JPH0428034A - Production of optical recording medium disk - Google Patents

Abstract

PURPOSE:To obtain an optical recording disk in a short period of time with simple equipment by forming a specific recording film and an interference film for intensifying a reflected light quantity on the plate surface of a transparent substrate on the side where guide grooves for tracking are provided. CONSTITUTION:The recording film 2 is formed by dissolving a dye material contg. an indolenine cyanine dye in a solvent of an alcohol system and applying the soln. by a spin coating method on the guide groove side surface of the transparent substrate 1 provided with the guide grooves for tracking at a prescribed film thickness. The interference film 3 for intensifying the reflected light quantity is formed by dissolving a material which is transparent to the recording and reproducing light of the medium disk, has the refractive index lower than the refractive index of the dye material contg. the indolenine cyanine dye and is soluble in a prescribed solvent and applying this soln. by a spin coating method on the recording film 2 at a prescribed film thickness. A vacuum atmosphere is, therefore, not needed for forming the recording film 2 and the interference film 3 for intensifying the reflected light quantity. The optical recording medium is obtd. in a short period of time with the simple equipment in this way.

Description

[Detailed description of the invention] [Industrial application field]

TECHNICAL FIELD The present invention relates to a method for manufacturing optical recording medium disks, particularly optical recording medium disks exhibiting high reflectivity.

[Conventional technology]

