Showing papers on "Inductive sensor published in 2010"

Electronic devices with capacitive proximity sensors for proximity-based radio-frequency power control

Abstract: An electronic device may have a housing in which an antenna is mounted. An antenna window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. Near-field radiation limits may be satisfied by reducing transmit power when an external object is detected in the vicinity of the dielectric antenna window and the antenna. A capacitive proximity sensor may be used in detecting external objects in the vicinity of the antenna. The proximity sensor may have conductive layers separated by a dielectric. A capacitance-to-digital converter may be coupled to the proximity sensor by inductors. The capacitive proximity sensor may be interposed between an antenna resonating element and the antenna window. The capacitive proximity sensor may serve as a parasitic antenna resonating element and may be coupled to the housing by a capacitor.

Circuits and Methods for Generating a Self-Test of a Magnetic Field Sensor

Abstract: A magnetic field sensor includes built in self-test circuits that allow a self-test of most of, or all of, the circuitry of the magnetic field sensor, including self-test of a magnetic field sensing element used within the magnetic field sensor, while the magnetic field sensor is functioning in normal operation.

A Combined Inductive–Capacitive Proximity Sensor for Seat Occupancy Detection

Abstract: This paper presents a simple and efficient seat occupancy detector. A seat occupancy detector is an integral part of the airbag safety system and, in its simplest form, provides the (occupied or vacant) status of the seat to the airbag control unit. Although the occupancy sensing methods based on a capacitive principle are efficient, they typically require electrodes to be placed in the surface layer of the sitting and backrest areas of the seat. The proposed sensor uses a simple electrode structure, and it is placed below the seat foam in the sitting area of the seat. These features promise a less-expensive sensor as it can be easily manufactured and installed in a seat. The new sensor combines inductive and capacitive proximity sensing principles. The sensor detects the presence of an occupant exploiting the shielding effect of the electric field while its inductive proximity feature senses the presence of conductive objects (e.g., laptop) that may be placed in the seat and helps to achieve reliable occupancy sensing. The measurement system uses a signal conditioning unit based on a carrier frequency principle. A prototype sensing system has been built, and its application as a seat occupancy sensing system in a vehicle has been verified. The developed system successfully senses human proximity and distinguishes it from other conductive objects.

Capacitive -inductive touch screen

Abstract: A touch screen uses a combination of capacitive sensing and inductive sensing applied to the same sensor pattern. A capacitive sensor uses the electric field formed by the columns and rows of the sensor matrix. An inductive sensor uses the magnetic field formed by current flowing in column and row lines to induce an inductive pen. Using the same sensor lines, the magnetic field created by the oscillating inductive pen is detected. Both methods require no moving elements in the sensor and it is possible to combine both method of detections in the same sensor pattern. Using switch matrices, the sensor lines are operated in an open loop fashion for the capacitive detection mode, and are operated in a closed loop fashion for the inductive detection mode.

Augmented reality proximity sensing

Abstract: Technologies are generally described for employing proximity sensing mechanisms in augmented reality (AR) systems. Sensors strategically placed on AR eyeglasses in locations such as right and/or left arms, bridge, or flip-up feature of the eyeglasses may be used to detect AR eyeglass usage for power management and/or to provide user interface elements like volume control, display controls, user input, and comparable ones. According to some examples, the sensors may be mechanical sensors, capacitive sensors, optical sensors, inductive sensors, magnetic sensors, and/or similar components.

A new MEMS sensor for AC electric current

Abstract: This paper presents new results in the testing and characterization of a MEMS sensor for AC electric current. The sensor is comprised of a piezoelectric MEMS cantilever with a microscale permanent magnet mounted to its free end. When placed near a wire carrying AC current the magnet couples to the oscillating magnetic field around the wire, deflecting the cantilever and generating a sinusoidal voltage proportional to the current. Unlike inductive sensors, this sensor does not need to encircle the conductor and it can measure current in a two-wire “zip-cord”. It is also self-powered, and is thus more suitable for wireless sensor node applications than a powered sensor device. The theoretical basis of this new sensor's operation is presented, as well as the fabrication of a MEMS sensor device, and the first test results of this new sensor measuring current in single-wire and two-wire conductors. Sensor response is linear (R2 > 0.99) with sensitivity in the range of 0.1–1.1 mV/A. An integrated self-powered sensor device is also presented, which employs a piezoelectric energy harvester to power the sensor's signal conditioning circuitry at a 2.6% duty cycle.

