Note: Descriptions are shown in the official language in which they were submitted.
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Description
OPTICAL DISC RECORDING METHOD WITH IMPROVED
WAVEFORM FOR REDUCING JITTER
Technical Field
[1] Aspects of the present invention relate to a recording method,, a
recording apparatus,
and an optical recording medium thereof that can improve the quality of a
signal
reproduced from a high multi-speed recording medium, and more particularly, to
an in-
formation storage medium having an optimal recording waveform to improve a
jitter
effect caused by a fast recording process and a method and apparatus for
recording
data in the information storage medium.
Background Art
[2] In general, information storage media, for example, optical discs, are
widely used
with optical pickup devices which record and/or reproduce information in a non-
contact manner. Information storage media may be classified into compact discs
(CDs)
and digital versatile discs (DVDs) according to the information recording
capacities of
the information storage media. Examples of a recordable disc that can write,
erase, and
read information include a 650MB CD-recordable (CD-R), a CD-rewritable ( CD-
RW), a 4.7GB DVD+R/RW, a DVD-random access memory (RAM), and a DVD-
R/RW. Examples of a read-only disc include a 650MB CD-read only memory (ROM)
and a 4.7GB DVD-ROM. Furthermore, a high definition DVD (HD-DVD) having a
recording capacity of over 20GB is currently being developed.
[3] When data is recorded in an optical disc, which is one type of an optical
recording
medium, marks are formed in tracks of the optical disc. For a read-only
optical disc,
such as a CD-ROM and a DVD-ROM, the marks are produced in the form of pits.
For
a recordable optical disc, such as a CD-R/RW and a DVD-R/RW/RAM, a phase
change layer is coated with a phase change material that changes between an
amorphous state and a crystalline state. The marks are formed in the
recordable optical
disc when the phase change layer undergoes a phase change. In order to
optimize
recording and/or reproducing features, the recordable optical disc employs
write
strategies. The write strategies are applied differently depending on the type
of disc
being written to. A writing condition may vary depending on disc drives used
with the
optical disc, which may result in incompatibility between an optical recording
medium
and a disc drive. In particular, an increased recording speed is needed to
meet the
demands of users who want to perform fast recording of information on optical
discs
having high storage capacity.
[4] A high definition optical recording apparatus, such as a next generation
blu-ray disc
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(BD) recorder, performs recording by using a run length limited (RLL)(1,7)
code
method in which a minimum value of a time period T of a clock pulse is equal
to 2T.
When the (RLL)(1,7) code method is used, a laser output waveform for forming a
recording mark with a predetermined length is composed of multi-pulses in
which the
number of write pulses generally increases according to the length of the
recording
mark. As shown in FIG. 1, if the length of the recording mark is equal to an
integer
multiple of N of the time period T, the laser output waveform uses a write
strategy
composed of N-1 write pulses.
[51 When this method is used, it is difficult to switch a light source, i.e.,
a laser diode, in
order to form multi-pulses at a high multi-speed. In addition, since recording
is rapidly
performed, there is no benefit to using multi-pulses. Moreover, when heat is
rapidly
emitted from the laser diode, sufficient heat is not easily transferred to an
optical
recording medium. Thus, the recording mark is not properly formed. In order to
solve
these problems, a write strategy using a new pulse is required.
[61 FIGs. 1A and 1B illustrate a waveform diagram of a conventional recording
waveform using a conventional multi-pulse write strategy. FIG. 1A illustrates
a
waveform diagram of a conventional recording waveform, and FIG. 1B illustrates
a
conventional multi-pulse write strategy. Referring to FIGs. 1A and 1B, a
conventional
recording waveform using a multi-pulse recording pattern is used to record non
return
to zero inverted (NRZI) data. Here, T denotes the cycle of a reference
recording and/or
reproducing clock signal. According to a method of recording a mark edge, a
mark is
recorded when the NRZI data is at a high level, and a space is formed when the
NRZI
data is at a low level. A recording waveform used to record the mark is
referred to as a
recording pattern. A recording waveform used to form the space (i.e. to erase
the mark)
is referred to as an erase pattern. In the conventional recording waveform,
multi-pulses
are used for forming the recording pattern, and a power level of each pulse is
regulated
to have one of three levels: Pw, Pe, and Pb. Specifically, the recording multi-
pulses of
the recording pattern used to form the marks have the power levels Pw and Pb,
and the
recording waveform used to form the space has the power level Pe. The power
level Pe
of the erase pattern for forming a space using low level NRZI data is
maintained to be
a predetermined direct current (DC) level. Here, Pw denotes a write power
level, Pb
denotes a bias power level, and Pe denotes an erase power level.
