JP2010054919A - Relief-type diffraction grating or hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relief-type diffraction grating or a hologram capable of improving such a defect that a large fluctuation/irregularity is caused in brightness or tone of color of the diffraction image or hologram image due to diffraction grating lines having the hidden information, in regard to the relief type diffraction grating or hologram having the hidden information according to a rugged structure incorporated as information difficult to ascertain by visible sight in various kinds of picture patterns used for security application. <P>SOLUTION: At least one of specified diffraction grating line which is formed by arranging prescribed information as the hidden information into a column of rugged shape is set to have the same L/S ratio as that of the other diffraction grating group and, thereby, a diffractive image without fluctuation or irregularity is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a concavo-convex structure mainly used for security applications, and more particularly, to a concavo-convex structure incorporated as information that is difficult to confirm visually in various patterns used for security applications such as diffraction gratings and holograms. The present invention relates to a relief type diffraction grating or hologram having hidden information.

  (Main use) The main use of the relief type diffraction grating or hologram of the present invention is a diffraction grating or hologram used in the field of anti-counterfeiting. Specifically, it is used after being counterfeited such as a credit card. This can cause damage to cardholders and card companies, driver's licenses, employee ID cards, ID cards such as membership cards, admission tickets for entrance examinations, passports, banknotes, gift certificates, point cards, There are stock certificates, securities, lottery tickets, horse tickets, passbooks, boarding tickets, passports, air tickets, admission tickets for various events, play tickets, prepaid cards for transportation and public telephones, and the like.

  Each of these is an information recording body that holds information having economic or social value, and it is desirable to have a function that can identify the authenticity of the recording body for the purpose of preventing damage caused by forgery. .

  In addition to these information recording media, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage of such expensive products. Boxes and cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.

  Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.

  In particular, the relief-type diffraction grating or hologram of the present invention is used in the field where it is physically impossible and economical to produce the same thing, that is, for arts and antiques. Otherwise, it is most suitable for the field where the value cannot be proved, or the field where it is necessary to confirm by the method that only the owner or the related person can know that it is very precious and not imitation.

Focusing on expensive cash vouchers, forgery cases with color copiers have frequently occurred in recent years.
For this reason, money vouchers such as high-value banknotes and gift certificates incorporate a small halftone dot or fine line that cannot be read by a color copier sensor in a part of the design, in a pattern designed with the same reflection density. . As a result, when trying to copy these high-value banknotes and gift certificates with a color copier, the copier scanner reads out small dots and fine lines, and those parts are identified as white and are identified as copies. .

(Background technology)
In addition, holograms that require advanced duplication techniques have been adopted for some high-value banknotes and other cash vouchers.
Holograms are also used as copy restraining means because a metal reflection layer is formed on the uneven surface to reproduce the hologram forming portion in black when the hologram is copied.
However, due to technological progress, counterfeit products similar to holograms have appeared. In order to check such a counterfeit product, a technique is disclosed in which hidden information that is difficult to discriminate is incorporated into a light diffraction structure of a hologram, that is, a diffraction grating, and used as a means for discriminating authenticity.
However, products using these technologies also have a problem that hidden information is slightly discriminated depending on the viewing angle.

  In order to solve such a problem, an authenticity identification structure constituted by a diffraction grating including hidden information that is extremely difficult to discriminate by a visual means and a manufacturing method thereof are provided (for example, see Patent Document 1). The technique disclosed in Patent Document 1 has first hidden information in a design constituted by a diffraction grating, and the first hidden information further includes characters / symbols or a combination thereof. The hidden information is formed by unevenness. The size of the second hidden information is 0.5 μm to 50 μm and is difficult to read even with a simple microscope.

  Moreover, even if the information on the unevenness formed as the second hidden information is read with a precise microscope, the information is random (random) information and the size is also formed randomly. When trying to counterfeit, since it is impossible to make an authentic one unless the information and size of all parts of the diffraction grating design are completely read and reproduced, it has a high anti-counterfeiting effect.

JP 2007-292899 A

  The technique disclosed in Patent Document 1 has improved anti-counterfeiting effect due to its disorder, but it is “disorder” and generates interference of transmitted light or reflected light due to “periodicity” of unevenness. This is contrary to the “diffraction principle / principle” of diffracting light “strongly”. When the entire diffraction grating or hologram produced by this technique is observed visually, the brightness of the diffraction image or hologram image There were large variations and unevenness in the shade.

