Abstract: A device for measuring the rotation of a rotating element comprising an encoder element rotating with the rotating element and a sensor unit connected to a stationary element. A scraping element cooperates with a surface of the encoder element in order to eliminate contaminating particles present on the surface of the encoder element. The scraping element may be carried on the sensor device and may be biased against the encoder element by an elastic device or by magnetism.

Abstract: An eddy current probe is configured with one axis of the electrical coil elongated to span a much larger distance than that of conventional coils. Thus, a single pass of the elongated coil can inspect a path of up to 100 times wider than the conventional coil. The parts of the eddy current probe include a pair of elongated ferrite cores disposed end-to-end in a housing block. A pair of receive coils are disposed in the housing block respectively surrounding the elongated ferrite cores. A transmit coil is wound around the receive coils in the housing block, and a pair of ferrite shields are disposed in the housing block sandwiching the transmit coil, the pair of receive coils, and the pair of elongated ferrite cores.

Abstract: A detector for a magnetic field having a low frequency compared to background EMF and having a magnitude approximately 1,000 times less than the EMF, the detector comprising: a pickup coil for capturing the magnetic field and the background EMF; an integrator coupled for receiving a signal having respective components representative of the magnetic field and the background EMF, the integrator having a time constant such that successive positive and negative polarity portions of the component representative of the background EMF cancel out one another in the integrator, but the component representative of the magnetic field results in a net output signal from the integrator, the net output signal being indicative of the magnitude of the magnetic field; and, a magnetic field strength output indicator responsive to the net output signal from the integrator, whereby the magnetic field can be detected with great sensitivity notwithstanding the background EMF.

Abstract: An evaluation method for an output signal of a sensing device for scanning a cyclic movement, consisting of a rotatable pole wheel provided with equidistant teeth and an inductive sensor, permits recognition and display of damage to the pole wheel, in particular defective or missing teeth. Contrary to known evaluation processes, where error monitoring of the output signal is carried out for a relatively short time period comprising few signal cycles of the output signal, an observation of the output signal is effected for a sufficiently long time span in the evaluation process according to the invention, such that within the time span, at least two complete revolutions of the pole wheel are completed. To detect damage to the pole wheel, the sudden changes in the output signal occurring in the course of a complete revolution are recorded and are compared with changes recorded in previous, complete revolutions.

Abstract: An apparatus and method for implementing azimuthal capabilities on electromagnetic wave resistivity well logging tools. The apparatus comprises a structurally simple antenna shield positioned around either the transmitting or receiving antennas, or both, positioned on the well logging tool on the drill string. The shields partially surround the tool and provide an electromagnetic barrier for either the transmission or reception of electromagnetic waves, as the case may be. Positioned on the shield are appropriately placed and sized windows through which electromagnetic waves may either be transmitted or received, depending upon the function of the antenna that the shield surrounds. Variations in window dimensions allow optimization of the device for use in conjunction with a variety of formations and a variety of drill mud characteristics.

Abstract: A rotary position sensor having redundant sensing including a base (20) upon which a plurality of radially extending magnetic sensing elements (22) are mounted to form two sets (74, 76) of sensors. Interleaved with the sensing elements (22) are a plurality of uniformly spaced magnetic concentrators (30). The sensor assembly (18) is placed in a uniform magnetic field created, for example, by a flat plate magnet (432) mounted adjacent the sensor assembly, and rotatable relative to it. The relative rotary position of the sensor assembly to the magnetic field is determined by comparing the relative values of the sensor elements (22) in the array to each other. Also, failure of the sensor assembly is determined by comparing the rotary position calculated for the first set 74 to the rotary position calculated for the second set 76.

Abstract: The method and apparatus of the invention determines earth formation resistivity at extended depths into the formation by the use of telemetry transmission signals to measure the formation resistivity. The telemetry transmission signals carry measurement data from downhole sensors through the formation to an uphole receiver. The signal transmission is by means of induction telemetry. At the receiver, the signal is demodulated to obtain the transmitted measurement data. During the detection of the signal at the receiver, the signal amplitude is also extracted and is used to determine the formation resistivity. In addition, changes in the signal amplitude are also used to indicate formation boundaries for determining well location during directional drilling.

