JP3539000B2 - Multilayer optical disc - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer optical disk having a plurality of signal recording layers.

[0002]

2. Description of the Related Art Hitherto, as a recording medium for recording a large amount of digital signals at a high density, a multilayer optical disk provided with a plurality of signal recording layers has been proposed as shown in FIGS. . This multilayer optical disk has a disk-shaped light transmitting substrate formed of a transparent material, and a plurality of signal recording layers are formed on the light transmitting substrate so as to be stacked.

As shown in FIG. 2, this type of multi-layer optical disc has a first surface having a signal reading surface 106 on one side.
Of the first light transmitting substrate 105 and a second light transmitting substrate 102 superposed on the other surface side of the first light transmitting substrate 105. The surface of the second light transmitting substrate 102 opposite to the surface on which the second light transmitting substrate 102 is superimposed on the first light transmitting substrate 105 is a label surface 101.

The first and second signal recording layers 10 are provided between the first light transmitting substrate 105 and the second light transmitting substrate 102.
4, 103 and the translucent layer 107 are provided so as to be laminated on each other. The first signal recording layer 104 is provided between the first light transmitting substrate 105 and the translucent layer 107, and the second signal recording layer 103 is formed between the second light transmitting substrate 102 and the translucent layer 107. It is provided between.

[0005] Each of the signal recording layers 104 and 103 is formed by the light transmitting substrate 1 when the light transmitting substrate 105 or 102 is molded.
And pits indicating information signals formed on the surfaces of the data lines 05 and 102.

First and second light transmitting substrates 105 and 10
2 have substantially the same thickness as each other, and when the thickness of this multilayer optical disc is t (for example, about 1.2 mm), it has a thickness of about (1/2) t. The translucent layer 107 has 4
It is formed as an extremely thin layer of about 0 μm.

In this multi-layer optical disc, a first reproduction light R ₁ for reading an information signal recorded on a first signal recording layer 104 is incident on a first light transmitting substrate 105 from a signal reading surface 106. , First signal recording layer 104
Is reflected and focused on the first light transmitting substrate 10 again.
5, the light is emitted outward from the signal reading surface 106 side.

In this multi-layer optical disc, a second reproduction light R ₂ for reading out an information signal recorded on the second signal recording layer 103 enters the first light transmitting substrate 105 from the signal reading surface 106. , The light passes through the first signal recording layer 104 and the translucent layer 107, is focused and reflected by the second signal recording layer 103, passes through the translucent layer 107 and the first signal recording layer 104 again, The light is emitted outward from the signal reading surface 106 side through the first light transmitting substrate 105.

As shown in FIGS. 3 and 5, there is a multilayer optical disk having a light transmitting substrate 105 having one surface as a signal reading surface 106. Signal reading surface 1
06, the first and second signal recording layers 103 and 104, the translucent layer 107 and the protective layer 102
Are provided so as to be stacked on the light transmitting substrate 105. Here, the second signal recording layer 104 is provided between the light transmitting substrate 105 and the translucent layer 107. The first signal recording layer 103 includes a translucent layer 107 and a protective layer 10.
2 is provided.

The surface of the protective layer 102 provided on the outermost side on the other side of the light transmitting substrate 105 has a label surface 101.
It has been done.

Each of the signal recording layers 103 and 104 includes pits indicating information signals formed on the surface of the light transmitting substrate 105 and on the surface of the translucent layer 107.

The light transmitting substrate 105 used here has a thickness substantially equal to the thickness t (for example, about 1.2 mm) of the multilayer optical disc. The translucent layer 107 is, for example, 4
It is formed as an extremely thin layer of about 0 μm.

In this multi-layer optical disc, a first reproduction light R ₁ for reading out an information signal recorded on the first signal recording layer 103 enters the light transmitting substrate 105 from the signal reading surface 106, The second signal recording layer 104 and the semi-transparent layer 107 are transmitted through the second signal recording layer 104 and focused on the first signal recording layer 103 to be reflected. The light is emitted outward from the signal reading surface 106 side through the inside of the substrate 105.

In this multilayer optical disk, a second reproduction light R ₂ for reading out an information signal recorded on the second signal recording layer 104 is incident on the light transmitting substrate 105 from the signal reading surface 106. , The second signal recording layer 104
Is focused and reflected at the light transmitting substrate 10 again.
5, the light is emitted outward from the signal reading surface 106 side.

