JP2774877B2 - Optical disc manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, and more particularly to a method for manufacturing an optical disk.

[0002]

2. Description of the Related Art A substrate of an optical disk on which information is recorded and reproduced by irradiating a laser beam is made of a disk-shaped glass or a transparent resin having a pregroove on its surface. at least one surface, magnetized perpendicularly _{(Tb-SiO 2 / Tb-} Fe-CO /
Tb-SiO ₂₎ magnetic film is formed as a recording medium.
On the substrate of such an optical disc or a recording medium, a protective layer made of a synthetic resin having a property of transmitting the laser beam is formed.

FIG. 3 is a flowchart showing an example of a method for manufacturing an optical disk. A recording medium 2 is vapor-deposited on a disk-shaped substrate 1 which has been formed into predetermined external dimensions and has tracks and groups formed on its surface, for example, by sputtering or CVD (FIG. 3 (a)). Then, the substrate 1 is set on a turntable 15 of a spin coater, and the turntable 15 is rotated at high speed together with the substrate 1 around a shaft 16 while dropping a liquid resin 3a such as an ultraviolet curable resin near the center of the substrate 1. Then, the resin 3a is coated on the substrate 1 and the recording medium 2 while moving the resin 3a toward the outer periphery of the substrate 1 by centrifugal force (FIG. 3B). Further, the synthetic resin 3a is irradiated with ultraviolet rays toward the resin 3a.
Is cured (FIG. 3 (c)). The step of forming the protective layer 3 as described above is performed in the same manner on the back surface of the substrate 1 to obtain the optical disk 20 (FIG. 3D).

[0004]

However, in the optical disk 20 manufactured through the above steps, as shown in FIG. 3D, the uncured synthetic resin 3a deviates from the front surface or the back surface of the substrate 1, and Hardened by ultraviolet irradiation on the outer peripheral side surface 1a of the optical disk 20 to form a burr 3b and adhere to the optical disk 20, which often causes a dimensional error in which the outer diameter of the optical disk 20 becomes larger than an expected value.

In recent years, the demand for optical disks having an outer diameter of 3.5 inches has been increasing in place of optical disks having an outer diameter of 5 inches with the downsizing of related devices. In the optical disc of 3.5 inch outer diameter standard, the outer diameter error due to the burr 3b, which could not be a serious problem in
It often deviates from the tolerance of the outer diameter dimension specified by the (nternational Standard Organization).

To remove the burr 3b, FIG.
As shown in FIG.
(b) As shown in FIG.
A method of wiping a with a wiping tool 18 such as a sponge may be considered, but this complicates the manufacturing process of the optical disk, and has a problem in reducing the manufacturing cost. The present invention has been proposed in view of the above-mentioned conventional circumstances, and has as its object to provide a method of manufacturing an optical disk which simplifies a process of forming a protective layer of the optical disk.

[0007]

In order to achieve the above object, the present invention employs the following means. That is, as shown in FIG. 1, in a method of manufacturing an optical disc in which a protective layer 3 made of a resin 3a is formed on a substrate 1 or a recording medium 2 formed on the surface of the substrate 1, before the protective layer 3 is formed, This is a method for manufacturing an optical disk in which a release agent 4 is formed on the outer peripheral side surface 1a of the substrate 1. In particular, the contact angle θ of the resin 3a to be the protective layer 3 with the release agent 4 is set to 40 ° or more. desirable.

[0008]

In the above configuration, as shown in FIG. 1, the outer peripheral side surface 1a of the substrate 1 is hardly wet by the release agent 4 with the resin 3a to be the protective layer 3. The resin 3a protruding from the outer peripheral side surface 1a falls by gravity or is shaken off by centrifugal force, so that it is possible to suppress or prevent the resin 3a from adhering to the outer peripheral side surface 1a. In addition, the burr 3b due to the resin 3a partially adhered can be easily removed from the release agent 4.

Further, as shown in FIG.
By selecting the material of the release agent 4 or the resin 3a so that the contact angle θ of the “a” with the release agent 4 becomes 40 ° or more, the above-described action is reliably ensured. A part of 3a may adhere to the outer peripheral side surface 1a or may be difficult to remove, which is not preferable.