  In order to solve the above-described problems, the first aspect of the relief type diffraction grating or hologram of the present invention is that the diffraction grating line group has a cross-sectional shape of a convex part (line part: L part) and a concave part (space part: S part). ) In which the diffraction grating line group includes at least one “specific diffraction grating line”, and the concave-convex ratio (L / S ratio) and the concavo-convex ratio of the specific diffraction grating line (ratio of convex portion: predetermined information display area and concave portion: non-display portion area) are the same.

The “specific diffraction grating line” is a diffraction grating line composed of a single line of uneven structure for displaying any one of predetermined characters, symbols, designs, or combination information thereof (hereinafter referred to as predetermined information). Predetermined information is positioned as “hidden information”.
As a basic structure, a plurality of diffraction grating lines are arranged in parallel as a basic structure, and when a cross section of the plurality of line groups in a vertical direction is seen, the “relief shape of the diffraction grating line group has a periodicity. (Uneven shape) can be observed.
This relief shape has “perfect periodicity” (the curve is formed by repeating one cycle of the same shape in exactly the same shape).

That is, in the cross section in a direction perpendicular to one diffraction grating line in the diffraction grating line group, the position of the grating line is constituted by, for example, one convex (convex part; line part or L part), and the subsequent part. The groove portion between the lattice lines has a shape composed of one concave portion (concave portion; space portion or S portion) (one uneven portion is one cycle. Is called a grid line.) This means that the uneven shape (for one period) is all the same as the vertical section of the other diffraction grating lines arranged side by side.
In this diffraction grating line group, at least one specific diffraction grating line is mixed and the concavo-convex shape itself is different from the others, but the L / S ratio is the same, thereby minimizing the disturbance of diffracted light. It is a limit.

  When this diffraction grating line group is illuminated with a certain light source (also referred to as light to be observed), the relationship between the wavelength of the light from the light source, the uneven shape, the period size, and the number of uneven portions Diffracted light of diffraction grating line group [Light diffracted by this diffraction grating line group when transmitted or reflected through the diffraction grating line group. Also called reconstructed image or diffraction image. In the case of an aggregate of various diffraction grating line groups (a collection of diffraction grating line groups whose period and angle arranged in parallel are varied), the reproduction images of the individual diffraction grating line groups are combined to create a more complex reproduction. It becomes an image and further a hologram image. The diffraction intensity, diffraction angle (diffraction direction), etc. are determined.

  When the light to be observed is visible light, infrared light, or ultraviolet light, the wavelength is approximately 200 nm to 4 μm, and thus the above period is twice that of 400 nm to 8 μm. Of course, in consideration of the second-order diffracted light, those having a period of 400 nm or less have the same effect. Which numerical value is adopted within this range is determined by the wavelength or wavelength range of the actually used observation light and the reproduction image reproduced by the diffracted light, that is, the design of the diffraction image or hologram image.

  In the relief type diffraction grating or hologram of the present invention, the diffraction grating line group includes at least one specific diffraction grating line, that is, any one of predetermined characters, symbols, designs, or combination information thereof (hereinafter referred to as predetermined information). Diffraction line composed of a single line of concavo-convex structure for displaying the concavo-convex structure, and the concavo-convex ratio (L / S ratio) of the diffraction grating line group and the concavo-convex ratio of the specific diffraction grating line (convex part: The predetermined information display area and the ratio of the concave portion: non-display portion area) are the same.

As described above, when the light to be observed is applied to the diffraction grating line group, the light is reflected or transmitted on the surface of the diffraction grating line group. The intensity distribution of the reflected light or transmitted light is reflected by electromagnetic waves, that is, This is explained by the diffraction theory of the second-order wave of Fraunhofer, and depends on the ratio, depth and interval between the convex and concave portions of the rectangular diffraction grating.
Based on this theory, the present invention makes the diffracted light distribution uniform by making the unevenness ratio and spacing of the specific diffraction grating lines the same as that of the diffraction grating line group, as if there was no specific diffraction grating. The same diffraction effect as that at the time, that is, a diffraction image or a hologram image is obtained.

Accordingly, when the image is observed visually or with an infrared camera or an ultraviolet camera, it is possible to realize a diffraction grating or hologram with high anti-counterfeiting properties without noticing the presence of the specific diffraction grating line.
Furthermore, the specific information is formed as hidden information on the specific diffraction grating line, and the authenticity of the diffraction grating or hologram is determined by separately reading the predetermined information by a predetermined confirmation method described below. can do.
Of course, a plurality of the specific diffraction grating lines may exist discretely, and may have different predetermined information. This further increases the anti-counterfeiting property.

