Showing papers on "Inductive sensor published in 1995"
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07 Jun 1995
TL;DR: In this article, the magnetic sensor is placed at a right angle to the sensor electronics to provide a smaller surface area across the diameter of the sensor, and the magnet that charges the object to be detected is manufactured as a part of a sensor encapsulant.
Abstract: A method and apparatus for sensing proximity of an object using near-field effects or magnetic effects. The sensor chips are designed to accommodate numerous sensing elements. In the electromagnetic sensor, radio frequency energy is fed to an antenna. The antenna radiates this radio frequency energy to charge the surface of an object. When the position of the object changes, the impedance of the antenna due to near-field effects changes. This impedance change is detected to provide an indication of the object's movement. In the magnetic sensor, the sensing element is placed at a right angle to the sensor electronics to provide a smaller surface area across the diameter of the sensor. The magnet that charges the object to be detected is manufactured as a part of the sensor encapsulant. The sensing device may be packaged to be inserted into a wall to provide a sensor having a leak-free seal.
86 citations
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06 Jun 1995
TL;DR: In this article, an electromagnetically resonant sensor has a measurable resonance characteristic (e.g., center resonance frequency, quality factor, or bandwidth) that varies in correspondence to changes in the environmental condition present at the sensor.
Abstract: Apparatus, and related method, for remotely measuring at 1east one environmental condition includes an electromagnetically resonant sensor having a measurable resonance characteristic (e.g., center resonance frequency, quality factor, or bandwidth) that varies in correspondence to changes in the environmental condition present at the sensor. The sensor emits an electromagnetic return signal representative of a state of the resonance characteristic when an electromagnetic excitation signal impinges on the sensor. The electromagnetic excitation signal is generated by a generator located separate and away from the sensor, and the excitation signal is then directed at the remote sensor. The sensor thus remotely detects and measures the environmental condition. In one embodiment, the sensor is an electromagnetically resonant electrical circuit. In another embodiment, the sensor is an antenna resonator (e.g., a half-wavelength antenna) made of a conductive material.
76 citations
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21 Mar 1995
TL;DR: In this article, a patient's body is supported on a number of interconnected compartments filled with air or water, and a thin metal sheet is attached to the inside of the upper surface and combines with a plate on the underside to form an inductive sensor.
Abstract: The method involves supporting a patients body (P) on a number of interconnected compartments (14) filled with air or water. A thin metal sheet (B) is attached to the inside of the upper surface (15) and combines with a plate (34) on the underside (16) to form an inductive sensor (34). The inductive sensor (30) measures the distance (Dm) between upper and lower surfaces and is connected to an oscillator (44), amplifier (46), preset distance (Dc) adjustment (48), and regulator and adaptor (50, 52). A computer (42) controls a pump (18, 20) and release valve (22) to maintain the distance between upper and lower surfaces (Dm) at the preset value (Dc).
30 citations
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TL;DR: In this article, an inductive magnetization sensor was designed to measure thin superconducting films (of order 3000 A) in very strong magnetic fields, and the sensitivity of the probe was 10−2 emu.
Abstract: This paper describes an inductive magnetization sensor, designed to measure thin superconducting films (of order 3000 A) in very strong magnetic fields. For magnetic fields in the range 250–500 kG, the sensitivity of the probe is 10−2 emu. Accuracy and high sensitivity were obtained by combining a sample extraction system, vibration isolation, and an inductive sensor with optimized flux coupling geometry. The magnetic flux coupling to the sensor was verified to exceed 70%, both by calculation and experimental calibration.
30 citations
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03 Mar 1995TL;DR: In this paper, an inductive proximity sensor has a resonant circuit including a sensing coil and driven by an oscillator at a predetermined frequency, and discriminator logic is provided to process phase shift signal and damping signal.
Abstract: An inductive proximity sensor has a resonant circuit including a sensing coil and driven by an oscillator at a predetermined frequency. To sense selectively ferrous and non-ferrous objects, the excitation frequency is a subcritical excitation frequency and discriminator logic is provided to process a phase-shift signal and a damping signal.
