Abstract: A method for non-destructive measurement of dynamic coercivity is disclosed. In this method, magnetic media is DC erased by applying a forward DC magnetic field to the magnetic media such that the magnetic moments in the magnetic media are substantially aligned. A specified number of reversed magnetic field pulses are then applied to the magnetic media in a direction opposite to the forward DC magnetic field, wherein the intensity of the reversed magnetic field pulses is less than the remanent coercivity of the magnetic media. The broadband medium noise of the magnetic media is measured. The intensity of the reversed magnetic field pulses is then repeatedly and incrementally increased and applied to the write head for the specified number of pulses, the intensity of the reversed magnetic field pulses eventually exceeding the remanent coercivity of the magnetic media. For each intensity level of the reversed magnetic field pulses, the broadband medium noise is again measured.

Abstract: A process permits the determination of multi-dimensional distribution of magnetic fields. The process uses a magneto-resistive sensor as a physical measuring device. The measuring device is coupled with a method for algebraic reconstruction so that sectional images of the field distribution are calculated from individual measurements of the magneto-resistive effect using the algebraic reconstruction.

Abstract: A magnetic signal reproducing apparatus which can lessen fluctuation of reproduced outputs in reproducing magnetic signals recorded in a magnetic tape by a magneto-resistance effect type magnetic head even if a magnetic tape sliding face of the magneto-resistance effect type magnetic head is abraded. A current value of a sense current when a voltage fluctuation level of the sense current caused when a magnetic field in the normal direction is applied to a magneto-resistance effect element of the magneto-resistance effect type magnetic head is equal with a voltage fluctuation level of the sense current caused when a magnetic field in the opposite direction is applied thereto is set to a predetermined value I0. Then, the current value of the sense current supplied to the magneto-resistance effect element of the magneto-resistance effect type magnetic head is set to be greater than I0 in reproducing the magnetic signals recorded in the magnetic tape.

Abstract: A method of measuring magnetization direction of a MR device, includes a first step of obtaining both maximum electrical resistance values under positive and negative applied measurement magnetic fields onto the MR device biased by anti-ferromagnetic material, a second step of relatively rotating a basic axis of the MR device against a direction of the applied measurement magnetic field until both the maximum resistance values become comparatively the same, and a third step of obtaining a relative rotation angle between the basic axis of the MR device and the direction of the applied measurement magnetic field.

Abstract: In accordance with the present invention, the initialization for orienting the magnetized directions of the free layers of GMR heads (mounted on the diagonally shaded surface of sliders 14) by an external magnetic field is again executed also for the opposite direction, thereby to increase the yield of the GMR heads. Further, it is determined whether the magnetized direction of the pinned layer of GMR heads can be once reversed to the opposite direction, thereby to select damaged GMR heads at an early stage. Then, by performing a reset while performing a quasi-static test for seeing the read back response of the GMR head after restoring the magnetized direction of the pinned layer to a positive rotation, a safe and efficient reset is executed. The reset can be executed not only by applying only a pulse, but also while providing an external magnetic field in the pinning direction, or only by giving a high magnetic field.

Abstract: A spacing between a transducer head and disk surface in a disk drive's head-disk interface is monitored. The transducer head includes a magneto resistive element. The surface of the disk includes a region containing at least one asperity extending from the surface to have a height. The transducer head is placed over the region containing the at least one asperity, and the disk is rotated. A determination is then made as to whether the transducer head contacts the at least one asperity.

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 method of manufacturing a disk drive which includes a disk having first and second magnetic surfaces and first and second read/write transducers for writing information on and reading information from the magnetic surfaces. The method includes determining a track width performance characteristic to be measured for the read/write transducers, establishing ranges of values for the performance characteristic to define a plurality of performance groups. The performance characteristic is measured for a plurality of read/write transducers from which the first and second read/write transducers for the disk drive are to be selected and the read/write transducers are segregated into groups based on the performance characteristic value falling within the range of the group. The disk drive is assembled using read/write transducers from only one of the groups. The measurement of the performance characteristic is accomplished either electrically or optically.

