U.S. patent application number 10/577926 was filed with the patent office on 2007-12-20 for wobble information recording method, information recording medium, and recording and reproduction method and apparatus thereof.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Shinya Abe, Takashi Ishida.
Application Number | 20070291628 10/577926 |
Document ID | / |
Family ID | 35052503 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070291628 |
Kind Code |
A1 |
Abe; Shinya ; et
al. |
December 20, 2007 |
Wobble Information Recording Method, Information Recording Medium,
and Recording and Reproduction Method and Apparatus Thereof
Abstract
An optical disk and a method for identifying the optical disk
are provided which make it possible to identify a recording system
of the optical disk easily in a short time by a recording and
reproduction apparatus when a groove-recording system and a
land-recording system are both employed in one kind of optical
disk, for, example, a BD-R. Specifically, the polarity upon
reproducing the wobble information is made to be the same in both
of the optical disk of groove-recording system and the optical disk
of land-recording system. The recording system of the optical disk
that shows the same wobble polarity irrespective of the recording
system can be easily detected by finding a tracking polarity that
can recognize the wobble information by changing the tracking
polarity, whereby the start-up time of the recording and
reproduction apparatus can be shortened.
Inventors: |
Abe; Shinya; (Osaka, JP)
; Ishida; Takashi; (Kyoto, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK L.L.P.
2033 K. STREET, NW
SUITE 800
WASHINGTON
DC
20006
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
Osaka
JP
571-8501
|
Family ID: |
35052503 |
Appl. No.: |
10/577926 |
Filed: |
May 10, 2005 |
PCT Filed: |
May 10, 2005 |
PCT NO: |
PCT/JP05/08838 |
371 Date: |
May 1, 2006 |
Current U.S.
Class: |
369/275.4 ;
G9B/7.025 |
Current CPC
Class: |
G11B 2007/0013 20130101;
G11B 7/0053 20130101; G11B 7/24082 20130101 |
Class at
Publication: |
369/275.4 |
International
Class: |
G11B 7/007 20060101
G11B007/007 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2004 |
JP |
2004-140652 |
Claims
1-20. (canceled)
21. A method for recording wobble information of an information
recording medium which comprises: selecting a recording system; and
forming a guide groove having wobble information wherein the wobble
starts its first wobble deviation towards the inner side of the
medium in the case where the selected recording system is a
groove-recording system, or a guide groove having wobble
information wherein the wobble starts its first wobble deviation
towards the outer side of the medium in the case where the selected
recording system is a land-recording system.
22. The method according to claim 21, wherein the information
recording medium has a plurality of recording layers, the selection
of the recording system is made for each recording layer, and the
guide groove having wobble information is formed for each recording
layer based on the selected recording system.
23. An information recording medium of groove-recording system,
wherein a wobble starts its first wobble deviation towards the
inner side of the medium in a guide groove having wobble
information.
24. (canceled)
25. An information recording medium of land-recording system,
wherein a wobble starts its first wobble deviation towards the
outer side of the medium in a guide groove having wobble
information.
26-39. (canceled)
40. An apparatus for recording information on the information
recording medium according to claim 23, which records information
on groove portions when a tracking polarity is set for the groove
recording system and wobble information is detected.
41. An apparatus for reproducing information from the information
recording medium according to claim 23, which reproduces the
information from the groove portions when a tracking polarity is
set for the groove recording system and wobble information is
detected.
42. An apparatus for recording information on the information
recording medium according to claim 25, which records information
on land portions when a tracking polarity is set for the land
recording system and wobble information is detected.
43. An apparatus for reproducing information from the information
recording medium according to claim 25, which reproduces the
information from the land portions when a tracking polarity is set
for the land recording system and wobble information is detected.
Description
TECHNICAL FIELD
[0001] The present invention is related to a method for recording
wobble information of an information recording medium such as an
optical disk so that a polarity of detected wobble information is
the same irrespective of recording system, and an information
recording medium wherein the wobble information is recorded
according to the method. Further, the present invention is related
to a method and apparatus for recording and reproducing information
using the information recording medium.
