JP2888427B2 - Recording / reproducing method for magneto-optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing method for a magneto-optical recording medium, and is preferably applied to a case where the recording density is further increased.

[0002]

2. Description of the Related Art Hitherto, in a method of manufacturing an optical disk of this kind, a 2P (photo polymerization) method has been proposed in which an optical disk is duplicated by using an ultraviolet curable resin (Japanese Patent Application No. Sho 61-61). No. 111199, Japanese Patent Application No. 61-146731
issue).

That is, in the 2P method, first, FIG.
As shown in (A), a disk stamper 1 on which a fine concavo-convex pattern is formed according to a recording signal and a thickness of about 1.2
Before the ultraviolet irradiation, a liquid ultraviolet curable resin 3 is sandwiched between the glass substrates 2 of about [mm], and the stamper is pressed from the glass substrate 2 side using a pressing roller (not shown) or the like. An ultraviolet curable resin 3 is filled between the substrate 1 and the glass substrate 2.

[0004] Subsequently, as shown in FIG. 2 (B), after the ultraviolet light L _UV emitted from the light source UV from the glass substrate 2 side becomes an ultraviolet lamp or the like is irradiated to cure the ultraviolet curable resin 3, As shown in FIG. 2C, the ultraviolet curing resin 3 is peeled off from the stamper 1 together with the glass substrate 2.

As a result, as shown in FIG. 2 (D), the signal pattern transfer layer 3A having a thickness of several [μm] to several tens [μm] obtained by transferring the fine concavo-convex pattern of the stamper 1 onto the glass substrate 2 is obtained. To form

Thereafter, as shown in FIG. 2 (E), from the pit side of the transfer glass substrate 4 on which the signal pattern transfer layer 3A is formed, aluminum is formed by a technique such as sputtering, vacuum evaporation or spin coating. After the reflection layer 5 is formed, a protective layer 6 is formed of a resin material on the aluminum reflection layer 5 side, and thus the optical disk 7 on which the pit pattern corresponding to the concavo-convex pattern of the stamper 1 is formed.
Can be manufactured.

[0007]

By the way, in the optical disk device or magneto-optical disk device using the optical disk 7 or the magneto-optical disk having the magneto-optical recording layer manufactured as described above, the recording density is increased. Therefore, the wavelength of the laser beam L applied to the optical disk 7 or the magneto-optical disk is shortened, and the aperture ratio (NA (num (num
erical aperture)).

However, the above-mentioned optical disk 7 has an objective lens 8 disposed on the glass substrate 2 side, irradiates a laser beam L through the objective lens 8, and as a result, a signal based on the reflected light reflected by the aluminum reflecting layer. Has been made to read.

Accordingly, between the objective lens 8 and the aluminum reflective layer 5, the thickness of the glass substrate 2 (= 1.2 [mm]) and the thickness of the signal pattern transfer layer 3A (= several [μm] to several tens [ μm]) is present at a minimum, which makes it practically difficult to increase the NA of the objective lens 8.

In order to solve this problem, it is conceivable to reduce the thickness of the glass substrate 2 of the optical disk 7. In this case, however, scratches and dust on the surface of the optical disk 7 have a great effect on the aluminum reflective layer 5. At the same time, there is a problem that the skew amount of the optical disk 7 increases due to an increase in the warpage of the glass substrate 2.

[0011] In addition, in such a case, according to the manufacturing method, the birefringence is expected to increase, and the durability of the aluminum reflective layer 5 against environmental changes may be deteriorated. The measures were still inadequate.

Similarly, when a magneto-optical recording layer is formed on the magneto-optical disk instead of the aluminum reflective layer 5 described above with reference to FIG. 2, it is difficult to increase the NA of the objective lens 8 disposed on the glass substrate 2 side. There was a problem.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a recording / reproducing method for a magneto-optical recording medium capable of further increasing the recording density.

[0014]

According to the present invention, there is provided a magneto-optical recording layer comprising a perpendicular magnetization film.
A recording / reproducing method for a magneto-optical recording medium comprising a thin plate-shaped light transmitting layer 10 having a thickness of 50 to 200 [μm] adhered thereon via an adhesive layer 11A. 5 is irradiated with laser light, and an external magnetic field is applied from the light transmitting layer 10 side.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 explains the principle of the method of manufacturing an optical disk. First, as shown in FIG. 1A, a signal pattern is transferred by a 2P method (FIGS. 2A to 2D). Layer 3
An aluminum reflective layer 5 is formed on the signal pattern transfer layer 3A of the transfer glass substrate 4 on which A is formed by a technique such as sputtering.

Subsequently, a thin cover glass 10 having a thickness of 50 to 200 [μm] is disposed on the transfer glass substrate 4 on the side of the aluminum reflective layer 5. After sandwiching a liquid ultraviolet curable resin 11 having a viscosity of centipoise to tens of centipoise, the transfer glass substrate 4 and the thin cover glass are pressed by pressing the thin cover glass 10 using a pressing roller (not shown). An ultraviolet curable resin 11 is filled between 10.

Subsequently, as shown in FIG.
And irradiating ultraviolet light L _UV emitted from V to cure the ultraviolet curing resin 11, a transparent UV adhesive layer 11A made of the number of thick [μm], the result, the thin cover glass 10 to transfer the glass substrate 4 Glue.

