JPH113543A - Information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information recording medium which cn reproduce information from both planes of surface and back to which labels having size being easy to read is attached even if a cartridge is not provided. SOLUTION: This recording medium is provided at least a recording layer 12 on a transparent substrate 11, information of the recording layer 12 is reproduced by focusing and irradiating a light beam 15 on the recording layer 12 through the transparent substrate 11 rotating the transparent substrate 11. In this case, a label pattern film 13 is formed on a transparent substrate plane of an incident plane side of the light beam 15 of a region of the recording layer 12, and the label pattern film 13 has such a characteristic that transmissivity is large at approximately wavelength of the light beam 15 and reflectance or absorptivity is large at one part of the other wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium such as an optical disk medium capable of recording and reproducing a large amount of information by using a light beam.

[0002]

2. Description of the Related Art An optical disk has very excellent characteristics as a storage device for a large amount of information, like a hard disk. In particular, an optical disc is most suitable as a medium for distributing and transporting multimedia information data such as moving image data requiring an extremely large capacity, since information can be recorded / reproduced with a light beam and only the information storage unit can be carried. .

In a conventional optical disk medium, a guide groove of a minute concave portion having a width of 0.56 μm and a pitch of 1.12 μm is spirally formed on a surface of a transparent substrate such as a disc-shaped polycarbonate having a thickness of 0.6 mm. GeSbTe or AgInSbT is formed on the substrate surface by sputtering or the like.
e) or a thin film of a phase change recording material such as TbFeCoT
A thin film of a magneto-optical recording material such as i or TbFeCoTa is formed. The thin film layer of this recording material is composed of ZnS and SiO ₂
, Or a protective film layer such as a transparent dielectric such as a Si ₃ N ₄ compound or a tantalum oxide. Further, an Al alloy or Si or Si / Al
In many cases, a reflective film layer such as an alloy laminated film or a heat radiation layer is provided. Further, a protective film layer such as an ultraviolet curable resin or an inorganic dielectric is often provided thereon. In addition to the above-described functions, these stacked structures also generate a multiple interference effect of light, and this effect functions as a single recording layer as a whole. These laminates are often bonded together with the recording material thin film layer inside and the transparent substrate outside. By doing so, information can be reproduced (and recorded) from both sides, so that the recording capacity of the information recording medium can be doubled.

Further, as a read-only optical disk medium, minute circular or oblong pits are formed on the surface of a transparent substrate such as a disc-shaped polycarbonate having a thickness of 0.6 mm or the like. The recording layer is formed by providing a reflective film layer of an Al alloy.

[0005] The guide groove or the pitted transparent substrate is exposed to a laser beam of a positive photoresist to cause a photoreaction, and then developed to form a concave portion. And a large amount is reproduced by a method such as injection molding.

[0006] This conventional optical disk medium records information
For reproduction, a laser beam is passed through a transparent substrate, and a groove (concave portion) or a flat portion (convex portion) is formed around a guide groove having an uneven shape.
By irradiating one of them as an information track.

This laser beam is narrowed down to a diameter of about 1 μm by an objective lens. A focus servo is performed to focus the laser beam narrowed down to the recording layer.

The guide groove is used for a track servo in which a laser beam accurately positions and tracks an information track position. A displacement signal (track error signal) between the laser light beam and the guide groove is detected by a push-pull method or the like. That is, the far field pattern of the reflected light from the optical disk medium is detected by a two-divided photodetector having two light receiving areas, and the difference between the photocurrents detected in both light receiving areas and the guide groove on the optical disk medium and the laser light are detected. Detects positional deviation from the beam. The depth of the guide groove for the track servo is set to a value near λ / 8 or a value near 3λ / 8 (where λ is the wavelength of the laser light beam in the transparent substrate) at which the track error signal is largest. It is usually done.

The recording / reproducing information track is generally divided into one or a plurality of information recording unit sections in one round, and an address number is assigned to each section.

[0010] For recording information, a thin film layer of a recording material is moved at a predetermined speed by rotating an optical disk medium, and a track servo is performed so that a laser light beam incident through a transparent substrate is positioned on an information track. While performing focus servo so as to focus on the recording material thin film layer, the intensity of the laser light beam is modulated according to information to be recorded. When the recording material is a phase change material, the laser light intensity is modulated to Pw1 and Pw2 (Pw1> Pw2) so as to be between the amorphization level and the crystallization level to overwrite (overwrite). Do it. That is, a mark in an amorphous state is formed in a section irradiated with a laser light beam having a light intensity Pw1 enough to melt the phase change material thin film layer, and a light intensity Pw2 not large enough to melt in a section other than the amorphous mark. Irradiates the laser light beam of the above, and becomes a crystallized state. Therefore, the section other than the amorphous mark is in a crystalline state regardless of whether the state before irradiation is amorphous or crystalline, so that even in a place where information is already recorded, overwriting (overwriting) is performed. ).

