JP2011043822A - Image forming apparatus and method, and image forming object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent conspicuousness of a latent image pattern in front view by forming a latent image equivalent to an intaglio latent image with toner using an electrophotographic image forming apparatus. <P>SOLUTION: In the method, with respect to a plurality of latent image lines L2 constituting a latent image pattern, a color material is attached in a large amount so that the color material is attached as thickly as in intaglio latent image printing. A first straight line L1 along the main scanning direction and a second straight line L3 along the sub scanning direction are perpendicular to each other, and a camouflage pattern with dots D printed randomly on intersections of the first straight line L1 and the latent image line L2 with the second straight line L3 is synthesized over the whole latent image pattern. As a result, when these images are printed on paper, the latent image pattern becomes inconspicuous in front view. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  Embodiments described herein relate generally to an image forming apparatus that forms an intaglio latent image on print paper by electrophotography.

  Conventionally, as one of the anti-counterfeiting techniques, an intaglio latent image in which a latent image is formed by intaglio printing on a gift certificate or a security is known. The principle of intaglio printing used for such gift certificates and securities will be described. First, as shown in FIG. 9, the first straight line 101 printed with a special ink that can be printed in a raised state on the paper 100 with a width w, and a normal ink (ink without ink) printed with a width w. A case is assumed where a plurality of continuous lines 103 printed as a single line with the second straight line 102 are printed in parallel at a constant pitch. Here, when the sheet 100 is viewed from the front indicated by the arrow A, as shown in FIG. 10, the plurality of continuous lines 103 are separately seen as one line, and the first straight line 101 and the second straight line 102 are also seen. The boundary between and can be seen as a single line. In this case, the continuous line 103 appears as halftone density. On the other hand, when the paper 100 is viewed from an oblique direction with respect to the front surface indicated by the arrow B, the paper 100 between the first straight lines 101 is formed with the rising ink constituting the first straight line 101 as shown in FIG. The surface of is hidden. Therefore, these first straight lines 101 appear dark and light and dark appear with respect to the second straight line 102, and the plurality of first straight lines 101 appear as thick single lines 104. That is, this single line 104 forms a latent image. When the sheet 100 is viewed from the side indicated by the arrow C, the plurality of continuous lines 103 are viewed separately as simply a plurality of continuous lines 103 having a halftone density.

  Such intaglio printing uses special inks, requires extremely advanced printing technology, and intaglio is very expensive.

  And if it can confirm that the intaglio latent image appears for the first time by seeing the printed matter diagonally, the printed matter such as the gift certificate or the securities printed with the intaglio latent image is a proof that the printed matter is genuine. However, when the intaglio latent image printing portion is viewed from the front, if even a slight latent image is seen, serious suspicion arises, so that the printed matter cannot be handled as a real one.

  Conventional intaglio latent image printing techniques are extremely sophisticated and expensive, and have been used in a limited range. However, if an intaglio latent image can be formed together with recorded images of characters, figures, symbols, numbers, etc. from a printer without using an intaglio for intaglio printing, it is guaranteed that the printed paper itself is the original. It is possible to easily prevent information leakage and counterfeit / illegal copy.

  Therefore, the present inventor has focused on an electrophotographic image forming apparatus, and has completed the present invention that can form a latent image equivalent to an intaglio latent image by enlarging a color material such as toner.

  The configuration of the image forming apparatus according to the embodiment generates a plurality of spaced apart latent image lines constituting an image pattern of a latent image, and performs image synthesis on the latent image pattern formed by the plurality of latent image lines. An image processing unit that generates a camouflage pattern that makes the latent image pattern inconspicuous in a front view in a state where the latent image pattern is printed on a sheet; and a latent image line generated by the image processing unit; A color material image is formed with respect to the camouflage pattern, and an image forming unit for adhering the amount of color material adhering to the latent image line to a height at which the latent image appears, and a color material image formed by the image forming unit are transferred to a sheet. The electrophotographic image forming apparatus includes a transfer unit and a fixing unit that fixes an unfixed color material image transferred onto the paper.