Abstract: A method and apparatus detects pulse asymmetries in a read signal of a data storage device. The read signal is rectified through multiplication with a rectification signal to produce a product signal. The product signal is integrated to produce integrands indicative of pulse asymmetry. In some embodiments of the present invention, the integrands are compared against a baseline value to determine a performance characteristic of a read head in the data storage device.

Abstract: A magnetic head and disk tester provides accurate positioning of a magnetic read-write head over a magnetic disk by means of a coarse positioning mechanism and a fine positioning mechanism. The coarse positioning mechanism includes a stepper motor, a lead screw, a nut, rear sliders and a housing. The fine positioning mechanism includes a piezoelectric actuator, slides and a carriage. The positioning displacements are along a linear axis, which lies on a horizontal plane. The carriage is connected to the housing via the fine positioning mechanism, which then moves the carriage with respect to the housing. Two pairs of linear encoders are mounted on the carriage about the axis and measure the position of the magnetic read-write head with respect to the magnetic disk. Each pair is mounted such that the pairs lie in separate horizontal planes.

Abstract: Obtaining fast dipole size estimation with less influence of noise by using a regional dipole model. An artificial neural network section 30 executes regional dipole size estimation using a neural network having coupling coefficients representing coupling states among as plurality of units and thresholds thereof.

Abstract: A method of analyzing defects in a magnetic thin film is provided. A magnetic field is applied to the magnetic thin film. The magnetization of the magnetic thin film is measured over a range of different field strengths. A value representative of a magnetic hardness coefficient is calculated for the magnetic thin film from the magnetizations measured. The calculated value is compared with a reference value. Defect information is determined in dependence upon the comparison made.

Abstract: A disc testing system includes a base, a disc rotatably attached to the base, and an actuator assembly movably attached to the base. A ramp assembly includes a set of ramps for loading and unloading the sliders and transducing elements carried by the sliders to and from the disc attached to the base. A load spring is attached to the arm of the actuator. A slider is attached to the load spring. The slider further includes a leading edge and a trailing edge. A piezoelectric sensor and a pyroelectric sensor is carried by the trailing edge of the slider. The piezoelectric sensor and the pyroelectric sensor are made from the same material which has both piezoelectric properties and pyroelectric properties. The piezoelectric sensor and the pyroelectric sensor are formed by the same process. The two sensors can also be formed substantially simultaneously. A conductive layer is placed on the trailing edge of the slider followed by a strip of thick film material.

Abstract: A testing method for a magnetic recording medium which is magnetized measures variation of magnetization with the passage of time and evaluates the magnetic recording medium over its life. The method includes the steps of recording a first pattern at a density to be guaranteed in the magnetic recording medium, the first pattern having a difference between the sum total of areas of +bits and the sum total of areas of -bits, measuring remanence of the first pattern with the passage of time, and evaluating the magnetic recording medium over its life based on a measurement result.

Abstract: A lightning arrester tester includes two tubular poles respectively carrying probe terminals, one probe terminal being connected in series through a high-voltage rectifier and high-resistance circuit disposed within the pole to one terminal of a DC microammeter mounted on the outside of the one pole, the other probe terminal being connected through a high-resistance circuit housed within the second pole to the other meter terminal. A diode is connected in parallel with the meter to protect the meter from high leakage currents. In use, the probe terminals are respectively connected to a high-voltage power transmission or distribution line and one terminal of an arrester, the other terminal of which is grounded or, alternatively, to ground and to one terminal of an arrester, the other terminal of which is connected to a high-voltage power transmission or distribution line. The meter displays DC leakage current through the arrester.

Abstract: A method for assessing write element performance in a combined magnetic head that also includes a magneto-resistive (MR) read element for a data storage drive includes exciting the write element with a square wave immediately after lapping the head during manufacture, before mounting the head for operation in the drive. The write element generates an output signal, and the output signal is detected by the read element and then used to determine whether the write element is defective. By using a square wave, temperature gradients in the head and inductive pick up is avoided, thereby facilitating the use of the read element as a test sensor.