BACKGROUND OF THE INVENTION
[0002] Conventionally, CD-R/RW or DVD-R/RW/RAM have been used as a
write-once or an rewritable optical disk and recently demand for a
DVD-R/RW/RAM has been increased since a DVD recorder has widely
prevailed for recording TV broadcasts. A guide groove is provided
in these optical disks and reference signals for synchronizing a
linear velocity upon recording and reproducing and optional address
information signals are recorded in these optical disks by "wobble"
signals which are a meander of the guide groove. A recording and
reproduction apparatus for such an optical disk records and
reproduces information by detecting the wobble signals to adjust
the linear velocity and detecting the address if the address
information is added to the optical disk. Of the above optical
disks, the DVD-RAM employs a recording system (or a recording mode)
which may be called as "land & groove" recording system
according to which recording and reproduction of information are
carried out on both of land portions (that are faces far from a
light used for recording and reproduction) and the groove portions
(that are faces near to the light) of the guide groove, and all the
other optical disks employ a groove recording system according to
which the recording and reproduction of information are carried out
only on the groove portions (that are faces near to the light used
for recording and reproduction) of the guide groove.
[0003] Recently, an optical disk whose recording density is higher
than the DVD has been developed. In general, information is
recorded on and reproduced from the optical disk by an incident
light for recording and reproduction which light passes through a
transparent layer which may be called as a "substrate." The
thickness of the substrate through which the light for recording
and reproduction passes is 0.6 mm for the DVD. The study has been
made for further thinning the thickness of the substrate into about
0.1 mm and thereby using a light with a short wavelength for
recording and reproduction. As a result, a recordable Blu-ray Disc
(BD) has been developed.
[0004] In the case where the thickness of the substrate is thin
such as 0.1 mm, it is difficult to form the guide groove in the
sheet having a thickness of 0.1 mm and to form the recording layer
on its surface. For this reason, an approach for producing the
Blu-ray Disc is made wherein the guide groove is formed in a
substrate of a 1.1 mm thickness which is to be positioned at the
side (rear side) that is not irradiated with the light for
recording and reproducing and the recording layer is formed on the
guide groove followed by forming a cover layer of a 0.1 mm
thickness. In this case, the light for recording and reproducing is
applied from the side of the cover layer.
[0005] When the recording layer is formed by sputtering a material
for recording layer onto the surface of the rear-side substrate,
the recording layer can be deposited and formed so that the
thickness of the recording layer in the groove portions (the top
surface of the guide groove) is almost the same as that in the land
portions (the bottom surface of the guide groove) viewed from the
cover layer side where the light for recording and reproducing is
applied. Therefore, in this case, the portions that present a
better recording and reproduction characteristics, which is
generally the groove portions, can be used for recording and
reproduction.
[0006] Further, there is a method for applying an organic dye by a
spin-coat method as a method for forming the recording layer. For
example, Japanese Patent Kokai (Laid-Open) Publication No.
2003-109246(A) describes a method for producing a write-once
optical disk which includes forming the recording layer by applying
the organic dye on the rear-side substrate by the spin-coat method
and then forming the cover layer. However, according to the spin
coat method, the organic dye preferentially deposits in the groove
portions (concaved portions) of the substrate. As a result, the
recording layer is formed thickly in the land portions when viewed
from the cover layer side. Therefore, since the recording film is
easily formed in the land portions in this case, it is preferable
that the land portions are used for recording and reproduction.
SUMMARY OF THE INVENTION
[0007] As described above, an appropriate recording system depends
on the method for forming the recording film. However, when
tracking is conducted by, for example, a push-pull method, tracking
characteristics obtained when using the groove portions as the
recording layer is reversal of those when using the land portion as
the recording layer. Similarly, a polarity of wobble signals
obtained in reproduced signals when reproducing the signals
recorded in the groove portions is reversal of a polarity of wobble
signals obtained in reproduced signals when reproducing the signals
recorded in the land portions.
