JP2014038682A - Optical recording medium and method of producing optical recording medium - Google Patents

Abstract

An optical recording medium and an optical recording medium manufacturing method capable of realizing a high capacity by enlarging a signal area are provided.
An optical recording medium includes a substrate, an information layer, and a light transmission layer, and a signal area in which information signals are recorded and / or reproduced by irradiating the information layer with light through the light transmission layer. The distance from the outer peripheral edge is up to a position of 1.0 mm or more and less than 1.5 mm.
[Selection] Figure 1

Description

  The present technology relates to an optical recording medium and a method for manufacturing the optical recording medium.

  As optical recording media, CD (Compact Disc), DVD (Digital Versatile Disc), Blu-ray Disc (registered trademark) (hereinafter referred to as BD) and the like are widely used. In a high-density recording optical disk such as a BD, a light-transmitting resin layer made of an ultraviolet curable resin called a cover layer is formed on the signal reading surface side of the disk. In an optical disc having a multilayer information layer, a resin layer made of an ultraviolet curable resin called a so-called intermediate layer is formed between the information layers.

  The resin layer is formed by using, for example, a spin coating method, an ink jet method, or the like (for example, see Patent Documents 1 to 3). Further, when a resin layer called a cover layer is manufactured by a spin coating method, an edge cut method or the like is used. The edge cut method can be summarized as follows.In the spin coating method, the outermost peripheral portion is covered with a mask, etc., so that the outermost peripheral portion is not irradiated with ultraviolet rays, and the ultraviolet curable resin other than the outermost peripheral portion is cured, This is a method for obtaining a resin layer having a uniform film thickness by removing the outermost ultraviolet curable resin by shaking it and suppressing the resin swell on the outer periphery.

JP 2004-280863 A Japanese Patent No. 3924855 International Publication No. 2009/0987871

  However, in the spin coating method, a bulge occurs in the outer peripheral portion of the resin layer, so that there is a region that cannot be used as a signal region of 1.5 mm or more in the outer peripheral portion. In addition, when the edge cut method is used, in the portion covered with the outermost peripheral mask, a large step in the dent direction occurs in the resin layer, and there is an area that cannot be used as a signal area. It is difficult to expand to the outer peripheral side.

  Accordingly, an object of the present technology is to provide an optical recording medium and a method for manufacturing the optical recording medium that can realize a high capacity by expanding a signal area.

  In order to solve the above-described problems, the present technology includes a substrate, an information layer, and a light transmission layer, and information signals are recorded and / or reproduced by irradiating the information layer with light through the light transmission layer. The signal recording area is an optical recording medium having a distance of 1.0 mm or more and less than 1.5 mm from the outer peripheral edge.

  In the present technology, an information layer is formed, and an application resin layer is formed by applying an ultraviolet curable resin by an inkjet method. In the application of the ultraviolet curable resin, the distance from the outer peripheral edge is 1.0 mm or more and less than 1.5 mm. The coating mode of the ultraviolet curable resin in the outer peripheral region on the outer peripheral side from the position and the coating mode of the ultraviolet curable resin in the inner peripheral region on the inner peripheral side from the outer peripheral region are changed. This is a method for producing an optical recording medium in which a light transmission layer is formed by curing.

  In the present technology, a high capacity can be realized by having a configuration in which the signal region has a position from 1.0 mm to less than 1.5 mm in distance from the outer peripheral edge.

  According to the present technology, an increase in capacity can be realized by expanding a signal region.

FIG. 1 is a schematic cross-sectional view showing a configuration example of an optical recording medium according to the first embodiment of the present technology. FIG. 2A is a schematic plan view for explaining a signal region. FIG. 2B is a schematic cross-sectional view for explaining a signal region. 3A to 3D are schematic cross-sectional views for explaining the manufacturing process of the optical recording medium. FIG. 4 is a schematic plan view for explaining an application mode of the ultraviolet curable resin. FIG. 5 is a block diagram illustrating a configuration example of an optical recording medium manufacturing apparatus. FIG. 6 is a schematic cross-sectional view showing a configuration example of an optical recording medium according to the second embodiment of the present technology. FIG. 7A is a graph showing the thickness distribution of the light transmission layer measured for Sample 1-1. FIG. 7B is a graph showing the thickness distribution of the light transmission layer measured for Sample 1-2. FIG. 8 is a graph showing the thickness distribution of the light transmission layer measured for Sample 2-1.

