JPH05114167A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To eliminate the trouble by the adhesion of dust and dirt on a substrate surface by electrification and the trouble by the generation of flaws. CONSTITUTION:A 1st protective film 2, a magnetic film 3, a 2nd protective film 4, a reflection film 5, an org. protective film 6, and an inorg. antistatic film 7 are formed on one surface of the substrate 1 and an inorg. antireflection film 8 is formed on the surface on the opposite side. The antireflection film 8 is formed to include >=1 layer of transparent conductive films and has an antistatic property as well. The transparent conductive films and inorg. antistatic film are constituted of the transparent conductive films mainly consisting of In2O3, ITO, SnO2, ZnO, CdO, and ZnS. The antistatic function and antireflection function are simultaneously imparted to the recording medium in this way and the surface hardness of the recording surface is increased, by which the above-mentioned purposes are attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium for recording and reproducing information with a laser beam.

[0002]

2. Description of the Related Art Since a substrate for supporting a recording layer in an optical information recording medium is generally formed of a dielectric material such as polycarbonate, glass, 2P (photopolymer) resin, etc. It's easy to do. When the optical information recording medium is charged, minute dust or dirt adheres to the surface of the substrate (hereinafter referred to as the outer surface) where the recording layer is not formed due to static electricity, which hinders reading and writing of information. The electrostatic charge causes a malfunction of the electronic circuit. This problem of charging is also the same on the surface of the substrate on which the recording layer is formed (hereinafter referred to as the recording surface).

Further, the above charging has an influence on the overwrite (overwriting) by the magnetic field modulation method using the floating magnetic head, which has been actively researched in recent years, but when the overwrite is further examined, When the magnetic head contacts the surface of the substrate, the surface hardness of the recording surface becomes important.
For example, the magnetic head is in contact with the recording surface when the magneto-optical disk starts and stops rotating, but when the hardness of this recording surface, that is, the hardness of the protective layer formed on the disk top layer is low, There is a high risk that the magneto-optical disk will become unusable due to scratches at the contact area and corrosion of the recording layer. As described above, it is desirable that the outer surface portion of the optical information recording medium has an antireflection function and an antistatic function, and that when overwriting, the recording surface has both an antistatic function and a high surface hardness. ..

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a highly reliable optical information recording medium in which static electricity and scratches are prevented. To do.

[0005]

In order to achieve the above object, according to the present invention, an optical information recording medium which is composed of at least a substrate and a recording layer and which records and reproduces by using a laser beam has a read side surface thereof. An optical information recording medium is provided, which comprises an inorganic antireflection film having one or more transparent conductive films and having an antistatic function, and an inorganic antistatic film provided on a surface opposite to a reading side. ..

The optical information recording medium of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing a configuration example of an optical information recording medium according to the present invention, in which a first protective film 2, a magnetic film 3, a second protective film 4 are formed on one surface (recording surface) of a transparent substrate 1. Reflective film 5,
An organic protective film 6 and an inorganic antistatic film 7 are formed, and an inorganic antireflection film 8 including one or more transparent conductive films is formed on the other surface (outer surface).

Polycarbonate, acrylic, epoxy, PMMA (polymethylmethacrylate) is used for the transparent substrate 1.
A synthetic resin such as glass, a 2P substrate, or the like is used.

The first protective film 2 and the second protective film 4 are provided in order to have a passivation effect for preventing the magnetic film 3 from being corroded by H ₂ O, O _2, etc.
A nitride such as iNx or an oxide such as In ₂ O ₃ or SiOx is used.

The magnetic film 3 is Tb-Dy-Fe-Co.
It is preferable to use a rare earth metal-transition metal amorphous alloy film having perpendicular magnetic anisotropy such as, but not limited to this. The magnetic film 3 may be a single layer or a multilayer.

The reflective film 5 is for enhancing the magneto-optical effect, and is made of a material having a high reflectance such as Al or Au.

The organic protective film 6 is for preventing the corrosion of the films below the reflective film 5, and is made of ultraviolet curable resin, thermoplastic resin, hot melt resin or the like.

The inorganic antistatic film 7 is made of In ₂ O ₃ , ITO,
A transparent conductive film whose main material is an inorganic material such as SnO ₂ , ZnO or ZnS is used. A suitable film thickness is about 100 to 2000Å. Further, the same structure as the antireflection layer 8 (transparent insulating material and transparent conductive film) is also possible.

The antireflection film 8 has its own refractive index based on the refractive indices of the protective films 2 and 4 and the substrate 1 according to the design theory of the antireflection layer that has been widely used in the conventional optical parts. With magnesium fluoride, silicon monoxide, silicon dioxide, titanium oxide, cerium oxide, aluminum oxide, etc.,
A film made of a transparent insulating material used as an antireflection layer of a conventional optical component and In having a refractive index of about n = 2
₂ O ₃ , ITO, SnO ₂ , ZnO, ZnS and the like are combined with a transparent conductive film whose main material is a transparent conductive film. Figure 2
An example of the structure of the antireflection film 8 is shown in FIG. The antireflection film 8 is formed by laminating the transparent insulating films B and B ′ and the transparent conductive film A, and the respective thicknesses of the transparent insulating films B and B ′ are λ / 4 and the transparent conductive film A is λ /.
In No. 2, the refractive index is different. Here, λ is the wavelength of the writing / reading laser, and the film thickness referred to here is the optical film thickness (nd) [n is the refractive index and d is the actual film thickness]. In such an antireflection layer structure, since each film constituting the layer structure is thin, a sufficient antistatic effect can be realized even if the transparent conductive film is not directly exposed to the outside.

