U.S. patent application number 13/443486 was filed with the patent office on 2012-08-02 for optical disc, information recording method, and information reproducing method.
Invention is credited to Hideo Ando, Naoki Morishita, Seiji Morita, Naomasa Nakamura, Yasuaki Ootera, Koji Takazawa, Kazuyo UMEZAWA.
Application Number | 20120195179 13/443486 |
Document ID | / |
Family ID | 38442597 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120195179 |
Kind Code |
A1 |
UMEZAWA; Kazuyo ; et
al. |
August 2, 2012 |
OPTICAL DISC, INFORMATION RECORDING METHOD, AND INFORMATION
REPRODUCING METHOD
Abstract
According to one embodiment, a re-recordable write-once optical
disc by which recording/reproducing can be properly done with a
short-wavelength blue laser is provided. The disc has recording
layers on which marks are recorded by the laser power of a
modulated short wavelength, with a space formed between the
recorded marks. The recording layer of the disc uses an organic dye
material by which no physical modification or no physical change
substantially occurs in an area of the recorded marks.
Inventors: |
UMEZAWA; Kazuyo; (Yokohama,
JP) ; Morita; Seiji; (Yokohama, JP) ;
Takazawa; Koji; (Tokyo, JP) ; Ando; Hideo;
(Hino, JP) ; Ootera; Yasuaki; (Yokohama, JP)
; Nakamura; Naomasa; (Yokohama, JP) ; Morishita;
Naoki; (Yokohama, JP) |
Family ID: |
38442597 |
Appl. No.: |
13/443486 |
Filed: |
April 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11752705 |
May 23, 2007 |
8179763 |
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13443486 |
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Current U.S.
Class: |
369/59.11 |
Current CPC
Class: |
G11B 7/246 20130101;
G11B 2007/0006 20130101; G11B 7/249 20130101; G11B 7/2495 20130101;
G11B 7/2467 20130101; G11B 7/00456 20130101 |
Class at
Publication: |
369/59.11 |
International
Class: |
G11B 7/0045 20060101
G11B007/0045 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2006 |
JP |
2006-151584 |
Claims
1. (canceled)
2. An information medium comprising: first and second recording
layers configured to record or reproduce information by light with
a predetermined wavelength, wherein the first or second layer
comprises a metal complex.
3. An information recording method using an information medium
comprising first and second recording layers configured to record
or reproduce information by light with a predetermined wavelength,
the first or second layer comprising a metal complex, the
information recording method comprising: recording the information
on the first or second recording layer using the light.
4. An information reproducing method using an information medium
comprising first and second recording layers configured to record
or reproduce information by light with a predetermined wavelength,
the first or second layer comprising a metal complex, the
information reproducing method comprising: reproducing the
information from the first or second recording layer using the
light.
5. An information recording apparatus using the information medium
as defined in claim 2, the information recording apparatus
comprising: a module configured to record the information on the
first or second recording layer using the light.
6. An information reproducing apparatus using the information
medium as defined in claim 2, the information reproducing apparatus
comprising: a module configured to reproduce the information from
the first or second recording layer using the light.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/752,705, filed May 23, 2007, and is based upon and claims
the benefit of priority from Japanese Patent Application No.
2006-151584, filed May 31, 2006, the entire contents of each of
which are incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] One embodiment of the invention relates to an information
recording medium such as a re-recordable write-once optical disc on
which information can be recorded and from which information can be
reproduced.
[0004] 2. Description of the Related Art
[0005] As an optical disc, in general, there are a read-only ROM
disc, a recordable or re-recordable R disc, and a rewritable RW or
RAM disc. As information becomes bulky, further-large capacity is
demanded for an optical disc. For the purpose of increasing the
capacity of an optical disc, some technique has been proposed in
which a recording capacity is increased by narrowing down a beam
spot, for example, in such a manner that a wavelength of a laser
beam is shortened, or a numerical aperture NA is enlarged (for
example, refer to Jpn. Pat. Appln. KOKAI Publication No.
2004-206849, paragraphs 0036 to 0041, FIG. 1).
[0006] As multi-layered optical discs, dual-layer ROM discs are
conventionally available in the market. Recently, dual-layer
recordable discs (DVD-R:DL) each using a laser of 650 nm wavelength
are reduced to practice. In a manner of recording and reproducing
an optical disc (such as a DVD-R) using an organic dye material for
the recording layer, recording marks in which the reflectivity of
the dye has been changed are formed by modulating the power of a
laser light. Thus, the information recording is performed utilizing
the difference between the reflectivity of recording marks and that
of unrecorded portions. As a manner of modulating the laser power,
multi-pulses are used for DVD-R, for example (cf. Jpn. Pat. Appln.
KOKAI Publication No. 9-282660).
[0007] For a dye allowing the blue-laser recording with a
wavelength of about 405 nm, there are two kinds: one is a dye whose
maximum absorption wavelength is shorter than the laser wavelength
of 405 nm, and the other is a dye whose maximum absorption
wavelength is longer than 405 nm. When the dye whose maximum
absorption wavelength is longer than 405 nm is used, a so-called "L
to H" disc is obtained in which a low reflectivity of a unrecorded
state will change to a high reflectivity of a recorded state.
[0008] In a single-recording-layer recordable optical disc of the
"L to H" type, good characteristics can be obtained. However, when
characteristics of a single-sided dual-recording-layer recordable
optical disc are investigated or examined, it is found that the
characteristics are very poor. In particular, the poor
characteristics are prominent at the recording layer (L0 layer)
close to the laser reception face.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] A general architecture that implements the various features
of the invention will now be described with reference to the
drawings. The drawings and the associated descriptions are provided
to illustrate embodiments of the invention and not to limit the
scope of the invention.
[0010] FIG. 1 is an exemplary view illustrating a configuration of
a multi-layered optical disc according to an embodiment of the
invention;
[0011] FIG. 2 is an exemplary view showing a metal complex portion
of an organic material for a recording layer;
[0012] FIG. 3 is an exemplary view showing an organic dye recording
material;
[0013] FIG. 4 is an exemplary view showing another organic dye
recording material;
[0014] FIG. 5 is an exemplary view illustrating an example of
optical absorption spectrum characteristics of an organic dye
recording material for use in a current DVD-R disc;
[0015] FIGS. 6A and 6B are exemplary views each showing comparison
of shapes of recording films formed in a pre-pit area or a
pre-groove area 10 in the phase shift recording film and the
organic dye recording film;
[0016] FIGS. 7A and 7B are exemplary views each showing a specific
plastic deformation state of a transparent substrate 2-2 at a
position of a recording mark 9 in a write-once type information
storage medium using a conventional organic dye material;
[0017] FIG. 8 is an exemplary view showing light absorption
spectrum characteristics in an unrecorded state of the "L-H"
recording film;
[0018] FIG. 9 is an exemplary view showing a change of light
absorption spectrum characteristics in a recorded state and an
unrecorded state of the "L-H" recording film;
[0019] FIG. 10 is an exemplary view showing a data recording method
for rewritable data recorded on a rewritable information storage
medium;
[0020] FIG. 11 is an exemplary view for explaining a data random
shift of rewritable data recorded on a rewritable information
storage medium;
[0021] FIG. 12 is an exemplary view for explaining a recording
method of additional recording onto a recordable information
storage medium;
[0022] FIG. 13 is an exemplary view showing an optical reflectance
range of each of a High-to-Low ("H-L") recording film and a
Low-to-High ("L-H") recording film;
[0023] FIG. 14 is an exemplary view showing a detailed structure of
an ECC block after PO interleaving;
[0024] FIG. 15 is an exemplary view showing a data structure of
recording management data RMD;
[0025] FIG. 16 is an exemplary view for explaining the structure of
the border area in a recordable information storage medium;
[0026] FIG. 17 is an exemplary diagram illustrating a comparison
between the embodiment and a current DVD-R;
[0027] FIG. 18 is an exemplary flowchart for explaining the
processing procedure immediately after an information storage
medium is installed in an information reproducing apparatus or an
information recording and reproducing apparatus;
[0028] FIG. 19 is an exemplary flowchart for explaining a method of
recording additional information onto a recordable information
storage medium in an information recording and reproducing
apparatus;
[0029] FIG. 20 is an exemplary diagram for explaining the concept
of a method of setting an extendable recording location management
zone RMZ;
[0030] FIG. 21 is an exemplary view showing details of FIG. 20;
[0031] FIG. 22 is an exemplary view showing a relation between the
error rate SbER and the amount of change in the volume of a mark
(or a change in the surface condition between the mark and its
periphery) recorded on an optical disc according to one embodiment
of the invention;
[0032] FIG. 23 is an exemplary view showing a relation between the
error rate SbER and the amount of change in the level of a
reproduction signal derived from the space between marks recorded
on an optical disc according to one embodiment of the
invention;
[0033] FIG. 24 is an exemplary flowchart for explaining a recording
method using an optical disc according to one embodiment of the
invention;
[0034] FIG. 25 is an exemplary flowchart for explaining a
reproducing method using an optical disc according to one
embodiment of the invention;
[0035] FIG. 26 is an exemplary view showing a physical sector
layout of the optical disc shown in FIG. 1;
[0036] FIG. 27 is an exemplary view showing a configuration of the
lead-in area of the optical disc shown in FIG. 1;
[0037] FIG. 28 is an exemplary view showing a configuration of the
control data zone shown in FIG. 27;
[0038] FIG. 29 is an exemplary view showing a structure of one of
the data segments shown in FIG. 28;
[0039] FIG. 30 is an exemplary view showing contents of the
physical format information shown in FIG. 29;
[0040] FIG. 31 is an exemplary view showing a data area allocation
of the physical format information shown in FIG. 30;
[0041] FIG. 32 is an exemplary view showing a part (regarding L0)
of the physical format information shown in FIG. 29;
[0042] FIG. 33 is an exemplary view showing another part (regarding
L1) of the physical format information shown in FIG. 29; and
[0043] FIG. 34 is an exemplary view showing a waveform (Write
Strategy) of a recording pulse.
DETAILED DESCRIPTION
[0044] Various embodiments according to the invention will be
described hereinafter with reference to the accompanying
drawings.
[0045] One of tasks of the embodiments is to provide an information
recording medium (such as a recordable optical disc) using an
organic dye material which allows excellent recording/reproducing
performance for both single- and multi-recording layers,
particularly wherein the recording is done with a wavelength
shorter than 620 nm.
[0046] An optical disc according to the embodiment comprises one or
more recording layers (L0, L1, etc.) on which a plurality of marks
are recorded with a space between the marks, using a modulated
laser power. The recording layer uses an organic dye material (cf.
FIGS. 2-4, etc.) by which no physical modification or no physical
change (change in the volume or in the sectional area)
substantially occurs in an area of the recorded marks (practically,
the rate of modification or change is equal to or less than 10%,
for example).
[0047] According to the embodiment, good recording and reproducing
performance can be obtained for both single- and multi-layer type
recordable optical discs.
[0048] Various investigations have been made to solve the above
task. The result is that the characteristic of a dual-layer disc is
wrong if using a dye with which some mark distortions are observed
from the electrical signal obtained when recording/reproducing are
done for a single-layer disc. However, the characteristic of the
dual-layer disc is also good if using another dye with which almost
no mark distortions are observed.
[0049] The reason of degrading the characteristic of a dual-layer
disc with a dye causing mark distortions may be as follows. Namely,
in the dual-layer structure, reflection or reflective film 106 of
the L0 layer has to be a semi-transparent reflection or reflective
film, resulting in disturbing sufficient heat-sinking, to thereby
further enlarging the distortions.
[0050] The mark distortions caused with use of a semi-transparent
film cannot be removed even if the light waveform of the recording
laser is changed. The reflectivity at a space portion between mark
portions is also enhanced. From this, at the trailing edge of the
recorded mark, a physical change in the volume of a dye or in the
surface state thereof may occur, resulting in generating the
distortions. When the recording film surface of disc 100 is
observed using SEM (scanning type electronic microscope), the
surface after recording becomes more rough than that before
recording. This may be caused by a change in the volume of the dye
after recording.
[0051] Meanwhile, when the recording film surface of disc 100 using
a mark-distortion-free dye is observed using SEM, the surface after
recording is not ragged.
[0052] Analysis and comparison between samples of the
mark-distortion-free dye are made using HPCL (High-Performance
Liquid Chromatography): one sample being extracted from the disc
after recording and the other sample being extracted from the disc
before recording. There is no difference between the samples.
Analyses using NMR (Nuclear Magnetic Resonance), IR (Infrared
Radiation), and MS (Magnetic Scanning) are also done, but no
difference between samples before and after recordings is found
too. It is concluded that the recording is independent of chemical
change.
[0053] To solve the task, therefore, for an information recording
medium (a single- or multi-layer recordable optical disc) using an
organic dye for the recording layer (L0 and/or L1), the information
recording is performed with a laser-power modulation. Further, as
the organic dye, it is sufficient to select an organic dye material
with which almost no change at the recording mark area in the
recording layer will occur with information recording.
[0054] Specifically, a specific dye material is used for the
recording layer, wherein a change in the volume of or in the
surface condition of the recording layer at the recording mark area
is to be equal to or less than 10%. Or, a specific material is used
for the dye material of the recording layer, said specific material
having a property to substantially avoid a chemical change in the
recorded layer. More specifically, at least part of an organic dye
material to be used for the recording layer may include an azo
metal complex whose center metal uses copper Cu or nickel Ni.
[0055] When a change in the volume of or in the surface condition
of the recording layer at the recording mark area exists, it is
liable to occur a distortion in the reproduction signal obtained
when repetitive patterns of long marks/spaces (e.g., 11T patterns)
are recorded. From this, the difference ([I11Lmax-I11Lmin]) between
the maximum and minimum values of a signal level from a space
portion is to be 10% of the minimum value (I11min) or less, where
the signal is reproduced when long patterns are recorded, and both
the mark and space lengths of the long patterns are longer than
1.2*.lamda./NA (.lamda. denotes the laser wavelength for recording,
and NA denotes the numerical aperture).
