Printed Materials

Abstract

To provide a printed matter allowing a location of a confidential information image to be easily spotted.SOLUTION: A printed matter has a print of a confidential information image 80 formed with an IR toner visible under a special condition such as photographing by an infrared camera 90. The printed matter has a print of an information image 81 formed with the IR toner having information related to a location of the confidential information image 80. A user grasps, from the information image 81 photographed by the infrared camera 90, that the confidential information image 80 is in a center of the printed matter, and moves a photographing spot of the infrared camera 90 to the center of the printed matter, so that a location of the confidential information image can be easily spotted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printing To things This is related to. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a printed matter on which a secret information image that is visible under special conditions is printed.

[0003] Patent Document 1 describes a printed matter having a QR code (registered trademark) formed with transparent infrared absorbing toner as a secret information image. The secret information can be read by reading the QR code with a reader that irradiates infrared light. Summary of the Invention [Problem to be solved by the invention]

[0004] However, since it is difficult to visually recognize the secret information image except under special conditions, there is a problem in that it is difficult to locate the position of the secret information image on the printed matter. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a method for determining the position of a secret information image in a printed matter on which a secret information image that is visible under special conditions is printed. Information that leads to Information image with The information image is a latent image that is visible under the condition that the secret information image is visible, and a plurality of the information images are arranged in a direction approaching the secret information image from a distance. It is characterized by the above. Effect of the Invention

[0006] According to the present invention, the position of a secret information image can be easily found. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing a printed matter according to the embodiment. [Diagram 2] FIG. 13 is a diagram showing a printout on which a conventional secret information image is formed. [Diagram 3] 1A and 1B are diagrams illustrating acquisition of a secret information image in the related art. [Figure 4] FIG. 13 is a diagram showing a first modified example of the printed matter of the embodiment. [Diagram 5] FIG. 11 is a diagram showing a second modified example of the printed matter of the embodiment. [Figure 6] 13 is a diagram showing an example in which an arrow image indicating the position of a secret information image is added to each character string in a printed matter according to a second modified example. [Figure 7] 7 is a diagram showing an example in which a character string indicating the content of the secret information in the secret information image is added to each character string in each position information image in the printed matter of FIG. 6. [Figure 8] 13 is a diagram showing an example in which straight lines extending radially from the secret information image as a center are added to each position information image in a printed matter of a second modified example. [Figure 9] 13 is a diagram showing an example of a printed matter according to a second modified example in which character strings and straight lines are extended in all directions from the secret information. [Figure 10] FIG. 13 is a diagram showing an example in which a gradation image is added to a position information image in a printed matter according to a second modified example. [Figure 11] FIG. 11 is a diagram showing a third modified example of the printed matter of the embodiment. [Figure 12] FIG. 11 is a diagram showing a fourth modified example of the printed matter of the embodiment. [Figure 13] FIG. 1 is an explanatory diagram showing the overall configuration of a printer. [Figure 14] 11 is a graph showing an example of the relationship between the number of sheets passed and the amount of refreshing. [Figure 15] 11A and 11B are diagrams showing an example of a position information image formed according to a refresh amount. [Figure 16] FIG. 13 is a flow diagram for setting location information images. [Figure 17] 13 is a printed matter showing an example in which a position information image and a secret information image are formed with visible toner. [Figure 18] 18A is an enlarged view of the first secret information image and its vicinity on the printed matter shown in FIG. 17, and FIG. 18B is an enlarged view of the second secret information image and its vicinity on the printed matter shown in FIG. [Figure 19]FIG. 13 is a functional block diagram for displaying a focus mark at a location corresponding to a confidential information image of a printed matter displayed on an image display unit of the camera. [Figure 20] 5A to 5C are diagrams showing an example of transition of an image display section of a camera. [Figure 21] FIG. 13 is a diagram showing another example of concealing a secret information image with a background image. [Figure 22] 22 is an enlarged view of the vicinity of the secret information image of the printed matter shown in FIG. 21. [Figure 23] FIG. 13 is a diagram showing an example of a printed matter on which a secret information image and a position information image are formed with general black toner. [Figure 24] FIG. 13 is a diagram showing an example of a printed matter having a secret information image formed with IR toner and a secret information image formed with black toner. [Diagram 25] 24 is a diagram showing an example in which the position information image in the printed matter shown in FIG. 23 is a code image. [Figure 26] FIG. 2 is a schematic diagram showing a state in which a background image 60 of Y, M, and C color toners is formed on a black toner image. [Figure 27] FIG. 2 is a schematic diagram showing a state in which a background image of a plurality of Y, M, and C color toners is formed on a black toner image. [Figure 28] FIG. 2 is a diagram showing an example of an image forming apparatus including a re-conveying path 220. [Figure 29] FIG. 2 is a functional block diagram of the information transmission system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a diagram showing a printed matter 300 according to this embodiment.

[0009] 1, the printed matter 300 of this embodiment is made up of a QR code (registered trademark) recording secret information, and a secret information image 80 that is difficult to see is formed in the center of a sheet of paper P. In addition, a plurality of position information images 81 indicating the positions of the secret information images are formed on the printed matter 300 of this embodiment. These position information images 81 are also difficult to see.

[0010] The secret information image 80 and the position information image 81 are formed of a special light reactive image forming material that absorbs light outside the visible light region, or emits or develops light in the visible light region by light outside the visible light region. Examples of the special light reactive image forming material include infrared light absorbing toner that is transparent and absorbs infrared light, transparent fluorescent toner that fluoresces when exposed to ultraviolet light, infrared light absorbing ink, and transparent fluorescent ink that fluoresces when exposed to ultraviolet light. This embodiment will be described using an example in which infrared light absorbing toner (hereinafter referred to as IR toner) is used.

[0011] FIG. 2 is a diagram showing a printout on which a conventional secret information image 80 is formed. Since the secret information image 80 is formed of IR toner having transparency, it is difficult to confirm with the naked eye where the secret information image 80 is formed on the paper P under visible light. The secret information image 80 can be visually recognized from an image captured by an infrared camera 90, which is an information acquisition device, and it is common to read the secret information by capturing an image of the secret information image 80 with the infrared camera 90. The infrared camera 90 that is commonly used has a spot size 90a of about 20 mm in diameter.

[0012] Therefore, when the secret information image 80 is formed on a part of a commonly used A4 size paper (210 mm×290 mm), for example, the user moves the infrared camera 90 as follows to find the secret information image 80. That is, the user moves the infrared camera 90 from the upper left of the paper to the left and right as shown by the broken line in FIG. 3 while looking at the captured image displayed on the image display unit of the infrared camera 90, and gradually moves it downward in the figure. In this way, the secret information image 80 is found. As a result, it takes time to find the secret information image 80 from the paper. In addition, when the entire paper is imaged by the infrared camera 90, the number of pixels constituting the secret information image 80 is small, and the secret information image 80 becomes a blurred image, so that the secret information image 80 cannot be recognized, and the secret information cannot be read from the secret information image.

[0013] In contrast, the printed matter 300 of this embodiment shown in FIG. 1 has position information images 81 indicating the position of the secret information image 80. These position information images 81 are character images consisting of a phrase indicating the position where the secret information image 80 is formed, such as "center". These position information images 81 are also formed of transparent infrared absorbing toner (IR toner) like the secret information image 80. Therefore, the position information image 81 is difficult to see with the naked eye, and by capturing an image of an arbitrary position on the paper surface using an infrared camera 90, the position information image 81 is displayed on the image display unit of the infrared camera 90 and becomes visible. In this way, by making the position information image 81 an image that is visible under the special condition of capturing an image with the infrared camera 90, it is possible to suppress the position information image 81 from being visible under normal visible light. This makes it possible to prevent the position information image 81 from impairing the design of the printed matter 300.

[0014] The user can understand from the wording "center" of the position information image 81 displayed on the image display unit of the infrared camera 90 that the secret information image 80 is in the center of the paper.

[0015] Based on the position information obtained from the position information image 81, the user moves the spot (photographing range) of the infrared camera 90 to the center of the paper, whereby the infrared camera 90 photographs the secret information image 80, and the secret information can be read from the secret information image. In this way, in the printed matter 300 of this embodiment, the secret information image 80 can be easily found from the position information image 81.

[0016] FIG. 4 is a diagram showing a first modified example of the printed matter 300 of the present embodiment. In FIG. 4, the position information image 81 is an arrow indicating the position of the secret information image 80. Even in the case of the printed matter 300 shown in FIG. 4, by moving the spot of the infrared camera 90 in the direction of the arrow of the location information image 81 shown in the image captured by the infrared camera 90, the hidden information image 80 can be easily found and the hidden information can be read.

[0017] FIG. 5 is a diagram showing a second modified example of the printed matter 300 of the present embodiment. The printed matter 300 shown in Fig. 5 has two secret information images 80a and 80b each consisting of a QR code formed with a transparent IR toner. The printed matter 300 also has a first position information image 81a indicating the position of the first secret information image 80a formed at the upper left of the paper surface, and a second position information image 81b indicating the position of the second secret information image 80b formed at the lower right of the paper surface. The first position information image 81a and the second position information image 81b are formed with a transparent IR toner.

[0018] The first position information image is composed of multiple character strings M1 in which multiple character images of "1 / 2" are arranged in a straight line, and these character strings M1 are arranged radially from the first secret information image 80a. The second position information image is composed of multiple character strings M2 in which multiple character images of "2 / 2" are arranged in a straight line, and these character strings M2 are arranged radially from the second secret information image 80b.

[0019] 5, it can be seen that there are two secret information images 80 from the character images "1 / 2" and "2 / 2" in the position information images 81a and 81b displayed on the image display unit of the infrared camera 90. This makes it possible to prevent forgetting to obtain secret information.

