JP2008076993A - Information recording medium and secrecy information reading system of information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium making forgery additionally difficult and in combination therewith, to provide a reading system capable of reliably performing cryptanalysis of secrecy information from the information recording medium. <P>SOLUTION: The information recording medium 10 comprises arranging a plurality of minute diffraction grating elements 13 on a substrate surface. Each of the diffraction grating elements 11 is comprised of the diffraction grating consisting of a plurality of regularly arranged gratings K. The information recording medium 10 is respectively set in the grating spacing (h) and grating angle θ of the diffraction grating elements 13 and the diffraction grating elements 14 in such a manner that the diffraction light 33 formed by diffraction of the illumination light 33 emitted from a light source 31 at the diffraction grating elements 13 and the diffraction light 35 formed by diffraction of the illumination light 34 emitted from the light source 31 at the diffraction grating elements 14 make incident on a prescribed spatial region. The information recording medium 10 is so constituted that, when the diffraction light 33, 35 make incident on the prescribed region 36, the regenerate information sum in the prescribed spatial region appears as the prescribed secrecy information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information recording medium that holds confidential information that cannot be recognized with the naked eye, for example, recorded using a diffraction grating, and a confidential information reading device that detects confidential information recorded on the information recording medium.

  Conventionally, an information recording medium such as a display having a diffraction grating pattern obtained by arranging a plurality of minute diffraction grating elements (dots) having a diffraction grating on a surface on a flat substrate has been used. Has been.

  Among these, an information recording medium having a diffraction grating pattern by two-beam interference is a photosensitive film in which minute interference fringes (hereinafter referred to as diffraction grating) by two-beam interference are changed in pitch, direction, and light intensity. Obtained one after another (see, for example, Patent Document 1).

  More specifically, the diffraction grating pattern is divided into a plurality of minute diffraction grating elements, and the pitch and spatial frequency of each diffraction grating element and the arrangement of the diffraction grating elements are appropriately changed. Further, the direction of the diffraction grating on the surface of the diffraction grating element is changed for each diffraction grating element.

  Furthermore, as an information recording medium having a diffraction grating pattern, for example, an electron beam exposure apparatus is used, and an XY stage on which a planar substrate is placed is moved under the control of a computer. There has also been proposed an information recording medium on which a diffraction grating pattern having a predetermined pattern formed by recording / arranging diffraction grating elements in a pattern (see, for example, Patent Document 2).

  By the way, as a method of reading recorded information of an information recording medium having such a diffraction grating using a reading device, for example, laser light or the like is applied to a portion of pattern information recorded in an array of minute diffraction grating elements. A method has been adopted in which diffracted light is obtained by irradiation, which is read and recorded by a sensor, and authenticity is determined based on this (for example, see Patent Document 3).

In addition, a method has been proposed in which information is recorded as a pattern that cannot be observed with the naked eye, or a pattern that cannot be identified, and the information is read using a reading device that uses laser light to determine authenticity (for example, Patent Documents). 4).
JP-A-5-72406 US Pat. No. 5,058,992 Japanese Patent Laid-Open No. 5-50788 Japanese Patent Application Laid-Open No. 10-10956

  However, when reading recorded information by such a method, there are the following problems.

  That is, when reading the recorded information by such a method, if the diffraction grating pattern of the information recording medium to be judged is formed on the paper by transfer using the transfer foil, the flatness of the paper to be transferred The transfer foil is bent along the unevenness of the paper surface, and the uneven state and pattern of the diffraction grating on the transfer foil are not faithfully transferred / reproduced on the paper, so that a correct reproduced image can be obtained at the time of judgment. There is a problem that it becomes difficult to read information clearly.

  The present invention has been made in view of such circumstances, and even when the surface smoothness of a substrate having a minute diffraction grating element having a diffraction grating on the surface is poor, the recorded information can be reliably read. It is possible, and it is difficult to discriminate the area where the predetermined confidential information is recorded, and it has an even higher level of anti-counterfeiting effect, improving the visibility as a display and increasing the degree of freedom of design. It is an object of the present invention to provide an information recording medium that can be used, and a secret information reader that reads information recorded on the information recording medium.

  In order to achieve the above object, the present invention takes the following measures.