  In the present invention, as a simple specific example, along with one specific diffraction grating line, predetermined information (for example, a letter “H”) as hidden information is “letterplate of“ H ”letter” in letterpress printing. As shown in FIG. This is formed as “HHHHHHH...” Along the specific diffraction grating line. The specific diffraction grating line and the diffraction grating line group are formed in parallel, and the interval between the grating lines is the same in one diffraction grating line group.

For example, when the uneven shape corresponds to visible light, the predetermined information is represented by a size of about visible light wavelength, that is, a size of 0.4 μm to 0.8 μm, but the uneven shape is more complicated. Since it is possible to incorporate a minute unevenness change with a size of 0.01 μm or less or a curve that changes from a concave part to a convex part as predetermined information, these fine changes are also genuine. It can be an element of determination, making it more difficult to “forge”.
The height of the concavo-convex shape, that is, the maximum value of the relief shape depth is determined by the design of the diffracted light intensity or the like and the above-described forming method, but is 4.0 μm or less, preferably 0.01 μm to 2.0 μm. Is preferred.

  Various methods are used to form the uneven portion. In particular, by using electron beam lithography or X-ray lithography, it has high resolution and the stability of the concavo-convex shape of the entire formation surface (the predetermined concavo-convex shape is the same shape over the entire surface of the diffraction grating or hologram). Contributes to realizing reproducibility of uneven shape, that is, periodicity without distortion and image reproducibility without distortion.), Parallelism of diffraction grating lines (within 0.01 μm at 10 mm), spacing A relief excellent in accuracy (within 10 mm, the deviation of each line is within 0.05 μm), that is, a relief master can be obtained.

In addition, these lithography methods have the characteristics that the positional accuracy of the predetermined information of the diffraction grating lines is extremely high and the resolution is high, which is preferable. In addition, in the development process, the exposure / non-exposure part is a simple diffraction grating line group. It is preferable to use a light-sensitive material in which a difference in development characteristics (development of the development, remaining height, etc.) is difficult to occur with respect to the specific diffraction grating line in which the exposed / non-exposed portions are complicated. For electron beam resist compounds, polymethyl methacrylate, polyolefin sulfone, etc. are used as positive types, and unsaturated polymers, epoxy resins, silicone resins, etc. are used as negative type electron beam resists, but calixarene resists, etc. Especially high resolution. Further, the electron beam drawing apparatus preferably has a high acceleration voltage (50 kV or more), and more preferably an apparatus capable of narrowing the electron beam system to the nm order.
As the X-ray resist compound, polymethyl methacrylate or the like is used.

Using this relief master, various types of manufacturing methods for relief type diffraction gratings or holograms can be used to produce diffraction gratings or hologram sheets, labels, and transfer foils that have high anti-counterfeiting properties and excellent design properties. Manufactured and formed into various media to be given security, and used for proof of authenticity of various media.
In addition, when creating a concavo-convex shape using lithography, the photosensitive material for lithography is uniformly applied, and a predetermined pattern is formed by exposure and development. Since the method of separating the portion to be removed is the most reproducible and stable method for forming irregularities, the “rectangular irregular shape” is preferable in terms of obtaining high reproducibility and stability.

The rectangle includes a blazed shape. In the case of blazed, predetermined information is formed on the slope, so that it is difficult to interpret the observation from directly above the information.
In this unevenness formation, not only an organic material but also a silicon substrate itself or an inorganic material such as a metal thin film can be used as a photosensitive material. The thickness accuracy of the metal thin film is much higher than that of the organic material, and an uneven shape with excellent stability can be obtained.
The predetermined information of the specific diffraction grating line may be “white display”, and may be displayed on the upper surface of the convex part of the diffraction grating line group with the area ratio of the image line part to the non-image line part being 1/10 or less. Is preferred.
In this case, the cross section of the diffraction grating line group is a diffraction grating line group having a rectangular shape as a basic shape, and it seems that only a part of the convex portion is recessed.

According to a second aspect of the relief type diffraction grating or hologram of the present invention, in the first aspect, the unevenness ratio is 1/1.
In the rectangular diffraction grating, the diffraction efficiency is highest when the L / S ratio is 1/1. Therefore, the concave / convex ratio (L / S ratio) of the diffraction grating line group is set to 1/1, and the specific diffraction grating line By setting the area ratio of the concave portion to the convex portion to 1/1, the diffraction efficiency of the relief type diffraction grating or hologram of the present invention can be maximized.

