Abstract: Any inspection object regardless of material can easily be inspected or discriminated with high accuracy and high sensitivity by being placed in a magnetic field generated by applying an alternating current to an exciting coil and detecting changes of voltage level and phase of electromotive force induced by a detection coil unit. The discrimination of the inspection object is performed on the basis of a DC voltage value with respect to a standard specimen and a phase differential voltage value with respect to a phase difference between the phase of a voltage signal from the induction coil and the phase of the exciting current to the exciting coil.

Abstract: The present invention relates to a substrate polishing apparatus and a substrate polishing method for polishing a substrate such as a semiconductor wafer to a flat finish. The substrate polishing apparatus includes a polishing table (100) having a polishing surface (101), a substrate holder (1) for holding and pressing a substrate (W) against the polishing surface (101) of the polishing table (100), and a film thickness measuring device (200) for measuring a thickness of a film on the substrate (W). The substrate holder (1) has a plurality of pressure adjustable chambers (22 to 25), and pressures in the respective chambers (22 to 25) are adjusted based on the film thickness measured by the film thickness measuring device (200).

Abstract: An arrangement and a method for detecting and/or locating magnetic material, and the use of an arrangement in the examination of buildings is disclosed, which arrangement comprises: selection means for generating a magnetic selection field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength and a second sub-zone having a higher magnetic field strength are formed in the region of action, drive means for changing the position in space of the two sub-zones in the region of action by means of a magnetic drive field so that the magnetization of the magnetic material changes locally, receiving means for acquiring detection signals, which detection signals depend on the magnetization in the region of action, which magnetization is influenced by the change in the position in space of the first and second sub-zone, wherein the magnetic selection field comprises at least a time-variable field component varying at a frequency of at least about 100 Hz.

Abstract: A metal detection device is capable of effectively detecting a metal mixed in food or the like by generating AC magnetic field simultaneously tuned to respective frequencies by a single transmission coil in response to frequency components of different frequencies without switching an element by a switch or the like. Constituent elements constituting magnetic field generation portion are connected so that a transmission coil L1 and a capacitor C1 resonate in the first frequency F1. Moreover, constituent elements are connected so that the transmission coil L1 and a capacitor C2 resonate in the second frequency F2. Furthermore, constituent elements function so as to effectively separate the capacitor C1 and capacitor C2 so that they do not interfere at least in the same frequency.

Abstract: A method and system are described for measuring agglutination in a target-induced agglutination assay with one or more magnetic particles performed in a reaction chamber. After the magnetic particles (3, 15), which are capable of binding to a target (5) are provided in the assay, an agglutination process resulting in agglutinated particles (100) comprising at least one magnetic particle is performed. The method then further comprises applying an alternating current magnetic field (HAC) to the assay and—measuring an effect of the HAC on the one or more magnetic particles (3,15) unattached to any surface. The measured effect is indicative of one or more agglutination parameters.

Abstract: A pulse-induction-type metal detector in which the receiver coil comprises bifilar windings that are connected in series, opposing during the coil pulse and in series, aiding, following the coil pulse. Pick-up of energy by the receiver coil during the coil pulse is thereby minimized and the duration of oscillations is curtailed. Owing to the rapid recovery of the system from the flux change that is used to charge the target, the signal sampling gate can be positioned very close to the trailing edge of the coil-current pulse, whereby detection of targets with very short time constants is made possible.

Abstract: According to one embodiment, an apparatus comprises a magnet assembly to produce a static magnetic field and a set of high-Tc flux transformers to detect a flux change from an item when the item is subjected to the static magnetic field produced by the magnet assembly and to produce a current based on the flux change. Additionally, the apparatus comprises a set of magnetoresistive sensors to detect a field produced by a current produced in the set of high-Tc flux transformers and a scanning mechanism to produce cyclic relative motion between the apparatus and the item. Furthermore, the apparatus comprises a magnetic shield to shield the magnetoresistive sensors, where the shield is an open ended cylinder made from mu-metal, where mu-metal is a very high magnetic permeability iron-nickel alloy. The apparatus additionally comprises a water interface mechanism to fill a gap between the apparatus and the item with water.