[71 Referring to FIG. 1B, an N-1 write strategy is exemplified as a
conventional multi-
pulse recording strategy. A laser output waveform for forming a recording mark
with a
predetermined length is composed of multi-pulses in which the number of write
pulses
generally increases according to the length of the recording mark. If the
length of the
recording mark is an integer multiple of N of a time period T (e.g., 2T, 3T,
etc), the
laser output waveform has N-1 write pulses. For example, in order to record
the
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recording mark of 5T, the laser output waveform has four write pulses (5-1=4).
[81 Table #1 below shows conditions for a recording method using a multi-pulse
type
write strategy.
[91 [Table 11
[Table I
Laser wavelength 405nm
Numerical aperture 0.85
User data transfer rate 35.965(Mbit/s) x 4 multi-speed
Recording velocity 4.92(m/s) x 4 multi-speed
User data capacity 25 Gbyte
Track pitch 0.32 m
[101 Table #2 below shows a result obtained by comparing recording quality
(also
referred to as 'jitter') of recordings performed at various multi-speeds by
using the con-
ventional multi-pulse write strategy shown in FIG. 1.
[111 [Table 21
[Table I
Jitter at lx multi-speed recording 5.6%
Jitter at 2x multi-speed recording 6.4%
Jitter at 4x multi-speed recording 10.0%
[121 Referring to Table #2 above, when recording is performed by using the
conventional
N-1 write strategy at 4x multi-speed (a rotation speed of about 10,000 RPM),
jitter sub-
stantially increases in comparison with the case of jitter at lx multi-speed
recording or
jitter at 2x multi-speed recording.
[131 FIGs. 2A, 2B and 2C illustrate a simulation result of a recording mark
formed in a
blu-ray disc recordable (BD-R) during the process of 4x multi-speed recording
using a
conventional multi-pulse type write strategy. Specifically, FIG. 2A
illustrates data for a
recording mark of length 5T; FIG. 2B illustrates a conventional multi-pulse
write
strategy; and FIG. 2C illustrates a simulation result of the recording mark
using the
conventional multi-pulse type write strategy shown in FIG. 2B. As shown by the
irregular shape of the formed recording mark in the simulation result of FIG.
2C, heat
transferred in response to a write pulse does not effectively form the
recording mark at
high speed. Since the simulation result of the recording mark shown in FIG. 2C
has an
irregular shape, it is not easy to optimally form the recording mark or to
regulate the
length of the recording mark by using the conventional multi-pulse type write
strategy
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shown in FIG. 2B.
[141 FIGs. 3A and 3B illustrate a waveform diagram of a conventional write
strategy
having a box type recording pattern using one pulse. FIG. 3A illustrates a
waveform
diagram of a conventional recording waveform, and FIG. 3B illustrates a
conventional
box type recording pattern . Referring to FIGs. 3A and 3B, a laser output
waveform for
forming a recording mark having a predetermined length is composed of only one
pulse, irrespective of the length of the recording mark. A time period T is
determined
by the length of each pulse.
[151 Table #3 below shows conditions for a recording method using the
conventional box
type write strategy shown in FIG. 3.
[161 [Table 31
[Table I
Laser wavelength 405nm
Numerical aperture 0.85
User data transfer rate 35.965(Mbit/s) x 4 multi-speed
Recording velocity 4.92(m/s) x 4 multi-speed
User data capacity 25 Gbyte
Track pitch 0.32 m
[171 Table #4 below shows a result of recording quality ('jitter') at 4x multi-
speed
recording by using the conventional box type write strategy.
[181 [Table 41
[Table I
Jitter at 4x multi-speed recording 6.8%
[191 FIGs. 4A, 4B and 4C illustrate a simulation result of a recording mark
formed in a
BD-R during the process of 4x multi-speed recording using the conventional box
type
write strategy shown in FIG 3.
[201 The conventional box type write strategy, which records at 4x multi-speed
(a rotation
speed of about 10,000 RPM), is used to solve the problems resulting from the
con-
ventional multi-pulse type write strategy. FIG. 4A illustrates data for a
recording mark
of length 5T; FIG. 4B illustrates a conventional box type write strategy; and
FIG. 4C
illustrates a simulation result of the recording mark using the conventional
box type
write strategy shown in FIG. 4B. As FIG. 4C illustrates, the conventional box
type
write strategy decreases jitter in comparison with the conventional multi-
pulse type
write strategy.
[211 As shown by the simulation result of FIG. 4C, the recording mark has a
relatively
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uniform shape. This shows that sufficient heat is transferred so as to form
the recording
mark. However, unlike the simulation result shown in FIG. 2C, in the
simulation result
shown in FIG. 4C, a trailing portion of the recording mark is larger than a
leading
portion of the recording mark. This is because heat accumulation at the
trailing portion
of the recording mark increases relative to the heat accumulation accumulated
at the
trailing portion of the recording mark in the multi-pulse type write strategy.
