Western Digital Technologies, Inc.

Broadcom Corporation

Western Digital Corporation

Seagate Technology Incorporated

Credence Systems Corporation

Nayna Networks, Inc.

Richard Koonwai Wong

Ara W Nazarian

Thao P Trieu

Guoxiao Guo

King Wai Thomas Lau

Wei Guo

Michael A Chang

Edgar D Sheh

Sanghoon Chu

Charles W Simmons

Fatih Sarigoz

Jie Yu

Brian Kenneth Tanner

Jack M Chue

Jenghung Chen

Carl E Barlow

Carlos Ramos

Min Chen

Teik Ee Yeo

John W Vanlaanen

Xiao Yang

David A Baker

Russ A Quisenberry

Davide Giovenzana

Benjamin Geunbae Ryu

Dar-Der Chang

Michael Barrett Wolfson

Sidney Peng

David Collins

A disk drive is disclosed comprising a disk having a plurality of data tracks defined by servo sectors, where each data track comprises a plurality of data sectors, and each servo sector comprises a servo preamble and servo data. The disk drive further comprises a head comprising a read element and a write element, and a servo read channel comprising an analog front end and a timing recovery circuit. During an access operation, data preceding the servo preamble of a first servo sector in the first data track is read in order to initialize the analog front end of the servo read channel. At least part of the servo preamble is read to initialize the timing recovery circuit of the servo read channel, and at least part of the servo data of the servo sector is read using the timing recovery circuit.

Disk drive initializing servo read channel by reading data preceding servo preamble during access operation

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by full sectors and intervening short servo sectors, where each full servo sector comprises a preamble, a sync mark, and servo bursts, and each short servo sector comprises a reference pattern and servo bursts. A first phase error is generated based on the sync mark in a first full servo sector, and a disk locked clock is adjusted in response to the first phase error. A second phase error is generated based on the reference pattern in a first short servo sector, and the second phase error is processed to determine whether the disk locked clock slipped a cycle before the head reaching the first short servo sector.

Disk drive compensating for cycle slip of disk locked clock when reading mini-wedge

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, and at least one servo sector of a servo track comprises a partial track address. A read signal generated by the head is processed to detect a current servo zone for the head, and the read signal is processed to detect the partial track address in one of the servo sectors of the current servo zone. A full track address is generated based on the detected servo zone and the detected partial track address.

Data storage device estimating servo zone to reduce size of track address

A disk drive is disclosed comprising a head actuated over a disk. A position y of the head is measured based on servo sectors, and the measured position y of the head is adjusted based on:11()where z1 represents a first adjusted position and c1(y) represents first correction values. The first adjusted position z1 is adjusted based on:2=1+2(1)where z2 represents a second adjusted position and c2(z1) represents second correction values. The first and second correction values are combined based on:3()=1()+2(1()).The measured position y of the head is adjusted based on:3=3()where z3 represents a third adjusted position comprising the adjustment based on c1(y) and the adjustment based on c2(y), and c3(y) represents third correction values.

Disk drive iteratively adapting correction value that compensates for non-linearity of head

Magnetic reference patterns may be generated on a disk or other magnetic media without the need for seed wedges. This involves writing a first magnetic reference pattern to the disk with a servo writer. The disk may then be transferred to a hard disk drive. Control circuitry within the hard disk drive may recognize the first magnetic reference pattern and then position a RW head within the hard disk drive based on the first magnetic reference pattern. As the RW drive is accurately positioned based on the first magnetic reference pattern a second magnetic reference pattern may be written to the disk using the RW head. The RW head location is determined based on the velocity and phase between the read-write head and spiral sync marks contained within the first magnetic reference pattern.

Method for establishing and maintaining radial position for hard disk drive self servo write without seed wedges

Embodiments of the present invention significantly reduce the number and complexity of processing operations to be performed. This is done by receiving the learned run out or vector A to be rotated by phase q. This phase q may be limited to a &#x3c0;/4 resolution. Sine function values and cosine function values based on q are selected from a group of values comprising &#x2212;1, 0, and +1. The sine function values and cosine function values selected may then be applied to the learned run out or vector A to rotate the vector A by phase q. Because the sine and cosine values are limited to &#x2212;1, 0 and +1 many multiplication processing operations are eliminated. This greatly simplifies the processing requirements associated with phase rotating of this learned run out.

Hard disk drive repeatable runout feed forward cancellation with high speed and low power phase rotator

The present invention provides a method of generating magnetic reference patterns on a disk or other magnetic media. This involves writing a first magnetic reference pattern to the disk with a servo writer. The disk may then be transferred to a hard disk drive. Control circuitry within the hard disk drive may recognize the first magnetic reference pattern and then position a RW head within the hard disk drive based on the first magnetic reference pattern. As the RW drive is accurately positioned based on the first magnetic reference pattern a second magnetic reference pattern may be written to the disk using the RW head. The RW head location is determined based on the velocity and phase between the read-write head and servo setter marks contained within the first magnetic reference pattern.

