JP2001283463A - Information recording medium and information recording/ reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new constitution of an information recording medium on which information can be recorded in high density, a new method for recording information in high density and a method for reproducing information from the information recording medium high in preservable property. SOLUTION: A write once type information recording medium is obtained by selecting two kinds of substances 102, 103 the simple of which does not show ferromagnetism at room temperature and forming a film by using the substances 102, 103 so that they coexist on a transparent substrate 101. A recording pit is formed by irradiating an information recording part with light and alloying the part to make it into a material 105 showing ferromagnetism in order to record information on the obtained medium. Heat can be used instead of light. More excellent recording is possible by recording information while magnetizing the ferromagnetic material 105 part by applying a magnetic field from the outside in the case of being irradiated with light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium and an information recording / reproducing method, and more particularly, to an optical information recording such as an optical disk capable of optically recording or reproducing information. An information recording medium for recording information by utilizing the property of a substance which is non-magnetic by itself but becomes ferromagnetic when alloyed as a component of a medium for achieving high density, and a recording method, and on the recording medium And a reproducing method for reproducing the information.

[0002]

2. Description of the Related Art As an optical recording medium, an information recording medium typified by a compact disk is well known. However, in the age of multimedia and information networks, a recording system having a larger capacity is required. I have. These information recording media include a read-only type, a write-once type, and a rewritable type.
A DVD-ROM, a CD-R as a write-once type, and a phase change recording type and a magneto-optical recording type as a rewritable type have been put to practical use.

Various proposals have been made with the aim of further improving the recording density. However, the methods for increasing the capacity are roughly divided into (1) making the recording pit smaller, (2) multiple recording pits at the same location. Record information.

In the method of reducing the pits, the recording density is improved and the reproduction signal is reduced by reducing the pits. When the reproduction signal becomes small, the reproduction signal becomes susceptible to crosstalk and the like. For this reason, there has been reported an example in which a Heusler alloy or the like having a large Kerr rotation angle is used as a material capable of obtaining a larger reproduction signal even in a small recording pit (for example, JP-A-7-272334). In addition, when the recording pit becomes small, the magnetization state in the pit changes with time and the magnetization becomes weak, so that the signal cannot be taken out well and the storage stability may be deteriorated.

[0005]

As described above, in order to realize a high-density medium by reducing pits, it is necessary to form small pits. As described above, the smaller the pit, the higher the recording density, but the adjacent information overlaps and crosstalk increases.In addition, the magnetic information becomes weaker with time, so the recorded information disappears when the pit becomes smaller. This causes problems such as easy storage and deterioration of storage stability.

Accordingly, the present invention provides a new configuration of an information recording medium capable of high-density recording, provides a new recording method for high-density recording, and further enhances the storage stability. It is an object of the present invention to provide a high information recording medium reproducing method.

[0007]

In order to solve the above-mentioned problems, the present invention utilizes the properties of a substance which is nonmagnetic as a single component of a medium but becomes ferromagnetic when alloyed. It is another object of the present invention to provide an information recording medium, an information recording method, and an information reproducing method in which a non-magnetic part and a ferromagnetic part make a binary information signal.

The invention according to claim 1 has a member made of at least two or more kinds of substances which do not show ferromagnetism, and a part of the member is formed by alloying the two or more kinds of substances which do not show ferromagnetism. By changing the alloyed portion to a recording pit, an information recording medium for reproducing a recording signal by light or magnetism is featured.

According to a second aspect of the present invention, in the first aspect of the present invention, at least two or more kinds of non-ferromagnetic substances are laminated.

According to a third aspect of the present invention, in the member according to the second aspect of the present invention, in a member formed by laminating at least two types of substances that do not exhibit ferromagnetism, the side on which light is incident and recording has a high light absorption rate. It is characterized by being a substance.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, Mn or Cr is contained as the non-ferromagnetic substance.

