Anti-falsification printed matter

Abstract

To provide a copy-forgery-inhibited printed matter capable of outputting a printed matter with high reproducibility without being affected by the resolution of a printer by constituting an image area only of an area with a low number of lines.SOLUTION: The copy forgery preventing printed matter 1 is provided with a first area 21 including a first image line 11 and a second area 41 including a second image line 31. The first region 21 and the second region 41 are visually equal in color, the first objects 11 and the second objects 31 are different in object circumferential length, and when the copy-forgery-inhibited pattern printed matter is copied, a difference occurs between the dot gain of the first objects 11 and the dot gain of the second objects 31, and a difference in print density occurs between the first regions 21 and the second regions 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to copy- and tamper-proof printed matter, including banknotes, passports, securities, cards, and valuable printed matter, for which anti-counterfeiting and anti-tampering functions are required. [Background technology]

[0002] In recent years, with the advancement of high image quality and functionality in color copiers, the circulation of counterfeit products of valuable printed materials such as banknotes and securities has become a serious problem. For this reason, there has long been a demand for valuable printed materials to be protected from tampering, such as copying by copiers.

[0003] As a technique for preventing copying, for example, the following copy-protected printed matter has been proposed using the technique described in Patent Document 1, which was previously filed by the present applicant.

[0004] This copy-protected printed matter has two areas: the first area is made up of halftone dots with a screen ruling of 175 lines (the number of pixels per inch), and the second area is made up of halftone dots with a screen ruling of 80 lines.These two areas have the same screen density and hue, so they cannot be distinguished under visible light.When copied, the first area with the higher screen ruling is not copied, while the second area with the lower screen ruling is copied, making the latent image pattern visible and preventing copying.

[0005] As a technique for preventing copying, for example, the technique described in Patent Document 2, previously filed by the present applicant, proposes the following copy-deterrent printed matter.

[0006] This copy prevention printed matter has two image areas, the first image area having non-copyable elements of 150 μm or less, and the second image area having copyable elements larger than 150 μm, the first and second image areas having equal area ratios and the same color, and when copied, the non-copyable elements are not copied and only the copyable elements are copied, making the latent image pattern visible and preventing copying. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-143117 [Patent Document 2] Patent No. 5910964 Summary of the Invention [Problem to be solved by the invention]

[0008] The technologies disclosed in Patent Documents 1 and 2 share the common feature of utilizing the characteristic of copiers that low-line-number images are highly reproducible and high-line-number images are poorly reproducible, forming images with different line numbers in two areas and visualizing the latent image pattern due to the difference in reproducibility during copying. For example, an area with a low line number of 30 to 50 lines and an area with a high line number of 100 to 300 lines were formed.

[0009] These conventional techniques assume that printed materials intended for copy prevention will be produced using high-performance offset printing machines, and take advantage of the advantage that offset printing machines have over copiers: their significantly higher image reproducibility. The faint, fine, high-line-count images printed by offset printing machines cannot be reproduced by a copier when copied, and disappear. This phenomenon is known as dot loss, and conventional techniques that utilize this dot loss effect of copiers to visualize latent images composed of low-line-count images have long been used as a core technology for copy prevention.

[0010] However, with the recent spread of on-demand printing services, there are now many opportunities for users to directly print various certificates, resident cards, etc. In these cases, printed materials are not printed using offset printing machines, but rather using general office printers or multifunction machines installed in convenience stores or printing centers.

[0011] When these conventional technologies are output as is using a general office printer or multifunction device, the image lines in low-line-count areas are reproduced, but the image lines in high-line-count areas are not, resulting in the problem that the latent image pattern becomes visible at the time of output. This problem is caused by the printer's low image reproducibility, and is an unavoidable problem when outputting conventional technologies using a printer.

