JPH07156584A - Forgery preventive printed matter - Google Patents

Abstract

PURPOSE:To make development of a latent image clear, by a method wherein ink which contains at least two primary colors out of three primary colors of cyanogen, magenta and yellow and genuine color density value of at least one kind out of those is adjusted within a fixed range is used. CONSTITUTION:Ink which is allowed to contain at least two primary colors selected out of three primary colors of cyanogen, magenta and yellow is used. Then at the time of colored copying, the every primary color of printed matter is scanned, in density between two points selected arbitrarily, ink and screen ruling of a latent image part 2 and nonlatent image part 3 is adjusted so that a density gradation where hues of the latent image part 2 and nonlatent image part 3 are different from each other is generated. Then at least a genuine color density value of at least one kind of the primary color is set up at a range of 0.04-0.26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed matter which prevents forgery due to copying. More specifically,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printed matter for preventing important documents such as banknotes, checks, stock certificates, title certificates, and ID cards from being forged by color copying.

[0002]

2. Description of the Related Art In recent years, as the accuracy of color copying machines has increased, they have been often misused for counterfeiting important documents such as banknotes, checks, stock certificates, title certificates, and identification cards. In order to prevent such forgery, attempts have been made to use special ink, imprint magnetic marks, print hidden characters with fluorescent substances, etc., but lack of sustainability, the need for special equipment, high costs, etc. There was a drawback in terms.

After that, as a remedy for such drawbacks, a latent image composed of a fine component is printed on the surface of a substrate, and a fine component coarser or denser than the latent image is used in a white background portion around the latent image. Printed matter with a latent image (Japanese Patent Publication No. 55-
No. 45400), a camouflage pattern is provided on the entire surface of the substrate area on which the first tone image and the second tone image are printed, and one of the first tone image and the second tone image can be reproduced by a color copying machine. When observing with the naked eye, forming the other with a non-reproducible density
A document in which both tone images cannot be identified, but a warning mark appears when a color copy is made (Japanese Patent Publication No. 58-4).
No. 7708), a dark-colored pattern pattern on the surface of the base paper is 150 to 175 lines, and a background pattern other than this pattern can be clearly discriminated from the pattern pattern with 150 to 175 lines and 10 to 150 lines. For example, copy false image prevention paper (Japanese Patent Laid-Open No. 2-81698), which is printed with halftone dots of about 10% and is imprinted with a wording indicating that the pattern pattern is applied to a part of the base paper, is available. was suggested.

However, when these false-image-preventing printed materials are copied at copy densities suitable for their respective latent images, the latent images and characters are clearly embossed, but when the copy densities deviate within a predetermined range, the latent images are formed. There is a drawback that it becomes unclear and difficult to identify. For example, if the density adjustment of a color copying machine is set to a light condition, both the latent image part and the non-latent image part are copied lightly at the same level and cannot be easily distinguished by the naked eye. In particular, the amount, title, date of issue, etc. If it overlaps with the display part of, the identification becomes difficult. This is due to the limit value of the reproduction lens of the color copying machine, and is a phenomenon that occurs when the density exceeds the fixed density range.

[0005]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the conventional printed matter for preventing false images due to color copying and provides a clear latent image in a wide range of dark to light density color copying. The purpose of the invention is to provide a novel printed matter in which an image is revealed.

[0006]

The inventors of the present invention have conducted various studies on false-image-preventing printed matter, and as a result, cyan, in the printing ink of the latent image portion and the non-latent image portion printed with different line numbers, At least two primary colors selected from the three primary colors of magenta and yellow are contained, and at the time of color copying, the printed matter is scanned for each primary color of cyan, magenta, and yellow to transfer each color toner onto the substrate. In the density between the two selected points, the ink containing the primary color and the screen line between the latent image portion and the non-latent image portion are formed so that the hues of the latent image portion and the non-latent image portion have different density gradients. It was found that the purpose could be achieved by adjusting the number.

More specifically, the primary colors of cyan, magenta, and yellow are screened with 65 screen rulings and 85 rulings.
The density adjustment range of the color copying machine, that is, the printed matter whose screen density is adjusted to 30% so that the true density value is 0.17 for each of the lines, 110 lines and 150 lines.
The lightest density adjustment is set to scale 1, the darkest adjustment is set to scale 9, and copying in the range of scales 1 to 9 results in a copy between two points of 1 to 5, due to the difference in screen frequency. It was confirmed that a color density difference (density gradient) of the copy was generated.

For example, the adjustment scale 1 has 65 lines and 85 lines.
Lines, 110 lines and 150 lines have copy density values of 0.0
9, 0.04, 0.01, 0.00, and scale 3
Then, the values were 0.14, 0.11, 0.09, and 0.08, respectively. That is, with the copy of 65 lines and 150 lines,
A color density difference of 0.01 (scale 5) to 0.09 (scale 1) occurs. And 85 lines, 110 lines, 65 lines and 150 lines
The color density difference occurs within the range of the color density difference with the line. That is, in the printed matter of 65 lines to 150 lines, 0.01 to 0.0 between any two points in the copy adjustment range of 1 to 5.
A concentration gradient of 9 is produced.

