JPH09167381A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk having excellent mechanical characteristics by providing this disk with a joint layer consisting of a transparent oxide-based inorg. dielectric material between a translucent layer and substrates or adhesive layer holding this translucent layer in-between, thereby intensifying the strength of adhesion and preventing peeling thereof. SOLUTION: The substrates 11, 12 of a two-layers laminated disk for reproducing one side consist of org. materials and a perfect reflection layer 16 of Al are formed on the substrate. A translucent layer 17 consisting of Au and further, a joint layer 19 consisting of SiO2 are formed. The substrates 12 and 11 are superposed on each other in such a manner that the perfect reflection layer 16 and the joint layer 19 face each other and are cured and adhered with a UV (UV curing) resin. The disk is irradiated with a light beam from the substrate 11 side and the light beam is focused at the translucent layer 17 or the perfect reflection layer 16. The information of the focused layer is then read. The strength of adhesion of the optical disk liable to peel at the respective boundaries is intensified by providing the disk with the joint layer. The optical disk free from problems in practicable use is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc in which an information signal such as an address and a header and a moving image information signal such as a video are formed in advance as embossed prepits on a surface thereof with a predetermined gap. The present invention relates to an optical disc used in a method of laminating or laminating a plurality of substrates, irradiating a light beam such as a laser beam from one substrate side, reading the change in the reflected light amount, and reproducing.

[0002]

2. Description of the Related Art In recent years, with the increase in capacity of information, an optical disk has been attracting attention as a memory for storing the information. C
Read-only optical discs represented by D, CD-ROMs, and LDs are widely known as well-known facts. However, with the recent increase in density, embossed optical discs written on these optical discs have been developed. The density of pit information is also increasing.

For example, according to the recently announced SD (Super Density) disc standard, the capacity of a double-sided laminated reproduction disc in which substrates of 0.6 mm thickness are laminated on both sides is 10 GB. The capacity of 5 GB on one side is MPEG (Moving Pict).
When moving image compression of the ure Expert Group) standard is performed, a 135-minute movie (moving image) can be recorded.

On the other hand, according to the SD standard, in order to eliminate the complexity that the back side cannot be reproduced unless the disc is turned inside out, a bonded disc as shown in FIG. 5 has been proposed. That is, when two discs 21 and 22 are bonded together through a very thin transparent adhesive layer 25 and the embossed pits 23 of the disc 21 are desired to be reproduced, a light beam 28 is emitted from the substrate side of the disc 21 and the focus thereof is focused. To the surface of the disc 21, and
When you want to play the embossed pit 24 of 2,
A light beam 28 ′ is emitted from the substrate side of the disk 21 and its focus is adjusted to the surface of the disk 22. In this case, in order to obtain the reflected light from both the disk 21 and the disk 22, as shown in FIG. 6, the focus surface of the light beam of the disk 21 has a layer for recording information together with the embossed pit 23. A semi-transparent layer 27 is required to be formed, and the focus surface of the disk 22 is required to be provided with the embossed pits 24 and the complete reflection layer 26 which is a layer for recording information. By doing so, when the light beam 28 is focused on the surface of the semitransparent layer 27, reflected light 29 from the surface 27 is obtained, and when focused on the completely reflective layer 26, the light from the surface 26 is reflected. The reflected light 30 is obtained.

It should be noted that the thickness d of the transparent adhesive layer 25 is set so that the operating range (working distance) of an objective lens actuator (not shown) or the light reflected from a surface other than the focused surface is reflected from the focused surface. It is set to a value that does not disturb the light. That is, the adhesive layer 2
The thickness d of 5 is based on the relationship with the wavelength of the light beam used,
When the reflected light 29 from the semi-transparent layer 27 is viewed, the reflected light 30 becomes weaker, and when the reflected light 30 from the completely reflective layer 26 is viewed, the reflected light 29 becomes weaker. ˜50 μm, SD standard 40 μm. If the reflectance of the semi-transparent layer 27 is too high, less light will pass through, and the reflected light 30 from the perfect reflection layer 26 cannot be obtained. Conversely, the reflectance of the semi-transparent layer 27 will be too low. Since the reflected light 29 from the layer 27 becomes small, it is usually 25 to 50.
%, The appropriate value is set to 35%.

