JPH07320014A - Information recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To provide an information recording medium which has both visual and mechanical authenticity deciding functions and its manufacturing method. CONSTITUTION:This information recording medium has such a feature that an area where a 1st light diffraction structure 41 enabling a mechanical read of recorded information is formed, and an area where a 2nd light diffraction structure 42 enabling a visual read of recorded information, do not overlap with each other, and its manufacturing method is also provided. Since white turbidity due to an overlap of the 1st light diffraction structure 41 and 2nd light diffraction structure 42 is not generated, malfunction at the time of the read by a machine is hardly caused, an accurate authenticity decision can be made, and a beautiful image can be read even visually.

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 in which recorded areas of a plurality of types of optical diffraction structures are formed so as not to overlap each other, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Cash cards, credit cards,
BACKGROUND ART Various anti-counterfeiting measures have been conventionally implemented for articles such as check cards and the like, cash vouchers, identification cards, important documents, etc., which require authentication and forgery prevention. For example, in a credit card, a rainbow hologram, which is a relief hologram having a metal reflection layer, is provided on the surface of the card as an authentication structure for visually determining the authenticity of the card.

By the way, the rainbow hologram provided on such a card may be optically duplicated and forged, and a more advanced technique is required as a forgery preventing means. Under such circumstances, Japanese Patent Laid-Open No. 59-154482 proposes a hologram in which two different holograms are recorded in combination so that they do not overlap each other in one hologram area, and it is effective in improving decorativeness. I have listed. Also, Japanese Patent Laid-Open No. 2-1659
In Japanese Patent Publication No. 87, one recording area is divided into M meshes, and each mesh is further divided into N pixels, and each pixel forms each pixel of N patterns, N screens. We proposed a switching diffraction grating and cite the improvement of forgery prevention as an effect. In the invention described in this gazette, the authentication structure is mainly intended for visual authenticity determination, but in visual authenticity determination, skill is required to distinguish similar products. Therefore, recent anti-counterfeiting means, of course, have a visual authenticity determination function,
It is required to have an authentication structure capable of making a genuine / counterfeit judgment even by a machine.

Therefore, in one hologram recording area,
There is a hologram in which a hologram obtained by photographing an object and a mechanically readable hologram such as a barcode are recorded by multiple exposure. However, according to this multiple exposure method, the interference fringes of the hologram that reproduces the object and the interference fringes of the hologram that reproduces the bar code coexist in the same recording area. It was difficult to read the bar code by a machine because the recording area scatters light, becomes cloudy in white, and the quality of the reproduced object and the image of the bar code deteriorate. In order to solve such a problem, Japanese Patent Application Laid-Open No. 63-168397 discloses that
The invention is described in which a slit with a barcode is used as a slit used when photographing a rainbow hologram by the step method. According to the present invention, the image recorded on the rainbow hologram is reproduced by the illumination of the white light, and thus it has a visual authenticity discrimination function, and the slit used when the rainbow hologram is photographed by the illumination of the laser light. By reading the bar code, the machine has a function of authenticity discrimination.

[0005]

By the way, a rainbow hologram is recorded on the hologram through an image of the slit used in the photographing of the second step, as described in Benton US Pat. No. 3,633,989. You can see the image of the object. When the rainbow hologram is illuminated with white light, the reproduction position of the slit image is slightly different depending on the wavelength of the light contained in the white light, so that a wide viewing area is obtained and the reproduced image looks like a rainbow color. . However, as in the invention of JP-A-63-168397, when a slit containing a bar code is used,
Since the object recorded in the hologram is viewed through the slit image containing the barcode, the reproduced image contains noise and the viewing area becomes narrow.Because the barcode exists as part of the slit image, There was a problem that the position to read the code was limited.

The present invention has been made in view of the above points, and an object thereof is to provide an information recording medium having a visual authenticity determining function and a machine authenticity determining function, and a manufacturing method thereof. To do.

[0007]

In order to achieve the above-mentioned object, an information recording medium according to the present invention has an area in which a first optical diffraction structure capable of mechanically reading recorded information is formed. The area in which the second light diffraction structure capable of visually reading the recorded information is formed does not overlap.

