Abstract: The present invention pertains to an apparatus and method for recording data in a variable bit density disc drive. The disc drive includes a recording surfaces, each having a corresponding head for recording data on the recording surface. At least one head is operated at a different recording frequency from the other heads, creating a variable bit density for the different recording surfaces. The combination of head recording frequencies is determined following an error testing operation and a unique physdisc lookup table is created based on the determined recording frequencies. The physdisc lookup table is used to allocate data sectors and to convert between logical and physical block addresses.

Abstract: A method for characterizing a bearing cartridge based on a preload applied to the bearing cartridge used in a disc drive, to increase disc drive yield rates. The method begins by loading the bearing cartridge on to a test fixture and to an actuator assembly such that the actuator is rotatably attached to the base by the bearing cartridge. Then, the method includes inducing a steady swing in the actuator. Then, the method includes measuring a voltage drop that occurs across the bearing cartridge during the steady swing to characterize the preload applied to the bearing cartridge.

Abstract: A method for minimizing unbalance in the disc pack of a disc drive where the unbalance of the spindle motor is quantified and incorporated into the biasing assembly of the disc pack. In the assembly process, the discs are biased in a manner such that the unbalance of the spindle motor is considered.

Abstract: A bias current for a magnetoresistive read head is selected by defining a tuning range based on a maximum and a minimum bias current value for the head. A plurality of read operations are iteratively performed using a different bias current value over the tuning range for each iteration. The results of each read iteration are measured and a bias current is selected on the basis of the read error rates, and particularly those bias currents associated with the lowest read error rate.

Abstract: The present invention pertains to an apparatus and method for recording data in a variable bit density disc drive. The disc drive includes a recording surfaces, each having a corresponding head for recording data on the recording surface. At least one head is operated at a different recording frequency from the other heads, creating a variable bit density for the different recording surfaces. The combination of head recording frequencies is determined following an error testing operation and a unique physdisc lookup table is created based on the determined recording frequencies. The physdisc lookup table is used to allocate data sectors and to convert between logical and physical block addresses.

Abstract: A disc drive production process automatically configures the disc drive to a suitable capacity based upon the data transfer capability of each of the head/disc surface combinations in the drive. The error rate of each of the head/disc surface combinations is determined as a function of the bit density of the disc surface. Based on the data transfer capability of the head/disc surface combinations, one of three drive configuration schemes is selected. A variable BPI (bits per inch) scheme reduces the data rate of a weak head/disc surface combination while increasing the data rate of a strong head/disc surface combination. If the drive contains one very weak head/disc surface combination, a head depopulation scheme disables the very weak head. If the drive contains two or more very weak heads, a de-frequency scheme reduces the overall capacity of the drive.

Abstract: The present invention pertains to an apparatus and method for recording data in a data storage medium. The data storage medium includes a number of discs, each having at least one recording surface. Each recording surface is associated with a read/write head that records and accesses data from the surface. Each recording surface is partitioned into a number of zones. Each zone is vertically aligned with a same zone on each surface of each disc. The zone boundaries on all surfaces of the disc drive are the same. The recording frequency for each zone on all surfaces can differ for each read/write head in order to compensate for a read/write head that cannot meet the BPI error rate threshold.

Abstract: Audio or video information is stored as data files in clusters or blocks of sectors on a magnetic disc. The data files are transferred from the disc drive to one or more buffers for respective data streaming applications. Optimal buffer size is calculated using operational parameters such as transfer rates and rotational latencies. The sectors are grouped in blocks having a size equivalent to, or slightly larger than, the size of an associated host buffer for the respective application to avoid fragmentation of the data used in each buffer fill, and thereby minimize the time required to fill the buffer from the disc drive.

Abstract: A data storage device has a plurality of head/surface combinations with different data track densities on at least two surfaces. A minimum head quality is established for the data storage apparatus. Head quality is identified for each of the heads at each of a plurality of track densities. A tuned track density is selected for each surface based on the track density that corresponds to a head quality.

Abstract: A writer coil in a data head of a data storage system is tested by coupling detection circuitry to the writer coil and driving the writer coil with a periodic pulse signal generated by the detection circuitry. As a result, voltage is generated, with the detection circuitry, as a function of an inductance of the writer coil. An inductance of the writer coil is calculated as a function of the generated voltage. Electrical short circuits and discontinuities in the writer coil are identified as a function of the calculated inductance.

Abstract: A system, modules, means, and computer readable media for and a method of compensating disturbances that cause track shape irregularities on a disc in a disc drive during a disc servo-writing process performed by a servo-writer are disclosed. The disturbances substantially attributable to a nonrepeatable runout (NRRO) are present during the servo-writing process. A substantial component of the NRRO is a cage frequency generated by a spindle motor mechanism in the disc drive. A reference cage frequency is determined during a servo-writing process by using a position sensor. Then a feed-forward input signal is determined based at least on the reference cage frequency during the servo-writing process. In addition, the feed-forward input signal is feed-forwardly transmitted to the servo-writer.