[0020] Moreover, the spot of the infrared camera 90 is moved in a direction in which the first character string M1 becomes denser based on the first position information image 81a displayed on the image display unit of the infrared camera 90. This allows the infrared camera 90 to capture the first hidden information image 80a, and allows hidden information to be read from the first hidden information image 80a.

[0021] Furthermore, based on the second position information image 81b displayed on the image display unit of the infrared camera 90, the spot of the infrared camera 90 is moved in a direction in which the second character string M2 becomes denser. This allows the infrared camera 90 to capture the second hidden information image 80b, and allows hidden information to be read from the second hidden information image. Even in this second modified example, each hidden information image 80a, 80b can be easily found from each position information image 81.

[0022] 6 shows a printed matter 300 of the second modification in which an arrow image indicating the position of the secret information image is added to each character string. This makes it easy to understand the direction in which the spot of the infrared camera 90 should be moved from the arrow image of the character string displayed on the image display unit of the infrared camera 90, and makes it easier to find the secret information image.

[0023] As shown in Fig. 7, each character string in each of the position information images 81a and 81b may have a character string indicating the content of the secret information of the secret information image. In Fig. 7, URL information is recorded as secret information in the first secret information image 80a, and a PASS code for accessing the website of the URL information is recorded as secret information in the second secret information image 80b. The first position information image 81a has a character image of "URL" in a character string M1 as information indicating the content of the secret information. On the other hand, the second position information image 81b has a character image of "PASS" in a character string M2 as information indicating the content of the secret information.

[0024] FIG. 8 shows a printed matter 300 of the second modified example, in which straight lines F1 and F2 radially extending from the secret information image as the center are added to each of the position information images 81a and 81b. In the printed matter 300 shown in Fig. 8, the straight line F1 of the first position information image 81a is a solid line, and the straight line F2 of the second position information image 81b is a dashed line. Furthermore, in the printed matter 300 shown in Fig. 8, the image density of the character strings M1 and M2 becomes lighter as they move away from the secret information image.

[0025] 8, the spot of the infrared camera 90 is moved in a direction in which the straight lines F1 become dense and the first character string M1 becomes thicker. This allows the infrared camera 90 to capture a first secret information image 80a, and the secret information can be read from the first secret information image 80a. In addition, by moving the spot of the infrared camera 90 in a direction in which the straight lines F2 become dense and the second character string M2 become thicker, the infrared camera 90 can capture a second secret information image 80b, and the secret information can be read from the second secret information image 80b.

[0026] FIG. 9 shows a printed matter 300 of the second modified example in which character strings and straight lines are extended in all directions from the secret information. 9, the straight line F1 of the first position information image 81a is a thick line, and the straight line F2 of the second position information image 81b is a double line. Furthermore, in the printed matter 300 shown in FIG 9, the image density of the character strings M1, M2 and the straight lines F1, F2 becomes lighter as they move away from the secret information image.

[0027] 9, by moving the spot of the infrared camera 90 in a direction in which the first character string M1 and the straight line F1 become darker, the infrared camera 90 can capture a first secret information image 80a, and the secret information can be read from the first secret information image 80a. Also, by moving the spot of the infrared camera 90 in a direction in which the second character string M2 and the straight line F2 become darker, the infrared camera 90 can capture a second secret information image 80b, and the secret information can be read from the second secret information image 80b.

[0028] FIG. 10 shows a printed matter 300 of the second modified example in which gradation images G1 and G2 are added to position information images 81a and 81b. The gradation images G1 and G2 are circles that become thinner as they move away from the secret information image. Also in FIG. 10, the image density of each of the character strings M1 and M2 becomes thinner as they move away from the secret information image.

[0029] 10, the spot of the infrared camera 90 is moved in a direction in which the first character string M1 and the gradation image G1 displayed on the infrared camera 90 become darker. This allows the infrared camera 90 to capture a first hidden information image 80a, and the hidden information can be read from the first hidden information image 80a. In addition, by moving the spot of the infrared camera 90 in a direction in which the second character string M2 and the gradation image G2 become darker, the infrared camera 90 can capture a second hidden information image 80b, and the hidden information can be read from the second hidden information image 80b.

[0030] FIG. 11 is a diagram showing a third modified example of the printed matter 300 of this embodiment. The position information image of the printed matter 300 of the third modified example is a character image including the number of secret information images, the positions of the secret information images, and the reading order of the secret information images. From the position information image 81 displayed on the image display unit of the infrared camera 90, the user can understand that there are three secret information images, that the secret information images are located at the top left, center, and bottom left of the paper, and that the reading order is top left, center, bottom left.

[0031] The size of the QR code needs to be increased according to the amount of information it contains. If the size is too large, it becomes difficult to read with the infrared camera 90. Therefore, when the amount of information is large, it may be necessary to divide the QR code into multiple QR codes and read the QR codes in a specific order to obtain the desired information.

[0032] As shown in FIG. 11, by having information on the order in which the secret information images are read, in addition to the position information of the secret information and the number of pieces of secret information as the position information image, the secret information images can be read in a predetermined order, and accurate secret information can be obtained from multiple secret information images.

[0033] Furthermore, imparting an order to the reading of a plurality of secret information images in this manner has the advantage of improving confidentiality in addition to increasing the amount of information as described above.

[0034] FIG. 12 is a diagram showing a fourth modified example of the printed matter 300 of the present embodiment. This fourth modified example has a plurality of secret information images and a number information image 82 relating to the number of secret information images. FIG. 12(a) shows a case where there are two hidden information images 80a and 80b, and FIG. 12(b) shows a case where there are three hidden information images 80a and 80b. The quantity information image 82 is a 6 to 12 point number made of transparent IR toner and is arranged at equal intervals across the entire surface of the paper.

[0035] According to the fourth modification, the number of the secret information images 80 can be known from the number of the number information image 82 displayed on the monitor of the infrared camera 90. This makes it possible to prevent forgetting to obtain secret information.

[0036] Next, an example of an image forming apparatus capable of printing a printout 300 including a secret information image 80 and a position information image 81 made of transparent IR toner will be described. The image forming device is not particularly limited as long as it forms the secret information image 80 and the position information image 81 on paper using IR toner that forms the secret information image 80 and the position information image 81. Therefore, the image forming device may be a single copy machine or facsimile machine other than a printer, or a multifunction machine having at least two functions of a printer, a copy machine, a facsimile machine, and a scanner.

[0037] In the following description, the toner symbols for each component are "Y" for yellow toner (Y toner), "M" for magenta toner (M toner), and "C" for cyan toner (C toner).

[0038] First, the overall configuration and operation of the image forming apparatus will be described. FIG. 13 is an explanatory diagram showing the overall configuration of a printer 200 which is an image forming apparatus. The printer 200 of this embodiment is mainly composed of an image forming unit 1, a transfer unit 2, a recording medium supply unit 3, a fixing unit 4, a recording medium discharge unit 5, a control unit 30, and an image formation control unit 40.

[0039] The image forming section 1 is provided with four process units 6Y, 6M, 6C, and 6IR as imaging units. Each process unit 6Y, 6M, 6C, and 6IR has the same configuration except that the type of toner used is different. In this embodiment, a process unit using black (K) toner is not provided, so color images and monochrome images are formed using only Y, M, and C color toners. A K process unit may be added, but in that case, there is a disadvantage that the device becomes larger.

[0040] Also, the IR process unit 6IR may be configured to be detachable, and a K process unit may be installed instead of the IR process unit. In this case, when forming an image without using IR toner, by installing the K process unit, a color image or a monochrome image can be formed using the Y, M, and C color toners and the K toner.

[0041] In addition, the image forming apparatus may have all process units detachable and interchangeable in position, in which case the positional relationship between the IR toner image and each color toner image on the recording medium (positional relationship in the toner image stacking direction) can be appropriately interchanged by interchanging the position of the IR process unit.

[0042] In this embodiment, each of the process units 6Y, 6M, 6C, and 6IR includes a photoconductor 7 as a latent image carrier, a photoconductor 7 as a latent image carrier that carries a latent image, and a charging roller 8 as a charging means for charging the surface of the photoconductor 7. Each of the process units 6Y, 6M, 6C, and 6IR also includes a developing device 9 as a developing means for developing the latent image on the photoconductor 7, and a photoconductor cleaning device 10 as a latent image carrier cleaning means for cleaning the surface of the photoconductor 7. At a position facing each of the photoconductors 7, an exposure device 11 is provided as a latent image forming means for forming a latent image on the surface of the photoconductor 7. In this embodiment, the exposure device 11 is an LED unit, but may be a laser beam scanning type using a laser diode.

[0043] The transfer unit 2 includes an endless intermediate transfer belt 12 serving as an intermediate transfer body onto which the toner image on the photoreceptor 7 is transferred, and a plurality of primary transfer rollers 13 serving as primary transfer means for primarily transferring the image on the photoreceptor 7 onto the intermediate transfer belt 12. The transfer unit 2 also includes a secondary transfer roller 14 serving as secondary transfer means for secondarily transferring the toner image transferred onto the intermediate transfer belt 12 onto a recording medium, and a belt cleaning device 17 serving as intermediate transfer body cleaning means for cleaning the surface (outer circumferential surface) of the intermediate transfer belt 12.

[0044] The intermediate transfer belt 12 is stretched around a drive roller 15 and a driven roller 16, and travels (rotates) as the drive roller 15 rotates. Each primary transfer roller 13 is disposed so as to press the intermediate transfer belt 12 against each photoconductor 7. As a result, a primary transfer nip is formed at the contact point between the intermediate transfer belt 12 and each photoconductor 7, where an image on each photoconductor 7 is transferred to the intermediate transfer belt 12. Meanwhile, the secondary transfer roller 14 is disposed so as to contact a portion of the intermediate transfer belt 12 wound around the drive roller 15. At the contact point between the secondary transfer roller 14 and the intermediate transfer belt 12, a secondary transfer nip is formed at the contact point between the intermediate transfer belt 12 and each photoconductor 7, where an image on the intermediate transfer belt 12 is transferred to a recording medium.

