JP2010186561A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium having recording surfaces corresponding to a plurality of different formats and having compatibility capable of being loaded on an optical recording and reproducing device corresponding to different formats. <P>SOLUTION: In the optical recording medium wherein a first transparent substrate 11, a first recording surface 13, a second substrate 14, a second recording surface 16 and a third transparent substrate 17 are laminated, a laser beam L11 performing recording and reproduction of the first recording surface 13 is radiated from the first transparent substrate 11 side, a laser beam L12 performing recording and reproduction of the second recording surface 16 is radiated from the third transparent substrate 17 side, and the first and second recording surfaces 13 and 16 support different formats. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical recording medium having compatibility with different standards, such as a multilayer optical recording medium having a nonlinear light transmission layer.

  In recent years, high-density, large-capacity, high-speed access, and the like have been demanded for optical recording media due to progress in computerization. CD (Compact Disk), MO (Magnet-Optical disk), DVD (Digital Versatile Disk), etc. are widespread as large-capacity optical recording media, and blue laser is used as an optical recording medium capable of realizing a larger capacity. The used Blu-Ray Disk (hereinafter abbreviated as BD) and HD-DVD have been developed.

  In the above CD, a read-only CD-ROM using prepits as a recording layer, a one-time recordable CD-R using a dye film as a recording layer, and a rewrite using a phase change film as a recording layer There are three types of CD-RW types. As for the DVD and BD, similar to the CD, there are read-only, write-once, and rewritable optical discs.

Here, the CD, DVD, and BD will be described with reference to the drawings.
FIG. 12 is a cross-sectional view for explaining a main configuration when information is recorded on and reproduced from a CD. In the case of CD (single layer 650 MB), the wavelength of the semiconductor laser beam 125 for recording / reproducing is 780 nm, the numerical aperture NA of the objective lens 124 is 0.45, and the transparent substrate 121 having a thickness of about 1.2 mm is used. A protective layer 123 is provided on the opposite side of the recording layer 122 formed on the surface of the transparent substrate 121 from the transparent substrate 121. The laser beam 125 is condensed and irradiated from the transparent substrate 121 side to the recording layer 122 by the objective lens 124, and information is recorded and reproduced.

  Next, FIG. 13 is a cross-sectional view for explaining a main configuration when information is recorded / reproduced on / from a DVD. In the case of DVD (single layer 4.7 GB), the wavelength of the semiconductor laser light 137 for recording and reproduction is 650 nm, the NA of the objective lens 136 is 0.6, and the thickness of the transparent substrate 131 is 0.6 mm. By bonding the two substrates, the total thickness of the optical recording medium is 1.2 mm, which is the same as that of CD.

  In the single-sided dual-layer DVD shown in FIG. 13, two transparent substrates 131 and 135 each having a thickness of 0.6 mm have a recording layer 132 and a recording layer 134, and the intermediate layer 133 is arranged so that the recording layers face each other. The recording layer 132 or the recording layer 134 is recorded / reproduced by condensing and irradiating the laser beam 137 from the one transparent substrate 131 side with the objective lens 136.

  In general, the relationship between the light and the focused spot diameter is expressed by (converged spot diameter) ∝λ / NA using the wavelength λ of the laser beam and the numerical aperture NA of the objective lens. Therefore, in order to make the focused spot diameter smaller, it is necessary to shorten the wavelength λ and increase the numerical aperture NA.

On the other hand, when the thickness of the transparent substrate through which the laser beam passes is t, coma aberration proportional to (t / λ) × NA ³ occurs when the transparent substrate is tilted. When the wavelength λ is shortened and the numerical aperture NA is increased, the coma aberration increases, and it becomes impossible to maintain a perfect circular focusing spot with respect to the inclination of the transparent substrate. Therefore, in order to suppress the coma aberration and increase the recording density, it is necessary to reduce the thickness t of the transparent substrate.

  For this reason, the thickness of the DVD transparent substrate 131 that has been increased in density by shortening the wavelength and increasing the NA is half the thickness of the CD transparent substrate 121 (see FIG. 12). Yes.

  Next, FIG. 14 is a cross-sectional view for explaining a main configuration when recording / reproducing is performed on a BD. The BD has a structure in which a recording layer 143 is provided on a disk substrate 144 having a thickness of 1.1 mm, and a transparent cover layer 141 having a thickness of 0.1 mm is pasted with a transparent adhesive 142 so as to cover the recording layer 143. It has become. Information recording / reproduction with respect to the BD is performed by condensing and irradiating a laser beam 146 having a wavelength of 405 nm from the transparent cover layer 141 side to the recording layer 143 with an objective lens 145 having a numerical aperture NA of 0.85.

  Even in the BD, the increase in coma aberration due to the use of a short wavelength laser beam / high NA objective lens is suppressed by reducing the thickness of the transparent cover layer 141 through which the laser beam passes to 0.1 mm, thereby reducing the recording density. The increase of is realized.

  In addition, development of an optical disc called HD-DVD in which laser light having a wavelength of 405 nm is applied to a DVD is also in progress. In this HD-DVD, an objective lens having a numerical aperture NA of 0.6 is used, as in the DVD. A transparent substrate having a thickness of 0.6 mm is employed.

  As described above, there are optical recording media having shapes different from those of CD, DVD, BD, and HD-DVD. In these optical discs, the configuration of an optical recording medium capable of ensuring compatibility between BD and CD is described in Non-Patent Document 1 “1.2 mm-Thick Blu-ray / CD Dual Format discs” (Technical Digest of ISOM). '04, p150, 151). 1 is disclosed.

  FIG. 15 is a cross-sectional view of the optical recording medium described in Non-Patent Document 1. The optical recording medium includes a BD recording layer corresponding to the BD format via a 0.03 mm-thick intermediate layer 153 on a 1.1 mm-thick CD substrate 155 on which a CD recording layer 154 corresponding to the CD format is formed. 152 is provided, and a BD cover layer 151 having a thickness of 0.1 mm is provided on the BD recording layer 152. Here, recording / reproduction of the CD recording layer 154 is performed by collecting laser light 158 having a wavelength of 780 nm or 650 nm from the CD substrate 155 side to the CD recording layer 154 using an objective lens 159 having a numerical aperture NA of 0.45. This is performed by light irradiation. For recording / reproduction of the BD recording layer 152, a laser beam 156 having a wavelength of 405 nm is condensed and irradiated from the BD cover layer 151 side to the BD recording layer 152 using an objective lens 157 having a numerical aperture NA of 0.85. Is done.

  Normally, the thickness of the CD substrate is 1.2 mm, but the above document demonstrates that good reproduction characteristics can be obtained even when the thickness of the CD substrate 155 is 1.1 mm. Further, according to the above configuration, the total thickness of the optical recording medium is approximately 1.2 mm, so that the optical recording medium can be mounted on an apparatus capable of recording / reproducing a CD, and can be mounted on an apparatus capable of recording / reproducing a BD. It is also proposed that the optical recording medium can be mounted.

  Further, Non-Patent Document 1 also describes the optical recording medium shown in FIG. In the optical recording medium shown in FIG. 16, a CD recording layer 162 and a BD recording layer 164 are provided on both surfaces of a transparent substrate 163 having a thickness of 1.1 mm, and a protective layer 161 is provided on the CD recording layer 162. A BD cover layer 165 is provided on the layer 164. Here, recording / reproduction of the CD recording layer 162 is performed by applying laser light 168 having a wavelength of 780 nm or 650 nm from the BD cover layer 165 side to the CD recording layer 162 using an objective lens 169 having a numerical aperture NA of 0.45. This is performed by focused irradiation. Further, recording / reproduction of the BD recording layer 164 is performed by condensing and irradiating a laser beam 166 having a wavelength of 405 nm from the BD cover layer 165 side to the BD recording layer 164 using an objective lens 167 having a numerical aperture NA of 0.85. Is done.

