Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1998-01-08
2000-05-02
Huber, Paul W.
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
369 50, 360 7708, G11B 509, G11B 5596
Patent
active
060580844
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a disk-shaped recording medium suitable for use in, for example, a magnetic disk unit or an optical disk device, and a disk unit using the disk-shaped recording medium. This invention relates specifically to a disk-shaped recording medium capable of recording segments IDs indicative of positions of the direction of rotation in a servo region thereof to improve the reliability of a sector ID-less system and to establish rapid frame synchronization. The invention also relates to a disk unit using the disk-shaped recording medium.
BACKGROUND ART
Servo regions for recording servo information and data regions for recording user data have heretofore been formed alternately in a disk-shaped recording medium employed in a disk unit, such as a magnetic disk unit or a magnet-optic disk device, along the direction of rotation of the disk-shaped recording medium. A sample servo system is known for generating a clock signal for obtaining timing in order to reproduce servo information or record and reproduce user data. This type of system generates a clock signal from a clock mark recorded in advance at a discrete position (e.g., servo region) on the disk-shaped recording medium by a magnetic means or a physical means. Further, a sector servo system for generating a clock signal from a data string itself is also known.
The prior art will hereinafter be described using a sample servo type magnetic disk unit as an example.
FIG. 11 shows one example of a magnetic disk employed in a sample servo type magnetic disk unit. The magnetic disk 201 has concentric or spiral tracks. Each of the tracks is uniformly divided into a plurality of segments (frames), e.g., 100 segments along the direction of rotation thereof. Further, the plurality of segments are respectively divided into servo regions (servo segments) for recording servo information and data regions (data segments) for recording user data.
The servo region comprises an address region, a fine region and a clock region. A clock mark 202 for generating a clock signal is radially and continuously recorded in the clock region. In a reproduce isolated or solitary waveform of the clock mark 202, for example, the time of presence of a peak indicates the supply of clock information synchronized with the rotation of the magnetic disk 201 to a data system and a servo system.
A fine pattern 204 is recorded in the fine region. In a magnetic head positioning servo, the fine pattern 204 is a pattern which is required by a tracking mode for accurately positioning a head to the center of a target track by the magnetic head positioning servo and indicates the position of the magnetic head relative to the track. The fine pattern 204 is composed of four magnetic patterns of A, B, X and Y.
An access pattern (track address code) 203 is recorded in the address region. The access pattern 203 is a pattern which is required in a track seek mode for shifting the magnetic head to the target track by the magnetic head positioning servo, encoding track addresses by, for example, gray codes, and changing them in length and layout so that they differ every track.
The clock mark 202 is synchronized by a clock generating circuit to be described later. However, the approximate position of presence of the clock mark 202 must be sought before the establishment of initial synchronization. As a synchronous auxiliary pattern, a unique pattern 205 is recorded in the address region in a predetermined cycle in place of the access pattern 203, e.g., at several tens of points per one track. The unique pattern 205 is composed of a plurality of lines (patterns) continuous in the radial direction. The unique pattern 205 can be easily detected even before the generation of the clock signal. For example, a violation code, which does not appear in an encoded data series, is normally used. Upon establishment of initial synchronization, the unique pattern 205 is first detected and a clock gate signal is thereafter generated after the elapse of a predetermined number of clocks,
REFERENCES:
patent: 5523903 (1996-06-01), Hetzler et al.
Yamakoshi Takamichi
Yamamoto Noriyuki
Huber Paul W.
Sony Corporation
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