A tactile proximity sensor

Abstract: This paper introduces a novel tactile sensor with the ability to detect objects in the sensor's near proximity. For both tasks, the same capacitive sensing principle is used. The tactile part of the sensor provides a tactile sensor array enabling the sensor to gather pressure profiles of the mechanical contact area. Several tactile sensors have been developed in the past. These sensors lack the capability of detecting objects in their near proximity before a mechanical contact occurs. Therefore, we developed a tactile proximity sensor, which is able to measure the current flowing out of or even into the sensor. Measuring these currents and the exciting voltage makes a calculation of the capacitance coupled to the sensor's surface and, using more sensors of this type, the change of capacitance between the sensors possible. The sensor's mechanical design, the analog/digital signal processing and the hardware efficient demodulator structure, implemented on a FPGA, will be discussed in detail.

Modification of the Maxwell–Wien Bridge for Accurate Measurement of a Process Variable by an Inductive Transducer

Abstract: The small inductance of an inductive transducer generally linearly changes with a process variable, but their measurement by the usual inductive bridge circuit like the Maxwell bridge, the Maxwell-Wien Bridge, the Hay bridge, etc., suffers from errors due to the effect of the stray capacitance between bridge nodal points and the ground and the stray inductance on the inductive coil, respectively. The conventional Wagner-Earth technique is not suitable for continuous measurement. In this paper, a modified operational-amplifier-based Maxwell-Wien bridge measurement technique has been proposed in which the effect of stray capacitance and inductance is minimized. In the first phase of the experiment, the bridge performance has been studied with a known variable inductor, and in the second phase, the same experimentation was done by replacing the variable inductor with an inductive coil having an adjustable core position for the measurement of displacement. The linear characteristics over a wide range of displacement with good repeatability, linearity, and variable sensitivity have been described.

Wireless temperature sensing using temperature-sensitive dielectrics within responding electric fields of open-circuit sensors having no electrical connections

Abstract: All temperature sensors or sensor systems previously developed have one common feature-–the sensors are part of electrically closed circuits and electrical connections are used to form the closed circuits. Using existing frameworks for designing, powering and interrogating sensors, any damage that ruptures the circuit can render the sensor non-functional. In many damage events, it is necessary to identify that the damage has occurred and also continue the measurement. In this paper we report a new temperature sensing method that uses a recently developed technique for designing, powering and interrogating sensors developed at NASA. In lieu of sensors being a collection of components assembled using electrical connections, the open-circuit sensors are patterns of electrically conductive material that can store electric fields and magnetic fields without electrical connections. These sensors are powered using oscillating magnetic fields and respond with their own electric and magnetic fields whose signatures provide temperature information. Because no electrical connections are used, there is no point on the sensor that if damaged renders the sensor non-functional. Damage to the sensor simply shifts the sensor's frequency range, allowing it to continue measurement while damaged. Temperature-sensitive dielectric material is placed within the sensor's responding electric field to modulate the sensor's resonant frequency. Temperature sensitivity and functional temperature range are dependent upon the temperature-sensitive material used and how it is placed within sensor's responding electric field. The principle and design strategies of the open-circuit temperature sensors are discussed and experimental results are presented.

Display Device Provided With Touch Sensor, Electronic Apparatus Using Same, And Control Circuit Of Display Module Provided With Touch Sensor

Abstract: Multiple sensor electrodes are formed such that they overlap a display panel, and each have an electrostatic capacitance that changes according to the user's touch. Furthermore, a proximity sensor electrode pair is formed as a transparent electrode such that they overlap the display panel. An electrostatic capacitance detection circuit detects change in the electrostatic capacitance of each sensor electrode due to the user's touch, thereby detecting a position touched by the user. A proximity detection circuit detects change in the electric field generated between the proximity sensor electrode pair due to the proximity of the user, thereby detecting the proximity of the user to the display panel. An electrostatic capacitance detection circuit is configured to have at least a component that is switchable between an operating state and a non-operating state. When detecting that the user is in proximity, this component transits from the non-operating state to the operating state.

