U.S. patent application number 09/949640 was filed with the patent office on 2002-03-14 for information recording method and apparatus.
Invention is credited to Minemura, Hiroyuki, Miyamoto, Harukazu, Miyauchi, Yasushi.
Application Number | 20020031073 09/949640 |
Document ID | / |
Family ID | 26420603 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020031073 |
Kind Code |
A1 |
Miyamoto, Harukazu ; et
al. |
March 14, 2002 |
Information recording method and apparatus
Abstract
An information recording method for recording information on a
rewritable recording medium including recording first synchronizing
signal information in a first synchronizing signal portion on the
rewritable recording medium, recording second synchronizing signal
information in a second synchronizing signal portion following the
first synchronizing signal portion on the rewritable recording
medium, and recording data information in a data portion of the
rewritable recording medium after the second synchronizing signal
portion by forming marks in the data portion, wherein the data
information corresponds to both ends of each of the record marks. A
length of the first synchronizing signal portion changes and a
start position of the first synchronizing signal portion changes,
and a change of the start position of the first synchronizing
signal portion is smaller than a change of the length of the first
synchronizing signal portion.
Inventors: |
Miyamoto, Harukazu;
(Kodaira-shi, JP) ; Minemura, Hiroyuki;
(Yokohama-shi, JP) ; Miyauchi, Yasushi;
(Akishima-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
26420603 |
Appl. No.: |
09/949640 |
Filed: |
September 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09949640 |
Sep 12, 2001 |
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09712969 |
Nov 16, 2000 |
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6307825 |
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09712969 |
Nov 16, 2000 |
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09535016 |
Mar 24, 2000 |
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6181661 |
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09535016 |
Mar 24, 2000 |
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09350282 |
Jul 9, 1999 |
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6104692 |
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09350282 |
Jul 9, 1999 |
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08863126 |
May 27, 1997 |
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5953299 |
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Current U.S.
Class: |
369/59.25 ;
G9B/20.01; G9B/20.015; G9B/20.027; G9B/7.01; G9B/7.026; G9B/7.031;
G9B/7.034; G9B/7.038 |
Current CPC
Class: |
G11B 2020/10898
20130101; G11B 2220/2537 20130101; G11B 7/0045 20130101; G11B 20/12
20130101; G11B 2020/1288 20130101; G11B 7/00454 20130101; G11B
7/013 20130101; G11B 20/10009 20130101; G11B 2020/1285 20130101;
G11B 20/1217 20130101; G11B 7/00718 20130101; G11B 7/006 20130101;
G11B 2020/1287 20130101; G11B 2220/216 20130101; G11B 7/00745
20130101 |
Class at
Publication: |
369/59.25 |
International
Class: |
G11B 007/0045 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 1996 |
JP |
08-136189 |
Mar 31, 1997 |
JP |
09-079587 |
Claims
1. An information recording method for recording information on a
rewritable recording medium comprising the steps of: recording
first synchronizing signal information in a first synchronizing
signal portion on the rewritable recording medium; recording second
synchronizing signal information in a second synchronizing signal
portion following the first synchronizing signal portion on the
rewritable recording medium; recording data information in a data
portion of the rewritable recording medium after the second
synchronizing signal portion by forming marks in the data portion
wherein said data information corresponds to both ends of each of
said record marks; wherein a length of the first synchronizing
signal portion changes and a start position of the first
synchronizing signal portion changes, and wherein a change of the
start position of the first synchronizing signal portion is smaller
than a change of the length of the first synchronizing signal
portion.
2. An information recording medium according to claim 1, wherein
the second synchronizing signal information is a fixed pattern.
3. An information recording method according to claim 1, wherein a
polarity of the second synchronizing signal portion is changed
depending on a polarity of a final end of the first synchronizing
signal portion.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of U.S. application Ser. No.
09/712,969, filed Nov. 16, 2000, which is a continuation of U.S.
application Ser. No. 09/535,016, filed Mar. 24, 2000, now U.S. Pat.
