JP2002015461A - Optical information recording medium, method for forming tracking layer of the same and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium in which high-density information recording is possible by using blue laser or the like having shorter wavelength and in which a tracking layer 25 is formed instead of pregrooves and lands when blue laser is used, and to provide a method for forming the tracking layer and a method for manufacturing the medium. SOLUTION: The medium is obtained by aiming such properties that the refractive index of a light absorbing layer 26 changes (generally decreases) by irradiating the dye in the layer with laser light, that the difference in the refractive index between in the region with a changed refractive index and in other part corresponds to the optical difference in the surface level, and that tracking is made possible by the optical difference in the surface level. A part of the light absorbing layer 26 is irradiated with laser light with a specified pitch to specified depth to form a laser irradiated part 23 so that the refractive index of the laser irradiated part 23 is made different from the refractive index of the region 24 not irradiated with laser light at specified depth to form the tracking layer 25 in which the both parts can be optically discriminated from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium, a method of forming a tracking layer thereof, and a method of manufacturing the same. More particularly, the present invention relates to a writable optical information recording medium having at least a light absorbing layer and a light reflecting layer. The present invention relates to a tracking layer forming method and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a conventional writable optical information recording medium, for example, a light absorbing layer containing a light absorbing substance made of an organic dye or the like is provided on a light transmitting substrate having a pregroove formed in a spiral shape. The structure is basically such that a light reflecting layer made of a metal film or the like is further provided on this light absorbing layer. By irradiating this optical information recording medium with recording light such as laser light from the substrate side, the energy is absorbed in the light absorbing layer, and the heat generation and decomposition of the dye in the light absorbing layer, or the thermal deformation of the substrate, etc. It forms recording pits and records information.

FIG. 6 is an enlarged sectional view in the radial direction showing an example of a general optical information recording medium 1.
Are a translucent substrate 2, a light absorbing layer 3 (recording layer) formed on the substrate 2, and a light reflecting layer 4 formed on the light absorbing layer 3.
And a protective layer 5 formed on the light reflecting layer 4.

[0004] The substrate 2 and the light absorbing layer 3 are in contact with each other by a first layer boundary 6. The light absorption layer 3 and the light reflection layer 4 are in contact with each other by the second layer boundary 7. The light reflecting layer 4 and the protective layer 5
It is in contact with the third layer boundary 8.

The substrate 2 has irregularities formed at a predetermined pitch and a predetermined depth. That is, the pregroove 9 is formed on the substrate 2 in a spiral shape. Parts other than the pre-groove 9, that is, lands 10 are located on the left and right of the pre-groove 9, that is, on the left and right in the radial direction of the optical information recording medium 1. A track that causes an optical distance difference or an optical phase difference between the pre-groove 9 and the land 10 is formed, and the pre-groove 9 can be tracked by this track.

As shown, a substrate 2 is placed on an optical information recording medium 1.
When the laser light L1 (recording laser light) is irradiated from the side, the dye in the light absorbing layer 3 absorbs the energy of the laser light L1 to generate heat, and the substrate 2 side is thermally deformed to generate recording pits. 11 is formed. In the recording portion, the refractive index of the recording pit 11 changes due to the exothermic decomposition of the dye in the light absorbing layer 3. By irradiating the recording pit 11 with a laser beam L2 (laser beam for reproduction), thermal deformation of the substrate 2 at the recording pit 11 and refraction of the recording pit 11 and the non-recording pit (land 10). Information is read by obtaining a pit contrast by diffraction of light generated from an optical phase difference caused by a rate difference.

The substrate 2 is made of a highly transparent material having a refractive index of about 1.4 to 1.6 with respect to a laser beam, and is made of a resin having excellent impact resistance, for example, a resin plate of polycarbonate, polyolefin, acrylic or other resin. Is configured.

The light absorbing layer 3 absorbs the energy of the recording laser beam L1. The main light absorbing substance having an arbitrary organic dye or the like is used for recording the recording laser beam L1.
Is a substance that causes the formation of the recording pits 11 by absorbing and decomposing to create a change in the refractive index in the light absorbing layer 3.

The light reflecting layer 4 needs to reflect the laser beams L1 and L2 effectively, and may be made of, for example, gold (Au), silver (Ag), or aluminum (A).
1) and so on.

The protective layer 5 is provided on the light reflecting layer 4 to protect it, and is made of an ultraviolet curable resin or the like.