  According to the first aspect of the relief type diffraction grating or hologram of the present invention, a relief type diffraction in which the cross-sectional shape of the diffraction grating line group includes a convex part (line part: L part) and a concave part (space part: S part). In a grating or hologram, a line for displaying at least one specific diffraction grating line, that is, any one of predetermined characters, symbols, designs, or combination information (hereinafter referred to as predetermined information) in the diffraction grating line group. The diffraction grating lines having the concavo-convex structure are mixed, and the concavo-convex ratio (L / S ratio) of the diffraction grating line group and the concavo-convex ratio of the specific diffraction grating line (convex portion: predetermined information). A relief type diffraction grating or hologram having the same display area and the ratio of the concave portion: non-display portion area) can be provided.

According to the 2nd aspect of the relief type diffraction grating or hologram of this invention, the relief type diffraction grating or hologram of the 1st aspect whose said uneven | corrugated ratio is 1/1 can be provided.
It is not easy to find out where the specific diffraction grating line is located on the relief type diffraction grating or hologram, and all information must be read from end to end (even if it is repeated information, it is not Because it may have changed to different information). Furthermore, in order to know how many specific diffraction grating lines there are, it is necessary to check all the diffraction grating lines from end to end, so that relief diffraction is very difficult to counterfeit. A grating or hologram can be provided. In addition, it is possible to provide a relief type diffraction grating or hologram free from variations and unevenness due to having hidden information.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
With reference to FIG. 1, an example of a relief type diffraction grating representing predetermined information of the present invention will be described.
The diffraction grating lines in FIG. 1 represent a predetermined information consisting of a single line of concave / convex structure that displays any one of predetermined characters, symbols, designs, or combination information thereof (hereinafter referred to as predetermined information). Become. The predetermined information may be any character, symbol, or design, or combination information thereof. As the concavo-convex structure forming method, any of fine processing methods capable of submicron processing (pattern processing of 1 μm or less) can be adopted.

  In the example of FIG. 1 (relief-type diffraction grating A), L / S of the diffraction grating line group is 6/4 (period 1.0 μm (L: 0.6 μm, S: 0.4 μm)), and specific diffraction grating lines. The character “HHH...” Is set as the predetermined information of the character, and the height and width of the character is 0.6 μm × 0.5 μm (period 1.0 μm), which can be formed by electron beam lithography. A relief master having irregularities can be formed by developing the electron beam resist to a thickness of 0.3 μm.

Looking at the aa cross section of the relief master, the cross section of the diffraction grating line group is a simple rectangle as shown in FIG. 2, and the convex section of the cross section of the single specific diffraction grating line formed is complicated by predetermined information. A rectangular shape. The ratio of the convex area to the concave area is 6/4.
FIG. 3 is a view of the relief type diffraction grating A as viewed from above.
Similarly, in the same predetermined information array, the period, the L / S ratio, and the character height / width are the period 1.25 μm, 6/4, 0.75 μm × 0.6 μm, and the period 1.5 μm, 6/4, 0.90 μm × 0.7 μm diffraction grating line group and specific diffraction grating lines are formed and arranged in the three areas (B1, B2, B3) of FIG. The master of body B can be created.

  By adjusting the relief period and relief depth (height in FIG. 2) of these diffraction grating lines, the color tone and brightness (light intensity) when observed can be controlled, and each diffraction By devising the arrangement method of the grating line group (the shape occupied by the diffraction grating line group, the area, the method of interspersing, etc.), it is possible to form a diffraction grating with a complicated design or a color hologram. That is, a diffraction grating line group having the same pitch and the same angle is filled in a predetermined area to form a diffraction grating line group for each area, and each area has a predetermined area, a predetermined pitch, and an angle. When assigned and observing the entire area with white light, a color hologram can be observed.

Next, a method for producing a sheet-like relief type diffraction grating or hologram using the above-described diffraction grating master will be described.
As a transparent substrate, it is possible to reduce the thickness, and it has mechanical strength and solvent resistance and heat resistance that can withstand processing when manufacturing a relief type diffraction grating or hologram sheet, label, and transfer sheet. Use things. Since it depends on the purpose of use, it is not limited, but a film-like or sheet-like plastic is preferable.

For example, various plastic films such as polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polysulfone, polyethylene, polypropylene, polystyrene, polyarylate, triacetyl cellulose (TAC), diacetyl cellulose, and polyethylene / vinyl alcohol can be exemplified. .
From the same consideration, the thickness of the transparent substrate is desirably 5 to 50 μm, particularly 5 to 15 μm. When forming the transfer sheet, the transparent substrate 1 may be provided with a release layer made of a commonly used cellulose acetate resin, methacrylic resin or the like.

