JPH07272317A - Information recording medium and its production - Google Patents

Abstract

PURPOSE:To surely identify whether an information recording medium is genuine or not by viewing by forming a hologram on a substrate. CONSTITUTION:An optical disk is formed of a transparent substrate 6 consisting of glass, etc., information bits 7 formed on this substrate 6, a reflection layer 8, a protective layer 9, etc. The hologram 5 is formed as plural pieces of ruggedness of a depth smaller than the depth of the bits 7 on the substrate 6 of the non-information region 3 of this disk 1. The hologram 5 is not read by coherent light for reading the bit 7 information and is not reproduced. Then, whether the optical disk, etc., are genuine or not is always identified when the hologram 5 image is viewed, unlike the case of sticking a peelable hologram to the disk.

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 on which information reproducible by light or magnetism is recorded, and in particular, it is visually judged whether the information recording medium is genuine or false. Information recording medium, manufacturing method thereof, and reproducing apparatus thereof.

[0002]

2. Description of the Related Art Conventionally, as a device for preventing forgery, for example, there is one described in Japanese Patent Publication No. 63-168397. In this technique, a so-called hologram sheet is attached to cards such as cash cards to prevent counterfeiting of the cards.

[0003]

However, in the above-mentioned prior art, once the hologram sheet is peeled off, it cannot be discriminated whether it is a genuine product or a fake product, and the genuine product is sufficiently protected. There is a problem that you cannot do it.

The present invention has been made in view of such conventional problems, and provides an information recording medium capable of more reliably protecting an authentic product from forgery, a manufacturing method thereof, and a reproducing apparatus thereof. The purpose is to do.

[0005]

In order to achieve the above object, an information storage medium has a hologram formed on the base material itself on which information reproducible by light or magnetism is recorded, in addition to the information. It is characterized by being present.

Here, the information storage medium includes those reproducible by light such as an optical disc and an optical card, as well as those reproducible by magnetism such as a magneto-optical disc, a magnetic disc and a magnetic card. Be done. Further, specifically, when the information storage medium is, for example, an optical disc, the base material is a concept that includes a substrate having pits formed thereon, a protective layer, a reflective layer, and the like.

Further, in the case where the information storage medium has a plurality of pits formed on the substrate as information that can be reproduced by light, such as an optical disc, the unevenness of the plurality of irregularities forming the hologram causes the pit depth. Less than, and
It is desirable that the unevenness is such that a hologram formed of a plurality of unevennesses cannot be read out when reading the pits as information. Further, in this optical information storage medium, the hologram may be formed on either or both of the information recording area and the non-information area formed on the substrate.

Further, in the method for manufacturing an optical information storage medium for achieving the above object, a photoresist is applied on a specific plate material, and a pit pattern to be a pit and an interference pattern to be a hologram are imprinted on the photoresist. , Developing the photoresist to remove only the exposed portion on the photoresist to create an original plate on which the pits and the hologram are formed, create a stamper based on the original plate, and based on the stamper A substrate on which the pits and the hologram are formed, and a reflective layer and a protective layer are formed on the substrate.

Further, a reproducing apparatus suitable for reproducing an optical information recording medium having a hologram formed in an information storage area, applies an coherent light to the optical information recording medium, and an optical pickup that receives reflected light from the information recording medium. A judging means for judging whether or not the signal level from the optical pickup is a predetermined level and outputting a signal exceeding the predetermined level, and a reproducing means for reproducing the signal outputted from the judging means. It is characterized by having.

[0010]

The hologram cannot be faithfully reproduced unless the conditions for creating the hologram and the conditions for reproducing the hologram are matched, so that it is very difficult to faithfully reproduce the hologram itself. Further, since the hologram is formed on the base material itself on which information reproducible by light or magnetism is recorded, the hologram is always formed on the base material of the genuine information storage medium. That is, unlike a hologram sheet, it is not peeled off from the base material so that it cannot be distinguished whether it is a genuine product or a fake product. Therefore, whether the storage medium is a genuine product or a fake product can be surely distinguished by the presence or absence of the hologram or the difference in the hologram. Further, since the presence or absence of the hologram and the difference between the holograms can be visually checked, it is possible to easily determine whether the product is a genuine product or a fake product.