Abstract: A method of implementing an automatic acoustic management feature for a disc drive includes receiving an acoustic/performance compromising factor from a host, tuning disc drive performance by applying the factor to a control parameter to generate a modified control parameter, and executing a loop for controlling a disc drive operation using the modified control parameter. In another embodiment, a disc drive has a base, a rotatable disc, an actuator assembly with an arm for carrying a head in transducing relation to the disc in response to a control signal, a receiver for receiving an acoustic/performance compromising factor, and a controller that monitors the position of the arm and generates the control signal. The controller executes a seeking control loop having a control parameter modified by applying a compromising factor to the parameter to tune the acoustic performance of the drive.

Abstract: A method of handling resonance effects on disc drives includes the steps of monitoring a position error signal (PES) for an actuator arm of a disc drive, generating a feedforward compensation signal from the PES using a bandpass filter, and applying the compensation signal to a servo control signal. The bandpass filter has a center frequency set to a known resonance frequency. A disc drive includes an actuator assembly including an arm for carrying a head in a transducing relation with respect to a disc in response to a control signal, and a controller that monitors a PES for the arm and generates the control signal. The controller includes a servo controller that generates a servo control signal from the PES, and a feedforward compensation element which bandpass filters the PES to generate a compensation signal which is combined with the servo control signal to generate the control 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: A method for characterizing a bearing cartridge based on a preload applied to the bearing cartridge used in a disc drive, to increase disc drive yield rates. The method begins by loading the bearing cartridge on to a and to an actuator assembly such that the actuator is rotatably attached to the base by the bearing cartridge. Then, the method includes inducing a steady swing in the actuator. Then, the method includes measuring a voltage drop that occurs across the bearing cartridge during the steady swing to characterize the preload applied to the bearing cartridge.

Abstract: An information handling system, such as a disc drive, including a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. The disc stack assembly includes a spindle hub rotatably coupled to the disc drive. The spindle hub has an axis of rotation about which the disc stack assembly rotates. The spindle hub includes a cylindrical portion. The disc stack assembly also includes a clamp, a disc spacer, and a disc coupled to a spindle hub. The disc spacer has an opening therein dimensioned to receive the cylindrical portion of the spindle hub. The disc spacer is asymmetrical and positioned to counter balance a mass offset in the disc stack assembly. The asymmetrical disc spacer also includes a registration surface. The registration surface is on the outer perimeter of the disc spacer. The disc spacer has a center of mass offset from the axial centerline of the opening. The disc spacer is used to counter the center of mass offset of the disc stack assembly.

Abstract: A system, method, and device for moving a plurality of heads in a disk drive is disclosed. The system comprises hard disks, read/write heads for reading from or writing to the hard disks, a voice coil motor for moving the plurality of heads, a voice coil motor driver for energizing the voice coil motor, a voltage clamp device for regulating a voltage across the voice coil motor, and a park voltage source. The voltage clamp device comprises a transistor, a switch, and a resistive divider network. During head parking, a park voltage source activates the voltage clamp device, which clamps the voltage across the voice coil motor to a fixed value, resulting in movement of the voice coil and heads towards a park location with fixed velocity.

Abstract: A system, method, and device for sensing temperature during the writing of information onto magnetic media and providing a sufficient write current for that temperature is disclosed. The system comprises a head responsive to a write current for generating a magnetic flux used in writing data onto the magnetic media, a write current source coupled to the head for receiving a write signal and providing write current to the head, and a temperature responsive device coupled to the write current source that senses temperature and provides a write signal whose magnitude is dependent on temperature.

Abstract: The present invention pertains to an apparatus and method for recording data in a data storage medium. The data storage medium includes a number of discs, each having at least one recording surface. Each recording surface is associated with a read/write head that records and accesses data from the surface. Each recording surface is partitioned into a number of zones. Each zone is vertically aligned with a same zone on each surface of each disc. The zone boundaries on all surfaces of the disc drive are the same. The recording frequency for each zone on all surfaces can differ for each read/write head in order to compensate for a read/write head that cannot meet the BPI error rate threshold.

Abstract: Head disc interference is detected and analyzed using the standard deviation of read back signal frequency. First, the amount of longitudinal head oscillation affecting transducer read/write heads located in the hard drive is measured. Measuring the longitudinal head oscillation is achieved by determining the degree of frequency modulation associated with the read-back signal as compared with a constant frequency used to write the information. Second, this measured amount of oscillation is compared to a predefined threshold value. Finally, a head disc interference alarm is activated when the oscillation is greater than the defined threshold value.