JP2006010721A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus easily and at low cost, performing processing to prevent unauthorized copying, when outputting an image. <P>SOLUTION: When the performance of the processing to prevent the unauthorized copying is inputted, an ink applying means 30 forms a copying preventing area 31 by applying color ink at a prescribed position on the image surface of paper 21 having passed through a fixing part 14. An image, formed on the paper 21 in an image forming part P and fixed in the fixing part 14, can be recognized visually through the copying preventing area 31. When monochromatically copying the image, the image in the copying preventing area 31 is outputted in a state, where it can not be discriminated from the copying preventing area 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to a function of suppressing illegal copying of an output image.

  In recent years, copying of documents has become easy due to the spread of copying machines. However, if the document is a confidential document, leakage of information described by unauthorized copying or unauthorized copying will cause serious damage to the company. . Conventionally, a method of preventing unauthorized copying by restricting the use of a copying machine or strictly managing confidential documents has been adopted, but it has been difficult to completely prevent unauthorized copying. .

  Therefore, various methods for preventing unauthorized copying of confidential documents have been proposed. For example, Patent Document 1 prints an identification code for specifying an image forming apparatus used after fixing an image using a chromogenic substance. A method for preventing unauthorized copying and preventing recidivism is disclosed. Also, in Patent Document 2, a confidential document is printed on a specific sheet coated with infrared absorbing ink on the entire surface or partly, and whether or not the original is a specific sheet by irradiating infrared rays on the copying machine side. A method for discriminating and prohibiting copying when a specific sheet is used is disclosed.

  Furthermore, Patent Document 3 discloses that when a confidential document is printed, a predetermined character pattern in the document is converted to such an extent that readability is not impaired, and the presence or absence of character pattern conversion is detected on the copier side. An unauthorized copying prevention method for determining whether or not copying is possible by determining whether or not the above is disclosed.

  However, in the method of Patent Document 1, it is necessary to apply an expensive ink containing a coloring material when printing confidential documents, and in the method of Patent Document 2, it is necessary to use special paper coated with infrared absorbing ink. As a result, the printing cost becomes high. In the method of Patent Document 3, the control of the image forming apparatus is complicated because a specific character pattern in the document is converted. Furthermore, in the case of the methods of Patent Documents 2 and 3, since it is necessary to provide a special detection function for determining whether or not copying is possible on the copying machine side, copying machines that can prevent unauthorized copying are limited and expensive. There was a problem that it would be a bad thing.

JP-A-6-54167 JP-A-6-250568 JP 2001-251490 A

  In view of the above problems, an object of the present invention is to provide an image forming apparatus that performs unauthorized copy prevention processing at the time of image output at a simple and low cost.

  In order to achieve the above object, the present invention provides a data input means for inputting image data, a data conversion means for converting image data input by the data input means into write data, and a paper on the basis of the write data. In the image forming apparatus comprising: an image forming unit that outputs an image to the image forming unit; an input unit that inputs whether or not to execute an unauthorized copy prevention process on the output image; And an ink application unit that applies color ink onto the output paper, and when the execution of illegal copy prevention processing is input from the input unit, the ink application unit displays an image overlapping the ink layer. It is characterized in that a copy-preventing area composed of a predetermined color that can be visually recognized and is output indistinguishable during monochrome copying is formed.

  According to the present invention, in the image forming apparatus having the above configuration, the image forming unit exposes the photosensitive member, a charging device for charging the photosensitive member, and the surface of the photosensitive member charged by the charging device to electrostatically An image forming unit comprising an exposure device for forming a latent image, a developing device for developing the electrostatic latent image to form a toner image, and transferring the toner image formed by the image forming unit onto a sheet An image transfer unit that fixes the image transferred by the image transfer unit on a sheet, and the ink application unit applies color ink onto the sheet on which the image is fixed by the fixing unit. It is characterized by doing.

  According to the present invention, in the image forming apparatus configured as described above, the ink applying unit is an ink jet apparatus.

  According to the present invention, in the image forming apparatus configured as described above, there is provided storage means for storing complementary color data that can be identified for the predetermined color and that is output indistinguishable from the predetermined color during monochrome copying. The data conversion means converts image data of a color similar to the predetermined color existing in the copy prevention area into the complementary color data before outputting the image.