27 citations
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17 Aug 1995
TL;DR: In this article, a feedback circuit for generating an output signal from a sensor that makes changing electrical and temperature characteristics of the sensor and any sensing medium irrelevant is proposed, where the sensor is placed in the forward loop of the circuit to make the output depend on the area of the parallel plates the sensor, not on any electrical or temperature characteristics.
Abstract: A feedback circuit for generating an output signal from a sensor that makes changing electrical and temperature characteristics of the sensor and any sensing medium irrelevant. The sensor is placed in the forward loop of the circuit to make the output depend on the area of the parallel plates the sensor, not on any electrical or temperature characteristics of the sensor or sensing medium. A liquid filled sensor having parallel conducting plates, one solid and the other being split into two differential plate sections may be used in the forward loop as a liquid level sensor or an inclinometer. Alternative sensors such as inductive sensors may also be used.
24 citations
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05 Sep 1995TL;DR: In this article, a three-phase variable reluctance motor is used as an encoder system to commutate a rotor, which includes a power source, a position sensor and excitation electronics.
Abstract: A method and apparatus for exciting a three-phase variable reluctance motor is used, for example, as an encoder system to commutate a rotor. The system includes a power source, a position sensor and excitation electronics. The position sensor is adapted to generate a plurality of variable induction values corresponding to relative motor torque rankings and absolute angular positions of the rotor. Excitation electronics is provided electric communication with the inductive sensor and the power source and is adapted to generate digital values of the inductance values corresponding to the motor torque rankings. Excitation electronics includes steering logic responsive to the digital values to generate an output signal having a value corresponding to the phase of the motor to apply current to so as to commutate the rotor.
24 citations
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TL;DR: In this paper, a low-cost and highly robust displacement sensor based on the Linear Variable Differential Transformer (LVDT) principle has been constructed in flat form in order to verify a certain system design mix of techniques.
19 citations
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3M1
TL;DR: In this paper, a detector system filters the effects of periodic noise such as magnetic flux from nearby power lines or other periodic sources and further adapts in the case that the system incorporates microloops for the inductive sensors.
Abstract: A detector system filters the effects of periodic noise such as magnetic flux from nearby power lines or other periodic sources The detector system further adapts in the case that the system incorporates microloops for the inductive sensors The detector system further counts multiple vehicles while in presence mode The detector system also allows logging of vehicle data and system faults
17 citations
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28 Nov 1995TL;DR: A reading head able to process both inductive debit cards and chip cards comprising two dissimilar complementary portions, the internal surfaces of the portions defining the channel housing the data card inserted in the head, the first portion (80) having inductive sensors (83) for the reading of inductive credit cells and the second portion (140) having a magnetic metal plate (142) completing the magnetic circuit of the inductive sensor, as well as contact pins (162) engaging the terminal pads on the surface of the card as discussed by the authors.
Abstract: A reading head able to process both inductive debit cards and chip cards comprising two dissimilar complementary portions, the internal surfaces of the portions defining the channel housing the data card inserted in the head, the first portion (80) having inductive sensors (83) for the reading of inductive credit cells and the second portion (140) having a magnetic metal plate (142) which completes the magnetic circuit of the inductive sensors, as well as contact pins (162) engaging the terminal pads on the surface of the card. The portions remain normally kept apart by a first set of mechanical coupling devices (84, 85, 86, 88, 89, 93, 94, 95, 144) placed between the two portions, the opening thus provided being substantially wider than the thickness of the card, the mutual approximation of the portions being provided by the mechanical devices at the final part of the card's insertion travel.
15 citations
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18 Sep 1995TL;DR: In this article, a continuous belt edge detector was proposed for use in a paper making machine having a continuous Belt guide device. But the inductive sensor sent a signal to the guide device indicative of a location of the continuous belt, i.e., transversely relative to the running direction of the belt within the machine.
Abstract: The invention is directed to a continuous belt edge detector system for use in a paper making machine having a continuous belt guide device. The edge detector system comprises a continuous belt having an edge dope with metallic particles therein and an inductive sensor connected to the guide device and adjacent the edge dope. The inductive sensor sends a signal to the guide device indicative of a location of the continuous belt. The guide device moves the continuous belt, e.g., transversely relative to the running direction of the belt within the machine, dependent on the inductive sensor signal.