  Various thermoplastic resins, thermosetting resins, or ionizing radiation curable resins may be used as a transparent resin material for constituting a relief type diffraction grating or a hologram forming layer (hereinafter referred to as a hologram forming layer). Can do. Thermoplastic resins include acrylic ester resins, acrylamide resins, nitrocellulose resins, or polystyrene resins. Thermosetting resins include unsaturated polyester resins, acrylic urethane resins, epoxy-modified acrylic resins, and epoxy-modified unsaturated resins. A polyester resin, an alkyd resin, a phenol resin, etc. are mentioned.

  These thermoplastic resins and thermosetting resins can be used alone or in combination of two or more. One or more of these resins may be cross-linked using various isocyanate resins, or various curing catalysts, for example, metal soap such as cobalt naphthenate or zinc naphthenate may be blended. Or peroxide such as benzoyl peroxide and methyl ethyl ketone peroxide for initiating polymerization with heat or ultraviolet light, benzophenone, acetophenone, anthraquinone, naphthoquinone, azobisisobutyronitrile, or diphenyl sulfide good.

  Examples of the ionizing radiation curable resin include epoxy acrylate, urethane acrylate, acrylic-modified polyester, etc., for the purpose of introducing a crosslinked structure into such an ionizing radiation curable resin or adjusting the viscosity, A monofunctional monomer, a polyfunctional monomer, or an oligomer may be blended and used. In order to accurately reproduce fine irregularities, it is preferable that the viscosity is 0.001 to 0.1 Pascal second.

  When thermosetting resin or ionizing radiation curable resin is used, curing is performed by heating or ionizing radiation irradiation while keeping the uncured resin in close contact with the mold surface, and then cured by peeling after curing. The fine irregularities of the relief hologram can be formed on one side of the layer made of a transparent resin material. According to this method, a minute unevenness change of about 0.01 μm can be accurately replicated. A relief type diffraction grating forming layer having a relief type diffraction grating formed into a pattern by a similar method can also be used as the optical diffraction structure.

In order to accurately reproduce such a fine shape and to minimize distortion and deformation such as heat shrinkage after replication, replication can be performed at low temperature and high pressure.
In this case, it is preferable that the duplication method is a flat plate type or a rotary type, the linear pressure is 0.1 ton / m to 10 ton / m, and the duplication temperature is usually 60 ° C. to 200 ° C.

Further, a reflective thin film layer is formed on part or all of the hologram relief surface of the hologram forming layer. Since this thin film needs to reflect incident light, it is not particularly limited as long as it is a thin film having a higher refractive index than the hologram forming layer.
The reflective thin film may be either a metallic gloss reflective layer such as a metal thin film formed by a vacuum thin film method or a transparent reflective layer, but a metallic gloss reflective layer is provided partially or a transparent reflective layer is provided. In this case, it is preferable because the security object provided in contact with the reflective layer can be confirmed through the transparent reflective layer.

As a transparent reflective layer, it is almost colorless and transparent, and its optical refractive index is different from that of the hologram forming layer. A simple hologram can be produced. For example, a thin film having a higher refractive index than that of the hologram forming layer, for example, ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ S ₃ , SiO, SnO ₂ , ITO, etc.

Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Ti, Fe, Co, Zn, Ge, Pb. Cd, Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, and other oxides or nitrides, and the like can be exemplified by a mixture of two or more thereof. Also, a general light-reflective metal thin film such as aluminum can be used as a transparent reflective layer when it has a thickness of 20 nm or less and becomes transparent.

  As with the metal thin film, the transparent metal compound is formed by vapor deposition, sputtering, ion plating, CVD (chemical) on the hologram relief surface of the hologram forming layer so as to have a thickness of about 10 to 2000 nm, preferably 20 to 1000 nm. It may be provided by a vacuum thin film method such as a vapor deposition method. In order to faithfully cover fine irregularities, CVD is particularly suitable. However, in order to obtain the same reproduced image not only with the reflected light from the surface in contact with the relief hologram but also with the reflected light on the opposite surface, it is necessary to make the unevenness of the thin film the same shape as the relief hologram, The thickness of the thin film is about 10 nm.

When the relief type diffraction grating or hologram is used in a transfer form, a heat-sensitive adhesive layer is formed on the reflective layer to form a transfer film, and the adhesive layer is formed by a heated metal mold or the like. A very thin resin layer including is transferred onto a security object and used.
When a relief type diffraction grating or hologram is used in the form of a label, an adhesive layer is formed on the reflective layer, the adhesive surface is covered with a release paper, and the base film is put together with the release paper in a predetermined manner. It is punched into a size to make a label, and the release paper is peeled off and attached to a security object for use.