Hereinafter, embodiments of the present technology will be described with reference to the drawings. The description will be given in the following order.
1. First Embodiment (First Example of Optical Recording Medium)
2. Second Embodiment (Second Example of Optical Recording Medium)
3. Other embodiment (modification)

1. First Embodiment <Configuration of Optical Recording Medium>
An optical recording medium according to the first embodiment of the present technology will be described. FIG. 1 is a schematic cross-sectional view showing a configuration example of an optical recording medium according to the first embodiment of the present technology. For example, the optical recording medium is an optical disc having a disk shape with an opening (also referred to as a center hole) provided at the center.

  As shown in FIG. 1, the optical recording medium according to the first embodiment of the present technology is a rewritable, write-once or read-only optical recording medium having a single information layer 2. In this optical recording medium, an information layer 2 and a light transmission layer 3 are sequentially laminated on a substrate 1.

  In the optical recording medium according to the first embodiment of the present technology, information signals are recorded and / or reproduced by irradiating the information layer 2 with laser light from the light transmitting layer 3 side. For example, a laser beam having a wavelength in the range of 405 nm is condensed by an objective lens having a numerical aperture of 0.85, and irradiated to the information layer 2 from the light transmission layer 3 side, thereby recording or reproducing an information signal. Is done.

  Hereinafter, the substrate 1, the information layer 2, and the light transmission layer 3 constituting the optical recording medium will be described in order.

(substrate)
The substrate 1 has an annular shape with an opening formed in the center. One main surface of the substrate 1 is an uneven surface, and the information layer 2 is formed on the uneven surface. Hereinafter, the concave portion of the uneven surface is referred to as in-groove, and the convex portion of the uneven surface is referred to as on-groove.

  Examples of the shape of the in-groove and the on-groove include various shapes such as a spiral shape and a concentric shape. In-grooves and / or on-grooves are wobbled (meandered) to add address information.

  The diameter of the substrate 1 is selected to be 120 mm, for example. The thickness of the substrate 1 is selected in consideration of rigidity, preferably 0.3 mm or more and 1.3 mm or less, for example, 1.1 mm. The diameter (radius) of the center hole is selected to be 15 mm, for example.

  As the material of the substrate 1, for example, a plastic material such as polycarbonate resin, polyolefin resin, or acrylic resin, or glass can be used. In consideration of cost, it is preferable to use a plastic material as the material of the substrate 1.

(Information layer)
The information layer 2 is a reflection film, a recording film, or the like formed on the unevenness of the substrate 1. When the optical recording medium is a read-only type, the information layer 2 is a reflective film made of, for example, gold (Au), silver (Ag), silver alloy, aluminum (Al), or aluminum alloy. When the optical recording medium is a write-once type, the information layer 2 is made of a write-once material of an organic compound or an inorganic compound. When the optical recording medium is a rewritable type, the information layer 2 is made of a phase change material or the like.

(Light transmission layer)
The light transmission layer 3 is a resin layer obtained by curing an ultraviolet curable resin. Examples of the material of the resin layer include an ultraviolet curable acrylic resin. Specifically, for example, an ultraviolet curable resin for optical discs such as a Blu-ray disc layer forming resin manufactured by Sony Chemical & Information Device Co., Ltd. can be used.

  The thickness of the light transmission layer 3 is preferably selected from the range of 10 μm or more and 177 μm or less, for example, 100 μm. The thickness of the light transmission layer 3 is preferably selected from the range of 10 μm or more and 177 μm or less, for example, 75 μm. By combining such a thin light transmission layer 3 and an objective lens having a high NA (numerical aperture) of, for example, about 0.85, high density recording can be realized. The inner diameter (diameter) of the light transmission layer 3 is selected to be 22.7 mm, for example.

(Signal area)
FIG. 2A is a plan view of an optical recording medium for explaining a signal area. FIG. 2B is a schematic cross-sectional view for explaining a signal region. In FIG. 2A, illustration of members other than the information layer 2 and the substrate 1 is omitted.