[0012] In view of the above circumstances, the present invention aims to provide a copy-and-tamper-proof printed matter that can be output with high reproducibility without being affected by the printer's resolution by configuring the image area only with low line count areas. [Means for solving the problem]

[0013] The copy-and-tamper-proof printed matter of the present invention comprises a first region including a first image line and a second region including a second image line, the first region and the second region having the same visual color, and the first and second images having different image perimeters, and when the copy-and-tamper-proof printed matter is copied, a difference occurs between the dot gain of the first image line and the dot gain of the second image line, resulting in a difference in print density between the first region and the second region.

[0014] The first and second objects may differ in at least one of line width, size, pitch, and shape.

[0015] One of the first object and the second object may be a closed figure and the other an open figure.

[0016] The first object and the second object may both be closed figures, and one of the closed figures may have the interior filled in, while the other may have the interior not filled in.

[0017] Either the first object line or the second object line may be formed as a broken line, and the other may be formed as a solid line.

[0018] The image recording medium may further include a visible image formed by a third image formed in a portion where the first image and the second image are not present.

[0019] The first and second regions may have gradations, and the first and second regions may have the same color at the same gradation. The gradation in the first region and the gradation in the second region may have a negative-positive relationship.

[0020] The ratio a / b of the ruling a of the first image line to the ruling b of the second image line may be within a predetermined range. [Effects of the Invention]

[0021] The copy and tamper-proof printed matter of the present invention does not utilize the phenomenon in which faint, fine halftone dots and lines are not reproduced when copied, i.e., the so-called dot loss when copying, which was utilized in conventional technology, but rather utilizes the dot gain that occurs when copying patterns of specific shapes and arrangements, and by configuring the image area to consist only of areas with low screen frequencies, it is possible to output copy and tamper-proof printed matter with high reproducibility without being affected by the resolution of the printer, even when output using a general office printer or multifunction device. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is an explanatory diagram showing the configuration of a copy-and-tamper-resistant print according to an embodiment of the present invention; [Figure 2] FIG. 4 is an explanatory diagram showing an image obtained by copying a copy-and-tamper-resistant print according to the embodiment. [Figure 3] 10A and 10B are explanatory diagrams showing examples of combinations of image lines with different image line perimeters and the relationship between the image line perimeters in a copy / tamper-proof print according to the embodiment; [Figure 4] 3A and 3B are explanatory diagrams showing the structure of image lines of a copy-and-tamper-resistant print according to the embodiment, and an enlarged view of a portion thereof; [Figure 5] 10A and 10B are explanatory diagrams showing the configuration of a copy / tamper-proof printed matter according to the embodiment when a visible image is provided, and an enlarged view of a portion thereof; [Figure 6]10A and 10B are explanatory diagrams showing an image when a copy-and-tamper-proof print according to the embodiment is visually viewed, and an explanatory diagram showing an image of a copy made by copying the original. [Figure 7] 10 is an explanatory diagram showing the configuration of the first and second objects in a copy and tamper-proof printed matter according to the embodiment, and the dot gain of the first and second objects in a copy. FIG. [Figure 8] 4 is an explanatory diagram showing the dimensions of the first and second objects and the pitch between the objects in the copy and tamper-proof printed matter according to the embodiment; FIG. [Figure 9] 10 is an explanatory diagram showing a combination of objects that are the same in shape but are filled in or not filled in, as an example of the configuration of the first object and the second object in the copy and tamper-proof print according to the embodiment; FIG. [Figure 10] 10 is an explanatory diagram showing a combination of objects that are the same in shape but are filled in or not filled in, as an example of the configuration of the first object and the second object in the copy and tamper-proof print according to the embodiment; FIG. [Figure 11] 10 is an explanatory diagram showing a combination of objects with different shapes and with or without fill, as an example of the configuration of the first object and the second object in the copy and tamper-proof printed matter according to the embodiment; FIG. [Figure 12] An explanatory diagram showing an example of the configuration of the first and second objects in a copy-and-tamper-proof printed matter according to the embodiment, including a combination of objects that have the same shape but are filled in or not, and a combination of objects that have the same shape but are closed or open. [Figure 13] 3A and 3B are explanatory diagrams showing the structure of a copy / tamper-proof print according to the embodiment and an image obtained by copying. [Figure 14] FIG. 4 is an explanatory diagram showing a first object line and a second object line in a copy / tamper-proof printed matter according to the embodiment. [Figure 15] FIG. 4 is an explanatory diagram showing a combined arrangement of a first object line and a second object line in a copy / tamper-proof printed matter according to the embodiment; [Figure 16] 10A and 10B are explanatory diagrams showing an image when a copy-and-tamper-proof print according to the embodiment is visually inspected, and an explanatory diagram showing an image obtained by copying. [Figure 17]An explanatory diagram showing the lines of a visible image in the copy-and-tamper-proof printed matter shown in Figure 16, and an explanatory diagram showing the configuration of the copy-and-tamper-proof printed matter having a first line, a second line, and a line of a visible image. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment described below, and various other embodiments are possible within the scope of the technical concept described in the claims.

