JPH04162223A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical information recording medium, which can be manufactured through a comparatively simple manufacturing process and can form a small-sized recording mark, by forming a recording-string guide groove in a layer nearest to a disk substrate. CONSTITUTION:A recording string is formed in a recording film 102 constituted by laminating at least two layers or more of films on a disk substrate 101 spirally or concentrically and information is recorded, and a recording-string guide groove 104 is formed in a layer nearest to the disk substrate 101. That is, trigger layers 103 promoting the process of mark formation are formed, and the track guide grooves 104 are formed by the trigger layers 103. When laser beams are applied on recording, the organic matter of the trigger layers 103 is expanded, and the recording layer 102 is pushed up and recording marks 105 are formed. Accordingly, an optical information recording medium capable of forming the small-sized recording marks can be acquired without complicating a manufacturing process.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an optical information recording medium.

(Prior Art) In an optical disk device, information is recorded on the surface along spiral or concentric tracks, and the information signal is optically reproduced by irradiating a light beam such as a laser beam. Document file systems were commercialized in the early days as devices that allowed users to record information signals onto optical disks using lasers, and products aimed at applications as peripheral storage devices for computers that required a higher level of reliability. has also been put into practical use. Furthermore,
Devices that can erase and rewrite stored information signals have also come into practical use. Further, progress has been made in the development of optical card memory devices or optical tape memory devices in which similar techniques are applied to card-shaped or tape-shaped recording media.

In the optical information recording medium used in these optical information recording and reproducing devices, a recording mark of about 1 micron in size is created at a track pitch of about 1.6 microns using a laser beam whose optical spot diameter is focused to about 1.2 microns, for example. It is formed on the recording column. As methods for forming recording marks, various methods have been proposed and put into practical use that cause local destruction, deformation, or change in optical properties of the recording film. In addition, in order to accurately track the recording array with a laser beam, it is widely practiced that a dock guide groove is provided in advance on the optical disk, and the laser beam position is controlled based on a tracking error signal obtained from the diffracted light. .

Such optical information recording devices are capable of recording information at extremely high density. However, like other recording devices, there is a strong social demand for devices that are smaller and have a larger capacity, that is, a higher recording density. In order to improve the recording density, it is necessary to reduce the track pitch or the interval on the recording row. FIG. 3 shows a schematic diagram of recording marks in an example of a conventional optical information recording medium. In FIG. 3, 301 is a disk substrate, 30
2 is a track guide groove, 303 is a recording film, and 304 is a recording mark formed on the recording film.

The recording mark forming method in this conventional example utilizes deformation of the recording film by laser irradiation, and records by forming localized bubbles. The size of the recording mark is determined by the spot diameter of the irradiation beam and the properties of the recording film. While using such recording marks, track pitch,
Alternatively, if the mark interval on the recording row is made smaller, code amount interference of the reproduced signal or crosstalk from adjacent tracks increases, resulting in errors being mixed into the reproduced information. A possible solution to this problem is to shorten the wavelength of the light to reduce the diameter of the irradiation spot, but this method is limited to the range of practically used light sources.

Even if the wavelength of light is not shortened, it is possible to improve the recording density by forming smaller recording marks. A patent proposal (13A899238-1) discloses a technique for recording a recording mark with a small width using a recording film having a multilayered medium structure in which a material that promotes the process of mark formation is embedded in the track guide groove. This results in
It became possible to improve recording density by reducing the track pitch. FIG. 4 shows a schematic diagram of a recording film with this multilayered medium structure. In the figure, 401 is a disk substrate, 402 is a track guide groove, 403 is a recording layer, 404 is a trigger layer that promotes the mark shape process, and 405 is a recording mark formed on the recording layer.

It can be seen that the width of the recording mark is smaller compared to the front side. However, in this method of embedding a layer of birds in the guide groove, the process for manufacturing the medium becomes complicated, so there is a problem in that it is difficult to efficiently supply a large quantity of inexpensive medium.

(Problems to be Solved by the Invention) As mentioned above, conventionally it is difficult to realize a factory with high recording density without assuming a shorter wavelength light source and without complicating the media manufacturing process. Met.

Therefore, the present invention was made in view of these circumstances.
The purpose is to provide an optical information recording medium that can be manufactured by a relatively simple manufacturing process and that can form recording marks smaller than conventional ones even with the same optical system as conventional ones.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method for forming recording columns in a spiral or concentric manner on a recording film formed by laminating at least two or more layers on a disk substrate. An optical information recording medium for recording information, characterized in that a recording column guide groove is formed in a layer closest to a disk substrate.