  The present invention also provides a data input means for inputting image data, a data conversion means for converting image data input by the data input means into writing data, and a color image is output on a sheet based on the writing data. In an image forming apparatus comprising: an image forming unit; an input unit that inputs whether or not to execute unauthorized copy prevention processing on an output image; and a predetermined color that can be identified, and at the time of monochrome copying, Storage means for storing complementary color data that is output indistinguishably from a predetermined color, and when the execution of illegal copy prevention processing is input from the input means, the image forming means A copy prevention area composed of colors is formed at the same time as image output, and the data converting means is an image having a color similar to the predetermined color existing in the copy prevention area. The chromatography data is characterized by converting the complementary color data before image output.

  According to the present invention, in the image forming apparatus configured as described above, the data conversion means converts all image data in the copy prevention area into the complementary color data before outputting the image.

  According to the present invention, in the image forming apparatus configured as described above, the copy prevention area is formed in a half or more area on a sheet.

  According to the first configuration of the present invention, the ink application means for applying the color ink is provided on the paper before the image output or after the image output, and on the paper overlapping the ink layer when the illegal copy prevention process is input. By forming a copy-prevention area where the image is visible and output indistinguishable during monochrome copying, it is possible to perform illegal copy prevention processing on the output image easily and at low cost without using special paper or ink. Can do.

  According to the second configuration of the present invention, in the image forming apparatus having the first configuration, the image forming unit includes an image forming unit including a photoreceptor, a charging device, an exposure device, and a developing device, and a toner image. An image transfer unit that transfers the image transferred onto the paper and a fixing unit that fixes the image transferred by the image transfer unit. The ink application unit applies color ink onto the paper on which the image is fixed by the fixing unit. Thus, in an electrophotographic copying machine, unauthorized copying prevention processing can be performed without damaging the formed image.

  Further, according to the third configuration of the present invention, in the image forming apparatus having the first or second configuration, the ink application unit is an ink jet device, so that a uniform copy-preventing region can be provided at a predetermined position on the sheet. Can be formed.

  Further, according to the fourth configuration of the present invention, in the image forming apparatus having any one of the first to third configurations, the predetermined color can be identified, and the monochrome image cannot be distinguished from the predetermined color. Storage means for storing complementary color data to be output is provided, and image data of a color similar to a predetermined color existing in the copy prevention area is converted into complementary color data and output, thereby outputting the same color existing in the copy prevention area The visibility of color images and characters can be improved.

  According to the fifth configuration of the present invention, in the image forming apparatus in which the image forming unit forms the copy-preventing area having the predetermined color on the paper simultaneously with the image output, the predetermined color can be identified, and Storage means for storing complementary color data that cannot be distinguished from a predetermined color during monochrome copying is provided, and when illegal copy prevention processing is input, image data of similar colors existing in the copy prevention area is output before image output. By converting to complementary color data, it is not necessary to separately provide means for forming a copy prevention area, and the structure of the apparatus is simplified. Furthermore, the visibility of images and characters in the copy prevention area can be further improved.

  According to the sixth configuration of the present invention, in the image forming apparatus having the fourth or fifth configuration, all image data in the copy prevention area is converted into complementary color data, thereby preventing copy at the time of monochrome copying. Even when the area is not blacked out, the image in the copy prevention area cannot be identified, so that the effect of preventing unauthorized copying can be ensured.

  Further, according to the seventh configuration of the present invention, in the image forming apparatus having any one of the first to sixth configurations, the copy prevention area is formed in a half or more area on the sheet, and thus illegal Ensure copy prevention effect.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of the image forming apparatus according to the first embodiment of the present invention. In FIG. 1, an image forming apparatus 1 is a type of printer that outputs an image on transfer paper based on input image data. In the image forming apparatus 1, when performing an image forming operation, an image forming unit P The photosensitive drum 5 rotating in the direction A in the drawing is uniformly charged by a charging device (not shown), and is supplied from an exposure device (laser scanning unit or the like) 7 based on document image data input from a data input means 25 described later. An electrostatic latent image is formed on the photosensitive drum 5 by the laser beam, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by a developing device (not shown) to form a toner image.

