Abstract: The present invention provides an eddy current array probe having a complaint body molded around a rigid insert. A flexible eddy current array circuit is wrapped around the outer surface of the compliant body.

Abstract: A method and system for measuring anchoring strength of liquid crystal through measurement of magnetic field induced torque. In the system for measuring anchoring strength of liquid crystal, when a magnetic field (7) is applied to a liquid crystal cell (1), a torsion wire (5) twists in response to the magnetic field (7) As a result, a mirror (6) attached to the torsion wire (5) displaces, and thus a laser beam emitted from a laser (8) and reflected from the mirror (6) rotates. The displacement of the laser beam is detected by a bisected photodiode (9) for position detection. Specifically, outputs from the bisected photodiode (9) are amplified by means of amplifiers (10) and (11), which output voltages VA and VB, respectively. The magnetic-field induced torque is proportional to the rotational angle of the mirror, which is proportional to VA-VB.

Abstract: An eddy current inspection probe provides multiple interchangeable configurations for enabling an inspector to reach most or all portions of most or all turbine blades within a combustion turbine by inserting the probe through an inspection port, without disassembling the turbine. The probe shaft contains the electronic signal wire for the inspection tip and a port for a video probe, thereby facilitating use of the video probe and protecting these components. The inspection tip connector at the end of the main shaft is pivotally secured to the shaft, and may be set at any desired angle by using a semirigid or rigid member passing through the shaft, and connected to lever within the handle. Any one of a plurality of probe tips and shaft extensions may be selected to configure the inspection probe to reach a desired location within the turbine.

Abstract: A current sensing system including a carrier strip, the carrier strip disposed so as to be associated with a current carrying conductor, wherein when an electrical current flows through the conductor, the electrical current flowing through the conductor creates a magnetic field having a magnetic flux, wherein the magnetic flux is responsive to the electrical current flow, a Hall effect sensor disposed relative to the carrier strip such that the Hall effect sensor is communicated with the magnetic field, wherein the Hall effect sensor generates an electrical signal responsive to the magnetic flux and a metering device in communication with the Hall effect sensor, wherein the metering device processes the electrical signal so as to create a processed signal responsive to the electrical current flow.

Abstract: A positioning device for determining the position of an object includes an anchoring surface, a first movable carriage on which the object is loaded and which has a means for suctioning onto the anchoring surface, a second movable carriage which has a drive assembly and which is connected with the first movable carriage as needed, and a connecting means which controls the connection of the first and second movable carriages. The first and second movable carriages are connected by the drive assembly and the first movable carriage is conveyed to a predetermined position on the anchoring surface and is suctioned and anchored on the anchoring surface at this position by a means for breaking the connection between the first and second movable carriages and for performing the suctioning to position the object.

Abstract: A rotation detecting apparatus including a drive gear rotatably supported by a case having a cover and capable of rotating cooperatively with an object to be detected, driven gears and brought in mesh with the drive gear and capable of rotating cooperatively therewith, magnets and provided at rotational center portions of the driven gears and having plane portions formed with N poles and S poles, a circuit board arranged at the case and capable of connecting to outside, magnetic reluctance elements attached to the circuit board and being opposed to the plane portions of the magnets and an electronic circuit part for converting an output signal of the magnetic reluctance element into a rotational angle signal, wherein the driven gears and are interposed by the case and the cover and a constant distance is maintained between the plane portion and the magnetic reluctance element.

Abstract: A single apparatus for magnetizing permanent magnet segments mounted on a cylindrical shell for use in a flywheel magneto or the like. Not only are the segments magnetized but also their magnetic strength is measured when the magnetized element is moved out of the magnetizing section. Prior to that, however, the circumferential location of the timing mark on the flywheel is also verified, within the single apparatus.

Abstract: A revolution detecting sensor includes a Hall IC facing a detection target, a magnet positioned behind the Hall IC and applying a bias magnetic field, and a substrate provided with a detecting circuit. The revolution detecting sensor is configured such that a lead terminal from the Hall IC bypasses the magnet, to be guided to the substrate. In a magnet holder holding the magnet, a recessed guide guiding the lead terminal is formed, and a pressing member is provided. Thus, a tip end portion of the lead terminal can be held in a prescribed position, and an operation for attachment to the substrate can easily be performed.

