JPH05307780A - Magneto-optical recording medium - Google Patents

Abstract

(57) [Abstract] [Purpose] A magneto-optical device capable of increasing the vertical component of the magnetic field in the light irradiation region applied by the magnetic head, reducing the power consumption and heat generation amount of the magnetic head, and improving the reliability. Realize a recording medium. [Structure] On a transparent substrate 1, a dielectric film 31, a recording film 32,
The high-permeability layer 35 and the protective layer 4 are sequentially laminated, or the photocurable resin layer 2, the first dielectric film 31, the recording film 32, the second dielectric film 33, and the high-permeability layer are formed on the transparent substrate 1. 35 and the protective layer 4 are sequentially laminated, and the recording film 32 is formed by the high magnetic permeability layer 35.
Alternatively, the light transmitted through the second dielectric film 33 is reflected to promote multiple interference and the like, and the vertical component of the magnetic field in the laser light irradiation region is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording / reproducing information by utilizing the magneto-optical effect.

[0002]

2. Description of the Related Art In a magneto-optical recording medium, a magnetic thin film is irradiated with a laser beam to locally raise the temperature, and an external magnetic field is applied while the coercive force as a magnetic body is reduced.
Information is recorded by orienting the magnetization of the local area in the direction of the magnetic field, and the recorded information is reproduced by irradiating the information recording area with a laser beam and reading the magnetization direction of a so-called recording bit. Therefore, the recording / reproducing apparatus for a magneto-optical recording medium is provided with an optical head and a magnetic head, and both are provided in order to prevent the magneto-optical recording system from increasing in size and complicating the apparatus configuration. It is arranged on one side.

FIG. 8 is a diagram showing an example of a conventional structure of a magneto-optical disk as a magneto-optical recording medium. In the figure, 1 is a transparent reading substrate made of glass or polycarbonate.
Is a photocurable resin layer in which guide grooves and ID signal pits (not shown) are formed, 3 is a recording layer in which information is recorded, 4
Indicates a protective coat layer, 5 indicates an optical head, and 6 indicates a magnetic head. This magneto-optical disk is constructed by laminating a transparent substrate 1, a photocurable resin layer 2, a recording layer 3, and a protective coat layer 4 in this order.

The photocurable resin layer 2 is obtained by applying an ultraviolet curable resin on the transparent substrate 1 and applying ultraviolet rays from the transparent substrate 1 side in a state where a stamper having a reverse pattern such as a guide groove is adhered to the resin layer. It is formed by a so-called 2P method in which a pattern is irradiated and transferred. In addition, regardless of the 2P method,
Transparent substrate 1 by injection molding using the stamper described above
If a guide groove or the like is formed at the same time as molding, it is not necessary to provide a photocurable resin layer.

As shown in FIG. 8B, the recording layer 3 includes a first dielectric film 31 made of, for example, SiN, a recording film 32 made of a magnetic material, for example, TbFeCo, and SiN from the photocurable resin layer 2 side. The second dielectric film 33 made of Al and the reflective film 34 made of metal such as Al are sequentially laminated. That is, the recording layer 3 prevents deterioration of the recording film 32 due to oxidation and improves the reproducing ability by utilizing the interference effect due to multiple reflection of light (Kerr effect enhancement). Second dielectric film 33
The recording film 32 is sandwiched by the so-called sandwich structure, and the reflection film 34 is the recording film of the second dielectric film 33 in order to reflect the light transmitted through the second dielectric film 33 and promote multiple interference. It is provided on the surface side opposite to the contact surface with 32.

With respect to the magneto-optical disk having such a structure, both the optical head 5 and the magnetic head 6 are arranged on the transparent substrate 1 side to record and reproduce information. Actually, the optical head 5 and the magnetic head 6 are integrated, and the flying head type and the actuator hold a fixed distance between the optical magnetic head and the magneto-optical disk. Information is recorded on the magneto-optical disk by inverting the magnetic field at high speed by the magnetic head 6 while the laser light is focused on the recording layer 3 of the disk by the optical head 5.

The above-described recording method is called a magnetic field modulation method, and like the magnetic recording, recording is performed by the magnetic head 6, and the laser light from the optical head 5 is used to limit the recording area. The so-called overwrite is possible, where new information is suddenly recorded on top.