No. 6,181,661, which is a continuation of U.S. application Ser. No.
09/350,282, filed Jul. 9, 1999, now U.S. Pat. No. 6,104,692, which
is a continuation of U.S. application Ser. No. 08/863,126, filed
May 27, 1997, now U.S. Pat. No. 5,953,299, the subject matter of
which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a so-called mark-edge
recording in which marks are recorded in certain areas of a
recording medium so that their physical property is made different
from the other areas to thereby have information associated with
both ends of each of the marks.
[0003] The present invention is particularly suited to a rewritable
high-density information recording method capable of recording
information to be repeatedly rewritable. The present invention is
also suited to a so-called phase-changing type information
recording method in which the physical property of the information
recorded areas is made different from the other areas by the phase
change of the recorded substance that is caused by changing the
temperature of the information recording medium.
[0004] A conventional rewritable information recording method is
disclosed in, for example, JP-A-63-229625. This method is an
optical disk recording method for recording information by
modulating the intensity of light.
[0005] As shown in FIG. 6, information is recorded in a plurality
of sectors 21, each of which has identification information 24
provided at its head in order to indicate the physical position of
information. This identification information 24 is used as a
reference to be followed by a synchronizing signal portion 22 and
an information recorded portion 23 which are recorded as a record
unit on the recording medium. At this time, the start position of
the record unit is randomly changed in its position at each time of
rewriting, thereby increasing the possible number of times of
repeated rewriting. In other words, the disk material at the same
place within a sector is prevented as much as possible from being
deteriorated by repeated rewriting, thereby raising the possible
number of times of repeated writing.
[0006] FIG. 7 illustrates the relation between the number of times
of rewriting and the jitter in the case where the same recording
information is repeatedly recorded. Here, the jitter is defined as
the standard deviation normalized by a reproduction detection
window width, the standard deviation being of the time shift
between a reproduction clock and a reproduced data after the same
random data is EFM-modulated, recorded repeatedly and then
reproduced.
[0007] In FIG. 7, a curve 701 was obtained when the start position
of the recorded portion is shifted by 2 bytes in the mark-edge
recording, a curve 702 when shifted by 30 bytes in the mark-edge
recording, a curve 703 when shifted by 2 bytes in the mark-position
recording, a curve 704 when shifted by 100 bytes in the mark-edge
recording, and a curve 705 when shifted by 30 bytes in the
mark-position recording. Here, the mark-position recording is the
recording system in which information is recorded in association
with the center position of the mark.
[0008] From FIG. 7, it will be seen that the increase of jitter
after rewriting can be suppressed more, or the possible number of
times of rewriting is increased as the amount of the shift of the
start position of the recorded area is increased. Here, the minimum
mark distance, in the mark-position recording in which data is
associated with the center position of the mark, was selected to be
0.9 .mu.m, and the minimum mark distance, in the mark-edge
recording in which data is associated with both ends of the mark,
was chosen to be 0.6 .mu.m. In addition, the diameter of the
recording and reproducing spot was 0.9 .mu.m, and the recording
medium used was a GeSbTe-based phase-change recording medium.
[0009] However, in the start-position shift system, and
particularly in the mark-edge recording, the shift of the start
position of the randomly recorded data must be increased to about
100 bytes in order to achieve a practical possible number of times
of rewriting, as will be understood from FIG. 7, when the same
information is repeatedly rewritten. Therefore, the utilization
efficiency of sectors was greatly reduced. In addition, under this
great positional shift, the beginning end or last end of recorded
information will be superimposed upon other recorded portions.
Since the recording characteristics of the beginning end or last
end of recorded information are deteriorated probably due to the
dissolution or flow of the recorded film, the effect of the change
of the recording and production characteristics may be expanded
over a wide range by repeated rewriting of these portions.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide an
information recording method capable of greatly increasing the
possible number of times of repeated rewriting without reducing the
recording efficiency in a rewritable high-density information
recording method for repeatedly rewriting information so that the
recorded information can be associated with both ends of a
mark.