Abstract: A fluxgate excitation circuit comprises an excitation inductor having a resistance Rsat and an inductance Lsat. Vin is provided by a half bridge converter of MOSFET switches (S1, S2). The excitation inductor is driven so that it enters saturation at the transition as the excitation cycle passes from positive to negative. Thus, a high input rms current value of the excitation circuit can be achieved. Because the excitation inductor is saturated for part of the cycle it may be much smaller than heretofore and have a smaller power supply. Thus, the circuit finds application in small devices.

Abstract: A rotary position sensor includes a cylindrical housing having a partition wall which divides the interior of the housing into a first storing space and a second storing space. The first storing space stores a rotating mechanism and is closed with a first cover in such a manner that a shaft portion of a rotating member projects outside, and the second storing space stores an electrical circuit component and is closed with a second cover. A magnet included in the rotating mechanism is disposed at a position close to the partition wall, and a giant magnetoresistive element included in the electrical circuit component is disposed in a recess formed in the partition wall. Thus, the rotating mechanism and the electrical circuit component are completely separated from each other by the partition wall, so that a complex sealing process is not necessary and the detection accuracy can be increased.

Abstract: A sensor arrangement with a first sensor (1) which comprises a measuring coil (2) that operates by the eddy current principle, and which detects the distance from a target (6), and a second sensor (3), the two sensors (1, 3) being arranged in a housing (4). To reduce the interaction of the sensors with each other, a panel (7) is positioned on the measuring side of the housing, with the panel being an active component of the second sensor (3). The second sensor is preferably a capacitive sensor, with the panel (7) being the active measuring surface of the capacitive sensor.

Abstract: A device for nondestructive testing of especially hot, bar-shaped rolling material above Curie point during the rolling process by means of an exploring coil system which can be impinged upon by a coolant and which rotates around the rolling material passing therethrough. The exploring coil system consists of at least two exploring coils. The invention is characterized in that the inventive device is arranged directly downstream from the point where the rolled product exits from the roll stand on the roller cooling system associated therewith. The invention is further characterized in that the coolant for the explorer coil system is fed into the rotating system essentially on the same plane as the one on which the device is secured to the roll stand, wherein a channel for said coolant is provided, extending in a threaded manner between the rolled product and the rotation bearing and wherefrom individual ducts lead to the respective explorer coils in a radial manner.

Abstract: An apparatus for measuring the magnetic field distribution of a magnetic sample includes a magnetic field sensor arrangement having three, orthogonally-disposed, Hall sensors for sensing the magnetic field produced by a magnetic sample at a given location, The sensor arrangement is scanned along a predetermined scan pattern. The apparatus then acquires sampling data from the sensor arrangement, the sampled data providing a representation of the magnetic field distribution of the magnetic sample. The data is preferably acquired by an interface card for a PC, which stores sampled data in the main memory of the PC for data analysis and display.

Abstract: Pressurized elastic support structures or balloons are used to press flexible sensors against the surface a material under test. Rigid support elements can also be incorporated into the inspection devices to maintain the basic shape of the inspection structure and to facilitate positioning of the sensors near the test material surface. The rigid supports can have the approximate shape of the test material surface or the pressurization of one or more balloons can be used to conform the sensor to the shape of the test material surface.

Abstract: A rotor disk is inspected using an inspection apparatus including an inspection fixture which has a base, and at least one guide extending from the base. Each guide is slidably engagable to one of the rotor slots of the rotor disk and has a guide side shaped to slidably conform to the rotor slot side, and a guide bottom having a guide bottom surface which, in combination with a slot bottom surface, defines an elongated inspection cavity extending parallel to the axis of revolution of the rotor disk. The inspection fixture is mated to the rotor disk such that each guide slides into one of the rotor slots. A sensor apparatus includes a sensor, such as an eddy current sensor, sized to slide into the inspection cavity with a close facing relation thereto, and a sensor drive that moves the sensor parallel to a direction of elongation of the inspection cavity. Inspection is performed by inserting the sensor into the inspection cavity, and sensing the rotor slot bottom using the sensor.

Abstract: A position sensor module in which a position sensor delivers a signal output to an electronic evaluation unit for further processing, wherein the sensor module and evaluation unit are mounted on and electrically connected by a shaped sheet metal part to eliminate the need for tuning adjustments between the position sensor and the electronic evaluation unit.

Abstract: An apparatus for measuring electromagnetic characteristics includes a sample rod with a sample fixed to a lower part thereof, a helium 3 refrigerator, in which the sample rod is inserted, having a main pipe that forms around the sample rod a space that is cooled by helium 3, a device for supplying helium 3 to the helium 3 refrigerator, an inner tube portion, into which the main pipe is inserted, that supports at an upper part thereof the refrigerator, an outer tube that cools an outer periphery of the inner tube with helium, a liquid helium container that supplies liquid helium to the outer tube, and a device for measuring the electromagnetic characteristics of the sample.

