Dynamic information storage or retrieval – Binary pulse train information signal – Having specific code or form generation or regeneration...
Reexamination Certificate
2002-07-08
2003-06-17
Hindi, Nabil (Department: 2655)
Dynamic information storage or retrieval
Binary pulse train information signal
Having specific code or form generation or regeneration...
C369S275300
Reexamination Certificate
active
06580673
ABSTRACT:
BACKGROUND OF THE INVENTION
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.
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.
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.
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.
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.
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.
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 &mgr;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 &mgr;m. In addition, the diameter of the recording and reproducing spot was 0.9 &mgr;m, and the recording medium used was a GeSbTe-based phase-change recording medium.
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
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.
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.
The present invention, in order to achieve the first object, provides the following aspects.
(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.
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.
(2) The substantially random inversion is made at each record unit.
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.
Thereby, the total number of times that marks are recorded in each record unit is uniform over the record unit. 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.
(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.
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
Minemura Hiroyuki
Miyamoto Harukazu
Miyauchi Yasushi
Antonelli Terry Stout & Kraus LLP
Hindi Nabil
Hitachi , Ltd.
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