[0024] FIG. 1 shows the configuration of a copy and tamper-proof printed matter 1 according to one embodiment of the present invention. This copy and tamper-proof printed matter 1 includes a first image area 21 in which a latent image is formed by a first object line 11, and a second image area 41 in which a background image is formed by a second object line 31. The first image area 21 and the second image area 41 may be formed in separate areas on the copy and tamper-proof printed matter 1 so as not to overlap, or they may be formed so as to overlap. However, the first object line 11 and the second object line do not overlap. Regarding each embodiment, the case in which the first object line 11 and the second object line are formed in separate areas will be described using FIGS. 1 to 12, and the case in which the first object line 11 and the second object line are formed so as to overlap will be described using FIGS. 13 to 17.

[0025] The number of lines in the first image area 21 and the second image area 41 can be configured at a low number of lines, for example, 30 to 50. If the pitch between images is, for example, 0.72 mm, the number of lines is 35 (= 25.4 mm / 0.72 mm). By configuring both the first image area 21 and the second image area 41 at a low number of lines in this way, they can be sufficiently reproduced even by a low-resolution printer, such as a general home printer.

[0026] The ratio a / b of the number of lines a of the first object 11 to the number of lines b of the second object 31 is within a predetermined range, for example, within the range of 0.5 to 2, and preferably a / b=1.

[0027] Furthermore, the colors of the first object 11 and the second object 31 do not need to be the same, but when a / b=1, the colors of the first object 11 and the second object 31 are the same. This makes the first image area 21 and the second image area 41 indistinguishable from each other visually.

[0028] The sizes of the first object 11 and the second object 31 are to be predetermined, i.e., sizes that can be reproduced by a copier. Specifically, each side is within the range of 0.2 mm to 0.8 mm, and they are arranged at an appropriate pitch so as not to overlap each other. The size is preferably 0.3 mm to 0.5 mm. If the first object 11 and the second object 31 are configured with a side of less than 0.3 mm, particularly 0.1 mm or less, they are unlikely to be accurately reproduced when the output device is a printer. Furthermore, dot gain will not occur during copying, and instead the image may be lost due to dot loss, so this must be avoided.

[0029] With regard to image area coverage, even if the first and second images are different in the data output by a printer, if the visual colors are the same when the original is printed, the first image area 21 and the second image area 41 will not be distinguishable, and the effect of concealing the latent image will be achieved. Furthermore, visual color includes concepts such as reflection density and hue, and as a result, if the colors are the same when visually observed, the first image area 21 and the second image area 41 will not be distinguishable. Furthermore, the first image area 11 and the second image area 31 have different image perimeters. The image perimeter referred to here will be described later using Figure 3.

