Dynamic information storage or retrieval – Binary pulse train information signal – Binary signal processing for controlling recording light...
Reexamination Certificate
1999-03-23
2002-10-01
Hindi, Nabil (Department: 2653)
Dynamic information storage or retrieval
Binary pulse train information signal
Binary signal processing for controlling recording light...
C369S059240, C369S047510
Reexamination Certificate
active
06459670
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical information recording method and an optical information recording device which form mark by irradiating light on a record medium and records information.
There is a phase change type optical disk which performs recording by using a phase change between a crystal and an amorphous caused by thermal as one of an optical record medium in which light is irradiated thereon, thereby a mark capable of optically being identified is formed by thermal generated therefrom, and is recorded. The record film of the phase change type optical disk is a crystal in a steady state. However, a region where the light is irradiated gives rise to the phase change to the amorphous by being cooled after heated and melted. An information can be recorded by forming an amorphous part as a mark by using this principle. In such a phase change type optical disk, a PWM (Pulse Width Modulation) method which makes correspondence to binary information which records the position of beginning and termination of the mark is effective to improve the record density.
In general, when a long mark is formed to decrease a thermal storage effect according to the irradiation of light in a case that the PWM scheme is applied to the optical disk, a so-called multi-pulse is recorded by using a divided plurality of optical pulses not a single optical pulse as the irradiation light. An example of such a multi-pulse record is shown in FIG.
1
A and FIG.
1
B. FIG.
1
A and
FIG. 1B
are examples when information is recorded by {fraction (8/16)} modulation code, and the mark length becomes a discrete value of 3T to 14T for record window width T.
According to FIG.
1
A and
FIG. 1B
, the short mark of 3T in length (hereinafter, mark of 3T in length is called “short mark” for convenience sake about the explanation) which is the shortest mark is recorded by the single pulse of 1.5T in width as shown in FIG.
1
A. However, the long mark of length 4T or more (hereinafter, length 4T or more mark is called “long mark” for convenience sake about the explanation) has the period when only the amount of long or more than 3T mark repeats a peak power level period of 0.5T and an erasing power level period of 0.5T after. a leading pulse of width 1.5T shown in FIG.
1
B. That is, when the long mark is recorded, the following pulse of 0.5T in width is added and formed, and the pulse width (time from start of a leading pulse to the end of the following final pulse in case of the multi-pulse) to form the mark increases T when the recorded mark length increases to T more than the shortest mark length.
However, there is a disadvantage in which the position of the beginning and the termination of the mark actually formed changes from the planned position depending on the length of the mark length even if such a multi-pulse is recorded. The beginning position and the termination position shift in a direction where the long mark is shortened compared with the short mark as for the formed mark, even when the irradiation starting or the irradiation completion of a light pulse is performed according to the same timing as shown from
FIG. 2A
in
FIG. 2C
for example according to only the mark length and the length at mark intervals.
That is, when the irradiation of light is started on the same timing when the short mark and the long mark are formed, both of them become the same heating condition until the leading pulse irradiation is completed. When a short mark which uses only a leading pulse is formed, the region where the medium is heated and melted is cooled as it is and becomes an amorphous. The beginning position of the mark shifts in the direction where the mark length is shortened, since the region which is heated and melted by a leading pulse receives re-heating by the irradiation of the following pulse, and the re-crystallization in the peripheral section of an amorphous region is accelerated when the long mark which uses the multi-pulse record is formed.
On the other hand, when an optical irradiation is completed when the short mark and the long mark are formed at the same timing, both of the temperature distributions when an optical irradiation is completed by a thermal characteristic of the medium are not always the same. The reason is as follows. The medium temperature immediately after heating by the following pulse lowers more than the medium temperature immediately after heating by a leading pulse when the long mark is formed. Therefore, a melted region of the optical irradiation end becomes small. As a result, the termination position of the mask shifts in the direction where the mark length is shortened as for the long mark.
The beginning position and the termination position of the long mark shift in the direction where the mark length is shortened more than the beginning position and the termination position of the short mark like this. It becomes necessary to perform some record compensation to avoid the shift of the beginning position and the termination position of the mark according to the mark length, and to accurately form the mark. As this record compensation method, a method of forming the mark by moving the leading pulse and the final pulse positions of the irradiation light pulse beforehand according to the length of the mark which intends to be formed is proposed.
However, it is necessary to change and generate an optical pulse from the clock synchronization state in this record compensation method, and it is necessary to change the amount of the change (that is, amount of the move at the position of the leading and the end by the length of the mark) according to the mark length. The disadvantage in which coexisting of accuracy and the cost becomes difficult occurs, since a complex circuit like the programmable delay line is needed.
As mentioned above, in the conventional record compensation method by which the position of the leading and the end of the irradiation light pulse is moved and generated beforehand according to. the length of the mark and the mark is formed to avoid the shift of the beginning position and the termination position of the mark according to the length of the mark and to form the mark in accuracy, there is a disadvantage that a complex circuit is necessary to change the amount of the change and it is difficult to make the accuracy of the formed mark and the cost united, by the change of an optical pulse from the clock synchronization state and the occurrence according to the mark length,.
BRIEF SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an optical information recording method and the optical information recording device which have the record compensation method by which the accuracy of the mark formed without accompanied by a big cost increase is enabled to be improved.
Another object of the present invention is to provide an optical information recording method and an optical information recording device which have the compensation method for the record which can improve the position accuracy of the mark formed even when the line record density is different.
An optical information recording device according to the present invention forms a mark, in which the mark indicating record information is formed by irradiating a record light pulse on a record medium, by controlling a strength of the record light pulse according to both of a mark length of the mark and a record density in a mark length direction of the record medium.
Another optical information recording device according to the present invention forms a mark, in which the mark indicating record information is formed by irradiating a record light pulse on a record medium, by controlling a pulse width of the record light pulse according to both of a mark length of the mark and a record density in a mark length direction of the record medium.
Still another optical information recording device according to the present invention forms a mark, in which the mark indicating record information is formed by irradiating a record light pulse
Hasegawa Hiroshi
Kuwahara Maho
Hindi Nabil
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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