JP3379093B2 - Hidden image - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hidden image which is difficult to visually recognize before copying, but when copied, characters such as "copy prohibited" appear on the copy paper so that they can be visually recognized.

[0002]

2. Description of the Related Art Conventionally, as a printed matter for which copying is desired to be prevented, there has been provided a hidden image provided on the surface of a sheet such that when copying, a "copy prohibited" character or the like appears on the copy paper with the naked eye. ing. The hidden image is generally divided into two sections, a first section that constitutes a character such as a "copy prohibited" character and a graphic that indicates that copying is desired to be prevented, and a second section that constitutes a background around the character. Consists of. The first section comprises a number of first patterns,
The second section is composed of a large number of second patterns, and a large number of the first and second patterns are printed on a sheet to form a hidden image on the sheet.

Each of the first and second patterns is composed of a plurality of hidden image forming elements, and the first pattern is arranged so that the first section and the second section cannot be discriminated from each other on the sheet on which the hidden image is provided. Are formed so that the total area of the plurality of hidden image forming elements and the total area of the plurality of hidden image forming elements of the second pattern are equal to each other, and when the sheet is copied, the character is printed on the copy paper. The interval between the plurality of hidden image forming elements of the first pattern and the interval between the plurality of hidden image forming elements of the second pattern are different so that a density difference that can be visually distinguished is generated between the portion and the background portion. It is formed with different dimensions.

As such a hidden image, for example, Japanese Patent Publication No. 64-5835, Japanese Patent Publication No. 2-51742, Japanese Patent Publication No. 3-32974, and Japanese Patent Laid-Open No. 63-627.
Those disclosed in Japanese Patent Application Laid-Open No. 97-97, and Japanese Patent Application Laid-Open No. 2-29679 are conventionally known. That is, Japanese Patent Publication No.
In Japanese Patent Application Laid-Open No. 5835, Japanese Patent Publication No. 2-51742, and Japanese Patent Publication No. 3-32974, the number of hidden image forming elements of the first pattern and the number of hidden image forming elements of the second pattern are different from each other. Accordingly, there is disclosed a hidden image in which the size of each hidden image forming element of the first pattern and the size of each hidden image forming element of the second pattern are different from each other. Further, in JP-A-2-29679 and JP-A-63-62797, the contact ratio of each hidden image forming element is changed between the first pattern and the second pattern, and accordingly, the first pattern is changed. There is disclosed a hidden image in which the size of each hidden image forming element and the size of each hidden image forming element of the second pattern are different from each other.

[0005]

However, when the first pattern and the second pattern are printed on a sheet, as shown in FIG.
As shown in FIGS. 3 (a) and 3 (b), when the ink is transferred from the printing original plate to the sheet, the contour of the hidden image forming element 91 on which the ink on the printing original plate is placed by the dot gain that spreads the ink to the outside. Rather, the contour 93 of the hidden image forming element on the sheet onto which the ink is transferred becomes slightly larger. Moreover, the degree to which the contour 93 of the hidden image forming element on the sheet increases due to the dot gain increases as the contour 91 of the hidden image forming element on the printing original plate increases. Therefore, when the sizes of the hidden image forming elements forming the first and second patterns are different from each other, like the conventional hidden images disclosed in the above-mentioned five publications, the size of the hidden image forming elements on the sheet is different. There is a difference in the total area of the hidden image forming elements of each pattern, which causes a density difference that can be visually distinguished between the first section and the second section on the sheet. As a result, there is a problem that adversely affects the printed contents on the printed matter, and
There is a problem that it is easy to understand that the sheet has a hidden image.