(Function) According to the present invention described above, it is possible to add the function of a track guide groove without forming a track guide groove on the disk substrate. This makes it possible to provide an optical information recording medium that can be manufactured using a simpler manufacturing process than conventional ones, and can form recording marks smaller than conventional ones even with the same optical system as conventional ones.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of an optical information recording medium according to an embodiment of the present invention. In FIG. 1, 101 is a disk substrate, 102 is a recording layer, 103 is a trigger layer that promotes the mark formation process, and 104 is a track guide groove formed in the trigger layer. Also, ]05 is a recording mark formed on the recording layer. The mechanism by which the trigger layer promotes the process of forming recording marks is that when a laser beam is irradiated during recording, the organic material in the trigger layer expands and pushes up the recording layer, and the trigger layer tends to sublimate, vaporize, and boil. This is due to the fact that it has good releasability from the recording layer.

If the refractive index of the trigger layer material is close to the refractive index of the substrate, it is optically considered to be a disk with the same structure as a conventional track guide groove, and a tracking error signal of good quality can be detected.

When the refractive indexes differ, the tracking error signal deteriorates because light is reflected at the interface between the substrate and the trigger layer. However, if the refractive index (nI) of the material of the trigger layer and the refractive index (n, ) of the disk substrate are I nl −no I/'(rz +r+, ) <
When the relationship is 0.2, the influence of light reflection at the boundary surface is sufficiently small, and it is possible to detect a good tracking error signal.

FIG. 2 is a diagram showing a manufacturing process of an optical information recording medium according to an embodiment of the present invention. First, as shown in FIG. 2a, a photoresist is coated on a disk substrate, exposed in a spiral pattern at a track pitch of 1.2 microns, and developed to form grooves. Next, a material for the trigger layer is deposited by sputtering to obtain state C.

Next, the photoresist is removed using a removal solution to obtain the state shown in d. Furthermore, a recording layer was deposited by sputtering to produce a medium as shown in e. Note that a glass disk substrate was used. As can be seen from the above manufacturing process, since there is no need to form guide grooves on the glass, there is no need to etch the glass, which simplifies the process.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the dimensions and materials shown in the embodiments of the present invention are not limited thereto. Further, the mechanism for promoting the formation process of the trigger layer or recording mark depends on the material of the layer and is not limited to the mechanism of the embodiment. For example, when polycarbonate is used for the trigger layer, it has a high heat storage effect due to its low thermal conductivity, and is effective as a mechanism for suppressing the rise in ambient temperature. In this way, the materials of the recording layer and the trigger layer are not limited to the examples. Furthermore, although a two-layered recording film was used in this example, another layer may be laminated for the purpose of protecting the film or improving its characteristics, and the number of layers is limited depending on the total number of layers. isn't it.

Further, although glass was used as the substrate material in this example, a resin substrate such as acrylic or 23 carbonate may also be used.
It is not limited to specific materials. Although the medium shape is disk-shaped as an example, it may also be card-shaped.
This is not limited to the embodiments.

[Effects of the Invention] The present invention has made it possible to provide an optical information recording medium on which small recording marks can be formed without complicating the manufacturing process.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of an optical information recording medium according to an embodiment of the present invention, FIG. 2 is a diagram showing a manufacturing process of an optical information recording medium according to an embodiment of the present invention, and FIG. FIG. 2 shows a schematic diagram of a recording mark in an embodiment of a conventional optical information recording medium. FIG. 4 is a diagram showing a schematic diagram of a recording film in a conventional multilayered medium structure. 101: Disc substrate, 102: Recording layer. 103 Nidoriger P +, 104 Nidorac guide groove,
io5: Record mark. lO5 Figure 1 Figure 2

Claims (3)

[Claims] (1) In an optical information recording medium in which information is recorded by forming spiral or concentric recording columns on a recording film formed by laminating at least two or more layers on a disk substrate, it is the closest to the disk substrate. An optical information recording medium characterized in that a recording column guide groove is formed in a layer. (2) The material of the layer closest to the disk substrate has a refractive index (N_1) equal to the refractive index (n_■) of the disk substrate.
The optical information recording medium according to claim 1, characterized in that the material is a material that satisfies the relationship n_1-n_■I/(n_1+n_■)<0.2. (3) The material of the layer closest to the disk substrate is an organic thin film, and the second layer is formed by sputtering In in a mixed gas of CH, O, and CF. The optical information recording medium according to claim 1 or 2.