[0008]

By the way, in the magneto-optical disk as shown in FIG. 8, the thickness of the transparent substrate 1 for reading gives practical strength to the disk itself, and in order to prevent dust and scratches. Recording film 3 of about 1 mm and several hundred nm
It is set to a larger value than 2 or the like. As a result, the distance between the magnetic head 6 and the recording layer 3 is increased, and the magnetic head 6 shown in FIG.
As shown in FIG. 5, the magnetic field vertical component generated by the magnetic head 5 on the recording film 32 is small in the recording area because the magnetic field lines M form a large loop, and therefore information is recorded on the recording film 32. In order to reliably perform the above, it is necessary to flow a large current through the magnetic coil of the magnetic head 6 to perform high-speed reversal of the magnetization. Therefore, the conventional magneto-optical disk device has a drawback that the magnetic head 6 consumes a large amount of power and generates a large amount of heat.

The present invention has been made in view of the above circumstances, and an object thereof is to increase the vertical component of the magnetic field in the light irradiation region applied by the magnetic head, and also to reduce the power consumption and heat generation amount of the magnetic head. It is an object of the present invention to provide a magneto-optical recording medium capable of reducing the noise and improving the reliability.

[0010]

In order to achieve the above object, in the magneto-optical recording medium of the present invention, a dielectric film, a recording film, a high magnetic permeability layer and a protective layer are sequentially laminated on a transparent substrate.

In the magneto-optical recording medium of the present invention, a reflective film having a heat radiation function is provided between the recording film and the high magnetic permeability layer.

In the magneto-optical recording medium of the present invention, a thermal insulating layer having magnetic permeability is provided between the reflective film and the high magnetic permeability layer.

In the magneto-optical recording medium of the present invention, a photocurable resin layer, a first dielectric film, a recording film, a second dielectric film, a high magnetic permeability layer and a protective layer are sequentially laminated on a transparent substrate.

In the magneto-optical recording medium of the present invention, a reflective film having a heat dissipation function is provided between the second dielectric film and the high magnetic permeability layer.

In the magneto-optical recording medium of the present invention, a heat insulating layer having magnetic permeability is provided between the reflective film and the high magnetic permeability layer.

In the magneto-optical recording medium of the present invention, a photocurable resin layer, a high magnetic permeability layer, a recording film, a dielectric film and a transparent substrate are sequentially laminated on a supporting substrate.

In the magneto-optical recording medium of the present invention, a reflective film having a heat radiation function is provided between the high magnetic permeability layer and the recording film.

In the magneto-optical recording medium of the present invention, a thermal insulating layer having magnetic permeability is provided between the high magnetic permeability layer and the reflective film.

In the magneto-optical recording medium of the present invention, a photocurable resin layer, a high magnetic permeability layer, a second dielectric film, a recording film, a first dielectric film, and a transparent substrate are sequentially laminated on a supporting substrate.

In the magneto-optical recording medium of the present invention, a reflective film having a heat dissipation function is provided between the high magnetic permeability layer and the second dielectric film.

In the magneto-optical recording medium of the present invention, a thermal insulating layer having magnetic permeability is provided between the high magnetic permeability layer and the reflective film.

[0022]

According to the magneto-optical recording medium of the present invention, the laser light emitted from the optical head is incident on the transparent substrate, the dielectric film and the recording film, and the light transmitted through the recording film is reflected by the high magnetic permeability layer. It This reflected light synergizes the Kerr effect with the Faraday effect, thereby expanding the rotation angle. On the other hand, the magnetic flux generated by the magnetic head reaches the high magnetic permeability layer after passing through the transparent substrate, the dielectric film and the recording film substantially perpendicularly to the respective surfaces. The magnetic flux that has reached the high-permeability layer does not pass through the high-permeability layer, travels in the high-permeability layer in the in-plane direction for a distance according to the magnetic field strength, and then passes through the recording film, dielectric film, and transparent substrate again. Then, draw a small closed magnetic loop that returns to the magnetic head.
As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

