JP3082395B2 - Optical recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, with a laser beam, recording of information, reproduction, relates to an optical recording how to erase, particularly high density, suitable optical recording how to realize an optical recording low noise <br/>

[0002]

2. Description of the Related Art Conventionally, in magneto-optical recording using a magnetic field modulation method, as shown in FIG. 10, a substrate 101 is provided on an optical recording medium 100 comprising an interference layer 102, a recording layer 103, and a protective layer 104 laminated on a substrate 101. Recording is performed by simultaneously irradiating the laser beam 106 from the side and applying a magnetic field modulated by a signal by the electromagnet 108. Here, a resin or glass such as polycarbonate is used for the substrate 101, a dielectric such as SiN is used for the interference layer 102 and the protective layer 104, and a rare earth transition metal amorphous thin film such as TbFeCo is used for the recording layer. The substrate 101 is provided with a guide groove 110 for tracking.
This is performed for the land 112 between zero.

When the recording layer 103 is irradiated with the laser beam 106, a high-temperature region 120 locally heated to a Curie temperature or higher is formed in the recording layer 103 as shown in FIG. The magnetization of the high-temperature region 120 is reversed according to the direction of the modulation magnetic field, and the high-temperature region 120 is cooled by the rotation of the optical recording medium 100, that is, the movement of the laser beam 106 accompanying the movement to the left in FIG. As a result, the direction of magnetization is fixed as the reversed magnetic domain 122 and recorded as information.

In a conventional overwrite recording method using a phase change recording material , GeS is used as the recording layer 103.
A phase change recording material such as bTe is used. Recording layer 103
In the crystalline state and the amorphous state correspond to the erased state and the recorded state, respectively. Crystalline state,
When the recording layer 103 in the erased state is irradiated with the laser beam 106 at high power, a high-temperature region 122 locally heated to a temperature equal to or higher than the melting point is formed on the recording layer 103 as shown in FIG. The movement of the laser beam 106 due to the rotation of the optical recording medium 100 and the reduction of the laser beam power make the recording layer 103
When the high temperature region 122 is rapidly cooled from the melting point,
22 becomes amorphous, and a mark 123 is formed. On the other hand, when the recording layer 103 is irradiated with the laser beam 106 at a medium power, a high-temperature region 124 locally heated to a temperature higher than the crystallization temperature and lower than the melting point is formed in the recording layer 103 as shown in FIG. You. Therefore, the portion 125 that has become the high-temperature region 124 in the already recorded mark 123 changes from amorphous to crystalline and is erased.

As described above, recording and erasing of information are performed in the recording layer 1.
03, for example, the direction of magnetization is changed in the case of magneto-optical recording, and the recording layer 1 is changed in the case of phase change recording.
03 is changed from crystal to amorphous or vice versa.

[0006]

However, in the above-described magneto-optical recording method using the conventional magnetic field modulation method, for example, as shown in FIG. 11, the shape of the reversal magnetic domain 122 reflects the temperature distribution during heating and cooling. , Crescent shaped.
Therefore, when the linear recording density, which is the recording density in the information writing direction, is increased, there is a problem that the density cannot be increased because a part of the front and rear reversal magnetic domains 122 may overlap. In addition, since an acute angle portion exists in the inversion magnetic domain 122, the domain wall energy of that portion increases, and the inversion magnetic domain 1
The shape of No. 22 was likely to be unstable, causing noise.

Further, in the above-described overwrite recording method using a phase-change recording material , as shown in FIG. 13, the temperature distribution of the laser-irradiated portion of the recording layer 103 includes a region having a melting point or higher at a high power. The width Wn is wider than the width Wc of the region where the temperature is equal to or higher than the crystallization temperature at the time of medium power. For this reason, as shown in FIG.
Since the width of 3 is wider than the width of the portion 125 to be erased, the both sides 130 of the mark are not erased, and unerased portions remain. This unerased portion causes noise and increases reproduction errors, which has been a problem.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to irradiate a recording layer with light through a recording area provided in a light-shielding layer.
By width of the heated above a temperature at which the state of the recording layer can change the high temperature region is set to be equal to or greater than the width of the recording area, occurrence of the noise to provide a reduced density capable optical recording how It is in.