  The sheet 21 is conveyed from the sheet feeding mechanism 10 to the image forming portion P via the sheet conveying path 11 and the registration roller pair 12 toward the photosensitive drum 5 on which the toner image is formed as described above. In the portion P, the toner image formed on the surface of the photosensitive drum 5 is transferred onto the sheet by the transfer roller 4 (image transfer portion). Then, the sheet 21 on which the toner image is transferred is separated from the photosensitive drum 5 and conveyed to the fixing unit 14 to fix the toner image. The sheet that has passed through the fixing unit 14 is sent to a sheet conveyance path 15 branched in a plurality of directions, and the conveyance direction is distributed by a path switching mechanism 22 having a plurality of path switching guides provided at branch points of the sheet conveyance path 15. As it is (or after being sent to the paper conveyance path 16 and double-sided printing), the paper is discharged to a paper discharge section comprising the discharge roller pair 23 and the discharge tray 24.

  Although not shown, a static elimination device that removes residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 18. The paper feed mechanism 10 is detachably attached to the image forming apparatus 1, and is connected to an image forming portion P including the photosensitive drum 5 and the exposure device 7 by a paper conveyance path 11. Specifically, the sheet conveyance path 15 is bifurcated on the downstream side of the fixing roller pair 14a, and one path (the path branching leftward in FIG. 1) is connected to the discharge tray 24 via the discharge roller pair 23. It is configured to communicate. The other path (the path that branches downward in FIG. 1) is configured to communicate with the sheet conveyance path 16.

  The data input means 25 captures a desired image converted into data into the image forming apparatus. The data input means 25 is a data reading means for taking a digital image stored on a web server on the Internet or an image created by a drawing application such as a personal computer into an image forming apparatus via a network, or a photograph or an illustration. An image reading means such as a scanner for reading the original image as image data is used.

  The data conversion unit 26 converts the image data input by the data input unit 25 into write data and transmits it to the exposure apparatus 7. The exposure device 7 forms an electrostatic latent image on the photosensitive drum 5 based on the transmitted writing data. A toner image is formed on the electrostatic latent image by a developing device (not shown) to form a toner image, which is transferred from the paper feed mechanism 10 onto the paper 21 conveyed through the paper conveyance path 11. The control unit 27 controls the operation of each part of the image forming apparatus based on a signal from the operation panel 28 or the data conversion unit 26.

  The operation panel 28 includes operation keys for a user to input settings such as device functions and printing conditions, and a display unit (none of which is shown) that displays the setting conditions and the state of the device. In the case of an image forming apparatus of a type in which a user inputs settings such as printing conditions from a personal computer, the operation panel 28 is a personal computer print setting screen. The storage unit 29 stores a control program for each part of the image forming apparatus used by the control unit 27. Reference numeral 30 denotes an ink application unit, which forms a copy prevention region by applying color ink to a predetermined position on the image surface of the paper 21 that has passed through the fixing unit 14 based on an instruction for illegal copy prevention processing input from the operation panel 28. To do.

  The ink application means 30 is not particularly limited as long as it can apply color ink to a certain area of the paper 21. For example, a felt pen provided with an ink supply device or an application that rotates in the paper conveyance direction. A roller or the like is provided adjacent to the paper conveyance path 15 so as to come into contact with the conveyed paper 21, or ink is ejected as fine droplets from a thin nozzle (orifice) while controlling this with an image signal. An ink jet type application device that adheres to a sheet can be mentioned. In particular, when an ink jet apparatus is used, it is possible to form a copy prevention region in which an ink layer is uniformly applied at a desired position on a sheet, and uneven application of ink. It is more preferable because it can prevent the image visibility and the copy prevention effect from being lowered.

  The color ink applied by the ink application unit 30 is not particularly limited as long as it is a normal printing ink, but the copy prevention area formed by the ink application unit 30 is formed on the paper 21 in the image forming unit P. The image fixed in the fixing unit 14 can be visually recognized through the ink layer, and is output so that it cannot be visually recognized during monochrome copying, thereby preventing unauthorized monochrome copying. For this reason, it is preferable that the output image on the paper 21 is not completely concealed and is output as a blackout in monochrome copying. For example, an organic dye-based ink is preferable.

