774results about "Functional testing of recording heads" patented technology

A method and system for providing a disk drive is described. The disk drive includes media such as one or more disks, a slider, and a head residing on the slider. The head has an air-bearing surface (ABS), a portion of which contacts the media during touchdown. The head further includes a plurality of touchdown sensors. A first touchdown sensor is proximate to the ABS, while a second touchdown sensor is distal from the ABS. The touchdown sensors are capable of detecting a temperature change of 0.1 degree Celsius or, in some embodiments, smaller.

A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and an ambient temperature reading. Test data is written to and read from the disk using different write current settings to generate a plurality of corresponding quality metrics. The quality metrics are evaluated to generate an optimized write current setting for the ambient temperature reading. In one embodiment, the first write current setting is selected relative to a previously optimized write current setting that corresponds to the ambient temperature reading. This embodiment expedites the optimization process by testing write current settings surrounding a previous write current setting rather than testing the entire range of write current settings.

A disk drive is disclosed which generates a pole tip protrusion (PTP) measurement by performing a write operation to heat the transducer while measuring a fly height of the transducer. A first data sequence written to the disk is read without heating the transducer to generate a first signal measurement. A second data sequence is then written to the disk in order to heat the transducer, and the first data sequence is again read to generate a second signal measurement. The PTP measurement is then generated in response to the first and second signal measurements.

A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and a plurality of ambient temperature readings. Test data is written to and read from the disk to generate quality metrics that are evaluated to generate an optimized write current setting for each ambient temperature reading. In one embodiment, the optimized write current settings are derived during manufacturing and used in-the-field during normal operation. In another embodiment, the optimized write current settings are re-optimized in-the-field to compensate for changes in the drive operating characteristics that occur over time (e.g., environmental changes and electrical and mechanical changes).

A disk drive is disclosed comprising a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors. The disk drive further comprises a plurality of heads, such as a top head and a bottom head. Control circuitry within the disk drive determines a head-switch preheat period used to format the disk. The head-switch preheat period is calibrated by selecting one of the heads to write a test pattern to the disk, and then preheating the selected head for a preheat period prior to reading the test pattern from the disk to generate a read signal. The head-switch preheat period is determined for the selected head in response to the read signal.

A method of estimating a writer / reader gap in a disk drive is disclosed. During a first revolution of the disk, a clock is synchronized to a first preamble and used to measure a write delay to write a second sync mark to the disk relative to a first sync mark. During a second revolution of the disk, the clock is again synchronized to the first preamble and used to measure a read delay required to detect the second sync mark relative to the first sync mark. The writer / reader gap is then estimated in response to the measured write delay and the measured read delay, for example, by computing a difference between the measured write delay and the measured read delay.

A method of measuring a bevel angle in a write pole comprises the step of providing a mask over a wafer containing the write pole. The mask has a first opening over the write pole and a second opening over a sacrificial region of the wafer. The sacrificial region comprises a same material as the write pole. The method further comprises the steps of performing a beveling operation on the write pole and the sacrificial region to form a first bevel in the write pole and a second bevel in the sacrificial region, and measuring an angle of the second bevel in the sacrificial region to determine the bevel angle of the write pole.

A system and method for the production level screening of low flying magnetic heads in the manufacture of disk drive head disk assemblies (HDAs) is disclosed. A test disk is provided and has a plurality of bumps extending from at least one surface thereof. The test disk is rotated to fly a head of a head gimbal assembly selected from the group adjacent the surface of the test disk. An interaction of the head with one or more of the plurality of bumps may be sensed and the head gimbal assembly may be screened out from the group in response to the sensing of the interaction.

