JPH0954985A - Optical disk and production of optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a less warped disk by forming translucent films on the one-side surfaces of two sheets of disk substrates having the rugged patterns meeting respective recording signals and reflection films on the other- side surfaces thereof and sticking these substrates to each other via a transparent material. SOLUTION: The disk substrates 11, 12 having the rugged patterns meeting the recording signals are formed respectively by an ordinary injection molding method. The translucent film layers 13 or the reflection layers 14 are formed on the respective one-side surfaces 11A, 12A of the resulted substrates 11, 12 and thereafter, the substrates 11, 12 are stuck to each other via the transparent film 15 in such a manner that the layers 13 and the layers 14 face each other via a prescribed distance L1 , by which the two-layered disk 10 is produced. As a result, approximately the same strength in the thickness direction of the substrates 11, 12 is obtd. and the less warped disk is obtd.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD The invention belongs to the related art (FIG. 6) Problem to be solved by the invention (FIG. 6) Means for solving the problem (FIGS. 1 to 4) Embodiment of the invention (1) First Example ( 1 to 2 and 5) (2) Second embodiment (Figs. 1 to 4 and 5) (3) Other embodiment (Figs. 1 to 4)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and a method for manufacturing the optical disc, and is particularly suitable for application to a two-layer optical disc.

[0003]

2. Description of the Related Art Conventionally, in this kind of optical disk,
As shown in FIG. 6, a reflectance of 30 is provided on one surface 2A of the disk substrate 2 made of a transparent resin such as polycarbonate.
Semi-transparent film layer 3 of about [%], transparent resin layer (spacer) 4 made of transparent resin, reflectance 90 made of aluminum or the like
It is formed by sequentially stacking the reflective film layer 5 and the protective film layer 6 made of an ultraviolet curable resin or the like in the order of [%].

In this case, an uneven pattern corresponding to a recording signal is formed on one surface 2A of the disk substrate 2 and the upper surface 4A of the transparent resin layer 4. Thus, in this kind of optical disk 1, by irradiating the light beam from the other surface 2B side of the disk substrate 2 to one surface 2A of the disk substrate 2 (hereinafter, referred to as the first signal surface), the light beam is focused. While the information recorded on the first signal surface 2A can be reproduced based on the reflected return light, the upper surface 4A of the transparent resin layer 4 from the other surface 2B side of the disk substrate 2 (hereinafter referred to as the second The signal recorded on the second signal surface 4A can be reproduced based on the return of the reflected light by irradiating the light beam with a focus on the signal surface).

[0005]

By the way, this kind of optical disk 1 is usually manufactured by the following procedure.
That is, first, the disk substrate 2 is prepared by the in-molding method, and a silicon material or the like is deposited on the upper surface 2A of the disk substrate 2 by the spattering method at 500 to 600 [Å]
The semitransparent film layer 3 is formed by depositing the semitransparent film layer 3.

Subsequently, the transparent resin layer 4 is formed on the semitransparent film layer 3 by applying a UV curable resin by a spin coating method to such an extent that a predetermined signal surface distance defined by the regulation can be obtained. A second signal surface is formed by pressing a stamper against the upper surface 4A of the transparent resin layer 4 and then curing the transparent resin layer 4 with ultraviolet rays. Further, aluminum is deposited on the second signal surface by a sputtering method to a thickness of about 500 to 800 [Å] to form a reflection film layer 5, and then an ultraviolet curing resin is applied on the reflection film layer 5 to remove the ultraviolet rays. The protective film layer 6 is formed by ultraviolet curing the resin. As a result, the two-layer optical disc 1 as described above can be obtained.

However, in such a conventional method for manufacturing a two-layer optical disk, the manufacturing process is complicated because the second signal surface is formed by the so-called 2P method as described above.
Therefore, there was a problem of poor production efficiency. Further, in the conventional method for manufacturing a two-layer optical disc as described above, the disc substrate 2
Since the ultraviolet curable resin is applied and cured on one side of the resin a plurality of times, there is a problem that the manufactured two-layer optical disc 1 is likely to be warped due to curing contraction which is a characteristic of this resin. .

The present invention has been made in consideration of the above points, and an object thereof is to propose an optical disk having less warp and an optical disk manufacturing method capable of efficiently manufacturing the optical disk.