Further, when the distance between the two hidden image forming elements is small, both hidden image forming elements are formed when the ink is transferred from the printing original plate to the sheet due to the influence of the surface tension of the ink placed on the printing original plate. Ink fills the spaces between the parts, causing a tone jump in which the two hidden imaging elements are connected on the sheet. Therefore, JP-A-2-296
Like the conventional hidden images disclosed in Japanese Patent Laid-Open No. 79 and Japanese Patent Application Laid-Open No. 63-62797, the hidden image forming elements are in contact with each other in one pattern, and the hidden image forming elements are separated from each other in the other pattern. Then, as shown in FIG.
As shown in (a), the tone jump occurs only in the pattern in which the hidden image forming elements are in contact with each other, and the outline 95 of the pattern portion on the sheet where the hidden image forming elements are in contact with each other becomes large. The difference in the total area of the hidden image forming elements of the respective patterns on the sheet is further increased, and thus the difference in density between the first section and the second section on the sheet is increased. As a result, the printed contents on the printed matter are more adversely affected, and it is more easily recognized that the sheet has a hidden image.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it difficult to distinguish the first section and the second section with the naked eye on a sheet before copying. Is to provide a hidden image on the copy paper in which the first section and the second section can be reliably distinguished by the naked eye.

[0008]

In order to achieve the above object, the present invention provides a first section in which a large number of first patterns are arranged and a second section in which a large number of second patterns are arranged. The first pattern and the second pattern each include a plurality of hidden image forming elements, and the intervals between the plurality of hidden image forming elements of the first pattern and the plurality of hidden image forming elements of the second pattern. The intervals of the hidden image forming elements are formed with different sizes, and the first and second
In a hidden image in which the total areas of a plurality of hidden image forming elements of the pattern are formed to be equal, the total length of line segments connecting the outer circumferences of the respective hidden image forming elements of the first pattern and the second pattern Is formed so that the total sum of the lengths of the line segments connecting the outer peripheries of the hidden image forming elements is equal.

Further, in the present invention, the first pattern and the second pattern are formed by a common hidden image forming element. Furthermore, the invention provides that the first pattern has two hidden imaging elements that are parallel to each other,
The second pattern has two hidden image forming elements that are parallel to each other.

In the present invention, the first pattern has a cross-hidden image forming element that intersects with the hidden image forming element, and the second pattern has a cross hidden image that intersects with the hidden image forming element. An angle at which the hidden image forming element intersects with the intersecting hidden image forming element in the first pattern, and an angle at which the hidden image forming element intersects with the intersecting hidden image forming element in the second pattern. The angles are assumed to be equal. Further, in the present invention, the first pattern has a cross-hidden image forming element that intersects with the hidden image forming element, and the second pattern has a cross hidden image forming element that intersects with the hidden image forming element. And the area where the hidden image forming element and the cross hidden image forming element overlap in the first pattern is equal to the area where the hidden image forming element and the cross hidden image forming element overlap in the second pattern. It has been formed. Further, the present invention provides the first and second
In the pattern, a plurality of the cross-hidden image forming elements are provided in parallel with each other.

Further, according to the present invention, the hidden image forming element or the cross hidden image forming element is formed by linearly extending a band having a predetermined width. Further, in the present invention, the hidden image forming element or the cross hidden image forming element is formed by extending a band having a predetermined width in a bent line shape. Further, in the present invention, the hidden image forming element or the cross hidden image forming element is formed by arranging a large number of dots having the same size and shape at equal intervals.

[0012]

The total sum of the lengths of the line segments connecting the outer circumferences of the hidden image forming elements of the first pattern and the total length of the line segments connecting the outer circumferences of the hidden image forming elements of the second pattern are equal. Therefore, even if dot gain occurs during printing of the first and second patterns on the sheet, the degree to which the contour of the first pattern on the sheet increases and the degree to which the contour of the second pattern increases on the sheet are the same. . If the angle at which the hidden image forming element intersects the intersecting hidden image forming element in the first pattern is equal to the angle at which the hidden image forming element intersects the intersecting hidden image forming element in the second pattern, these first and Even if a tone jump occurs during printing of the second pattern on the sheet, the degree to which the contour of the first pattern on the sheet increases and the degree to which the contour of the second pattern increases on the sheet are the same.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a top view of a copy protected print. In FIG. 1, reference numeral 1 is a copy-preventing printed matter. The copy-preventing printed matter 1 includes a sheet 3, a hidden image 5 that appears on a copy sheet when a copy is made on the surface of the sheet 3, and print contents formed on the surface of the sheet 3. (Not shown) and. The hidden image 5 is composed of a "copy prohibited" character portion 7 (corresponding to the first section) that indicates that copying is desired to be prevented, and a background portion 9 (corresponding to the second section) around the character section 7. In the background portion 9, a large number of fine square patterns having the same size are arranged.