  FIG. 2 shows an image provided with a copy prevention area. As shown in FIG. 2A, a vertical stripe-shaped copy prevention region 31 is formed on the paper 21 by the ink applying means 30 (see FIG. 1). At this time, since the copy prevention area 31 does not completely hide the output image, the user can easily read the image and characters output on the paper 21 through the copy prevention area 31.

  On the other hand, when the paper 21 provided with the copy prevention area 31 is copied in black and white, the copy prevention area 31 is output in black as shown in FIG. 2B, and images and characters in the copy prevention area 31 are unreadable. It becomes possible. That is, when outputting important documents, confidential documents, etc., by forming the copy prevention area 31, illegal copying and unauthorized copying by a monochrome copying machine can be prevented.

  In this embodiment, a monochrome type digital copying machine has been described as an image forming apparatus. However, other types of copying machines such as a tandem color copying machine and an analog type monochrome copying machine, or a facsimile, an inkjet printer, and a laser printer. The present invention can also be applied to an image forming apparatus. However, when applied to a color image forming apparatus, for example, if an image of the same color as the applied ink overlaps the copy prevention area, the visibility of the output original image is deteriorated.

  Therefore, the storage unit 29 stores color data (hereinafter referred to as complementary color data) that can be visually recognized with respect to a predetermined color forming the copy prevention area and that cannot be distinguished from the predetermined color during monochrome copying. In addition, it is desirable to convert image data of a similar color to a predetermined color existing in the copy prevention area into complementary color data in advance.

  When image data of similar colors W existing in the copy prevention area 31 is output without being converted into complementary color data, the boundary of the characters W becomes unclear as shown in FIG. Sex is reduced. On the other hand, when converted into complementary color data and output, the visibility of the character W can be ensured as shown in FIG. The conversion of the image data may be a conversion that emphasizes the contour, for example, the image is edged with a complementary color as shown in FIG.

  Also, regarding the color and density of the ink, various color inks that satisfy the above conditions can be used by setting them to the optimum density as appropriate. However, the color ink that is completely blackened during monochrome copying is used to prevent copying. When the region 31 is formed, although the effect of preventing unauthorized copying is enhanced, the concealment property for the output image is enhanced and the visibility of the original image is lowered. On the contrary, the concealment property is weakened to ensure the visibility of the original image. If it tries to do so, the copy prevention area 31 is output as a halftone during monochrome copying, and there is a risk that the dark color image in the copy prevention area will be read. Therefore, in such a case, it is preferable to convert all the image data in the copy prevention area 31 into complementary color data in advance.

  In the original image including the similar color image W1 and the dark color image W2 in the copy prevention area 31 as shown in FIG. 4A, when only the similar color image data is converted into the complementary color data, FIG. As shown in b), the visibility of the image W1 of the same color in the original image can be improved, but if the copy prevention area 31 is not completely blacked out during monochrome copying, The dark image W2 can be identified during monochrome copying as shown in FIG. On the other hand, when all the image data in the copy prevention area 31 is converted into complementary color data, the visibility of W1 and W2 in the original image is ensured as shown in FIG. The color image W2 cannot be identified during monochrome copying as shown in FIG.

  As a result, even when the color ink is not sufficiently concealed to the extent that the black color is crushed during monochrome copying, the copy prevention area 31 is output as a uniform halftone together with the existing image during monochrome copying. It is possible to make the image in the region 31 indistinguishable. Also in the case of a monochrome type image forming apparatus, the image data is converted into complementary color data (in this case, gradation data), and the image density is adjusted as appropriate to ensure the visibility of the original image in the same manner. The effect of preventing unauthorized copying during monochrome copying can be enhanced. In order to suppress a reduction in the visibility of the image outside the copy prevention area 31, it is preferable that the range in which the image data is converted is matched with the range in which the copy prevention area 31 is formed.

