Showing papers on "Piezoelectric motor published in 1982"

Improving the linearity of piezoelectric ceramic actuators

Abstract: It is shown that the linearity of a piezoelectric ceramic actuator may be greatly improved if the applied electric charge, rather than the applied voltage, is varied to control the extension. Hysteresis is virtually eliminated.

Piezoelectric motor with two part rotor

Abstract: A piezoelectric motor of the invention comprises a stator and a rotor one of which includes at least one first piezoelectric oscillator. The rotor consists of a first and a second parts one of which parts includes a second piezoelectric oscillator. Said parts of the rotor are mounted for relative rotation about the axis of rotation. The first part is in contact with the stator along the first surface of frictional interaction and with the second part along the second surface of frictional interaction. Each surface of frictional interaction is formed by rotation of at least one straight line length about the axis of rotation of the rotor.

Electric motor controls for mechanical actuators

Abstract: Methods and apparatus for controlling an electric motor effect operation of such motor by electric energization thereof, and derive from a motor winding or from the back electromotive force of the motor an electric signal indicative of motor speed. The motor is thereupon mechanically stalled, and such stalling is detected from a comparison of the derived speed signal and the electric energization. Deenergization of the motor is effected in response to the stalling detected from the latter comparison. Limit switching of electric motors and actuators without limit switches may be provided in this manner.

Piezoelectric pressure sensor

Abstract: A pressure sensor comprising a piezoelectric material formed in a geometry which provides a piezoelectric output signal when subjected to a pressure. The piezoelectric material also has a pyroelectric output signal. The present sensor further comprises conductive contacts having a geometry for enhancing the piezoelectric output signal and for substantially eliminating the pyroelectric output signal.

Ring laser gyroscope

Abstract: A resiliently mounted ring laser gyro is dithered below its resonant frequency with a waveform differing from the sine waveform. This is achieved by a piezoelectric motor formed by several piezoelectric elements in a pile. The motor is acting tangentially on a support for the laser and the support takes the form of a strong biased torsion spring.

Transducer with a piezoelectric sensor element

Abstract: In addition to having at least one piezoelectric sensor element, a transducer is provided with at least one further measuring element, which is influenced by the state variable to be measured in the same way as the piezoelectric sensor element, and has its own signal lead. The additional measuring element may also be a piezoelectric element which may be excited so as to produce mechanical vibrations by utilizing the inverse piezo-effect, the change of the vibration characteristics of the vibration system consisting of the excited piezo-element and its environment serving as a measurement value for a static or quasi-static measurement.

Principle of piezoelectric frequency-tunable transducer

Abstract: Eecently, in our papers[1,2] the effect of electric load on the characteristics of piezoelectric vibration system has been obtained. The resonant frequency of such a system changes continually with the changing of the electric load. In accordance with this effect, we made piezoelectric frequency-tunable transducers. In this paper, the principle of this freqency-tunable piezoelectric transducer is described. We theoretically analyse the piezoelectric frequency-tuning of the sandwich transducers and experimentally investigate a sandwich transducer of length-vibration bar with field parallel to length. The theoretical and experimental results show that such frequency-tuning is available at one and half octaves. For piezoelectric frequency-tunable transducer, the frequency tuning is convenient, continual and instantaneous.

Energy Trapping of Width-Shear Vibrations in Thin Piezoelectric Strips : PIEZOELECTRIC VIBRATOR

Abstract: This paper presents theoretical analyses and experiments of energy trapping of width-shear vibrations in thin piezoelectric strips. By the use of width-shear vibrations, miniaturization of trapped-energy resonators is achieved in the medium-frequency range below several megahertz. The width-shear-mode trapped-energy resonators have some advantages, such as: 1) Excitation electrodes are deposited only on the one side of the plate. 2) The ratio of capacitances of the resonator can widely be varied by the electrode spacing. 3) A specified higher-harmonic mode can easily be suppressed by special electrode arrangement related to stress distribution of the mode. In addition, trapped-energy single-mode filters using the width-shear modes are proposed, and small-sized filters of 455 kHz are constructed.

Improvements in or relating to ultrasonic transducers.

Abstract: An ultrasonic transducer including a plate of piezoelectric material which can be excited to produce ultrasonic vibrations in a medium which is coupled acoustically to the transducer, and means for so exciting the plate of piezoelectric material, wherein the plate of piezoelectric material is divided into elements such that each element has at least one dimension which is considerably smaller than the thickness of the plate of piezoelectric material.