JPH03132935A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain a disk which is hard in its surface hardness and in addition, is difficult for dust to stick by providing a protection layer which is constituted of the mixture of ultraviolet ray hardening resin and inorganic substance, and in addition, is conductive. CONSTITUTION:The surface of a disk-shaped based plate 1 provided with a recording film 5 on an uneven pattern is coated in the shape of a disk with the mixture 2 of the ultraviolet ray hardening resin and alumina prepared beforehand, and a stamper 3 of a flat surface is put upon it. Then, the mixture 2 of the ultraviolet ray hardening resin and the alumina is spread out by applying load over 10 kg to the whole base plate from the upper part. After that, it is irradiated by ultraviolet rays 4, and the mixture of the ultraviolet ray hardening resin and the alumina is hardened, and when the stamper 3 is removed, the protection film by the mixture of the ultraviolet ray hardening resin and the alumina is formed on the recording film 5 of the base plate. Thus, the disk protection film whose surface hardness is high and uniform, and in addition, which is difficult for the dust to stick is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to optical discs, and more particularly to an optical disc protective film that strengthens the protective film on a recording film and at the same time reduces dust adhesion. [Prior Art] In recent years, research has been conducted on overwriting using a magnetic field modulation recording method using a floating magnetic head. Hereinafter, an example of overriding using the magnetic field modulation recording method will be explained with reference to FIG. 6 is a magnetic head, 7 is a lens that narrows down the laser beam, and 8 is a laser beam. The structure of the disk is SiN on the substrate 9.
Enhancement film 10, TbFeC. A recording film 11, a SiN protective layer 12, and an ultraviolet curing resin protective film 13 are formed in this order. A magnetic head 6 is disposed on the upper surface of the protective film 13, and applies a magnetic field whose polarity is inverted according to a recording signal to the optical disk. Furthermore, an optical system is arranged on the substrate 9 side and is used for heating the recording film, reproducing signals, and the like. 2. When recording, the magnetization is extinguished by irradiating a light spot and heating the recording film 11 with optical energy, and at the same time, the magnetic head 6 generates a magnetic field that is positively inverted in accordance with the recording signal. As a result, when the recording film 11 is cooled after the light spot has passed, a magnetization distribution is formed on the optical disk in a direction corresponding to the polarity of the recording magnetic field. In the case of reproduction, a laser beam is irradiated, and the rotation of the polarization plane due to the Kerr effect can be obtained as a light intensity signal. This type of device and method are also discussed, for example, in "Electronic Materials J, July 1988 issue, pages 76 to 82. Problem 1 to be Solved by the Invention The above-mentioned prior art Considering that the magnetic head comes into contact with the protective layer in the override method, which is a recording method for magnetic disks, it was necessary to increase the surface hardness. It is unavoidable that dust will enter the interior.In this case, it may be caused by friction with the air due to the high speed rotation of the disc, or by contact start/stop (C8/S).
Contact 5tart/5top) Static electricity is generated on the disk due to contact between the disk and the magnetic head during operation, and dust inside the device is collected on the disk. The collected dust contaminates the lens of the optical head, deteriorating the characteristics of the aperture spot.
Problems arise in that incomplete recording and reproduction errors occur, and the flying characteristics of the magnetic head deteriorate due to dust deposited on the disk. An object of the present invention is to provide an optical disc that has a high surface hardness and is difficult to attract dust. [Means for Solving the Problems 1] The above object is achieved by providing a protective layer that is made of a mixture of an ultraviolet curable resin and an inorganic substance and has electrical conductivity or hydrophilicity. The above inorganic substances include SiO2, Al□○1, Cr, 0
3. Fungi such as ZrO2, nitrides such as Si3N4 and BN, carbides such as SiC, graphite, or mixtures thereof are preferred, and among these, Al□03 is particularly preferred because it is hard and has a uniform particle size. In addition, to provide conductivity, metal powder such as Cu, Fe, Al, or carbon may be mixed, and to provide hydrophilicity, a surfactant having a woody group may be mixed. good. [Function 1] The protective layer made of a mixture of an ultraviolet curable resin and an inorganic substance has a high hardness as a whole, depending on the hardness of the inorganic substance. Therefore, in the magnetic field modulation recording method, when performing override by the magnetic head, the recording film is not damaged by the head, and stable recording/reproduction can be performed. In addition, since the protective layer is conductive or hydrophilic, friction with air due to high-speed rotation of the disk, or C8/
Static electricity is less likely to be generated due to contact between the disk and the magnetic head during S operation, and dust inside the device is not collected on the disk. Therefore, it is possible to realize a highly reliable magneto-optical disk device in which the optical head and the disk are not stained by dust, and in which recording/reproducing errors and head crashes do not occur. [Example] Hereinafter, an example of the present invention will be explained using FIG. In this example, a case will be described in which alumina (Al□O1) is used as the inorganic substance. A mixture 2 of ultraviolet curable resin and alumina prepared in advance is applied in the same disk shape onto a disk-shaped base 1 having a recording film 5 on a concavo-convex pattern, and a stamper 3 with a flat surface is placed on top of it. They are stacked one on top of the other, and a load of 10 kg or more is applied over the entire substrate to spread the mixture 2 of ultraviolet curing resin and alumina. After that, the ultraviolet ray 4 is irradiated to harden the mixture 2 of the ultraviolet curable resin and alumina, and the stamper 3 is removed. J5
A protective film made of the mixture 2 of ultraviolet curing resin and alumina is formed on top of the protective film. Note that other examples of inorganic substances include SiO2, Cr,
Examples include oxides such as O, ZrO2, nitrides such as Si3N4 and BN, carbides such as SiC, graphite, and mixtures thereof. In particular, graphite can also be used as a lubricant. Further, as a method for applying a mixture of an ultraviolet curable resin and an inorganic substance, it is also possible to create a protective film by spin coating using a spinner. The mixing ratio of inorganic substances to ultraviolet curing resin is 6 by weight.