[0045] The recording medium supply unit 3 has a paper feed cassette 18 as a recording medium storage unit, a paper feed roller 19 as a recording medium feeding means, and a timing roller 20 as a recording medium transport means. The paper feed cassette 18 stores paper P as a recording medium. The paper feed roller 19 feeds paper P from the paper feed cassette 18. The timing roller 20 transports the paper P fed by the paper feed roller 19 to the secondary transfer nip at a predetermined timing. The recording medium may be an OHP sheet, an OHP film, a cloth, etc., in addition to paper. Furthermore, the paper includes, in addition to plain paper, cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), textured paper such as Japanese paper, tracing paper, etc.

[0046] The fixing section 4 is provided with a fixing device 21 as a fixing means for fixing an image onto the paper P. The fixing device 21 is mainly composed of a fixing roller 22 as a fixing member that is heated by a heat source such as a heater, and a pressure roller 23 as a pressure member that comes into contact with the fixing roller 22 with a predetermined pressure to form a fixing nip.

[0047] The recording medium discharge section 5 is provided with a paper discharge roller 24 as a recording medium discharge means for discharging the paper P sent from the fixing device 21 outside the device, and a paper discharge tray 25 as a recording medium mounting section for placing the paper P discharged by the paper discharge roller 24.

[0048] The control unit 30 performs image processing on input image information from a reading device (scanner), a personal computer, etc., and also controls the printer 200 as a whole. In addition, the image forming control unit 40, under the control of the control unit 30, controls the image forming operations in each part of the printer 200 (the image forming unit 1, the transfer unit 2, the recording medium supply unit 3, the fixing unit 4, the recording medium discharge unit 5, etc.).

[0049] In addition to the above-mentioned components, the printer 200 of this embodiment is equipped with a plurality of toner cartridges 26 as powder containers that contain toner, which is a powder used in image formation. Each toner cartridge 26 contains toner of the same color as the toner in the corresponding developing device 9, and when the toner in the developing device 9 falls below a predetermined amount, toner is replenished from the toner cartridge 26. Furthermore, the printer 200 is equipped with a waste toner container 27 as a powder container separate from the toner cartridges 26. The waste toner container 27 contains waste toner collected by the belt cleaning device 17 or the photoconductor cleaning device 10.

[0050] 13, the printer 200 of this embodiment includes a cover member 101 for opening and closing the upper portion of the device body (image forming device body) 100. The cover member 101 is rotatable up and down about a rotation shaft 103 provided in the device body 100. In addition, a container holding member 102 that detachably holds four toner cartridges 26 is disposed below the cover member 101. The container holding member 102 is rotatable up and down about another rotation shaft 104 provided in the device body 100.

[0051] In this embodiment, the IR process unit 6IR is disposed on the most downstream side in the running direction of the intermediate transfer belt 12, and the color process units 6Y, 6M, and 6C are disposed upstream of it. This is because the IR toner image made of IR toner is formed on the recording medium closer to the recording medium than the color toner images made of Y, M, and C color toners. In other words, on the intermediate transfer belt 12, the Y toner image, the M toner image, the C toner image, and the IR toner image are stacked in this order from the belt side, but on the recording medium after secondary transfer, the IR toner image, the C toner image, the M toner image, and the Y toner image are stacked in this order from the recording medium side.

[0052] By forming the IR toner image closer to the recording medium than the color toner image, the IR toner image is hidden by the color toner image, reducing its visibility, making it easier to ensure the secrecy of the image formed by the IR toner image. However, it is possible to appropriately set where the IR process unit 6IR is disposed relative to the color process units 6Y, 6M, and 6C. Also, as described above, if the mounting positions of the process units 6Y, 6M, 6C, and 6IR are configured to be interchangeable with each other, the position of the IR process unit can be freely interchanged.

[0053] Next, the basic operation of the printer 200 of this embodiment will be described. When the image forming operation starts, each photoconductor 7 is rotated and the surface of each photoconductor 7 is uniformly charged to a predetermined polarity by the charging roller 8. Next, based on input image information from a reading device (scanner), a personal computer, etc., an exposure device 11 irradiates the charged surface of each photoconductor 7 with laser light to form a latent image (electrostatic latent image).

[0054] The latent image formed on each photoconductor 7 is a latent image based on monochrome image information obtained by decomposing a desired full-color image into color information of Y, M, and C. In more detail, a color conversion separation table is used to convert and separate the color information (RGB, YCM, etc.) of the input image information into color information (YMC) for the printer 200. This color conversion separation table converts the input image information into color information of Y, M, and C, and generates decomposed monochrome image information. Each exposure device 11 for Y, M, and C forms a latent image of each color on the respective photoconductor 7 based on the image information of each color of Y, M, and C.

[0055] In this embodiment, the input image information specifies an image to be an IR image by an application on the personal computer, and IR image information is generated from the specified information. The image to be an IR image may also be specified by a printer driver on the personal computer. The IR exposure device 11 forms an IR latent image on the photoconductor 7 of the IR process unit 6IR based on the IR image information.

[0056] Toner is supplied from the respective developing devices 9 to the latent images of Y, C, M, and IR formed on the photoconductor 7, and the latent images are developed into toner images of Y, C, M, and IR. The toner images on the photoconductors 7 are transferred in sequence onto the intermediate transfer belt 12, which travels around the photoconductor 7, superimposed on one another. In detail, when the toner images on the photoconductors 7 reach the position of the primary transfer nip, the toner images on the photoconductors 7 are transferred in sequence onto the intermediate transfer belt 12 by a transfer electric field formed by applying a predetermined voltage to the primary transfer roller 13. In this way, a full-color toner image (visible image) made of Y, C, and M toners and an IR toner image (invisible image) made of IR toners are formed on the surface of the intermediate transfer belt 12. The toner on each photoconductor 7 that has not been transferred to the intermediate transfer belt 12 is removed by the photoconductor cleaning device 10.

[0057] Furthermore, when the image forming operation is started, the paper feed roller 19 rotates and feeds the paper P from the paper feed cassette 18. The transport of the fed paper P is temporarily stopped by the timing roller 20. Thereafter, the rotational drive of the timing roller 20 is started at a predetermined timing, and the paper P is transported to the secondary transfer nip in time with the toner image on the intermediate transfer belt 12 reaching the secondary transfer nip.

[0058] When the paper P is transported to the secondary transfer nip, a predetermined voltage is applied to the secondary transfer roller 14, and a transfer electric field is formed in the secondary transfer nip. The toner images on the intermediate transfer belt 12 are transferred all at once to the paper P by the transfer electric field formed in the secondary transfer nip. At this time, the toner remaining on the intermediate transfer belt 12 is removed by the belt cleaning device 17.

[0059] Thereafter, the paper P is transported to a fixing device 21, where the toner image is heated and pressed by a fixing roller 22 and a pressure roller 23, thereby being fixed to the paper P. Then, the paper P is discharged outside the device by a paper discharge roller 24, and placed on a paper discharge tray 25.

[0060] The above description is of the image formation operation when forming a full-color image, but it is also possible to form an image using any one of the four process units 6Y, 6M, 6C, and 6IR, or to form an image using any two or three of the process units.

[0061] By creating the secret information image 80 and the position information image 81 or the number information image 82 using application software on the personal computer and specifying these as the IR image, the printout 300 shown in FIGS. 1 to 12 can be obtained.

[0062] Also, the printer 200 may automatically create the position information image 81 or the number information image 82 to obtain the printed matter 300 shown in Figs. 1 to 12. Specifically, when the concealed information image 80 is designated as an IR image by a printer driver on the personal computer, a selection screen for selecting whether or not to create the position information image 81, etc. is displayed on the screen of the personal computer. When the user selects to create the position information image 81, etc., the user selects from, for example, a plurality of position information image patterns or number information image patterns shown in Figs. 1 to 12. The concealed information image 80 designated as an IR image and the position information image 81 or number information image 82 selected by the user are transmitted to the printer 200 as IR image information.

[0063] The PC side specifies the position of the specified secret information image 80, automatically generates a position information image 81 based on the specified secret information image 80 and the position information image pattern specified by the user, and transmits the generated position information image to the printer 200 as IR image data. Alternatively, the printer 200 side automatically generates a position information image based on the position information image pattern information specified by the user received from the PC and the position information of the secret information image 80.

[0064] Furthermore, if the toner consumption in the developing device is low, the amount of old toner that remains in the developing device and deteriorates increases. If the amount of old toner increases, the image becomes uneven and prone to insect holes, resulting in a decrease in image quality. Therefore, in order to prevent such a decrease in image quality, the printer 200 performs refresh control to eject old toner from the developing device 9 at a predetermined timing and replace it with new toner to keep the toner fresh.

[0065] FIG. 14 is a graph showing an example of the relationship between the number of sheets passed and the amount of refreshing. The refresh amount, which is the amount of toner discharged from the developing device 9 necessary to refresh the toner in the developing device 9, is determined by the toner consumption of the developing device 9. The toner consumption amount can generally be calculated from the image area per unit travel distance of the developing device, but is not limited to this as long as it represents the toner consumption amount. When the calculated toner consumption amount is below a certain threshold, the refresh amount (image area required for toner refresh) is calculated. This calculated refresh amount is accumulated. On the other hand, when the toner consumption amount is above a certain threshold, the refresh consumption amount is calculated and subtracted from the accumulated refresh amount. Then, when the accumulated refresh amount reaches the discharge execution threshold H, refresh control is executed and the refresh amount becomes 0.

