JPH09220892A - Diffraction grating pattern with copy protection and article to which it is applied - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: Even when copying from any scanning direction, the appearance of the copy is apparently incongruous with the original pattern, and is a copy. Providing a diffraction grating (hologram) pattern that can be easily identified. SOLUTION: In a diffraction grating pattern in which relief type diffraction gratings are appropriately combined on the surface of the same substrate, and a reflective layer is formed on the entire surface, a plurality of types of diffraction different in at least different directions are provided so as to reflect and diffract in a plurality of directions. A diffraction grating pattern composed of a combination of gratings. The diffraction grating may use dots as a constituent unit, or a region where no diffraction grating exists may be provided in the pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a diffraction grating pattern for adding a function of preventing forgery due to copying to a cash voucher, a securities, etc.

[0002]

2. Description of the Related Art Conventionally, countermeasures against illegal use (counterfeiting) by copying copies of cash vouchers, securities, etc. have been demanded due to improvement in the performance of copying machines, and copying using holograms or diffraction gratings has been desired. As a proposal for prevention, JP-A-6-20
6394 is publicly known.

FIG. 1 is an explanatory diagram showing the invention disclosed in the above publication. Anti-counterfeit printed matter 2 exemplified by cash vouchers
Reference numeral 0 denotes the base material 21, the information display layer 22 (22A to 22D; the letter "1000" by printing) formed on the base material 21, and the hologram forming layer 23 formed on the upper layer.
(23A to 23D). Each of the hologram forming layers 23A to 23D is provided so that light is diffracted in different directions. When the voucher 20 is copied, the images 42A to 42D different from the visual images of the information display layer 22 and the hologram forming layer 23 are visually recognized by the diffraction action of the hologram forming layers 23A to 23D. FIG.
1A is a plan view showing the cash voucher 20, and FIG. 1B is a cash voucher 20.
It is a top view which shows the copy 40 which copied.

In the above proposal, the information display layer 22 (printed matter)
Since the information display layer (hologram forming layer 23) made of a transparent or translucent hologram or diffraction grating is formed on the upper layer or the lower layer of the information display layer 22 (printed material) so as not to be difficult to see, If the hologram pattern is not synchronized with the hologram pattern, it will be uncomfortable when the two are visually perceived. Therefore, the alignment of both is required, and a plurality of hologram patterns (four types in the figure) are required.

[0005]

According to the present invention, the print pattern and the hologram pattern are considered to be separate and independent, and when the hologram pattern is formed on the article surface, the hologram pattern and the print pattern are not necessarily synchronized with each other. There is no need, and the patterns or formations are different, each functioning to make the observer see a unique pattern (pattern), and one type (one sheet made of the same substrate) of hologram (diffraction grating) ) Is applied to the surface of the article, and the article is copied,
It is an object of the present invention to provide a hologram (diffraction grating) pattern in which a pattern (pattern) formed by the hologram (diffraction grating) cannot be completely reproduced from a copy.

[0006]

In order to achieve the above object, the diffraction grating pattern according to the present invention is a diffraction grating in which a relief type diffraction grating is appropriately combined on the surface of the same substrate and a reflection layer is formed on the entire surface. The grating pattern is characterized by being composed of a combination of a plurality of types of diffraction gratings having at least different directions so as to be reflected and diffracted in a plurality of directions.

A region where no diffraction grating exists may be provided in the pattern.

Further, as the diffraction grating forming the pattern, a fine dot-shaped diffraction grating may be used as a structural unit.

By forming these diffraction grating patterns on the surface, an article (cash voucher, securities, etc.) with copy protection is obtained.

Various methods for producing holograms and diffraction gratings are well known, and as a method for producing a diffraction grating pattern (corresponding to claim 3) having minute dots as constituent units, "2.
A method based on "light flux interference" is known.