Thus, it is
difficult to regulate the formation of a mark edge of the trailing portion of
the
recording mark.
[221 In the above two methods, when recording is performed at a rotation speed
equal to
or greater than about 10,000 RPM, switching a laser diode to implement the con-
ventional multi-pulse type write strategy as currently used is difficult.
Furthermore,
since the amount of heat transferred to a recording medium is small per unit
time,
using the conventional multi-pulse type write strategy for high speed
recording is not
appropriate for the formation of the recording mark. Therefore, the
conventional box
type write strategy may instead be used for recording so that more heat can be
transferred per unit time with a pulse structure that is simpler to achieve in
terms of
switching the laser diode. As a result, the conventional box type write
strategy
decreases jitter compared to the jitter generated by the conventional multi-
pulse type
write strategy.
Disclosure of Invention
Technical Problem
[231 However, the simulation result shown in FIG. 4C illustrates that the
trailing portion
of the recording mark is larger than the leading portion of the recording
mark. This
change in the width of the recording mark occurs because of heat accumulation.
Ac-
cordingly, an optimal write strategy is required for high multi-speed
recording.
Technical Solution
[241 Aspects of the present invention provide a recording apparatus, a
recording method,
and an optical recording medium that can improve quality of a reproducing
signal by
facilitating regulation of a trailing portion of a mark in a high multi-speed
recording
medium.
Advantageous Effects
[251 According to aspects of the present invention, a trailing portion of a
mark can be
easily regulated in a high multi-speed recording medium, thereby improving the
quality of a reproducing signal.
Description of Drawings
[261 FIG. 1A illustrates a waveform diagram of a conventional recording
waveform;
[271 FIG. 1B illustrates a conventional multi-pulse recording pattern;
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[281 FIG. 2A illustrates a recording mark of length 5T;
[291 FIG. 2B illustrates an example of a multi-pulse recording pattern used to
form the
recording mark illustrated in FIG. 2A;
[301 FIG. 2C illustrates a simulation result of the recording mark formed by
using the
multi-pulse recording pattern shown in FIG. 2B;
[311 FIG. 3A illustrates a waveform diagram of a conventional recording
waveform;
[321 FIG. 3B illustrates a conventional single-pulse recording pattern;
[331 FIG. 4A illustrates a recording mark of length 5T;
[341 FIG. 4B illustrates an example of a single-pulse recording pattern used
to form the
recording mark illustrated in FIG. 4A;
[351 FIG. 4C illustrates a simulation result of the recording mark formed by
using the
single-pulse recording pattern shown in FIG. 4B;
[361 FIG. 5 is a block diagram of a recording apparatus according to an
embodiment of
the present invention;
[371 FIG. 6 is a block diagram of a recording apparatus according to another
embodiment
of the present invention;
[381 FIG. 7A illustrates a recording mark of length 5T;
[391 FIG. 7B illustrates a box type recording pattern for recording the mark
of length 5T
shown in FIG. 7A according to an embodiment of the present invention;
[401 FIG. 7C illustrates a recording mark formed by using the box type
recording pattern
of FIG. 7B according to an embodiment of the present invention;
[411 FIG. 8A illustrates a waveform diagram of a recording waveform;
[421 FIG. 8B illustrates a first example of a box type recording pattern
according to an
embodiment of the present invention;
[431 FIG. 9A illustrates a waveform diagram of a recording waveform;
[441 FIG. 9B illustrates a second example of a box type recording pattern
according to an
embodiment of the present invention;
[451 FIG. 10A illustrates a waveform diagram of a recording waveform;
[461 FIG. 10B illustrates a third example of a box type recording pattern
according to an
embodiment of the present invention;
[471 FIG. 1 1A illustrates a waveform diagram of a recording waveform;
[481 FIG. 11B illustrates a fourth example of a box type recording pattern
according to an
embodiment of the present invention;
[491 FIG. 12A illustrates a waveform diagram of a recording waveform;
[501 FIG. 12B illustrates a fifth example of a box type recording pattern
according to an
embodiment of the present invention;
[511 FIG. 13A illustrates a waveform diagram of a recording waveform;
[521 FIG. 13B illustrates a sixth example of a box type recording pattern
according to an
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embodiment of the present invention;
[531 FIG. 14 is a flowchart of a data recording method according to an
embodiment of the
present invention;
[541 FIG. 15 is a flowchart of a parameter recording method according to an
embodiment
of the present invention; and
[551 FIG. 16 is a flowchart of a method of using a parameter after reading the
parameter
from an information storage medium according to an embodiment of the present
invention.
Best Mode
[561 Additional aspects and/or advantages of the invention will be set forth
in part in the
description which follows and, in part, will be obvious from the description,
or may be
learned by practice of the invention.