A head for use in a drive includes a heating element capable of generating heat sufficient to cause the head to have a shape that is similar or identical to the shape that the head has when performing an operation (e.g. writing) on a recording medium in the drive. The heating element is activated when the operation is not being performed. Hence, a head generates the same amount (or similar amount) of heat and is therefore at the same temperature (also called “operating temperature”), regardless of whether or not an operation (such as writing) is being performed. Therefore, the head maintains a fixed shape or has a shape that varies minimally, within a predetermined range around the fixed shape, that in turn results in maintaining fly height (distance between the head and the recording medium). The heating element may be implemented to use loss mechanisms inherent in a write transducer, e.g. by providing a center tap to the write transducer. When using a center tapped write transducer, currents in phase with one another are provided to perform a write operation. When not performing the write operation, the same currents are provided, but out of phase.

The magnetic disk drive system has a read head and a write head, writes data on the track of the disk, and reads data on the track of the disk. In the present invention, the distance between the heads in the circumferential direction of the disk is computed. The distance between the heads is computed based on the distance between the position of the write head where said data is written and the position of the read head where said data is read. The timing when data is written by the write head is determined by adding said distance to the position where the data is written. Thus, the efficiency of the format of the disk is improved.

A method of connecting a plurality of probe pins to a plurality of first external connection pads, which are provided on a head gimbal assembly and are electrically connected to a plurality of terminal electrodes of a write magnetic head element, respectively, and a plurality of second external connection pads, which are provided on the head gimbal assembly and are electrically connected to a plurality of terminal electrodes of a read magnetic head element. In the connection method, an approach direction of the probe pins to the first external connection pads and an approach direction of the probe pins to the second external connection pads are made different from each other.

The magnetic tape device includes: a magnetic tape; and a reproducing head, in which the reproducing head is a magnetic head including a tunnel magnetoresistance effect type element as a reproducing element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, and logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050.

An apparatus and method for automatically adjusting the gram load and static attitude in a head suspension assembly comprising one or more lasers, a fiber optic switch, a measurement apparatus and a computer control means. The fiber optic switch includes a plurality of fiber optic lines which direct the output of the laser to well-defined regions on the suspensions in a disk drive. Irradiation of the suspension by the laser causes a load change which alters the static attitude change in the slider. In the method of the present invention, the initial gram load or static attitude is measured by the measurement apparatus and the control means calculates how much energy is required to cause the change needed to achieve the desired condition. Other information, such as the type of laser to be used is also specified by the control means. The laser then delivers output to the suspension through the fiber optic line having an angled end and the static attitude or gram load is remeasured to determine if additional adjustment is required.

A disk drive with switchable power levels for the heaters in the sliders is disclosed. The invention includes a switch for the electrical circuit of each heater which selects between two or more voltages to apply to the power control element and the heater with at least a high and a low voltage option. The heater power control circuit dissipates a certain amount of heat as a part of the control process. By having a low voltage option the disk drive can save power and reduce the amount of heat dissipated by the heater control circuit when high power is not required. The programmable switch is controlled by the drive control system. The high power setting can be used during manufacturing testing or otherwise if higher heater power is needed. The low power setting is used for normal operation or to save power.

There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read / write element, and a write track width is twice or more as large as a read track width in the head.

A heater for changing a projection distance protrusion value by thermal expansion accompanying electric-power-distributed heating is provided in a head having at least a reading element. At desired correction timing, a changed distance detection unit measures a clearance changed distance in a state in which the head is positioned to a track on the recording medium while increasing the amount of electric power distributed to the heater. A contact determination unit determines that the head is brought into contact with the recording medium when a derivative value of the clearance changed distance is below a predetermined threshold value. A measurement output unit outputs the clearance changed distance detected by the changed distance detection unit at the time of contact determination of the contact determination unit as a measurement result of the clearance between the reading element and the recording medium.

An HDC asserts the read gate of an RDC when a read head is positioned in a sector located before a sector that a hot system instructs to read data when seen from the rotation direction of a storage medium. The data that the read head has read from the sector is used to adapt a circuit that constitutes the RDC. However, the data is not transferred to the host system. Such a process is repeated until the read head reaches a position where data stored in a sector whose data has been instructed to read can be read. In this way, time needed to adapt a circuit that constitutes a read channel can be shortened.

