U.S. patent application number 11/959743 was filed with the patent office on 2008-04-24 for optical disc having uniform structure.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Kyung-geun LEE, In-sik Park, Du-seop Yoon.
Application Number | 20080094993 11/959743 |
Document ID | / |
Family ID | 36102694 |
Filed Date | 2008-04-24 |
United States Patent
Application |
20080094993 |
Kind Code |
A1 |
LEE; Kyung-geun ; et
al. |
April 24, 2008 |
OPTICAL DISC HAVING UNIFORM STRUCTURE
Abstract
An optical disc is manufactured under a uniform condition by
forming grooves and lands on the entire surface of the disc. The
optical disc is configured to obtain a reliable reproduction
signal, and the grooves and lands are formed on a lead-in area, a
user data area and a lead-out area of the optical disc. Since the
same manufacturing condition can be adopted in mastering discs, the
yield can be enhanced and the manufacturing cost can be
reduced.
Inventors: |
LEE; Kyung-geun;
(Gyeonggi-do, KR) ; Park; In-sik; (Gyeonggi-do,
KR) ; Yoon; Du-seop; (Gyeonggi-do, KR) |
Correspondence
Address: |
STEIN, MCEWEN & BUI, LLP
1400 EYE STREET, NW
SUITE 300
WASHINGTON
DC
20005
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
36102694 |
Appl. No.: |
11/959743 |
Filed: |
December 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11429335 |
May 8, 2006 |
|
|
|
11959743 |
Dec 19, 2007 |
|
|
|
10998010 |
Nov 29, 2004 |
7164647 |
|
|
11429335 |
May 8, 2006 |
|
|
|
10128530 |
Apr 24, 2002 |
7065015 |
|
|
10998010 |
Nov 29, 2004 |
|
|
|
Current U.S.
Class: |
369/100 ;
369/275.3; G9B/7.035 |
Current CPC
Class: |
G11B 2020/1239 20130101;
G11B 7/00736 20130101; G11B 7/24082 20130101; G11B 7/261 20130101;
G11B 7/24038 20130101; G11B 7/0053 20130101; G11B 2020/1274
20130101; G11B 2220/235 20130101; G11B 20/1403 20130101; G11B
7/00718 20130101; G11B 7/00745 20130101; G11B 20/1426 20130101;
G11B 20/1217 20130101; G11B 27/24 20130101; G11B 2220/216 20130101;
G11B 2020/1292 20130101; G11B 27/3027 20130101; G11B 2220/2575
20130101; G11B 2220/2562 20130101 |
Class at
Publication: |
369/100 ;
369/275.3 |
International
Class: |
G11B 7/24 20060101
G11B007/24; G11B 7/00 20060101 G11B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2001 |
KR |
2001-23747 |
Sep 29, 2001 |
KR |
2001-61041 |
Claims
1. An optical storage medium comprising: a lead-in area comprising
a read-only area and a readable/recordable area; a user data area
in which user data is recorded; a first wobble formed in the read
only area of the lead-in area; and second wobble formed in the
readable/recordable area, wherein: the first wobble is modulated by
a first modulation method, the second wobble is modulated by a
second modulation method other than the first modulation method,
and a first track pitch of the readable/recordable area is
different from a second track pitch of the read-only data area.
2. An apparatus for transferring data with respect to an optical
storage medium comprising a lead-in area, which comprises a
read-only area and a readable/recordable area, and a user data area
in which user data is recorded, the apparatus comprising: an
optical pickup to emit light to transfer data with respect to the
storage medium; and a controller arranged to control the optical
pickup to record data on the storage medium, wherein: first data is
transferred with respect to a first wobble formed in the read-only
area of the lead-in area, second data is transferred with respect
to the readable/recordable area of the lead-in area in which a
second wobble is formed, the first wobble is modulated by a first
modulation method, the second wobble is modulated by a second
modulation method other than the first modulation method, and a
first track pitch of the readable/recordable area is different from
a second track pitch of the read-only data area.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/429,335, filed May 8, 2006, currently
pending, which is a continuation of U.S. patent application Ser.
No. 10/998,010, filed Nov. 29, 2004, which issued as U.S. Pat. No.
7,164,647, which is a continuation of U.S. patent application Ser.
No. 10/128,530, filed Apr. 24, 2002, which issued as U.S. Pat. No.
7,065,015, which claims the benefit of Korean Application Nos.