[0056] Various embodiments will be described with reference to the
accompanying drawings. FIG. 1 shows an example of the configuration
of optical disc (a recordable or re-recordable single-sided
dual-layer disc as a practical example) 100 according to one of the
embodiments. As exemplified by (a) and (b) of FIG. 1, disc 100
comprises transparent resin substrate 101 having a disc-like figure
and being formed of a synthetic resin material such as
polycarbonate, for example. Grooves are coaxially or spirally
formed on transparent resin substrate 101. Transparent resin
substrate 101 may be manufactured by injection molding with a
stamper.
[0057] On transparent resin substrate 101 with 0.59 mm thickness
and made of polycarbonate or the like, organic dye recording layer
105 and semi-transparent light-reflection or light-reflective layer
106 are sequentially laminated or stacked for the first layer (L0).
Photo Polymer (abbreviated as 2P resin) intermediate layer 104 is
spin-coated on layer 106. Then, the groove pattern of the second
layer (L1) is transferred to layer 104, and organic dye recording
layer 107 and reflection or reflective film 108 of silver or silver
alloy are sequentially laminated or stacked for the second layer
(L1). To the body on which L0 and L1 recording layers are laminated
or stacked, another transparent resin substrate (or dummy
substrate) 102 with 0.59 mm thickness is pasted via UV curing resin
(adhesive layer) 103. The organic dye recording films (recording
layers 105 and 107) have a dual-layer configuration in which
semi-transparent reflection or reflective layer 106 and
intermediate layer 104 are sandwiched between the organic dye
recording films. The total thickness of the resultant pasted
optical disc is about 1.2 mm.
[0058] On transparent resin substrate 101, spiral grooves with the
track pitch of 0.4 .mu.m and the depth of 60 nm, for example, are
formed (for respective layers L0 and L1). The grooves are wobbled
so that address information is recorded on the wobble. Further,
recording layers 105 and 107 each including an organic dye are
formed on transparent resin substrate 101 so as to fill-up the
grooves.
[0059] As the organic dye for forming recording layers 105 and 107,
a dye material whose maximum absorption wavelength area is shifted
to the longer wavelength side than the recording wavelength (e.g.,
405 nm) may be used. Note that the dye material is designed to have
a substantially large light absorption at the longer wavelength
area (e.g., 450 nm to 600 nm), and the absorption does not
disappear at the recording wavelength area.
[0060] The organic dye (practical examples will be described later)
is dissolved in a solvent to provide a liquid material. The
recording film thickness can be precisely managed by controlling
the dilution rate of the solvent and/or the rotating speed of
spin-coating.
[0061] A low light reflectivity may be met when a recording laser
light is focused on or tracking over the track before recording of
information. Thereafter, the dye is subjected to a resolving
reaction by the laser light to reduce the optical absorption rate,
so that the light reflectivity at the recording mark portion is
enhanced. From this, a so-called "Low-to-High" (or "L to H")
characteristic is obtained wherein the light reflectivity at the
recording mark portion formed by irradiating the laser light
becomes higher than the light reflectivity obtained before the
laser light irradiation.
[0062] Incidentally, in transparent resin substrate 101,
particularly at the groove bottom portion (of L0 or L1), some
deformations may be caused by heat generated due to the irradiation
of the recording laser. In this case, in a reproduction process
after recording, a phase difference (compared with the case of no
heat deformation) could occur in the reflected laser light.
Problems due to the phase difference can be suppressed or avoided
if deformations of the recording mark are prohibited or prevented
by the embodiment.
[0063] According to the embodiment, a physical format that can be
applied to the L0 and L1 layers on transparent resin substrate 101
and photo polymer (2P resin) 104 may be as follows: Namely, general
parameters of a recordable single-sided dual-layer disc are almost
the same as those of a single-layer disc, except for the following.
That is, the user-available recording capacity is 30 GB, the inner
radius of layer 0 (L0 layer) of the data area is 24.6 mm, the inner
radius of layer 1 (L1 layer) thereof is 24.7 mm, and the outer
radius (of each of layer 0 and layer 1) of the data area is 58.1
mm.
[0064] In optical disc 100 of FIG. 1(a), system lead-in area SLA
includes a control data section as exemplified by FIG. 1(c). The
control data section includes, as a part of physical format
information, etc., recording-related parameters such as recording
power (peak power), bias power, and the like, for each of L0 and
L1.
[0065] On the track within data area DA of optical disc 100, as
exemplified by FIG. 1(d), mark/space recording is done by the laser
with a given recording power (peak power) and bias power. By this
mark/space recording, as exemplified by FIG. 1(e), object data
(such as VOB) and its management information (VMG) of a
high-definition TV broadcasting program, for example, are recorded
on the track (of L0 and/or L1) in data area DA.
[0066] A cyanine dye, styryl dye, azo dye, or the like may be used
as an organic dye applicable to the embodiment. Particularly, the
cyanine dye or the styryl dye is suitable because control of the
absorption with respect to the recording wavelength is easy. The
azo dye may be obtained as a single azo compound or as a complex of
a metal and one or more molecules of an azo compound.
[0067] In the embodiment, cobalt, nickel, or copper may be used for
the center metal M of the azo metal complex so as to enhance the
optical stability. However, without being limited thereto, there
may be used for the center metal M of the azo metal complex:
scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium,
tantalum, chrome, molybdenum, tungsten, manganese, technetium,
rhenium, iron, ruthenium, osmium, rhodium, iridium, palladium,
platinum, silver, gold, zinc, cadmium, or mercury and the like.
[0068] An azo compound includes an aromatic ring. Not only by
applying various structures to the aromatic ring, but by adopting
or getting various substituents for the aromatic ring, it is
possible to optimize the characteristics of recording, preserving,
reproduction stability, etc. As the substituent becomes bulky,
there is a tendency to improve the persistence to reproduction
light. But at the same time, there is another tendency to lower the
recording sensitivity. From this it is proposed to select a
suitable substituent with which both characteristics of the
persistence and the sensitivity are good. This substituent concerns
the solubility of the solvent.
[0069] Differing from the recording mechanism of a dye-based
information recording medium until now (whose recording laser
wavelength is longer than 620 nm), in case of the invention
relating to short wavelength laser recording (whose recording
wavelength is 405 nm, for instance), the recording mechanism is
independent of a physical change in the substrate and/or in the
volume of the dye film. During reproducing, the dye is subjected to
the irradiation of a feeble laser (weaker than the recording
laser). Heat or light of this laser causes a gradual change in the
arrangement or orientation of dye molecules in the recording layer,
or in the spatial conformation or spatial arrangement of the dye
molecules. However, bulky substituents in the dye molecules may
disturb that change. In other words, the bulky substituent serves
to improve the persistence to reproduction light.
[0070] The bulky substituent may be a substituent comprising three
or more carbons for substituting an aromatic ring in dye molecule.
Examples of the substituent include n-propyl group, isopropyl
group, n-butyl group, 1-methylpropyl group, 2-methylpropyl group,
n-pentyl group, 1-ethylpropyl group, 1-methylbutyl group,
2-methylbutyl group, 3-methylbutyl group, 1,1-dimethylpropyl group,
1,2-dimethylpropyl group, 2,2-dimethylpropyl group, cyclopentyl
group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group,
3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl
group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group,
2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl
group, 1-ethylbutyl group, 2-ethylbutyl group, cyclohexyl group,
phenyl group, and the like. Incidentally, the substituent may
include an atom other than carbon, such as oxygen, sulfur,
nitrogen, silicon, fluorine, bromine, iodine, or the like.
[0071] FIG. 2 shows an example of the metal complex portion of an
organic dye material for the recording layer. A circular periphery
area around center metal M of the azo metal complex shown in FIG. 2
is obtained as coloring area 8. When a laser light beam passes
through coloring area 8, local electrons in coloring area 8
resonate to an electric field change of the laser light beam, and
absorbs energy of the laser light beam. A value converted to a
wavelength of the laser light beam with respect to a frequency of
an electric field change at which these local electrons resonate
most and easily absorbs the energy is called a maximum absorption
wavelength, and is represented by .lamda.max. As a range of
coloring area 8 (resonation range) as shown in FIG. 2 increases,
the maximum absorption wavelength .lamda.max is shifted to the long
wavelength side. In addition, the localization range of local
electrons around the center metal M (how large the center metal M
can attract the local electrons to the vicinity of the center) is
changed by changing atoms of the center metal M, and the value of
the maximum absorption wavelength .lamda.max changes. When a
material having a property that the .lamda.max is about 405 nm is
selected, an organic material having a sensitivity (optical
absorption) at wavelength 405 nm can be obtained.
[0072] As the dye material for the recording layer (e.g., L0 or L1)
having an optical absorption at wavelength 405 nm, it is possible
to use an organic dye material having a structure corresponding to
a combination of the organic metal complex portion whose general
structural formula is shown by FIG. 2 and a dye material portion
(not shown). The center metal M of the organic metal complex
portion may generally be cobalt or nickel (or scandium, yttrium,
titanium, zirconium, hafnium, vanadium, niobium, tantalum, chrome,
molybdenum, tungsten, manganese, technetium, rhenium, iron,
ruthenium, osmium, rhodium, iridium, palladium, platinum, copper,
silver, gold, zinc, cadmium, mercury, etc.). The dye material
portion may be cyanine dye, styril dye, or monomethine cyanine dye
(not shown).
[0073] Here, a theory of recording in a current DVD-R will be
explained. According to a current DVD-R disc, when laser light 7 is
irradiated to the recording film, recording film 3-2 partly absorbs
the energy of laser light 7, resulting in heating-up at the
energy-absorbing portion. When the temperature at that portion goes
over a specific temperature, transparent substrate 2-2 is partly
deformed. Although a mechanism, which induces deformation of
transparent substrate 2-2, is different depending on manufacturers
of DVD-R discs, it is said that this mechanism is caused by:
[0074] (1) local plastic deformation of transparent substrate 2-2
due to gasification energy of recording layer 3-2; and
[0075] (2) transmission of a heat from recording layer 3-2 to
transparent substrate 2-2 and local plastic deformation of
transparent substrate 2-2 due to the heat. If transparent substrate
2-2 is locally plastically deformed, there changes an optical
distance of laser light beam 7 reflected in light reflection or
reflective layer 4-2 through transparent substrate 2-2, the laser
light beam 7 coming back through transparent substrate 2-2 again. A
phase difference occurs between the laser light beam 7 from a
recording mark, the laser light beam coming back through a portion
of the locally plastically deformed transparent substrate 2-2, and
the laser light beam 7 from the periphery of the recording mark,
the laser light beam coming back through a portion of transparent
substrate 2-2 which is not deformed, and thus, a light amount
change of reflection light beam occurs due to interference between
these light beams. In particular, in case where the above described
mechanism of (1) has occurred, a change of a substantial refractive
index n32 produced by cavitations of the inside of the recording
mark in the recording layer 3-2 due to gasification (evaporation),
or alternatively, a change of a refractive index n32 produced due
to thermal decomposition of an organic dye recording material in
the recording mark, also contributes to the above described
occurrence of a phase difference. In the current DVD-R disc, until
transparent substrate 2-2 is locally deformed, there is a need for
recording layer 3-2 becoming hot (i.e., at a gasification
temperature of recording layer 3-2 in the above described mechanism
of (1) or at an internal temperature of recording layer 3-2
required for plastically reforming transparent substrate 2-2 in the
mechanism of (2)) or there is a need for a part of recording layer
3-2 becoming hot in order to cause thermal decomposition or
gasification (evaporation). In order to form a recording mark,
there is a need for large amount of power of laser light beam
7.
[0076] In order to form the recording mark, there is a demand that
recording layer 3-2 can absorb energy of laser light beam 7 at a
first stage. The light absorption spectra in recording layer 3-2
influence the recording sensitivity of an organic dye recording
film. A principle of light absorption in an organic dye recording
material which forms recording layer 3-2 will be described with
reference to (A3) of the embodiment.
[0077] FIG. 2 shows a specific structural formula of the specific
contents "(A3) azo metal complex+Cu" of the constituent elements of
the information storage medium. A circular periphery area around
center metal M of the azo metal complex shown in FIG. 2 is obtained
as coloring area 8. When laser light beam 7 passes through coloring
area 8, local electrons in coloring area 8 resonate to an electric
field change of laser light beam 7, and absorbs energy of laser
light beam 7. A value converted to a wavelength of the laser light
beam with respect to a frequency of an electric field change at
which these local electrons resonate most and easily absorbs the
energy is called a maximum absorption wavelength, and is
represented by .lamda.max. As a range of coloring area 8
(resonation range) as shown in FIG. 2 increases, the maximum
absorption wavelength .lamda.max is shifted to the long wavelength
side. In addition, in FIG. 2, the localization range of local
electrons around the center metal M (how large the center metal M
can attract the local electrons to the vicinity of the center) is
changed by changing atoms of center metal M, and the value of the
maximum absorption wavelength .lamda.max changes.
[0078] Although it can be predicted that the light absorption
spectra of the organic dye recording material in the case where
there exists only one coloring area 8 which is absolute 0 degree at
a temperature and high in purity draws narrow linear spectra in
close to a maximum absorption wavelength .lamda.max, the light
absorption spectra of a general organic recording material
including impurities at a normal temperature, and further,
including a plurality of light absorption areas exhibit a wide
light absorption characteristic with respect to a wavelength of a
light beam around the maximum absorption wavelength .lamda.max.