As the demand for recording various information signals at high recording densities has increased, in recent years there has been an increase in the demand for high-density recording and reproduction of information signals using information recording media created based on various structural and operating principles. 1 For example, recording in which an information signal is recorded by forming irregularities corresponding to the information signal on the signal surface of an information recording medium, and the recorded information signal is reproduced by optical means. Playback devices are already in practical use for recording and playing back video and audio signals. In addition, in order to meet the demands for high-density recording and reproduction in various technical fields, by irradiating the recording layer of the information recording medium with a beam whose intensity is modulated by the information signal, the recording layer of the information recording medium can respond to the information signal. Research has also begun on information recording media in which information signals are recorded by causing physical or chemical changes, but in recent years, it has become easier to obtain semiconductor lasers that operate stably. As a result, various optical recording media (optical disks) that use laser light to perform high-density recording and reproduction have already been put into practical use, or research and development is being carried out to put them into practical use. The current situation is well known. For example, a recorded optical disc (a playback-only optical disc) that has been copied in large quantities from a master disc on which information signals are recorded using pits formed as geometrical concave or convex parts is used as a video disc, for example. and compact
Optical discs that can be added once by the user (write-once optical discs) and erasable optical discs are starting to become popular in ordinary households as discs, etc., and are now being used as file memories for offices and for other purposes. Research and development is actively being carried out for practical application. By the way, when reproducing information signals from an information recording medium on which information signals are recorded at high density, tracking control is used to ensure that the reproducing element or the reproducing beam always accurately follows the recording trace where the information signals are recorded. It is well known that this is done, and even when reproducing information signals recorded at high density on the various types of information recording media mentioned above, the reproduction operation is performed under tracking control operation. Normally, it is allowed to take place. - As an example, let's talk about a compact disc, which is known as an information recording medium in which information signals are recorded at high density by an array of pits corresponding to the information signals on the signal surface of the information recording medium. In compact discs, information signals are recorded on the signal surface by an array of pits with depths set in a specific relationship with respect to the wavelength of light of 780 nm, and the entire surface of the signal surface is made of a material such as aluminum. The structure is covered with a thin film, and the reflectance of the land portion on the signal surface is specified to be 70% to 90% for light with a wavelength of 780 nm. The information signal is read out using a light spot having a wavelength of 780 nm. When reading an information signal from the above-mentioned compact disc, the amount of light reflected from the pit portion on the signal surface is greater than the amount of light reflected from the land portion as a result of light interference occurring at the pit portion. This is done by taking advantage of the fact that the amount of light is reduced compared to the amount of light, and tracking error information is also calculated using the difference between the amount of light reflected from the recorded trace area and the amount of reflected light from the land area. However, with the spread of compact discs, optical discs compatible with compact discs that can be played using a compact disc player include, for example, playback-only optical discs. Various proposals have been made for write-once optical discs with a configuration that has a recorded area and a recording area that can be used as a write-once optical disc, or optical discs whose entire surface is a recording area. The optical disc of this configuration has a structure in which a guide groove for tracking is provided on a transparent substrate so that tracking control can be performed even during recording. By the way, for an optical disc to be compatible with compact discs, it must of course satisfy the standard values for reflectance among the various playback standards established for compact discs. The standard value for the reflectance of compact discs is 780 nm from the readout side of the optical disc.
The optical disc is required to have a reflectance of 70% or more when viewed from the readout side when a laser beam of Even if only the reflection loss on the surface is considered, in order to achieve a reflectance of 70% or more on the continuous side of the optical disc, the reflectance of the metal reflective film must be at least 80% or more. It is well known that compact "discs use an aluminum reflective film with a reflectance of 80% or more to satisfy the reflectance standards mentioned above (
It goes without saying that the reflectance described above changes depending on the conditions for forming the aluminum film). However, in write-once optical discs, since recording is performed on the recording film (recording layer), energy for recording is absorbed by the recording film, and as mentioned above, in write-once optical discs, the energy for recording is absorbed during recording. For tracking control,
Since the transparent substrate is provided with a guide groove for tracking control, the light intensity loss due to the incident light being diffracted by the guide groove is added, so that the reflectance on the read side of the optical disk is reduced by the reflectance on the compact disk. In the past, it was considered difficult to set the ratio to a standard value, but in recent years, as disclosed in Japanese Patent Application Laid-Open No. 2-42652, it has been found that A special dye-based recording film and a high-reflectance gold reflective film are laminated on the side of the plate where the tracking guide groove is provided by applying a spin coating method, allowing light with a wavelength of 780 nm to be applied. In contrast, a write-once optical disc has been proposed in which the reflectance of the land portion on the signal surface is 70% to 90%, which is the reflectance specified for compact discs. However, with the previously proposed write-once optical disc,
If a reflective film made of expensive gold is used as a metal reflective film, the reflectance of the land portion on the signal surface for light with a wavelength of 780 nm is 70% to 90%, which is specified by compact discs. It is possible to construct a type of optical disc that shows reflectance, but if cheap aluminum or aluminum alloy is used as the metal reflective film, the reflectance of the land portion on the signal surface is 70 nm for light with a wavelength of 780 nm. It has been difficult to construct a write-once optical disc that exhibits a reflectance of 90% to 90%, which is the standard for compact discs. In addition, it is not limited to write-once optical discs that can obtain the reflectance specified by the above-mentioned compact discs.
It is also well known that there have been requests for the realization of an optical recording medium disc that exhibits a predetermined high reflectance for light for recording and reproduction, and that the reflectance specified for compact discs can be obtained. Write-once optical discs such as
others. In order to construct an optical recording medium disk that exhibits a predetermined high reflectance for light for recording and reproduction, attempts have been made to provide an interference film for increasing the amount of reflected light on a recording film made of an organic dye material. became.

[Problems to be Solved by the Invention] However, in an optical disk having a structure in which an interference film for increasing the amount of reflected light is provided on a recording film made of the above-mentioned organic dye material, the interference film for increasing the amount of reflected light is made by applying a vapor deposition method. However, when film formation is performed by vapor deposition, it is possible to avoid high costs due to the need for large-scale equipment and long working hours, including several hours of exhaust work. There wasn't.