Abstract: A magnetic-head short-circuit detector for correctly detecting an electrical short-circuit between coil terminals of a magnetic head. Terminals H.sub.X and H.sub.Y of the magnetic head are connected to the bases of a pnp-transistors P.sub.1 and P.sub.2 respectively. Current sources I.sub.1 and I.sub.2 are inserted between power supply V.sub.CC and the emitters of the transistors P.sub.1 and P.sub.2 respectively. The emitter of the transistor P.sub.1 is connected to the (-) input terminal of a comparator 1 through a resistor R.sub.1 and directly to the (+) input terminal of a comparator 2. The emitter of the transistor P.sub.2 is connected to the (+) input terminal of the comparator 1 through a resistor R.sub.2 and directly to the (-) input terminal of the comparator 2. A current source I.sub.3 is connected between the (-) input terminal of the comparator 1 and GND. A current source I.sub.4 is connected between the (input terminal of the comparator 2 and GND.

Abstract: A magnetic force sensor for detecting a magnetic force of a magnetic sample having a given magnetization direction comprises a magnetic probe having a tip portion. The tip portion is coated with a film of hard-magnetic material effective to maintain the magnetization direction of the probe constant and parallel to the given magnetization direction of the sample. A biasing member has the magnetic probe attached thereto at a free end thereof and is resiliently deflectable in response to the magnetic force between the magnetic probe and the magnetic sample. When the magnetic probe is scanned across the magnetic sample, the distribution of the magnetic force on the magnetic sample is effectively detected.

Abstract: A method of testing a magnetic head with a spin-valve MR element having a pinned direction, includes a step of reproducing magnetic information recorded on a magnetic medium by the spin-valve MR element of the magnetic head to be tested to generate a reproduced signal, the information being recorded on the magnetic medium by using a rectangular wave current with a predetermined pattern, and a step of judging whether the pinned direction of the spin-valve MR element is correct in accordance with a relationship between wave shape of the reproduced signal and the predetermined pattern.

Abstract: A magnetic recording and reproducing apparatus in which a magnetic head contacts a recording medium to record or reproduce a signal onto or from the recording medium. The apparatus includes a measurement unit for measuring an abrasion amount of the magnetic head and outputting measurement data. A display unit displays the abrasion amount of the magnetic head represented by the measurement data outputted from the measurement unit.

Abstract: The present invention relates to a method for characterizing a head in a hard drive assembly, in which the head has a write element. The method comprises providing a disk attached to a hard disk drive assembly, the disk having a plurality of tracks each having a track centerline. One of the tracks has a plurality of sectors. One of the sectors has a servo field with an A burst, a B burst and a C burst, where the A burst and the C bursts have a common boundary located at a track centerline and where the B burst has a center that is positioned along the track centerline. Each sector also has a data field. The read element is aligned with the B servo burst, and data is written in a data field of a first sector of one of the tracks. An A burst and a C burst located in a following sector of one of the tracks is read to provide an A burst amplitude value and a C burst amplitude value. A characteristic of the read element based on the A burst amplitude value and the C burst amplitude value is then determined.

Abstract: According to the present invention, there is provided a magnetic disk apparatus comprising a reading/writing circuit for detecting first to fourth burst signals corresponding to first to fourth burst data items recorded on a recording medium in order to position a head, a CPU for calculating a first value expressed by ((first burst signal)-(second burst signal))/((first burst signal)+(second burst signal)) and a second value expressed by ((third burst signal)-(fourth burst signal))/((third burst signal)+(fourth burst signal)) from the amplitudes of the first to fourth burst signals detected by the reading/writing circuit to move the head to a position at which the obtained first value and the obtained second value coincide with each other, a ROM for storing a reference value with which abnormality of the head is determined and a CPU for determining whether or not the difference between the absolute value of the first value when the head has been moved to the position at which the first value and the second va

Abstract: A method of testing a magnetic head with a spin-valve MR element which includes at least a pinned layer, a free layer and a non-magnetic layer for magnetically separating the pinned layer and the free layer. The method includes a step of measuring an output voltage of the spin-valve MR element under application of an external alternating magnetic field to the magnetic head in a direction parallel to a magnetization direction of the pinned layer, a step of obtaining a .rho.-H loop characteristics of the spin-valve MR element from the measured output voltage, and a step of judging pinned direction of the spin-valve MR element in accordance with a polarity of an inclination of the obtained .rho.-H loop characteristics.