  Of course, if the relief type diffraction grating or hologram of the present invention is not only the design property and anti-counterfeiting property, but also the only authenticity proof means for the security object, it can be easily peeled from the security object. When the security object is molded, the relief type diffraction grating or hologram of the present invention is embedded as an integral molding, or the security object or the present It is desirable to further improve anti-counterfeiting as an integral part of the security object such that the relief type diffraction grating or the hologram itself of the invention is destroyed.

  The predetermined information may be arbitrary, may be random (such as a random number generated by a random number generator), or may be the same letter / symbol / design repeated (in this case, the diffraction efficiency can be easily calculated). Because it is information that is incorporated as information that is difficult to confirm visually, information related to various patterns as the color hologram image adopted for security applications, and security objects to which this color hologram image is transferred or pasted Or information relating to the relief diffraction grating or hologram of the present invention, such as the name of the company providing the product, the name of the company providing the product, or a mark, can be included.

In the above example, the predetermined information width is 0.5 μm to 0.7 μm, but this width is not limited and can be arbitrarily set. For example, it may be a single character, symbol, or pattern from the end of the diffraction grating line to the bridge. For example, from the end of the color hologram image to the end, it is connected as information regardless of the interruption of the diffraction grating line on the way. It may be a thing.
Since this predetermined information cannot be discriminated by visual observation or a simple microscope, in order to confirm the authenticity, the information is read using a high-precision microscope, and “regular information” (the predetermined information is actually converted into a physical shape). Information for determining authenticity at the time of formation, which may include not only the predetermined information itself but also information such as the shape, etc. In addition to the predetermined information, the data obtained by measuring the shape, etc. It may be necessary to determine whether or not the information transformed into the above may be used.

  The authenticator needs to have accurate knowledge about "regular information" when making a determination, but as described above, if it is information about various designs or security objects as a color hologram image, No special inquiry or the like is required, and it can be easily inferred to be authentic by preliminarily sending the judgment person about “related information is included as hidden characters”. Alternatively, it is also possible to use a method in which only a part of the hidden character feature is sent and placed.

Of course, when “authenticating authenticity” (when determining whether a counterfeit product is authentic, for example, when making a more reliable determination, such as when using some evidence), as “regular information”, for example, It is preferable to set not only information on characters, symbols, and designs but also more information such as the size, the thickness of the image portion, the height of the unevenness, and confirm all of them.
As a method of leaving the “regular information” of the predetermined information in the data, the three-dimensional shape information obtained by a high-resolution laser microscope is acquired, and this data and the “confirm authenticity” measured for the appraisal It is also preferable to use a method of collating data and determining “authentic” with a certain degree of coincidence such as “100% coincidence” or “100% coincidence” depending on the collation item.

Since these “regular information” are key information for authenticating authenticity, it is desirable to store and store them physically or electronically in a place with high security level (physical or electronic). Of course, encryption by DES (Data Encryption Standard), AES (Advanced Encryption Standard, same as the left) or the like may be performed. In that case, it is also preferable to provide key information to a plurality of appraisers while maintaining the confidentiality by using various key management methods such as a common key method and a public key method with higher confidentiality.

  In a simple example, it may be written on a predetermined sheet and stored in a safe or the like, or recorded as electronic data in a predetermined holder of a server that is restricted in access (password setting, etc.) The system may require a password input when reading the holder so that only a limited person can read it. In any case, it is required to define a management method in consideration of the level of confidentiality of legitimate information and considering availability (ease of use).

  It is also preferable to change the predetermined information in the middle of the diffraction grating line or to change it when the pitch (period) or angle of the diffraction grating line group is changed in order to improve the forgery prevention property. Furthermore, the diffraction grating lines in the area where the pitch and angle of the diffraction grating line group are the same are “continuous” (arranged assuming that there is no blank, regardless of the blank between the areas). The predetermined information may be formed.

In this way, unless the person who tries to counterfeit the “same thing” completely decodes all the predetermined information of all the diffraction grating lines of the relief type diffraction grating or hologram of the present invention, It can be a situation that cannot be counterfeited.
Of course, the predetermined information may be changed for each diffraction grating line group, but in this case, it is necessary to arrange the diffraction efficiency for each predetermined information.

Predetermined information and information on the uneven shape can be held as authenticity proof information by information as an actual pattern, uneven design information, and each lithography formation information (in electron beam lithography, an electron beam drawing program or the like). Of course, the same applies to information such as the pitch and angle of the diffraction grating lines.
As a method for forming the concavo-convex structure, not only a lithography method capable of forming a high-precision pattern such as the electron beam lithography and X-ray lithography described above, but also a high-precision uniform film thickness such as a metal thin film formation method is formed. Various thin film forming methods that can be used and methods for combining the patterning methods can be used.

  The diffraction efficiency of the relief type diffraction grating A is as follows: the respective areas (B1, B2, B3) of the relief type diffraction grating B in FIG. 3 are each light source, an area with a period of 1.0 μm, an area with a period of 1.25 μm, When an area with a period of 1.5 μm was measured with a corresponding semiconductor laser, they were 14%, 15%, and 15%, respectively. When the entire relief type diffraction grating B was illuminated with all light sources, each area was divided into each image and observed vividly.

In addition, “HHH...” As a hidden character was read with a simple microscope (magnification 200 ×, 400 ×) as well as visually, but it was not possible to read even the character / symbol. However, it was clearly readable with a high-resolution laser microscope that had been adjusted to the specified setting.
Of course, higher resolution microscopes such as confocal laser microscopes, electron microscopes, transmission electron microscopes, scanning electron microscopes, scanning probe microscopes, atomic force microscopes, scanning tunneling microscopes, scanning near-field light microscopes, It can be used in a range that can be physically measured, such as an X-ray microscope. Furthermore, techniques for improving resolution such as confocal method and phase shift interferometry can also be used. By using an image processing method using a high-resolution CCD camera or the like for these microscopic images, the images can be joined together precisely to obtain information for a wide area.

However, the method for determining (or appraising) “authenticity” is not limited to the above-mentioned “method of reading a large amount of predetermined information”, but paying attention to one character, symbol, symbol or part thereof, and this one It is also possible to use a method in which characters, symbols, symbols or parts thereof are “precisely measured” and only the three-dimensional shape is used for “authenticity” determination.
In this case, do not make all the focused parts the same, but slightly deform (double the thickness or add a defect) and use the information for “authenticity” determination can do. In other words, the information used for the “authenticity” determination can be determined by the security management side (the voluntary nature further enhances the anti-counterfeiting property), and it can be assumed that the counterfeiter cannot make any analogy. Become.

Another example of the relief type diffraction grating representing the predetermined information of the present invention will be described.
Relief type diffraction grating A and relief type diffraction grating B can be obtained in the same manner by setting the L / S ratio of the relief diffraction grating of the above-mentioned example to 1/1.

  The diffraction efficiency of the relief type diffraction grating A is as follows: the respective areas (B1, B2, B3) of the relief type diffraction grating body B are each light source, an area having a period of 1.0 μm, an area having a period of 1.25 μm, and a period. When the area of 1.5 μm was measured with the corresponding semiconductor laser, they were 18%, 19%, and 19%, respectively. When the entire relief type diffraction grating B was illuminated with all light sources, each area was divided into each image and observed vividly.

Example 1
An electron beam was irradiated along a predetermined relief type diffraction grating pattern while changing the intensity of the electron beam according to control data prepared in advance on a pattern formation substrate on which an electron beam resist was formed to 0.3 μm. The diffraction grating line group has a period of 1.0 μm, L / S is 6/4, and the specific diffraction grating line has a predetermined information “HHH... And its repetition” on a 0.6 μm width line. However, it irradiated so that it might become 0.6 micrometer x 0.5 micrometer.
Similarly, in the same predetermined information array, the period, the L / S ratio, and the character height / width are the period 1.25 μm, 6/4, 0.75 μm × 0.6 μm, and the period 1.5 μm, In order to form 6/4, 0.90 μm × 0.7 μm diffraction grating line groups and specific diffraction grating lines, each was carried out until the three areas (B1, B2, B3) in FIG. 3 were filled.
The substrate was developed to obtain a desired uneven relief master.

Between this master and 16 μm thick polyethylene terephthalate (Toray “Lumilar”), as ionizing radiation curable resin,
・ <Ionizing radiation curable composition A>
2-hydroxyethyl acrylate 100 parts by weight Dibutyltin dilaurate 0.1 part by weight Ionizing radiation curable composition A obtained by reacting methyl isocyanate 50 parts by weight,
・ <Ionizing radiation curable composition B>
Ionizing radiation curable composition A 80 parts by weight Polyurethane resin (Desmocol 130, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 20 parts by weight The above ionizing radiation curable composition B was prepared, and 10 μm of this ionizing radiation curable composition B was introduced. While sending out the film, an electron beam irradiation apparatus “Electro Curtain” (manufactured by ESI, USA) was used to irradiate with a dose of 3 Mrad under the conditions of 150 KeV and 15 mA to be cured.