According to a fifth aspect of the present invention, in the first, second or third aspect of the present invention, the substance changed to exhibit ferromagnetism by the alloying is A2MnX (A is Cu, P
at least one of d, Au, Pt, and Ag, and X is Al, In, Sn, Ga, Ge, Sb, Si, Bi.
Or an A-Mn-X-based alloy (A is Cu,
At least one of Pd, Au, Pt and Ag, X
Al, In, Sn, Ga, Ge, Sb, Si, B
i, at least one of which is selected).

According to a sixth aspect of the present invention, a member formed by laminating at least two or more kinds of substances that do not show ferromagnetism is irradiated with light, so that the irradiated part changes to a substance showing ferromagnetism. The portion becomes a recording pit, and is recorded as a recording signal corresponding to binary information in a ferromagnetic portion and a non-ferromagnetic portion,
The information is reproduced by an optical or magnetic head.

According to a seventh aspect of the present invention, there is provided the first, second, third and fourth aspects.
Or, when reproducing information recorded on the information recording medium described in 5, after applying an external magnetic field to strengthen the recorded information signal, reproduction is performed using light or magnetism. is there.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Invention of claim 1) The invention of claim 1 has at least two or more kinds of members made of a material which does not exhibit ferromagnetism, and a part of the member is made of the two or more kinds of strong materials. Alloy to become a substance showing magnetism. The present invention relates to an information recording medium in which the alloyed portion is used as a recording pit and the information is reproduced by light or magnetism.
The recording member is a state in which at least two types of substances that do not show ferromagnetism are mixed, and it is necessary that these two types of substances exist without being alloyed.

The information recording medium of the present invention is a read-only medium,
It can be used as a write-once medium. In the case of a read-only medium, for example, as shown in FIG. 1, substances 102 and 103 which do not exhibit ferromagnetism at room temperature are mixed on a transparent substrate 101 such as a transparent resin or glass, and One having the protective layer 104 formed thereon can be used. As shown in FIG. 2, a ferromagnetic material is embedded in this information recording medium in advance as recording pits 105, or a material of 102, 103 is alloyed and changed to a material exhibiting ferromagnetism at room temperature. The recording pit 105 is used. The information is read out magnetically or optically to form a read-only medium.

Next, as an example of a write-once medium, two kinds of substances which do not exhibit ferromagnetism at room temperature will be described. FIG.
As shown in (1) above, two types of substances 102 and 103 that do not exhibit ferromagnetism at room temperature by themselves are selected and formed into a film on the transparent substrate 101 so as to form a write-once information recording medium. In order to record information on a recording medium, a portion where information is to be recorded is irradiated with light, and as shown in FIG. 2, the portion is alloyed into a substance 105 exhibiting ferromagnetism to form recording pits. Heat may be applied instead of light. It is preferable to perform recording while magnetizing the ferromagnetic portion by applying a magnetic field from the outside when irradiating light, because more excellent recording can be performed. It is preferable that the magnetization is perpendicular to the surface of the medium.

Reproduction is performed by using light or magnetism. In the case of performing reproduction by magnetism, there is no particular limitation on a magnetic head using a magnetoresistive effect and a magnetic head using an induction coil, but a magnetic head called a GMR head using a giant magnetoresistive effect is preferable. In the case of performing reproduction by light, a method of irradiating light and performing reproduction based on a difference in reflectance between an information signal portion and a non-signal portion, or a method of reproducing by using polarization rotation of light due to pit magnetization is used. is there.

Since the binary value of the signal is formed by the ferromagnetic portion and the non-magnetic portion, the signal is hardly affected by the strength of magnetization, is not easily affected by an adjacent signal, and the signal separation is improved. as a result,
Good recording and reproduction can be performed even at high density.

Although there is no particular limitation on the transparent substrate, a substrate in which signals such as tracking and address are incorporated, and a substrate in which grooves such as grooves are formed can be used. As shown in FIG.
01, or as shown in FIG. 4, the light may be incident from the direction of the film formed on the substrate. For higher density, as shown in FIG. 4, light is preferably incident from the side of the film formed on the substrate.

