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Patent

Magnetostrictive linear displacement transmitter having improved piezoelectric sensor

TL;DR: An improved magnetostrictive wire based position transducer that has applications in both liquid level measuring systems and in position indicating systems is presented in this article, where a cylindrically structured and circularly polarized piezoelectric element directly measures the torsional acoustic waves in the magnetostriction wire as they are received by the sensor.
Abstract: An improved magnetostrictive wire based position transducer that has applications in both liquid level measuring systems and in position indicating systems. A cylindrically structured and circularly polarized piezoelectric element directly measures the torsional acoustic waves in the magnetostrictive wire as they are received by the sensor. The cylindrical structure of the sensor eliminates many of the inadvertently detected acoustic and electrical pulses within the wire that are not indicative of the passage of the torsional wave of concern. The present system provides an improved sensor configuration which is selectively sensitive to torsional waves while being insensitive to vibrations in alternate planes. This improved piezoelectric sensor in combination with the electrical configuration allows placement of the magnetostrictive wire apart from the liquid whose level is being measured or from the indicator whose position is of concern. The system provides a means for transmitting the liquid level within a container to a sensor column outside of the container in a manner that improves access, maintenance, calibration, and installation. In the preferred embodiment, each of the above improvements is provided in a system that incorporates an instrumentation loop powered microprocessor based transmitter with low current requirements and increased sensitivity.
Citations
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Patent
02 Jun 2000
TL;DR: In this article, a position feedback system is used to determine the position of movable elements on a path and control the movable element on the path and the programmable controller using positional information from the sensors.
Abstract: The present invention is directed to a machine with a position feedback system and a method for use thereof. The machine includes at least one movable element mounted for movement on a path and at least one programmable controller. The machine further includes at least two absolute or magnetostrictive sensors or the machine includes an absolute sensor and a non-absolute sensor. The programmable controller uses positional information from the sensors to determine the position of the movable elements on the path and control the movable elements. The method includes determining a known position for the movable elements, linking at least two magnetostrictive sensors into one virtual sensor, and/or performing commutation alignment for the movable elements. Determining the position and commutation alignment can occur when the movable elements are stationary or moving.

379 citations

Patent
02 Apr 1998
TL;DR: In this article, a disposable sensor is disclosed for non-invasively detecting and characterizing a container's contents by generating microwave frequency signals, electromagnetic fields are produced by a sensor and penetrate a container.
Abstract: A disposable sensor is disclosed for non-invasively detecting and characterizing a container's contents. By generating microwave frequency signals, electromagnetic fields are produced by a sensor and penetrate a container. The EM fields are analyzed in regards to how they are perturbed by the container contents. Analysis of the perturbed EM fields enables determination of content level, content purity, content density, content temperature, container pressure, and content conductivity.

86 citations

Patent
05 Aug 1996
TL;DR: A disposable fluid level sensor is disclosed for determining the level of fluid in a container (12), a flex circuit sensor is coupled to a processing module having a power supply, the sensor being mounted at a selectable location by an adhesive patch which holds the sensor flush against the container.
Abstract: A disposable fluid level sensor is disclosed for determining the level of fluid in a container (12). A flex circuit sensor (16) is coupled to a processing module (20) having a power supply, the flex circuit sensor being mounted at a selectable location by an adhesive patch which holds the sensor flush against the container. The processing module hangs from the flex circuit, and provides a human perceptible indication, such as a flashing light (32) or an audible alarm (34), when the fluid level drops below a desired point as determined by the sensor. The sensor detects the change in fluid level by transmitting an electromagnetic signal and determining whether there is a change in reflected energy.