After that, the master and the electron beam resist were peeled off and removed, and the fine irregularities of the relief hologram could be formed on one side of the layer made of a cured transparent resin material.
An aluminum thin film having a thickness of 100 nm was formed on the surface of the transparent resin by a vacuum deposition method to obtain a hologram sheet. An adhesive was applied to the hologram sheet and adhered so as to partially cover the face photograph of the passport.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each relief type diffraction grating, and obtained in advance as top secret information (only the person who manages the passport has the size and arrangement of the predetermined information) Etc. (hereinafter referred to as “predetermined information related information”). The passport authenticity was confirmed by comparing the predetermined information related information with the read information.
Separately, when the diffraction efficiency of this hologram was measured using a corresponding semiconductor laser, it was 14%, 15%, and 15%, respectively, and high diffraction efficiency was obtained.

(Example 2)
An electron beam was irradiated along a predetermined relief type diffraction grating pattern while changing the intensity of the electron beam according to control data prepared in advance on a pattern formation substrate on which an electron beam resist was formed to 0.3 μm.
Except for setting the L / S ratio to 1/1, everything was the same as in Example 1, and a relief type diffraction grating B and a passport to which it was applied were obtained.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each relief type diffraction grating, and obtained in advance as top secret information (only the person who manages the passport has the size and arrangement of the predetermined information) Etc. (hereinafter referred to as “predetermined information related information”). The passport authenticity was confirmed by comparing the predetermined information related information with the read information.
Separately, when the diffraction efficiency of this hologram was measured using a corresponding semiconductor laser, it was 18%, 19%, and 19%, respectively, and a high diffraction efficiency was obtained.

(Comparative example)
As the predetermined information, “HHH...” Was used, but the character size and the character width and character width were randomly selected between 0.3 μm and 6.0 μm, and the circle in FIG. A comparative example was obtained in the same manner as in Example 1 except that the area was completely filled with this condition.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was not divided into three patterns, but only a little iridescent. Furthermore, when it was confirmed by magnifying with a microscope of 20 times and 400 times, predetermined information could be read in some places.

By observing this hologram part with a high-resolution laser microscope, it is possible to read all the predetermined information of each relief type diffraction grating, compare the read information with the predetermined information related information obtained in advance as confidential information, and passport We were able to confirm the authenticity of.
Separately, when the diffraction efficiency of this hologram was measured using each semiconductor laser, a diffraction efficiency as low as 2-3% was obtained. This is presumably because light is diffracted in various directions and is not concentrated in one direction.

(Evaluation test) The evaluation of the reproducibility of the hologram was visually determined for the design property under a halogen lamp light source. The brightness of the hologram was evaluated by the diffraction efficiency of the diffraction grating.
Halogen lamp: Low bolt halogen lamp with 35mm diameter mirror
: Voltage 12V, luminous intensity 2300cd (candela)
Visual judgment criteria: ○ The reproduced image looks vivid and uniform. Hidden information is not visible.
: X Hidden information is not visible, but the playback image is dark and uneven. .
Diffraction efficiency measurement: Light source: Each color semiconductor laser: Kiko Giken MLX collimated laser
: Voltage DC 4.8-6.5V, beam diameter expansion 6mm at the time of parallel light
: Diffraction efficiency: reflected light intensity / incident light intensity * 100 (%)
: Criteria: A: High diffraction efficiency Diffraction efficiency 15% or more
: ○: Slightly high diffraction efficiency 〃 5% ~ 15%
: ×: Low diffraction efficiency 未 満 Less than 5%

These are the overhead views of the relief type diffraction grating A which shows an example of embodiment of this invention. These are the figures for demonstrating the aa line cross section of the relief type diffraction grating A. FIG. These are figures of the relief type diffraction grating body B which shows an example of embodiment of this invention. These are the figures which looked at the relief type diffraction grating A from the top.

Explanation of symbols

A Relief type diffraction grating (diffraction grating line group)
B Relief type diffraction grating bodies B1, B2, B3 Each diffraction grating line group

Claims (2)

  In a relief type diffraction grating or hologram in which the cross-sectional shape of the diffraction grating line group is composed of a convex part (line part: L part) and a concave part (space part: S part), there is at least one specific diffraction in the diffraction grating line group. The grating lines are mixed, and the concave / convex ratio (L / S ratio) of the diffraction grating line group, and the concave / convex ratio of the specific diffraction grating lines (convex portion: predetermined information display area, concave portion: Relief type diffraction grating or hologram characterized in that the ratio to the non-display area is the same.   2. The relief type diffraction grating or hologram according to claim 1, wherein the unevenness ratio is 1/1.

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