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 housing for enclosing a measuring apparatus for a hard disk recording medium and a recording apparatus for recording a signal on the hard disk recording medium is provided with a fan including a high efficiency particulate air filter. The fan blows air onto the hard disk recording medium and the recording apparatus under measurement through the high efficiency particulate air filter at a substantially constant air temperature and at a substantially constant air flow rate. An automatic door is located at a position other than an air protection area which includes positions of the hard disk recording medium under measurement by the recording apparatus and the recording apparatus, and includes a predetermined surrounding area. The automatic door shields the other area from the air protection area in the housing for enclosing the measuring apparatus under no measurement.

Abstract: A method of manufacturing disc drives. Before a pivot cartridge is assembled into a disc drive, impedance readings of the pivot cartridge are taken, preferably, at more than one rotational position and across a frequency range. The pivot cartridge is accepted for assembly into the disc drive only if its impedance readings compare favorably with readings taken of a good pivot cartridge. Otherwise, the pivot cartridge is rejected and the impedance readings are analyzed to provide identification of the defect in the pivot cartridge. In addition, a system and a storage device readable by a computer system for implementing the method of screening pivot cartridges and identifying causes of defects is provided.

Abstract: A method of calculating an amplitude decay rate of a magnetic storage medium. The method involves (a) writing a test track to the magnetic storage medium and measuring the initial amplitude of the test track to obtain a reference amplitude; (b) performing a DC erase on the test track; (c) measuring and storing the test track amplitude after step (b) together with a time at which the measurement was made; (d) writing a reference track; (e) measuring and storing the reference track amplitude after step (d); (f) repeating steps (b) to (e) until a DC erase amplitude decay rate has been established; and (g) calculating a normal amplitude decay rate for the magnetic storage medium from the DC erase amplitude decay rate.

Abstract: A preferred system for measuring bearing friction first measures voice coil motor current values required to move an actuator arm assembly to each of several cylinder position intervals. Torque values required to move the actuator arm assembly are then computed using the measured voice coil motor currents. Drive-level bearing friction values are then calculated using the computed torque values and then combined into a composite indicator.

Abstract: An apparatus and method for detecting and marking delamination defects on thin film disks are disclosed. The apparatus includes a read/write (R/W) head and a burnishing head mounted on separate arms that access the disk while spinning on the test stand. The controller uses the R/W head to perform an initial magnetic test of selected areas on the disk to establish an initial defect map. The burnish head is then flown over the surface for an extended time to accelerate and open up the latent delamination defects by impacting protruding material. The R/W head is then used to perform a second magnetic test which is compared against the first test to identify the delamination defects which have been developed by the burnishing. The delamination defects are then marked with a magnetic pattern which aids in optically locating the defect during subsequent failure analysis.

Abstract: A magnetic disk certifier includes a defect detector circuit comprising a low-pass filter for extracting a low frequency component of the read-out signal, the low frequency component containing a signal component of the error, a signal generator circuit for generating a signal having a predetermined frequency lower than the frequency of the read-out signal, a synthesizer circuit for synthesizing an output signal of the low-pass filter and the signal outputted from the signal generator circuit and a comparator for generating an error signal by comparing the synthesized signal from the synthesizer circuit with a predetermined reference level.

Abstract: The magnetic powder for validity determining ink is composed of magnetic oxide power having a Curie temperature between −50°C. and 150°C. and a mean powder particle diameter of 10 &mgr;m or less.

Abstract: A method and apparatus are provided for testing a head to be used in a disc drive. The method is performed in a spin-stand and includes steps of positioning a head over a radial position on a disc, reading test data from a track at the radial position, reading servo data from the track, and using the servo data to position the head at a desired location within the track. The apparatus for practicing this method includes a disc capable of spinning, a positioning system capable of establishing a position for a head relative to the disc, a servo circuit capable of converting a servo signal into a position value, and a feedback circuit capable of controlling the positioning system based on the position value.

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 apparatus for detecting disk drive head instability. Normal head fluctuation is removed from the criterion used to detect whether a head is unstable. The present invention accumulates error signals in an accumulator and calculates a criterion having an average fluctuation removed using the accumulated error signals. The criterion is calculated according to (max+min)−(2×average), wherein max is the maximum error signal, min is the minimum error signal and average is the average error signal. The criterion is then compared to a predetermine threshold to determine whether the head is unstable. A head is determined to be unstable when (max+min)−(2×average) is greater than the predetermined threshold.