48 citations

Patent
20 Jul 2007
TL;DR: A rotational, shear mode, piezoelectric motor is integrated with a suspension, head or head gimbal assembly (HGA) into a collocated, rotational and shear model for high frequency, high resolution track positioning of the read/write element.
Abstract: A rotational, shear mode, piezoelectric motor is integrated with a suspension, head or head gimbal assembly (HGA) into a collocated, rotational, shear mode, piezoelectric micro-actuated suspension, head or head gimbal assembly (HGA) for use in disk drives and disk drive manufacturing equipment. When excited by a control voltage, the collocated, shear mode, piezoelectric micro-actuated HGA rotates the head enabling high frequency, high resolution track positioning of the read/write element. The motor is integrated with the head and flexure (collocation). The head rotates about a rotation axis that is ideally located at the center of mass of the head. A shear mode piezoelectric motor rotates the head. A collocated, rotational, shear mode, piezoelectric micro-actuated HGA has high stiffness, high frequency response, high positioning resolution, low mass and low internal vibration for improved tracking, increased track density and greater disk drive storage capacity. Furthermore, its solid integration improves shock resistance and reduces micro-contamination.

37 citations

Patent
02 Apr 1997
TL;DR: In this article, a disposable fluid level sensor is configured for determining the level of fluid in a container, coupled to a processing module having a power supply, the flex circuit being mounted at a selectable location by an adhesive patch which holds the sensor flush against the container.
Abstract: A disposable fluid level sensor is configured for determining the level of fluid in a container. A flex circuit or other electromagnetic sensor is coupled to a processing module having a power supply, the flex circuit being mounted at a selectable location by an adhesive patch which holds the sensor flush against the container. The processing module hangs from the sensor's antenna, and provides a human perceptible indication, such as a flashing light or an audible alarm, when the fluid level drops below a desired point as determined by the sensor. The sensor detects the change in fluid level by transmitting an electromagnetic signal and determining whether there is a change in reflected or resonated energy.

30 citations

References
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Patent
19 Dec 1973
TL;DR: In this paper, a linear distance measuring device is disclosed in which the time it takes a torsion pulse to traverse a sonic waveguide from a movable magnet to a pulse responsive element is determined and converted to a measurement of the distance from the movable magnets to the pulse responsive elements.
Abstract: A linear distance measuring device is disclosed in which the time it takes a torsion pulse to traverse a sonic waveguide from a movable magnet to a pulse responsive element is determined and converted to a measurement of the distance from the movable magnet to the pulse responsive element The position of the magnet, which is moved by an external means such as a machine tool element, can thus be determined precisely

153 citations

Patent
03 Nov 1975
TL;DR: In this paper, a magnetic field generator is mounted on a movable member and an elongated ferromagnetic member is positioned adjacent and parallel to the path of movement of the member.
Abstract: The position of a movable member is measured without the establishment of physical contact with such member. A magnetic field generator, which provides a localized field of special geometry, is mounted on the movable member and an elongated ferromagnetic member is positioned adjacent and parallel to the path of movement of the member. The magnetic field will produce a change in the Young's modulus of elasticity in an adjacent region of the ferromagnetic member and sonic strain pulses launched along the ferromagnetic member will be partly reflected from this region of Young's modulus discontinuity. The time required for a strain pulse to travel from a given point on the ferromagnetic member to the region of Young's modulus discontinuity and be partially reflected therefrom and returned to a known detection point will provide a measure of the position of the field generator along the elongated ferromagnetic member.

75 citations

Patent
24 Sep 1987
TL;DR: In this paper, a magnetostrictive wire is used to measure liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.
Abstract: A liquid level detector of the type in which a magnetostrictive wire extends through the liquid level measurement range and is captured in a tensioned vertical orientation within a stainless steel tube. Liquid level is measured as a function of the time required for a torsional disturbance imparted the wire near the top to travel along the wire to a magnet which is contained within a liquid level float which slides up and down along the tube. The torsional disturbances imparted to the wire by means of a piezoelectric crystal to which the wire is easily clamped. Accuracy is enhanced by measuring liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.

55 citations

Patent
29 Jan 1968

53 citations

Patent
03 Apr 1989
TL;DR: In this article, a magnetostrictive wire is used to measure liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.
Abstract: A liquid level detector of the type in which a magnetostrictive wire extends through the liquid level measurement range and is captured in a tensioned vertical orientation within a stainless steel tube. Liquid level is measured as a function of the time required for a torsional disturbance imparted the wire near the top to travel along the wire to a magnet which is contained within a liquid level float which slides up and down along the tube. The torsional disturbances imparted to the wire by means of a piezoelectric crystal to which the wire is easily clamped. Accuracy is enhanced by measuring liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.

45 citations