The material of the transparent adhesive layer 25 is, for example,
Ultraviolet (UV) curable resin, hot melt resin, double-sided adhesive tape without a base material, etc.
In order to maintain the thickness of m over the entire surface of the disc, UV
Resin and double-sided tape are suitable. In addition, the semi-transparent layer 27
Usually, gold (Au) or copper (Cu) is used as the material of the, and its thickness is set to 50 to 300 # in order to make the reflectance 25 to 50%.

[0007]

However, in such a two-layer optical disc which is reproduced from one side,
There were the following disadvantages. That is, with respect to the two reflective layers (semi-transparent layer 27 and complete reflective layer 26), information can be reproduced by irradiating the light beam 28 from only one surface and receiving the reflected light so that information can be reproduced. Beam 2
The reflective layer (semi-transparent layer 2
7) must be a semitransparent layer, and the problem can be solved by reducing the layer thickness of the reflective layer. In that case, the semitransparent layer 27 is formed too thin. Therefore, the interface 27 between the adhesive layer 25 and the semitransparent layer 27
The adhesive strength of the interface a of the disk a and the disk substrate 21 and the semitransparent layer 27 was weak, and the two disks were easily peeled off. Alternatively, there is a drawback that even if they can be adhered once, they will come off during long-term storage or accelerated deterioration test of high temperature and high humidity.

[0008] Such a problem is not limited to the case where the optical disc is composed of only two reflective layers, but a plurality of optical discs used for reproducing information from several reflective layers from one surface is used. The same problem occurs, of course, in the optical disc formed by laminating the optical discs described above as one optical disc, and in the optical disc manufactured by laminating a plurality of reflective layers while inserting an intermediate layer or the like.

The present invention has been made to solve these problems of the prior art, and its object is to reduce the thickness of the layer to make it semitransparent. The semi-transparent layer and the weakened adhesive strength between the substrate and the adhesive layer provided in contact with the semi-transparent layer are reinforced, their peeling is prevented, and the mechanical properties are excellent.
It is intended to provide an optical disc.

[0010]

In order to achieve the above object, an optical disc according to the present invention is a layer having good adhesion between a semitransparent layer and a substrate or an adhesive layer sandwiching the semitransparent layer. For example, a bonding layer made of a transparent inorganic dielectric material such as SiO2 is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a first embodiment of the present invention and shows a double-sided bonded single-sided reproducing dual-layer disc having two reflective layers (semi-transparent layer and complete reflective layer). The substrates 11 and 12 each have a diameter of 120 mm
It is a substrate made of an organic material such as polycarbonate and having a thickness of 0.6 mm. Normally, according to the SD standard, in the case of such a single-sided reproducing disk, the information amount of 4.5 GB capacity is engraved on one side. Of these two substrates, the substrate 1
Regarding No. 2, after being installed in a sputtering device (not shown) and evacuated to a vacuum of 10 −5 torr, Al
RF with Ar gas for (aluminum) target
Sputtering was performed to form about 1000 # of the Al perfect reflection layer 16. The other substrate 11 was placed in the same vacuum sputtering apparatus, and after drawing a similar vacuum, Ar gas was introduced to the SiO 2 (silicon dioxide) target as a transparent inorganic dielectric material. RF sputtering was performed to obtain about 1000 # of SiO2.
A bonding layer 18 was formed, and then sputtering was performed on an Au (gold) target to form a semitransparent layer 17 of about 120 #. In this way, the SiO2 bonding layer 18 and Au
The substrate 11 on which the semitransparent layer 17 is formed is set on a spinner (not shown), and an ultraviolet curable type (U
V) The resin was spin-coated to a thickness of 40 μm. After that, as shown in FIG.
u Al perfect reflection layer 16 so that the semi-transparent layers 17 face each other
The substrate 12 on which the semi-transparent layer 17 of Au is formed and the substrate 11 on which the semi-transparent layer 17 of Au are overlapped, and UV light of about 2 kW is irradiated for about 1 minute from the side of the substrate 11 on which the semi-transparent layer 17 of Au is formed. Then, the UV resin was cured. A disk sample manufactured by such a procedure is referred to as Sample A.

FIG. 2 shows a second embodiment of the present invention, which is the same as the first embodiment and shows a single-sided reproduction dual-layer bonded disc having two reflective layers. In this figure, of the two transparent substrates 11 and 12 having the same diameter of 120 mm and a thickness of 0.6 mm, only the perfect reflection layer 16 of Al is formed on the substrate 12, and on the substrate 11, After the Au semi-transparent layer 17 was formed, the SiO 2 bonding layer 19 was formed, and then the two substrates were cured and adhered with a UV resin having a thickness of 40 μm. The disc sample manufactured in this manner is referred to as Sample B.

