. CONSTITUTION:Every unit of first inner electrodes 2-2 is connected to a first common external electrode, and two of the first external electrodes are grouped at the splitting position of the first inner electrode 2-2 thus providing three terminals. Second inner electrode 2-3 is connected to a second common external electrode for every other inner electrode layer 1-2, and voltages are applied on the first and second external electrodes while shifting sequentially. By such arrangement, low voltage drive cylindrical piezoelectric ceramics and piezoelectric motor, which can be assembled easily, can be obtained.