2001-61041, filed Sep. 29, 2001 and 2001-23747, filed May 2, 2001,
in the Korean Industrial Property Office, the disclosures of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an optical disc which can
be manufactured under uniform conditions by forming grooves and
lands on the entire surface of the disc having a lead-in area, a
user data area and a lead-out area, and which is configured to
obtain a highly reliable recording/reproduced signal.
[0004] 2. Description of the Related Art
[0005] In general, optical discs are widely employed as information
recording media for an optical pickup device which
records/reproduces information in a non-contact manner. They are
classified into compact discs (CDs) and digital versatile discs
(DVDs) according to information recording capacity. Furthermore, a
DVD disc capable of writing, erasing and reading information can be
sub-divided into a digital versatile disc-random access memory
(DVD-RAM) disc and a digital versatile disc-rewritable (DVD-RW)
disc.
[0006] FIG. 1 shows a conventional DVD-RAM or DVD-RW disc having a
lead-in area 10, a user data area 20 and a lead-out area 30. The
lead-in area 10 contains read only data, such as the disc size,
number of track layers on a readable plane or illegal copy
preventing information. The user data area 20 contains user data
that can be repeatedly read and/or written. The lead-out area 30
contains other disc-related information.
[0007] FIG. 1 further shows a partially enlarged view of the
lead-in area 10 (a portion A), the user data area 20 (a portion C)
and the lead-out area 30 (a portion B). In the lead-in area 10 and
the lead-out area 30, pits 15 are used to record read only
data.
[0008] In the user data area 20, grooves 23 and lands 25 are
alternatively formed to accommodate recording and/or reproducing
information marks 27 along a predetermined track. Here, a reference
numeral 40 denotes a reproduction beam.
[0009] A noticeable difference between a DVD-RAM and a DVD-RW is a
physical area provided for recording. In other words, the DVD-RAM
performs recording on both the lands 25 and the grooves 23, while
the DVD-RW performs recording only on the grooves 23. Application
of these two standard formats results in the following
problems.
[0010] First, while a DVD-RW having the same physical recording
structure as a DVD-ROM (read only disc) has an excellent
reproduction compatibility in DVD-ROM drives or DVD players, a
DVD-RAM having a phase difference corresponding to depths of a land
and a groove requires hardware modification to suitably track lands
and grooves. Therefore, a conventional DVD-RAM has a poor
reproduction compatibility.
[0011] Second, in the context of recording/reproduction
characteristics or injection-molding characteristics in recording
data on a groove, the grooves formed in a DVD-RW are two or more
times shallower than that in a DVD-RAM. Here, if necessary, read
only data is formed on the lead-in area 10 in a form of pits
15.
[0012] FIG. 2 shows a graph illustrating an amplitude ratio of a
reproduced signal with respect to a pit depth represented in
.lamda./n unit for a wavelength (.lamda.) of a reproduced beam to a
refractive index (n) of a disc. In cases where the lengths of a
recording mark for the minimum recording mark length T are 3T and
14T, the amplitude ratios denoted by m.sub.1 and m.sub.2 are in a
range of between 0.2 and 0.3 where the pit depth (corresponding to
a groove depth of a DVD-RW) is approximately 0.06 in .lamda./n
unit. The amplitude ratio is approximately 1 where the pit depth is
approximately 0.25. Accordingly, the signal level at the pit depth
of .lamda./12n is approximately 30% (1:0.3) as compared to the case
where the pit depth is .lamda./4n. Therefore, a reliable pit signal
cannot be obtained where read only data as shallow as a groove
depth of a DVD-RW is formed in a DVD-RAM.
[0013] Third, there is a demand for a multi-layered optical disc
having a plurality of recording layers, looking from the direction
of an incident beam, to enhance the recording capacity. FIG. 3
shows a dual recording layer disc having a first recording layer L0
and a second recording layer L1. A recording laser passes through
the first recording layer L0 where a recording is performed on the
second recording layer L1. In this case, there is a difference in
light power between a pit portion and a groove portion. Also, where
a physical header representing a basic recording unit in a data
area is used, there is a difference in light transmittance because
unlike the recording area, the physical header area always remains
crystallized.
[0014] FIG. 4 shows a graph illustrating light power for each of a
mirror portion, pit portion, groove portion and a groove portion
with marks. As shown in FIG. 4, the physical geometry of the first
recording layer L0 affects the light power.