Abstract: Reference standards or articles having prescribed levels of damage are fabricated by monitoring an electrical property of the article material, mechanically loading the article, and removing the load when a change in electrical properties indicates a prescribed level of damage. The electrical property is measured with an electromagnetic sensor, such as a flexible eddy current sensor, attached to a material surface, which may be between layers of the article material. The damage may be in the form of a fatigue crack or a change in the mechanical stress underneath the sensor. The shape of the article material may be adjusted to concentrate the stress so that the damage initiates under the sensor. Examples adjustments to the article shape include the use of dogbone geometries with thin center sections, reinforcement ribs on the edges of the article, and radius cut-outs in the vicinity of the thin section.

Abstract: A magnetic field response sensor comprises an inductor placed at a fixed separation distance from a conductive surface to address the low RF transmissivity of conductive surfaces. The minimum distance for separation is determined by the sensor response. The inductor should be separated from the conductive surface so that the response amplitude exceeds noise level by a recommended 10 dB. An embodiment for closed cavity measurements comprises a capacitor internal to said cavity and an inductor mounted external to the cavity and at a fixed distance from the cavity's wall. An additional embodiment includes a closed cavity configuration wherein multiple sensors and corresponding antenna are positioned inside the cavity, with the antenna and inductors maintained at a fixed distance from the cavity's wall.

Abstract: A system and method for tracking an object through a three dimensional space is provided that uses the generation and detection of various magnetic fields to provide three-dimensional location data. The integrity of the generated magnetic fields are monitored against a baseline in order to detect compromise by the unintentional introduction of a foreign metallic or magnetic object in the procedural space.

Abstract: A laminated core testing device for testing laminated cores in a generator is provided. The laminated core testing device includes an exciting winding situated parallel to a rotation axis of the generator and connected to a secondary alternating current generator, and further includes an infrared image acquisition device for acquiring infrared recordings. The secondary alternating current generator has a controllable frequency converter, and the secondary alternating current generator, at a frequency ranging from 400 Hz to 600 Hz, provides, in a single-phase manner, an output of 200 kW with a controllable output voltage ranging from 0 V to 3.0 kV.

Abstract: A device and method for inspecting an inspection object of in the vicinity of a further object, both of electrically conductive material, the device comprising a transmitter/receiver arrangement for generating an electromagnetic field in the inspection object, and for measuring a signal indicative of a transient eddy current which is generated in the inspection object by the electromagnetic field, wherein the device further comprises a magnetic shield means, providing at least a partial magnetic shield for the transmitter/receiver arrangement in a direction other than a measurement direction; use of the device from inside an annulus between an inner and an outer tubular, and a method of operating a hydrocarbon well having a well completion, and inspecting the well completion from inside an annulus.

Abstract: A portable metal detection system that includes a hand/wrist mounted metal detector with two search coils mounted on the palm side of the detector. The mounted metal detector includes a wireless transmitter and a small rechargeable fuel cell. The detection system also includes a separate housing that contains a wireless receiver, a small rechargeable fuel cell and an adjustable vibration or audio alert circuitry. The separate housing may be worn anywhere on the operator of the system. Once the hand/wrist mounted metal detector detects a metal object, the wireless transmitter sends a signal to the wireless receiver in the separate housing that activates the vibration or audio alert circuitry. The separation of the detection device and the alert circuitry prevents a metal detection detainee from hearing or feeling a metal detection alert.

Abstract: A magnetic field response sensor comprises an inductor placed at a fixed separation distance from a conductive surface to address the low RF transmissivity of conductive surfaces. The minimum distance for separation is determined by the sensor response. The inductor should be separated from the conductive surface so that the response amplitude exceeds noise level by a recommended 10 dB. An embodiment for closed cavity measurements comprises a capacitor internal to said cavity and an inductor mounted external to the cavity and at a fixed distance from the cavity's wall. An additional embodiment includes a closed cavity configuration wherein multiple sensors and corresponding antenna are positioned inside the cavity, with the antenna and inductors maintained at a fixed distance from the cavity's wall.