Abstract: A sensor for measuring magnetostriction of and/or magnetic thin film is constructed by depositing a thin film nonferromagnetic electrically insulating layer followed by a thin film layer of a sensor material which is piezoresistive and nonferromagnetic. The insulating and the piezoresistive film can be etched into an appropriate pattern and orientation to provide sensitivity to strain in the magnetic film. The magnetostrictive strain in the magnetic film is induced by a known magnetic field which produces a corresponding strain in the piezoresistive film which can be measured as a change in the electrical resistance which can be detected by external probes or other measuring means. The measurement of the magnetostriction can be performed as a part of the manufacturing process for wafers with a plurality of thin film magnetic heads thereon and does not require that the wafers be removed to a laboratory.

Abstract: An apparatus and associated method for attaching a disc drive cover member to a disc drive base member. A fixture comprises a base and a stop guard, cradle and guide rails supported by the base. The disc drive base member is operatively receivingly engaged in the cradle adjacent the guide rails. The disc drive cover member is operatively abuttingly engaged at one end against the stop guard and pivoted toward the disc drive base member. Any substantial misalignment of the disc drive cover member with the disc drive base member causes the disc drive cover member to engage at least one of the guide rails and therefore be urged into proper alignment, preventing adverse contact between the disc drive cover member and the disc drive base member.

Abstract: A disc stabilizer for use in a spin-stand tester having a spindle motor for rotating a disc is provided. The spin-stand tester is capable of positioning a transducing head adjacent a first surface of the disc. The disc stabilizer includes a vacuum plate coupled to a spindle of the spindle motor. The vacuum plate has a top surface and a bottom surface opposite the top surface. At least one of the top and the bottom surfaces is a grooved surface including multiple vacuum channels. The grooved surface is substantially in contact with a second surface of the disc. Vacuum distributed through the multiple vacuum channels of the grooved surface is applied directly to the second surface of the disc, thereby holding the disc in place.

Abstract: A seat position sensor for a vehicle including: a sensing portion configured to sense a position of a vehicle seat with respect to a part of the vehicle; and a mounting portion coupled to the sensing portion, wherein the mounting portion includes an integral locking pin configured to secure the seat position sensor to a portion of the vehicle. A seat position sensor including a housing having an internal surface defining an opening and a seal disposed in the opening to create a cavity for housing electrical circuitry is also provided. A seat position sensor circuit is also provided to enable testing of a varistor without adversely affecting other portions of the circuit.

Abstract: A magnetic sensor includes a plurality of rows of elements in each of which a plurality of magnetoresistive elements are aligned in a direction which intersects at a predetermined angle the passing direction of an object to be detected, the object including magnetic patterns, the plurality of rows of elements being staggered in the passing direction of the object to be detected. Each of the magnetoresistive elements includes a magnetic sensitive region, and each of the magnetoresistive elements in one of the rows of elements is aligned so that the magnetic sensitive region overlaps the magnetic sensitive region of the magnetoresistive element in another row in the passing direction of the object to be detected. Accordingly, the whole region passed by the object in the alignment direction of the magnetoresistive elements is a magnetic sensitive region.

Abstract: An apparatus for attaching sensors to rotating shafts on equipment includes a cup magnet and a housing for receiving the cup magnet. A target rotor is displaced within the housing which rotates when attached to a rotating shaft for the purpose of sensing the shaft rotation. Alternately, the cup magnet may be permanently attached to a rotating couple rather than a non-rotating housing. A preferred embodiment may have a dust cover.

Abstract: A detection system determines the position of an object moving along a first direction. The system includes a magnetic field source generating a magnetic field signal and a magnetic field detection system coupled to the object. The detection system includes a source interface module with magnetic field sensors positioned a known distance apart along a second direction different from the first direction. Each sensor detects the magnetic field generated by the magnetic field source and generates a magnetic field signal. A processing module processes the magnetic field intensity signal produced by the source interface module. The processing module generates data for each sensor in the source interface module, which is made up of points representing peak magnetic field and sensor location along the second direction. The points are compared to determine the distance of the object from the magnetic field source along the second direction.