The layer structure of the information recording medium includes a structure in which a protective layer is formed between the substrate and a material layer that does not exhibit ferromagnetism, a layer for controlling light such as reflecting light, and the like. Then, a large effect is preferable.

(Invention of Claim 2) The invention of Claim 2 relates to an information recording medium configured so that at least two or more kinds of substances not exhibiting ferromagnetism exist in a laminated state. By laminating, the production of the medium is simplified,
Further, alloying at the time of recording becomes uniform, and good recording characteristics are exhibited. The invention of claim 2 can be used as both a read-only medium and a write-once medium, similarly to the invention of claim 1. As for the configuration of the information recording medium, taking a write-once medium as an example, as shown in FIG. 5, two kinds of substances 102 and 103 which do not exhibit ferromagnetism at room temperature by themselves are selected and laminated on a transparent substrate 101. By doing so, a write-once information recording medium is obtained. In order to record information on a recording medium, a portion where information is to be recorded is irradiated with light, and as shown in FIG. 6, the portion is alloyed into a substance 105 exhibiting ferromagnetism to form recording pits. The same configuration as that of the first aspect of the invention can be used except that the configuration is such that the substance that does not exhibit ferromagnetism exists in a laminated state.

According to a third aspect of the present invention, there is provided a member formed by laminating at least two types of substances not exhibiting ferromagnetism, wherein light is incident from the side of the substance having a high light absorption rate to record. By performing the above, an information recording medium having more excellent recording characteristics is provided. When recording is performed by irradiating light, recording can be performed excellently even with relatively weak light by performing recording by irradiating light from a material side having a high light absorption rate.

(Invention of Claim 4) As described in claim 4, as the substance not exhibiting ferromagnetism, a substance containing Mn or Cr is preferable. For example, Mn-Cu-
Al alloy, Mn-Al alloy, Mn-Au alloy, Mn-Z
n alloy, Mn-Ga alloy, Mn-In alloy, Mn-Pt
Alloy, Cr-Pt alloy, MnSb, MnBi and the like. The structure of the information recording medium according to claim 4 is, for example, that the substance 102 which does not exhibit ferromagnetism on the transparent substrate 101,
As 103, a material in which a protective layer 104 is formed using Mn or Al can be used.

(Invention of claim 5) The invention of claim 5 is a method of irradiating light to irradiate a part of a substance which has changed to a substance exhibiting ferromagnetism with A2MnX (A, Cu, Pd, A).
at least one of u, Pt and Ag, where X is A
alloy represented by at least one selected from 1, In, Sn, Ga, Ge, Sb, Si, and Bi, or an A-Mn-X-based alloy (Cu, P as A)
at least one of d, Au, Pt, and Ag, and X is Al, In, Sn, Ga, Ge, Sb, Si, Bi.
At least one selected from the above). Among them, PtMnSb and the like are preferable because the magnetization tends to be perpendicular to the medium surface. A2M
It is also preferable to add an additional element to the nX alloy or the A-Mn-X alloy in order to further improve the characteristics. As additional elements, Ti, V, Cr, Zn, Z
r, Nb, Mo, Ru, Re, Rh, Hf, Ta, W,
Os, Ir, Pb and the like can be exemplified. The configuration of the information recording medium includes a transparent substrate 101, a material portion that does not exhibit ferromagnetism as a recording layer, a protective layer, and the like, as described in the first and second aspects.

(Invention of claim 6) According to the invention of claim 6, a member formed by laminating at least two or more kinds of substances which do not show ferromagnetism is irradiated with light, so that the portion irradiated with light becomes ferromagnetic. The alloy changes into a material exhibiting ferromagnetism, and the portion is used as a recording pit. A recording signal corresponding to a binary signal is formed in the ferromagnetic portion and the non-ferromagnetic portion, and the information is reproduced by an optical or magnetic head. The invention of claim 6 is
The ferromagnetic part is a recording pit where an information signal is written, and the non-magnetic part which does not show ferromagnetism is recorded and reproduced on the medium as an unrecorded part. The signal can be separated well, and is suitable for high-density recording and reproduction.