Abstract: The system (10) and the method are used for forecasting the electrical conductivity of an anode (12) for aluminum production before the anode (12) is baked. In the system (10), at least one receiving coil (20,22) is coupled to an electromagnetic field emitting unit (14,18). A sensing device (30) is connected to the receiving coil (20,22), the sensing device (30) outputting a signal indicative of a variation of the electromagnetic field received by the receiving coil (20,22) as the crude anode (12), or a portion thereof, passes inside the receiving coil (20,22). A value indicative of the electrical conductivity of the anode (12) is then calculated using the signal from the sensing device (30) and signals previously obtained using reference anodes (12). This way, the electrical conductivity of the anodes (12) can be forecasted before the crude anodes (12) are baked.

Abstract: Apparatus for determining magnetic properties of materials comprises a portable probe (1), an equipment trolley (2) holding cryogenics and electronics and connecting cables (3). The probe (1) comprises a drive coil (4) and a correction coil (5), the drive coil (4) being disposed symmetrically with respect to an inner second-order gradiometer sensor coil (8). Electrical connectors in the form of 2-metre long Belden (1192A) microphone cables (3) are used to connect the apparatus on the equipment trolley (2) to the drive coil (4), the correction coil (5) and the sensor coil (8). The drive coil (4) is driven so as to generate a sinusoidally varying magnetic field. The electronics comprise a flux-locked loop (9), a SQUID controller (10), a data acquisition module (11), which captures and processes the signals and a computer (12). A liquid-nitrogen dewar (13) is supported on the equipment trolley (2) and houses a sensitive SQUID detector (14) and a transfer coil (15) made from copper.

Abstract: Modeling and simulation of free and forced structural vibrations is essential to an overall structural health monitoring capability. In the various embodiments, a first principles finite-difference approach is adopted in modeling a structural subsystem such as a mechanical gear by solving elastodynamic equations in generalized curvilinear coordinates. Such a capability to generate a dynamic structural response is widely applicable in a variety of structural health monitoring systems. This capability (1) will lead to an understanding of the dynamic behavior of a structural system and hence its improved design, (2) will generate a sufficiently large space of normal and damage solutions that can be used by machine learning algorithms to detect anomalous system behavior and achieve a system design optimization and (3) will lead to an optimal sensor placement strategy, based on the identification of local stress maxima all over the domain.

Abstract: A system for determining the magnetic permeability of a material is provided. Two electrical inductors formed as primary and secondary concentric coils share a common magnetic core space. An AC voltage applied to the primary coil creates a magnetic flux in the core proportional to the magnetic permeability of a sample of the material positioned within the core space. The magnetic flux induces an AC voltage in the secondary coil indicative of the sample magnetic permeability. When the material is a magnetorheological fluid, the magnetic permeability is proportional to the concentration of magnetic particles in the sample and can be back-calculated from the amplitude of the secondary voltage signal. Sensitivity and resolution can be increased by using two identical sets of coils wherein a reference material forms a core for the primary set and the MR fluid sample forms a core for the secondary set.

Abstract: At least one time-varying signal is applied to a plurality of coil elements in cooperative relationship with and spanning different portions of a vehicle. The coil elements generate an associated plurality of magnetic field components that interact with the vehicle. At least one detection circuit generates a detected signal responsive to signal components from the coil elements so as to provide for detecting a change in a magnetic condition of the vehicle.

Abstract: There is provided a metal detection device capable of effectively detecting a metal mixed in food or the like by generating AC magnetic field simultaneously tuned to respective frequencies by a single transmission coil in response to frequency components of different frequencies without switching an element by a switch or the like. Constituent elements constituting magnetic field generation means (2) are connected so that a transmission coil L1 and a capacitor C1 resonate in the first frequency F1. Moreover, constituent elements are connected so that the transmission coil L1 and a capacitor C2 resonate in the second frequency F2. Furthermore, constituent elements function so as to effectively separate the capacitor C1 and capacitor C2 so that they do not interfere at least in the same frequency.