1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating a system configuration of an image forming apparatus according to an embodiment. The operation part of the image forming apparatus by this embodiment is shown, The enlarged view of the other camouflage pattern shown on a display part is shown. FIG. 5 is a diagram illustrating an example of a sheet with a latent image printed by the image forming apparatus according to the embodiment. It is a figure which shows an example of the intaglio latent image of the unfixed state formed by the electrophotographic system. It is a figure which shows an example in the state which fixed the intaglio latent image of FIG. 5 to the paper. It is a figure which shows an example which camouflaged the latent image with the dotless camouflage pattern in the latent image display part of the paper. It is a figure which shows an example which camouflaged the latent image with the camouflage pattern with a dot formed in the latent image display part of the paper. It is a figure for demonstrating an intaglio latent image. It is A arrow directional view of FIG. It is a B arrow line view of FIG.

Hereinafter, the present embodiment will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of the image forming apparatus according to the present embodiment. FIG. 2 is a block diagram showing the system configuration of the image forming apparatus according to the present embodiment.
FIG. 3 shows an operation unit of the image forming apparatus, and shows an enlarged view of another camouflage pattern shown on the display unit.

  1 and 2, an image forming apparatus 1 according to the present embodiment is an electrophotographic multi-function printer (MFP). An automatic document feeder (ADF) 3 is disposed on an upper part of an apparatus main body 2 and is on a document tray. The originals stacked on the paper are conveyed one by one to the image reading unit (scanner) 4. The image reading unit 4 has a mode for reading a document from the ADF 3 and a mode for reading a document placed on the document table glass 5, and the scanned document information (scanner data) is converted into an RGB scanner by the first image processing unit 6. The data is processed and input to the storage unit 14.

  Document information from the personal computer 11 is input to the printer controller unit 13 via the external interface unit (external I / F unit) 12 and temporarily stored in the storage unit 14.

  Here, the storage unit 14 includes a first memory 15 that stores document information, and a second memory 16 that stores intaglio latent image information described later and camouflage pattern information described later. Document information in the first memory 15 is input to the first memory control unit 17, and document information controlled by the first memory control unit 17 is input to the second image processing unit 19. In the processing unit 20, the second image processing unit 19 performs image processing such as separating the document information into image data of each color of Y (yellow), M (magenta), C (cyan), and K (black).

  Here, when only the document image is printed, information for each color is output from the processing unit 20 to the image forming unit 7. The processing unit 20 includes a color material limit unit 21 for limiting the amount of color material that is toner, and limits the amount of toner that adheres to the photosensitive drum in the image forming unit 7. If the amount (height) of unfixed toner image transferred to the paper is large, fixing failure will occur and color material will be scattered. To prevent these phenomena, the amount of color material applied is limited. To do. As a method for limiting the amount of color material attached, for example, there is a method for limiting the charging potential of the photosensitive drum, the output of laser exposure, and the like.

  The image forming unit 7 of the image forming apparatus 1 is provided for each color of Y (yellow), M (magenta), C (cyan), and K (black) (7Y, 7M, 7C, 7K). (7Y, 7M, 7C, and 7K) each include a photosensitive drum, a laser unit, a developing device, a charger, a cleaning device, and the like.

  Each image forming unit (7Y, 7M, 7C, 7K) is a primary transfer charger using toners of colors Y (yellow), M (magenta), C (cyan), and K (black) as color materials. Then, the toner image formed on the intermediate transfer belt 8 is sequentially overlapped at the primary transfer position where the secondary transfer charger 35 is disposed, and the toner image overlapped at the transfer position where the secondary transfer charger 35 is disposed is transferred to a printing sheet. Then, the sheet to which the unfixed toner image is transferred is conveyed toward the fixing unit 9, and the unfixed toner image is heated and pressed by the fixing unit 9 to be fixed on the sheet. In this case, the paper is discharged to the paper discharge tray 10.