Similarly, in a printed matter in which the screen density is adjusted to 20% so that the true density value becomes 0.12.
Between 2 points (up to 65 lines to 150 lines) 0.01
A density gradient in the range of (scale 9) to 0.07 (scale 5) was confirmed, and at 150 lines, 0.01 to 0.1.
A tilt of 4 was confirmed. Further, in the printed matter in which the screen density is adjusted to 10% so that the true density value is 0.05, the print density is 0.01 in the range of 2 to 9 (for 65 to 150 lines).
A density gradient of (Scale 2) to 0.08 (Scale 9) was confirmed.

Further, in a printed matter in which the screen density is adjusted to 40% so that the true density value becomes 0.23, 1
Between 2 points of ~ 5 (for 65 to 150 lines) 0.01
A density gradient of (Scale 1) to 0.08 (Scale 5) was confirmed.

As mentioned above, in the present invention,
The primary color density of at least one of the primary colors
Must be in the range of 0.04 to 0.26
However, the true color density value of each primary color is blue, green and
Yellow and maze obtained through the red and red filters
Black and cyan ink reflection density Dy (yellow
-), Dm (magenta) and Dc (cyan)
It was calculated as follows. Dy = Yy + a₁・ Mm + a₂Cc (1) Dm = b₁・ Yy + Mm + b₂・ Cc (2) Dc = c₁・ Yy + C₂・ Mm + Cc (3) where Yy, Mm, and Cc are yellow and magenta, respectively.
This is the true color density value for a single color of cyan and cyan ink. formula
A in (1) to (3)₁, A₂, B₁, B₂, C ₁as well as
c₂The type and composition of the primary color dye (or pigment) depends on the latent image part and
And a non-latent image part state.

Further, the ink reflection densities Dy of the above respective colors,
Dm and Dc are the reflection densities of the paper itself calculated from D obtained for each color by the equation D = log ₁₀ 1 / R (4) from the ratio (reflectance R) of the amount of reflected light and the amount of incident light measured by a reflection densitometer. Required by subtracting.

For example, in the primary color ink used in one example, a ₁ = 0.7, a ₂ = 0.2, b ₁ = 0.1, b ₂ = 0.4 c ₁ = 0, c ₂ An approximate value of = 0.2 was obtained. By substituting this into the equations (1) to (3) and using the measured values Dy, Dm and Dc of the ink reflection density of each color, the true color density values Yy, Mm and C of each primary color are obtained.
c can be calculated according to the following equation: Yy = 1.08 Dy−0.77 Dm + 0.09 Dc (5) Mm = I. 17 Dm-0.12 Dy-0.44 Dc (6) Cc = 1.09 Dc + 0.02 Dy-0.23 Dm (7)

Further, in the present invention, it is preferable to adjust the synthetic true color density value Ds of the primary colors in the ink to 0.5 or less, which can be calculated according to the following formula. Ds = Yy + Mm + Cc (8)

That is, according to the present invention, when the latent image portion and the non-latent image portion are printed on the surface of the substrate by the same color ink with different screen rulings, respectively, and are visually recognized uniformly, but color copying is performed. In a printed matter in which a latent image is made visible, at least two primary colors selected from the three primary colors of cyan, magenta and yellow are contained as the ink, and at least one true color density value among them is The present invention provides an anti-counterfeit printed matter, characterized in that an ink adjusted to a range of 0.04 to 0.26 is used.

In the present invention, the three primary colorants contained in the printing ink used to form the latent image portion and the non-latent image portion are cyan-based coloring agents and magenta-based coloring agents used in ordinary printing inks. Agents and yellow colorants can be arbitrarily selected. This printing ink may contain two or three kinds of cyan, magenta and yellow, and when the two kinds are contained, the combination may be any of cyan and magenta, cyan and yellow and magenta and yellow. Good.

In this case, it is necessary to adjust the true color density value of any one of the primary colors used so that it falls within the range of 0.04 to 0.26. Also, the combined true color density of the primary colors is preferably 0.5 or less.
If the true color density of each of the above primary colors is less than 0.04, the density is too light during color copying to prevent the latent image from appearing, and if it is greater than 0.26, the combined true color density value is When it is larger than 0.5, it becomes difficult to visually identify the latent image when color copying is performed even if one color changes. To set the combined true color density value to 0.5 or less, the true color density value of one or two primary colors is set to 0.04.
To 0.13 and the true color density value of the other one or two kinds to 0.08 to 0.26, the color copy has a density gradient in at least one of the primary colors. Color change or density difference occurs.