FIG. 2A is an explanatory diagram of a pattern of a character portion of a hidden image according to the first embodiment, and FIG. 2B is an explanatory diagram of a pattern of a background portion thereof. The first pattern 11 arranged on the character portion 7 and the second pattern 13 arranged on the background portion 9 each include two horizontal linear elements 15 (corresponding to hidden image forming elements). All the 13 horizontal linear elements 15 are formed with the same length and width. The horizontal linear element 15 is formed by linearly extending a band having a predetermined width. In each of the patterns 11 and 13, the horizontal linear element 15 is spaced above and below each pattern 11 and 13 on both left and right sides. And extend in parallel with each other and are arranged at symmetrical positions of the patterns 11 and 13, respectively. The distance L1 between the horizontal linear elements 15 of the first pattern 11 is equal to the horizontal linear element 15 of the second pattern 13.
It is formed to be smaller than the interval L3 between them, and is set so that the character portion 7 appears on the copy paper (not shown) when copying. Each pattern 1 having such a configuration
1 and 13, the total sum of the lengths of the line segments connecting the outer circumferences of the horizontal linear elements 15 of the patterns 11 and 13 and the total area of the horizontal linear elements 15 are equal to each other.

According to the first embodiment as described above, the total lengths of the line segments connecting the outer peripheries of the horizontal linear elements 15 of the patterns 11 and 13 are formed to be equal to each other. Even if the dot gain occurs when printing 11 and 13 on the sheet 3, the horizontal linear element 15 on the sheet 3
The degree to which the contour of the pattern becomes large is the same in both patterns 11 and 13. Since the horizontal linear elements 15 of each of the patterns 11 and 13 extend in the left-right direction, the dot gain can be the directionality of the patterns 11 and 13 in the vertical direction, the horizontal direction, or the diagonal direction. Even if it has, or if the amount of dot gain generated is slightly different depending on the vertical direction, the horizontal direction, or the diagonal direction of each pattern 11, 13, the horizontal linear element 15 on the sheet 3
The degree to which the contour of the pattern becomes large is the same in both patterns 11 and 13. Further, since the two horizontal linear elements 15 are not in contact with each other in both patterns 11 and 13, it is possible to prevent the tone jump from occurring when the patterns 11 and 13 are printed on the sheet 3.

Furthermore, when characters or the like are continuously printed on a plurality of sheets 3 by, for example, offset printing, ink is not transferred to the sheets 3 and remains on the blanket, and due to the phase shift between the rotation of the printing original plate and the rotation of the blanket. The next ink is transferred from the metal original plate to the blanket portion deviated from the remaining ink, both inks are transferred to the next sheet 3, and the so-called double printing in which characters are double-printed on the sheet 3 It may occur. However, even in such a case, when the patterns 11 and 13 are printed on the sheet 3, as described above, the patterns 11 and 13 have two horizontal linear elements having the same length and the same width and extending in the left-right direction. 1
Since the patterns 5 and 5 are formed respectively, the degree to which the contour of the lateral linear element 15 on the sheet 3 increases due to the duplication is the same in both patterns 11 and 13. Therefore, according to the first embodiment, each pattern 11, 1 on the sheet 3 is
The total sum of the lengths of the line segments connecting the outer peripheries of the two horizontal linear elements 15 of 3 becomes equal to each other, whereby the total sum of the areas of the patterns 11 and 13 on the sheet 3 becomes equal to each other, and the sheet 3 There is no visible density difference between the character portion 7 and the background portion 9 above, so that it is possible to prevent the sheet 3 from easily recognizing that the hidden image 5 is provided. .

Next, a second embodiment of the present invention will be described. FIG. 3A is an explanatory diagram of a pattern of a character portion of a hidden image according to the second embodiment, and FIG. 3B is an explanatory diagram of a pattern of the background portion thereof, which are the same elements as those in FIGS. 2A and 2B. , Will be described with the same reference numerals. The first pattern 17 and the second pattern 19 according to the second embodiment are the same as the patterns 11 and 13 according to the first embodiment.
One slanted linear element 21 diagonally extending from the upper left corner to the lower right corner of 13 (corresponding to a cross hidden image forming element)
Is added.

