JPH08273331A - Optical disc and its manufacture - Google Patents

Abstract

PURPOSE: To provide an optical disc which has a label with higher publicity effect suitable for mass production by simplifying a process for labeling. CONSTITUTION: In an optical disc, at least part of the areas on transparent disc base plates 11a and 11b are arranged as data recording areas to record data on the data recording area in a pit train while the two disc base plates are stuck together. In this optical disc, labeling areas are set in the areas other than the data recording areas on the respective disc base plates 11a and 11b to form label information as hologram patterns 15a and 15b of a surface relief type corresponding to the contents of the data recorded in the data recording areas in the label areas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and a method for manufacturing the same.

[0002]

2. Description of the Related Art Among optical disks, a read-only optical disk has a large storage capacity and can be mass-produced at low cost. Therefore, it is used as a compact disk (CD) for audio, a video disk on which video is recorded, and a read-only storage medium for a computer. It is widely used as a CD-ROM or the like. Recently, two discs with a diameter of 120 mm, which is the same as a CD, are placed on one side.
DVD (Digital Video Disc: Nikkei Electronics No.630, 1995, pp.94-100)
Etc.) are also being considered.

In these read-only optical disks, it is important to simply and effectively convey the content of the information (software) contained in the disk to the user or to appeal the content to the consumer. For that purpose, it is necessary to display software titles and the like in a form that is easily noticeable and easily understood by anyone. Also, these read-only optical disks cannot be put in a cartridge in many cases for the reason of suppressing the manufacturing cost. Therefore, not only for identifying the disc itself, but also for identifying the front and back sides of the disc, it is necessary to display some information directly on the disc in a visually recognizable form.

In a single-sided disc such as a CD, since the non-recording surface of the disc is empty, a label including a title or the like is printed on the non-recording surface side. FIG. 3A is a cross-sectional view showing an example of a single-sided optical disk such as a CD, which is a disk substrate 11 made of a transparent material such as polycarbonate.
The reflective film 12 and the protective film 14 are sequentially formed on the structure. The outer peripheral side of the disc is a data recording area, and the central portion is a clamp area and label area used when the optical disk is set in the reproducing apparatus.
6 is adhered or attached.

A double-sided disc such as a video disc has no empty surface, but the disc diameter is as large as 300 mm, and a relatively large unused area is left in the inner peripheral portion. Therefore, the above-mentioned demand has been met by directly printing a title or the like on this unused area or by attaching a separately printed label.

On the other hand, for a high-density optical disc called a DVD, which has been studied recently, a specification has been proposed in which the disc diameter is about the same as that of a CD and the disc is a double-sided disc.
FIG. 3B is a cross-sectional view showing an example of such a high-density double-sided optical disk. A reflective film 12 and a protective film 14 are sequentially formed on each of the disk substrates 11a and 11b made of a transparent material such as polycarbonate and the like, The structure is such that the film 12 side is placed inside and an adhesive layer 13 is used for bonding.
The outer peripheral side of the disc is a data recording area, and the central portion is a clamp area and label area used when the optical disk is set in the reproducing apparatus. Labels 16a, 16 are provided in this area.
b is adhered or attached.

In such an optical disc, since the recording area is made wider than before to increase the capacity, the unused area left in the inner peripheral portion is very small, and even characters are written very little. I can't.

Further, for example, when the information to be written is limited to only the title and is printed in this unused area, a printing step is included in the disc manufacturing process because of the characters at most, which is inefficient. Furthermore, depending on the type and content of the software, even a double-sided DVD actually uses only one side,
Alternatively, it is conceivable that one surface may be used only about half, and in such a case, it is possible to expand the printing area depending on the type of disk. However, in this case, it is necessary to change the printing area, which complicates the printing process, and is not efficient when mass-producing various kinds of disks. Further, even if the necessary contents can be written by printing, as long as the printing technique is used, only a flat image can be written on the surface of the disc, and it is difficult to obtain a higher PR effect than the conventional disc.

[0009]

As described above, in the conventional optical disc, the information about the contents of the disc is printed on the non-recording surface of the disc in the case of a CD, or in the vacant area of the inner circumference in the case of a video disc. Or it was displayed by attaching a label. However, double-sided DVD
When labeling a double-sided disc with a small diameter as in the above, the conventional method can print only a small number of characters in the limited area inside, making it difficult to read the display or providing only limited information. Further, since a printing process is provided for printing a small amount of labels, there is a problem that manufacturing efficiency is low.