[0066] The threshold value for counting up the refresh amount is usually a consumption amount equivalent to 2 to 3% of the image area, but since the optimal threshold value differs depending on the imaging system and toner, it is desirable to control it at an optimal value depending on the system.

[0067] When the accumulated refresh amount reaches the discharge execution threshold H, refresh control is executed. When refresh control is executed, a latent image pattern with a width equivalent to the accumulated refresh amount is formed on the surface of the photoconductor 7. The toner in the developing device 9 is made to adhere to this latent image pattern and developed, so that the old toner in the developing device is discharged and the toner in the developing device is refreshed. This developed image is removed by the photoconductor cleaning device 10 and becomes waste toner.

[0068] Generally, IR toner is used less frequently and in smaller amounts, so deteriorated old toner tends to accumulate in the developing device 9IR. Therefore, the above-mentioned refresh control is likely to be triggered for IR toner, and it often becomes waste toner.

[0069] In order to reduce the amount of IR toner that becomes waste toner by such refresh control, the position information image 81 to be formed on the paper may be determined according to the refresh amount of the IR toner. This allows for effective use of old IR toner that would otherwise become waste toner. In this case, for example, if the user selects to create a position information image 81 or the like from the printer driver, the printer creates a position information image 81 according to the refresh amount of the IR toner.

[0070] For example, when forming an image including a secret information image, the accumulated refresh amount is checked. When the accumulated refresh amount is less than a specified value, there is almost no old toner in the developing device 9IR. Therefore, as shown in FIG. 15(b), the printer 200 forms a position information image 81 consisting of an arrow image with only an edge, thereby suppressing unnecessary IR toner consumption. On the other hand, when the accumulated refresh amount is equal to or greater than the specified value, the printer 200 forms a position information image 81 consisting of a solid arrow image, as shown in FIG. 15(a). This increases the amount of IR toner consumed, allowing old toner in the developing device to be expelled.

[0071] Furthermore, the printer 200 may change the image density of the position information image 81 consisting of an arrow image according to the accumulated refresh amount, and adjust the IR toner consumption amount. The image density of the position information image 81 can be adjusted by changing at least one of the image forming conditions, the development bias and the LD power (exposure amount) of the exposure device that irradiates the photoconductor 7IR. When the accumulated refresh amount is large, the image density is made thicker to increase the IR toner consumption amount so that old toner in the development device is expelled. On the other hand, when the accumulated refresh amount is small, the image density is made thin to suppress the IR toner consumption.

[0072] Also, the IR toner consumption amount may be adjusted according to the accumulated refresh amount by changing the number of arrow images, changing the thickness of the arrows, or changing the position information image to the character image shown in Fig. 1. Also, when there are multiple secret information images, any of the position information images shown in Figs. 5 to 11 may be adopted according to the refresh amount to adjust the IR toner consumption amount.

[0073] The printer 200 may also create the position information image 81 based on the amount of refresh after the job is completed. The amount of refresh after the job is completed is calculated from the amount of refresh at the start of the print job, the travel distance of the developing unit required for one job, and the image area of ​​the secret information image 80.

[0074] 16 is a setting flow diagram of the position information image 81. The following Table 1 shows a setting example of the position information image 81 in the following case. That is, when the refresh threshold is 25 [cm 2 / m], refresh execution threshold 50 [cm 2 ], the cumulative refresh amount before the job is 20 [cm 2 ], when outputting 10 sheets of confidential information images with an image area of ​​3% (A4).

[0075] [Table 1]

[0076] First, when the control unit 30 of the printer 200 receives a print instruction, it acquires the number of prints and the image area of ​​the secret information image 80 as job information (S1). In the example of Table 1 above, the number of prints: 10 and the image area ratio of the secret information image 80: 3% (A4) are acquired from the job information, and the image area of ​​the secret information image 80: 2 [cm 2 ] is calculated.

[0077] Next, the control unit 30 calculates the cumulative refresh amount after the print job is completed (S2). Specifically, the control unit 30 calculates the cumulative refresh amount stored in the memory of the device (in the example of Table 1, the cumulative refresh amount is 20 [cm 2 ]) is read.

[0078] Next, the amount of refresh added after this print job is calculated. The amount of refresh added is a value calculated from the travel distance of the developing unit in this print job and the refresh threshold value minus the image area of ​​the secret information image 80 in this print job. The travel distance of the developing unit is calculated by multiplying the travel distance of the developing device per sheet, which is stored in advance in memory, by the number of printed sheets. The calculated amount of refresh added is added to the cumulative amount of refresh stored in the memory of the device, thereby calculating the cumulative amount of refresh after the print job is completed.

[0079] In the example of Table 1, the travel distance of the developing unit in the print job is 4 [m]. The travel distance of the developing unit is calculated by multiplying the travel distance of the developing device per sheet, which is stored in advance in the memory, by the number of printed sheets. In the example of Table 1, the refresh threshold is 25 [cm 2 / m], and the cumulative image area of ​​the secret information image 80 is 20 [cm 2 ](=2[cm 2 ]×10). Therefore, in the example shown in Table 1, the accumulated refresh amount after the print job is completed is 80 [cm 2 ](=4[m]×25[cm 2 / m]-(2[cm2 ]×10). The cumulative refresh amount before the print job is 20[cm 2 ], so the cumulative refresh amount after the print job is completed is 100 [cm 2 ](=20[cm 2 ]+80[cm 2 ]).

[0080] Next, the control unit 30 divides the calculated cumulative refresh amount after the print job by the number of printed sheets to calculate the image area per sheet of the position information image (S3). In the example of Table 1, the image area per sheet of the position information image is 10 [cm 2 ](=100[cm 2 ] / 10). The image area per location information image is 10 [cm 2 ], the cumulative refresh amount at the end of the print job becomes 0, and the IR toner in the developing device 9IR is refreshed.

[0081] Next, the control unit 30 determines the position information image pattern that is closest to the calculated image area per sheet from a plurality of position information image patterns that are stored in advance in the memory (S4).

[0082] Next, the control unit 30 adjusts the image density of the determined position information image (S5). For example, if the image area of ​​the position information image pattern closest to the calculated image area per sheet is 20 cm 2 ], and the image area of ​​each calculated location information image is 10[cm 2 When the toner consumption is halved, the image forming conditions (development bias and LD power) are determined so that the image density is such that the toner consumption is halved.

[0083] In the above, the control unit 30 adjusts both the position information image pattern and the image density based on the calculated image area per sheet, but it may also be configured to adjust only the position information image pattern or only the image density.

[0084] In the above, the position information image pattern is selected and the image density is adjusted so that the cumulative refresh amount after the job is completed is 0, but it is sufficient to set the cumulative refresh amount after the job is completed to be equal to or greater than 0 and less than the discharge execution threshold H. If the cumulative refresh amount after the job is completed to be less than 0, not only the old IR toner in the developing device but also the new IR toner replenished to the developing device will be consumed, which is undesirable because toner will be wasted. On the other hand, if the cumulative refresh amount after the job is completed to be equal to or greater than the discharge execution threshold H, refresh control will be executed after the job is completed, which is undesirable.

[0085] Furthermore, in the above description, the position information image 81 and the secret information image are formed with transparent IR toner, but the position information image 81 and the secret information image may be formed with visible toner.

[0086] FIG. 17 is a printed matter 300 showing an example in which a positional information image 81 and secret information images 80a and 80b are formed with visible toner, FIG. 18(a) is an enlarged view of the vicinity of the first secret information image, and FIG. 18(b) is an enlarged view of the vicinity of the second secret information image. 17, the position information image 81 is a QR code formed with visible toner and is formed in the upper right corner of the drawing. Also, each of the secret information images 80a and 80b is a latent image hidden in the background image 180.

[0087] The background image 180 is formed of a visible light toner that does not absorb infrared light. The secret information images 80a and 80b are formed of an IR toner that has the same color as the background image 180 under visible light and absorbs infrared light. By photographing these secret information images 80a and 80b with an infrared camera 90, the secret information images 80a and 80b appear in a color different from that of the background image 180, and can be distinguished from the background image 180. This makes it possible to obtain secret information from the secret information images 80a and 80b. In this example, the secret information of "ABC" is obtained from the first secret information image 80a, and the secret information of "123" is obtained from the second secret information image 80b.

[0088] In the example shown in Fig. 17, the secret information image is divided into multiple parts in consideration of the design, but the secret information image may not be divided if the design is not impaired. Also, depending on the image, such as a latent image in which character strings are spaced apart, distributing the secret information image into multiple parts may reduce the area of ​​the background image 180. In such a case, distributing the secret information image is preferable because it reduces toner consumption.

[0089] As an image forming apparatus capable of printing the printed matter 300 shown in FIG. 17 and FIG. 18, the image forming apparatus shown in FIG. 13 can be used, except that the IR toner of the process unit 6IR is a colored IR toner. In this case, as described above, the K color is formed by overlapping the Y, M, and C color toners. When the IR toner is K color, the background image 180 is formed by overlapping the Y, M, and C color toners, so a large amount of toner is consumed to form the background image 180 for hiding the secret information image 80. In addition, if the area of ​​the background image 180 is large, there is a risk of the fixation property being deteriorated. Therefore, when the secret information image 80 is used frequently, it is preferable to use any one of Y, M, and C colors as the IR toner. This allows the background image to be formed using only any one of Y, M, and C toners, thereby suppressing toner consumption and deterioration of fixation property.

[0090] On the other hand, black toner generally has carbon that absorbs infrared rays and can directly play the role of IR toner, so the secret information image 80 can be formed using the same configuration and toner as a general image forming apparatus, which is a great advantage. Therefore, when the secret information image 80 is rarely printed, it is preferable to be able to form the secret information image 80 using black toner, even if there is a disadvantage that a large amount of toner is consumed to form the background image 180. In addition, as described later, it is also possible to prevent the fixing property from deteriorating. Note that an embodiment in which the secret information image is generally formed using black toner will be described later.