[0030] If the first object 11 and the second object 31 are configured with an appropriate pitch and size, significant dot gain occurs during copying. In the present invention, the latent image is visualized by utilizing the difference in dot gain between the first object 11 and the second object 31 when they are copied, and it is therefore necessary to control the dot gain. The amount of dot gain is closely correlated with the perimeter of the first object 11 and the second object 31.

[0031] Figure 2 shows a copy 2 obtained by copying this copy and tamper-proof print 1 as an original. As mentioned above, the first object 11 contained in the first image area 21 and the second object 31 contained in the second image area 41 have different object perimeters. Therefore, when the image is copied, a difference occurs between the dot gain generated around the first object 11 and the dot gain generated around the second object 31. As a result, as shown in Figure 2, a density difference occurs between the first image area 21 and the second image area 41, and they are perceived as different images, making the latent image apparent and providing a copy and tamper-proof effect.

[0032] The gradation in the first region 21 and the gradation in the second region 41 in the copy 2 have a negative-positive relationship. If the first image region 21 in which the latent image is formed has a higher density than the second image region 41 in which the background image is formed, the latent image will be a positive image, and if the second image region 41 has a higher density than the first image region 21 as shown in the figure, the latent image will be a negative image.

[0033] 3(a) to 3(d) show examples of combinations of multiple images with different image perimeters in a copy / tamper-proof printed matter according to this embodiment. Taking the example of FIG. 3(a), the image perimeter refers to the combined perimeter of the outer and inner rings of the image 51, which is a double white diamond with no filled-in interior. Similarly, for the image 52, which is a white diamond with no filled-in interior, the combined perimeter refers to the combined perimeter of the outer and inner rings. For the image 53, which is a black diamond, the perimeter refers to the outer perimeter alone.

[0034] When comparing the perimeters of the double white diamond-shaped line 51 with its interior unfilled, the white diamond-shaped line 52 with its interior unfilled, and the black diamond-shaped line 53 with its interior filled in shown in Figure 3(a), the relationship is "double white diamond-shaped line 51 > white diamond-shaped line 52 > black diamond-shaped line 53".

[0035] When each of these images is copied, in the double white diamond image 51, dot gain occurs on the outer and inner peripheries of the two rings, in the white diamond image 52, dot gain occurs on the outer and inner peripheries of one ring, and in the black diamond image 53, dot gain occurs only on the outer periphery.

[0036] As a result, the magnitude of the dot gain has the same relationship as the image perimeter: "double white diamond image 51>white diamond image 52>black diamond image 53".

[0037] Comparing the perimeters of the thin white diamond-shaped image 54 and the thick white diamond-shaped image 55 shown in Figure 3(b), if the shapes of the outer peripheries of the images are the same, the perimeters of the thin white diamond-shaped image 54 and the thick white diamond-shaped image 55 are approximately the same, or the thin white diamond-shaped image 54 is longer than the thick white diamond-shaped image 55, that is, there is a relationship of "thin white diamond-shaped image 54 ≧ thick white diamond-shaped image 55".

[0038] This is because the thin white diamond-shaped image 54 has an inner perimeter that is approximately the same as or longer than that of the thick white diamond-shaped image 55. As the thick white diamond-shaped image 55 becomes thicker, it approaches the black diamond-shaped image 53, and the length of the inner perimeter becomes shorter.

[0039] When such an image is copied, dot gain occurs on the outer and inner peripheries of the ring for both the thin white diamond-shaped image 54 and the thick white diamond-shaped image 55, but due to the difference in the image perimeter, the magnitude of the dot gain has the relationship "thin white diamond-shaped image 54 ≧ thick white diamond-shaped image 55."

[0040] 3(c), if the maximum length of star-shaped object 57 made up of dashed lines and unfilled white diamond-shaped object 52 are compared, the relationship is "star-shaped object 57 made up of dashed lines > unfilled white diamond-shaped object 53" if the maximum length of star-shaped object 57 is approximately the same as the diameter of white diamond-shaped object 53. When an object is made up of dashed lines, each dashed line has its own perimeter, and the perimeters of all the dashed lines are added together to increase the overall object perimeter.

