JP2908012B2 - Information recording method and information recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for recording information on a recording member capable of recording information by irradiating an energy beam, and in particular, to a new method for erasing existing information while erasing existing information. Information recording method and apparatus that exhibit excellent effects on overwrite-capable phase change optical discs for recording information [Prior art] Conventional recording / erasing methods for rewritable recording films include:
For example, when a recording film for a high-speed erasable optical disk that can be crystallized in approximately the same time as the laser irradiation time for recording shown in JP-A-56-145530 is used, This has been done by changing the power of one energy beam between at least two levels, both higher than the read power level, at least between a high power level and an intermediate power level. This method has an advantage that so-called overwriting (rewriting by overwriting) in which new information is recorded while erasing existing information is possible.

[Problems to be solved by the invention]

When recording is performed using the above-described conventional technique, a recording signal (original signal) is used as in the 2-7 modulation mark edge detection recording method.
In the recording waveform where the high level part continued, the temperature was higher in the later irradiated area due to the heat accumulation effect,
The recording mark has a teardrop shape. As a result, there are problems such that the S / N is reduced, the remaining erase is increased, and a reproduced signal properly corresponding to the recording signal cannot be obtained. Further, when rewriting is repeated many times, there is a problem that the thickness of the recording film fluctuates due to the flow of the recording film in one direction, thereby increasing the noise level.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for recording information which solves the above-mentioned problems in the prior art and enables rewriting many times.

[Means for solving the problem]

In order to solve the above-mentioned problems in the prior art,
In the information recording method and apparatus of the present invention, the average irradiation energy near the center of a pulse for forming a recording mark is reduced. Here, in order to prevent the temperature of the recording film near the rising portion of the recording pulse from becoming too low, the center of the portion where the average irradiation energy is low should be located after the center of the recording pulse. Therefore, the average irradiation energy is reduced from the rise of the recording pulse to the pulse width.
It is preferably after 20% or more, particularly preferably after 40% or more. It is preferable to increase the average irradiation energy again after 70% or more of the pulse width has elapsed,
It is particularly preferable after the above-mentioned time has elapsed.

A recording medium composed of at least one selected from recording media containing In-Sb-Te, In-Sb, and Ge-Sb-Te as main components is preferable.

Here, if the pulse waveform is such that the average irradiation energy at the center of the recording mark is low, for example, the power level is constant, and between a middle power level (erasing level) and a high power level (recording level). The pulse density may be changed by dividing into several pulse waveforms, or may be changed to a lower power level than a higher power level so that the vicinity of the center of the recording pulse becomes lower.

The above operation has been described with respect to the case where a crystal-amorphous phase change optical recording medium capable of high-speed crystallization is used. It is also effective for a crystal-crystal phase change recording medium such as a change in particle size and a magneto-optical recording medium.

In the recording waveform of the present invention, even if the power level is arbitrarily changed to another power level (for example, 0 level or read power level) for a short period of time, the temperature of the recording film at the irradiated portion hardly follows, and such a change does not occur. You can expect the same result as without.

On the other hand, a high-speed change such that the temperature of the recording film hardly follows the recording waveform of the present invention may be superimposed, and the change in the average power may be the pattern described above in the present invention. .

The present invention naturally applies to at least one laser beam when recording is performed by irradiating the same or different patterns with two or more laser beams (two or more light spots).

The energy beam for recording is not limited to a light beam such as a laser, and other energy beams such as an electron beam and an ion beam can also be used according to the properties of a reversible recording film. However, the present invention can be applied to other types of recording media such as a tape and a card.

A method of dividing a recording pulse into a plurality of pulses when one recording mark is formed on a recording medium corresponding to one recording pulse is disclosed in JP-A-61-237233 and JP-A-62-237233.
No. 8371, JP-A-61-113154, JP-A-61-2161
No. 26, JP-A-63-363632, JP-A-63-266633
This is also disclosed in Japanese Patent Publication No.

[Action]

In the present invention, by lowering the average irradiation energy of the central part of the pulse forming the recording mark, the temperature of the recording film does not rise more than necessary, and the recording mark does not become a teardrop-shaped. Therefore, a reproduction signal faithful to the recording signal can be obtained, and the unerased portion can be reduced. Even if rewriting is performed many times, the flow in the area where the recording mark is formed occurs in both the traveling direction of the light spot and the opposite direction. Therefore, a change in the thickness of the recording film due to rewriting is suppressed, and an increase in the noise level is suppressed.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

Embodiment 1 FIGS. 1 to 3 are explanatory diagrams of an embodiment of the present invention.