Next, the structure of the anti-counterfeit printed matter of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of a printed matter of the present invention, in which a latent image 2 composed of the letters “copy” on the surface of a sheet 1 and a ground pattern on a portion other than this latent image, that is, a non-latent image portion. 3 is printed. 2, FIG. 3, and FIG. 4 show the latent image 2 and the non-latent image portion in a pattern instead of the characters in FIG. The latent image portion has a screen ruling of 50 to 85 lines per inch (2.54 cm), preferably 60 to 75 lines, more preferably about 65 to 70 lines, and screen density (lines or dots occupied per unit area). (Percentage of area) 10 to 80%, preferably 20 to 60%. Since the density of the screen changes due to the medium in the ink, the density of the printed matter is adjusted by the amount of the medium.

On the other hand, the non-latent image portion 3 has a screen ruling of 1
20 to 180 lines, preferably 140 to 180 lines, and more preferably 150 to 180 lines.

In this example, the number of screen lines in the latent image portion 2 is small and the number of screen lines in the non-latent image portion 3 is large. On the contrary, the number of screen lines in the latent image portion 2 is large and the non-latent image is large. It is also possible to reduce the screen ruling of the portion 3.

Further, in order to make it difficult to visually distinguish the latent image portion 2 and the non-latent image portion in a normal state, a camouflage pattern may be printed over the entire surface.

[0022]

In the present invention, the latent image portion and the non-latent image portion are printed with the ink containing at least two colors selected from the three primary colors of cyan, magenta and yellow, and the ink of different density is printed on the printed portion. Since there are two or more types, even when the density is adjusted to one of the shades by adjusting the density of the color copying machine, density gradients having different hues are generated, and the latent image appears on the copy in a visually recognizable state.

[0023]

The present invention will be described in more detail with reference to Examples.

Example 1 Ink (A) in which 79% by weight of magenta and 21% by weight of cyan were mixed, Ink (B) in which 82% by weight of magenta and 18% by weight of cyan were mixed, and 84% by weight of magenta and 1 of cyan.
6% by weight of the mixed ink (C) was prepared and printed with different screen rulings and screen densities, and a copying test was conducted with a color copying machine (Canon, Color Laser Copier 500). The results are as follows.

(1) When the density adjusting dial is set to the lightest; all of the inks A, B, and C show almost the same result, 6
Only magenta was confirmed in 30% of 5 lines, 40% of 65 lines and 40% of 85 lines. (2) Normal density adjustment dial; Inks A and B show almost the same results, 150 lines 30%, 150 lines 4
Cyan was not confirmed at 0%, magenta was confirmed, and cyan was slightly confirmed at 65% at 30% and 65% at 40%. For ink C, 150 lines 30%, 150
At the line 40%, almost no cyan was confirmed, and magenta was clearly confirmed. 65% line 30%, 65% line 40%,
The dye is not found for cyan. (3) When the darkness of the density adjustment dial is set; Ink A
And B show almost the same results. Cyan was hardly confirmed at 150% line 30% and magenta was clearly confirmed, but the presence of cyan was clearly confirmed at 65 line 30%. Further, magenta was clearly confirmed at 150% line 40%, and cyan was slightly recognized, but the presence of cyan was clearly confirmed at 65 line 40%. The same tendency was recognized for ink C, but it was difficult to recognize the color difference due to cyan at 65 lines as compared with inks A and B.

Ink A, ink B and ink C
The reflection density value (Dy ', Dm', Dc '), the ink reflection density value (Dy, Dm, Dc), the true color density value (Yy, Mm, Cc) and the composite true color density value (Ds). The results are shown in Table 1, Table 2 and Table 3.

The reflection density value is a portable reflection densitometer "Smart 100" [manufactured by Couser Japan KK].
The ink reflection density value is obtained by the formula: ink reflection density (Dy ', Dm', Dc ') = reflection density (Dy, Dm, Dc) -blank paper density, and is the true color density. The value and the composite true color density value are obtained by the above equations (5), (6), (7) and (8).

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

Example 2 Ink (D) containing 79% by weight of cyan and 21% by weight of yellow, ink (E) containing 82% by weight of cyan and 18% by weight of yellow, and 84% by weight of cyan with yellow 1
6% by weight of the mixed ink (F) was prepared and printed with different screen rulings and screen densities, and a copying test was conducted with a color copying machine (Canon, Color Laser Copier 500). The results are as follows.