[0041] When such an image is copied, the relationship between the dot gain and the perimeter of the image is the same: star-shaped image 57 made up of dashed lines > unfilled white diamond-shaped image 53. When an image is made up of dashed lines like this, the perimeters of the dashed lines become thicker and the dashed lines become connected and integrated, further increasing the dot gain.

[0042] FIG. 4(a) shows an external view of the structure of the image lines of the copy and tamper-proof print 1 according to this embodiment, and FIG. 4(b) shows an enlarged view of a part of it.

[0043] 4(a), this copy and tamper-proof print 1 comprises a first image area 21 in which a latent image is formed and a second image area 41 in which a background image is formed, the first image area 21 including a first image line 11 and the second image area 41 including a second image line 31. The first image area 21 including the first image line 11 and the second image area 41 including the second image line 31 have the same color.

[0044] As shown in Figure 4(b), the first object 11 is a white diamond-shaped object, and the second object 31 is a black diamond-shaped object. As described above, when the perimeters of the white diamond-shaped object and the black diamond-shaped object are compared, the relationship is "white diamond-shaped object > black diamond-shaped object."

[0045] When such a copy-and-tamper-proof print 1 is copied, the dot gain in accordance with the perimeter of the image line is in the relationship "white diamond-shaped image lines > black diamond-shaped image lines." As a result, the first image area 21 made up of white diamond-shaped image lines is output in a darker color than the second image area 41 made up of black diamond-shaped image lines, making the latent image more visible and preventing copying and tampering.

[0046] Fig. 5(a) shows a copy-and-tamper-proof printed matter 1 in which the significant character "A" has been added as a visible image 81 to the copy-and-tamper-proof printed matter 1 shown in Fig. 4(a). As another image configuration, it has a white diamond-shaped image as the first image 11 and a black diamond-shaped image as the second image 31, similar to the copy-and-tamper-proof printed matter 1 shown in Fig. 4(a).

[0047] Fig. 5(b) shows an enlarged view of a portion of this copy-and-tamper-proof printed matter 1. Like the copy-and-tamper-proof printed matter 1 shown in Fig. 4(b), it has a first object 11 and a second object 31, and also an object 71 of a visible image 81. The object 71 of this visible image 81 is made up of fine halftone dots with a diameter of 0.09 mm or less to cause dot loss.

[0048] When this copy and tamper-proof printed matter 1 is copied, the latent image area becomes visible due to dot gain because the first image line 11 and the second image line 31 have different image perimeters, and the visible image 81 disappears due to dot loss. The presence of the visible image 81 in the copy and tamper-proof printed matter 1 before copying makes it possible to further enhance the concealment of the latent image due to the shade of the visible image 81.

[0049] Fig. 6(a) shows the visible state of the copy / tamper-proof print 1 shown in Fig. 4. As described above, the first image area 21 including the first image line 11 and the second image area 41 including the second image line 31 have the same color. Therefore, as shown in Fig. 6(a), the entire image area is uniformly visible, and the first image area 21, in which the latent image "X" shown by the dashed line is formed, cannot be distinguished from the second image area 41, in which the background image is formed around it, and the latent image "X" is not apparent.

[0050] When the copy and tamper-proof print 1 shown in Fig. 4 is copied, the copy 2 shown in Fig. 6(b) is obtained. Because the first image 11 and the second image 31 have different perimeters, the first image area 21 and the second image area 41 are copied with different densities, and the latent image "x" becomes apparent.

[0051] Similarly, when copying the copy-and-tamper-proof printed matter 1 containing the visible image 81 shown in Figure 5, the first image line 11 and the second image line 31 have different image perimeters, so the first image area 21 and the second image area 41 are copied with different densities, and the latent image becomes apparent.