The information recorded on the optical disk medium is reproduced by rotating the optical disk medium to move the thin film layer of the recording material at a predetermined speed, so that the laser beam incident through the transparent substrate is positioned on the information track. While performing the track servo so as to perform the focus servo so as to focus on the recording material thin film layer, the laser light beam Pr (P
w1>Pw2> Pr), light reflected from the optical disk medium is received by the photodetector, and information is reproduced by a change in the amount of reflected light. When the recording material is a phase change material, the recording is performed by utilizing the fact that the reflectance and / or the phase difference are different between the amorphous state and the crystalline state.

It is desired that the recording / reproducing apparatus for such an information recording medium be made thinner. Therefore, it is desirable that the information recording medium has no cartridge.

[0013]

However, such an information recording medium capable of reproducing information from both sides without a cartridge has a problem that a user cannot attach a label having a size that is easy to read.

An object of the present invention is to provide an information recording medium with a large label capable of reproducing information from both sides without using a cartridge.

[0015]

The above object is achieved by the following means.

That is, the present invention provides at least a recording layer on a transparent substrate, and focuses and irradiates a light beam onto the recording layer through the transparent substrate while rotating the transparent substrate, thereby obtaining information on the recording layer. In the information recording medium to be reproduced, a label pattern film is formed on the transparent substrate surface on the light beam incident surface side of the recording layer region, and the label pattern film has a large transmittance near the wavelength of the light beam. At least a part of the wavelength is provided at least a recording layer on an information recording medium and a transparent substrate characterized by having a large reflectance or absorptivity, the light beam is passed through the transparent substrate while rotating the transparent substrate An information recording medium for reproducing information from the recording layer by irradiating the recording layer with the light focused, wherein the transparent substrate comprises a first transparent substrate and a second transparent substrate. At least two pairs with a light-emitting substrate and a structure in which the two substrates are bonded to each other, the information of the first recording layer is reproduced through the first transparent substrate, and the second recording layer is reproduced through the second transparent substrate. In the information recording medium for reproducing information, a label pattern film representing the content of the first recording layer is formed on the second transparent substrate surface on the light beam incident surface side of the region of the second recording layer, A label pattern film representing the content of the second recording layer is formed on the first transparent substrate surface on the light beam incident surface side of the region of the first recording layer, and the label pattern film is formed of the light beam. The transmittance near the wavelength is to provide an information recording medium characterized by having a large reflectance or absorptivity at some of the other wavelengths, the label pattern film is a laminate film, Said la Wherein the label pattern film is a multilayer interference film, the label pattern film is a film in which a blue dye is mixed with a resin binder, and the label pattern film is a film in which a red dye is mixed with a resin binder. .

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view for explaining the information recording medium of the present invention. FIG. 1 shows an optical disk medium as an example. A recording layer 12 is formed on the transparent substrate 11, and a label pattern film 13 indicating its contents is formed on the opposite side of the recording layer 12 with respect to the transparent substrate 11. The transparent substrate 11, the recording layer 12, and the label pattern film 13 constitute one recording medium element 14. Transparent substrate 21,
Another recording medium element 24 comprising a recording layer 22 and a label pattern film 23 is prepared, and the label pattern films 13 and 2 are prepared.
3 is adhered via the adhesive layer 30 so that it is on the outside,
An information recording medium capable of reproducing information from both sides is completed. Here, the recording layers 12 and 22 include a so-called recorded layer in which pits are provided on a transparent substrate and a reflective layer is provided thereon. The information reproduction of the recording layer 12 is performed by a reproduction light beam 15 radiated through the transparent substrate 11, and the information reproduction of the recording layer 22 is performed by a reproduction light beam 25 radiated through the transparent substrate 21. The present invention is characterized in that the reproducing light beam can be applied to the recording layer through the label pattern film. In the present invention, by selecting a label pattern film material that allows the reproducing light beam to pass through the label pattern film, the direction of the reproducing light beam and the label reading directions 16, 26 can be made the same, and the recording layer area and Since a label pattern area can be overlapped, a large label can be obtained. For this reason, a double-sided bonding structure is possible. It is desirable that the position of the label pattern film in the incident depth direction be as far away from the recording layer as possible, since there is not much problem even if the label pattern film has a defect. In this sense, the formation position of the label pattern film is not on the recording layer surface side, and
The incident surface side is essential, not in a transparent substrate. The label pattern film does not need to have high transmittance in the other wavelength band of the reproducing light beam wavelength, and the readability of the label pattern film is improved by increasing the reflectance at another certain wavelength.