  That is, the invention of claim 1 includes a substrate and a plurality of minute diffraction grating elements arranged on the surface of the substrate, and each diffraction grating element includes a diffraction grating, and two or more of the diffraction gratings are provided. An information recording medium provided with a plurality of diffraction grating element groups consisting of elements, wherein all or part of the diffracted light formed by diffracting illumination light irradiated to the information recording medium for each diffraction grating element group is A grating interval and a grating angle of the diffraction grating elements constituting the diffraction grating elements are set so as to be incident on a predetermined region in a space facing the information recording medium, and diffracted light from the diffraction grating element groups is transmitted to the diffraction grating elements. The reproduction information sum represented by all or part of the diffracted light having a specific amount of diffracted light incident on the predetermined region is expressed as predetermined confidential information. Characterized by being adapted to.

  Therefore, in the information recording medium of the first aspect of the invention, by taking the above-described means, the confidential information can be reliably read even when the surface smoothness of the substrate surface is poor, It is possible to provide an information recording medium in which it is difficult to discriminate the area where the secret information is recorded.

  In the invention of claim 2, the change in the amount of diffracted light for each of the diffraction grating element groups can be achieved by changing the diffraction efficiency by changing the shape of the diffraction grating elements constituting the diffraction grating elements for each of the diffraction grating element groups. To be made.

  Therefore, in the information recording medium of the invention of claim 2, by taking the above-mentioned means, it becomes more difficult to discriminate the area where the predetermined confidential information is recorded, and a more advanced forgery prevention effect is obtained. This makes it possible to improve visibility as a display and increase design flexibility.

  According to a third aspect of the present invention, the change in the amount of diffracted light for each diffraction grating element group is made by changing the grating depth of the diffraction grating constituting the diffraction grating element for each diffraction grating element group. ing.

  Therefore, in the information recording medium of the invention of claim 3, by taking the above-mentioned means, it becomes more difficult to discriminate the area where the predetermined confidential information is recorded, and a more advanced forgery prevention effect is obtained. This makes it possible to improve visibility as a display and increase design flexibility.

  According to a fourth aspect of the present invention, in the information recording medium according to any one of the first to third aspects, a visible image is represented by each of the diffraction grating element groups.

  A fifth aspect of the invention is an apparatus for reading the confidential information from the information recording medium according to any one of the first to fourth aspects, wherein the information recording medium is irradiated with the illumination light, and the diffracted light. Detecting means, means for separating a specific brightness portion of the diffracted light detected by the detecting means, and means for reading confidential information based on the separated information. It is a secret information reader.

  The apparatus includes a light source and a reading unit. The light source irradiates light to the information recording medium. The reading unit detects a diffracted light, and a specific brightness portion detected by the detection function. And means for reading confidential information based on the separated information.

  Therefore, in the confidential information reading device of the invention of claim 5, by taking the above-described means, a plurality of diffraction grating element groups composed of combinations of at least two diffraction grating elements are arranged, and each diffraction grating element is arranged. Even the secret information of the information recording medium in which the diffracted light from the diffraction grating elements of the group has a different diffracted light amount for each diffraction grating element group can be read stably.

  According to the present invention, it is possible to reliably read recorded information even when the surface smoothness of a substrate having a minute diffraction grating element having a diffraction grating on the surface is poor, and to store predetermined confidential information. An information recording medium that is difficult to discriminate the recorded area, has an even higher level of anti-counterfeiting effects, can improve visibility as a display, and increase the degree of freedom of design, and A secret information detection device for an information recording medium can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view showing a configuration example of an information recording medium according to an embodiment of the present invention. That is, the information recording medium 10 according to the present embodiment has a plurality of minute diffraction grating elements 11 arranged on the substrate surface (not shown).

Each diffraction grating element 11 is formed of a diffraction grating composed of a plurality of regularly arranged gratings K, as shown in the plan view of FIG. 2, and the planar shape is square or square. The length H of one side or the long side of the square is 0.15 mm or less (for example, 0.05 mm).
The planar shape of each diffraction grating element 11 is not limited to a square or a square, and may be a circle or an ellipse. In this case, the circular diameter or the major axis of the ellipse is, for example, 0.15 mm or less.

