Seagate Technology Incorporated

Fujitsu Corporation

Opto Tech Corporation

Miniscribe Corporation

Todd David Baumann

James Joseph Touchton

Roger R Bracht

Leroy L Leach

EweChye Tan

Dorrel R Silvy

Method and apparatus for data security in a data storage device. In some embodiments, a first version of firmware is installed in a memory of the device. The firmware is used by a programmable processor to control accesses to a rotatable data recording medium on which is written pre-recorded servo positioning data used to position a data transducer. A newer, second version of the firmwave is subsequently installed in the memory to replace the first version of firmware. The second version of the firmware includes an instruction to corrupt a selected portion of the servo positioning data on the medium in order to authenticate the second version of the firmware. During a subsequent initialization of the device, host access is granted based on detection of the corruption of the selected portion of the servo positioning data.

Protecting against unauthorized firmware updates using induced servo errors

A method and apparatus for normalizing the acceleration constant used by a servo control system in a disc drive are disclosed. The method and apparatus involve performing a test seek and summing the position error measured at sample periods during the deceleration phase of the test seek. A correction factor applied to the acceleration constant is adjusted if the sum of the position errors differs from the sum of position errors measured from a nominal seek. Adjusting the correction factor to cause a position error sum that is close or equal to the sum from the nominal seek provides a relatively symmetrical seek arrival without additional correction factor offsets or gain variances.

Method and apparatus to normalize the acceleration constant

The present invention is a method of correcting radial position error signal (PES) values by utilizing predetermined error correction values located at predetermined locations in advance of their associated servo fields. Calculated correction values are written to zero-acceleration path (ZAP) fields on the disc during the manufacture process. ZAP fields are positioned before the servo fields whose PES they are designed to correct. The ZAP field is comprised of two or more correction data elements to correct subsequent PES values. As the read/write head flies along a track, it reads a ZAP field, and stores the PES correction data in local random access memory (RAM). Subsequently, the corresponding servo field is read and the stored PES correction data is used to correct the PES. Two types of ZAP fields are written on the disc&mdash;one type for read operations, another type for write operations. An arrangement of ZAP fields relative to servo and data track nulls allows for the read head to gather the ZAP field information in the write position, without having to move from the write position to the read position and back to the write position in the middle of a write operation.

Method and apparatus to encode position error signal correction information

During the deceleration portion of a seek operation, the current level provided to the actuator motor of a disk drive is based on a desired linear deceleration versus time profile that has been temporally advanced by half of a servo data position sampling interval. At each position sampling interval, a new current level is determined and maintained for the interval between samples. The actual deceleration current follows a staircase curve centered on the desired profile so as to be self-synchronizing. The current level is also adjusted to compensate for the delay between obtaining a new servo data position sample and applying a new current level to the motor.

Method and apparatus for self-synchronizing seek deceleration

An apparatus for detecting an over-velocity error condition of a head actuator driven by a voice coil motor in a hard disk drive system includes an integrator for providing an integrated value of the current flowing through the voice coil motor and a detector for detecting when the integrated value exceeds a threshold value. In response to this detection, the supply of current through the voice coil motor is interrupted. To prevent false detections, the integrator is inhibited until the motor current reaches a level indicative of a track access operation.

Method and apparatus for preventing an over-velocity error condition of

A focus initialization system adapted for use with an optical data recording system. Focus initialization is performed while a tracking servo loop is in an open loop mode, and an objective lens is fixedly positioned along a tracking axis. With a focus servo system in an open loop mode, the objective lens is cyclically driven along a focus axis about a neutral position and between offset positions. Displacement of the offset positions from the neutral position is increased with each successive cycle. After the objective lens has been positioned at each peak offset position, the focus servo loop is closed and track crossings resultant from eccentricity of the servo tracks on the record carrier are counted. Focus capture is recognized when at least a predetermined number of track crossings are counted during a predetermined time period. If less than the predetermined number of track crossings are counted during the predetermined time period, the focus servo loop is opened and the objective lens is driven to a successive offset position.

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Berthoud, CO, United States of America

Todd David Baumann