  As shown in FIGS. 2A and 2B, in the optical recording medium, the information layer 2 is formed and has an annular signal region R having good recording / reproducing signal characteristics. In the signal region R, information signals are recorded and / or reproduced by irradiating the information layer 2 with light through the light transmission layer 3. In this optical recording medium, the signal region R has a position from 1.0 mm to less than 1.5 mm in distance from the outer peripheral edge of the optical recording medium. In the example shown in FIGS. 2A and 2B, the signal region R is up to a distance t1 = 1 mm from the outer peripheral edge of the optical recording medium. The distance from the outer peripheral edge of the optical recording medium is a radial distance from the outer peripheral edge of the optical recording medium.

  In the signal region R, the change in film thickness (film thickness error) of the light transmission layer 3 is, for example, ± 2 μm or less. The region where the change in film thickness of the light transmission layer 3 is ± 2 μm or less is, for example, a position from 1.0 mm to less than 1.5 mm in distance from the outer peripheral edge of the optical recording medium.

  As shown in FIG. 2B, the light transmission layer 3 has a flat surface on the inner peripheral side and an inclined surface on the outer peripheral end. This inclined surface is, for example, a steeply inclined surface that starts to be inclined toward the outer periphery from a position that is 1.0 mm or more and less than 1.5 mm in distance from the outer peripheral edge of the optical recording medium. This inclined surface forms, for example, an arcuate curved surface at the inclination start portion. In this optical recording medium, the light-transmitting layer 3 has a steeply inclined surface at the outer peripheral end portion, the rise of the outer peripheral end portion is suppressed, and a region where the film thickness change of the light transmitting layer 3 is small is expanded to the outer peripheral side. Has been.

  Since this optical recording medium has a larger signal area on the outer peripheral side compared to the conventional optical recording medium, even with the same dimensions as the conventional optical recording medium, a larger capacity optical recording medium than the conventional optical recording medium can be obtained. realizable. In the conventional optical recording medium, in the light transmission layer formed by the spin coating method, a bulge occurs at the outer peripheral edge, and therefore there is an area where recording and reproduction cannot be performed more than 1.5 mm from the outer peripheral edge. For this reason, as in the optical recording medium of the present technology, a signal region having good recording / reproducing signal characteristics may be located at a distance of 1.0 mm or more and less than 1.5 mm from the outer peripheral edge of the optical recording medium. It was difficult.

<Method for producing optical recording medium>
A method for manufacturing an optical recording medium according to the first embodiment of the present technology will be described. 3A to 3D are schematic cross-sectional views for explaining a method for manufacturing an optical recording medium. Below, the manufacturing method of an optical recording medium is demonstrated, referring FIG. 3A-FIG. 3D suitably.

(Substrate molding process)
First, the board | substrate 1 with which the uneven surface was formed in one main surface is shape | molded. As a method for molding the substrate 1, for example, an injection molding (injection) method, a photopolymer method (2P method: Photo Polymerization), or the like can be used.

(Information layer formation process)
Next, the information layer 2 is formed by, eg, sputtering. Thus, the information layer 2 is formed on the substrate 1 as shown in FIG. 3A.

(Light transmission layer forming process)
Next, the light transmission layer 3 is formed on the information layer 2. In the present technology, the light transmission layer 3 is formed by applying an ultraviolet curable resin by an inkjet method described below and then curing the resin.

(Coating process)
As shown in FIG. 3B, an ultraviolet curable resin 3a is applied on the information layer 2 by an inkjet method. The inkjet method is, for example, a method in which at least one of the inkjet head 11 and the substrate 1 is moved, and an ultraviolet curable resin is applied by discharging the ultraviolet curable resin from the inkjet head 11.

  In the step of applying the ultraviolet curable resin 3a, it is preferable to change the application mode of the ultraviolet curable resin 3a between the outer peripheral region Q1 and the inner peripheral region Q2 shown in FIG. For example, in the application step of the ultraviolet curable resin 3a, the application amount of the ultraviolet curable resin in the outer peripheral region Q1 is made smaller than the application amount of the ultraviolet curable resin in the inner peripheral region Q2, so that the ultraviolet curable resin is applied in the outer peripheral region Q1. The mode and the application mode of the ultraviolet curable resin in the inner peripheral region Q2 are changed.