FIG. 5 shows an example of light absorption spectra of an organic
dye recording material used for a current DVD-R disc. In FIG. 5, a
wavelength of a light beam to be irradiated with respect to an
organic dye recording film formed by coating an organic dye
recording material is taken on a horizontal axis, and absorbance
obtained when an organic dye recording film is irradiated with a
light beam having a respective wavelength is taken on a vertical
axis. The absorbance used here is a value obtained by entering a
laser light beam having incident intensity Io from the side of
transparent substrate 2-2 with respect to a state in which a
recordable or write-once type information storage medium has been
completed (or alternatively, a state in which recording layer 3-2
is merely formed on transparent substrate 2-2 (a state that
precedes forming of an optical reflection or reflective layer)),
and then, measuring reflected laser light intensity Ir (light
intensity It of the laser light beam transmitted from the side of
recording layer 3-2). The absorbance Ar (At) is represented by:
Ar.ident.-log 10(Ir/Io) (A-1)
Ar.ident.-log 10(It/Io) (A-2)
[0079] Unless otherwise specified, although a description will be
given assuming that the absorbance denotes absorbance Ar of a
reflection shape expressed by formula (A-1), it is possible to
define absorbance At of a transmission shape expressed by formula
(A-2) without being limited thereto in the embodiment. In the
embodiment shown in FIG. 5, there exist a plurality of light
absorption areas, each of which includes coloring area 8, and thus,
there exist a plurality of positions at which the absorbance
becomes maximal. In this case, there exist a plurality of maximum
absorption wavelengths .lamda.max when the absorbance takes a
maximum value. A wavelength of the recording laser light in the
current DVD-R disc is set to 650 nm. In the case where there exist
a plurality of the maximum absorption wavelengths .lamda.max in the
embodiment, a value of the maximum absorption wavelength .lamda.max
which is the closest to the wavelength of the recording laser light
beam becomes important. Therefore, only in the description of the
embodiment, the value of the maximum absorption wavelength
.lamda.max set at a position which is the closest to the wavelength
of the recording laser light beam is defined as ".lamda.max write";
and is discriminated from other .lamda.max (.lamda.max 0).
[0080] 2-2) Difference of Light Reflection or Reflective Layer
Shape in Pre-Pit/Pre-Groove Area . . . Influence on Optical
Reflection or Reflective Layer Shape (Difference Between
Spin-Coating and Sputtering Deposition) and Reproduction Signal
[0081] FIGS. 6A and 6B show a comparison in shape when a recording
film is formed in a pre-pit area or pre-groove area 10. FIG. 6A
shows a shape relevant to a phase change recording film. In the
case of forming any of undercoat intermediate layer 5, recording
layer 3-1, upper intermediate layer 6, and light reflection or
reflective layer 4-1 as well, any of methods of sputtering vapor
deposition, vacuum vapor deposition, or ion plating is used in
vacuum. As a result, in all of the layers, irregularities of
transparent substrate 2-1 are duplicated comparatively faithfully.
For example, in the case where a sectional shape in the pre-pit
area or pre-groove area 10 of transparent substrate 2-1 is
rectangular or trapezoidal, the sectional shape of recording layer
3-1 and light reflection or reflective layer 4-1 each is also
rectangular or trapezoidal.
[0082] FIG. 6B shows a general recording film sectional shape of a
current DVD-R disc which is a conventional technique as a recording
film in the case where an organic dye recording film is used. In
this case, as a method for forming the recording film 3-2, there is
used a method called spin coating (or spinner coating) which is
completely different from that shown in FIG. 6A. The spin coating
used here denotes a method for dissolving in an organic solvent an
organic dye recording material which forms recording layer 3-2;
applying a coating onto transparent substrate 2-2; followed by
rotating transparent substrate 2-2 at a high speed to spread a
coating agent to the outer periphery side of transparent substrate
2-2 by a centrifugal force; and gasifying the organic solvent,
thereby forming the recording layer 3-2. Using this method, a
process for coating the organic solvent is used, and thus, a
surface of recording layer 3-2 (an interface with light reflection
or reflective layer 2-2) is easily flattened. As a result, the
sectional shape on the interface between light reflection or
reflective layer 2-2 and recording layer 3-2 is obtained as a shape
which is different from the shape of the surface of transparent
substrate 2-2 (an interface between transparent substrate 2-2 and
recording layer 3-2). For example, in a pre-groove area in which
the sectional shape of the surface of transparent substrate 2-2 (an
interface between transparent substrate 2-2 and recording layer
3-2) is rectangular or trapezoidal, the sectional shape on the
interface between light reflection or reflective layer 2-2 and
recording layer 3-2 is formed in a substantially V-shaped groove
shape. In a pre-pit area, the above sectional shape is formed in a
substantially conical side surface shape. Further, at the time of
spin coating, an organic solvent is easily collected at a recessed
portion, and thus, the thickness Dg of recording layer 3-2 in the
pre-pit area or pre-groove area 10 (i.e., a distance from a bottom
surface of the pre-pit area or pre-groove area to a position at
which an interface relevant to light reflection or reflective layer
2-2 becomes the lowest) is larger than the thickness D1 in land
area 12 (Dg>Dl). As a result, an amount of irregularities on an
interface between transparent substrate 2-2 and recording area 3-2
in the pre-pit area or pre-groove area 10 becomes materially
smaller than an amount of irregularities on transparent substrate
2-2 and recording layer 3-2.
[0083] As described above, the shape of irregularities on the
interface between light reflection or reflective layer 2-2 and
recording layer 3-2 becomes blunt and an amount of irregularities
becomes significantly small. Thus, in the case where the shape and
dimensions of irregularities on a surface of transparent substrate
2 (pre-pit area or pre-groove area 10) are equal to each other,
depending on a difference in method for forming a recording film,
the diffraction intensity of the reflection light beam from the
organic dye recording film at the time of laser light irradiation
is degraded more significantly than the diffraction intensity of
the reflection light beam from the phase change recording film. As
a result, in the case where the shape and dimensions of
irregularities on the surface of transparent substrate 2 (pre-pit
area or pre-groove area 10) are equal to each other, as compared
with use of the phase change recording film, use of the
conventional organic dye recording film is disadvantageously
featured in that:
[0084] (1) a degree of modulation of a light reproduction signal
from the pre-pit area is small, and signal reproduction reliability
from the pre-pit area is poor;
[0085] (2) a sufficiently large track shift detecting signal is
hardly obtained in accordance with a push-pull technique from the
pre-groove area; and
[0086] (3) a sufficient large wobble detecting signal is hardly
obtained in the case where wobbling occurs in the pre-groove
area.
[0087] In addition, in a DVD-R disc, specific information such as
address information is recorded in a small irregular (pit) shape in
a land area, and thus, width Wl of the land area 12 is larger than
width Wg of the pre-pit area or pre-groove area 10 (Wg>Wl).
[0088] Chapter 3: Description of Characteristics of Organic Dye
Recording Film in the Embodiment
[0089] 3-1) Problem(s) Relevant to Achievement of High Density in
Write-Once Type Recording Film (DVD-R) Using Conventional Organic
Dye Material
[0090] As has been described in "2-1) Difference in recording
principle/recording film structure and difference in basic concept
relating to generation of reproducing signal", a general principle
of recording of a current DVD-R and CD-R, which is a recordable
(write-once type) information storage medium using a conventional
organic dye material includes "local plastic deformation of
transparent substrate 2-2" or "local thermal decomposition or
gasification in recording layer 3-2". FIGS. 7A and 7B show a
plastic deformation state of a specific transparent substrate 2-2
at a position of a recording mark 9 in a write-once type
information storage medium using a conventional organic dye
material. There exist two types of typical plastic deformation
states. There are two cases, i.e., a case in which, as shown in
FIG. 7A, a depth of bottom surface 14 of a pre-groove area at the
position of recording mark 9 (an amount of step relevant to
adjacent land area 12) is different from a depth of a bottom
surface of pre-groove area 11 in an unrecorded area (in the example
shown in FIG. 7A, the depth of bottom surface 14 in the pre-groove
area at the position of recording mark 9 is shallower than that in
the unrecorded area); and a case in which, as shown in FIG. 7B,
bottom surface 14 in a pre-groove area at the position of recording
mark 9 is distorted and is slightly curved (the flatness of bottom
surface 14 is distorted: In the example shown in FIG. 7B, bottom
surface 14 in the pre-groove area at the position of recording mark
9 is slightly curved toward the lower side). Both of these cases
are featured in that a plastic deformation range of transparent
substrate 2-2 at the position of recording mark 9 covers a wide
range. In the current DVD-R disc which is a conventional technique,
a track pitch is 0.74 .mu.m, and a channel bit length is 0.133
.mu.m. In the case of a large value of this degree, even if the
plastic deformation range of transparent substrate 2-2 at the
position of recording mark 9 covers a wide range, comparatively
stable recording and reproducing processes can be carried out.
[0091] However, if the track pitch is narrower than 0.74 .mu.m
described above, the plastic deformation range of transparent
substrate 2-2 at the position of recording mark 9 covers a wide
range, and thus, the adjacent tracks are adversely affected with
"cross-write" or "cross-erase". In the "cross-write" the recording
mark is widened to the adjacent tracks, and in the "cross-erase"
the recording mark of the existing adjacent track is substantially
erased (or cannot be reproduced) due to overwriting. In addition,
in a direction (circumferential direction) along the tracks, if the
channel bit length is narrower than 0.133 .mu.m, there occurs a
problem that inter-code interference appears; an error rate at the
time of reproduction significantly increases; and the reliability
of reproduction is lowered.
[0092] 3-2) Description of Basic Characteristics Common to Organic
Dye Recording Film in the Embodiment
[0093] 3-2-A] Range Requiring Application of Technique According to
the Embodiment
[0094] As shown in FIGS. 7A and 7B, in a conventional recordable
(write-once type) information storage medium including plastic
deformation of transparent substrate 2-2 or local thermal
decomposition or gasification phenomenon in recording film 3-2, a
description will be given below with respect to what degree of
track pitch is narrowed when an adverse affect appears or what
degree of channel pit length is narrowed when an adverse effect
appears and a result obtained after technical discussion has been
carried out with respect to a reason for such an adverse effect. A
range in which an adverse effect starts appearing in the case of
utilizing the conventional principle of recording indicates a range
(suitable for the achievement of high density) in which
advantageous effect is attained due to a novel principle of
recording shown in the embodiment.
[0095] 1) Condition of Thickness Dg of Recording Layer 3-2
[0096] When an attempt is made to carry out thermal analysis in
order to theoretically identify a lower limit value of an allowable
channel bit length or a lower limit value of allowable track pitch,
a range of the thickness Dg of recording layer 3-2 which can be
substantially thermally analyzed becomes important. In a
conventional recordable (write-once type) information storage
medium (CD-R or DVD-R) including plastic deformation of transparent
substrate 2-2 as shown in FIGS. 7A and 7B, with respect to a change
of light reflection amount in the case where an information
reproduction focusing spot is provided in recording mark 8 and in
the case where the spot is in an unrecorded area of recording layer
3-2, the largest factor is "an interference effect due to a
difference in optical distance in recording mark 9 and in
unrecorded area". In addition, a difference in its optical
difference is mainly caused by "a change of the thickness Dg of
physical recording layer 3-2 due to plastic deformation of
transparent substrate 2-2 (Dg: a physical distance from an
interface between transparent substrate 2-2 and recording layer 3-2
to an interface between recording layer 3-2 and light reflection or
reflective layer 4-2)" and "a change in refractive index n32 of
recording layer 3-2 in recording mark 9". Therefore, in order to
obtain a sufficient reproduction signal (change of light reflection
amount) between the recording mark 9 and the unrecorded area, when
a wavelength in vacuum of laser light beam is defined as .lamda.,
it is demanded that the value of thickness Dg of recording layer
3-2 in the unrecorded area has a size to some extent as compared
with .lamda./n32. If not, a difference (phase difference) in
optical distance between the recording mark 9 and the unrecorded
area does not appear, and light interference effect becomes small.
In practice, a minimum condition:
Dg.gtoreq..lamda./8n32 (1)
[0097] shall be met, and desirably, a condition that:
Dg.gtoreq..lamda./4n32 (2)
[0098] may be met.
[0099] At a time point of current discussion, the vicinity of
.lamda.=405 nm is assumed. A value of refractive index n32 of an
organic dye recording material at 405 nm ranges from 1.3 to 2.0.
Therefore, as a result of substituting n32=2.0 in formula (1), it
is conditionally mandatory that the value of thickness Dg of
recording layer 3-2 is:
Dg.gtoreq.25 nm (3)
[0100] Here, discussion is made with respect to a condition when an
organic dye recording layer of a conventional recordable
(write-once type) information storage medium (CD-R or DVD-R)
including plastic deformation of transparent substrate 2-2 is
associated with a light beam of 405 nm. As described later, in the
embodiment, although a description is given with respect to a case
in which plastic deformation of transparent substrate 2-2 does not
occur and a change of absorption coefficient k32 is a main factor
of the principle of recording, it is demanded to carry out track
shift detection by using, e.g., a DPD (Differential Phase
Detection) technique from recording mark 9, and thus, in reality,
the change of refractive index n32 is caused in recording mark 9.
Therefore, the condition for formula (3) is considered to be met in
the embodiment in which plastic deformation of transparent
substrate 2-2 does not occur.
[0101] From another point of view as well, the range of thickness
Dg can be specified. In the case of a phase change recording film
shown in FIG. 6A, when a refractive index of the transparent
substrate is n21, the step amount between a pre-pit area and a land
area is .lamda./(8n21) when the largest track shift detection
signal is obtained by using a push-pull technique. However, in the
case of an organic dye recording film shown in FIG. 6B, as
described previously, the shape on an interface between recording
layer 3-2 and light reflection or reflective layer 4-2 becomes
blunt, and the step amount becomes small. Thus, it is demanded to
increase the step amount between the pre-pit area and the land area
on transparent substrate 2-2 more significantly than
.lamda./(8n22). When polycarbonate is used as a material for
transparent substrate 2-2, for example, the refractive index at 405
nm is n22.apprxeq.1.62. From this, it is demanded to increase a
step amount between the pre-pit area and the land area more
significantly than 31 nm. In the case of using a spin coating
technique, if the thickness Dg of recording layer 3-2 in the
pre-groove area is greater than the step amount between the pre-pit
area and the land area on transparent substrate 2-2, there is a
risk that the thickness D1 of recording layer 3-2 in land area 12
disappears. Therefore, from the above described discussion result,
it is demanded to meet a condition that:
Dg.gtoreq.31 nm (4)
[0102] The condition for formula (4) is also a condition, which
should be met in the embodiment in which plastic deformation of
transparent substrate 2-2 does not occur. Although conditions for
the lower limit values have been shown in formulas (3) and (4), the
value Dg.apprxeq.60 nm obtained by substituting n32=1.8 for an
equal sign portion in formula (2) is utilized as the thickness Dg
of recording layer 3-2 used for thermal analysis.