[0008] In a recording and reproduction apparatus, a circuit for
tracking is generally separated from a circuit for detecting wobble
signals. For this reason, when it is desired that a single
recording and reproduction apparatus accepts two types of optical
disks, one being of the groove recording system, and the other
being of the land-recording system, it is necessary to detect
whether the portions to be used for recording is the groove
portions or the land portions and to detect the wobble signal
polarity for a loaded optical disk, which results in a problem that
a longer time is required for start-up.
[0009] In order to resolve this problem, the present inventors
propose that the polarity obtained upon reproducing the wobble
signals is made the same in both of the information recording
medium of land-recording system and the information recording
medium of groove-recording system. Specifically, the polarity of
wobble signals formed in the optical recording medium which employs
one recording system is made mirror reverse of that formed in the
optical recording medium which employs the other recording system.
More specifically, the physical direction of the wobble
(specifically, right and left of starting direction of the wobble,
that is, whether the wobble starts its first wobble deviation
towards the inner side or the outer side of the medium) in the case
of the groove-recording system is reversed in the wobble in the
case of the land-recording system so that the polarity of the
wobble signals in the case of the land-recording system is made to
be the same as the polarity of the wobble signals in the case of
the groove-recording system. Herein, the phrase "the wobble starts
its first wobble deviation towards the inner side of a medium"
means that a starting point of the wobble is positioned at the
innermost of the medium (a position nearer to the center in the
case of a disk) relative to a position where a wobble amplitude is
zero and the wobble starts from the starting point as shown in FIG.
6. The phrase "the wobble starts its first wobble deviation towards
the outer side of a medium" means that a starting point of the
wobble is positioned at the outermost of the medium relative to a
position where the wobble amplitude is zero and the wobble starts
from the starting point as shown in FIG. 7. Both of the wobbles
shown in FIGS. 6 and 7 are monotone wobbles. Timing and address
information by MSK (Minimum Shift Keying) modulation and HMW
(Harmonic Modulated Wave) modulation are optionally incorporated
into the monotone wobble.
[0010] Thus, the present invention provides a method for recording
wobble information of an information recording medium which
includes:
[0011] selecting a recording system; and
[0012] forming a guide groove having wobble information wherein the
wobble starts its first wobble deviation towards the inner side of
the medium in the case where the selected recording system is a
groove-recording system, or a guide groove having wobble
information wherein the wobble starts its first wobble deviation
towards the outer side of the medium in the case where the selected
recording system is a land-recording system. This is particularly
applicable to an optical disk on and from which information is
recorded and reproduced with a light. This method makes it possible
that the polarity of the wobble signals of the information
recording medium of the groove-recording system is the same as that
of the information recording medium of the land-recording system.
According to this method, an information recording medium of
groove-recording system, wherein a wobble starts its first wobble
deviation towards the inner side of the medium in a guide groove
having wobble information, and an information recording medium of
land-recording system, wherein a wobble starts its first wobble
deviation towards the outer side of the medium in a guide groove
having wobble information can be obtained.
[0013] Further, the present invention provides a method for
recording wobble information of a multi-layer information recording
medium having a plurality of recording layers, which includes
making the wobble polarity that is detected from all the recording
layers to be the same, and a multi-layer information recording
medium having a plurality of recording layers wherein wobble
information is recorded according to this method. In such an
information recording medium, the wobble starts its first wobble
deviation towards the inner side or the outer side of the medium in
a guide groove having wobble information for each recording layer
depending on a recording system of the each recording layer.
Herein, the terms "a guide groove for a certain recording layer"
means a groove for guiding a light used for recording information
on the certain recording layer and reproducing the information from
the certain recording layer.
[0014] Furthermore, the present invention provides a method for
recording information on and reproducing information from an
information recording medium of the present invention, which
includes judging a tracking polarity peculiar to a loaded
information recording medium (particularly, an optical disk), based
on the result whether or not wobble information is detected from
wobble signals under a fixed tracking polarity. Further, the
present invention provides a recording and reproduction apparatus
which is used for carrying out this method.