When irradiating light, a magnetic field is applied from the outside,
It is preferable to perform recording while magnetizing the alloyed ferromagnetic portion, because better recording can be performed.
Further, it is preferable to apply a magnetic field perpendicular to the surface of the medium. Reproduction can be performed by using light or magnetism. The reproducing magnetic head is not particularly limited, such as a magnetic head utilizing a magnetoresistive effect and a magnetic head utilizing an induction coil, but a magnetic head called a GMR head utilizing a giant magnetoresistive effect is preferable.
When performing reproduction by light, a method of irradiating light and performing reproduction by a difference in reflectance between an information signal portion and a non-signal portion,
A method of reproducing by utilizing rotation of polarization of light due to magnetization of pits can be used.

(Invention of claim 7) The invention of claim 7 is a method of reproducing information recorded on the information recording medium, in which an external magnetic field is applied to strengthen the recorded information signal, and then the optical or magnetic information is reproduced. The present invention relates to an information reproducing method for reproducing by using the information. In the case where the recorded information becomes weaker due to a change over time and the reproduction becomes difficult, for example, the magnetic field is applied again to increase the magnetization as the recorded information and then reproduce the information. The recording medium that can be used in this method records information by making an alloy that shows ferromagnetism on a part of the medium that does not show ferromagnetism. Is not ferromagnetic. Therefore, even if the magnetic field is applied again later, the information is not erased and the recording state is improved. In addition, by performing reproduction while applying a magnetic field with a magnetic head or the like at the time of reproduction, a signal in a good recording state can always be reproduced, which is more effective.

(Examples) The present invention will be described in more detail with reference to the following examples. However, the present invention
It is not limited to these examples. Embodiment 1 (Claim 1) An embodiment of the invention of claim 1 will be described. The recording medium shown in FIG. 1 was used. Bi and Mn were used as substances corresponding to the substances 102 and 103 which do not show ferromagnetism on the transparent resin substrate or the glass substrate 101. These fine particles were dispersed in a solvent or the like, and formed into a film by spin coating or the like. Further, a protective layer 104 was formed by a sputtering method. A medium in which recording pits are formed in advance by light or heat is used as a read-only medium. In a write-once optical medium, the transparent substrate 101
An information recording medium was manufactured by using a transparent resin or glass having a diameter of 120 mmφ, forming Bi and Mn into a film, and further stacking SiN as a protective layer 104 by a sputtering method.

Embodiment 2 (Claim 2) Next, an embodiment of the invention of claim 2 will be described. The recording medium shown in FIG. 5 was used. Transparent resin substrate or glass substrate 1
On Al, an Al film having a thickness of 30 nm, a Mn film having a thickness of 25 nm, and a protective layer 104 were formed by sputtering as layers corresponding to the substances 102 and 103 which do not exhibit ferromagnetism. A medium in which recording pits are formed in advance by light or heat is used as a read-only medium. In the write-once optical medium, a transparent resin or glass having a diameter of 120 mmφ is used as the transparent substrate 101.
30 nm Al film, 25 nm Mn film, and protective layer 1
As No. 04, an information recording medium was manufactured by laminating SiN by a sputtering method.

Embodiment 3 (Claim 3) Next, an embodiment of the invention according to claim 3 will be described. On the transparent resin substrate or the glass substrate 101 shown in FIG. 7, a layer corresponding to the non-ferromagnetic substances 102 and 103 has an InSb film of 30 nm, a MnCu film of 25 nm, and a protective layer 104.
Was produced by a sputtering method. When light is incident from the direction shown in FIG. 7 (a substance having a high light absorption rate), excellent recording characteristics can be obtained.

