JPH07105073B2 - Read-only optical disc - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical disc for reading information using a laser, and more particularly to a read-only optical disc excellent in reliability and weather resistance.

(Prior Art) A compact disc (hereinafter referred to as a CD) is widely known as a read-only optical disc. The CD has a structure in which a reflection film made of aluminum and a protective film made of a UV curable resin are provided on a polycarbonate substrate (hereinafter, referred to as a PC substrate), and minute unevenness (hereinafter, referred to as a fine irregularity) formed on the PC substrate in advance. , Pits) is used to enable sound reproduction.

In recent years, the CD-ROM has been used not only for the audio reproduction described above.
Read-only optical disks for various types of data called "data" are also being used in various fields. For example, it is being applied to data media for personal computers and electronic publishing media.

(Problems to be solved by the invention) Although a CD-ROM can be easily manufactured using a conventional CD manufacturing technique using a PC substrate, it is strongly required to have reliability of reading and data storability (weather resistance of CD-ROM). If so, it will be a problem with the PC board. That is, due to the water absorption and moisture permeability of the PC substrate, warpage or deterioration of the reflective film such as corrosion and peeling is likely to occur. Further, even in the case of a CD, when considering, for example, mounting on a vehicle, the environmental conditions are severe, and higher quality is required.

An object of the present invention is to provide a read-only optical disc having high reliability and high weather resistance.

(Means for Solving the Problems) The present invention will be described below with reference to FIG. FIG. 1 is a schematic sectional view of the present invention.

The present invention uses a glass substrate 1 having no hygroscopicity or moisture permeability,
On the glass substrate 1, a so-called sol-gel method is used to form a baked layer 2 of metal alcoholate having a glassy pit pattern obtained by baking an organometallic compound, and then a reflection having high corrosion resistance is formed. By stacking the film 3 and the protective film 4 in sequence, a highly reliable read-only optical disc can be obtained.

Usual soda lime glass, aluminosilicate glass, or the like is used as the glass substrate 1, but from the viewpoint of reliability as an optical disc, a chemically strengthened one is preferable.

To form the desired pit pattern on the glass substrate,
It can be easily carried out using the sol-gel method as shown below.

First, a coating solution containing a metal alcoholate, water, hydrochloric acid, alcohol, etc. is prepared and spin-coated on a glass substrate so as to have a predetermined thickness. Then, press a resin mold designed to have the desired pit pattern,
Primary firing is performed at a temperature of about 60 to 120 ° C. After that, the glass substrate is released from the mold, the secondary baking is performed at 250 to 400 ° C., the solvent,
By removing organic components such as additives, the amorphous metal oxide layer 2 having a desired pit pattern can be formed.

As the metal alcoholate used here, various metal alcoholates, for example, alcoholates such as Si, Ti, Zr, Al, and B can be used. System alcoholate or
A mixed system of Si-based alcoholate and Ti-based alcoholate is preferable.

In this way, a transparent glass substrate having a desired pit pattern can be obtained.

Next, on the fired layer having the obtained pit pattern,
The reflective film 3 is attached by a sputtering method or the like, and the protective film 4 is further added.
A read-only optical disc is obtained by coating the above with.

As the material of the reflective film 3, various metals, metal nitrides, etc. can be used, but those satisfying the characteristics as an optical disk and exhibiting high corrosion resistance are preferable, and Au, Au-based alloy and TiN are the present invention. To achieve the purpose of.

As the protective film 4, an inorganic oxide such as SiO ₂ or an inorganic oxide such as Si ₃ N ₄ or an organic such as a UV curing resin can be used alone or in combination.

(Operation) Since the read-only optical disc according to the present invention has the glass substrate and the reflective film having excellent moisture resistance, high reliability can be realized.

(Example) Hereinafter, it demonstrates in detail based on an Example.

Example 1 A chemically strengthened glass substrate was spin-coated with an ethyl alcohol solution containing tetraethoxysilane, hydrochloric acid, water, and polyethylene glycol, and an organometallic compound was added to 2000.
~ 3000Å formed. Then, a resin mold having a predetermined pit pattern on the surface is pressed against the organometallic compound layer,
The pit pattern was transferred and primary firing was performed at 120 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

On the fired layer having a pit pattern produced in this manner, an Au-Ta alloy film was formed as a reflective film by a sputtering method in an amount of about 10
00Å and 1000Å SiO ₂ film was sequentially formed as a protective film.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which was an initial value of 2.0 × 10 ⁻³ , slightly increased to 2.2 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 2 On a chemically strengthened glass substrate, an ethyl alkote solution containing tetraethoxysilane, tetrabutoxytitanium, hydrochloric acid, water, and polyethylene glycol was spin-coated to form an organometallic compound layer at 2000 to 3000 liters. Then, a resin mold having a predetermined pit pattern on the surface was pressed against the organometallic compound layer to transfer the pit pattern and perform primary baking at 100 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

On the fired layer of metal alcoholate having a pit pattern thus produced, an Au-Ge alloy film of about 1000Å and a SiO ₂ film as a protective film of 1000Å were sequentially formed by a sputtering method.
Furthermore, it was covered with a UV curable resin layer.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 1.5 × 10 ⁻³ , slightly increased to 2.1 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 3 A TiN film of about 1000 Å by a cluster ion beam method and a Si ₃ N ₄ film of 800 by a sputtering method were formed on a baked layer of a metal alcoholate having a pit pattern prepared in the same manner as in Example 2.
~ 1000Å The film was formed sequentially. Furthermore, it was covered with a UV curable resin layer.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 1.8 × 10 ⁻³ , slightly increased to 2.5 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Comparative Example When the weather resistance of a commercially available music CD disk was evaluated in the same manner, the block error rate was 5 ×.
It changed significantly from 10 ^-4 (initial value), and it became impossible to measure after 500 hours. Also, after leaving it under conditions of 80 C and 90% RH for about 1 hour, it was taken out and regenerated, and it was impossible to regenerate because of a large warp.

(Effects of the Invention) As described above, the read-only application disk according to the present invention is excellent in reliability and weather resistance, and can be applied to the application fields which cannot be used conventionally.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a read-only optical disc according to the present invention. 1 ... Glass substrate, 2 ... Firing layer of metal alcoholate,
3 ... Reflective film, 4 ... Protective film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikiko Saito 5-33-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Yoshihiro Matsuno 3-5, Doshomachi, Chuo-ku, Osaka-shi, Osaka No. 11 within Nippon Sheet Glass Co., Ltd. (72) Inventor Toshio Kaku 3-5-11 Doshumachi, Chuo-ku, Osaka-shi, Osaka Prefecture Within Japan Sheet Glass Co., Ltd. (72) Shinya Katayama 3 Doshu-cho, Chuo-ku, Osaka City, Osaka Prefecture 5-11, Nippon Sheet Glass Co., Ltd. (72) Inventor, Atsunori Matsuda, 3-5-11, Doshomachi, Chuo-ku, Osaka City, Osaka Prefecture (56) Reference, Japanese Sheet Glass Co., Ltd. (JP) 3-30133 (JP) , A) JP 3-40243 (JP, A) JP 3-40244 (JP, A) JP 64-14082 (JP, A)

Claims (1)

[Claims] 1. A read-only optical disc comprising a transparent glass substrate, a firing layer of metal alcoholate having fine irregularities, a reflective film made of Au alloy or TiN, and a protective film, which are sequentially laminated.