In this case, the first light diffractive structure may be a hologram capable of reading the information recorded therein only with light having high coherence, and the second light diffractive structure may also be used.
The light diffractive structure may be a hologram or a diffraction grating capable of visually reading information recorded therein by illuminating white light, and further, a region in which the first light diffractive structure is formed, The region where the second light diffraction structure is formed may not be on the same plane.

Further, in the method for manufacturing an information recording medium according to the present invention, a step of applying a photosensitive material on a substrate on which a light diffractive structure is recorded and a light diffractive structure different from the light diffractive structure on the photosensitive material. In the method for manufacturing an information recording medium, which comprises a step of recording and a step of recording a mask pattern on the photosensitive material by exposing a mask having a light-transmitting predetermined area on the photosensitive material in an overlapping manner, One of the light diffractive structure and the light diffractive structure different from the light diffractive structure is a first light diffractive structure capable of mechanically reading the information recorded therein, and is different from the light diffractive structure or the light diffractive structure. The other of the light diffractive structures is a second light diffractive structure capable of visually reading the information recorded therein.

In this case, a step of recording a mask pattern may be performed after the step of recording a light diffraction structure different from the light diffraction structure on the photosensitive material, and a step of recording a mask pattern may be performed after the step of recording a mask pattern. A step of recording a light diffraction structure different from the light diffraction structure on the photosensitive material may be performed.

[0011]

In the anti-counterfeit medium according to the present invention, a region where the first mechanically readable light diffractive structure is formed and a region where the second visually readable light diffractive structure is formed are provided. Since they do not overlap, white turbidity does not occur due to the overlap of the first light diffractive structure and the second light diffractive structure, so that a malfunction in reading by a machine is unlikely to occur.

If the first light diffractive structure is a hologram capable of reading the information recorded therein only with light having high coherence, it is difficult to understand that the mechanically readable information is recorded. Further, if the second light diffractive structure is a hologram or a diffraction grating capable of visually reading the information recorded therein by illumination of white light,
No special device is required for visual verification.
If the region where the first light diffractive structure is formed and the region where the second light diffractive structure is formed are not on the same plane, the first light diffractive structure is formed when the light diffractive structure is formed. The stress on the structure or the second light diffractive structure can be reduced.

In the method for manufacturing an information recording medium according to the present invention, a step of applying a photosensitive material on a substrate on which a light diffractive structure is recorded, and a light diffractive structure different from the light diffractive structure on the photosensitive material are applied. In the method for manufacturing an information recording medium, which comprises a step of recording and a step of recording a mask pattern on the photosensitive material by exposing a mask having a light-transmitting predetermined area on the photosensitive material in an overlapping manner, One of the light diffractive structure and the light diffractive structure different from the light diffractive structure is a first light diffractive structure capable of mechanically reading the information recorded therein, and is different from the light diffractive structure or the light diffractive structure. Since the other of the light diffractive structures is the second light diffractive structure capable of visually reading the information recorded therein, the misalignment of the position of the mask does not occur and the first light beam is not reflected. It can be formed and the region where the structure is formed, and a second region in which the light diffractive structure is not formed in different planes.

[0014]

Embodiments of the information recording medium according to the present invention will be described below with reference to the drawings. Examples of the information recording medium of the present invention include cards such as bank cards, credit cards, and prepaid cards, money such as currency, stock certificates, bills, checks, gift certificates, tickets such as airline tickets and admission tickets, identification Examples include media such as certificates that require authenticity determination when used.

FIG. 1 is a top view of a prepaid card 1 which is an embodiment of an information recording medium according to the present invention.
Visual information such as "card" and "5000 yen ticket" is recorded as information on the card base material 2 provided by an appropriate means such as printing and the pattern of Mt. Fuji as the visually readable second optical diffraction structure information. The light diffractive structure 3 is formed. FIG. 2 is a schematic enlarged sectional view of a portion of the prepaid card 1 of FIG. 1 in which the light diffraction structure 3 is formed. The protective layer 31, the relief layer 32, the reflective layer 33, and
The light diffractive structure 3 in which the adhesive layers 34 are sequentially laminated is formed on the card base material 2. Here, the relief layer 32
The first light diffractive structure 41 in which mechanically readable information is recorded and the second light in which visually readable information expressed as a pattern of Mt. Fuji in FIG. 1 is recorded. The diffractive structure 42 is formed.