[0091] In Figures 17 and 18, the secret information image is a character string, and this character string is the secret information, but as in Figures 1 to 12, the secret information image may be a code image such as a QR code, and the secret information may be included in this code image.

[0092] By capturing an image of a position information image 81 consisting of a QR code formed in the upper right part of Fig. 17 with a camera, information such as the position information, number information, and reading order of the secret information image is read. The read information is displayed, for example, on the image display unit of the camera. Then, the user switches the camera to infrared mode and moves the camera spot to the position of the secret information image based on the information displayed on the image display unit of the camera, whereby the secret information image is captured and the secret information can be obtained.

[0093] Also, a focus mark may be displayed at a location corresponding to the secret information image of the printed matter 300 displayed on the image display unit of the camera 90 based on the position information acquired from the position information image 81. Such an embodiment will be described below with reference to Figs. 19 and 20.

[0094] FIG. 19 is a functional block diagram showing how to display a focus mark at a location corresponding to the secret information image of the printed matter 300 displayed on the image display unit 97 of the camera 90. As shown in FIG. The camera 90 as an information acquisition device includes an optical system 91, an imaging section 92, an image processing section 93, an image storage section 94, an image analysis section 95, a mark generating section 96, and an image storage section 94.

[0095] The optical system 91 has a focus lens, a shutter mechanism, etc. The imaging unit 92 has an imaging element sensitive to visible light and an imaging element sensitive to infrared light, and is capable of switching between the imaging elements to be used for imaging by user operation or the like.

[0096] The image processing unit 93 performs image processing such as AD conversion and shading correction on the image captured by the imaging element. The image processed by the image processing unit 93 is transferred to the image display unit 97 and displayed in real time on the image display unit 97. In addition, an image captured when the user presses the shutter button of the camera is processed by the image processing unit 93, and then transferred to the image storage unit 94 and stored in the image storage unit 94.

[0097] The image analysis unit 95 analyzes the position information image 81 and the secret information image 80 to extract information. The image analysis unit 95 extracts position information, number information, reading order information, etc. of the secret information image 80 from the position information image 81. Here, the position information of the secret information image 80 acquired from the position information image 81 is the distance from the position information image 81 to the secret information image and the distance from the edge of the paper to the secret information image.

[0098] The mark generating unit 96 displays a focus mark at the position of the secret information image of the captured image displayed in real time on the image display unit 97 based on the position information, number information, and reading order information of the secret information image 80 extracted by the image analyzing unit 95. For example, when the position information of the secret information image 80 is the distance from the position information image 81 to the secret information image 80, the position of the position information image 81 is specified by image analysis of the image obtained by capturing the entire printed matter 300. Then, the mark generating unit 96 displays a focus mark based on the distance from the position information image 81 to the secret information image 80. Also, when the position information of the secret information image 80 is the distance from the edge of the paper, the image obtained by capturing the entire printed matter 300 is image analysis to specify the edge position of the paper. Then, the mark generating unit 96 displays a focus mark based on the distance from the edge of the paper. Note that this is not limited to this, and a focus mark may be displayed at the position of the secret information image 80 based on the position information of the secret information image 80 by another existing method. The image display unit 97 may be any device capable of displaying images, such as a liquid crystal panel or a touch panel.

[0099] FIG. 20 is a diagram showing an example of the transition of the image display section 97 of the camera. The camera 90 has a secret information reading mode, and the user executes the secret information reading mode when reading the secret information on the printed matter 300. When the secret information reading mode is executed, first, a command to read the position information image 81 is displayed on the image display unit 97.

[0100] The user brings the camera 90 close to the position information image 81 of the printed matter 300 and captures a sufficiently large position information image 81. Then, the image analysis unit 95 recognizes the position information image 81 consisting of a QR code, and obtains information such as the position information of the secret information image 80, the number of secret information images, and the reading order of the secret information images from the position information image.

[0101] When the position information of the secret information image 80 and the like are acquired from the position information image 81, the camera 90 switches to the infrared mode and instructs the user to display the entire printed matter 300 on the image display unit 97.

[0102] As shown in Fig. 20(a), when the entire printed matter 300 is displayed on the image display unit 97, the mark generating unit 96 displays a focus mark M for the first secret information image 80a from which secret information is acquired first as follows: That is, the mark generating unit 96 displays a focus mark M for the first secret information image 80a based on the image in which the entire printed matter 300 is photographed, the position information of the secret information image, and the reading order of the secret information image (see Fig. 20(b)).

[0103] Since the number of pixels constituting the first secret information image 80a is small and the resolution is low from the image in which the entire print 300 is displayed, the secret information cannot be obtained from the first secret information image 80a. Therefore, as shown in Fig. 20(b), the camera 90 displays on the image display section 97 an indication that the first secret information image 80a surrounded by the focus mark M will be zoomed in.

[0104] Based on the instruction displayed on the image display unit 97, the user moves the camera while watching the screen of the image display unit 97 so that the focus mark M is located at the center of the screen, and zooms in on the first secret information image 80a. Then, as shown in Fig. 20(c), when the first secret information image 80a of a sufficient size is photographed, the image analysis unit 95 recognizes the first secret information image 80a (character string "ABC"), and the secret information of "ABC" is obtained.

[0105] Once the secret information is obtained from the first secret information image 80a, as shown in FIG. 20(d), the focus mark M disappears from the image display section 97, and a message is displayed indicating that the image display section 97 will zoom out so that the entire printed matter 300 is captured.

[0106] The user moves the camera 90 based on the instruction displayed on the image display section 97, and causes the image display section 97 to display the entire printed matter 300 again. When the entire printed matter 300 is displayed on the image display section 97, the mark generating section 96 specifies the position of the second secret information image 80b as follows. That is, based on the image in which the entire printed matter 300 is displayed and position information of the second secret information image 80b (the distance between the paper edge and the second secret information image, the distance between the position information image and the second secret information image, etc.), the position of the second secret information image 80b is specified. Then, the camera 90 displays a focus mark M at a position corresponding to the second secret information image 80b, as shown in FIG. 20(e).

[0107] Similarly to the first secret information image, the user moves the camera while viewing the screen of the image display unit 97 so that the focus mark M is positioned at the center of the screen, and zooms in on the second secret information image 80b. Then, as shown in Fig. 20(f), when the second secret information image 80b of a sufficient size is photographed, the image analysis unit 95 recognizes the second secret information image 80b, and the secret information "123" is obtained.

[0108] In this manner, when the secret information has been acquired from all the secret information images printed on the printed matter 300, the camera 90 displays the acquired secret information on the image display unit 97. In this example, the secret information of “ABC123” is displayed on the image display unit 97.

[0109] In this way, since the focus mark M is displayed at a position corresponding to the secret information image, the user can prevent losing sight of the secret information image and can easily find the secret information image. Also, according to the display of the image display section 97 of the camera 90, the secret information can be obtained in a specified order, and the correct secret information can be obtained from the secret information image divided into a plurality of parts.

[0110] It should be noted that a camera-equipped smartphone or the like may be used as the camera 90. In this case, the secret information of the printed matter 300 can be obtained by the above-mentioned method using application software installed on the camera-equipped smartphone.

[0111] Furthermore, if the camera is equipped with a zoom lens, for example, it may be configured so that when the focus mark is positioned at the center of the screen from the state shown in FIG. 20(b), it automatically zooms in to the secret information image.

[0112] Furthermore, when the printed matter 300 is small, the resolution of the camera 90 is high, and the resolution of the secret information image and the position information image is sufficiently high even from an image of the entire printed matter 300, the image analysis unit 95 can recognize the secret information image and the position information image from the image of the entire printed matter 300. In this case, the secret information and information regarding the order of the secret information may be obtained at once from the image of the entire printed matter 300.

[0113] Alternatively, the scanner may acquire position information, acquire secret information from the acquired position information, and display the secret information on the display unit of the scanner or a display unit of an external device such as a PC connected to the scanner. Specifically, the scanner as an information acquisition device first reads the entire printed matter 300, performs image analysis on the read image data, and acquires the position of the secret information image and the order of the secret information image from the position information image consisting of a QR code. Next, the scanner identifies multiple secret information images based on the acquired position information of the secret information images, and performs image analysis on the identified secret information images to acquire divided secret information. Then, the scanner combines the divided secret information into one piece based on the acquired information on the order of the secret information, and displays it on the display unit of the scanner or a display unit of an external device connected to the scanner.

[0114] FIG. 21 is a diagram showing another example in which the secret information image 80 is concealed by the background image 180, and FIG. 22 is an enlarged view of the vicinity of the secret information image 80. As shown in FIG. 21 and 22, the background image 180 and the secret information image 80 are made of the same visible toner, and the dither patterns of the background image 180 and the secret information image 80 are made different from each other. It is difficult to recognize the difference between the dither patterns with the naked eye, and the secret information image 80 becomes a latent image of the background image 180, and the secret information image 80 is concealed by the background image 180.

[0115] In the printed matter 300 shown in Fig. 21 and Fig. 22, by enlarging the vicinity of the secret information image 80 with a magnifying glass or the like, it is possible to distinguish the difference in dither pattern between the secret information image 80 and the background image 180, and it is possible to recognize the secret information image 80. In addition, in the case of a camera, by optically zooming in and photographing the vicinity of the secret information image 80, it is possible to distinguish the difference in dither pattern between the secret information image 80 and the background image 180, and it is possible to recognize the secret information image 80. In addition, in the case of a scanner, by increasing the set resolution, it is possible to distinguish the difference in dither pattern between the secret information image 80 and the background image 180, and it is possible to recognize the secret information image 80.