Abstract: Spin stand platform. The platform includes an air bearing puck forming a micropositioning stage. The puck is constrained for two dimensional motion on a surface. The micropositioning stage supports a read head element under test. At least one actuator moves the puck to a desired location on the surface and apparatus is provided for removing air from the air bearing puck to lock down the puck to the surface at the desired location. It is preferred that the air bearings be vacuum preloaded and that linear motors be used to move the puck.

Abstract: The support that bears and positions the head in a head holding apparatus is further supported by a heat-compensating member, so that when the support is expanded by the heat source of the head holding apparatus, the heat-compensating member expands in the direction opposite to the direction of expansion of the support. Moreover, supplying of heat to the support and heat-compensating member is further alleviated by insulating said heat source with an insulating material. The amount of displacement of the recording element per unit of time with exposure to heat is controlled by the above-mentioned structure and effects.

Abstract: A method and mechanism for ensuring quality control in printed biological assays is provided. A multi-ejector system having a plurality of individual drop ejectors is loaded with a variety of biofluids. Biofluids include at least a carrier fluid, a biological material to be used in the testing, and markers, such as fluorescent dyes. Data regarding the biofluid loaded in each of the drop ejectors is stored along with an expected signature output of the biofluid. Particularly, the signature output represents signals from individual ones of the fluorescent markers included within the biofluid. Once a biological assay consisting of the biofluid drops has been printed, a scanner capable of detecting the markers scans the biological assay and obtains signature output signals for each of the drops of the biological assay.

Abstract: The present invention relates to an eddy current testing probe, which is suitable for used in a nondestructive test. The eddy current testing probe is provided with an excitation coil (2, 2a, 2b) which generates an alternating magnetic field to generate an eddy current (12) in a specimen (10), and a pair of detection coils (1a, 1b) differentially connected and arranged in phase. A central portion (C1) of the pair of detection coils and a central portion (C2) of the excitation coil (2, 2a, 2b) are arranged to be located at an identical or an almost identical position in a plan view taken in the direction toward the specimen (10), and a flaw (11) on the specimen (10) is detected based on a difference between voltages generated in the pair of detection coils (1a, 1b) due to the eddy current (12).

Abstract: Disclosed is a fixture for a magnetic resistance sensor chip. A rectangular magnetic resistance sensor chip having a sensing part on one side thereof and an electrode at every corner on both sides thereof is fixed onto a front side of a PCB which has a pattern part on the front side, such that the electrode is in contact with the pattern part. The PCB is provided with a through-hole coated with a conductor connected to a terminal part formed on its back side. The PCB associated fixedly with the magnetic resistance sensor chip is installed onto a motor board with a magnet mounted. The installation is achieved by soldering the back side terminal part onto the motor board. Facing the magnet, the sensing part is located at a predetermined distance from the magnet. In the fixture, the magnetic resistance sensor chip can be fixed to a PCB without requiring an additional holder and mounted onto a board of a motor with ease.

Abstract: A stage system includes a movable stage, a first driving mechanism, having magnet and a coil unit, for moving the stage along a predetermined direction, the coil unit including a coil and a yoke, wherein the magnet is connected to the stage side, and a second driving mechanism for moving the coil unit along the predetermined direction. While a position or a speed of the stage is controlled as the stage is driven through the first driving mechanism, the coil unit is moved substantially in synchronism with the stage.

Abstract: A product sensor system for use in a refreshment center configured to sense a number of metal product containers. The sensor device can comprise a support shelf mounted in the refreshment center, which holds the product containers. One or more sensor loops are arranged on the shelf below the product containers, and an analysis circuit is connected to the sensor loops to measure the changes in inductance at the sensor loop when product containers are removed from the refreshment center. A microprocessor compares the signals from the inductance sensing circuit with values stored in memory to determine the amount of product remaining.

Abstract: A fixture for use with eddy current inspection probes facilitates inspection of airfoil leading and trailing edges. The fixture includes a fixture body having a hole formed in one side thereof for receiving a probe and a V-groove formed in another side thereof for receiving a workpiece surface. A clamp arm is pivotally mounted to the fixture body, and a spring is disposed between the clamp arm and the fixture body. The spring biases one end of the clamp arm towards the fixture body so that a workpiece can be clamped between the clamp arm and the fixture body.

Abstract: A method of inspecting a preselected area of an electrically conductive component to determine whether flaws are present. The method includes the steps of permanently mounting an eddy current element on the component over the preselected area and energizing the element to generate alternating magnetic fields proximate the component. An electrical signal generated by a secondary magnetic field formed proximate the component is detected using the element and the detected electrical signal is compared to a reference signal to determine whether the detected signal is different than the reference signal. Differences indicate the presence of a flaw in the component. Inspection apparatus for performing this method is also disclosed.

