JPH07141712A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain such a disk type recording medium that a flying head does not touch the surface of the disk in the inner circumference area. CONSTITUTION:Recording and reproducing is preformed in a recording and reproducing device equipped with a floating-type magnetic head 1 for a disk-type optical recording medium having at least a protective film 13 formed on a substrate 11. In this case, the protective film 13 is formed by coating to the inner circumference side of the innermost information recording area 12a so that the film 13 is close to the inner end 1a of the floating-type magnetic head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium suitable for application to a magneto-optical disk.

[0002]

2. Description of the Related Art Various recording / reproducing apparatuses using a recording medium called a magneto-optical disk have been developed. Recording and reproduction are performed on this magneto-optical disk with the configuration shown in FIG. That is, in FIG. 4, 10 indicates a magneto-optical disk,
A signal recording layer is formed on the magneto-optical disk 10. The magnetic head 1 is arranged on the upper side and the optical pickup 4 is arranged on the lower side so as to sandwich the signal recording layer, and the disk can be irradiated with laser light. To do so. Then, at the time of recording, the magnetic head 1 is heated while the recording portion is heated by the laser light emitted from the optical pickup 4 to the disk 10.
The process of recording the magnetic field generated in 1. is performed. This recording process is called a magnetic field modulation recording method.

At the time of reproduction, the light receiving means in the optical pickup 4 detects the state of the returning light of the laser beam emitted from the optical pickup 4 to the signal recording layer of the disk 10, and reproduces the data recorded in the signal recording layer. To do.

The magneto-optical disk 10 on which recording / reproduction is performed in this manner has a cross section as shown in FIG. That is, the recording layer 12 is formed on the transparent substrate 11, and the protective film 13 is formed on the recording layer 12. In this case, as the recording layer 12, for example, SiN, TbFeCo, SiN, and Al layers are sequentially formed from the substrate 11 side. The protective film 13 is formed of, for example, an ultraviolet curable resin, and is referred to as a spin coating method in which the resin is dropped on the surface of the disc and the disc is rotated at a high speed so that the disc is spread over the entire recording layer forming surface and cured. It is formed by the method.

FIG. 5 shows the arrangement of the magnetic heads on the disk 10 having such a structure. The core 2 which is the magnetic pole portion of the magnetic head 1 is set at a predetermined position on the surface side of the disk 10 and the supporting member is provided. The magnetic head 1 is supported by the gimbal 3. Then, while the magneto-optical disk 10 is rotated by the drive unit on the recording / reproducing apparatus side, the magnetic head 1 is levitated by the air flow generated between the surface of the disk 10 and the magnetic head 1, and the surface of the disk 10 is moved. The distance between the core and the core 2 is kept constant. Further, the recording layer 12 just below the core 2 is irradiated with the laser light L from an optical pickup (not shown). The magnetic head which floats the magnetic head on the disk surface in this way is called a flying head or a floating head.

By using such a flying head, the distance between the core 2 and the surface of the disk 10 can be kept constant, and data can be stably recorded on the disk in a constant state.

[0007]

By the way, in order for the magnetic head to float stably as shown in FIG. 5, the disk surface must be smooth. However, the maximum recording layer in the inner peripheral portion of the disk is required. In the vicinity of the inner peripheral edge, the thickness of the disk changes because the recording layer and the protective film are removed. Therefore, when recording or reproducing on the inner circumference of the disc, the flying state of the magnetic head is not stable, and in some cases, the magnetic head may come into contact with the surface of the rotating disc to remove the disc. There was the inconvenience of causing damage.

That is, as shown in FIG. 6, the protective film 13 is formed at the innermost peripheral edge 12a of the recording layer 12 on the inner peripheral portion of the disk.
The thickness of the disk is changed by the thickness of the recording layer 12 and the protective film 13. Therefore, the airflow generated by the rotation of the disk is disturbed by the change in the thickness, the flying state of the magnetic head is disturbed, the magnetic head vibrates, and a part of the magnetic head becomes a surface of the disk. (The position indicated by x in FIG. 6 is the contact portion).