Abstract: A method and apparatus are provided for testing a microactuator that forms part of a suspension assembly in a disc drive. The method and apparatus test the microactuator before placing the suspension assembly in a disc drive. In the invention, the head is positioned over a track on a disc based in part on servo information read from the disc. At least one input signal is then applied to at last one microactuator on the suspension assembly. Servo information is then read from the disc to determine a change in the position of the head. By comparing the change in the position of the head to the input signal applied to the microactuator, a performance characteristic of a microactuator can be determined.

Abstract: A test simulation circuit includes a simulated read/write head with a magnet shield and a magnetoresistive sensor exposed at a lapped surface. The test simulation circuit also includes first and second electrical test path connected respectively to the magnet shield and the magnetoresistive sensor. The second electrical test path is electrically isolated from the first electrical test path.

Abstract: A method and apparatus for characterizing asymmetries of a magneto-resistive type head in proximity to a magnetic media such as a magnetic disk of a hard disk drive. The method includes using the magneto-resistive type head to read a continuous signal from the magnetic media to provide a read back signal. Energies contained in the read back signal which occur in excess of a predetermined threshold for the positive and negative portions of the read back signal are then determined. The energies may be determined by accumulating sampled signal values from the read back signal in registers during times at which the read back signal exceeds the threshold.

Abstract: The present invention is directed to a disc heater for use with a spin-stand. The disc heater is adapted to heat a disc that is mounted to a spindle of the spin-stand. The disc heater includes a heater support, a heater, and a controller. The heater support is couplable adjacent the spindle and the disc and is adapted to support the heater near a surface of the disc. The heater produces heat that raises at least a surface of the disc to a temperature that simulates an operating temperature of a disc drive. The controller is electrically coupled to the heater and controls the heat produced by the heater. The spin-stand is adapted to perform various tests on the transducing head. Additional tests, such as accelerated aging studies, can also be performed on the disc.

Abstract: An apparatus and a method for measuring the magnetic properties of recording media. Particularly, the invention is directed to the measurement of the coercivity of recording media having high coercivity values. The apparatus for measuring the magnetic properties of recording media contains a thermal source to increase the temperature of a selected portion of the recording media, thus temporally decreasing the coercivity of the recording media in the selected portion. Magnetic transitions are induced by applying a magnetic field to the regions of the medium affected by the thermal source. The electromagnet applies an incrementally increasing DC field to the selected portion to generate variable magnetization data.

Abstract: A method for manufacturing a disk drive includes assembling the head disk assembly in a clean room, performing servo writing upon the head disk assembly in the clean room, and performing a head disk assembly test upon the head disk assembly in the clean room. The head disk assembly is then connected to the controller printed circuit board assembly to form a drive-under-test. The drive-under-test is then transported to an integrated test system and electrically connected thereto. The integrated tests system then performs substantially all of the required manufacturing tests upon the drive-under-test, thereby substantially reducing the labor and floor space associated therewith.

Abstract: The present invention provides an efficient and accurate method for determining an outer diameter roll-off value for a magnetic disc that provides information relevant to fly height stability. The present invention can be implemented in a disc manufacturing process to insure that each disc passing through the manufacturing process has an acceptable outer diameter roll-off value that accommodates stable fly height at the outer data tracks of a maximized data track band width.

Abstract: Magnetic characterization of the magnetic field emanating from an RWH device is presented using a magnetostrictive layer as a probe between the device and the scanned SFM tip. The findings suggest a very promising technique to resolve magnetic fields laterally at least in the 100 nm realm. Other magnetosensitive properties such as the magnetoelastic and the piezomagnetic effect can be used in a similar way to infer magnetic characteristics of microstructures or of magnetic multilayers.

Abstract: A system for testing and cleaning a removable media drive such as a tape drive includes a utility cartridge and computer readable program code to initiate utility operations. The utility cartridge comprises computer readable magnetic storage media for performing testing operations thereon and non-magnetic cleaning media for cleaning the drive head. A method for testing and cleaning a removable media drive is also disclosed, as is a method for providing the system described herein.

