JP2007334130A - Optical structure for genuineness certification, recording medium for genuineness certification, and method for checking genuineness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical structure for genuineness certification where micro-areas where laser light reproduction type holograms are recorded and micro-areas where diffraction grating display elements are arranged in parallel, in which concealed information recorded in the laser light reproduction type holograms is easily confirmed. <P>SOLUTION: In the optical structure 3 where micro-areas 4 laser light reconstruction type holograms are recorded and micro-areas 5 where diffraction gratings are recorded are adjacently arranged in a two-dimensional way, the pitch of the diffraction gratings is set in such a manner that, when the optical structure 3 is irradiated with laser light 8 reproducing the laser light reproduction type holograms from a prescribed direction, each diffraction light 9 from the micro-areas 5 where the diffraction gratings are recorded is not superimposed on each reproduced image 10 reproduced from the micro-areas 4 where the laser light reconstruction type holograms are recorded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical structure for authenticity verification, a recording medium for authenticity verification, and a method for confirming authenticity, and relates to an optical structure mainly used for security purposes.

  The hologram / diffraction grating technology has been used in the forgery prevention field because of its distinctive visibility when viewed visually and its difficulty in manufacturing. However, an increasing number of companies handle the hologram technology itself, and at first glance these counterfeiting have come to the fore. As countermeasures, a laser beam reproduction type hologram that reproduces a specific pattern when irradiated with laser light has been proposed (Patent Documents 1 and 2, etc.).

These laser beam reproduction type holograms are often used in combination with a diffraction grating display for the purpose of preventing the appearance of forgery and concealing the laser beam reproduction type hologram (Patent Document 2). If the optical conditions of the grating display and the laser beam reproduction type hologram (CGH) are not properly designed, not only the reproduction image of the laser beam reproduction type hologram that should be reproduced when the laser beam is irradiated, but also diffraction. There is also a problem in that a reconstructed image of the lattice display also appears and it is difficult to confirm the reconstructed image of the laser beam regenerative hologram.
JP 2003-122233 A JP 2003-122234 A

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to arrange a micro area where a laser beam reproduction type hologram is recorded and a micro area where a diffraction grating display is recorded in parallel. In the optical structure for authenticity verification, it is easy to confirm the hidden information recorded in the laser beam reproduction type hologram.

The optical structure of the present invention that achieves the above object is an optical structure in which a micro area where a laser beam reproduction type hologram is recorded and a micro area where a diffraction grating is recorded are two-dimensionally adjacently arranged.
When the optical structure is irradiated with a laser beam for reproducing the laser beam reproduction hologram from a predetermined direction, the diffraction grating is recorded on a reproduction image reproduced from a micro area where the laser beam reproduction hologram is recorded. The pitch of the diffraction grating is set so that the diffracted lights from the minute areas do not overlap.

  In this case, it is desirable that the micro area where the laser beam reproduction type hologram is recorded and the micro area where the diffraction grating is recorded are mixed with each other.

  Another optical structure according to the present invention has a boundary line between a region occupied by a group of minute areas in which a laser beam reproduction hologram is recorded and a region occupied by a group of minute areas in which a diffraction grating is recorded. In the optical structure that is arranged in parallel with each other, the size of the micro area recording the diffraction grating close to the boundary line is set smaller than the size of the micro area recording the diffraction grating at a position away from the boundary line. In addition, a gap is provided between minute areas corresponding to the size of the small area.

  In the above, the laser beam reproduction type hologram can be a hologram in which the phase information of the Fourier transform image of the original image is multivalued and recorded as a depth, or a relief hologram by two-beam interference.

  The present invention includes an authenticity proof recording body having the above optical structure.

  Further, the present invention irradiates coherent light to the optical structure described above or the optical structure included in the authenticity proof recording body, and a reproduced image is used as a reference prepared in advance. This includes a method for confirming authenticity in which a difference is determined by comparison with an image.

  In the optical structure, authenticity recording medium, and authenticity confirmation method of the present invention described above, the reproduced image reproduced from the laser beam reproduction hologram and the diffracted light from the diffraction grating do not overlap. Even if the reproduced image and the diffracted light overlap, the intensity of the diffracted light is relatively weak, so that the reproduced image can be easily confirmed and the authenticity can be confirmed reliably. For example, even if hidden information whose pattern cannot be confirmed under visual conditions is recorded on a laser beam reproduction type hologram, the hidden information can be easily and reliably confirmed by laser beam irradiation.

