JPH03181030A - Optical recording medium disk - Google Patents

Abstract

PURPOSE:To easily form a recording film having specified recording characteristics by constituting the recording layer of two layers, one is an org. material film which shows reduction of refractive index by absorption of proper quantity of recording light, and the other is a transparent material film having 95% or higher transmittance for recording/reproducing light. CONSTITUTION:On a transparent substrate 1 having guide grooves G, G... for tracking, there is formed a recording layer RL of two-layer structure. The one layer is an org. material film 2 formed by vapor deposition, which shows reduction of refractive index by absorption of proper quantity of recording light, and the other is a transparent material film 3 formed by spin coating, which has 95% or higher transmittance for the recording/reproducing light of specified wavelength. The recording layer RL is formed so as to have recessed parts g, g,... of specified depth corresponding to the tracking guide grooves G, G,... of the transparent substrate 1. A metal reflecting film 4 is then formed on the recording layer RL. By this method, the recording layer of specified characteristics can be easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to optical recording media discs, and in particular to write-once optical recording media discs compatible with compact discs.

(Prior Art) As the demand for recording various information signals at high recording densities has increased, in recent years, information recording media created based on various structural and operating principles have been used to record various information signals at high recording densities. It is well known that high-density recording and reproduction of signals has become possible. For example, information signals are recorded by forming irregularities corresponding to the information signals on the signal surface of an information recording medium.

A recording and reproducing apparatus reproduces a recorded information signal by optical means or by detecting a change in capacitance value.

It is already in practical use for recording and reproducing 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 that record information signals by causing physical or chemical changes, but in recent years it has become easier to obtain semiconductor lasers that operate stably. Along with this, various optical recording media (which use laser light for high-density recording and reproduction)
It is well known that optical discs) have already been put into practical use, or research and development is currently underway to put them into practical use.

In other words, recorded optical discs (playback-only optical discs) that are mass-copied from master discs on which information signals are recorded using bits formed by geometrically concave or convex parts are, for example, video discs or compact discs. In addition, optical discs that can be added and recorded only once by the user (write-once optical discs) and erasable optical discs are becoming more and more popular in general households, such as file memory for offices and other uses. Research and development is actively being carried out for the purpose of

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. For example, a spot of light with a minute diameter is projected onto the signal surface of an information recording medium,
As a tracking error detection method used for tracking control in an optical information signal reproducing device that reproduces an information signal based on reflected light whose intensity is modulated by bits formed on the signal surface, there is a tracking error detection method that is used for tracking control from an information recording medium. The so-called push-pull tracking error detection method uses the fact that the intensity distribution of the reflected light is biased by the tracking error to detect the tracking error, but the optical system has a simple configuration. In addition, it is widely used because it is advantageous in terms of cost.In addition, a straight line that projects a first light spot for signal reading onto the signal surface of an information recording medium and includes the first light spot described above. Above.

Projecting second and third light spots for tracking at symmetrical positions with the first light spot as the center of symmetry,
The second point mentioned above. It is well known that a tracking error detection method that detects a tracking error based on the reflected light generated on the signal surface of the information recording medium by the third light spot has also been used. When reproducing information signals recorded at high density on various types of information recording media, the reproducing operation is usually performed under tracking control operation.

Now, a compact disc, which is known as one of the information recording media in which information signals are recorded at high density by an arrangement of bits corresponding to the information signals on the signal surface of the information recording medium, is a compact disc that uses 780 nm light. An information signal is recorded on the signal surface by an array of bits with a depth set in a specific relationship with respect to the wavelength, and the entire surface of the signal surface is covered with a thin film such as aluminum. It is specified that the reflectance of the land portion on the signal surface is 70% to 90% for light with a wavelength of 780 nm, and the readout of information signals from the signal surface of the information recording medium is This is done using a 780 nm light spot.

When reading an information signal from the above-mentioned compact disc, the amount of light reflected from the bit portion on the signal surface of the compact disc is greater than the amount of light reflected from the land portion as a result of light interference occurring at the bit portion. This is done by taking advantage of the fact that the amount of light is reduced compared to the amount of light, and the tracking error information is also based on the amount of light reflected from the recorded trace.
It is obtained by using the difference between the amount of light reflected from the land portion and the amount of light reflected from the land portion.