[571 According to an aspect of the present invention, a method of recording
data in an
optical recording medium comprises: generating a box type recording pattern
including
a first pulse, which has a duration determined according to a length of a
recording
mark and which has a first power level, and a second pulse which has a second
power
level different from the first power level, and recording data according to
the box type
recording pattern.
[581 According to an aspect of the present invention, the second pulse is
positioned at an
edge portion of the box type recording pattern so as to regulate an edge
portion of the
recording mark.
[591 According to an aspect of the present invention, when the recording mark
has a
length of nT, the second pulse starts at a time point of (n-1)T.
[601 According to an aspect of the present invention, when the recording mark
has a
length of nT and n is an integer, the first pulse of the box type recording
pattern starts
at a first position separated by a first distance from a time point that is 1T
from a start
point for forming the recording mark or at a second position separated by a
second
distance from the start point for forming the recording mark.
[611 According to an aspect of the present invention, the second pulse is
generated im-
mediately following the first pulse, and a length of the box type recording
pattern is
determined based on a length from a start point of the first pulse to an end
point of the
second pulse.
[621 According to an aspect of the present invention, the second pulse is
generated im-
mediately following the first pulse, and a length of the box type recording
pattern is
determined based on a total duration of the first pulse and the second pulse.
[631 According to an aspect of the present invention, the second pulse is
generated im-
mediately following the first pulse, the duration of the first pulse is
determined by a
distance from a start point of the first pulse to a start point of the second
pulse, and the
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second pulse may end at a second position separated by a second distance from
an end
point of the record mark.
[641 According to an aspect of the present invention, the generating of the
recording
pattern comprises reading parameter information for the box type recording
pattern
from the optical recording medium and generating the box type recording
pattern
according to the read parameter information.
[651 According to another aspect of the present invention, a method of
recording in-
formation on a recording pattern in an optical recording medium includes
generating
the information on the recording pattern, and recording the generated
information on
the recording pattern in a predetermined area of the optical recording medium,
wherein
the information on the recording pattern comprises parameter information on a
box
type recording pattern comprising a first pulse, which has a duration
determined
according to a length of a recording mark and which has a first power level,
and a
second pulse which has a second power level different from the first power
level.
[661 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a time point that is 1T from a
start point for
forming the recording mark, and a length of the box type recording pattern
determined
by a length from the start point of the first pulse to an end point of the
second pulse,
wherein the recording mark has a length of nT, and n is an integer.
[671 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a start point for forming the
recording mark,
and a length of the box type recording pattern determined by a length from the
start
point of the first pulse to an end point of the second pulse.
[681 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a time point that is 1T from the
start point
for forming the recording mark, a duration of the first pulse determined by a
distance
from the start point of the first pulse to a start point of the second pulse,
and an end
point of the second pulse which ends at a second position separated by a
second
distance from an end point of the first pulse, wherein the recording mark has
a length
of nT, and n is an integer.
[691 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a time point for forming the
recording mark,
a duration of the first pulse determined by a distance from the start point of
the first
pulse to a start point of the second pulse, and an end point of the second
pulse which
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ends at a second position separated by a second distance from an end point of
the first
pulse.
[701 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a time point that is 1T from the
start point
for forming the recording mark, a duration of the first pulse determined by a
distance fr
om the start point of the first pulse to a start point of the second pulse,
and an end point
of the second pulse which ends at a second position separated by a second
distance
from an end point of the record mark, wherein the recording mark has a length
of nT,
and n is an integer.
[711 According to another aspect of the present invention, the parameter
information on
the box type recording pattern comprises a start point of the first pulse at a
first
position separated by a first distance from a time point for forming the
recording mark,
a duration of the first pulse determined by a distance from the start point of
the first
pulse to a start point of the second pulse, and an end point of the second
pulse which
ends at a second position separated by a second distance from an end point of
the
recording mark.
[721 According to another aspect of the present invention, the parameter
information on
the box type recording pattern further comprises an end point of a cooling
pulse
separated by a predetermined distance from an end point of the recording mark.
[731 According to another aspect of the present invention, an apparatus for
recording data
as a recording mark on an optical recording medium comprises a recording
waveform
generator which generates a box type recording pattern including a first
pulse, which
has a duration determined according to a length of a recording mark and which
has a
first power level, and a second pulse which has a second power level different
from the
first power level, and a pickup unit which records the recording mark
according to the
box type recording pattern.
[741 According to another aspect of the present invention, an apparatus for
recording
parameter information in an optical recording medium comprises: a controller
which
generates parameter information on a box type recording pattern including a
first pulse,
which has a duration determined according to a length of a recording mark and
which
has a first power level, and a second pulse which has a second power level
different
from the first power level, and a pickup unit which records the generated
information
on the recording pattern in an area of the optical recording medium.