Abstract: An apparatus and a method for measuring the remanence curve of a magnetic material with high accuracy is disclosed. First and second pulse magnetic field coils generate a rapidly-changing pulse magnetic field in the space where a magnetic material is located. First and second air-core coils generate a space of a zero magnetic field as well as a finite magnetic field gradient around the magnetic material after application of a pulse magnetic field. A detector detects the force generated by the cooperation between the magnetic field gradient and the magnetic moment of the magnetic material. An arithmetic unit 33 determines the residual magnetization characteristic of the magnetic material based on the detection result in the detector.

Abstract: A method and apparatus are provided for detection of the presence of slider airbearing resonance using surface analysis test (SAT) primary defect list (P-list) data. The P-list in the disk drive is selected. Checking for a cluster threshold of adjacent tracks within a sector to identify a SAT cluster is performed. Responsive to identifying the SAT cluster, checking for multiple defects on some tracks within the SAT cluster is performed. Responsive to identifying multiple defects on some tracks within the SAT cluster, the SAT cluster is converted to a binary matrix map. A histogram is generated for the binary matrix map. The harmonic magnitude content of the histogram from harmonics centered about a predetermined slider airbearing resonance frequency is identified.

Abstract: A spin valve magnetoresistive effect type element assessment device includes a head assaying device having a magnetic disk provided with an assaying track where magnetic information is recorded, an oscilloscope for receiving a reproducing signal from an SV head employing an SV element through an amplifier, and a PC for measuring a track profile, namely, data representing relative position dependency of an output from the SV head with respect to the assaying track by controlling the head assaying device and oscilloscope.

Abstract: An apparatus and a method for measuring signal decay of a magnetic recording medium using an approach in which a control track and a track of interest are located on one track are disclosed.

Abstract: In summary, preferred embodiments disclose a system, method, and program for generating and displaying disk drive performance data. A center stripe of one sector of one track on a recordable surface is read. An indication is made indicating whether the read operation to the center of the sector succeeded. Each offset stripe from the center of the track in the sector within the track is read and indication is made as to whether each read operation to each offset stripe succeeded. Output in human observable format is generated indicating whether each offset stripe and the center stripe for the sector and track were read successfully or could not be read.

Abstract: A testing apparatus for a magnetic head or a magnetic disk, includes a magnetic disk; a magnetic head moving mechanism which holds a magnetic head and which moves the magnetic head to a predetermined position in a radial direction of the magnetic disk; a movement mechanism control device for driving the magnetic head moving mechanism, wherein the movement mechanism control device moves the magnetic head moving mechanism to a predetermined radial position corresponding to position data; a read/write control device for writing a predetermined magnetic signal on the magnetic disk using the magnetic head, and for reading a magnetic signal of the magnetic disk using the magnetic head; and a memory for storing therein position data embedded in a data surface of the magnetic disk, extracted from the magnetic signal which is read by the read/write control device. A testing method is also disclosed.

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 magnetic disk certifier includes a defect detector circuit comprising a low-pass filter for extracting a low frequency component of the read-out signal, the low frequency component containing a signal component of the error, a signal generator circuit for generating a signal having a predetermined frequency lower than the frequency of the read-out signal, a synthesizer circuit for synthesizing an output signal of the low-pass filter and the signal outputted from the signal generator circuit and a comparator for generating an error signal by comparing the synthesized signal from the synthesizer circuit with a predetermined reference level.

Abstract: A method and apparatus are provided for efficiently testing magnetic media in which a read level test is performed using an approximation for an average signal level in determining a test threshold and while reading data and testing against the approximate average read signal level, the data signal level is averaged to determine the real average read signal and this value is then used to adjust the results of the comparisons performed against the approximate average read level.

Abstract: An apparatus and method for evaluating surface characteristics of a recording disc prior to incorporation into a disc drive. A glide test system includes a glide test head supportable over the disc, the glide test head having a negative-pressure air bearing slider and a contact sensor which outputs a signal when the glide test head contacts a feature of the disc surface. The glide test head and the disc are characterized as opposing plates of a variable capacitor with a dielectric layer therebetween including at least a layer of air supporting the glide test head. A voltage source, operably coupled to the glide test head and the disc, applies a fly height control voltage across the capacitor to adjust the fly height of the glide test head. The disc surface preferably comprises a data region configured to magnetically store data as the disc is rotated and a texturized landing zone configured to support the disc drive read/write head when the disc is stopped.