According to the magneto-optical recording medium of the present invention,
The laser light emitted from the optical head is incident on the transparent substrate, the dielectric film, and the recording film, and the light transmitted through the recording film is reflected by the reflective film. By this reflected light, the Faraday effect is synergized with the Kerr effect, and the rotation angle is expanded. At this time, the heat of the area which has become high temperature by the irradiation of the laser beam is radiated by the reflective film. This makes the high-permeability layer less likely to be affected by heat, and prevents the permeability and saturation magnetic flux density of the high-permeability layer from decreasing. On the other hand, the magnetic flux generated by the magnetic head reaches the high magnetic permeability layer after passing through the transparent substrate, the dielectric film, the recording film and the reflective film almost perpendicularly to each surface. The magnetic flux that has reached the high magnetic permeability layer does not pass through the high magnetic permeability layer and travels in the high magnetic permeability layer in the in-plane direction by a distance according to the magnetic field strength,
It draws a small closed magnetic loop that again passes through the reflective film, recording film, dielectric film and transparent substrate and returns to the magnetic head. As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

According to the magneto-optical recording medium of the present invention,
The laser light emitted from the optical head is incident on the transparent substrate, the dielectric film, and the recording film, and the light transmitted through the recording film is reflected by the reflective film. By this reflected light, the Faraday effect is synergized with the Kerr effect, and the rotation angle is expanded. At this time, the heat of the area which has become high temperature by the irradiation of the laser beam is radiated by the reflective film. This makes the high-permeability layer less likely to be affected by heat, and prevents the permeability and saturation magnetic flux density of the high-permeability layer from decreasing. Further, since the heat insulating layer is provided between the reflective film and the high magnetic permeability layer, the heat generated by the laser light irradiation is hardly transferred to the high magnetic permeability layer. On the other hand, the magnetic flux generated by the magnetic head is generated by the transparent substrate, the dielectric film,
After passing through the recording film, the reflective film, and the heat insulating layer almost perpendicularly to the respective surfaces, they reach the high magnetic permeability layer. The magnetic flux that has reached the high-permeability layer does not pass through the high-permeability layer and travels in the high-permeability layer in the in-plane direction by a distance according to the magnetic field strength, and again as a heat insulating layer, a reflection film, a recording film, A small closed magnetic loop is drawn that passes through the dielectric film and the transparent substrate and returns to the magnetic head.
As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

According to the magneto-optical recording medium of the present invention,
The laser light emitted from the optical head is incident on the transparent substrate, the photo-curable resin layer, the first dielectric film, the recording film and the second dielectric film, and the light transmitted through the second dielectric film is highly transparent. The light reflected by the magnetic susceptibility layer is subjected to multiple interference. on the other hand,
The magnetic flux generated by the magnetic head is transmitted through the transparent substrate, the photo-curable resin layer, the first dielectric film, the recording film and the second dielectric film almost perpendicularly to each surface, and then is transmitted to the high magnetic permeability layer. To reach. The magnetic flux that has reached the high-permeability layer does not pass through the high-permeability layer and travels in the high-permeability layer in the in-plane direction for a distance corresponding to the magnetic field strength, and again reaches the second dielectric film, the recording film, and the second film. A small closed magnetic loop is drawn which passes through the first dielectric film, the photocurable resin layer and the transparent substrate and returns to the magnetic head. As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

According to the magneto-optical recording medium of the present invention,
The laser light emitted from the optical head is incident on the transparent substrate, the photocurable resin layer, the first dielectric film, the recording film and the second dielectric film, and the light transmitted through the second dielectric film is the reflection film. The reflected light is subjected to multiple interference. At this time, the heat of the area which has become high temperature by the irradiation of the laser beam is radiated by the reflective film. This makes the high-permeability layer less likely to be affected by heat, and prevents the permeability and saturation magnetic flux density of the high-permeability layer from decreasing. On the other hand, the magnetic flux generated by the magnetic head is transmitted through the transparent substrate, the photo-curable resin layer, the first dielectric film, the recording film, the second dielectric film and the reflective film almost perpendicularly to the respective surfaces, Reach high permeability layer. The magnetic flux that has reached the high-permeability layer does not pass through the high-permeability layer and travels in the high-permeability layer in the in-plane direction for a distance according to the magnetic field strength, and then again on the reflection film, the second dielectric film, and the recording layer. A small closed magnetic loop is drawn which passes through the film, the first dielectric film, the photocurable resin layer and the transparent substrate and returns to the magnetic head. As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