[0011] It is another object of the invention to provide an
information recording apparatus capable of greatly increasing the
possible number of times of repeated rewriting without reducing the
recording efficiency in a rewritable high-density information
recording method for repeatedly rewriting information so that the
recorded information can be associated with both ends of a
mark.
[0012] The present invention, in order to achieve the first object,
provides the following aspects.
[0013] (1) An information recording method is provided for
repeatedly recording information on a recording medium in
association with both ends of each of marks that are formed to be
different in their physical property from other areas, wherein each
time information is recorded, the marks and the spaces between the
marks are substantially randomly inverted in their positions.
[0014] Thereby, when repetitive rewriting is made, the total number
of times that the marks and spaces are recorded is uniform over all
the medium, and therefore the medium is physically uniformly
changed by repetitive recording. Accordingly, the possible number
of times of repetitive rewriting can be greatly increased. This
does not reduce the information recording efficiency at all.
[0015] (2) The substantially random inversion is made at each
record unit.
[0016] Here, the record unit is a unit such as a sector that is
actually recorded on the recording medium. In other words, any
smaller ones than these record units are never rewritten as
information on the recording medium. Of course, it is possible that
after the record units are reproduced, only part of the reproduced
information is modified and again recorded as in the
read-modify-write process so that the minimum unit to be recorded
can be apparently reduced. However, even in this case, the
above-given record units are actually recorded on and reproduced
from the medium. If this inversion occurred within the record unit,
a complicated process would be necessary at the time of signal
reproduction.
[0017] Thereby, the total number of times that marks are recorded
in each record unit is uniform over the record unit.
[0018] Since the reproduction process is generally made for each
information record unit, the change of the medium due to repetitive
recording of each record unit is uniform, and thus the possible
number of times of repetitive rewriting can be increased.
[0019] (3) An information recording method is provided for
repeatedly recording information on a recording medium in
association with both ends of each of marks that are formed to be
different in their physical property from other areas, wherein a
synchronizing signal formed of a plurality of marks is provided at
the head of an information recorded portion, and the number of
marks of the synchronizing signal is changed each time information
is rewritten so that the length of the synchronizing signal can be
substantially randomly changed.
[0020] Thereby, since the region in which the synchronizing signal
is recorded is used as an adjustment region, the position of the
information recorded portion is substantially randomly changed.
Therefore, when repetitive rewriting is made, the total number of
times that the marks and spaces are repeatedly recorded is uniform
over all the medium in each record unit. Consequently, the
recording medium is uniformly changed in the physical property by
the repetitive recording with the result that the possible number
of times of repetitive rewriting can be greatly increased.
[0021] (4) An information recording method is provided for
repeatedly recording information on a recording medium by forming
recorded marks that are different in their physical property from
other areas so that the information corresponds to both ends of
each of the marks, wherein a synchronizing signal having a
plurality of marks and spaces is provided at the head of the
information recorded portion, and each time the information is
rewritten, the number of the marks or the spaces of the
synchronizing signal is changed so that the length of the
synchronizing signal is substantially randomly changed, and the
marks and the spaces between the marks are substantially randomly
reversed in their positions.
[0022] Thereby, when repetitive rewriting is made, the total number
of times that the marks and spaces are repeatedly recorded is more
uniform over the medium, and hence the possible number of times of
repetitive rewriting can be more increased.
[0023] (5) The length of a guard portion which has dummy data and
is provided at the back end of the information recorded portion is
changed depending upon the length of the synchronizing signal
portion. Therefore, the total length of the record unit ranging
from the head of the synchronizing signal portion to the back end
of the guard or dummy data portion is substantially unchanged.