[0009]

In order to solve such a problem, in the present invention, a semi-transparent substance is formed on one surface of a first disk substrate made of a transparent resin material having an uneven pattern corresponding to a recording signal formed on one surface. And a reflective film layer made of a light-reflecting material are laminated on the one surface of the second disk substrate having a concavo-convex pattern according to a recording signal formed on the one surface. An optical disk was formed by bonding the second disk substrate through a bonding means made of a transparent material.

One surface of the first disk substrate acts as a first signal surface of the optical disk, and one surface of the second disk substrate acts as a second signal surface of the optical disk. Accordingly, in the optical disc thus formed, a semitransparent film layer or a reflective film layer is formed by irradiating a light beam from the other surface side of the first disk substrate while focusing on the first or second signal surface. The signals recorded on the first and second signal surfaces can be reproduced based on the reflected return light reflected and returned at.

In this case, this optical disk is composed of the first and second optical disks.
The strengths in the thickness direction of the first and second disk substrates can be made approximately the same by selecting the material and thickness of the disk substrate. Further, this optical disk is manufactured by, for example, manufacturing the optical disk by bonding the first and second disk substrates, which are separately formed, through a bonding means made of a transparent material.
It can be manufactured without using a complicated construction method such as the P method.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 10 indicates a two-layer optical disk according to the first embodiment as a whole, and first and second surfaces 11A and 12A are provided with a concavo-convex pattern corresponding to a recording signal. The second disk substrates 11 and 12 are attached to the respective surfaces 11A and 12
It is formed by laminating A so as to face each other through a transparent film 15. In this case, a semi-transparent film layer 13 made of a semi-transparent material is laminated on one surface 11A of the first disk substrate 11, and a reflective film layer 1 made of a reflective material is formed on one surface 12A of the second disk substrate 12.
4 are laminated.

As a result, in the two-layer optical disc 10, by irradiating a light beam from the other surface 11B side of the first disk substrate 11 to the one surface 11A thereof, the reflected return light obtained at this time is reflected. Based on the first
The signal recorded on one surface 11A of the disk substrate 11 can be reproduced and the other surface 11B of the first disk substrate 11 can be reproduced.
The signal recorded on the one surface 12A of the second disk substrate 12 is reproduced on the basis of the reflected return light obtained by irradiating the light beam with the one surface 12A of the second disk substrate 12 focused from the side. It is designed to be able to do.

Here, in practice, this two-layer optical disk can be manufactured by the following procedure. That is, first, by using a transparent resin material such as polycarbonate, a first disk substrate 11 having a predetermined thickness (usually 1.2 [mm]) having a concavo-convex pattern corresponding to a recording signal on one surface 11A is formed by a normal intrusion molding method. create. Separately from this, a second disk substrate 12 having an appropriate thickness and having a concavo-convex pattern corresponding to a recording signal on one surface 12A is formed by using an appropriate material (not necessary to consider the light transmittance). Created by the molding method.

Next, one surface 11 of the first disk substrate 11
A semitransparent film layer 13 having a reflectance of about 30% is deposited on A (corresponding to the first signal surface of the two-layer optical disk 10) by using a sputtering method by depositing a semiconductor such as metal or silicon. Is formed with a thickness of about 500 to 600 [Å]. Separately from this, one surface 1 of the second disk substrate 12
2A (corresponding to the second signal surface of this two-layer optical disc 10)
The reflection film layer 14 having a reflectance of about 90% is formed on the upper surface by depositing aluminum or the like by using the sputtering method.
It is formed with a thickness of 0 to 800 [Å].

Thereafter, the first and second disk substrates 11,
12 so that each one surface 11A, 12A of the first and second disk substrates 11, 12 can maintain a predetermined signal surface distance L ₁ (usually about 40 to 50 [μm]) defined by the standard. , A transparent film 15 having a predetermined thickness is attached. Thereby, the two-layer optical disk 10 as shown in FIG. 1 can be obtained.

In this case, the two-layer optical disk 10 manufactured by such a method is obtained by laminating the first and second disk substrates 11 and 12 which are prepared by the usual intrusion molding method as described above. As shown in FIG. 2, since the pits P1 and P2 on the first and second signal surfaces are both concave (that is, the first
The signal surface pit P ₁ has a concave shape when viewed from the one surface 11A side of the first disk substrate 11, and the second signal surface pit P ₂ is viewed from the one surface 12A side of the second disk substrate 12. It becomes concave).