  For example, in the inner peripheral region Q2, the discharge amount of the droplets made of the ultraviolet curable resin 3a discharged from the inkjet nozzles of the inkjet head 11 is increased, and in the outer peripheral region Q1, the discharge amount of the droplets made of the ultraviolet curable resin 3a is increased. Set smaller. The outer peripheral region Q1 is, for example, a region on the outer peripheral side from a position that is 1 mm or more and less than 1.5 mm in distance from the outer peripheral end. The inner peripheral region Q2 is, for example, a region on the inner peripheral side from the outer peripheral region Q1.

  For example, the appropriate liquid discharge amount is set to 12 pl / nozzle amount or the like in the outer peripheral region Q1, and is set to 30 pl / nozzle amount or the like in the inner peripheral region Q2. As a result, a step is formed between the coating layer of the ultraviolet curable resin 3a having a small thickness in the outer peripheral region Q1 and the coating layer of the ultraviolet curable resin 3a having a large thickness in the inner peripheral region Q2.

(Leveling process)
As shown in FIG. 3C, after applying the ultraviolet curable resin 3a, the ultraviolet curable resin 3a in the inner peripheral region Q2 moves to the outer peripheral region Q1 with a small amount of application by leaving it to stand for a predetermined time. An inclined surface in which the level difference from the inner peripheral region Q2 is eliminated is formed. This inclined surface is, for example, a steep inclined surface where the inclination starts from the position of 1.0 mm or more and less than 1.5 mm from the outer peripheral edge toward the outer periphery. In addition, this inclined surface forms, for example, an arcuate curved surface at the inclination start portion.

(UV irradiation process)
After the leveling step shown in FIG. 3C, the UV irradiation step shown in FIG. 3D is performed. By the UV irradiation 12 with respect to the ultraviolet curable resin 3a, the uncured ultraviolet curable resin 3a is cured, and a desired light transmission layer 3 is formed. As described above, the target optical recording medium can be obtained.

<Optical recording medium manufacturing apparatus>
FIG. 5 shows an example of an apparatus for manufacturing an optical recording medium used in the above-described light transmission layer forming step. As shown in FIG. 5, the optical recording medium manufacturing apparatus includes one or a plurality of inkjet heads (IJ heads) 21, a UV curing device 22, a feed stage 23, and an operation unit for operating and controlling them. 24, a control unit 25, and a pattern generation unit 26. In accordance with the application target medium input corresponding to the type of recording medium (disk 20) input from the operation unit 24, the control unit 25 communicates with the pattern generation unit 26 for generating an ejection pattern to the inkjet head 21, An inkjet discharge pattern is generated. For example, the pattern generation unit 26 generates, for example, a discharge pattern in which the discharge amount is changed between the outer peripheral region Q1 and the inner peripheral region Q2 described above.

  Thereafter, the inkjet head 21 and the feed stage 23 are controlled to discharge a predetermined pattern onto the disk 20. Then, after a predetermined waiting time, the UV curing device 22 irradiates the disk 20 with UV light, thereby curing the protective material (ultraviolet curable resin) on the disk 20. Thereby, the light transmission layer 3 is formed.

2. Second Embodiment <Configuration of Optical Recording Medium>
An optical recording medium according to the second embodiment of the present technology will be described. FIG. 6 is a cross-sectional view illustrating a configuration example of an optical recording medium according to the second embodiment of the present technology. As shown in FIG. 6, the optical recording medium according to the second embodiment of the present technology is a rewritable, write once or read-only optical recording medium having two information layers. In this optical recording medium, a first information layer 32, an intermediate layer 33, a second information layer 34, and a light transmission layer 35 are sequentially laminated on a substrate 31.

(substrate)
The substrate 31 is the same as that of the first embodiment.

