JPH0638301B2 - Optical recording medium manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a writable optical recording medium.

2. Description of the Related Art Optical recording media, especially optical discs, have made remarkable progress in recent years, and it is expected that they will be used for various purposes and applications as the market expands. Optical discs are roughly classified into two types. That is, a read-only disc and a writable disc,
The former uses a stamper on which information is recorded in advance and deposits aluminum on a transparent substrate 6 (FIG. 4) onto which information on the stamper has been transferred by molding to manufacture tens of thousands or more disks of the same information. Since a manufacturer mass-produces a compact disc for music (hereinafter referred to as a CD), it can be produced at a relatively low cost even if an expensive stamper is used.

However, this method cannot be applied to small-scale production, especially to personal information files and personal music discs in terms of cost performance. Further, in a writable optical disk which has recently been in the spotlight, an optical recording film 9 is formed on a transparent substrate 8 on which a groove 12 for tracking is previously formed as shown in FIG. It had a two-layered structure with 11 facing each other.
Therefore, although it is suitable for personal use, the manufacturing cost is very high. Further, since the structure is a structure in which two sheets are stuck together, the thickness is more than twice that of a CD, the reflectance is low, and the written signal cannot be reproduced by the conventional CD player. (Introduction to "Video Disc and DAD", Corona Publishing Co., Ltd.) Problems to be Solved by the Invention That is, each of the conventional methods must be very expensive for an individual to make his / her own music software. In addition, it is necessary to purchase a device that can be newly reproduced for reproduction, which is a major obstacle to substantially suppressing the expansion of the optical disc market.

Means for Solving the Problems The present invention provides a writable optical disc at a low cost, and the overall thickness of the written optical disc is thin so that it can be reproduced by a commercially available CD player by increasing the reflectance of the recording surface. It is possible to do.

That is, according to the present invention, as shown in FIG. 2, the fading recording film 2 is formed on the transparent substrate 1 on which a groove for performing tracking servo is formed in advance so that the groove and the surface on the reflection side are smooth. The first step of forming the pits, the second step (FIG. 3) of writing a signal as a pit train by the focused laser light while applying the tracking servo on the smooth recording surface, and the remaining recording film. It is established by four steps of manufacturing an optical recording medium by a third step of bleaching 2 without being deformed and a fourth step of forming a reflective layer 3 on a recording film having recorded pit rows. There is. However, any of the above-mentioned third and fourth steps may be performed before or after. The grooved transparent substrate 1 used in the first step is preferably made of a material having no characteristic absorption in the wavelength range of the semiconductor laser. Specifically, polycarbonate or polymethacryl resin is used. A molded substrate or a substrate in which grooves are formed using a photocurable resin on a smooth transparent substrate made of glass or methacrylic resin is used. The optical recording film used has a spectral absorption characteristic in the wavelength range of the semiconductor laser, and a perforated pit row is formed by the focused semiconductor laser, and the unrecorded part is discolored by irradiating with specific light. It is necessary to use a material in which absorption of the above spectral characteristics disappears, and an organic dye or a dye in which a dye is dispersed in a transparent resin, and a cyanine dye is particularly suitable. The spin coating method is the most suitable method for coating the recording film on the substrate, but it can also be prepared by a method such as dipping, roll coating, or kiss coating. In order to improve the solvent resistance of the surface of the grooved substrate, it is possible to form a thin protective film on the surface of the grooved substrate before coating the recording film to such an extent that the groove shape does not change.
As a third step of fading the recording film, a method of irradiating ultraviolet rays to oxidatively decompose functional groups of dye molecules forming the recording film is excellent, and by this method, the shape of recorded pits is changed. Can be faded without Of course, in addition to light bleaching, chemical bleaching and heat bleaching can be performed. As the fourth reflective layer forming method, high reflectance can be easily obtained by vapor deposition of aluminum. In addition, after forming the reflective layer for protecting the reflective layer, a fifth step of applying a protective film from above may be added.