Now, with the spread of compact discs mentioned above, there are seven types of optical discs that are compatible with compact discs that can be played using a compact disc player: Various proposals have been made for write-once optical discs that have a recording area that can be used as optical discs, or for optical discs that have a recording area that covers the entire surface.
In an optical disc having a recording area as described above, a guide groove for tracking is provided in a transparent substrate so that tracking control is performed even during recording.

By the way, as an optical disc that is compatible with compact discs, it goes without saying that compact discs are
It must satisfy the standard values for reflectance among the various standards for playback established for 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 at the surface is considered, in order to achieve a reflectance of 70% or more on the reading side of an optical disc, the reflectance of the metal reflective film must be at least 80% or more. .

Therefore, it is well known that compact discs use an aluminum reflective film that exhibits a reflectance of 80% or more, and that it satisfies the standard value of the reflectance mentioned above (the above reflectance is (Needless to say, it changes depending on the film formation conditions).

However, in write-once optical discs, the energy for recording is absorbed by the recording film (recording is performed as the recording progresses), and as mentioned above, in write-once optical discs, the For tracking control, since a guide groove for tracking control is provided on the transparent substrate, the reflectance on the read side of the optical disc is reduced due to the loss of light amount due to the incident light being diffracted by the guide groove. In the past, it was thought to be difficult to set reflectance to a standard value for compact discs, but in recent years, for example, the magazine ``Electronic Ceramics J
As disclosed in pages 49 to 52 of the November 1987 issue, spin coating is applied to the surface of a transparent substrate provided with a tracking guide groove on the side where the tracking guide groove is provided. By applying the method, a special dye-based recording film and a metal reflective film are laminated, and the wavelength is 780 nm.
A write-once optical disc is disclosed in which the land portion on the signal surface has a reflectance of 70% to 90% for light of m, which is defined as a reflectance for compact discs, and another application is filed. Even companies that apply for a patent application first on Hei 1-4.
In No. 044, as a write-once optical disc compatible with compact discs, a transparent substrate is provided with a guide groove for tracking, and a surface of the transparent substrate on which the guide groove for tracking is provided is provided. .

When irradiated with a recording laser beam having a predetermined wavelength, an organic material film whose refractive index decreases by absorbing an appropriate amount of the laser beam is applied to the transparent substrate. We propose an optical disc in which a metal reflective film is provided on the organic material film, which is formed by a spin coating method so that the film thickness of the portion of the transparent substrate other than the tracking guide groove is (d - Δd). are doing.

(Problem K111 to be solved by the invention) However, the previously proposed write-once optical disc absorbs an appropriate amount of the laser beam when it is irradiated with a recording laser beam having a predetermined wavelength. A single-layer recording layer made of an organic material film whose refractive index decreases is formed using a spin coating method. The problem is that the types of constituent materials that can be used as the recording film are limited, and since the recording layer is formed by spin coating, it is not easy to form a recording layer with predetermined characteristics. , and a solution was sought.

(Means for Solving the Problems) The present invention provides a transparent substrate provided with a guide groove for tracking, and a film formed by vapor deposition on the surface of the transparent substrate on which the guide groove for tracking is provided. an organic material film that absorbs an appropriate amount of recording light and reduces the refractive index;
For tracking on the above-mentioned transparent substrate, a recording layer having a two-layer structure consisting of a film formed by a spin coating method and a film made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength is used. an optical recording medium disk (optical disk) formed with a recess of a predetermined depth in a portion corresponding to the guide groove, and a metal reflective film laminated on the recording layer; A transparent substrate is provided with a guide groove for tracking, and a recording/reproducing device having a predetermined wavelength is formed by forming a film using a spin coating method on the surface of the transparent substrate on which the guide groove for tracking is provided. The recording layer has a two-layer structure: a film made of a transparent material that has a transmittance of 95% or more for the intended light, and an organic material film that absorbs an appropriate amount of the recording light and reduces the refractive index by forming a film using a vapor deposition method. , is formed with a recess of a predetermined depth in the portion corresponding to the guide groove for tracking in the transparent substrate described above, and a metal reflective film is laminated on the recording layer. Provides recording medium discs (optical discs).