  In the present embodiment, as shown in FIG. 1, the ink application unit 30 is provided on the downstream side of the fixing unit 14. When the ink application unit 30 is provided between the image forming unit P and the fixing unit 14, the color ink is applied before the toner image transferred onto the paper 21 by the image forming unit P is fixed. The toner image is disturbed by the color ink application. Therefore, as in the present embodiment, the ink application unit 30 is provided on the downstream side of the fixing unit 14, and after the toner image is fixed on the paper, the color ink is applied to form the copy prevention region 31, or the ink application is performed. The means 30 is provided on the upstream side of the image forming portion P, and the copy prevention area 31 must be formed in advance before the image formation.

  When the copy prevention area 31 is formed before image formation, a desired image can be formed on the ink layer of the copy prevention area 31 so that the output image may be hidden by the copy prevention area 31. Therefore, the visibility of the image in the copy prevention area 31 is improved, but a drying process is required to dry the formed copy prevention area 31 before image formation. Therefore, it is preferable to adopt the configuration of this embodiment in which the copy prevention area 31 is formed after the toner image is fixed.

  Although it is possible to make the entire surface of the paper 21 as the copy-preventing area 31, as shown in FIG. 2, illegal copying is possible if it is formed in a predetermined area where images and characters cannot be read after monochrome copying. The prevention effect is sufficient, the legibility of the original image before copying is improved, and the consumption of color ink can be reduced. In order to ensure the effect of preventing unauthorized copying, it is preferable to form the copy prevention area 31 in an area of 1/2 or more of the paper 21.

  Here, the copy prevention area 31 is formed in a vertical stripe shape, but various patterns covering the entire surface of the paper 21 such as a horizontal stripe shape and a matrix shape can be used. Further, an output image detecting means for detecting the position of the image on the paper 21 may be provided, and the copy prevention area 31 may be formed only in the portion where the image or character is output.

  Next, the operation of the image forming apparatus of this embodiment will be described. FIG. 5 is a flowchart illustrating an image forming procedure performed by the image forming apparatus according to the first embodiment. The image forming operation of the image forming apparatus will be described with reference to FIG. In this operation procedure, first, the operation panel 28 is operated by the user, and an image forming operation is started (step S1). At this time, whether or not to execute “illegal copy prevention processing” for forming the copy prevention area 31 is also input. Next, a desired image is taken in by the data input means 25 and converted into write data by the data conversion means 26 (step S2). The write data is transmitted to the image forming unit P, and a toner image is formed on the paper 21 (step S3).

  The formed toner image is fixed on the paper 21 in the fixing unit 14 (step S4). In step 1, it is determined whether or not execution of “illegal copy prevention process” has been input (step S 5). When the “illegal copy prevention process” is executed, the ink application unit 30 performs a predetermined area on the paper 21. After the color ink is applied to form the copy prevention area 31 (step S6), the color ink is discharged to the discharge tray 24 via the discharge roller 23 (step S7).

  On the other hand, when the “illegal copy prevention process” is not executed in step S5, the paper 21 is discharged as it is to the discharge tray 24 (step S7), and the process is terminated. When the copy prevention area is formed before the image formation, it is determined whether or not the “illegal copy prevention process” is executed (step S5) and the copy prevention area 31 is formed by applying color ink (step S6). May be performed before the toner image forming step (step S3).

  FIG. 6 is a flowchart showing another example of the image forming operation in the image forming apparatus of the present embodiment. In this example, an image forming operation in the case where image data of a portion where a copy prevention area is formed in advance is converted into complementary color data will be described. First, the operation panel 28 is operated by the user, and an image forming operation is started (step S1). At this time, whether or not to execute “illegal copy prevention processing” for forming the copy prevention area 31 is also input. Next, a desired image is taken in by the data input means 25 and converted into write data by the data conversion means 26 (step S2). At this time, it is determined whether or not execution of “illegal copy prevention processing” is input in step S1 (step S3).