  On the other hand, the second memory 16 of the storage unit 14 stores, for example, a latent image (latent image original data) formed by the personal computer 11 and a plurality of camouflage pattern data for camouflaging a latent image printed on paper. . The latent image source data stored in the second memory 16 is composed of characters, graphics, symbols, image data, or combination information thereof, and the ON signal of the latent image print selection switch 24 is output to the control unit 23. Then, the control unit 23 stores the latent image source data stored in the second memory 16 in the second memory control unit 18 and stores the selected camouflage pattern data in the first memory control unit 17.

  Note that the control unit 23, the first memory control unit 17, the second memory control unit 18, the second image processing unit 19, and the storage unit in this embodiment are, for example, a CPU 801 (Central processing unit) mounted on the MFP. It can be realized by an arithmetic device or a storage device such as the MEMORY 803 or the HDD 804. It goes without saying that the CPU 801 can be replaced by an MPU (Micro Processing Unit) capable of executing equivalent arithmetic processing. Similarly, the HDD 804 can be replaced by a storage device such as a flash memory.

  In the present embodiment, when the ON signal of the latent image print selection switch 24 is output to the control unit 23, a display including a liquid crystal panel or the like provided in the operation unit 26 of the image forming apparatus 1 as shown in FIG. A plurality of camouflage patterns are displayed on the unit 27, and the camouflage pattern selected by the camouflage pattern selection switch 25 configured by, for example, a panel switch is stored in the first memory control unit 17.

  FIG. 4 shows a state in which the image printing unit S1 and the latent image printing unit S2 are printed on the printing paper S. The color material amount of the image of the image printing unit S1 is limited by the color material limit unit 21. It does not exceed a fixed amount (predetermined height). Further, the camouflage pattern only needs to have the same height as the image printed on the image printing unit S1, so that the color material amount is limited by the color material limit unit 21 of the processing unit 20.

  On the other hand, the lines constituting the latent image printed on the latent image printing unit S2 require a certain height as shown in FIGS. Therefore, the latent image data is output from the second control unit 18 to the image composition unit 22 provided on the rear side of the color material limit unit 21 so that the toner is swelled without being limited by the color material limit unit 21.

  The control unit 23 outputs the composition image data 23 a from the second memory control unit 18 to the image composition unit 22. Further, the control unit 23 outputs the composition image ON / OFF control signal 23b to the image composition unit 22, and when the composition image ON / OFF control signal 23b is “0”, there is no image composition, and when it is “1”. Is instructed to synthesize an image. That is, when forming the latent image “P” shown in FIG. 5 in the latent image printing unit S2, for example, if the horizontal direction in the figure is the main scanning direction and the vertical direction is the sub-scanning direction, The composition image ON / OFF control signal 23b is set to “1” at the timing of forming the latent image line L2 along the main scanning direction that contributes to the character image in one straight line L1, and “0” otherwise. However, the first straight line L1 is not formed for the blank portion in the character, but the second straight line L3 is formed along the sub-scanning direction. Note that the second straight line L3 does not contribute to the formation of the latent image. A pattern composed of a large number of first straight lines L1 and second straight lines L3 is taken as an example of a camouflage pattern.

  FIG. 5 shows a state in which a latent image “P” is formed by an unfixed toner image, and the first straight line L1 and the latent image line L2 are formed to have the same line width. However, when the sheet S carrying the unfixed toner image passes through the fixing device 9 and the toner is heated and pressurized, as shown in FIG. The line width of the latent image line L2 is thicker than the line (non-latent image forming line portion) in which the latent image line L2 is not formed in one straight line L1. Therefore, when the latent image printing portion S2 of the paper S is viewed from the front, the latent image “P” is visually recognized due to the difference in the line width. 5 and 6 are drawn so that the line widths are greatly different, and for easy understanding, the distance between the first straight line L1 and the second straight line L3 is drawn wider than the actual one. .

  Further, since the line width of the latent image line L2 formed by the laser beam is very thin, no fixing failure occurs even if the color material is raised to form the latent image line L2. Further, the control unit 23 outputs a weighting coefficient (%) 23c for exciting each color material to the image composition unit 22, and multiplies the image data for composition 23a of each color output to the image composition unit 22 by the weighting coefficient. Thus, an unfixed toner image is formed with a color material in an amount necessary for forming a latent image.