The protective layer 31 covers the surface of the relief layer 32,
It is formed to protect from scratches and dirt, and is formed of a light-transmissive transparent material because the relief layer 32 having the light diffraction structure is present in the lower layer. For example, a synthetic resin film such as a polyethylene terephthalate film having a thickness of about 20 to 100 μm coated with a synthetic resin represented by an acrylic resin such as methyl methacrylate to a thickness of about 0.5 to 3 μm and cured. Can be used. When the relief layer 32 itself is made of a strong material, it is not necessary to provide the protective layer 31.

The relief layer 32 has irregularities such as an electron beam or ultraviolet ray curable resin such as urethane acrylate or melamine acrylate, an ionizing radiation curable resin such as a thermosetting resin such as methyl methacrylate, or a thermoplastic resin such as vinyl chloride. A moldable resin can be used, 1 to 1
It can be formed to a thickness of about 00 μm and used.
It is preferable that the thickness is equal to or more than the height difference between the region where the light diffractive structure 41 is formed and the region where the second light diffractive structure 42 is formed. In terms of heat resistance and weather resistance,
The use of ionizing radiation curable resins is preferred. In this embodiment, the relief layer 32 has a first diffractive direction.
The light diffractive structure 41 and the second light diffractive structure 42 are formed in a concavo-convex shape. In addition to the concavo-convex light diffractive structure, a volume hologram such as a Lippmann hologram using a photopolymer or the like, or a silver salt is used. It is also possible to use an amplitude hologram using a photosensitive material. In particular, in the case of a volume hologram, interference fringes are formed in the thickness direction of the recording material, and the space between the interference fringes partially contracts when pressure is applied, and the reproduced image with the wavelength light as designed is obtained. Therefore, it is desirable to provide a height difference in the recording area when dividing the recording area of one recording material into a plurality of areas and recording a plurality of volume holograms.

In the first light diffractive structure 41, mechanically readable information such as a bar code and bit information is recorded as a hologram object image or a diffraction grating formation region. The hologram can be a rainbow hologram that can be reproduced with white light, but from the viewpoint of forgery prevention,
An object image is difficult to recognize under white light, and it is desirable to use a Fresnel hologram or a Fourier transform hologram that can recognize only a reproduced image by light having high coherence, such as laser light. The second light diffraction structure 42 is
It is a light diffractive structure capable of visually reading recorded information, and it is possible to use a hologram in which a three-dimensional object or a two-dimensional object is recorded, or a diffraction grating that represents a two-dimensional pattern in the formed area. Although it is possible, it is not necessary to use a special device such as a laser light source to visually judge whether it is true or false.A hologram that can be reproduced with white light, for example, an image plane hologram or a holographic stereogram that uses the principle of a rainbow hologram. Further, a diffraction grating or the like is desirable.

In the example of FIG. 2, the first light diffractive structure 41
Area of the second light diffractive structure 42
The light diffractive structure is formed using a mask made of halftone dots so that the ratio of the area to the area in which is formed is 2: 3. Thus, by controlling the ratio of the occupied area, the ratio of brightness of the diffracted light from the light diffractive structure can be controlled. For example, when the area ratio is 2: 3, the brightness ratio is substantially 2: 3.

The first light diffractive structure 41 is formed along the plane A in the figure, and the second light diffractive structure 4 is formed.
2 is formed along the surface B in the drawing. In this way, when the light diffractive structure 3 is formed on the card substrate 2 by forming the first light diffractive structure 41 and the second light diffractive structure 42 on different surfaces, for example, a hot stamp method or , Label system, etc.
The light diffractive structure 41 or the second light diffractive structure 42 can be concentrated. For example, in the embodiment of FIG. 2, an ultraviolet curable resin is used as the material of the relief layer 32,
When the material of the adhesive layer 34 is a mixture of vinyl chloride resin and vinyl acetate resin, the adhesive layer 34 has a greater flexibility than the relief layer 32, and therefore the first adhesive layer 34 having a sufficient thickness is used. The pressure is absorbed by the adhesive layer 34 in the portion where the light diffractive structure 41 is formed, but the second light diffractive structure 42, which has a smaller thickness of the adhesive layer 34 than the first light diffractive structure 41, is formed. The pressure is not sufficiently absorbed by the adhesive layer 34 in the area where the second light diffraction structure 42 is formed, and the second light diffractive structure 42 is slightly damaged. However,
The reproduction condition is strict because the information mechanically read by the first light diffractive structure 41 is recorded, whereas the second
The optical diffraction structure 42 of No. 2 has only some information recorded for visual determination as to whether it is true or false.
Even with the optical diffraction structure 42, it is very difficult to visually determine the effect of the damage on the reproduced image, and the recorded information can be read mechanically.
It is very useful to adopt such a configuration for the purpose of protecting the light diffraction structure 41 of FIG.