Abstract: A pair of elastic strips are provided in order to hold sheet material to be measured in thickness. Each of the elastic strips includes of one or more elastic films. Ends of the elastic strips are supported by support portions, and the other ends of the elastic strips are provided with respective coils, opposed to push each other, and kept in contact with each other. When the sheet material is held between support portions, the inductances of the coils are changed and the thickness of the sheet material is detected as an electric signal representative of the changed inductance.

Abstract: An inductive angle sensor for a motor vehicle has an oscillator circuit that generates a periodic AC oscillator-frequency signal in an exciting coil, at least one receiving coil, an evaluation circuit for detecting the signal induced in the at least one receiving coil, and a movable inductive coupling element that influences a strength of inductive coupling between the exciting coil and the at least one receiving coil. The oscillator circuit is a "soft" or "flexible" oscillator circuit such that when an interference frequency close to the oscillator frequency is coupled into the coil system, the oscillator circuit adapts the oscillator frequency and phase relationship to that of the interference frequency. Undesired overlapping effects are thus efficaciously prevented.

Abstract: A method for determining a relative clay content of at least a portion of a well core taken from a subterranean geologic formation by: determining the relationship of the clay content of the well core portion to the dielectric constant of the well core portion at a selected frequency at relatively few locations over a substantial length of the well core portion by measuring the clay content by a clay determination test such as x-ray diffraction, thin section analysis, sieve analysis or laser particle analysis and the dielectric constant at the locations; and, measuring the dielectric constant of the well core portion at a large plurality of spaced apart other locations on the well core portion at the selected frequency; translating the large plurality of dielectric measurements according to the relationship into relative clay content measurements. The dielectric constant is representative of the water constant of the well core portion, which is related to the clay content of the well core portion.

Abstract: A magnetic field sensor is provided which can be easily downsized and has a capability to detect a magnetic field in the Ghz band with a high space resolution and to reduce a voltage induced by an electric field. The magnetic field sensor is composed of a first layer, a second layer and a third layer. The first layer is provided with a straight-lined conductor pattern disposed in a perpendicular manner to a mid-point of another straight-lined conductor pattern being the longest among J-shaped conductor patterns. The third layer has the same conductor pattern as the first layer. The second layer has a ladle-shaped conductor pattern disposed along the center of the width of the conductor pattern of the first layer and third layer and an L-shaped conductor pattern disposed so as to form a loop face to face with the bending section of the J-shaped conductor pattern.

Abstract: A head mounted tracker is placed in the operator area near the operator. The tracker has the capability to map the operator area without manual assistance. These operations are performed by processing low and high frequency components, based on the frequency of an alternating current generating the magnetic field, of the magnetic field in the operator area.

Abstract: In a magnetic impedance device according to the present invention, an approximately uniformly biased magnetic field is applied to a sensing part of a magnetic wire in a longitudinal direction by setting the range of winding of a coil. The sensing part is composed of magnetic material with high permeability and is disposed between a pair of mounting pins. The coil is wound around the sensing part of the magnetic wire and generates a biasing magnetic field. The range of winding of the coil is longer than the sensing part. This arrangement allows the sensing part of the magnetic wire to detect external magnetic fields without problems caused by edge effects from the ends of the coil, thereby enhancing the precision of detection.

Abstract: A magnetic force microscopy (MFM) probe has an elongated probe tip with a planar surface onto which a uniformly thick magnetic film is formed. The probe tip is formed by focused ion beam (FIB) machining in a manner that creates both the planar surface and a triangular end with the triangular vertex forming the tip apex. Because the magnetic film is formed on a planar surface and has a uniform thickness it has the structural shape of an ideal bar magnet, with the triangular tip apex concentrating the magnetic flux from the ideal bar magnet to a very small volume. The probe tip has a length-to-width ratio of approximately 8:1 or greater, which gives rise to strong magnetic shape anisotropy. This stabilizes the magnetization of the tip in the presence of external magnetic fields, including fields from the sample.

Abstract: A method and apparatus for detecting mostly-plastic mines having steel firing pins and copper igniter cups. A frequency spectrum is transmitted, and response signals from the metal components induced by resultant eddy currents are detected. The firing pin generates a response characterized by a first frequency that is in phase with the transmitted frequency, whereas the igniter cup generates a response characterized by a second frequency that is in quadrature with the transmitted frequency. Accordingly, the detected response can be compared to prestored response templates to determine what type of mine, if any, has been detected, with the use of two response frequencies and phase relationships enabling the discrimination of buried plastic mines from surrounding metal particles in the earth.