If the information storage medium has a plurality of pits recorded on the substrate as information that can be reproduced by light, such as a so-called optical disc, the unevenness of the hologram formed on the substrate is smaller than the pit depth. In addition, if the hologram formed of a plurality of concaves and convexes cannot be read when reading the pits as information, the pits can be formed even if the hologram is formed in the information recording area in which the plurality of pits are formed. Information can be reproduced clearly. Furthermore, even if the pit is exposed to specific light and the pit cannot be read as information, the hologram itself cannot be read.Therefore, even if the optical information recording medium is reproduced and copied, the hologram is not reproduced. Can not do it.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments according to the present invention will be described below with reference to the drawings. First, a first embodiment of the information recording medium according to the present invention will be described with reference to FIGS.

The information recording medium of this embodiment is an optical disc in which information is recorded in a pit shape on a substrate and information is read out and reproduced by coherent light. As shown in FIG. 1, this optical disc 1 has an information recording area 2 in which pit-shaped information is recorded on the outer peripheral side, a non-information area 3 on the inner peripheral side, and a reproducing device in the center. There is formed a spindle hole 4 for mounting on. A hologram 5 is formed in the non-information area 3. FIG. 2 is a sectional view taken along line AA of FIG. The optical disc 1 is made of, for example, a transparent substrate 6 such as polycarbonate, epoxy resin, or glass, a reflective layer 8 made of aluminum or the like formed on the information recording area 2 of the substrate 6, and an ultraviolet ray formed on the reflective layer 8. And a transparent protective layer 9 made of a cured (UV) resin or the like. In the information recording area 2 of the substrate 6, a plurality of pits 7, 7, ... Are formed concentrically or spirally. In addition, in the non-information area 3 of the substrate 6, an uneven hologram 5 is formed.

Even if a part of the hologram 5 is scratched, it has little influence on the reproduced image, and therefore it is not always necessary to positively cover it, but here, in order to completely prevent the hologram 5 from being scratched. The protective layer 9 is also formed on the hologram 5 formed in the non-information area 3. At this time, a transparent material is used as the protective layer 9, and the refractive index of the material forming the substrate 6 is made different from that of the material forming the protective layer 9 so that the wavefront reproduction light can be obtained from the hologram 5 formed on the transparent substrate 6. There is a need. It should be noted that the hologram 5 may be any one as long as a reproduced image can be obtained with white light or laser light. When the hologram 5 is irradiated with light, the object, figure, character pattern, etc. recorded as the hologram 5 is reproduced on the wavefront, so that the object, figure, character pattern, etc. can be visually recognized. Here, the object, figure, character pattern, etc. recorded as the hologram 5 may be one that represents the manufacturer of the optical disc 1 or one that indicates the content of the pit information recorded on the optical disc 1 to some extent.

Next, an optical disc of the second embodiment according to the present invention will be described with reference to FIG. The optical disc 1a of the present embodiment has the reflection layer 8 formed on the hologram 5 as well, and is otherwise similar to the first embodiment. In this way, the reflection layer 8 is also formed on the uneven hologram 5.
By forming the above, the amount of wavefront reproduction light due to reflection is increased, and the reproduced image of the hologram 5 is easily visible.

Next, a third embodiment and a fourth embodiment according to the present invention
4 and 5 for the optical disc of the embodiment of FIG.
Will be explained. The optical disc 1b of the third embodiment is
As shown in FIG. 4, the hologram 5 is formed on a part of the information recording area 2 (or may be the entire area). The hologram 5 is formed both in the information recording area 2 where there is no pit 7 and in the pit 7. Further, as shown in FIG. 5, the optical disc 1c of the fourth embodiment has a hologram 5 formed in the information recording area 2 where there is no pit 7. In this way, when the hologram 5 is formed in the information recording area 2, the hologram 5
The size itself can be increased, and the objects, figures, character patterns, etc. recorded as the hologram 5 can be more easily visually observed. However, when the hologram 5 is formed in the information recording area 2 as described above, it is necessary to prevent the information recorded as the hologram 5 from being reproduced when reproducing the pit information.