[0024] Thereby, since the total length of the record unit is
substantially unchanged, the change of the beginning end and last
end of information does not affect the information recorded portion
at the center of the information. Therefore, the possible number of
times of repetitive rewriting can be suppressed from being reduced
by the effect of the change of the beginning end and back end of
information.
[0025] (6) Each time the information is rewritten, the information
recording start position is substantially randomly changed.
[0026] Thereby, when repetitive rewriting is made, the total number
of times that the marks and spaces are repeatedly recorded can be
made more uniform over the medium. Therefore, the possible number
of times of repetitive rewriting can be more increased.
[0027] (7) An information recording method is featured in that the
change of the information recording start position is smaller than
that of the length of the synchronizing signal.
[0028] Thereby, the change of the beginning end and back end of
information does not affect the central portion of information, or
the information recorded portion irrespective of the change of the
information recording start position. Consequently, the possible
number of times of repetitive rewriting can be suppressed from
being reduced by the effect of the change of the beginning end and
back end of information. Therefore, the possible number of times of
rewriting can be greatly increased.
[0029] The present invention, in order to achieve the second
object, provides the following aspects.
[0030] (8) An information recording apparatus is provided for
recording information on a recording medium by a structure having
at least a record/reproduce head and a recording pulse generation
circuit, further including at least a random signal generation
circuit, a timing generation circuit, and any one of at least a
polarity inverting circuit for inverting the recording pulse
polarity in accordance with a random signal generated from the
random signal generation circuit, and a synchronizing signal
generation circuit having a function to change the length of the
synchronizing signal.
[0031] Thus, since at least one of the polarity and timing of the
recording pulse can be changed during recording, the total number
of times that the marks and spaces are repeatedly recorded when
repetitive rewriting is made can be made uniform over the medium.
Consequently, the possible number of times of repetitive rewriting
on the recording medium can be increased.
[0032] Here, the recording pulse is not any one of the pulses
themselves of heat, light and magnetic field to be applied to the
medium at the time recording on the medium. The actual pulse to be
applied to the medium is formed after being converted by a
recording pulse shaping circuit or the like into a multi-pulse
train or the like depending on the characteristic of the medium,
and then recorded.
[0033] (9) In addition, the recording pulse is passed through a
synthesizing circuit after the generation of the synchronizing
signal, coded data and dummy data, and then its polarity is
inverted.
[0034] Thus, the polarity can be surely inverted without dependence
on the encoding circuit and system for recording.
[0035] (10) The polarity of the synchronizing signal generated from
the synchronizing signal generation circuit is at least changed in
accordance with the above-mentioned random signal.
[0036] Thus, since the polarity of the recording pulse can be
automatically inverted without additionally providing a polarity
inverting circuit, the apparatus can be fabricated at low cost.
[0037] As described above, according to the present invention,
there is provided an information recording method for recording
information on the medium in a form of an array of recorded marks
so that the "0"s or "1"s of binary information are made associated
with both ends of each of the recorded marks, and featured in that
if the same information is recorded a plurality of times, an array
of recorded marks , recorded on the medium according to the
information includes an array in which the recorded marks and the
spaces between the marks are inverted in their positions.
Therefore, even though the same information is repeatedly recorded
on the medium, the marks are not formed at a particular location,
but can be uniformly formed over the medium by an energy beam, and
thus the life of the recording medium can be expanded.
[0038] Moreover, the recording medium of the invention has formed
along tracks a plurality of sectors each of which has a data region
in which the recording data is recorded, a synchronizing signal
region provided before the data region, and a dummy data region
provided after the data region, the length of the synchronizing
signal region included within each sector being not constant, the
length of the range from the head of the synchronizing signal
region to the back end of the dummy data region being constant.
[0039] Furthermore, a preferred embodiment of the medium has formed
along tracks a plurality of sectors each of which has a data region
in which the recording data is recorded, first and second regions
provided before and after the data region, and an identification
information portion provided before the first region, the length of
the first region within each sector being not constant, the length
of the range from the head of the first region to the back end of
the second region being constant, the distance from the head of the
first region to the back end of the identification information
portion being not constant.