  In many of these optical recording media, the optical recording media may have unique identification information from the viewpoint of copyright protection. In Patent Document 1, as shown in FIG. 17, a barcode-shaped BCA 170 is provided. The BCA 170 is a disc in which identification information (ID), an encryption key, and a decryption key that are different for each optical recording medium are recorded in the form of a bar code after the optical recording medium is manufactured. Irradiation with light causes the recording film itself to evaporate to form a non-rewritable barcode, and causes a non-rewritable alteration in the recording layer itself or the substrate around the recording layer. There is a reflectance control type BCA that reads changes in the amount of reflected light in a region.

JP 2000-173062 A (published on June 23, 2000)

Shin Masuhara et al., “1.2 mm-Thick Blu-ray / CD Dual Format discs”, Technical Digest of ISOM'04, p150, 151 (published on September 11, 2004)

  However, the optical recording medium according to the prior art shown in FIGS. 15 and 16 can provide an optical recording medium having both a CD and a BD format, but has both a BD and a DVD format. An optical recording medium cannot be provided.

  For example, when an optical recording medium having both BD and DVD formats is formed according to the prior art shown in FIG. 15, a 0.6 mm thickness in which a DVD recording layer 184 having the DVD format is formed as shown in FIG. A BD recording layer 182 having a BD format is provided on the DVD substrate 185 with a 0.03 mm thick intermediate layer 183, and a 0.1 mm thick BD cover layer 181 is provided on the BD recording layer 182. It becomes the composition which was made. In this case, the total thickness t of the optical recording medium is approximately 0.7 mm. Since both the DVD recording / reproducing apparatus and the BD recording / reproducing apparatus are assumed to be an optical recording medium having a thickness of 1.2 mm, the above-mentioned optical recording medium having a thickness of approximately 0.7 mm is used for both recording and reproducing apparatuses. This results in an optical recording medium that cannot be loaded.

  Also, in the optical recording medium having the configuration shown in FIG. 16, when an optical recording medium having both BD and DVD formats is formed, the total thickness of the optical recording medium is approximately 0.6 mm. As a result, there is a problem that the optical recording medium cannot be mounted on a BD recording / reproducing apparatus or a DVD recording / reproducing apparatus.

  Next, in the optical recording medium shown in FIGS. 15 and 18, the recording layers are adjacent to each other through intermediate layers 153 and 183 that are extremely thin with a thickness of 0.03 mm. Therefore, when each recording layer has the BCA 170, the light transmitted through the BCA 170 of one recording layer is reflected by the BCA 170 of the other recording layer, so that the BCA information of one recording layer becomes the other recording layer. There is a problem that an identification information reading error may occur.

  In addition, in the optical recording medium shown in FIG. 16, since the laser light 168 focused on the CD recording layer 162 is transmitted through the BD recording layer 164, the BCA 170 of the CD recording layer 162 and the BCA 170 of the BD recording layer 164 When the radial position and the like approach, the light for reading the BCA 170 in the CD recording layer 162 passes through the BCA 170 in the BD recording layer 164. As a result, there is a problem that reading error of identification information may occur by reading the BCA information superimposed on each recording layer.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an optical recording medium having compatibility that can be attached to an optical recording / reproducing apparatus compatible with a plurality of different formats.

  In order to solve the above problems, an optical recording medium according to the present invention is an optical recording medium in which a first transparent substrate or a first transparent cover layer, a first recording surface, a second recording surface, and a third substrate are laminated in this order. The first recording surface and the second recording surface correspond to different formats, and the first recording surface or the second recording surface is a write-once or rewritable recording surface, and the first recording surface The recording capacity of the surface and the recording capacity of the second recording surface are substantially equal.

  In the optical recording medium according to the present invention, the first recording surface or the second recording surface may be composed of multiple recording layers.

  In the optical recording medium according to the present invention, as described above, the first recording surface and the second recording surface correspond to different formats, and the first recording surface or the second recording surface is a write-once type or It is a rewritable recording surface, and the recording capacity of the first recording surface is substantially equal to the recording capacity of the second recording surface.

  Therefore, it is possible to provide a compatible optical recording medium that can be attached to an optical recording / reproducing apparatus compatible with a plurality of different formats.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a cross-sectional view illustrating a schematic configuration of a first optical recording medium of the present invention. It is sectional drawing which shows schematic structure of the recording layer which is a read-only type. It is sectional drawing which shows schematic structure of the recording layer which is a recordable type. It is sectional drawing which shows schematic structure of the recording layer which is a recordable type. FIG. 5 is a cross-sectional view showing a schematic configuration of a second optical recording medium of the present invention, showing another embodiment of the present invention. FIG. 5 is a cross-sectional view showing a schematic configuration in a case where a plurality of recording layers are formed on each recording surface in the second optical recording medium of the present invention, showing another embodiment of the present invention. Another embodiment of the present invention is a cross-sectional view showing a schematic configuration of a third optical recording medium (read-only type) of the present invention. Another embodiment of the present invention is a sectional view showing a schematic configuration of a third optical recording medium (recordable type) of the present invention. Another embodiment of the present invention is shown, and is a cross-sectional view showing a schematic configuration of a third optical recording medium (rewritable type) of the present invention. FIG. 10 is a perspective view illustrating another embodiment of the present invention and illustrating an outline of a BCA of a fourth optical recording medium of the present invention. It is sectional drawing of the surface parallel to the lamination direction of the recording layer expanded in order to demonstrate the positional relationship of BCA of FIG. FIG. 9 is a cross-sectional view of a main part that shows a conventional technique and performs recording / reproduction on a CD. It is a sectional view of the principal part which shows the prior art and performs recording and reproducing with respect to DVD. It is a sectional view of the principal part which shows a conventional technique and performs recording / reproduction on a BD. It is sectional drawing which shows the prior art and shows the outline of the optical recording medium provided with the recording / reproducing layer of BD and CD. It is sectional drawing which shows the prior art and shows the outline of the other optical recording medium provided with the recording / reproducing layer of BD and CD. It is a top view which shows the prior art and shows the outline of the optical recording medium provided with BCA. FIG. 16 is a cross-sectional view illustrating a conventional technique and realizing an optical recording medium including a recording / reproducing layer of BD and DVD using the configuration of the optical recording medium of FIG. 15.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 11 as follows. Each embodiment described below is only an example of an embodiment of the present invention, and the scope of the present invention is not limited to the scope of the following embodiment.

[First optical recording medium of the present invention]
A cross-sectional view of a first optical recording medium as an embodiment of the present invention is shown in FIG. As shown in the figure, the first optical recording medium of the present invention has a first transparent substrate 11, a first recording layer 13, a second substrate 14, a second recording layer 16, and a third transparent substrate 17 laminated thereon. It is a configuration. The transparent adhesive layer 12 is made of an adhesive that bonds the first transparent substrate 11 and the second substrate 14, and the transparent adhesive layer 15 is made of an adhesive for bonding the second substrate 14 and the third transparent substrate 17. It will be. In FIG. 1, the first transparent substrate 11 and the first recording layer 13 forming surface of the second substrate 14 are bonded together by the transparent adhesive layer 12, and the opposite side of the first recording layer 13 of the second substrate 14 by the adhesive layer 15. The side surface and the second recording layer 16 formation surface of the third transparent substrate 17 are bonded together. The first recording layer 13 and the second recording layer 16 each have a concave / convex pattern formed according to different formats, and a recording film and a reflective film are appropriately formed.

  Note that a substrate such as polycarbonate can be used for the first transparent substrate 11. The first transparent substrate 11 may have a thickness of about 100 μm and is not necessarily a substrate. The optical recording medium of the present embodiment may be provided with a cover layer produced by spin-coating an ultraviolet curable resin or the like, for example, instead of the first transparent substrate 11.

  As the first recording layer 13 and the second recording layer 16 (hereinafter, collectively referred to as “recording layer” as appropriate), there are three types: a read-only type, a write-once type, and a rewritable type. The configuration of these three types of recording layers will be described below with reference to FIGS.

  FIG. 2 shows a cross-sectional view when the recording layer is a read-only type. As shown in the figure, the read-only recording layer has a configuration in which a reflective film 22 such as Al is formed on a transparent substrate 21 provided with prepits 23, and the laser beam 25 is reflected by the objective lens 24. The pre-pit 23 is reproduced by focusing and irradiating on the film 22.