An evaluation method that can easily evaluate properties of a carbon protective film and a lubricant on a magnetic-disk surface or particularly, an evaluation method of a magnetic disk in which the properties of the magnetic-disk surface can be evaluated accurately so that a strict demand for interactions between the magnetic-disk surface and a head can be met is provided. In a state in which an element portion of the magnetic head provided with the head element portion that projects by thermal expansion is projected, after being brought into contact with a predetermined radial position on the surface of the rotating magnetic disk, the head is further made to perform seeking in a state in which the element portion is projected by a specified amount, whereby the properties of the carbon film or the lubricant formed on the magnetic-disk surface is evaluated.

A disk drive with switchable power levels for the heaters in the sliders is disclosed. The invention includes a switch for the electrical circuit of each heater which selects between two or more voltages to apply to the power control element and the heater with at least a high and a low voltage option. The heater power control circuit dissipates a certain amount of heat as a part of the control process. By having a low voltage option the disk drive can save power and reduce the amount of heat dissipated by the heater control circuit when high power is not required. The programmable switch is controlled by the drive control system. The high power setting can be used during manufacturing testing or otherwise if higher heater power is needed. The low power setting is used for normal operation or to save power.

The present invention provides an improved magnetic disk drive manufacturing method that is to be employed during an interval between magnetic disk drive assembly completion and shipment. In one embodiment, a magnetic disk drive has an interface connector. The magnetic disk drive is retained by a shock absorber so that the interface connector is exposed. A testing side connector mounted on a base plate is connected to the interface connector of the magnetic disk drive that is retained by the shock absorber. A host apparatus transfers a test / adjustment program to the magnetic disk drive via the testing side connector. The magnetic disk drive executes the test / adjustment program.

A method of determining and monitoring head polarity of data heads comprises performing a head polarity detection routine. The head polarity detection routine comprises the step of setting a read gate period duration to a first value. The routine also comprises searching for a good address mark signal during a first read gate period with a channel polarity set to a first polarity. The routine further comprises identifying a polarity of a data head based upon the channel polarity when the good address mark is detected.

In various embodiments, systems and methods to detect signal irregularity caused by defects in the read / write head element are disclosed. In some embodiments, an exemplary system comprises a memory and a processor. The processor is coupled to the memory and is configured to implement a filter module and a detector module. The filter module is configured to generate a test waveform based on data read from a medium by a storage device head to be tested. The detector module is configured to generate a signal quality value based on a property of at least a portion of the test waveform, compare the signal quality value to an event threshold, and generate an event indicator based on the comparison, the event indicator indicating possible instability of the storage device head.

An apparatus, system, and method for measuring thermally induced electric resistance changes in thermally assisted magnetic recording are disclosed for monitoring laser light output in thermally assisted magnetic recording disk drives. An electrical lead is coupled to a read / write head element. A first electrical resistance in the read / write head element is measured. The read / write head is heated by a laser and a second electrical resistance in the read / write head element is measured. The electrical resistance may be monitored at regular intervals when the read / write head element is on the ramp or the electrical resistance measurements may be continuously monitored as the read / write head flies over the magnetic media.

A system and method for determining head-disk contact (HDC) in a magnetic recording disk drive uses the signal from the magnetoresistive (MR) read head. The analog MR signal is digitized and input to a digital signal processor with circuitry and / or software for integrating the signal amplitude over a low-frequency range. The calculated value from the integration when the slider is out-of-contact with the disk is a reference value. The same integration is then performed during operation of the disk drive and the measured value is compared to the reference value. If the measured value exceeds the reference value by some predetermined amount, this is an indication of the onset of HDC or that HDC has occurred. The method can be used in head-disk testers to facilitate the design and testing of disk drive components, such as slider-suspension assemblies and fly-height actuators located on the slider to alter the head-disk spacing, and in disk drives to control fly-height actuators and to take corrective action prior to HDC.