JP4270808B2 - Hidden pattern discrimination method by optical diffraction structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for discriminating a hidden pattern by an optical diffraction structure that is difficult to discriminate in a normal visual state.
[0002]
[Prior art]
In recent years, forgery cases of high-value banknotes and gift certificates using color copiers have frequently occurred.
For this reason, high-value banknotes and gift certificates have a small halftone dot or fine line that cannot be read by a color copier sensor in a part of the design, and is incorporated 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. .
[0003]
In addition, a method of discriminating a copy product by providing a brilliant metal part in a part of the design of the printed material is also implemented.
Since such a metal portion reflects 100% of incident light, the copying machine reproduces this portion in black. As an example, for example, a gold thread is sewed on the surface layer of paper, and copy check is performed.
[0004]
In addition, the metal diffractive surface of the light diffraction structure replicated with a transparent resin is subjected to metal vapor deposition, thermally transferred to a part of the printing area, and copying by a copying machine is restrained. This light diffractive structure is used as a means for preventing counterfeiting of a printed matter that has been thermally transferred, while attempting to check fraud due to copying by the reflection effect of the metal surface. Optical diffraction structures are often used as a means for preventing counterfeiting of vouchers because they require advanced manufacturing techniques.
However, improvement in manufacturing technology has made it possible to manufacture an optical diffraction structure that is close to the real thing at first glance.
In order to check such counterfeit products, a technique has been disclosed in which a hidden pattern that is difficult to discriminate is incorporated in the light diffraction structure and the authenticity is discriminated by the discriminating pattern formed on the discriminator. There is a problem that the pattern itself is slightly perceived depending on the viewing angle.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of such a problem, and provides a discrimination method for a hidden pattern that has a large effect of preventing forgery and is extremely difficult to discriminate visually by a visual means.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the method for discriminating a hidden pattern by the light diffraction structure of the present invention is a method for discriminating a hidden pattern by a discriminating pattern formed on the surface of a transparent film. a is, the hidden pattern, the entire area formed by the diffraction grating is divided into partial areas of the multiple, in said partial region, can not determine the at least one region normal observation state 2 The pattern is an optical diffraction structure characterized in that each of the two patterns is composed of fine stripes arranged in parallel with each other, and the discrimination pattern is any of the two patterns. It is a striped pattern formed in parallel with the stripes constituting one pattern.
[0007]
The invention according to claim 2 is the invention according to claim 1, wherein the discrimination pattern is any one of a line, a halftone dot, and a diffraction grating having the same pitch and the same line width as the hidden pattern stripe. It is formed by any method of photoengraving, etching, printing and transfer.
[0010]
Further, the invention according to claim 3, in the invention described in claim 2, parallel line, discrimination pattern by halftone dots, the width of the colored portion is narrower Ri by the width of the transmission portion, the colored portion other than black It is formed by the material of this.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The hidden pattern discrimination method using the light diffraction structure of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining a method of discriminating a hidden pattern due to a light diffraction structure using a discriminator, and FIG. 2 is a diagram for explaining an example of a printed material on which a light diffraction structure having a hidden pattern is transferred. 3 is an enlarged view of the hidden pattern region of FIG. 2, FIG. 4 is an explanatory diagram of various discrimination patterns, FIG. 5 is an explanatory diagram of an example of a layer configuration by a section of a discriminator for hidden pattern discrimination, 6 is a diagram in which a discrimination pattern is placed over the hidden pattern shown in FIG. 2, and the hidden pattern is discriminated. FIG. 7 is a diagram for explaining a modification of FIG. 6, and FIG. FIG. 9 is a diagram showing the hidden pattern shown in FIG. 8, FIG. 10 is a diagram for explaining an aggregate of two bands forming a pair, and FIG. 11 is a fringe density. Illustration for explaining Figure 12 is a diagram for explaining an example of a diffraction grating formed in a band.
[0013]
In many of the anti-counterfeit media using the light diffractive structure, a light diffractive structure including a hidden pattern for checking forgery or copying is formed at a predetermined position of the printed matter. The forming method is such that a very thin resin with unevenness is melted to a predetermined size by heat and formed on a printed matter such as paper with a heat-reactive adhesive.
In rare cases, a light diffraction structure is formed on a base film and punched out to a predetermined size, and is formed on a printed material together with the base film using an adhesive or an adhesive.
[0014]
Examples of printed matter that may not be counterfeited or copied include banknotes, gift certificates, admission tickets, gift certificates, bills, checks, and the like.