The inclined linear element 21 is formed by linearly extending a band having a predetermined width, and each of the patterns 17 and 19 is formed.
The inclined linear elements 21 of the
The patterns 17 are formed with the same inclination and a width smaller than the width of the horizontal linear elements 15, so that the inclined linear elements 21 respectively intersect the two horizontal linear elements 15 at the positions 23. , 19 horizontal linear elements 1
The angles θ1 and θ3 at which 5 and the inclined linear element 21 intersect, and the shape and area of the portion where the lateral linear element 15 and the inclined linear element 21 overlap are the same in both patterns 17 and 19,
The character portion 7 is set so as to appear on the copy paper when the copy is made. Each pattern 1 having such a configuration
7 and 19, the sum of the lengths of the line segments that connect the outer circumferences of the horizontal linear elements 15 and the inclined linear elements 21 of the patterns 17 and 19, and the horizontal linear elements 15 and the inclined linear elements 2
The total area of 1 is equal to each other.

According to the second embodiment as described above, the lengths of the line segments connecting the outer circumferences of the two horizontal linear elements 15 and the one inclined linear element 21 of each pattern 17, 19 are equal to each other. Therefore, even if a dot gain or a double is generated when the patterns 17 and 19 are printed on the sheet 3, the extent to which the contours of the patterns 17 and 19 on the sheet 3 become large is At 19 they are identical to each other. Further, the two horizontal linear elements 15 of each pattern 17 and 19 all extend in the left-right direction, and the inclined linear elements 21 of each pattern 17 and 19 are both from the upper left corner to the lower right corner of each pattern 17, 19. Since it extends diagonally across the sheet 3 even if the dot gain and double are directional
The degree to which the contours of the patterns 17 and 19 are large is the same in both patterns 17 and 19. In addition, the point 2 where the horizontal linear element 15 and the inclined linear element 21 intersect
3, the horizontal linear element 15 of each pattern 17, 19
Since the angles θ1 and θ3 at which the inclined linear element 21 intersects with each other and the shape and the area of the portion where the horizontal linear element 15 and the inclined linear element 21 overlap each other are equal in both patterns 17 and 19. , When the patterns 17 and 19 are printed on the sheet 3, even if tone jumps occur at the intersections 23 of the patterns 17 and 19, the horizontal linear element 15 and the inclined linear element 21 on the sheet 3 are The degree to which the contour of the intersection 23 becomes large is determined by both patterns 17,
At 19 they are identical to each other. Therefore, according to the second embodiment, the lengths of line segments connecting the outer peripheries of the patterns 17 and 19 on the sheet 3 are equal to each other.
Since the areas of the patterns 17 and 19 above are equal to each other, no visible density difference occurs between the character portion 7 and the background portion 9 on the sheet 3, and therefore the hidden image is formed on the sheet 3. It is possible to prevent that it is easy to know that 5 is provided.

Next, a third embodiment of the present invention will be described. FIG. 4A is an explanatory diagram of the pattern of the character portion of the hidden image according to the third embodiment, and FIG. 4B is an explanatory diagram of the pattern of the background portion thereof, which is the same as FIGS. 2A and 2B. Elements and parts will be described with the same reference numerals. The first pattern 25 and the second pattern 27 according to the third embodiment are the same as the patterns 11 and 13 according to the first embodiment.
Two vertical straight line-shaped elements 29 (corresponding to intersecting hidden image forming elements) which are spaced from each other on the right and left sides of 13 and extend parallel to each other on both upper and lower sides are added.