Therefore, in the two-layer optical disk 10, the signal recorded on the one surface 11A of the first disk substrate 11 is reproduced normally, and the signal recorded on the one surface 12A of the second disk substrate 12 is reproduced. Reproduction is performed by performing signal processing such as inverting the reproduction signal. Further, as is clear from FIG. 2, the two-layer optical disk 10 manufactured by such a method originally has the same width W ₁
Of the pit P _1, P ₂ even better the pit P ₂ of the second signal surface, pit width W ₂ than the pit P ₁ of the first signal plane as viewed from the other surface 11B side of the first disc substrate 11 Is reduced by twice the film thickness W ₃ of the reflective film layer 14.

Therefore, when the two-layer optical disk 10 is manufactured by the manufacturing method as described above, the size of the pit P ₂ of the second disk substrate 12 is set to the size corresponding to that of the first disk substrate 11. Each pit P ₂ is formed so that the pit width W ₂ is larger than the pit P ₁ by twice the film thickness W ₃ of the reflective film layer 14. This makes it possible to manufacture the two-layer optical disc 10 having the same reproduction characteristic on the first signal surface and reproduction characteristic on the second signal surface.

In the above-mentioned structure, the first and second disk substrates 11 and 12 each having a concavo-convex pattern corresponding to a recording signal are produced by a normal injection molding method, and the first and second thus obtained. After forming the semitransparent film layer 13 or the reflective film layer 14 on the respective surfaces 11A and 12A of the disk substrates 11 and 12, respectively, the first and second disk substrates 11 and 12 are formed on the semitransparent film layer 13 respectively.
And the reflective film layer 14 and the transparent film 15 so as to face each other with a predetermined distance L ₁ therebetween.
The layered optical disk 10 is manufactured.

Therefore, according to the method for manufacturing the two-layer optical disk as described above, the two-layer optical disk can be manufactured by using only the injection molding method, so that the work such as the conventional 2P method is complicated. It is possible to manufacture the two-layer optical disk easily and at low cost as compared with the case of using a different construction method.

Further, according to such a method for manufacturing a two-layer optical disk, the transparent film 1 is provided with the first and second disk substrates 11 and 12 each having a certain strength in the thickness direction.
5, the first and second disk substrates 11 and 12 are made to have substantially the same strength in the thickness direction by selecting the materials and thicknesses of the first and second disk substrates 11 and 12. be able to. Therefore, it is difficult to warp 2
The layered optical disc 10 can be manufactured.

According to the above construction, the first and second disk substrates 11 and 12 each having the concavo-convex pattern corresponding to the recording signal are produced by the normal intrusion molding method, and the first and second thus obtained. After the semitransparent film layer 13 or the reflective film layer 14 is formed on the surfaces 11A and 12A of the two disk substrates 11 and 12, respectively, the first and second disk substrates 11 and 12 are attached to the surfaces 11A and 11A, respectively.
By 12A each other was to produce a 2-layer optical disc 10 as bonded via the transparent film 15 so as to face each other with a predetermined distance L _1, a conventional two-layer optical disc using a 2P method 1 The two-layer optical disk 10 can be manufactured more easily than the manufacturing method of FIG. 6 and the two-layer optical disk 10 is less likely to warp than the conventional two-layer optical disk 1 (FIG. 6). Thus, it is possible to realize the two-layer optical disk with less warp and the optical disk manufacturing method capable of efficiently manufacturing the two-layer optical disk.

(2) Second Embodiment FIG. 3 in which parts corresponding to those in FIG.
The two-layer optical disk 20 according to the embodiment is shown, and is formed in substantially the same manner as the two-layer optical disk 10 (FIG. 1) of the first embodiment except the configuration of the second disk substrate 21. That is, in the case of this two-layer optical disk 20, the second disk substrate 21
Pits P ₃ of each are formed in a convex shape (that is, pits P 3
₃ has a shape protruding from the one surface 21A side of the second disk substrate 21). As a result, in this two-layer optical disk 20, one surface 21 of the second disk substrate 21 is
The signal recorded in A can be reproduced normally without performing signal processing such as inversion.