  As shown in FIG. 6, in the camouflage pattern indicated by the first straight line L1 and the second straight line L3 that are orthogonal to each other, the latent image line L2 and the non-latent image forming line portion whose line width is increased by visual observation from the front. And can be distinguished.

  Therefore, in order to make the latent image line L2 whose line width has become thicker due to the fixing process to be apparently inconspicuous, dots having a diameter that protrudes beyond the line width of the fixed latent image line L2 are used as the first straight line L1 latent image. A large number of dots D are randomly formed at the intersections of the line L2 and the second straight line L3. Due to the large number of dots, the difference in line width between the first straight line L1 and the second straight line L3 becomes inconspicuous with respect to the fixed latent image line L2.

  FIG. 7 is a diagram in which a latent image of “1048” is formed on the latent image printing unit S2 together with a camouflage pattern composed of a number of first straight lines L1 and second straight lines L2, and FIG. 8 is similar to FIG. In addition, a latent image of “1048” is formed on the latent image printing unit S2 together with a camouflage pattern composed of a number of first straight lines L1 and second straight lines L2, and further, the first straight line L1, the latent image line L2, and the first 2 is a front view of a state in which a large number of dots D are randomly formed at intersections with a straight line L3.

In FIG. 8, it is confirmed that the latent image “1048” is less noticeable than FIG. Although the dots D are randomly formed, they may be arranged with regularity in an oblique direction as shown in the partially enlarged view. This is because the human eye is likely to notice vertical and horizontal lines, and by adding a pattern in an oblique direction, the vertical lines and parallel lines are made inconspicuous.
Further, the first straight line L1, the second straight line L3, the latent image line L2, and the dot D are all formed in the same color.

  In this embodiment, the thick line width of the fixed latent image line L is increased by a camouflage pattern in which dots D are formed at the intersections of the first straight line L1, the latent image line L2, and the second straight line L3 that are orthogonal to each other. Although it has been described that it is inconspicuous, the present invention is not limited to this, and may be a camouflage pattern having another shape as shown in FIG.

  The display unit 27 shown in FIG. 3 includes a corrugated camouflage pattern 30, a first camouflage pattern 31 with a cross pattern in which a large number of diagonal lines intersect at a narrow pitch to reduce the rhombus space, and a scaled camouflage pattern 32, an intersecting second camouflage pattern 33 is prepared in which the pitch of the diagonal lines is wider than that of the first camouflage pattern 31 to enlarge the rhombus space.

  These four types of camouflage patterns 30 to 33 have regularity different from the latent image pattern, and exhibit the same effects as the dot camouflage pattern.

Next, an image forming operation when the latent image printing mode is selected will be described.
When the latent image print selection switch 24 provided in the operation unit 26 is turned on, latent image data is output to the image composition unit 22, and a latent image can be formed in the latent image print unit S2 that allows the color material to rise. And wait for the start switch 29 to be turned on. Further, the image processing unit 22 outputs document information to be printed on the image printing unit S1 and pattern information of the selected camouflage pattern (an example in which the camouflage pattern in FIG. 8 is selected) to the image processing unit 21. , And waits for the start switch 29 to be turned on.

  When the start switch 29 is turned on, an image signal of each color whose color material adhesion amount is limited by the color material limit unit 21 is output to the image forming unit 7 of each color, and the first straight line to be printed on the latent image printing unit. A camouflage pattern composed of L1 (excluding the latent image line L2), the second straight line L3, and the dot D (the portion of the dot D formed on the latent image line L2 that protrudes from the latent image line 2) has each color. The image is output to the image forming unit 7. Then, the latent image signal of each color from which the color material limit is released is output from the image composition unit 22 to the image forming unit 7.