Abstract: A method and apparatus for loading and unloading a slider onto the surface of a substrate. The present invention includes a suspension assembly that supports a slider having an air bearing surface. The suspension assembly is coupled to a guide rod that is biased toward a first, second and third bearing. The guide rod remains in continuous contact with at least two bearings. Movement of the slider toward or away from the substrate surface is accomplished by changing the position of one or more of the bearings. In this manner, a set of pivot points acting upon the guide rod is varied as the slider is rotated toward or away from the disk surface such that the axis of rotation of the slider varies as the slider is rotated toward or away from the substrate surface. The loader is also configured to minimize the lateral movement of the slider along the surface of the substrate as the slider is loaded or unloaded from the substrate surface.

Abstract: A fastening portion 1a of a plate spring 1 of a head unit H supported by a support member 12 and an arm portion 1d is pressed by a pressurizing pin 22a to impart the same displacement to a slider 4 as a Z-height when the head unit is mounted to an apparatus. In this condition, the inclination of the slider 4 is measured, and, further, the arm portion 1d is twisted by a tool 30 to correct deformation in the roll direction. Since the plate spring 1 is corrected in the same condition as when the unit is mounted to the apparatus, an accurate correcting operation is conducted.

Abstract: A memory media tester uses a dynamic threshold margin between the sensor signal produced by a sensor and a threshold level. The dynamic threshold margin is generated as a function of a DC signal generated by converting the sensor signal to a DC voltage, where the sensor signal is composed of a noise level and signal spikes. The rate of change of the DC converted signal is controlled in order to prevent the DC converted signal from being significantly affected by the signal spikes. The dynamic threshold margin may be produced as a dynamic threshold level, a dynamically amplified output signal, or both. The sensitivity of the dynamic threshold margin may be electronically adjusted. The dynamic threshold margin automatically adjusts to changes in the DC converted signal, such as when there is a change in the surface roughness of the media, or when the sensor loses sensitivity.

Abstract: A method for testing electrical connectivity between conductive structures on a chip that is preferably layered with conductive and nonconductive layers. The method includes determining the layer on which each structure is located and defining the perimeter of each structure. Conductive layer connections between each of the layers are determined, and, for each structure, the points of intersection between the perimeter of that structure and the perimeter of each other structure on the chip are also determined. Finally, electrical connections between the structures are determined using the points of intersection and the conductive layer connections.

Abstract: A magnetic recording and/or reproduction apparatus which is low in load to a CPU for calculating measurement data of a projection amount of a magnetic head and is small in capacity required for a non-volatile memory for storing resulting values of calculation of the CPU includes a measurement instrument for measuring a position and a projection amount of a magnetic head held on a rotary drum, a digital circuit for converting the position and the projection amount into digital data in response to a reference signal generated for each rotation of the rotary drum, a memory for storing initial values of the position and the projection amount, and a CPU for comparing the initial values stored in the memory with the rotational position and the projection amount measured by the measurement instrument.

Abstract: For evaluating Barkhausen noise of a magnetoresistive head in a frequency range where it is used for read/write of recording media, in an inspection device of a magnetoresistive head (10) of the invention having an external magnetic field generator (1) for applying an external magnetic field to a magnetoresistive element (11) of the magnetoresistive head, and a noise measurement section (2) for evaluating noise of a signal output of the magnetoresistive element according to the external magnetic field, an inductive head (20) is applied in the external magnetic field generator for generating the external magnetic field.