Embodiment 4 (Claim 4) Next, an embodiment of the invention of claim 4 will be described. A glass substrate 10 having a layer configuration as shown in FIG.
A film is formed on 1 by stacking a 10 nm Pt layer, a 5 nm Mn layer, and a 5 nm Sb layer as layers corresponding to the substances 102 and 103 which do not exhibit ferromagnetism. By alloying this laminated film by light irradiation, it becomes a PtMnSb alloy exhibiting ferromagnetism, and a recording pit can be formed. As the protective layer 104, a diamond-like thin film having a thickness of 20 nm was formed and used as an information recording medium.

Embodiment 5 (Claim 5) Next, an embodiment of the invention according to claim 5 has a layer structure as shown in FIG. On a polycarbonate substrate 101 having a diameter of 120 mmφ, an Al layer having a thickness of 50 nm and a manganese copper layer of 2
5 nm was laminated. A protective layer ZnS.SiO2 is formed on the upper surface.
Alternatively, SiN was formed to obtain an information recording medium. By irradiating light corresponding to the information, a CuMnAl-based alloy which is a ferromagnetic material corresponding to the recording pit 105 shown in FIG. 6 is formed.

Embodiment 6 (Claim 6) Next, an embodiment of the invention according to claim 6 will be described. As a recording medium, as shown in FIG.
A layer having a thickness of 10 nm and an MnSb layer having a thickness of 10 nm was laminated, and a protective layer 104 was formed on the surface. At the time of recording, recording was performed by controlling the light intensity while applying a magnetic field with the magnetic head 106 from the back side of the substrate. MnSb and Pt are alloyed in a high-temperature portion of the light-irradiated region to form a ferromagnetic portion. The portion is magnetized by the magnetic field from the magnetic head in the process of returning from high temperature to room temperature, and becomes a recording pit. When reproducing by light, reproduction is performed by changing the reflectance of light between the ferromagnetic part and the non-magnetic part, or linearly polarized light is rotated because the polarization of the light is rotated by the magnetization of the ferromagnetic part with pits. The signal was reproduced from the irradiation and the rotation of the polarized light. In the reproduction using magnetism, the reproduction was performed by detecting the leakage magnetic field from the ferromagnetic portion using the GMR head.

Embodiment 7 (Claim 7) An embodiment of the invention according to claim 7 will be described. As shown in FIG. 9, when reproducing the information recording medium as described in the first, second, third, fourth and fifth embodiments, the magnetic head is perpendicular to the medium plane before detecting the reproduction signal. To apply a magnetic field.
As a result, the ferromagnetic portion 105 forming the recording pit has a better magnetization state. The non-magnetic portion without pits does not change even when a magnetic field is applied. FIG. 9 shows a method of reproducing with light while applying a magnetic field. By this method, the recording signal is strengthened before reproduction, and good reproduction can be performed.

[0036]

According to the first aspect of the present invention, at least 2
Having a member made of a material that does not exhibit more than one kind of ferromagnetism,
By changing a part of the member to an alloy of two or more kinds of substances not exhibiting ferromagnetism, the alloyed part is used as a recording pit, and a recording signal is reproduced by light or magnetism. Therefore, information can be reproduced satisfactorily with less crosstalk, and a high-density information recording medium using a method different from the conventional method can be provided.

According to a second aspect of the present invention, in the first aspect of the invention, at least two or more kinds of non-ferromagnetic substances are laminated, so that a high density The information recording medium can be realized with a simple configuration.

According to a third aspect of the present invention, in the member according to the second aspect of the present invention, in a member formed by laminating at least two types of substances not exhibiting ferromagnetism, light is incident from the side of the substance having a high light absorption rate. Since recording is performed, it is possible to provide an information recording medium capable of recording with relatively weak light.

According to the invention of claim 4, in the invention of claims 1, 2 or 3, Mn or Cr is contained as the substance which does not exhibit ferromagnetism, so that a high-density information recording medium having excellent recording characteristics can be provided. .