[0015] Table 1 below lists conditions used in the light power
experiments. TABLE-US-00001 TABLE 1 Parameter Condition Wavelength
(nm) 400 Numerical aperture (NA) 0.65/0.85 Minimum mark length
(.mu.m) 0.275/0.194 Modulation EFM+ (Eight-to-Fourteen
Modulation-plus) Track pitch (.mu.m) 0.30, 0.34, 0.38 Reflectivity
(%) Rc = 25, Ra = 5
[0016] In Table 1, Rc represents the reflectivity of a crystallized
portion of a recording layer and Ra represents the reflectivity of
an amorphous portion of a recording layer. According to the
experimental results, the smallest decrease in the light power was
found in the mirror portion. The light power gradually decreased,
in order, with the physical geometry of a pit portion, a groove
portion and a groove portion with marks. FIG. 3 shows that a
recording/ reproducing beam 40 is trapped over a boundary of the
lead-in area 10 of the first recording layer L0 and the data area
20 having grooves. Accordingly, the amount of the light beam
irradiated onto the second recording layer L1 is different from the
case where a recording/reproducing beam 40 extends over only to the
grooves. Therefore, the groove portion with marks adversely affects
the recording power as the data is written on the second recording
layer L1 of the dual-layered optical disc, resulting in a poor
recording/reproduction efficiency.
[0017] Fourth, in order to reduce a spot size of a reproducing beam
to attain high-density, a numerical aperture (NA) should be
increased. However, the problem with a dual recording layer disc is
that a difference in light power becomes more serious as the NA
increases. Factors causing the difference in the light power with
increased NA are listed in Table 2 below. TABLE-US-00002 TABLE 2
Item Parameter Example Dual recording Structure of first recording
layer Grooves, pits, etc., layers High NA Number of tracks trapped
by beam 85 for NA 0.65 160 for NA 0.85 Incident angle of beam
40.5.degree. for NA 0.65 58.2.degree. for NA 0.85
[0018] As shown in Table 2, with the grooves and pits formed on the
first recording layer of a dual recording layer disc, the number of
tracks trapped by a beam and the incident beam angle increase as
the NA is increased.
[0019] Finally, the manufacturing conditions of the disc mastering
may vary depending on different structures of the disc in a lead-in
area (pits), a data area (grooves) and a lead-out area (pits). This
makes the manufacturing process complex, resulting in a poor yield
and an increased manufacturing cost.
SUMMARY OF THE INVENTION
[0020] Accordingly, it is an object of the present invention to
provide an optical disc with an improved yield, a reduced
manufacturing cost and an improved recording/reproducing capacity,
by forming grooves in both a lead-in area and a lead-out area so as
to have the same manufacturing conditions for discs during
mastering.
[0021] It is another object of the present invention to provide an
optical disc having an improved structure of multiple recording
layers such that light power is uniformly irradiated to the
multi-layered disc during recording/reproducing.
[0022] Additional objects and advantages of the invention will be
set forth in part in the description which follows, and, in part,
will be obvious from the description, or may be learned by practice
of the invention.
[0023] To achieve the above and other objects of the present
invention, there is provided an optical disc for recording and/or
reproduction, wherein grooves and lands are provided to a lead-in
area, a user data area and a lead-out area of the optical disc.
[0024] According to an aspect of the present invention wobbles are
formed on at least one side of the grooves and lands as read only
data.
[0025] According to another aspect of the present invention, the
wobbles in the lead-in area, the user data area and the lead-out
area may be modulated by the same modulation technique or by
different modulation techniques.
[0026] The wobbles may be modulated by a Quadrature Phase Shift
Keying (QPSK) technique or by a Modified Amplitude Modulation (MAM)
technique in which a wobbled portion of a single frequency having a
predetermined period and a non-wobbled portion having a
predetermined period are merged.
[0027] Alternatively, the wobbles may be modulated by a frequency
modulation technique, an amplitude modulation technique, a phase
modulation technique, a minimum shift keying (MSK) modulation
technique or a saw tooth wobble (STW) modulation technique.
[0028] On the other hand, the wobbles in the user data area may be
modulated by at least one selected from a QPSK modulation, a
frequency modulation, an amplitude modulation, a MAM modulation, a
phase modulation, a MSK modulation and a STW modulation, and the
wobbles in the lead-in area and the lead-out area are modulated by
a modulation technique different from that of the wobbles in the
user data area.
