JPS62119748A - Optical recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to writable optical recording media.

2. Description of the Related Art Optical recording media, especially optical disks, have been making remarkable progress in recent years, and as the market expands, it is expected that they will be used for a wide variety of purposes and applications. Optical discs can be broadly divided into two types. In other words, there are read-only discs and writable discs, and the former uses a stamper on which information is recorded in advance.
Transparent substrate 6 onto which the information on the stamper was transferred by molding
(Figure 4) By vapor-depositing aluminum on the top, tens of thousands of discs with the same information can be manufactured, and like compact discs for music (hereinafter referred to as CDs), manufacturers mass-produce discs. Therefore, even if an expensive stamper is used, it can be produced at a relatively low cost.

However, this method cannot be applied to small-scale production, especially to personal information files, personal music discs, etc., in terms of cost performance. In addition, a writable optical disk that has been in the spotlight recently has an optical recording film 9 formed on a transparent substrate 8 on which a groove 12 for tracking has been formed in advance, as shown in FIG. It had a two-layer structure with 1) facing each other.

For this reason, although it is suitable for personal use, it is extremely expensive to manufacture. In addition, since it has a structure of two sheets pasted together, it is more than twice as thick as a CD, and has low reflectance, making it impossible for conventional CD players to play back the written signals (see "Video Introduction to "Disks and DAD".

Corona Inc.).

Problems that the invention aims to solve: In other words, all conventional methods are extremely expensive for individuals to create their own music software; The user had to purchase a device that could play the optical discs, which effectively became a major hindrance to 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, has a thin overall thickness of the written optical disc, and has a high reflectance on the recording surface, so that it can be played on a commercially available CD player. It made it possible to do so.

That is, in the present invention, as shown in FIG. 2, a bleachable recording film 2 is formed on a transparent substrate 1 in which grooves for performing tracking servo are formed in advance so that the surface opposite to the grooves is smooth. The first step is to form a pit array on this smooth recording surface, the second step is to write a signal as a pit row on this smooth recording surface using a focused laser beam while applying tracking servo (Fig. 3), and the remaining recording film 2. The optical recording medium is manufactured by four steps: a third step of discoloring without deforming the optical recording medium, and a fourth step of forming a reflective layer 3 on the recording film having recorded pit rows. . Note that the third and fourth steps may be performed before or after any of them.

Now, among these, the grooved transparent substrate l used in the first step is preferably made of a material that does not have characteristic absorption in the wavelength range of the semiconductor laser, and specifically, polycarbonate, polymethacrylic resin, etc. are 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 spectral absorption characteristics in the wavelength range of a semiconductor laser, and by forming a perforation pit row with a focused semiconductor laser and irradiating it with a specific light,
It is necessary to use a material in which the unrecorded areas are bleached and the above spectral characteristic absorption disappears, and organic dyes or dyes dispersed in transparent resins, especially cyanine dyes, are suitable.

The most suitable method for applying the recording film onto the substrate is the spin coating method, but it can also be formed by methods such as dipping, roll coating, and kiss coating. In order to improve the solvent resistance of the surface of the grooved substrate, it is also possible to form a protective film on the surface so thin that the shape of the grooves does not change before applying the recording film. The third method of bleaching the recording film is to irradiate it with light to oxidize and decompose the functional groups of the dye molecules that form the recording film, and this method changes the shape of the recorded pits. Can be bleached without bleaching. In addition to photobleaching, chemical bleaching and thermal bleaching are also possible. As the fourth method for forming a reflective layer, high reflectance can be easily obtained by vapor depositing aluminum. In addition, in order to protect the reflective layer, a fifth step of applying a protective film over the reflective layer may be added after the reflective layer is formed.

As described above, the optical recording medium of the present invention allows signals from an external information source, such as a magnetic tape, to be directly written as perforated focus rows on a recording film with a smooth surface on the medium. Because the expensive scrubber required for the production of CDs is not required for each information source, costs can be reduced for small-scale applications.Furthermore, by forming a highly reflective layer after bleaching, it is possible to create an optical disc with the same structure as a conventional CD. It has the excellent feature of being able to be played back on a commercially available CD player, making it an optimal optical recording medium for personal software and small-scale software production.

EXAMPLE Hereinafter, an optical recording medium according to an example of the present invention will be described with reference to the drawings.

(Example 1) Thickness: 1.2m, depth: 0.08μm, width: 0.8μ
A protective film of SiO2 of lQnm is spattered onto the grooved surface of the methacrylic resin molded substrate 1, on which tracking grooves of m are spirally formed at a pitch of 1.6μm, and an iodized film is applied over this. -1,1"-diethyl-2,
A methylene chloride solution of 2'-quinotricarbocyanine was spin-coded at 50 Orpm to form a record WA2 with a thickness of 20 nm. The substrate with the recording film is rotated and the tracking servo is applied while passing through the transparent substrate for 4 m.
Semiconductor laser light with a wavelength of 830 nm is transmitted at 1.4 m/s using W.
Irradiation was performed at a linear velocity of ec. Written signal 4 is 500K
)Iz with a duty ratio of 50150. After recording, 50 nm of aluminum 3 was deposited on the surface, and 3000 mJ/aJ of ultraviolet rays were irradiated through the base substrate to bleach the unrecorded areas. When the completed optical disc shown in Figure 1 was played using a commercially available CD player,
A reproduction C/N ratio of 55 dB is obtained with a bandwidth of 30 KHz,
It was demonstrated that playback using a commercially available CD player was possible.

(Example 2) On the same grooved substrate as in Example 1, lQnm
After forming the S i 02 layer, the following dye was applied by a 200 nm spin code method, and the same signal was recorded under the same conditions as in Example 1.

After recording, the entire surface was irradiated with ultraviolet rays of 3000 mJ/-, and after bleaching, 50 nm of aluminum was deposited on the surface to form a reflective layer. When this was played back with a commercially available CD player, a playback C/N ratio of 53d13 was obtained with a bandwidth of 30 KHz, demonstrating that playback with a commercially available player is possible.

Effects of the Invention By using the optical recording medium according to the present invention, it is possible to manufacture small-scale optical recording media having a wide variety of information at low cost, and the manufactured optical recording medium has the advantage that it can be played by a conventional CD player. It has the following characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating the optical disc of the present invention, FIGS. 2 and 3 are 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. FIG. 1 is a cross-sectional view of a writable optical disc having an air sand inch structure. 1...Transparent substrate, 2...Recording film, 3.
Old: reflective layer, 4: written pit. Name of agent: Patent attorney Toshio Nakao Haka1 person! −″゛jishidanha4【ne length

Claims (4)

[Claims] (1) A second transparent layer is provided on the first transparent layer that is transparent to light of a specific wavelength, and a signal is recorded as a surface deformation on the second transparent layer, and a signal is recorded on the surface having the deformation. An optical recording medium provided with a reflective layer. (2) Claim (1) characterized in that the second transparent layer is a recording film capable of perforation recording in response to light of a specific wavelength, and can be made transparent to the specific wavelength by a drifting treatment after recording. The optical recording medium described. (3) The second transparent layer has a reflectance at the interface with the first transparent layer in an unbleached state.
1) The optical recording medium described in item 1). (4) The first transparent layer has a groove for tracking servo on its surface, a second transparent layer is formed on the surface, and the surface of the second transparent layer is flat. An optical recording medium according to claim (1).