First, an example of a structural sectional view of a disk used in the information recording method of the present invention will be described with reference to FIG. First, an Si ₃ N ₄ protective film 2 having a thickness of about 100 nm was formed on a polycarbonate substrate 1 having a guide groove (track) having a diameter of 13 cm and a thickness of 1.2 mm by magnetron sputtering. Next, Si ₃ N
₄ on the protective film 2 in the same sputtering apparatus Ge ₁₃ Sb ₃₀ Te
A recording film 3 having a composition of ₅₇ was deposited to a thickness of about 30 nm. Next, the Si ₃ N ₄ protective layer 4 is again set to about 220 nm in the same sputtering apparatus.
Was formed. Further, a Ni-Cr reflective film 5 was formed thereon by 100 nm in the same sputtering apparatus. Thereafter, the resultant was bonded to another disk having the same structure via the adhesive layer 6.

Next, the recording method of the present invention will be described with reference to FIGS. 1 (1) to (5).

First, an optical disc having the Ge ₁₃ Sb ₃₀ Te ₅₇ recording film was used.
Rotating at 1800 rpm, semiconductor laser light (continuous light with a wavelength of 830 nm) at an intermediate power level between the intermediate power level (P _M ) and the high power level (P _H ) while performing automatic focusing and tracking on the recording track To perform initialization. On the initialized recording track, automatic focusing and tracking are performed at the read power level (P _R ), and while confirming the recording location, the laser power is adjusted as shown in the recording waveform of FIG. Recording was performed by raising and lowering. Here, a mark edge detection recording method of 2-7 modulation was used.
In the case of such a modulation method, the time during which the power is maintained at a high power level (P _H ) may be long. In such a case,
In the conventional method, the recording pulses B are all kept at a high power level (P _H ). When recording is performed with such a recording waveform, the temperature of the recording film rises as the position is irradiated later due to the heat storage effect, resulting in a teardrop-shaped recording mark. Further, when rewriting is performed many times, a flow in one direction occurs in a portion of the recording film irradiated with the pulse, and a change in the film thickness of the recording film occurs. Therefore, in the present invention, in order to prevent this, as shown in FIG. 1 (2), the average irradiation energy at the central portion of the recording pulse is reduced. In this example, for the sake of simplicity, the average irradiation energy within a time period in which the recording pulse A is divided into three equal parts and the recording pulse B is divided into five equal parts is shown. Here, the recording pulse is divided into several pulses so as to increase the average irradiation energy at the central portion, but it is not necessary to divide all the pulses, for example, the shortest recording pulse may not be divided in some cases. . When rewriting is performed with a recording pulse train as shown in FIG. 1 (1), the temperature of the highest temperature portion of the light irradiation area shows a temporal change as shown in FIG. 1 (3). As a result, a recording mark as shown in FIG. 1 (4) was formed. That is, the recording mark was not a teardrop-shaped recording mark, but an oval shaped in the track direction and having a correct edge position. When this was reproduced, a reproduced signal corresponding to the recording mark was obtained as shown in FIG. 1 (5). In addition, even when the rewriting was performed many times, the change in the recording film thickness due to the flow was averaged, and the increase in the noise level due to the rewriting many times was suppressed.

There are several other methods for dividing a long pulse, but in all cases, it is necessary to lower the average irradiation energy at the center of the recording pulse. The average irradiation energy is an average value within an arbitrary unit time shorter than the pulse width, and the averaged time width may be appropriately changed each time since the disk diameter and the rotation speed differ depending on the device.

FIG. 3 and FIG. 4 show examples of another recording waveform for lowering the average irradiation energy near the center of the recording pulse. In this example, instead of dividing the recording pulse into several pulses at a constant power level, a high power level (P _H ) and an intermediate power level are set so that the average irradiation energy is low near the center of the recording pulse. A similar effect is obtained by holding each of the different power levels during (P _M ) for a certain period of time. In order to prevent the temperature of the recording film near the rising portion of the recording pulse from becoming too low, the center of the portion where the average irradiation energy is low as shown in FIG. 5 should be located after the center of the recording pulse. . It is preferable that the average irradiation energy is reduced after elapse of 20% or more of the pulse width from the rise of the recording pulse, and particularly preferable after elapse of 40% or more.
It is preferable to increase the average irradiation energy after a lapse of 70% or more of the pulse width from the rise of the recording pulse.
It is particularly preferable after 80% or more has passed.

〔The invention's effect〕

According to the present invention, even when recording is performed with a recording waveform in which a high-level portion continues as a recording signal (original signal) as in the 2-7 modulation mark edge detection recording method,
A reproduced signal faithfully corresponding to the recorded signal was obtained, and the unerased portion could be reduced. Further, even when rewriting is repeated many times, the flow of the recording film in one direction can be suppressed, so that the noise level does not increase due to the rewriting many times.