[751 According to another aspect of the present invention, an optical
recording medium
for a recording and/or reproducing apparatus comprises an area where parameter
in-
formation on a recording pattern is recorded, wherein the parameter
information on the
recording pattern comprises parameter information on a box type recording
pattern
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including a first pulse, which has a duration determined according to a length
of a
recording mark and which has a first power level, and a second pulse which has
a
second power level different from the first power level, and the parameter
information
is used to offset heat accumulation generated during recording to prevent
changes in a
width of the recording mark in the recording pattern.
Mode for Invention
[761 Reference will now be made in detail to the present embodiments of the
present
invention, examples of which are illustrated in the accompanying drawings,
wherein
like reference numerals refer to the like elements throughout. The embodiments
are
described below in order to explain the present invention by referring to the
figures.
[771 FIG. 5 is a block diagram of a recording apparatus 1 according to an
embodiment of
the present invention. Referring to FIG. 5, the recording apparatus 1 records
data by
forming a mark or a space in an optical recording medium 100. The recording
apparatus 1 includes a pickup unit 10, a recording waveform generator 20, and
a
channel modulator 30.
[781 The channel modulator 30 modulates externally input data to a channel bit
stream in
accordance with a predetermined modulation algorithm, such as RLL (1,7)
modulation
techniques.
[791 The recording waveform generator 20 receives the channel bit stream from
the
channel modulator 30 to generate a recording waveform for writing the channel
bit
stream according to information on a recording pattern. The recording waveform
includes a box type recording pattern composed of a first pulse having a first
power
level and a second pulse having a power level lower than the first power
level. The
recording waveform will be described later in greater detail.
[801 The pickup unit 10 irradiates light to the optical recording medium 100
according to
the generated recording waveform in order to form a mark or a space. The
pickup unit
includes a motor (not shown) which rotates the optical recording medium 100,
an
optical head (not shown) which irradiates a laser light from a laser source
(not shown)
to the optical recording medium 100 or receives a laser light reflected from
the optical
recording medium 100, a servo circuit (not shown) which servo-controls the
motor and
the optical head, and a laser driving circuit (not shown) which drives a laser
installed at
the servo circuit and the optical head.
[811 The recording apparatus 1 may perform a write test and an erase test on a
test area of
the optical recording medium 100 by using specific test data (arbitrary data
or pre-
determined data) according to parameter information of the box type recording
pattern.
After performing the write test and the erase test, the recording apparatus 1
may select
an optimal condition (e.g., a minimum jitter value, a maximum resolution, a
maximum
modulation rate) from the test conditions according to the test result. The
selected
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condition may then be applied to the recording waveform generator 20.
[821 FIG. 6 is a block diagram of a recording apparatus 2 according to another
embodiment of the present invention. Referring to FIG. 6, the recording
apparatus 2
records data by forming a mark or a space in an optical recording medium 100.
The
recording apparatus 2 includes a pickup unit 10, a recording waveform
generator 20, a
channel modulator 30, a signal processor 40, and a controller 50.
[831 The channel modulator 30 modulates externally input data to a channel bit
stream in
accordance with a predetermined modulation algorithm, such as RLL (1,7)
modulation
techniques.
[841 The recording waveform generator 20 receives the channel bit stream from
the
channel modulator 30 to generate a recording waveform for writing the channel
bit
stream. The pickup unit 10 irradiates light to the optical recording medium
100
according to the generated recording waveform so as to form the mark or the
space.
[851 More specifically, the channel modulator 30 modulates input data to a
channel bit
stream, thereby outputting non return to zero inverted (NRZI) data. The
recording
waveform generator 20 generates a recording waveform for writing the NRZI data
and
supplies the generated waveform to a laser driving circuit (not shown)
included in the
pickup unit 10. It is understood that the invention is not limited to using
NRZI data,
and may instead use other types of data, such as non return to zero (NRZ)
data.
[861 The laser driving circuit (not shown) receives the recording waveform to
control the
laser source (not shown) to irradiate laser light onto the optical recording
medium 100
so as to form the mark or the space.
[871 In particular, the pickup unit 10 reads information on a recording
pattern from a
specific area of the optical recording medium 100. The signal processor 40
performs
signal processing of the information on the read recording pattern and
transmits the
result of the signal processing to the controller 50. The controller 50
transmits the in-
formation on the recording pattern to the recording waveform generator 20. The
recording waveform generator 20 generates a recording waveform for writing
channel
data received from the channel modulator 30 according to the information on
the
recording pattern received from the controller 50. The information on the
recording
pattern read from the optical recording medium 100 contains parameter
information for
generating a box type recording pattern composed of a first pulse having a
first power
level and a second pulse having a power level lower than the first power
level. The
parameter information for generating the box type recording pattern will be
described
later.
[881 FIGs. 7A, 7B and 7C illustrate a box type recording pattern and a mark
formed by
using the box type recording pattern according to an embodiment of the present
invention. FIG. 7A shows NRZI data for a mark of length 5T. FIG. 7B shows a
box
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type recording pattern for recording the mark of length 5T shown in FIG. 7A.