The horizontal linear elements 15 and the vertical linear elements 29 of both patterns 25 and 27 are all formed to have the same length and width, and the vertical linear elements 29 of each pattern 25 and 27 are the two horizontal elements. The transverse linear element 15 and the longitudinal linear element 2 are intersected at right angles with the linear elements 15 and therefore at the points 31 where the transverse linear elements 15 and the longitudinal linear elements 29 intersect.
The shape and area of the portion where 9 is overlapped are both patterns 25 and 27.
They are equal to each other. The vertical linear elements 29 of each of the patterns 25 and 27 are arranged at symmetrical positions of the patterns 25 and 27, respectively, and the interval L5 between the two vertical linear elements 29 of the first pattern 25 is two horizontal. The distance L1 between the linear elements 15 is equal to the distance L7 between the two vertical linear elements 29 in the second pattern 27, which is equal to the distance L3 between the two horizontal linear elements 15. Is set to appear on the copy paper. In each of the patterns 25 and 27 having such a configuration, the sum of the lengths of the line segments connecting the outer peripheries of the horizontal linear elements 15 and the vertical linear elements 29 of the patterns 25 and 27, and the horizontal linear elements The total area of 15 and each of the vertical linear elements 29 is equal to each other.

According to such a third embodiment, the second
The same effects as those of the embodiment can be obtained, and FIGS.
The imaginary line indicates the degree to which the contour 33 of each pattern 25, 27 on the sheet 3 becomes large when a dot gain occurs when the pattern 25, 27 is printed on the sheet 3.

Next, a modification of the third embodiment will be described. FIG. 6A is an explanatory diagram of a pattern of a character portion of a hidden image according to the first modified example, FIG. 6B is an explanatory diagram of a fine area of the background portion 9, and FIG. 4A and FIG. The same elements and parts will be described with the same reference numerals. The 1st pattern 35 and the 2nd pattern 37 which concern on a 1st modification change the arrangement | positioning of the two horizontal linear elements 15 and the two vertical linear elements 29 of each pattern 25, 27 which concerns on a 3rd Example. It is a thing. That is, the first pattern 35 and the second pattern 37
The arrangement of the lower horizontal straight line element 15 and the right vertical straight line element 29 of each pattern 35, 37 is the same as each other, and the upper horizontal straight line element 15 and the left vertical straight line element 15 of each pattern 35, 37 are the same. As for the arrangement of the elements 29, the first pattern 35 is closer to the lower horizontal straight line element 15 and the right vertical straight line element 29 than the second pattern 37. It is vertically asymmetric and laterally asymmetric. Each pattern 35, 3 having such a configuration
7, each horizontal linear element 1 of each pattern 35, 37
5 and the sum of the lengths of the line segments connecting the outer peripheries of the vertical linear elements 29 and the total of the areas of the horizontal linear elements 15 and the vertical linear elements 29 are equal to each other.

FIG. 7A is an explanatory diagram of a pattern of a character portion of a hidden image according to the second modification, FIG. 7B is an explanatory diagram of a pattern of the background portion thereof, and FIGS. 4A and 4B. The same elements and parts as those in FIG. The first pattern 39 and the second pattern 41 according to the second modification are
In each of the patterns 25 and 27 according to the third embodiment, the width of the lower horizontal linear element 15 and the right vertical linear element 29 is increased, and the upper horizontal linear element 15 and the left vertical linear element 29 are widened. The width of 29 is narrowed to be vertically asymmetrical and asymmetrical to the left and right, and the horizontal linear elements 43 and the vertical linear elements 45 having large widths of both patterns 39 and 41 are all formed to have the same width. , 41 with a narrow lateral straight element 47
And the vertical linear elements 49 are all formed with the same width. In each of the patterns 39 and 41 having such a configuration, the horizontal linear elements 43 of the patterns 39 and 41,
The sum of the lengths of the line segments connecting the outer circumferences of 47 and the vertical linear elements 45, 49 and the total of the areas of the horizontal linear elements 43, 47 and the vertical linear elements 45, 49 are equal to each other.

