JPH0448353B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to an information recording carrier, and more particularly to an optical information recording carrier having a recording layer sensitive to laser light.

BACKGROUND ART Optical recording and reproducing methods are well known, in which information such as video and audio is recorded and reproduced using an optical information recording carrier having a recording layer sensitive to laser light. In such an optical recording/reproducing method, in order to record information, a laser beam modulated in a predetermined manner according to an information signal is irradiated onto the surface of the recording layer of an optical information recording carrier such as an optical recording disk. information is recorded by forming a row of pits. A conventional optical information recording carrier usually has a cross-sectional structure as shown in FIG. That is, the base 1 is made of a material selected from glass, acrylic resin, vinyl resin, polyether resin, epoxy resin, polycarbonate resin, polybutyral resin, cellulose acetate butyrate resin, nitrocellulose resin, and the like. A thin film made of a material that sublimates upon exposure to laser light is provided as a recording layer 2 on this substrate 1 for forming pits. Examples of materials that can be sublimated by laser light include those obtained by dissolving a dye sensitizer (dye) and a binder such as nitrocellulose in a ketone solvent. Further, in order to make the thickness of the recording layer 2 uniform, the recording layer is formed by a method called a spin coating method. In this case, while rotating the substrate 1 around its center at, for example, about 200 rpm, a solution of the photosensitive material on which the recording layer 2 is to be formed is dripped onto the substrate through a nozzle that moves gently in the radial direction, After stopping the dropping, the rotation speed of the substrate 1 is increased to, for example, about 1000 rpm, and the excess solution is shaken off to form a uniform solution layer containing the photosensitive material on the substrate 1. Thereafter, the solution layer is dried and the solvent component is volatilized to form the recording layer 2.

However, it became clear that it was difficult to obtain a recording layer with good photosensitivity to a laser beam of a certain wavelength using a single photosensitive material, so it became clear that it was difficult to obtain a recording layer with good photosensitivity to laser light of a certain wavelength. It is considered to form. However, in order to form a recording layer made of two or more types of photosensitive materials, it is necessary to
A solution must be obtained using a solvent that is compatible with the type of photosensitive material, and spin coating must be performed using this solution, resulting in a problem that the degree of freedom in selecting the photosensitive material is narrowed. Furthermore, when selecting a compatible solvent, consideration must be given to the condition that it does not have any adverse effects such as dissolution or swelling on the substrate 1, and there are severe restrictions on the combination of photosensitive materials and solvents. be.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an optical information recording carrier with excellent photosensitivity to laser light.

The optical information recording carrier according to the present invention is a write-once optical recording carrier having a plurality of overlapping recording layers, the recording layer being formed of an organic photosensitive material, wherein at least one of the recording layers is Adjacent layers are formed of organic photosensitive materials having different solubility, and the organic photosensitive materials have light absorption bands that overlap each other at least in part.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a cross section of an information record carrier according to the invention. That is, the base 21 is made of a material selected from glass, acrylic resin, vinyl resin, polyether resin, epoxy resin, polycarbonate resin, polybutyral resin, cellulose acetate butyrate resin, nitrocellulose resin, and the like. The first recording layer 22 is a thin film layer of an infrared and ultraviolet absorbing material A formed on the substrate 21 by spin coating. The second recording layer 23 is a thin film layer of near-infrared absorbing material B formed on the recording layer 22 by spin coating. The third recording layer 24 is a thin film layer of the same infrared and ultraviolet absorbing material A as the recording layer 22 formed on the recording layer 23 by spin coating.

In the process of forming the plurality of recording layers 22, 23, and 24, they are sequentially laminated on the substrate 21. That is, the infrared and ultraviolet absorbing material A is spin-coated with a solvent a that does not damage the substrate 21, and after the solvent a dries, the recording layer 22 is formed.
Next, the near-infrared absorbing material b is spin-coated with a solvent b that does not damage the recording layer 22, and after the solvent b dries, a recording layer 23 is formed. Next, the recording layer 24
is formed in the same manner as the recording layer 22. By arranging the infrared and ultraviolet absorbing material A to sandwich the near-infrared absorbing material B, the shapes of the pits after sublimation of the recording layer are complementary to each other, and the shape at the boundary between the pit and the non-pit portion is the same as the whole. As such, it is not greatly affected by the noise wavelength component of the laser light used, and can prevent noise during reproduction. It goes without saying that the adjacent recording layers are made of different materials, dissolved in different solvents, and formed by a spin coating method or the like.

Further, in the above embodiments, an infrared and ultraviolet absorbing photosensitive material was used as the photosensitive material, but the recording layer may be formed of a material that has water resistance, solvent resistance, and weather resistance in addition to photosensitivity. It is also possible to form each layer using a composite material thereof. It is preferable that such photosensitive materials having water resistance, solvent resistance, and weather resistance are laminated in such a manner that a recording layer 23 is sandwiched therebetween, as shown in recording layers 22 and 24 shown in FIG.

For example, when using different photosensitive materials (), (), () having transmittances (), (), () for the wavelengths of laser light shown in FIG. 3, the photosensitive materials are coated on the substrate 31 with different solvents. Spin coat and laminate. In this way, the mutual photosensitivity characteristics are complemented, and good overall characteristics can be obtained for laser light with a wavelength of 830 mm, for example. In other words, each recording layer having the sensitivity characteristics of () and () does not respond to low-frequency laser light, and the recording layer has the sensitivity characteristics of () without being affected by low-frequency laser light. This makes it possible to compensate for the deterioration in shape at the boundary between pits and non-pit portions after sublimation of the layer, and to obtain a good pit boundary shape penetrating the entire recording layer.

Effects As described above, according to the present invention, by laminating photosensitive materials that could not be made into thin films due to poor common compatible solvents and making them into thin films,
It is possible to obtain a recording layer that is not adversely affected by the noise wavelength component in the laser beam and has a steep overall absorption characteristic for a predetermined wavelength component. Furthermore, it becomes possible to use a combination of materials having various UV resistance, infrared ray resistance, water resistance, solvent resistance, and weather resistance, and the complementary effects of these materials make it possible to improve overall performance. That is,
It is possible to obtain an information recording carrier that is less susceptible to deterioration due to external light after the recording process. In addition, if the material for the base recording layer that adheres to the base is a material that can be dissolved in a solvent that does not have a negative impact on the base, the material for the recording layer laminated on the base recording layer may have an adverse effect on the base. It is also possible to use a certain solvent, thereby increasing the degree of freedom in material selection.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a conventional optical information recording carrier, FIG. 2 is a partial cross-sectional view of an optical information recording carrier of the present invention, and FIG. 3 is a partial cross-sectional view of a conventional optical information recording carrier. 3 is a graph showing a characteristic curve of rate. Explanation of symbols of main parts, 1 and 21...Foundation,
2... Recording layer, 22... First recording layer, 23... Second recording layer, 24... Third recording layer.

Claims (1)

[Claims] 1. A write-once optical type having a plurality of overlapping recording layers, each of which is made of an organic photosensitive material capable of absorbing a single irradiated laser beam to form an optically deformable portion. In the recording carrier, at least one of the adjacent recording layers is formed of a first organic photosensitive material having a solubility that is insoluble in a second solvent that dissolves the other, and the other is formed of a first organic photosensitive material that is insoluble in a second solvent that dissolves the other. The second organic photosensitive material has a solubility that is insoluble in the first solvent that dissolves the organic photosensitive material, and the first and second organic photosensitive materials have light absorption bands that overlap at least in part with each other. . A write-once optical record carrier, wherein the frequency of the irradiated laser beam is within the overall optical absorption band of the entire recording layer.