  Hereinafter, an optical structure for authenticity verification, a recording medium for authenticity verification, and a method for verifying authenticity according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining one embodiment of an authenticity proof recording body including an authenticity proof optical structure and a method for confirming the authenticity of the present invention.

  In FIG. 1, an authenticity proof recording body 1 includes an optical structure 3 for authenticity verification laminated on an upper surface of a substrate 2, or the upper surface of the substrate 2 and the upper surface of the optical structure 3. Are embedded and laminated so as to be on the same plane.

  In the case of this example, the optical structure 3 for proof of authenticity is constituted by square micro optical unit areas 4 and 5 which are two-dimensionally adjacently arranged. In the example shown in FIG. Optical unit areas 4 and 5 are arranged in a vertical and horizontal matrix. For the purpose of making visual confirmation difficult, the micro-optical unit areas 4 and 5 are preferably smaller in size, and specifically 0.3 mm or less. This is because, when the size of the micro optical unit areas 4 and 5 exceeds 0.3 mm, the possibility that the micro optical unit areas 4 and 5 can be visually recognized is increased and the possibility of analysis is generated. The size of the micro optical unit areas 4 and 5 is represented by the length of one side if it is a square, the length of a long side if it is a rectangle, the diameter if it is a circle, the major axis if it is an ellipse, etc. If it is a shape, it shall be indicated by the maximum value of the passing dimension.

  Here, in the micro optical unit area 4, a laser beam reproduction type hologram that is a kind of a computer generated hologram (CGH), in which phase information of a Fourier transform image of an original image is multi-valued and recorded as a depth (Patent Document 1, 2) is a recorded micro area. Of course, a relief hologram by two-beam interference may be used as the laser beam reproduction type hologram. When a laser beam having a predetermined wavelength is irradiated from a specific direction, for example, the vertical direction, the micro area 4 in which the laser beam reproduction type hologram is recorded reproduces the original image in a specific direction, for example, the front direction, and the original image is hidden. Information can be confirmed in this state.

  The micro optical unit area 5 is a micro area where a linear or curved diffraction structure in which light is diffracted in a specific direction is recorded. The micro area 5 in which the diffraction grating is recorded appears to be colored in a specific color according to the direction and pitch of the diffraction grating under white light.

  In addition, the surface of the fine irregularities formed in these micro optical unit areas 4 and 5 is usually made of a reflective metal thin film such as Al or a thin film made of a material having a light refractive index different from that of the cured resin film. A reflective layer is laminated and formed along the fine irregularities.

  Now, when such an optical structure 3 is irradiated with the laser beam 8, it hits the micro-optical unit area 5 of the diffraction grating adjacent to or around the micro-optical unit area 4 of the laser light reproducing hologram, and the micro-optical The diffracted light diffracted by the diffraction grating of the unit area 5 overlaps with the reproduced image from the laser beam reproduction type hologram of the micro-optical unit area 4, and the reproduced image becomes difficult to see, and the hidden information for authenticity confirmation is confirmed. It becomes difficult to do.

  A method for eliminating such overlap and making it easy to see the reproduced image will be described in the following embodiments.

  As shown in FIG. 2, a laser beam having a wavelength of 650 nm from the front direction of the optical structure 3 including the micro optical unit area 4 in which the laser beam reproducing hologram is recorded and the micro optical unit area 5 in which the diffraction grating is recorded. When 8 is irradiated from the vertical direction, a hologram reproduction image 10 of 45 mm long × 35 mm wide is projected onto the screen 7 separated by 100 mm. At this time, in order that the diffracted light 9 by the diffraction grating recorded in the micro optical unit area 5 does not overlap the reproduced image 10, the horizontal reproduction angle is 10 ° (FIG. 2A), and the vertical reproduction is performed. The angle is 13 ° (FIG. 2B) or more. That is, the diffracted light 9 from the micro optical unit area 5 of the diffraction grating arranged around or in the vicinity of the micro optical unit area 4 of the laser beam reproducing hologram is reproduced from the micro optical unit area 4 of the laser beam reproducing hologram. In order not to overlap with each other, the diffraction angle of the diffracted light 9 needs to be 13 °, 10 ° or more in the vertical and horizontal directions.