[0040] Thus, the recording medium is deteriorated uniformly by the
irradiation of energy beam, and hence high reliability can be
ensured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIGS. 1A and 1B are a conceptional diagram and a pulse
waveform diagram for explaining one embodiment of an information
recording method of the present invention;
[0042] FIG. 2 is a plan view showing another embodiment of the
information recording method of the present invention;
[0043] FIG. 3 is a plan view showing still another embodiment of
the information recording method of the present invention;
[0044] FIG. 4 is a plan view of showing a further embodiment of the
information recording method of the present invention;
[0045] FIG. 5 is a block diagram of an information recording
apparatus showing an embodiment of the present invention;
[0046] FIG. 6 is a plan view of for explaining one example of the
prior art information recording method;
[0047] FIG. 7 is a graph showing the effect and drawbacks of the
prior art information recording method;
[0048] FIG. 8 is a graph showing the effect of the information
recording method according to the present invention; and
[0049] FIG. 9 is a circuit block diagram of part of the information
recording apparatus according to the embodiment the present
invention in conjunction with FIG. 5.
[0050] Other objects, features and advantages of the present
invention will become apparent from reading of the following
description of embodiments of the invention in conjunction with the
accompanying drawings. Like reference numerals and symbols indicate
like elements, parts or circuits in the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] Embodiments of the invention will now be described in detail
with reference to the drawings.
[0052] (Embodiment 1)
[0053] FIG. 5 shows an information recording apparatus of an
embodiment of the invention. This apparatus includes a
record/reproduce head 32 irradiating to a recording medium 8 an
energy beam that is based on a recording pulse corresponding to
coded recording data of binary information, to form recorded marks
on the medium. The "1"s or "0"s of the binary information are
recorded corresponding to the edges of the recorded marks. This
apparatus also includes a pulse conversion circuit 34 for reversing
the polarity of the recording pulse. The polarity-reversed
recording pulse may be a pulse of which the leading edges and
trailing edges correspond to either "1"s or "0"s of the binary
information. In this embodiment, a phase-change type optical
recording medium (recording film: GeSbTe based material) is used as
the recording medium. Therefore, the laser beam is modulated in its
intensity, and irradiated on the recording medium to form recorded
marks as amorphous portions within a crystal region of the
medium.
[0054] Referring to FIG. 5, there are shown the record/reproduce
head 32 which records and/or reproduces on the recording medium 8,
a detection circuit 33 which detects the reproduced signal from the
record/reproduce head 32, and a reproduction circuit 41 which
reproduces information from the detected signal. The reproduction
circuit 41 has at least an identification information detection
circuit 42 which detects identification information on the medium.
The identification information signal from the identification
information detection circuit 42 is supplied to a timing generation
circuit 40, which then generates various different timing signals
for the recording operations.
[0055] The apparatus of this embodiment also includes at least a
random signal generation circuit 36. The random signal generation
circuit 36 may include a quasi-random sequence generator or may
generate a random signal from the information asynchronous with the
recording and reproduction operations, such as time or date. The
apparatus of this embodiment further includes an encoding circuit
38 which encodes recording information (recording data) 50. This
encoding circuit 38 is not necessarily provided within the
apparatus depending on the recording code.
[0056] This embodiment employs (2, 11) RLL coding. A synthesizing
circuit 35 provided in the apparatus combines the synchronizing
signal from a synchronizing signal generation circuit 37, the coded
data from the encoding circuit 38, and the dummy data from a dummy
data generation circuit 39 in accordance with a timing signal from
the timing signal generation circuit 40, to generate coded
composite data 51 that is to be recorded as recorded units. The
pulse conversion circuit 34 converts the coded composite data 51
into a recording pulse 53 with the polarity depending on the random
signal 52 produced from the random signal generation circuit 36. In
this case, the polarity inversion according to the random signal 52
is made for each record unit. The polarity inversion timing is
controlled by a timing signal 54 from the timing generation
circuit. The recording pulse thus generated is fed to a recording
pulse shaping circuit 31 by which it is converted into a pulse form
suitable for the record/reproduce head and the recording medium.