FIG. 8A is an explanatory view of a pattern of a character portion of a hidden image according to the third modification, FIG. 8B is an explanatory view of a pattern of the background portion thereof, and FIGS. 4A and 4B. The same elements and parts as those in FIG. The first pattern 51 and the second pattern 53 according to the third modification are
The two horizontal linear elements 15 and the two vertical linear elements 29 in each of the patterns 25 and 27 according to the third embodiment are shortened,
The ends of the horizontal linear elements 55 and the vertical linear elements 57 are located inside the patterns 51 and 53.
In each of the patterns 51 and 53 having such a configuration, the sum of the lengths of the line segments connecting the outer circumferences of the horizontal linear elements 55 and the vertical linear elements 57 of the patterns 51 and 53, and the horizontal linear elements 55 and the vertical linear elements 57 have the same total area. According to the first to third modified examples described above, the same operation and effect as those of the third example can be obtained, and FIG.
The imaginary lines in (a) and (b) are the patterns 5 of the third modification.
1 shows the degree to which the contour 59 of each pattern 51, 53 on the sheet 3 becomes large when a double image is generated when the sheet 1, 3 is printed on the sheet 3.

Next, a fourth embodiment of the present invention will be described. FIG. 10A is an explanatory diagram of the pattern of the character portion of the hidden image according to the fourth embodiment, and FIG. 10B is an explanatory diagram of the pattern of the background portion thereof. The first pattern 61 and the second pattern 63 according to the fourth example are the patterns 2 according to the third example.
Two horizontal dashed-line elements 15 and 27 composed of two horizontal linear elements 15 and two vertical linear elements 29, in which a large number of rectangular dots of the same size are arranged at equal intervals. 65 and two vertical broken line shaped elements 67 (corresponding to the cross hidden image forming elements). At a portion 69 where the horizontal broken line-shaped element 65 and the vertical broken line shaped element 67 of each pattern 61, 63 intersect, one dot 6501 of the horizontal broken line shaped element 65 and one dot 6701 of the vertical broken line shaped element 67 overlap each other by half. Therefore, the shape and the area of the portion where the horizontal broken line element 65 and the vertical broken line element 67 overlap each other are the same in both patterns 61 and 63. Further, at a position 69 where the horizontal broken line-shaped element 65 and the vertical broken line shaped element 67 of each of the patterns 61 and 63 intersect, another dot 6503 of the horizontal broken line shaped element 65 is provided on the short side of the dot 6701 of the vertical broken line shaped element 67. Of the dot 6503 of the horizontal broken line-shaped element 65 is in contact with the short side of the dot 6501 of the horizontal broken line-shaped element 65, and the long side of another dot 6703 of the vertical broken line-shaped element 67 is in contact. The corner and the corner of the dot 6701 of the vertical broken line element 67 are in contact with each other. Each pattern 61, 6 having such a configuration
3, each horizontal broken line-shaped element 6 of each pattern 61, 63
5 and the sum of the lengths of the line segments connecting the outer peripheries of the vertical broken line elements 67 and the total of the areas of the horizontal broken line elements 65 and the vertical broken line elements 67 are equal to each other. According to such a fourth embodiment, the same operational effects as those of the third embodiment can be obtained.

Next, a fifth embodiment of the present invention will be described. FIG. 11A is an explanatory diagram of the pattern of the character portion of the hidden image according to the fifth embodiment, and FIG. 11B is an explanatory diagram of the pattern of the background portion thereof. The first pattern 71 and the second pattern 73 according to the fifth example are the patterns 2 according to the third example.
Two horizontal straight line elements 15 and two vertical straight line elements 29 of 5, 27 are formed by arranging a large number of circular dots of the same size on a straight line at equal intervals. Dashed element 7
5 and two vertical broken line-shaped elements 77 (corresponding to the cross hidden image forming elements). At a location 79 where the horizontal broken line-shaped element 75 and the vertical broken line shaped element 77 intersect, one dot 7501 has a horizontal broken line shaped element 75 and a vertical broken line shaped element 77.
Doubles as Each pattern 7 having such a configuration
1 and 73, the sum of the lengths of the line segments connecting the outer peripheries of the horizontal broken line elements 75 and the vertical broken line elements 77 of the patterns 75 and 77, and the horizontal broken line element 75 and the vertical broken line elements 7 respectively.
The total area of 7 is equal to each other. According to the fifth embodiment as described above, since the horizontal broken line element 75 and the vertical broken line element 77 do not overlap with each other, the same effect as the first embodiment can be obtained.