FIG. 7C
shows a shape of a mark formed in an information storing medium by using the
box
type recording pattern shown in FIG. 7B.
[891 Referring to FIG. 7A, the NRZI data for the mark of length 5T has a
rising edge at a
start point 90 and a falling edge at an end point 95. After the NRZI data for
the mark of
length 5T begins, a time point that is 1T from the start point is indicated by
a reference
numeral 91, a time point that is 2T from the start point is indicated by a
reference
numeral 92, a time point that is 3T from the start point is indicated by a
reference
numeral 93, a time point that is 4T from the start point is indicated by a
reference
numeral 94, and a time point that is 5T from the start point is indicated by a
reference
numeral 95. However, such a mark length is not limited thereto.
[901 Referring to FIG. 7B, the box type recording pattern includes a first
pulse 70 having
a first power level Pwl and a second pulse 80 having a second power level Pw2
which
is different from the first power level. Preferably, the second power level
Pw2 is lower
than the first power level Pw 1. However, the second power level Pw2 is not
limited to
being lower than the first power Pwl. Additionally, the first and second power
levels
Pwl and Pw2 may be adjusted depending on recording conditions, such as an
amount
of heat accumulation. Also, more than two power levels may be used to reduce
the
effects of heat accumulation.
[911 The duration of the first pulse 70 is determined according to a mark
length. The
second pulse 80 is positioned at a trailing portion of the box type recording
pattern. For
example, the start point of the second pulse 80 may be positioned at a time
point of
(n-1)T when the mark length is nT. Referring to FIG. 7B, the mark length is
equal to
5T, and the start point of the second pulse 80 is equal to the time point 94
because
(n-1)T = (5-1)T = 4T. However, the start point of the second pulse is not
limited to
being at a position (n-1)T.
[921 The parameter of the box type recording pattern may have various forms.
For
example, the parameter may include a start point 71 of the first pulse 70, a
duration 72
of the first pulse 70, a duration 82 of the second pulse 80, a total duration
73 of the first
pulse 70 and the second pulse 80, an end point 81 of the second pulse 80, and
an end
point of a cooling pulse 110. The start point 71 of the first pulse 70 may be
determined
by a distance from the start point 90 of the mark. Alternatively, the start
point 71 may
be determined by a distance from the time point 91 that is 1T from the start
point of the
NRZI data for forming the mark. Furthermore, the start point 71 may be
determined by
a distance from various other time points, such as 92, 93, etc. In addition,
the end point
81 of the second pulse 80 may be determined by a distance from (n-1)T.
Alternatively,
the end point 81 may be determined by a distance from the end point 95 of the
mark.
Furthermore, the end point 81 may be determined by a distance from various
other
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times points, such as 92, 93, etc.
[931 The parameter having various forms will now be described in detail with
reference to
FIGS. 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A and 13B. When data is
recorded onto an optical recording medium using the box type recording pattern
shown
in FIG. 7B, which includes two pulses having the first and second power
levels, a mark
having a regular shape and a uniform width as shown in FIG. 7C may be
obtained.
[941 Table #5 below shows a result of quality (also referred to as 'jitter')
at 4x multi-speed
recording by using the box type write strategy shown in FIG. 7B. Recording
conditions
are the same as those described with reference to FIG. 3. Using the box type
write
strategy shown in FIG. 7C decreases the amount of jitter in comparison to the
jitter
generated by conventional write strategies.
[951 [Table 51
[Table I
jitter at 4x multi-speed recording 6.2%
[961 Examples of a parameter for a box type recording pattern according to
aspects of the
present invention will now be described with reference to FIGS. 8 A, 8B, 9A,
9B, 10A,
10B, 11A, 1 1B, 12A, 12B, 13A and 13B. In the recording apparatus according to
aspects of the present invention, a recording waveform for recording data is
generated
by using parameters for the box type recording pattern. Furthermore, according
to
aspects of the present invention, parameter information for the box type
recording
pattern is recorded in a specific area of an information storage medium, and
parameter
information for the box type recording pattern recorded in the specific area
of the in-
formation storage medium is read in order to generate a recording waveform for
recording data on the basis of the parameter information. The parameter
information
for the box type recording pattern may vary depending on various recording
conditions, such as, for example, a recording speed, a recording layer
location, and a
recording layer material.
[971 FIGs. 8A and 8B illustrate a first example of a parameter for a box type
recording
pattern according to an embodiment of the present invention. FIG. 8A
illustrates a
waveform diagram of a recording waveform, and FIG. 8B illustrates a first
example of
a box type recording pattern. Referring to FIG. 8B, the box type recording
pattern
includes a first pulse 70 having a first power level Pwl and a second pulse 80
having a
second power level Pw2 lower than the first power level Pw 1. The first
example of the
parameter for the box type recording pattern includes a start point dP of the
first pulse
70, a duration P of the box type recording pattern, and an end point dS of a
cooling
pulse 110.