Here, in practice, this second disk substrate 21 is used.
A disk substrate having a convex pit shape as shown in FIG.
It can be created by the following procedure shown in (F).
That is, first, in the same manner as in the case of forming a normal optical disk stamper, a resist layer 31 is formed by applying a photo resist on one surface 30A of the glass substrate 30 that has been polished to be extremely smooth (FIG. 3). (A)) After exposing the resist layer 31 according to a recording signal, the resist layer 31 is developed to develop the residual resist 31 on the glass substrate 30.
A concavo-convex pattern corresponding to the recording signal of A is formed (FIG. 3B).

Subsequently, a conductive film layer (hereinafter referred to as a conductive film layer) is formed on the surface of the uneven pattern made of the residual resist 31A by a method such as electroless plating, and then this conductive film is formed. A plating layer is formed on the layer by plating nickel using a method such as electroforming to a required thickness. Further, the conductive film layer and the plating layer are integrally peeled from the glass substrate 30 and the remaining resist 31A to form a stamper 32 having a convex pit shape (FIG. 3C), and then based on the stamper 32. A stamper 33 having a concave pit shape is formed (see FIG. 3).
(D) and (E)).

After this, a disk substrate is prepared by the intrusion molding method using the stamper 33. This makes it possible to form the second disk substrate 21 having the convex shape of the pit P ₃ as described above (FIG. 3 (F)).

In the above structure, in the two-layer optical disk 10 (FIG. 1) of the first embodiment, the pit-shaped irregularities are different between the first signal surface and the second signal surface. However, in the reproducing apparatus using the push-pull method, it is necessary to invert the tracking signals on the first signal surface and the second signal surface during the tracking servo.

If this is not done, this is the second or first
This is because the tracking servo is performed when the optical beam spot is moving in the center of two adjacent tracks when the signal surface of is reproduced and the tracking servo is performed. Example 2-layer optical disk 1
0 (FIG. 1) requires that the tracking signal be inverted when reproducing the signal recorded on the first signal surface and when reproducing the signal recorded on the second signal surface. However, there is a problem that the configuration of the signal processing circuit is complicated.

However, as in the second embodiment, the two-layer optical disk 20 is formed by bonding the first disk substrate 11 having a concave pit shape and the second disk substrate 21 having a convex pit shape. By forming the signal, the signal recorded on the first signal surface is reproduced at the time of reproduction
It is possible to avoid the need to invert the tracking signal at the time of reproducing the signal recorded on the signal surface, and thus to prevent the signal processing circuit of the reproducing device from becoming complicated.

According to the above construction, the first disk substrate 11 made of transparent resin having a concave pit shape and the second disk substrate 21 having a convex pit shape are provided on one surface 11A, respectively.
By forming the two-layer optical disc 20 by laminating the 21A with the transparent film 15 so as to face each other with a predetermined distance L ₁ therebetween, the warp is small and the signal processing circuit of the reproducing apparatus is formed. It is possible to realize a two-layer optical disk that can prevent the complication of the above and a method for manufacturing the optical disk that can efficiently manufacture the two-layer optical disk.

(3) Other Embodiments In the above-described first and second embodiments, the case where the first and second disk substrates 11, 12 (or 21) are formed by the injection molding method is described. Although described, the present invention is not limited to this, and various other manufacturing methods can be applied as the manufacturing method of the first and second disk substrates 11 and 12 (or 21).

In the first and second embodiments described above, the first and second disk substrates 11 and 12 (or 2) are used.
Transparent film 15 is used as a bonding means for bonding 1).
However, the present invention is not limited to this, and instead of the transparent film 15, for example, a light-transmitting ultraviolet curable resin or an adhesive is used to form the first and second disk substrates 11, 12 (or 21) may be attached to each other. The point is that the first and second disk substrates 1 are attached.
As long as 1, 12 (or 21) can be bonded, various bonding means other than this can be applied as the bonding means.

Further, in the above-described first and second embodiments, a semiconductor such as metal or silicon is deposited on the one surface 11A of the first disk substrate 11 by the sputtering method so that the reflectance is about 30%. Transparent film layer 15
The reflective film layer 14 is formed to have a thickness of about 500 to 600 [Å], and aluminum is deposited on the one surface 12A, 21A of the second disk substrate 12, 14 by the sputtering method to have a reflectance of about 90%. From 500 to 800
Although the case where the film is formed with a thickness of about [Å] is described, the present invention is not limited to this, and the thickness, the material, the forming method, and the reflectance of the semitransparent film layer 13 and the reflective film layer 14 are other than the above. It may be.