[0029] The optical disc according to the present invention
comprises at least one recording layer.
[0030] An optical disc for recording and/or reproduction according
to another embodiment of the present invention comprises a lead-in
area, a user data area and a lead-out area, wherein each have
grooves and lands formed thereon, and data in the user data area is
recorded on at least one side of the lands and grooves.
[0031] An optical disc for recording and/or reproduction according
to yet another embodiment of the present invention comprises a
lead-in area, a user data area and a lead-out area, wherein each
have grooves and lands formed thereon, and the lead-in area further
includes a read only data area and a write/read data area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] These and other objects and advantages of the present
invention will become more apparent and more readily appreciated
from the following description of the preferred embodiment, taken
in conjunction with the accompanying attached drawings in
which:
[0033] FIG. 1 is a diagram of a conventional optical disc with
enlarged views illustrating portions A, B and C;
[0034] FIG. 2 is a graph illustrating the amplitude ratio of a
reproduced signal with respect to a pit depth;
[0035] FIG. 3 is a diagram of a partial cross-sectional view
illustrating a conventional optical disc;
[0036] FIG. 4 is a graph illustrating light power with respect to a
mirror portion, a pit portion, a groove portion and a groove
portion with marks;
[0037] FIG. 5 is a diagram of an optical disc according to an
embodiment of the present invention with enlarged views
illustrating portions D, E and F;
[0038] FIG. 6 is a diagram illustrating a one-side wobbling method
adopted by an optical disc according to the present invention;
[0039] FIG. 7 is a diagram illustrating a wobble-and-land prepit
combination method adopted by an optical disc according to the
present invention;
[0040] FIG. 8A is a diagram of waveforms obtained from wobbles
based on a frequency modulation technique adopted by an optical
disc according to the present invention;
[0041] FIG. 8B is a diagram of waveforms obtained from wobbles
based on a phase modulation technique adopted by an optical disc
according to the present invention;
[0042] FIG. 8C is a diagram of waveforms obtained from wobbles
based on an amplitude modulation technique adopted by an optical
disc according to the present invention;
[0043] FIG. 8D is a diagram of waveforms obtained from wobbles
based on a Modified Amplitude Modulation (MAM) technique adopted by
an optical disc according to the present invention;
[0044] FIG. 9 is a diagram of wobbles based on a Quadrature Phase
Shift Keying (QPSK) technique adopted by an optical disc according
to the present invention;
[0045] FIGS. 10 is a diagram of waveforms obtained from wobbles
based on a Minimum Shift Keying (MSK) modulation technique adopted
by an optical disc according to the present invention;
[0046] FIG. 11 is a diagram of waveforms obtained from wobbles
based on a Surface Transverse Wave (STW) modulation technique
adopted by an optical disc according to the present invention;
[0047] FIG. 12 is a diagram illustrating wobbles with different
track pitches adopted by an optical disc according to the present
invention;
[0048] FIG. 13 is a diagram illustrating a lead-in area of an
optical disc according to yet another embodiment of the present
invention;
[0049] FIG. 14 is a diagram illustrating a header field and a read
only data field of the optical disc of FIG. 13; and
[0050] FIG. 15 is a schematic diagram illustrating an example of an
optical recording/reproducing system which records and/or
reproduces data from an optical disc of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] FIG. 5 shows an optical disc according to an embodiment of
the present invention. The optical disc includes a lead-in area
100, a user data area 120 and a lead-out area 130, and grooves 123
and lands 125 that are formed on the entire surface thereof. User
data can be recorded on only the grooves 123 or on both the grooves
123 and the lands 125. Where read only data is recorded, waveforms
of wobble signals 105 are consecutively recorded on at least one
side of the grooves 123 and lands 125, instead of pits.
[0052] An enlarged view of portions D and E shows that the grooves
123 and the lands 125 are alternately formed in the lead-in and
lead-out areas 100 and 130, and waveform wobble signals 108 are
formed on both the grooves 123 and the lands 125. A portion F shows
that the grooves 123 and the lands 125 are alternately formed in
the user data area 120, and the wobble signals 105 are formed on
both the grooves 123 and the lands 125. Recording and/or
reproduction are performed while a recording/reproduction beam 110
travels along groove and/or land tracks.