Read write (RW) head position control for self servo writing process

Disclosed is a disk drive having a plant with a moveable transducer and a servo controller that more precisely controls the transducer during short to medium seeks by producing a multi-rate feed-forward command effort signal. The servo controller includes a reference position generator that provides a reference position signal that varies as a function of time along a shaped position profile for moving the transducer from a start position to a target position in a smoothly controlled fashion, a feed-forward control path that receives the reference position signal and applies a feed-forward command effort signal at a feed-forward rate that is greater than the servo sampling rate to move the actuator more closely along the shaped position profile between servo samples; and a feedback control path that receives the reference position signal and the indicated position signal and applies a feedback command effort signal at the servo sampling rate based on a difference between the reference position signal and the indicated position signal to make minor corrections to error remaining after application of prior feed-forward command effort signals.

Disk drive with feed-forward control path that receives a reference position signal to apply a feed-forward command effort at a rate greater than a servo sampling rate

A method for switching signals using one of a plurality of mirrors in an array structure. The method includes determining an optical path to be formed between an input fiber and an output fiber. The method also includes determining a set of mirrors to be used to form the optical path. The set of mirrors includes at least a first mirror. The first mirror is coupled to a mechanical spring assembly and an actuation assembly. The method captures an analog signal indicative of a spatial position of the first mirror using a position sensing device. The sensing device is coupled to the mirror. The method also converts the signal analog signal into a digital signal. The method processes the digital signal indicative of the spatial position of the mirror using the digital signal processing device to obtain a characteristic of the mirror. The method provides a control signal based upon the characteristic of the mirror. The converts the control signal into an analog control signal. The method uses the analog control signal with the actuation assembly to set a desired position of the first mirror.

Method for transparent switching and controlling optical signals using mirror designs

A floating interface assembly provides signal paths between an integrated circuit (IC) test head and contact pads on a load board or probe card accessing an IC to be tested. Pogo pins or other contactors for contacting the contact pads are mounted on the interface assembly and linked to the test head by flexible conductors. The interface assembly is attached to the test head by springs to allow it the freedom to rotate to some extent about any axis. As the test head approaches the contact pads, alignment pins engage and orient the interface assembly so that its contactors will mate with the contact pads. As the contactors come into contact with the contact pads, the interface assembly adjusts the plane of the contactors so as to evenly distribute contact pressure over all contactor pads.

Floating interface for integrated circuit test head

Repeatable runout cancellation in sectored servo disk drive positioning system

A method in a magnetic storage disk drive for independently learning and thereafter canceling repeatable runout that is written to the servo fields of each servo track during the servo writing process. The method does not require a servo writer because the disk drive may independently detect the runout without spinning out of control in response to such runout by operating its servo control loop in a low bandwidth mode so that it is less responsive to the higher frequency components of the runout, and by removing the effect of the DC component of the runout or selected harmonics on each revolution. The method takes several revolutions to 'learn' the servo wedges of a current track by initializing a wedge runout value for each servo wedge and an average uncorrected runout value and then successively developing an interim wedge runout estimate for each servo wedge by adding a fractional portion .lambda. of a raw position error signal to a fractional portion (1-.lambda.) of the wedge runout value, computing a corrected position error signal by subtracting the interim wedge runout estimate from the raw position error signal, and computing a new wedge runout value by subtracting the average uncorrected runout value from the interim wedge runout estimate and, subsequent to each revolution, updating the average uncorrected runout value.

Repeatable runout cancellation in sectored servo disk drive positioning

In the disk controller in a hard disk system, the microcontroller is an integral part of the servo positioning system. The servo positioning system is the system responsible for positioning the read/write heads. This involves moving the read/write heads from track to track and holding the head in place as data is read or written. A time and calculation intensive portion of the control algorithm is the calculation of the position error signal, which represents the degree to which the actual position of the head varies from the desired position. A hardware position error signal circuit is provided to calculate this signal, thus freeing microprocessor bandwidth for other tasks and facilitating a more stable controller. Furthermore, a circuit for adjusting erroneous cylinder numbers is provided.

Hardware PES calculator

A method used to implement a sampled servo control system in a magnetic disk drive for generating a fractional track portion of a position error signal to correctably maintain the alignment of a read transducer (or associated write transducer) relative to a centerline of one of a plurality of a concentric data tracks upon a rotating data storage disk. The system uses a hybrid approach of determining a fractional track position by using a two-burst algorithm when possible and using a multi-burst algorithm only when necessary. The system is particularly suited to determining fraction track position when jogging a relatively narrow magnetoresistive read transducer with a servo pattern normally useful only for wider transducers, namely a pattern of four angularly sequential servo bursts A, B, C, D that are 100% of a track pitch in width and are arranged in quadrature. In this context, the preferred system reads all four 100% servo bursts and then uniquely selects between a two-burst algorithm and a four-burst algorithm to generate a fractional track position relative to a two-burst centerline (A/B or C/D) or a four-burst centerline (N-Q or N+Q). In general, the servo system selects between the two-burst and the four-burst algorithms based on the transducer's passing through a two-burst zone or a four-burst zone, which preferably overlap, as determined from the relative burst amplitudes of all four servo bursts. When operating at a position in which the zones overlap, the preferred system is biased to select the zone corresponding to the algorithm used during the immediately previous servo sample in order to add stability.

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San Jose, CA, United States of America

Richard Koonwai Wong