Inductive sensor

About: Inductive sensor is a research topic. Over the lifetime, 2282 publications have been published within this topic receiving 21984 citations.

Inductive Sensor for Temperature Measurement in Induction Heating Applications

Abstract: A new inductive sensor for temperature measurement in domestic induction hobs and results of its applications are presented. It consists of a coil and a resonant electronic circuit which measures the impedance variation of ferromagnetic pots when their temperature changes. This sensor has promising applicability in induction hobs because it has instantaneous response, it is cheap, and contactless. The performance of the sensor is tested in the cooking range from 20°C to 220° C with pots of different materials, revealing a measurement error lower than 6°C. This error is much lower than that obtained from measurements with current sensing systems installed in induction hobs, namely a thermistor measuring the temperature of the glass in the cooking zone. The proposed sensor will allow fire prevention in cooking processes with a cost comparable to that of conventional measurement systems.

Method and device for detecting displacement of valve rod movement in an electropneumatic position regulator with at least one proximity sensor

Abstract: A method and apparatus for detecting displacement of valve rod movement in electropneumatic position regulators, by generating a high-frequency electromagnetic alternating field by exciting a high-frequency oscillation within an LC oscillating circuit in an inductive sensor, damping the high-frequency oscillation as a function of displacement via an electrically conductive body moved along by the valve rod, demodulating the oscillator signal and feeding the demodulated signal to a microcomputer without amplification for evaluation of the displacement-dependent damping of the oscillation amplitude, measuring the temperature within the inductive sensor, correlating the temperature with the measured oscillation amplitude in the microcomputer, and determining a corrected displacement signal from the correlation.

Method and apparatus for measuring thickness of conductive films with the use of inductive and capacitive sensors

Abstract: The invention relates to an apparatus for measuring thickness and deviations from the thickness of thin conductive coatings on various substrates, e.g., metal coating films in semiconductor wafer or hard drive disks. The thickness films may be as small as fractions of microns. The apparatus consists of an inductive sensor and a proximity sensor, which are rigidly interconnected though a piezo-actuator used for displacements of the inductive sensor with respect to the surface of the object being measured. Based on the results of the operation of the proximity sensor, the inductive sensor is maintained at a constant distance from the controlled surface. Variations in the thickness of the coating film and in the distance between the inductive sensor and the coating film change the current in the inductive coil of the sensor. The inductive sensor is calibrated so that, for a predetermined object with a predetermined metal coating and thickness of the coating, variations in the amplitude of the inductive sensor current reflect fluctuations in the thickness of the coating. The distinguishing feature of the invention resides in the actuating mechanism of microdisplacements and in the measurement and control units that realize interconnection between the proximity sensor and the inductive sensor via the actuating mechanism. The actuating mechanism is a piezo actuator. Measurement of the film thickness in the submicron range becomes possible due to highly accurate dynamic stabilization of the aforementioned distance between the inductive sensor and the object. According to one embodiment, the distance is controlled optically with the use of a miniature interferometer, which is rigidly connected to the inductive sensor. According to another embodiment, the distance is controlled with the use of a capacitance sensor, which is also rigidly connected to the inductive sensor.

Device for contact-less measurement of distances in multiple directions

Abstract: A device for contact-less measurement of distances (10, 20) in multiple directions of an electrically conductive body (2, 22) comprises a plurality of inductive elements (1, 4, 7). At least one (1) of the plurality of inductive elements (1, 4, 7) is placed essentially around the body (2). The other inductive ele­ments or other magnetic field sensors (4, 7) are provided in the vicinity of said one inductive element (1). The device with these features allows integrating a multi axis inductive sensor on a single circuit board.

In-Situ Investigation of Strain-Induced Martensitic Transformation Kinetics in an Austenitic Stainless Steel by Inductive Measurements

Abstract: An inductive sensor developed by Philips ATC has been used to study in-situ the austenite (γ) to martensite (α′) phase transformation kinetics during tensile testing in an AISI 301 austenitic stainless steel. A correlation between the sensor output signal and the volume fraction of α′-martensite has been found by comparing the results to the ex-situ characterization by magnetization measurements, light optical microscopy, and X-ray diffraction. The sensor has allowed for the observation of the stepwise transformation behavior, a not-well-understood phenomena that takes place in large regions of the bulk material and that so far had only been observed by synchrotron X-ray diffraction.