Abstract: A process is presented for the direct determination of characteristic magnetic values of thin magnetizable layers, in which an element creating a magnetic field creates the magnetization of a part surface in such a way that the thin magnetizable layer, the element creating the magnetic field, and a magnetic field sensor are located in a relative position of rest to one another. The magnetic field sensor is then positioned opposite the magnetized part surface by a relative movement of the element creating the magnetic field, the magnetic field sensor, and the thin magnetic layer. During the subsequent measurement of the magnetization of the part surface, the thin magnetic layer, the element creating the magnetic field, and the magnetic field sensor are in a relative position of rest to one another.

Abstract: A method for characterizing a head in a hard drive assembly based on a magnetic read center shift and a read sensitivity change of the head. A disk attached to a hard disk drive assembly having a plurality of tracks each having a track centerline is provided. One of the tracks has a plurality of sectors, one of the sectors having a servo field with an A burst, a B burst and a C burst, where the A burst and the C burst have a common boundary located at a track centerline and where B burst has a center that is positioned along the track centerline. Each sector also has a data field. The read element is aligned with the B servo burst and a write excitation field is applied to the write element. The amplitudes of an A burst and a C burst located in a following sector of the track are then read to provide an A burst amplitude value and a C burst amplitude value.

Abstract: A test method and apparatus for use with a plurality of magnetically sensitive elements having a fixed relative physical sequence, and with a plurality of electrical lead sets through each of which the magnetic field being experienced by a respective one of said magnetically sensitive elements can be sensed. The method includes the steps of placing the magnetically sensitive elements in a variable magnetic field and determining a respective magnetic field setting at which each given one of the lead sets indicates the presence of a magnetic null. The results of such a test can be used to determine which lead sets are connected to which magnetic elements, and/or to determine whether at least one lead set is mis-connected.

Abstract: A wear indicator is incorporated on the slider of a magnetic transducer in a magnetic storage system for in operation on-the-fly detection of the state of wear of the transducer. The wear indicator involves monitoring a change in an electrical property of an electrical circuit structure as the transducer is worn by abrasion against the magnetic disk medium. In one aspect of the present invention, the resistance (or conductance) of the circuit is monitored during disk drive operations. Part of the resistance (conductance) circuit structure is mounted on the slider and it is physically worn along with the wearing of the transducer. A predetermined change in resistance (or conductance) gives an indication of the predetermined wear limit at which the transducer should be replaced prior to its actual failure. In a specific embodiment, the circuit is configured such that an open circuit (infinite resistance or zero conductance) indicates that the wear limit has been reached.

Abstract: A method and apparatus for testing a magnetic head provided with at least one MR transducer. The method includes a step of applying a sense current varying with respect to time to the MR transducer element via input/output terminals of the MR transducer element, and a step of measuring a terminal voltage across the input/output terminals of the MR transducer element to check varying resistance characteristics of the MR transducer element with respect to the variation of the applied sense current.

Abstract: A technique for suppression of stray pickup interference signal during testing of a magneto-resistive head assembly with an external exciting magnetic field. An interruptable phase lock loop and an interruptable amplitude lock loop temporarily hold a replica of the stray-pickup interference signal.

Abstract: A test apparatus for testing a plurality of magnetic recording heads. The apparatus includes a tool which supports a bar that contains a number of individual magnetic recording heads. Alternatively, the tester may contain a tool which supports a plurality of individual sliders. The tool locates the heads within a magnetic field emanating from a coil wound magnet. The magnet has a length and permeability that provides a uniform magnetic field for each slider in the entire bar. The test apparatus includes a probe card that has a plurality of probe needles which make simultaneous contact with the bonding pads of each head. The needles are coupled to a test circuit that applies a constant current to the magnetic recording heads and measure a change in voltage as a function of a varying magnetic field. The tester can sequentially test the heads without spatially moving the bar, thereby minimizing the test cycle time of testing the heads. Alternatively, the tester may test two or more of the heads simultaneously.

