Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data clocking
Patent
1995-02-27
1997-10-21
Psitos, Aristotelis M.
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data clocking
360135, G11B 509
Patent
active
056802676
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a disk apparatus, and is applicable to, for example, a hard-disk apparatus.
BACKGROUND ART
In the hard disk, each of a plurality of data recording areas (hereinafter referred to as tracks) concentrically arranged with respect to the center of the disk is divided into a plurality of blocks (hereinafter referred to as sectors), and data are divided and recorded on these sectors. In hard-disk apparatuses, there has been adopted a sector servo method as a servo method which is used in reading data from sectors.
This servo method asynchronously detects a servo header from each sector, locks phase-locked loop (PLL) output by means of a synchronous (SYNC) pattern and the like, and generates various types of timing signals based on the PLL output.
A gap region (redundancy signal region, etc.) of a specified length was therefore needed in front of a servo zone, as shown in FIG. 1.
However, this servo method, as shown in FIG. 2, has the problem that, while the position and the time near the head of the sector can be controlled relatively accurately, accurate control near the end (points P1 and P2 of the figure) of the sector becomes more difficult.
That is, since the sector servo method generates a synchronizing signal at a unit of several tens of sectors per one lap of the track, it cannot follow a change in the time axis such as a change in the rotation of the disk and cannot obtain the positions of as many as several ten thousands of bit units per one lap with a high degree of accuracy.
The number of regions to which servo information is given can be increased to solve this, but it is hard to improve the track density from the viewpoint of accuracy of writing because the sector servo method writes the servo information in units of sectors. Likewise, the position on the disk could not be fixed with a high degree of accuracy for this reason.
SUMMARY OF THE INVENTION
Considering the above points, the present invention provides a disk apparatus in which an angular position on the track can be specified with a high degree of accuracy without increasing the area occupied by servo information.
To solve such problems, the present invention includes a rotational drive means for rotating and driving a disk recording medium (2) having a plurality of clock marks (CM) formed in advance at constant intervals along recording tracks, a recording and/or reproducing means (3) for recording and/or reproducing desired data on/from the disk recording medium (2), and a clock interpolation means (5B, 5C) for detecting the plurality of clock marks (CM) appearing at definite periods from a reproducing signal (S2) reproduced by the recording and/or reproducing means (3), and for generating an interpolation clock (PLL clock) subdividing a time axis between the plurality of clock marks (CM) based on a clock component sampled from the plurality of clock marks (CM).
The clock component is sampled from a plurality of clock marks CM formed in advance at constant intervals along the tracks of the disk recording medium, and an interpolation clock (PLL clock) subdividing between clock marks (CM) is generated. Thus, the clock component is sampled based not on self-clock contained in reproducing code but on the physically formed clock marks (CM) having a definite period. By generating the interpolation clock (PLL clock) based on this, a very accurate interpolation clock (PLL clock) can be obtained. As a result, the absolute coordinate position on the disk recording medium 2 can also be fixed precisely.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram showing a conventional sector structure;
FIG. 2 is a schematic diagram explaining an asynchronous sector servo method;
FIGS. 3(A) to 3(D) are schematic diagrams showing a data structure that is formed on a disk recording medium of the present invention;
FIGS. 4(A) to 4(C) are schematic diagrams explaining a hierarchical data structure in the servo pattern zone;
FIG. 5 is a schematic diagram explaining the array of segments constitutin
REFERENCES:
patent: 5276564 (1994-01-01), Hessing et al.
Takeda Toru
Tanaka Shoji
Kananen Ronald P.
Psitos Aristotelis M.
Sony Corporation
Wamsley Patrick
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