[0116] 21 and 22, it is difficult to identify the position of the secret information image with the naked eye, so a position information image 81 is formed on the printed matter 300. This makes it possible to easily find the position of the secret information image 80 from the position information acquired from the position information image 81, and to acquire secret information from the secret information image 80 by zooming in and photographing that location.

[0117] In the examples shown in Figs. 21 and 22, the position information image 81 consisting of a QR code may have resolution information in addition to the position information of the secret information image. This is because if the resolution of the camera is low, even if the camera is zoomed in and photographed, the dither patterns of the secret information image and the background image may not be distinguished from the photographed image. For this reason, by including the resolution information in the position information image, the camera automatically changes the resolution to a high resolution based on this resolution information. Alternatively, the user changes the set resolution based on the resolution information displayed on the image display unit of the camera. In this way, by setting the set resolution of the camera to a high resolution, the image photographed near the secret information image becomes fine, and the dither patterns of the secret information image and the background image can be well distinguished, and the secret information image can be distinguished from the photographed image.

[0118] When reading the printed matter 300 shown in Fig. 21 and Fig. 22 with a scanner to obtain secret information, first, the scanner reads the position information image consisting of a QR code to obtain the position of the secret information image and the information of the resolution to be set. Next, the scanner changes the set resolution to a high resolution based on the resolution information. This makes it possible to read the secret information image 80 and the background image 180 in a distinguishable manner.

[0119] Next, based on the position information of the secret information image, the scanner reads, at high resolution, the vicinity of the secret information image formation position of the printed matter 300. In this way, by reading only the vicinity of the secret information image formation position, the volume of image data can be reduced compared to the case where the entire printed matter 300 is read at high resolution.

[0120] The scanner then displays the read image data on the display unit of the scanner or on the display unit of an external device such as a PC, allowing the user to obtain confidential information from the image read by the scanner.

[0121] Also, the read image data may be analyzed to specify the secret information image 80, the image data may be processed so that the secret information image 80 is emphasized, and the processed data may be displayed on the display unit of the scanner or the display unit of an external device such as a PC. Also, if the external device connected to the scanner is a printer 200, the processed data may be printed out. This makes it possible to easily obtain secret information from the image read by the scanner.

[0122] Also, the read image data may be analyzed to identify the secret information image 80 to obtain the secret information, and the obtained secret information may be displayed on the display unit of the scanner or on the display unit of an external device such as a PC.

[0123] In the printed matter 300 shown in Figures 21 and 22, information can be concealed without using special toner such as IR toner, and the printed matter 300 shown in Figures 21 and 22 can be created with a general image forming device. When concealing information using IR toner, the concealed information cannot be obtained unless it is imaged with a device having an image sensor sensitive to infrared light, but the printed matter 300 shown in Figures 21 and 22 can obtain the concealed information with a general scanner or camera having only an image sensor sensitive to visible light. In addition, in the printed matter 300 shown in Figures 21 and 22, if the set resolution of the scanner is increased, the printed matter 300 having the concealed information can be copied, and if the set resolution of the scanner is decreased, the printed matter 300 can be copied as a normal image (an image in which the concealed information image is not reproduced).

[0124] 21 and 22, the secret information image 80 can be easily blended into a normal image by using a plurality of color toners, and the secret information image 80 can be made less noticeable than the printed matter 300 shown in FIGS. 17 and 18.

[0125] 20 and 21, a plurality of secret information images may be formed and the secret information may be divided into a plurality of pieces. The secret information image may be a code image such as a QR code so that the secret information is included in the code image.

[0126] Next, a printed matter on which a secret information image 80 and a position information image 81 are formed using a general black toner containing carbon that absorbs infrared rays will be described. As mentioned above, black toner generally differs from other color toners (yellow, magenta, cyan) in that it contains carbon that absorbs infrared rays, and can be read by an infrared camera. By using this characteristic, it is possible to form a secret information image that is usually invisible to the naked eye but can be read by an infrared camera.

[0127] FIG. 23 is a diagram showing an example of a printed matter 300 on which a secret information image 80 and a position information image are formed with general black toner. 23(b), the secret information image 80 and the position information image 81 formed with black toner are black, unlike IR toner. Therefore, in order to make them difficult to see, it is preferable that the secret information image 80 and the position information image 81 are formed as halftone images and light images.

[0128] The secret information image 80 and the position information image 81 formed with black toner as shown in Fig. 23(b) are covered with the background image 180 created with Y, M, and C color toners as shown in Fig. 23(a). As a result, as shown in Fig. 22(c), the secret information image 80 and the position information image 81 formed with black toner are hidden by the background image of Y, M, and C color toners, and the secret information image 80 and the position information image 81 become images that are difficult to view.

[0129] 23 is photographed by an infrared camera 90, which is an information acquisition device, a position information image 81 formed of black toner containing carbon that absorbs infrared rays is displayed and becomes visible on the image display section of the infrared camera 90. By moving the infrared camera along the arrow of this position information image 81 that has become visible, the hidden information image 80 can be easily found and the hidden information can be read.

[0130] FIG. 24 is a diagram showing an example of a printed matter 300 having a concealed information image formed with IR toner and a concealed information image formed with black toner. A first secret information image 80a shown in Fig. 24(b) and a first position information image 81a showing the position of the first secret information image 80a are formed with IR toner. A second secret information image 80b shown in Fig. 24(c) and a second position information image 81b showing the position of the second secret information image are formed with black toner. The second secret information image 80b and the second position information image 81b formed with black toner are covered with a background image formed with Y, M, and C color toners shown in Fig. 24(a) to obtain a printed matter 300 shown in Fig. 24(d).

[0131] The IR toner absorbs, for example, 800 [nm] infrared light, and the black toner absorbs, for example, 950 [nm] infrared light. Therefore, the wavelength of infrared light absorbed by the first concealed information image 80a and the first position information image 81a formed with the IR toner can be made different from the wavelength of infrared light absorbed by the second concealed information image 80b and the second position information image 81b formed with the black toner.

[0132] In this way, by making the wavelengths at which the first secret information image 80a and the second secret information image 80b absorb infrared light different from each other, the following advantages can be obtained. That is, for example, the first secret information image 80a formed with IR toner that absorbs infrared light of 800 [nm] can be detected well by a near-infrared camera using a CMOS image sensor that is excellent in detecting near-infrared light of 780 to 900 [nm]. On the other hand, for example, the second secret information image 80b formed with black toner that absorbs infrared light of 950 [nm] can be prevented from being detected by a near-infrared camera using a CMOS image sensor.

[0133] On the other hand, the second secret information image 80b formed with black toner can be detected well by a near-infrared camera using an InGaAs (indium gallium arsenide) image sensor that is excellent at detecting near-infrared rays of 900 to 1700 nm. However, the first secret information image 80a formed with IR toner cannot be detected well by a near-infrared camera using an InGaAs (indium gallium arsenide) image sensor.

[0134] In this way, unless multiple infrared cameras with different infrared detection wavelength ranges are used, it is impossible to obtain all of the hidden information formed on the printed matter 300, which has the advantage of increasing the security level (making it more difficult to imitate).

[0135] 24 has a first position information image 81a formed with IR toner and a second position information image 81b formed with black toner. Therefore, when the printed matter is imaged with a near-infrared camera using a CMOS image sensor, the first position information image 81a is projected, and the position of the first concealed information image 80a can be easily understood based on the first position information image 81a. When the printed matter is imaged with a near-infrared camera using an InGaAs (indium gallium arsenide) image sensor, the second position information image 81b is projected, and the position of the second concealed information image 80b can be easily understood based on the second position information image 81b.

[0136] Also, as shown in Fig. 25, the position information image may be a QR code, similarly to those shown in Figs. 17 and 18. For example, when searching for a secret information image by automation, a position information image consisting of a QR code is placed at the scan start position of the infrared camera of the machine (lower right in the example shown in Fig. 25). As a result, the machine first reads the QR code, which is the position information image, with the infrared camera and receives the position information of the secret information image. Then, based on the received position information of the secret information image, the infrared camera is moved to capture the secret information image, and the secret information image can be quickly read.

[0137] Next, a method for forming the secret information image 80 and the position information image using general black toner shown in FIGS. 23 to 25 will be described. As an image forming apparatus for forming the secret information image 80 or the position information image with general black toner, for example, in the image forming apparatus shown in FIG. 13, the IR process unit 6IR may be replaced with a K process unit that uses black toner.

[0138] 24, when forming a printed matter on which a secret information image made of IR toner and a secret information image made of black toner are printed, the Y, M, C, K, and IR process units are arranged as follows: the process units are arranged in the order of Y, M, C, K, and IR, or in the order of Y, M, C, IR, and K in the surface movement direction of the intermediate transfer belt.

[0139] Also, the image forming apparatus shown in FIG. 13 can also generate the printed matter shown in FIG. 24. Specifically, the IR process unit and toner bottle are replaced with a K-color process unit and toner bottle. Then, a secret information image and a position information image made of black toner are formed on a sheet P using the K process unit. Next, the K-color process unit and toner bottle are replaced with an IR process unit and toner bottle. Then, on the sheet P on which the secret information image and the position information image made of black toner have been formed, a secret information image and a position information image made of IR toner, and a background image 180 made of Y, M, and C are formed. This allows the printed matter shown in FIG. 24 to be formed.

[0140] By disposing the K color process unit downstream of the Y, M, and C color process units in the intermediate transfer belt movement direction, the K toner image is primarily transferred onto the Y, M, and C toner images on the intermediate transfer belt. In this way, since the K toner image is placed on the Y, M, and C toner images on the intermediate transfer belt, the K toner image 50 is placed below the C toner image 61, M toner image 62, and Y toner image 63 forming the background image 180 on the paper P, as shown in Fig. 26. As a result, the secret information image 80 and the position information image formed with the K toner are covered by the background image 180 made of the Y, M, and C toners, making it difficult to view the secret information image 80 and the position information image formed with the K toner.