  When the “illegal copy prevention process” is executed, all the image data in the portion where the copy prevention area 31 is formed is converted into complementary color data (gradation data) stored in the storage means 29 (step S4) and output. The image is converted into a predetermined halftone image. Then, the write data is transmitted to the image forming portion P, and a toner image is formed on the photosensitive drum 5, and then transferred onto the paper 21 (step S5). The transferred toner image is fixed on the paper 21 by the fixing unit 14 (step S6), and after the color ink is applied to a predetermined area on the paper 21 by the ink applying means 30, the copy prevention area 31 is formed (step S6). In step S8, the sheet is discharged to the discharge tray 24 through the discharge roller 23 (step S8).

  On the other hand, if the “illegal copy prevention process” is not executed in step S3, the image data is not converted, and the toner image is formed on the photosensitive drum 5 and transferred onto the paper 21 as it is (step S9). . The formed toner image is fixed on the paper 21 by the fixing unit 14 (step S10), and is discharged onto the discharge tray 24 via the discharge roller 23 without being applied with ink by the ink applying means 30 (step S8). Exit. Although the operation of the monochrome type image forming apparatus has been described here, the color image forming apparatus is also described in exactly the same manner. In the case of a color image forming apparatus, only the image data of similar colors in the copy prevention area may be converted to complementary color data in step S4.

  Next, a second embodiment of the present invention will be described. FIG. 7 is a schematic diagram showing the configuration of the image forming apparatus according to the second embodiment, and FIG. 8 is a block diagram showing the configuration of the image forming apparatus according to the second embodiment. Portions common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, a tandem color image forming apparatus is shown as the image forming apparatus 1, and four image forming portions Pa, Pb, Pc, and Pd are provided in the image forming apparatus 1 on the upstream side of the conveying belt 8 ( They are arranged in order from the right side in FIG. These image forming units Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and constitute an image forming unit 40 (see FIG. 8) together with the fixing unit 14 described later. Then, cyan, magenta, yellow, and black images are sequentially formed by charging, exposing, developing, and transferring processes.

  In the image forming portions Pa to Pd, photosensitive drums 5a, 5b, 5c, and 5d that carry toner images of respective colors are disposed, and the toner images formed on these photosensitive drums 5a to 5d are disposed. The image is transferred onto a sheet 21 carried and conveyed by a conveying belt 8 that moves adjacent to each image forming unit, and is further fixed on the sheet 21 by a fixing unit 14 and then discharged from the apparatus main body. It has become. An image forming process for each of the photosensitive drums 5a to 5d is executed while rotating the photosensitive drums 5a to 5d clockwise in FIG.

  Next, the image forming units Pa to Pd will be described. Around and around the photosensitive drums 5a to 5d rotatably arranged, image information is supplied to the charging devices 2a, 2b, 2c and 2d for charging the photosensitive drums 5a to 5d and the photosensitive drums 5a to 5d. LED heads 17a, 17b, 17c and 17d to be exposed, developing devices 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 5a to 5d, and toner remaining on the photosensitive drums 5a to 5d are removed. Cleaning parts 18a, 18b, 18c and 18d are provided.

  First, the surfaces of the photosensitive drums 5a to 5d are uniformly charged by the charging devices 2a to 2d, and then light is irradiated by the LED heads 17a to 17d, and electrostatic charges corresponding to the image signals are applied to the photosensitive drums 5a to 5d. A latent image is formed. Each of the developing devices 3a to 3d is filled with a predetermined amount of cyan, magenta, yellow, and black toner by a replenishing device (not shown). The toner is supplied onto the photosensitive drums 5a to 5d by the developing devices 3a to 3d and electrostatically attached to the toner corresponding to the electrostatic latent images formed by the exposure from the LED heads 17a to 17d. An image is formed.

  The sheet 21 onto which the toner image is transferred is accommodated in the sheet feeding mechanism 10 at the lower part of the apparatus, and is supplied onto the conveying belt 8 via the pair of sheet feeding rollers 32 and the pair of registration rollers 12, and each photosensitive drum 5a. It is conveyed to a position of ˜5d. A sheet made of dielectric resin is used for the conveyor belt 8, and a belt in which both ends thereof are overlapped and joined to form an endless shape or a seamless belt is used.