Abstract: A fixture for use with eddy current inspection probes facilitates inspection of airfoil leading and trailing edges. The fixture includes a fixture body having a hole formed in one side thereof for receiving a probe and a V-groove formed in another side thereof for receiving a workpiece surface. A clamp arm is pivotally mounted to the fixture body, and a spring is disposed between the clamp arm and the fixture body. The spring biases one end of the clamp arm towards the fixture body so that a workpiece can be clamped between the clamp arm and the fixture body.

Abstract: The design of an electro-magnetic radiation suppression shield and cooling housing for a computer, server or other electronic device having a computer processor may be greatly enhanced and expedited by a test apparatus that permits the placement of electro-magnetic radiation suppression plates at differing locations, spacings and alignments, which allows a variance in positioning the electro-magnetic radiation source. The test apparatus not only has an air flow cooling opening in which an electro-magnetic radiation suppression panel forms cooling air flow holes but also a fixture for disposing a second similar electromagnetic radiation suppression panel at a distance from the first electro-magnetic radiation suppression panel. Each of the panels may be substituted to test various designs.

Abstract: A scanning AC hall microscope and a method which measures the domain pattern of magnetic materials, such as magnetic storage media, by measuring the oscillatory motion of a domain boundary under the influence of an external applied AC magnetic field, which allows a differentiation between domains which are immobile and domains which are mobile.

Abstract: A system and method for measuring volumes and areas using electromagnetic induction techniques. A current is generated and fed into one of two coil assemblies to induce voltage into another coil assembly to provide accurate values for volume or area.

Abstract: An apparatus for locating positions on a surface of a structural member indicating the presence of elements within and below the surface of the structural member by means of a detector (1) including a scanning head (3), a position measuring device (4) and an evaluation unit (5) all located within a housing (2). A marking device (6) is connected to and interacts with the evaluation unit (5) for automatically placing a visible marking on the surface of the structural member at the location of the elements scanned by the detector.

Abstract: A device for positioning control of a magnetic head in consideration of eccentricity amount generated due to chucking under the same structure or condition as a hard disk drive of the actual machine is provided. The device includes a thin suspension for supporting a magnetic head for testing, a thick rotary positioner for supporting the suspension, a voice coil disposed at the reverse direction end of the magnetic head for testing of ends of the rotary positioner, a rotary shaft for supporting the magnetic head for testing, the suspension and the rotary positioner, and a pair of magnets and b for sandwiching the voice coil are provided on a stage, thereby constructing the same mechanism as a hard disk drive of the actual machine.

Abstract: A meandering winding magnetometer (MWM) includes a meandering primary winding and at least one sensing winding or coil on a membrane to be pressed against a test surface. The membrane may be supported on a flexible carrier which is translatable into a probe. Abutments in the probe press the carrier against the test surface but allow the carrier and membrane to conform to the test surface. One MWM circuit includes meandering primary and secondary windings. The return leads from the secondary winding return to connector pads in close alignment with the test array, while leads from the primary winding are spaced at least one wavelength from the array. In another MWM circuit, individual sensing loops are positioned within the meandering primary winding. The MWM circuit may be provided on an adhesive tape which may be cut to length.

Abstract: A guide device for linear guidance of elongated objects, particularly for positioning wires passing a nondestructive eddy current test device, can be the inlet nozzle or outlet nozzle, and has a brush arrangement integrated into a guide sleeve. The brush arrangement damps vibration of the wires or other elongated objects transiting the test device. A wire guided by the guide device is protected at its surface and subjected to little or no transverse vibration in the vicinity of the test probe of the test device, resulting in improved measurement accuracy.

Abstract: An inspection apparatus includes a component engagement apparatus, a detection apparatus, and a movement apparatus and is controlled by a cam. A drawer is slidably attached to the component engagement apparatus to receive and align a component including a TV-shaped opening. The detection apparatus is sized to receive an eddy current probe and is attached to the movement apparatus with an adjustable fixture. The movement apparatus identifies a relative position of the eddy current probe in relation to the TV-shaped opening being inspected and guides the movement of the detection apparatus.

Abstract: A non-contact absolute encoder for determining the absolute position of a movable workpiece includes a movable transducer element adapted to be coupled to the workpiece, and a sensor positioned proximate the transducer element. The encoder may be of either the rotary or linear type. The transducer element includes a characteristic profile that varies substantially continuously as a function of the transducer position. The characteristic profile may be magnetic, optical, or some other characteristic that is measurable by a non-contact sensor and is representative of transducer position.