[Means to solve the problem]

In the present invention, a dye material containing an indolenine-based cyanine dye is dissolved in an alcohol-based solvent on the surface of a transparent substrate provided with a tracking guide groove, and A step of forming a recording film by applying the above-described film to a predetermined thickness by a spin coating method, and applying the above-mentioned ink film on the above-mentioned recording film that is transparent to the recording and reproducing light of the optical recording medium disc and A substance that has a refractive index lower than the refractive index of a dye material containing a renin-based cyanine dye and is soluble in an aliphatic or alicyclic hydrocarbon solvent is dissolved in an aliphatic or alicyclic hydrocarbon solvent. Then, a process of applying it to a predetermined film thickness by spin coating to form an interference film for increasing the amount of reflected light, and vacuum evaporation of a reflective film of metal or alloy on the interference film for increasing the amount of reflected light. A method for manufacturing an optical recording medium disk is provided, the method comprising forming an optical recording medium disk by a method or a sputtering method.

[Effect]

A dye material containing an indolenine-based cyanine dye is dissolved in an alcohol-based solvent and then spin-coated on the side of the transparent substrate on which the tracking guide groove is provided. A recording film is formed by applying the film to a predetermined film thickness by a coating method, and the above-mentioned indolenine is coated on the recording film and is transparent to the recording and reproducing light of the optical recording medium disc. A substance that has a refractive index lower than the refractive index of a dye material containing a cyanine dye and is soluble in an aliphatic or alicyclic hydrocarbon solvent is dissolved in an aliphatic or alicyclic hydrocarbon solvent. This is applied by spin coating to a predetermined thickness to form an interference film for enhancing the amount of reflected light. Since a vacuum atmosphere is not required to form the recording film and the interference film for increasing the amount of reflected light, an optical recording medium can be manufactured in a short time using simple equipment.

【Example】

/ Hereinafter, specific details of the method for manufacturing an optical recording medium disk of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view of a part of an optical recording medium disk manufactured by the method of manufacturing an optical recording medium disk of the present invention, and FIG. FIG. 3 is a curve diagram showing the reflectance characteristics of an optical recording medium disk. In FIG. 1 showing an optical recording medium disk manufactured by the optical recording medium disk manufacturing method of the present invention, 1 is a transparent substrate provided with tracking guide grooves G, G... A recording film 2, an interference film 3 for enhancing the amount of reflected light, and a reflective film 4 made of aluminum or aluminum alloy are disposed on the surface of the transparent substrate 1 on which the tracking guide grooves G, G, . . . are provided. and a protective film 5 are laminated. First, the method for manufacturing the optical recording medium disc of the present invention is as follows. An indolenine-based cyanine dye material (which may contain additives such as a quencher) is dissolved in a solvent 1 that does not attack the polycarbonate resin, such as a cellosolve-based, keto-alcohol-based, alcohol-based, or aliphatic hydrocarbon-based solvent. Using a spin coating method, a transparent substrate 11 made of polycarbonate resin is provided with guide grooves G, G, etc. for tracking, for example, a transparent substrate 1 is provided with guide grooves with a pitch of 1.6 microns. A recording film 2 having a thickness of 50 nm is formed. Next, it is transparent to the recording and reproducing light of the optical recording medium disc, has a refractive index lower than the refractive index of the dye material containing the above-mentioned indolenine cyanine dye, and has an aliphatic or alicyclic carbonized material. Aliphatic or alicyclic carbonization of substances that are soluble in hydrogen-based solvents and do not crystallize (resins such as petroleum resins, urethane resins, and silicone resins, hydrocarbon compounds such as triphenylmethane, various oil-based dyes, and pigments) To enhance the amount of reflected light, dissolve it in a hydrogen-based solvent (e.g. n-decane, n-heptane, n-hexane and their isomers, decalin, tetralin) and apply it to a predetermined thickness using a spin coating method. An interference film 3 is formed. As an example, the above-mentioned interference film 3 for enhancing the amount of reflected light can be prepared by dissolving petroleum resin (trade name: Inton) manufactured by Zeon Corporation in n-decane, and then dissolving it in n-decane.
A film with a thickness of about 50 nm can be formed thereon by spin coating. In addition, as another example, the above-mentioned interference film 3 for increasing the amount of reflected light
For example, petroleum resin manufactured by Nippon Zeon Co., Ltd. (trade name Finton) is dissolved in decalin, and then the above-mentioned
A film with a thickness of about 50 nm may be formed on ll12 by spin coating. It is well known that the thickness of the film formed by the spin coating method can be arbitrarily set by setting the concentration of the material, the rotation speed of the disk, etc. during the spin coating described above. Next, an aluminum reflective film 4 with a thickness of about 50 nm is formed by sputtering on the above-mentioned interference film 3 for increasing the amount of reflected light, and then an ultraviolet curing resin is formed on the above-mentioned aluminum reflective film 4. It is coated and irradiated with ultraviolet rays to form a protective film 5 with a thickness of about 5 microns. Figure 2 shows an increase in the amount of reflected light by 1 in an optical recording medium disk having a 50 nm thick recording film 2 made of an indolenine cyanine dye material as the recording layer 2 and a 50 nm thick aluminum film as the reflective film 4. FIG. 3 is a diagram showing changes in the reflectance of land portions in the optical recording medium disk when the film thickness of the interference film 3 is changed.