The shaped pulse is supplied to the record/reproduce head 32 by
which the energy beam according to this pulse is applied to the
recording medium 8 to form recorded marks on the medium.
[0057] With reference to FIGS. 1A and 1B, a description will be
made of the relation between the finally recorded marks and the
coded data in this embodiment.
[0058] Referring to FIG. 1A, a coded data sequence
"0010000100100001000100- " is converted in NRZI-NRZ scheme into a
recording pulse of a form A: "0011111000111110000111 or B:
"1100000111000001111000", by the pulse conversion circuit 34.
[0059] The coded data sequence is, for example, a pulse 51 having
high levels at "1"s as shown in FIG. 1B. The pulse conversion
circuit converts this pulse 51 into a pulse 53A or a pulse 53B with
the polarity opposite to the pulse 53A.
[0060] When the recording pulse 53 is shaped into a multi-pulse
train by the recording pulse shaping circuit 31, and then recorded
on the medium, a mark 6 associated with the "1"s of the recording
pulse and a space 7 corresponding to the "0"s are formed on the
recording medium as illustrated in FIG. 1A. In other words, the
mark 6 and the space 7 between the marks 6 in the recording pulse A
are respectively turned over in the pulse B to be the space 7 and
the mark 6, associated with "0"s and "1"s. Thus, there is no
problem in the reproduction even when the mark and space are turned
over, respectively. This is because the reproduced data from A and
B are the same coded data since the signal corresponding to both
ends of the recorded mark 6, or the boundary between the mark 6 and
the space 7 is detected at the time of reproduction.
[0061] FIG. 9 shows one example of the pulse conversion circuit 34
in this embodiment. When a timing signal 54 is turned to be at a
logical high level, the binary random signal 52 is selected as an
initial value into one input of an exclusive logic sum circuit
EX-OR to the other input of which the coded composite data 51 is
applied. Then, when the timing signal 54 is turned to be at a
logical low level, the exclusive logic sum circuit EX-OR produces
the recording pulse signal 53A or 53B, or an exclusive logic sum of
the output from the exclusive logic sum circuit EX-OR and the coded
composite data including the coded data sequence 51.
[0062] In this embodiment, the beginning end of the record mark is
randomly shifted in addition to the inversion of polarity. This
random shift timing control is made by controlling the output
timing of the synthesizing circuit 35 under the timing generation
circuit 40. The timing generation circuit 40 randomly shifts the
recording start timing in accordance with the signal from the
random signal generation circuit 36.
[0063] FIG. 8 shows jitter characteristics obtained when the same
data is repeatedly recorded on one recording medium according to
this embodiment. In FIG. 8, a curve 81 was obtained when the
recording start position was shifted by two bytes, but when there
was no polarity inversion. A curve 82 was obtained when the
recording start position was similarly shifted by two bytes and
when polarity inversion was made. In this case, the standard
deviation of the time shift between the reproduction clock and the
reproduced data after the same data was recorded repeatedly and
then reproduced was normalized by the reproduction detection window
width and used as the rate of jitter. From FIG. 8, it will be
obvious that even when the recording start position is shifted by a
small value in the order of two bytes, the possible number of times
of rewriting can be increased much more by the additional polarity
inversion in this embodiment than in the conventional apparatus
(with no polarity inversion). In this experiment for the jitter
characteristic, the minimum mark length was selected to be 0.6
.mu.m, and the record/reproduce spot diameter was 0.9 .mu.m.