Abstract: Methods and systems are provided for determining a state of charge of a battery. The battery is subjected to a predetermined magnetic field such that the battery and the predetermined magnetic field jointly create a resultant magnetic field. The resultant magnetic field is sensed. The state of charge of the battery is determined based on the resultant magnetic field.

Abstract: The invention relates to an incremental displacement transducer for determining a displacement of a first object relative to a second object with a scanning unit linked with the first object for scanning a division track linked with the second object having first areas and second areas alternately arranged with a period length, the first areas having a first physical property and the second areas a second physical property differing therefrom. The scanning unit has a plurality of sensors for scanning the first areas and second areas on the basis of the first and/or second physical property. An evaluating unit is linked with the scanning unit for determining the displacement on the basis of the measuring signals of the sensors.

Abstract: There is disclosed a method for monitoring wall thickness of an object having an electrically conductive wall, using a pulsed eddy current probe, wherein the same location on the wall is inspected repeatedly over an extended period of time. The pulsed eddy current probe is arranged in a predetermined position relative to the inspection location. The wall thickness dm is determined from a signal Vm which is recorded as a function of time t and from which a characteristic value ?m is determined, which is used to determined the wall thickness. The measurements are corrected for the influence of temperature. The disclosed method is particularly suitable for determining the rate of corrosion at the inspection location.

Abstract: A sensor for sensing a parameter such as position, comprises: (i) an excitation winding for example coils (7, 9) in quadrature; (ii) a signal generator (41, 42, 43) operable to generate an excitation signals and arranged to apply the generated excitation signal to the excitation winding; (iii) a sense coil (11) that can be electromagnetically coupled to the excitation winding such that, in response to the excitation signal being applied to the excitation winding by the signal generator, a periodic electric signal is generated in the sense coil that is indicative of the value of the parameter to be measured by the sensor; and (iv) a signal processor (108) operable to process the periodic electric signal generated in the sensor winding to determine a value representative of the parameter being measured.

Abstract: A time-varying signal is applied to at least one coil in magnetic communication with at least a portion of a vehicle susceptible to deformation responsive to a crash. A sense resistor in series with the at least one coil provides for detecting a current therethrough responsive to a voltage thereacross. The current is responsive to a magnetic condition affecting the magnetic field generated by the at least one coil, responsive to the reluctance of a magnetic circuit with which the at least one coil is in magnetic communication, and responsive to associated eddy currents in proximal conductive elements, responsive to the magnetic field generated by the at least one coil.

Abstract: A sensorless position measurement method may be used to determine the position of a solenoid-based actuator which controls some substance. The sensorless position measurement method of the present invention eliminates the need for a dedicated sensor in the actuator device, as well as the associated electrical connections between this sensor and the system controller.

Abstract: An eddy current sensor (10) has a sensor coil (100) disposed near a conductive film (6) formed on a semiconductor wafer (W) and a signal source (124) configured to supply an AC signal to the sensor coil (100) to produce an eddy current in the conductive film (6). The eddy current sensor (10) includes a detection circuit operable to detect the eddy current produced in the conductive film (6). The detection circuit is connected to the sensor coil (100). The eddy current sensor (10) also includes a housing (200) made of a material having a high magnetic permeability. The housing (200) accommodates the sensor coil (100) therein. The housing (200) is configured so that the sensor coil (100) forms a path of a magnetic flux (MF) so as to effectively produce an eddy current in the conductive film (6).

Abstract: The invention relates to a method of detecting surface defects on a continuously-cast crude metallic product, such as a steel slab (4). According to the invention, a sensor (10) is used to detect surface defects by means of eddy currents, said sensor consisting of a matrix comprising at least two rows (22, 24) of at least three adjoining measuring cells (21) which can be controlled by a multiplexing control unit (12). Moreover, each cell can generate eddy currents at the surface of the slab and, alternately, detect eddy currents in said surface. The inventive method comprises a step consisting in controlling a first transmitting cell and a second receiving cell from the same row, but which are separated from one another by at least one inactive cell.

