JP4319807B2 - Hidden pattern by light diffraction structure and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hidden pattern having a light diffraction structure that is difficult to distinguish in a normal visual state and a method for manufacturing the same.
[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 into a light diffraction structure and used as a means of authenticity discrimination. There was a problem of being discriminated.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and provides a hidden pattern that has a large effect of preventing forgery and is extremely difficult to discriminate by visual means, and a method for producing the same.
[0006]
[Means for Solving the Problems]
Wherein in order to achieve the object of the object, the invention according to claim 1 of the hidden pattern by optical diffraction structure of the present invention, the entire area formed by the diffraction grating is divided into partial areas of the multiple, the partial region Is a hidden pattern by a light diffraction structure composed of two patterns in which at least one region is incorporated in an indistinguishable state in a normal visual state ,
Each of the two patterns is composed of fine stripes arranged in parallel with each other,
The fine stripe is an aggregate of two bands forming a pair, and the diffraction grating formed in one of the two bands is different from the diffraction grating formed in the other band, the pitch, and the diffraction angle. Is characterized in that at least one of them is different.
[0008]
The invention according to claim 2 is characterized in that, in the invention according to claim 1 , the density of the stripes is 5 stripes / mm or more.
[0009]
The invention according to claim 3 is the invention according to any one of claims 1 and 2 , wherein the two patterns are composed of a first pattern and a second pattern, and the first pattern includes the first pattern. In the state in which the two patterns are incorporated, the stripes constituting each pattern form an angle of 90 degrees.
[0010]
According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, when the entire region of the diffraction grating is placed in a correct observation state, the stripes of the first pattern are observed by the observer. The stripes of the second pattern are arranged at an angle of 135 degrees with respect to a line connecting the left and right eyes.
[0011]
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the second pattern is bordered by a fringe having a period shifted by a half period from the period of the fringe constituting the pattern. It is characterized by that.
[0012]
A method for producing a hidden pattern using an optical diffraction structure according to claim 6 is a method for producing a hidden pattern using an optical diffraction structure according to claim 3 , wherein the first pattern and the second pattern are formed using a masking pattern. And is incorporated as a part in the entire pattern of the designed diffraction grating .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The hidden pattern by the light diffraction structure of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining an example of a printed material on which a light diffraction structure having a hidden pattern according to the present invention is transferred, FIG. 2 is an enlarged view of a partial region in which the hidden pattern is incorporated, and FIG. FIG. 4 is a diagram for explaining the density of stripes, FIG. 5 is a diagram for explaining an example of a diffraction grating formed on the belt, and FIG. These are enlarged views of the entire region of the optical diffraction structure in which the hidden pattern is incorporated, and are diagrams for explaining an example in which the incorporation angle of the hidden pattern is different.
[0014]
A light diffraction structure (3) including a hidden pattern for checking forgery or copying is formed at a predetermined position of the printed matter 4. 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.
[0015]
The printed matter on which the light diffractive structure is formed is often not forged or copied, and examples thereof include banknotes, gift certificates, admission tickets, gift certificates, bills, checks, and the like. In addition, the printing itself incorporates a technique that cannot be duplicated unless it has a special technique, and it is double protected against forgery and abuse by copying.
[0016]
In FIG. 1, an entire region 4 having a light diffraction structure is formed at the lower right of the printed matter 5.
The entire region 4 by the light diffraction structure is composed of a partial region 3 and other partial regions, and the partial region 3 which is a hidden pattern region is composed of the second pattern 2 and the first pattern 1 of the background. ing.
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.
[0017]
In the embodiment of FIG. 1, the alphabet “H” is incorporated as a hidden pattern as the second pattern 2.
The second pattern 2 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 2, that is, the hidden pattern, is incorporated in the first pattern in a state where it is extremely difficult to duplicate.
When such a hidden pattern is used in a practical state, if the second pattern 2 is incorporated in the simple first pattern 1 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, and the region of the first pattern 1 is provided in a harmonized form, and the second pattern 2 is incorporated.
[0018]
With reference to FIG. 2, the hidden pattern which consists of a 1st pattern and a 2nd pattern is demonstrated.
The 1st pattern 1 and the 2nd pattern 2 which form the partial area | region 3 which expresses a concealment effect are comprised by the several fine stripe formed with the optical diffraction structure.
In FIG. 1, the partial region 3 that exhibits a concealment effect when the lower end of the printed matter 5 is placed in a horizontal state is visually recognized in the state shown in FIG. 2. In other words, the angle 11 formed by the stripes forming the first pattern is 45 degrees with respect to a line (hereinafter referred to as a horizontal line) 13 parallel to the line connecting the left and right eyes of the visual recognition means, and is also hidden. The angle 12 formed by the second pattern as a 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.
[0019]
In the above description, it can be seen that the first pattern 1 and the second pattern 2 are incorporated so that the stripes constituting each of them 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.
For reference, FIG. 6 illustrates the case where the angles of incorporation of the first pattern 10 and the second pattern 20 are 90 degrees and 180 degrees with respect to the horizontal line, respectively. Then, the concealment effect of the second pattern 20 is low.
Although not shown, the second pattern is surrounded by a fringe having a period that is shifted by a half period from the period of the fringe constituting the pattern. The pattern can be visually recognized more clearly.
[0020]
Next, the stripe configuration will be described with reference to FIG.
The stripe (a pair of bands) 300 is composed of two bands (band 100 and band 200) in which an optical diffraction structure is formed. The band 200 is formed of a diffraction grating that differs from the band 100 in at least one of a diffraction angle and a pitch. For example, in FIG. 3, the band 100 is formed with the diffraction angle of the diffraction grating falling to the right, and the band 200 is formed with the diffraction angle of the diffraction grating rising to the right.
In this way, two bands of diffraction gratings formed at different diffraction angles or pitches form a pair to form a stripe, forming a light diffraction structure, and the first pattern and the second pattern Forming.
[0021]
In order to enhance the concealing effect, it is preferable that the density of the bands constituting the stripes is preferably 5 or more in 1 mm, as shown in FIG. It became clear by the experiment of the person.
The purpose of reducing the number of stripes is to make it difficult to visually recognize the hidden pattern, to increase the definition of the first pattern, and to facilitate confirmation using the confirmation pattern.
Regarding the upper limit, the inventor is not particularly limited because there is a relation such as the width and length of the constituent units constituting the diffraction grating.
[0022]
With reference to FIG. 5, the fringes formed by the diffraction grating will be described.
When the A portion of the band 100 constituting the stripe is enlarged, it is as shown on the right side of FIG. 5, and a plurality of structural units 1000 of the diffraction grating are formed inside the band 100.
One of these structural units is regularly arranged with the same diffraction angle and the same pitch with respect to the band.
For example, the band 100 and the band 200 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 200 is arranged at an angle β with respect to the length direction of the band (not shown).
[0023]
As described above, there are a method of changing the formation angle (diffraction angle) of the structural unit 1000 with respect to the band 100 and the band 200, and a method of changing the pitch.
For example, even if the structural unit formed in the band 200 is an angle similar to the diffraction angle shown in FIG. 5, the number of structural units formed for a certain length is changed to be different from the band 100, The concealment effect of the second pattern can also be enhanced by connecting the band 100 and the band 200 together.
As an example of setting the pitch or diffraction angle of the diffraction grating, the pitch of the structural unit 1000 is a and the diffraction angle is α for the band 100, for example. On the other hand, for the band 200, the pitch of the structural unit 1000 is b, and the diffraction angle is α.
Contrary to the above, with respect to the band 100, the pitch of the structural unit 1000 is a, and the diffraction angle is α. On the other hand, for the band 200, the pitch of the structural unit 1000 is a, and the diffraction angle is β.
In this way, when the fringe is formed by changing the diffraction angle and pitch of the diffraction grating (structural unit), any one of the elements is made the same and the other element is changed.
A considerable effect can also be obtained by a combination of changing two elements.
[0024]
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 the two 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 discern by ordinary visual means, and is clarified only by using a special confirmation pattern It becomes possible to make it possible to distinguish.
[0025]
As described in FIG. 2, FIG. 6 incorporates the first pattern 10 and the second pattern 20 so that the stripes intersect at right angles, and the stripes constituting the second pattern 20 are included in the entire area. In this case, the angle 120 formed is parallel to the horizontal line 130 and the angle 110 formed by the stripes forming the first pattern 10 is perpendicular to the horizontal line 130.
Although the concealment effect can be obtained even if the concealment pattern (second pattern 20) is incorporated at the angle shown in FIG. 6, at such an embedding angle, the light diffraction is performed by standing at a position where the observer can easily see the light source. The light reflected from the structure amplifies the contrast so that the hidden pattern is slightly more visible when compared to the built-in angle shown in FIG.
[0026]
EXAMPLES thin metal on a glass plate with a deposit of by irradiating an electron beam having a diameter of 4 [mu] m at an angle of 45 degrees with respect to 1 cut surface of the glass, 12μ m × 24μ m in size configuration unit by the diffraction grating Form. The formation density of the constitutional units was 3 rows / band, and was formed at a pitch of 0.5 constitutional units in the longitudinal direction of the band. The bands on the connecting side were formed by changing the diffraction angle, and two bands were alternately formed. As a result, the stripe density was set to 7 stripes / mm. A first pattern and a second pattern were produced by using a masking pattern, and incorporated as a part in the entire design of the diffraction grating, thereby producing an original. A duplicate was produced from this original plate, and irregularities were reproduced on the surface of a transparent acrylic resin coated on the base film to produce a light diffraction structure. A yellow colorant was applied to the transparent resin on the base film on which the light diffractive structure was replicated, and an aluminum thin film was formed thereon by vacuum deposition, and a heat-sensitive adhesive was applied thereon. The light diffraction structure formed on the base film was thermally transferred to a sample of a high-quality paper gift voucher with a line drawing printed on the surface by a metal plate heated to 160 degrees Celsius. As a result of observing the light diffractive structure at a position where the design of the gift certificate can be correctly viewed and visually recognizing the second pattern which is a hidden picture, it cannot be discriminated by ordinary visual means.
[0027]
【The invention's effect】
With the hidden pattern of the light diffraction structure of the present invention, the following effects can be obtained.
1) As the invention of claim 1, the entire area formed by the diffraction grating is divided into partial areas of the multiple, in said partial region, determined in at least one region normal observation state not It is a hidden pattern by an optical diffraction structure composed of two patterns that can be incorporated , wherein the two patterns are each composed of fine stripes arranged in parallel to each other, and the fine stripes are paired. In the aggregate of two bands formed, the diffraction grating formed in one of the two bands is different from the diffraction grating formed in the other band in at least one of pitch and diffraction angle. Thus, it becomes easy to synthesize with the counterfeit check means similarly formed by the diffraction grating, and it becomes possible to make it difficult to determine the presence of the hidden pattern. In addition, it is possible to improve security by designing areas other than the partial areas constituting the hidden pattern with a diffraction grating so as to form a collective pattern. In addition, it is possible to make a difference between the colors of the two stripes and make it difficult to check the hidden pattern in a normal viewing state.
2) As in the invention described in claim 2, if the number of stripes in which two bands are connected is set to 5 / mm or more, the thickness of the band by the diffraction grating constituting the stripes becomes 100 μm or less, Even if the color of the stripes is different according to the invention of claim 1, the band per stripe and the thickness of the stripes are fine, so that it looks like a uniform diffraction image in a normal viewing state. The presence of the hidden pattern can be made more difficult to confirm.
3) As in the invention described in claim 3, when the angle formed by the stripes of the first pattern and the stripes of the second pattern is 90 degrees, the first pattern generated by the confirmation pattern and the second pattern The difference in moiré from the pattern can be easily confirmed, and the convenience in determining authenticity is remarkably improved.
4) As in the fourth aspect of the invention, the angle formed by the first pattern and the stripes of the second pattern in the state where the second pattern is incorporated in the first pattern region is 45 degrees and 135 degrees. This enhances the concealment effect of the second pattern and facilitates confirmation using the confirmation pattern.
5) As in the invention described in claim 5, the second pattern is bordered by a fringe having a period shifted by a half period with respect to the period of the fringe constituting the pattern. improves.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an example of a printed material to which a light diffraction structure having a hidden pattern according to the present invention is transferred. FIG. 2 is an enlarged view of a partial region in which the hidden pattern is incorporated. FIG. 4 is a diagram for explaining the density of the bands constituting the stripes. FIG. 5 is a diagram for explaining an example of the diffraction grating formed on the bands. ] An enlarged view of the entire region of the optical diffraction structure in which the hidden pattern is incorporated, and a diagram for explaining an example in which the angle of incorporation of the hidden pattern is different.
DESCRIPTION OF SYMBOLS 1, 10 1st pattern 2, 20 2nd pattern 3 Partial area | region 4 of optical diffraction structure 4 Whole area | region 5 of optical diffraction structure Printed material 11, 110 First pattern installation angle 12, 120 Second pattern installation angle 13, 130 Line parallel to the line connecting the left and right eyes of the visual recognition means 14 Line 100, 200 indicating diffraction grating formation angle (α) Band 300 One pair of bands (stripe)
1000 diffraction grating (unit)

Claims (6)

The entire area formed by the diffraction grating is divided into a plurality of partial areas, and at least one of the partial areas is composed of two patterns that are incorporated so as to be indistinguishable in a normal visual state. A hidden pattern with a diffractive structure,
Each of the two patterns is composed of fine stripes arranged in parallel with each other,
The fine stripe is an aggregate of two bands forming a pair, and the diffraction grating formed in one of the two bands is different from the diffraction grating formed in the other band, the pitch, and the diffraction angle. The hidden pattern by the light diffraction structure, wherein at least one of the two is different. The hidden pattern according to claim 1, wherein the fringe density is 5 stripes / mm or more. The two patterns are composed of a first pattern and a second pattern, and in a state where the second pattern is incorporated in the first pattern, stripes constituting each pattern form an angle of 90 degrees. The hidden pattern by the light diffraction structure according to any one of claims 1 and 2. When the entire area of the diffraction grating is placed in a correct observation state, the stripes of the first pattern are at an angle of 45 degrees with respect to the line connecting the left and right eyes of the observer, and the stripes of the second pattern are The hidden pattern by the light diffraction structure according to claim 1, wherein the hidden pattern is disposed at an angle of 135 degrees. 5. The hidden pattern by the light diffraction structure according to claim 1, wherein the second pattern is bordered by a fringe having a period shifted by a half period with respect to a period of the fringe constituting the pattern. . A method for producing a hidden pattern by the light diffraction structure according to claim 3 ,
Create a first pattern and a second pattern with a masking pattern,
A method for producing a hidden pattern using an optical diffraction structure, wherein the hidden diffraction pattern is incorporated as a part of the entire designed diffraction grating pattern .

Images