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25 May 1995
TL;DR: In this article, the rotational speed of a magnet wheel is measured using the square wave signal generated by the magnet wheel and a comparator connected downstream of the filter and therefrom into a signal that is essentially proportional to the rotation speed of the wheel.
Abstract: A method and a device for detecting rotational speed with an inductive sensor in which a sinusoidal potential is induced by a magnet wheel and then fed to a filter with a comparator connected downstream of the filter and therefrom into a square-wave signal that is essentially proportional to the rotational speed of the magnet wheel. This output signal of the comparator is evaluated in a microcomputer. In this evaluation, only the same type of edges of the comparator signal are evaluated, specifically those in which the intervals fluctuate less when considered over a certain time span. The microcomputer here can initially evaluate both types of edges, that is, positive and negative edges, and then use those edges in which smaller fluctuations, that is, interference, are determined for calculating the rotational speed. The microcomputer can also first evaluate only one type of edges and change over to edges of the other type only if the former displays interference above a present value. If the edges of the other type show even greater interference than those of the first type, then the system switches back to the first type. The changeover can be done either in the microcomputer or externally. The external changeover to the type of edge can be done by an external inverter or by reversing the polarity of the sensor output signals by means of a controllable switch.
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25 May 1995TL;DR: In this article, an inductive sensing element for sensing displacement of a resilient flexible beam or diaphragm is presented. But the parameters of both the open and closed faced members are selected so that the self-inductance of the open faced member is determined by the overall distance separating the members.
Abstract: An inductive sensing element for sensing displacement of a resilient flexible beam or diaphragm. The inductive sensing element comprises an open faced member and a closed faced member one of which is attachable to the flexible beam and the other of which is attachable to a stationary member. The parameters of both the open and closed faced members are selected so that the self-inductance of the open faced member is determined by the overall distance separating the members. Both the open and closed faced members have a magnetic coating and the open face member further comprises an electrically conductive coating arranged in a predetermined pattern on its magnetic coating. The self- inductance of the open faced member, in particular, the predetermined pattern, is dependent upon the magnetic coating on the open faced member and the magnetic contribution that the magnetic coating of the closed faced member makes to the magnetic coating of the open faced member which, in turn, is dependent upon the overall distance separating the open and closed faced members.
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17 Oct 1995
TL;DR: In this paper, the distance between sensing coil L1 and object is measured by the pulse width proportional to the phase-shift Ph 1 between the coil current and voltage, where the Schmitt trigger can be added to introduce hysteresis in the switch point.
Abstract: The distance between sensing coil L1 and object is measured by the pulse width proportional to the phase-shift Ph1 between the coil current and voltage. An analogue comparator K1 measures the coil voltage relative to a reference dc voltage and switches a logic gate when the coil voltage becomes larger or smaller than the reference. A second comparator K2 measures the voltage across a reference impedance Zref relative to a second dc voltage and switches a gate. The output from K1 and the inverted K2 output are fed into a logic gate which generates a pulse sequence F of pulse width proportional to the phase-shift at the oscillator frequency. A Schmitt trigger can be added to introduce hysteresis in the switch point.
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23 Nov 1995TL;DR: In this paper, a device for sensing the displacement of working members in industrial equipment is disclosed. But, the sensor housing of the device easily fixes the analog inductive sensor by fitting the sensor into a mount hole formed in the housing, thereby easily changing the troubled sensor with a new one and easily focusing the sensor when initially mounting the sensor to the housing.
Abstract: A device for sensing the displacement of working members in industrial equipment is disclosed. The above sensing device includes cheap analog inductive sensors capable of maintaining the sensing characteristics irrespective of moisture and leaking water, thereby precisely sensing the displacements of the working members. The sensor housing of the device easily fixes the analog inductive sensor by simply fitting the sensor into a mount hole formed in the housing, thereby easily changing the troubled sensor with a new one and easily focusing the sensor when initially mounting the sensor to the housing. As a pair of analog inductive sensors are mounted to both side surfaces of the working member, the sensing device of this invention also prevents the operational errors to the sensors caused by the operational vibrations of the working members while sensing the displacements of the working members.