According to the magneto-optical recording medium of the present invention,
The laser light emitted from the optical head is incident on the transparent substrate, the photocurable resin layer, the first dielectric film, the recording film and the second dielectric film, and the light transmitted through the second dielectric film is the reflection film. The reflected light is subjected to multiple interference. At this time, the heat of the area which has become high temperature by the irradiation of the laser beam is radiated by the reflective film. This makes the high-permeability layer less likely to be affected by heat, and prevents the permeability and saturation magnetic flux density of the high-permeability layer from decreasing. Further, between the reflective film and the high magnetic permeability layer,
Since the heat insulating layer is provided, the heat generated by the laser light irradiation is hardly transferred to the high magnetic permeability layer. On the other hand, the magnetic flux generated by the magnetic head is generated by the transparent substrate, the photocurable resin layer, the first dielectric film, the recording film, the second dielectric film,
After passing through the reflective film and the heat insulating layer almost perpendicularly to the respective surfaces, they reach the high magnetic permeability layer. The magnetic flux that has reached the high-permeability layer does not pass through the high-permeability layer and travels in the high-permeability layer in the in-plane direction for a distance according to the magnetic field strength, and then again as the thermal insulation layer,
A small closed magnetic loop is drawn which passes through the reflective film, the second dielectric film, the recording film, the first dielectric film, the photocurable resin layer and the transparent substrate and returns to the magnetic head. As a result, the vertical component of the magnetic field in the laser light irradiation region increases.

The magneto-optical recording medium of the present invention using the supporting substrate also has the same effect as described above.

[0029]

[Embodiment 1] FIG. 1A is a schematic sectional view of an essential part showing a first embodiment of a magneto-optical disk according to the present invention, and FIG.
It is a partially expanded sectional view of the recording layer in (a), and the same components as those in FIG. 8 showing a conventional example are denoted by the same reference numerals. That is, 1 is a transparent substrate for reading, 2 is a guide groove or ID
Is a photo-curable resin layer having signal pits (not shown) formed therein, 3a is a recording layer for recording information, 4 is a protective coat layer, 5 is an optical head, and 6 is a magnetic head. This magneto-optical disk is constructed by sequentially laminating a transparent substrate 1, a photo-curable resin layer 2, a recording layer 3a, and a protective coat layer 4.

The transparent substrate 1 is made of glass, polycarbonate or the like, and its thickness is set to, for example, 1.2 mm in consideration of practical strength. In particular, when glass is used as the material, it is possible to realize a magneto-optical disk that is less likely to be bent by an external force, is less likely to be scratched, and is less likely to be charged, and has less dust attached.

The photocurable resin layer 2 is obtained by applying an ultraviolet curable resin on the transparent substrate 1 and bringing a stamper having a reverse pattern such as a guide groove into close contact with the resin layer to irradiate the transparent substrate 1 with ultraviolet rays. Transfer pattern by using so-called 2
It is formed to a thickness of about 5 to several tens of μm by the P method. When the guide groove and the like are formed at the same time when the transparent substrate 1 is formed by injection molding using the stamper described above regardless of the 2P method, it is not necessary to provide the photocurable resin layer.

The recording layer 3a, as shown in FIG.
From the photocurable resin layer 2 side, the first dielectric film 31, the recording film 3
2, the second dielectric film 33, and the high magnetic permeability layer 35 are laminated in this order. The first dielectric film 31 is a nitride such as SiN (silicon nitride) or AlN (aluminum nitride),
Photocurable resin layer 2 made of oxide such as SiO
It is formed to a thickness of several 100 nm on the top by a vacuum film forming technique such as sputtering. The recording film 32 is
The perpendicular anisotropy energy is large, a perpendicular magnetization film necessary for high-density recording is likely to be formed, the Kerr rotation angle is relatively large, and the Curie point is low (150 to 200 ° C).
The recording / erasing power is a commercially available semiconductor laser (output 20-4
0 mW) and other requirements, such as C
Rare Earth (RE) and F such as d and Tb
and an alloy with a transition element (TM) such as e or Co, for example, a TbFeCo film,
It is formed on the first dielectric film 31 to have a thickness of several 100 nm by a vacuum film forming technique such as sputtering.
The second dielectric film 33, like the first dielectric film 31, is made of Si.
It is made of a nitride such as N or AlN or an oxide such as SiO, and is formed on the recording film 32 to have a thickness of several 100 nm by a vacuum film forming technique such as sputtering. The high magnetic permeability layer 35 is made of a soft magnetic material having a high magnetic permeability such as an alloy of a transition metal such as Fe, Co, or Ni, and is formed on the second dielectric film 33 by a vacuum film forming technique such as sputtering. To a thickness of several 100 nm. The high-permeability layer 35 functions as a conventional reflection film and, as shown in FIG. 2, reduces the loop of the magnetic force line M by the magnetic head 6 and makes the magnetic field perpendicular to the recording area irradiated with the laser beam. It has the function of increasing the components.