[0015] In these recording and reproduction method and apparatus,
the default of the tracking polarity may be preferably one for a
groove-recording system. Since many optical disks conventionally
employ the groove-recording system, it may be considered that many
unspecified optical disks also employ the groove-recording system.
For this reason, the default of the tracking polarity is one for
the groove-recording system and a detection time required for
detecting an optical disk of the groove-recording system can be
shorten, whereby the start time when the unspecified optical disk
is loaded can be shortened.
[0016] This invention makes it possible to omit the time required
for a recording and reproduction apparatus to study the wobble
polarity of each optical disk irrespective whether its recording
system is the groove-recording system or the land recording system.
Further, the recording system of the information recording medium
of the present invention can be easily judged by detecting whether
or not the wobble information is obtained from the wobble signals
when tracking is carried out under a predetermined polarity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic view of an optical disk according to a
first embodiment of the present invention;
[0018] FIG. 2 is a schematic view of a laser master recording
apparatus for producing a master of the optical disk according to
the first embodiment of the present invention;
[0019] FIG. 3 is a block diagram of a signal reproduction circuit
of the optical disk according to the first embodiment of the
present invention;
[0020] FIG. 4 is a schematic view describing a groove polarity and
a tracking signal-polarity of the optical disk according to the
first embodiment of the present invention;
[0021] FIG. 5 is a schematic view of an optical disk according to a
second embodiment of the present invention;
[0022] FIG. 6 is a schematic view showing an example of wobble of a
guide groove formed in an information recording medium of
groove-recording system, according to a method of the present
invention; and
[0023] FIG. 7 is a schematic view showing an example of wobble of a
guide groove formed in an information recording medium of
land-recording system, according to a method of the present
invention.
[0024] Here, in FIGS. 1 to 7, the reference numbers represent the
following elements:
[0025] 101 . . . substrate, 102 . . . recording film, 103 . . .
overcoat, 104 . . . UV curable resin layer, 105 . . . PC sheet, 201
. . . laser, 202 . . . light regulator, 203 . . . deflector, 204 .
. . beam expander, 205 . . . movable optical bench, 206 . . .
master, 207, 208 . . . mirror, 209 . . . formatter, 210 . . .
objective lens, 301 . . . optical disk, 302 . . . objective lens,
303 . . . mirror, 304 . . . photodetector, 305, 306 . . .
preamplifiers, 307 . . . differential amplifier, 308 . . . tracking
circuit, 309 . . . wobble detecting circuit, 501 . . . substrate,
502 . . . second recording film, 503 . . . intermediate layer, 504
. . . first recording film, 505 . . . VU curable resin layer, 506 .
. . PC sheet.
Detailed Description of the Preferred Embodiments
[0026] The embodiments of the present invention are described with
reference to the attached drawings.
First Embodiment
[0027] FIG. 1 shows a schematic view showing a construction of an
optical disk according to the first embodiment of the present
invention. The optical disk includes a substrate 101, a recording
film 102 formed on a surface of the substrate 101, an overcoat
layer 103 formed on a surface of the recording film 102 and a sheet
105 bonded to the overcoat layer 103 through an adhesive layer 104.
The substrate 101 is a substrate (or plate) which is formed by
injection molding and has a guide groove wherein wobble information
is recorded on its surface where the recording film 102 is formed.
The substrate 101 has a thickness of about 1.1 mm. The recording
film 102 may be formed by, for example, a spin coat method using an
organic dye. The overcoat layer 103 may be formed of a UV curable
resin into a thickness of about 4 .mu.m. The sheet 105 may be a
polycarbonate sheet (PC sheet) having a thickness of about 80
.mu.m, and it may be bonded to the overcoat layer 103 by the
adhesive layer 104 of a UV curable layer.
[0028] A stamper gives the guide groove on the substrate upon the
injection molding. That is, the stamper corresponds to a mold of
the guide groove. The stamper may be produced using a master that
is produced using a laser master recording apparatus.