(Function) A transparent substrate provided with a guide groove for tracking and a recording layer deposited on the surface of the transparent substrate on which the guide groove for tracking is provided are formed by vapor deposition. an organic material film that absorbs an appropriate amount of recording light to reduce its refractive index, and a transparent material that has a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength, formed by spin coating. The recording film that constitutes a part of the recording layer, that is, the organic material film that absorbs an appropriate amount of recording light and reduces the refractive index, is formed by a vapor deposition method. By forming a film, a recording film having predetermined recording characteristics can be easily formed by setting the film thickness and other various conditions correctly, and by forming a film by spin coating, it is possible to create a recording film with a predetermined wavelength. A film (transparent film) formed using a transparent material with a transmittance of 95% or more is determined by the characteristics of the recording film described above, such that the film thickness is set to a predetermined value for the reflectance of the disc. It is easy to configure as any desired and furthermore,
Since the recording layer described above is formed with a predetermined depth α in the portion corresponding to the tracking guide groove on the transparent substrate, tracking information can also be easily reproduced.

(Example) Hereinafter, specific contents of the optical recording medium disk of the present invention will be explained in detail with reference to the accompanying drawings. Fig. 2 is a vertical sectional view of a part of the optical recording medium disk of the present invention, Fig. 3 and Fig. 4 are longitudinal sectional views of a part of a conventional optical recording medium disk, and Fig. 5 is a longitudinal sectional view of a part of the conventional optical recording medium disk. is a diagram showing the relationship between the combination of a recording film and a transparent film and the reflectance.

Figure 1 shows a transparent substrate l on which tracking guide grooves G, G... are provided, and the surface of the transparent substrate l on which the tracking guide grooves G, G... are provided. An organic material film 2 is formed by vapor deposition to absorb an appropriate amount of recording light to reduce the refractive index, and a film is formed by spin coating to transmit recording and reproducing light having a predetermined wavelength. A recording layer RL having a two-layer structure consisting of a transparent material II3 and a transparent material having a transparent material ratio of 95% or more is provided with depressions g2g of a predetermined depth in the portions of the transparent substrate 1 corresponding to the tracking guide grooves G, G... . . , and a metal reflective film 4 is laminated on the recording layer RL. Figure 2 shows a transparent substrate 1 provided with tracking guide grooves G, G... and the tracking guide grooves G, G... in the transparent substrate 1 described above.
A film 3 made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength by forming a film by a spin coating method on the surface of the plate where ... is provided,
The recording WRL has a two-layer structure with an organic material film 2 that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by a vapor deposition method.
Guide groove G for tracking in the transparent substrate 1 described above
, G... Which corresponding part has a depression of a predetermined depth gtg...
2 is a vertical cross-sectional view of an optical recording medium disc (optical disc) having a configuration in which a metal reflective film 4 is laminated on the recording layer RL.

Next, in FIGS. 3 and 4 showing an example of the configuration of a conventional optical disc, 1 indicates a tracking guide groove G;
In addition, in FIG. 3, reference numeral 2 denotes a transparent substrate on which guide grooves G, G, and so on for tracking are provided on the transparent substrate l, by vapor deposition. An organic material film that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film. In Fig. 4, 5 is an organic material film that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by spin coating. be.

The optical disks shown in FIGS. 3 and 4 described above have an organic material film 2 that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film using a vapor deposition method, and an organic material film 2 that absorbs an appropriate amount of recording light by forming a film using a spin coating method. an organic material film 5 that reduces the refractive index by absorbing
Although it is shown without a metal reflective film laminated thereon.

In an actual optical disk, like the optical disks illustrated in FIGS. 1 and 2, an organic material film 2 that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by a vapor deposition method,
It is used in a state in which a metal reflective film is laminated on a recording layer such as an organic material film 5 that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by a spin coating method.
The reflectance values shown in the figure were also obtained with the metal reflective films laminated as described above.

Guide groove G for tracking shown in each figure.

The transparent substrate 1 provided with G... is, for example, a commercially available one with a guide groove for tracking and a diameter of 120 m.
m polycarbonate substrates can be used.