[0103] Then, assuming polycarbonate used as a standard material of
transparent substrate 2-2, 150.degree. C. which is a glass
transition temperature of polycarbonate is set as an estimate value
of a thermal deformation temperature at the side of transparent
substrate 2-2. For discussion using thermal analysis, a value of
k32=0.1 to 0.2 is assumed as a value of an absorption coefficient
of organic dye recording film 3-2 at 405 nm. Further, for the case
wherein NA=60 as the condition of a conventional DVD-R format and
NA=0.65 as the H format, discussion has been made with respect to
the NA value of a focusing objective lens and the incident light
intensity distribution when the light passes through the objective
lens.
[0104] (2) Condition for Lower Limit Value of Channel Bit
Length
[0105] A check has been made for a lengthwise change in a direction
along a track of an area reaching a thermal deformation temperature
at the side of transparent substrate 2-2 which comes into contact
with recording layer 3-2, when recording power is changed.
Discussion has been made with respect to a lower limit value of an
allowable channel bit length considering a window margin at the
time of reproduction. As a result, if the channel bit length is
lower than 105 nm, it is considered that a lengthwise change in a
direction along a track in an area which reaches the thermal
deformation temperature at the side of transparent substrate 2-2
occurs according to a slight change in the recording power, and a
sufficient window margin cannot be obtained. On discussion of
thermal analysis, an analogous tendency is shown in the case where
the NA value is any one of 0.60, 0.65, and 0.85. Although a
focusing spot size is changed by changing the NA value, a
possibility cause is believed to be that a thermal spreading range
is wide (a gradient of a temperature distribution at the side of
transparent substrate 2-2 which comes into contact with recording
layer 3-2 is comparatively gentle). In the above thermal analysis,
the temperature distribution at the side of transparent substrate
2-2 which comes into contact with recording layer 3-2 is discussed,
and thus, an effect of the thickness Dg of recording layer 3-2 does
not appear.
[0106] Further, in the case where a shape change of transparent
substrate 3-3 shown in FIGS. 7A and 7B occurs, a boundary position
of a substrate deformation area blurs (is ambiguous), and thus, a
window margin is lowered more significantly. When the sectional
shape of an area in which recording mark 9 is formed is observed by
an electron microscope, it is believed that a blurring amount of
the boundary position of the substrate deformation area increases
as the value of the thickness Dg of recording layer 3-2 increases.
With respect to the effect of the thermal deformation area length
due to the above recording power change, in consideration of the
blurring of the boundary position of this substrate deformation
area, it is demanded that the lower limit value of the channel bit
length allowed for allocation of a sufficient window margin is in
order of two times of the thickness Dg of recording layer 3-2, and
it is desirable that the lower limit value is greater than 120
nm.
[0107] In the foregoing, a description has been principally given
with respect to discussion using thermal analysis in the case where
thermal deformation of transparent substrate 2-2 occurs. There also
exists a case in which plastic deformation of transparent substrate
2-2 is very small as another principle of recording (mechanism of
forming the recording mark 9) in a conventional write-once type
information storage medium (CD-R or DVD-R) and thermal deformation
or gasification (evaporation) of the organic dye recording material
in recording layer 3-2 mainly occurs. Thus, an additional
description will be given with respect to such a case. Although the
gasification (evaporation) temperature of the organic dye recording
material is different depending on the type of the organic dye
material, in general, the temperature ranges 220.degree. C. to
370.degree. C., and a thermal decomposition temperature is lower
than this range. Although a glass transition temperature
150.degree. C. of a polycarbonate resin has been presumed as an
arrival temperature at the time of substrate deformation in the
above discussion, a temperature difference between 150.degree. C.
and 220.degree. C. is small, and, when transparent substrate 2-2
reaches 150.degree. C., the inside of recording layer 3-2 may
exceed 220.degree. C. Therefore, although there exists an exception
depending on the type of the organic recording material, even in
the case where plastic deformation of transparent substrate 2-2 is
very small and thermal decomposition or gasification (evaporation)
of the organic dye recording material in the recording layer mainly
occurs, there is obtained a result which is substantially identical
to the above discussion result.
[0108] When the discussion result relating to the above channel bit
length is summarized, in the conventional write-once type
information storage medium (CD-R or DVD-R) including plastic
deformation of transparent substrate 2-2, it is considered that,
when a channel bit length is narrower than 120 nm, the lowering of
a window margin occurs, and further, if the length is smaller than
105 nm, stable reproduction becomes difficult. That is, when the
channel bit is smaller than 120 nm (e.g., 105 nm), advantageous
effect is attained by using a novel principle of recording shown in
the embodiment.
[0109] (3) Condition for Lower Limit Value of Track Pitches
[0110] When recording layer 3-2 is exposed at recording power,
energy is absorbed in recording layer 3-2, and a high temperature
is obtained. In a conventional write-once type information storage
medium (CD-R or DVD-R), it is demanded to absorb energy in
recording layer 3-2 until transparent substrate 3-2 has reached a
thermal deformation temperature. A temperature at which a
structural change of the organic dye recording material occurs in
recording layer 3-2 and a value of a refractive index n32 or an
absorption coefficient k32 starts its change is much lower than an
arrival temperature for transparent substrate 2-2 to start thermal
deformation. Therefore, the value of refractive index n32 or
absorption coefficient k32 changes in a comparatively wide range in
recording layer 3-2 at the periphery of recording mark 9, which is
thermal deformed at the side of transparent substrate 2-2, and this
change seems to cause "cross-write" or "cross-erase" for the
adjacent tracks. It is possible to set the lower limit value of
track pitch in which "cross-write" or "cross-erase" does not occur
with the width of an area which reaches a temperature that changes
the refractive index n32 or absorption coefficient k32 in recording
layer 3-2 when transparent substrate 2-2 exceeds a thermal
deformation temperature. From the above point of view, it is
considered that "cross-write" or "cross-erase" may occur in
location in which the track pitch is equal to or smaller than 500
nm. Further, in consideration of an effect of warping or
inclination of an information storage medium or a change of
recording power (recording power margin), it can be concluded
difficult to set the track pitch to 600 nm or less in the
conventional write-once type information storage medium (CD-R or
DVD-R) in which energy is absorbed in recording layer 3-2 until
transparent substrate 2-2 has reached a thermal deformation
temperature. As described above, even if the NA value is changed
from 0.60, 0.65, and then, to 0.85, substantially similar tendency
is shown because the gradient of the temperature distribution in
the peripheral recording layer 3-2 when transparent substrate 2-2
has reached a thermal deformation temperature at a center part is
comparatively gentle, and the thermal spread range is wide. In the
case where plastic deformation of transparent substrate 2-2 is very
small and thermal decomposition or gasification (evaporation) of
the organic dye recording material in recording layer 3-2 mainly
occurs as another principle of recording (mechanism of forming the
recording mark 9) in the conventional write-once type information
storage medium (CD-R or DVD-R), as has been described in the
section "(2) Condition for lower limit value of channel bit", the
value of track pitch at which "cross-write" or "cross-erase" starts
is obtained as a substantially analogous result. For the above
described reason, advantageous effect is attained by using a novel
principle of recording shown in the embodiment when the track pitch
is set to 600 nm (500 nm) or lower.
[0111] 3-2-B] Basic Characteristics Common to Organic Dye Recording
Material in the Invention
[0112] As described above, in the case where plastic deformation of
transparent substrate 2-2 is very small and thermal decomposition
or gasification (evaporation) of the organic dye recording material
in recording layer 3-2 mainly occurs as another principle of
recording (mechanism of forming the recording mark 9) in the
conventional write-once type information storage medium (CD-R or
DVD-R), there occurs a problem that a channel bit length or track
pitches cannot be narrowed because the inside of recording layer
3-2 or a surface of transparent substrate 2-2 reaches a high
temperature at the time of forming the recording mark 9. In order
to solve the above described problem, the embodiment is featured in
"inventive organic dye material" in which "a local optical
characteristic change in recording layer 3-2, which occurs at a
comparatively low temperature, is a principle of recording" and
"setting environment (recording film structure or shape) in which
the above principle of recording easily occurs without causing a
substrate deformation and gasification (evaporation) in recording
layer 3-2. Specific characteristics of the embodiment can be listed
below.
[0113] .alpha.] Optical Characteristic Changing Method Inside of
Recording Layer 3-2
[0114] Chromogenic characteristic change
[0115] Change of light absorption sectional area due to qualitative
change of coloring area 8 (FIG. 2) or change of molar molecule
light absorption coefficient
[0116] Coloring area 8 is partially destroyed or the size of
coloring area 8 changes, whereby a substantial light absorption
sectional area changes. In this manner, an amplitude (absorbance)
at a position of .lamda.max write changes in recording mark 9 while
a profile (characteristics) of light absorption spectra (FIG. 5)
itself is maintained.
[0117] Change of electronic structure (electron orbit) relevant to
electrons which contribute to a chromogenic phenomenon
[0118] Change of light absorption spectra (FIG. 5) based on
discoloring action due to cutting of local electron orbit
(dissociation of local molecular bonding) or change of dimensions
or structure of coloring area 8 (FIG. 2)
[0119] Intra-molecular (inter-molecular) change of orientation or
array
[0120] Optical characteristic change based on orientation change in
azo metal complex shown in FIG. 2, for example
[0121] Molecular structure change in molecule
[0122] For example, discussion is made with respect to an organic
dye material which causes either of dissociation between anion
portion and cation portion, thermal decomposition of either of
anion portion and cation portion, and a tar phenomenon that a
molecular structure itself is destroyed, and carbon atoms are
precipitated (denaturing to black coal tar). As a result, the
refractive index n32 and/or absorption coefficient k32 in recording
mark 9 is changed with respect to an unrecorded area, enabling
optical reproduction.
[0123] .beta.] Setting Recording Film Structure or Shape, Making It
Easy to Stably Cause an Optical Characteristic Change of [.alpha.]
Above:
[0124] The specific contents relating to this technique will be
described in detail in the section "3-2-C) Ideal recording film
structure which makes it easy to cause a principle of recording
shown in the embodiment" and subsequent.
[0125] .gamma.] Recording Power is Reduced in Order to Form
Recording Mark in a State in which Inside of Recording Layer or
Transparent Substrate Surface is Comparatively Low at
Temperature
[0126] The optical characteristic change shown in [.alpha.] above
occurs at a temperature lower than a deformation temperature of
transparent substrate 2-2 or a gasification (evaporation)
temperature in recording layer 3-2. Thus, the exposure amount
(recording power) at the time of recording is reduced to prevent
the deformation temperature from being exceeded on the surface of
transparent substrate 2-2 or the gasification (evaporation)
temperature from being exceeded in recording layer 3-2. The
contents will be described later in detail in the section "3-3)
Recording characteristics common to organic dye recording layer in
the embodiment". In addition, in contrast, it becomes possible to
determine whether or not the optical characteristic change shown in
[.alpha.] above occurs by checking a value of the optimal power at
the time of recording.
[0127] .delta.] Electron Structure in a Coloring Area is
Stabilized, and Structural Decomposition Relevant to Ultraviolet
Ray or Reproduction Light Irradiation is Hardly Generated
[0128] When ultraviolet ray is irradiated to recording layer 3-2 or
reproduction light is irradiated to recording layer 3-2 at the time
of reproduction, a temperature size in recording layer 3-2 occurs.
There is a demand for an apparently contradictory performance that
characteristic degradation relevant to such a temperature rise is
prevented and recording is carried out at a temperature lower than
a substrate deformation temperature or a gasification (evaporation)
temperature in recording layer 3-2. In the embodiment, the above
described apparently contradictory performance is satisfied by
"stabilizing an electron structure in a coloring area". The
specific technical contents may be described in "Chapter 4 Specific
Description of Embodiments of Organic Dye Recording Film in the
embodiment".
[0129] .epsilon.] Reliability of Reproduction Information is
Improved for a Case in which Reproduction Signal Degradation Due to
Ultraviolet Ray or Reproduction Light Irradiation Occurs
[0130] In the embodiment, although a technical contrivance is made
for "stabilizing an electron structure in a coloring area", the
reliability of recording mark 9 formed by a principle of recording
shown in the embodiment may be principally lowered as compared with
a local cavity in recording layer 3-2 generated due to plastic
deformation or gasification (evaporation) of the surface of
transparent substrate 2-2. As countermeasures against it, in the
embodiment, advantageous effect that the high density and the
reliability of recording information are achieved at the same time
in combination with strong error correction capability (novel ECC
block structure), as may be described in "Chapter 7: Description of
H Format" and "Chapter 8: Description of B Format". Further, in the
embodiment, PRML (Partial Response Maximum Likelihood) technique is
employed in a reproduction method, as may be described in the
section "4-2 Description of reproducing circuit in the embodiment".
The high density and the reliability of recording information are
achieved at the same time in combination with an error correction
technique at the time of the ML demodulation.
[0131] 5-2) Characteristics of Light Absorption Spectra Relating to
"L-H" Recording Film in the Embodiment . . . Setting Condition for
the Value of Maximum Absorption Wavelength .lamda.max Write and
Ah405
[0132] As described in "3-4) Description of characteristics
relating to "H-L" recording film in the embodiment, the relative
absorbance in an unrecorded area is basically low in the "H-L"
recording film, and thus, when reproduction light is irradiated at
the time of reproduction, there occurs a little optical
characteristic change generated by absorbing energy of the
reproduction light. Even if an optical characteristic change
(update of recording action) occurs after the energy of the
reproduction light is absorbed in a recording mark having high
absorbance, a light reflection factor from the recording mark is
lowered. Thus, reproduction signal processing is less affected
because such a change effects on a direction in which an amplitude
(I11.ident.I11H-I11L) of the reproduction signal increases.
[0133] In contrast, the "L-H" recording film has optical
characteristics that "a light reflection factor of an unrecorded
portion is lower than that in a recording mark". This means that
the absorbance of the unrecorded portion is higher than that in the
recording mark. Thus, in the "L-H" recording film, signal
degradation at the time of reproduction is likely to occur as
compared with the "H-L" recording film.
[0134] As described in "3-2-B] Basic characteristics common to
organic dye recording material in the invention", there is a demand
for improving reliability of reproduction information in the case
where reproduction signal degradation has occurred due to
.epsilon.] ultraviolet ray or reproduction light irradiation".