Next, the manufacturing method of the present invention will be described. As shown in FIG. 3A, a positive type photoresist or a negative type photoresist is formed on a substrate 51 on which a second light diffraction structure 42, which is information that can be visually identified, is provided as an uneven pattern. For the substrate 51, a glass substrate may be coated with a photosensitive material and dried, and a rainbow hologram or a diffraction grating may be recorded and developed on the photosensitive material to use an original plate having an uneven surface pattern.
It is also possible to use a duplicate of the surface unevenness pattern on a metal plate, a synthetic resin plate or the like through a process such as plating or embossing. By preparing in advance a plurality of duplicates in which a general-purpose light diffraction structure is formed as an uneven surface pattern, the number of steps can be omitted and the delivery time can be shortened.

FIG. 3B shows the photosensitive material 5 of FIG.
2 shows a step of recording as mechanically readable information the first light diffraction structure 41 as an uneven pattern. For recording mechanically readable information, a mask (not shown) in which a mechanical reading bar code is recorded as a light transmitting area is used as a subject with a light scattering plate overlaid, and a laser light source is used. Of the light, the light that has passed through the light transmitting region of the mask and the light scattering plate is the object light 53, and the reference light 54 is light that is coherent with the object light 53. Generally, the light from one laser source is
A half mirror is used to split the beam into two beams, one of which is the object beam 5
3 and the other is the reference light 54. The object light 53 and the reference light 54 intersect with each other at a predetermined angle to generate an interference fringe on the photosensitive material 52 so that the position of the illumination light source and the position of the reproduced image do not overlap with each other during reproduction, and the photosensitive material 52 Records the interference fringes.

FIG. 3 (c) shows a partial ultraviolet ray 56 of the photosensitive material 52 on which the interference fringes are recorded in FIG. 3 (b).
Shows the step of performing exposure. The mask 55 in the figure is
It has an opening that partially transmits the ultraviolet rays 56,
It is arranged in close contact with the photosensitive material 52. Photosensitive material 52
Is exposed to almost the same shape as the opening of the mask 55 by the ultraviolet rays 56 that have passed through the opening of the mask 55. In the case of the photosensitive material 52 of the positive photoresist, the exposed photosensitive material is washed away in the subsequent development process, so the second light diffractive structure 42 in the lower layer of the portion corresponding to the opening of the mask 55. Appears, and the first light diffractive structure 41 is formed in the remaining portion. If the photosensitive material 52 is a negative photoresist, conversely, the first light diffractive structure 41 is formed in the portion corresponding to the opening of the mask 55, and the second light diffractive structure 42 is formed in the remaining portion. It is formed.

FIG. 3D shows a state after the photosensitive material 52 which is partially exposed by the ultraviolet ray 55 in FIG. 3C is developed. The developed photosensitive material 52 is mechanically readable information consisting of interference fringes generated by the intersection of the object light 53 and the reference light 54 containing the information of the bar code recorded in the step of FIG. 3B. And information on the opening of the mask 55 exposed in the step of FIG. 3C. A photosensitive material 52 having the first light diffractive structure 41 formed on the surface thereof is provided in a portion of the substrate 51 having the second light diffractive structure 42 formed on the surface corresponding to the opening of the mask 55. The difference in height between the surface on which the first light diffractive structure 41 is formed and the surface on which the second light diffractive structure 42 is formed is determined by the coating thickness of the photosensitive material 52 to be applied at the height shown in FIG. It is due to. This height difference requires at least a thickness such that the uneven pattern of the second light diffraction structure 42 does not affect the uneven pattern of the first light diffraction structure 41, and the convex portion of the uneven pattern of the light diffraction structure is required. The difference between the
Since the thickness is 5 μm to 0.5 μm, the thickness of 0.05 μm or more is required when the light diffraction structure has an uneven pattern. If the above-mentioned height difference is too large, the oblique illumination light is blocked by the photosensitive material 52 on which the first light diffractive structure 41 is formed and does not reach the second light diffractive structure 42. Since the diffraction efficiency of the light diffractive structure 42 is extremely reduced, the upper limit is about the size of one pixel of the second light diffractive structure 42. For example, the second light diffractive structure 42 is formed. If one of the regions is a pixel composed of a square of 50 μm square, it is desirable that the height difference is 50 μm or less.

