JPH08297859A - Optical disk - Google Patents

Abstract

PURPOSE: To effectively evade deformation compared with the case when two pieces of thin optical disk bodies are stuck by sticking the thin and easy to be deformed optical disk body with a thick and hard to be deformed optical disk body. CONSTITUTION: Reflection films are formed on signal patterns 3a, 3b in respective optical disk bodies 1a, 1b similarly to a usual optical disk body. Then, these optical disk bodies 1a, 1b are stuck through adhesives 5, and an optical disk 1 constituted so that the optical disk body 1b of a thickness of e.g. 0.6mm is stuck with the optical disk body 1a of the thickness of 1.2m is formed. In such a case, the optical disk of less deformation after stuck is obtained compared with the case when two pieces of the optical disk bodies of the thickness of 0.6mm are stuck.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to optical discs such as compact discs (CDs), digital video discs (DVDs) and the like.

[0002]

2. Description of the Related Art Optical discs capable of reading information by optical means include compact discs (CD), magneto-optical discs (MO), digital video discs (DV).
D) and the like, and are classified into a read-only optical disc for recording various information in advance and used only for reproduction, and a writable optical disc for reproducing recorded information and recording information.

For example, a reproduction-only optical disc on which various information such as voice, music, video and data is recorded, for example, a CD
As shown in the cross-sectional configuration diagram of FIG. 3, a groove or a pit formed in accordance with recorded information is formed on one surface of the disk substrate 12 made of a light-transmissive glass substrate, PC (polycarbonate) substrate, or the like. An optical disc 1 having a signal pattern 13 formed thereon, and a reflective film 14 made of, for example, an Al vapor deposition film and a protective film 15 for protecting the reflective film 14 formed on the signal pattern 13 by coating.
It consists of 1.

Disk substrate 1 having signal pattern 13
2 is injection-molded by, for example, an injection molding machine in which a stamper having an uneven pattern in which the unevenness of the signal pattern 13 is inverted corresponding to the signal pattern 13 is arranged in the cavity.

The thickness of the disc substrate 12 of this optical disc, for example, an ordinary CD, is selected to be 1.2 mm.

[0006]

By the way, due to the demand for higher recording density and higher recording capacity of optical discs, especially DVDs, as shown in FIG. 4 as a schematic sectional view thereof,
An optical disk 21 having a structure in which two optical disk bodies 11a and 11b are bonded to each other, each of which has an information recording surface, that is, a signal pattern and is selected to have a thin thickness of 0.6 mm, has been proposed. ing.

However, as described above, the thickness is 0.6 mm.
When a thin disk substrate is manufactured, deformation is likely to occur, so even if two thin disk substrates are bonded together, the two disk substrates still have deformation and a recording / playback error occurs. There's a problem.

On the other hand, the normal C having a thickness of 1.2 mm described above.
Even in D, the selection of this thickness does not cause a problem such as deformation in a normal environment, that is, humidity and temperature.
As described above in (1), it is required that even a weak deformation of the disk be avoided as much as possible as the information recording density becomes higher. However, as shown in FIG. However, since it is formed on only one surface of the disk substrate 12 on which the signal pattern is formed, there is a possibility of weak deformation when a rapid temperature change is given.

In the present invention, as described above, even when a thin disk substrate of, for example, 0.6 mm is used,
(EN) An optical disc capable of surely avoiding deformation and, at the same time, effectively avoiding even weak deformation even in a disk substrate having a thickness of 1.2 mm.

[0010]

The optical disc according to the present invention has a structure in which two optical disc bodies having different thicknesses are bonded together.

[0011]

As described above, even in the case of two optical disc bodies having different thicknesses, that is, a thin optical disc body having a thickness of 0.6 mm, an optical disc body having a thickness larger than this, for example, 1.2 mm is bonded. As a result, the deformation is suppressed or corrected.

Further, even for an optical disc body having a thickness of 1.2 mm, for example, as compared with an optical disc made of a single optical disc body, the weak deformation described above is caused by bonding other optical disc bodies. Effectively suppressed.

[0013]

The typical construction of an optical disc according to the present invention is as follows:
Optical disc body with a thickness of 1.2 mm and 0.6 mm
And an optical disc body having the above thickness are bonded together to form an optical disc.

A method of manufacturing an optical disk according to the present invention will be described below with reference to the drawings.

As shown in a schematic sectional view of one optical disc body in FIG. 2A, the disc substrate 2a is made of a light transmissive resin, for example, a polycarbonate resin, and a signal pattern 3a is formed by a concavo-convex pattern formed according to various information. An optical disc body 1a having a disc thickness of 1.2 mm is formed.

This optical disk body is manufactured by an injection molding method or the like using a stamper having a concavo-convex pattern formed corresponding to the above-mentioned signal pattern.