The method of forming the pattern by the two-beam interference method is disclosed in Japanese Patent Application Laid-Open No. 60-156004 and Japanese Patent Application Laid-Open No. 2-72319 by the present applicant. The above method is a minute interference fringe (hereinafter, referred to as a method of recording dots in which interference fringes are formed by causing two beams of coherent light such as laser light to interfere with each other on a photosensitive material) by a two-beam interference method. , A diffraction grating) whose pitch, direction, and light intensity are changed as appropriate, are sequentially exposed on a photosensitive material in dot units, and a pattern is formed by a collection of dots.

An example of a picture pattern is shown in FIG.
In the figure, a plurality of dots are arranged so as to be “*”, and the diffraction gratings forming each dot have various directions for each dot. When observing the pattern with the naked eye, the diffraction grating reflects and diffracts in a direction orthogonal to the grating stripes, so any dot appears to shine when viewed from any direction.
When the viewing angle is changed, the glowing color of the dots also changes.

On the other hand, as a method for producing a diffraction grating having no dot as a constitutional unit, when coherent light (parallel light) is irradiated from two directions through a mask having an opening of a specific shape arranged on the surface of the photosensitive material, the photosensitive material is irradiated. The pattern of the specific shape is formed by interference. The diffraction grating (grating fringe) formed in this pattern is a linear diffraction grating due to the interference of parallel lights. In order to change the direction of the formed diffraction grating (grating fringe), the direction in which two coherent light beams intersect with each other and the relative direction between the photosensitive material are changed.

In a diffraction grating pattern in which relief type diffraction gratings are appropriately combined on the surface of the same substrate and a reflective layer is formed on the entire surface, a plurality of types of diffraction gratings having at least different directions are reflected and diffracted in a plurality of directions. Among the diffraction grating patterns (Claim 1) formed by the combination of the above, the pattern formed by the combination of two kinds of orthogonal diffraction gratings is effective in preventing the copying of the pattern, and the pattern by the present applicant is It is proposed by Japanese Patent Application No. 6-196602.

FIG. 3 shows an example of the diffraction grating pattern according to the above application. The pattern is composed of a character "TPTP" formed from horizontal lattices and a pattern composed of vertical lattices around the character, and a character "PTPT" composed of vertical lattices and a character formed of vertical lattices around the character. This is a pattern composed of a combination with a pattern composed of plaids.

When the above pattern (actual product) is observed with the naked eye, the manner of reflection and diffraction differs between the character and its surroundings, and the manner of reflection and diffraction also differs depending on the viewing angle. Therefore, the color and brightness expressed by the pattern are variable. To be observed. Further, since the reflective layer (metal layer) is formed on the entire surface of the pattern, the metallic luster is visually recognized as a whole.

When copying the above pattern, when the light source of the copying machine scans the pattern, the direction in which the light receiving portion of the reflected light from the original moves in accordance with the scan (hereinafter, for convenience, Scan direction) and the direction of the diffraction grating forming the pattern are orthogonal, the pattern formed by the diffraction grating is copied, but the other diffraction grating forming the other direction is formed. The pattern to be copied is not copied, and the appearance of the copy is apparently uncomfortable with respect to the original pattern, so that it can be determined that the copy is not a regular pattern but a copy.

FIG. 4 shows a copy of the pattern of FIG. 3 when the scanning direction is vertical. In FIG. 4, the characters "TPT
Since the reflected light from "P" is detected by the light receiving portion, the pattern is copied in white in the figure, but the reflected light from around the character is not detected by the light receiving portion and becomes black in the figure. . On the other hand, the reflected light from the character "PTPT" becomes black without being detected by the light receiving portion, and the reflected light from around the character is detected by the light receiving portion and is copied in white in the figure.

FIG. 5 shows a copy of the same pattern when the scanning direction is horizontal. In FIG. 5, white and black are opposite to those in FIG.

A document (copy object) composed of two kinds of orthogonal diffraction gratings is, for example, 45 ° with respect to the scanning direction.
If it is tilted, the light receiving part will detect the reflected diffracted light from both diffraction gratings even if the intensity is weak, so the actual pattern (relief type diffraction grating with a reflective layer) and the copy. Although the appearance is obviously different, the image as a whole is uncomfortable for those who do not know the existence of the relief type diffraction grating (hologram) itself having a reflective layer (those who have no preconception about metallic luster). Otherwise, there is a fear that the copy will not be perceived as abnormal and you will not notice the forgery.

FIG. 6 shows a copy when the scanning direction is inclined by 45 ° with respect to the pattern of FIG. In FIG. 6, since there is no black portion which is not copied at all, it cannot be clearly discriminated that it is a copy, and if the characters can be discriminated as a picture without a feeling of strangeness, the copy may not be considered abnormal.

Therefore, even if copying is performed from any scanning direction, the appearance of the copied material is apparently incongruous (the entire pattern is incomplete).
It must be a pattern like this.

In order to achieve the above object, it is not always necessary to make "two kinds of orthogonal diffraction gratings" as in the above proposal, and "at least a plurality of kinds of diffraction gratings having different grating fringe directions" are required. When the user sees a copy, it is clear that it is a copy.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. In the present invention, as described above, it is not specified to include at least "two kinds of orthogonal diffraction gratings", but a diffraction grating in a certain direction is scanned among "a plurality of kinds of diffraction gratings forming a pattern". It should be in the same direction, so that there is an area on the copy that is not copied at all.

FIG. 7 shows an example of the diffraction grating pattern according to the present invention. The letter "T" is composed of elements composed of a plurality of diffraction gratings in different directions, and the letter "T" is expressed as a whole by the collection of each element. Around the letter “T” may be one kind of diffraction grating (for example, a rainbow hologram in which the directions of the lattice stripes are uniform) or many types (not only the direction but also the pitch of the lattice stripes, etc.). It may be a diffraction grating with arbitrary elements),
It is only necessary that the character "T" can be discriminated when the diffraction grating pattern is observed with the naked eye. The direction of the diffraction grating formed in the entire pattern formed on the same substrate may be two or more, and the directions do not necessarily need to be orthogonal to each other.

FIG. 8 shows a copy obtained by copying the pattern of FIG. 7 at a certain scan angle. Since there is a diffraction grating in the same direction as the scanning direction, that part will not be copied at all, and inevitably a "black" area will occur on the copy, which will be recognized as something strange. become. 8A shows a case where the scan direction is vertical, and FIG. 8B shows a case where the scan direction is horizontal.
FIG. 9C is an explanatory diagram of a copy for each of the cases in which the scan direction is 45 ° to the right.

In order to always produce a "black" area in a copy regardless of the copy in any scanning direction, as described in Japanese Patent Application No. 6-196602 mentioned above, "a diffraction grating is formed in a pattern. It is effective to have a non-existing area. FIG. 9 shows an example of a pattern including a region where no diffraction grating exists.

FIG. 9 shows a pattern consisting of three elements. That is, the diffraction grating 1 forming the character “T”, the diffraction grating 2 forming the periphery of the character 2, and the region 3 where no diffraction grating exists. A copy obtained by copying the pattern of FIG. 9 is shown in FIG. FIG. 10 shows the case where the scanning direction is vertical (the letter “T” is copied and the surroundings are black).
Not limited to this, the area 3 cannot be copied and becomes black regardless of the scanning direction.

As described above, the region 3 where the diffraction grating does not exist does not have to be a part different from the character "T" and the surroundings of the character. For example, as shown in FIG. It may be mixed between the diffraction gratings so as to be bordered.

Even a user who is completely unaware of the existence of the relief type diffraction grating (hologram) having a reflection layer,
Thus, by looking at the copy (or the incomplete character "T") having the blackened area, it is possible to recognize that it is abnormal and distinguish the counterfeit product. In particular, if the regions 3 where the diffraction grating does not exist are scattered in the form of broken lines, "black" regions will appear in the copy in a broken line pattern that is difficult to see from the diffraction grating (hologram). , It becomes easier to notice the abnormality.

Further, the present invention is also applied to a pattern having minute dots as a constituent unit as shown in FIG. In the example of FIG. 2, since the diffraction grating does not exist in the area around each dot that does not form the “*”, the “*” can be copied.
Around becomes black. Naturally, if the diffraction grating of a certain dot is the same as the scanning direction, that dot will also become black on the copy. FIG. 13 shows an example of a copy of the pattern of FIG. 2 (when the scan direction is 45 ° upward to the right).

By forming such a diffraction grating pattern on the article surface, forgery by copying is prevented. Items that require counterfeiting can be applied to all items that require credit, such as cards, prepaid cards, gift certificates, traveler's checks, passbooks, tickets, admission tickets, business cards, etc., and ask for materials such as paper, resin, and metal materials. However, the surface is not limited to a flat surface, and may have a curvature or unevenness that does not cause a problem visually or in reading performance of the diffraction grating pattern.

As a method of forming the diffraction grating pattern on the surface of the article, it is preferable to form it in the form of a transfer sheet or a seal (label).

FIG. 12 is a cross-sectional explanatory view showing a structural example of the transfer sheet 10. In the case of a seal (label), generally, the configuration of the transfer sheet described later is a configuration excluding the release protection layer and the resin layer.

As shown in FIG. 12, a transfer sheet 10 having this diffraction grating pattern has a release protective layer 12, a diffraction grating pattern forming layer 13, a thin film layer 14, a resin layer on a support film 11 which is a base film. 15 and the adhesive layer 16 are sequentially laminated.

As the support film 11, for example, polyester, acetate, polycarbonate or the like is used.

The peeling protection layer 12 contains, for example, a polyacrylic resin, an acrylic-vinyl resin, or the like as a main component,
The thickness is suitably 0.5 to 2 μm.

Further, as the diffraction grating pattern forming layer 13, for example, an acrylic resin, an urethane resin, a cellulose acetate resin, a nitrocellulose resin having an acid value is used as a main component, and the thickness thereof is 0.5. Solvent coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating method to ~ 2 μm,
Alternatively, a resin layer is formed by coating and forming by a known coating method such as a screen printing method, and then drying.

On the other hand, as the thin film layer 14, Al, Cr,
It is made of a reflective metal material such as Au or Ag or a material having a refractive index larger than that of the material forming the diffraction grating pattern forming layer 13, and is provided in the diffraction grating pattern forming layer 13. In the latter case, the reflectance of the light in the thin film layer 14 becomes maximum within the reproducible angle range of the diffraction grating pattern and functions as a "reflection type", while outside the reproducible angle range of the diffraction grating pattern. , Functions as a simple transparent film and has a function of transmitting an image pattern located on the base material side.

Materials applicable to the transmissive (reflective) thin film include, for example, Sb ₂ S ₃ , Fe ₂ O ₃ , TiO ₂ , and C.
dS, CeO ₂ , PbCl ₂ , CdO, Sb ₂ O ₃ , B
i ₂ O ₃ , ZnS, WO ₃ , SiO, In ₂ O ₃ , Pb
O, Ta ₂ O ₃ , ZnO, CaO.SiO ₂ , ZrO,
Cd ₂ O ₃ and Al ₂ O ₃ can be exemplified.

In the case of a thin film layer made of any material, it is formed by a vacuum vapor deposition method, a sputtering method, an ion plating method or the like, and its thickness is 0.03 to.
0.08 μm is appropriate.

The resin layer 15 is mainly made of acrylic resin, styrene resin, polyester resin, etc., and its thickness is preferably 0.5 to 2 μm.

Further, the adhesive layer 16 is mainly made of acrylic resin or vinyl resin and has a thickness of 0.
5-2 μm is appropriate.

The adhesive layer 16 itself is a reflective thin film layer 1.
In the case where the adhesiveness with the resin layer 4 is good, the resin layer 15 need not be provided.

The resin layer 15 and the adhesive layer 16 are formed by a known coating method such as a solvent coating method such as bar coating, blade coating, air knife coating, gravure coating or roll coating, or a screen printing method. Then, it is dried to form a resin layer.

The transfer sheet 10 having the diffraction grating pattern having such a structure is superposed on the base material via the adhesive layer 16 and transferred by heating and pressing. After the transfer, the support film 11 is peeled off to obtain an article having a diffraction grating pattern.

In the case of a pattern in which dots are constituent units, there is no particular restriction on the shape or size of the dots, and the pattern (pattern) may be a figure, a diagram, a symbol, a character, etc. Anything is fine.

In the present invention, among the factors of the diffraction grating, at least the directions of the lattice fringes are set to plural directions, but the present invention is not limited to this, and other factors such as the pitch of the lattice fringes can be appropriately changed to achieve the visual effect of the pattern. Is diversified.

[0049]

As described above, according to the present invention,
Even if you try to copy the diffraction grating pattern in any scan direction, it will cause an incomplete pattern on the copy, or an area that will appear black without being copied at all. Obviously, it is possible to make the original pattern feel uncomfortable, and it is possible to easily determine that it is a copy.

[0050]

[Brief description of drawings]

FIG. 1 is an explanatory view showing a forgery prevention printed material (diffraction grating pattern) according to a conventional technique.

FIG. 2 is an explanatory diagram showing an example of a diffraction grating pattern having dots as constituent units.

FIG. 3 is an explanatory view showing a diffraction grating pattern according to a conventional technique.

FIG. 4 is an explanatory diagram showing an example of a copy of the pattern of FIG.

5 is an explanatory view showing another example of a copy of the pattern of FIG.

FIG. 6 is an explanatory view showing another example of a copy of the pattern of FIG.

FIG. 7 is an explanatory view showing an example of a diffraction grating pattern according to the present invention.

8 is an explanatory view showing an example of a copy of the pattern of FIG.

FIG. 9 is an explanatory view showing another example of the diffraction grating pattern according to the present invention.

10 is an explanatory diagram showing an example of a copy of the pattern of FIG.

FIG. 11 is an explanatory view showing another example of the diffraction grating pattern according to the present invention.

FIG. 12 is an explanatory diagram showing a configuration example in which a diffraction grating pattern is used as a transfer sheet.

13 is an explanatory diagram showing an example of a copy of the pattern of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pattern (character) consisting of a diffraction grating 2 ... Pattern (background) consisting of a diffraction grating 3 ... Area without fine dots 10 ... Transfer sheet 22 (22A to 22D) to which a diffraction grating pattern is applied ... Information display layer 23 ( 23A to 23D) ... Hologram forming layer 40 (42A to 42D) ... Copy

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03H 1/18 G03G 21/00 554 G06K 19/06 G06K 19/00 D (72) Inventor Hiroshi Watanabe 1-5-1 Taito, Taito-ku, Tokyo, Toppan Printing Co., Ltd.

Claims (4)

[Claims] 1. In a diffraction grating pattern in which relief type diffraction gratings are appropriately combined on the surface of the same substrate and a reflective layer is formed on the entire surface, a plurality of different types having different directions are reflected so as to be reflected and diffracted in a plurality of directions. A diffraction grating pattern with copy protection, which is composed of a combination of diffraction gratings. 2. The anti-copy diffraction grating pattern according to claim 1, wherein the diffraction grating pattern includes a region where no diffraction grating exists. 3. A diffraction grating pattern composed of a relief type diffraction grating in which a plurality of fine dots composed of a diffraction grating are arranged on the surface of the same substrate, and a reflective layer is formed on the entire surface, at least for each dot in the direction of the diffraction grating. An anti-copy diffraction grating pattern, which is optional and includes a region where no diffraction grating exists. 4. An article for copy protection, comprising the diffraction grating pattern according to any one of claims 1 to 3 formed on a surface thereof.