FIG. 3 (e) shows the process of making a duplicate 57 from the developed light diffractive structure of FIG. 3 (d). The developed light diffractive structure cannot be used as a plate for embossing because the photosensitive material 52 remains as it is as it is, and when the embossed by the developed light diffractive structure, the light diffractive structure is Since the unevenness of the structure will be embossed in the opposite direction, it is possible to copy from the developed light diffractive structure.
Create 7. As a method of producing the duplicate 57, a conductive metal is vapor-deposited on the developed light diffractive structure to make it conductive, and then plated with nickel or the like to have a thickness, and then the developed light diffractive structure is formed. It may be created by peeling it off, or it may be a resin-made replicated product 5 through a plurality of replication processes.
It may be 7. Each of the duplicates 57 is used as a plate for further producing a duplicate, and if it is used when directly embossing on a card substrate or the like, the unevenness of the light diffraction structure of the duplicate 57, It is formed opposite to the original unevenness of the light diffraction structure. However, as will be described later, when a transfer sheet or a label having a high protection of the unevenness of the light diffraction structure is produced, the unevenness of the light diffraction structure of the duplicate 57 is the same as the original unevenness of the light diffraction structure. Has been formed. The replicated product 57 is preferably a metal such as nickel having high heat resistance and pressure resistance, as long as it is a replicated product 57 for producing a replicated product by embossing it in a thermoplastic resin or the like. A duplicated product 57 as a plate for molding using an ultraviolet curable resin or the like.
If it is used, it is desirable that it is made of a resin because it is easy to handle and has a property of transmitting light.

Next, the duplicate 57 created in the process of FIG.
A method for producing a transfer sheet having a light diffractive structure, which is an embodiment of the present invention, will be described with reference to FIG. Figure 4
(A) is a support 61 made of a synthetic resin such as a polyethylene terephthalate film, a protective layer 62 having a releasability from a support such as an acrylic resin, and a relief layer made of a thermoplastic resin containing methyl methacrylate resin as a main component. A laminated body in which 63 is sequentially laminated is shown. This laminated body is heated and, as shown in the figure, on the relief layer 63 side,
By applying pressure to the duplicate 57 in the direction of the arrow,
The optical diffraction structure of the present invention is formed on the relief layer 63, and a laminate having the optical diffraction structure is shown in FIG. Next, as shown in FIG. 4C, a reflective layer 64 is formed by vacuum-depositing aluminum, titanium oxide, or the like on the relief layer 63 side of this laminated body, and further a heat-sensitive adhesive containing an acrylic resin as a main component. The heat-sensitive adhesive layer 65 is coated to form a transfer sheet. As shown in FIG. 4D, the transfer sheet thus produced is brought into close contact with the transfer sheet 66 and is partially heated and pressed by a hot stamper (not shown). The heated and pressed portion is transferred to a transfer-receiving member 66 such as a card,
The portion not heated and pressed is the support 61 of the transfer sheet.
Remains on the side and is peeled off from the transferred material.

The duplicated product 57 created in the process of FIG.
A label having an optical diffractive structure, which is an example of the present invention, may be prepared by using the same as in the method of FIG. In this case, in FIG. 4, since the label is different from the transfer sheet, the protective layer 62 having peeling property from the support is omitted, and instead of the heat-sensitive adhesive layer 65, a vinyl chloride-vinyl acetate copolymer is contained as a main component. Providing an adhesive layer with an adhesive, on the exposed surface of this adhesive layer, laminate a release sheet whose surface is release treated from silicon etc., when using the label,
This release sheet can be peeled off and adhered to the adherend by pressure.