Now, with reference to FIG. 6, a condition for not reproducing the information recorded as the hologram 5 when reproducing the pit information of the optical discs 1b and 1c of the third and fourth embodiments will be described. To do. In addition, in the same figure, the reflective layer and the protective layer are not drawn in order to simplify the drawing. Generally, in an optical disc, the depth d of the information pit 7 is ¼ of the wavelength λ of the coherent light that reproduces the information pit 7. In a general optical disk reproducing apparatus for such an optical disk, it is not possible to reproduce unevenness of 1/10 or less of the wavelength λ of coherent light.
Therefore, the optical discs 1b and 1c of the third and fourth embodiments
Then, the unevenness difference d ₁ of the hologram 5 is set to 1/10 or less of the wavelength λ of the coherent light. In addition, here, the unevenness difference d ₁ of the hologram 5 is 1 / the wavelength λ of the coherent light.
Although it is set to 10 or less, since this is determined only in relation to the optical disc reproducing apparatus, the unevenness difference d ₁ of the hologram 5 does not need to be λ / 10.
It may be equal to or less than a value at which the hologram 5 cannot be reproduced as information by the optical disc device. If you do this,
It is difficult to faithfully copy the hologram 5 itself, and since the unevenness of the hologram 5 cannot be read, it becomes very difficult to copy such optical disks 1b and 1c.

As described above, since the hologram 5 is formed on the substrate 6 itself in the optical discs 1, 1a, 1b and 1c in each embodiment, it is not peeled off from the substrate like a hologram sheet, and Since it is difficult to faithfully reproduce the hologram itself, it is possible to surely discriminate whether the optical disk is a genuine product or a fake product from the presence or absence of the hologram formed on the substrate 6 itself and the difference in the hologram. Also, the presence or absence of holograms and the differences between holograms
Since it is possible to visually check, it is possible to easily determine whether the product is genuine or fake.

Next, an optical disk reproducing apparatus suitable for reproducing an optical disk having the hologram 5 formed in the information recording area 2 will be described with reference to FIG. Generally, in the optical disc reproducing apparatus, the pit information is read out and processed as a reproduction signal by utilizing the difference between the amount of reflected light of the pit portion 7 of the optical disc and the amount of reflected light at a place where the pit 7 is not formed. . Therefore, the pit depth d is set to λ / 4 as described above in order to set the optical path difference between the reflected lights to λ / 2 so that the light amount difference between the two portions is maximized. By the way, when the depth d of the pit 7 becomes smaller due to the formation of the hologram 5 or the like, the difference between the light amount of the reflected light at the pit portion 7 and the light amount of the reflected light at the portion without the pit 7 becomes smaller. Therefore, in order to make the hologram 5 formed in the information recording area 2 clear, when the unevenness difference d ₁ of the hologram 5 is increased (for example, larger than λ / 10 described above), when reproducing the pit information of the optical disc. While the hologram 5 may be reproduced, the pit information may not be clearly reproduced due to the decrease in the reflectance difference.

Therefore, in the optical disk reproducing apparatus of the present embodiment, a threshold value is set in advance for the signal level for reading the pit information, and the signal is not reproduced as a signal when the threshold value is less than this threshold value. Specifically, the optical disc reproducing apparatus is configured as shown in FIG. In the figure, 1
5 is an optical disk, 16 is a spindle motor, 17 is an optical pickup, 18 is a servo circuit, 20 is an optical pickup feeding device for driving the optical pickup 17, 19 is an access control unit for controlling the servo circuit 18 and the optical pickup feeding device 20, Reference numeral 21 is a preamplifier, 22 is a detection circuit for determining whether or not the level of the signal from the preamplifier 21 is higher than a threshold value, and 23 is a signal determined by the detection circuit 22 as a signal having a level higher than the threshold value. Eig
ht to Fourteen Modulation) CD digital signal processing unit for demodulation, 24 is a CD-ROM controller, and 25 is a host system.