Next, a sixth embodiment of the present invention will be described. FIG. 12A is an explanatory diagram of the pattern of the character portion of the hidden image according to the sixth embodiment, and FIG. 12B is an explanatory diagram of the pattern of the background portion thereof. The first pattern 81 and the second pattern 83 according to the sixth example are the patterns 2 according to the third example.
5, 27 two horizontal linear elements 15 and two vertical linear elements 29, two horizontal bending linear elements 85 and 2 formed by extending a band of a predetermined width in a bending linear shape. Vertical bending linear element 8
7 (corresponding to the cross-hidden image forming element). At the location 89 where the horizontal bending linear element 85 and the vertical bending linear element 87 of each of the patterns 81 and 83 intersect, the shape and area of the portion where the horizontal bending linear element 85 and the vertical bending linear element 87 overlap are both patterns 81. , 83 are equal to each other.
In each of the patterns 81 and 83 having such a configuration, the sum of the lengths of the line segments that connect the outer circumferences of the lateral bending linear elements 85 and the vertical bending linear elements 87 of the patterns 81 and 83, and the horizontal bending The sum total of the areas of the linear element 85 and each of the vertically bent linear elements 87 is equal to each other. According to the sixth embodiment as described above, it is possible to obtain the same effects as those of the third embodiment.

In each of the above-described embodiments and its modifications, the first patterns 11, 17, 25, 35, 39, 5 are used.
1, 61, 71, 81 are used as patterns for the background portion 9, and second patterns 13, 19, 27, 37, 41, 5 are used.
You may make it use 3,63,73,83 as a pattern for the character part 7. Further, the present invention is not limited to the hidden image 5 composed of the character portion 7 and the background portion 9 around the character portion 7 as described in each of the above-described embodiments and the modifications thereof, but may be a character portion such as a figure or a symbol and the surrounding area. It goes without saying that it can also be applied to a hidden image consisting of the background part of.

[0030]

As described above, according to the present invention, a first section formed by arranging a large number of first patterns,
A second section formed by arranging a large number of second patterns, wherein the first pattern and the second pattern each include a plurality of hidden image forming elements,
The intervals between the plurality of hidden image forming elements of the pattern and the intervals between the plurality of hidden image forming elements of the second pattern are formed with different sizes, and the plurality of hidden image formations of the first and second patterns are formed. In the hidden image in which the total area of the image forming elements is equal, the sum of the lengths of line segments connecting the outer circumferences of the hidden image forming elements of the first pattern and the hidden image forming elements of the second pattern are formed. The total length of the line segments connecting the outer circumferences of the two is made equal.
Therefore, even if a dot gain occurs during printing on the sheet of the first and second patterns, the total length of line segments connecting the outer peripheries of the respective hidden image forming elements of the first pattern on the sheet, and the sheet The sum of the lengths of the line segments that connect the outer peripheries of the respective hidden image forming elements of the second pattern above becomes equal, which makes it difficult to visually distinguish the first section and the second section on the sheet before copying. In addition, the first section and the second section can be surely discriminated from each other on the copy paper when copied.

[Brief description of drawings]

FIG. 1 is a plan view of a copy-proof printed matter to which the present invention is applied.

2A is an explanatory diagram of a pattern of a character portion of a hidden image according to the first embodiment, and FIG. 2B is an explanatory diagram of a fine area of the background portion 9;

FIG. 3A is an explanatory diagram of a pattern of a character portion of a hidden image according to the second embodiment, and FIG. 3B is an explanatory diagram of a pattern of a background portion thereof.

FIG. 4A is an explanatory diagram of a pattern of a character portion of a hidden image according to the third embodiment, and FIG. 4B is an explanatory diagram of a pattern of a background portion thereof.

5A and 5B are explanatory diagrams of each pattern on a sheet whose contour is enlarged by dot gain.

FIG. 6A is an explanatory diagram of a pattern of a character portion of a hidden image according to the first modification of the third embodiment, and FIG. 6B is an explanatory diagram of a pattern of the background portion thereof.

7A is an explanatory diagram of a pattern of a character portion of a hidden image according to a second modification of the third embodiment, and FIG. 7B is an explanatory diagram of a pattern of the background portion thereof.

