JPH07192322A - Formation of reutilized optical disk - Google Patents

Abstract

PURPOSE:To reutilize substrate of an optical disk and to form a fresh optical disk excellent in optical characteristic by forming a photopolymerizable high- molecular material having the same refractive index as the substrate to fill the fine ruggednesses left on the surface. CONSTITUTION:The reutilized optical disk substrate 20 without the printing layer, protective film and reflecting film on the surface is constituted. A photopolymerizable high-molecular material layer 12 having the same refractive index as the substrate 20 is adhered or applied to the substrate 20 in the thickness sufficiently larger than the level difference of the fine rugednesses 11 on the substrate 20 surface. A UV curing resin consisting of a modified acrylic resin, for example, is used for the layer 12. The refractive index of the resin is nearly equal to that of the substrate 20. An optical information detecting ruggedness 21 based on the fresh recorded information is formed on the layer 12 by the pressing of a stamper before the layer 12 is cured. The layer 12 is then irradiated with UV and cured, and a optical disk substrate 22 with the fresh detecting ruggedness 21 formed on the substrate 20 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc having a substrate on which irregularities for detecting optical information such as non-defective products, defective products and semi-finished products are formed, for example, CD (compact disc), magneto-optical disc, phase change optical disc, etc. The present invention relates to a method for producing a reusable optical disc, in which the substrate is reused to newly produce these optical discs of various reflective or transmissive optical discs.

[0002]

2. Description of the Related Art Optical discs such as CDs, video discs, digital audio discs and optical recording discs are
As shown in FIG. 10, a reflective film 3, such as aluminum (Al), a protective film 4, a printed layer (not shown) is formed on a substrate 2 on which phase pits are formed by the optical information detecting unevenness 1.
Etc. are formed.

An optical disc using a so-called 2P (Photo Polymer: photopolymerizable polymer material) glass substrate 2 is formed by photopolymerization for forming optical information detecting irregularities 1 on a glass substrate 42, as shown in FIG. It is configured to have a functional polymer material layer 43, on which the above-described reflective film 3, protective film 4, printing layer (not shown), etc. are formed.

Further, for example, in the case of reading phase pits, that is, recorded information by phase change, the substrate 2
A phase change material layer or the like is formed on top.

When manufacturing such an optical disk, for example, in the manufacturing process thereof, for example, when the above-mentioned optical information detecting unevenness 1 is formed on the substrate 2, or when each film or layer formed on the substrate 2 is formed. In some cases, some inconvenience occurred, after commercialization, or in the semi-manufactured state,
When there are good and defective products, they may be discarded.

However, simply discarding the optical disc in this way is not desirable in terms of waste of resources, increase of waste, and the like.

Therefore, it is desired to reuse the substrate of this discarded optical disc, but when a new optical disc is manufactured using this substrate, it is difficult to obtain an optical disc having excellent optical characteristics. This is because fine irregularities due to the optical information detecting irregularities already formed on the surface of the substrate 2 or polishing the surface thereof, for example, a reflection film, a protective film, a printing layer formed on the substrate 2 or the like. This is due to the fact that fine irregularities due to scratches and the like that have occurred when removing the are left.

Therefore, generally, the substrate of this waste disk, for example, the plastic substrate is crushed and diverted to various molded products which are not required to have high optical characteristics.

However, this discarded disk substrate is
If it can be reused as a substrate of an optical disc, it will bring great benefits such as reduction of the cost of the optical disc and reduction of large energy for crushing.

[0010]

According to the present invention, as described above, the optical disk substrate can be reused to reliably form an optical disk having a new optical information detecting concave and convex with excellent optical characteristics. A method for manufacturing a reusable optical disc is provided.

[0011]

The first aspect of the present invention, as shown in FIG. 1, has a surface of a reusable optical disc substrate 20 having optical information detecting irregularities, fine irregularities 11 due to polishing scratches, and the like. The photopolymerizable polymer material layer 12 having the same refractive index as that of the substrate 20 is adhered or applied sufficiently thicker than the height difference of the fine irregularities 11 on the substrate surface.

