JP2941703B2 - Information recording method and information recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method using an information recording member whose information can be rewritten by irradiation of an energy beam such as light or an atomic beam. In particular, a method of recording and erasing information by a single laser beam, a method of recording information effective on a rewritable phase-change optical disc, and
It concerns the device . 2. Description of the Related Art A conventional recording / erasing method for a phase-change optical disk recording medium is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 59-71140. In this method, when erasing information that has already been recorded by crystallizing the recording film, it is performed by maintaining a temperature at which crystallization can be performed for a relatively long time using an oval light spot that is long in the track direction. Thereafter, new information was recorded by modulating the power of a sufficiently focused circular light spot with an information signal. However, recently, the inventors of the present invention by improving the material used for the recording film, the crystallizing while sufficiently condensing the circular light spot passes over one point on the disk Made it possible. For this reason, it has become possible to perform recording by first erasing with one rotation of the disk and modulating and irradiating the laser power with the next rotation by the circular light spot. Further, by modulating the laser power between the crystallization power level and the amorphization power level in accordance with the information signal, it has become possible to rewrite information in one rotation of the disk. However, in the above prior art, when the rotation speed of the disk is increased to increase the information transfer speed, the speed of the atomic arrangement change (for example, crystallization) of the recording film is reduced. Even if the crystal is melted by irradiation with an energy beam (eg, a laser beam), the atomic arrangement returns to its original state during cooling after irradiation (eg, recrystallization), and the atomic arrangement changes in the opposite direction (eg, recrystallization). (For example, amorphization) cannot be performed. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to use a recording film having a high phase change speed.
A method and method that can surely cause a reversible phase change
And equipment . It is an object of the present invention to form a recording point with one or a plurality of pulses having a pulse width shorter than the time required for the center of the energy beam spot to pass from one end of the recording point to another. Achieved by: It is more preferable that the pulse has a pulse width smaller than 3/4 of the time required to pass from one end to the other end, and it is more preferable that the pulse has a pulse width smaller than 1/2. A pulse is particularly preferable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By narrowing the pulse width as described above, thermal diffusion due to heat conduction from an irradiated portion to its surroundings can be prevented, and the irradiation beam energy can be relatively reduced. Therefore, the cooling rate after irradiation can be increased. The present invention has a problem that when information is overwritten by a single laser beam (rewriting is performed by overwriting without erasing in advance), the cooling rate after laser beam irradiation tends to be low. So we will solve
Especially effective. [0008] The recording medium to which the present invention is applied may be one which causes a phase change between a crystal and an amorphous phase, or one which causes another change in the atomic arrangement. For example, one of the atomic arrangement changes is effective for a crystal-to-crystal atomic arrangement change requiring rapid cooling or an amorphous-to-amorphous atomic arrangement change. The present invention is effective irrespective of the type of energy beam, and can use light, electron beam, ion beam and the like. However, in the case of an electron beam or an ion beam, the thickness of the protective film formed on the recording film of the recording medium is preferably 1 μm or less, more preferably 1,000 or less. Hereinafter, the present invention will be described with reference to examples. [0011] Both sides of a recording film mainly composed of In and Se are sandwiched between protective films of SiO ₂ for performing recording and erasing reversibly by a phase change between a crystalline state and an almost amorphous state. The structure was formed on a disk-shaped glass substrate having an ultraviolet curable resin layer on the surface. Tracking grooves and bits representing addresses are transferred to the surface of the ultraviolet curable resin layer. Next, an ultraviolet curable resin was applied on the above protective film, bonded to another glass substrate, and cured by ultraviolet light. Next, this optical disk is rotated at a rotational speed of 600 rpm.