FIG. 3 shows a third embodiment of the present invention, which shows a single-sided reproduction dual-layer laminated disc similar to the above-mentioned embodiment. In this figure as well, a disk is manufactured by the same method as the above-mentioned sample A and sample B, except that, as shown in FIG. 3, the SiO 2 bonding layer 18 and the SiO 2 bonding layer 18 are provided on both sides of the Au translucent layer 17. 19 was formed to a thickness of 1000 #. The disk sample manufactured in this manner is referred to as Sample C.

Further, the optical disc shown in FIG.
This is a single-sided reproduction dual-layer laminated disc similar to the above, but the optical disc of FIG. 6 does not have a bonding layer made of a transparent inorganic dielectric material such as SiO 2. That is,
The substrate 22 is formed with only the 1000 # -thick Al perfect reflection layer 26, and the substrate 21 is formed with the 120 # -thick Au semi-transparent layer 27.
Only two such substrates 21 and 22 are formed.
It has a structure in which it is cured and adhered with a UV resin having a thickness of 0 μm.
The disk sample manufactured in this manner is referred to as Sample D.

The sample A, sample B, sample C, and sample D manufactured as described above were subjected to a drop test on a concrete floor surface. The test is 30 cm,
It was carried out under the same conditions by spontaneously dropping from heights of 50 cm, 70 cm and 100 cm. As a result, sample D
Was peeled off in a drop test from a height of 30 cm. On the other hand, sample A and sample B were not peeled off even when dropped from a height of 70 cm, but were peeled off when dropped from a height of 100 cm. Sample C did not peel even when dropped from a height of 100 cm.

Next, the sample A, the sample B, the sample C, and the sample D have exactly the same structure, but only the portions of the adhesive layers 17 and 27 using the UV resin can transmit light. Samples A ′, B ′, C ′, and D ′ are manufactured by changing to a double-sided adhesive tape made of an organic material and having adhesive on both sides. The double-sided pressure-sensitive adhesive tape was pressure-bonded under reduced pressure in order to prevent air bubbles from being mixed in during bonding. When the same natural drop test as described above was performed, Sample D ′ was peeled off by dropping from a height of 30 cm. The sample A ′, the sample B ′, and the sample C ′ were not separated even when dropped from a height of 100 cm.

Further, the samples A, B, and
Samples C and D have exactly the same structure, but are manufactured by changing only the bonding layers 18 and 19 made of a transparent inorganic dielectric material from SiO2 to TiO2. B ",
These are sample C ″ and sample D ″. These samples were also subjected to the same free-falling test as above. Sample A ", sample B", and sample C "
In both cases, peeling did not occur when dropped from a height of 100 cm.

The materials used for the bonding layers 18 and 19 are not limited to the above-mentioned SiO2 and TiO2, but, for example, other oxide-based inorganic dielectric materials such as Ta2O5, SiO, Al2O3, SiN, Si3N4, etc. , AlN
And other nitride-based inorganic dielectric materials, ZnS and other sulfide-based inorganic dielectric materials, or inorganic materials consisting of simple elements such as Si that have good adhesion and are considered transparent to the light beam used. It is conceivable that a thin layer or a mixture thereof is used.
It goes without saying that similar effects can be expected even when used as 8 and 19.

In the embodiment of the present invention, the bonding layer 1
The thickness of 8 and 19 is 1000 #, but normally 2
It is generally known that the adhesiveness can be maintained if the thickness is 00 # or more. Further, if the thickness of the bonding layer becomes a thickness which cannot be optically ignored with respect to the thickness of the adhesive layer of 40 μm, light cannot be condensed by the lens actuator. Therefore, the upper limit of the thickness is about 1 μm. Appropriate.

In the embodiment of the present invention, the bonded two
Although both disks were described as read-only ROM disks, for example, instead of the perfect reflection layer, a recording layer capable of recording, erasing, and overwriting is provided, and the light beam is focused on the semitransparent layer to make the ROM. Even if it is a two-layer laminated disc of a type that reproduces information from the disc and records, erases, and overwrites by focusing the light beam on the recording layer, if the joining layer made of the inorganic material of the present invention is provided. ,
It goes without saying that exactly the same effect can be expected. On the contrary, when the disc on the side having the perfect reflection layer is the ROM disc and the semitransparent layer is the recording layer as described above,
Alternatively, even when both the completely reflective layer and the semitransparent layer are the above recording layers, the effect produced by providing the bonding layer remains unchanged.