Abstract: A metal detection device for a working unit with at least one driven working element for conveying crop material has windings for generating electrical detection signals when metal objects are present in the region of the working unit, and the detection signals generated by the windings are detected in a time window, thereby enabling a more accurate identification of the metal object.

Abstract: An electronic metal detector having transmit electronics includes switching electronics arranged and adapted to generate a transmit signal. The transmit electronics includes at least two power sources, and is connected to a transmit coil arranged and adapted to transmit an alternating magnetic field. The switching electronics are adapted and arranged to switch a first voltage of one power source to the transmit coil for at least a first period and also a third period, and to switch a second voltage of the other power source to the transmit coil for at least a second period. Receive electronics are arranged to receive and process a receive magnetic field during at least some of the second period and fourth period to produce an indicator output, at least indicating the presence and a characteristic of some metal targets under the influence of the magnetic field.

Abstract: A sensor device measures a property of an object. The sensor device comprises a magnetic field generator adapted to generate a magnetic field in at least a part of the object, and at least one magnetic field detector adapted to detect at least one detection signal in response to the magnetic field generated in at least a part of the object. The at least one detection signal is indicative of the property of the object. A direct current or a direct voltage is applicable to the magnetic field generator to generate the magnetic field in at least a part of the object.

Abstract: An aspect of the invention is directed to a variable sensor head for use in multiple electric machines with varying slot openings comprising a ferromagnetic core; a first adjustable portion and a second adjustable portion positioned in communication with the ferromagnetic core wherein the first adjustable portion and the second adjustable portion are adjusted to fit between a plurality of slot openings of varying widths between a pair of lamination teeth of an electric machine. According to another embodiment, the first and second adjustable portions are sliding portions where the sliding portions may be spring biased to provide a close fit between the pair of lamination teeth. According to another embodiment, the first and second adjustable portions are adjustable screws.

Abstract: A method is suggested for determining the angular position of the rotor in a rotating electric machine, which machine has a stator winding set with at least three stator windings, and the stator winding set is powered by a converter device. Firstly, a first voltage (U1) is applied to the stator winding set via the converter device within a first definable time period (tx1), and a first current gradient ( ? i ? t ? | U 1 ) is calculated therefor, and a second voltage (U2) is applied to the stator winding set via the converter device within the first definable time period (tx1), and a second current gradient ( ? i ? t ? | U ? ? 2 ) is calculated therefor.

Abstract: System and method of inductively measuring the bio-impedance of a conductive tissue The present invention relates to a system (100) and method of inductively measuring the bio-impedance of a conductive tissue (106). Furthermore the invention relates to a computer program (115) for operating such a system (100).

Abstract: A metal detector employing digital means for the generation of highly quality reference signals used for transmission and demodulation and capable of continuously monitoring the parameters of the transmitting and receiving coils. Using the monitored signals and calibration of the measurements paths in both amplitude-frequency and phase-frequency, the effects of the targets and magnetic and/or conductive grounds on the transmitting and receiving coils are greatly reduced, leaving the received signals substantially free of instrumental effects. Methods of ground tracking and filtering are described to separate target information from the ground plus-target receive signals. Single-and multi-frequency operation, with or without modulation for both sinusoidal and square wave transmission, is described, as are means to detect abnormal situations and to find and operate at resonance.

Abstract: An apparatus for detecting a potentially dangerous ferromagnetic object carried inadvertently by a person approaching the magnet of a magnetic resonance imaging system (14) uses the fringe field (16) of the magnet and provides guide members (11) defining a path along which the person is prescribed to pass. The path (11) is generally or approximately parallel to the field the path. At least one sense coil and generally two sets of sense coils (12, 13) are located on respective sides of the path (11) s the movement of the ferromagnetic object in the field of the magnet causes a voltage to be generated in the sense coil.