[0029] FIG. 2 is a schematic view showing a construction of the
laser master recording apparatus. A light emitted from a light
source that is a laser 201 (whose wavelength is 248 nm) is
reflected on a mirror 207 and its intensity is adjusted in a light
regulator 202. The light is further reflected on a mirror 208 and
deflected by a deflector 203. At this moment, wobble information to
be recorded is generated in a formatter 209 and introduced in the
deflector 203. The diameter of the light deflected by the deflector
is adjusted in a beam expander 204, focused by an objective lens
210 that is mounted in a movable optical bench 205, and applied to
a master 206. A photoresist has been applied to the surface of the
master 206 which is irradiated with the light. The master 206 is
rotated on a spindle.
[0030] By changing the output polarity of the formatter 209, it is
possible to change the physical direction of the wobble recorded in
the master 206, that is, the direction of the first wobble
deviation (that is, whether the wobble starts its first wobble
deviation towards the inner side or the outer side of the disk).
Therefore, the method for recording wobble information of the
present invention can be carried out by determining the recording
system of the optical disk to be produced, selecting the output
polarity of the formatter based on the determination, and producing
the master by means of this master recording apparatus, and
producing the stamper from this master, and forming the guide
groove in the surface of the substrate using this stamper.
[0031] In addition to reference frequency information which are
used in order that a recording and reproduction apparatus
synchronizes a linear velocity, address information may be added to
the wobble information by mixing signals (STW; Saw Tooth Wobbles)
that are added while advancing or delaying the phase of a wave
having double frequency relative to the reference frequency and
signals having 1.5 times frequency of the reference frequency (MSK;
Minimum Shift Keying).
[0032] In general, a Blu-ray Disc employs the groove-recording
system. In that case, the wobble starts its first wobble towards
the inner side of the medium, that is, the wobble starts at the
inner side of the medium. In other words, the wobble starts at a
point where the wobble amount (or an amplitude) is maximum on the
inner side of the medium. Such a wobble is as shown in FIG. 6. As
shown in FIG. 6, in the case of the groove-recording system, the
starting point of the wobble is situated at the inner side of the
medium.
[0033] In the first embodiment, the output characteristic of the
formatter 209 is set so that the wobble starts its first wobble
deviation towards the outer side of the disk, that is, the wobble
starts at the outer side of the disk, considering that this disk
employs the land-recording system. In other words, the output
characteristic of the formatter 209 is set so that the wobble
starts at a point where the wobble amount is maximum on the outer
side of the disk. The wobble employed in the optical disk of
land-recording system is as shown in FIG. 7, and the start point of
the wobble is situated at the outer side of the disk.
[0034] FIG. 3 shows a block diagram for detecting tracking signals
and wobble signals in a recording and reproduction apparatus at the
time of recording information on and reproducing information from a
fabricated optical disk. As shown in FIG. 3, a light reflected on
an optical disk 301 is focused by an objective lens 302 and
reflected on a mirror 303 and then introduced in a bisected
photodetector 304. The section (or dividing) line is disposed
perpendicular to movement of a radial direction of the optical
disk.
[0035] Outputs of channels of the photodetector 304 are amplified
by preamplifiers 305 and 306 respectively, become a differential
signal in a differential amplifier 307, and the differential signal
is input into a tracking circuit 308 and an address detecting
circuit 309.
[0036] FIG. 4 shows the relationship between push-pull tracking
error signals corresponding to the groove portions (G) and the land
portions (L) when a spot of the light used for recording and
reproduction traverses the guide groove. As shown in FIG. 4, the
tracking error signals change as a substantially sinusoidal
waveform depending the period of the guide groove. Although the
error signals become zero at the center of the groove portion and
at the center of the land portion, the inclination at the groove
center is opposite to the inclination at the land center. The
reproduced wobble signals are generated by sifting the groove or
the land purposefully and its polarity is the same as that of the
tracking error signals.