Thus, as shown in FIG. 1C, an optical disk 12 capable of reproducing the pit pattern of the aluminum reflection layer 5 is manufactured through the thin cover glass 10 and the transparent UV adhesive layer 11A.

When the optical disk 12 manufactured as described above is irradiated with the laser beam L through the objective lens 13 arranged on the thin cover glass 10 side, the objective lens 13 The thickness of the thin cover glass 10 (= 50-200 [μm])
The distance can be reduced to the distance obtained by adding the thickness (= several [μm]) of the V adhesive layer 11A.

Thus, in the optical disk device using the optical disk 12, the objective lens 13 can be brought closer to the aluminum reflective layer 5 as compared with the conventional one, so that the NA of the objective lens 13 is higher.
Thus, the optical disk 12 capable of recording at a higher density can be obtained.

According to the above method, the resin 11 is filled between the aluminum reflective layer 5 on the transfer glass substrate 4 and the thin cover glass 10 and then cured to bond the thin cover glass 10 to the transfer glass substrate 4. As a result, the aluminum reflective layer 5
In this way, the optical disk 12 capable of reproducing the image data can be manufactured. In this case, the distance between the objective lens 13 and the aluminum reflective layer 5 is markedly shortened as compared with the related art, so that the NA of the objective lens 13 can be increased. Thus, it is possible to realize a method of manufacturing an optical disk capable of manufacturing the optical disk 12 capable of high-density recording / reproduction with a simple process.

Further, according to the above-described method, the cover glass 10 is adhered to the aluminum reflective layer 5 on the side of the objective lens 13, so that the flatness and the transparency are excellent, the moisture permeability is low, and the scratches and stains are not formed. A strong optical disk can be manufactured.

According to the above-mentioned method, since the same glass substrate is used as the substrate, the occurrence of surface runout and skew can be prevented.

Further, according to the above-described method, the pit pattern of the aluminum reflective layer 5 is reproduced through the thin cover glass 10 and the transparent UV adhesive layer 11A, so that the optical disk capable of effectively eliminating the occurrence of birefringence can be removed. 12 can be manufactured.

The magneto-optical recording medium used in the method for recording / reproducing a magneto-optical recording medium according to the embodiment of the present invention is the same as the method for manufacturing the optical disk 12 described above with reference to FIG. To form a perpendicular magnetization film.

In this case, if an external magnetic field is applied from the objective lens side, the distance between the magnetic head and the perpendicular magnetization film can be further reduced, and a low magnetic field can be used as the external magnetic field. The structure of the magnetic head can be further simplified.

In the above-described embodiment, the case where a glass substrate is used as the substrate has been described. However, the present invention is not limited to this, and it is not necessary to irradiate a laser beam from the substrate side. The same effects as those of the above-described embodiment can be realized by using substrates made of various materials.

Further, in the above-described embodiment, the case where the ultraviolet curable resin 11 is interposed between the transfer glass substrate 4 and the thin cover glass 10 and the resin is filled is described. 11 may be applied to the transfer glass substrate 4 or the thin cover glass 10 side,
Furthermore, the thin cover glass 10 may be subjected to a silane coupling treatment in advance.

In the above-described embodiment, the optical disk according to the present invention is applied to the one in which the laser beam is irradiated from one side of the optical disk to reproduce the information in the aluminum reflective layer. However, the present invention is not limited to this. 2P on both sides
An aluminum reflective layer is formed by a method, and a thin cover glass is adhered to each of the aluminum reflective layers on both sides thereof, and the information of the aluminum reflective layer may be reproduced by irradiating a laser beam from both sides of the optical disc. .

In the above-described embodiment, the case where the signal pattern layer formed of the signal pattern transfer layer is formed by using the 2P method has been described. However, the signal pattern layer is not limited to this, and may be formed by ion etching or the like. Even if it does in this way, the same effect as the above-mentioned embodiment can be realized.

Further, in the above-described embodiment, the present invention is applied to a disk recording / reproducing method. However, the present invention is not limited to this, and is widely applied to a recording / reproducing method of another optical information recording medium such as an optical card. It is suitable.

[0033]

As described above, according to the present invention, the thickness is 50 to 200 [μm] on the magneto-optical recording layer of the substrate via the adhesive layer.
By bonding the thin plate light transmitting layer of
Information can be recorded and / or reproduced from the light transmitting layer side to the magneto-optical recording layer. Thus, the aperture ratio of the objective lens on the side of the light transmitting layer that irradiates the laser beam can be further increased, whereby the information recording density can be further increased, and the laser beam can be applied from the side of the light transmitting layer that irradiates the laser light. An external magnetic field having a low magnetic field can be used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the principle of a method for manufacturing an optical disc according to the present invention.

FIG. 2 is a schematic diagram illustrating a method for manufacturing an optical disk by a 2P method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stamper, 2 ... Glass substrate, 3, 11 ... UV curable resin, 3A ... Signal pattern transfer layer, 5 ... Aluminum reflective layer, 8, 12 ... Optical disk, 10 ... Thin cover glass.

Claims (1)

(57) [Claims] 1. An adhesive layer on a magneto-optical recording layer comprising a perpendicular magnetization film
Through a thin plate-like light transmitting layer with a thickness of 50 to 200 μm
A method for recording and reproducing a magneto-optical recording medium, comprising irradiating a laser beam to the magneto-optical recording layer through the light-transmitting layer, and applying an external magnetic field from the light-transmitting layer side. Characteristic recording / reproducing method for a magneto-optical recording medium.