  As shown in FIG. 3, the information recording medium 10 is arranged at a position (hollow) away from the information recording medium 10, and the illumination light 32 irradiated from the light source 31 having a circular diffusion surface is the diffraction grating element 13. The diffraction grating element 13 so that the diffracted light 33 diffracted by the light source 31 and the diffracted light 35 formed by diffracting the illumination light 34 irradiated from the light source 31 by the diffraction grating element 14 are incident on the predetermined region 36 in space. The grating interval h and the grating angle θ (shown in FIG. 2) of the diffraction grating element 14 are set.

  Further, when the diffracted light 33 from the diffraction grating element 13 and the diffracted light 35 from the diffraction grating element 14 are incident on the predetermined area 36, the information recording medium 10 has the reproduction information sum in the predetermined area 36 as the predetermined confidential information. As it appears as.

  Next, FIG. 4 shows a case where the amount of diffracted light from a plurality of diffraction grating element groups in such an information recording medium 10 is different for each diffraction grating element group.

The information recording medium 40 in FIG. 4 is provided with two diffraction grating element groups, that is, a diffraction grating element group 41 and a diffraction grating element group 42, and the amount of diffracted light from each of the diffraction grating element groups 41 and 42 is different from each other. It is set to be.
In FIG. 4, one diffraction grating element group 41 is composed of six diffraction grating elements arranged in the horizontal direction on the paper surface, and the other diffraction grating element group 42 is composed of six diffraction grating elements arranged in the horizontal direction on the paper surface. Yes.

Here, the diffracted light from one diffraction grating element group 41 is diffracted light brighter than the diffracted light from the other diffraction grating element group 42. In other words, the amount of diffracted light from one diffraction grating element group 41 is the other. The amount of diffracted light from the diffraction grating element group 42 is larger.
The method of changing the amount of diffracted light is to control the amount of diffracted light by changing the diffraction efficiency of each diffraction grating element group by changing the shape of the diffraction grating constituting the diffraction grating elements or the depth of the diffraction grating. The method to be used is used.

  When the information recording medium 40 is illuminated by the method shown in FIG. 3, the diffraction from the diffraction grating element 13 and the diffraction grating element 14 is provided in the predetermined region 36 in the space by providing the mask 37. When only light is incident and is not diffracted from the diffraction grating element 12 and is observed from the vicinity of the predetermined region 36, the diffraction grating element is observed as shown in FIG.

In FIG. 5, the diffractive grating elements that can be observed are schematically shown by diagonal lines of the grating angle. However, in actuality, the entire surface of the diffractive grating elements indicated by the diagonal lines is observed to shine, and the diffraction grating elements The group 41 and the diffraction grating element group 42 are observed with different brightness.
In FIG. 5, as in FIG. 4, one diffraction grating element group 41 is composed of six diffraction grating elements arranged in the horizontal direction on the paper surface, and the other diffraction grating element group 42 is also arranged in the horizontal direction on the paper surface 6. It is composed of two diffraction grating elements.

  Here, when the secret information is set to be recorded by the brightness element of the diffraction grating element group 42, the diffraction grating element group 42 includes the grating interval h and the grating angle of the diffraction grating element 13 and the diffraction grating element 14. A diffraction grating element having a condition equal to θ and having a diffraction light amount smaller than that of the diffraction grating element group 41 is incident on the predetermined region 36.

  That is, it is possible to read confidential information recorded as a pattern as shown in FIG. 6 by performing processing for excluding elements having the same brightness as the diffraction grating element group 41 from the pattern in FIG.

  The part of the confidential information is, for example, a signal such as “1” or “0” which is a part of the binary data. The whole of the confidential information is, for example, “1” or “0”. It is configured by combining signals and has meaningful information.

  Here, in the information recording medium 40, 36 diffraction grating elements of 6 lengths and 6 widths having three types of diffraction grating angles are arranged on the substrate surface, and the diffraction grating element 12, the diffraction grating element 13, and the diffraction grating element are arranged. It is constituted by a diffraction grating element of the grating element 14.