[0052] FIG. 7(a) shows a white diamond-shaped object 52 and a black diamond-shaped object 53 as two objects used in the copy and tamper-proof print 1 according to this embodiment.

[0053] Figure 7(b) shows the images obtained by copying the white diamond-shaped object 52 and the black diamond-shaped object 53. As described above with reference to Figure 3(a), the white diamond-shaped object 52 has dot gain 52a not only on the outer periphery but also on the inner periphery, resulting in a thicker image. In contrast, the black diamond-shaped object 53 has dot gain 53a only on the outer periphery, resulting in a thicker image. As a result, as described above, the dot gains 52a and 52b of the white diamond-shaped object 52 are greater than the dot gain 53a of the black diamond-shaped object 53.

[0054] 8 shows the dimensions of the object 58 and the pitch between the objects as parameters relating to the configuration of the object 58 in the copy and tamper-proof printed matter 1 according to this embodiment. In this object configuration, the width of the object 58 in the horizontal direction is W1, the height in the vertical direction in the figure is H1, and further, the distance between the objects, that is, the horizontal pitch in the figure, is M1, and the vertical pitch is M2.

[0055] Below are shown other examples of combinations of the first object 11 and the second object 31 in the copy and tamper-proof printed matter 1 according to this embodiment. In all combinations, the first object 11 and the second object 31 have the same color but different object perimeters.

[0056] In the example combination shown in FIG. 9, the first object 11 is a square object 59 with an unfilled interior, and the second object 31 is a square object 60 with a filled interior.

[0057] When comparing the perimeters of the unfilled square image 59 and the filled square image 60, the relationship is "unfilled square image 59 > filled square image 60."

[0058] When this copy-and-tamper-proof print 1 is copied, the dot gain according to the image perimeter has the following relationship: "unfilled square image 59 > filled square image 60."

[0059] Figure 10 shows an example of a combination of lines that have the same shape but are filled in or not, which is different from the shape shown in Figure 9. In the example of the combination shown in Figure 10(a), the first line 11 is a star-shaped line 61 that is not filled in, and the second line 31 is a star-shaped line 62 that is filled in.

[0060] When comparing the perimeters of the star-shaped image 61 whose interior is not filled in and the star-shaped image 62 whose interior is filled in, there is a relationship of "star-shaped image 61 whose interior is not filled in > star-shaped image 62 whose interior is filled in."

[0061] When this copy and tamper-proof print 1 is copied, the dot gain according to the image perimeter has the following relationship: "star-shaped image 61 with the interior unfilled > star-shaped image 62 with the interior filled."

[0062] In the example combination shown in Figure 10(b), the first object 11 is a diamond-shaped object 63 with an unfilled interior, and the second object 31 is a diamond-shaped object 64 with a filled interior.

[0063] When comparing the perimeters of the unfilled diamond-shaped object 63 and the filled diamond-shaped object 64, the relationship is "unfilled diamond-shaped object 63 > filled diamond-shaped object 64."

[0064] When this copy-and-tamper-proof print 1 is copied, the dot gain according to the image perimeter has the following relationship: "unfilled diamond-shaped image 63 > filled diamond-shaped image 64."

[0065] 11 shows another example of a combination of first objects 11 and second objects 31, which are different in shape and whether or not the interior is filled in. The first object 11 is a diamond-shaped object 63 with an unfilled interior, and the second object 31 is a black circle object 53 with a filled interior.

[0066] When comparing the perimeters of the unfilled diamond-shaped image 63 and the filled-in black circle image 53, the relationship is "unfilled diamond-shaped image 63 > filled-in black diamond-shaped image 53." The difference in perimeter between images of different shapes and whether or not they are filled depends on the diameter or area ratio of each image, as well as whether or not they are filled.

[0067] When this copy-and-tamper-proof print 1 is copied, the dot gain according to the perimeter of the image line has the following relationship: "unfilled diamond-shaped image line 63 > filled-in black diamond-shaped image line 53."