Further, the recording method and apparatus of the present invention are effective not only for disk-shaped recording media but also for other forms of recording media such as tapes and cards.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a recording method according to the present invention, FIG. 2 is a sectional view of the structure of a disk used in the present invention, and FIGS. FIG. 3 is a diagram showing an example for reducing the average irradiation energy. 1,1 ′… Polycarbonate substrate, 2,2 ′… Si ₃ N ₄ protective layer,
3,3 ′… Ge ₁₃ Sb ₃₀ Te ₅₇ recording film, 4,4 ′… Si ₃ N ₄ protective layer, 5,5
... Ni-Cr reflection film, 6 ... adhesive layer.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/00 G11B 7/125

Claims (16)

(57) [Claims] 1. A method for recording information in which one recording mark is formed on a recording medium in response to one recording pulse by irradiating an energy beam, wherein n (here, n ≧ 5) recording pulses are provided. When the recording pulse is divided into a plurality of pulses, the average irradiation energy within a time obtained by dividing the recording pulse into n equal parts has at least three levels, and the level of the average irradiation energy from the end to the center of the recording pulse is A method for recording information, characterized in that the information is reduced. 2. The information recording method according to claim 1, wherein the power of the energy beam between the n pulses has reached an erasing power level. 3. The information recording method according to claim 1, wherein a period in which the energy beam is at an erasing power level is provided between the recording pulse and the next recording pulse. 4. A method for recording information in which one recording mark is formed on a recording medium in response to one recording pulse by irradiating an energy beam. A second period, wherein the first level is maintained at a first level lower than the recording level and the second level is maintained at a second level lower than the first level, between the first period and the second period; And a period in which the first level and the second level decrease in order from the end of the recording pulse toward the center thereof. 5. The information recording method according to claim 4, wherein said first and second levels are higher than an erasing power level. 6. The information recording method according to claim 4, wherein a period in which the energy beam is at an erasing power level is provided between the recording pulse and the next recording pulse. 7. A method for recording information in which one recording mark is formed on a recording medium in response to one recording pulse by irradiating an energy beam, wherein n (here, n ≧ 5) recording pulses are used. When the pulse is divided into two pulses, the pulse width of the second pulse of the n pulses is smaller than the pulse width of the first pulse, and the pulse width of the (n-1) th pulse of the n pulses is n A method for recording information, characterized in that the pulse width is narrower than the pulse width of the first pulse. 8. The information recording method according to claim 7, wherein the pulse width of the n pulses is gradually reduced from the end of the recording pulse toward the center. 9. An information recording apparatus for irradiating an energy beam to form one recording mark on a recording medium in response to one recording pulse, wherein said recording pulse is n (here, n
≧ 5) control means for controlling the energy beam so that, when divided into n pulses, the average irradiation energy within a time obtained by equally dividing the recording pulse into n has at least three levels; Means for controlling the energy beam so that the level of the average irradiation energy decreases from the end of the recording pulse toward the center thereof. 10. The information recording apparatus according to claim 9, wherein the power of the energy beam between the n pulses has reached an erasing power level. 11. The energy beam control device according to claim 9, wherein said control means controls said energy beam so as to provide a period in which said energy beam is at an erasing power level between said recording pulse and the next recording pulse. The information recording device according to any one of the above. 12. An information recording apparatus for irradiating an energy beam to form one recording mark on a recording medium in response to one recording pulse, wherein the recording device records the energy beam when forming the recording mark. And a first period lower than the recording level between the first period and the second period.
And control means for controlling the energy beam so as to have a period of maintaining the energy beam at a second level lower than the first level and a period of maintaining the energy beam at a second level lower than the first level. An information recording apparatus, wherein the control is performed such that the levels are decreased in order of the first level and the second level toward a center. 13. The information recording apparatus according to claim 12, wherein said first and second levels are higher than an erasing power level. 14. The control unit according to claim 12, wherein a period in which the energy beam is set to an erasing power level is provided between the recording pulse and the next recording pulse.
14. The information recording device according to any one of 13. 15. An information recording apparatus for forming one recording mark on a recording medium in response to one recording pulse by irradiating an energy beam, wherein said recording pulse is generated by n (here, n ≧ 5) recording pulses. When divided into pulses, control means for controlling the energy beam so that the pulse width of the second pulse of the n pulses is narrower than the pulse width of the first pulse, An information recording apparatus, wherein the energy beam is controlled so that the pulse width of the (n-1) th pulse among the n pulses is smaller than the pulse width of the nth pulse. 16. The energy beam control device according to claim 15, wherein said control means controls said energy beam such that the pulse width of said n pulses is gradually reduced from an end of said recording pulse toward a central portion thereof. Information recording device.