  Next, FIG. 3 shows a cross-sectional view when the recording layer is a recordable type. As shown in the figure, the recordable type recording layer has a configuration in which a recording layer composed of a phase change film 32 such as TeOx and a reflective film 33 is formed on a transparent substrate 31 provided with a guide groove 34. Yes, the objective lens 35 condenses and irradiates the recording layer with the laser beam 36, and information is recorded and reproduced.

Next, FIG. 4 shows a cross-sectional view of the rewritable type. As shown in the figure, a transparent dielectric film 42 such as ZnS-SiO ₂ , a phase change recording film 43 such as GeSbTe, and a transparent dielectric such as ZnS-SiO ₂ are formed on a transparent substrate 41 provided with guide grooves 46. A recording film composed of a film 44 and a reflective film 45 such as Al is formed, and a laser beam 48 is condensed and irradiated onto the recording layer by the objective lens 47, and information is recorded and reproduced.

  As described above, there are three types of recording layers: a read-only type, a write-once type, and a rewritable type. Hereinafter, these three types will be described without distinction.

  Recording / reproduction on the first optical recording medium according to the embodiment of the present invention is performed as follows. As shown in FIG. 1, the first laser light L11 irradiated from the first transparent substrate 11 side is condensed onto the first recording layer 13 by the first objective lens CL11, and the information on the first recording layer 13 is transferred. Recording and / or reproduction of information recorded on the first recording layer 13 is performed. Further, the second laser beam L12 irradiated from the third transparent substrate 17 side is condensed onto the second recording layer 16 by the second objective lens CL12, and recording / reproduction of the second recording layer 16 is performed.

  With the above configuration, stable recording and reproduction can be realized. That is, when recording / reproducing on the first recording surface composed of the first recording layer 13, the first laser light L 11 is transmitted only through the first transparent substrate 11 and the transparent adhesive layer 12, thereby the first recording layer. 13 can be recorded and reproduced. Further, when performing recording / reproduction on the second recording surface composed of the second recording layer 16, the second laser light L <b> 12 transmits only the third transparent substrate 17 to perform recording / reproduction on the second recording layer 16. It can be realized. As a result, it is possible to realize stable recording / reproduction similar to that of the conventional optical recording medium without passing through the other recording layer for each recording layer.

  Here, it is desirable to set the thickness of the second substrate 14 so that the compatibility of the optical recording medium of the present invention can be ensured. For example, when the first recording layer 13 is a recording layer corresponding to the BD format, the wavelength of the first laser light L11 is 405 nm, the numerical aperture NA of the first objective lens CL11 is 0.85, and the first The thickness of the transparent substrate 11 is approximately 0.1 mm. When the second recording layer 16 is a recording layer corresponding to the HD-DVD format, the wavelength of the second laser light L12 is 405 nm, the numerical aperture NA of the second objective lens CL12 is 0.60, The thickness of the third transparent substrate 17 is approximately 0.6 mm.

  In general, in an optical recording medium, the total thickness of the optical recording medium is uniform in order to ensure compatibility such as chucking. For example, the total thickness of CD, DVD, and BD is all the same 1.2 mm.

  Here, in the first optical recording medium of the present embodiment, the thickness of the first transparent substrate 11 is 0.1 mm, and the thickness of the third transparent substrate 16 is 0.6 mm. It is desirable that the thickness of the substrate 14 is approximately 0.5 mm and the total thickness of the optical recording medium is 1.2 mm. Here, although the thickness of the transparent adhesive layers 12 and 15 (hereinafter referred to as “adhesive layer” where appropriate) is ignored, the thickness of the adhesive layer is so thick that it cannot be ignored. In this case, it is desirable to reduce the thickness of the second substrate 14 by the thickness of the adhesive layer.

  As described above, the first optical recording medium of the present embodiment is adjusted to the BD format only by adjusting the thickness of the second substrate 14 and setting the total thickness t of the optical recording medium to 1.2 mm. It is possible to provide an optical recording medium that can be chucked to both the corresponding recording / reproducing apparatus and the recording / reproducing apparatus that supports only the HD-DVD format.

  In the above-described embodiment, the optical recording medium in which the first recording layer 13 corresponds to the BD format and the second recording layer 16 corresponds to the HD-DVD format has been described. In the optical recording medium corresponding to the BD format and the second recording layer 15 corresponding to the DVD format, similarly, by setting the thickness of the second substrate 14 to 0.5 mm, both the BD format and the DVD format are used. It is possible to provide an optical recording medium having compatibility.

  In addition, since BD recording / reproducing apparatuses that are not compatible with two-layer recording / reproduction are currently on the market, for example, the first recording surface has a BD-format two-layer recording layer, and the second The recording surface may have a single recording layer of BD format. By adopting such a configuration, for example, it is possible to provide an optical recording medium having a configuration in which a 4-hour image with HD image quality is recorded on a two-layer recording surface and a similar program is recorded with SD image quality for 4 hours. Thus, a similar program can be viewed even on models that do not support two-layer recording.

  Here, the second substrate 14 of the first optical recording medium of the present embodiment will be further described. The second substrate 14 is not an adhesive layer produced by spin coating an ultraviolet curable resin or the like, but a substrate such as a polycarbonate sheet. This makes it easy to adjust the total thickness of the optical recording medium to 1.2 mm. With an adhesive, it is difficult to smooth a layer having a thickness of 100 μm or more. Even in an existing optical recording medium, an adhesive layer having an adhesive layer of 100 μm or less is used. In the first optical recording medium, the laser beam for recording / reproducing on the recording layer passes through the first transparent substrate 11 or the third transparent substrate 17 but does not pass through the second substrate 14. It is not necessary to use a material capable of transmitting light as the second substrate 14. Accordingly, various materials can be selected as the second substrate 14 as appropriate.

  For example, by using a metal sheet such as a highly rigid stainless sheet as the second substrate 14, the mechanical strength of the optical recording medium is increased, deformation such as warpage is prevented, and a high-quality optical recording medium is provided. Is possible. Further, by using a paper sheet as the second substrate 14, it is possible to reduce the cost of the optical recording medium.

  In addition, the first optical recording medium of the present embodiment, when reproducing the first recording surface composed of the first recording layer 13 and the second recording surface composed of the second recording layer 16 at the same wavelength, respectively. These recording surfaces can be recorded and reproduced independently. On the other hand, for example, in the conventional technique shown in FIG. 16, two recording surfaces (CD recording layer 162 and BD recording layer 164) are formed on the same substrate with laser beams having different wavelengths (laser beam 169 and laser beam 167). In this case, by using a translucent reflective film having wavelength selectivity as the BD recording layer 164, the two recording surfaces can be recorded and reproduced independently ( Fig. 2 of Non-Patent Document 1).

  However, when recording and reproducing the two recording surfaces with laser light having the same wavelength, the semi-transparent reflective film having the wavelength selectivity cannot be used for the second recording layer 16 in FIG. For this reason, the thickness of the reflective film constituting the second recording layer 16 is reduced to form a translucent reflective film. In this case, the reflectance and transmittance of each recording layer are set so that the reflected light intensity from the first recording layer 13 and the reflected light intensity from the second recording layer 16 are substantially equal. However, as described above, the second recording layer 16 is a semi-transparent reflective film by reducing the thickness of the reflective film, and has no wavelength selectivity. For this reason, since it is necessary to increase the intensity of the laser beam incident on each recording layer, a high-power semiconductor laser light source is required.

  On the other hand, in the optical recording medium of the present invention, one recording surface is directly irradiated with laser light without passing through the other recording surface. For this reason, even when recording / reproduction is performed using laser light having substantially the same wavelength as in BD and HD-DVD, for example, recording / reproduction on both recording surfaces is performed using a low-power semiconductor laser light source. Therefore, it can be performed appropriately.

[First Method for Manufacturing Recording Medium of the Present Invention]
A manufacturing method (forming method) of the first optical recording medium of the present embodiment shown in FIG. 1 will be described below.
In the first optical recording medium, a second substrate 14 on which a first recording layer 13 is formed is bonded to a third transparent substrate 17 on which a second recording layer 16 is formed by an adhesive 15, and the second substrate The first transparent substrate 11 is bonded to the first recording layer 13 formed on the surface of the first recording layer 13 with the transparent adhesive 12.

  For example, when the first recording layer 13 corresponds to the BD format and the second recording layer 16 corresponds to the HD-DVD format, the thicknesses of the first transparent substrate 11, the second substrate 14, and the third transparent substrate 17. Are approximately 0.1 mm, 0.5 mm, and 0.6 mm, respectively. Here, according to the manufacturing method, the first recording surface made of the first recording layer 13 is provided on the second substrate 14 having a thickness of 0.5 mm, and the second recording surface made of the second recording layer 16 is It will be provided on the third transparent substrate 17 of 0.6 mm. Thus, since the thickness of the substrate on which the recording layer is provided is relatively thick, 0.5 mm to 0.6 mm, recording is performed using an injection molding method or a photopolymer method (2P method) as in the conventional case. An uneven pattern for information and tracking can be formed on the surface of the substrate, and the formation cost of the optical recording medium can be reduced.

  In addition, the manufacturing method of the first optical recording medium is not limited to the above-described manufacturing method, and the first recording surface and the second recording layer formed of the first recording layer 13 are formed on both surfaces of the second substrate 14, respectively. After forming the second recording surface 16, the first transparent substrate 11 is bonded to the first recording surface side, and the third transparent substrate 17 is bonded to the second recording surface side by a transparent adhesive, whereby light A recording medium may be formed. In this case, it is possible to form the concave / convex pattern for recording information and tracking at the same time on both surfaces of the second substrate 14, so that the formation process is further simplified. According to this manufacturing method, the adhesive layer 15 is positioned not between the second substrate 14 and the second recording layer 16 but between the second recording layer 16 and the third transparent substrate 17. In this respect, an optical recording medium different from that shown in FIG. 1 is obtained.

  A first recording surface made of the first recording layer 13 is formed on the first transparent substrate 11 having the concavo-convex pattern, and a second recording surface made of the second recording layer 16 is formed on the third transparent substrate 17 having the concavo-convex pattern. After forming the optical recording medium of the present invention, the first transparent substrate 11 and the third transparent substrate 17 are bonded to the second substrate 14 with an adhesive. According to this manufacturing method, the transparent adhesive layer 12 is positioned not between the first transparent substrate 11 and the first recording layer 13 but between the first recording layer 13 and the second substrate 14. Thus, an optical recording medium different from that shown in FIG. 1 is obtained.

  In this case, since the laser beam does not pass through the adhesive layer for recording / reproduction of the recording layer, it is possible to use an adhesive that does not easily transmit light. For example, by using an inexpensive double-sided pressure-sensitive adhesive tape or the like as the adhesive layer, the cost of the optical recording medium can be reduced and the bonding process can be simplified.

  At present, the optical system is becoming denser with a shorter wavelength and higher NA in order to increase the density of the optical recording medium. However, it is difficult to secure a margin for the tilt angle of the disk. On the other hand, for example, by using a substrate having high mechanical strength including metal as the second substrate, it is possible to prevent warping of the optical recording medium and reduce recording errors and reading errors due to tilt.

[Second optical recording medium of the present invention]
FIG. 5 shows a sectional view of a second optical recording medium as another embodiment of the present invention. As shown in the figure, the second optical recording medium of the present embodiment includes a first transparent substrate 51, a first recording layer 53, a second substrate 54, a second recording layer 55, a third recording layer 57, and a third recording layer. The transparent substrate 58 is laminated. The transparent adhesive layer 52 is made of an adhesive for bonding the first transparent substrate 51 and the second substrate 54, and the transparent adhesive layer 56 is for bonding the second substrate 54 and the third transparent substrate 58. It consists of an adhesive. Hereinafter, when the transparent adhesive layer 52 and the transparent adhesive layer 56 are not distinguished from each other, they are appropriately referred to as “adhesive layer”.

  In addition, the second recording layer 55 and the third recording layer 57 have a concavo-convex pattern according to the same format, and the first recording layer 53 follows a format different from that of the second recording layer 55 and the third recording layer 57. It has an uneven pattern. In addition, in the first recording layer 53, the second recording layer 55, and the third recording layer 57 (hereinafter referred to as “recording layer” as appropriate when they are not distinguished from each other), a recording film or a reflective film is appropriately formed. Has been.

  Recording / reproduction on the second optical recording medium of the present embodiment is performed as follows. Recording and reproduction with respect to the first recording surface made of the first recording layer 53 is performed from the first transparent substrate 51 side, as in the first optical recording medium described above. On the other hand, recording / reproduction with respect to the second recording surface including the second recording layer 55 and the third recording layer 56 is performed from the third transparent substrate 58 side. Here, recording / reproduction on the second recording layer 55 is performed by transmitting the second laser light L52 irradiated from the third transparent substrate 58 side through the third recording layer 57. Therefore, in the second optical recording medium of the present embodiment, the third recording layer 57 is a light-transmitting recording layer, and the reflected light amount of the second laser light from the second recording layer 55 and the third recording layer 57. It is desirable to set the transmittance so that the two are substantially equal.

  Here, it is desirable to set the thickness of the second substrate 54 so that the compatibility of the optical recording medium of the present embodiment can be ensured. For example, when the first recording layer 53 is a recording layer corresponding to the BD format, the wavelength of the first laser beam L51 is 405 nm, the numerical aperture NA of the first objective lens CL51 is 0.85, and the first The thickness of the transparent substrate 51 is 0.1 mm. When the second recording layer 55 and the third recording layer 57 are recording layers corresponding to the HD-DVD format, the wavelength of the second laser light L52 is 405 nm, and the numerical aperture NA of the second objective lens CL52. Is 0.60, and the thickness of the third transparent substrate 58 is 0.6 mm.

  In general, in an optical recording medium, the total thickness of the optical recording medium is uniform in order to ensure compatibility such as chucking. For example, the total thickness of CD, DVD, and BD is all the same 1.2 mm.

  Here, in this embodiment, since the thickness of the first transparent substrate 51 is 0.1 mm and the thickness of the third transparent substrate 58 is 0.6 mm, the thickness of the second substrate 54 is set to 0. It is desirable that the total thickness of the optical recording medium is 1.2 mm with 5 mm. Here, the thickness of the adhesive layer is neglected, but when the thickness of the adhesive layer becomes so thick that it cannot be ignored, the thickness of the second substrate 54 is set to the thickness of the adhesive layer. It is desirable to make it thinner.

  As described above, the optical recording medium of this embodiment adjusts the thickness of the second substrate 54 so that the total thickness of the optical recording medium is 1.2 mm. On the other hand, it is possible to provide an optical recording medium that can be chucked even by a recording / reproducing apparatus that supports only the HD-DVD format.

  Further, since the BD uses an objective lens CL51 having a numerical aperture NA of 0.85, and the HD-DVD uses an objective lens CL52 having a numerical aperture NA of 0.6, the recording density of the BD is HD-DVD. Approximately twice the recording density. Therefore, in the first optical recording medium shown in FIG. 1, the recording capacity of the first recording layer 13 is about twice the recording capacity of the second recording layer 16. For this reason, when recording / reproduction is performed under the same conditions, only half the information of the first recording surface consisting of the first recording layer 13 can be recorded on the second recording surface consisting of the second recording layer 16.

  On the other hand, in the second optical recording medium of the present embodiment, the first recording surface including the first recording layer 53 conforming to the BD format, the second recording layer 55 and the third recording layer 57 conforming to the HD-DVD format, A second recording surface is formed. For this reason, since the recording capacity of the first recording surface and the recording capacity of the second recording surface are substantially equal, it is possible to perform recording with the same capacity for each format under the same conditions.

  Also in the second optical recording medium of the present embodiment, it is not necessary to use a light transmissive material for the second substrate 54 as in the first optical recording medium described above. Accordingly, various materials can be selected as appropriate for the second substrate 54. As the second substrate 54, for example, a stainless sheet or a paper sheet can be used.

[Second Method for Manufacturing Recording Medium of the Present Invention]
A manufacturing method (forming method) of the second optical recording medium of the present embodiment shown in FIG. 5 will be described below. In the second optical recording medium, a second substrate 54 having a first recording layer 53 and a second recording layer 55 formed on both sides is provided on a third transparent substrate 58 on which a third recording layer 57 is formed. The second recording layer 55 is bonded to the third recording layer 57 side by a transparent adhesive 56, and the first transparent substrate 51 is bonded to the first recording layer 53 of the second substrate 54 by the transparent adhesive 52. It can be manufactured by combining them.

  For example, when the first recording layer 53 is made to correspond to the BD format and the second recording layer 55 and the third recording layer 57 are made to correspond to the HD-DVD format, the first transparent substrate 51, the second substrate 54, and the The thicknesses of the three transparent substrates 58 are approximately 0.1 mm, 0.5 mm, and 0.6 mm, respectively. Here, according to the above manufacturing method, the first recording layer 53 and the second recording layer 55 are provided on both surfaces of the second substrate 54 having a thickness of 0.5 mm, and the third recording layer 57 is a third layer having a thickness of 0.6 mm. It will be provided on the transparent substrate 58. Thus, since the thickness of the substrate on which the recording layer is provided is relatively thick, 0.5 mm to 0.6 mm, recording is performed using an injection molding method or a photopolymer method (2P method) as in the conventional case. An uneven pattern for information and tracking can be formed on the surface of the substrate, and the formation cost of the optical recording medium can be reduced.

  Further, the manufacturing method of the second optical recording medium is not limited to the manufacturing method described above, and the third recording layer 57 and the second recording layer 55 are formed by the injection molding method or the photopolymer method. A second substrate 54 on which a first recording layer 53 is formed by an injection molding method or a photopolymer method is bonded to a transparent substrate 58 with an adhesive, and the first transparent substrate 51 is transparent on the first recording layer 53. The optical recording medium may be formed by bonding with an adhesive 52. According to this manufacturing method, the transparent adhesive layer 56 is positioned not between the second recording layer 55 and the third recording layer 57 but between the second recording layer 55 and the second substrate 54. Thus, an optical recording medium different from that shown in FIG. 5 is obtained.

  Also in this case, the first recording layer 53, the second recording layer 55, and the third recording layer 57 are formed on the second substrate 54 or the third transparent substrate 58 that is relatively thick, 0.5 mm to 0.6 mm. be able to. For this reason, since the recording information and the concave / convex pattern for tracking can be formed on the surface of the substrate using the same method as in the prior art, it is possible to reduce the cost of forming the optical recording medium.

  In addition, after forming the first recording layer 53 on the first transparent substrate 51 having the concavo-convex pattern and forming the third recording layer 57 and the second recording layer 55 on the third transparent substrate 57, the first transparent substrate The optical recording medium of the present invention can also be formed by bonding 51 and the third transparent substrate 58 to the second substrate 54 with an adhesive. According to this manufacturing method, the transparent adhesive layer 56 is located not between the second recording layer 55 and the third recording layer 57 but between the second recording layer 55 and the second substrate 54, and thus transparent. 5 in that the adhesive layer 52 is positioned not between the first transparent substrate 51 and the first recording layer 53 but between the first recording layer 53 and the second substrate 54. Different optical recording media can be obtained.

  In this case, since the laser beam does not pass through the adhesive layer for recording / reproduction of the recording layer, it is possible to use an adhesive that does not easily transmit light. For example, by using an inexpensive double-sided adhesive tape or the like, the cost of the optical recording medium can be reduced, and the bonding process can be simplified.

  In the above-described embodiment, the optical recording medium corresponding to the BD format as the first recording layer 53 and the HD-DVD format as the second recording layer 55 and the third recording layer 57 has been described. Even in an optical recording medium corresponding to the BD format as the first recording layer 53 and corresponding to the DVD format as the second recording layer 55 and the third recording layer 58, by setting the thickness of the second substrate 54 to 0.5 mm, It is possible to provide an optical recording medium that is compatible with both the BD format and the DVD format.

  In this case, in the case of the BD format, the optical disk has a diameter of 120 mm and has a storage capacity of 25 GB. In the case of the DVD format, the storage capacity is 4.7 GB with the same diameter. In order to ensure the same storage capacity, it is desirable to provide approximately five DVD format recording layers for one BD format recording layer. Thus, in order to stack a plurality of recording layers, it is desirable to sequentially stack the recording layers on the second substrate 58 using the photopolymer method.

  As shown in FIG. 6, when the first transparent substrate 61 or the second substrate 63 has a first recording surface composed of two recording layers 62 corresponding to the BD format, the second substrate 63 or the third transparent substrate By providing the substrate 65 with the second recording surface comprising the four recording layers 64 corresponding to the HD-DVD format, the recording capacity of the first recording surface comprising the recording layer 62 and the second recording surface comprising the recording layer 64 are provided. Recording capacity becomes equal. As shown in FIG. 6, information recording / reproduction on the first recording surface composed of the two recording layers 62 is performed by condensing the laser beam L61 on the first recording surface with the objective lens CL61. Recording / reproduction on the second recording surface composed of the recording layer 64 is performed by condensing the laser beam L62 on the first recording surface with the objective lens CL62.

  As described above, in the second optical recording medium of the present embodiment, each recording is performed so that the total storage capacity determined by each format is equal in the optical recording medium having recording layers corresponding to different formats. By determining the number of recording layers that constitute the surface, it is possible to perform recording with the same capacity for each format under the same conditions.

[Third optical recording medium of the present invention]
The third optical recording medium according to another embodiment of the present invention is the same as the first optical recording medium of the present invention except that a nonlinear optical layer is provided on the light incident side of the recording layer. It is a configuration. 7, 8 and 9 are sectional views of the recording layer of the third optical recording medium of the present invention.

  FIG. 7 shows a cross-sectional view when the third optical recording medium is a read-only type. As shown in the figure, a non-linear optical film 72 and a reflection film 73 made of Al or the like are formed on a transparent substrate 71 provided with prepits 74. Laser light 76 is condensed and irradiated onto the nonlinear optical film 72 and the reflective film 73 by the objective lens 75, and the prepit 74 is reproduced.

  Here, as the non-linear optical film 72, a thin film such as ZnO, CeOx, TiOx or the like whose refractive index, light transmittance, or light reflectance changes due to a temperature rise accompanying the irradiation of the laser beam 76, or a minute region due to the near-field effect. It is possible to use a thin film such as PtOx or AgOx that can utilize the super lens effect in which the amount of reflected light increases.

  By providing these nonlinear optical films, super-resolution reproduction capable of reproducing only a part of information in a light beam spot formed by condensing and irradiating the laser beam 76 is realized, and normal optical recording is performed. It is possible to realize a recording capacity twice that of the medium. In the above embodiment, a nonlinear optical film may be formed between the laser beam incident side and the reflective film with respect to the recording surface.

  Next, FIG. 8 shows a cross-sectional view when the third optical recording medium is a recordable type. As shown in the figure, on a transparent substrate 81 provided with a guide groove 85, a recording layer comprising a non-linear optical film 82, a phase change film 83 such as TeOx, and a reflective film 84 is formed. As a result, the laser beam 87 is condensed and applied to the recording layer, and information is recorded and reproduced. In the case of the recordable type, similarly to the read-only type, by providing the nonlinear optical film 82, it is possible to realize a recording capacity twice that of a normal optical recording medium.

Next, FIG. 9 shows a cross-sectional view of the third optical recording medium of the rewritable type. As shown in the drawing, the guide groove 97 on the transparent substrate 91 provided, ZnS-SiO ₂ transparent dielectric film 92 such as a transparent dielectric film 94 such as a nonlinear optical film 93, ZnS-SiO _2, GeSbTe A recording film composed of a phase change recording film 95 such as ZnS—SiO _{2 and} a transparent dielectric film 96 such as ZnS—SiO ₂ is formed. . In the case of the rewritable type as well as the read-only type, by providing the non-linear optical film 93, it is possible to realize a recording capacity twice that of a normal optical recording medium.

  The recording layer having the nonlinear optical film as described above is used for both the first recording layer 13 and the second recording layer 16 of the first optical recording medium of the present invention shown in FIG. It is possible to provide the third optical recording medium of the present embodiment, which is an optical recording medium having a recording capacity twice that of the above optical recording medium.

  In FIG. 1, the first recording surface formed of the first recording layer 13 is a recording surface using a laser beam L11 having a wavelength of 405 nm corresponding to the BD format and an objective lens CL11 having a numerical aperture NA of 0.85. When the second recording surface consisting of two recording surfaces 16 is a recording surface using a laser beam L12 having a wavelength of 405 nm corresponding to the HD-DVD format and an objective lens CL12 having a numerical aperture NA of 0.6, a nonlinear optical film Is not used, the recording capacity of the first recording surface becomes twice the recording capacity of the second recording surface due to the difference in the numerical aperture NA of the objective lens that records and reproduces the first recording surface and the second recording surface. It becomes impossible to perform recording of the same capacity on the first recording surface and the second recording surface under the same conditions.

  Here, in FIG. 1, a recording layer not having a nonlinear optical film is formed on the first recording surface corresponding to the BD format, and the nonlinear optical on the second recording surface that can be reproduced by the optical system corresponding to the HD-DVD format. By forming a recording layer having a film, only the recording capacity of the second recording surface is doubled by super-resolution reproduction of the nonlinear optical film, and the recording capacities of the first recording surface and the second recording surface are made equal. Can do.

  That is, according to the above configuration, in an optical recording medium having recording layers corresponding to different formats, one recording layer constituting each recording surface is arranged so that the total storage capacity determined by each format is equal. A nonlinear optical film can be provided. Thus, the third optical recording medium of the present invention can perform recording of the same capacity for each format under the same conditions.

[Fourth Optical Recording Medium of the Present Invention]
As shown in FIG. 10, the fourth optical recording medium of the present invention is the first recording surface 101 and the second recording surface 102 of the first to third optical recording media according to the embodiment of the present invention described above. Both have a configuration in which the BCA 103 is provided.

  FIG. 10 shows both the BD recording layer 152 corresponding to the first recording surface 101 and the CD recording layer 154 corresponding to the second recording surface 102 with respect to the conventional optical recording medium having the configuration shown in FIG. In this way, when the light transmission type BCA 103 composed of a stripe pattern row having a width of 50 μm is formed, the thickness of the intermediate layer 153 is as thin as 10 μm to 30 μm. Reflected by the BD recording layer 152. Here, when the BCA 103 of the BD recording layer 152 is formed at the same radial position as the second recording surface 154, the reflected light from the BD recording layer 152 is modulated by the presence or absence of the pattern of the BCA 103 of the CD recording layer 154. Will be. As a result, the information of the BCA 103 of the CD recording layer 154 is mixed into the information of the BCA 103 of the BD recording layer 152, and a BCA information reading error occurs.

  On the other hand, any of the first to third optical recording media according to the embodiment of the present invention has a thickness of about 0.5 mm between the first recording surface 101 and the second recording surface 102. Two substrates (second substrate 14, second substrate 54, second substrate 63) are provided, and the distance between the first recording surface 101 and the second recording surface 102 is wide. Therefore, even if the laser beam that has passed through the BCA 103 on the first recording surface 101 is reflected on the second recording surface 102, the reflected light is diffused, so that the BCA information on the first recording surface 101 is added to the second recording surface 102. Therefore, the BCA information on each recording surface can be stably reproduced.

  Further, by using a material that does not transmit laser light, for example, an opaque resin substrate, a stainless sheet, a paper sheet, or the like as the second substrate, the BCA information on the first recording surface 101 and the BCA information on the second recording surface 102 Thus, the BCA information on each recording surface can be stably reproduced.

  In the conventional optical recording medium having the configuration shown in FIG. 16, the laser beam 168 for reproducing the CD recording layer 162 corresponding to the first recording surface 101 passes through the BD recording layer 164 corresponding to the second recording surface 102. Since the light is transmitted and condensed and irradiated, the BCA information formed on the BD recording layer 164 is mixed as noise in the BCA information of the CD recording layer 162, resulting in a reading error of the BCA information. .

FIG. 11 is an enlarged cross-sectional view showing the vicinity of the BCA 103 in FIG. 10. The BCA 103 on the first recording surface 101 and the BCA 103 on the second recording surface 102 are viewed from the center of each recording surface of the optical recording medium. The relationship of distance (radius position) is shown. In the example shown in FIG. 11, the radial positions on the inner peripheral side and the outer peripheral side of the BCA 103 formed on the first recording surface 101 are a1 and b1, respectively, and the inner peripheral side and the outer peripheral side of the BCA 103 formed on the second recording surface 102 are shown. Are indicated by a2 and b2, respectively. Here, when the distance between the first recording surface 101 and the second recording surface 102 is d, the numerical aperture of the objective lens for condensing the laser beam 104 is NA1, and the refractive index of the substrate is n1, as shown in FIG. The angle θ between the optical axis of the laser beam 104 and the outer edge of the laser beam 104 is represented by θ = sin ⁻¹ (NA1 / n1).

At this time, when the radial positions of the BCAs satisfy the relationship of the following expressions (1) and (2), the laser beam that reproduces the BCA 103 on the first recording surface 101 is BCA 103 on the second recording surface 102. There is a possibility that the superimposed signal is reproduced and an error in reading the BCA information occurs.
b1> a1-d × tan (sin ⁻¹ (NA1 / n1)) (1)
b2 <a2 + d × tan (sin ⁻¹ (NA1 / n1)) (2)
However, in the fourth optical recording medium of the present embodiment, the laser beam that reproduces information on each recording surface (the first recording surface 101 and the second recording surface 102) does not pass through the other recording surface, that is, When reproducing information on one recording surface, the laser beam does not pass through the other recording surface, and only the recording surface that reproduces the information is irradiated. Each BCA information can be reproduced independently even if the positional relationship satisfies the relationship of the expressions (1) and (2).

  As described above, in the optical recording medium of the present embodiment, the information on the BCA 103 on the first recording surface 101 and the second recording surface 102 can be reproduced independently. Therefore, even when at least part of the BCA 103 of the first recording surface 101 and the second recording surface 102 is formed in a region overlapping in the stacking direction of the recording layers, the information of the BCA 103 of the first recording surface 101 and the first information 2 Information on the BCA 103 on the recording surface 102 can be read accurately.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The optical recording medium of the present invention has the following configuration as means for solving the above problems.

  The optical recording medium of the present invention is an optical recording medium in which the first transparent substrate or the first transparent cover layer, the first recording surface, the second substrate, the second recording surface, and the third transparent substrate are laminated in this order. The one recording surface and the second recording surface correspond to different formats, and information is recorded and / or reproduced by laser light irradiated from the first transparent substrate side and the third transparent substrate side in this order, respectively. An optical recording medium characterized by that.

  According to the above invention, both when recording and reproducing information on the first recording surface and when recording and reproducing information on the second recording surface, without passing through the other recording surface, Each recording surface can be irradiated with laser light. This makes it possible to realize stable recording / reproduction similar to that of a conventional optical recording medium.

  Further, by adjusting the thickness of the second substrate, the entire thickness of the optical recording medium can be made predetermined. Thereby, since the total thickness of the optical recording medium can be easily adjusted, the compatibility of different formats can be ensured with respect to the total thickness of the optical recording medium.

  The optical recording medium of the present invention may be configured such that the first recording surface is a recording surface corresponding to the BD format, and the second recording surface is a recording surface corresponding to the HD-DVD format or the DVD format.

  According to the above invention, in the optical recording medium having a recording surface corresponding to the BD format and a recording surface corresponding to the HD-DVD format or the DVD format, the other recording surface is transmitted through each recording surface. Therefore, stable recording / reproduction similar to that of the conventional optical recording medium can be realized.

  In the optical recording medium of the present invention, the thickness of the optical recording medium is preferably the thickness of the optical recording medium corresponding to the BD format.

  According to the above invention, by adjusting the thickness of the second substrate, the thickness of the optical recording medium corresponding to the BD format can be made equal. An example of setting the thickness of the second substrate is a configuration in which the total thickness of the optical recording medium is 1.2 mm. As a result, it is possible to provide an optical recording medium that can be chucked to both a recording / reproducing apparatus that supports only the BD format and a recording / reproducing apparatus that supports only the HD-DVD format.

  In the optical recording medium of the present invention, the first recording surface and / or the second recording surface may be composed of a plurality of recording layers. In this case, it is preferable that the recording capacity of the first recording surface is approximately equal to the recording capacity of the second recording surface.

  According to the invention described above, the recording density of the optical recording medium is increased by using one or both of the first recording surface and the second recording surface as a recording surface composed of a plurality of recording layers. It becomes possible to make it. In addition, by making the recording capacity of the first recording surface equal to the recording capacity of the second recording surface, it is possible to perform recording of the same capacity for each format under the same conditions. For this reason, for example, when recording the same program on a recording surface of a different format, it becomes possible to perform signal processing at the same compression rate and to record, and to perform signal processing at a compression rate corresponding to each recording surface. Can be performed and recorded. For this reason, since it is not necessary to perform signal processing at a compression rate corresponding to each recording surface, it is possible to reduce the cost for signal processing when manufacturing one media package.

  In order to make the recording capacity of the first recording surface substantially equal to the recording capacity of the second recording surface, for example, the first recording surface is constituted by one recording layer corresponding to the BD format. The second recording surface may be constituted by two recording layers corresponding to the HD-DVD format.

  According to the above invention, the recording capacity 25 GB of the first recording surface composed of one recording layer corresponding to the BD format and the recording capacity of the second recording surface composed of two recording layers corresponding to the HD-DVD format. Since 30 GB is substantially equal, it is possible to perform recording of the same capacity for each format under the same conditions.

  In addition to the above configuration, the first recording surface is composed of two recording layers corresponding to the BD format, and the second recording surface is composed of four recording layers corresponding to the HD-DVD format. Even in this case, the recording capacity of the first recording surface and the recording capacity of the second recording surface can be made substantially equal.

  According to the above invention, the recording capacity of the first recording surface composed of two recording layers corresponding to the BD format, and the recording capacity of the second recording surface composed of four recording layers corresponding to the HD-DVD format, Therefore, it is possible to perform recording of the same capacity for each format under the same conditions.

  In addition to the above configuration, the first recording surface is composed of one recording layer corresponding to the BD format, and the second recording surface is composed of five recording layers corresponding to the DVD format. Also, the recording capacity of the first recording surface and the recording capacity of about 23.5 GB of the second recording surface can be made substantially equal.

  According to the above invention, the recording capacity of the first recording surface consisting of one recording layer corresponding to the BD format, and the recording capacity of the second recording surface consisting of five recording layers corresponding to the DVD format, Since they can be made substantially equal, it is possible to perform recording of the same capacity for each format under the same conditions.

  In the optical recording medium of the present invention, the wavelength of the laser beam for recording / reproducing information on the first recording surface is substantially equal to the wavelength of the laser beam for recording / reproducing information on the second recording surface. There may be.

  The first recording surface and the second recording surface of the optical recording medium of the present invention are recorded and / or recorded with laser light irradiated in this order from the first transparent substrate side and the third transparent substrate side, respectively. Since the information is reproduced, information is recorded and reproduced by directly irradiating one recording surface with laser light without passing through the other recording surface of the first and second recording surfaces. Can do. For this reason, for example, even when information is recorded / reproduced by using a laser beam having substantially the same wavelength, such as BD and HD-DVD, the information on one recording surface can be transferred without passing through the other recording surface. Can be recorded and played back. Therefore, recording and reproduction on both recording surfaces can be appropriately performed using a low-power semiconductor laser light source.

  For example, there are parts with a wavelength of about 620 nm to 670 nm due to differences in standards and manufacturing variations of semiconductor lasers in the pickup parts of a DVD recording / reproducing apparatus, and in BD and HD-DVD recording / reproducing apparatuses, the wavelength There is a distribution of about 10 nm before and after 405 nm. Therefore, in the present invention, the wavelength is “substantially equal” means that the wavelength of the laser beam that records and reproduces information on the first recording surface and the wavelength of the laser beam that records and reproduces information on the second recording surface. The difference is within about 40 nm.

  The second substrate of the optical recording medium of the present invention may be composed of, for example, a metal sheet or a paper sheet. By using the second substrate made of a metal sheet, it is possible to increase the rigidity of the optical recording medium and to provide an optical recording medium in which the occurrence of deformation such as warpage is suppressed. Further, by using the second substrate made of a paper sheet (paper sheet), it is possible to reduce the cost of the optical recording medium and to provide an optical recording medium with a small environmental load. “Metal sheet” and “paper sheet” refer to sheets composed mainly of “metal” and “paper”, and those containing other components such as resin for reinforcement or on the surface. It may be coated.

  The optical recording medium of the present invention may be one in which a nonlinear optical film is formed on the laser light incident surface side of the first recording surface and / or the second recording surface.

  According to the above invention, since the nonlinear optical film is provided on the laser beam incident side of the recording surface, an optical recording medium having a large recording capacity can be realized by the nonlinear optical film. Here, the “nonlinear optical film” refers to a film in which the refractive index, light transmittance, light reflectance, and the like change nonlinearly with respect to a temperature rise accompanying laser light irradiation, for example. As a result, it is possible to realize super-resolution reproduction that reproduces only a part of information in a light beam spot formed by condensing and irradiating a laser beam, so that an optical recording medium having a large recording capacity can be obtained. It becomes.

  In the optical recording medium on which the nonlinear optical film is formed, the first recording surface is a recording layer corresponding to the BD format, the second recording surface is a recording layer corresponding to the HD-DVD format, and Of the first recording surface and the second recording surface, a non-linear optical film may be formed only on the laser light incident side of the second recording surface.

  According to the above invention, the first recording surface corresponding to the BD format does not have a nonlinear optical film, and the second recording surface that can be reproduced by the optical system compatible with the HD-DVD format has a nonlinear optical function on the laser beam incident side. Since no film is provided, the recording capacity of the first recording surface and the recording capacity of the second recording surface can be easily made equal. Thereby, it is possible to obtain an optical recording medium capable of performing the recording of the same capacity on the recording surfaces of the first recording surface and the second recording surface under the same conditions.

  In the optical recording medium of the present invention, each of the first recording surface and the second recording surface has a BCA (Burst Cutting Area), and the BCA includes the identification information of the optical recording medium in the BCA. The mark may be formed.

  In the optical recording medium of the present invention, as described above, the first recording surface and the second recording surface are provided via the second substrate. For this reason, when reading the barcode pattern information recorded on the BCA provided on each recording surface, it is possible to prevent the BCA information on one recording surface from being mixed into the BCA information on the other recording surface. An optical recording medium can be realized.

  In the optical recording medium in which each of the first recording surface and the second recording surface has a BCA, at least a part of the BCA formed on each of the first recording surface and the second recording surface is It may be formed in a region overlapped when viewed from the normal direction of the first recording surface and the second recording surface.

  In the optical recording medium of the present invention, as described above, the first recording surface and the second recording surface are provided via the second substrate. For this reason, at least a part of the BCA of the first recording surface and the second recording surface is the normal direction of the first recording surface and the second recording surface, that is, the recording constituting the first recording surface and the second recording surface. Even when it is formed in a region overlapping in the stacking direction of the layers, it is possible to accurately read out the BCA information on the first recording surface and the BCA information on the second recording surface.

  The manufacturing method of the present invention is the manufacturing method of the optical recording medium of the present invention, wherein the second recording surface is formed on the third transparent substrate on which the second recording surface is formed. The substrate is bonded with an adhesive, and the first transparent substrate is bonded onto the first recording surface with a transparent adhesive.

  According to the above invention, it is possible to form the second recording surface and the first recording surface on the third transparent substrate and the second substrate having the same thickness as the conventional optical recording medium. Therefore, as in the prior art, an uneven pattern for recording information and tracking can be formed on the substrate surface by using an injection molding method or a photopolymer method (2P method), thereby reducing the cost of forming an optical recording medium. It becomes possible.

  The manufacturing method of the present invention is the manufacturing method of the optical recording medium of the present invention, wherein the first transparent substrate is formed on both surfaces of the second substrate on which the first recording surface and the second recording surface are formed. And the third transparent substrate are bonded together with a transparent adhesive.

  According to the above-described invention, it is possible to collectively form the concave / convex pattern for recording information and tracking on both surfaces of the second substrate, simplifying the forming process and reducing the cost of the optical recording medium. Can be realized.

  The manufacturing method of the present invention is a method for manufacturing the optical recording medium of the present invention, wherein the first transparent substrate on which the first recording surface is formed and the third transparent on which the second recording surface is formed. The substrate is bonded to the second substrate with an adhesive.

  According to the above invention, since the laser beam for recording / reproduction does not pass through the adhesive for bonding the substrates, it is possible to use an adhesive that hardly transmits light. For this reason, for example, by using an inexpensive adhesive such as a double-sided pressure-sensitive adhesive tape, the cost of the optical recording medium can be reduced, and the bonding process can be simplified.

  As described above, in the optical recording medium of the present invention, the first recording surface and the second recording surface correspond to different formats, and in this order from the first transparent substrate side and the third transparent substrate side, respectively. Information is recorded and / or reproduced by the irradiated laser beam. Thereby, when recording / reproducing information on the first recording surface and recording / reproducing information on the second recording surface, each recording surface does not pass through the other recording surface, Stable recording / reproduction similar to that of a conventional optical recording medium can be realized. In addition, since the total thickness of the optical recording medium can be easily adjusted by the second substrate, compatibility of different formats can be ensured with respect to the entire thickness of the optical recording medium.

  The method for producing an optical recording medium of the present invention is an optical recording in which a first transparent substrate or a first transparent cover layer, a first recording surface, a second substrate, a second recording surface, and a third transparent substrate are laminated in this order. In the medium, the first recording surface and the second recording surface correspond to different formats, and information is recorded and recorded by laser light emitted from the first transparent substrate side and the third transparent substrate side in this order, respectively. A method of manufacturing an optical recording medium to be reproduced, wherein a concavo-convex pattern is collectively formed on the first recording layer constituting the first recording surface and the second recording layer constituting the second recording surface. The first transparent substrate and the third transparent substrate may be bonded to both surfaces of the second substrate on which the first recording surface and the second recording surface are formed with a transparent adhesive.

  Also, the method for producing an optical recording medium of the present invention provides an optical recording in which a first transparent substrate or a first transparent cover layer, a first recording surface, a second substrate, a second recording surface, and a third transparent substrate are laminated in this order. In the medium, the first recording surface and the second recording surface correspond to different formats, and information is recorded and recorded by laser light emitted from the first transparent substrate side and the third transparent substrate side in this order, respectively. A method of manufacturing an optical recording medium to be reproduced, wherein the first transparent substrate on which the first recording surface is formed and the third transparent substrate on which the second recording surface is formed are bonded with an adhesive. You may affix on the said 2nd board | substrate.

  In the optical recording medium manufacturing method of the present invention, as described above, the first transparent substrate or the first transparent cover layer, the first recording surface, the second substrate, the second recording surface, and the third transparent substrate are laminated in this order. In the optical recording medium, the first recording surface and the second recording surface correspond to different formats, and information is obtained by laser light emitted from the first transparent substrate side and the third transparent substrate side in this order, respectively. Is a method for producing an optical recording medium on which recording and / or reproduction is performed, wherein the uneven pattern is collectively formed on the first recording layer constituting the first recording surface and the second recording layer constituting the second recording surface. The first transparent substrate and the third transparent substrate may be bonded to both surfaces of the second substrate on which the first recording surface and the second recording surface are formed with a transparent adhesive. .

  Also, the method for producing an optical recording medium of the present invention provides an optical recording in which a first transparent substrate or a first transparent cover layer, a first recording surface, a second substrate, a second recording surface, and a third transparent substrate are laminated in this order. In the medium, the first recording surface and the second recording surface correspond to different formats, and information is recorded and recorded by laser light emitted from the first transparent substrate side and the third transparent substrate side in this order, respectively. A method of manufacturing an optical recording medium to be reproduced, wherein the first transparent substrate on which the first recording surface is formed and the third transparent substrate on which the second recording surface is formed are bonded with an adhesive. You may affix on the said 2nd board | substrate.

  Therefore, it is possible to provide a method of manufacturing an optical recording medium having compatibility that can be attached to an optical recording / reproducing apparatus compatible with a plurality of different formats.

  In order to solve the above problems, an optical recording medium according to the present invention includes a first transparent substrate or a first transparent cover layer, a first recording surface, a second substrate, a second recording surface, and a third transparent substrate laminated in this order. In the optical recording medium, the first recording surface and the second recording surface correspond to different formats, and the uneven pattern of the second substrate and the first recording layer constituting the first recording surface And the uneven | corrugated pattern of the 2nd recording layer which comprises the said 2nd recording surface may be the formation formed by injection-molding collectively.

  In order to solve the above problems, an optical recording medium according to the present invention includes a first transparent substrate or a first transparent cover layer, a first recording surface, a second substrate, a second recording surface, a third recording surface, and a third transparent surface. An optical recording medium in which substrates are laminated in this order, wherein the first recording surface corresponds to a format different from the second recording surface and the third recording surface, and the second recording surface and the second recording surface The three recording surfaces correspond to the same format, and the second substrate, the concave / convex pattern of the first recording layer constituting the first recording surface, and the concave / convex pattern of the second recording layer constituting the second recording surface. May be formed by injection molding in a lump.

  In the optical recording medium according to the present invention, the thicknesses of the first transparent substrate or the first transparent cover layer, the second substrate, and the third transparent substrate are 0.1 mm, 0.5 mm, and 0.6 mm, respectively. Preferably there is.

  In the optical recording medium according to the present invention, as described above, the first recording surface and the second recording surface correspond to different formats, and the second substrate and the first recording surface constituting the first recording surface. The concavo-convex pattern of the recording layer and the concavo-convex pattern of the second recording layer constituting the second recording surface are collectively formed by injection molding.

  In the optical recording medium according to the present invention, as described above, the first recording surface corresponds to a format different from the second recording surface and the third recording surface, and the second recording surface and The third recording surface corresponds to the same format, and the second substrate, the concavo-convex pattern of the first recording layer constituting the first recording surface, and the second recording layer constituting the second recording surface The concavo-convex pattern is a formed product that is injection-molded in a lump.

  Therefore, it is possible to provide a compatible optical recording medium that can be attached to an optical recording / reproducing apparatus compatible with a plurality of different formats.

  INDUSTRIAL APPLICABILITY The present invention can be used as a compatible optical recording medium that can be attached to an optical recording / reproducing apparatus compatible with a plurality of different formats.

11, 51, 61 First transparent substrate 12 Transparent adhesive layer 13 First recording surface 14, 54 63 Second substrate 15 Adhesive 16 Second recording surface 17, 58, 65 Third transparent substrate L11, L12 Laser light LC11, LC12 objective lens 53 first recording layer (first recording surface)
55 Second recording layer (second recording surface)
57 Third recording layer (third recording surface)
62 Recording layer (first recording surface)
64 recording layer (second recording surface)
72, 82, 93 Nonlinear optical film

Claims (2)

In the optical recording medium in which the first transparent substrate or the first transparent cover layer, the first recording surface, the second recording surface, and the third substrate are laminated in this order,
The first recording surface and the second recording surface correspond to different formats,
The first recording surface or the second recording surface is a write-once or rewritable recording surface,
An optical recording medium, wherein the recording capacity of the first recording surface and the recording capacity of the second recording surface are substantially equal.   The optical recording medium, wherein the first recording surface or the second recording surface comprises a multi-layered recording layer.

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