[0135] As a result of examining the characteristics of an organic
dye recording material in detail, it is found that a mechanism of
absorbing the energy of reproduction light to cause an optical
characteristic change is substantially analogous to that of an
optical characteristic change due to ultraviolet ray irradiation.
As a result, if there is provided a structure of improving
durability relevant to ultraviolet ray irradiation in an unrecorded
area, signal degradation at the time of reproduction hardly occurs.
Thus, the embodiment is featured in that, in the "L-H" recording
film, a value of .lamda.max write (maximum absorption wavelength
which is the closest to wavelength of recording light) is longer
than a wavelength of recording light or reproduction light (close
to 405 nm). In this manner, the absorbance relevant to the
ultraviolet ray can be reduced, and the durability relevant to
ultraviolet ray irradiation can be significantly improved. As is
evident from FIG. 9, a difference in absorbance between the
recorded portion and the unrecorded portion in the vicinity of
.lamda.max write is small,
[0136] and a degree of reproduction signal modulation (signal
amplitude) is reduced where the light with a wavelength in the
vicinity of .lamda.max write is used for reproduction. In view of a
wavelength change of a semiconductor laser light source, it is
advisable that a sufficiently large degree of reproduction signal
modulation (signal amplitude) be taken in the range of 355 nm to
455 nm. Therefore, in the embodiment, the design of recording film
3-2 is made so that the wavelength of .lamda.max write exists out
of the range of 355 nm to 455 nm (i.e., at a longer wavelength than
455 nm).
[0137] FIG. 8 shows an example of light absorption spectra in the
"L-H" recording film in the embodiment. As described in "5-1)
Description of feature relating to "L-H" recording film, lower
limit value .beta. of a light reflection factor at a non-recording
portion ("L" section) of the "L-H" recording film is set to 18%,
and upper limit value .gamma. is set to 32% in the embodiment. From
1-0.32=0.68, in order to meet the above condition, it is possible
to intuitively understand that value Al405 of the absorbance in an
unrecorded area at 405 nm should meet:
Al405.gtoreq.68% (36)
[0138] Although the light reflection factor at 405 nm of light
reflection or reflective layer 4-2 is slightly lowered than 100%,
it is assumed that the factor is almost close to 100% for the sake
of simplification. According to this assumption, the light
reflection factor when absorbance Al=0 is almost 100%. In FIG. 8,
the light reflection factor of the whole recording film at the
wavelength of .lamda.max write is designated by R.lamda.max write.
At this time, assuming that the light reflection factor is zero
(R.lamda.max write.apprxeq.0), formula (36) is derived. However, in
actuality, the factor is not set to "0", and thus, it is demanded
to derive a severer formula. A severe conditional formula for
setting the upper light value .gamma. of the light reflection
factor of the non-recording portion ("L" portion) of the "L-H"
recording film to 32% is given by:
1-Al405.times.(1-R.lamda.max write).gtoreq.0.32 (37)
[0139] In a conventional write-once type information storage
medium, only the "H-L" recording film is used, and there is no
accumulation of information relating to the "L-H" recording film.
However, in the case of using the embodiment described in "5-3)
Anion portion: azo metal complex+cation portion: dye", the severest
condition which meets formula (37) is obtained as:
Al405.gtoreq.80% (38)
[0140] In the case of using an organic dye recording material
described later in the embodiment, when an optical design of a
recording film is made including a margin such as a characteristic
variation at the time of manufacture or a thickness change of
recording layer 3-2, it is found that a minimum condition, which
meet the reflection factor described in the section "Description of
feature relating to "L-H" recording film" in the embodiment:
Al405.gtoreq.40% (39)
[0141] may be satisfied. Further, by satisfying either of:
Al355.gtoreq.40% (40)
Al455.gtoreq.40% (41)
[0142] it is possible to ensure stable recording characteristics or
reproduction characteristics even if the wavelength of a light
source is changed in the range of 355 nm to 405 nm or in the range
of 405 nm to 455 nm (in the range of 355 nm to 455 nm when both of
the formulas are met at the same time).
[0143] FIG. 9 shows a light absorption spectrum change after
recorded in the "L-H" recording film according to the embodiment.
It is considered that the value of maximum absorption wavelength
.lamda.Imax in the recording mark deviates from wavelength of
.lamda.max write, and an inter-molecular array change (for example,
an array change between azo metal complexes) occurs. Further, it is
considered that a discoloring action (cutting of local electron
orbit (or local molecular link dissociation)) occurs in parallel to
a fact that both of the absorbance in location of .lamda.lmax and
the absorbance Al405 at 405 nm are lowered and the light absorption
spectra spreads itself.
[0144] In the "L-H" recording film according to the embodiment as
well, by meeting each of formulas (20), (21), (22), and (23), the
same signal processor circuit is made available for both of the
"L-H" recording film and the "H-L" recording film, thereby
promoting simplification and cost reduction of the signal processor
circuit. In formula (20), when:
I11/I11H.ident.(I11H-I11L)/I11H.gtoreq.0.4 (42)
[0145] is modified,
I11H.gtoreq.I11L/0.6 (43)
[0146] is obtained. As described previously, in the embodiment,
lower limit value .beta. of the light reflection factor of an
unrecorded portion ("L" portion) of the "L-H" recording film is set
to 18%, and this value corresponds to I11L. Further, conceptually,
the above value corresponds to:
I11H.apprxeq.1-Ah405.times.(1-R.lamda.max write) (44).
[0147] Thus, from formulas (43) and (44), the following formula is
established:
1-Ah405.times.(1-R.lamda.max write).gtoreq.0.18/0.6 (45)
[0148] When 1-R.lamda.max write.apprxeq.0, formula (45) may be
obtained as:
Ah405.gtoreq.0.7 (46)
[0149] In comparison between the above formulas (46) and (36), it
is found that the values of Al405 and Ah405 may be seemingly set in
the vicinity of 68% to 70% as values of absorbance. Further, in
view of a case in which the value of Al405 is obtained in the range
of formula (39) and performance stability of a signal processor
circuit, a sever condition may be obtained as:
Ah405.gtoreq.0.4 (47)
[0150] If possible, it is advisable to meet;
Ah405.gtoreq.0.3 (48)
[0151] An evaluation disc of recordable dual-layered optical disc
100 according to one embodiment can be made as follows. More
specifically, on transparent resin substrate 101, a 1.2 wt % TFP
solution of an organic dye is applied by spin coating to form L0
recording layer 105. The thickness of the dye after application
from the bottom of the groove is set to be 60 nm. Reflecting film
106 of an Ag alloy with 25 nm thick is laminated or stacked on the
dye-coated substrate by sputtering, and intermediate layer 104 of
2P (photo polymer) resin with 25 pm thickness is spin-coated. A
separately prepared polycarbonate stamper is placed thereon to
transfer the groove shape, and the stamper is removed. On the 2P
resin intermediate layer 104 thus prepared, a 1.2 wt % TFP solution
of an organic dye is applied by spin coating to form L1 recording
layer 107. Reflection or reflective film 108 of an Ag alloy is
laminated or stacked thereon with a thickness of 100 nm by
sputtering, and pasted with 0.59 mm thick transparent resin
substrate 102 by using UV hardening resin 103.
[0152] Using the information storage medium (a single-sided
dual-layer evaluation disc) produced as described above, an
experiment for evaluating a reproduction signal is performed.
[0153] The apparatus used for evaluation is optical disc evaluation
apparatus ODU-1000 manufactured by Pulstec Industrial Co., Ltd.
This apparatus has a laser wavelength of 405 nm and NA of 0.65. The
linear velocity in recording and reproduction is selected to be
6.61 m/s. A recording signal is 8-12 modulated random data, and
information is recorded by using a laser waveform containing a
given recording power and two bias powers 1 and 2 as shown in FIG.
34. The recording conditions applied to the evaluation are as
follows.
[0154] Explanation on Recording Conditions (Information of Write
Strategy)
[0155] Referring to FIG. 34, a description will be given with
respect to a recording waveform (exposure condition at the time of
recording) used when the optimal recording power is checked. The
exposure levels at the time of recording have four levels of
recording power (peak power), bias power 1, bias power 2, and bias
power 3. When long (4T or more) recording mark 9 is formed,
modulation is carried out in the form of multi-pulses between
recording power (peak power) and bias power 3. In the embodiment,
in any of the H format and B format systems, a minimum mark length
relevant to channel bit length T is obtained as 2T. In the case
where the minimum mark of 2T is recorded, one write pulse of the
recording power (peak power) level after bias power 1 is used as
shown in FIG. 34, and bias power 2 is temporarily obtained
immediately after the write pulse. In the case where 3T recording
mark 9 is recorded, bias power 2 is temporarily used after exposing
two write pulses, a first pulse and a last pulse of recording power
(peak power) level that follows bias power 1. In the case where
recording mark 9 having a length of 4T or more is recorded, bias
power 2 is used after the exposure is made with multi-pulse and
write pulse.
[0156] The vertical dashed line in FIG. 34 shows a channel clock
cycle. When a 2T minimum mark is recorded, the laser power is
raised at a position delayed by TSFP from the clock edge, and
fallen at a position delayed by TELP from the one-clock passing
portion. The just-subsequent cycle during which the laser power is
set at bias power 2 is defined as TLC. Values of TSFP, TELP, and
TLC are recorded in physical format information PFI contained in
control data zone CDZ in the case of the H format.
[0157] In the case where a 3T or more long recording mark is
formed, the laser power is risen at a position delayed by TSFP from
the clock edge, and lastly, ended with a last pulse. Immediately
after the last pulse, the laser power is kept at bias power 2
during the period of TLC. Shift times from the clock edge to the
rise/fall timing of the last pulse are defined as TSLP, TELP. In
addition, a shift time from the clock edge to the fall timing of
the last pulse is defined as TEFP, and further, an interval of a
single pulse of the multi-pulse is defined as TMP.
[0158] Each of intervals TELP-TSFP, TMP, TELP-TSLP, and TLC is
defined as a half-value wide relevant to the maximum value. In
addition, in the embodiment, the above parameter setting ranges are
defined as follows:
0.25T.ltoreq.TSFP.ltoreq.1.50T (eq. 01)
0.00T.ltoreq.TELP.ltoreq.1.00T (eq. 02)
1.00T.ltoreq.TEFP.ltoreq.1.75T (eq. 03)
-0.10T.ltoreq.TSLP.ltoreq.<1.00T (eq. 04)
0.00T.ltoreq.TLC.ltoreq.1.00T (eq. 05)
0.15T.ltoreq.TMP.ltoreq.<0.75T (eq. 06)
[0159] Further, in the embodiment, the values of the above
described parameters can be changed or modified according to the
recording mark length (Mark Length) and the immediately
preceding/immediately succeeding space length (Leading/Trailing
space length).
[0160] For the recordable information recording medium whose
recording is to be performed based on the recording theory of the
embodiment, parameters of the optimum recording power are
investigated. The result is that the values of bias power 1, bias
power 2, and bias power 3 are 2.6 mW, 1.7 mW, and 1.7 mW,
respectively, and reproduction power is 0.4 mW.
[0161] Optimum recording conditions (information of Write Strategy)
can be determined with an apparatus (disc drive) by which a test
writing has been done at a drive test zone accoring to the
respective parameter values as mentioned above.
[0162] As data of the recording signal, repetitive patterns of 11T
mark and 11T space are also used. The physical format existing in
the recording layers (L0, L1) on transparent resin substrate 101
and photo polymer resin 104 used in the following examples is
explained with reference to FIGS. 26-34
Example 1
[0163] Optical disc 100 is prepared using a dye corresponding to
the chemical formula of FIG. 4. Information recording is made on
this disc using random data. Error rate SbER of the L0 layer is
measured. The obtained result shows a good value of 5.4 e-6 which
is sufficiently lower that the target value 5.0 e-5 (even though
this value may be a higher hurdle than a practical level). When the
repetitive patterns of 11T mark and 11T space are recorded and
reproduced, almost no waveform distortion is seen. The difference
([I11Lmax-I11Lmin]/I11Lmin) between the maximum and minimum values
of I11L, which is a space level obtained when the 11T space is
reproduced, is 2%. Here, the 11T mark length is sufficiently long
as 1.12 .mu.m, and 1.2*Na/.lamda. is 0.74 .mu.m. Using IR, MS, and
NMR, analyses are made for the dye before recording and after
recording, but no difference is found between the before and after
recordings.
Comparison Example
[0164] An optical disc is prepared using a dye corresponding to the
chemical formula of FIG. 3, and information recording is made
thereon. The resultant error rate SbER of the L0 layer is 6.3 e-4
which is larger than the target value 5.0 e-5. This value may cause
a difficulty in information reading by a disc drive. When the
repetitive patterns of 11T mark and 11T space are recorded and
reproduced, a large waveform distortion is seen, and the difference
([I11Lmax-I11Lmin]/I11Lmin) between the maximum and minimum values
of space level I11L is 14%.
[0165] From the above result and the "Relation between SbER and
Change Amount of I11L" shown in FIG. 23, it is found that a
barometer or an index for reducing the invention to practice may be
based on a selection of dye material which ensures 10% or less of
the difference ([I11Lmax-I11Lmin]/I11Lmin) between the maximum and
minimum values of I11L.
Example 2
[0166] FIG. 10 shows a method of recording rewritable data onto a
rewritable information storage medium. As shown in FIG. 10, in this
embodiment, part of the guard areas 442, 443 are added in front of
and behind one ECC block data 412, thereby constructing data
segment 490. Extended guard fields 258, 259 are added to one or
more (an n number of) data segments, thereby constructing recording
clusters 540, 542, which are recording (re-recording) units or
rewriting units. When recording management data RMD is recorded,
recording management data RMD is added sequentially as recording
clusters 540, 542 including only one data segment (one ECC block)
in recording management zone RMZ. Although not shown, the length of
a place in which one data segment 531 is recorded coincides with
the length of one physical segment block composed of seven physical
segments 550 to 556.