  Specifically, image light is scanned in the main scanning direction by the laser exposure optical system on the photosensitive drums of the image forming units (7Y, 7M, 7C, and 7K) of the respective colors, and the toner adheres to the image portion by the developing unit. The toner image on the photosensitive drum is transferred to the intermediate transfer belt 8 by the primary transfer charger 34 at the primary transfer position. The amount of toner that adheres to the latent image (different from the intaglio latent image) formed on the photosensitive drum by the developing unit is defined as the maximum amount for the image limited by the color material limit unit 21, whereas The latent image output to the image composition unit 22 without passing through the color material limit unit 21 is developed to exceed the toner adhesion amount limited so as to obtain a height at which an effect as an intaglio latent image can be obtained. Note that the image formed on the image printing unit S1 has an interval between the latent image lines L2 constituting the latent image to be printed on the latent image printing unit S2 as compared to the line interval in the main scanning direction scanned by the laser exposure optical system. Is widely formed so that the individual latent image lines L2 in a fixed state have a gap. Therefore, the distance between the first straight line L1 and the second straight line L2 is set in accordance with the distance between the latent image lines L2.

  As shown in FIG. 4, the image forming units (7Y, 7M, 7C, and 7K) for the respective colors have the maximum toner adhesion amount limited to the image printing unit S1 of the printing paper S by the color material limit unit 21. The original document image is formed, and a dot camouflage pattern in which the maximum value of the toner adhesion amount is limited by the color material limit unit 21 is formed on the latent image printing unit S2 of the paper S. Further, the latent image in the latent image printing unit S2 is formed with the set adhesion amount (height) of the latent image line L2 without being limited by the toner adhesion amount. Note that the camouflage pattern with dots (the first straight line L1 and the second straight line L3) and the latent image line L2 have the same color and are supported on the intermediate transfer belt 8 in the order of Y, M, C, K, and the secondary transfer charger 35. Is transferred onto the sheet S at the secondary transfer position. Then, the unfixed toner images of the paper S in the document printing unit S1 and the latent image printing unit S2 are fixed on the paper S by heating and pressurizing by the fixing unit 9 and discharged onto the paper discharge tray 10.

  For example, as shown in FIG. 8, the fixed image in the latent image printing unit S2 is formed by a raised latent image line L2 having the number “1048” on the same line as the first straight line L1, and the latent image line L2 Even if the line width becomes larger than the line width of the first straight line L1 due to fixing, the camouflage effect of the dot D makes it difficult to distinguish the latent image line L2 from the first straight line L1 even when viewed from the front. When the latent image printing unit S2 is viewed obliquely from the front, the latent image “1048” is visually recognized.

  In the above-described embodiment, the latent image display unit S2 is set on the upper portion of the sheet S. However, the present invention is not limited to this, and the latent image display unit may be any area on the sheet S that can be printed. Can be set.

Each operation in the processing in the image forming apparatus described above is realized by causing the CPU 801 or the like to execute an image forming program stored in the memory 802.
Furthermore, it is possible to provide a program that causes a computer constituting the image forming apparatus to execute each operation described above as an image forming program. In the present embodiment, the case where the program for realizing the function for carrying out the invention is recorded in advance in a storage area provided inside the apparatus is exemplified. However, the present invention is not limited to this, and a similar program can be downloaded from the network. It may be downloaded to the apparatus, or a similar program stored in a computer-readable recording medium may be installed in the apparatus. The recording medium may be in any form as long as it can store a program and can be read by a computer. Specifically, as the recording medium, for example, an internal storage device such as a ROM or a RAM, a portable storage medium such as a CD-ROM, a flexible disk, a DVD disk, a magneto-optical disk, or an IC card, a computer Examples include a database holding a program, another computer, its database, and a transmission medium on a line. In addition, the function obtained by installing or downloading in advance may be realized in cooperation with an OS (operating system) or the like inside the apparatus.
Note that a part or all of the program may be an execution module that is dynamically generated.
In addition, it goes without saying that various processes realized by causing a processor to execute a program in each of the above-described embodiments can be executed at least in part by the ASIC 802 in a circuit form.