As a result of experiments, it has been found that when the amount is 0% or more, the surface of the protective film becomes rough, and when it is less than 10%, the strength is poor. From this, the mixing ratio is preferably in the range of about 20% or more and 50% or less. In order to reduce dust adhesion to the disk, the protective film is made to have conductivity or hydrophilicity. If the protective film is conductive or hydrophilic, charges will move more easily within the protective film, making it difficult for static electricity to occur. Therefore, the effect of collecting dust due to static electricity can be reduced. In order to give the protective film electrical conductivity, metal powders such as Cu, Fe, Al, etc., oxides such as Sn○, or carbon black are mixed in with the above-mentioned materials (in addition to footwear). For example, a surfactant having a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonate, an amine, or a polyethylene oxide may be mixed. It is electrically connected to the spindle 15.The spindle 15 is grounded, so the protective film 2 is in a grounded state.Therefore, the charge generated in the protective film 2 moves in the direction of the ground potential, thereby reducing static electricity on the disk. In the above explanation, the protective film 2 itself has conductivity or hydrophilicity, but it is also possible to newly provide a layer having conductivity or hydrophilicity between the recording film and the protective film. In this case, it goes without saying that the generation of static electricity can be further suppressed by adopting a structure in which the disk hub shown in FIG. 3 is brought into contact with this layer. Effect] According to the present invention, the surface hardness is high and uniform, and at the same time,
It is possible to produce a disk protective film to which dust does not easily adhere. Therefore, the optical head and disk are not contaminated by dust, so while maintaining the medium exchangeability that is a feature of optical disks, there are no errors during recording/playback, and head crashes are less likely to occur, increasing reliability. A magneto-optical disk device with high performance can be realized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the manufacturing process of the optical disc of the present invention;
FIG. 2 is an explanatory diagram of override using the magnetic field modulation recording method, and FIG. 3 is a sectional view showing the relationship between the disk and the spindle. Explanation of symbols 1...Base, 2...Mixture of ultraviolet curing resin and inorganic powder, 3...Stamper, 4...Ultraviolet light, 5
Recording film, 6... Magnetic head, 7... Lens, 8...
Laser light, 9... Substrate, 1o... Enhancement film, 1
1.Recording film, 12.13...Protective film, 14...Hub, 15...Spindle burn 1 Yu/A candy 2 J6 Shi-Sa first cause ni deka ku

Claims (1)

[Claims] 1. An optical disc in which a protective layer made of an ultraviolet curing resin or a mixture of ultraviolet curable resin and other substances is formed directly or through another layer on the recording film, wherein the protective layer is electrically conductive. An optical disc characterized by having. 2. The optical disc according to claim 1, wherein the other substance is a single conductive substance or a mixture of an inorganic substance and a conductive substance. 3. The optical disc according to claim 1, wherein the other substance is a single hydrophilic substance or a mixture of an inorganic substance and a hydrophilic substance. 4. The optical disc according to claims 1 and 2, wherein the conductive substance is metal powder such as Cu, Fe, Al, etc. or carbon. 5. The optical disc according to claims 1 and 3, wherein the hydrophilic substance is a surfactant having a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonate, or an amine. 6. The inorganic substance is SiO_2, Al_2O_3, Cr
Oxide such as _2O_3, ZrO_2, or Si_3
Nitride such as N_4, BN, or carbide such as SiC,
4. The optical disc according to claim 1, 2, or 3, wherein the optical disc is made of graphite or a mixture thereof. 7. The optical disc according to claim 1, wherein the other layer is a protective film made of SiN. 8. The optical disk according to claim 1, wherein the other layer is made of the conductive material. 9. The optical disc according to claim 1, wherein the other layer is made of the hydrophilic substance. 10. The optical disc according to claim 1, wherein the protective film is grounded through a disc hub.