These printed materials include a technique that cannot be duplicated unless the printing itself has a special technique, and is double protected against forgery and abuse by copying.
[0015]
In FIG. 1, the light diffractive structure 2 is formed on the surface of the printed matter 3 via an adhesive 23.
The light diffractive structure 2 is formed on the base film and adhered to the printed material as it is, and only the light diffractive structure formed in a thin film of resin is transferred to the printed material by a thermal transfer method or the like. May have been.
When discriminating a hidden pattern incorporated in the optical diffraction structure in an invisible manner, the hidden pattern discriminating tool (hereinafter referred to as discriminating tool) 1 is brought close to the printed matter 3 at a predetermined angle, whereby the hidden pattern is formed. It is displayed on the discriminator 1 in a moire state. When the hidden pattern displayed on the determination tool 1 is a predetermined pattern, the printed material is determined to be a legitimate product (genuine product) supplied from a correct supplier.
The discriminating tool forms the discriminating pattern on the transparent base substrate because the light irradiated to the hidden pattern (2) of the printed material must pass through the discriminating tool 1 and reach the “eyes” of the observer. Has been. Moreover, since the discriminating tool is frequently used, a discriminating tool in which the base substrate is fixed with a strong frame material is often used. This frame material has a handle or the like to prevent the transparent base substrate of the discriminator 1 from being soiled with fingerprints or oil.
[0016]
At the time of discrimination of the hidden pattern, the hidden pattern discriminating tool 1 is discriminated to a degree close to the printed matter 3 on which the light diffraction structure 2 is formed.
Although the hidden pattern can be discriminated from the close contact state up to a certain distance, it is possible to discriminate that the distance between the light diffraction structure 2 and the discriminator 1 is too large due to the use of the moire phenomenon. It becomes difficult.
Further, since the light that generates the discrimination pattern by the hidden pattern (2) and the discrimination tool 1 becomes light incident on the discrimination tool 1 from the “eye” direction shown in FIG. It is preferable that the transparency is high, and the pattern is formed so as not to disturb the incident light by the discrimination pattern formed on the substrate.
[0017]
In FIG. 2, the light diffraction structure 2 is formed on the lower right side of the printed material 3.
The optical diffraction structure 2 includes a hidden pattern region 4 and other partial regions, and the hidden pattern region 4 includes a second pattern 22 and a first pattern 21 in the background.
In the case of banknotes, historical images of famous leaders, cultural merits, national buildings and ruins are designed in a partial area located in the center.
[0018]
In the embodiment of FIG. 2, the alphabet “H” is incorporated as a hidden pattern as the second pattern 22.
The second pattern 22 is incorporated so as to be indistinguishable in a normal visual state, and cannot be confirmed without using a special confirmation pattern. Therefore, the second pattern 22, ie, the hidden pattern, is incorporated into the first pattern in a state that is extremely difficult to duplicate.
When such a hidden pattern is used in a practical state, if the second pattern 22 is incorporated in the simple first pattern 21 and used, it is clear that the entire area is a counterfeit check means. In some cases, some design, such as a hologram, is provided as a partial region in the entire region, the region of the first pattern 21 is provided in a manner to be harmonized, and the second pattern 22 is incorporated.
[0019]
The hidden pattern area 4 will be described with reference to FIG.
In the present embodiment, the light diffraction structure 2 is composed of a first pattern 21 and a second pattern 22, and the second pattern 22 is incorporated as a hidden pattern in the first pattern 21. It is in a state.
The second pattern 22 is incorporated so as not to be discriminated in a normal visual state, and cannot be discriminated unless it is based on a special discrimination pattern. Therefore, the second pattern 22, that is, the hidden pattern, is incorporated in the first pattern 21 in a state that is extremely difficult to duplicate.
[0020]
The first pattern 21 and the second pattern 22 are configured by a plurality of fine stripes formed of a light diffraction structure.
In FIG. 3, when the lower end of the printed material 3 is placed in a horizontal state, the first pattern 21 is the first pattern 21 with respect to a line 13 (hereinafter referred to as a horizontal line) parallel to a line connecting the left and right eyes of the observer. The pattern 11 is incorporated so that the angle 11 formed by the stripes constituting the pattern 21 is 45 degrees, and the second pattern 22 which is a hidden pattern is incorporated so as to be 135 degrees.
The angle 11 formed by the stripes forming the first pattern with respect to the horizontal line 13 is 45 degrees, and the angle 12 formed by the second pattern is 135 degrees. However, the angle between the first pattern and the second pattern is By swapping, the angle 11 formed by the stripes forming the first pattern may be 135 degrees, and the angle 12 formed by the second pattern may be 45 degrees.