Next, a method of reading the information recording medium according to the present invention will be described. FIG. 5 relates to the reading method of the information recording medium shown in FIG. 1, and is composed of coherent light with the semiconductor laser 71 as the light source on the light diffraction structure 3 formed on the surface of the card substrate 2. The illumination beam 72 is emitted. As described above, the light diffractive structure 3 illuminated with the coherent light reproduces the barcode image 73 which is mechanically readable information, and was used at the time of photographing the rainbow hologram which is visually readable information. The slit image 74 is also reproduced. The slit image 74 is clearly reproduced because the illumination light source is the semiconductor laser 71 that emits monochromatic light, but under multi-wavelength light such as white light, it is diffracted by light as it is visually read. The wavelength dispersion is performed, the reproduction of the slit image 74 becomes unclear, and the image of the object (subject) recorded in the slit image can be seen. On the other hand, due to the redundancy of the hologram, the barcode image 73 shows the barcode as shown in the figure if it is illuminated by the coherent light in any area where the first light diffraction structure is recorded. The image 73 is reproduced. Further, under white light, as with the slit image 74, due to wavelength dispersion due to diffraction of light, the barcode image is reproduced at a position displaced by the light of each wavelength, and the barcode image 73 is visually recognized. It is difficult to do so, and the barcode image 73 is hidden.

The reading method of the bar code image 73 is as follows.
At the position where the barcode image 73 is reproduced, the barcode image 7
It can be read by providing a line sensor (not shown) longer than the length of the barcode image 73 in the direction orthogonal to each bar of 3 and can be converted into an electric signal.
When a single photo sensor (not shown) is used, the sensor is installed at a position where the barcode image 73 is reproduced, and the direction card orthogonal to each bar is moved,
Due to the redundancy of the hologram, the barcode image 73 can be read as a temporal electric signal. The information of the bar code image 73 read by the sensor can be subjected to arithmetic processing and compared with a value stored in the reading device in advance to determine the authenticity of the card.

The information recording medium according to the present invention can be modified in various ways other than the above-mentioned structure. For example, one kind of visually readable information and one kind of mechanically readable information can be used. , If the areas are formed so as not to overlap with each other, it is possible for a counterfeiter to notice that some information is recorded in the area other than the area in which the visually readable information is recorded. On the other hand, by forming two or more types of visually readable information and mechanically readable information so that the areas do not overlap each other, it is possible to read the information with a first visual inspection against a counterfeiter. In areas other than the area where the possible information is recorded,
It is possible to make the user think that the second visually readable information is recorded, and to obtain an information recording medium having a higher anti-counterfeit effect.

Further, the region where the first light diffraction structure is formed may be a halftone dot region in which the first light diffraction structure is almost uniformly dispersed over the entire surface of the light diffraction structure. By forming the pattern, the information recorded in the first light diffraction structure can be read out by irradiating any region of the light diffraction structure with coherent light, and the first light diffraction structure and the second light diffraction structure can be read. If the light diffractive structure is desired to be formed over substantially the entire surface of the light diffractive structure, the stress can be dispersed at the time of pressing. Further, in the light diffractive structure 3 of FIG. 1, the first light diffractive structure is formed in the region of the sky portion which is the background of Mt. Fuji, with respect to the region of the second light diffractive structure in which the pattern of Mt. Fuji is formed by the diffraction grating. The region in which the first light diffractive structure is formed may form a part of the pattern formed by the second light diffractive structure, such that the first region is formed in the first light diffractive structure. Recording the light diffractive structure has the effects of reducing discomfort and making it difficult to discover the first light diffractive structure itself. Furthermore, the region where the first light diffraction structure is formed may be a region surrounded by the region of the second light diffraction structure where the pattern is formed by the diffraction grating, and such a region is the first region. Recording the light diffracting structure of the first light diffusing structure, the intensity of the diffracted light by the second light diffracting structure is
Since the intensity of the diffracted light by the light diffraction structure of
There is little discomfort, and the first light diffractive structure itself is less likely to be found.