In an optical information recording medium having the above writable structure (so-called CD-R) or an optical information recording medium having a writable structure using laser light of a shorter wavelength side (so-called DVD-R), The wavelength of the laser light for writing is 600 to 800 nm
An orange or magenta laser beam of a degree (for example, 635 nm or 780 nm) is used.

In order to record information at a higher density, laser light having a shorter wavelength (for example, about 400 to 600 nm, specifically, 410 nm or 42 nm) is used.
It is necessary to use laser light (such as 5 nm or 515 to 520 nm), commonly called a blue laser.

However, the wavelength of the blue laser is 4
In the vicinity of 10 nm, in order to cope with coma, the thickness of the substrate 2 needs to be about 0.1 mm, and the pitch (for example, 0.74 μm) and the depth (for example, 0.35 μm) or less of DVD-R or less. Substrate 2 having a thickness of 0.1 mm or less
Furthermore, it is virtually impossible to injection-mold the pregroove 9. The thickness of the substrate 2 is the same as that of a conventional CD.
-R is about 1.2 mm, and DVD-R is about 0.6 mm.

Therefore, when performing high-density information recording using a blue laser as a recording laser beam and a reproducing laser beam of an optical information recording medium, a pre-groove having a tracking function of the optical information recording medium is required. There is a problem that it is necessary to form a track or tracking layer corresponding to the land 9 and the land 10.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. An optical information recording medium capable of recording information at a higher density, a method of forming a tracking layer thereof, and a method of manufacturing the same are provided. The task is to provide.

Another object of the present invention is to provide an optical information recording medium capable of recording information using a blue laser having a shorter wavelength, a tracking layer forming method thereof, and a manufacturing method thereof.

Another object of the present invention is to provide an optical information recording medium having tracks formed in place of pregrooves and lands when a blue laser is used, a method of forming a tracking layer thereof, and a method of manufacturing the same.

[0018]

That is, according to the present invention, the irradiation of a dye in a light absorbing layer with laser light changes its refractive index (generally decreases). The difference in refractive index from other parts corresponds to an optical step, and this optical step focuses on enabling tracking operation, and the first invention is capable of absorbing laser light. An optical information recording medium having a light absorbing layer and a light reflecting layer formed on the light absorbing layer and reflecting the laser light, wherein the laser light is applied to a part of the light absorbing layer at a predetermined pitch. Irradiation forms a laser beam irradiating part to a predetermined depth, and the refractive index of this laser light irradiating part is made different from the refractive index of the laser light non-irradiating part at the above predetermined depth, so that they can be optically distinguished from each other. Shape tracking layer An optical information recording medium, characterized in that the.

Tracking can be performed by discriminating between the laser beam irradiating section and the laser beam non-irradiating section.

According to a second aspect of the invention, there is provided an optical information layer having a light absorbing layer containing a light absorbing substance capable of absorbing laser light, and a light reflecting layer formed on the light absorbing layer and reflecting the laser light. A method for forming a tracking layer of a recording medium, comprising: a provisional light absorption layer forming step of forming a provisional light absorption layer using the light absorbing substance; and irradiating a part of the provisional light absorption layer with a laser beam at a predetermined pitch. A tracking layer forming step of forming a tracking layer having a portion different from the refractive index of the laser light non-irradiated portion at the predetermined depth in the temporary light absorbing layer by forming a laser light irradiated portion to a depth; A method of forming a tracking layer of an optical information recording medium, further comprising: a step of applying the light absorbing substance to the light absorbing layer to form the light absorbing layer having a predetermined thickness. A.

As the laser light to be applied to the temporary light absorbing layer, a laser light having a higher power than that of a normal recording laser light or a reproduction laser light or a laser light having another wavelength is selected.

According to a third aspect of the present invention, there is provided a track which causes an optical distance difference in an optical path of a laser beam, and a light absorbing layer which is disposed in contact with the track.
An optical information recording medium for recording information, wherein the track has a deteriorated region formed intermittently in a radial direction of the optical information recording medium in a second light absorption layer provided separately from the light absorption layer. An optical information recording medium characterized by having:

According to a fourth aspect of the present invention, there is provided a track having an optical distance difference in an optical path of a laser beam, and a light absorbing layer disposed in contact with the track.
A method of manufacturing an optical information recording medium for recording information, wherein the track is formed by helically altering a second light absorbing layer provided separately from the light absorbing layer and arranging altered regions. A method for manufacturing an optical information recording medium characterized by the following.