(First information layer)
The first information layer 32 is a reflective film, a recording film, or the like formed on the unevenness of the substrate 31. When the optical recording medium is a read-only type, the first information layer 32 is a reflective film made of, for example, gold (Au), silver (Ag), silver alloy, aluminum (Al), or aluminum alloy. . When the optical recording medium is a write-once type, the first information layer 32 is made of a write-once material of an organic compound or an inorganic compound. When the optical recording medium is a rewritable type, the first information layer 32 is made of a phase change material or the like.

(Middle layer)
The intermediate layer 33 serves to separate the first information layer 32 and the second information layer 34 from each other with a sufficient physical and optical distance, and an uneven surface is provided on the surface thereof. The uneven surface forms, for example, concentric or spiral grooves (in-groove and on-groove). The material of the intermediate layer 33 is not particularly limited, but it is preferable to use an ultraviolet curable resin. The same material as that in the first embodiment can be used for the ultraviolet curable resin. Further, the intermediate layer 33 preferably has a sufficiently high light transmittance since it serves as an optical path of laser light for recording or reproducing information signals to the inner layer.

(Second information layer)
The second information layer 34 is a recording film that can record and / or reproduce information signals by irradiation with laser light. The second information layer 34 is a reflection film, a recording film, or the like formed on the unevenness of the intermediate layer 33. When the optical recording medium is a read-only type, the second information layer 34 is a reflective film made of, for example, gold (Au), silver (Ag), silver alloy, aluminum (Al), or aluminum alloy. . When the optical recording medium is a write-once type, the second information layer 34 is made of a write-once material of an organic compound or an inorganic compound. When the optical recording medium is a rewritable type, the second information layer 34 is made of a phase change material or the like.

(Light transmission layer)
The light transmission layer 35 is the same as that of the first embodiment.

(Method for producing optical recording medium)
A method for manufacturing an optical recording medium according to the second embodiment of the present technology will be described.

(Substrate molding process)
First, the board | substrate 31 with which the uneven surface was formed in one main surface is shape | molded. As a method for molding the substrate 31, for example, an injection molding (injection) method, a photopolymer method (2P method: Photo Polymerization), or the like can be used.

(First information layer forming step)
Next, the first information layer 32 is formed on the substrate 31 by sputtering, for example.

(Intermediate layer formation process)
Next, the intermediate layer 33 is formed on the first information layer 32. The intermediate layer 33 is uniformly coated with an ultraviolet curable resin on the first information layer 32 by, for example, the inkjet method described above. At this time, similarly to the step of forming the light transmission layer 3 of the first embodiment, the application mode of the ultraviolet curable resin in the outer peripheral region Q1 and the application mode of the ultraviolet curable resin in the inner peripheral region Q2 may be changed. You may perform a process.

  Thereafter, the concave / convex pattern of the stamper is pressed against the ultraviolet curable resin uniformly applied on the first information layer 32, and the ultraviolet curable resin is irradiated with ultraviolet rays to be cured, and then the stamper is peeled off. Thereby, the uneven pattern of the stamper is transferred to the ultraviolet curable resin, and the intermediate layer 33 provided with, for example, in-grooves and on-grooves is formed on the first information layer 32.

(Second information layer forming step)
Next, the second information layer 34 is formed on the unevenness of the intermediate layer 33 by, for example, sputtering.

(Light transmission layer forming process)
Next, the light transmission layer 35 is formed on the second information layer 34. The light transmission layer 35 can be formed by applying an ultraviolet curable resin by an ink jet method and then curing it, as in the first embodiment. As described above, the target optical recording medium can be obtained.

  Specific examples of the present technology will be described in detail, but the present technology is not limited thereto.

[Test example]
<Sample 1-1>
An ultraviolet curable resin (BD base resin (viscosity> 400 cp)) was applied onto a disk-shaped polycarbonate resin substrate by an inkjet method. In sample 1, the coating amount in the inner peripheral region Q2 and the coating amount in the outer peripheral region Q1 (regions within 1 mm from the outer peripheral edge) were changed. That is, the inner peripheral area Q2 was discharged at an amount of 30 pl / nozzle and the outer peripheral area Q1 was discharged at an amount of 12 pl / nozzle. Then, after leaving still for 20 seconds, UV hardening which hardens an ultraviolet curable resin by performing UV irradiation was performed. As a result, Sample 1-1 in which a light transmission layer was formed on the substrate was obtained. The nozzle resolution of the inkjet head is 360 dpi × 360 dpi.

