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Showing papers on "Inductive sensor published in 2004"


01 Jan 2004
TL;DR: In this article, the authors define a position sensor as a sensor or a transducer: position versus displacement, absolute or incremental reading, contact or contactless sensing and actuation, or linear and angular configurations.
Abstract: Preface 1 Sensor Definitions and Conventions 11 Is It a Sensor or a Transducer? 12 Position versus Displacement 13 Absolute or Incremental Reading 14 Contact or Contactless Sensing and Actuation 15 Linear and Angular Configurations 16 Application versus Sensor Technology 2 Specifications 21 About Position Sensor Specifications 22 Measuring Range 23 Zero and Span 24 Repeatability 25 Nonlinearity 26 Hysteresis 27 Calibrated Accuracy 28 Drift 29 What Does All This about Accuracy Mean to Me? 210 Temperature Effects 211 Response Time 212 Output Types 213 Shock and Vibration 214 EMI/EMC 215 Power Requirements 216 Intrinsic Safety, Explosion Proofing, and Purging 217 Reliability 3 Resistive Sensing 31 Resistive Position Transducers 32 Resistance 33 History of Resistive Linear Position Transducers 34 Linear Position Transducer Design 35 Resistive Element 36 Wiper 37 Linear Mechanics 38 Signal Conditioning 39 Advantages and Disadvantages 310 Performance Specifications 311 Typical Performance Specifications and Applications 4 Capacitive Sensing 41 Capacitive Position Transducers 42 Capacitance 43 Dielectric Constant 44 History of Capacitive Sensors 45 Capacitive Position Transducer Design 46 Electronic Circuits for Capacitive Transducers 47 Guard Electrodes 48 EMI/RFI 49 Typical Performance Specifications and Applications 5 Inductive Sensing 51 Inductive Position Transducers 52 Inductance 53 Permeability 54 History of Inductive Sensors 55 Inductive Position Transducer Design 56 Coil 57 Core 58 Signal Conditioning 59 Advantages 510 Typical Performance Specifications and Applications 6 The LVDT 61 LVDT Position Transducers 62 History of the LVDT 63 LVDT Position Transducer Design 64 Coils 65 Core 66 Carrier Frequency 67 Demodulation 68 Signal Conditioning 69 Advantages 610 Typical Performance Specifications and Applications 7 The Hall Effect 71 Hall Effect Transducers 72 The Hall Effect 73 History of the Hall Effect 74 Hall Effect Position Transducer Design 75 Hall Effect Element 76 Electronics 77 Linear Arrays 78 Advantages 79 Typical Performance Specifications and Applications 8 Magnetoresistive Sensing 81 Magnetoresistive Transducers 82 Magnetoresistance 83 History of Magnetoresistive Sensors 84 Magnetoresistive Position Transducer Design 85 Magnetoresistive Element 86 Linear Arrays 87 Electronics 88 Advantages 89 Typical Performance Specifications and Applications 9 Magnetostrictive Sensing 91 Magnetostrictive Transducers 92 Magnetostriction 93 History of Magnetostrictive Sensors 94 Magnetostrictive Position Transducer Design 95 Waveguide 96 Position Magnet 97 Pickup Devices 98 Damp 99 Electronics 910 Advantages 911 Typical Performance Specifications 912 Application 10 Encoders 101 Linear Encoders 102 History of Encoders 103 Construction 104 Absolute versus Incremental Encoders 105 Optical Encoders 106 Magnetic Encoders 107 Quadrature 108 Binary versus Gray Code 109 Electronics 1010 Advantages 1011 Typical Performance Specification and Applications References Index

104 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented an inductive proximity sensor with fully integrated electronics, which is composed of a sensing flat coil and an integrated electronic interface, with a longitudinal resolution of 120 nm for an aluminum target position up to 500um from the sensing coil with the side size of 3.5 mm.
Abstract: In this paper,we present an inductive proximity sensor with fully integrated electronics. The sensor with the compact hybrid configuration is composed of a sensing flat coil and an integrated electronic interface. We focused during the development on the temperature stability and robustness of the sensor by keeping its low-fabrication cost. The sensor exhibits a longitudinal resolution of 120 nm for an aluminum target position up to 500um from the sensing coil with the side size of 3.5 mm. The temperature drift of the sensor is less than 700 ppm/◦C for the same range of the target position. The total working range is from 100 to 1500um. The sensor power consumption is 100mW and the active sensor dimensions are 3.5mm×3.5mm×1.2 mm.We also showed the facility of the sensor packaging. This kind of integrated sensor has the potential for even more industrial applications.