FIG. 8A is an explanatory diagram of a pattern of a character portion of a hidden image according to a third modification of the third embodiment, and FIG. 8B is an explanatory diagram of a pattern of the background portion thereof.

9 (a) and 9 (b) are explanatory views of each pattern on a sheet whose contour has become large due to duplication.

FIG. 10A is an explanatory diagram of a pattern of a character portion of a hidden image according to the fourth embodiment, and FIG. 10B is an explanatory diagram of a pattern of a background portion thereof.

FIG. 11A is an explanatory diagram of a pattern of a character portion of a hidden image according to the fifth embodiment, and FIG. 11B is an explanatory diagram of a pattern of a background portion thereof.

FIG. 12A is an explanatory diagram of a pattern of a character portion of a hidden image according to the sixth embodiment, and FIG. 12B is an explanatory diagram of a pattern of a background portion thereof.

13A is an explanatory diagram of a pattern of a character portion of a hidden image according to a conventional example, and FIG. 13B is an explanatory diagram of a pattern of a background portion thereof.

[Explanation of symbols]

5 Hidden image 7 Character part 9 Background part 13, 21, 29, 39, 43, 55, 65, 75, 8
5 First patterns 17, 23, 31, 41, 45, 57, 67, 77, 8
7 2nd pattern 15,43,47,55 horizontal linear element 21 inclined linear element 29,45,49,57 vertical linear element 65,75 horizontal broken line element 6501,6503,6701,6703,7501
Dots 67, 77 Vertical broken line elements L1, L3, L5, L7 Intervals θ1, θ3 Angles

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-167870 (JP, A) JP-A-6-247089 (JP, A) JP-A-59-120491 (JP, A) Actual development Sho-59- 99773 (JP, U) Actual Kaihei 4-67667 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41M 3/14 B42D 15/10 531

Claims (9)

(57) [Claims] 1. A first section formed by arranging a large number of first patterns and a second section formed by arranging a large number of second patterns, wherein the first pattern and the second pattern Are each composed of a plurality of hidden image forming elements, and the intervals between the plurality of hidden image forming elements of the first pattern and the intervals between the plurality of hidden image forming elements of the second pattern are formed with different sizes. In the hidden image in which the total areas of the plurality of hidden image forming elements of the first and second patterns are equal, the length of a line segment connecting the outer circumferences of the respective hidden image forming elements of the first pattern And a total length of line segments connecting the outer circumferences of the hidden image forming elements of the second pattern are equal to each other. 2. The hidden image according to claim 1, wherein the first pattern and the second pattern are formed by a common hidden image forming element. 3. The first patterns are parallel to each other.
And two hidden imaging elements, the second pattern comprising:
A hidden image according to claim 1 or 2 having two hidden imaging elements that are parallel to each other. 4. The first pattern has intersecting hidden image forming elements that intersect with the hidden image forming element, and the second pattern includes intersecting hidden image forming elements that intersect with the hidden image forming element. And an angle at which the hidden image forming element intersects the intersecting hidden image forming element in the first pattern is equal to an angle at which the hidden image forming element intersects the intersecting hidden image forming element in the second pattern. The hidden image according to claim 1, 2, or 3. 5. The first pattern has intersecting hidden image forming elements that intersect with the hidden image forming element, and the second pattern includes intersecting hidden image forming elements that intersect with the hidden image forming element. And an area where the hidden image forming element and the intersecting hidden image forming element overlap in the first pattern and an area where the hidden image forming element overlaps the intersecting hidden image forming element in the second pattern are formed to be equal to each other. The hidden image according to claim 1, 2, or 3. 6. The hidden image according to claim 4, wherein a plurality of the intersecting hidden image forming elements are provided in parallel with each other in the first and second patterns. 7. The hidden image forming element or the intersecting hidden image forming element is formed by linearly extending a band having a predetermined width. Hidden image described. 8. The hidden image forming element or the intersecting hidden image forming element is formed by extending a band having a predetermined width in a bent line shape. The hidden image described in 6. 9. The hidden image forming element or the crossed hidden image forming element is formed by arranging a large number of dots having the same size and shape at equal intervals.
The hidden image described in 2, 3, 4, 5 or 6.