Action As described above, the method of manufacturing the optical recording medium of the present invention is designed to directly input a signal from an external information source such as a magnetic tape,
Since it is possible to write as a perforation table pit string on a recording film whose surface on the medium is smoothed, an expensive stamper required for CD manufacturing is not required for each information source, so cost can be reduced in a small-scale application, Moreover, by forming a highly reflective layer after fading, it is possible to obtain an optical disc having exactly the same structure as a conventional CD, so that it has an excellent feature that it can be reproduced by a commercially available CD player. It is the most suitable optical recording medium manufacturing method for personal software and small-scale software production.

Example (Example 1) The thickness is 1.2 mm, the depth is 0.08 μm, and the width is 0.8 μ.
A 10 nm SiO ₂ protective film is sputtered on the grooved surface of the methacrylic resin molded substrate 1 in which tracking grooves of m are formed in a spiral shape at a pitch of 1.6 μm. 1,1'-diethyl-2,
A solution of 2'-quinotricarbocyanine in methylene chloride was added to 5
Recording film 2 with a thickness of 20 nm by spin coating at 00 rpm
Was formed. While rotating the substrate having the recording film and applying the tracking servo, the semiconductor laser beam having a wavelength of 830 nm at 4 mW was irradiated through the transparent substrate at a linear velocity of 1.4 m / sec. The written signal 4 is a pulse with a duty ratio of 50/50 at 500 KHz. After recording, 50 nm of aluminum 3 was vapor-deposited on the surface, and 3000 mJ / cm ² of ultraviolet ray was irradiated through the base substrate to discolor the unrecorded area. When the completed optical disc is played back using a commercially available CD player, the bandwidth is 30 dB and 55 dB.
The reproduction C / N ratio was obtained, and it was proved that reproduction by a commercially available CD player was possible.

(Example 2) On the same grooved substrate as in Example 1, 10 nm was also formed.
After the formation of the SiO ₂ layer, the following dyes were applied by the 200 nm spin coating method to form Example 1. The same signal was recorded under the same conditions. 300 after recording
Irradiate with 0 mJ / cm ² of ultraviolet light, and after fading, 50
nm of aluminum was vapor-deposited to form a reflective layer. When this was played on a commercially available CD player, the bandwidth was 30K.
A reproduction CD / N ratio of 53 dB was obtained at Hz, demonstrating that reproduction by a commercial player is possible.

Effects of the Invention By using the method for producing an optical recording medium according to the present invention,
An optical recording medium having small-scale, multi-product information can be manufactured at low cost, and the manufactured optical recording medium can be reproduced by a conventional CD player.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an optical disc manufactured by the manufacturing method of the present invention, FIGS. 2 and 3 are perspective views showing a state of a medium in the manufacturing process, and FIG. 4 is a commercially available compact. FIG. 5 is a sectional view of a writable optical disk having an air sandwich structure. 1 ... Transparent substrate, 2 ... Recording film, 3 ... Reflective layer, 4 ...
The written pit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuaki Oshima 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-57-212628 (JP, A)

Claims (5)

[Claims] 1. A step of forming a recording film capable of perforating recording on a transparent substrate in response to light, a step of writing a signal from an external information source as a deformation on the recording film by light, and the entire recording film. And a step of forming a reflective layer on the recording film on which a signal is recorded as a surface deformation, and a method of manufacturing an optical recording medium. 2. A transparent substrate having grooves for tracking servo formed on its surface in advance is used, and a recording film exhibiting a fading property by light on the surface having the grooves is smoothed on the surface opposite to the grooved side. 2. The method for manufacturing an optical recording medium according to claim 1, further comprising a second step of writing the pit row on a smooth surface while applying the tracking servo using the groove. 3. The method for producing an optical recording medium according to claim 1, wherein a dye having characteristic absorption in a wavelength range of 700 to 900 nm is used among organic dyes which are faded by ultraviolet rays as the fading recording film. . 4. The method for producing an optical recording medium according to claim 1, wherein a light ray containing an ultraviolet region is used for fading the recording layer. 5. The method for producing an optical recording medium according to claim 1, wherein the fourth step is vapor deposition of aluminum for forming the reflective layer.