82 citations


Patent
02 Dec 2004
TL;DR: In this article, a sensing device includes a circuit that compensates for time and spatial changes in temperature, which includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes.
Abstract: A sensing device includes a circuit that compensates for time and spatial changes in temperature. The circuit includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes. The circuit also provides correction for temperature gradients across coils of the transducer.

37 citations


Patent
30 Sep 2004
TL;DR: In this paper, an extended range inductive proximity sensor (IRIS) is used to determine coil temperature in a proximity sensor, where voltage measurements can be taken before, and during, damped oscillatory decay of a voltage in a resonant circuit in the proximity sensor to determine a value, γ, associated with an inductive time constant for the resonance circuit.
Abstract: Systems and methods are disclosed that facilitate determining coil temperature in a proximity sensor, such as an extended range inductive proximity sensor. Voltage measurements can be taken before, and during, damped oscillatory decay of a voltage in a resonant circuit in the proximity sensor to determine a value, γ, associated with an inductive time constant for the resonant circuit. The gamma value comprises information related to both inductance and resistance in the sensor coil, and can be employed to determine coil temperature. Derivation of the gamma value, and thus of coil temperature, can utilize a current pulse of a duration of approximately one RC time constant of the resonant circuit, thus mitigating current consumption by the proximity sensor during temperature assessment.

29 citations


Patent
26 Mar 2004
TL;DR: In this paper, an inductive proximity sensor (D) includes a coil or inductance (L) arranged in the vicinity of the active surface or end of the sensor, a current source (C, S) repeatedly supplying the coil or induction, a signals processor (SP) for signals corresponding to the voltages (V) induced in the coils or inductances when fed, the induced voltages being influenced by the presence of objects or bodies (B) within a given detection area, depending on their distance and on their constituting material(s), being part of a parallel LC
Abstract: An inductive proximity sensor (D) includes: a coil or inductance (L) arranged in the vicinity of the active surface or end of the sensor (D), a current source (C, S) repeatedly supplying the coil or inductance, a signals processor (SP) for signals corresponding to the voltages (V) induced in the coil or inductance (L) when fed, the induced voltages (V) being influenced by the presence of objects or bodies (B) within a given detection area, depending on their distance and on their constituting material(s), and the coil or inductance (L) being part of a parallel LC circuit. The current source is the capacitor (C) of the LC circuit. A voltage signal amplitude measurement is performed after each switch from charge to discharge state. The result is computed using reference measurements to calculate distance (D), nature of the constituting material(s), and/or mass indicative value of the object(s) (B).

19 citations


Journal ArticleDOI
TL;DR: In this article, two feed-forward back-propagation neural networks were used to estimate bar depth and diameter using images generated by an inductive sensor, and the results showed that the extracted bar diameter is within the requirements of the DIN 488 standard.
Abstract: A new method is presented for extracting dimensional information from steel bars using images generated by an inductive sensor The technique is based on the application of two feedforward backpropagation neural networks; one to estimate bar depth and the other to estimate bar diameter Both of the networks have been trained on a set of data that consists of the peak parameters of six different bars scanned at 41 different bar depths These input and target data must be pre-processed to obtain a good network generalisation By testing the two networks with a completely different set of data, accurate performance has been obtained Real, two-dimensional scan data have then been applied to both of the networks and the bar dimensional parameters have been extracted successfully The advantage of the neural network method for extracting information is that it continues to operate reliably for very deep bars, for which the signal strength is severely attenuated and manifests a poor signal-to-noise ratio Depth and diameter measurements have been obtained for bars located down to 58 mm, with errors that satisfy the requirements of the BS 1881 standard At a depth of 40 mm, these measurements yield an error of ±4%, and this decreases as the depth reduces; in other words, the extracted bar diameter is within the requirements of the DIN 488 standard

18 citations


Journal ArticleDOI
TL;DR: In this article, the effect of microstructural variations, particularly decarburisation, on the signal from an electromagnetic sensor used to detect ferrite formation from austenite below the Curie temperature was reported.