<Sample 1-2>
An ultraviolet curable resin (BD base resin (viscosity> 400 cp)) was applied onto a disk-shaped polycarbonate resin substrate by an inkjet method. In sample 2, the coating amount of the inner peripheral region Q2 and the outer peripheral region Q1 was made equal. That is, the inner peripheral area Q2 and the outer peripheral area Q1 were discharged at an amount of 30 pl / nozzle. Then, after leaving still for 20 seconds, UV hardening which hardens an ultraviolet curable resin by performing UV irradiation was performed. Thereby, Sample 1-2 in which a light transmission layer was formed on the substrate was obtained. The nozzle resolution of the inkjet head is 360 dpi × 360 dpi.

(Evaluation)
(Thickness distribution of light transmission layer)
For Sample 1-1 to Sample 1-2, the thickness distribution of the light transmission layer was measured. FIG. 7A shows the thickness distribution of the light transmission layer of Sample 1-1. FIG. 7B shows the thickness distribution of Sample 1-2.

  As shown in FIG. 7A, when the amount of the UV curable resin applied is changed between the inner peripheral region and the outer peripheral region, it is confirmed that there is no bulge at the outer peripheral end and the slope is steep in the range of 1 mm in width. It was. On the other hand, as shown in FIG. 7B, when the application amount of the ultraviolet curable resin was made equal in the inner peripheral region and the outer peripheral region, swell occurred at the outer peripheral end.

<Sample 2-1>
After forming an Ag film on a polycarbonate resin substrate, an ultraviolet curable resin (BD base resin (viscosity> 400 cp)) was applied by an inkjet method. The application conditions were: inkjet feed rate: 7 m / min, application thickness: 16 μm, liquid: 5 drop per dpt, application width 70 mm × 1 scan. After coating, the solution was allowed to stand for 30 seconds and then cured by ultraviolet irradiation. Thereby, Sample 2-1 in which a light transmission layer was formed on the target substrate was obtained.

<Sample 2-2>
After forming an Ag film on a polycarbonate resin substrate, an ultraviolet curable resin (BD base resin (viscosity> 400 cp)) was applied by spin coating, and then cured by ultraviolet irradiation. Thereby, Sample 2-2 in which a light transmission layer was formed on the target substrate was obtained.

(Evaluation)
(Thickness distribution of light transmission layer)
For Sample 2-1, the thickness distribution of the light transmission layer was measured. FIG. 8 shows the thickness distribution of the light transmission layer of Sample 2-1. As shown in FIG. 8, the region where the change in the thickness of the light transmission layer (error from the thickness of 16 μm) was ± 2 μm or less could be expanded to a position of 1 mm from the outer peripheral edge.

(Noise level measurement)
When the noise level of Sample 2-1 in which the light transmission layer was formed using the inkjet method and Sample 2-2 in which the light transmission layer was formed using the spin coating method was measured, the noise level in Sample 2-1 was − It was 76.8 dBm, and in sample 2-2, the noise level was -77.4 dBm. That is, in Sample 2-1 produced using the inkjet method, a noise level comparable to that of Sample 2-2 produced using the spin coat method was obtained.

3. Other embodiment (modification)
The present technology is not limited to the above-described embodiments of the present technology, and various modifications and applications are possible without departing from the scope of the present technology.

For example, the numerical values, structures, shapes, materials, raw materials, manufacturing processes and the like given in the above-described embodiments and examples are merely examples, and different numerical values, structures, shapes, materials, raw materials, A manufacturing process or the like may be used.

  In addition, the configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and examples can be combined with each other without departing from the gist of the present technology.

  In the first to second embodiments described above, the present invention is applied to an optical recording medium having one or two information layers. However, the present invention is an optical recording medium having three or more information layers. It is also possible to apply to a recording medium.

  In the above-described embodiment, in the formation of the light transmission layer and / or the formation of the intermediate layer, the outer peripheral region Q1 and the inner peripheral region are changed by changing the coating amount of the ultraviolet curable resin between the outer peripheral region Q1 and the inner peripheral region Q2. Although the application | coating aspect of the ultraviolet curable resin with Q2 was changed, it is not limited to this.