Sensor device and information processing device

Abstract: A sensor device is provided which includes a pressure-sensitive sensor which changes shape in response to pressing of an operation tool and which detects change in capacitance due to the change in shape, and a barrier which covers at least a part of the pressure-sensitive sensor and which prevents change in capacitance of the pressure-sensitive sensor due to capacitive coupling that occurs with approach between the pressure-sensitive sensor and the operation tool.

Sensor device, method of driving sensor element, display device with input function and electronic unit

Abstract: A sensor device includes sensor elements arranged in a matrix form, and a sensor driving section driving the sensor elements. Each of the sensor elements includes a photoelectric conversion element generating electric charge, a storage node storing electric charge, to show a voltage which fluctuates according to the stored electric charge, a reset transistor resetting the voltage in the storage node and a readout section reading the voltage value resulted from the stored electric charge in the storage node, to output the resultant voltage value. The sensor driving section controls the reset transistor so that the storage nodes of the sensor elements over sensor element lines are reset into the predetermined reset voltage at a time, and then performs read control after a lapse of a predetermined exposure period to allow the sensor detection signals to be sequentially outputted from the respective sensor elements arranged in each sensor element lines.

Partial discharge pulse shape recognition using an inductive loop sensor

Abstract: Partial discharges (PD) are a clear ageing agent on insulating materials used in high-voltage electrical machines and cables. For this reason, there is increasing interest in measuring this phenomenon in an effort to forecast unexpected failures in electrical equipment. In order to focus on harmful discharges, PD pulse shape analysis is being used as an insulation defect identification technique. In this paper, a simple, inexpensive and high-frequency inductive loop sensor will be used to detect and acquire PD pulses. Several measurements will be made on some controlled test cell geometries in order to characterize PD pulse shapes for different discharge sources. The sensor identification capability has been checked in an insulation system where two simultaneous PD sources were active.

Modelling and simulation of an inductive displacement sensor for mechatronic systems

Abstract: The paper presents design, simulation, implementation and testing of an inductive displacement sensor based on a Linear Variable Differential Transformer (LVDT) controlled by a single chip electronic module with 16 bit RISC microcontroller. LVDT device is widely used in hydraulic and pneumatic mechatronic systems for measuring physical quantities like displacement, force or pressure; it consists of two magnetic coupled coils with a common moving core; its displacement is converted in reluctance variation of magnetic circuit. Standard electronics for LVDT sensor conditioning is analog - quadrate oscillator, synchronous demodulator and amplifiers - but has its drawbacks – relative complex, hard to adjust, many components and packages, no connection to computer systems. The originality aspects of the work come from the unique method of finding displacement information by switching supply voltage in the coils of inductive device. This method uses only peripherals from a microcontroller so is low cost and easy to adjust. Present paper focuses on modelling and simulation of displacement measuring method but analyzes also implementation aspects for a real application (an electro hydraulic position control system).

Evaluation of the planar inductive magnetic field sensors for metallic crack detections

Abstract: The planar inductive magnetic field sensors were fabricated by photolithography process. The sensor was composed of the planar coils (42 turns and 120 turns) with magnetic thin film as a core. To evaluate the sensor for crack detection, the nonmagnetic Al and magnetic FeC specimens were prepared with the circular and slit shaped artificial surface cracks. The alternative current (0.1 A to 1.4 A) with frequency range of 1.0–2.0 MHz was generated by the straight shaped driving Cu coil. In the case of 120 turns of planar inductive magnetic field sensor, the induced signals on crack positions exhibited the high intensities and stable signal to ratio as varying the driving current and frequency in comparison with those of 42 turns of planar inductive sensor. The measured output signals on FeC specimen with the micro-sized surface crack by the non-contacted scanning were converted to the image which was compared with that of the optical image, respectively.

Robust sensing of human proximity for safety applications

Abstract: This paper presents a robust capacitive proximity sensor that facilitates the safety features of power tools. Power tools (e.g. pneumatic metal forming machines) enable easier and faster work but they can also cause severe injuries, if not operated carefully. However, accidents and related injuries can be prevented to a large extent by providing an automatic shut-off functionality. In order to realize such a functionality, a sensing mechanism which detects the presence of a human in the dangerous working areas of the power tool is necessary. A capacitive sensor which is suitable for this application has been developed. In most of the cases, the tools are made of metallic parts and have good electrical conductivity. Typically, the tools have a fixed part and a movable part. In the proposed scheme, the proximity sensor is attached to the movable part of the tool. Depending on the position of the movable part, changes of the electric field distribution across the electrodes will occur. Hence, comparatively large changes of the sensor capacitance are introduced compared to a capacitance change for the presence of a human hand. The current position of the movable part and the prior knowledge of the capacitance values for a vacant condition are used to solve this issue. The practicality of the proposed sensor system is demonstrated with detailed simulation studies and results from the measurements conducted with a prototype sensor installed on a typical metal forming machine.