According to a fifth aspect of the present invention, there is provided an optical information recording medium for recording information using a laser beam, comprising: a light incident layer that transmits the laser light; and a light incident layer formed on the light incident layer. A tracking layer which causes an optical distance difference in the optical path of the laser light, a light absorbing layer which is formed on the tracking layer and absorbs the laser light, and which is formed on the light absorbing layer And a light reflection layer that reflects the laser light, wherein the tracking layer is intermittently arranged in a radial direction of the optical information recording medium in a second light absorption layer provided separately from the light absorption layer. An optical information recording medium characterized by having an altered area formed in the optical information recording medium.

According to a sixth aspect of the present invention, there is provided an optical information recording medium for recording information using a laser beam, comprising: a light incident layer that transmits the laser light; and a light incident layer formed on the light incident layer. A light-absorbing layer that absorbs the laser light, and a tracking layer that is formed on the light-absorbing layer and generates an optical distance difference in the optical path of the laser light,
A light reflection layer formed on the tracking layer and reflecting the laser light, wherein the tracking layer is formed in a second light absorption layer provided separately from the light absorption layer. An optical information recording medium characterized by having an altered area formed intermittently in the radial direction of the optical information recording medium.

In the optical information recording medium, the method of forming the tracking layer thereof, and the method of manufacturing the same according to the present invention, a laser beam irradiation portion or a deteriorated region is formed in the light absorbing layer, for example, and the other region is formed optically. As in the conventional optical information recording medium, there is no need to physically form unevenness and use this as a track, and a tracking function can be provided regardless of the thickness of the substrate. .

In the first aspect of the present invention, in particular, the refractive index is changed (generally lowered) by irradiating a light absorbing substance such as a dye in the light absorbing layer with a laser beam.
Since the difference in the refractive index between the portion where the refractive index has changed and the other portion corresponds to an optical step, a layer having a predetermined depth including this portion can be used as the tracking layer, and the blue laser A tracking layer can be formed in place of a pre-groove and a land on a substrate that needs to be formed thin in order to use such a method.

In particular, in the second invention, the tracking layer is formed by irradiating a part of the provisional light absorbing layer made of the light absorbing substance with laser light at a predetermined pitch to form a laser light irradiated portion to a predetermined depth. With this configuration, the tracking layer can be formed by laser light irradiation treatment.

In the third aspect of the present invention, in particular, the altered region formed intermittently in the radial direction of the optical information recording medium in the second light absorbing layer provided separately from the light absorbing layer, for example, in the upper layer or the lower layer. This altered area is optically identifiable from adjacent areas, and tracks are provided without forming irregularities. Optical information recording using light is enabled.

Particularly, in the fourth invention, the tracks are formed by arranging the second light absorbing layer provided separately from the light absorbing layer in a helical manner and arranging the deteriorated regions, thereby forming the optical information. The altered area can be intermittently arranged in the radial direction of the recording medium.

In particular, in the fifth invention, the tracking layer formed on the light incident layer has the altered region formed intermittently in the second light absorption layer provided separately from the light absorption layer. As a result, an optical tracking function can be exhibited.

In the sixth invention, in particular, the tracking layer formed on the light absorbing layer is provided with a deteriorated region formed intermittently in the second light absorbing layer provided separately from the light absorbing layer. As a result, an optical tracking function can be exhibited.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an optical information recording medium 20 according to a first embodiment (first invention, third invention) of the present invention.
Will be described with reference to FIGS. 1 to 3 together with a method for forming the tracking layer (second invention) and a method for manufacturing the same (fourth invention). However, the same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. 1 to 3
Is an enlarged cross-sectional view of a main part. First, as shown in FIG. 1, a dye (light absorbing material) is thinly applied to a sheet-like substrate 21 having a predetermined thickness to form a temporary light absorbing layer 22 ( Temporary light absorbing layer forming step).

As shown in FIG. 2, a laser beam L3 for cutting is irradiated to perform laser cutting.
The pigment in the laser light irradiation part 23 is decomposed, and the refractive index of the laser light irradiation part 23 is reduced to make it a deteriorated area. The laser beam irradiating unit 23 by irradiating this cutting laser beam L3 is
(Fig. 3), which are arranged spirally at a predetermined pitch in the radial direction. As shown in Fig. 2 or Fig. 3,
With such an arrangement, the deteriorated region (the laser beam irradiation part 23) is formed intermittently in the radial direction. Therefore, the laser beam irradiating section 23 (degraded area) and the laser beam non-irradiating section 2 alternately adjacent thereto at a predetermined pitch are provided.
4 (non-altered regions) have different refractive indices, and form a tracking layer 25 where an optical distance difference occurs (tracking layer forming step).