Further, as shown in the schematic sectional view of the other optical disc body in FIG. 2B, the disc substrate 2b is made of a light transmissive resin, for example, a polycarbonate resin, and the signal pattern 3b is formed by a concavo-convex pattern. An optical disc body 1b having a thickness of 0.6 mm is produced. The optical disc body 1b can be manufactured by the same method as in the case of the optical disc body 1a.

The respective optical disk bodies 1a and 1b are
Similar to the ordinary optical disc shown in FIG. 3, a reflection film (not shown) is formed on the signal patterns 3a and 3b.

These optical disk bodies 1a and 1b are bonded together with an adhesive 5 as shown in the schematic sectional view of FIG.

In this way, the optical disc body 1b having a thickness of 0.6 mm and the optical disc body 1 having a thickness of 1.2 mm are provided.
The optical disc 1 formed by laminating a and a is formed.

As described above, the thickness of 0.6 mm which is easily deformed
The optical disc body 1b of 1. has a thickness of 1.
By bonding with the 2 mm optical disc body 1a, the bonding can be performed as compared with the case where the optical disc body has a thickness of 0.6 mm alone and the case where two optical disc bodies having a thickness of 0.6 mm are bonded. It became an optical disc with little deformation after it was burned.

In the above-mentioned embodiment, the disc substrates 2a and 2b of the two optical disc bodies 1a and 1b are made of polycarbonate resin, but the disc substrates 2a and 2b of the two optical discs are made of different materials. For example, polycarbonate resin and PMMA (polymethylmethanoacrylate) may be used, and in that case, the same effect that the deformation of the disk is reduced can be obtained. Further, the material of the disk substrate is not limited to the above-mentioned polycarbonate resin and PMMA, but other glass or transparent resin can be used.

Further, in the above-mentioned embodiment, the two optical disk bodies 1a and 1b are both provided with the signal patterns 3a and 3b.
However, one of the optical disc bodies 1a and 1b may be a so-called dummy disc in which no signal is present, and only one side may be readable. Even in this case, the effect of reducing the deformation of the optical disc can be obtained.

In the above embodiment, the thickness of the optical disk body to be bonded is 0.6 mm and 1.2 m, respectively.
However, the thickness is not limited to these values, and in other cases, as in the above-described embodiment, by bonding two optical disks having different thicknesses, high strength can be obtained. It is possible to make an optical disc with little deformation.

The bonded optical disc according to the present invention comprises:
The present invention is not limited to the above-described embodiment, and various other configurations can be adopted without departing from the gist of the present invention.

In the above-mentioned embodiment, the optical disk has a structure for reproduction having irregularities. However, for example, an optical disk having a multilayer film structure such as a magnetic layer used in a magneto-optical disk or the like is used. The present invention can be similarly applied to a disc body, and in the same manner, a recordable / rewritable optical disc with little deformation can be manufactured.

[0027]

As described above, the optical disc according to the present invention has a thin optical disc body which is easily deformed and a thick optical disc body which is hard to be deformed, so that two thin optical disc bodies are bonded to each other. Thus, the deformation after pasting can be effectively avoided. Therefore, it is possible to obtain a disk having better dimensional stability against changes in temperature and humidity.

Since the disk has good dimensional stability, the reproduction position is less likely to shift due to deformation, and accurate reproduction can be performed. As a result, even if the interval between the signal patterns is narrowed, a reproduction error does not occur, and the recording capacity of the optical disc is doubled, and the recording density of the optical disk can be further improved.

By further adhering two optical disk bodies together, signals of different formats can be recorded to form an optical disk.

Therefore, reproduction is possible even in a plurality of devices which reproduce in two different formats.
That is, it can be a compatible optical disc.

It is also possible to adopt two reproducing means in a single reproducing device to form an optical disc which reproduces different kinds of signals such as audio and video from the respective discs.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an example of a bonded optical disc according to the present invention.

FIG. 2A is an optical disc body having a thickness of 1.2 mm. B An optical disc body having a thickness of 0.6 mm.

FIG. 3 is a cross-sectional configuration diagram of an optical disc (CD).

FIG. 4 is a schematic sectional view of a conventional bonded optical disc.

[Explanation of symbols]

 1, 11, 21 Optical disc 1a, 1b Optical disc body 2a, 2b Disc substrate 3a, 3b Signal pattern 5, 22 Adhesive material 11a, 11b Optical disc body 12 Disc substrate 13 Signal pattern 14 Reflective film 15 Protective film

Claims (2)

[Claims] 1. An optical disk comprising two optical disk bodies having different thicknesses bonded together. 2. The two optical disc bodies have a length of 1.2 m.
The optical disc according to claim 1, which is an optical disc having a thickness of m and an optical disc having a thickness of 0.6 mm.