A vehicle classification based on inductive loop detectors using artificial neural networks

Abstract: This paper presents a classifier based on a net neural MLP (Multiple Layers Perceptron) using the algorithm of Levenberg-Marquardt to do the identification of the load of vehicles through the magnetic profile collected in equipment of control of traffic.

Measuring apparatus for measuring bearing and its part surface appearance

Abstract: A measuring apparatus for measuring surface topography of bearing and other parts comprises a pedestal (1), an absolute encoder (2), a ball screw (3), an X-axis sliding guide track device (4), an X-axis limit switch (5), an X-axis signal collection grating (6), a driving box supporting plate (7), a sensor driving box (8), an upright guide track (9), a Z-axis motor (10), a Z-axis manual adjusting knob (11), an X-axis motor (12), an X-axis belt wheel and cog belt (13), an inductive sensor device (14), a sensor coupling rod (15), a multi-dimensional workbench (16) and an electrical system. The invention can measure more than 100 parameters, including profile, waviness, roughness, peak height, valley deepness, total height, average deviation, gradient, slope, bearing length ratio and others; provides detection reference for users to perform various technical analyses to the workpiece to be measured; and can add certain measurement parameter at any time according to the requirement of users.

Arrangement comprising an inductive proximity sensor, and method implementing such a sensor

Abstract: An electronic circuit detecting proximity includes an excitation coil emitting an inductive excitation field toward a target. A first pair of detection coils obtains a first differential inductive signal that is modified by a transition of the target within the inductive field. An out-of phase second pair of detection coils obtains a second differential inductive signal that is modified by a transition of the target within the inductive field. A comparator generates a transition signal when the difference between the first and second differential signals reaches a threshold value. A stationary target, in a ferromagnetic or conductive material, creates an offset to the signals at the outlet of the coil pairs. The offset is decreased during the presence of a movable target within the same type of material or increased during the presence of a movable target within another type of material. A comparator detects the offset level.

Whole body and spine chiropractic massager

Abstract: The present invention relates to whole body and spine chiropractic massagers (including retractors), and more specifically, to a whole body and spine chiropractic massager which enables accurate treatment by automatically sensing a target treatment position even if an original treatment n position that was set during the spinal retraction phase has changed, the sensing operation being performed by a sensing part attached to a user's body, or by a sensor installed at a massager or indicator lamp disposed in the bed. In particular, a whole body and spine chiropractic massager 1 according to the present invention comprises an inductive proximity sensor 4 that is selectively installed at a massager roller 3 or indicator lamp 6 disposed in a bed 2 of the whole body and spine chiropractic massager 1 in such a way as to be able to elevate and horizontally reciprocate; and a sensing part 5 formed of a metallic plate, the sensing part being removably attached to a target treatment area of a patient, such that the inductive proximity sensor 4 together with the sensing part 5 may sense a body area to be treated. Such a whole body and spine chiropractic massager of the present invention performs massage and chiropractic adjustment treatment by virtue of accurate sensing of a taret treatment area even if an original treatment area has been displaced while retracting the spine of a patient, wherein the accurate sensing is offered by an inductive proximity sensor selectively installed at a massage roller or indicator lamp disposed in the bed and of a sensing part attached to a treatment area. As such, with the present invention, accurate treatment can be effected regardless of a change in the treatment area on the bed due to the spinal retraction.

Detection of proximity between a sensor and an object

Abstract: An apparatus includes a sensor having a heater. The apparatus also includes a proximity detection component that analyzes a sensed signal, obtained from the sensor during application of an alternating current signal to the heater of the sensor, and responsively provides an output indicative of whether proximity exists between the sensor and an object that causes the sensor to produce the sensed signal.