  From the diffraction formula d = λ / sin θ (d: diffraction grating pitch, λ: laser beam wavelength, θ: diffraction angle), the diffraction grating pitch of the longitudinal diffraction grating recorded in the micro-optical unit area 5 is d ≦ The diffraction grating pitch of the transverse diffraction grating of 2.89 μm must satisfy d ≦ 3.74 μm.

  FIG. 3 shows that, as described above, the diffracted light 9 from the micro-optical unit area 5 of the diffraction grating arranged around or in the vicinity of the micro-optical unit area 4 of the laser light reproducing hologram is the micro optical of the laser light reproducing hologram. It is a figure which shows the example set so that it might not overlap with the reproduced image 10 from the unit area 4. FIG. When the optical structure 3 is arranged as shown in FIG. 3A and the laser beam 8 is irradiated from the front, the diffraction grating recorded in the micro-optical unit area 5 of the diffraction grating is as shown in FIG. If the pitch is set to d ≦ 3.74 μm as described above, the diffracted light 9 deviates from the lateral reproduction region of the reproduced image 10 as shown in FIG. The incident position, and does not interfere with the observation of the reproduced image 10. If the diffraction grating recorded in the micro-optical unit area 5 of the diffraction grating is a lateral diffraction grating as shown in FIG. 3D, the pitch is set to d ≦ 2.89 μm as described above. As shown in FIG. 3E, the diffracted light 9 is incident on a position deviated from the vertical reproduction area of the reproduced image 10 and similarly does not disturb the observation of the reproduced image 10.

FIG. 4 is a diagram for explaining another embodiment. In this embodiment, even when the reproduced image 10 from the micro optical unit area 4 of the laser beam reproducing hologram and the diffracted light 9 from the micro optical unit area 5 of the diffraction grating overlap, the intensity of the diffracted light 9 is relatively high. If it is weak, it is based on the knowledge that the visibility of the reproduced image 10 is not affected. As shown in FIG. 4 (a), in the optical structure 3, the region occupied exclusively by the group of micro optical unit areas 4 of the laser beam reproducing hologram and the group of micro optical unit areas 5 of the diffraction grating are occupied. The size of the micro-optical unit area 5 of the diffraction grating adjacent to the group of micro-optical unit areas 4 of the laser beam reproduction type hologram is set to the size of the micro-optical unit area 4 The smaller the distance is, the smaller the optical unit area 5 is. That is, as shown in FIG. 4 (b), the micro-optical unit areas 5 adjacent to the micro-optical unit areas 4 of the laser beam reproduction type hologram by the reference numeral 5 _1, the micro-optical unit areas 5 closer then at reference numeral 5 ₂ , if the micro-optical unit zone 5 close to the third represented by reference numeral 5 ₃ etc., more smaller than the dimensions of the micro-optical unit areas 5 ₁ normal size of the minute optical unit areas 5, micro-optical unit areas The laser beam is irradiated to reproduce the laser beam reproduction hologram in the group of micro-optical unit areas 4 as shown in FIG. Even if the light 8 leaks into the group of the micro-optical unit areas 5 of the parallel diffraction grating, the micro-optical unit areas whose normal light intensity is incident on the micro-optical unit areas 5 ₁ , 5 ₂ , 5 ₃ , 5 ₄ Compared to the amount of incident light when only 5 Accordingly, the intensity of the diffracted light 9 becomes weaker, and even if the diffracted light 9 overlaps the reproduced image 10 as shown in FIG. There is no.

  FIG. 5 is a diagram for explaining still another embodiment. This embodiment relates to the mutual arrangement of the micro optical unit area 4 of the laser beam reproducing hologram and the micro optical unit area 5 of the diffraction grating. As shown in FIG. The micro-optical unit areas 4 and the micro-optical unit areas 5 that are adjacently arranged in dimension are mixed together, thereby making the micro-optical unit areas 4 of the laser beam reproducing hologram inconspicuous. As a way of mixing, a method of periodically mixing the micro optical unit areas 4 in the group of the micro optical unit areas 5 may be used. However, it is less noticeable if the micro optical unit areas 4 are not mixed vertically and horizontally and are randomly mixed.