[981 The start point dP of the first pulse 70 of the box type recording
pattern according to
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the example shown in FIG. 8 is measured starting from a time point that is 1T
from the
start point for forming the recording data. The duration P of the box type
recording
pattern denotes a total duration of a write pulse from the start point dP of
the first pulse
70 to an end point EP of the second pulse 80. The end point dS is an end point
of a
cooling pulse 110 that is measured from an end point of the recording data.
[991 FIGs. 9A and 9B illustrate a second example of a parameter for a box type
recording
pattern according to an embodiment of the present invention. FIG. 9A
illustrates a
waveform diagram of a recording waveform, and FIG. 9B illustrates a second
example
of a box type recording pattern. Referring to FIG. 9B, the box type recording
pattern
includes a first pulse 70 having a first power level Pwl and a second pulse 80
having a
second power level Pw2 lower than the first power level Pw 1. The second
example of
the parameter for the box type recording pattern includes a start point dP of
the first
pulse 70, a duration P of the box type recording pattern, and an end point dS
of a
cooling pulse 110.
[1001 The start point dP of the first pulse 70 of the box type recording
pattern according to
the example shown in FIG. 9 is measured starting from a mark start point MSP.
The
duration P of the box type recording pattern denotes a total duration of a
write pulse
from the start time dP of the first pulse 70 to an end point EP of the second
pulse 80.
The end point dS is an end point of a cooling pulse 110 that is measured from
an end
point of the recording data.
[1011 FIGs. 10A and 10B illustrate a third example of a parameter for a box
type recording
pattern according to an embodiment of the present invention. FIG. 10A
illustrates a
waveform diagram of a recording waveform, and FIG. 10B illustrates a third
example
of a box type recording pattern. Referring to FIG. l OB, the box type
recording pattern
includes a first pulse 70 having a first power level Pwl and a second pulse 80
having a
second power level Pw2 lower than the first power level Pw 1. The third
example of the
parameter for the box type recording pattern includes a start point dP of the
first pulse
70, a duration P of the first pulse 70, an end point L of the second pulse 80,
and an end
point dS of a cooling pulse 110.
[1021 The start point dP of the first pulse 70 of the box type recording
pattern according to
the example shown in FIG. 10 is measured starting from a time point that is 1T
from
the start point for forming the recording data. The duration P of the first
pulse 70
denotes a length from the start point dP of the first pulse 70 to a start
point of the
second pulse 80. The end point L of the second pulse 80 is measured starting
from a
first pulse end point FEP. The end point dS is an end point of a cooling pulse
110 that
is measured from an end point of the recording data.
[1031 FIGs. 1 1A and 11B illustrate a fourth example of a parameter for a box
type
recording pattern according to an embodiment of the present invention. FIG.
11A il-
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lustrates a waveform diagram of a recording waveform, and FIG. 11B illustrates
a
fourth example of a box type recording pattern. Referring to FIG. 1 1B, the
box type
recording pattern includes a first pulse 70 having a first power level Pwl and
a second
pulse 80 having a second power level Pw2 lower than the first power level Pwl.
The
fourth example of the parameter for the box type recording pattern includes a
start
point dP of the first pulse 70, a duration P of the first pulse 70, an end
point L of the
second pulse 80, and an end point dS of a cooling pulse 110.
[1041 The start point dP of the first pulse 70 of the box type recording
pattern according to
the example shown in FIG. 11 is measured starting from a mark start point MSP.
The
duration P of the first pulse 70 denotes a length from the start point dP of
the first pulse
70 to a start point of the second pulse 80. The end point L of the second
pulse 80 is
measured starting from a first pulse end point FEP. The end point dS is an end
point of
a cooling pulse 110 that is measured from an end point of the recording data.
[1051 FIGs. 12A and 12B illustrate a fifth example of a parameter for a box
type recording
pattern according to an embodiment of the present invention. FIG. 12A
illustrates a
waveform diagram of a recording waveform, and FIG. 12B illustrates a fifth
example
of a box type recording pattern. Referring to FIG. 12, the box type recording
pattern
includes a first pulse 70 having a first power level Pwl and a second pulse 80
having a
second power level Pw2 lower than the first power level Pw 1. The fifth
example of the
parameter for the box type recording pattern includes a start point dP of the
first pulse
70, a duration P of the first pulse 70, an end point dL of the second pulse
80, and an
end point dS of a cooling pulse 110.