[0167] FIG. 11 is a diagram to explain a data random shift of
rewritable data recorded on a rewritable information storage
medium. As shown in FIG. 11, the part where next VFO area 522 and
extended guard field 528 overlap with each other lies 24 wobbles or
more from the start position of a physical segment. Although not
shown, 16 wobbles from the head of physical segment 550 constitute
wobble sync area 580 and the following 68 wobbles constitute
unmodulated area 590. Therefore, the part where next VFO area 522
and extended guard field 528 overlap with each other from 24
wobbles or more from the head of physical segment 550 is in
unmodulated area 590. As described above, locating the start
position of the data segment 24 wobbles or more from the start
position of the physical segment, not only causes the overlapping
place to lie in unmodulated area 590 but also secures the detection
time for wobble sync area 580 and the preparation time for a
recording process suitably. From this, a stable, high-accuracy
recording process can be assured.
[0168] In the embodiment, the recording film of the rewritable
information storage medium uses a phase-change recording film. In a
phase-change recording film, since the recording film begins to
deteriorate near the rewrite starting and end positions, repeating
the recording start and end in the same position limits the number
of rewrites due to the deterioration of the recording film. In the
embodiment, to alleviate this problem, a shift of (Jm+1/12) data
bytes is made in rewriting as shown in FIG. 11, thereby shifting
the recording start position at random.
[0169] In the diagrams (c) and (d) of FIG. 10, to explain the basic
concept, the start position of extended guard field 528 coincides
with the start position of VFO area 522. Strictly speaking,
however, the start position of VFO area 522 is shifted at random as
shown in FIG. 11 in the embodiment.
[0170] A DVD-RAM disc, an existing rewritable information storage
medium, also uses a phase-change recording film and shifts the
recording start and end positions at random to increase the number
of rewrites. The maximum amount of shift in making a random shift
on an existing DVD-RAM disc is set to eight data bytes. The channel
bit length (of modulated data recorded on the disc) in an existing
DVD-RAM disc is set to 0.143 .mu.m on average. In the rewritable
information storage medium of the embodiment, the average length of
a channel bit is:
(0.087+0.093)/2=0.090 .mu.m (6)
[0171] When the length of the physical shift range is adapted to
the existing DVD-RAM disc, the required minimum length as the
random shift range in the embodiment is calculated using the above
value as follows:
8 bytes.times.(0.143 .mu.m/0.090 .mu.m)=12.7 byte (7)
[0172] In the embodiment, to facilitate the reproduction signal
detecting process, the unit of the amount of random shift is
adapted to a "channel bit" after modulation. In the embodiment,
since ETM modulation (Eight to Twelve modulation) that converts 8
bits into 12 bits is used, the amount of random shift is expressed
using a mathematical formula with a date byte as a reference:
Jm/12 data bytes (8)
[0173] It follows from equation (7) that:
12.7.times.12=152.4 (9)
[0174] Therefore, the values Jm can take are from 0 to 152. For the
above reasons, in the range satisfying equation (9), the length of
the random shift range agrees with the existing DVD-RAM disc, which
assures the same number of rewrites as that of the existing DVD-RAM
disc. In the embodiment, to secure the number of rewrites larger
than that of the existing DVD-RAM disc, a small margin is allowed
for the value of equation (7) as follows:
The length of the random shift range is set to 14 data bytes
(10)
[0175] Substituting the value of equation (10) into equation (8)
gives 14.times.12=168. Therefore, it follows that:
Values Jm can take from 0 to 167 (11)
[0176] As described above, the amount of random shift is set to a
larger range than Jm/12 (0.gtoreq.Jm.gtoreq.154), thereby
satisfying equation (9) and causing the length of the physical
range for the amount of random shift to agree with the existing
DVD-RAM, which produces the effect of assuring the same number of
repeated recordings as that of the existing DVD-RAM.
[0177] In FIG. 10, the length of buffer area 547 and that of VFO
area 532 are constant in recording cluster 540. Amount Jm of random
shift of each of data segments 529, 530 has the same value
throughout the same recording cluster 540. When recording cluster
540 including many data segments is recorded consecutively, the
recording positions are monitored using wobbles. Specifically, the
position of wobble sync area 580 is detected and the number of
wobbles in unmodulated areas 590, 591 are counted, thereby checking
the recording positions on the information storage medium and
recording data at the same time. At this time, there may be rare
occasions when a wobble slip (recording done in a position shifted
by one wobble period) will occur due to the miscounting of wobbles
or uneven rotation of the rotating motor (e.g., a spindle motor;
not shown) that rotates the information storage medium and
therefore the recording position will shift on the information
storage medium. The information storage medium of the embodiment is
characterized in that, if a shift in the recoding position has been
detected, adjustment is made in rewritable guard area 461 of FIG.
10 or in recordable guard area 452 (not shown here), thereby
correcting the recording timing. In FIG. 10, important information
that permits neither the omission of bits nor the redundancy of
bits is recorded in postamble area 546, extra area 544, and
pre-sync area 533. However, in buffer area 547 and VFO area 532, a
specific pattern is repeated. Then, the omission and/or redundancy
of only one pattern may be permitted, as long as the repeated
boundary positions are secured. Therefore, in guard area 461,
particularly in buffer area 547 or VFO area 532, adjustment is made
to correct the recording timing according to the embodiment.
[0178] In this embodiment, as shown in FIG. 11, the actual start
point position serving as a reference of position setting is set so
as to coincide with the position of the wobble amplitude "0" (the
center of wobble). However, since the wobble position detecting
accuracy is low, the embodiment, as written as ".+-.1 max" in FIG.
11, permits the actual start point position to have up to
a shift of .+-.1 data byte (12)
[0179] In FIGS. 10 and 11, the amount of random shift in data
segment 530 is set to Jm (as described above, the amount of random
shift is the same in all of data segments 529 in recording cluster
540). Thereafter, the amount of random shift in data segment 531 in
which additional recording is done is set to Jm+1. A value Jm in
equation (11) and Jm+1 can take is, for example, the intermediate
value: Jm=Jm+1=84. When the position accuracy of the actual start
point is sufficiently high, the starting position of extended guard
field 528 coincides with the starting position of VFO area 522 as
shown in FIG. 10.
[0180] In contrast, when data segment 530 is recorded in the
rearmost position and data segment 531 to be rewritten or
additionally recorded later is recorded in the very front position,
the start position of VFO area 522 may go into buffer area 537 by
up to 15 data bytes because of equations (10) and (12). In extra
area 534 just in front of buffer area 537, specific important
information is recorded. Therefore, in the embodiment, the
following is to be met:
the length of buffer area 537 has to be 15 data bytes or more
(13)
[0181] In the embodiment of FIG. 10, a margin of 1 data byte is
added, and the data size of buffer area 537 is set to 16 data
bytes.
[0182] If a gap occurs between extended guard area 528 and VFO area
522 as a result of a random shift, when a single-sided
dual-recording-layer structure is used, interlayer crosstalk is
caused by the gap during reproduction. To overcome this problem,
extended guard field 528 and VFO area 522 are caused to always
partially overlap with each other even when a random shift is made,
thereby preventing a gap from occurring. Therefore, in the
embodiment, from equation (13), the length of extended guard field
528 is to be set to 15 data bytes or more. Since subsequent VFO 522
is made as long as 71 data bytes, even if the overlapping area of
extended guard field 528 and VFO area 522 becomes a little wider,
this has no adverse effect in reproducing a signal (because the
time demanded to synchronize the reproduction reference clock in
unoverlapped VFO area 522 is secured sufficiently). For this
reason, extended guard field 528 can be set to a larger value than
15 data bytes. As explained above, there may be occasions when a
wobble slip will occur in continuous recording and the recording
position will shift by one wobble period. As seen from equation
(5), a wobble period corresponds to 7.75 (about 8) data bytes.
Thus, taking this into account, equation (13) is modified as
follows in the embodiment:
The length of extended guard field 528 is set to (15+8)=23 data
bytes or more (14)
[0183] In the embodiment of FIG. 10, a margin of one data byte is
given as in buffer area 537 and the length of extended guard field
528 is set to 24 data bytes.
[0184] In the diagram (e) of FIG. 10, the recording start position
of recording cluster 541 has to be set accurately. The information
recording and reproducing apparatus of the embodiment detects the
recording start position by using the wobble signal previously
recorded on a rewritable or a recordable information storage
medium. All of the areas excluding the wobble sync area 580 are
changed in pattern from NPW to IPW in units of 4 wobbles. In
contrast, in wobble sync area 580, since the wobble switching unit
partially shifts from 4 wobbles, wobble sync area 580 is easiest to
detect. Therefore, the information recording and reproducing
apparatus of the embodiment detects the position of wobble sync
area 580 and then prepares for a recording process and starts
recording. Thus, the starting position of the recording cluster has
to lie in unmodulated area 590 just behind the wobble sync area
580. FIG. 11 shows its contents. Wobble sync area 580 is provided
immediately after the switching of physical segments. The length of
wobble sync area 580 is equivalent to 16 wobble periods. After
wobble sync area 580 is detected, 8 wobble periods are provided,
allowing a margin for preparation for a recording process. Thus, as
shown in FIG. 11, the start position of VFO area 522 existing at
the start position of recording cluster 541 has to be placed 24
wobbles or more behind a physical segment switching position, even
taking random shift into account.
[0185] As shown in FIG. 10, a recording process is carried out many
times in overlapping place 541 in rewriting. When rewriting is
repeated, the physical shape of a wobble groove or a wobble land
changes or deformed (or deteriorates), resulting in a decrease in
the quality of the wobble reproduction signal. In the embodiment,
as shown in the diagram (f) of FIG. 10, overlapping place 541 is
prevented from lying in wobble sync area 580 or wobble address area
586 in rewriting or additional recording and then is recorded in
unmodulated area 590. Since a specific wobble pattern (NPW) is just
repeated in unmodulated area 590, even if the quality of the wobble
reproduction signal has partially deteriorated, the signal can be
supplemented or interpolated with the preceding and following
wobble reproduction signals. As described above, setting is done so
that the position of overlapping place 541 may lie in unmodulated
area 590 in rewriting or additional recording, making it possible
to prevent the quality of the wobble reproduction signal from
deteriorating due to the deterioration of the shape in wobble sync
area 580 or wobble address area 586, which produces the effect of
assuring a stable wobble detection signal from wobble address
information 610.
[0186] FIG. 12 is a diagram to explain a method for recording
additional data onto a recordable information storage medium. Since
recording is done only once on a recordable information storage
medium, the above-described random shift is not needed. In a
recordable information storage medium, too, as shown in FIG. 11,
setting is done so that the start position of a data segment may
lie 24 wobbles or more from the start position of a physical
segment. Then, an overlapping place lies in the unmodulated area of
a wobble.
[0187] Use of both of a "H-L" (High-to-Low) recording film and a
"L-H" (Low-to-High) recording film is permitted in the embodiment.
FIG. 13 shows the reflectivity ranges of a "H-L" recording film and
a "L-H" recording film determined in the embodiment. This
embodiment is characterized in that the lower limit of reflectivity
at an unrecorded part of the "H-L" recording film is set higher
than the upper limit of reflectivity at an unrecorded part of the
"L-H" recording film. When the information storage medium is
installed in the information recording and reproducing apparatus or
information reproducing apparatus, slice level detecting section
132 or PR equalizing circuit 130 (not shown) can measure the
reflectivity of an unrecorded part and determine whether the film
is a "H-L" recording film or a "L-H" recording film, which makes it
very easy to determine the type of recording film. As a result of
forming and measuring "H-L" recording films and "L-H" recording
films by changing many manufacturing conditions, it is found that,
when the reflectivity a between the lower limit of reflectivity at
an unrecorded part of the "H-L" recording film and the upper limit
of reflectivity at an unrecorded part of the "L-H" recording film
is set to 36%, the productivity of the recording film is high and
the cost of the recording medium is easy to reduce. When
reflectivity range 801 of an unrecorded part ("L" part) of the
"L-H" recording film is caused to coincide with reflectivity range
803 of the single-sided dual-layer of a read-only information
storage medium and reflectivity range 802 of an unrecorded part
("H" part) of the "H-L" recording film is caused to coincide with
reflectivity range 804 of the single-sided single layer of a
read-only information storage medium, the interchangeability or
compatibility with the read-only information storage medium and a
recordable information storage medium is good and the reproducing
circuit of a reproduction-only apparatus and that of an information
recording and reproducing apparatus can be shared, which enables
the information reproducing apparatus to be produced at low cost.
As a result of forming and measuring "H-L" recording films and
"L-H" recording films by changing many manufacturing conditions, to
increase the productivity of the recording film and make it easier
to reduce the cost of the recording medium, the lower limit .beta.
of the reflectivity of an unrecorded part ("L" part) of the "L-H"
recording film is set to 18%, its upper limit .gamma. is set to
32%, the lower limit .delta. of the reflectivity of an unrecorded
part ("H" part) of the "H-L" recording film is set to 40%, and its
upper limit .epsilon. is set to 70% in this embodiment.
[0188] FIG. 13 shows the reflectivity ranges of a "H-L" recording
film and a "L-H" recording film. When the reflectivity range at an
unrecorded portion is determined as shown in FIG. 13, a signal
appears in the same direction in emboss areas (including system
lead-in SYLDI, etc.) and in recording mark areas (data lead-in/-out
DTLDI, DTLDO and/or data area DTA) in the "L-H" recording film,
with the groove level as a reference. Similarly, a signal appears
in the opposite direction in emboss areas (including system lead-in
SYLDI, etc.) and in recording mark areas (data lead-in/-out DTLDI,
DTLDO and/or data area DTA) in the "H-L" recording film, with the
groove level as a reference. Use of this phenomenon not only helps
identify whether the recording film is a "L-H" recording film or a
"H-L" recording film but also makes it easier to design a detecting
circuit compatible with both of a "L-H" recording film and a "H-L"
recording film.
[0189] FIG. 14 shows a detailed structure of an ECC block after PO
interleaving. As shown in FIG. 14, in this embodiment, to create
one ECC block using 64 KB of data, the data size of recording
management data RMD is made equal to one ECC block size, thereby
simplifying the additional recording process.
[0190] The embodiment is characterized in that the same data frame
is distributed over a plurality of small ECC blocks. Specifically,
in the embodiment, two small ECC blocks constitute a large ECC
block. The same data frame is distributed over the two small ECC
blocks alternately. PI of a 10-byte size written in the middle is
added to 172 bytes provided on its right side and PI of a 10-byte
size written at the right end is added to 172 bytes provided on its
left side and in the middle. That is, 172 bytes from the left end
and PI of consecutive 10 bytes constitute a left small ECC block
and 172 bytes in the middle and PI of 10 bytes at the right end
constitute a right small ECC block.