  The shape of the diffraction grating element is a square with one side H. If the side H of the diffraction grating element is 0.05 mm, the information recording medium 40 has a size of 0.3 mm square. The grating elements cannot be observed at all with the naked eye, and cannot be read unless a specific reading device is used, and this diffraction grating element group is observed as one diffraction grating having a size of 0.3 mm square. Is done.

  By the way, when the side H of the diffraction grating element is set to 0.05 mm, since it cannot be produced by interference fringes by laser light, the fringes of the diffraction grating are directly drawn on the photosensitive material by the electron beam drawing apparatus. By doing so, a diffraction grating element is obtained.

  In addition, it is possible to produce a diffraction grating element having a smaller size in the electron beam drawing apparatus. However, when the diffraction grating element is extremely small, it is necessary to reduce the resolution of the reading apparatus, and to increase the enlargement ratio. For this reason, there is a possibility that it becomes difficult to search for a reading position or a problem of vibration at the time of image reading by the reading device.

  Incidentally, the arrangement of the diffraction grating element group 41 and the diffraction grating element group 42 having different amounts of diffracted light in the information recording medium 40 is a state in which the respective diffraction grating elements are alternately arranged regularly, but is not limited to this arrangement. It is assumed that the confidential information is arranged to be converted into a spatial arrangement by a predetermined rule and method.

  Further, by arranging a diffraction grating element group composed of similar diffraction grating elements around the information recording medium 40 on which the confidential information is recorded, the confidential information is not retained in the diffraction grating element group. A diffraction grating element group that holds confidential information is mixed in a diffraction grating element group that does not hold information, and the existence and position of the diffraction grating element group that holds the confidential information is hidden. It is possible to make it more difficult to counterfeit by making the entire image represent a visible image.

  Next, the secret information reading device according to the embodiment of the present invention will be described.

  FIG. 7 is an explanatory diagram showing the principle of the confidential information reading device according to the embodiment of the present invention. The secret information reading device according to the embodiment of the present invention includes a light source 31 having a hollow and circular diffusion surface, and an imaging device 71 in the hollow portion.

  The light source 31 is selected by the mask 37 and irradiates the diffraction grating element 13 and the diffraction grating element 14 of the information recording medium 40 as illumination light 32 and illumination light 34.

  The imaging device 71 has a function of imaging the diffracted light 33 diffracted from the diffraction grating element 13 and the diffraction grating element 14 and the diffracted light 35 and classifying the captured image data into groups according to the brightness level of the diffracted light. It is possible to separate a group having a specific brightness from a plurality of data groups, reconstruct data, and read confidential information from the data.

  That is, in the secret information reading device of FIG. 7, a diffraction grating element that is diffracted by a specific illumination angle is selected from the diffraction grating elements of the information recording medium 40 by the mask 37, and further, a specific brightness of the image data is obtained. A diffraction grating element is selected, and information recorded by the configured data is read.

  Next, a method for manufacturing the information recording medium according to the embodiment of the present invention will be described. The information recording medium according to the embodiment of the present invention can be manufactured by a known method.

  That is, first, a master is manufactured. In the master, a resist is applied on a base material, the resist layer is divided into a large number of regions, and diffraction grating irregularities are provided on the resist layer surface in each region. This unevenness is possible by a well-known two-beam interference method using laser light or an electron beam drawing method.

  In the case of the two-beam interference method, it is necessary to use a photoresist as the resist, and in the case of the electron beam drawing method, it is necessary to use an EB resist. Since the unevenness constitutes a diffraction grating of the information recording medium, it is necessary to design the reflection diffraction direction in advance.

  And the process which reverses the unevenness | corrugation of the surface is repeated from the obtained original disk, and a practical version is manufactured. This practical version accurately reflects the unevenness of the master.

  On the other hand, a release layer and a protective layer are applied in this order on the transfer foil substrate. As the transfer foil substrate, for example, a plastic film such as a polyester film can be used.

  Moreover, a silicone resin can be used as a peeling layer. As the protective layer, a highly transparent resin is preferable. For example, an acrylic resin can be used.

  Then, the practical version is hot-pressed to transfer the surface irregularities to the protective layer surface. Next, a light reflecting layer is formed on the uneven surface.