Then, new optical information detecting concavities and convexities 21 are formed on the photopolymerizable polymer material layer 12, and then the photopolymerizable polymer material layer 12 is cured by irradiation with light to obtain the target optical disk 25. To get

A second aspect of the present invention is the above-mentioned method of the first aspect of the present invention, in which the substrate 20 for reused optical disk is a substrate obtained by mechanically or chemically peeling each layer formed on the substrate 20. To use.

[0014]

As described above, according to the present invention, although a new optical disk 25 is manufactured by using the reused substrate 20, the unevenness 11 for optical information detection and the fine unevenness 11 such as scratches remaining on the surface of the optical disk 25 are produced. A photopolymerizable polymer material layer 12 having a refractive index equal to that of the substrate 20 is formed so as to be thicker than the height difference, that is, to fill the fine unevenness 11, and new unevenness 21 for optical information detection is formed on the material layer 12. Substrate 2
The optical effect of the fine unevenness 11 remaining on the surface of 0 can be almost ignored, and the optical disk 25 having excellent characteristics can be manufactured.

[0015]

EXAMPLES Examples of the method of the present invention will be described in detail. Figure 1
Optical disc indicated by 0, that is, concave and convex for optical information detection 1
An optical disc in which a reflective film 3 made of, for example, Al, a protective film 4 made of an ultraviolet curable resin, a printed layer, etc. are formed on a transparent substrate 2 made of, for example, polycarbonate (PC) on which phase pits are formed by A case will be described in which the substrate 2 is reused to obtain an optical disk having a similar configuration having new concaves and convexes for detecting optical information.

In this case, as shown in FIG. 2, a printed layer (not shown) on the substrate 2 in FIG. 10, a protective film 4, and a reflective film 3 are provided.
Are peeled off or removed to form the reused optical disk substrate 20. This peeling is performed by mechanical removal with a brush, chemical etching with a chemical, or the like. In this way, the reusable optical disc substrate 20 from which each film or layer has been eliminated is, for example, a part of the fine irregularities due to the previously formed irregularities 1 for optical information detection, or mechanical exclusion or chemical. There are fine irregularities 11 such as scratches caused by etching.

The fine unevenness 11 is actually the RM.
S (root mean square) is 0.2 μm or less, and in the production method of the present invention, this RMS is 0.
It is desired to keep it to 2 μm or less.

Next, as shown in FIG. 3, the photopolymerizable polymer material layer 12 having the same refractive index as that of the reuse optical disc substrate 20 is provided on the reuse optical disc substrate 20. Adhesion or application is performed to a thickness that is sufficiently thicker than the height difference of the fine irregularities 11 on the surface of 20, for example, 10 to several μm to several 10 μm.

For the photopolymerizable polymer material layer 12, for example, an ultraviolet curable resin made of a modified acrylic resin (for example, a mixture of urethane acrylate and acrylic ester monomer) is used. The modified acrylic resin has a refractive index of about 1.6, which is almost equal to the refractive index of PC of the reused optical disk substrate 20 of 1.6.

As another example of the photopolymerizable polymer material layer 12, a liquid material having a high viscosity is used because of the ease of the step of coating the reusable optical disc substrate 20, or, for example, a sheet-shaped polymerizable polymer material ( Proceedings of EOS / SPIE Intern
ational Conference- "Hologrtaphics International 9
2 "26-29 July 1992)).

When the photopolymerizable polymer material layer 12 is in the form of a sheet, it is placed on the substrate 20 for reused optical disc, and the reused optical disc is formed by a pressing body having smoothness from the back surface thereof. The surface is flattened by pressing it toward the substrate 20 side. Photopolymerizable polymer material layer 1
In the case where 2 is formed by applying a liquid material having a high viscosity, the surface of the reused optical disk substrate 20 is flattened by rolling and pressing a roller held at a predetermined distance to the reused optical disk substrate 20. To convert.

Then, while the photopolymerizable polymer material layer 12 is in an uncured state, as shown in FIG. 4, optical information detection based on new recorded information is performed on the photopolymerizable polymer material layer 12. The unevenness 21 for use is formed by pressing a stamper (not shown).

Thereafter, the photopolymerizable polymer material layer 12 is cured by, for example, irradiation with ultraviolet rays, and as shown in FIG.
An optical disk substrate 22 having new optical information detecting concavities and convexities 21 formed on the reused optical disk substrate 20 is obtained.