Abstract: An apparatus for testing magnetic heads and disks comprises a phase locked loop (11) with a phase detector (13) formed by an analog-to-digital converter (40) and a digital-to-analog converter (50). A sine wave signal is supplied to an analog input of an ADC (40) and raw data pulses are supplied to the clock input the of ADC. A phase detector (13) detects deviations in the positions of raw data pulses from the zero crossings of the sine wave signal. A PLL (11) locks in the locations of the zero crossings of the sine wave signal and ADC samples constitute instantaneous values of a bit-shift distribution. These values are processed by a DSP (70). The resulting bit-shift distribution is generated during one disk revolution.

Abstract: A method for testing slider/disk contact in a disk drive is described. The disk drive comprises a rotating disk having tracks and a head mounted by an actuator for selective positioning of the head over any one of the tracks of the disk. The head includes a slider. The method comprises the steps of positioning the head at each of a preselected set of tracks, while at each one of the preselected set of tracks, rotating the disk of the disk drive at a preselected rotational velocity and using the head of the disk drive, at each track, to write a signal having a substantially uniform pattern on the disk as it rotates. Thereafter, rotating the disk at a fixed preselected rotational velocity, and while rotating at the fixed preselected rotational velocity, using the head to read back the signals written at each one of the preselected set of tracks. The read back signals are used to determine rotational velocities at which slider/disk contact occurs.

Abstract: A magnetic sensor is disposed in an opposing relationship to a rotating magnetic head device with a magnetic head mounted thereon and placed in noncontact therewith so as to fall outside a lap angle .alpha. of a magnetic tape. The magnetic sensor is used as a part of oscillating elements of an oscillator circuit. By noting that a magnetic resistance of a magnetic circuit at a rotational position where the magnetic head faces the magnetic sensor changes according to the degree of extension of the magnetic head from the surface of a drum, and taking the change in magnetic resistance as a variation in oscillating frequency, the rate of wear of the magnetic head is measured. Since the change in magnetic resistance is taken as the variation in oscillating frequency, the degree of extension of the magnetic head, i.e., the rate of wear of the magnetic head can be measured with high accuracy.

Abstract: A method and apparatus for testing an integrated magnetic head assembly for normal operation. The head assembly includes an inductive write element and a MR read element. The method includes a step of applying an external alternating magnetic field to a plurality of magnetic head assemblies which are aligned on a head block and are not yet individually separated from the head block, in a direction perpendicular to an ABS of the head block, and also applying high frequency current to the inductive write element so that alternating leakage magnetic field from the inductive write element is applied to the MR read element, and a step of measuring varying resistance characteristics of the MR read element with respect to the variation of the external alternating magnetic field and to the variation of the alternating leakage magnetic field.

Abstract: A low-cost, portable, magnetic ink printer calibration system including a device which directly measures magnetic flux from recorded magnetic ink characters and provides an electrical signal representative of that flux, an amplifier to convert the electrical signal into a readable signal level, and a device to provide a measure of that signal level so that the signal can be compared to one produced by a reference character and the comparison results used for printer calibration.

Abstract: A monitoring apparatus is provided for determining permeabilities of a vacuum-deposited second pole piece of a magnetic head at the wafer level by providing wafer-mounted monitors which have layers formed by the same masking and deposition steps employed in making the magnetic heads so that the layers of the monitors are replicated layers, except for a shaping layer on top of a replicated second pole piece of some of the monitors. Each monitor is a transformer wherein each of a primary winding and a secondary winding comprises essentially a replicated magnetic head. The first and second pole pieces of the replicated magnetic heads are joined so as to magnetically couple the primary and secondary windings that constitute the transformer.

Abstract: A tester for measuring the resistance of magnetoresistive heads as a function of the magnetic field applied to the heads. The tester applies a time varying magnetic field to the magnetoresistive head to be tested and filters the resulting time varying (AC) voltage signal indicative of the resistance of the head with a capacitor to remove the DC component of the signal. The AC component of the signal is then amplified, digitized, and analyzed to obtain the resistance properties of the magnetoresistive head.