14 citations


Patent
04 Nov 2004
TL;DR: In this article, an inductive proximity sensor, comprising a resonant circuit (120) adapted to be affected electrically by the approach of metallic materials and comprising a control (130) for storing a value of a sampling instant when an output value of the resonant circuits is measured, the sampling instant corresponds substantially to an instant in which a first amplitude of the response of the resonance to a pulse applied thereto, measured in the presence of a ferromagnetic material arranged at a distance from the proximity sensor (100), is substantially equal to a second amplitude of a non-ferromagnetic
Abstract: An inductive proximity sensor, comprising a resonant circuit (120) adapted to be affected electrically by the approach of metallic materials and comprising a control (130) for storing a value of a sampling instant when an output value of the resonant circuit (120) is measured, the sampling instant corresponding substantially to an instant in which a first amplitude of the response of the resonant circuit (120) to a pulse applied thereto, measured in the presence of a ferromagnetic material arranged at a distance from the sensor (100), is substantially equal to a second amplitude of the pulse response measured in the presence of a non-ferromagnetic material arranged at the same distance.

12 citations


Patent
14 Feb 2004
TL;DR: In this article, an independent claim is made for a measurement device with a high-frequency capacitive sensor and at least one other sensor, e.g., an inductive, radar, broadband pulsed radar or infrared sensor.
Abstract: Method for locating an object enclosed within a medium uses a high-frequency capacitive sensor (60) and at least one other sensor to obtain an information signal relating to the enclosed object. An independent claim is made for a measurement device with a high-frequency capacitive sensor and at least one other sensor, e.g. an inductive, radar, broadband pulsed radar or infrared sensor.

9 citations


Patent
30 Sep 2004
TL;DR: In this paper, a sensor element is arranged on a lead structure for adjusting the operating point of the sensor element in measuring magnetic field based on current flow, and an independent claim is included for the operation method of the sensors.
Abstract: The sensor (10) has a sensor element (12) for measuring magnetic field (20,28), and generates output signals (30) based on the measured magnetic field. The sensor element is arranged on a lead structure (14) for adjusting the operating point of the sensor element in measuring magnetic field based on current flow. An independent claim is included for the operation method of the sensor.

9 citations


Patent
15 Sep 2004
TL;DR: In this article, a method and apparatus for measuring temperature of a conductive film or coating on a non-conductive substrate or on a substrate having conductivity significantly lower than that of the material or coating is presented.
Abstract: The invention provides a method and apparatus for measuring temperature of a conductive film or coating on a non-conductive substrate or on a substrate having conductivity significantly lower than that of the film or coating. The temperature is measured with the use of an inductive sensor as at least one of electrical characteristics of the film or coating the relation of which with the temperature is known. The invention is intended for use in processes that involve heating of the conductive film or coating, e.g., annealing. The sensor is located on the side of the object-holding chuck opposite to the object but at a distance from the object that provides sensitivity of the sensor. A distinguishing feature of the invention is a shield formed from a layer of a dielectric-liquid that is permeable to electromagnetic waves but resistant to permeation of heat flow. This shield is arranged between the aforementioned conductive film or coating on a semiconductive substrate and the inductive sensor for shielding the sensor against influence of heat developed in the processing chamber. Preferably, the sensor is an inductive resonance-type sensor.

Proceedings ArticleDOI
21 Jul 2004
TL;DR: In this article, the authors proposed the BEMI (Barkhausen Noise and Eddy Current MIcroscopy) method for non-destructive testing of thin materials.
Abstract: The need for an accelerated development of new materials and surfaces raises expectations in lateral homogeneity and quantitative exactness of the characteristic material properties. The interest is focused on microstructure characterization, detection of micro-imperfections and evaluation of the local distribution of residual stresses, mechanical hardness and coating thickness. These requirements meet with the development of high-resolution NDT methods such as Barkhausen Noise and Eddy Current MIcroscopy (BEMI) at IZFP. BEMI enables locally high-resolved non-destructive materials testing by means of Barkhausen noise and eddy current analysis: The sample is scanned with a miniaturized inductive probe which serves as Barkhausen noise pick-up and eddy current inductive sensor. Characteristic quantities are derived from the measured data and mapped as 2-D or 3-D images allowing the recognition of defects as small as 5 μm. The device is controlled by a modular measuring system which is split into modules for positioning, data acquisition and evaluation. Two additional software modules enable contact-less, quantitative testing of sensitive surfaces. This way, thin coatings can be characterized regarding their microstructure, thickness, internal stresses and heat-treatment condition. The efficiency of this device was demonstrated on many materials as solids stacks of several thin films. The BEMI testing device achieves an accuracy of 10 nm for the thickness of thin films on a variety of substrates.

Patent
09 Sep 2004
TL;DR: In this paper, the authors describe an inductive sensor of alternate current for use in an electronic currentmeter, which consists of two coils (1, 2) containing each two windings, one winding for current measurement and another serving as a static armour of the first winding, whereby both coils are positioned on a printed circuit board.
Abstract: An inductive sensor of alternate current, preferably for use in an electronic current meter basically consists of two coils (1,2) containing each two windings, one winding for current measurement and another serving as a static armour of the first winding, whereby both coils (1,2) are positioned on a printed circuit board (3) that can be independent or part of a printed circuit board of a large electronic assembly and function as a secondary winding of the sensor. The sensor of the invention is characterized in that a primary winding (4) is of such shape that its free ends are adapted to various types of connectors (DIN, BS, ANSI) of electronic electricity meters, whereas the central part of the primary winding is shaped in a way that it at least partially embraces both coils (1,2) in a relatively small distance or runs between them.

Patent
18 Feb 2004
TL;DR: In this paper, a non-contacting position sensor having primary and secondary sensors detects relative displacement between two objects, where the primary sensor is positioned in a flux path between sections of a flux gathering pole.
Abstract: A non-contacting position sensor having primary and secondary sensors detects relative displacement between two objects. The secondary sensor may function as a limit switch detection element in a limit switch circuit, and is positioned to be in the path of magnetic flux not detected by the primary sensor. The primary sensor is positioned in a flux path between sections of a flux gathering pole. A secondary sensor is positioned in a leakage flux path outside the first sensor or may be positioned in a secondary flux path.

Patent
26 Jan 2004
TL;DR: A position detector for the position of a pipe (10) movable scraper (12) comprises an annular radially magnetized permanent magnet (22) and arranged one on the conduit (10), which, for example, is an inductive sensor as mentioned in this paper.
Abstract: A position detector for the position of a pipe (10) movable scraper (12) comprises an annular radially magnetized permanent magnet (22) and arranged one on the conduit (10) magnetic field sensor (24) which, for example, an inductive sensor. In a further embodiment, two Hall sensors are arranged opposite one another on the pipe. In this case, in the pipeline a rod-shaped, transversely oriented to the longitudinal axis of the pipe magnet and two pole shoes extending in the circumferential direction may be used.

Patent
Lutz Rissing1
20 Feb 2004
TL;DR: An inductive sensor includes at least two circuit boards and receiver circuit traces applied on the first circuit board as discussed by the authors, which are joined in a sandwich-type manner and at least one component of the evaluation electronics is accommodated between the two circuits.
Abstract: An inductive sensor includes at least two circuit boards and receiver circuit traces applied on the first circuit board. Arranged on the second circuit board are components of an evaluation electronics for evaluating signals that originate from the receiver circuit traces. The two circuit boards are joined in a sandwich-type manner and at least one component of the evaluation electronics is accommodated between the two circuit boards. A rotary encoder may be fitted with this inductive sensor.