On the optical disk substrate 22 thus formed, for example, an Al reflective film 23 and a protective film 23 are sequentially deposited, and a new optical disk 25 shown in FIG. 1, a reflective optical disk such as a CD is used in this example. Create.

A new optical disk using the optical disk substrate 22 using the recycled optical disk substrate 20 thus formed is in a state before the photopolymerizable polymer material layer 12 is deposited on the recycled optical disk substrate 20. When the surface roughness of the fine concavo-convex pattern 11 in RMS was 0.2 or less, the characteristics were comparable to those of an optical disk using a completely new substrate that does not depend on reuse, that is, a CD.

Next, an example in which the present invention is applied to a CD using a 2P glass substrate will be described. In this case, the disc to be reclaimed has the structure described in FIG.
A photopolymerizable polymer material (2P) having a thickness of several μm for forming the optical information detecting unevenness 1 on the disc-shaped glass substrate 42 of mm.
An optical disk was formed in which 43 was formed, on which an Al reflection film 3 having a thickness of about 0.1 μm, a protective film 4 made of an ultraviolet curable resin having a thickness of several μm, a printing layer, and the like were formed.

The hardness of the 2P optical disk is lower than that of the glass substrate 42, and is higher than that of the photopolymerizable polymer material layer 42, the reflection film 3, the protective film 4, the printing layer and the like on the glass substrate 42. Plastic particles having a high hardness, for example, a Moss hardness of about 4 were blasted for about 2 minutes by a blasting device that blows with compressed air. By doing so, the material on the substrate 42, that is, the photopolymerizable polymer material layer 42, the reflective film 3, the protective film 4, the printed layer, and the like appeared to be all removed by visual observation.

Then, using this substrate 42 as the substrate 20 for the reusable optical disc, the photopolymerizable polymer material layer 12 and the optical information detecting irregularities 21 are formed by the same method as described with reference to FIGS. Then, a new optical disc, for example, a CD was manufactured (hereinafter referred to as sample 1). In this way, the CD of the sample 1 by recycling the 2P glass substrate
For a so-called new CD that does not rely on recycling,
Using the D regenerator, when observing the eye pattern by the high frequency signal reproduced under the condition that the reproduction wavelength is 780 nm and the numerical aperture (NA) of the optical lens is 0.45, there is no difference between them. I couldn't do it.

In the sample 1 according to the method of the present invention, the reusable optical disk substrate 20 was prepared by removing the layers other than the glass substrate 42 by blasting abrasive particles with plastic particles having a hardness lower than that of the glass substrate 42 to be reused. However, when the layers other than the substrate 42 are removed using the abrasive grains having a hardness higher than that of the substrate 42 to be reused to form the substrate 20 for the reused optical disk, the surface of the substrate 42 is relatively rough and roughened. May occur. Therefore, in the case of this method, the photopolymerizable polymer material layer 43 on the substrate 42 is not removed over the entire thickness, and after this removal step, a strong alkaline liquid treatment by heating for a long time is performed to remain. The method of removing the material layer on the substrate 42 will be adopted. However, in this case, not only the problem of processing the waste liquid and the problem of workability but also the deterioration of the optical characteristics of the surface of the glass substrate 42 becomes a problem.

Now, it is formed by reusing the sample 1 described above and the glass substrate 42 having the same structure as the sample 1 but subjected to the blasting and the strong alkaline heating treatment with the abrasive grains having high hardness as described above. 6 and 7 show the results of measurement of the number of block errors for the prepared CD (hereinafter referred to as Sample 2). In both figures, the horizontal axis shows each time of the block error measurement, and the vertical axis shows the number of block errors in 10 seconds. In both figures, the average value for the so-called bottom error excluding the so-called burst error in which the number of block errors is outstanding is
It was 20.1 for sample 1 according to FIG. 6 and 24.7 for sample 2 according to FIG. By the way, in FIG. 6 of the measurement result of the sample 1, so-called burst errors are often generated, but this can be eliminated by processing in a circuit manner.