As the cutting laser light L3,
The recording laser beam L1 and the reproduction laser beam L2
A laser beam having a power different from that shown in FIG. 6 or a laser beam having a different wavelength is used. Of course, it is sufficient that the refractive index of the portion irradiated with the cutting laser beam L3 is different from the refractive index of the non-irradiated portion and can be optically distinguished from each other, and the refractive index of the laser beam irradiated portion 23 may be high.

As shown in FIG. 3, a dye is further applied on the provisional light absorbing layer 22 (second light absorbing layer) so as to overlap with each other to form a light absorbing layer 26 having a predetermined thickness ( Light absorption layer completion process). The light reflection layer 2 is formed on the light absorption layer 26.
7 is formed (light reflection layer forming step). This light reflection layer 27
Is formed on the upper layer (protective layer forming step). Thus, the optical information recording medium 2 having the tracking layer 25
0 can be created.

In the optical information recording medium 20 having such a configuration, the tracking layer 25 has an optical step (optical distance difference) as shown by an imaginary line and an optical uneven line especially in the upper part of FIG. The pre-groove 9 and the land 10 have the same structure as that of the pre-groove 9 and the land 10 due to the difference in the refractive index between the laser light irradiation part 23 and the laser light non-irradiation part 24.
Can perform the same tracking function as.

In the recording operation using the recording laser beam L1, the recording pits 11 can be formed in the light absorbing layer 26 corresponding to either the laser beam irradiation section 23 or the laser beam non-irradiation section 24. .

FIG. 4 shows a second embodiment (fifth invention).
FIG. 3 is an enlarged cross-sectional view of the optical information recording medium 30 in a radial direction according to FIG. 1, wherein the optical information recording medium 30 includes a light incident layer 31 that transmits a laser beam, and 25, the light absorbing layer 26 formed on the tracking layer 25, and the light absorbing layer 2
6, the light reflection layer 27 formed on the light reflection layer 27, and the substrate 2 or the protection layer 28 formed on the light reflection layer 27.

The light incident layer 31 has a thickness of 0.1 mm or less and is made of a light-transmitting, for example, thermosetting or other arbitrary resin layer. To record.

As described above, the tracking layer 25 causes an optical distance difference in the optical path of the laser beam. As described with reference to FIGS. 2 and 3, the tracking layer 25 is provided separately from the light absorbing layer 26. 2 light absorption layer (provisional light absorption layer 22)
In the optical information recording medium 30, there are a deteriorated area (laser light irradiation section 23) and a non-changed area (laser light non-irradiation section 24) formed intermittently in the radial direction of the optical information recording medium 30.

In the optical information recording medium 30 having such a configuration, the optical distance difference corresponding to the pre-groove 9 and the land 10 is recorded in the tracking layer 25 as shown by the optical concave and convex lines in the lower part of FIG. It can be arranged, and can exhibit a tracking function.

In particular, in the optical information recording medium 30, the laser beam L1 is not transmitted from the substrate 2 or the protective layer 28 side which has sufficient mechanical strength but from the light incident layer 31 side having a thickness of 0.1 mm or less. , L2 to form the recording pits 11 in the light absorbing layer 26 so that recording and reproduction of optical information can be performed. Even a laser beam having a short wavelength such as a blue laser can be employed. Thus, higher density optical information recording is possible.

FIG. 5 shows a third embodiment (sixth invention).
FIG. 3 is an enlarged cross-sectional view in the radial direction of the optical information recording medium 40 according to the first embodiment. The optical information recording medium 40 includes the light incident layer 31, a light absorbing layer 26 formed on the light incident layer 31, Tracking layer 2 formed on light absorbing layer 26
5, a light reflection layer 27 formed on the tracking layer 25, and the substrate 2 or the protection layer 28 formed on the light reflection layer 27.

In the optical information recording medium 40 having such a configuration, as in the case of the optical information recording medium 30 in FIG. Can be arranged in the tracking layer 25, and a tracking function can be exhibited.

[0046]

As described above, according to the present invention, instead of forming irregularities such as pre-grooves and lands, a track is formed by an optically altered region such as a laser beam irradiating portion. Higher-density optical information recording becomes possible by employing laser light of a short wavelength such as a laser.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical information recording medium 20, a tracking layer forming method thereof, and a manufacturing method thereof according to a first embodiment of the present invention, and is an enlarged cross-sectional view of a main part of a provisional light absorbing layer forming step. It is.

FIG. 2 is an enlarged sectional view in the radial direction of the tracking layer forming step.

FIG. 3 is an enlarged sectional view of the completed optical information recording medium 20 and its tracking layer 25 in the radial direction.

