JPH0734269B2 - Optical recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to 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 are expected to 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 was a double-layered structure with 11 facing each other. Therefore, although it is suitable for personal use, the manufacturing cost is very high. Also, because it is a structure in which two sheets are stuck together, it is twice as thick as a CD, and the reflectance is low,
A conventional CD player could not reproduce the written signal. (Introduction to "Video Disc and DAD", Corona Publishing Co., Ltd.) Problems to be Solved by the Invention That is, all of the conventional methods have to be very expensive for one individual to make their 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 on 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, a recording film 2 is formed on a transparent substrate 1 in which a groove for performing tracking servo is formed in advance so that the groove and the reflection side surface are smooth. One step and a second step (FIG. 3) of writing a signal as a perforation pit train by a laser beam of a specific wavelength condensed while applying tracking servo on this smooth recording surface were recorded. It comprises a third step of forming the reflective layer 3 on the recording film having a pit row.

Now, of these, the transparent substrate 1 with a groove used in the first step
Is preferably made of a material that does not have characteristic absorption in the wavelength range of 400 nm or more. Specifically, on a molded substrate using polycarbonate or polymetal resin, or a smooth transparent substrate made of glass or methacrylic resin. A substrate in which a groove is formed using a photocurable resin is used. The optical recording material used is the oscillation wavelength range of the semiconductor laser, that is, 750n.
In the region from m to 850 nm, it must have a spectral absorption property of 10% or more, while it must be a material that can perforate and record by sensing laser light of 750 nm or less. Compositions with thermoplastics are suitable. As a method for forming the recording film on the substrate, a solution in which a recording material is dissolved can be applied by spin coating, dip coating, roller coating, kiss coating, or the like, as well as vapor deposition. Note that a protective film having a thickness of several tens of nanometers (hereinafter, nm) or less may be formed in advance on the surface of the substrate for the purpose of protecting the surface of the substrate from a solvent or temperature rise during vapor deposition. The laser used to record a signal from an external information source may have a wavelength of 750 nm or less, and may have an oscillation wavelength close to the wavelength exhibiting the spectral characteristic absorption of the recording material used, and may be helium-neon. Laser, argon ion laser, krypton ion laser, etc. are good. While applying tracking servo to these lasers by a groove formed on a transparent substrate, a signal is written as a perforation pit string on a smooth recording surface. A reflective layer is formed on the pits thus written, and aluminum (hereinafter referred to as A
The method of vapor deposition of l) is most suitable. In addition, in order to protect the reflective layer, it is possible to add a step of applying a protective film thereon.

Action As described above, in the optical recording medium of the present invention, a signal from an external information source such as a magnetic tape can be directly written as a perforated pit train on the recording film whose surface on the medium is smoothed. Since an expensive stamper required for CD manufacturing is not required for each information source, the cost can be reduced for small-scale applications, and by forming a highly reflective layer after recording, an optical disc with exactly the same structure as a conventional CD Therefore, it has an excellent feature that it can be played on a commercially available CD player, and it is an optimal optical recording medium for personal software and small-scale software production.

Examples An optical recording medium according to an example of the present invention will be described below with reference to the drawings.

(Example 1) 1.2 mm thick tracking groove having a depth of 0.05 μm and a width of 0.8 μm on the surface of the molded substrate 1 made of polycarbonate resin spirally formed at 1.6 μm and pitch Then, sputter 10 nm SiO ₂ and iodize it from above.
A methylene chloride solution of 3,3'-diethyl-2,2'-selenacarbocyanine was spin-coated at 1000 rpm to form a recording film 2 having a thickness of 20 nm. A 633 nm helium neon laser (output, 20 mw) is passed through the transparent substrate 1 while rotating the substrate on which the recording film 2 is formed and applying tracking servo.
Was used to write a rectangular pulse signal with a duty ratio of 50/50 at 50 KHz. From the recording film having the perforated pits 4 written therein, aluminum was vapor-deposited to a thickness of 50 nm to prepare an optical disc. When the produced optical disc shown in FIG. 1 was reproduced by a commercially available compact disc player, a reproduction C / N ratio of 50 dB was obtained at a bandwidth of 30 KHz. That is, the optical disk manufactured by the manufacturing method of Example 1 could be reproduced by a commercially available CD player.

Example 2 On a grooved polymethacrylic resin substrate having the same shape as in Example 1, 1,3′-diethyl-2,2′-quinothiacyanine iodide as a methanol solution was spin-coated to a thickness of 200 nm. Then, an argon ion laser (output, 40 mw) was opened, a rectangular pulse signal with a duty ratio of 50/50 was written at 500 KHz, and aluminum was vapor-deposited to a thickness of 40 nm to prepare an optical disc. The created optical disc can be played using a commercially available CD player, and 49d with a bandwidth of 30KHz.
It was confirmed that the reproduction C / N ratio of B was obtained.

EFFECTS OF THE INVENTION By using the optical recording medium according to the present invention, an optical recording medium having small-scale and multi-product information can be manufactured at low cost, and the manufactured optical recording medium can be reproduced by a conventional CD player. It has excellent characteristics.

[Brief description of drawings]

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

Front Page Continuation (72) Inventor Mitsuaki Oshima 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-62-119748 (JP, A)

Claims (2)

[Claims] 1. A first transparent layer having a groove for tracking servo on its surface in advance and transparent to both light of a first specific wavelength used for recording and light of a second wavelength used for reproduction. On the top, it has a second transparent layer for flattening the groove, the second transparent layer absorbs the first wavelength, is transparent to the second light, the second An optical recording medium in which a signal accompanied by surface deformation is recorded on a second transparent layer, and a reflective layer is provided on the surface having the deformation. 2. Reflection at the interface between the first transparent layer and the second transparent layer for light of the first wavelength, and reflection at the interface for light of the second wavelength is negligible. An optical recording medium according to claim (1), characterized in that: