JP2004006027A - Optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium for continuous irradiation of light for reproduction or (and) recording to a plurality of laminated information sections. <P>SOLUTION: A first recording element 31, having a first optical translucent information section 31M on one surface of a first light transmission substrate 31S, and a second recording element 32 having a second reflective information section 32M on one surface of a second substrate 32S are joined via a transparent layer 33, by allowing surfaces at sides having the first and second information sections to face each other. The recording tracks of the first and second information sections are arranged coaxially. The rotation recording travelling direction of each recording track is selected to a rotation recording traveling direction, where one of them faces an inner periphery section from an outer periphery section and the other faces the outer periphery section from the inner periphery section. <P>COPYRIGHT: (C)2004,JPO

Description

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

In order to increase the amount of recordable information in optical recording media such as disks and cards for recording or (and) reproducing by light irradiation as recording media for recording audio and video and other various information, It is conceivable that the recording information surface has a multilayer structure.

For example, in an optical disc, as shown in FIG. 6, information portions 1M and 2M on which information is recorded by information recording pits are formed on one surface of each of the transparent substrates 1S and 2S, and these information recording portions 1M are formed. And 2M, the first recording body 1 and the second recording body 2 on which the reflecting surfaces 1R and 2R are formed by, for example, Al vapor deposition, with their surfaces having the information sections 1M and 2M facing each other. Proposals have been made for a configuration in which the components are bonded by a bonding adhesive 3.

In such an optical recording medium such as an optical disk, in order to read out or reproduce the recorded information with respect to the first and second information sections 1M and 2M, irradiation of the readout light (hereinafter referred to as reproduction light) is performed. Is performed by irradiating the first information section 1M with the reproduction light 1L from the transparent substrate 1S side, and performing the second information section 2M by irradiating the reproduction light 2L from the transparent substrate 2S side. . That is, in this case, as the drive device for the optical recording medium, the reproduction optical pickups for the above-described two-layer information recording section, that is, the first and second information sections 1M and 2M, are opposed to both surfaces of the optical recording medium. A method is adopted in which two optical pickups are arranged respectively, or a method in which an optical disc is inverted with respect to one optical pickup and each information section is selectively opposed to the optical pickup side to reproduce the information. become.

In such a configuration, the two-optical pickup configuration is unavoidable for an increase in the size of the apparatus, an increase in the number of parts, and an increase in weight, and the one-optical pickup configuration requires an inversion operation of the optical disk. In order to perform continuous reproduction for the first and second information units 1M and 2M, a large-scale mechanism is required to automate the reversal of the optical recording medium. An increase in points and an increase in weight cannot be avoided.

す る To avoid such inconveniences, there has been proposed an optical recording medium capable of reproducing information from a two-layer information recording section by irradiating light from the same side of the optical recording medium. This optical recording medium will be described together with its manufacturing method with reference to the process chart of FIG. 7. In this case, as shown in FIG. 7A, for example, a first information portion 21M formed by recording pits corresponding to recording information is formed. A first transparent substrate 21S made of polycarbonate (hereinafter, referred to as PC) or the like is formed by injection molding. Then, a translucent optical layer 23 for controlling the required transmittance and reflectance in the information section 21M, for example, a sputtered layer of SiN is formed. Then, a second information section is formed on the first information section 21M by a photopolymerization method using an ultraviolet light curable resin, a so-called 2P method. That is, as shown in FIG. 7C, a stamper 25 having a concavo-convex pattern forming a second information portion is pressed against the information portion 21M of the transparent substrate 21S via the ultraviolet curable resin 24, and in this state, from the transparent substrate 21S side. The ultraviolet curing resin 24 is cured by irradiating ultraviolet rays. Thereafter, as shown in FIG. 7D, the stamper 25 in FIG. 7C is peeled off. Thus, the second information portion 22M is formed on the ultraviolet curable resin 24 by transferring the concave and convex pattern of the stamper 25. A reflective film 26 such as an Al vapor-deposited film is formed on the second information section 22, and a protective layer 27 of a photocurable resin or the like is further coated thereon. Thus, an optical recording medium on which the first and second information sections 21M and 22M are formed is constituted.

Reproduction by light irradiation on the optical recording medium according to this configuration is performed from the same side on the transparent substrate 21S side. As shown in FIG. 7D, reproduction on the first information section 21M is performed from the transparent substrate 21S side. The first information section 21M is irradiated with the focused reproduction light 21L, and information is read out by the reflected light from the first information section 21M. Similarly, the reproduction with respect to the second information section 22M is performed in a transparent manner. The reproduction light 22L focused on the second information portion 22M is irradiated from the substrate 21S side with the reproduction light 22L, and the information is read by the reflected light from the second information portion 22M.

According to this configuration, both the first and second information recording sections can be reproduced by irradiating light from one side, so that a single optical pickup configuration can be achieved, and the operation of reversing the optical recording medium can be performed. Since the necessity of performing the optical recording medium is avoided, there is an advantage that the size and weight of the drive device for the optical recording medium can be reduced, the configuration can be simplified, and the assembly can be simplified. In the medium, since one information section 2M is formed by the 2P method, it is necessary to form the information section 2M in a so-called single-sheet manner, which causes a problem in mass productivity.

(4) Even when the information section has a two-layer structure, a structure capable of continuously reading out information of each layer has not been proposed, and there is a problem that it is difficult to increase continuous recording or reproduction time.

In view of the foregoing, the present invention provides an optical recording medium capable of continuously performing light irradiation for reproduction or (and / or) recording on a plurality of stacked information sections, and has a high productivity in the production thereof. Be able to improve.

An optical recording medium according to the present invention comprises a first recording medium having a semi-light transmitting first information portion on one surface of a light transmitting first substrate, and a first recording material having a semi-light transmitting first information portion on one surface of a second substrate. A second recording medium having a reflective second information section, and a first recording medium having a first information section and a second recording medium having a second information section facing the second information section, and a first recording medium and a second recording section having a second information section facing each other. The recording tracks of the first information section are arranged coaxially, and either one of the rotation recording progress direction of the recording track of the first information section and the rotation recording progress direction of the recording track of the second information section is inward from the outer periphery. The rotation recording direction is selected in the direction toward the circumference and the other direction from the inner circumference toward the outer circumference.

Further, in the method of manufacturing an optical recording medium according to the present invention, a step of manufacturing a first substrate having a first information part and a second substrate having a second information part by injection molding, respectively, Forming a reflective surface on the second information portion of the substrate, and setting the first recording body and the second recording body such that the surfaces on the side having the first and second information portions are opposed to each other. And a recording track of the first, second, and information sections are coaxially arranged, and a rotational recording progress direction of the recording track of the first information section and a second information One of the recording recording directions of the recording tracks is selected to be the rotation recording traveling direction in which one goes from the outer periphery to the inner periphery and the other goes from the inner periphery to the outer periphery.

According to the above-described present invention, the first recording body on which the first information section is formed and the second recording body on which the second information section is formed are separately formed and joined. The first information section and the second information section are stacked, but the recording tracks of the first information section and the second information section are arranged coaxially when viewed from the light incident surface side. The recording tracks of the first information section and the recording tracks of the second information section have the same recording progress direction, and one of them is directed from the inner peripheral portion (center portion) to the outer peripheral portion. By adopting a configuration in which the other is directed from the outer peripheral portion to the inner peripheral portion, particularly when each recording track is formed in a spiral shape, the recording and / or reproduction of both information portions can be continuously performed. Therefore, the continuous recording or (and / or) You can mow it.

According to the optical recording medium of the present invention, the recording tracks of the first information section and the second information section are arranged coaxially, and the recording tracks of the first information section are viewed from the light incident surface side. The recording directions of the recording tracks of the second information section are set to the same direction, and one of them is directed from the inner peripheral portion (center portion) to the outer peripheral portion, and the other is directed from the outer peripheral portion to the inner peripheral portion. In particular, when each recording track has a spiral shape, the recording and / or reproduction of both information portions can be performed continuously, so that the continuous recording or (and) reproduction time can be reduced. It can be increased.

In addition, as described above, the first recording body and the second recording body formed independently are joined together, so that the manufacturing is extremely simple and mass-produced as compared with the case of the 2P method. . In addition, since the first recording medium and the second recording medium are joined to each other, the mechanical strength can be increased. When a 6 mm thick configuration is used, the strength can be improved, and the 0.6 mm thick configuration can be adapted to the 1.2 mm configuration. This has the effect of facilitating the conversion.

The present invention is applied to an optical recording medium such as a disk or a card for recording or (and / or) reproducing by light irradiation as a recording medium for recording various kinds of information in addition to audio, video and the like. FIG. 1 is a schematic cross-sectional view of an embodiment in which the present invention is applied to a so-called ROM (Read Only Memory) type optical disc in which an information portion is formed, particularly by concave and convex recording pits, and this information is read out by light irradiation. is there.

As shown in a schematic sectional view of FIG. 2, the optical recording medium according to the present invention has a first information portion 31M having a semi-light-transmitting first information portion 31M on one surface of a light-transmitting first substrate 31S. 3 and a second recording body 32 having a reflective second information part 32M on one surface of a second substrate 32S as shown in a schematic sectional view of FIG. As shown in FIG. 1, the first and second information sections 31M and 32M have a configuration in which the surfaces on the side having the information sections 31M and 32M face each other and are joined via a transparent layer 33.

Then, the incident surfaces of the reproduction light beams 31L and 32L on the optical recording medium and the first and second information portions 31M and 32M, that is, in the example of FIG. The incident surface of each of the reproduction lights 31L and 32L on the second information units 31M and 32M is set to the side of the first recording body 31 of the optical recording medium (optical disk in this example) having the first information unit 31M. On the opposite side, ie, the back.

The first information section 31M is configured to be semi-light-transmitting as described above, and has a reflectance of 20% to 50% and a light transmittance of 30% to 80%.

{Circle around (2)} Although the second information section 32M is configured to be reflective as described above, the reflectance is set to 60% or more.

In this optical disc, the recording tracks of the first and second information sections are coaxially arranged, and the rotational recording direction of the first information section 31M and the rotational recording direction of the second information section 32M. The direction is selected in the same direction as viewed from the light incident surface side, as indicated by arrows in FIG.

Similarly, the recording tracks of the first and second information sections are coaxially arranged as shown in FIG. 4, and the rotation recording progress direction of the recording track of the first information section 31M and the second As indicated by arrows, the direction of the rotation recording progress of the information recording track of the information portion 32M is, for example, spiral from the outer periphery to the inner periphery and the other is spiral from the inner periphery to the outer periphery. In the direction of rotation recording progress.

As shown in a schematic cross-sectional view of an example of the optical recording medium according to the present invention, as shown in FIG. 2, a semi-light transmitting first information is provided on one surface of a light transmitting first substrate 31S. As shown in a schematic cross-sectional view of one example of the first recording body 31 having a portion 31M, a second substrate having a reflective second information portion 32M on one surface of a second substrate 32S as shown in FIG. The recording body 32 and the recording body 32 are separately manufactured.

As shown in FIG. 1, when each of the information sections 31M and 32M adopts a recording mode using uneven recording pits, the first recording body 31 and the second recording body 32 have an example shown in FIG. As shown in the schematic cross-sectional view, it is formed by injection molding a transparent resin such as PC using a mold 40. In this case, in molding the first recording body 31, a master stamper 41 on which an information uneven pattern for forming the first information portion 31M is formed is arranged in the cavity of the mold 40, and the molding is performed. In molding the second recording body 32, a master stamper 42 on which an information uneven pattern for forming a second information portion 32M is formed in a cavity of a mold 40, and a transparent resin is formed in the cavity. For example, PC is injected and so-called injection molding is performed.

In each of the master patterns 41 and 42, one of the information concavo-convex patterns is sequentially recorded in the inner circumferential side, that is, from the center side to the outer circumferential side, and in one of the clockwise or counterclockwise rotation directions. It is formed in a pattern, and the other is sequentially recorded from the inner circumference side to the outer circumference side opposite to the above, and the rotation direction is either the counterclockwise direction or the clockwise direction of the rotation direction opposite to the above. It is formed in the done pattern.