That is, the recording layer 3a has a first dielectric layer in order to prevent deterioration of the recording film 32 due to oxidation and to improve the reproducing capability by utilizing the interference effect of multiple reflection of light (Kerr effect enhancement). The recording film 32 has a sandwich structure with the film 31 and the second dielectric film 33,
In addition, in order to reflect the light transmitted through the second dielectric film 33 to promote multiple interference and increase the vertical component of the magnetic field in the recording area, the high magnetic permeability layer 35 is used as the second dielectric film 3
3 is provided on the surface side opposite to the contact surface with the recording film 32.

After forming the recording layer 3a, the protective coat layer 4 is formed on the second dielectric film 33 to a thickness of about several hundreds of μm by, for example, a spin coat method. The protective coat layer 4 does not need to transmit the laser beam, and may be opaque. When the reading transparent substrate 1 is thin, for example, 0.3 mm and does not have sufficient strength, it is made of glass, polycarbonate, metal or the like and is bonded to the recording layer 3a with an adhesive.

With respect to the magneto-optical disk having such a structure, both the optical head 5 and the magnetic head 6 are arranged on the transparent substrate 1 side to record and reproduce information. Actually, the optical head 5 and the magnetic head 6 are integrated, and the flying head type and the actuator hold a fixed distance between the optical magnetic head and the magneto-optical disk.

Recording of information on the present magneto-optical disk is performed by
This is performed by reversing the magnetic field at high speed by the magnetic head 6 while the laser light is focused on the recording layer 3a of the disk by the optical head 5. At this time, the magnetic flux generated by the magnetic head 6 causes the reading transparent substrate 1, the photo-curable resin layer 2, the first dielectric film 31, the recording film 32, and the second dielectric film 33 to be substantially flush with each surface. After passing vertically, it reaches the high magnetic permeability layer 35, but the magnetic flux does not pass through the high magnetic permeability layer 35 and travels in the high magnetic permeability layer 35 in the in-plane direction by a distance corresponding to the magnetic field strength, and then again. A small closed magnetic loop is drawn which passes through the second dielectric film 33, the recording film 32, the first dielectric film 31, the photocurable resin layer 2 and the read transparent substrate 1 and returns to the magnetic head 6. as a result,
The vertical component of the magnetic field in the recording area irradiated with the laser light is increased as compared with the conventional magneto-optical disk in which the high magnetic permeability layer 35 is not provided as in the conventional case. Therefore, the current I flowing through the magnetic head 6 can be made smaller than before.

FIG. 3 is a diagram showing the relationship between the drive current I for the magneto-optical disk (invention product) of FIG. 1 and the drive current I for the conventional magneto-optical disk (conventional product) shown in FIG. 8 and CN. .. As shown in FIG. 3, according to the product of the present invention, even if the drive current I of the magnetic head 6 is set to about 50% of the conventional value, a better CN ratio can be obtained as compared with the conventional product.

As described above, according to this embodiment,
In the recording layer 3a, a soft magnetic material having a high magnetic permeability such as an alloy of a transition metal such as Fe, Co, or Ni is used instead of the reflective film made of Al or the like. Not only can the light transmitted through the dielectric film 33 be reflected to promote multiple interference, but also the vertical component of the magnetic field in the recording region irradiated with the laser light can be increased. As a result, the current I flowing through the magnetic head 6 can be reduced, which in turn can reduce the power consumption and heat generation of the magnetic head 6. In addition, the high magnetic permeability layer 35
Is formed in place of the reflection film 34 in the conventional recording layer 3 shown in FIG. 8, so that it can be manufactured by the same film forming process in the manufacturing process, and the thickness of the magneto-optical disk itself is the same as that of the conventional product. Can maintain the same thickness.

In the above description, the method of forming the high-permeability layer 35 is described by taking a vacuum film forming technique such as sputtering as an example. However, the method is not limited to this, and for example, vacuum evaporation or It goes without saying that it can be formed using a method such as plating.