Patent
03 Dec 2004
TL;DR: In this article, a function that defines how the performance of a given proximity sensor deviates from performance reference data is employed to normalize the count of oscillations produced by the given proximity sensors and the normalized count is used to determine presence of an object.
Abstract: A proximity sensor has a resonant circuit which when stimulated by a pulse produces a signal with decaying oscillations. The number of such oscillations above a signal threshold varies in relation to the distance between a metal object and the proximity sensor. The sensor operation is configured by deriving a function that defines how the performance of a given proximity sensor deviates from performance reference data. The function is employed to normalize the count of oscillations produced by the given proximity sensor and the normalized count is used to determine presence of an object. By normalizing sensor performance, common configuration data can be used to setup a given proximity sensor without having to take into account specific performance variations of that sensor.

Patent
19 Feb 2004
TL;DR: In this article, a linear sensor and coupling element are arranged on the opposite side of the pivot axle to the pedal, where the sensor is an inductive sensor and the coupling element is a linear coupling element.
Abstract: Motor vehicle accelerator pedal arrangement (1) has a pedal (5), pedal arm (4) and a housing (2, 3) on which the arm is mounted so that it pivots around an axle. A linear sensor has a sensor (13) and coupling element (9) with the sensor connected to the housing and the coupling element attached to the pedal arm. The sensor and coupling element are arranged on the opposite side of the pivot axle to the pedal. The linear sensor is an inductive sensor.

Proceedings ArticleDOI
18 May 2004
TL;DR: In this article, an innovative approach for position, velocity and acceleration estimation using traditional inductive sensors such as LVDTs is described, which overcomes typical limits of traditional processing techniques, such as coherent demodulation or spectral analysis, implementing a least mean squares estimation of interesting variables.
Abstract: This paper describes an innovative approach for position, velocity and acceleration estimation using traditional inductive sensors such as LVDTs. These transducers have been considered thanks to their diffusions and performances; however, the same algorithm can be applied to any other kind of AC-excited sensor. It overcomes typical limits of traditional processing techniques, such as coherent demodulation or spectral analysis, implementing a least mean squares estimation of interesting variables. Some preliminary simulations have been conducted to evaluate algorithm functionalities. A working prototype, designed around a low-cost DSP from TI, has been realized to perform real world tests.

Journal ArticleDOI
01 Feb 2004-Insight
TL;DR: In this article, a combined Q and heterodyne inductive sensor is described incorporating real-time digital signal processing (DSP) for the imaging of steel reinforcement together with surface corrosion within concrete.
Abstract: A combined Q and heterodyne inductive sensor is described incorporating real-time digital signal processing (DSP) for the imaging of steel reinforcement together with surface corrosion within concrete. The sensor exploitsthe principle whereby a time- varying magnetic field is induced around a sensing coil carrying an alternating current. When a metal target is exposed to the sensing coil, eddy currents will be induced resulting in an EMF, which will oppose the change producing it. As a result the electrical properties and the impedance of the sensing coil will change due to the interaction with the field around the target. In general, conductive targets change the resistive part and non-conducting permeable targets change the reactive part. A change in voltage amplitude will occur for conductive targets and frequency change for non-conducting ferrous targets. These parameter changes are expressed as a voltage level and processed by a DSP system. The DSP system is acquiring hundreds of samples per second and filtering the data using moving averaging. It is possible to detect a steel bar to a depth of approximately 150 mm and to generate an image to a depth of approximately 30 to 60 mm, indicating the presence of surface corrosion.

Patent
28 Sep 2004
TL;DR: In this article, an extended range inductive proximity sensor is used to compensate for temperature drift in a proximity sensor, such as an Extended Range Inductive Sensor (ERSI) or an ERSI-based proximity sensor.
Abstract: Systems and methods are disclosed that compensate for temperature drift in a proximity sensor, such as an extended range inductive proximity sensor. Voltage measurement can be taken before, and during damped oscillatory decay of a voltage in a resonant circuit in the proximity sensor to determine a value, γ, associated with an inductive time constant for the resonant circuit. A target-induced inductance value can be isolated, via manipulation of the gamma value, and compared to a predetermined threshold value to determine whether the target has been sensed by the proximity sensor.