Further, in the embodiment of the present invention, the single-sided reproduction laminated disc manufactured by laminating two discs is used. However, as shown in FIG. Used in the method of reproducing the information described above, an optical disc having a multilayer structure formed of a reflective layer, for example, a plurality of optical discs are pasted together to form 1
Even in an optical disc composed of one optical disc, or in an optical disc manufactured by laminating a plurality of reflective layers while inserting an intermediate layer or the like, by using the above-mentioned bonding layer according to the present invention, it is generated in each reflective layer portion. It is possible to bring about the effect of preventing possible peeling.

[0022]

Since the present invention is configured as described above, it has the following effects. The substrate on which the semi-transparent layer is provided and the substrate on which the semi-transparent layer is provided are bonded together via a transparent organic adhesive having a predetermined thickness, and the substrate on the side where the semi-transparent layer is provided is attached. In an optical disc of a type that irradiates a light beam such as a laser beam and focuses on a semitransparent layer or a completely reflective layer to read information in the focused layer, it is semitransparent at the interface between the semitransparent layer and the substrate. By providing a bonding layer made of a transparent inorganic dielectric material at the interface between the layer and the organic adhesive layer, or at both interfaces, the adhesive strength of the optical disc that is easily peeled off at each of the above interfaces is increased, and practical It is possible to provide an optical disc with no problem.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a single-sided reproduction dual-layer bonded disc having a bonding layer provided at an interface between a substrate and a semitransparent layer according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a single-sided reproduction dual-layer bonded disc in which a bonding layer is provided at an interface between a semitransparent layer and an adhesive layer according to the second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a single-sided reproduction dual-layer bonded disc according to a third embodiment of the present invention in which a bonding layer is provided on both sides of a semitransparent layer.

FIG. 4 is a partial cross-sectional view of an optical disc having a plurality of reflective layers, with a bonding layer provided on both sides of a semitransparent layer, according to a fourth embodiment of the present invention.

FIG. 5 is a partial cross-sectional view for explaining the structure of a conventional double-layer laminated single-sided laser reproducing disk according to the SD standard.

FIG. 6 is a partial cross-sectional view for explaining the structure of a conventional two-layer disc having a semitransparent layer and a completely reflective layer.

[Explanation of symbols]

 11 Disk Substrate on Light Beam Entrance Side 12 Second Layer Disk Substrate 13 First Layer Groove (Embossing Information) 14 Second Layer Groove (Embossing Information) 15 Adhesive Layer 16 Perfect Reflection Layer 17 Semi-Transparent Layer 18, 19 Bonding layer

Claims (17)