[0040]

[Embodiment 2] FIG. 4 is a schematic sectional view of a main portion of a second embodiment of a magneto-optical disk according to the present invention, specifically a partially enlarged sectional view of a recording layer. This embodiment is different from the first embodiment in that the reflective film 3 made of a metal such as Al is provided between the second dielectric film 33 of the recording layer 3a and the high magnetic permeability layer 35.
6 is provided. Therefore, the recording layer 3a of this example
The recording layer 3a is formed by forming the reflective film 36 on the second dielectric film 33 by sputtering or the like, and then forming the high magnetic permeability layer 35 by sputtering or the like.

As described above, the high-permeability layer 35 has the function of reflecting the light transmitted through the second dielectric film 33 as well as the reflection film to promote multiple interference, but like the metal such as Al. In addition, it is inferior in the function as a so-called heat sink that quickly dissipates heat in a region that has become high in temperature by irradiation with laser light. Further, since the high magnetic permeability layer 35 is easily affected by heat, there is a concern that the magnetic permeability and the saturation magnetic flux density will decrease. Therefore, in this embodiment, the reflective film 36 made of a metal such as Al is provided between the second dielectric film 33 and the high magnetic permeability layer 35.
Is provided.

As described above, in the magneto-optical disk of this embodiment, the laser light emitted from the optical head (not shown) is
The light that has passed through the unillustrated transparent substrate for reading and the photo-curable resin layer is incident on the recording layer 3a. Of these lights, the light that has passed through the first dielectric film 31, the recording film 32, and the second dielectric film 33 is , Is reflected by the reflection film 36 and is used for multiple interference. The heat generated by the laser light is radiated by the reflective film 36.

On the other hand, the magnetic flux generated by the magnetic head (not shown) passes through the reading transparent substrate, the photo-curable resin layer, the first dielectric film 31, the recording film 32, the second dielectric film 33 and the reflective film 36. After permeating almost perpendicularly to the plane, it reaches the high magnetic permeability layer 35. The magnetic flux that has reached the high-permeability layer 35 does not pass through the high-permeability layer 35, travels in the high-permeability layer 35 in the in-plane direction by a distance corresponding to the magnetic field strength, and again reaches the reflection film 36 and the second layer. A small closed magnetic loop is drawn which passes through the dielectric film 33, the recording film 32, the first dielectric film 31, the photocurable resin layer and the transparent substrate for reading and returns to the magnetic head.
As a result, the vertical component of the magnetic field in the recording area irradiated with the laser beam is increased as compared with the conventional magneto-optical disk in which the high magnetic permeability layer 35 is not provided as in the conventional case. Therefore, the current I flowing through the magnetic head 6 can be made smaller than before. Further, the high magnetic permeability layer 35 is unlikely to be affected by the heat due to the laser light irradiation due to the heat dissipation effect of the reflective film 36.

As described above, according to this embodiment,
The current I flowing to the magnetic head can be reduced, and the power consumption and heat generation amount of the magnetic head can be reduced, and the high-permeability layer 35 is not easily affected by heat generated by laser light irradiation. The magnetic susceptibility and the saturation magnetic flux density can be prevented from lowering, and the reliability of the magneto-optical disk can be improved.

[0045]

[Embodiment 3] FIG. 5 is a schematic sectional view showing a third embodiment of a magneto-optical disk according to the present invention, specifically a partially enlarged sectional view of a recording layer. The present embodiment is different from the second embodiment in that the third dielectric made of a magnetically permeable material having high thermal insulation is provided between the reflective film 36 of the recording layer 3a and the high magnetic permeability layer 35. The film 37 is provided. This third dielectric film 37 is, for example, the first and second dielectric films 3
It is made of the same material as 1, 33. The recording layer 3a in this example is formed on the reflective film 36 by sputtering or the like.
After the dielectric film 37 is formed, the high magnetic permeability layer 35 is formed by sputtering or the like.
a is constructed.

As described above, in the magneto-optical disk of this embodiment, the laser light emitted from the optical head (not shown) is
The light that has passed through the unillustrated transparent substrate for reading and the photo-curable resin layer is incident on the recording layer 3a. Of these lights, the light that has passed through the first dielectric film 31, the recording film 32, and the second dielectric film 33 is , Is reflected by the reflection film 36 and is used for multiple interference. The heat generated by the laser light is radiated by the reflective film 36. At this time, since the third dielectric film 37 having a high thermal insulation property is provided between the reflective film 36 and the high magnetic permeability layer 35, the heat generated by the laser light irradiation is generated by the high magnetic permeability layer. Three
It is hardly transmitted to 5.