And searched for a location to record while performing tracking and autofocusing. Where to record,
After raising the power of the laser beam from the read power level to the crystallization power level, the power was varied as shown in FIG. The upper part of FIG. 1 shows an arrangement of amorphous points formed on the recording track. The other portions on the tracks are crystallized, and the space between the tracks is in an as-depo state (as deposited). Actually, the position of the light spot does not move,
The points on the disk move to the left, but the points on the disk are shown stationary and the light spot moves to the right. In the lower diagram of FIG. 1, the horizontal axis corresponds to the horizontal position of the center of the light spot in the upper diagram, and indicates the laser power applied to each point when the light spot moves to the right. I have. In a place where the film is to be made amorphous according to the information signal, the power is raised to the amorphous level for a short time. The time width during which the laser power rises to the amorphization level is about ／ of the time required for the center of the light spot to pass from end to end of the corresponding amorphization point (a region having lower crystallinity than the surroundings). ing. However, the time width during which the power rises is defined as the width of the point at half the pulse height from the crystallization level. The irradiated portion on the disk is melted by the laser light irradiation at the amorphizing power level and rapidly cooled to become amorphous. When recording information including a pulse having a length twice or more the length of the shortest pulse, the original recording waveform is divided into a plurality of short pulses as shown in the center of the waveform in FIG. Irradiate. In the example of FIG. 1, the irradiated portion forms a long amorphized portion in which three amorphized portions adhere to each other. When divided into such short pulses, the power between the pulses is preferably lower than the crystallization power level, and the power is preferably set to 0 or the read power level. However, depending on the composition of the recording film and the material of the protective film, the crystallization power level may be reduced to a level slightly higher than the crystallization power level. It is particularly preferable that the narrower the interval between the pulses, the greater the way in which the power of that portion is reduced. FIG. 1 shows a case where the read power level is lowered. Even if the information to be recorded has a part with a long pulse width, forming a recording pattern on a disk that gives a reproduction signal that is faithful to the original signal by irradiating it in this way by dividing it into multiple pulses Can be. When the information to be recorded has only a portion with a short pulse width, the division into a plurality of pulses as described above is not necessary. The laser power waveform of the present embodiment is a waveform that allows information to be rewritten by overwriting that does not need to be erased in advance, that is, a waveform that can be overwritten. It is more preferable that the time width during which the laser power rises to the amorphization level be equal to or less than 1/2 of the time required for the center of the light spot to pass from one end of the corresponding amorphization point to the other. It is particularly preferable to set the number to 4 or less since the amorphous state can be completely achieved. In the case where the entire track is crystallized and erased by continuous laser beam irradiation and then erased, and then recording is performed with a laser beam power-modulated between a read power level and an amorphized power level, a pulse is similarly applied. Preferably, the width is reduced. However, in this case, the cooling rate is originally high even though the power is always reduced to the read power level between the pulses. The effect is therefore not as pronounced as in the case of single beam overwriting. In the case of single beam overwriting, the crystallization power level is set to 30 to 9 with respect to the amorphous power level.
If the adjustment is made in the range of 5%, a reproduced signal can be obtained irrespective of the width of the time width at the amorphizing power level. 5
A range of 5 to 90% is a more preferable range. In this embodiment, the recording is considered to be amorphous, but the viewpoint may be changed so that the crystallization is regarded as recording. According to the present invention, even if a recording film capable of changing the atomic arrangement at a high speed is used, the atomic arrangement can be changed in the opposite direction, so that the information transfer speed can be increased. Moreover, overwriting with a single laser beam is possible, which is extremely advantageous for recording and reading a large amount of information.

[Brief description of the drawings] FIG. 1 is a diagram showing the operation principle of one embodiment of the present invention.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroshi Yasuoka               1-280 Higashi Koikebo, Kokubunji-shi, Tokyo               Central Research Laboratory, Hitachi, Ltd. (72) Inventor Keikichi Ando               1-280 Higashi Koikebo, Kokubunji-shi, Tokyo               Central Research Laboratory, Hitachi, Ltd. (72) Inventor Norio Ota               1-280 Higashi Koikebo, Kokubunji-shi, Tokyo               Central Research Laboratory, Hitachi, Ltd.                (56) References JP-A-59-22239 (JP, A)                 JP-A-56-148740 (JP, A)                 JP-A-63-266633 (JP, A)

Claims (1)

(57) [Claims] A recording medium capable of causing the energy beam to enter a first state at a first power level and a second state at a second power level lower than the first power level;
A method of recording information by recording information on the recording medium by overwriting as a length and an interval of a recording point in the first state, the method comprising: moving the recording medium relative to the energy beam; When recording the recording point of the length, the recording is performed with one pulse reaching the first power level, and the first and second pulses reaching the first power level are recorded .
Each pulse on the recording medium is generated by three pulses in the second and third order.
A long recording part where the recording parts of Lus stuck together
When forming, the second pulse is interposed between the first and second pulses.
To a level lower than the power level of
The second power level is between the second and third pulses.