(1) When the density adjusting dial is set to the lightest; all of the inks D, E, and F show almost the same result, and 6
Only cyan was confirmed in 5% line 30%, 65% line 40% and 85% line 40%. (2) Normal density adjustment dial; Inks D and E show almost the same results, 150 lines 30%, 150 lines 4
At 0%, yellow was not confirmed but at cyan was confirmed, and at 30% of 65 lines and 40% of 65 lines, yellow was slightly confirmed. For ink F, 150 lines 30%, 15
At 0% line 40%, yellow was hardly confirmed, and cyan was clearly confirmed. At 30% of 65 lines and 40% of 65 lines, the dye is not recognized for yellow. (3) When the darkness of the density adjustment dial is set; Ink D
And E showed almost the same results, and yellow was hardly confirmed at 150% line 30% and cyan was clearly confirmed, but the presence of yellow was clearly confirmed at 65 line 30%. Further, magenta was clearly confirmed at 150% line 40%, and yellow was slightly recognized, but the presence of yellow was clearly confirmed at 65 line 40%. The same tendency was recognized for ink F, but it was difficult to recognize the color difference due to yellow at 65 lines as compared with inks D and E.

Ink D, ink E and ink F
Table 4, Table 5 and Table 6 show the reflection density value, ink reflection density value, true color density value and composite true color density value obtained in the same manner as in Example 1.

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

Example 3 Ink (G) in which 79% by weight of cyan and 21% by weight of yellow were mixed, ink (H) in which 82% by weight of magenta and 18% by weight of yellow were mixed, and 84% by weight of cyan and 16% by weight of yellow were mixed. A mixed ink (I) was prepared and printed with different screen rulings and screen densities, and a copying test was carried out by a color copying machine (manufactured by Canon, Color Laser Copier 500). The results are as follows.

(1) When the density adjusting dial is set to the lightest; all of the inks G, H, and I show almost the same result, and 6
Only magenta was confirmed in 30% of 5 lines, 40% of 65 lines and 40% of 85 lines. (2) Normal density adjustment dial; inks G and H show almost the same results, 150 lines 30%, 150 lines 4
At 0%, yellow was not confirmed and magenta was confirmed, and at 30% of 65 lines and 40% of 65 lines, yellow was slightly confirmed. For ink I, 150 lines 30%, 1
In 50% line 40%, yellow was hardly confirmed, and magenta was clearly confirmed. 65 lines 30%, 65 lines 40%
Then, the dye is not recognized for yellow. (3) When the density adjustment dial is darkest; ink G
And H show almost the same results, and yellow was hardly confirmed at 150% line 30% and magenta was clearly confirmed, but the presence of yellow was clearly confirmed at 65 line 30%. Further, magenta was clearly confirmed at 150% line 40%, and yellow was slightly recognized, but the presence of yellow was clearly confirmed at 65 line 40%. The same tendency was observed for Ink I, but it was difficult to recognize the color difference due to yellow at 65 lines as compared with Inks G and H.

Ink G, Ink H and Ink I
Table 7, Table 8 and Table 9 show the reflection density value, ink reflection density value, true color density value, and combined true color density value, which were obtained in the same manner as in Example 1.

[0040]

[Table 7]

[0041]

[Table 8]

[0042]

[Table 9]

Each of the above-mentioned embodiments is an example of a mixed ink of two primary colors, but the same can be applied to a mixture of three primary colors or a combination of two primary colors or a mixture of three primary colors with a sumi ink. did it.

[0044]

According to the present invention, with a very simple process,
A clear latent image is detected in a wide range of color copying from dark density to light density, and a printed matter effective for preventing forgery of important documents can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an example having a latent image portion formed of characters and a non-latent image portion formed of a ground pattern.

FIG. 2 is a perspective view of an example having a latent image portion composed of a diagonal pattern and a non-latent image portion composed of a ground pattern.

FIG. 3 is a perspective view of an example having a latent image portion having a ring-shaped pattern and a non-latent image portion having a ground pattern.

FIG. 4 is a perspective view of an example in which the oblique upper left half is a latent image portion and the oblique lower right half is a non-latent image portion.

[Explanation of symbols]

 1 sheet 2 latent image part 3 non-latent image part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // D21H 21/40

Claims (3)

[Claims] 1. A latent image portion and a non-latent image portion are printed on the surface of a substrate with the same color ink at different screen rulings, respectively, and are visually recognized uniformly, but in the case of color copying, the latent image is formed. In the printed matter that was able to reveal
The ink contains at least two primary colors selected from the three primary colors of cyan, magenta, and yellow, and at least one of them has a true color density value of 0.04 to 0.26.
The anti-counterfeit printed matter is characterized in that the ink adjusted to the range is used. 2. The latent image portion is 50 to 85 lines per 1 inch (2.54 cm) of the screen ruling, and the screen density is 1.
The anti-counterfeit printed matter according to claim 1, wherein the non-latent image portion has a screen density of 120 to 180 lines per inch (2.54 cm) and a screen density of 10 to 80%. 3. The anti-counterfeit printed matter according to claim 1, wherein the composite true color density value of the primary colors in the ink is 0.5 or less.