The signal read from the optical disk 15 by the optical pickup 17 is amplified by the preamplifier 21. The detection circuit 22 determines whether the signal amplified by the preamplifier 21 is greater than a preset threshold level, and the signal determined to be greater is the CD.
It is output to the digital signal processing unit 23. This signal is C
In the D digital signal processing unit 23, EFM demodulation,
Then, the CD-ROM controller 24 is used to drive the CD-R.
It is scrambled as OM and sent to the host system 25 as ROM data. Access control unit 19
Is instructed by the host system 25 to operate the servo circuit 18
The pickup pickup device 20 is controlled to control the movement of the optical pickup 17, the rotation amount of the spindle motor 16, and the like.

By configuring the optical disk reproducing apparatus as described above, even if the unevenness difference d ₁ of the hologram 5 is increased, if the level of the signal read by the optical pickup 17 is smaller than the threshold value, it is not reproduced. Therefore, when reproducing the pit information of the optical disk 15, the hologram 5
Is not reproduced, and the pit information can be clearly reproduced. Therefore, the unevenness difference d of the hologram 5
_{Since 1} can be increased (for example, larger than λ / 10 described above), it is possible to form the hologram 5 that can be clearly seen.

Next, a method for manufacturing the above-described optical disc will be described. On a disk such as glass,
A photoresist material is used to form a thin film having a wavelength of ¼ of the coherent light used for reading. This disc is used as an original plate for creating an information recording medium, an information pit pattern is written on a photoresist material by a known method, and further, a hologram of a figure, an object, a character pattern, or the like as a subject is formed on the photoresist material. The interference pattern is created by the well-known method of creating holograms. The information pit pattern may be written on the photoresist after the hologram interference pattern is created. Then, the original plate is developed. For example, in the developing process, at the pit portion irradiated with light, and
Remove the photoresist material only on the bright part of the interference fringes of the hologram. The photoresist material cannot be removed because the dark portion of the hologram interference pattern is not exposed. In this way, pits and hologram irregularities are formed on the original plate. Using this original as a master original, a stamper is created by a well-known method. After that, an optical disc is created by a normal method using this stamper.

When the hologram 5 is superposed on the information recording area 2 as in the optical disc 1c of the fourth embodiment (shown in FIG. 5), the intensity of light when writing the information signal as the pit 7 and the hologram. Change the intensity of light when creating. That is, when the intensity of light at the time of hologram formation is set to be smaller than the intensity of light at the time of writing an information signal as the pit 7, the depth d of the information pit 7 when the photoresist material is developed.
Is 1/4 of the wavelength λ of the coherent light, and the unevenness d ₁ of the hologram 5 is 1/10 of the wavelength λ of the coherent light. In this example, since the photoresist material is set to a thin film of 1/4 of the wavelength λ of the coherent light used for reading, only the light intensity at the time of writing the information signal as the pit 7 is used, and Is removed and the hologram 5 is overlaid here
The intensity of the forming light does not affect the formation of the pit 7.

When the optical disc 1 of the first embodiment is produced, as described above, the pits 7 and the hologram 5 are formed.
You may create one original plate with and formed together,
An original plate of the information recording area 2 in which a plurality of pits 7 are formed,
The original of the non-recorded area 3 in which the hologram 5 is formed may be separately prepared, and then the originals may be assembled into one, or a stamper may be created for each original and each stamper may be created. You may combine them into one. As described above, since the originals of the respective areas 2 and 3 are separately prepared, the respective operations can be performed in parallel, so that the original preparation time can be shortened. Further, it is possible to reduce the risk when a manufacturing error occurs in the process of making each part separately, rather than making the original plate in a series as a single item.
Furthermore, when a plurality of holograms expressing information recording contents are formed on one optical disc, a plurality of holograms can be formed relatively easily.

In the above embodiments, the optical disc is exemplified as one of the information recording media, but the present invention is
The present invention is not limited to this, and the present invention is also applied to an optical card in which information is recorded as pits on a rectangular substrate, a magneto-optical disk for reproducing by utilizing magnetism, a magnetic disk, or a magnetic card. Good.

[0027]

According to the present invention, since the hologram is formed on the base material itself on which the information reproducible by light or magnetism is recorded, the base material of the genuine information storage medium is
Inevitably, a hologram that is extremely difficult to duplicate is formed, and the genuine product can be more reliably protected from forgery. Further, since the presence or absence of the hologram or the difference between the holograms can be visually observed, it is possible to easily determine whether the product is a genuine product or a fake product.