In order to provide a label that is easy to see, some discs may be labeled on one side, or a part of one side (a wider area than a double-sided disc) may be labeled. In the case of production on a mass production line, it is necessary to change the printing area for each type of disc, which reduces mass production. In addition, since printing involves absorption of light, the color reproduction area is narrow, vivid colors are difficult to produce, and special visual effects such as changing the color depending on the viewing position cannot be produced. There was a problem that it was not.

An object of the present invention is to provide an optical disc equipped with a label having a high PR effect, which is suitable for mass production by simplifying the process for labeling.

Another object of the present invention is to provide a manufacturing method for such an optical disk, and in particular, a manufacturing method of a master used for manufacturing the optical disk.

[0013]

The optical disc of the present invention comprises:
The essence is that the label information indicating the content of the recorded data is formed as a holographic method, particularly as a surface relief type hologram pattern.

That is, the first optical disk according to the present invention is an optical disk in which at least a part of an area on a transparent disk substrate is used as a data recording area, and data is recorded as a pit string in this data recording area. A label area is set in an area other than the data recording area, and label information corresponding to the content of the data recorded in the data recording area is formed in the label area as a surface relief hologram pattern.

A second optical disk according to the present invention is such that at least a partial area on a transparent disk substrate is used as a data recording area, data is recorded as a pit row in this data recording area, and two disk substrates are used. In an optical disc formed by sticking together, a label area is set in an area other than the data recording area on the two disk substrates, and label information corresponding to the contents of the data recorded in the data recording area is provided on this label area. It is characterized in that it is formed as a mold hologram pattern.

A third optical disc according to the present invention is such that at least a part of a transparent disc substrate is used as a data recording region, data is recorded in this data recording region as a pit row, and two disc substrates are used. In the optical disc formed by bonding the two disc substrates, a label area is set on one of the two disc substrates, and the label area corresponds to the content of the data recorded in the data recording area on the other disc substrate. It is characterized in that the label information is formed as a surface relief type hologram pattern.

Here, the label information is information corresponding to the contents recorded in the data recording area, and is, for example, information such as characters, figures and images representing the contents of the information and the additional information accompanying it.

Further, in the method of manufacturing an optical disk according to the present invention, the first photoresist is applied to the entire surface of the disk substrate which is the master, and the portion corresponding to the data recording area of the first photoresist is exposed and exposed. After the photoresist of the portion corresponding to the label area is left by developing, the second photoresist is applied on the entire surface, and the portion of the second photoresist corresponding to the data area is recorded according to the data to be recorded. After exposing, and then hologram-exposing the portion corresponding to the label area of the second photoresist,
The method is characterized by including a step of producing a master by developing the second photoresist, and manufacturing the optical disc of any one of the first to third using the master.

In another method of manufacturing an optical disk according to the present invention, a first photoresist is applied to the entire surface of a disk substrate which is a master, and a portion of the first photoresist corresponding to a data recording area is exposed and exposed. After development, the photoresist of the portion corresponding to the label area is left, and then the first photoresist is applied only to the portion corresponding to the data recording area, and the portion corresponding to the data area of the second photoresist is applied. Exposing according to the data to be recorded, then hologram-exposing the portion corresponding to the label area of the first photoresist, and developing the master by developing the first and second photoresist, It is characterized in that any one of the first to third optical discs is manufactured using this master disc.

[0020]

In the optical disk according to the present invention, the hologram pattern, which is the label information, can be formed at the same time when the disk is molded, so that a printing step is not particularly required for the label information as in the conventional case. In particular, since the surface relief type hologram pattern hardly absorbs light, the spectral component contained in the illumination light for image reproduction can be effectively used and the color reproduction range is wide. Furthermore, it is possible to display a stereoscopic image by using a holographic method for the label information. Therefore, label information having a high PR effect can be provided.

Further, according to the optical disc manufacturing method of the present invention, an optical disc having such a surface relief type hologram pattern as label information can be simultaneously formed at the time of molding an optical disc having a pit string corresponding to data. A master disk can be provided.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are cross-sectional views of an optical disc according to an embodiment of the present invention. FIGS. 1A and 1B are examples of a double-sided disc, and FIG. 1C is an example of a single-sided disc. The left end of FIG. 1 corresponds to the outermost circumference of the disc, and the right end thereof corresponds to the innermost circumference.