[0068] 12(a) shows another example of a combination of first objects 11 and second objects 31. These objects have the same shape but are different in whether their interiors are filled in or not. The first object 11 is an object 65 in the shape of a meaningful letter "S" and has no interior filling, and the second object 31 is an object 66 in the shape of the same letter "S" and has an interior filling.

[0069] When comparing the perimeters of the stroke 65 of the character "S" whose interior is not filled in and the stroke 66 of the character "S" whose interior is filled in, the relationship is "stroke 65 of the character "S" whose interior is not filled in > stroke 66 of the character "S" whose interior is filled in."

[0070] When this copy-and-tamper-proof print 1 is copied, the dot gain according to the image perimeter has the following relationship: image 65 of the letter "S" with the interior unfilled > image 66 of the letter "S" with the interior filled in.

[0071] 12(b) shows another example of a combination of first objects 11 and second objects 31, in which the shapes are the same but there are different portions and the interiors are different in whether they are filled in or not. The first object is object 67, which is an open figure in the shape of a meaningful letter "S" with open top and bottom ends and is not filled in, and the second object is object 66, which is a closed figure in the shape of the same letter "S" and is filled in.

[0072] When comparing the stroke perimeters of the open-shaped character "S" 67 and the closed-shaped character "S" 66 with a filled-in interior, the relationship is "open-shaped character "S" 67 > closed-shaped character "S" with a filled-in interior."

[0073] When this copy-and-tamper-proof print 1 is copied, the dot gain according to the perimeter of the image line is in the following relationship: image line 67 of the open-shaped letter "S" > image line 66 of the closed-shaped letter "S" with the interior filled in.

[0074] FIG. 13(a) shows an image obtained when viewing the copy and tamper-proof printed matter 1 according to this embodiment. When the first and second objects 11 and 31 are combined, the colors are the same, so the entire image area is uniformly visible, and the significant letter "A" depicted by the dashed line at the boundary between the first image area 21 where the latent image is formed and the second image area 41 where the background image is formed is not visible. When such a copy and tamper-proof printed matter 1 is copied, the copy 2 shown in FIG. 13(b) is obtained. Because the first and second objects 11 and 31 have different perimeters, the first and second image areas 21 and 41 are copied with different color densities, revealing the latent image "A." Furthermore, in this example, the gradation is varied.

[0075] This copy and tamper-proof print 1 comprises a first object 11 shown in FIG. 14(a) and a second object 31 shown in FIG. 14(b).

[0076] The first object 11 is a white diamond-shaped object with continuously varying line thickness, and all of the white diamonds have the same center. The center of the shape of the first object 11 refers to the distance from the center of the shape to the center of the outer line. Therefore, the changes in line thickness create shades and change the gradation, but the center of the shape itself does not change. The second object 31 is a black diamond-shaped object with continuously varying line dimensions, i.e., diameter. The first object 11, which is a white diamond with varying line thickness, exhibits positive gradation, while the second object 31, which is a black diamond with varying diameter, exhibits negative gradation. These two have a negative-positive relationship, and when combined, the overall image density and overall color appear uniform when the original is viewed, concealing the latent image.

[0077] More specifically, as shown in FIG. 15, a second object 31 in the shape of a small black diamond is included within a first object 11 in the shape of a thick white diamond, and a second object 31 in the shape of a large black diamond is included within a first object 11 in the shape of a thin white diamond, resulting in an arrangement that results in a uniform overall image area ratio.

[0078] When an image having the above configuration is copied, the white diamond-shaped first object 11 has a relatively larger perimeter than the black diamond-shaped second object 31, which has the largest diameter, and therefore the dot gain of the white diamond-shaped first object 11 is visualized as a relatively strong shade during copying. Essentially, the effect of dot gain on the black diamond-shaped second object 31 during copying is relatively small and can be ignored.