Further, in the above-mentioned first and second embodiments, the case where the present invention is applied to the two-layer optical disk and the manufacturing process thereof has been described, but the present invention is not limited to this, and the signal surface is It can also be applied to a normal optical disk having only one and its manufacturing process. That is, for example, as shown in FIG. 5, a reflective film layer 42 made of aluminum or the like is laminated on the one surface 41A of a disk substrate 41 having an uneven pattern according to a recording signal formed on the one surface 41A, and the reflective film layer is formed. The optical disc 40 may be formed by bonding a thin transparent film 44 having a thickness of 0.5 [mm] or less to 42 via a transparent substance (for example, a light-transmissive adhesive 43).

[0037]

As described above, according to the present invention, a semitransparent semitransparent film layer is formed on one surface of a first disk substrate made of a transparent resin material having an uneven pattern formed on one surface in accordance with a recording signal. And a reflective film layer is laminated on the one surface of the second disk substrate having a concave-convex pattern formed according to a recording signal on one surface, and the first and second disk substrates are transparent on one surface. Since the optical discs are manufactured so that the optical discs are laminated so as to face each other via the laminating means made of a substance, the strengths in the thickness direction of the first and second disc substrates can be made approximately the same. At the same time, it is possible to manufacture without using a complicated construction method, and thus it is possible to realize an optical disk with less warp and an optical disk manufacturing method capable of efficiently manufacturing the optical disk.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a two-layer optical disk according to a first embodiment.

2 is a schematic cross-sectional view showing a pit shape of first and second signal surfaces in the two-layer optical disc of FIG.

FIG. 3 is a sectional view showing the structure of a two-layer optical disk according to a second embodiment.

FIG. 4 is a cross-sectional view showing a procedure for producing a second disk substrate.

FIG. 5 is a sectional view showing another embodiment.

FIG. 6 is a cross-sectional view showing a configuration of a conventional two-layer optical disc.

[Explanation of symbols]

20,30 …… 2 layer optical disk, 11,12,21 ……
Disk substrate, 11A, 12A, 21A ... One side, 13
...... Semi-transparent film layer, 14 ...... Reflective film layer, 15 ...... Light transmissive film, P ₁ , P ₂ , P ₃ ...... pit.

Claims (6)

[Claims] 1. A first disk substrate made of a transparent resin material having a concavo-convex pattern formed on one surface according to a recording signal, and a semi-transparent material laminated on the one surface of the first disk substrate. A transparent film layer, and a second surface having an uneven pattern corresponding to a recording signal formed on one surface.
Disk substrate, a reflective film layer made of a light reflective material laminated on the one surface of the second disk substrate, and the first and the first and second transparent film layers disposed between the semitransparent film layer and the reflective film layer. An optical disk comprising: a bonding means made of a transparent material for bonding the two disk substrates together. 2. The pits of the first and second disk substrates are concave, and the pits of the second disk substrate are larger than the pits of the corresponding size of the first disk substrate. 2. The optical disc according to claim 1, wherein the pit width is selected to be as large as twice the film thickness of the reflective film layer. 3. The optical disk according to claim 1, wherein the first disk substrate has concave pits, and the second disk substrate has convex pits. 4. A first disk substrate made of a transparent resin material having a concavo-convex pattern according to a recording signal on one surface, and a second disk substrate having a concavo-convex pattern according to a recording signal on one surface. 1), forming a semitransparent film layer made of a semitransparent material on the one surface of the first disk substrate, and forming a reflective film layer made of a light reflecting material on the one surface of the second disk substrate. A second step of forming and a third step of bonding the first and second disk substrates through a bonding means made of a transparent material so that the one surfaces face each other with a predetermined distance therebetween. A method for manufacturing an optical disc, which comprises: 5. The pits of each of the first and second disk substrates are concave, and the pits of the second disk substrate are larger than the pits of the corresponding size of the first disk substrate. 5. The method of manufacturing an optical disk according to claim 4, wherein the pit width is selected to be as large as twice the film thickness of the reflective film layer. 6. The method of manufacturing an optical disk according to claim 4, wherein the first disk substrate has concave pits, and the second disk substrate has convex pits. .