Journal ArticleDOI
TL;DR: An electronic interface circuit for sensors based on inductance variations is presented to reduce the number of circuit elements as much as possible, while maintaining sensibility, linearity and stability specifications of the output dc signal.
Abstract: In this work we present an electronic interface circuit for sensors based on inductance variations. The aim is to reduce the number of circuit elements as much as possible, while maintaining sensibility, linearity and stability specifications of the output dc signal. By carefully analyzing issues such as conditions for appropriate isolation between circuit stages and the possibilities of the filtering stage to improve the quality of the signal, we have been able to minimize significantly the amount of necessary electronic components. The results have been applied to an specific prototype of pressure sensor for automatic washing machines, but are extensive to other sensor devices based on inductance variations.

Patent
Rudolf Temming1
29 Dec 2004
TL;DR: In this article, the authors present a method for testing the functioning of an inductive sensor that is designed to detect the passage nearby of a metal object, especially a railway wheel, whereby in a track-side oscillation coil, a high-frequency alternating field is induced that is damped by a metal body or wheel.
Abstract: Method for testing the functioning of an inductive sensor (1) that is designed to detect the passage nearby of a metal object, especially a railway wheel, whereby in a track-side oscillation coil (2) a high-frequency alternating field is induced that is damped by a metal body or wheel In the time gaps between the passage of wheels cyclic test damping signals can be generated and detected - The invention also relates to a device for implementing the inventive method comprising a damping coil (11) that can be short circuited by a testing arrangement (12) so that it acts on the oscillation coil generating detectable test damping signals

Patent
09 Jun 2004
TL;DR: In this paper, the pedal unit includes a contactless linear sensor that has a cursor element (5) and a stator element and that is connected to a pedal lever (1).
Abstract: The pedal unit includes a contactless linear sensor that has a cursor element (5) and a stator element and that is connected to a pedal lever (1). The cursor element is coupled backlash free with the pedal lever via a slaving element. Preferably, the linear sensor is an inductive sensor.

Patent
16 Mar 2004
TL;DR: In this article, a circuit arrangement for adjusting inductive sensors, in particular from the track area provided by the two-wire wheel sensors, which in the fixing position on the rail are (1) various influences, for example due to the rail shape, the assembly position or the current temperature, a safe, fast and durable match is sought.
Abstract: In a circuit arrangement for adjusting inductive sensors, in particular from the track area provided by webs the two-wire wheel sensors (6) which in the fixing position on the rail are (1) various influences, for example due to the rail shape, the assembly position or the current temperature , a safe, fast and durable match is sought. To achieve this, the circuit arrangement (Fig. 2) passive balancing elements, particularly in the form of resistors (22 to 25) or capacitors, and at least one microcontroller (14) which can be activated via a control command, so that he controlled by him switch (17 to 20), the adjustment elements (22 to 25) achieved in a pre-selected sequence to the oscillator coil (7) on or off by this, to which, for example by a predetermined amount for the target quiescent current of the sensor (6) defined balance is. For example, in the microcontroller (14) a non-volatile memory may be provided which holds the switch positions in the collated status activate after the trimming microcontroller (14).