  According to this embodiment, a latent image pattern similar to an intaglio latent image can be printed on a sheet by an electrophotographic image forming apparatus, and the latent image pattern printed on the sheet by a camouflage pattern can be viewed from the front. However, even if the latent image pattern becomes inconspicuous and the color material such as toner becomes thicker due to fixing, it can serve as a latent image.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 apparatus main body, 3 automatic document feeder (ADF), 4 image reading part (scanner), 5 original plate glass, 6 1st image processing part, 7 (7Y, 7M, 7C, 7K) Image formation Section, 8 intermediate transfer belt, 9 fixing section, 10 paper discharge tray,
11 PC, 12 External interface unit (external I / F unit), 13 Printer controller unit, 14 Storage unit, 15 First memory, 16 Second memory,
17 first memory control unit, 18 second memory control unit, 19 second image processing unit, 20 processing unit, 21 color material limit unit, 22 image composition unit, 23 control unit, 23a composition image data, 23b composition image ON / OFF control signal, 23c weighting coefficient (%), 24 latent image print selection switch, 25 camouflage pattern selection switch, 26 operation unit, 27 display unit, 28 start button, 29 start switch, 30 wave-shaped pattern camouflage pattern, 31 cross-pattern first camouflage pattern, 32 scale-pattern camouflage pattern, 33 cross-pattern second camouflage pattern, S paper, S1 image print section, S2 latent image print section, L1 first straight line, L2 latent image line, L3 2nd straight line, D dot

JP 11-291609 A

Claims (11)