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04 Apr 1995TL;DR: In this article, a tuning device is connected in parallel with the oscillatory circuit, which is a variable gain amplifier with feedback via an inductive or capacitive impedance, and the tuning device can be used to tune the oscillator at a constant frequency.
Abstract: A proximity sensor includes a coil for sensing metal objects which are part of an oscillatory circuit and an oscillator which drives the oscillatory circuit at a constant frequency. A tuning device is connected in parallel with the oscillatory circuit. The tuning device is a variable gain amplifier with feedback via an inductive or capacitive impedance.
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22 Feb 1995
TL;DR: In this article, a system for sensing a position of a body rotating about an axis, the system including at least one inductive sensor positioned in proximity to the body, each of the sensors providing an output; material forming part of the body for effecting a variation in the output of the at least 1 sensor as a function of axial movement relative to the axis.
Abstract: A system for sensing a position of a body rotating about an axis, the system including at least one inductive sensor positioned in proximity to the body, each of the at least one inductive sensor providing an output; material forming part of the body for effecting a variation in the output of the at least one inductive sensor as a function of axial movement of the body relative to the axis; circuitry for analyzing the output of the at least one inductive sensor to produce a system output indicative of the axial movement.
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30 Mar 1995
TL;DR: In this paper, an inductive sensor device consisting of an electric coil and an assigned core which is arranged in a housing consisting of a ferromagnetic material and is likewise produced from a ferrous material is presented.
Abstract: A proposal is made for an inductive sensor device which consists of an electric coil and an assigned core which is arranged in a housing consisting of a ferromagnetic material and is likewise produced from a ferromagnetic material. For the purpose of detecting angular positions or changes in angle of rotating machine parts, in the device the coil is arranged on a rectangular coil former (form) which is provided at its centre with an elongated cutout (opening) extending in the direction of its longitudinal axis. The housing opening assigned to the cutout is of a length and width which roughly correspond to the length and width of the cutout, and the core is designed as a configured plate and is assigned to the cutout or the housing opening via a rotating part which is aligned at right angles to the plate and mounted eccentrically thereon.
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23 Feb 1995
TL;DR: In this paper, a rectangular pole shoe stack (7) is inserted into the injection mold when the housing of the inductive sensor is moulded, and a coil former with a coil (14) is pushed over these plastic layers.
Abstract: In an inductive sensor, plastic layers (11, 12) are provided on the side faces of a rectangular pole shoe stack (7) which layers are created by inserting the pole shoe stack (7) into the injection mould when the housing (1) of the inductive sensor is moulded A coil former (13) with a coil (14) is pushed over these plastic layers (11, 12) and then the coil former (13) is ultrasonically welded to the plastic layers (11, 12)
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01 Jun 1995
TL;DR: In this article, an electronic evaluation unit for measuring the flow of fluids in pipes is presented, which consists of an inductive sensor for flow rates of 0.5 to 5.0 m/sec and a calorimetric sensor for rates below 1m/sec.
Abstract: An electronic evaluation unit for measuring the flow of fluids in pipes (1) e.g. water incorporates an inductive sensor (2) for flowrates of 0.5 to 5.0 m/sec. and a calorimetric sensor (3) for rates below 1m/sec. The calorimetric sensor (3) output is linearised in the module (4) and the inductive sensor (2) output is decoupled/amplified in the module (6). The signals are combined in an addition unit (5) and a single output related to flow is obtained in the form of a proportional current signal of 0 to 20 mA or via a frequency converter calibrated to generate a pulse for each cubic metre of flow.
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10 Aug 1995
TL;DR: In this article, a movable contact on an arm is used to activate an external indicator to indicate overload or short circuit conditions, which activates an external sensor that responds to the contact.
Abstract: The switch has a movable contact [16] on an arm [15] that normally sits against a fixed contact [21]. The switch has two contact terminals [12,13] that are connected [23,28] to an arc extinguishing plate stack [24]. Operation of the movable contact is made by an electromagnetic actuator [18] with input from a bimetallic element [26] that responds to overload or short circuit conditions. Built into the terminal is an inductive sensor [30] that responds to the movable contact. This activates an external indicator.
