International Business Machines Corporation

Other

Todd Barry Anderson

John Jeffrey Stephenson

Mark David Hagen

Jeffrey Fred Boigenzahn

Michael Charles Stich

Amy L Warner

Earl Albert Cunningham

Michael Scott Hicken

Thomas W Glaser

Clark A Anderson

Hjalmar H Ottesen

Martin R Green

Daniel D Reno

John J Neesz

Lawrence P Segar

Gerald Lawrence Cadloni

Mark E Bofferding

Joseph M Humel

William J Hunt

John B Resman

A phase modulated servo method and apparatus are provided for use in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface for storing data. At a predefined location of the disk surface a series of servo tracks of a predetermined high gain servo pattern are written. The predetermined high gain servo pattern includes 360&deg; phase difference information within each data cylinder. The servo tracks are detected for identifying servo phase information.

Method and apparatus for phase modulated servo positioning in a direct access storage device

In a ultra high density, multiple-disk drive, track switches within a cylinder of tracks as well as track switches to tracks on other cylinders both require a movement of the head stack actuator. Track switching latency in such a disk drive is reduced by overlapping pre-movement portions of the track switching process with the data transfer operation of the currently active recording head. In addition, post-movement portions of the track switching process are overlapped with the movement of the heads so that the next selected read/write head may begin a data transfer operation immediately upon arrival at the next track. Further, the pre-movement and post-movement portions of the track-switch process may be overlapped with low displacement movement of the read/write heads relative to the currently active track or the next track.

Method and apparatus for reducing track switch latency in a disk drive

A method and an apparatus for optimizing movement of a disk drive's head actuator arm away from a magnetic latch that holds the arm in a parked position at the Inner Diameter (ID) of a disk. Current energizing of the arm's actuator motor moves the arm away from the magnetic latch and is controlled to compensate for any change in magnetic holding force. When the disk drive is powered up, a current pulse of one polarity is applied to the actuator motor. This initial current pulse normally moves the arm away from the magnetic latch and is followed by a current pulse of the opposite polarity to decelerate movement of the arm. If this initial sequence fails to move the arm away from the magnetic latch, the magnitude of the two current pulses is increased, and the opposite polarity pulse is followed by a small magnitude current of the one polarity. The read signal from the head is monitored to indicate that the arm has moved into the disk's central databand area, and then into the disk's Outer Diameter (OD) area. At this point, the magnitude of current of the one polarity is increased in small steps to gently bring the arm into contact with the disk drive's OD crash stop. The current of the one polarity is then decreased in small steps, and the arm gently moves away from the OD crash stop. The head signal is monitored until the head is positioned at a selected track.

Method and apparatus for moving a disk drive actuator away from a

A chiller device (10) for a pitcher (12) which holds a beverage (14). The pitcher (12) has a body (16) with an open top rim (18), a spout (20) on the open top rim (18) and a handle (22) on the body (16). The chiller device (10) comprises a sealed container (24) with a coolant (20) that becomes frozen is carried within the sealed container (24). A structure (28) is for maintaining the sealed container (24) with the coolant (26) within the body (16) of the pitcher (12), to keep the beverage (14) cold during a predetermined time interval. Even when the handle (22) is grasped by a hand of a person and the body (16) of the pitcher (12) tipped over to pour some of the beverage (14) from the spout (20) on the open top rim (18) into a glass, the sealed container (24) with the coolant (26) will stay within the body (16)) of the pitcher (12).

Chiller device for a pitcher

In a disk storage device dedicated servo system, a reference track is written in the outer guardband of the servo surface and each of the data surfaces. Supplemental position error signal (PES) values are obtained from the difference of servo and data surface samples at a plurality of locations around the disk and stored for access during read/write operations. The supplemental PES values are combined with the dedicated surface PES values to yield a composite PES that more accurately follows the data track centerline of the disk surface being addressed. The supplemental PES values are also periodically updated. To provide a more accurate correction of the composite PES, two consecutive supplemental values are used and an interpolation is calculated to provide a continuously changing supplemental PES value for modification of each sector actuator drive pulse between the two current supplemental PES values. Provision is also made in the apparatus to make the correction technique tolerant of tangential skew that may make tracks unreadable because of early or late timing through the provision of sequences of alternative early and later sample sector sequences.

Disk drive servo control

A controller for a voice coil motor driven disk file actuator is described. The device has an online adjustable gain characteristic for controlling movement of the actuator assembly and an estimator that estimates actuator velocity and bias. Forward gain is estimated from position and coil current measurements and compared with a nominal value to create an error signal used to adjust the controller and estimator gain characteristics. The control technique allows changes in the open loop system without changing the closed loop performance. By monitoring loop gain it is possible to alter compensator gains to maintain a constant closed loop performance.

Adaptive control technique for a dynamic system

A sector servo seek control samples each sector to obtain sector time, the track identification within a sequence of track types and a position error signal for a track location to track location seek. The device during each sector determines the actual transducer track location and the next sector projected track location with respect to the sequence of track types. The projected track location is corrected using the error signal to find the actual location, but if a sector signal is missing or erroneous, the projected location is used as the actual location, permitting a composite correction to be made when a correct sector signal is obtained. The seek time is minimized by using maximum acceleration followed by maximum deceleration while not exceeding a velocity value that would cause the device to overshoot the target track using full deceleration.

Sector servo seek control

Growing community of inventors

Rochester, MN, United States of America

Todd Barry Anderson