Abstract: A system for verifying the location of physical features on complex magnetic elements, such as magnetic rotors, for driving an electrostatic shutter. A magnetic rotor of the type measured by the magnetic measuring apparatus of the invention has a plurality of magnetic poles and physical features arranged thereon. Each one of both the magnetic poles and physical features has a spatial and magnetic field relative to one another which is rapidly measured by the magnetic measuring apparatus using a dual probe Gaussmeter and encoder means operably connected to a data comptroller.

Abstract: A method of aligning a lithographic fabrication tool to a substrate to be exposed or patterned by the tool includes the steps of providing a first conductive coil pattern on a surface of the substrate, applying electrical current to the coil pattern, providing a second conductive coil on a surface of the tool, sensing an electro-magnetic field generated by the first coil and the second coil, and aligning the tool according to the signal sensed from the first coil. The method contemplates that electrical current is provided to the first coil from either an external source or the tool. Electrical current is provided by the tool through electrical probes on the tool that contact the first coil, preferably at contact pads. A semiconductor processing lithography apparatus for maskless pattern generation is also disclosed.

Abstract: A speed sensor assembly is provided that isolates the internal components of the speed sensor from detrimental external environmental influences. Further provided is a new seal that seals between a housing and an overmold of a speed sensor and is capable of use in speed sensors of varying types and of all different sizes and shapes. Provided is a seal in which a bead of glue cured by ultraviolet light is applied around part of the exterior surface of a housing, after which an injected molded plastic overmold is applied over at least that part of the housing having the applied ultraviolet cured glue. In this way, once the housing is overmolded, the ultraviolet cured glue forms a gasket-like seal between the housing and the overmold preventing the penetration of water or other contaminants into the internals of the speed sensor. Also provided is a mounting fixture for use during a process of applying the seal to the housing.

Abstract: A flatness measuring apparatus is adapted to measure the flatness of the surface of a plate-shaped object such as a disk in a non-contact fashion. A disk is removably held by a measuring table, with the projection of the measuring table engagedly received in a central through hole of the disk. A plurality of eddy current undulation sensors are arranged in a sensor head that is arranged so as to be able to linearly move back and forth along the measuring table. Said eddy current undulation sensors generate an eddy current in said disk and detect any undulation on the surface of said disk. A flatness map is produced for the surface of the disk based on a signal representing the position of the sensor head and on signals from the eddy current undulation sensors, and then is output to a display and/or a printer.

Abstract: A biomagnetic field measurement apparatus includes a bed which holds a subject to be inspected in a shielded room. A cryostat holds a plurality of SQUID magnetometers at low temperature. The cryostat is arranged in the shielded room and the plurality of SQUID magnetometers detect a magnetic field generated from the subject. A driving and detecting circuit drives the plurality of SQUID magnetometers and detects signals therefrom that are processed by a computer. A display that is arranged in the shielded room displays data for viewing by an operator.

Abstract: A magnetic head and disk tester includes a magnetic head which is selectively positioned relative to a rotatably mounted magnetic disk to accomplish testing of either of the head or disk or both. The magnetic head is secured to a carriage which is under electro-mechanical control, wherein displacement of the carriage causes a corresponding displacement of the head relative to the disk and, to some degree, may cause yaw in the carriage. Measurements of the linear position of a left and a right side of the carriage are detected, measured, and fed back to a control system. The control system responds to a difference between a desired command position and the actual position of each side of the carriage and causes actuators to adjust the position of each side of the carriage until the difference, and thereby the yaw, is substantially eliminated. Additionally, during a positioning operation, vibrations in the yaw direction are decreased, which decreases a corresponding settling time of the magnetic head.

Abstract: A head-disk interface tester for magnetic recording disk drives uses a rotary voice coil motor (VCM) actuator and a rotating laser beam that rotates with the actuator to accurately move the head to the desired position and with the desired velocity. A diode laser is located on the rotating actuator and directs a laser beam through the pivot axis of the actuator. The laser beam is received by a linear position detector. The detector provides position data which is used by control circuitry to move the actuator to the position determined by the user or according to a velocity determined by the user. The rotary VCM actuator is mounted on an adjustable stage that allows the height of the actuator to be varied, as well as the distance between the actuator pivot axis and the spindle motor rotation axis to be varied.