Abstract: System for processing fine position signals pulse-width modulates signals from two magnetic sensors for producing sinusoidal wave signals different from each other in phase by a quarter cycle in correspondence with the scale pitches, then switches the phase so as to bring the pair of pulse-modulated signals in phase with each other, then calculates the weight constants for the pair of pulse-width modulated signals in phase in order that of said pair of pulse-width modulated signals in phase, any one having a higher linearity will be treated at a handsome rate, and then subjects said pulse-width modulated signals to weighted mean by the use of the resultant weight constants, with the result that the pair of pulse-width modulated signals will become free from disorder at the switching point, thereby producing signals of a high accuracy representing fine positions corresponding to the scale pitch divided at regular intervals.

Abstract: An apparatus for detecting machining conditions in a machine tool has a magnetic bearing for magnetically supporting a work spindle or a tool spindle. An exciting current detector is provided for detecting an exciting current of an electromagnet of the magnetic bearing. The exciting current corresponds to various machining conditions including the conditions when the machine tool starts operating, the tool contacts the workpiece to follow various unfinished faces, and a machining face condition of the workpiece during machining. The detection signals from the exciting current detector are inputted to a plurality of frequency band pass filters to discriminate the machining conditions. Comparators are provided to compare the output signals from the frequency band pass filters with a predetermined set of reference values, and comparative judgment signals are inputted to a control unit, thereby controlling the machine tool to automatically perform appropriate machining operations.

Abstract: A linearly moving external part on a multi-cylinder internal combustion engine is contacted with a hand-held rotary encoder, contact tachometer having a hollow handle in which processing circuitry is disposed for converting the rotary encoder output to a waveform signal. This signal, along with a signal responsive to the firing of the number one cylinder, are applied to an engine analyzer processor for display of a single engine cycle of the waveform signal on the CRT oscilloscope of the engine analyzer. The variations in amplitude of the waveform signal correspond to speed variations of the moving part over an engine cycle to give an indication of the relative power contributions of the individual cylinders.

Abstract: A proximity sensor is provided with a means for directly measuring parameters of a proximity sensor coil which permit the determination of both the AC and DC resistances of the coil. These parameters are then used to determine a discriminator value magnitude according to a mathematical relationship that has been predetermined through previous analysis of empirical data for the particular coil and application intended for the proximity sensor. In one particular application of the present invention, the rear AC resistance is utilized and is added to the DC resistance after the DC resistance has been mathematically altered by a preselected factor. Alternative embodiments of the present invention can also utilize the imaginary AC component of the impedance either by itself or in conjunction with the rear AC component of the impedance.

Abstract: A pickup coil and a planar type SQUID are formed integrally on a single substrate to form a SQUID magnetometer. The SQUID is disposed on the surface of a projecting portion of the substrate and an insulating layer for spacing is laminated on the SQUID. The top, bottom and side surfaces of the assembly of the SQUID and insulating layer covering the same are all covered with a superconducting layer to form a magnetic shield for enclosing the SQUID. The magnetic shield is remote from the planar type pickup coil disposed on the remaining portion of the substrate by a distance which is equal to or greater than a length of one side of the size of the magnetic shield, thereby preventing magnetic flux distortion due to the presence of the magnetic shield from disturbing coil balance of the pickup coil.

Abstract: An electromagnetic rotation sensor for detecting a rotational speed of a rotating member includes a sensor portion and a connector portion which are molded of a resin to provide a resin-molded structure. The resin-molded structure is received in a cover, with the connector portion extending outwardly from the cover through a sensor portion-positioning hole formed through a wall of the cover. In order to prevent a positional displacement of the sensor portion with respect to a detection gear, connected to the rotating member, when fixedly mounting the cover on the resin-molded structure, a primary molded portion is molded to provide the sensor portion, and then the primary molded portion is inserted into the cover, and then a secondary molded portion is molded to form the connector portion on the primary molded portion in such a manner that a peripheral edge portion of the sensor portion-positioning hole is fixedly held between the primary molded portion and the secondary molded portion.