[0037] Therefore, in the case where a conventional master for an
optical disk of land-recording system is used to produce an optical
disk by, for example, a mothering method so that a predetermined
information is recorded in land portions and the optical disk is
used as one of land-recording system, the polarity of the
reproduced wobble signals is reversed. In the first embodiment, the
wobble recording polarity is opposite to that employed in a medium
of groove-recording system. For this reason, even if the tracking
polarity is adapted to the land portion, the wobble signals whose
polarity is opposite to the tracking polarity are obtained. As a
result, the polarity of reproduced wobble signals from the optical
disk of the first embodiment becomes identical with the polarity of
those from the optical disk of groove-recording system.
[0038] In lieu of the present invention, it might be considered
that a method for reversing both of the wobble-signal polarity and
the tracking-signal polarity for groove-recording system by means
of a common amplifier in a recording and reproduction apparatus
when recording information on and reproducing information from the
optical disk of land-recording system. This method does not require
that the wobble shape for the land-recording system is reversal of
the wobble shape for the groove-recording system. However, the
frequency band of the wobble signals is significantly different
from that of the tracking error signals (the former is several kHz
and the latter is several tens kHz), a mechanism wherein the wobble
signal and the tracking error signal are separately managed using
respective circuits designed specifically for respective signals
has an advantage that the property of the recording and
reproduction apparatus is maintained more easily compared to a
mechanism which reverse the polarities using the common amplifier.
In the following, a method and an apparatus for recording
information in and reproducing information from an optical disk
wherein the wobble information is recorded according to the method
of the present invention.
[0039] The optical disk recording and reproduction apparatus of the
present invention is used with its tracking polarity set for a
groove-recording system and a land-recording system, preferably for
the groove-recording system. When a conventional optical disk of
groove-recording system is loaded in the recording and reproduction
apparatus wherein the tracking polarity is set for the
groove-recording system and tracking is carried out with an
appropriate mechanism, wobble information is detected from wobble
signals. The detected information during this tracking may be
preferably address information included in the wobble information
or another characteristic information from which a location on the
disk can be identified. In the case of an optical disk of CLV
(Constant Linear Velocity), the reference frequency signal may be
detected as the wobble information. When the wobble information is
detected by setting the tracking polarity for the groove-recording
system, the loaded optical disk is identified as one of
groove-recording system. When the wobble information is not
detected, the tracking polarity is switched and the detection of
wobble information is carried out again. After switching, when the
wobble information is detected, the loaded optical disk can be
identified as one of land-recording system.
[0040] The optical disk of the first embodiment can be identified
as one being of land-recording system according to the latter
procedure.
[0041] As described above, the number of combinations of the
tracking polarity and the wobble polarity is reduced by always
detecting a wobble polarity of an optical disk under the same
polarity in a recording and reproduction apparatus, whereby a
start-up time is reduced upon loading the optical disk.
Second Embodiment
[0042] FIG. 5 is a schematic view showing a construction of an
optical disk of a second embodiment. This disk has two recording
films. A second recording film 502 which is located further from a
laser light may be formed on a substrate 501 using an organic dye
by a spin-coat method. The substrate 501 is produced in the same
manner as in the first embodiment. Next, an intermediate layer 503
having a guide groove on its surface is stacked. The guide groove
formed in the intermediate layer 503 is used to record information
on and reproduce information from a first recording film 504 that
is located near to the laser light and it also may be formed using
a stamper which is produced with a master. The first recording film
504 whose main component may be a Te oxide film may be formed on a
surface of the intermediate layer 503 by a sputtering method. A
polycarbonate sheet (PC sheet) 506 having a thickness of about 65
.mu.m is bonded to the surface of the second recording film 504
through a UV curable resin layer 505. A method for stacking the
intermediate layer 503 is described in Japanese Patent Kokai
(Laid-Open) Publication No. 2003-203402(A) that is incorporated
herein by reference.
[0043] In this optical disk, the recording system of the second
recording film 502 is land-recording system, and the recording
system of the first recording film 504 is groove-recording system.