FIG. 4 is an enlarged sectional view in the radial direction of an optical information recording medium 30 according to a second embodiment (fifth invention) of the present invention.

FIG. 5 is an enlarged sectional view in the radial direction of an optical information recording medium 40 according to a third embodiment (sixth invention) of the present invention.

FIG. 6 is an enlarged sectional view in the radial direction showing an example of a general optical information recording medium 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 optical information recording medium (FIG. 6) 2 translucent substrate 3 light absorbing layer (recording layer) 4 light reflecting layer 5 protective layer 6 first layer boundary 7 second layer boundary 8 second layer boundary 9 pre Groove 10 land 11 recording pit 20 optical information recording medium (first embodiment, first and third inventions, FIG. 3) 21 sheet-like substrate (FIG. 1) 22 provisional light absorbing layer (second light absorption) Layer) 23 Laser Light Irradiated Area (Degraded Area) 24 Laser Light Non-Irradiated Area (Non-Transformed Area) 25 Tracking Layer 26 Light Absorbing Layer 27 Light Reflecting Layer 28 Protective Layer 30 Optical Information Recording Medium (Second Embodiment, 5 invention, FIG. 4) 31 light incident layer 40 optical information recording medium (third embodiment, sixth invention, FIG. 5) L1 laser light (recording laser light) L2 laser light (reproduction laser light) L3 Laser light for cutting (Fig. 2)

Claims (7)

[Claims] 1. An optical information recording medium comprising: a light absorbing layer capable of absorbing laser light; and a light reflecting layer formed on the light absorbing layer and reflecting the laser light. A part of the layer is irradiated with laser light at a predetermined pitch to form a laser light irradiating part to a predetermined depth, and a refractive index of the laser light irradiating part is different from a refractive index of the laser light non-irradiating part at the predetermined depth. An optical information recording medium characterized by forming a tracking layer that can be optically distinguished from each other. 2. The optical information recording medium according to claim 1, wherein tracking is performed by discriminating between the laser light irradiation section and the laser light non-irradiation section. 3. Tracking of an optical information recording medium comprising: a light absorbing layer containing a light absorbing material capable of absorbing laser light; and a light reflecting layer formed on the light absorbing layer and reflecting the laser light. A method of forming a layer, comprising: a provisional light absorption layer forming step of forming a provisional light absorption layer using the light absorption substance; and irradiating a portion of the provisional light absorption layer with laser light at a predetermined pitch to a predetermined depth. By forming an irradiation part, a tracking layer forming step of forming a tracking layer having a portion different from the refractive index of the laser light non-irradiation part at the predetermined depth in the provisional light absorption layer, A method of forming a tracking layer on an optical information recording medium, further comprising: a step of applying the light absorbing substance to form the light absorbing layer having a predetermined thickness. 4. A track for generating an optical distance difference in an optical path of a laser beam, and a light absorbing layer disposed in contact with the track, and optical information for recording information using the light absorbing layer. A recording medium, wherein the track has a deteriorated region intermittently formed in a radial direction of the optical information recording medium in a second light absorbing layer provided separately from the light absorbing layer. Optical information recording medium. 5. A track for generating an optical distance difference in an optical path of a laser beam, and a light absorbing layer disposed in contact with the track, and optical information for recording information using the light absorbing layer. A method for manufacturing a recording medium, wherein the track is formed by arranging a second light absorbing layer provided separately from the light absorbing layer in a helical manner and arranging a deteriorated region. Manufacturing method of recording medium. 6. An optical information recording medium for recording information using laser light, comprising: a light incident layer that transmits the laser light; a light incident layer formed on the light incident layer; A tracking layer for generating an optical distance difference in an optical path; a light absorbing layer formed on the tracking layer and absorbing the laser light; and a laser light formed on the light absorbing layer and formed on the light absorbing layer. A light reflection layer that reflects light; and wherein the tracking layer is formed intermittently in a radial direction of the optical information recording medium in a second light absorption layer provided separately from the light absorption layer. An optical information recording medium having an area. 7. An optical information recording medium for recording information using laser light, comprising: a light incident layer that transmits the laser light; a light incident layer formed on the light incident layer; A light-absorbing layer for absorbing, a tracking layer formed on the light-absorbing layer and causing an optical path difference in an optical path of the laser light, and a laser light formed on the tracking layer and formed on the tracking layer. A light reflection layer that reflects light; and wherein the tracking layer is formed intermittently in a radial direction of the optical information recording medium in a second light absorption layer provided separately from the light absorption layer. An optical information recording medium having an area.