Dynamic information storage or retrieval – Storage medium structure – Optical track structure
Reexamination Certificate
2000-12-06
2003-06-24
Dinh, Tan (Department: 2653)
Dynamic information storage or retrieval
Storage medium structure
Optical track structure
C369S013350
Reexamination Certificate
active
06584066
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improvements to a storage medium which increase the storage capacity of the medium. More particularly, the present invention relates to a storage medium in which sector address information is recorded using MSR techniques.
BACKGROUND OF THE INVENTION
Optical disks are widely used as external storage media for computers. Magneto-optical disks have become popular because they are rewritable and provide a relatively high recording density. In the past, 3.5 inch magneto-optical disks were only capable of storing 128 MB of information. Recent advances, however, have enhanced the storage capacity of 3.5 inch magneto-optical disks to 1.3 GB, and even greater increases in storage capacity are presently being sought.
Magneto-optical disks include at least one recording layer formed on a substrate. Information is recorded/reproduced from magneto-optical disks using a laser light source and a magnetic source. Typically, grooves (tracking guide grooves) are formed in spiral fashion on the substrate of the medium. Data is recorded on tracks provided on lands between these grooves.
In the past, the recording density of magneto-optical disks has been limited by the diameter of the beam spot of the laser beam. However, in recent years, magneto-optical super resolution technology known as MSR (Magnetically Induced Super Resolution) has facilitated the recording and retrieving of a mark smaller than the diameter of a laser beam. For example, with a 3.5 inch magneto-optical disk, recording and retrieving of a mark smaller than the laser beam spot with track pitch of 0.90 &mgr;m and a mark length of 0.38 &mgr;m is now possible. Consequently, a ten fold increase in storage capacity to 1.3 GB has been realized.
Magneto-optical disks record and retrieve in a storage unit termed a sector. By manner of illustration,
FIGS. 12A and 12B
show a traditional MSR magneto-optical disk sector format in which sector address information portion
90
is physically formed as an indented (embossed) pit with a stamper in the same manner as a tracking groove. Sector address information
90
includes a sector mark SM which indicates the beginning of a sector, PLL phase lead-in term signal VFO
1
, address mark AM indicating the beginning of the first sector ID, first sector address ID
1
, PLL phase lead-in term signal VFO
2
, address mark AM indicating the beginning of the second sector, second sector address ID
2
and post amble PA indicating the end of the sector address information portion.
Sector address information stored in ID
1
and ID
2
includes track number and sector number information. The second sector address ID
2
stores the same information as the first sector address, and is included as a backup in case ID
1
becomes unreadable.
A gap
91
separates the sector address information portion
90
from VFO area
92
in which a VFO pattern for adjusting the frequency is recorded. Sync byte area
93
is interposed between a data area
94
, and the aforementioned VFO area
92
. A post amble (PA)
95
and buffer
96
for a buffering area are formed subsequent the data area
94
.
Data is recorded at a high density in the data area
94
portion using MSR techniques. In contrast, sector address information portion
90
is recorded at a significantly lower density than the data recorded in the data portion
94
, since it is physically formed by embossing or the like.
Accordingly, one problem associated with conventional magneto-optical storage mediums relates to the relatively large area required to store sector address information, and the ensuant decrease in usable storage capacity of the medium.
OBJECTS
One object of the present invention is to increase the usable storage capacity of a magneto-optical storage medium by reducing the area required to store sector address information.
Another object of the invention is provide a storage medium including an error correction code for correcting a sector address.
Another object of the invention is to provide an improved method for determining whether a head is in an off track condition during a read operation.
Yet another object of the invention is to provide an improved method for verifying that a write operation has written to the correct sector, where the target sector is not read prior to the writing operation.
SUMMARY
Briefly, the present invention relates to an improved storage medium for storing information. Information is stored on a plurality of tracks formed on the storage medium, each of the tracks being divided into a plurality of sectors. Each sector includes a physically formed sector beginning identifier provided at a leading portion of the sector, and an information storing portion. At least one sector address portion for storing a sector address is provided at a leading end of the information storing portion, and a data portion for storing user data is provided after the sector address portion.
These and other aspects of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings.
REFERENCES:
patent: 5422874 (1995-06-01), Birukawa et al.
patent: 5740154 (1998-04-01), Izumi et al.
patent: 6069870 (2000-05-01), Maeda et al.
patent: 6072754 (2000-06-01), Izumi
patent: 6449231 (2002-09-01), Numata
patent: 0 880 129 (1996-11-01), None
patent: 08-339540 (1996-12-01), None
patent: 10-112029 (1998-04-01), None
patent: WO97/29483 (1997-08-01), None
Dinh Tan
Fujitsu Limited
Greer Burns & Crain Ltd.
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