[0191] According to this, the symbols in each frame are set. For
example, "2-R" indicates which of data frame number and right and
left small blocks it belongs to (e.g., it belongs to the right
small ECC block in the second data frame). In addition, the data in
the same physical sector is also distributed over the right and
left small ECC blocks alternately in each physical sector finally
configured. Here, the left-half column is included in the left
small ECC block (the left small ECC block A shown in FIG. 14) and
the right-half column is included in the right small ECC block (the
right small ECC block B shown in FIG. 14).
[0192] As described above, distributing the same data frame over a
plurality of small ECC blocks improves the error correcting
capability of the data in the physical sector, which increases the
reliability of the recorded data. For example, suppose the optical
head has come off the track and overwritten the recorded data, with
the result that one physical sector of data has been destroyed. In
this embodiment, since destructed data of one sector is subjected
to error correction using two small ECC blocks, the burden of
correcting errors in one ECC block is alleviated, which assures
higher-performance error correction. Moreover, in the embodiment,
since data ID is provided at the start position of each sector even
after an ECC block is formed, the data position in access is
checked at high speed.
[0193] FIG. 15 shows a data structure of recording management data
RMD. In this embodiment, since the border-in area BRDI for the
first bordered area BRDA#1 is partly shared with the data lead-in
area DTLDI, recording management data RMD#1 to RMD#3 corresponding
to the first bordered area are recorded in the recording management
zone RMZ in the data lead-in area DTLDI. When no data is recorded
in the data area DTA, the recording management zone RMZ is reserved
area 273, which is an unrecorded state. Each time data is recorded
additionally into the data area DTA, updated recording management
data RMD is recorded in the beginning place of reserved area 273.
Recording management data RMD corresponding to the first bordered
area in recording management zone RMZ is added one after another.
The size of recording management data RMD recorded additionally
each time in the recording management zone RMZ is set to 64
Kbytes.
[0194] The diagram (c) of FIG. 15 shows a data structure of
recording management data RMD#1. In the diagram (c) of FIG. 15, the
data structure of recording management data RMD#1 in the data
lead-in area DTLDI is shown. Recording management data RMD#A, RMD#B
recorded in the RMD duplication zone RDZ, (extended) recording
management data RMD (the diagram (d) of FIG. 16) recorded in
border-in area BRDI explained later, (extended) recording
management data RMD recorded in the R zone, and/or RMD copy CRMD
(the diagram (d) of FIG. 16) recorded in the border-out area BRDO
may also have the same structure. As shown in the diagram (c) of
FIG. 15, an item of recording management data RMD is configured to
include a reserved area and "0" to "21" RMD fields. In the
embodiment, one ECC block composed of 64 KB of user data contains
32 physical sectors. In one physical sector, 2 KB (to be exact,
2048 bytes) of user data are recorded. According to the user data
size recorded in one physical sector, the individual RMD fields are
divided in units of 2048 bytes and are assigned with relative
physical sector numbers. RMD fields are recorded on a recordable
information storage medium in the order of the relative physical
sector numbers. The outline of data content recorded in each RMD
field is as follows:
[0195] RMD field 0 . . . Information on the disc state and data
area allocation (information on the location of various data in the
data area);
[0196] RMD field 1 . . . Information on the test zone used and
recommended recording waveforms;
[0197] RMD field 2 . . . Area available to the user;
[0198] RMD field 3 . . . Information on the starting position of
the border area and the position of extended RMZ; and
[0199] RMD fields 4 to 21 . . . Information on the position of R
zone.
[0200] Incidentally, in a recordable (or re-recordable) information
storage medium, an RMD duplication zone RDZ, a recording management
zone RMZ, an R physical information zone R-FIZ are provided
separately. In the recording management zone RMZ, recording
management data RMD, which is management information on the
recording position of data updated by an additional recording
process of data, is recorded. In this embodiment, a recording
management zone RMZ is set in each bordered area BRDA, which
enables the area of the recording management zone RMZ to be
extended. Even if the frequency of additional recording is
increased and therefore the recording management data RMD area is
to be increases, the recording management data RMD can be recorded
by extending the recording management zone RMZ. As a result, the
effect of increasing the number of times of additional recording
remarkably is obtained. In this case, in the embodiment, the
recording management zone RMZ is provided in the border-in area
BRDI corresponding to each bordered area BRDA (or provided just in
front of each bordered area BRDA). In the embodiment, the border-in
area BRDI corresponding to the first bordered area BRDA#1 and the
data lead-in area DTLDI share an area, eliminating the formation of
the first border-in area BRDI in the data area DTA, which enables
the data area DTA to be used effectively. That is, the recording
management zone RMD in the data lead-in area DTLDI is used as the
recording place of the recording management data RMD corresponding
to the first bordered area BRDA#1.
[0201] An RMD duplication zone RDZ is a place in which recording
management data RMD satisfying the following condition is recorded.
As in the embodiment, having the recording management data RMD
redundantly increases the reliability of the recording management
data RMD. Specifically, even when the recording management data RMD
in the recording management zone RMD cannot be read because of the
influence of dust on and/or flaws or scratches in the surface of a
recordable information storage medium, the recording management
data RMD recorded in the RMD duplication zone RDZ may be reproduced
and further the remaining demanded information may be acquired by
tracing, which enables the latest recording management data RMD to
be reproduced or recovered.
[0202] In the RMD duplication zone RDZ, the recording management
data RMD at the time of closing a border (or a plurality of
borders) is recorded. Since one border is closed and a new
recording management zone RMZ is defined each time a subsequent new
bordered area is set, it may be said that, each time a new
recording management zone RMZ is created, the last recording
management data RMD related to the preceding bordered area is
recorded in the RMD duplication zone RDZ. If the same information
is recorded in the RMD duplication zone RDZ each time the recording
management data RMD is additionally recorded on the recordable
information storage medium, the RMD duplication zone RMD is filled
up with a relatively small number of times of additional recording,
with the result that the upper limit of the number of times of
additional recording is small. In contrast, as in the embodiment,
if a new recording management zone RMZ is created when a border is
closed or when the recording management zone RMZ in the border-in
area BRDI has got full and a new recording management zone RMZ is
created using an R zone, only the last recording management data
RMD in the current recording management zone RMZ is recorded in the
RMD duplication zone RDZ, which enables the RMD duplication zone
RDZ to be used effectively and increases the number of times of
additional recording.
[0203] For instance, when the recording management data RMD in the
recording management zone RMZ corresponding to the bordered area
BRDA in the middle of additional recording (before border closing
is done) cannot be reproduced due to dust on or flaws/scratches in
the surface of the recordable information storage medium, the
recording management data RMD recorded at the end of the RMD
duplication zone RDZ, which enables the position of the already
closed bordered area to be known, is reproduced. Therefore, tracing
the remaining part of the data area DTA of the information storage
medium makes it possible to acquire the place of the bordered area
BRDA in the middle of additional recording (before border closing
is done) and the contents of the information recorded there, which
enables the latest recording management data RMD to be reproduced
or recovered.
[0204] FIG. 16 is an exemplary view for explaining the structure of
the border area in a recordable or re-recordable information
storage medium. This embodiment is characterized in that each of
the size of the area of RDZ lead-in area RDZLI and the size of an
item of the recording management data RMD is 64 KB, that is, an
integral multiple of the user data size in a single ECC block. In
the case of a recordable or re-recordable information storage
medium, after a part of the data in one ECC block are changed, the
changed data in the ECC block cannot be rewritten on the
information storage medium. Therefore, particularly in the case of
the recordable or re-recordable information storage medium, the
data is recorded in units of a recording cluster (b) composed of an
integral multiple of a data segment including one ECC block. Thus,
if the size of the area of RDZ lead-in area RDZLI and the size of
one item of the recording management data RMD differ from the user
data size in the ECC block, a padding area or a stuffing area to
match with the recording cluster unit is demanded, which
practically lowers the recording efficiency. In the embodiment, the
size of the area of RDZ lead-in area RDZLI and the size of one item
of the recording management data RMD are set to an integral
multiple of 64 KB, thereby preventing the recording efficiency from
decreasing.
[0205] The corresponding RMZ last recording management data RMD
recording area 271 will be explained. There is a method of
recording intermediate information during the interruption of
recording in the lead-in area. In this case, each time recording is
interrupted or each time additional recording is done, intermediate
information (in the embodiment, recording management data RMD) has
to be additionally recording one after another. Therefore, if
recording is interrupted frequently or if additional recording is
done frequently, a problem arises: the area is soon filled and
therefore, an additional recording cannot be done. To solve this
problem, the present invention is characterized in that an RMD
duplication zone RDZ is set as an area in which the updated
recording management data RMD can be recorded only when special
conditions are fulfilled and the recording management data RMD
sampled out or decimated under the special conditions are recorded.
In this way, the frequency of addition of recording management data
RMD to the RMD duplication zone RDZ is lowered, which prevents the
RMD duplication zone RDZ from being filled-up and increases the
number of times of additional recording into the recordable
information storage medium remarkably.
[0206] In parallel with this, recording management data RMD updated
every additional recording is recorded additionally into the
recording management zone RMZ in the border-in area BRDI of FIG. 16
(or into the data lead-in area DTLI in the first bordered area
BRDA#1) or into the recording management zone using an R zone.
Then, when a new recording management zone RMZ is created, such as
when the next area BRDA in the border is created (or a new
border-in BRDI is set) or a new recording management zone RMZ is
created in the R zone, the last recording management data RMD (or
the latest one immediately before a new recording management zone
RMZ is formed) is recorded in (the corresponding RMZ last recording
management data RMD recording area 271 in) the RMD duplication zone
RDZ. As a result, the number of times of additional recording into
a recordable information storage medium increases remarkably. Use
of this area makes it easier to search for the position of the
latest RMD.
[0207] FIG. 17 shows a comparison between the embodiment and a
current DVD-R. FIG. 17 compares the embodiment with the current
DVD-R. In this embodiment, to shorten the border closing time, the
recording width of the minimum recording capacity (in border
closing) is made narrower (from 1.65 mm to 1.0 mm) than that of a
current DVD-R. As a result, useless recording information is
reduced and finalize time can be made shorter. Since the recoding
capacity of this embodiment is much larger (4.7 GB to 15 GB) than
that of the current DVD-R, the maximum number of R zones is almost
doubled (2302 to 4606). While the recording unit of the existing
DVD-R is one ECC block, the recording unit of the embodiment is one
physical segment. In a physical segment block, redundant areas,
including a VFO area, a pre-sync area, a postamble area, an extra
area, and a buffer area, are added in front of and behind an ECC
block, thereby forming a data segment 531. These data segments are
combined to form a physical segment, a unit in data recoding.
[0208] Since redundant areas (guard areas) are added in front of
and behind one ECC block, data cannot be recorded continuously from
the end of the ECC block at the time of additional recording. The
reason is that, even if an attempt is made to record data from the
end of the ECC block, the recoding position may shift slightly due
to rotation irregularity of the disc or the like. If the recording
position shifts forward, the last part of the recorded data
disappears due to overwriting. Since the lost data can be
reproduced by error correction, there is almost no problem. If the
recording position shifts backward, an unrecorded part appears on
the disc, resulting in preventing the reproduction by a player,
which is a serious problem. Therefore, at present, when additional
recording is to be done, the recording position is shifted slightly
forward and data is written over the last part of the recorded
data, thereby destroying the last data. In this embodiment, since a
guard area is provided in front of and behind an ECC block,
overwriting is done in the guard area and therefore the user data
can be additionally recorded stably without destroying the data.
Accordingly, the data structure of the embodiment can increase the
reliability of the recorded data.
[0209] When border closing is done, the unrecorded part of first
and second R zones (open R zone) (the zones are called first,
second, and third zones, starting from the inner periphery) is
filled with "00h and border-out area is recorded outside the
recorded data in the third zone (incomplete R zone). Border-in area
is recorded outside the border-out area. In the border-in area,
extended recording management zone EX.RMZ is recorded. As shown in
FIG. 17, recording management data RMD can be updated 392 or more
times (16384 times) using the extended recording management zone
EX.RMZ in the border-in area. However, before extended recording
management zone EX.RMZ in the border-in area is used, the border
has to be closed, which takes time.
[0210] FIG. 18 is a flowchart for explaining the processing
procedure immediately after an information storage medium is
installed in an information reproducing apparatus or information
recording and reproducing apparatus. When the disc is installed in
or loaded into the apparatus, burst cutting area BCA is reproduced
(ST22). This embodiment supports an HD DVD-R disc. It further
supports both of the recording film polarities, "L-H" (Low to High)
and "H-L" (High to Low). In ST24, the system lead-in area is
reproduced. In ST26, RMD duplication RDZ is reproduced. In the case
of a nonblank disc, recording management data RMD has been recorded
in RMD duplication zone RDZ. According to the presence or absence
of the recording of recording management data RMD, it is determined
in ST28 whether the disc is a blank one. If the disc is a blank one
(yes at ST28), the present process is ended. If the disc is not a
blank disc (no at ST28), the latest recording management data RMD
is searched for (ST30). Then, the number of the additionally
recordable R zone now in use, the start physical segment number of
the R zone, and the last recorded address LRA are found. Up to
three additionally recordable R zones can be set. When a nonblank
disc is discharged or unloaded, border closing or finalizing is
done.
[0211] FIG. 19 is a flowchart for explaining a method of recording
additional information onto a recordable information storage medium
in the information recording and reproducing apparatus. When a host
gives a record instruction (write (10)), it is determined in ST32
whether the remaining amount of recording management zone RMZ in
which recording management data RMD is to be recorded is
sufficient. If the remaining amount is not sufficient (no at ST32),
the host is informed in ST34 that "the remaining amount of RMZ is
small". In this case, an extension of recording management zone RMZ
is expected.
[0212] If the remaining amount is sufficient (yes at ST32), it is
determined in ST36 whether OPC (the process of recording how much
test recording has been done) is demanded. If OPC is demanded (yes
at ST36), OPC is executed in ST38. In ST40, it is determined
whether the update of recording management data RMD is demanded.