[0141] Note that it is sufficient that the K toner image can be formed below the Y, M, and C color toner images on the paper, and the configuration is not limited to disposing the K process unit downstream of the Y, M, and C color process units in the intermediate transfer belt movement direction. Also, in the case of a direct transfer type image forming device that transfers the toner image of the process unit directly to the paper, the K process unit is disposed upstream of the Y, M, and C process units in the transport direction of the paper P. This allows the K toner image to be formed below the Y, M, and C toner images on the paper, and the secret information image 80 and position information image formed with the K toner can be covered by the background image 180 made of the Y, M, and C toners.

[0142] In addition, since the secret information image 80 and the position information image 81 formed with K toner are colored, there is a risk that the secret information image 80 and the position information image 81 formed with K toner may be visible depending on the background image formed. Therefore, as shown in Fig. 27, the background image 180 made of Y, M, and C colors may be formed multiple times to make the background image 180 thicker.

[0143] When forming a background image multiple times, it is preferable to use an image forming apparatus equipped with a re-conveyance path 220 as shown in Fig. 28. The image forming apparatus shown in Fig. 28 is equipped with a relay path 230 that conveys the paper P that has passed through the fixing device 21 to the re-conveyance path 220 without passing through the switchback path 210.

[0144] The confidential information image 80 and the position information image 81 made of black toner and the first background image 180 made of Y, M, and C toners are transferred onto the front surface of the paper P fed from the paper feed cassette 18, and then fixed by the fixing device 21. Next, the paper P on whose front surface the confidential information image 80, the position information image 81, and the first background image 180 have been fixed is transported to the re-transport path 220 via the relay path 230. At this time, the paper P is transported to the re-transport path 220 without being switched back by the switchback path 210, and is therefore transported again to the secondary transfer position as the image forming position without being inverted.

[0145] Then, a second background image 180' formed with Y, M, and C toners is transferred onto the first background image 180 on the front side of the paper that has been re-transported to the secondary transfer nip, and is then fixed to the paper P by the fixing device 21.

[0146] By using the image forming apparatus shown in FIG. 28, a printed matter consisting of a secret information image and a position information image made of black toner and a background image 180 made of Y, M, and C colors can be formed in a plurality of separate steps. Specifically, in the first step, a black toner image and a Y toner image are transferred onto the front side of a sheet of paper, and the black toner image and the Y toner image are fixed onto the sheet of paper. In the second step, an M toner image and a C toner image are transferred onto the front side of a sheet of paper, and the M toner image and the C toner image are fixed onto the sheet of paper. In this manner, a printed matter consisting of a secret information image and a position information image made of black toner, and a background image 180 made of Y, M, and C colors may be formed. By forming a printed matter in this manner, even if the background image 180 is wide, deterioration of fixability can be suppressed.

[0147] In addition, in the method of transferring an image to the front surface of the paper in multiple steps, it is possible to form K toner in the bottom layer of the paper even if the K-color process unit 6K is not positioned at the most downstream position in the direction of movement of the intermediate transfer belt.

[0148] In addition, the method of forming an image on the front side of the paper in multiple steps is not limited to the case where a secret information image and a position information image are formed with black toner, but can also be applied to the case where a secret information image and a position information image are formed with invisible toner such as IR toner. And by dividing the image into multiple steps in this way, it is possible to obtain the advantage that the image can be fixed without causing fixing failure.

[0149] In the above, an example in which the printed matter 300 is formed using toner has been described, but the printed matter 300 including the secret information image 80 and the position information image 81 may be printed using Y, M, and C color inks and IR ink in an inkjet type image forming apparatus. Also, the printed matter 300 including the secret information image 80 and the position information image 81 may be printed using black ink containing carbon and having infrared light absorbing properties.

[0150] Next, an information transmission system using the above-mentioned printer 200, printed matter 300, and infrared camera will be described. FIG. 29 is a functional block diagram of an information transmission system 600. First, an information sender 400 who sends secret information outputs an image having secret information created using a personal computer or the like by a printer 200 or the like shown in FIG. 13 or FIG. 28, and creates a printed matter 300 shown in FIG. 1, FIG. 4 to FIG. 12, FIG. 17, FIG. 21, FIG. 23 to FIG. 25. An information receiver 500 who receives secret information acquires secret information using the infrared camera 90 described above. In this way, the secret information is transmitted to the information receiver. The information sender prints the printed matter 300 having the position information image 81 shown in FIG. 1, FIG. 4 to FIG. 12, FIG. 17, FIG. 21, FIG. 23 to FIG. 25, etc., so that the information receiver can easily acquire the secret information. Furthermore, by using the infrared camera 90 described using FIG. 19, etc., the information receiver can acquire the secret information even more easily.

[0151] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) A printed matter 300 on which a concealed information image 80 that is visible under special conditions is printed has information images such as a position information image 81 relating to the position of the concealed information image 80. According to this, the position of the secret information image 80 can be easily found from an information image such as a position information image related to the position of the secret information image 80 printed on the printed matter 300.

[0152] (Aspect 2) In the first embodiment, the secret information image 80 is made of a special light-reactive image-forming material such as an IR toner. According to this, as described in the embodiment, the secret information image 80 becomes difficult to see except under special conditions such as irradiating it with special light such as infrared light or capturing an image with a special camera such as an infrared camera, and the secret information image 80 can be well concealed.

[0153] (Aspect 3) In embodiment 2, the special light responsive image forming material is an infrared absorbing toner such as an IR toner or an infrared absorbing ink such as an IR ink. According to this, the secret information image 80 is difficult to view except under special conditions such as when it is photographed by a special camera such as an infrared camera, and the secret information image 80 can be well concealed.

[0154] (Aspect 4) In the first aspect, the secret information image is a latent image that is distinguishable under special conditions from a background image that is visible under visible light. According to this, as explained using Figures 17, 18, and 21 to 25, except under special conditions such as capturing images with an infrared camera or using a high-resolution camera, the secret information image 80 blends into the background image 180 and becomes difficult to see, so that the secret information image 80 can be well concealed.

[0155] (Aspect 5) In the fourth embodiment, the secret information image 80 is made of a special light-reactive image forming material such as an IR toner that has the same color as the background image 180 under visible light. 17 and 18, the hidden information image 80 becomes a latent image blended into the background image 180 and is difficult to see, except under special conditions such as irradiation with special light such as infrared light or imaging with a special camera such as an infrared camera. This allows the hidden information image 80 to be well concealed.

[0156] (Aspect 6) In the fourth aspect, the dither pattern of the background image 180 and the dither pattern of the secret information image 80 are different from each other. 21 and 22, the hidden information image 80 becomes a latent image blended into the background image 180 and is difficult to see, except under special conditions such as when the vicinity of the hidden information image 80 is enlarged by a camera or the like. This allows the hidden information image 80 to be well concealed.

[0157] (Aspect 7) In aspects 1 or 4, the secret information image 80 is formed with black toner or black ink, and the secret information image 80 is covered with a background image formed with an image forming material (in this embodiment, Y, M, and C color toners) that is visible under visible light other than black toner and black ink. 23 to 25, the secret information image 80 formed with black toner or black ink can be concealed by covering it with the background image 180. In addition, the secret information image 80 formed with black toner or black ink absorbs infrared rays, and therefore becomes visible under special conditions such as capturing an image with an infrared camera.

[0158] (Aspect 8) In aspect 2 or 3, there is a second secret information image formed with black toner or black ink, and at least the second secret information image is covered with a background image formed with an image forming material (in this embodiment, Y, M, and C color toners) that is visible under visible light other than black toner and black ink. According to this, as explained using Figure 24, the secret information image made of the special light reactive image forming material and the second secret information image can be made visible under different special conditions, thereby increasing the security of the secret information image formed on the printed matter.

[0159] (Aspect 9) In the eighth aspect, the special condition under which the second hidden information image becomes visible is different from the special condition under which the hidden information image made of the transparent special light reactive image forming material becomes visible. According to this, as described with reference to FIG. 24, it is possible to improve the security of the secret information image formed on the printed matter.

[0160] (Aspect 10) In embodiment 9, the transparent special light reactive image forming material is an infrared absorbing toner such as an IR toner or an infrared absorbing ink, and the peak wavelength of infrared light absorbed by the infrared absorbing toner or infrared absorbing ink is different from the peak wavelength of infrared light absorbed by the black toner or black ink. According to this, as explained using Figure 24, unless multiple infrared cameras with different infrared detection wavelength ranges are used, it is impossible to obtain all of the hidden information formed on the printed matter 300, thereby increasing the security level.

[0161] (Aspect 11) In any of Aspects 7 to 10, the black toner or black ink contains carbon. According to this, as described with reference to FIGS. 23 to 25, an image formed with black toner or black ink becomes an image that absorbs infrared rays, and becomes visible under special conditions such as being captured by an infrared camera.

[0162] (Aspect 12) In any of the aspects 1 to 11, an information image such as the position information image 81 is an invisible image that is visible under the same conditions as those under which the secret information image 80 is visible. According to this, as described in the embodiment, the position information image becomes a latent image and cannot be seen except under special conditions, so the image formed by the position information image is not damaged by the position information image. Also, when searching for a secret information image using a means for making a secret information image visible, such as an infrared camera, an information image such as the position information image 81 becomes visible, and the position information of the secret information image can be obtained from the information image. This makes it possible to easily find the secret information image.

[0163] (Aspect 13) In aspect 12, an information image such as the position information image 81 has an arrow image that indicates the position of the secret information image. According to this, as described with reference to FIG. 4 and the like, the position of the secret information image can be grasped from the direction indicated by the arrow image, and the secret information image can be found.