The release agent 4 can be easily removed by using a predetermined solvent, and there is no fear that the optical disk will be adversely affected.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a flowchart of one embodiment according to the present invention, and FIG. 2 is an explanatory diagram for comparing the wettability of a synthetic resin serving as a protective layer. As shown in FIG. 1, a recording medium 2 is vapor-deposited on a polycarbonate substrate 1 previously formed into a disk having a predetermined outer diameter and a predetermined thickness and having tracks and grooves formed on its surface, for example, by sputtering or CVD. (FIG. 1 (a)).

Next, a sponge roller 11 impregnated with a fluorine release agent (for example, trade name: MS188, manufactured by Daikin Industries, Ltd.) for the protective layer is brought into contact with the outer peripheral side surface 1a of the substrate 1, and the release agent is brought into contact therewith. 4 is formed (FIG. 1 (b)). The release agent 4 can be easily removed by wiping using a predetermined solvent. Thereafter, the substrate 1 is set on the turntable 15 of a spin coater, and a synthetic resin (for example, SD-301, manufactured by Dainippon Ink and Chemicals, Inc.) 3a having ultraviolet curability is dropped near the center of the substrate 1 while dropping. Axis 1
6, the turntable 15 is rotated at a high speed together with the substrate 1 so that the synthetic resin 3a is removed by centrifugal force.
While moving toward the outer periphery of the substrate 1 and the recording medium 2
(FIG. 1 (c)). In this step, the synthetic resin 3a drops from the upper peripheral edge of the substrate 1 and adheres to the outer peripheral side surface 1a covered with the release agent 4, but the synthetic resin 3a separates as shown in FIG. Contact angle θ with mold agent 4
Is approximately 50 °, and the contact angle に 対 す る with the polycarbonate substrate 1 shown in FIG. 2 (b) is about 5 °, compared with the case where the mold release agent 4 formed on the outer peripheral side surface 1a is significantly leaky. As a result, all the synthetic resin 3a attached to the outer peripheral side surface was shaken off with the rotation of the turntable 15. The method for forming the protective layer 3 can be arbitrarily selected, but the step of removing the synthetic resin 3a attached to the outer peripheral side surface 1a simultaneously with the formation of the protective layer 3 as described above is not required at all. It is desirable to use a spin coater as a forming means.

Further, the synthetic resin 3a is irradiated with ultraviolet rays to cure the synthetic resin 3a (FIG. 1 (d)).
1 (a) to 1 (d) are also performed on the back surface of the optical disk 10 to obtain an optical disk 10 in which no burr made of the synthetic resin 3a constituting the protective layer 3 adheres to the outer peripheral side surface 1a. (FIG. 1 (e)). The present invention is not limited to the material of the synthetic resin 3a constituting the protective layer 3 and the material of the release agent 4 used in the above embodiment, and various materials can be used. Further, the step of forming the release agent 4 can be performed immediately after the formation of the substrate 1 instead of after the deposition of the recording medium 2.

[0014]

As described above, according to the present invention, before the protective layer is formed, the release agent made of a highly oil-repellent material is formed on the outer peripheral side surface of the substrate, whereby the outer peripheral side surface of the substrate is formed. Since the burr of the resin constituting the protective layer does not adhere or can be easily removed even if it adheres, it is not necessary to remove the burr in a separate process, so that the manufacturing process can be simplified and the An adverse effect can be eliminated, which greatly contributes to reduction of manufacturing cost and improvement of product yield.

[Brief description of the drawings]

FIG. 1 is a flowchart of one embodiment according to the present invention.

FIG. 2 is an explanatory diagram comparing the leakiness of a resin serving as a protective layer.

FIG. 3 is a flowchart showing a manufacturing procedure of a conventional example.

FIG. 4 is an explanatory diagram showing a problem of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 substrate 1b outer peripheral side surface 2 recording medium 3 protective layer 3a resin 4 release agent θ contact angle

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/26 531 G11B 5/84

Claims (2)

(57) [Claims] 1. A method for manufacturing an optical disk, wherein a protective layer made of a resin is formed on a substrate or a recording medium formed on a surface of the substrate, wherein before the protective layer is formed, an outer peripheral side surface of the substrate is separated from the protective layer. A method for producing an optical disk, comprising applying a mold agent. 2. The method for manufacturing an optical disk according to claim 1, wherein a contact angle of the resin serving as a protective layer with respect to the release agent is 40 ° or more.