Optical recording medium and recording/reproduction method...

Details Optical recording medium and recording/reproduction method... Optical recording medium and recording/reproduction method...

2000-04-20

2004-06-15

Tran, Thang V. (Department: 2653)

Dynamic information storage or retrieval

Binary pulse train information signal

Format arrangement processing for auxiliary information

C369S047220, C369S047270, C369S275300, C369S275400

Reexamination Certificate

active

06751178

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority of Korean Application Nos. 99-14286 and 99-24296, Apr. 21, 1999 and Jun. 25, 1999 respectively, in the Korea Patent Office, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording medium, and more particularly, to an optical recording medium, and a recording/reproduction method therefor, in which a header, used for addressing, is disposed between adjacent land and/or groove tracks, a basic addressing unit having a first predetermined size is assigned, and a minimum recording unit having a second predetermined size is assigned.
2. Description of the Related Art
A mass recording capacity and high speed reproduction of optical discs is required for recording and/or reproducing high definition (HD) images. Accordingly, a multimedia technology of recording and/or reproducing a large quantity of information on and/or from a recording medium such as a rewritable or read only HD-digital versatile disc (DVD) is required.
Various methods have been suggested for satisfying the requirements of mass recording capacity and high speed reproduction. For example, the area of a disc or the rate of rotation may be increased. However, such methods are not practical since they require an increase in the sizes of a disc and a player and also result in increased production cost. Thus, it is preferable to increase the recording density per unit area of the disc, rather than increase the area of a disc at the rate of rotation.
The size of a recording laser spot is proportional to the laser wavelength and inversely proportional to the numerical aperture (NA) of an object lens. Accordingly, to increase the recording density per unit area of the disc, the laser wavelength should be decreased, or an object lens having a high numerical aperture should be used to decrease track pitch.
In such an optical disc, particularly, a recordable disc, a recording area for recording data in regular units is segmented into regular basic recording units (e.g., sectors or frames). In writing or reading data to or from an area which is a physically segmented basic recording unit, it is essential for an optical pick-up unit (hereinafter, referred to as a pickup) to move to the exact position of the corresponding area at high speed without error.
To allow a pickup to move to an exact position a header field in the optical disc is utilized. In a 2.6 gigabyte (GB) or 4.7 GB DVD-RAM, a header field for each sector is assigned 128 bytes. The information of the header field is written on the disc in the form of pre-pits during the manufacture of a substrate. The header field is composed of a variable frequency oscillator region for a phase locked loop (PLL), a physical identifier (PID) region to which a sector number is assigned, an ID error detection (IED) region for storing ID error detection information, and a postamble (PA) region for regulating modulation. A header field is appropriately disposed at the front portion of a sector. When a pickup accesses a desired position, a microcomputer (not shown), recognizing signals which are stored in the header field and picked up by the pickup, can detect the sector number and sector type of a sector corresponding to the accessed position and determine whether the sector is included in a land track or a groove track. Moreover, the microcomputer can perform servo control using the picked up signals.
Representative examples of the structures of conventional headers are shown in
FIGS. 1A through 1D
. “G” indicates a groove track, and “L” indicates a land track. In
FIG. 1A
, a header is located between adjacent land and groove tracks. In this structure, the track pitch is narrowed as the recording density increases, thus, crosstalk between adjacent tracks may occur.
In
FIG. 1B
, a single header is located at the boundary between a land track and a groove track. The single header can be used for a pair of land and groove tracks. This structure produces more advantageous signals than the structure of
FIG. 1A
since the width of a header of
FIG. 1B
is wider than the width of the header in the structure of FIG.
1
A. However, since the arrangement of headers is unbalanced, this structure is susceptible to a tracking offset (or margin).
In
FIG. 1C
, a header is located between adjacent groove and land tracks such that headers are not adjacent between the adjacent land and groove tracks. In this structure, crosstalk does not occur. However, servo control compensation cannot be achieved. Therefore, an additional servo control compensation method is required.
The structure of
FIG. 1D
is used in a DVD-RAM. Compared to the structure of
FIG. 1C
, a header is shifted by half of a track pitch. The structure of
FIG. 1D
compensates for the drawbacks of the structures of
FIGS. 1A
,
1
B and
1
C. However, since half of a header is offset from the other half of the header by one track pitch, the manufacture of this structure is more difficult compared to the other structures. For this reason, particularly in a 4.7 GB DVD-RAM having the structure of
FIG. 1D
, the signal characteristics (jitter) of first and second header fields may not be the same as those of third and fourth header fields. The content of the header field will later be described with reference to
FIGS. 4A and 4B
.
To provide mass storage capacity of HD image data, for example, 15-20 GB, a recordable area (user data area) needs to be increased by minimizing not only track pitch but also areas (overhead) other than a recording area. The size of header fields in a DVD-RAM is about 5% of the physical sectors of the DVD-RAM. To achieve high density recording, by decreasing the size of an overhead, a structure for decreasing header fields, that is, a structure in which a header field is located at the boundary between adjacent tracks as shown in
FIGS. 1B and 1D
, is necessary. However, as described above, in the structure of
FIG. 1B
, servo control compensation, including track offset, must be implemented.
FIGS. 2A through 2C
show examples of a typical track structure.
FIG. 2A
shows a concentric circle track structure.
FIG. 2B
shows a double spiral track structure.
FIG. 2C
shows a single spiral track structure used in a DVD-RAM. Reference numeral
1
indicates a groove track, reference numeral
2
indicates a land track, and reference numeral
3
indicates a header assigned to each basic recording unit (here, a sector).
Particularly in the single spiral track structure of
FIG. 2C
, a land track can be distinguished from a groove track at a land/groove track transition position
4
, at which the land track transitions to the grove track or the groove track transitions to the land track, based on a detection of the land/groove track transition position signal and according to the arrangement of a header therein.
For discs having the single spiral track structure of FIG.
2
C and the header structures of
FIGS. 1B
,
1
C and
1
D, the header structures of the discs, at a position at which groove tracks are connected to land tracks, are shown in
FIGS. 3A
,
3
B, and
3
C. It can be determined whether a sector including a header belongs to a land track or a groove track using a header signal (for example, a two-divisional signal of a photodetector) at a position at which the groove track is connected to the land track.
Accordingly, in the header structure of
FIG. 1A
, it can be determined whether a sector including a header belongs to a land track or a groove track, at a position at which the land track is connected to the groove track, from pre-pit information within the header. In the header structure of
FIG. 1B
, it can be determined whether a sector including a header belongs to a land track or a groove track, at a position at which the land track is connected to the groove track as shown in
FIG. 3A
, from pre-pit information within the header or from a header signal. In the header structure of
FIG. 1C
, it can b

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