Further, as shown in FIG. 4, a multi-layer optical disk has one surface each of which is a signal reading surface 10.
The first and second light-transmitting substrates 102, 1 and 1106
05. These light transmitting substrates 1
The first and second signal recording layers 103 and 104 and the first and second translucent layers 107 are provided between the light transmitting substrates 102 and 105, respectively. , 108 are provided so as to be stacked on each other.

Here, the first signal recording layer 103 has the first
The second signal recording layer 104 is provided between the first translucent layer 107 and the first translucent layer 107.
08 and the first light transmitting substrate 105. The translucent layers 107 and 108 are joined to each other.

First and second signal recording layers 103 and 104
Includes pits indicating information signals formed on the surfaces of the light transmitting substrates 102 and 105 when the respective light transmitting substrates 102 and 105 are molded.

The thickness of the light transmitting substrate 105 used here is
Assuming that the thickness of this multilayer optical disc is t (for example, about 1.2 mm), it has a thickness substantially equal to (1/2) t.

[0019] In this multilayer optical disc, the first reproduction light R ₁ for reading an information signal recorded on the first signal recording layer 103, as shown in FIG. 4, the first signal of the light transmission substrate 102 The light enters the first light transmitting substrate 102 from the reading surface 101, is focused and reflected by the first signal recording layer 103, passes through the first light transmitting substrate 102, and returns to the first light transmitting substrate 102. 102 signal reading surface 1
It is injected outward from the 01 side.

[0020] In this multi-layer optical disc, a second reproducing light R ₂ for reading an information signal recorded on the second signal recording layer 104, as shown in FIG. 4, the signal of the second light transmitting substrate 105 The light enters the second light transmitting substrate 105 from the reading surface 106, is focused and reflected by the second signal recording layer 104, passes through the second light transmitting substrate 105, and returns to the second light transmitting substrate 105. 105 signal reading surface 1
Injected to the outside through 06.

[0021]

In the above-described multi-layer optical disc, since the signal recording layers are close to each other, the signals recorded in the signal recording layers are read out from the signal recording layers. It is difficult to discriminate between the performed signals.
For this reason, in this type of multilayer optical disc, when the multilayer optical disc is rotated in the same rotation direction, signals recorded on each signal recording layer from the same surface side cannot be read.

When the signal recording layers are close to each other as in the above-described multilayer optical disk, signals of different recording forms cannot be recorded on the signal recording layers.

As the recording form, a recording form using molded pits in a so-called read-only (ROM) disc, a recording form using punching or phase change (Phase Change) in a write-once (DRAW) disc, or a rewritable (Erasable ( Rewriter
ble)) There are a magneto-optical effect and a recording form by phase transition on a disk.

Therefore, the present invention has been proposed in view of the above situation, and reads out signals recorded on each signal recording layer in a multilayer optical disc provided with a plurality of signal recording layers laminated. Sometimes it is easy to discriminate between signals read from each signal recording layer, and it is also possible to read signals recorded on each signal recording layer from the same surface side while rotating in the same rotation direction. It is still another object of the present invention to provide a multi-layer optical disc capable of recording signals of different recording forms on each signal recording layer.

[0025]

In order to solve the above-mentioned problems, a multilayer optical disk according to the present invention comprises a first light transmitting substrate and the first light transmitting substrate as a signal reading surface. A first signal recording layer formed on the light transmitting substrate, a second light transmitting substrate having substantially the same thickness as the first light transmitting substrate, and a signal reading surface on the second light transmitting substrate side A second signal recording layer formed on the second light transmitting substrate. The second recording layer is provided so as to sandwich the first signal recording surface together with the first signal recording surface and the second light transmitting substrate formed on the second transmission substrate, and A first semi-transmissive layer on which a signal recording surface is formed, and a second semi-transmissive layer provided so as to sandwich the second signal recording surface together with the first semi-transmissive layer. A first light transmitting substrate and the second light transmitting substrate,
The first signal recording layer is laminated so as to sandwich the second signal recording layer,
Is bonded to the second semi-transmissive layer.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multilayer optical disc according to the present invention will be described with reference to the drawings.

The multilayer optical disk according to the present invention is used as a recording medium for recording a large amount of digital signals at high density.

As shown in FIG. 1, the multilayer optical disk according to the present invention has a disk-shaped first and second light-transmitting substrates 4 made of a transparent material such as glass or polycarbonate.
The first and second signal recording layers 3 and 6 for recording information signals are formed on the light transmitting substrates 4 and 7.