[0009]

Means for Solving the Problems An optical recording how according to claim 1 of the present invention in order to achieve this goal, substantially transparent base
Material layer and the phase change record laminated so as to cover the base material layer
A recording layer made of a material, between the recording layer and the base layer.
Are formed in a spiral or concentric shape at a predetermined distance from each other
An optical recording medium having a light shielding layer can be heated by light.
A result, the recording or erasing predetermined information on the optical recording medium
In particular, in the method, the light is the predetermined length.
Heating the recording layer above its melting point over a length
It is characterized by that.

[0010] The optical recording method according to the second aspect is substantially equivalent to the optical recording method.
Transparent substrate layer and light laminated to cover the substrate layer
Recording layer made of magnetic recording material, the recording layer and the base material
Spiral or concentric with a certain distance between the layers
An optical recording medium having a light-shielding layer
Recording predetermined information on the optical recording medium by heating
Or for erasing methods, in particular, the light is
Curing the recording layer over a length exceeding a predetermined length
It is characterized by heating above the temperature.

[0011]

[Action] In <br/> optical recording how according to claim 1 of the present invention having the above configuration, light is substantially transparent substrate of the optical recording medium
Layers are formed in a spiral or concentric shape with a predetermined length of separation
The light-shielding layer and the recording layer made of the phase-change recording material.
To heat the recording layer and apply a predetermined amount to the heated recording layer.
Record or delete the information. Here, the light is transmitted to the light shielding layer.
Heats the recording layer above its melting point over a certain length
So that it is possible to prevent unerased residue on the recording layer.
To prevent noise and reproduction errors
Can be.

Further, in the optical recording method according to the present invention,
Thus, light is transmitted over a length exceeding a predetermined length of the light shielding layer.
Heat the recording layer made of magnetic recording material above the Curie temperature
To prevent the formation of sharp corners in the recording layer.
And prevent noise and reproduction errors.
Can be It is also possible to record information at high density
it can. That is, an acute angle portion of a conventional recording how crescent reversed magnetic domains are formed in is not formed for the outside of the recording area of the light blocking layer in the present invention, the inverted magnetic domain is Ri Do closer to a rectangular shape , Record information at high density
be able to. Furthermore, due to heat conduction, the width of the high-temperature region is wider than the width of the recording region, and even if the width of the mark or the reversal magnetic domain formed on the recording layer is wider than the recording region, the portion that is wider than the recording region during reproduction is Since the light is shielded by the light-shielding layer, generation of noise and reproduction error can be suppressed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

[0014] optical recording medium 10 for use in suitably applied to optical recording how the present invention may, for example, as shown in FIG. 1,
A light shielding layer 14 laminated on a substrate 12 as a base material layer ,
It comprises an interference layer 16, a recording layer 18, and a protective layer 20. Here, a transparent material such as a resin such as polycarbonate or glass is used for the substrate 12. Also, the light shielding layer 1
For 4, a metal such as aluminum, tantalum, gold, silver, copper, and titanium, and a compound such as titanium nitride are used. SiO2, SiAlON, Si
Transparent oxides such as N and AlN, nitrides and the like are used. For the recording layer 18, a magneto-optical recording material made of a rare earth transition metal alloy such as TbFeCo or GbTbFe is used.

A part of the light shielding layer 14 is removed along a spiral or concentric shape with a predetermined width as shown in FIG. 2 which is a plan view seen from the substrate 12 side, and a recording area 24 is formed. Note that, in addition to the recording area 24, pits 26 removed in a predetermined pattern to generate a preformat signal or the like may be formed in the light shielding layer 14. The laser beam 30 is irradiated from the substrate 12 side, and a part thereof is
The other is irradiated to the recording layer 18 through the recording area 24 provided in the light shielding layer 14. A magnetic field is applied to the recording layer 18 by the magnetic head 34.