  A plurality of spaced apart latent image lines constituting an image pattern of the latent image are generated, and an image is synthesized with the latent image pattern formed by the plurality of latent image lines, and the latent image pattern is formed on a sheet. An image processing unit that generates a camouflage pattern that makes the latent image pattern inconspicuous in a front view in a printed state, and a color material image is formed for the latent image line and the camouflage pattern generated by the image processing unit, An image forming unit that attaches the color material amount adhering to the latent image line to a height at which the latent image appears, a transfer unit that transfers the color material image formed by the image forming unit to a sheet, and the image that has been transferred to the sheet An electrophotographic image forming apparatus having a fixing unit for fixing an unfixed color material image.   A plurality of spaced apart latent image lines constituting an image pattern of the latent image are generated, and an image is synthesized with the latent image pattern formed by the plurality of latent image lines, and the latent image pattern is formed on a sheet. An image processing unit that generates a camouflage pattern having a uniform pattern that makes the latent image pattern inconspicuous when viewed from the front in a printed state, and the latent image line and camouflage pattern generated by the image processing unit An image forming unit that forms a material image and attaches the color material amount adhering to the latent image line to a height at which the latent image appears; a transfer unit that transfers the color material image formed by the image forming unit to paper; An electrophotographic image forming apparatus having a fixing unit for fixing an unfixed color material image transferred to the paper.   A plurality of spaced apart latent image lines constituting an image pattern of the latent image are generated, and an image is synthesized with the latent image pattern formed by the plurality of latent image lines, and the latent image pattern is formed on a sheet. An image processing unit that generates a camouflage pattern that makes the latent image pattern inconspicuous in a front view in a printed state, and a color material image is formed for the latent image line and the camouflage pattern generated by the image processing unit, An image forming unit that attaches the color material amount adhering to the latent image line to a height at which the latent image appears, a transfer unit that transfers the color material image formed by the image forming unit to a sheet, and the image that has been transferred to the sheet The camouflage pattern includes a fixing unit that fixes an unfixed color material image, and the camouflage pattern includes a plurality of first straight lines and a plurality of second straight lines orthogonal to each other, and the intersection of the first straight lines and the second straight lines. The latent image line electrophotographic image forming apparatus to form a dot of a large size than the line width in the state in which the coloring material is fixed in the.   A plurality of spaced apart latent image lines constituting an image pattern of the latent image are generated, and an image is synthesized with the latent image pattern formed by the plurality of latent image lines, and the latent image pattern is formed on a sheet. An image processing unit that generates a camouflage pattern that makes the latent image pattern inconspicuous in a front view in a printed state, and a color material image is formed for the latent image line and the camouflage pattern generated by the image processing unit, An image forming unit that attaches the color material amount adhering to the latent image line to a height at which the latent image appears, a transfer unit that transfers the color material image formed by the image forming unit to a sheet, and the image that has been transferred to the sheet An electronic device comprising a fixing unit for fixing an unfixed color material image, wherein the camouflage pattern is composed of a plurality of lines arranged with regularity in a direction different from the formation direction of the latent image lines. The image forming apparatus of the true type.   5. The electrophotographic image forming apparatus according to claim 4, wherein the camouflage pattern is prepared so that a plurality of types of patterns having different regularities can be arbitrarily selected.   A first generation step of generating a plurality of spaced apart latent image lines constituting an image pattern of the latent image, and a sheet of the latent image pattern with respect to the latent image pattern formed by the plurality of latent image lines A second generation step of generating a camouflage pattern that makes the latent image pattern inconspicuous in a front view when printed on the image, and the latent image generated in the first generation step and the second generation step A color material image is formed with respect to the line and the camouflage pattern, and an image forming process for adhering the color material amount adhering to the latent image line to a height at which the latent image appears, and the color material image formed in the image forming process on the paper An electrophotographic image forming method comprising a transfer step of transferring and a fixing step of fixing an unfixed color material image transferred onto the paper.   A first generation step of generating a plurality of spaced apart latent image lines constituting an image pattern of the latent image, and a sheet of the latent image pattern with respect to the latent image pattern formed by the plurality of latent image lines A second generation step of generating a camouflage pattern having a uniform pattern that makes the latent image pattern inconspicuous in a front view in a state printed on the first generation step, the first generation step, and the second generation step Forming a color material image with respect to the latent image line and camouflage pattern generated in step 1, and forming the color material amount adhering to the latent image line to a height at which the latent image appears, and the image forming step. An electrophotographic image forming method comprising a transfer step of transferring a color material image onto a sheet and a fixing step of fixing an unfixed color material image transferred onto the sheet.   A first generation step of generating a plurality of spaced apart latent image lines constituting an image pattern of the latent image, and a sheet of the latent image pattern with respect to the latent image pattern formed by the plurality of latent image lines A second generation step of generating a camouflage pattern that makes the latent image pattern inconspicuous in a front view when printed on the image, and the latent image generated in the first generation step and the second generation step A color material image is formed with respect to the line and the camouflage pattern, and an image forming process for adhering the color material amount adhering to the latent image line to a height at which the latent image appears, and the color material image formed in the image forming process on the paper A transfer step of transferring and a fixing step of fixing the unfixed color material image transferred to the paper, wherein the camouflage pattern includes a plurality of first straight lines and a plurality of second straight lines orthogonal to each other. The first straight line and the image forming method of an electrophotographic system forming a dot of larger size than the line width in the state in which the coloring material is fixed intersection of the latent image line of the second straight line.   A first generation step of generating a plurality of spaced apart latent image lines constituting an image pattern of the latent image, and a sheet of the latent image pattern with respect to the latent image pattern formed by the plurality of latent image lines A second generation step of generating a camouflage pattern that makes the latent image pattern inconspicuous in a front view when printed on the image, and the latent image generated in the first generation step and the second generation step A color material image is formed with respect to the line and the camouflage pattern, and an image forming process for adhering the color material amount adhering to the latent image line to a height at which the latent image appears, and the color material image formed in the image forming process on the paper A transfer step for transferring, and a fixing step for fixing the unfixed color material image transferred to the paper. The camouflage pattern is arranged with regularity in a direction different from the formation direction of the latent image lines. The image forming method of an electrophotographic system constituted by a plurality of lines that are.   The electrophotographic image forming method according to claim 9, wherein the camouflage pattern is prepared so that a plurality of types of patterns having different regularities can be arbitrarily selected. 11. An image formed article in which a composite image of a latent image and a camouflage pattern is formed on a sheet by the image forming method according to claim 6.

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