Abstract: A method and apparatus for using control apparatuses and read/write apparatuses within a disc drive to create a microtrack that is used to probe the magnetic sensitivity of each portion of a magnetic stripe of a magneto-resistive read/write head in the disc drive. The method can be executed by first selecting a target track and then recording a test signal along the target track. Next, the target track is trimmed to create a microtrack, the microtrack having a microtrack width less than the stripe width, the microtrack having a first circumferential edge and a second circumferential edge. Subsequently, the magneto-resistive stripe is positioned at various radial locales traversing the microtrack, and at each locale the magneto-resistive stripe is used to read the test signal recorded on the microtrack, thereby producing a detected signal at each of the various locales. Finally, a signal-strength profile is determined.

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 byte wide flaw scan interface is used to identify an characterize flaws in a disk medium. In one embodiment, the associated disk drive (100) includes head electronics (120) associated with a disk drive controller (122) via an NRZ interface (127). The NRZ interface (127) is operative for transmitting flaw information for a particular disk address via 8 predefined bit lines. The bit lines have separate definitions for user data sector addresses and servo wedge addresses. By using this byte wide interface, media flaws of various types can be identified and characterized based on a single pass of the transducer head over the disk surface thereby shortening testing times.

Abstract: A system for use in a memory disk test system is disclosed. The system comprises a fixture for holding a disk head and a moveable slide coupled to the fixture. The system includes a non-magnetic motor system engageably coupled to the slide for moving the test fixture. A system and method in accordance with the present invention offers an SDT system which utilizes piezoelectric motors resulting in higher throughput in producing memory disks. The system and method further achieves high performance, is lower cost in implementation, and is more compact than conventional SDT systems. The system and method, by removing time delay, offers the advantage of cycle time reduction over conventional SDT systems.

Abstract: Herein is disclosed a method and apparatus for controlling a lapping process, so as to create a read/write head that contains a primary magnetoresistive read element with a desired stripe height. An improved lapping guide is achieved by incorporating a secondary magnetoresistive element into a read/write head. By virtue of its location on the same read/write head as a primary magnetoresistive element (used for reading data during operation of the disc drive), the secondary element is located in close proximity to the primary element, resulting in smaller tolerances in aligning or relating the top edges of the primary and secondary elements. Accordingly, the secondary magnetoresistive element more reliably serves as a proxy for the primary element. Optionally, the secondary magnetoresistive element may be fashioned with identical dimensions as the primary element, so as to render the secondary element equivalent to the primary element with regard to magnetic sensitivity.

Abstract: A method for testing a thin-film magnetic head with a MR read head element includes a step of applying a low-frequency or DC external magnetic field to the thin-film magnetic head from a stationary magnetic field generation unit, a step of executing a high-frequency amplification of an output from the MR read head element under the application of the external magnetic field to provide a high-frequency amplified signal, a step of deriving only a high-frequency component from the high-frequency amplified signal to provide a high-frequency component signal, and a step of judging whether the thin-film magnetic head occurs a noise or not by using the high-frequency component signal.

Abstract: A method of characterizing and screening a disc drive based on a voice coil motor pivot friction developed during a low velocity seek operation consists of determining estimated drive level bias values required by the voice coil motor to move an actuator arm assembly during a fast seek, then determining a low velocity drive level bias values required by the voice coil motor to move an actuator arm assembly during a slow seek, then computing a difference between the estimate drive level bias values and the low velocity drive level bias values, then determining a hit counter value based on comparing the computed difference with a predetermined threshold value, and then characterizing the disc drive based on the hit counter value.

Abstract: An apparatus and method for determining the configuration of a disc drive head-disc assembly (HDA). The HDA includes an array of rotatable discs and an actuator adjacent the discs, with the actuator supporting a maximum number of heads in a fully populated configuration and a reduced number of heads in a depopulated configuration. Each head is disposed at a unique head position. A servo circuit determines an impedance of a selected head position having a head when the disc drive is fully populated but not when the disc drive is depopulated. The servo circuit identifies this configuration of the HDA in relation to the determined impedance, and initializes the drive accordingly.

