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AssigneeInternational Business Machines Corporation
InventorsThomas Robert Albrecht, Robert Carl Barrett, James Howard Eaton
Estimating the term…
A track following servo system is disclosed for use with magnetic tape systems in which magnetic servo track patterns contain transitions recorded at more than on azimuthal orientation across the width of the servo track. The timing of a signal derived from reading at any point across the width of such a pattern varies continuously as the read head is moved across the servo track. The pattern is read by a servo read head whose width is small compared to the servo track pattern. The combination of a wide servo pattern and a narrow servo read head offers excellent position sensing linearity and dynamic range. In the preferred embodiment, the servo read head is also narrow with respect to the data tracks, which provides the additional advantages of superior immunity to position sensing errors caused by defects or temporal variations in the servo read head, defects in the servo pattern on the tape, wear of the head or tape, or debris collection on the head or tape. Position sensing with this system is achieved by deriving a ratio of two servo pattern intervals and therefore is insensitive to tape speed during reading. The servo patterns may include spacing intervals recognizable for error detection and correction purposes. Servo tracks are recorded using a patterned multiple gap servo write head whose magnetic gaps have geometries appropriate to generate the desired servo patterns. The patterned gaps of the servo write head are produced by photolithographically defined electroplating of permalloy on a ferrite ring head structure.
A magnetic storage medium having a servo pattern recorded into servo tracks for generating a servo read head signal from a servo read head as the head is moved relative to the servo pattern, the servo pattern comprising a cyclic sequence of magnetic flux transitions that extend continuously across the width of the servo tracks and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of a servo track, including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation, such that the stripes are arranged in groups having a plurality of sequential stripes at the first azimuthal orientation followed by a plurality of sequential stripes at the second azimuthal orientation.
A magnetic storage medium having a servo pattern recorded into servo tracks for generating a servo read head signal from a servo read head as the head is moved relative to the servo pattern, the servo pattern comprising a cyclic sequence of magnetic flux transitions that extend continuously across the width of the servo tracks and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of a servo track, including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation and the stripes are arranged in groups containing a plurality of sequential subgroups, each subgroup containing stripes at more than one azimuthal orientation, the groups being separated by synchronization features.
A tape cartridge comprising:
A tape cartridge having a servo pattern recorded into servo tracks for generating a servo read head signal from a servo read head as the head is moved relative to the servo pattern, the servo pattern comprising a cyclic sequence of magnetic flux transitions that extend continuously across the width of the servo tracks and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of a servo track, including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation and the stripes are arranged in groups containing a plurality of sequential subgroups, each subgroup containing stripes at more than one azimuthal orientation, the groups being separated by synchronization features.
A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:
A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:
A data storage system comprising:
A data storage system comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
With provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing…: for…
Information storage based on relative movement between record carrier and transducer
Term ended 30 Jun 2014 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
This invention relates generally to recording and reading data from magnetic storage media and, more particularly, to servo control systems that maintain the position of a magnetic head relative to tracks in magnetic storage media.
2. Description of the Related Art
FIG. 1 is a perspective view of a tape drive storage device and associated tape cartridge constructed in accordance with the present invention.
FIG. 2 is a schematic representation of the magnetic head and servo control system of the tape drive and cartridge combination illustrated in FIG. 1.
FIG. 3 is a schematic representation of an alternative head assembly arrangement in accordance with the invention.
FIG. 1 shows a timing based servo tape system 10 constructed in accordance with the present invention. The system includes a tape drive 12 that accepts a tape data cartridge 14 and is connected to a host processor 16 by a data cable 18. The tape cartridge comprises a housing 19 containing a loop of magnetic tape 20. The system is constructed for use with servo control information comprising a repeating servo pattern of magnetic flux transitions that are recorded in tracks on the magnetic tape 20 in the data cartridge and extend across the width of the tracks such that a servo position information signal generated by reading the servo control information varies continuously as a magnetic servo read head is moved across the width of a track in a translating direction, thereby indicating the relative position of the head within the track. The tape drive 12 can read the servo control information and generate a position signal to control the position of an associated data read head, or can write the servo control information into tracks on a data cartridge using a magnetic servo write head, or can do both. The system is optimized for the magnetic tape environment, so that the magnitude of the position signal error due to wear and debris is reduced and such errors are easier to detect.
The tape drive 12 includes a receiving slot 22 into which the cartridge 14 is inserted. The host processor 16 can comprise, for example, a personal computer such as the IBM Corporation “PS/2” personal computer, or can be a workstation such as the IBM Corporation “RS6000” workstation, or can be a mini computer, such as the IBM Corporation “AS400” computer. The tape drive 12 preferably is compatible with such host processors and, for example, tape library systems that employ tape cartridges, such as IBM Corporation “3480” and “3490” tape drive units. The tape cartridge 14 can assume any one of a variety of cartridge formats, including, for example, conventional 8 mm, 4 mm, ¼-inch, and ½-inch data cartridge formats.
FIG. 2 is a view looking down on a portion of the magnetic tape 20 of the cartridge 14 (FIG. 1) past a head assembly 24 of the tape drive unit 12. The tape is shown in phantom with dashed lines where it passes beneath the head assembly. The head assembly is shown in solid lines and includes a relatively narrow servo read head 26 that detects a servo pattern recorded in a servo track 27 of the tape. Also shown, for purposes of illustrating relative size, is a data read head 28 of the head assembly that is positioned over a data track region 29 of the tape containing multiple data tracks for reading data recorded in a data track. FIG. 2 shows a single servo read head and a single data read head for simplicity of illustration. Those skilled in the art will appreciate that most tape systems have multiple servo tracks, multiple servo read heads, and multiple data read and write heads.