[0064] According to this embodiment, as described above, the marks
6 having the first optical property and the spaces 7 having the
second optical property are formed on the recording medium, and
information associated with a binary code of "1"s or "0"s is
recorded as an existence of boundary between a mark and a space. In
this recording method, even if the same information is recorded a
plurality of times, both cases in which the boundary corresponding
to a particular binary code of information is changed from mark to
space and changed from space to mark are controlled so as to appear
in a plurality of repeated recording operations. Thus, the
reliability in the recording medium can be increased.
[0065] (Embodiment 2)
[0066] Another embodiment of the invention will be described. The
information recording apparatus of this embodiment is the same as
in FIG. 5. In other words, this apparatus has the record/reproduce
head 32 for recording and/or reproducing on the recording medium 8.
The reproduced signal from the record/reproduce head 32 is detected
by the detection circuit 33, and the detected signal is fed to the
reproduction circuit 41 by which information is reproduced from the
detected signal. The reproduction circuit 41 includes at least the
identification information detection circuit 42 for detecting the
identification information on the medium. The identification
information signal from the identification information detection
circuit 42 controls the timing generation circuit 40 to generate
various different timing signals for the recording operations. The
apparatus of this embodiment also has at least the random signal
generation circuit 36. The random signal generation circuit 36 may
include the quasi-random sequence generator, or may generate the
random signal from the information asynchronous to the recording
and reproduction operations, such as time or date.
[0067] The apparatus of this embodiment further has the encoding
circuit 38 which encodes recording information (recording data) 50.
This encoding circuit 38 is not necessarily provided within the
apparatus depending on the recording code.
[0068] This embodiment employs (2, 11) RLL coding. The synthesizing
circuit 35 provided in the apparatus combines the synchronizing
signal from the synchronizing signal generation circuit 37, the
coded data from the encoding circuit 38, and the dummy data from
the dummy data generation circuit 39 in accordance with the timing
signal from the timing signal generation circuit 40, to generate
the coded composite data 51 that is to be recorded as recorded
units. The synchronizing signal generation circuit changes the
length of the synchronizing signal in accordance with the random
signal generated from the random signal generation circuit 36. The
dummy data generation circuit changes the length of the dummy data
in accordance with the random signal generated from the random
signal generation circuit 36. The pulse conversion circuit 34
converts the coded composite data 51 into the recording pulse 53 of
a particular polarity. In other words, such polarity inversion as
in the previous embodiment is not made. Thus, the generated pulse
is converted into a pulse suitable for the actual record/reproduce
head and recording medium by the recording pulse shaping circuit
31, and the record/reproduce head 32 applites the energy beam
according to the shaped pulse on the recording medium 8 to form the
recorded marks on the medium.
[0069] In this embodiment, the recording information is recorded to
be arranged on the recording medium as illustrated in FIG. 2. In
other words, the synchronizing signal portion 22 which may be
considered as a guard portion is placed at a position separated
about a certain distance from the identification information 24
that indicates the head of the sector 21, and the length of the
synchronizing signal portion 22 is changed at each sector 21. The
synchronizing signal portion 22 is followed by the information
recorded portion 23 and the guard portion 25 in this order. The
length of the synchronizing signal portion is changed in accordance
with the random signal generated from the random signal generation
circuit 36. The length of the dummy data is changed by the dummy
data generation circuit 39 in accordance with the random signal
generated from the random signal generation circuit 36. At this
time, the distance from the head of the synchronizing signal to the
back end of the guard portion is kept substantially constant.
[0070] Thus, even if the data in the information recorded portion
is the same as in the previous recording, the information recorded
portion 23 can be moved back and forth so that the position of the
information recorded portion 23 on the medium is randomly changed.
As a result, the total number of times of recording marks and
spaces is kept uniform over all positions on the recording medium.