As is clear from the comparison between Sample 1 and Sample 2, as described above, in the case of using the reused optical disk substrate 20, in the case of using abrasive grains for mechanical exclusion by blasting or brushing for eliminating each layer on the substrate. It was found that it is desirable to avoid heated alkali treatment by using abrasive grains having a hardness lower than that of the substrate to be reused and a hardness higher than that of the layer to be eliminated. .

In the optical disk of Sample 1 described above, all layers on the glass substrate 42 of FIG. 11 to be reused are visually observed to be excluded, and the reused optical disk substrate 20 is removed. In this case, for example, the printing layer, the protective film 4, the reflective film 3, and the photopolymerizable polymer material layer 43 are removed by mechanical etching and chemical etching, but the photopolymerizable polymer material layer 42 is removed. The substrate for the reused optical disk 20 may be a substrate in which the fine irregularities 11 due to etching remain on a part of the substrate 42 side without being completely removed.

As described above, even when the reused optical disk substrate 20 in which the polymer material layer 43 remains is used,
A new optical disc such as a CD (hereinafter referred to as Sample 3) using a glass substrate on which the photopolymerizable polymer material layer 12 was formed was manufactured by the same method as described with reference to FIGS.

FIGS. 6 and 7 show a sample 3 using the above-mentioned reuse substrate according to the present invention and a so-called new CD produced by the same 2P method, using a CD regenerator at a reproduction wavelength of 780 nm, N. A. Shows an eye pattern by a high frequency signal reproduced under the condition of 0.45. As is clear by comparing these, almost no difference was observed in the eye pattern between the optical disk of Sample 3 using the reuse substrate according to the present invention and the optical disk produced using the new substrate not using the reuse.

In each of the above-mentioned examples, the present invention is applied to a CD, but it is applicable to various other optical discs such as a magneto-optical disc, an optical disc having a phase change layer, and a transmissive optical disc without being limited to a reflective optical disc. Can also be applied to.

[0036]

As described above, according to the present invention, an optical disk which is no different from the case where a completely new substrate is used despite the reuse of the substrate 2 on which the optical information detecting unevenness 1 is once formed. Since it can be configured, it is possible to reduce the cost, and it is possible to save resources by avoiding the disposal of the substrate, reduce the amount of waste, save energy by avoiding crushing for other uses, etc. It can be measured and brings great benefits in practical use.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of an optical disc manufactured by the method of the present invention.

FIG. 2 is a process chart of an example of a method for producing a reusable optical disc according to the present invention.

FIG. 3 is a process chart of an example of a method for producing a reusable optical disc according to the present invention.

FIG. 4 is a process chart of an example of a method for producing a reusable optical disc according to the present invention.

FIG. 5 is a process chart of an example of a method for producing a reusable optical disc according to the present invention.

FIG. 6 is a diagram showing a measurement result of the number of block errors of a reused optical disc.

FIG. 7 is a diagram showing a measurement result of the number of block errors of a reused optical disc.

FIG. 8 is an eye pattern showing reproduction characteristics of a reused optical disc manufactured by the method of the present invention.

FIG. 9 is an eye pattern showing reproduction characteristics of an optical disc that does not depend on reuse.

FIG. 10 is a schematic cross-sectional view of an example of an optical disc to be reused.

FIG. 11 is a schematic cross-sectional view of an example of an optical disc to be reused.

[Explanation of symbols]

 1, 21 Optical Information Detecting Concavo-convex 2, 22 Substrate 20 Reusable Optical Disc Substrate 3, 23 Reflective Film 4, 24 Protective Film 25 Optical Disc

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Mishima 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (2)

[Claims] 1. A photopolymerizable polymer material layer having a refractive index equal to that of the substrate is provided on the surface of a substrate for a reusable optical disc having irregularities for optical information detection and fine irregularities due to polishing scratches, etc. Adhesion or application is made sufficiently thicker than the height difference of the fine irregularities of, to form new optical information detecting irregularities on the photopolymerizable polymer material layer, and then the photopolymerizable polymer material layer is cured by light irradiation. A method for producing a reusable optical disc, which is characterized by obtaining an intended optical disc. 2. The reusable optical disc according to claim 1, wherein the substrate for the reusable optical disc is a substrate obtained by mechanically or chemically peeling off each layer formed on the substrate. Method.