A method of recording information characterized by reaching a lower level . 2. A recording medium capable of causing the energy beam to enter a first state at a first power level and a second state at a second power level lower than the first power level;
A method of recording information by recording information on the recording medium by overwriting as a length and an interval of a recording point in the first state, the method comprising: moving the recording medium relative to the energy beam; When recording the recording point of the length, the recording is performed with one pulse reaching the first power level, and the first and second pulses reaching the first power level are recorded .
Each pulse on the recording medium is generated by three pulses in the second and third order.
A long recording part where the recording parts of Lus stuck together
When forming, the second pulse is interposed between the first and second pulses.
To a level lower than the power level of
The second power level is between the second and third pulses.
The time width of one pulse reaching the first power level when recording the recording point having the shortest length is determined by performing an operation of reaching a lower level, and the energy beam is emitted from one end of the recording point. A method for recording information, wherein the time is shorter than the time required to pass to the other end. 3. A recording medium capable of turning the energy beam into an amorphous state at a first power level and into a crystalline state at a second power level lower than the first power level,
A method for recording information in which information is recorded on the recording medium by overwriting as the length and interval of recording points in the amorphous state, wherein the recording medium is moved relatively to the energy beam, When recording the recording point of the length, the recording is performed with one pulse reaching the first power level, and the first and second pulses reaching the first power level are recorded .
Each pulse on the recording medium is generated by three pulses in the second and third order.
A long recording part where the recording parts of Lus stuck together
When forming, the second pulse is interposed between the first and second pulses.
To a level lower than the power level of
The second power level is between the second and third pulses.
A method of recording information characterized by reaching a lower level . 4. 2. The information recording method according to claim 1, wherein the second power level is in a range of 30% to 90% of the first power level. 5. 3. The information recording method according to claim 2, wherein the second power level is in a range from 30% to 90% of the first power level. 6. 4. The information recording method according to claim 3, wherein the second power level is in a range of 30% or more and 90% or less of the first power level. 7. A recording medium capable of causing the energy beam to enter a first state at a first power level and a second state at a second power level lower than the first power level;
What is claimed is: 1. An information recording apparatus for recording information on a recording medium by overwriting as information on a length and an interval of a recording point in the first state, comprising: means for generating the energy beam; Means for relatively moving, and when recording a recording point of the shortest length, recording is performed with one pulse reaching the first power level, and first, second, and so on reaching the first power level.
The three pulses in the third order correspond to each pulse on the recording medium.
The recording parts form a long recording part that is stuck together
The second power between the first and second pulses.
-Lower than the level, and the second and
Lower than the second power level between the third pulse
Means for controlling the energy beam so as to reach a level . 8. A recording medium capable of causing the energy beam to enter a first state at a first power level and a second state at a second power level lower than the first power level;
What is claimed is: 1. An information recording apparatus for recording information on a recording medium by overwriting as information on a length and an interval of a recording point in the first state, comprising: means for generating the energy beam; Means for relatively moving, and when recording a recording point of the shortest length, recording is performed with one pulse reaching the first power level, and first, second, and so on reaching the first power level.
The three pulses in the third order correspond to each pulse on the recording medium.
The recording parts form a long recording part that is stuck together
The second power between the first and second pulses.
-Lower than the level, and the second and
Lower than the second power level between the third pulse
Means for controlling the energy beam so as to reach the first power level when recording the recording point having the shortest length. An information recording apparatus which is shorter than a time when the recording point passes from one end to the other end of the recording point. 9. A recording medium capable of turning the energy beam into an amorphous state at a first power level and into a crystalline state at a second power level lower than the first power level,
An information recording apparatus for recording information on the recording medium by overwriting as the length and interval of recording points in the amorphous state, wherein the means for generating the energy beam and the energy beam Means for relatively moving, and when recording a recording point having the shortest length, recording is performed with one pulse reaching the first power level, and first, second, and so on reaching the first power level.
The three pulses in the third order correspond to each pulse on the recording medium.
The recording parts form a long recording part that is stuck together
The second power between the first and second pulses.
-Lower than the level, and the second and
Lower than the second power level between the third pulse
Means for controlling the energy beam so as to reach a level . 10. 8. The information recording apparatus according to claim 7, wherein the second power level is in a range from 30% to 90% of the first power level. 11. 9. The information recording apparatus according to claim 8, wherein the second power level is in a range from 30% to 90% of the first power level. 12. 10. The information recording apparatus according to claim 9, wherein the second power level is in a range from 30% to 90% of the first power level.