  As the light reflecting layer, metals such as aluminum and copper can be used. It is also possible to use a transparent material having a refractive index different from that of the protective layer. Examples of such a transparent material include titanium oxide and zinc sulfide. These light reflecting layers are desirably provided by a vacuum film forming method such as vacuum deposition or sputtering.

  In addition, after providing a light reflection layer on the surface of the protective layer, it is also possible to transfer irregularities by heat-pressing the practical plate onto the surface of the light reflection layer.

  Next, an adhesive layer is applied to the surface of the light reflecting layer to obtain a transfer foil. Then, this transfer foil is overlaid on the substrate, the adhesive layer, the light reflection layer and the protective layer are transferred, and the transfer foil base material and the release layer are peeled off to obtain an information recording medium.

  As described above, in the information recording medium according to the present embodiment, confidential information can be reliably read out even if the surface smoothness of the substrate surface is poor due to the above-described action, It is possible to make it difficult to determine the area where the secret information is recorded.

  Further, in the confidential information reading device according to the present embodiment, it is difficult to determine the area where the confidential information is recorded, as in the information recording medium according to the present embodiment, due to the above-described operation. Even from a medium, confidential information can be read stably.

  The best mode for carrying out the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such a configuration. Within the scope of the invented technical idea of the scope of claims, a person skilled in the art can conceive of various changes and modifications. The technical scope of the present invention is also applicable to these changes and modifications. It is understood that it belongs to.

It is a top view which shows the structural example of the information recording medium which concerns on embodiment of this invention. It is a top view which shows an example of a diffraction grating element. It is a figure for demonstrating the diffraction of the light in the information recording medium which concerns on embodiment of this invention. It is a top view which shows the example of an arrangement | sequence of the several diffraction grating element which comprises a diffraction grating element group. It is a top view which shows the example of an arrangement | sequence of the several diffraction grating element which comprises a diffraction grating element group. It is a top view which shows the example of an arrangement | sequence of the confidential information to record. It is a conceptual diagram which shows the structural example of the confidential information reading apparatus which concerns on embodiment of this invention.

Explanation of symbols

  K: grating, h: grating spacing, θ: grating angle, 10: information recording medium, 11: diffraction grating element, 12: diffraction grating element, 13: diffraction grating element, 14: diffraction grating Elements 31... Light source 32. Illumination light 33. Diffracted light 34. Illumination light 35. Diffracted light 36. Predetermined area 37. Mask 40. Information recording medium 41 ...... Diffraction grating element group, 42 ....... Diffraction grating element group, 60... Recording information pattern, 71.

Claims (5)

A substrate,
A plurality of minute diffraction grating elements disposed on the surface of the substrate,
Each diffraction grating element is composed of a diffraction grating,
An information recording medium provided with a plurality of diffraction grating element groups each including two or more diffraction grating elements,
Each diffracting light is so arranged that all or part of the diffracted light formed by diffracting the illumination light applied to the information recording medium for each diffraction grating element group is incident on a predetermined region in the space facing the information recording medium. A grating interval and a grating angle of the diffraction grating constituting the grating element are set,
The diffracted light from each of the diffraction grating element groups becomes a diffracted light amount of a different size for each diffraction grating element group,
Reproduction information sum represented by all or part of the diffracted light of a specific amount of diffracted light incident on the predetermined region appears as predetermined confidential information.
An information recording medium characterized by the above. The change in the amount of diffracted light for each diffraction grating element group is made by changing the diffraction efficiency by changing the shape of the diffraction grating constituting the diffraction grating element for each diffraction grating element group.
The information recording medium according to claim 1. The change in the amount of diffracted light for each diffraction grating element group is made by changing the grating depth of the diffraction grating constituting each diffraction grating element for each diffraction grating element group.
The information recording medium according to claim 1. A visible image is represented by each diffraction grating element group,
The information recording medium according to claim 1, wherein the information recording medium is a recording medium. An apparatus for reading the confidential information from the information recording medium according to any one of claims 1 to 4,
A light source for irradiating the information recording medium with the illumination light;
Detecting means for detecting the diffracted light;
Means for separating a specific brightness portion of the diffracted light detected by the detection means;
Means for reading confidential information based on the separated information;
The secret information reader characterized by the above-mentioned.

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