The conventional information recording medium has a recording layer 102 on a transparent substrate 101, as can be seen from the schematic sectional view of FIG.
Are provided, and the label pattern film 103 is provided thereon. The reproduction of the information in the recording layer 102 is performed by irradiating the light beam 105 for reproduction through the transparent substrate 101. However, since the label is read from the label pattern film side, a double-sided bonding structure is impossible.

The label pattern film can be formed by attaching a laminate film using a multilayer interference film or by directly forming a multilayer interference film on a transparent substrate. Increasing the transmittance near the wavelength of the reproducing light beam and increasing the reflectivity or absorptance at some other wavelengths (It is not necessary to increase the reflectivity or absorptance at all wavelengths other than the reproducing wavelength. Absent). Having such characteristics facilitates the reading of the label. This can be realized by using a multiple interference design method. A laminate film is more preferable because a multicolor label pattern film can be easily formed. As another method of forming the label pattern film, when the reproducing light beam is red, a dye having a high transmittance for light having a wavelength near red, that is, a blue dye mixed with a transparent resin binder is used. When the reproducing light beam is blue, a dye in which a dye having a high transmittance to light having a wavelength near blue, that is, a red dye is mixed with a transparent resin binder can be used.

The wavelength at which the transmittance is maintained at a certain level or more needs to be the wavelength of the recording light beam in the case of a recordable medium in addition to the wavelength of the reproducing light beam.

When the information recording medium is used by mounting it on an information recording / reproducing apparatus, as shown in FIG. 2, the reproducing light beam is irradiated from the lower side, and the label can be read only from the upper side. The medium used in this case is
As shown in FIG. 2, a label pattern 4 representing the contents of the first recording layer 42 for reproducing information through the first transparent substrate 41
3 is provided on the second transparent substrate 51, and the label pattern 53 representing the content of the second recording layer 52 for reproducing information through the second transparent substrate 51 is provided on the first transparent substrate 41. Desirable from a viewpoint.

In all of the above description, the case where the information recording medium has no cartridge has been described. However, even if the information recording medium in the cartridge uses the method of the present invention, it is within the scope of the rights of the present invention. Needless to say, there is.

[0025]

As described above, according to the information recording medium of the present invention, it is possible to obtain an information recording medium capable of reproducing information from both front and back sides with a label having a size that is easy to read without a cartridge. Can be

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining an information recording medium of the present invention.

FIG. 2 is a schematic sectional view for explaining another information recording medium of the present invention.

FIG. 3 is a schematic sectional view of a conventional information recording medium.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 transparent substrate 12 recording layer 13 label pattern film 14 recording medium element 15 reproducing light beam 16 label reading direction 21 transparent substrate 22 recording layer 23 label pattern film 24 recording medium element 25 reproducing light beam 26 label reading direction 30 adhesive layer Reference Signs List 41 first transparent substrate 42 first recording layer 43 label pattern film 51 second transparent substrate 52 second recording layer 53 label pattern film 101 transparent substrate 102 recording layer 103 label pattern film 105 reproducing beam 106 label reading direction

Claims (6)

[Claims] At least a recording layer is provided on a transparent substrate,
In the information recording medium for reproducing the information of the recording layer by focusing and irradiating a light beam to the recording layer through the transparent substrate while rotating the transparent substrate, the light beam incident surface side of the area of the recording layer Forming a label pattern film on the transparent substrate surface, wherein the label pattern film has a property such that the transmittance is large near the wavelength of the light beam and the reflectance or absorptance is large at a part of other wavelengths. Information recording medium. 2. At least a recording layer is provided on a transparent substrate,
An information recording medium for reproducing information on the recording layer by focusing and irradiating the recording layer with a light beam through the transparent substrate while rotating the transparent substrate, wherein the transparent substrate is a first transparent substrate and a second transparent substrate. At least 2 with transparent substrate
An information recording device for reproducing information of a first recording layer through the first transparent substrate and reproducing information of a second recording layer through the second transparent substrate; In the medium, a label pattern film representing the content of the first recording layer is formed on the second transparent substrate surface on the light beam incident surface side of the region of the second recording layer, and the second recording layer Is formed on the first transparent substrate surface on the light beam incident surface side of the region of the first recording layer, and the label pattern film has a transmittance near the wavelength of the light beam. An information recording medium characterized in that it has a characteristic that the reflectivity or the absorptance is large at a part of other wavelengths. 3. The information recording medium according to claim 1, wherein the label pattern film is a laminate film. 4. The information recording medium according to claim 1, wherein the label pattern film is a multilayer interference film. 5. The information recording medium according to claim 1, wherein the label pattern film is a film in which a blue dye is mixed with a resin binder. 6. The information recording medium according to claim 1, wherein the label pattern film is a film in which a red dye is mixed with a resin binder.