FIG. 7 shows an example of the flying state of the magnetic head with respect to the disk. The example shown in FIG.
22 mm to 42 m radius for a disc with a radius of 43 mm
A recording layer is formed in a range r ₀ of m, and a radius of 19 mm is used as a protective film of an ultraviolet curable resin so as to protect the recording layer.
An example in the case of forming by spin coating in the range of up to 43 mm is shown. In this example, the protective film thickness is at least 9 μm at the recording layer (9 μm is sufficient to protect recorded data), and the disk is rotated at 1800 rpm. The position of the magnetic head shown in the figure is the head position (radial position and flying height) when recording on the innermost recording layer and the head position (radial position and radial height when recording on the outermost recording layer). Flying height). The magnetic head used here has a size of 5 mm (in the radial direction of the disk) × 6 mm (in the circumferential direction of the disk), and the core is arranged at a position 0.5 mm from the end near the outer circumference.

In this example, it is understood that the flying height of the magnetic head at the time of recording on the innermost circumference is not sufficient and the magnetic head collides with the disk surface at the position indicated by x. The flying head type magnetic head requires a slider portion (a portion directly facing the surface of the disk) having a large area in order to stably fly, and therefore the shape of the magnetic head is relatively large. It has a shape that allows easy collision.

An object of the present invention is to prevent such a flying head from contacting the disk surface at the inner peripheral portion.

[0012]

According to the present invention, for example, as shown in FIG. 1, a disk-shaped optical recording medium 1 having a substrate 11 and a protective film 13 formed on the substrate 11 is formed.
0, when recording / reproducing is performed by the recording / reproducing apparatus equipped with the levitation type magnetic head 1, the inner circumference end 1a of the levitation type magnetic head 1 is located closer than the innermost information recording area 12a. The protective film 13 is applied even to the peripheral side.

Further, in this case, an ultraviolet curable resin is used as the protective film.

[0014]

According to the present invention, since the protective film is applied even to the inner peripheral side close to the inner peripheral end of the magnetic head, the magnetic head can perform recording and reproduction in the innermost information recording area of the disk. Even when it is performed, the surface of the recording medium adjacent to the magnetic head is kept almost smooth by the extended protective film, and the magnetic head stably floats so that it does not come into contact with the surface of the recording medium.

[0015]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3, parts corresponding to those of FIGS. 4 to 7 described as a conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this example, the flying head is applied to a magneto-optical disk used for recording, and is constructed as shown in FIGS. That is, in the magneto-optical disk 10 of this example, the recording layer 12 is formed on the transparent substrate 11, and the protection 13 is further formed on the recording layer 12. FIG. 1 is a diagram showing the vicinity of the innermost peripheral edge 12a of the recording layer 12 on the inner peripheral portion of the magneto-optical disk 10 (the left side is near the center of the disk, and the right side is near the outer circumference of the disk).
In this example, the protective film 13 applied on the recording layer 12
Is a predetermined range r from the innermost peripheral edge 12a of the recording layer 12.
It is formed by extending only _{1 to the} inner circumference side. The range r ₁ to be extended is from the core 2 which is the magnetic pole part of the magnetic head 1,
It is made slightly longer than the length L1 to the inner peripheral end 1a of the magnetic head 1.

The protective film 13 of this example is formed by spin coating while using an ultraviolet curable resin.

Therefore, the magneto-optical disk 10 having the structure of this example is used.
When the plane of view, as shown in FIG. 2, the recording layer 12 is formed in a predetermined range r _0, the formation range r ₀ of the recording layer 12
The protective film 13 is formed in the range r ₂ from the position extended by r ₁ to the inner peripheral side to the outer peripheral end. Note that FIG.
In the figure, 10a is a through hole in the center of the disc.

Here, the magneto-optical disk 10 of this example is shown in FIG.
In this case, the outer diameter of the disc 10 is 43 mm, and the formation range r ₀ of the recording layer 12 is a radius of 22 mm to 42 mm.
3 is formed in a radius of 16 mm to 43 mm by a spin coating method, the protective film 13 has a sufficient thickness (about 9 μm or more) as a protective film from a position of a radius of about 17 mm,
The film thickness gradually increases toward the outer peripheral side.

When the magneto-optical disk having the shape shown in FIG. 3 is rotated at 1800 rpm, the shape of the head is 5 mm (disk radial direction) × 6 mm (disk circumferential direction), and the core is near the outer circumference. FIG. 3 shows the position of this flying head (magnetic head) when recording is performed with the flying head at a position 0.5 mm from the end. The position of the magnetic head shown in FIG. 3 is the head position (radial position and flying height) when recording on the innermost recording layer.
And the head position (radial position and flying height) when recording on the outermost recording layer.