In FIG. 3, the mask 55 used for partially exposing the photosensitive material 52 with the ultraviolet rays 56 may be a general halftone dot used in printing or the like, and each halftone dot has a star shape or It may be designed in the shape of a heart, letters or symbols. Creating halftone dots designed in this way is extremely difficult because each halftone dot is extremely fine, and the forgery prevention effect is increased. Further, if the area ratio of halftone dots is gradually and continuously changed like gradation, the forgery prevention effect is further increased, and it may be completely discontinuous like a geometric pattern.

[Preferred Example] A preferred method for producing the information recording medium of the present invention will be described below. Thickness 2 μm
A positive photoresist is applied to the glass plate of 1 to 3 μm in thickness by spinner coating and dried to prepare a photosensitive plate. The light from the Ar laser (wavelength 488 nm) is split into two light beams by a half mirror, and one light beam is transmitted through a slit-shaped hologram in which a three-dimensional object is recorded, and becomes object light. The other light flux is used as the reference light. The object light and the reference light are crossed on the photosensitive plate to generate interference fringes, and the interference fringes are recorded on a photoresist and developed to form a substrate on which the interference fringes are recorded as an uneven pattern. A positive photoresist is applied onto this substrate by spinner coating to a thickness of 1 to 3 μm and dried to prepare a photosensitive material. The light from the Ar laser (wavelength 488 nm) is split into two light beams by the half mirror. A mask in which a bar code as mechanically readable information is formed as a light transmitting portion and a light scattering plate made of translucent opal glass are laminated is prepared, and one of the two light fluxes is prepared. Is radiated on the laminated body of the mask and the light-scattering plate, and the transmitted light is used as the object light. The lower luminous flux is used as the reference light. The object light and the reference light are crossed on the photosensitive plate to generate interference fringes, and the interference fringes are recorded on the photosensitive material. Next, about 50%
The mask on which halftone dots are formed is brought into close contact with the photosensitive material, and the photosensitive material is irradiated with light having a wavelength of 488 nm at 1 W / cm ² for 10 seconds, and then the mask is peeled from the photosensitive material.
The photosensitive material was developed under the condition of 25 ° C. for 1 minute, and the surface pattern of the photosensitive material on the substrate was duplicated a plurality of times to prepare a stamper made of nickel. On the other hand, the thickness of the support is 50μ
m polyethylene terephthalate film is coated with a methylmethacrylate resin to be a protective layer after transfer to a thickness of about 1 μ, and a protective layer made of an acrylic resin that receives a surface pattern from a stamper is coated to a thickness of about 3 μm on the protective layer. Then, a laminate was prepared by vacuum-depositing aluminum to a thickness of about 400 Å as a reflective layer on the exposed surface of the relief layer. 140
Under a heat and pressure condition of 0.5 ° C. for 0.5 seconds, the reflection layer side of this laminate was brought into contact with the stamper, and the surface pattern of the stamper was transferred to the reflection layer side of the laminate. Further, a heat-sensitive adhesive composed of a mixture of vinyl chloride resin and vinyl acetate resin was coated on the reflective layer side of the laminate to a thickness of about 3 μm to form a heat-sensitive adhesive layer, and the laminate was formed into a transfer foil. .
The surface of the heat-sensitive adhesive layer of the transfer foil and a card substrate made of polyethylene terephthalate having a thickness of about 0.3 mm are superposed and heated and pressed from the support side of the transfer foil to form a protective layer and relief for the heated and pressed portion. An information recording medium was prepared by forming a layer, a reflective layer, and a heat-sensitive adhesive layer on a card substrate.
When this information recording medium was observed under white light, an image of the rainbow-colored three-dimensional object could be seen, and when illuminated with a semiconductor laser, the image of the barcode could be seen. Moreover, when the surface state of the reflection layer is measured by the surface shape inspection device, as shown in FIG. 6, the first light diffraction structure 41 is hardly affected by the pressure, whereas the second light diffraction structure 41 is not affected. It was found that the effect of pressure appeared in the portion 42 as the height difference. Note that FIG.
The scale inside is a relative value.