  For example, in the formation of the light transmission layer and / or the intermediate layer, the outer peripheral region may be printed with a predetermined pattern such as a mesh pattern or a staggered pattern, and the ultraviolet curable resin may be applied. After applying the UV curable resin, the UV curable resin flows into the area where there is no droplet of the predetermined pattern, and the film thickness in the outer peripheral area after application can be reduced, reducing the rise of the UV curable resin in the outer peripheral area. it can.

  For example, in the formation of the light transmission layer and / or the formation of the intermediate layer, the coating solution concentration may be changed between the inner peripheral region and the outer peripheral region. In the outer peripheral region, the volume decrease during solvent drying is increased by decreasing the coating liquid concentration and increasing the amount of solvent. Thereby, the rise of the ultraviolet curable resin in the outer peripheral region can be relatively reduced. In this case, a plurality of ink jets are required.

  For example, in the formation of the light transmission layer and / or the formation of the intermediate layer, a material having a low viscosity and a low surface tension may be applied to the outer peripheral portion. When the liquid in the inner peripheral area moves to the liquid in the outer peripheral area, the liquid blends in the outer peripheral area, so that the swell is reduced.

  For example, in the formation of the light transmission layer and / or the formation of the intermediate layer, at least one of a groove, a dent, and an inclination may be provided on the outer peripheral side of the substrate. When the UV curable resin is applied by spin coating, the amount of coating liquid in the outer peripheral region cannot be controlled, so that protrusions can be prevented but the film thickness cannot be controlled. In the case of inkjet, the application amount and the application location can be precisely controlled, so that the UV curable resin can be applied while maintaining the film thickness uniformity.

  Further, for example, in the formation of the light transmission layer and / or the formation of the intermediate layer, it may be applied accurately only to the area that needs to be ejected. The outer diameter of the disc and the outer diameter of the film are detected with a camera. A coating pattern in a range that falls within the outer diameter of the disk may be generated while completely covering the outer diameter of the film formation with a uniform film thickness based on the detection position, and then the ejection may be performed using the generated coating pattern.

  Moreover, this technique can take the following structures.

[1]
A substrate,
The information layer,
A light transmission layer,
Optical recording in which a signal area where information signals are recorded and / or reproduced by irradiating light to the information layer through the light transmission layer is at a distance of 1.0 mm or more and less than 1.5 mm from the outer peripheral edge. Medium.
[2]
[1] The optical recording medium according to [1], wherein the region where the change in thickness of the light transmission layer is ± 2 μm or less is a position from 1.0 mm to less than 1.5 mm in distance from the outer peripheral edge.
[3]
The optical recording according to any one of [1] to [2], wherein the light transmission layer has an inclined surface that starts to be inclined toward the outer periphery from a position of 1.0 mm or more and less than 1.5 mm at a distance from the outer peripheral end. Medium.
[4]
The optical recording medium according to [3], wherein the inclined surface forms an arcuate curved surface at an inclination start portion.
[5]
The optical recording medium according to any one of [1] to [4], comprising two or more information layers.
[6]
The optical recording medium according to [5], further comprising an intermediate layer between the information layers.
[7]
The optical recording medium according to any one of [1] to [6], wherein the light transmission layer is formed by applying an ultraviolet curable resin by an inkjet method.
[8]
Forming an information layer,
Form a coating resin layer by applying an ultraviolet curable resin by the inkjet method,
In the application of the ultraviolet curable resin, the application mode of the ultraviolet curable resin in the outer peripheral region on the outer peripheral side from the position of 1.0 mm or more and less than 1.5 mm in the distance from the outer peripheral end, and the inner periphery on the inner peripheral side from the outer peripheral region Change the application mode of the UV curable resin in the region,
A method for producing an optical recording medium, wherein after forming the coating resin layer, the coating resin layer is cured by ultraviolet irradiation to form a light transmission layer.
[9]
In the application of the ultraviolet curable resin, the application amount of the ultraviolet curable resin in the outer peripheral region is made smaller than the application amount of the ultraviolet curable resin in the inner peripheral region, so that the ultraviolet curable resin in the outer peripheral region is reduced. [8] The method for producing an optical recording medium according to [8], wherein the coating mode and the coating mode of the ultraviolet curable resin in the inner peripheral region are changed.
[10]
The method for producing an optical recording medium according to [9], wherein after the formation of the coating resin layer, the coating resin layer is cured by ultraviolet irradiation after a predetermined time has elapsed.
[11]
In the formation of the light transmission layer, an inclined surface that starts to be inclined toward the outer periphery from a position of 1.0 mm or more and less than 1.5 mm at a distance from the outer peripheral end is formed. The manufacturing method of the optical recording medium of description.
[12]
In the formation of the light transmission layer, a region where the change in thickness of the light transmission layer is ± 2 μm or less is formed to a position of 1.0 mm or more and less than 1.5 mm in distance from the outer peripheral edge [8] to [8] 11] The method for producing an optical recording medium according to any one of [11].