First, the embodiment shown in FIG. 1A will be described. The optical disk of this embodiment has a structure in which a reflective film 12 and a protective film 14 are sequentially formed on each of disk substrates 11a and 11b made of a transparent material such as polycarbonate, and the reflective film 12 side is bonded to the inside by an adhesive layer 13. Has become. A data recording area is provided on the outer peripheral side of the disc, and a clamp area / label area used when the optical disc is set in the reproducing apparatus is provided at the center.

Then, on the inner surfaces of the substrates 11a and 11b, pit rows or continuous grooves corresponding to data such as video and audio information are formed in the data recording area, and the surface relief type having label information in the label area. Hologram patterns (hereinafter, simply referred to as hologram patterns) 15a and 15b are formed. Details of such a surface relief hologram method are described in, for example, "Holographic Display" (industrial books). In this embodiment, data is recorded on the entire surface of the data recording area on both sides of the disc, and the hologram patterns 15a and 15b are formed only on the inner non-recording area including the clamp area.

The optical disk shown in the embodiment of FIG. 1B is
Since the amount of recorded data is smaller than that of the optical disc of (a),
This is an example in which the data recording area on the substrate 11a is empty.
In this case, the empty portion of the data recording area can also be used as an area for label information. That is, in this embodiment, the hologram pattern 15c on the substrate 11a is formed wider than the hologram pattern 15d on the substrate 11b.

Next, the optical disk shown in the embodiment of FIG. 1 (c) is an example in which it is used as a single-sided disk, and the hologram pattern 15e is formed on the entire surface of the substrate 11a on which data is not recorded, and the substrate 11b is formed. An area other than the data recording area is used as a label area on the upper side of which a hologram pattern 15f is formed.

Next, an embodiment of a mastering process for mass-producing optical disks according to the present invention, that is, a mastering process will be described with reference to FIG. First, a glass disk 31 whose surface has been polished and washed is prepared as a master disk substrate (a), and a photoresist 32 is provided on the entire surface thereof.
Is applied (b).

An optical disk according to the present invention, in particular FIG. 1 (a)
In the double-sided disk shown in (b), the data recording area and the label area are present on the same surface of the disk at the same time, but the thickness of the photoresist to be applied is different in each of these areas. For optical discs, the thickness of the photoresist is usually 0.
The thickness is about 1 μm, but for holograms formed in the label area, a film thickness of at least twice that is required, usually about 1 μm is required. Therefore, in this embodiment, the photoresist is applied in two steps.

That is, in the step (b), the glass disk 3
A photoresist 32 is applied to the entire surface of 1 in a thickness corresponding to the difference in resist thickness between the data recording area and the hologram area. Next, the label area where the hologram is to be formed is masked by the light-shielding mask 33, only the data recording area is exposed (c), and further developed to remove the photoresist in the data recording area (d). The photoresist 32a remains only in the label area. Next, a photoresist 32b is applied again so that a resist having a required thickness is attached to the data recording area (e). Up to this point, a master having the required thickness of the photoresist coated thereon can be obtained.

Subsequently, using the master recording apparatus, intensity modulation (on / off) is performed according to the data to be recorded in the photoresist in the data recording area in order to form the data pit row and the groove.
The exposure light beam 34 that has been off-modulated is used for exposure (f). Next, a light shielding mask 33 is formed on the data recording area.
And the photoresist in the label area is exposed using the hologram exposure object light 35 and the hologram exposure reference light 36 (g). Thereafter, development processing is performed to complete the master (h). In this final development, the data recording area and the label area are processed at the same time, so it is necessary to optimize the development conditions.

As a comparative example, FIG. 4 shows a mastering process for producing a conventional master such as a CD. As shown at the same time, the mastering process according to the present invention is greatly different in that the photoresist coating process is performed only once.

As another embodiment of the mastering process of the optical disk according to the present invention, the thickness of the photoresist 32 formed first in the step (b) in the example of FIG. 2 is set to a thickness required for hologram recording. Alternatively, it is possible to perform hologram exposure of the label area after the developing step of (d) and apply the resist only to the data recording area when applying the photoresist 32b in the step of (e). The subsequent steps are the same as those in the embodiment shown in FIG.