On the other hand, the magnetic flux generated by the magnetic head (not shown) reads the transparent substrate for reading, the photo-curable resin layer, the first dielectric film 31, the recording film 32, the second dielectric film 33, the reflecting film 36 and the first film. After passing through the dielectric film 37 of No. 3 substantially perpendicularly to each surface, it reaches the high magnetic permeability layer 35. The magnetic flux that has reached the high-permeability layer 35 does not pass through the high-permeability layer 35, travels in the high-permeability layer 35 in the in-plane direction by a distance according to the magnetic field strength, and again the third dielectric film 37, A small closed magnetic loop is drawn which passes through the reflective film 36, the second dielectric film 33, the recording film 32, the first dielectric film 31, the photocurable resin layer and the transparent substrate for reading and returns to the magnetic head. As a result, the vertical component of the magnetic field in the recording area irradiated with the laser beam is increased as compared with the conventional magneto-optical disk in which the high magnetic permeability layer 35 is not provided as in the conventional case. Therefore, the current I flowing through the magnetic head 6 can be made smaller than before, and the heat dissipation effect of the reflective film 36 and the third dielectric film 3 can be achieved.
Due to the heat insulating property of No. 7, the high magnetic permeability layer 35 is hardly affected by heat due to laser light irradiation.

As described above, according to this embodiment,
Compared to the case of the second embodiment, the high magnetic permeability layer 35 is less susceptible to the heat caused by the laser light irradiation.
It is possible to reliably prevent a decrease in the saturation magnetic flux density and further improve the reliability of the magneto-optical disk.

[0049]

[Embodiment 4] FIG. 6 is a schematic cross-sectional view of an essential part showing a fourth embodiment of the magneto-optical disk according to the present invention. In this embodiment, a support substrate 38 made of, for example, glass, polycarbonate or metal is prepared, the photocurable resin layer 2 is formed on the support substrate 38 by the 2P method, and the recording layer is formed on the photocurable resin layer 2. 3a is formed into a film, and this recording layer 3a
And the transparent substrate for reading 1 are provided with an adhesive 39 having good light transmittance.
It is configured by bonding with.

In this magneto-optical disk, the manufacturing process is slightly different, but the other structure, particularly the structure of the recording layer 3a, is the same as that of FIGS. 1, 4 and 5, and the magneto-optical disk having such a structure is used. With respect to the disk, the optical head 5 and the magnetic head 6 are both arranged on the side of the transparent substrate for reading 1 as in the first, second and third embodiments described above.
Information recording / reproduction is performed.

Also in this embodiment, the same effect as that of each of the above-mentioned embodiments can be obtained.

[0052]

[Embodiment 5] FIG. 6 is a schematic sectional view of a main portion of a fifth embodiment of a magneto-optical disk according to the present invention. In the present embodiment, each of the above-described embodiments was constructed on the premise of a single-sided disc, but the present invention is applied to a double-sided disc. The double-sided disc having the structure shown in FIG. 7 is formed by bonding the protective coating layers 4 and 4'of the single-sided disc shown in FIG. When the single-sided disk shown in FIG. 6 is used, the supporting substrates 38 are bonded together with an adhesive to form a double-sided disk.

In this embodiment, in addition to the effects of the above-described embodiments, both sides can be accessed simultaneously.

In each of the above embodiments, a disk was described as an example of the form of the magneto-optical recording medium to which the present invention is applied, but the present invention is not limited to this, and for example, a card, tape, drum, etc. Of course, it is also applicable to.

[0055]

As described above, according to the present invention,
The high-permeability layer can reflect the light transmitted through the recording film or the second dielectric film to promote multiple interference and increase the vertical component of the magnetic field in the laser light irradiation region. As a result, the current flowing through the magnetic head can be reduced, which in turn can reduce the power consumption and heat generation of the magnetic head.