[0053] FIG. 6 shows a one-side wobbling method in which wobbles
108' are formed on at least one side of the lands 125' and grooves
123'. Alternatively, wobbles may be formed on both sides of the
grooves 123' and lands 125'.
[0054] FIG. 7 shows that an optical disc according to another
embodiment of the present invention may record read only data by a
combination of wobbles 127 and land prepits 133 formed on lands 125
at predetermined intervals. The land prepits 133 are formed on a
predetermined area during the manufacture of a disc substrate. A
pickup device provided in a recording/reproducing apparatus (not
shown) can easily move to a desired location using the information
recorded in the land prepits 133. Also, the pickup device can
identify a sector number or type, a land/groove or the like, and
perform a servo control using the information recorded in forms of
land prepits.
[0055] As described above, the optical disc of the present
invention has read only data recorded as wobble signals rather than
pits, and the physical geometry of the recording layer is the same
throughout the entire surface of the optical disc. Therefore, the
optical disc of the present invention having multiple layers has
less reduction in light power than a conventional optical disc
having multiple layers.
[0056] FIG. 8A shows an example of a wobble signal modulation
adopted by an optical disc of the present invention. Specifically,
a frequency modulation technique is used, and data is memorized by
changing frequencies of wobble signals 108 and 108'. For example,
data is recorded in combinations of bits of logic "0" or "1". Data
is recorded in such a manner that the frequencies of the wobble
signals 108 and 108' are made different in cases of the bits of
logic "0" and logic "1", respectively. For example, the frequency
of the wobble signal of the logic "0" is greater than that of the
logic "1", so as to distinguish the bits having logic values "0"
and "1".
[0057] Alternatively, FIG. 8B shows that a phase modulation
technique may be used in recording data, whereby phases of wobble
signals 108 and 108' are shifted. That is, data is recorded in such
a manner that the phases of the wobble signals in cases of bits of
logic "0" and bits of logic "1" are made different. For example, a
phase difference of 180.degree. is made between the wobble signal
of the logic "0" and the wobble signal of the logic "1".
[0058] FIG. 8C shows that wobble signals can also be modulated by
an amplitude modulation technique. That is, data is recorded in
such a manner that amplitudes of wobble signals of bits of logic
"0" and "1" are made different.
[0059] FIG. 8D shows that data may be recorded by a Modified
Amplitude Modulation (MAM) technique, in which a wobbled portion
135 of a single frequency having a predetermined period and/or a
non-wobbled portion 137 having a predetermined period, are merged.
For example, the lengths of neighboring wobbled portions or the
lengths of neighboring non-wobbled portions are made different,
thereby recording data.
[0060] In addition, FIG. 9 shows that data can be recorded by a
Quadrature Phase Shift Keying (QPSK) modulation, whereby the phases
of the respective wobble signals 140 are different from each other
at 90.degree.. Here, a reference numeral 145 denotes a recording
mark corresponding to user data. As described above, where read
only data is recorded as wobble signals, both the user data and the
read only data are stored in the groove and/or land tracks, thereby
enhancing the utilization efficiency of a recording area of a
disc.
[0061] FIG. 10 shows that data can be recorded by a Minimum Shift
Keying (MSK) modulation, whereby only the frequencies in a
predetermined period comprising consecutive wobble signals 140 are
varied.
[0062] FIG. 11 shows that a saw tooth wobble (STW) modulation may
be employed, whereby saw tooth wobbles 150 are formed. The logic
states "0" or "1" of the saw tooth wobbles 150 are determined by
the shapes of a relatively sharply sloping portion 150a and a
relatively gently sloping portion 150b.
[0063] FIG. 12 shows that a crosstalk between tracks can be reduced
by making track pitches TP1 and TP2 of wobbles different.
[0064] FIG. 13 shows a lead-in area of an optical disc according to
yet another embodiment of the present invention. That is, a read
only data area 103 and a write/read data area 105 are provided in
the lead-in area (i.e., 100 shown in FIG. 5) of the optical disc.
In the read only data area 103, data is recorded by first wobbles.
In the write/read data area 105, second wobbles are formed. The
first and second wobbles may be modulated by different modulation
techniques or indicated by different specifications. In other
words, the first wobbles are modulated by at least one selected
from a QPSK modulation, a frequency modulation, an amplitude
modulation, a phase modulation a MAM modulation, a MSK modulation
and an STW modulation, and the second wobbles are modulated by a
modulation technique different from that for the first wobbles.
