233results about "Magnetostrictive property measurements" patented technology

A magnetic torque transducer arrangement for self-compensating effects of external magnetic sources and temperature offset includes a shaft with at least one magnetized zone, at least one active magnetic field sensor and at least one passive magnetic field sensor disposed in such a way that the active field sensor is always in a position with higher magnetic field strength arising from applied torque than that of the passive sensor. Passive field sensors may also be placed on both sides of the active field sensor, or on only one side of the active field sensor. The transducer output is obtained by subtracting the output of the passive field sensors from that of the active field sensor, thus canceling out the effect of the interfering magnetic field flux and temperature offset on the torque transducer, and partially filtering out the temperature sensitivity drift and rotational dependant signal.

Apparatus and method for harvesting energy from the environment and / or other external sources and converting it to useful electrical energy. The harvester does not contain a permanent magnet or other local field source but instead relies on the earth's magnetic field of another source of a magnetic field that is external to the sensing device. One advantage of these new harvesters is that they can be made smaller and lighter than energy harvesters that contain a magnet and / or an inertial mass.

An apparatus for inspecting a metallic post contoured in a single dimension for defects. The apparatus has a clamp having at least one jaw with a surface conforming to the contour to the metallic post. The conforming jaw or jaws also have a plurality of eddy current coils and the probe has at least one sensor configured to sense at least one of position or motion.

An ultrasensitive room temperature magnetoelectric thin film magnetometer is fabricated on a cantilever beam and includes an active magnetoelectric multilayer structure having a plurality of thin films formed at a region defined on the cantilever beam. Upon application of a magnetic field, the active magnetoelectric structure generates a corresponding response of an electrical nature which is a measure of a value of the applied magnetic field. The material of the cantilever beam may be removed beneath the active magnetoelectric multilayer structure to form a freestanding modification of the magnetometer with superior sensitivity. The active magnetoelectric multilayer structure is either a bi-layer structure which includes a piezoactive (piezoelectric and / or piezoresistive) thin film deposited in contact with a magnetostrictive thin film or a tri-layer active structure (in the free-standing implementation) including a piezoactive thin film sandwiched between a pair of magnetostrictive thin films.

An apparatus (10) is set forth for measuring a return signal of a magnetostrictive sensor (20) that detects a force, torque, or pressure. The return signal includes noise, a DC resistance (44), an AC resistance and an inductance and the inductance is shifted ninety degrees from the AC resistance. The apparatus (10) includes a sensor filter (22) to remove the noise from the return signal. A sensor filter (22) shifts the return signal and more specifically, the inductance by an additional angle and the sum of the additional angle and the ninety degrees phase shift is defined as the final detection angle. To detect the inductance at the final detection angle, a wave filter (16) and a reference filter (28) shifts a reference signal by the final detection angle to trigger a first demodulator (26) to detect the inductance at the final detection angle. The inductance detected by the first demodulator (26) varies due to temperature. To remove the temperature from the measured inductance, the apparatus includes a DC detection circuit (42) to detect the DC resistance which is proportional to the temperature across the sensor (20). The DC resistance and the measure inductance are inserted into a correction equation to produce a corrected inductance which is independent of temperature. Instead of inductance, an AC resistance may be used in the equation.

A magnetic field sensor circuit comprises a first magneto-resistive sensor (Rx) which senses a first magnetic field component in a first direction to supply a first sense signal (Vx). A first flipping coil (FC1) applies a first flipping magnetic field with a periodically changing polarity to the first magneto-resistive sensor (Rx) to cause the first sense signal (Vx) to have alternating different levels synchronized with the first flipping magnetic field. A second magneto -resistive sensor (Ry) senses a second magnetic field component in a second direction different than the first direction to supply a second sense signal (Vy). A second flipping coil (FC2) applies a second flipping magnetic field with a periodically changing polarity to the second magneto -resistive sensor (Ry) to cause the second sense signal (Vy) to have an alternating different levels synchronized with the second flipping magnetic field. The first flipping magnetic field and the second flipping magnetic field have a phase shift. A differential amplifier (AMP1) receives the first sense signal (Vx) and the second sense signal (Vy) to obtain a difference signal (Vd). A first synchronous demodulator (DEM1) receives the difference signal (Vd) and a first switching signal (Q1) being phase locked to the alternating different levels of the first sense signal (Vx) to supply a first output signal (Vox) indicating the first magnetic field component. A second synchronous demodulator (DEM2) receives the difference signal (Vd) and a second switching signal (Q2) being phase locked to the alternating different levels of the second sense signal (Vy) to supply a second output signal (Voy) indicating the second magnetic field component.