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 recording/reproducing method and apparatus having the function of tracking a head on a data track formed on a recording medium of a lower-order specifications and on a data track formed on a recording medium of the upper-order specifications. During calibration, a controller 10 causes a locally maximum value and a locally minimum value of the signal level of a sine wave signal to be sequentially stored as the table information in a storage unit 11, as a magnetic head is moved by a head driving unit 7 in a direction perpendicular to the plural tracks. The sine wave signal is generated by an optical encoder and represents a substantially sinusoidal signal which completes its full cycle on the track basis. During tracking, the locally maximum value and the locally minimum value associated with a targeted track are read out from the storage unit 11 and a target sine wave level information is generated based on the generated locally maximum value and the locally minimum value.

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 magnetic disk tester which also incorporates a sensor such as an AFM or MFM is described. The device is able directly and quickly to detect and characterize sub-micrometric defects on the surface of magnetic disks. A process for finding and characterizing defects on a magnetic disk according to the invention comprises the steps of rotating the magnetic disk using a spindle motor; writing data on the magnetic disk at selected positions; finding a position on the magnetic disk having a defect which produces an error when reading the data from the magnetic disk; determining coordinates of the defect referenced from an index on the disk; stopping the spindle motor; positioning a sensing device such as an AFM or MFM head over the defect; and sensing characteristics of the defect which aid in determining a cause of the defect.

Abstract: The present invention is a method for defect locating marking and analysis of thin film hard disks. Initially, the hard disk is disposed in a disk drive and the disk is formatted with sector identification lines and data written into data tracks. During the data writing process a disk surface defect is identified by its sector, track and byte location. The hard disk is then marked such that the defect can be located at a later time. The erased bands aid in later locating the defect. After the defect locating erasures have been completed for each defect found on the disk, the disk is removed from the hard disk drive for further analysis. The disk is then placed on the stage of a microscope and ferromagnetic fluid is applied to the disk in order to make the erased tracks visible. The ferromagnetic fluid is applied out to the end of the track erasure of the track that includes the defect, without application of ferromagnetic fluid to the defect itself.

Abstract: The disclosure is directed to a method for identifying and classifying data surface defects on the disks of a rigid disk data storage device. By partitioning each surface into cells and sub-sampling every Nth track, the number and location of defects can be determined. The number of stored defects is then examined to determine whether clusters of contiguous cells exist wherein defect totals exceed a predetermined threshold number. This enables the location of clusters on multiple surfaces to be examined for axial alignment, radial alignment or random occurrence as an indication of the source of damage. To obtain further verification of the data surface condition, the location of a defect cluster can be scanned using a utility that evaluates each track within the defect cluster or area.

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: Disclosed are a method of detecting a thermal asperity of a magnetic storage device which detects that a magnetic resistance element comes into contact with a magnetic storage medium, and a circuit thereof. This method comprises detecting an amplitude of an output of the magnetic resistance element, and creating a slice level that is m-times (m>1) as large as an output level. The slice level of an output relative value is created from the output of the magnetic resistance element, and hence the slice level having a magnitude corresponding to the output level of each magnetic resistance element can be automatically created. It is therefore feasible to accurately detect the thermal asperity of each magnetic resistance element.

Abstract: A method for measuring the total track width of a test track and adjacent erase bands written over an erased area of magnetic media is disclosed. The test track has a known test track center and effective track width, and contains a periodic signal having a known maximum signal strength. An erase is performed at a certain position from the test track center, followed by a reading of the remaining signal strength of the test track, measured at the test track center. The remaining signal strength is stored as a data value as a function of the position of the erase. The erase, reading, and data value storage steps are repeated at various positions from the test track center, each position being successively closer to the test track center. When the remaining signal strength is less than 50% of the maximum signal strength, the test track is rewritten. The erase, reading, and data value storage steps are repeated at various positions from the test track center, this time on the opposite side of the test track.

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: An improved media defect glide test head assembly which incorporates a wide thermo-resistive (TR) element suitable for detection of thermal asperities on the surfaces of magnetic recording discs. The TR element of the inventive glide test head assembly is very wide when compared to magneto-resistive (MR) elements in normal MR read/write heads. In the currently preferred embodiment, the TR element is envisioned to be as wide as is possible to fabricate on the trailing edge of an air bearing element of the glide test head assembly, to enable detection of thermal asperities across a relatively wide band of disc surface during each disc rotation, thus enabling rapid testing of the media surface. In a second aspect of the invention, the wide TR element is envisioned to be formed of nickel or other material having a large thermal resistance coefficient.

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.