[1061 The start point dP of the first pulse 70 of the box type recording
pattern according to
the example shown in FIG. 12 is measured starting from a time point that is 1T
from
the start point for forming the recording data. The duration P of the first
pulse 70
denotes a length from the start point dP of the first pulse 70 to a start
point of the
second pulse 80. The end point dL of the second pulse 80 is measured starting
from a
mark end point MEP. The end point dS is an end point of a cooling pulse 110
that is
measured from an end point of the recording data.
[1071 FIGs. 13A and 13B illustrate a sixth example of a parameter for a box
type recording
pattern according to an embodiment of the present invention. FIG. 13A
illustrates a
waveform diagram of a recording waveform, and FIG. 13B illustrates a sixth
example
of a box type recording pattern. Referring to FIG. 13B, the box type recording
pattern
includes a first pulse 70 having a first power level Pwl and a second pulse 80
having a
second power level Pw2 lower than the first power level Pw 1. The sixth
example of the
parameter for the box type recording pattern includes a start point dP of the
first pulse
70, a duration P of the first pulse 70, an end point dL of the second pulse
80, and an
end point dS of a cooling pulse 110.
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[1081 The start point dP of the first pulse 70 of the box type recording
pattern is measured
starting from a mark start point MSP. The duration P of the first pulse 70
denotes a
length from the start point dP of the first pulse 70 to a start point of the
second pulse
80. The end point dL of the second pulse 80 is measured starting from a mark
end
point MEP. The end point dS is an end point of a cooling pulse 110 that is
measured
from an end point of the recording data.
[1091 FIG. 14 is a flowchart of a data recording method according to an
embodiment of the
present invention.
[1101 First, non return to zero inverted (NRZI) data is generated at block
141.
[1111 Next, a recording waveform is generated which has a box type recording
pattern
composed of a first pulse which has a first power level and which has a
duration
determined according to a length of a recording mark, and a second pulse which
has a
second power level different from the first power level, at block 142.
Preferably, the
second power level is lower than the first power level.
[1121 Next, at block 143, NRZI data is recorded when a mark or a space is
formed by using
the recording waveform generated at block 142.
[1131 FIG. 15 is a flowchart of a parameter recording method according to an
embodiment
of the present invention.
[1141 Referring to FIG. 15, a parameter is determined for a box type recording
pattern
composed of a first pulse which has a first power level and which has a
duration
determined according to a length of a recording mark, and a second pulse which
has a
second power level different from the first power level, at block 151.
Preferably, the
second power level is lower than the first power level.
[1151 Next, the parameter determined at block 151 is stored in an information
storage
medium at block 152.
[1161 FIG. 16 is a flowchart of a method of using a parameter after reading
the parameter
from an information storage medium according to an embodiment of the present
invention.
[1171 Referring to FIG. 16, parameter information is read from an information
storage
medium, wherein the parameter information is information regarding a box type
recording pattern composed of a first pulse which has a first power level and
which has
a duration determined according to a length of a recording mark and a second
pulse
which has a second power level different from the first power level, at block
161.
Preferably, the second power level is lower than the first power level.
[1181 Next, at block 162, a recording condition is determined by using the
parameter in-
formation read at block 161, and data is stored in the information storage
medium
based on the determined recording condition.
[1191 Aspects of the invention can also be embodied as computer readable codes
on a
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computer readable recording medium. The computer readable recording medium is
any
data storage device that can store data which can be thereafter read by a
computer
system. Examples of the computer readable recording medium include read-only
memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy
disks, optical data storage devices, and a computer data signal embodied in a
carrier
wave comprising a compression source code segment and an encryption source
code
segment (such as data transmission through the Internet). The computer
readable
recording medium can also be distributed over network coupled computer systems
so
that the computer readable code is stored and executed in a distributed
fashion. Also,
functional programs, codes, and code segments for accomplishing aspects of the
present invention can be easily construed by programmers skilled in the art to
which
the present invention pertains.
[1201 While there have been illustrated and described what are considered to
be example
embodiments of the present invention, it will be understood by those skilled
in the art
and as technology develops that various changes and modifications may be made,
and
equivalents may be substituted for elements thereof without departing from the
true
scope of the present invention. Many modifications, permutations, additions
and sub-
combinations may be made to adapt the teachings of the present invention to a
particular situation without departing from the scope thereof. For example, in
FIG. 8B,
the box type recording pattern is not limited to having a first pulse 70 and a
second
pulse 80, and may instead have a series of pulses which each correspond to
different
power levels. Additionally, FIGs. 8A, 8B, 9A, 9B, 10A, 10B, 1 1A, 1 1B, 12A,
12B,
13A and 13B are not required to have a first pulse and a second pulse, and may
instead
have a single pulse which has an adjustable power level, or may have more than
two
pulses. Accordingly, it is intended, therefore, that the present invention not
be limited
to the various example embodiments disclosed, but that the present invention
includes
all embodiments falling within the scope of the appended claims.
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