Abstract: A scanning device for automated eddy current inspection of retaining rings is disclosed. The scanning device supports an eddy current probe inside the retaining rings and moves the probe automatically in an axial and rotational path within the rings to scan the entire surface of the rings.

Abstract: A system to determine the position of an electrically conductive element movably positioned in a housing, like a metal disc in a check valve, with greater accuracy and resolution than single magnet systems includes first and second A.C. electromagnets positioned in close proximity to the element on opposing sides of the housing. The magnets are excited with A.C. currents to generate magnetic fields which penetrate the housing and the element. The magnetic fields are sensed by a magnetic field sensor. A control portion of the system includes a microprocessor configured to allow an operator to adjustably select and set a common frequency, individual amplitudes and a phase difference between the two currents supplied to the two magnets so that the currents might be adjusted to cause the magnets to generate magnetic fields at least partially and preferably essentially cancelling one another at the sensor.

Abstract: A magnetic-field-sensitive device includes several magnetic-field sensors. Each sensor comprises a compound element surrounded by a coil winding. Each compound element is made of two ferromagnetic cell components extending in one axial direction with uniaxial magnetic anisotropy and with different coercive field strengths. A spontaneous reversal of magnetization is produced by an external magnetic switching field only in the cell component having the lower coercive field strength. The magnetic-field sensors are combined to form a series arrangement, or array, and the coil windings and cell components of the magnetic-field sensors of the array are formed as thin-film structures on a non-magnetic substrate.

Abstract: A gradiometer utilizes at least three vector magnetometers (preferably SQUIDs) to measure a magnetic field gradient. The gradiometer includes a reference magnetometer and a plurality of sensor magnetometers, wherein the reference magnetometer (SQUID) used to cancel background magnetic fields from outputs of the sensor magnetometers via a feedback loop provided with a signal from the reference magnetometer. Similarly, higher order gradiometers can be built using a reference magnetometer cube and a plurality of sensor magnetometer cubes.

Abstract: A magnetic encoder has a wiring structure which includes a retaining member 20 for retaining the magneto-sensitive element 37 in a certain positional relationship with respect to a surface on which a magnetic code is formed. This retaining member 20 is equipped with: a pair of gripping members 21c protruding toward the surface on which the magnetic code is formed; and an abutting member 21a adapted to abut against the back surface of the magneto-sensitive element 37 so as to keep the element 37 a certain distance apart from the surface on which the magnetic code is formed. The magneto-sensitive element 37, which is positioned by the abutting member 21a and the gripping members 21c, is fixed to the retaining member 20 by means of an adhesive agent or the like.

Abstract: The operation of a biomagnetometer is verified using a tool containing a dipole source of known strength having a fixed, known position. The tool includes a hollow nonconducting and nonmagnetic sphere filled with an electrically conducting fluid, and at least one well-characterized dipole source within the fluid. The position of the dipole source relative to fixed locations on the surface of the sphere is established by X-ray measurement, and the the fixed surface locations and strength of the dipole source are measured with the biomagnetometer. The position and strength of the dipole source determined in this manner are compared with the known position and strength of the dipole source, to verify the operation of the biomagnetometer.

Abstract: A system to determine the position of an electrically conductive element movably positioned in a housing, like a metal disc in a check valve, includes an A.C. electromagnet positioned in close proximity to the valve casing and the disc. The magnet is excited with an A.C. voltage to generate a magnetic field which penetrates the casing and the disc. The magnetic field is detected by a sensor. A.C. current and voltage signals from the electromagnet and a magnetic field signal from the sensor are presented to a processor portion of the system. The processor portion digitizes, amplitude and phase modulates each of the three signals and generates four traces: A.C. current amplitude, magnetic field amplitude, A.C. current phase and magnetic field phase. The latter two traces are derived with respect to an A.C. voltage phase signal. Comparable baseline signals previously gathered for the valve are stored.