When the recording layer 18 is irradiated with laser light through the recording region 24 provided in the light shielding layer 14, a high temperature region 36 heated to a Curie temperature or higher is formed in the recording layer 18 as shown in FIG. . The magnetization of the high-temperature region 36 is inverted according to the modulation magnetic field, and the rotation of the optical recording medium 10, that is,
When the high-temperature region 36 is cooled by the movement of the laser beam 30 accompanying the movement to the left, the direction of magnetization is fixed as the inverted magnetic domain 38 and recorded as information. At this time,
By appropriately increasing the power of the laser beam, the width of the portion of the recording layer 18 heated above the Curie temperature becomes equal to the width of the recording region 24, and the width of the high-temperature region 36 is reduced by heat conduction. It is slightly wider than the width. Therefore, the width of the inversion magnetic domain 38 is slightly wider than the width of the recording area 24, but its shape is closer to a rectangle than the conventional inversion magnetic domain 122 shown in FIG. That is, since there is no acute angle portion as in the conventional crescent-shaped magnetic domain 122, the magnetic domain shape is stable, and the generation of noise is suppressed.

Further, at the time of reproduction, both end portions of the inverted magnetic domain 38 are hidden by the light shielding layer 14, and the width of the inverted magnetic domain 38 read by the reproducing laser beam is limited to the width of the recording area 24. Is closer to a rectangle, so that the reversal magnetic domains 38 are less likely to overlap,
Higher densities are possible. Further, since the information can be reproduced without being affected by the fluctuation of the width of the reversal magnetic domain 38,
C / N and error rate are improved.

If the power of the laser beam is too low, the width of the high-temperature area 36 becomes smaller than the width of the recording area 24, which is not desirable.

Next, an embodiment in which a phase change recording material such as GeSbTe is used for the recording layer 18 in the same configuration as that of FIG. 1 will be described. At this time, the materials of the substrate 12, the light shielding layer 14, the interference layer 16, and the protective layer 20 other than the recording layer 18 may be the same as those described above, and are not particularly limited.
Although not shown, a reflective layer may be provided on the protective layer 20. No magnetic field is applied during recording or erasing.

When the recording layer 18 in the crystalline state, that is, the erasing state is irradiated with the laser beam 30 through the recording region 24 provided in the light shielding layer 14, the recording layer 18 is locally applied to the recording layer 18 as shown in FIG. A high temperature region 42 heated above the melting point is formed. Laser light 30 accompanying rotation of optical recording medium 10
The recording layer 1 by lowering the movement of the laser beam and lowering the laser beam power.
8 is rapidly cooled from its melting point,
2 becomes amorphous, and the mark 44 is formed. At this time, the width of the high-temperature area 42 is reduced due to heat conduction.
It is wider than the width. Accordingly, the width of the mark 44 is also wider than the width of the recording area 24, but is smaller than the width of the conventional mark 123 without the light shielding layer 14 shown in FIG.

On the other hand, the laser beam 30 is applied to the recording layer 1 at a medium power.
4, a high-temperature region 46 locally heated to a temperature higher than the crystallization temperature and lower than the melting point is formed in the recording layer 18 as shown in FIG. At this time, the width of the high-temperature area 46 is also wider than the width of the recording area 24 due to heat conduction. In particular, in the case of erasing, the high-temperature region 46 is easily expanded because the laser beam 30 is continuously irradiated. Therefore, almost all of the already recorded marks 44 become high-temperature regions 46 and change from amorphous to crystalline, so that erasing is performed.
At least, since the width of the high-temperature region 46 is wider than the width of the recording region 24, only the portion 48 of the recording layer 18 that is equal to or larger than the width of the recording region 24 is reliably erased. Further, even if the unerased portion is left, the light shielding layer 1 is located on both sides of the erased portion 48.
Because it is hidden by 4, the rest of the erased part will not be played,
No noise or reproduction error increases.

While the embodiment of the present invention has been described in detail with reference to FIGS. 1 to 4, the present invention can be implemented in other modes.

For example, the material of each layer is not particularly limited, and an acrylic resin, a polycarbonate resin, an amorphous polyolefin resin, or the like may be used as a substrate material instead of glass.