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08 Mar 1995
TL;DR: In this article, an inductive sensor has two or three coils (1,3,5) positioned in the effective range of a damping plate (31), attached to the shaft (30), each coil connected in circuit with a capacitor (2,4,6) for forming a measuring oscillator receiving resonance pulses (P1,P2,P3) of defined length.
Abstract: The inductive sensor has 2 or 3 coils (1,3,5) positioned in the effective range of a damping plate (31), attached to the shaft (30), each coil connected in circuit with a capacitor (2,4,6) for forming a measuring oscillator receiving resonance pulses (P1,P2,P3) of defined length. A Schmitt trigger (7,8,9) converts the sinusoidal oscillations into rectangular pulses fed to a counter (21,22), with a further counter indexed by measuring pulses (Pm) provided by a measuring oscillator (Om), to provide a reference threshold for the count values (Z1,Z2) fed to a decoder providing the shaft revs (n) and rotation direction (Ri).
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TL;DR: In this paper, a planar transformer is used for a two-coil proximity sensor, where the primary and secondary coils are fabricated on a micromachined membrane to protect the primary coil from the environment.
Abstract: Here we present results for a new inductive proximity sensor that makes use of two coupled coils, forming a planar transformer, fabricated on a micromachined membrane. Macroscopic proximity sensors based on eddy-current techniques are currently commercially available. However, their design is not conducive to scaling inductor. When such an inductor is scaled down and made planar, the inductance decreases while the resistance of the coil increases dramatically. This dictates that the sensor be operated at much higher frequencies for which the inductance of the coil dominates its resistance. In our new two-coil design a signal is applied across the primary coil and a significant sensitivity to the gap to the 'target' plate is seen in the phase difference between the primary and secondary output. This phase change is largely invariant with change in coil resistance (due to either temperature change or change due to scaling to IC levels), allowing operation at lower frequencies than that required for a single coil proximity sensor. By fabricating the transformer on the back side of a micromachined membrane, the coil is protected from the environment, while the deleterious effect of the silicon substrate on inductance is eliminated.
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25 Oct 1995
TL;DR: In this article, an inductive sensor is mounted on a lateral edge of the shield which detects tye guide edges of the guide rail, and a controller with a sensor mounted on the door plate detects the position of the sensor wrt.
Abstract: The roller door has a flexible, non-metallic hanging part (2) with a lower closure edge which rests tight against a base surface in the closed position and which has a shield (7) with a guide element (11) which runs in a lateral guide rail (9). The shield is deflected out of the door opening plane by a force acting upon on the door plate. A controller with a sensor (14) mounted on the door plate detects the position of the sensor wrt. the guide rail. The sensor can be an inductive sensor mounted on a lateral edge of the shield which detects tye guide edges of the guide rail.
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27 Feb 1995TL;DR: In this paper, the phase and amplitude detector/comparator (20,21,21), discrimination logic (18,19), and an output stage (19,20) are used to detect ferrous and non-ferrous metals.
Abstract: The detector portion (11) of the circuit contains a resonant circuit (13) excited by an oscillator (15) at constant subcritical frequency and amplitude, with a tuning circuit (16) and a high impedance (17) ensuring constant excitation current. The processing portion (12) comprises phase and amplitude detector/comparators (20,21), discrimination logic (18) and an output stage (19). The proximity of ferrous and non-ferrous metals (14) gives rise to different signals (S2,S4) on separate output lines (SM1,SM2). A ferrous object is discerned when the phase-shift signal (S2) is active while a damping signal (S3) from the amplitude comparator (21) is inactive.
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08 Apr 1995
TL;DR: In this paper, the inductive sensor (11) has a coil (14) with a formed core (22), the core has a cylindrical section, a second cylinrical section of smaller diameter with a conical section between the two cylinders, and a further third cyline section of still smaller diameter, the profile is of a cross section matching the rotating teeth of the rotating engine part.
Abstract: The inductive sensor (11) has a coil (14) with a formed core (22). The core has a cylindrical section, a second cylindrical section of smaller diameter with a conical section between the two cylindrical sections and a further third cylindrical section of still smaller diameter.The core may be made by a cold forming process. The third cylindrical section profile is of a cross section matching the rotating teeth of the rotating engine part. The material used is steel X6 Crl 7, e.g. high alloy steel 17 percent chrome.