As mentioned above, when a polycarbonate substrate is used as the transparent substrate 1, a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength (780 nm) is a material that does not corrode the polycarbonate substrate. It is sufficient to use a substance that is soluble in a solvent (alcohol-based solvent) and that does not precipitate crystals after film formation. If it is a substance, the film made of the substance will also have an ultraviolet absorbing function.
The light resistance of the optical disc can be improved.

Using a polycarbonate substrate as a transparent substrate, 7
Transmittance of 9 for recording and reproducing light with a wavelength of 80 nm
To form a transparent Mj3 made of a transparent material of 5% or more on the substrate 1 or on the recording film 2 formed on the substrate 1, an alcohol-based solvent that does not attack the polycarbonate substrate, such as n-butanol or cellosolve, is used. As a solvent,
and 1 to 4% by weight of UV-Blue-1 or A.
C i dRe d 52 (see FIG. 5) is dissolved and a film is formed by spin coating.

In addition, as the constituent material of the organic material film that absorbs an appropriate amount of the recording light and reduces the refractive index, it is possible to use a material that can be formed into a film by a vacuum evaporation method and that absorbs light in the vicinity of the wavelength band of 780 nm to 830 nm. Substances that have the property of absorbing C, such as C
U-phthalocyanine can be used, and a metal-dispersed organic material such as a gold-guanine co-deposited film can be used as a constituent material of the organic material film that absorbs an appropriate amount of the recording light and reduces the refractive index. Naturally, the constituent material of the organic material film that absorbs an appropriate amount of recording light and reduces the refractive index is not limited to the substances exemplified above.

In FIG. 5, #1 to #6 in the Example column are numbers for distinguishing the examples of the structure of the optical disk wrapper of the present invention, and #1 in the Comparative Example column.

#2 is a number for distinguishing the configuration of the wrapper of the optical disc as a comparative example.

In addition, the numbers written in the figure number column in Figure 5 are the figure numbers of the attached drawings, and the numbers written in the columns of the recording film (deposited film) and transparent film (spin coated film), respectively. What is listed is the name of the material used for film formation, and the values listed in the column for on-groove reflectance (%) are for forming a 700 angstrom thin gold film as Metal Reflective II!14 by magnetron sputtering. The diameter is 1 from the surface side of the transparent substrate 1 in the optical disc in the state of
This is the reflectance obtained when 780 nm light of m and m is incident.

The recording film 2 of the optical disk shown in #1 to #6 of the embodiment shown in FIG. The transparent film 3 of the optical disk shown in #1 to #6 of the embodiment shown in FIG. A film is formed by dissolving 1 to 4% by weight of each of the materials listed in the column ``Film'' in an alcohol-based solvent 2, such as n-butanol or cellosolve, which does not attack the polycarbonate substrate, and using a spin coating method.

Now, the reflectance values of the optical disks #1 to #6 of the example shown in FIG. 5 and the value of $1.0 of the comparative example. As can be readily seen by comparing the reflectance values for the optical disc shown in #2, the optical disc cited as a comparative example, that is, as shown in Figure 3, has a recording film made by vapor deposition. A configuration in which a recording layer consisting of only two layers of an organic material film that absorbs an appropriate amount of recording light and reduces the refractive index by film formation is provided, and a metal reflective film is laminated on top of the recording layer. In contrast to the optical discs (the reflective film is not shown) whose 1 reflectance is as low as 55% and 59%,
The optical disc shown in FIGS.
As shown in the figure, the recording layer RL consists of an organic material film 2 (recording film 2) that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by a vapor deposition method, and a film formed by a spin coating method. A recording layer RL having a two-layer structure including a film 3 (transparent film 3) made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength is formed on the transparent substrate described above. The reflectance of an optical disc having a structure in which a recess of a predetermined depth is formed in a portion corresponding to the tracking guide groove in the recording layer RL, and a metal reflective layer [4] is laminated on the recording layer RL is as follows. , even if the conventional recording layer shown in the comparative example is provided with the recording film 2 made of the same constituent material as the optical disc with a single-layer structure, the fifth
As shown in the figure, the reflectance is significantly higher than that of the comparative example, and the reflectance of the optical disk of the present invention satisfies the standard value of reflectance for compact disks. Further, tracking control signals can also be generated satisfactorily due to the depressions g in the recording layer RL.