Thus, the change of the recording medium due to the repeated
recording can be averaged so that the possible number of times of
repeated rewriting can be increased similarly to the prior art that
is the mark position recording, although this embodiment is the
mark-edge recording. In this case, since the recording start
position and recording end position are respectively maintained to
be substantially unchanged unlike the operation of the conventional
apparatus. Therefore, even if the amount of shift of the
information recorded portion 23 is selected to be about 30 to 100
bytes, the change of the recording and reproduction characteristic
of the medium at around the recording start point and recording end
point does not affect the recorded portion. Accordingly, the
information recorded portion 23 can be easily shifted by a large
amount, thus making it possible to increase the possible number of
times of rewriting.
[0071] According to this embodiment, there is provided an
information recording method in which a record mark is formed in
the data region of the recording medium, and information is
recorded in association with both ends of the record mark, as
described above. In this method, first and second adjustment
regions are provided at the front and back ends of the data region,
and changed in their lengths so that the data region is shifted in
its position. In addition, when the same information is recorded a
plurality of times, the arrays of a plurality of record marks
formed on the recording medium in association with the same
information include opposite arrays in which the record marks and
the spaces between the record marks are inverted as opposed to the
former arrays.
[0072] (Embodiment 3)
[0073] This embodiment employs the same apparatus as Embodiment 2.
The length of the synchronizing information is changed. In this
case, the synchronizing information includes a first synchronizing
information portion 221 (VFO) that has marks 6 and spaces 7 of the
same length alternately and repeatedly arranged in turn, and the
length of the synchronizing information portion 221 and its
polarity at the end are changed. Specifically, the polarity is
automatically changed depending on whether the total number of
marks and spaces is even or odd. In addition, a second
synchronizing information portion 222 (SYNC) is provided to follow
the first synchronizing information portion 221. This second
synchronizing information portion 222 has a fixed pattern, but its
polarity is changed depending on the polarity of the final end of
the first synchronizing information portion 221.
[0074] FIG. 3 shows examples (A), (B) of the first synchronizing
information portion 221 in which the total number of marks and
spaces is odd, and an example (C) of the first synchronizing
information portion 221 in which the total number of marks and
spaces is even.
[0075] Since this embodiment is capable of making polarity
inversion without any polarity inverting circuit, the recording
apparatus is simple in construction. In addition, since the
information recorded portion 23 can be shifted in its position, the
accumulated number of times that the marks and spaces are recorded
is more uniform over the recording medium. Thus, the medium is more
uniformly changed by repeated recording with the result that the
possible number of times of repeated rewriting can be increased
more than in Embodiment 1.
[0076] (Embodiment 4)
[0077] This embodiment employs the same apparatus as Embodiment 3.
As shown in FIG. 4, the length of the first synchronizing
information portion 221 is randomly changed, and also the recording
start position of the first synchronizing information portion 221
is changed in accordance with the random signal. The amount of
shift of the recording start position is substantially equal to the
length of the marks (-1/4 byte) within the first synchronizing
information portion 221. Thus, since the total number of times at
which the marks and spaces within the synchronizing information
portion are recorded is uniform over all the medium, the possible
number of times of repeated rewriting is increased more than in
Embodiment 3. In addition, since the amount of shift of the
recording start position is small enough, the recording start
position can be considered not to be changed from the standpoint of
the change of recording and reproduction characteristics at around
the recording start position. Thus, there is no adverse effect of
shift which appears in the prior art.
[0078] Since the marks and spaces are repeatedly recorded while
they are turned over at each repetition, the total number of times
by which the marks and spaces are repeatedly recorded, or rewritten
is uniform over all the recording medium. Thus, the recording
medium is uniformly changed by repetitive recording so that the
possible number of times of repeated rewriting can be greatly
increased. This does not reduce the information recording
efficiency at all. In addition, since the position of the
information recorded portion on the medium is randomly changed when
the length of the synchronizing signal portion at the head of the
information recorded portion is randomly changed, the total number
of times by which the marks and spaces are repeatedly recorded is
uniform over all the medium. Therefore, the recording medium is
uniformly changed by repetitive recording, and hence the possible
number of times of repetitive rewriting can be increased.
* * * * *