Further, since the reflective film having a heat dissipation property is provided between the recording film and the high magnetic permeability layer or between the second dielectric film and the high magnetic permeability layer, the reflective film causes the irradiation of the laser beam. Since the heat can be dissipated, the high-permeability layer is less likely to be affected by the heat accompanying the laser light irradiation. As a result, it is possible to prevent a decrease in the magnetic permeability and the saturation magnetic flux density of the high magnetic permeability layer, and it is possible to improve the reliability of the magneto-optical recording medium.

Further, since the heat insulating layer having magnetic permeability is provided between the reflective film and the high magnetic permeability layer, the high magnetic permeability layer is further less susceptible to the heat due to the laser light irradiation. Therefore, it is possible to reliably prevent a decrease in the magnetic permeability and the saturation magnetic flux density of the high magnetic permeability layer, and it is possible to further improve the reliability of the magneto-optical disk.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of essential parts showing a first embodiment of a magneto-optical disk according to the present invention.

FIG. 2 is an explanatory diagram of a locus of magnetic flux of the magneto-optical disk according to the present invention.

3 is a diagram showing the relationship between the drive current for the magneto-optical disk of FIG. 1 (product of the present invention) and the drive current for the conventional magneto-optical disk of FIG. 8 (conventional product) and CN.

FIG. 4 is a schematic cross-sectional view of essential parts showing a second embodiment of the magneto-optical disk according to the present invention.

FIG. 5 is a schematic cross-sectional view of essential parts showing a third embodiment of the magneto-optical disk according to the present invention.

FIG. 6 is a schematic cross-sectional view of essential parts showing a fourth embodiment of the magneto-optical disk according to the present invention.

FIG. 7 is a schematic cross-sectional view of essential parts showing a fifth embodiment of the magneto-optical disk according to the present invention.

FIG. 8 is a schematic sectional view of a main part of a conventional magneto-optical disk.

FIG. 9 is an explanatory diagram of a magnetic flux locus of a conventional magneto-optical disk.

[Explanation of symbols]

 1, 1 '... Transparent substrate for reading 2, 2' ... Photocurable resin layer 3a, 3a '... Recording layer 31 ... First dielectric film 32 ... Recording film 33 ... Second dielectric film 35 ... High magnetic permeability layer 36 ... Reflective film 37 ... Third dielectric film 38 ... Support substrate 4, 4 '... Protective coating layer 5, 5' ... Optical head 6, 6 '... Magnetic head

Claims (12)

[Claims] 1. A magneto-optical recording medium comprising a transparent substrate, a dielectric film, a recording film, a high-permeability layer, and a protective layer, which are sequentially laminated on the transparent substrate. 2. The magneto-optical recording medium according to claim 1, wherein a reflective film having a heat dissipation function is provided between the recording film and the high magnetic permeability layer. 3. The magneto-optical recording medium according to claim 2, wherein a heat insulating layer having magnetic permeability is provided between the reflective film and the high magnetic permeability layer. 4. A light comprising a transparent substrate, a photocurable resin layer, a first dielectric film, a recording film, a second dielectric film, a high magnetic permeability layer, and a protective layer, which are sequentially laminated on a transparent substrate. Magnetic recording medium. 5. The magneto-optical recording medium according to claim 4, wherein a reflective film having a heat dissipation function is provided between the second dielectric film and the high magnetic permeability layer. 6. The magneto-optical recording medium according to claim 5, wherein a thermal insulating layer having magnetic permeability is provided between the reflective film and the high magnetic permeability layer. 7. A magneto-optical recording medium, wherein a photocurable resin layer, a high magnetic permeability layer, a recording film, a dielectric film, and a transparent substrate are sequentially laminated on a supporting substrate. 8. The magneto-optical recording medium according to claim 7, wherein a reflective film having a heat radiation function is provided between the high magnetic permeability layer and the recording film. 9. The magneto-optical recording medium according to claim 8, wherein a heat insulating layer having magnetic permeability is provided between the high magnetic permeability layer and the reflective film. 10. A photocurable resin layer is sequentially formed on a supporting substrate,
A magneto-optical recording medium comprising a high magnetic permeability layer, a second dielectric film, a recording film, a first dielectric film, and a transparent substrate, which are laminated. 11. Between the high magnetic permeability layer and the second dielectric film,
The magneto-optical recording medium according to claim 10, further comprising a reflective film having a heat dissipation function. 12. The magneto-optical recording medium according to claim 11, wherein a thermal insulating layer having magnetic permeability is provided between the high magnetic permeability layer and the reflective film.