According to a fifth aspect of the present invention, in the first, second, or third aspect of the present invention, the material changed to exhibit ferromagnetism by the alloying is A2MnX (A is Cu,
At least one of Pd, Au, Pt and Ag, X
Al, In, Sn, Ga, Ge, Sb, Si, B
i) or an A-Mn-X-based alloy (A is C
at least one of u, Pd, Au, Pt, and Ag, and X is Al, In, Sn, Ga, Ge, Sb, S
Since at least one type is selected from i and Bi), it is possible to provide a high-density information recording medium capable of satisfactorily recording small recording pits.

According to the sixth aspect of the present invention, by irradiating a member formed by laminating at least two or more kinds of substances which do not show ferromagnetism, a portion irradiated with light changes to a substance showing ferromagnetism, This portion becomes a recording pit, and is recorded as a recording signal corresponding to binary information in a ferromagnetic portion and a non-ferromagnetic portion, and the information is reproduced by an optical or magnetic head, so that high-density information recording / reproduction is possible. Reproduction method can be provided.

According to the invention of claim 7, according to claims 1, 2, 2,
When reproducing the information recorded on the information recording medium described in 3, 4 or 5, since the recorded information signal is strengthened by applying an external magnetic field, the reproduction is performed using light or magnetism. The recording condition is good, and good reproduction can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration example of an information recording medium according to the present invention in cross section.

FIG. 2 is a schematic diagram showing a cross-sectional example of a state in which pits are recorded on an information recording medium according to the present invention.

FIG. 3 is a schematic diagram illustrating a direction of incidence of light on an information recording medium.

FIG. 4 is a schematic diagram showing a direction of incidence of light on an information recording medium.

FIG. 5 is a schematic view showing a configuration example of an information recording medium according to the present invention in cross section.

FIG. 6 is a schematic view showing a cross section of an example of a state in which pits are recorded on an information recording medium according to the present invention.

FIG. 7 is a schematic diagram showing a cross section showing an example of the configuration of an information recording medium according to the present invention and a light incident direction on the recording medium.

FIG. 8 is an explanatory diagram showing a method for recording and reproducing on an information recording medium according to the present invention.

FIG. 9 is an explanatory diagram showing a reproducing method from an information recording medium according to the present invention.

[Explanation of symbols]

101: transparent substrate, 102: substance not showing ferromagnetism, 1
03: substance not showing ferromagnetism, 104: protective layer, 105
... A ferromagnetic portion forming a recording pit,..., A magnetic head.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/14 G11B 11/14 13/04 13/04

Claims (7)

[Claims] 1. A member comprising at least two or more kinds of non-ferromagnetic substances, and a part of the member is changed to an alloy of the two or more kinds of non-ferromagnetic substances. An information recording medium characterized in that a converted portion is used as a recording pit and a recording signal is reproduced by light or magnetism. 2. An information recording medium according to claim 1, wherein said at least two or more kinds of non-ferromagnetic substances are laminated. 3. A member formed by laminating at least two types of substances that do not exhibit ferromagnetism, wherein a side on which light is incident and recording is performed has a high light absorption rate. Information recording medium. 4. The information recording medium according to claim 1, wherein said non-ferromagnetic substance contains Mn or Cr. 5. A substance changed to exhibit ferromagnetism by alloying is A2MnX (A is Cu, P
at least one of d, Au, Pt, and Ag, and X is Al, In, Sn, Ga, Ge, Sb, Si, Bi.
Or an A-Mn-X-based alloy (A is Cu,
At least one of Pd, Au, Pt and Ag, X
Al, In, Sn, Ga, Ge, Sb, Si, B
4. The information recording medium according to claim 1, wherein at least one type is selected from i). 6. A member formed by laminating at least two kinds of materials that do not show ferromagnetism is irradiated with light, so that the irradiated portion changes to a material showing ferromagnetism, and the portion becomes a recording pit. An information recording method comprising: recording as a recording signal corresponding to binary information in a ferromagnetic portion and a non-ferromagnetic portion. 7. When reproducing information recorded on the information recording medium according to claim 1, 2, 3, 4, or 5, after applying an external magnetic field to strengthen the recorded information signal, An information reproducing method characterized by performing reproduction using magnetism.