[Claims] 1. A plurality of information recording layers capable of recording a change in a certain information signal as a change in optical characteristics and reading the information signal from a change due to an optical access from the outside, and the information recording layer. An optical disc comprising a plurality of transparent organic material layers provided in contact with each other and made of an organic material capable of transmitting a light beam, and used for a method of optically accessing some of the information recording layers from one surface. 2. The optical disc according to claim 1, further comprising a bonding layer made of an inorganic dielectric material capable of transmitting a light beam, at the interface between the transparent organic material layer and the information recording layer. 2. The optical disk according to claim 1, wherein a part of the transparent organic material layer is an adhesive layer made of an ultraviolet curable resin having a property of being cured by irradiation of ultraviolet rays. 3. The optical disk according to claim 1, wherein a part of the transparent organic material layer is an adhesive layer composed of a double-sided tape having an adhesive on both sides. 4. The optical disc according to claim 1, wherein the bonding layer is a layer made of an oxide-based inorganic dielectric material. 5. The optical disc according to claim 1, wherein the bonding layer is a layer made of a nitride-based inorganic dielectric material. 6. The optical disc according to claim 1, wherein the bonding layer is a layer made of a sulfide-based inorganic dielectric material. 7. The bonding layer is a layer formed by mixing an oxide-based inorganic dielectric material, a nitride-based inorganic dielectric material, and a sulfide-based inorganic dielectric material. Optical disc. 8. The information recording layer reflects a light beam,
The optical disk according to claim 1, comprising a semitransparent layer having a property of transmitting the light and a completely reflective layer having a property of substantially completely reflecting the light beam. 9. The information recording layer is a layer of a functional film capable of fixing, erasing and reading a certain information signal by irradiation of a light beam, and a light beam can be reflected on a pre-formed embossed pit. The optical disc according to claim 1, further comprising a layer provided with a film. 10. One transparent organic material layer, the bonding layer formed on one side of the transparent organic material layer, and the information recording layer formed on one side of the bonding layer to reflect a light beam. A first optical disc including a semi-transparent layer having a transparent and transparent property, a transparent organic material layer, and an information recording layer formed on one side of the transparent organic material layer to substantially completely shield the light beam. A second reflective optical disk comprising a completely reflective layer having a property of reflecting light to the surface of the second optical disk was bonded to the semi-transparent layer with the completely reflective layer facing each other with an adhesive layer as a transparent organic material layer interposed therebetween. The optical disc according to claim 1, wherein: 11. The transparent organic material layer as one layer and the information recording layer formed on one side of the transparent organic material layer,
A first optical disk comprising a semitransparent layer having a property of reflecting and transmitting a light beam, and the bonding layer formed on one side of the semitransparent layer; and a single transparent organic material layer, A second optical disk comprising a completely reflective layer formed on one side of the transparent organic material layer as an information recording layer and having a characteristic of substantially completely reflecting a light beam, and a bonding layer and a completely reflective layer thereof are opposed to each other. 2. The optical disc according to claim 1, wherein the optical discs are bonded together via a layer made of an adhesive as a transparent organic material layer. 12. The transparent organic material layer as one layer and the first bonding layer formed on one side of the transparent organic material layer,
Further, a semi-transparent layer formed as the information recording layer on one side of the joining layer and having a characteristic of reflecting and transmitting a light beam, and a second joining layer formed on one side of the semi-transparent layer. , A single transparent organic material layer, and a completely reflective layer formed as an information recording layer on one side of the transparent organic material layer and having a characteristic of substantially completely reflecting a light beam. A second optical disc consisting of
2. The optical disk according to claim 1, wherein the second bonding layer and the perfect reflection layer are opposed to each other and are bonded together via a layer made of an adhesive as a transparent organic material layer. 13. The first optical disc and the second optical disc.
Both optical discs have a diameter of approximately 120 mm and a diameter of approximately 0.6.
The optical disc according to claim 10, 11 or 12, having a thickness of mm. 14. The thickness of the bonding layer is 200 # or more 1
14. The optical disc according to claim 13, wherein the optical disc has a thickness of not more than μm. 15. An information signal to be reproduced is formed as embossed pits, is capable of transmitting a light beam, and has a disk shape having a diameter of approximately 120 mm and a thickness of approximately 0.6 mm. A first optical disc comprising a first substrate and the semitransparent layer provided on the embossed pit side of the first substrate, and an information signal to be reproduced, which is different from the information signal, is embossed. A disk-shaped second substrate as a transparent organic material layer formed as pits, capable of transmitting a light beam, having a diameter of about 120 mm and a thickness of about 0.6 mm, and its second substrate. And a perfect reflection layer provided on the embossed pit side of the second substrate.
And a semi-transparent layer and a complete reflection layer thereof are opposed to each other, and they are adhered to each other through an adhesive layer made of a transparent organic material, and a light beam is irradiated from the side of the first substrate, The light beam is focused on the semitransparent layer to reproduce the information signal from the first optical disc, and the light beam is irradiated from the side of the first substrate, and the light beam is focused on the completely reflective layer. In the optical disc used for the method of reproducing the information signal from the second optical disc,
A bonding layer made of a transparent inorganic dielectric material and having a layer thickness of 200 # or more and 1 μm or less is provided on the interface between the substrate and the semitransparent layer and the interface between the semitransparent layer and the adhesive layer. 13. The optical disc according to claim 12, wherein the optical disc is an optical disc. 16. The adhesive layer is an adhesive layer made of an ultraviolet curable resin having a property of being cured by irradiation of ultraviolet rays, and the joint layer is a joint layer made of SiO 2. Item 15. The optical disc according to Item 15. 17. The optical disc according to claim 15, wherein the adhesive layer is an adhesive layer made of a double-sided tape having adhesives on both sides, and the bonding layer is a bonding layer made of TiO 2. .