Inductive sensor module for a vehicle and method for operating such a sensor module

Abstract: The invention relates to a sensor module for a vehicle safety system and to a method for actuating such a sensor module for a vehicle safety system, wherein data are wirelessly transmitted by at least one transmitter of the sensor module according to a sensor signal. The sensor module uses a generational measurement principle so that the energy for the operation of the sensor module is generated by said measurement principle. The data are stored in a memory in the sensor module, and a control device reads out said data according to at least one vehicle variable (e.g., speed) and/or event (e.g., slipping, blocking) and transmits said data.

An Axial Position Sensor for Active Magnetic Bearings

Abstract: Inductive sensors commonly used in Active Magnetic Bearings (AMBs) comprise soft-magnetic cores on stators and sensor targets on rotors. The rotor position is estimated based on values of inductances of sensor coils wound around the cores. These sensors are often easier to use than eddy-current sensors, but their readings can be affected by stray magnetic fields from AMB actuators. For radial sensors this problem can be mitigated by using two diametrically-opposite sensor heads in differential connection, however, the same cannot be done for axial sensors. In addition, the axial sensors often need to be located as close as possible to axial actuators, where the stray fields are higher, in order to minimize changes of the actuator operating gaps caused by differences in thermal expansions of the rotor and the stator. The axial sensor presented in this paper has been developed to address primarily the issue of sensitivity to external fields. The closest kin of the proposed sensor is the axial inductive edge sensor. Because the magnetic excitation flux in the new sensor is maintained nearly constant during the operation, it was given a name “a constant-flux edge sensor”. A prototype of the new sensor has been built and tested.Copyright © 2010 by ASME

Enhanced Performance Proximity Sensor

Abstract: An industrial control sensor is provided. The sensor includes a sensor circuit to detect changes in an electromagnetic field induced from an object or material passing in proximity of the electromagnetic field. This includes a housing that employs the sensor circuit as part of an inductive proximity sensor. A sensor face is attached to the housing, where the sensor face receives the changes in the electromagnetic field and transmits the changes to the sensor circuit, and where the sensor face has a higher electrical resistivity or a lower temperature coefficient of resistivity than stainless steel.

Double-coil inductive proximity sensor apparatus

Abstract: Systems and/or methods are provided for a dual-channel inductive proximity sensor. The sensor can include a sensing element which includes a core having a first cavity and a second cavity, a first coil accommodated within the first cavity of the core, and a second coil housed within the second cavity of the core. Each coil can be independently driven by oscillators to generate respective magnetic fields. The magnetic fields can be monitored to determine whether detection of a target object occurs.

Linear position sensor

Abstract: The invention relates to the field of position sensors, especially to the field of so-called inductive sensors. The device according to the invention comprises a track provided with a primary winding (513) fed by a high-frequency alternating current, and a plurality of secondary windings (511, 512). The device measures the position of the leading edge (510) of a target (500), in a so-called longitudinal direction (5000) between a first position and a second position between which the target (500) entirely covers the track (550). Surprisingly, said configuration enables the useful measuring length of such a track (550) to be very slightly increased.

System and method for providing electromagnetic imaging through electroquasistatic sensing

Abstract: A system and method for providing electromagnetic imaging through electroquasistatic sensing contains an electromagnetic sensor for imaging a sample. The electromagnetic sensor contains drive/sense electronics and a pixelated sensor array having an array of capacitive sensor electrodes that source electric fields that interact with the sample, and wherein the electrodes are individually drivable by the drive/sense electronics in a coordinated manner to establish a desired temporal and spatial pattern in which electrical properties of the electrodes are used to generate an image. Other components of the system include a precision motion controller, sensor head and associated electronics, and a computer for performing data acquisition and signal inversion.

Apparatus for preventing unauthorized use of a vehicle

Abstract: An apparatus for protecting a vehicle includes a fob in the possession of a person who whishes to use the vehicle. The fob includes a fob code. A proximity sensor mounted on the vehicle is used to actuate circuitry for interrogating the fob so as to retrieve the fob code. The fob code is then matched to a vehicle code to determine whether the person possessing the fob is authorized to use the vehicle. The proximity sensor may include a capacitive sensor, and inductive sensor, or both.

Interactions of an eddy current sensor and a multilayered structure

Abstract: A study of the interactions between a cup-core eddy current sensor and a metallic layered structure is reported. An affine relationship between the sensor's normalised impedance and the distance between two plates of a metallic assembly is brought to light both by the experiment and by finite elements computations.