Abstract: A method of determining a mass variation of a conductive film on a substrate with an area, an edge zone, and a center zone, is disclosed. The method includes providing a measured conductive film mass of a conductive film on a substrate. The method also includes positioning a sensor near a set of positions on the substrate; measuring using the sensor a set of electrical responses; and correlating the set of electrical responses to a set of conductive film thicknesses. The method further includes estimating a volume of the conductive film based at least in part on the set of conductive film thicknesses and the area; and estimating a derived conductive film mass based in part on the volume and a conductive film density, wherein the mass variation is a difference between the measured conductive film mass and the derived conductive film mass.

Abstract: A proximity sensor 717 comprising a combination of an arbitrarily selected one of a plurality of types of detection end modules 707, a plurality of types of output circuit modules 709 and a plurality of types of outer shell cases 711. The detection end module 707 includes an integrated arrangement having a detection coil assembly (705, 701, 702) with the detection characteristic self-completed by a mask conductor 700 for reducing the conductor detection sensitivity in a specific peripheral area where the outer shell case is assumed to exist, and a detection circuit assembly (703) with the coil of the detection coil assembly as a resonance circuit element. The characteristics of the proximity sensor are completely adjusted before shipment. As a result, the adjustment of the characteristics which otherwise might be required each time is eliminated even in the case of the combination with an outer shell case of a different material.

Abstract: The present invention relates to a method and an apparatus for measuring magnetic properties of a document (5) and to a measuring head (12) suitable therefor for measuring magnetic field changes. The apparatus comprises a device (2, 3) for generating an electromagnetic alternating field, a measuring element (6) and a lock-in amplifier (7). The measuring element (6) is so adapted that it converts an electrical input signal of the measuring element (6) into an electrical output signal in dependence on changes of the magnetic field when the document (5) with magnetic properties is brought into the magnetic field. The measuring element (6) used is preferably as a GMR or SDT element which changes its electrical resistance comparatively strongly upon even small changes of the electromagnetic alternating field. The measuring head (12) for use in the apparatus comprises a printed circuit board (13) with coils (14) disposed thereon and a GMR or SDT element (6).

Abstract: At least one time-varying signal is applied to a plurality of coil elements in cooperative relationship with and spanning different portions of a vehicle. The coil elements generate an associated plurality of magnetic field components that interact with the vehicle. At least one detection circuit generates a detected signal responsive to signal components from the coil elements so as to provide for detecting a change in a magnetic condition of the vehicle.

Abstract: Disclosed is an assembly and method for locating magnetic objects or objects that can be magnetized, with the objects being located in non-magnetic media. To increase the detection depth for such objects and to clearly register their shape, position and structures on single detection planes, at least one sensor is arranged in a primary magnetic field of a magnetic field generator and the magnetization distribution of the magnetic field is uniform in the vicinity of the corresponding senor or its local profile is known.

Abstract: An electric current perturbation probe includes at least one driver coil and at least one receiver. The at least one driver coil produces an omni-directional magnetic field. The at least one receiver is decoupled from the omni-directional magnetic field. In one example, the at least one driver coil includes a first driver coil that defines a first effective coil axis which is positioned orthogonally to a second effective coil axis of a second driver coil. The first driver coil is provided with a first electrical excitation signal which is phase shifted by 90 degrees from a second electrical excitation signal used to drive the second driver coil.

Abstract: A metal object detecting apparatus comprising, a transmitter for generating a primary magnetic field having a resultant magnetic field direction which varies along any substantially linear path through a surveillance volume such that at three locations along said path the resultant magnetic field points in three mutually substantially orthogonal directions; a detector for measuring a secondary magnetic field at a plurality of positions as a function of time due to the presence of a metal object within the surveillance volume as it passes a plurality of measurement points there-through; and a processor for determining from the measured secondary magnetic fields a track through the surveillance volume comprising a plurality of locations of the metal object and a magnetic moment thereof at each location, the processor being adapted in use to derive there-from a magnetic signature that is characteristic of the metal object and independent of the orientation and track of the metal object.