The update is demanded when (yes at ST40) a record instruction is
given immediately after the reservation of an R zone or when the
difference between the last writable address NWA in the latest RMD
and the actual last writable address NWA is 16 MB or more. In ST42,
recording management data RMD is updated. In ST44, the data is
recorded. In ST46, the host is informed of the recording end and
the process is completed.
[0213] FIG. 20 is a diagram for explaining the concept of a setting
method of extendable recording management zone RMZ. At the
beginning, recording management zone RMZ for storing recording
management data RMD has been set in the data lead-in area. When
recording management zone RMZ is used up, the data cannot be
recorded onto the disc even if the data area includes an empty
portion. Therefore, if the remaining amount of recording management
zone RMZ becomes small, extended recording management zone EX.RMZ
is set. Extended recording management zone EX.RMZ may be set in a
bordered area BRDA in which user data is recorded or in a border
zone (made up of adjacent border-out area and border-in area). That
is, the extended recording management zone EX.RMZ in the bordered
area and the extended recording management zone EX.RMZ in the
border-in area can be mixed on the disc. When extended recording
management zone EX.RMZ is set, the latest recording management data
RMD is copied into RMD duplication zone RDZ in the form of a
physical segment block. RMD duplication zone RDZ is used to manage
the position of extended recording management zone EX.RMZ. Since
the RMD duplication zone RDZ is composed of 128 physical segments,
recording management zone RMZ can be extended 127 times on the
disc. The maximum number of border zones on the disc is 128. Using
127 extended recording management zones EX.RMZ, recording
management data RMD can be extended 16348 times.
[0214] FIG. 21 is a detailed diagram of FIG. 20. Specifically,
extended recording management zone EX.RMZ in the bordered area is
set between adjacent R zones. When it is extended to the border
zone, it is normally added to the end of the border-in area.
[0215] An information recording medium based on the above-mentioned
format is prepared, and information recording of random data is
performed. The result is that the jitter of L0 is 6.2% which is a
very good performance. When the repetitive patterns of 7T marks and
7T space are recorded and reproduced, the waveform distortion is
very low and the difference ([I11Lmax-I11Lmin]/I11Lmin) between the
maximum and minimum values of I11L (which is the space level of a
reproduction signal) is 3%. When the difference is equal to or less
than 10%, the error rate (SbER) becomes not more than 1.0 e-04 as
will be seen from FIG. 23, resulting in ensuring a sufficient
practicability. Further, when the recording layer uses an organic
dye material with which the physical deformation (change in the
volume or change in the surface condition between the mark and its
peripheral) at the recorded mark portion is equal to or less than
10%, as exemplified by FIG. 22, the error rate (SbER) becomes equal
to or less than 1.0 e-04, thereby confirming the actual
practicability.
[0216] FIG. 24 is an exemplary flowchart explaining a recording
method using optical disc 100 according to one embodiment of the
invention. (This disc uses an organic dye material for the
recording layer by which no modification or no change will occur in
recorded marks.) An optical pickup of a disc drive (not shown)
generates or provides a modulated laser with a wavelength of, e.g.,
405 nm. This laser is irradiated to the target recording layer (L0
or L1) of disc 100, so that object data (such as VOB of DVD or
VOB/SOB of HD_DVD) is recorded thereon (ST100). When the recording
is ended (yes at ST102), management information (such as VMG of DVD
or HD_DVD) regarding the recorded object data is written in disc
100, to thereby complete one recording.
[0217] FIG. 25 is an exemplary flowchart explaining a reproducing
method using optical disc 100 according to one embodiment of the
invention. (This disc uses an organic dye material for the
recording layer by which no modification or no change will occur in
recorded marks.) From disc 100 on which object data and management
information are recorded according to the method of FIG. 24, the
management information is read using a laser with a wavelength of,
e.g., 405 nm (ST200). The read management information is
temporarily stored in a work memory of a reproduction apparatus (or
a player; not shown). In the reproduction apparatus, reproduction
sequence information or the like is referred to and the recorded
object data (video object VOB or stream object SOB) is reproduced
or played back (ST202). When a user stops the reproduction, or when
the reproduction reaches the position indicated as a reproduction
end by reproduction sequence information in the management
information (yes at ST204), the reproduction process ends.
[0218] FIG. 26 is an exemplary view showing a physical sector
layout of optical disc 100 shown in FIG. 1. As exemplified in FIG.
26, the information area provided throughout the dual layers
includes seven areas: the System Lead-in area, Connection area,
Data Lead-in area, Data area, Data Lead-out area, System Lead-out
area, and Middle area. The Middle area on each layer allows the
read-out beam to move from Layer 0 (L0) to Layer 1 (L1). Data area
DA is intended for recording of the main data (such as management
information VMG, object data VOB, etc. in the example of FIG.
1(e)). System Lead-in area SLA contains the Control data and
Reference code. The Data Lead-out area allows for a continuous
smooth read-out.
[0219] <<Lead-out Area>>
[0220] The System Lead-in area and System Lead-out area contain
tracks which consist of a series of embossed pits. The Data Lead-in
area, Data area and Middle area on Layer 0 (L0), and the Middle
area, Data area and Data Lead-out area on Layer 1 (L1) include a
series of groove tracks. The groove tracks are continuous from the
start of the Data Lead-in area to the end of the Middle area on
Layer 0 and from the start of the Middle area to the end of the
Data Lead-out area on Layer 1. When two single-sided dual-layer
discs are pasted on each other, a double-sided quadruplex-layer
disc having two read-out surfaces is manufactured.
[0221] FIG. 27 is an exemplary view showing a configuration of the
lead-in area of the optical disc shown in FIG. 1. As exemplified in
FIG. 27, system lead-in area SLA of Layer 0 is composed of an
initial zone, a buffer zone, a control data zone, and a buffer zone
in sequence from the inner peripheral side. The data lead-in area
of Layer 0 is composed of a blank zone, a guard track zone, a drive
test zone, a disc test zone, a blank zone, an RMD duplication zone,
an L-RMD (recording management zone in the Data Lead-in area), an
R-physical format information zone, and a reference code zone in
sequence from the inner peripheral side. A starting address (inner
peripheral side) of the data area of Layer 0 (L0) and an ending
address (inner peripheral side) of the data area of Layer 1 (L1)
are shifted by a distance of a clearance, and the ending address
(inner peripheral side) of the data area of Layer 1 is at a side
outer than the starting address (inner peripheral side) of the data
area of Layer 0.
[0222] <<Structure of Lead-in Area>>
[0223] FIG. 27 exemplifies a configuration of the lead-in area of
Layer 0 (L0). The system lead-in area is composed of an initial
zone, a buffer zone, a control data zone, and a buffer zone in
sequence from the inner peripheral side. The data lead-in area is
composed of a blank zone, a guard track zone, a drive test zone, a
disc test zone, a blank zone, an RMD duplication zone, a recording
management zone in the data lead-in area (L-RMD), an R-physical
format information zone, and the reference code zone in sequence
from the inner peripheral side.
[0224] <<Details of System Lead-in Area>>
[0225] The initial zone contains embossed data segments. The main
data of the data frame recorded as the data segment of the initial
zone is set to "00h". The buffer zone is formed of 1024 Physical
sectors from 32 Data segments. The Main data of the Data frames
eventually recorded as Data segments in this zone is set to "00h".
The Control data zone contains embossed Data segments. The Data
segments contain embossed Control data. The Control data is
comprised of 192 Data segments starting from PSN 123904 (01
E400h).
[0226] FIG. 28 exemplifies a configuration of the control data
zone, and FIG. 29 exemplifies a structure of the data segment of
the control data section. The contents of the first Data segment in
a Control data section is repeated 16 times. The first Physical
sector in each Data segment contains the physical format
information. The second Physical sector in each Data segment
contains the disc manufacturing information. The third Physical
sector in each Data segment contains the copyright protection
information. The contents of the other Physical sectors in each
Data segment are reserved for system use.
[0227] FIG. 30 exemplifies the physical format information in the
control data section, and FIG. 31 exemplifies the data area
allocation of the physical format information. The contents of
description of respective bite positions (BP) for the physical
format information are as follows. The values specified for the
Read power, Recording speeds, Reflectivity of Data area, Push-pull
signal, and On-track signal given in BP 132-154 are only for
example. Their actual values may be determined by a disc
manufacture provided that the values are chosen within the values
satisfying the emboss condition and the recorded user data
characteristics. The details of the data area allocation given in
BP 4-15 are shown in FIG. 31, for example.
[0228] BP149 and BP152 specify reflectance ratios of the data areas
of Layer 0 and Layer 1. For example, 0000 1010b denotes 5%. An
actual reflectance ratio can be specified by the following
formula:
Actual reflectance ratio=value.times.(1/2).
[0229] BP150 and BP153 specify push-pull signals of Layer 0 and
Layer 1. In respective BP's, bit b7 (not shown) specifies a track
shape of the disc of each layer, and bits b6 to b0 (not shown)
specify amplitudes of the push-pull signals as:
[0230] Track shape: 0b (track on a groove) [0231] 1b (track on a
land)
[0232] Push-pull signal: 010 1000b denotes 0.40, for example.
[0233] An actual amplitude of a push-pull signal is specified by
the following formula:
Actual amplitude of push-pull signal=value.times.(1/100).
[0234] BP151 and BP154 specify amplitudes of on-track signals of
Layer 0 and Layer 1:
[0235] On-track signal: 0100 0110b denotes 0.70, for example.
[0236] An actual amplitude of an on-track signal is specified by
the following formula:
Actual amplitude of on-track signal=value.times.(1/100).
[0237] Incidentally, recording-related parameters for L0 as
exemplified by FIG. 32 may be described at BP512 to BP543 of the
physical format information. Information of the initial peak power
and/or bias power, etc. for the L0 layer recording can be obtained
from the description of FIG. 32. Further, recording-related
parameters for L1 as exemplified by FIG. 33 may be described at
BP544 to BP2047 of the physical format information. Information of
the initial peak power and/or bias power, etc. for the L1 layer
recording can be obtained from the description of FIG. 33.
[0238] <Summary>
[0239] (1) The optical disc according to the embodiment has a
recording layer (L0, L1, etc.) on which a plurality of marks are
recorded with spaces sandwiched between the marks, using a
modulated laser power. The recording layer uses an organic dye
material (cf. FIGS. 2 to 4) with which no physical modification or
change (changes in the volume or in the sectional area) occurs
substantially in the recording layer at the recorded mark area (for
instance, the modification or change is equal to or less than
10%).
[0240] (2) The condition that no physical modification or change
occurs substantially in the recording layer corresponds to a fact
that a change in the volume of the recording layer at the mark area
is equal to or less than 10% (cf. FIG. 22, etc.).
[0241] (3) Or, the condition that no physical modification or
change occurs substantially in the recording layer may correspond
to a fact that a change in the surface condition or in the
sectional area of the recording layer at the mark area is equal to
or less than 10% (cf. FIG. 22, etc.).
[0242] (4) An organic dye material (e.g., the dye of FIG. 4) in
which no chemical change occurs when the mark is recorded may be
used for the recording layer.
[0243] (5) At least a part of the organic dye material to be used
for the recording layer may include an azo metal complex (cf. FIGS.
2 to 4) comprising copper (Cu) or cobalt (Co) as its center
metal.
[0244] (6) The organic dye material (such as azo metal complex) may
include a substituent (as a bulky substituent) comprising three or
more carbons being substituted for the aromatic ring in the dye
molecule.
[0245] (7) Assume that the recording laser wavelength is
represented by .lamda., the numerical aperture of an objective lens
for condensing the laser to the recording layer is represented by
NA, the length of recorded patterns of marks and space is larger
than 1.2*.lamda./NA, the maximum value of the reproduction signal
level from the space is denoted by I11Lmax, and the minimum value
thereof is denoted by I11Lmin. Under this assumption, the
difference ([I11Lmax-I11Lmin]/I11Lmin) between the maximum and
minimum values of the reproduction signal level from the space may
be configured to be equal to or less than 10% (cf. FIG. 23).
[0246] (8) A recording method may be applied to an optical disc
having one or more recording layers (L00, L1, etc.) on which marks
are to be recorded with a space formed therebetween, wherein the
one or more recording layers may include an organic dye material
configured to substantially avoid a physical modification
(deformation) or a physical change in an area of the recorded mark.
The recording method may comprise:
[0247] recording (ST100) object data (video object VOB or stream
object SOB) on the recording layer using a modulated laser power;
and recording (ST104) management information (VMG) for managing the
recorded object data on the recording layer using a modulated laser
power.
[0248] (9) In the recording method, when a wavelength of the laser
for recording is represented by .lamda., a numerical aperture of an
objective lens for condensing the laser to the recording layer is
represented by NA, and a length of recorded patterns of the marks
and the space is larger than 1.2*.lamda./NA, a difference
([I11Lmax-I11Lmin]/I11Lmin) between maximum and minimum values of a
reproduction signal level from the space may be configured to be
equal to or less than 10%.
[0249] (10) A reproducing method may be applied to an optical disc
having one or more recording layers (L0, L1, etc.) on which marks
are recorded with a space formed therebetween, wherein the one or
more recording layers may include an organic dye material
configured to substantially avoid a physical modification
(deformation) or a physical change in an area of the recorded mark.
The reproducing method may comprise:
[0250] reproducing (ST200) management information (VMG) from the
recording layer using a laser with a given wavelength (e.g., 405
nm); and reproducing (ST202) object data (VOB or SOB) from the
recording layer using the laser, based on the reproduced management
information.
[0251] While certain embodiments of the inventions have been
described, these embodiments have been presented by way of example
only, and are not intended to limit the scope of the inventions.
Indeed, the novel methods and systems described herein may be
embodied in a variety of other forms. For instance, the invention
can be reduced to practice not only in a single/dual-layer disc,
but in a future available optical disc with three or more recording
layers.
[0252] Furthermore, various omissions, substitutions and changes in
the form of the methods and systems described herein may be made
without departing from the spirit of the inventions. The
accompanying claims and their equivalents are intended to cover
such forms or modification as would fall within the scope and
spirit of the inventions.
* * * * *