Abstract: A non-contact level measurement system for monitoring distances with very high accuracy between a sensor coil and a metallic object such as a molten liquid level over either very narrow or extended distances. Controllers coupler with heaters, thermocouples, coolant air are provided for maintaining the sensor coil at a operating temperatures within the range of 400.degree. F. and 1200.degree. F. to eliminate variations to the operation of the sensor coil. The system incorporates an L-C resonant circuit connected between the output of an oscillator and the input of an operational amplifier. A variable inductor parallel with the capacitor of the L-C resonant circuit is used to obtain a precise offset operating frequency of the resonant circuit from the frequency of the oscillator.

Abstract: A transformer and method for sensing displacement, A linear variable displacement transformer (LVDT) 50, 100, 150, 200, and 250) is disclosed with respect to several embodiment,s each including a core (52, 102, 152, 202, and 252) having a primary leg (56, 104, 154, 204, and 254), and two secondary legs (58 and 60, 106 and 108, 158 and 160, 206 and 208, and 258 and 260). A primary coil (54, 110, 156, 210, and 264) is disposed on the primary leg, and secondary coils (62 and 64, 112 and 114, 162 and 164, 212 and 214, and 266 and 268) are disposed on the secondary legs. Pole pieces (70 and 72, 120 and 122, 170 and 172, 222 and 224, and 274 and 276) are disposed in gaps between the primary leg and each secondary leg, so that they control the reluctance to a magnetic flux produced by an electric current flowing thorugh the primary coil.

Abstract: A position detecting apparatus detects the position of an object and includes a sensor device which outputs first and second AC detection signals which have a predetermined phase relationship and which correspond to a detected position of the object. An instantaneous value detecting unit detects and outputs instantaneous values of the first and second AC detection signals. A DC component detecting unit processes the instantaneous values to obtain first and second DC components of the first and second AC detection signals, respectively. A position calculating section calculates the position of the object based on a difference between the first DC component and the first AC detection signal, and a difference between the second DC component and the second AC detection signal.

Abstract: A locating system has its performance enhanced by the use of digital filtering. The locating system may include a transmitter for transmitting an electromagnetic signal from a concealed object. The locating system may also use electromagnetic signals from existing electromagnetic sources unrelated to the locator system. A receiver is provided for receiving a selected electromagnetic signal. The signal is subsequently converted from an analog signal into a digital signal and subjected to digital filtering. The resulting digital signal is then processed to provide location information about the concealed object.

Abstract: Inductive proximity sensor for detecting an object having electrical conductivity comprising a sensor housing, a measuring coil and reference coil placed on either side of a plane of symmetry through the sensor housing. Each coil is partly surrounded by a piece of magnetic material which leaves the measuring coil or reference coil respectively free at the front which faces the direction of the object to be detected or a reference member. An electronic circuit is provided for supplying both coils with an AC signal and for measuring the change in a specific property of the measuring coil with respect to that of the reference coil when object approaches and determining therefrom the distance or the presence of the object. The pieces of magnetic material around the two coils are formed essentially from the same homogeneous material forming a block. Means are provided in the sensor housing for screening magnetic fields produced by both coils in order to suppress thereby mutual crosstalk.

Abstract: A meter driving device for indicating angular positions corresponding to input values. The device includes a memory for storing previously given input values, angular directions corresponding to the input values, and coefficients representative of the grades of change in angular direction depending on the change between adjacent two input values, as parameters. Based on these parameters and the frequency of input pulse signal giving the input values, the angular direction corresponding thereto is calculated. The angular direction signal receives PWM process and then supplies to a pair of crossed exciting coils via a driver. During a predetermined time period from the turning ON and OFF of the power source, the transference of the angular direction signals to the driver is shut out by logic gates, thereby inhibiting malfunctional meter indication.

Abstract: Pickup coils for imaging magnetometers are formed from plural turns of a conductor with varying spacing between turns selected so that the Fourier transform of the coil turns function which is the filter function of the coil, has no zeroes within the spatial frequency bandwidth of the magnetic field generated by a two or three dimensional current to be imaged. Various exemplary coil configurations are presented including a Gaussian distribution for the turns of a planar coil.