The master patterns 41 and 42 can be formed by a known method. That is, for example, a photoresist is applied on a glass substrate having a mirror surface, for example, and the laser light on which light modulation such as ON / OFF is performed in accordance with the recorded information is rotated relative to the glass substrate, and radially. Pattern exposure is performed by relatively moving and scanning. Thereafter, the photoresist is developed to form a concavo-convex pattern corresponding to the pattern exposure, and metal plating, for example, silver plating is performed thereon to produce a disk master. Thereafter, a metal such as nickel plating is applied to the disk master to form a metal mask having an uneven pattern obtained by inverting the unevenness of the disk master described above, and nickel plating is applied to the uneven pattern of the metal mask, for example. Thus, a mother having a concavo-convex pattern in which the concavo-convex pattern of the metal mask is reversed is formed, and based on this, the master patterns 41 and 42 in which the concavo-convex pattern of the mother are reversed are similarly formed by plating.

The pattern exposure according to each record information on the photoresist on each glass substrate described above for forming each of the master patterns 41 and 42 described above is performed in such a manner that one of the patterns is directed, for example, clockwise from the inner peripheral side to the outer peripheral part. When the exposure according to the recording information is sequentially performed as the rotation direction of the other pattern, the other pattern exposure is performed according to the recording information sequentially as the counterclockwise rotation direction from the outer periphery toward the inner periphery.

Using the master patterns 41 and 42 produced as described above, a first transparent substrate 31S on which a first information section 31M is formed by injection molding and a second transparent substrate 31S on which a second information section 32M is formed, respectively. Of the substrate 32S is formed.

As shown in FIG. 2, a semi-transparent film 34 of SiN, SiO ₂ or the like is formed on the first information portion 31M thus formed to a thickness of, for example, 150 ° by vapor deposition, sputtering, or the like, as necessary. As described above, the first information section 31M is an information section having a reflectivity of 20% to 50% and a light transmittance of 30% to 80% and having an anti-transmissivity.

On the second information section 32M, as shown in FIG. 3, for example, a deposited film or the like having a thickness of about 500 ° is formed so that the reflectivity of the second information section 32M is 60% or more. Information section.

Then, the substrates 31S and 32S are joined with the side on which the first information part 31M is formed and the side on which the second information part 32M is formed, respectively, with the transparent layer 33 interposed therebetween. . As the transparent layer 33, for example, a photo-curable transparent resin, for example, an ultraviolet-curable transparent resin is sandwiched between the two substrates 31S and 32S and pressed against each other. To cure. In this case, it is assumed that the first transparent substrate 31S and the first information section 31M show transmission or semi-transmission also with respect to the ultraviolet light for performing the exposure and curing.

In this manner, the interval between the first and second information units 31M and 32M is set to a required interval, for example, 40 μm depending on the thickness of the transparent layer 33, and, for example, the reflection of the reproduction light from each of the information units 31M and 32M. At the same time, the interval is set so that light does not interfere, and at the same time, both substrates, that is, the first recording body 31 and the second recording body 32, are joined to produce a target optical recording medium.

In the optical recording medium finally formed in this manner, the recording tracks of each of the first and second information sections 31M and 42M have the same rotation as viewed from the light incident surface, that is, from the substrate 31S side in the above-described example. A configuration is adopted in which the recording progress direction is set, one of which goes from the inner peripheral portion to the outer peripheral portion, and the other takes the recording progress direction from the outer peripheral portion to the inner peripheral portion.

記録 The recording tracks of the first and second information sections can be spiral or concentric rings, respectively.

{Circle around (1)} Each of the substrates 31S and 32S of the first and second recording bodies has substantially the same thickness, for example, 1.2 mm or 0.6 mm. In this case, it is possible to effectively avoid the deformation of the optical recording medium due to the influence of the ambient temperature, such as "warp" due to the influence of the ambient temperature due to the joining of the substrates 31S and 32S.

According to the configuration of the present invention described above, since the first and second information sections 31M and 32M have a multilayer structure formed in an overlapping manner, the information capacity can be increased. Of the second information section is also illuminated from the second information section 31M in the same direction as the direction in which the first information section 31M is irradiated with the reproduction light. Since the light can reach the information section 32M and the reflected light can be detected, information can be read out by the occurrence of, for example, information pit interference in the information sections 31M and 32M.

In this case, as described above, the reflectance of the first information unit 31M is set to 20% to 50%, the light transmittance is set to 30% to 80%, and the reflectance of the second information unit is set to 60% or more. By doing so, it is possible to make the light amount of the reading light for the first information portion 31M substantially equal to the light amount of the reading light for the second information portion 32M. The adjustment circuit can be simplified.