As mentioned above, the recording layer RL is made of an organic material film 2 (which absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by vapor deposition).
A recording film 2) and a film 3 (transparent film 3) made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength by film formation by a spin coating method.
A recording layer RL having a layered structure is formed with a recess of a predetermined depth in a portion corresponding to the guide groove for tracking in the transparent substrate, and a recording layer RL is formed on the recording layer RL. In the optical disc of the present invention having a structure in which metal reflective films 4 are laminated, the recording film 2 is formed to a predetermined thickness using a desired recording material by applying a vapor deposition method. In order to make the optical disc have a predetermined reflectance, a film 3 made of a transparent material can be formed to a desired thickness on the tracking guide grooves G, G, etc., which are provided in advance on the transparent substrate 1. Because it is done to
Optical discs compatible with compact discs can be easily manufactured while increasing the degree of freedom in selecting recording materials when manufacturing optical discs.

(Effects of the Invention) As is clear from the above detailed explanation, the optical disc of the present invention includes a transparent substrate provided with a guide groove for tracking, and a guide groove provided for tracking in the transparent substrate. The recording layer deposited on one side of the plate consists of an organic material film (recording film) that absorbs an appropriate amount of recording light and reduces the refractive index by depositing it by vapor deposition, and a film deposited by spin coating. A recording film constituting a part of a recording layer of 2 mWK, consisting of a film made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength. By forming a film using a vapor deposition method, a recording film having predetermined recording characteristics can be easily formed by correctly setting the film thickness and other various conditions, and by forming a film using a spin coating method, a recording film having a predetermined wavelength can be easily formed. The film (transparent film) formed using a transparent material with a transmittance of 95% or more for light used for recording and reproduction must have a film thickness as described above so that the reflectance of the disc is set to a predetermined value. Since the thickness of the recording film can be adjusted to any desired thickness depending on the characteristics of the recording film, it is possible to create optical discs compatible with compact discs while increasing the degree of freedom in selecting recording materials when producing optical discs. Moreover, since the recording layer described above is formed with a recess of a predetermined depth in the portion of the transparent substrate corresponding to the guide groove for tracking, it is possible to easily manufacture the recording layer for tracking. Information can also be easily reproduced.

[Brief explanation of drawings]

3 and 4 are vertical sectional views of a portion of a conventional optical recording medium disk, and FIG. FIG. 2 is a diagram showing the relationship between the combination of a recording film and a transparent film and the reflectance. 1... A transparent substrate provided with a guide groove for tracking, 2... An organic material film (recording film) that absorbs an appropriate amount of recording light and reduces the refractive index by forming a film by vapor deposition, 3...・
A film made of a transparent material (transparent film) with a transmittance of 95% or more for recording and reproducing light, 4...Metal reflective film, 5...A film formed by spin coating to absorb an appropriate amount of recording light. an organic material film that reduces the refractive index, RL...a recording layer with a two-layer structure,

Claims (1)

[Claims] 1. A transparent substrate provided with a guide groove for tracking;
An organic material film that absorbs an appropriate amount of recording light and reduces the refractive index is formed by vapor deposition on the surface of the transparent substrate on which the tracking guide groove is provided, and an organic material film is formed by spin coating. A two-layer recording layer consisting of a film made of a transparent material having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength is connected to the tracking guide groove in the transparent substrate described above. An optical recording medium disc 2 is formed with a recess of a predetermined depth in the corresponding portion and a metal reflective film is laminated on the recording layer, and a guide groove for tracking is provided. A certain transparent substrate,
A film having a transmittance of 95% or more for recording and reproducing light having a predetermined wavelength is formed by spin coating on the surface of the transparent substrate on which the tracking guide groove is provided. A two-layer recording layer consisting of a transparent substance film and an organic material film formed by vapor deposition to absorb an appropriate amount of recording light and reduce the refractive index is connected to the tracking guide groove in the transparent substrate described above. An optical recording medium disk formed with a depression of a predetermined depth in a corresponding portion, and a metal reflective film laminated on the recording layer.