The present invention has been described above by taking the magneto-optical recording medium of one constitutional example as an example, but the present invention is not limited to this, and various kinds of modifications and changes are possible, for example, on the reflection film 5. The organic protective film 6 may be omitted. In addition to the magneto-optical recording medium, a video disc, a CD-ROM, a CD-V, a CD-I, which is desired to have an antistatic function together,
It can be applied to various other optical information recording media such as a CD-XA and a phase change type rewritable optical disk.

[0015]

EXAMPLES Next, examples of the present invention will be described.

Example 1 One side of a polycarbonate (PC) substrate having a diameter of 130 mmφ and a thickness of 1.2 mm A SiN film as a first protective film, a TbDyFeCo film as a magnetic film, and a Si as a second protective film.
An N film, an Al film as a reflection film, an In ₂ O ₃ film as an antistatic film are further provided on the N film, and an SiO ₂ film, an In ₂ O ₃ film and a SiO film are provided on the opposite surface. An antireflection film was provided to obtain a recording medium according to the present invention. The thickness of the antistatic film is 350Å, and the thickness of the antireflection film is SiO.
The film was λ / 4, the In ₂ O ₃ film was λ / 2, and the SiO film was λ / 4. Table 1 shows each constituent material. Where λ is write /
It is the wavelength of the reading laser, and the film thickness referred to here is the optical film thickness (nd) [n is the refractive index, and d is the actual film thickness].

[Table 1]

Example 2 In Example 1, the antireflection film was formed of SiO (λ / 4 thickness) /
A recording medium according to the present invention was obtained in the same manner except that ITO (λ / 2 thickness) / SiO ₂ (λ / 4 thickness) was used.

Example 3 In Example 1, the antistatic film was made of ITO (350 Å thickness).
And the antireflection film is SiO (λ / 4 thickness) / In ₂ O
_A similar recording medium according to the present invention was obtained except that the thickness was ₃ (λ / 2 thickness) / SiO ₂ (λ / 4 thickness).

Example 4 In Example 1, the substrate was glass and the antireflection film was I.
A recording medium according to the present invention was obtained in the same manner except that TO (λ / 2 thickness) / SiO ₂ (λ / 4 thickness) was used.

Comparative Example 1 In Example 1, the antistatic film was (5 μm thick) (organic antistatic film) and the antireflection film was (5 μm thick) (organic antireflection film).

Comparative Example 2 The same as Example 1, except that the antistatic film (thickness of 5 μm) (organic antireflection film) is not provided.

The reflectance, Kerr rotation angle, surface resistance and surface hardness of each recording medium produced as described above, and dust test (about 10 years with the recording medium mounted in a driving device and rotated) A considerable amount of dust was adsorbed on the dust tester, and BER (bit error rate) before and after the test was evaluated). The results are shown in Table 2.

[0023]

[Table 2]

[0024]

According to the present invention, since it has the above-mentioned structure, the following effects can be obtained.

By forming the inorganic antireflection film, the reflectance is increased, the enhancement of the magneto-optical effect is increased, and the Kerr rotation angle is increased. By including one or more transparent conductive films in the inorganic antireflection film and the inorganic antistatic film, an antistatic effect is produced, and it is possible to prevent dust from adhering to the surface of the medium. By forming the inorganic antistatic film on the recording surface, the surface hardness of the recording surface can be increased, and the possibility of damaging the recording layer even when used for overwriting can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration example of an optical information recording medium according to the present invention.

[Explanation of symbols]

 1 Substrate 2 First Protective Film 3 Magnetic Film 4 Second Protective Film 5 Reflective Film 6 Organic Protective Film 7 Inorganic Antistatic Film 8 Inorganic Antireflective Film

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[Procedure amendment]

[Submission date] October 27, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration example of an optical information recording medium according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration example of an antireflection film.

[Explanation of reference numerals] 1 substrate 2 first protective film 3 magnetic film 4 second protective film 5 reflective film 6 organic protective film 7 inorganic antistatic film 8 inorganic antireflective film

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Yujiro Kaneko 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Michiaki Shinozuka 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Masashi Nakazawa 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh company (72) Inventor Toshihiko Yoshio 10-3 Kitamura, Tottori-shi, Tottori Ricoh Micro Electronics Co., Ltd.

Claims (2)

[Claims] 1. An optical information recording medium comprising at least a substrate and a recording layer, for recording and reproducing using laser light,
Optical information recording characterized in that an inorganic antireflection film having an antistatic function including one or more transparent conductive films is provided on the reading side surface, and an inorganic antistatic film is provided on the surface opposite to the reading side. Medium. 2. The transparent conductive film and the inorganic antistatic film are formed of a transparent conductive film containing In ₂ O ₃ , ITO, SnO ₂ , ZnO, CdO or ZnS as a main material. The optical information recording medium according to claim 1.