【Effect of the invention】

As is clear from the detailed explanation above, the present invention provides an indolenine-based cyanine dye on the side of the transparent substrate provided with the tracking guide groove. A recording film is formed by dissolving the dye material contained in an alcohol-based solvent and applying it to a predetermined film thickness using a spin coating method.
Furthermore, the above-mentioned recording film is transparent to the recording and reproducing light of the optical recording medium disc, has a refractive index lower than the refractive index of the dye material containing the above-mentioned indolenine cyanine dye, and has an aliphatic Alternatively, a substance soluble in alicyclic hydrocarbon solvents is dissolved in an aliphatic or alicyclic hydrocarbon solvent, and the amount of reflected light is increased by applying it to a predetermined thickness using a spin coating method. Since a vacuum atmosphere is not required to form the recording film and the interference film for enhancing the amount of reflected light, optical recording media can be manufactured in a short time with simple equipment. According to the present invention, the above-mentioned conventional problems can be satisfactorily solved.In addition, according to the method of manufacturing an optical recording medium of the present invention, it is possible to solve the above-mentioned conventional problems depending on the dye material used in the structure of the recording film. There is an advantage that an optical recording medium with a predetermined reflectance can be easily obtained by changing the thickness of the interference film for increasing the amount of reflected light and the constituent material of the reflective film.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a part of an optical recording medium disk manufactured by the method of manufacturing an optical recording medium disk of the present invention, and FIG. FIG. 3 is a curve diagram showing the reflectance characteristics of an optical recording medium disk. 1...Transparent substrate provided with guide grooves G, G... for tracking, 2...Recording film, 3...Interference film for enhancing the amount of reflected light, 4...Reflection by aluminum or aluminum alloy Membrane, 5...Protective membrane, Substitute Yassho Buriji Sunma Shao-1

Claims (1)

[Claims] A dye material containing an indolenine-based cyanine dye is dissolved in an alcohol-based solvent and then spin-coated on the side of the transparent substrate on which the tracking guide groove is provided. forming a recording film by coating the recording film to a predetermined thickness using a method;
The above-mentioned recording film is transparent to the recording and reproducing light of the optical recording medium disc, has a refractive index lower than the refractive index of the dye material containing the above-mentioned indolenine cyanine dye, and has an aliphatic or aliphatic material. A substance that is soluble in a cyclic hydrocarbon solvent is dissolved in an aliphatic or alicyclic hydrocarbon solvent, and then applied to a predetermined film thickness using a spin coating method to create interference for increasing the amount of reflected light. A method for manufacturing an optical recording medium disk, comprising the steps of forming a film, and forming a metal or alloy reflective film on the interference film for increasing the amount of reflected light by vacuum evaporation or sputtering.