  Next, the authenticity confirmation method of the present invention will be described. The authenticity confirmation method of the card-like authenticity proof recording body 1 described with reference to FIG. 1 will be described. As shown in FIG. 6, the optical structure 3 of the authenticity proof recording body 1 includes a laser light source. 11 is used to irradiate laser light 8 which is coherent light having a predetermined wavelength. The beam diameter of the laser beam 8 may be smaller than the micro optical unit area 4 of the optical structure 3, but is preferably larger than the micro area constituting the micro optical unit area 4. By this irradiation, reproduced images a and b corresponding to multi-value depth information based on the original images A and B, which are arranged in advance in the micro optical unit area 4, are reproduced. These micro areas in which multi-valued depth information based on the original images A and B is recorded appear white under white light. In addition, the diffraction gratings C and D are recorded by the laser light irradiation, that is, the light is diffracted in a specific direction in the micro area 5 where the information of the diffraction gratings C and D is recorded. These micro-areas 5 where the diffraction grating is recorded appear to be colored in a specific color according to the direction and pitch of the diffraction grating under white light. Therefore, the micro optical unit area 4 in which multi-valued depth information based on the original images A and B is recorded and the micro optical unit area 5 in which information of the diffraction gratings C and D are recorded are randomly selected as described above. By mixing them together, it is possible to make the minute optical unit area 4 that looks white when viewed visually inconspicuous. The reproduced images a and b reproduced from the laser beam reproducing hologram are collectively referred to as “reproduced images”. The authenticity can be confirmed by comparing the reconstructed image with a reference image prepared in advance and determining whether they are the same or different.

  Therefore, assuming a certain surface 13, for example, the reproduced image a in the area 13a on the right, the reproduced image b in the area 13b on the left, the diffracted light c in the area 13c on the back, and Since the diffracted light d can be observed in the area 13d in the foreground (the diffracted lights c and d are set so as not to overlap the reproduced images a and b), the surface 13 is the upper plate of the box, and the laser Prepare an instrument equipped with a light source 11 and a fixing base (not shown) for authenticity recording, and provide a transmission screen in each of the areas 13a to 13d on the upper plate of the box. In this case, it is possible to determine the reproduced image using this instrument, and it is easy to confirm the authenticity of the authenticity-providing recording body 1. Further, the light diffracted in the minute area 5 in which the diffraction grating is recorded may be detected at a predetermined position to serve as auxiliary means for confirming authenticity.

  Although the present invention basically has the above-described structure, the authenticity proof recording member 1 may include the following elements. The cards described with reference to FIG. 1 usually have a magnetic recording layer. The magnetic recording layer is usually in the form of a stripe having a width of about 5 to 10 mm. The magnetic recording layer is applied to a thin plastic sheet directly applied by applying a magnetic paint on the surface or inside of the base material 2 and stripes are applied. It is formed by transfer using a magnetic recording layer transfer sheet prepared by being cut into a shape and pasted, or laminated on a temporary base sheet so as to be peelable.

  In general recording media including cards, a magnetic recording layer is usually provided. The function of the magnetic recording layer may be replaced with an optical recording layer, an IC module, or the like. However, even if an optical recording layer or an IC module is provided, it is preferable to provide a versatile magnetic recording layer. Further, in addition to the optical structure 3 in the present invention, a normal hologram or the like (including a diffraction grating) may be provided, and in this way, attention and interest to the optical structure 3 in the present invention is increased. Can be diverted.

  The authenticity recording body 1 of the present invention may be provided with appropriate characters by printing or the like. In the case of a card, the contents expressed in characters include the issuing company, the name of the card, the issue number, the expiration date, the name of the holder, or a cautionary note. Some of these, for example, the issue number, the expiration date, and the name of the holder may be formed by unevenness by embossing. In addition, the base material 2 may be colored or patterned to decorate the authenticity recording body 1 and is usually printed.

  The authenticity proof recording body 1 of the present invention is not only for use in card applications, but various articles can be used as the base material 2 and the optical structure 3 can be laminated thereon. Depending on the article, there are a case where the article itself is a recording body having information and a case where the article itself does not have information but is a recording body provided with information by stacking the optical structures 3.