Abstract: An embodiment of the invention generally relates to a temperature-independent method of determining an engine health parameter, namely stand-off distance, between an eddy current sensor and a conductive element. The method includes receiving a signal from the eddy current sensor and demodulating a waveform from the received signal. The method also includes determining a predetermined set of substantially temperature-independent parameters from the waveform and determining the stand-off distance based on the predetermined set of substantially temperature-independent parameters.

Abstract: There is described a sensor comprising an excitation winding, a signal generator operable to generate an excitation signal and arranged to apply the generated excitation signal to the excitation winding, a sensor winding electromagnetically coupled to the excitation winding and a signal processor operable to process a periodic electric signal generated in the sensor winding when the excitation signal is applied to the excitation winding by the signal generator to determine a value of a sensed parameter. The excitation signal comprises a periodic carrier signal having a first frequency modulated by a periodic modulation signal having a second frequency, the first frequency being greater than the second frequency. In this way, the sensor is well suited to using digital processing techniques both to generate the excitation signal and to process the signal induced in the sensor windings. In an embodiment, the sensor is used to detect the relative position of two members.

Abstract: An electronic ferrous metal detector with an alarm includes a non-ferrous core positioned circumferentially about an opening in an object, such as a hole in a garbage can lid. A pick-up coil having a sufficient number of windings is wound about the non-ferrous core for detecting magnetized objects passing therethrough and generating a voltage. The voltage is passed through an op-amp and into a comparator/detector, where a preset reference point is compared to the voltage from the op-amp. Once the voltage passes the preset reference point, the comparator goes to a high output and powers a switch, such as a SCR or Triac, which is gated on and carries the current and feeds the voltage to an alarm that provides an audible or visual signal that a magnetized piece of ferrous material has passed through the metal detector.

Abstract: An eddy current testing probe has a flexible substrate adapted to face to a surface of a test article, a plurality of coils which are fixed to the flexible substrate and energized one of which is capable of being changed sequentially, a pressing member for pressing the substrate toward the test article, an elastic member arranged between the substrate and the pressing member, and a movement limiting member for limiting a movement of the pressing member toward the test article.

Abstract: There is described a sensor comprising an excitation winding, a signal generator operable to generate an excitation signal and arranged to apply the generated excitation signal to the excitation winding, a sensor winding electromagnetically coupled to the excitation winding and a signal processor operable to process a periodic electric signal generated in the sensor winding when the excitation signal is applied to the excitation winding by the signal generator to determine a value of a sensed parameter. The excitation signal comprises a periodic carrier signal having a first frequency modulated by a periodic modulation signal having a second frequency, the first frequency being greater than the second frequency. In this way, the sensor is well suited to using digital processing techniques both to generate the excitation signal and to process the signal induced in the sensor windings. In an embodiment, the sensor is used to detect the relative position of two members.

Abstract: A pair of cores are arranged such that first end portions thereof face to each other with a gap via a conveying path through which a medium to be detected passes. Coils wound at the first end portions of the cores, respectively, are connected in series to each other, thereby constituting a first coil. Coils wound at second end portions on a side opposite to the first end portions are connected in series to each other, thereby constituting a second coil. There are provided an exciting coil which generates a detection magnetic field passing the cores and the gap, and a convergent magnetic field generating unit which generates, in the gap, a convergent magnetic field for converging the detection magnetic field in a direction perpendicular to a direction in which the first end portions of the cores are connected to each other.

Abstract: Apparatus (10) for establishing the positions of metal objects in a mixed input stream of both metal and non-metal objects, the apparatus comprising a differential metal-detecting coil (14A) having a first coil portion wound in a first sense and a second coil portion of generally similar shape and size to the first, wound in a second sense opposite to the first sense, and conveying means (11) for moving objects with respect to, and past, the differential metal-detecting coil in a plane and in a direction with unit vector â, characterised in that the second coil portion is displaced from the first coil portion by a displacement B having a component in the plane in a direction with unit vector {circumflex over (b)}, wherein 0 < cos - 1 ? a ^ · b ^ < ? 2 , and in that the apparatus further comprises analysing means for analysing the form of the output voltage of the coil as a function of time to establish the position of said metal objects in a direction ? in the plane, where ? is d