On the first light transmitting substrate 4, the first light transmitting substrate 4 side is used as a signal reading surface side.
Signal recording layer 3 is provided. Second light transmitting substrate 7
On the upper side, a second signal recording layer 6 formed with the second light transmitting substrate 7 side as a signal reading surface side is formed.

The protective layer 2 is formed on the first light transmitting substrate 4 and on the first signal recording layer 3. The first signal recording layer 3 is provided so as to be sandwiched between the protective layer 2 and the first light transmitting substrate 4. The surface of the protective layer 2 is a label surface 1. The protective layer 2 is formed of a material such as an ultraviolet curable resin.

Each of the first and second signal recording layers 3 and 6 has a signal recording surface, on which information signals are recorded. The signal recording surfaces of the signal recording layers 3 and 6 are formed with pits indicating information signals formed on the surfaces of the light transmitting substrates 4 and 7 when the light transmitting substrates 4 and 7 are molded.
And a reflective film formed along the surface on which the pits are formed. The reflection film is formed of a metal material such as aluminum or a dielectric material.

In the multilayer optical disk according to the present invention,
At least one of the first and second signal recording layers 3 and 6
It has a plurality of signal recording surfaces. In this embodiment, the second signal recording layer 6 is provided with first and second signal recording surfaces 6a and 6b.

The second signal recording layer 6 sandwiches the first signal recording surface 6a together with the first signal recording surface 6a formed on the second light transmitting substrate 7 and the second light transmitting substrate 7. The first semi-transmissive layer 9 provided with the second signal recording surface 6b and the second semi-transmissive layer 9 provided with the first semi-transmissive layer 9 so as to sandwich the second signal recording surface 6b And a semi-transmissive layer 5.

The second signal recording layer 6 of the second light transmitting substrate 7
One surface on the opposite side to the surface on which
The surface on the signal reading surface side of the signal recording layer 6 is a signal reading surface 8.

The first and second light-transmitting substrates 4 and 7 are
Are stacked in such a manner that the signal recording layer 6 is interposed therebetween.
The first light transmitting substrate 4 and the second semi-transmitting layer 5
Are joined together.

The first and second light transmitting substrates 4 and 7 are substantially (1/2) t, where t is the thickness of the multilayer optical disk.
It is formed in the thickness of. Here, since the thickness of the multilayer optical disk is 1.2 mm, the first and second light transmitting substrates 4 and 7 each have a thickness of 0.6 mm. Each of the translucent layers 9 and 5 is formed as an extremely thin layer of about 40 μm.

In the multilayer optical disk according to the present invention, the first reproduction light R ₁ for reading out the information signal recorded on the first signal recording layer 3 is transmitted from the signal reading surface 8 to the second light transmitting substrate 7. And the second signal recording layer 6 and the first signal recording layer 6
Of the first signal recording layer 3, the light is focused and reflected on the signal recording surface of the first signal recording layer 3, passes through the first light transmitting substrate 4 and the second signal recording layer 6 again, and The light is emitted outward from the signal reading surface 8 side through the inside of the second light transmitting substrate 7.

In this multi-layer optical disc, the second reproduction light R ₂ for reading out the information signal recorded on the first signal recording surface 6 a of the second signal recording layer 6 is transmitted from the signal reading surface 8 to the first reproduction light R ₂ . The light enters the light transmitting substrate 7, is focused and reflected on the first signal recording surface 6 a of the second signal recording layer 6, and passes through the second light transmitting substrate 7 again to the signal reading surface 8 side It is ejected from outside.

Further, in the multi-layer optical disc according to the present invention, the third reproduction light R for reading out the information signal recorded on the second signal recording surface 6b of the second signal recording layer 6 is used.
Numeral ₃ is incident on the first light transmitting substrate 7 from the signal reading surface 8, passes through the first signal recording surface 6 a of the second signal recording layer 6, and focuses on the second signal recording surface 6 b. The light is coupled, reflected, and emitted again from the signal reading surface 8 side through the first signal recording surface 6a and the second light transmitting substrate 7 again.

In this multilayer optical disc, the signal recorded on the first signal recording layer 3 and the signal recorded on the second signal recording layer 6 are the same in terms of modulation system and recording system. be able to. In this case, the multilayer optical disc can be used as a recording medium having a signal recording capacity equal to the number of signal recording faces multiplied by the number of signal recording faces with respect to an optical disc having the same number of signal recording faces.

In this multi-layer optical disc, the signal recorded in the first signal recording layer 3 and the signal recorded in the second signal recording layer 6 are different from each other in terms of modulation method and reproduction light wavelength. Can be.