As can be seen from FIG. 3, in the case of the magneto-optical disk of the present example, when the magnetic head is located at a position corresponding to the innermost recording layer, the innermost portion of the innermost recording layer is removed. Due to the protective film extended to the peripheral side, the thickness of the disk surface hardly changes in the area close to the magnetic head, and a stable air flow is generated as the disk rotates, causing the magnetic head to move several micrometers from the disk surface. Stable at the height of. Therefore, when the magnetic head moves to the position of the innermost peripheral portion of the disk as in the conventional case, the magnetic head does not come into contact with the surface of the disk, and it is possible to prevent the occurrence of an accident in which the head damages the magneto-optical disk. .

Further, since the magnetic head does not come into contact with the surface of the disk in this way, the position where the core is provided in the magnetic head can be set closer to the outer circumference of the disk, which is good as a recording / reproducing apparatus. Can be configured to. That is, the core of the magnetic head that constitutes the flying head is
It is preferable to provide the slider at the end portion in terms of manufacturing, and the position closer to the outer circumference as described above can be achieved without specially providing a mechanism for preventing contact with the disk.

Further, as can be seen from the film thickness shown in FIG.
When the protective film is formed by the spin coating method, since the thickness of the protective film on the inner peripheral side is thinner than that on the outer peripheral portion, the weather resistance of the recording layer on the inner peripheral side is inferior to that on the outer peripheral side. In the case of this example, since the protective film on the inner peripheral side is extended, the weather resistance of the recording layer on the inner peripheral side is improved by that much, and the recording layer is well protected by the protective film.

In the above-mentioned embodiments, the UV-curable resin is used as the protective film, but other substances that protect the recording layer may be used. Further, the protective film may be formed of a plurality of layers. In this case, at least one layer may be formed of an ultraviolet curable resin. When the protective film is formed of a plurality of layers in this way, the protective films of all the layers may be extended to the inner peripheral side as described above, or the thin layer may be the recording layer portion only. It may be provided in the. Further, in the above-described embodiment, the range in which the protective film is extended to the inner peripheral side is set to be substantially the same as the portion facing the magnetic head, but it may be extended to the inner peripheral side.

The shape and thickness of the disk shown in FIG. 3 are examples, and other shapes and thicknesses may be selected.

Although the protective film is formed by the spin coating method, it may be formed by another method.

Further, in the above-mentioned embodiment, the present invention is applied to the magneto-optical disk, but it is needless to say that the present invention can be applied to other disk-shaped recording media in which the flying head is used for recording and reproducing.

[0028]

According to the present invention, since the protective film is applied to the inner peripheral side which is close to the inner peripheral end of the magnetic head,
Even when the magnetic head performs recording or reproduction in the innermost information recording area of the disk, the surface of the recording medium adjacent to this magnetic head is kept almost smooth by the extended protective film, which stabilizes the magnetic head. It is possible to prevent an accident that the magnetic head flies and stops contacting the surface of the recording medium, and the magnetic head damages the recording medium.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line I-I of FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a positional relationship between a recording medium and a magnetic head of one example.

FIG. 4 is a perspective view showing a recording / reproducing state of a magneto-optical disk.

FIG. 5 is a cross-sectional view showing the configuration of a conventional recording medium.

FIG. 6 is a cross-sectional view showing the configuration of a conventional recording medium.

FIG. 7 is a characteristic diagram showing a positional relationship between a conventional recording medium and a magnetic head.

[Explanation of symbols]

 1 magnetic head 2 core 3 gimbal 10 magneto-optical disk 11 transparent substrate 12 recording layer 12a inner peripheral edge of recording layer 13 protective film

Claims (2)

[Claims] 1. A disk-shaped optical recording medium comprising a substrate and at least a protective film formed on the substrate, wherein a recording / reproducing apparatus equipped with a floating magnetic head is used for recording / reproducing.
When performing reproduction, to the inner peripheral side closer to the inner peripheral end of the floating magnetic head than the innermost information recording area,
An optical recording medium coated with the above protective film. 2. The optical recording medium according to claim 1, wherein an ultraviolet curable resin is used as the protective film.