[0034]

In the anti-counterfeit medium according to the present invention, the region having the first mechanically readable light diffractive structure and the region having the second visually readable light diffractive structure are formed. Since and do not overlap, white turbidity does not occur due to the overlap of the first light diffractive structure and the second light diffractive structure, and malfunctions when reading with a machine are unlikely to occur, and accurate authenticity determination is possible. Not only can it be performed, but also a beautiful image can be read visually.

Further, in the method for manufacturing an information recording medium according to the present invention, a step of applying a photosensitive material on a substrate on which an optical diffraction structure is recorded, and a photosensitive material having a different optical diffraction structure from the optical diffraction structure are applied. In the method for manufacturing an information recording medium, which comprises a step of recording and a step of recording a mask pattern on the photosensitive material by exposing a mask having a light-transmitting predetermined area on the photosensitive material in an overlapping manner, One of the light diffractive structure and the light diffractive structure different from the light diffractive structure is a first light diffractive structure capable of mechanically reading the information recorded therein, and is different from the light diffractive structure or the light diffractive structure. Since the other of the light diffractive structures is the second light diffractive structure capable of visually reading the information recorded therein, the misalignment of the position of the mask does not occur and the first light beam is not reflected. Since the region where the structure is formed and the region where the second light diffractive structure is formed can be formed on different planes, the first light diffractive structure and the second light diffractive structure are overlapped. Since clouding does not occur, a malfunction when reading with a machine is unlikely to occur, and it is possible to manufacture an information recording medium that can perform accurate authenticity determination and can read a beautiful image even by visual observation.

[Brief description of drawings]

FIG. 1 is a top view of one embodiment of an information recording medium according to the present invention.

2 is a schematic enlarged cross-sectional view of a portion where a light diffraction structure of the embodiment of FIG. 1 is formed.

FIG. 3 is a diagram showing an embodiment of a method for manufacturing an information recording medium according to the present invention.

FIG. 4 is a diagram showing an example of a method of manufacturing a transfer sheet having an information recording medium according to the present invention.

5 is an explanatory diagram of a reading method of one embodiment of the information recording medium according to the present invention shown in FIG. 1. FIG.

FIG. 6 is a diagram showing a measurement result of a surface state of a reflective layer of an information recording medium manufactured in a preferred example.

[Explanation of symbols]

 1 Prepaid Card 2 Card Base Material 3 Optical Diffraction Structure 31 Protective Layer 32 Optical Diffraction Structure Forming Layer 33 Reflective Layer 34 Adhesive Layer 41 First Optical Diffraction Structure 42 Second Optical Diffraction Structure

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Claims (7)

[Claims] 1. An area in which a first light diffraction structure capable of mechanically reading recorded information is formed and a second light diffraction structure capable of visually reading recorded information are formed. An information recording medium, characterized in that the recorded area does not overlap. 2. The information recording medium according to claim 1, wherein the first light diffractive structure is a hologram capable of reading information recorded therein only with light having high coherence. 3. The information recording medium according to claim 1, wherein the second light diffractive structure is a hologram or a diffraction grating capable of visually reading the information recorded therein by illumination of white light. 4. The region according to claim 1, wherein the region where the first light diffractive structure is formed and the region where the second light diffractive structure is formed are not on the same plane. Information recording medium. 5. A substrate on which an optical diffraction structure is recorded,
By applying a photosensitive material, recording a light diffractive structure different from the light diffractive structure on the photosensitive material, and by exposing a mask having a predetermined region is light-transmissive on the photosensitive material in an overlapping manner, In a method for manufacturing an information recording medium, which comprises a step of recording a mask pattern on the photosensitive material,
One of the light diffractive structure or a light diffractive structure different from the light diffractive structure is a first light diffractive structure capable of mechanically reading information recorded therein, and the light diffractive structure or the light diffractive structure A method for manufacturing an information recording medium, wherein the other of the different light diffractive structures is a second light diffractive structure capable of visually reading the information recorded therein. 6. The method of manufacturing an information recording medium according to claim 5, wherein a step of recording a mask pattern is performed after the step of recording a light diffraction structure different from the light diffraction structure on the photosensitive material. 7. After the step of recording the mask pattern,
The method for manufacturing an information recording medium according to claim 5, wherein a step of recording a light diffraction structure different from the light diffraction structure on the photosensitive material is performed.