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10 Nov 1995
TL;DR: In this paper, a phase detector is used to make high-reliability identification by inputting the voltage signal of a resonance circuit driven at the subcritical excitation frequency, outputting the phase shift signal when the phase is the threshold value or above, and transmitting the signal indicating a nonferrous metal or a ferrous metal respectively depending on whether the signal is the active state or inactive state.
Abstract: PURPOSE: To make high-reliability identification by inputting the voltage signal of a resonance circuit driven at the subcritical excitation frequency to a phase detector, outputting the phase shift signal when the phase is the threshold value or above, and transmitting the signal indicating a nonferrous metal or a ferrous metal respectively depending on whether the signal is the active state or inactive state. CONSTITUTION: A resonance circuit 13 containing a coil acted on a metal 14 via inductance L and a capacitance C has an impedance ZLC, and it is driven by a constant- amplitude oscillator 15 at the fixed frequency of the critical frequency (about tens kHz) or below. A constant exciting current flows in the circuit 13 at a high impedance 17 (R>>ZLC). The signal S0 of the oscillator 15 and the voltage signal S1 of the circuit 13 are inputted to a phase detector 20, the phase difference is compared with the threshold value, and the phase shift signal S2 is outputted when the phase difference exceeds the threshold value. A phase detector 21 compares the signal S1 with the other threshold value and outputs the brake signal S3 when the signal S1 is the threshold value or below. A discriminating logic 18 feeds the signal S2 or S4 indicating a nonferrous metal or a ferrous metal based on the signal S2 , S3 to an output circuit 19 and drives a display device.
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25 Jun 1995TL;DR: In this article, the authors analyzed the problem of scaling down an inductive proximity sensor made of superposed multiple-turn flat coils and linearly scaled down all geometrical dimensions.
Abstract: SUMMARY We analyze the problem of scaling down an inductive proximity sensor made of superposed multiple-turn flat coils. We linearly scale down all geometrical dimensions. Then the nominal inductance is scaled down proportionally to the scale factor. The coupling factor of the superposed coils remains constant. However for both ferromagnetic and non-ferromagnetic targets, the sensitivity remains constant when the frequency is scaled by the inverse square of the reduction factor. But the parasitic effects in the sensor coil become more important for small device dimensions. Therefore these effects are expected to set the ultimate limit in the miniaturization of the integrated inductive proximity sensors.
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31 Aug 1995TL;DR: In this article, an inductive proximity sensor (10) placed in the vicinity of a rotating element (A) was used to generate an electric pulse (100) upon each revolution of the element, and an optical-fibre link was connected to this sender (20) and to a receiver (40) in order to use it so as to calculate the speed of the rotating element.
Abstract: The pulse tachometer for measuring the rotation of a rotating element (A) is characterized in that it comprises an inductive proximity sensor (10) placed in the vicinity of this element (A) in order to generate an electric pulse (100) upon each revolution of the element (A), a sender (20) connected to this sensor (10) for receive this electric pulse (100), shaping it and converting it into an optical signal, an optical-fibre link (30) connected to this sender (20) and to a receiver (40) for receiving this optical signal from the sender (20) and routing it to this receiver (40) in order to use it so as to calculate the speed of the rotating element. Application to rotating machines, for example turbine generators.
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31 May 1995
TL;DR: In this article, a control device uses a sensor that detects the rotation of one of the counter-pressure rollers cooperating with the driven transport rollers for the printing plate to indicate the feeding of a printing plate during the automised plate changing procedure.
Abstract: of EP0692379The control device uses a sensor (9) detecting the rotation of one of the counter-pressure rollers (2) cooperating with the driven transport rollers (4) for the printing plate (5), to indicate the feeding of the printing plate during the automised plate changing procedure. Pref. the counter-pressure roller has a measuring cuff (8) with peripheral slits in the form of a crown ring, the sensor provided by an inductive proximity sensor, providing a signal when the measuring cuff is rotated together with the counter-pressure roller.