[0164] (Aspect 14) In the twelfth or thirteenth aspect, an information image such as the position information image 81 has a character image indicating the position of the secret information image. According to this, as described with reference to FIG. 1 and FIG. 11, the position of the secret information image can be grasped from the character image, and the secret information image can be found.

[0165] (Aspect 15) In any of the aspects 11 to 14, the information images such as the position information image 81 are printed radially from the secret information image 80. According to this, as described with reference to Figs. 5 to 8, the position of the secret information image can be grasped from the density of the information image such as the position information image 81, and the secret information image can be found.

[0166] (Aspect 16) In any of aspects 11 to 15, an information image such as the position information image 81 is a grayscale image in which the image density changes with increasing distance from the secret information image side. According to this, as described with reference to FIGS. 8 to 10, the position of the secret information image can be grasped from the change in image density of the position information image 81, and the secret information image can be found.

[0167] (Aspect 17) In any of aspects 1 to 16, an information image such as the position information image 81 is a code image from which information regarding the position of the concealed information image is read by a reading device. According to this, as described with reference to Figures 17, 21, 25, etc., by reading the code image, it is possible to obtain information such as the position information, number information, and reading order of the secret information image. Also, compared to the case where the information is a character image, it is possible to notify such information with a smaller image, and even if the position information image is an image visible under visible light, the design of the image is not impaired.

[0168] (Aspect 18) In any of the aspects 1 to 17, a plurality of secret information images are printed, and an information image such as the position information image 81 has at least one of information regarding the number of secret information images and information regarding the reading order of the secret information images. According to this, as described with reference to Fig. 5 to Fig. 9 and Fig. 17, by having the information on the number of secret information images, it is possible to prevent forgetting to read the secret information images. Also, by having the information on the reading order of the secret information images, it is possible to obtain the secret information from the secret information images in the correct order.

[0169] (Aspect 19) A printed matter 300 on which a plurality of secret information images visible under special conditions are printed has an information image having at least one of number information on the number of secret information images and information on the reading order of the secret information images. 12 and the like, by having the information on the number of secret information images, it is possible to prevent forgetting to read the secret information images. Also, by having the information on the reading order of the secret information images, it is possible to obtain the secret information from the secret information images in the correct order.

[0170] (Aspect 20) In an image forming apparatus that forms a printed matter 300 by forming an image on a recording medium, the printed matter 300 of any of the aspects 1 to 19 can be generated.

[0171] (Aspect 21) In the 20th aspect, when a secret information image is formed, an information image such as the position information image 81 is automatically formed on the recording medium. This eliminates the need to create information images such as the position information image 81 using application software or the like.

[0172] (Aspect 22) In aspect 21, a calculation means is provided for calculating the amount of image forming material that needs to be discharged from the developing device in order to replace old image forming material, such as toner, in the developing device with new image forming material, and an information image, such as a position information image 81, is formed based on the amount of image forming material that needs to be discharged, such as the cumulative refresh amount, calculated by the calculation means. According to this, as described in the embodiment, the amount of image-forming material to be discarded can be reduced.

[0173] (Aspect 23) In the twenty-second embodiment, an information image such as the position information image 81 is changed according to the amount of image-forming material that needs to be discharged, which is calculated by the calculation means. According to this, as explained in the embodiment, when the amount of image forming material that needs to be discharged, such as the cumulative refresh amount, is large, an information image such as the position information image 81 that uses a lot of image forming material can be produced, and the image forming material such as toner that needs to be discharged from the developing device can be used effectively. On the other hand, when the amount of image forming material that needs to be discharged is small, an information image that does not use much image forming material can be produced, and consumption of image forming material that does not need to be discharged can be suppressed.

[0174] (Aspect 24) In the embodiment 22 or 23, the image density of an information image such as the position information image 81 is changed according to the amount of image forming material that needs to be discharged, such as the cumulative refresh amount calculated by the calculation means. According to this, as explained in the embodiment, when the amount of image forming material that needs to be discharged, such as the cumulative refresh amount, is large, the image density is increased, so that a large amount of image forming material can be used, and the image forming material such as toner that needs to be discharged from the developing device can be effectively used. On the other hand, when the amount of image forming material that needs to be discharged is small, the image density is decreased, so that consumption of image forming material that does not need to be discharged can be suppressed.

[0175] (Aspect 25) In the twenty-fourth embodiment, at least one of the amount of exposure light of the exposure device 11 that exposes a latent image carrier such as the photoreceptor 7 to form a latent image and the developing bias of the development device 9 is adjusted to change the image density. According to this, as described in the embodiment, the amount of image forming material such as toner adhering to a latent image carrier such as a photoconductor 7 can be adjusted, and the image density of an information image such as a positional information image 81 can be changed.

[0176] (Aspect 26) In any of aspects 22 to 25, a position information image is formed so that the amount of image forming material that needs to be discharged from the developing device, such as the cumulative refresh amount after forming an image including an information image such as position information image 81, is greater than or equal to 0 and less than an execution threshold such as discharge execution threshold H that executes refresh control to discharge old image forming material in the developing device. According to this, as described in the embodiment, the refresh control is executed after the image formation, and it is possible to prevent the image forming material such as toner from being wasted. Also, it is possible to suppress the consumption of the image forming material that does not need to be discharged.

[0177] (Aspect 27) In any of aspects 20 to 26, a re-transport path 220 is provided to re-transport a recording medium that has passed through an image forming position, such as a secondary transfer position where an image is formed on a recording medium such as paper P, to the image forming position, and the recording medium is passed through the image forming position multiple times, and an image is formed on the recording medium in multiple passes to generate a printed matter. According to this, as described with reference to FIG. 28, it is possible to make the background image 180 thicker and to prevent poor fixing.

[0178] (Aspect 28) In an information acquisition device such as an infrared camera 90 that acquires secret information from a secret information image of a printed matter 300 of any of aspects 1 to 19, the device has an identification unit such as an image analysis unit 95 that identifies the position of the secret information image from an information image such as a position information image 81, and a display unit such as an image display unit 97 that displays the position information of the secret information image identified by the identification unit. According to this, as described in the embodiment, it is possible to find a secret information image based on the position information displayed on a display unit such as the image display unit 97 of an information acquisition device such as the infrared camera 90.

[0179] (Aspect 29) In aspect 28, a display unit such as the image display unit 97 displays the printed matter 300 captured by the imaging element, and based on the positional information of the confidential information image identified by an identification unit such as the image analysis unit 95, places a mark such as a focus mark M at a position on the printed matter 300 displayed on the display unit corresponding to the confidential information image. According to this, as described in the embodiment, it is possible to grasp from marks such as the focus mark M displayed on the display unit where the secret information image is located on the printed matter 300, and it is possible to easily locate the secret information image.

[0180] (Aspect 30) In aspect 29, when the printed matter 300 has multiple secret information images formed thereon and an information image such as the position information image 81 includes information indicating the order in which the multiple secret information images were acquired, the secret information image to be marked is changed based on the information indicating the order in which the position information images were acquired and whether or not secret information was acquired from the marked secret information image. According to this, as described in the embodiment, it is possible to obtain the secret information from the secret information image in the correct order.

[0181] (Aspect 31) In an information transmission system that transmits secret information by using an image forming device such as a printer 200 to output a printed matter 300 on which a secret information image is printed, and acquiring the secret information from the secret information image using an information acquisition device such as an infrared camera 90, at least one of the printed matter of any of aspects 1 to 19, the image forming device of any of aspects 20 to 27, and the information acquisition device of any of aspects 28 to 30 is used. According to this, as described with reference to FIG. 29, the information receiver can easily obtain the secret information. [Explanation of symbols]

[0182] 9: Developing device 11: Exposure equipment 30: Control section 80: Confidential information image 81: Location information image 82: Quantity information image 90: Infrared camera 90a: Spot size 91:Optical system 92: Imaging unit 93: Image processing section 94: Image storage section 95: Image analysis section 96: Mark generation unit 97: Image display section 180: Background image 220: Re-transport path M: Focus mark P:Paper [Prior art documents] [Patent documents]

[0183] [Patent Document 1] JP 2019-117371 A

Claims

1. In a printed matter on which a secret information image that is visible under special conditions is printed, an information image having information leading to a position of the secret information image; the information image is a latent image that is visible under a condition in which the secret information image is visible, A printed matter, characterized in that a plurality of the secret information images are arranged in a direction approaching the secret information image from a distance.

2. In the printed matter described in claim 1, A plurality of information image columns in which a plurality of the information images are arranged, A printed matter, characterized in that a row of a plurality of information images is printed radially from the secret information image.

3. In the printed matter according to claim 2, There are a plurality of groups each including the secret information image and a sequence of a plurality of information images, A printed matter, characterized in that the image of the information image is different for each of the groups.

4. The printed matter according to any one of claims 1 to 3, The printed matter is characterized in that the information image has an arrow image indicating the position of the secret information image.

5. The printed matter according to any one of claims 1 to 3, The printed matter is characterized in that the information image has a character image indicating a position of the secret information image.

6. In the printed matter according to any one of claims 1 to 5, The printed matter is characterized in that the secret information image is made of a transparent special light-reactive image-forming material.

7. The printed matter according to claim 6, The special light-reactive image-forming material is an infrared absorbing toner or an infrared absorbing ink.

8. In the printed matter according to any one of claims 1 to 7, The printed matter is characterized in that the information image is a grayscale image in which image density changes with distance from the secret information image.

9. The printed matter according to any one of claims 1 to 8, The printed matter is characterized in that the information image is a code image from which information regarding the position of the secret information image is read by a reading device.

10. The printed matter according to any one of claims 1 to 9, A plurality of the secret information images are printed, The information image includes at least one of information regarding the number of the secret information images and information regarding the reading order of the secret information images.

Images