The recording layer 18 is not only a rare earth transition metal alloy other than TbFeCo, a multilayer film of PtCo or PdCo, an oxide magnetic material such as a rare earth iron garnet, and a magneto-optical material obtained by combining these, but also a phase change material such as TeOx. An organic material such as a molding material and a dye can be used. Further, also in the case of performing direct overwriting by an optical modulation method using an exchange-coupling multilayer magnetic film, the remaining unerased can be prevented or the influence of the unerased remaining can be suppressed in the same manner as in the embodiment shown in FIG. .

The thicknesses of the recording layer 18, the protective layer 20, and the light shielding layer 14 are not particularly limited.

For example, when the light-shielding layer 14 is thin, the unevenness generated on the recording layer 18 is also small, so that the effect of suppressing the deterioration of the recording layer 18 from the step is increased.

Further, as shown in FIG. 5, the recording layer 18 is made thinner,
A reflective layer 50 made of a metal such as Al, Au, or Cu may be provided on the protective layer 20. That is, the light incident from the substrate 12 side passes through the recording layer 18, is reflected by the reflection layer 50, and transmits through the recording layer 18 again. This allows
Not only the car effect but also the Faraday effect is added, so the reproduction C / N becomes higher. Further, as shown in the figure, an enhancement layer 52 may be provided between the light shielding layer 14 and the substrate 12. The enhancement layer 52 is made of, for example, a material having the same refractive index as that of the interference layer 16. By setting the sum of the thicknesses of the enhancement layer 52 and the interference layer 16 to be λ / (4n), the Kerr effect enhancement is further increased. , The reproduction C / N increases. Here, λ is the wavelength of the laser beam, and n is the refractive index of the interference layer 16 and the enhancement layer 52. At this time, it is desirable that the refractive index of the interference layer 16 and the enhancement layer 52 be higher than the refractive index of the substrate 12 because the Kerr effect enhancement is increased. Note that the refractive indexes of the interference layer 16 and the enhancement layer 52 do not necessarily have to be equal.

The material of the interference layer 16 is not particularly limited, and may be a multilayer film using a plurality of materials. The thickness of the interference layer 16 is not particularly limited, and may be any value as long as the push-pull signal and the preformat signal used for tracking can be obtained with practically sufficient strength.

As shown in FIG. 6, instead of the interference layer,
A translucent recording material 60 such as an organic dye or magnetic garnet may be used, and a reflective layer 62 may be provided thereon.

The removal pattern of the light shielding layer 14 is not particularly limited. For example, it may be removed in a continuous band shape.

The width of the recording area 24 and the track pitch are not particularly limited. For example, the track pitch and the width of the recording area 24 may be reduced toward the outer periphery. This further increases the recording capacity.

In order to make the width of the high-temperature areas 36 and 42 equal to or larger than the width of the recording area 24, the width of the recording area 24 is reduced, the intensity of the laser light is increased, The spot diameter may be increased. Further, these may be combined. It is to be noted that an increase in crosstalk can be suppressed by making the spot diameter of the laser beam 30 applied to a certain recording area 24 smaller than the width of the recording area 24 combined with the light shielding layers 14 on both sides thereof.

The interference layer 16 is not always necessary, and a recording layer 18 may be provided on the light shielding layer 14 as shown in FIG. At this time, tracking may be performed by, for example, a three-beam method using a difference in reflectance between the light shielding layer 14 and the recording layer 18. Alternatively, wobbling pits may be provided on the substrate 12 to perform tracking by a sample servo method. When the sample servo method is used, the difference between the reflectances of the light shielding layer 14 and the recording layer 18 may be small or the reflectances may be equal.

Further, as shown in FIG. 8, the interference layer 64 may be formed by spin coating or the like, and the surface thereof may be flattened. At this time, the recording layer 66, the protective layer 68, and the reflective layer 69 also become flat. That is, since no step portion which causes noise and defects occurs in the recording layer 66, the reliability is improved.

The surface of the substrate 12 does not need to be flat. For example, as shown in FIG. 9A, unevenness or the like may be formed on the substrate 70, and the light shielding layer 14 may be formed on one of the concave portion and the convex portion. Also at this time, the interference layer 16 may not be provided as shown in FIG.

The electromagnet 34 used for applying a magnetic field is not particularly limited. That is, for example, a floating magnetic head may be used in addition to the fixed electromagnet.