[0079] Furthermore, as described above, the thick white diamond-shaped first object 11 has a shorter inner perimeter than the thin white diamond-shaped first object 11, resulting in smaller dot gains occurring inside, but conversely, the outer perimeter is longer, resulting in larger dot gains occurring outside. As a result, the dot gains inside and outside cancel each other out, so the dot gains for all white diamonds are the same, regardless of whether the lines are thick or thin. As a result, the amount of dot gain for each is the same, and the gradation that has been imparted in advance by the thickness and thinness of the lines is visualized as a latent image. In this way, by varying the line thickness of the white diamond-shaped first object line 11 and the continuous size of the black diamond-shaped second object line 31, continuous gradation can be imparted to the latent image that appears when copied.

[0080] As a result, the overall color is recognized uniformly to the naked eye and the latent image "A" in the first image area 21 is concealed, but when copied, the gradation given by the thickness and thinness of the white diamond-shaped first image line 11 becomes visible as it is, and a copy with continuous gradation is obtained.

[0081] The copy-and-tamper-resistant printed matter 1 shown in Figure 16(a) corresponds to the copy-and-tamper-resistant printed matter 1 shown in Figure 13(a) with a visible image 81 of "B" added to it, and when this copy-and-tamper-resistant printed matter 1 is copied, a copy 2 corresponding to Figure 16(b) is obtained, in which the latent image "A" in the first image area 21 becomes visible and an image with continuous gradation is obtained.

[0082] The image configuration of this copy and tamper-proof print further includes an image 71 of a visible image 81 shown in Fig. 17(a) in addition to the first image 11 and second image 31 shown in Fig. 15, and the first image 11, second image 31, and image 71 of the visible image 81 are arranged as shown in Fig. 17(b). Note that the image 71 is arranged so as not to overlap the first image 11 and second image 31.

[0083] 13(a) except that this copy and tamper-proof printed matter 1 has the same structure and effect as the copy and tamper-proof printed matter 1 shown in Fig. 13(a) in terms of the first image line 11 and the second image line 31. That is, to the naked eye, the overall color is recognized as uniform, and the latent image "A" in the first image area 21 is concealed, but when copied, the gradation of the thin white diamond-shaped first image line 11 is reflected, resulting in a copy 2 with continuous gradation.

[0084] According to the copy and tamper-proof printed matter of the above embodiment, by configuring the image area only with areas with low line count, it is possible to output a printed matter in which the latent image is concealed before copying and the latent image appears after copying, regardless of the resolution of the printer, even when using a general commercial printer or multifunction device.

[0085] Although the embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the technical scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the technical scope and spirit of the invention, and are also included in the scope of the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0086] 1. Copy and tamper-proof printed matter 2. Copies 11 First stroke 21 First Image Region 31 Second stroke 41 Second Image Region 51~67, 71 lines 81 Visible Images 52a, 52b, 53a Dot Gain H1 Dimension of the image line (height) W1 Line size (width) M1, M2 pitch

Claims

1. A copy and tamper-proof printed matter having at least a first image area including a plurality of first image lines each having a predetermined size, and a second image area including a plurality of second image lines each having a predetermined size, the first image line and the second image line have different image line perimeters and are formed so as not to overlap each other; the first image area and the second image area have the same color in visible light, When the copy-and-tamper-proof printed matter is copied, a difference occurs between the dot gain of the first image line and the dot gain of the second image line, resulting in a difference in print density between the first image area and the second image area.

2. 2. The copy and tamper-proof print according to claim 1, wherein the first and second image lines are different in at least one of line width, size, pitch, and shape.

3. 2. The copy and tamper-proof printed matter according to claim 1, further comprising a visible image formed of a third image line not overlapping the first image line and the second image line.

4. the first image area and the second image area have gradation; 4. The copy / tamper-proof print according to claim 1, wherein the first image area and the second image area have the same color at the same gradation.

Images