  The authenticity proof recording body 1 of the present invention may be an ID (identity verification) card, and specifically may be a bank saving deposit card, a credit card, an identification card or the like. Further, it may be an examination slip, a passport or the like which is not necessarily in a card form. The authenticity proof recording body 1 may be a bill, a gift certificate, a stock certificate, a securities, a bankbook, a boarding ticket, an air ticket, or a prepaid card for transportation or a public telephone. In these, information such as an amount, an issuer, an issue number, or a cautionary note is recorded.

  The authenticity proof recording body 1 of the present invention does not necessarily have information, but can be various articles to which information is given by laminating the optical structure 3. The various articles are, for example, world-renowned luxury goods such as luxury watches, precious metals, jewelry, etc., so-called brand goods, articles such as storage boxes and cases, and these are usually expensive. Therefore, it is easy to be forged. In some cases, a tag that is hung on a product can also serve as the base material 2 of the authenticity proof recording body 1.

  Similarly, the optical structure 3 can be laminated as the base material 2 on a storage medium in which music software, video software, computer software, game software, etc. are recorded, and articles such as those cases. These are not necessarily expensive, but if they are illegally copied in large quantities and put on the market, there is a risk that the distributor of the genuine product may suffer serious damage.

  In any authenticity proof recording body 1, the optical structure 3 is provided regardless of whether the portion other than the optical structure 3 has information or not. By confirming the authenticity of the optical structure 3, it is possible to confirm the authenticity of the substrate 2 having the optical structure 3, that is, the authenticity proof recording body.

  As described above, the optical structure for authenticity proof, the authenticity proof recording body, and the authenticity confirmation method of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments, and is various. Can be modified.

It is a figure for demonstrating one Example of the authenticity recording body provided with the optical structure for authenticity verification of this invention, and the confirmation method of the authenticity. It is a figure for demonstrating the principle for canceling the overlap of the reproduced image from a laser beam reproduction type hologram, and the diffracted light from a diffraction grating. It is a figure which shows the example set so that the reproduced image from a laser beam reproduction | regeneration type | mold hologram and the diffracted light from a diffraction grating may not overlap. It is a figure for demonstrating another Example. It is a figure for demonstrating another Example. It is a figure for demonstrating the authenticity confirmation method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Authenticity proof recording body 2 ... Base material 3 ... Optical structure 4 ... Micro optical unit area (laser beam reproduction type hologram)
5 ... Micro optical unit area (diffraction grating)
5 ₁ , 5 ₂ , 5 ₃ , 5 ₄ ... micro optical unit area (diffraction grating)
7 ... Screen 8 ... Laser light 9 ... Diffracted light 10 ... Hologram reproduction image 11 ... Laser light source 13 ... Assumed planes 13a, 13b, 13c, 13d ... Area

Claims (7)

In an optical structure in which a micro area where a laser beam reproduction type hologram is recorded and a micro area where a diffraction grating is recorded are adjacently arranged two-dimensionally,
When the optical structure is irradiated with a laser beam for reproducing the laser beam reproduction hologram from a predetermined direction, the diffraction grating is recorded on a reproduction image reproduced from a micro area where the laser beam reproduction hologram is recorded. An optical structure characterized in that a pitch of the diffraction grating is set so that diffracted light from a minute area does not overlap. 2. The optical structure according to claim 1, wherein a micro area in which the laser beam reproduction type hologram is recorded and a micro area in which the diffraction grating is recorded are mixed with each other. In an optical structure in which a region occupied by a group of micro-areas recording a laser beam reproduction type hologram and a region occupied by a group of micro-areas recording a diffraction grating are juxtaposed across a boundary line The size of the micro area in which the diffraction grating adjacent to the boundary line is recorded is set smaller than the size of the micro area in which the diffraction grating at a position away from the boundary line is recorded. An optical structure characterized in that a gap is provided between minute areas. 4. The optical structure according to claim 1, wherein the laser beam reproduction type hologram includes a hologram recorded as a depth by multi-leveling phase information of a Fourier transform image of an original image. 5. body. The optical structure according to any one of claims 1 to 3, wherein the laser beam reproduction type hologram is a relief hologram by two-beam interference. A recording medium for proof of authenticity comprising the optical structure according to any one of claims 1 to 5 on a substrate. The optical structure according to any one of claims 1 to 5 or the optical structure possessed by the recording medium for authenticity according to claim 6 is irradiated with coherent light and reproduced. A method for confirming authenticity, wherein an image is compared with a reference image prepared in advance and a difference is determined.

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