As described above, the recording tracks of the first information section 31M and the second information section 32M are arranged coaxially, and the recording tracks of the first information section 31M are viewed from the light incident surface side. The recording directions of the recording tracks of the second information section 32 are set to the same direction, and one of the recording tracks is moved from the inner peripheral portion (center portion) to the outer peripheral portion, and the other is moved from the outer peripheral portion to the inner peripheral portion. By adopting a configuration in which the recording sections are turned, particularly when each recording track is formed in a spiral shape, the recording or (and) reproduction of the information sections 31M and 32M can be continuously performed. ) The reproduction time can be increased.

Note that, in the above-described example, the case where the first and second information sections 31M and 32M are both optical discs having a ROM configuration with uneven recording pits has been mainly described, but the recording mode of these information sections is not limited to this. Instead, the present invention can be applied to an optical recording medium capable of optically recording, appending, and rewriting. Each of the information sections 31M and 32M can be an information section according to the same recording and reproduction mode, or can be an information section according to different recording and reproduction modes. These information sections are, for example, recorded by a phase change between an amorphous state and a crystalline state, and the information section is formed by a phase change type recording in which the recording is performed by changing optical characteristics, or a magneto-optical element is used. Various modes such as a recording configuration can be adopted.

Also, in the above-described example, the first and second recording bodies 31M and 32M are configured by joining, but a configuration in which three or more recording bodies are overlapped may be employed.

The optical recording medium and the method of manufacturing the same according to the present invention are not limited to a disk, but may be variously modified without being limited to the above-described example, such as a card configuration.

In this specification, the optical pickup is not limited to a reproduction pickup, but also refers to a pickup having an optical recording function.

1 is a schematic sectional view of an example of an optical recording medium according to the present invention. FIG. 2 is a schematic cross-sectional view of an example of a first recording medium constituting the optical recording medium according to the present invention. FIG. 3 is a schematic cross-sectional view of an example of a second recording medium constituting the optical recording medium according to the present invention. FIG. 3 is an explanatory diagram of a recording progress direction of each information section of the optical recording medium according to the present invention. FIG. 2 is a cross-sectional view of an injection mold as an example of a method for producing an optical recording medium according to the present invention. FIG. 7 is a schematic sectional view of a conventional optical recording medium. A is a cross-sectional view of one step of a conventional method for manufacturing an optical recording medium. FIG. 1B is a cross-sectional view of one step of a conventional method for manufacturing an optical recording medium. C is a cross-sectional view of one step in a conventional method for manufacturing an optical recording medium. D is a cross-sectional view of one step of the conventional optical recording medium manufacturing method.

Explanation of reference numerals

31 first recording body 32 second recording body 31S first substrate 32S second substrate 31M first information section 32M second information section 33 transparent layer

Claims (2)

A first recording medium having a semi-light transmitting first information portion on one surface of a light transmitting first substrate, and a reflecting second information portion on one surface of a second substrate. A second recording medium having a first portion and a second information portion are joined via a transparent layer with the surfaces having the first and second information portions facing each other,
The recording tracks of the first and second information sections are coaxially arranged,
One of the rotation recording direction of the recording track of the first information portion and the rotation recording direction of the recording track of the second information portion is directed from the outer peripheral portion to the inner peripheral portion, and the other is the inner peripheral portion. An optical recording medium, which is selected in a rotational recording progressing direction from an outer peripheral portion to an outer peripheral portion. Manufacturing a first substrate having a first information section and a second substrate having a second information section by injection molding, respectively;
Forming a reflective surface on the second information portion of the second substrate;
Joining the first recording body and the second recording body via a transparent layer with the surfaces on the side having the first and second information portions facing each other, and
The recording tracks of the first, second and information sections are coaxially arranged,
One of the rotation recording direction of the recording track of the first information portion and the rotation recording direction of the recording track of the second information portion is directed from the outer peripheral portion to the inner peripheral portion, and the other is the inner peripheral portion. A method of selecting an optical recording medium in a rotational recording progressing direction from an outer peripheral portion to an outer peripheral portion.

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