Abstract: A testing apparatus for detecting popcorn noise in magnetic heads comprises a fully integrated testing system which includes an analog circuit portion and a digital circuit portion. The analog circuit portion is implemented to interface with a magnetic head while the digital circuit portion is designed to store the testing sequence, analyze the testing data, control and execute the testing routines. The testing apparatus is designed for production environments where testing data are required instantaneously as feedback for production process monitoring.

Abstract: A method and apparatus for testing for mechanical defects in a disc drive during manufacturing test is disclosed. Resonances in the disc drive are excited by injecting a sinusoidal test signal of known magnitude and frequency into an incoming servo position error (SPE) signal in the servo loop to provide a modified SPE. While the test signal is injected, the modified SPE is sampled and filtered to characterize the test frequency in the modified SPE which is compared to a resultant frequency characterized in the incoming SPE. The presence of resonances in the disc drive structure will result in an increase in the gain of the loop as indicated by the characterized resonant frequencies from the incoming and modified SPE. When the gain exceeds predetermined criteria, an error flag is set indicative of a failure condition for the disc drive, enabling the disc drive to be removed from test for subsequent remedial actions.

Abstract: In the simplest embodiment of the invention, the apparatus holds the edge of the magnetized film to be measured close to, and above, a linearly biased magnetoresistive (MR) element. Magnetic poles appearing at the magnetic discontinuity at the edge of the film generate a magnetic field which is incident on the MR element, and which results in a measurable change in the element's resistivity. In a preferred embodiment, a pair of MR elements are placed so that they are both linearly biased by a magnet; only one of the MR elements being in close proximity to, and influenced by the magnetic field emanating from the edge of the magnetized film. The second MR element, selected for matched characteristics with the first MR element, is located out of the field of the magnetized film, but still subject to the same temperature environment and field noise as the first MR element.

Abstract: A load open state detection circuit includes a driver having X and Y terminals between which an inductive load is connected and which receive drive signals, a first transistor whose base is connected to the X terminal and whose collector is connected to a terminal supplied with a predetermined voltage, a second transistor whose base is connected to the Y terminal and whose collector is connected to the terminal supplied with a predetermined voltage and third and fourth transistors having bases thereof connected to input terminals supplied with respective drive signals. A fifth transistor has a base connected to the base of the first transistor, a collector connected to a resistor which is in turn connected to the collector of the first transistor, and an emitter connected to a second resistor which is connected to the emitter of the first transistor.

Abstract: A preamplifier circuit for a computer data storage system disk drive read/write head (or HSA) includes multiple test modes to enable electrical testing of the preamplifier, the read/write heads, and associated circuitry without physically probing the components or circuitry. Communication between the preamplifier and a host controller provides for test mode selection and test mode enablement within the preamplifier. Testing occurs using only the normal interface connector to the head disk assembly (HDA) in which the preamplifier and HSA are embodied. Properties such as electrical resistance, ESD, preamplifier bond wire connection integrity, head bond wire and solder joint integrity, and connections from the head slider to the preamplifier leads are all tested. Testing occurs without probing to provide efficient, reliable, and cost effective manufacturing and testing benefits of the read/write heads, flex assembly, HSA, and HDA.

Abstract: Benzothiophenes and related compounds of the formula ##STR1## are estrogen agonists which are useful for treating prostatic and diseases, obesity and bone loss in male animals.

Abstract: A method and apparatus (10, 410) for testing magnetic media read/write head components such as a head element bar (46) and a slider assembly (546). The component to be tested is held in a head bar holding assembly (44) or an alternate head holding assembly (544), and positioned with a head gross positioning assembly (18) or a head fine positioning assembly (16) over a localized portion (50) of a flexible magnetic medium (28) which is caused to spin in relation to a stabilizer plate (20) by a media spin motor (28). The localized portion (50) is deformed to bring the localized portion (50) of the flexible magnetic medium (28) into proximity with the component under test.