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Information layer 3 ... Light transmission layer 3a ... Ultraviolet curable resin 5 ... Light transmission layer 11 ... Inkjet head 12 ... UV irradiation 20 ... Disk 21 ... Inkjet head 22 ... UV curing device 23 ... Stage 24 ... Operation unit 25 ... Control unit 26 ... Pattern generation unit 31 ... Substrate 32 ... Information layer 33 ...・ Intermediate layer 34 ... Information layer 35 ... Light transmission layer

Claims (12)

A substrate,
The information layer,
A light transmission layer,
Optical recording in which a signal area where information signals are recorded and / or reproduced by irradiating light to the information layer through the light transmission layer is at a distance of 1.0 mm or more and less than 1.5 mm from the outer peripheral edge. Medium.   2. The optical recording medium according to claim 1, wherein the region where the change in thickness of the light transmission layer is ± 2 μm or less is up to a position of 1.0 mm or more and less than 1.5 mm in distance from the outer peripheral edge.   2. The optical recording medium according to claim 1, wherein the light transmission layer has an inclined surface whose inclination starts toward the outer periphery from a position of 1.0 mm or more and less than 1.5 mm at a distance from the outer peripheral end.   The optical recording medium according to claim 3, wherein the inclined surface forms an arcuate curved surface at an inclination start portion.   The optical recording medium according to claim 1, further comprising two or more information layers.   The optical recording medium according to claim 5, further comprising an intermediate layer between the information layers.   The optical recording medium according to claim 1, wherein the light transmission layer is formed by applying an ultraviolet curable resin by an inkjet method. Forming an information layer,
Form a coating resin layer by applying an ultraviolet curable resin by the inkjet method,
In the application of the ultraviolet curable resin, the application mode of the ultraviolet curable resin in the outer peripheral region on the outer peripheral side from the position of 1.0 mm or more and less than 1.5 mm in the distance from the outer peripheral end, and the inner periphery on the inner peripheral side from the outer peripheral region Change the application mode of the UV curable resin in the region,
A method for producing an optical recording medium, wherein after forming the coating resin layer, the coating resin layer is cured by ultraviolet irradiation to form a light transmission layer.   In the application of the ultraviolet curable resin, the application amount of the ultraviolet curable resin in the outer peripheral region is made smaller than the application amount of the ultraviolet curable resin in the inner peripheral region, so that the ultraviolet curable resin in the outer peripheral region is reduced. The method for producing an optical recording medium according to claim 8, wherein the coating mode and the coating mode of the ultraviolet curable resin in the inner peripheral region are changed.   The method for producing an optical recording medium according to claim 9, wherein after the formation of the coating resin layer, the coating resin layer is cured by ultraviolet irradiation after a predetermined time has elapsed.   The manufacturing of the optical recording medium according to claim 10, wherein in forming the light transmission layer, an inclined surface starting to be inclined toward the outer periphery from a position of 1.0 mm or more and less than 1.5 mm at a distance from the outer peripheral end is formed. Method.   9. The formation of the light transmissive layer according to claim 8, wherein a region where the change in thickness of the light transmissive layer is ± 2 μm or less is formed to a position of 1.0 mm or more and less than 1.5 mm in distance from the outer peripheral edge. Of manufacturing an optical recording medium.