In the case of this embodiment, only one layer of resist is required in the label area, and it is also possible to use a resist having optimized recording characteristics for hologram recording in the label area for forming a hologram. The characteristics such as the diffraction efficiency of the hologram can be improved as compared with the process of the above embodiment. However, in this case, an area having an uneven resist film thickness is formed near the inner peripheral edge of the photoresist 32b applied in the step (e), so that a margin is provided between the label area and the data recording area. It is necessary.

In order to manufacture the above-mentioned optical disk according to the present invention by using the master disk manufactured as described above, first, a stamper is formed from the master disk by an electroforming method or the like in the same manner as in the known manufacturing process of CD and the like. The pit row may be transferred to a resin substrate that serves as a replicar by injection molding or the like using the stamper, and then a reflective film made of aluminum or the like and a protective film may be formed. Further, when the optical disk is a double-sided optical disk, the disk substrates thus obtained may be bonded together.

[0035]

As described above, the optical disc according to the present invention is excellent in mass productivity because the label can be formed at the same time when the disc is molded by using the surface relief hologram as the label and the process can be simplified. Further, since good color reproducibility, color difference depending on the viewing position, and stereoscopic image display are possible, a high PR effect as a label can be obtained.

Further, according to the present invention, a master can be obtained which can be simultaneously formed at the time of molding an optical disk having a pit string corresponding to data, which has an optical disk having such a surface relief type hologram pattern as label information. Thus, the optical disc can be manufactured with high mass productivity.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an optical disc of the present invention.

FIG. 2 is a diagram showing an example of a mastering process according to the optical disc of the present invention.

FIG. 3 is a sectional view showing the structure of a conventional optical disc.

FIG. 4 is a diagram showing a mastering process for a conventional optical disc.

[Explanation of symbols]

11, 11a, 11b ... Disk substrate 12 ... Reflective film 13 ... Adhesive layer 14 ... Protective film 15a, 15b, 15c, 15d, 15e, 15f ... Surface relief hologram pattern 16, 16a, 16b ... Label 31 ... Glass disk 32, 32a, 32b ... Photoresist 33 ... Shading mask 34 ... Exposure light beam 35 ... Hologram exposure object light 36 ... Hologram exposure reference light

Claims (5)

[Claims] 1. An optical disc in which at least a part of a transparent disc substrate is used as a data recording region and data is recorded in the data recording region as a pit string, wherein a region other than the data recording region is labeled on the disc substrate. An optical disc, wherein an area is set and label information corresponding to the contents of data recorded in the data recording area is formed in the label area as a surface relief hologram pattern. 2. An optical disc in which at least a part of a transparent disc substrate is used as a data recording region, data is recorded as a pit row in this data recording region, and two disc substrates are bonded together. A label area is set in an area other than the data recording area on the two disk substrates, and label information corresponding to the content of the data recorded in the data recording area is formed in the label area as a surface relief hologram pattern. An optical disc characterized by being formed. 3. An optical disc in which at least a part of a transparent disc substrate is used as a data recording region, data is recorded as a pit row in this data recording region, and two disc substrates are bonded together. A label area is set on one of the two disk substrates, and label information corresponding to the content of the data recorded in the data recording area on the other disk substrate is provided in the label area on the surface relief type. An optical disc formed as a hologram pattern. 4. The method according to claim 1, wherein a master is used.
The method for manufacturing an optical disc as described in the item 1, wherein a first photoresist is applied to the entire surface of a disc substrate to be a master, and a portion of the first photoresist corresponding to the data recording area is exposed and developed. By this, the photoresist of the portion corresponding to the label area is left, and then the second photoresist is applied to the entire surface.
The portion of the photoresist corresponding to the data area is exposed according to the data to be recorded, and then the portion of the second photoresist corresponding to the label area is holographically exposed, and then the second photoresist is developed. A method of manufacturing an optical disc, comprising the step of producing the master by doing so. 5. The method according to claim 1, wherein a master is used.
The method for producing an optical disc as described in the item 1, wherein a first photoresist is applied to the entire surface of a disc substrate which is a master, and a portion of the first photoresist corresponding to the data recording area is exposed and developed. By doing so, the photoresist of the portion corresponding to the label area is left, and then the first photoresist is applied only to the portion corresponding to the data recording area to correspond to the data area of the second photoresist. The master is produced by exposing a portion according to the data to be recorded, then hologram-exposing the portion corresponding to the label area of the first photoresist, and then developing the first and second photoresists. A method for manufacturing an optical disc, comprising the steps of: