JP2006308723A - Concealed pattern by optical diffraction structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concealed pattern by an optical diffraction structure, in which the sequence of fine characters by gratings is further processed finely and the characters are made hard to discriminate. <P>SOLUTION: A plurality of pattern groups composed of optical diffraction structures are provided, wherein each pattern group contains a fine pattern, containing at least one of numbers, characters, marks and figures and each fine pattern has at most 100 μm height. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hidden pattern by a light diffraction structure having a fine pattern.

In recent years, forgery cases of high-value banknotes and gift certificates using color copiers have frequently occurred.
For this purpose, banknotes, gift certificates, admission tickets, gift certificates, bills, checks, cards, etc. are part of the design with small dots and fine lines that cannot be read by the color copier sensor incorporated in the design. As for what is done, the part is made to come out white.
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. As a result, the metal part reflects 100% of the incident light of the copier, so the copy reproduces the metal part in black.
In addition, a technique is disclosed in which a translucent metal deposition process is performed on the uneven surface of a light diffractive structure replicated with a transparent resin, thermally transferred to a part of the printed material, and copying by a copying machine is controlled.

Optical diffraction structures are often used as a means for preventing counterfeiting of vouchers because they require advanced manufacturing techniques.
However, with the advancement of peripheral technology, metal deposits that are close to the real ones have appeared, and it has become difficult for general users to distinguish real and fake at first glance.
In order to check such a counterfeit product, a technique is disclosed in which a hidden pattern that is difficult to discriminate is incorporated into a light diffraction structure and used as a means for discriminating authenticity (see, for example, Patent Document 1).
The technique disclosed in Patent Document 1 is a genuine product by forming a 300-micron-height character string that is difficult to read visually in an optical diffraction structure and enlarging and confirming that portion with a magnifying glass or the like. It is determined that there is.

Japanese Utility Model Publication No. 9-66

However, in the technique disclosed in Patent Document 1, a hidden pattern such as a micro character is incorporated in a part of a ruled line and the like, and the micro character is as large as 250 to 300 μm. There was a problem of being discriminated.
Accordingly, an object of the present invention is to provide a hidden pattern with an optical diffraction structure in which a fine character string by a diffraction grating is further refined and the discrimination thereof is difficult.

  In order to achieve the object of the present invention, the invention according to claim 1 of the hidden pattern by the light diffraction structure of the present invention is characterized in that in each of the plurality of pattern groups composed of the light diffraction structure, each pattern group is at least: It includes a fine pattern including any one of numbers, letters, symbols, and designs, and each of the fine patterns has a height of 100 μm or less.

  The invention according to claim 2 is the invention according to claim 1, wherein either the pitch or the diffraction angle is different between the fine pattern and its peripheral part, or a diffraction grating is not formed on either one of them. It is characterized by this.

  The invention according to claim 3 is the invention according to any one of claims 1 and 2, characterized in that a character group constituting a word is included in the fine pattern.

  According to a fourth aspect of the present invention, in the invention according to any one of the first and second aspects, the fine pattern includes a mathematical expression.

  The invention according to claim 5 is the invention according to any one of claims 1 and 2, characterized in that a pattern group including a mark is included in the fine pattern.

  The invention according to claim 6 is the invention according to claims 3 to 5, wherein the character group, the mathematical formula, and the symbol group are divided into a plurality of parts and are dispersed and incorporated in a plurality of patterns. It is what.

1) As described in claim 1, in the plurality of pattern groups constituted by the light diffraction structures, each pattern group includes at least a fine pattern including any one of numbers, letters, symbols and designs. Since the fine pattern has a height of 100 μm or less, it is difficult to specify the location by visual observation, and therefore, it is difficult to duplicate the pattern, which is effective as a countermeasure against forgery.
2) In addition, as described in claim 2, in the invention described in claim 1, the fine pattern and its peripheral part are different in at least one of pitch and diffraction angle, or any one of them has a diffraction grating. Since it is not formed, it is impossible to distinguish a fine pattern with the naked eye. However, when it is magnified with a magnifying glass or the like and viewed with appropriate light, it can be recognized as a pattern due to the difference in diffraction state.
3) As described in any one of claims 3 to 5 and 6, in the invention described in any one of claims 1 and 2, the fine pattern includes a character group, an equation, and a symbol group, and the character group, the equation, and the symbol group. Is divided into a plurality of patterns and dispersed and incorporated into a plurality of patterns, so that it is difficult to distinguish each divided character group, mathematical expression and symbol group, and the fine pattern has a height of 100 μm or less. The person who tries to counterfeit it is necessary to identify all the elements and counterfeit all of them, so it requires advanced technology and a lot of labor, and exerts a very large check effect against counterfeiting .

Hereinafter, with reference to drawings, the hidden pattern by the light diffraction structure of this invention is demonstrated.
FIG. 1 is a diagram for explaining a hidden pattern by the light diffraction structure of the present invention, FIG. 2 is a diagram for explaining the basic concept of the hidden pattern, and FIG. 3 is a diagram for explaining the hidden pattern of the present invention. FIG. 4 is a diagram for explaining an example of a combination of diffraction gratings in each part of the hidden pattern, FIG. 5 is a diagram for explaining an example of the fine pattern, and FIG. 6 is another example of the fine pattern. It is a figure for demonstrating.

With reference to FIG. 1, the hidden pattern by the light diffraction structure of this invention is demonstrated.
The combined pattern 1 is formed in a state where a pattern A11 composed of four wavy lines by the light diffractive structure and a circular pattern B12 by the light diffractive structure overlap at the center of the pattern A11.
The wavy lines constituting the pattern A11 are thickest at the bottom and narrower toward the top.
Only the thinnest wavy line 111 of the pattern A11 is formed across the front surface of the pattern B12, and this portion is a hidden pattern of the combination pattern 1.
The diffraction grating constituting the thinnest wavy line 111 of the pattern A11 is selected in angle or pitch so that it can be seen integrally with the pattern B12.
The combination pattern 1 is formed on the base film as an extremely thin resin film, and is thermally transferred to a printed material or the like with an adhesive, or is punched into a predetermined size while being formed on the base film, and is printed as a label. Affixed to the product.

The basic concept of the hidden pattern will be described with reference to FIG.
A circular first pattern 2, which is also a hidden pattern by the light diffraction structure, is incorporated in the rectangular second pattern 3 by the light diffraction structure.
As shown in FIG. 2, the second pattern 3 is composed of, for example, a diffraction grating 31 with a dot diffraction angle of 135 degrees, and the first pattern 2 is a diffraction grating with a dot diffraction angle of 45 degrees, for example. 21.
Conversely, the diffraction angles of the diffraction gratings of the first pattern 2 and the second pattern 3 are the same, the dot pitch of the first pattern 2 is 1 μm, and the dot pitch of the second pattern 3 is 2 μm. It is possible to set different settings such as, or to set the same.

With reference to FIG. 3 and FIG. 4, the hidden pattern by the pattern A and the pattern B is demonstrated.
FIGS. 3B and 3C are diagrams in which a part 120 of the pattern B on which a hidden pattern is formed is cut out and enlarged from the pattern B12 shown in FIG. 3A.
The thinnest wavy line 111 of the pattern A is formed at the center of the part 120 of the pattern B. A fine pattern 1112 having a maximum height of 100 μm is formed inside the thinnest wavy line 111 of the pattern A, and the peripheral part 1111 of the fine pattern has a light diffraction structure inside the wavy line.

An example of the hidden pattern by the light diffraction structure will be described with reference to FIG.
The thinnest wavy line 111 of the pattern A is formed in the diffraction grating 1201 formed as a part 120 of the pattern B, and the fine pattern 1112 is incorporated in the thinnest wavy line 111 of the pattern A.
The fine pattern 1112 is an equation in the example of FIG. B, and the height of each number is adjusted to 100 μm or less. The inside of the thinnest wavy line 111 of the pattern A and the fine pattern 1112 have a light diffraction structure, and the inside of the part 120 of the pattern B appears to be a uniform solid state as a whole. The example shown in FIG. b is an example in which patterns having different diffraction angles described in FIG. 2 are combined.
The diffraction grating of the fine pattern 1112 is formed with a diffraction angle of 0 degree, and the diffraction grating of the peripheral part 1111 of the fine pattern is formed with a diffraction angle of 90 degrees.
Furthermore, the diffraction grating formed as a part 120 of the pattern B is formed with a diffraction angle of 0 degree.
Thus, the inside of the part 120 of the cut pattern B is in a state where diffraction gratings having the same pitch are formed at different diffraction angles, and further, formed inside the thinnest wavy line 111. Since the formed fine pattern is 100 μm or less, the boundary between the fine pattern and the peripheral portion cannot be discriminated with the naked eye, and the same color is seen.

Another example of the hidden pattern by the light diffraction structure will be described with reference to FIG.
The thinnest wavy line 111 of the pattern A is formed in the diffraction grating 1202 formed as a part 120 of the pattern B, and the fine pattern 1112 is incorporated in the thinnest wavy line 111 of the pattern A. The fine pattern 1112 is represented by a mathematical formula, as in the example of FIG. B, and the height of each number is adjusted to 100 μm or less.
The example shown in FIG. c is an example in which diffraction gratings having different pitches are combined.
The fine pattern 1112 and the peripheral part 1111 of the fine pattern have the same diffraction angle and are formed at 0 degree.
The diffraction grating formed as a part 120 of the pattern B is formed with a diffraction angle of 135 degrees, and the pitch is also different from the fine pattern and the peripheral part of the fine pattern.
Thus, the inside of the part 120 of the cut pattern B is in a state where diffraction gratings having the same angle are formed at different pitches.
Therefore, in the example of FIG. C, it can be determined that the thinnest wavy line of the pattern A crosses the inside of the pattern B. However, since the fine pattern formed inside the thinnest wavy line 111 is 100 μm or less, The boundary of the peripheral part cannot be discriminated with the naked eye, and it cannot be discriminated that a fine pattern is formed inside the wavy line.
In the example shown in FIG. c, the combination pattern may be configured such that all four wavy lines constituting the pattern A are placed in front of the pattern B.

  In FIGS. b and c, even if the peripheral portion of the fine pattern is in a blank state in which no diffraction grating is formed, it is determined that the fine pattern is formed in the thinnest wavy line portion because the fine pattern is 100 μm or less. It ’s difficult.

An example of a fine pattern will be described with reference to FIG.
The example of the fine pattern described above is a mathematical expression, but other than that, it may be a hiragana character string indicating an address as shown in FIG. D, or a capital letter as shown in FIG.
In the examples as shown in Fig. d and e, in the expression quoted "Kanji" used in printed matter such as the above-mentioned banknotes, gift certificates, admission tickets, gift certificates etc. that use diffraction grating. It is more effective if it is.
In addition, it may be a mathematical expression combining alphabets, numbers, and symbols as shown in Fig. F, or a pictograph with a design as shown in Fig. G.

With reference to FIG. 6, another example of the fine pattern will be described.
The example shown in FIG. 6 is an example in which a “meaningful character string” used in a fine pattern is disassembled and used. For example, the word “security” meaning “safety” shown in FIG. H is broken down into two, “sec” and “urity”, and a group of “abcd” + [sec] as shown in FIG. As shown in the figure, it is possible to make discrimination more difficult by arranging them in a group of “efg” + [urity]. Since this character string is very fine, 100 μm or less, its existence itself cannot be understood except by the manufacturer and the related parties.
If there are multiple such “significant character strings”, it is extremely difficult to identify and discriminate all of the embedded character strings except for manufacturers including some related parties. The deterrent effect against is tremendous.
Even if the product is counterfeited, the counterfeit product can be easily identified.

(Example)
A thin metal-deposited glass plate was irradiated with an electron beam having a diameter of 1 μm to form a diffractive structure with 4 μm × 8 μm dots at a pitch of 1 μm.
Pattern A, pattern B, and a fine pattern mask with a character height of 90 μm are prepared, and at a predetermined position, the fine pattern and pattern B are at a diffraction angle of 0 degrees, inside the thinnest wavy line of pattern A. A pattern was formed at the diffraction angle of 90 degrees around the fine pattern.
A fine pattern which is a hidden pattern could not be visually confirmed.

  Used by attaching to certificates, warranty cards, etc. of expensive products such as clothing, accessories and bags.

It is a figure for demonstrating the hidden pattern by the light diffraction structure of this invention. It is a figure for demonstrating the basic idea of a hidden pattern. It is a figure for demonstrating the hidden pattern of this invention. It is a figure for demonstrating an example of the combination of the diffraction grating of each part of a hidden pattern. It is a figure for demonstrating an example of a fine pattern. It is a figure for demonstrating other examples of a fine pattern.

Explanation of symbols

1 Combination Pattern 2 First Pattern 3 Second Pattern 11 Pattern A
12 Pattern B
21, 31 Diffraction grating 111 Thinnest wavy line of pattern A 120 Part of pattern B 1111 Peripheral part of fine pattern 1112 Fine pattern 1201, 1202 Diffraction grating formed as part 120 of pattern B

Claims (6)

In a plurality of pattern groups composed of light diffraction structures,
Each pattern group includes a fine pattern including at least one of numbers, letters, symbols, and designs, and each of the fine patterns has a height of 100 μm or less. Hidden pattern. In the hidden pattern by the light diffraction structure according to claim 1,
A hidden pattern by a light diffraction structure, wherein the fine pattern and its peripheral part are different in at least one of pitch and diffraction angle or a diffraction grating is not formed on either one. The hidden pattern by the light diffraction structure according to claim 1, wherein a character group constituting a word is included in the fine pattern. The hidden pattern by the light diffraction structure according to claim 1, wherein a mathematical expression is included in the fine pattern. The hidden pattern by the light diffraction structure according to claim 1, wherein a pattern group including a mark is included in the fine pattern. In the hidden pattern by the light diffraction structure according to claim 3,
A hidden pattern by a light diffraction structure, wherein a character group, a mathematical expression, and a symbol group are divided into a plurality of parts and dispersed and incorporated into a plurality of patterns.

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