Therefore, the wobble guide groove is formed so that the wobbles
starts its first wobble deviation towards the outer side of the
disk, that is, the wobble starts at the outer side of the disk, in
the substrate 501 where the second recording film 502 is formed,
while the wobble guide groove is formed so that the wobble starts
its first wobble deviation towards the inner side of the medium,
that is, the wobble starts at the inner side of the medium in the
intermediate layer 503 for the first recording film 504. Each
wobble guide groove for each recording layer is also formed by
producing a master that determines the shape of the guide groove
with a laser master recording apparatus so as to record wobble
information in a predetermined manner, and forming the substrate
501 or the intermediate layer 503 by means of a stamper that is
formed by the master.
[0044] This construction enables a two-layer optical disk to be
obtained, wherein the tracking polarities of both recording layers
are different from each other, while the detecting polarity of the
wobbles of both recording layers are the same.
[0045] Also for this optical disk, the tracking polarity of each
recording layer can be easily identified according to the procedure
for distinguishing an optical disk of groove-recording system from
an optical disk of land-recording system with use of a recording
and reproduction apparatus as mentioned above, in a manner as
described in connection with the first embodiment. Therefore, the
start-up time is shortened by using this optical disk and a
recording and reproduction apparatus which is provided with a
mechanism for tracking each recording layer.
[0046] As the second embodiment, the two-layer optical disk is
described which has two recording layers whose recording systems
are different from each other. Of course, a similar construction
may be applied to an optical disk wherein the recording systems of
the first and the second recording layers are the same. For
example, in the case where the recording systems of the first and
the second recording layers are both groove-recording system, the
guide grooves are formed in the substrate and the intermediate
layer so that wobbles start their first wobble deviation towards
the inner side of the medium. Further, a similar construction is
applicable to a multi-layer optical disk having more than two
recording layers (for example, an optical disk having four
recording layers). The optical disk having four recording layers
has a combination wherein land portions or groove portions are used
for recording in each of the four recording layers. The combination
may be, for example, a construction wherein
groove-groove-groove-groove-recording systems are employed in the
respective layers in this order from the side near to a laser
light, or a construction wherein
groove-groove-groove-land-recording systems are employed in the
respective layers in this order from the side near to a laser
light.
[0047] In the first embodiment and the second embodiment, the
physical polarity of the wobble is reversed on the optical disk.
Alternatively, the polarity of the reproduced wobble signals can be
reversed by changing a depth of the guide groove. To this end, the
depth of the guide groove or the refractive index of a material for
the recording layer may be adjusted so that difference between the
optical path length of a light reflected on a groove portion and
the optical path length of a light reflected on a land portion is
not less than .lamda./2 and not greater than .lamda. (.lamda.: a
wavelength of a light used for recording and reproduction).
[0048] As described above, by recording wobble information
according to the present invention, there is an advantage that
detection of the recording system of an optical disk (that is,
detecting whether the optical disk employs a groove-recording
system or a land-recording system) can be easily made, and
therefore the start-up time can be shortened upon loading the
optical disk into the recording and reproduction apparatus. The
present invention can be applied to various recordable disks, such
as a BD-R, a BD-RE, a DVD-R, and a DVD-RW. The present invention
may be preferably applicable to the BD-R on and from which
information is recorded and reproduced with a laser beam having a
wavelength in a blue-violet region (specifically, about 405
nm).
[0049] The method for recording wobble information of the present
invention is characterized in that the polarity of wobble
information is made to be the same irrespective of the recording
system (a groove-recording system or a land-recording system) of an
information recording medium. Therefore, the present invention is
advantageously applied particularly to an information recording
medium as to which both recording systems are allowed (that is,
coexisting) according to a specification (or a standard).
[0050] Further, the method and apparatus for recording and
reproducing information of the present invention using the optical
disk of the present invention employs a specific procedure and
thereby makes it possible to reduce the load on the recording and
reproduction apparatus which load is added until the apparatus
identifies the recording system of the information recording
medium. As a result, the recording and reproduction method and
apparatus wherein the time required for start-up is reduced can be
realized.
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