[0065] FIG. 14, with reference to FIG. 13, shows an example of a
header field 101 and a read only data field 102 of the optical disc
shown in FIG. 13. That is, address information is contained in the
entire area of the grooves in the write/read area 105, and the
header field 101, indicating the address information, and the read
only data field 102 are provided in the read only data area 103.
The header field 101 may be positioned at the front or rear of an
error correction code (ECC) recording unit or at the interface of
ECC recording units. Here, the specification of wobbles in the
header field 101 may be identical with or different from that of
wobbles in the write/read data area 105 or read only data area 103.
In particular, as shown in FIG. 13, wobbles formed in the read only
data field 102 of the read only data area 103 are high-frequency
wobbles and wobbles formed in the header field 101 and the
write/read data area 105 are low-frequency wobbles. This
arrangement prevents a reproduction signal from deteriorating as
the address information contained in the header field 101 is
recorded at high frequency. Also, to reduce the crosstalk between
the tracks, track pitches from the write/read data area 105 and the
read only data area 103 may be set differently from each other. For
example, the track pitch for the read only data area 103 may be
greater than that of the write/read data area 105.
[0066] The optical disc of the present invention may further
include a predetermined area formed for a specific purpose in
addition to the lead-in area 100, the data area 120 and the
lead-out area 130. For example, the predetermined area may be a
burst cutting area (BCA) for copy protection.
[0067] FIG. 15 is a schematic diagram illustrating an example of an
optical disc recording/reproducing system which records and/or
reproduces data from an optical disc of the present invention. The
system includes a laser diode 150 which radiates light, a
collimating lens 152 which collimates the light radiated from the
laser diode 150, a polarizing beam splitter 154 which changes the
traveling path of incident light according to the polarization
direction of the incident light, a 1/4 wavelength plate 156 and an
objective lens 158 which focuses the incident light onto an optical
disc 160. The light reflected from the optical disc 160 is
reflected by the polarizing beam splitter 154 and received by a
photodetector, e.g., a quadrant photodetector 162. The light
received in the quadrant photodetector 162 is converted into an
electrical signal and output to a channel 1, in which the
electrical signal is detected as an RF signal, and to a channel 2,
in which the electrical signal is detected as a wobble signal by a
push-pull method. Here, H1, H2, H3 and H4 denote DC amplifiers, and
Ia, Ib, Ic and Id denote first through fourth current signals
output from the quadrant photodetector 162.
[0068] According to an optical disc of the present invention, read
only data can be formed by various modulation schemes described
above. In particular, wobble signals can be formed on the lead-in
area 100, the lead-out area 130 and the user data area 120 by the
same modulation technique.
[0069] On the other hand, wobbles can be formed by different
modulation techniques according to the disc area, that is, the
lead-in area 100, the user data area 120 or the lead-out area 130.
For example, at least one selected from a frequency modulation, a
phase modulation, an amplitude modulation, a MAM modulation, a QPSK
modulation, a MSK modulation and an STW modulation can be employed
in the user data area 120. Then, a modulation technique different
from that employed in the user data area 120, may be employed in
the lead-in area 100 and the lead-out area 130.
[0070] To increase the storage capacity, the present invention
provides a disc having at least one recording layer. For example, a
dual recording-layer disc of the present invention comprises
grooves and lands which are formed on the entire surface of the
dual recording-layer disc, and read only data which is formed
uniformly as wobble signals. Thus, there is no difference in the
light power at the boundary between the lead-in area or lead-out
area and the user data area. Furthermore, efficiency of a recording
area is enhanced because the read only data is recorded as wobble
signals, allowing both the user data and the read only data to be
stored in the groove and/or land tracks.
[0071] In the optical disc according to the present invention,
grooves are consecutively formed throughout the entire surface of
the disc, which eases the manufacturability and provides advantages
from the viewpoint of controllability of mastering parameters.
Also, since the same manufacturing condition can be adopted in
mastering discs, the yield can be enhanced and the manufacturing
cost can be reduced. Furthermore, the light power can be uniformly
adjusted while recording/reproducing data on/from a
multiple-layered disc, by forming read only data as wobbles rather
than pits.
[0072] Although a few embodiments of the present invention have
been shown and described, it would be appreciated by those skilled
in the art that changes may be made in this embodiment without
departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
* * * * *