[Brief description of drawings]

FIG. 1 is a front view of an optical disc according to a first embodiment of the present invention.

FIG. 2 is a cross section taken along the line AA in FIG.

FIG. 3 is a cross-sectional view of essential parts of an optical disc according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts of an optical disc according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of an essential part of an optical disc according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the relationship between the unevenness of holograms provided on the optical disc of one embodiment according to the present invention and the depth of information pits.

FIG. 7 is a circuit block diagram of an optical disc reproducing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1b, 1c ... Optical disc, 2 ... Information recording area, 3 ... No information area, 4 ... Spindle hole, 5 ... Hologram, 6 ... Substrate, 7 ... Information pit, 8 ... Reflective layer, 9 ... Protective layer, 16 ... Spindle motor, 17 ... Optical pick up,
18 ... Servo circuit, 19 ... Access control part, 20 ... Optical pickup sending device, 22 ... Detection circuit, 23 ... CD digital signal processing part, 24 ... CD-ROM controller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G11B 19/04 501 H 7525-5D

Claims (9)

[Claims] 1. An information recording medium in which a plurality of pits are formed as light-reproducible information on a substrate, and a hologram is formed on the substrate itself, in addition to the information recorded as the pits. An information recording medium characterized by: 2. The information recording medium according to claim 1, wherein a transparent protective layer is formed on the hologram formed on the substrate. 3. The hologram is formed as a plurality of irregularities on the substrate, and the irregularity difference is smaller than the pit depth of the pits, and is formed by a plurality of irregularities when the pits are read as information. The information recording medium according to claim 1 or 2, wherein the unevenness is such that a hologram cannot be read. 4. An information recording area in which a plurality of pits are formed and an information-free area in which the pits are not formed are formed on the substrate, and the hologram is formed in the information-free area. The information recording medium according to claim 1, 2 or 3, characterized in that. 5. An information recording area in which a plurality of the pits are formed, and a non-information area in which the pits are not formed are formed on the substrate, and the hologram is formed in the information recording area. The information recording medium according to claim 1, 2 or 3, characterized in that. 6. The method for manufacturing an information recording medium according to claim 1, 2, 3, 4 or 5, wherein a photoresist is applied on a specific plate material, and the pit pattern to be the pits and the hologram are formed on the photoresist. Then, the photoresist is developed and only the exposed portion on the photoresist is removed to create an original plate on which the pits and the hologram are formed, and a stamper is created based on the original plate. A method for manufacturing an information recording medium, characterized in that the substrate on which the pits and the hologram are formed is created based on the stamper, and a reflective layer and a protective layer are formed on the substrate. 7. The method for manufacturing an information recording medium according to claim 4, wherein an information recording area plate member for forming the information recording area of the substrate, and a non-information area for forming the non-information area Prepare a plate material, apply a photoresist on the plate material for the information recording area, copy the pit pattern to be the pits on the photoresist, develop the photoresist, and only the portion exposed on the photoresist While removing the pits to form an information recording area original plate, while applying a photoresist on the non-information area plate material, on the photoresist, the interference pattern to be the hologram is imprinted, The photoresist is developed to remove only the exposed portion on the photoresist to prepare a master for the non-information area on which the hologram is formed. The information recording area original plate and the non-information area original plate are combined to create one original plate, and a stamper is created based on the one original plate, or the information recording area original plate and the non-information area original plate Information recording characterized in that a stamper is directly formed, the substrate on which the pits and the hologram are formed is formed based on the stamper, and a reflective layer and a protective layer are formed on the substrate. Medium manufacturing method. 8. A reproducing apparatus for an information recording medium according to claim 5, wherein an optical pickup that applies coherent light to the information recording medium and receives reflected light from the information recording medium, and a signal level from the optical pickup. Is provided with a determination means for determining whether or not is a predetermined level and outputting a signal exceeding the predetermined level, and a reproduction means for reproducing the signal output from the determination means. An information recording medium reproducing apparatus. 9. An information recording medium in which information that can be reproduced by light or magnetism is recorded on a specific base material, and in addition to the predetermined information, a hologram is formed on the base material itself. Characteristic information recording medium.