Further, the optical recording medium used in the optical recording how the present invention need not be disc-shaped, are not particularly limited for its shape. For example, it may be a card.

[0038]

As is clear from the above explanation, according to the present invention, according to the optical recording how according to claim 1 of the present invention, the light, light
Substantially transparent substrate layer of recording medium, spiral shape separated by a predetermined length
Or a concentric light-shielding layer and phase-change recording material
Irradiating the recording layer made of this, the recording layer is heated and heated.
Predetermined information is recorded or erased on the heated recording layer. here
The light is recorded over a length exceeding a predetermined length of the light shielding layer.
Since the recording layer is heated above its melting point, the remaining
Noise can be prevented, noise can be generated and
Raw errors can be prevented.

Further , in the optical recording method according to claim 2,
Thus, light is transmitted over a length exceeding a predetermined length of the light shielding layer.
Heat the recording layer made of magnetic recording material above the Curie temperature
To prevent the formation of sharp corners in the recording layer.
And prevent noise and reproduction errors.
Can be It is also possible to record information at high density
it can. That is, formed by the conventional recording method
In the present invention, the acute angle portion of the crescent-shaped inverted magnetic domain
It is not formed because it is outside the recording area of the light shielding layer,
Magnetic domains have a shape close to a rectangle, and record information at high density
be able to. Furthermore, the width of the high-temperature region
Is wider than the width of the recording area and the mask formed on the recording layer
Playback even if the width of the
Sometimes the part wider than the recording area is shielded by the light shielding layer
Therefore, generation of noise and reproduction error can be suppressed.

[0040]

[Brief description of the drawings]

1 is a fragmentary cross-sectional view showing an embodiment of an optical recording how the present invention.

FIG. 2 is a plan view of an essential part showing one embodiment of a removal pattern of a light shielding layer in an optical recording medium.

3 is an explanatory view showing a recording method in the optical recording how the present invention.

Is an explanatory view showing another recording method in the optical recording how of the present invention; FIG.

Figure 5 is a fragmentary cross-sectional view showing another embodiment of an optical recording medium used in the optical recording how the present invention.

6 is a fragmentary cross-sectional view showing another embodiment of an optical recording medium used in the optical recording how the present invention.

7 is a fragmentary cross-sectional view showing another embodiment of an optical recording medium used in the optical recording how the present invention.

8 is a fragmentary cross-sectional view showing another embodiment of an optical recording medium used in the optical recording how the present invention.

9 (a), is a fragmentary cross-sectional view showing another embodiment of an optical recording medium used in the optical recording how the (b) the present invention.

Figure 10 is a fragmentary cross-sectional view of a conventional optical recording how.

11 is an explanatory diagram showing a recording method according to a conventional optical recording how.

[12] (a) is an explanatory diagram showing a recording with the conventional optical recording how. (B) is an explanatory diagram showing the erasing by conventional optical recording how.

FIG. 13 is an explanatory diagram showing a temperature distribution in a recording layer at the time of heating by a laser beam.

[Explanation of symbols]

 12 substrate 14 light shielding layer 18 recording layer 24 recording area 36 high temperature area 42 high temperature area

Claims (2)

(57) [Claims] A substantially transparent base material layer and a cover for covering the base material layer.
Recording layer comprising a phase change recording material
Spiral with a predetermined distance between the recording layer and the base layer
Or an optical recording medium comprising a concentrically formed light-shielding layer
Is heated by light, so that the optical recording medium
In an optical recording method for recording or erasing predetermined information, the light is transmitted over a length exceeding the predetermined length.
Optical recording method characterized by heating the recording layer above its melting point
Law. 2. A substantially transparent substrate layer and a cover for covering the substrate layer.
A recording layer made of a magneto-optical recording material
Spiral with a predetermined distance between the recording layer and the base layer
Or an optical recording medium comprising a concentrically formed light-shielding layer
Is heated by light, so that the optical recording medium
In an optical recording method for recording or erasing predetermined information, the light is transmitted over a length exceeding the predetermined length.
Light characterized by heating the recording layer above the Curie temperature
Recording method.