Patent
01 Jul 2004
TL;DR: In this article, an inductive rotational angle sensor for determining the angular position of a rotatable around a rotation axis member, with a position detector in the form of a coil arrangement comprising at least two series-connected, substantially identical measuring coils having disposed between the measuring coils average voltage tap, the measuring coil are each spirally wound on in an angular sector a housing fixedly mounted normal to the axis of rotation.
Abstract: In an inductive rotational angle sensor for determining the angular position of a rotatable around a rotation axis member, with a position detector in the form of a coil arrangement comprising at least two series-connected, substantially identical measuring coils having disposed between the measuring coils average voltage tap, the measuring coil are each spirally wound on in an angular sector a housing fixedly mounted normal to the axis of rotation, non-magnetic and non-conductive support wheel are disposed and is provided with a position sensor in the form of two with an inductively active material, formed as an angular sector discs sensor discs, the opposite to each other axially on both sides and parallel to the carrier disc to a rotatable with the component connected support shaft are mounted, the sensor arrangement after Permeabilitatsprinzip is effectively formed, the coil arrangement comprises measuring coils with relatively low inductance and the Sensorsc heiben made of a soft magnetic material and are coupled via a soft-magnetic hub of the carrier axis magnetically with each other.

Patent
Solka Ulrich1
05 Feb 2004
TL;DR: In this article, a suitable arrangement for measuring the steering angle and or piston stroke is coupled to the piston rod of the steering cylinder, said arrangement incorporating at least a sensor system, such as an inductive sensor system.
Abstract: Device for measuring the steering angle or piston stroke of a steering cylinder, especially a synchronizing cylinder, whereby a suitable arrangement for measuring the steering angle and or piston stroke is coupled to the piston rod (3) of the steering cylinder, said arrangement incorporating at least a sensor system (10), such as an inductive sensor system.

Patent
18 Nov 2004
TL;DR: In this article, a method of assembling an inductive proximity sensor is presented. But the method is based on the inductive coil wound bobbin, which is not suitable for the case of a single core leg.
Abstract: An inductive proximity sensor comprises: a housing including an opening on one side; an inductive core including two legs, each core leg including a foot portion; an inductive coil wound bobbin disposed about each leg of the core, each bobbin including an integral ledge cantilevered from an inside surface of the bobbin for forming a pocket under the integral ledge at a bottom of the bobbin for containing the foot portion of the corresponding core leg; a thruster element including a top surface and two legs, each thruster leg disposed into a respective bobbin resting on the integral ledge thereof, the core, wound bobbins and thruster element disposed in the housing; a spring element disposed on the top surface of the thruster element at the housing opening; and a housing cover disposed over the housing opening for compressing the spring element against the thruster element which renders the core and wound bobbins in a fixed relationship to each other in the housing. Also disclosed is a method of assembling the proximity sensor.

Patent
02 Dec 2004
TL;DR: The magnetic inductive fluid flow sensor as discussed by the authors has a short straight length of non-ferromagnetic pipe between two flanges, with two saddle-shaped field coils (15,16) on the outside, with ferromagnetic coupling elements (17-20).
Abstract: The magnetic inductive fluid flow sensor (10) has a short straight length of non-ferromagnetic pipe (11) between two flanges (12,13). It has two saddle-shaped field coils (15,16) on the outside, with ferromagnetic coupling elements (17-20). The ferromagnetic coupling elements have projecting parts (17a-20a) covering the field coils. Packets of ferromagnetic laminae form pole shoes (21,22) lying between the field coils and the pipe. There are electromagnetic return circuits (23,24) near the ends of the pipe.

Journal ArticleDOI
TL;DR: In this paper, a spin-valve giant magnetoresistive (SV-GMR) sensor was proposed for inspection of PCBs, which showed high sensitivity to a small magnetic field in one direction.
Abstract: The eddy-current testing technique is an interesting method for detecting defects on bare printed circuit boards. This technique detects various defects without mechanical stress to PCB patterns. Usually various pickup coils are used in an ECT probe as a magnetic sensor. Pickup coil sensors, however, do not show enough S/N ratio to detect defects in high-density PCBs, whose conductors are less than 100μm. We propose a new ECT probe with a spin-valve giant magnetoresistive (SV-GMR) sensor for inspection of PCBs. SV-GMR sensors show high sensitivity to a small magnetic field in one direction. This sensor senses a magnetic field as varying its resistance unlike inductive sensors such as a pickup coil.In this paper, we investigated the sensing properties of a SV-GMR sensor with changing axes, frequencies, and magnetic field amplitudes, and discussed problems that could occur in replacing a pickup coil with SV-GMR.