For example, the wavelength of the _first reproduction light R1 used for reading out the signal recorded on the first signal recording layer 3 is 770 nm to 830 nm, and each signal recording surface 6a of the second signal recording layer 6 , 6b used to read the signals recorded on the second and third reproduction lights R ₂ , R ₃
It can be 15 nm to 655 nm.

In this case, the total thickness of the first and second light transmitting substrates 4 and 7 is set to 1.2 mm, and the second signal recording layer 6 affects the transmission of the _first reproduction light R1. By not giving the signal, the signal recorded on the first signal recording layer 3 can be read out by a disc player device for reproducing an optical disc having a diameter of 12 cm or 8 cm, which is generally called a compact disc. it can.

In order to prevent the second signal recording layer 6 from affecting the transmission of the _first reproduction light R1, the spectral transmittance of each signal recording surface 6a, 6b of the second signal recording layer 6 is required. By selecting or setting the characteristics, the transmittance for the light of the wavelength of the _first reproduction light R1 is increased. In this case, the signal recorded on the second signal recording layer 6 can be read without being affected by the first signal recording layer 3. On the second signal recording layer 6, for example, a high-density information signal such as a digital video signal can be recorded.

In the multi-layer optical disc according to the present invention, the signals recorded on the first signal recording layer 3 and the signals recorded on the second signal recording layer 6 may have different recording forms. it can. As a recording form here, in addition to a recording form using molded pits in a read-only (ROM) disk as described above, a so-called write-once type (DRA)
W) Recording form by drilling in a disc, recording form by phase change (Phase Change (PC)), or rewritable (Erasable (Rew
ritable)) type optical discs, a recording mode (including a recording mode called CD-R, CD-MO, etc.) by a magneto-optical effect (MO), a recording mode by a phase transition (PC), and the like.

In the multi-layer optical disc according to the present invention, the first signal recording layer 3 is rewritable as a recording form by a magneto-optical effect or a recording form by phase transition in the rewritable disc, and the second signal recording layer 6 is formed. A high-density information signal such as a digital video signal can be recorded as a recording mode using molded pits on a read-only disc.

Further, the multilayer optical disc according to the present invention
The first signal recording layer 3 is rewritable as a recording form by a magneto-optical effect or a recording form by phase transition in a rewritable disc, and the second signal recording layer 6 has different characteristics from the first signal recording layer 3. Rewritable as a recording mode due to the magneto-optical effect or phase transition of the recording medium.

[0048]

As described above, in the multilayer optical disk according to the present invention, when reading out the signals recorded on the first and second signal recording layers, the signals read from each signal recording layer can be discriminated from each other. It is easy to read signals from each signal recording layer from the same surface side while rotating in the same rotational direction, and further, it is possible to record signals of different recording forms on each signal recording layer. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a multilayer optical disc according to the present invention.

FIG. 2 is a sectional view of a main part showing a conventional multilayer optical disc.

FIG. 3 is a sectional view of a main part showing another example of a conventional multilayer optical disk.

FIG. 4 is a cross-sectional view of a principal part showing still another example of the conventional multilayer optical disc.

FIG. 5 is a sectional view of a main part of the conventional multilayer optical disc shown in FIG.

[Explanation of symbols]

3 first signal recording layer, 4 first light transmitting substrate, 6
Second signal recording layer, 6a First signal recording surface, 6b
Second signal recording surface, 7 Second light transmitting substrate R ₁
1st reproduction light, R2 _2nd reproduction light, R3 _3rd reproduction light

Claims (1)

(57) [Claims] A first light-transmitting substrate; a first signal recording layer formed on the first light-transmitting substrate with the first light-transmitting substrate side serving as a signal reading surface; A second light transmitting substrate having substantially the same thickness as the light transmitting substrate, and a second signal recording layer formed on the second light transmitting substrate with the second light transmitting substrate side as a signal reading surface. The second recording layer is provided so as to sandwich the first signal recording surface together with the first signal recording surface and the second light transmitting substrate formed on the second transmission substrate; A first semi-transmissive layer on which a second signal recording surface is formed, and a second semi-transmissive layer provided so as to sandwich the second signal recording surface together with the first semi-transmissive layer. The first light transmitting substrate and the second light transmitting substrate are stacked so as to sandwich the second signal recording layer. The first light transmitting substrate and the second semitransparent layer and the multilayer optical disc is bonded.