Further, the concealment effect does not change even if the angles of 45 degrees and 135 degrees are changed by about plus or minus 5 degrees.
[0021]
In the above description, it can be seen that the first pattern 21 and the second pattern 22 are incorporated so that the stripes constituting each pattern are 90 degrees, but including an allowable angle that does not change the hidden effect. It can be seen that it should be incorporated within the range of 90 degrees plus or minus 10 degrees.
[0022]
Although not shown, the second pattern may be bordered by a fringe having a period shifted by a half period with respect to the period of the fringe constituting the pattern. The bordering has an effect of facilitating the discrimination when discriminating the second pattern.
[0023]
An embodiment of various discrimination patterns will be described with reference to FIG.
A discrimination pattern of a, b, c, and d shown in FIG. 4 formed on the surface of the transparent substrate is brought close to the surface of the hidden pattern to generate a discrimination image based on the hidden pattern.
FIG. 4A is a discriminating pattern based on a line having a stripe angle 15 of 45 degrees with respect to a horizontal line. The lines are connected in pairs with transparent bands and colored bands. The width of the transparent band and the width of the colored band may be the same or different.
As described above, since the light for discriminating the hidden pattern is light that has passed through the discriminator, the light that is formed on the discriminator is narrower than the width of the transparent belt and more light is emitted. Try to get in. In addition, when the discrimination pattern is formed by printing or etching, a bright material, a transparent dye, or a transparent material can be used for the colored portion.
[0024]
FIG. 4B is a discrimination pattern by a line having a stripe angle 16 of 135 degrees with respect to the horizontal line. The contents of the discrimination pattern are in accordance with FIG.
[0025]
FIG. 4c shows a discrimination pattern by a diffraction grating having a fringe angle 17 of 45 degrees with respect to the horizontal line. The pattern formation by the diffraction grating will be described in detail with reference to FIG. 10, FIG. 11, and FIG.
[0026]
FIG. 4d shows a discrimination pattern by halftone dots having a stripe angle 18 of 135 degrees with respect to the horizontal line.
The halftone dot is composed of a point where the transparent part and the colored part are independent, or a point where the two parts are connected in a chain, and the (dotted) line connecting the transparent part is colored. A pair of (chain-like) lines connecting the parts is formed. This pair of bands is formed at an angle of 135 degrees. The configuration of the halftone dots and the transparent portion is the same as in FIG.
[0027]
FIG. 5 is a cross-sectional view of the discriminating tool in which the discriminating pattern shown in FIG.
In the discriminating tool, a transparent adhesive layer 102 and a light diffraction structure layer 101 are formed on the surface of a transparent substrate 103 made of synthetic resin or the like. A transparent reflective layer may be provided on the adhesive side of the light diffraction structure layer 101. A protective layer is provided on the outermost surface of the light diffraction structure layer 101 to protect the light diffraction structure from abrasion.
The transparent substrate 103 is made of a plastic such as polyethylene terephthalate (hereinafter referred to as polyester) having a thickness of 100 to 250 μm and acrylic, and is previously acrylic based on a vinyl acetate-based or acrylic-based thermoplastic adhesive (102). The light diffraction structure coated with the resin protective layer 100 is transferred by heat.
As another production method, the light diffractive structure can be formed of a resin such as acrylic on the surface of polyester treated with an adhesive by the matrix of the light diffractive structure. Also in this case, a protective layer is provided on the outermost surface.
[0028]
A method of discriminating the hidden pattern by the light diffraction structure with the discriminating tool will be described with reference to FIGS. 6, 7, 8, and 9. FIG. The discrimination pattern used here is the pattern shown in FIG.
FIG. 6 shows the horizontal line 13 of the optical diffraction structure composed of the first pattern 21 and the second pattern (hidden pattern) 22 shown in FIG. 3 shows an image (discrimination pattern) displayed on the discriminator when the discriminator is brought into close contact with the surface of the light diffraction structure.
The hidden pattern “H” that could not be identified in the state of FIG. 2 clearly appears.
[0029]
When the discriminator described with reference to FIG. 6 is moved along the horizontal line of the printed material on which the optical structure is formed, a deformation pattern due to moire as shown in FIG. 7 appears. The process returns to the discrimination pattern as shown in FIG.
[0030]
In FIG. 6 and FIG. 7, the hidden pattern (22) of the alphabet “H” is determined, but in FIG. 8 and FIG. 9, the hidden pattern (32) of kanji and “genuine” is determined.
As shown in FIG. 8, a second pattern 32 is incorporated as a hidden pattern in the first pattern 31. In the state of FIG. 8, the first pattern 32 cannot be discriminated, but the second pattern 32 can be discriminated only by using the discrimination pattern by the discriminator.
[0031]
Next, an example in which the discrimination pattern formed on the discrimination tool is a fringe due to a diffraction grating will be described with reference to FIG.
The stripe (a pair of bands) 230 is formed by connecting two bands of the band 210 where the light diffraction structure is formed and the band 220 where the light diffraction structure having a different diffraction angle or pitch is formed with respect to the band 220. Configured. Although the stripe is displayed as the band 210 ascending to the left, it indicates that the diffraction grating constituting the light diffraction structure is formed at an angle that is increasing to the left with respect to the length direction of the band.
In the band 220, the stripe is displayed as rising to the right, but the diffraction grating constituting the optical diffraction structure is formed as rising to the right with respect to the length direction of the band.
[0032]
In this way, two bands formed at different diffraction angles or pitches on the diffraction grating form a pair to form a stripe, thereby forming a first pattern and a second pattern.
Further, in order to enhance the concealing effect, the density of the bands constituting the stripes described above may be such that the density of a pair of bands, that is, the stripes 230 is 5 or more in 1 mm, as shown in FIG. Inventors' experiments have shown that it is preferable.
The upper limit is not particularly limited by the inventor because there is a relation such as the width and length of pits constituting the diffraction grating.
[0033]
With reference to FIG. 12, the fringes formed by the diffraction grating will be described.
When the portion A of the band 210 constituting the stripe is enlarged, it is as shown on the right side of FIG. 12, and a plurality of structural units 2100 of the diffraction grating are formed inside the band 210.
One of these structural units 2100 is regularly arranged with the same diffraction angle and the same pitch with respect to the band.
For example, the band 210 and the band 220 are arranged at an angle α (14) with respect to the length direction of the band even though the pitch of the constituent units of the formed diffraction grating is the same. In contrast, the band 220 is arranged at an angle β (not shown) with respect to the length direction of the band.
[0034]
As described above, when changing the characteristics of a pair of bands, there are a band 210, a method of changing the formation angle (diffraction angle) of the structural unit 2100 with respect to the band 220, and a method of changing the pitch.
For example, even if the diffraction grating formed in the band 220 has an angle similar to the diffraction angle of the band 210 shown in FIG. 12, the number of pits formed for a certain length is changed and is different from the band 210. In addition, the concealing effect of the second pattern can be enhanced by connecting the band 210 and the band 220 together.
As an example of setting the pitch or the diffraction angle of the diffraction grating, the pitch of the structural unit 2100 is a and the diffraction angle is α for the band 210, for example. On the other hand, for the band 220, the pitch of the structural unit 2100 is b, and the diffraction angle is α.
Contrary to the above, with respect to the band 210, the pitch of the structural unit 2100 is a, and the diffraction angle is α. On the other hand, for the band 220, the pitch of the structural unit 2100 is a, and the diffraction angle is β.
As described above, when the fringe is formed by changing the diffraction angle and pitch of the diffraction grating, either one of the elements is made the same, and the other element is changed.
The same effect can be obtained by a combination of changing two elements.
[0035]
In this way, a stripe is created by the band on which the diffraction grating is formed, the first pattern and the second pattern are created by the aggregate of stripes, and the stripes of the first pattern and the second pattern intersect at right angles. By incorporating both of them and making a difference in the colors reflected from each stripe, the hidden pattern made up of the light diffraction structure is made a hidden pattern that is difficult to discriminate with ordinary visual means, and a special discrimination pattern is used. Only a clear discrimination is possible.
[0036]
(Example)
An embodiment in which a discrimination pattern with a diffraction structure is formed on the surface of a transparent polyester will be described.
A thin metal-deposited glass plate is irradiated with an electron beam having a diameter of 6 μm to form a diffraction grating structural unit having a size of 12 × 24 μm at an angle of 45 degrees with respect to one cut surface of the glass.
The formation density of the structural units by the diffraction grating was 2 rows / band, and was formed at a pitch of 12 μm in the longitudinal direction of the band. The band on the connecting side was formed by changing the diffraction angle, and two bands were alternately formed. As a result, the stripe density was set to 7 stripes / mm.
In this way, a discrimination pattern on a line having a stripe of 45 degrees was produced to produce an original plate.
On the other hand, on the surface of a transparent acrylic resin previously applied on a transparent polyester base film having a thickness of 150 μm, the unevenness is reproduced by duplication of the discrimination pattern by the light diffraction structure prepared from the above-mentioned original plate. An optical diffraction structure was produced. A protective layer was applied to the transparent resin on the base film on which the light diffractive structure was replicated by coating, and cut into a predetermined size.
A frame was attached so that the cut discriminating pattern forming film was in a flat state.
As a result of visually recognizing the second pattern corresponding to the concealed pattern by placing the above discriminator on the surface of the optical diffraction structure in which the concealed pattern thermally transferred onto the surface of the fine paper is incorporated, it is discriminated by ordinary visual means. Hidden patterns that could not be identified.
[0037]
【The invention's effect】
The following effects can be achieved by the method for discriminating a hidden pattern of a light diffraction structure according to the present invention.
1) As in the first aspect of the present invention, the hidden pattern formed by fine stripes which is difficult to distinguish is hidden by forming a striped pattern parallel to the hidden pattern stripe on the transparent substrate and confirming it. The pattern can be easily distinguished.
2) As in the invention described in claim 2, any one of lines, halftone dots, and diffraction gratings having the same pitch and the same line width as the discrimination pattern is any one of photolithography, etching, printing, and transfer. By being formed by this method, an inexpensive and highly accurate discriminating tool can be provided.
3) As in the invention described in claim 3 , by forming the colored portion with a transparent material, a material other than black is used for the colored portion, and the width of the colored portion is narrower than the width of the transmissive portion. It becomes possible to discriminate the hidden pattern in a bright state.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a method of discriminating a hidden pattern due to a light diffraction structure using a discriminator; FIG. 2 is a diagram for explaining an example of a printed material on which a light diffraction structure having a hidden pattern is transferred; FIG. 3 is an enlarged view of the hidden pattern area of FIG. 2. FIG. 4 is an explanatory view of various discrimination patterns. FIG. 5 is an explanatory view of an example of a layer structure by a section of a discriminator for hidden pattern discrimination. FIG. 7 is a diagram for explaining a modification of FIG. 6 while holding a discrimination pattern over the hidden pattern shown in FIG. 2. FIG. 8 is a diagram for explaining a case where the hidden pattern is a Chinese character. FIG. 9 is a diagram showing the hidden pattern shown in FIG. 8. FIG. 10 is a diagram for explaining an aggregate of two bands forming a pair. FIG. 11 is a diagram for explaining a stripe density. ] Formation on the belt It is a diagram for explaining an example of a diffraction grating.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hidden pattern discriminating tool 2 Optical diffraction structure 3 Printed matter 4 Hidden pattern area | region 11 The mounting angle 12 of a 1st pattern The mounting angle 13 of a 2nd pattern A line (horizontal line) parallel to the line which connects the right and left eyes of a visual recognition means
14 The angle (45 degrees) that the discriminating pattern of 150,000 lines indicating the diffraction grating formation angle (α) forms with the horizontal line
The angle (135 degrees) between the 160,000 line discrimination pattern and the horizontal line
17 Angle formed by the diffraction grating fringe discrimination pattern and the horizontal line (45 degrees)
18 Angle formed by halftone dot discrimination pattern with horizontal line (135 degrees)
21, 31 First pattern 22, 32 Second pattern 100 Protective layer 101 Optical diffraction structure, hidden pattern 102 Adhesive layer 103 Transparent base material 210, 220 Band 230 A pair of bands (stripe)
2100 Diffraction grating components a, b, c, d Various discrimination patterns

Claims (3)

A method for discriminating a hidden pattern by a discrimination pattern formed on the surface of a transparent film,
The hidden pattern, the entire area formed by the diffraction grating is divided into partial areas of the multiple, the inside of the partial region, consists of two patterns can not determine the at least one region normal observation state The two patterns are patterns of light diffraction structures characterized in that each of the two patterns is composed of fine stripes arranged in parallel with each other.
The hidden pattern discriminating method using an optical diffraction structure, wherein the discriminating pattern is a striped pattern formed in parallel with a fringe constituting one of the two patterns. The discrimination pattern is formed by any one of photoengraving, etching, printing, and transfer by using any of lines, halftone dots, and diffraction gratings having the same pitch and the same line width as the hidden pattern stripes. The method for discriminating a hidden pattern by the light diffraction structure according to claim 1. Said parallel line, the discrimination pattern by halftone dots, the width of the colored portion is narrower Ri by the width of the transmission portion, the light of claim 2, the colored portion, characterized in that it is formed of a material other than black Hidden pattern discrimination method by diffraction structure.

Images