  The conveyor belt 8 is stretched between an upstream conveyor roller 33 and a downstream drive roller 34, and the conveyor belt 8 rotates counterclockwise as the drive roller 34 is rotated by a drive motor (not shown). When the rotation is started, the paper 21 is transported from the registration roller pair 12 onto the transport belt 8 via the suction roller 35 provided on the most upstream side of the transport belt. A predetermined voltage is applied to the suction roller 35, and the paper 21 is held on the transport belt 8 by an electrostatic suction force.

  At this time, the image writing signal is turned ON, and an image is formed on the uppermost photosensitive drum 1a at a predetermined timing. The cyan toner image on the photosensitive drum 5a is transferred onto the paper 21 by applying an electric field to the lower portion of the photosensitive drum 5a with the transfer roller 4a to which a predetermined transfer voltage is applied. Thereafter, the sheet 21 is conveyed to the next image forming portion Pb, and a magenta toner image is transferred by the photosensitive drum 5b in the same manner as described above.

  Thereafter, yellow and black toner images are transferred by the photosensitive drums 5c and 5d by the same method as described above. These four-color images are formed with a predetermined positional relationship predetermined with respect to the paper 21 for forming a predetermined full-color image. Reference numerals 4b, 4c and 4d denote transfer rollers positioned below the photosensitive drums 5b to 5d. The sheet 21 on which the four-color toner images are transferred is separated from the conveying belt 8 and conveyed to the fixing unit 14. In addition, the photosensitive drums 5a to 5d after the toner image is transferred are prepared by a cleaning unit 18a to 18d to remove toner remaining on the surface in preparation for the subsequent formation of a new electrostatic latent image.

  The paper 21 transported from the transport belt 8 to the fixing unit 14 is heated and pressed by the fixing roller 14a, and the toner image is fixed on the surface of the paper 21 to form a predetermined full-color image. The paper 21 on which the full-color image is formed is then discharged to the discharge tray 24 by the discharge roller pair 23.

  In the present embodiment, when the toner image is transferred by the image forming portions Pa to Pd, the copy prevention area 31 (see FIG. 2) is formed at the same time. With this configuration, it is not necessary to separately provide the ink application unit 30 as in the first embodiment, and the structure of the image forming apparatus can be simplified. As in the first embodiment, the copy prevention area 31 needs to be output so that images and characters in the area can be read and cannot be visually recognized during monochrome copying. At this time, if the copy prevention area 31 and the image or character existing in the copy prevention area 31 have similar colors, the output image or character cannot be accurately visually recognized.

  Therefore, the same complementary color data as in the first embodiment is stored as conversion data in the storage unit 29, and when a similar color image or character exists in the copy prevention area 31, the image data is converted into complementary color data. (See FIG. 3). For example, when the color of the copy prevention area 31 is magenta, the magenta image in the copy prevention area 31 is converted to cyan and output.

  The image forming portion for forming the copy prevention area 31 may be any one of Pa to Pd. By forming the copy prevention area 31 using two or more of the image formation portions Pa to Pd, the copy prevention area 31 is formed. It can also be a desired color. Since the area, pattern, and the like in which the copy prevention area 31 is formed are the same as those in the first embodiment, description thereof is omitted.

  If complete blackout is not achieved during monochrome copying due to the color tone or density of the copy prevention area 31, not only image data of the same color but all image data in the copy prevention area 31 as in the first embodiment. Is preferably converted into complementary color data in advance (see FIG. 4).

  Next, the operation of the image forming apparatus of this embodiment will be described. FIG. 9 is a flowchart illustrating an image forming procedure performed by the image forming apparatus according to the second embodiment. With reference to FIGS. 7 and 8, the image forming operation of the image forming apparatus will be described in accordance with the steps in FIG.

  In this operation procedure, first, the operation panel 28 is operated by the user, and an image forming operation is started. At this time, whether or not to execute “illegal copy prevention processing” for forming the copy prevention area 31 is also input (step S1). Next, a desired image is captured by the data input means 25 (step S2). The captured image data is converted into write data by the data conversion means 26. At this time, it is determined whether or not execution of “illegal copy prevention processing” is input in step S1 (step S3).

  When the “illegal copy prevention process” is executed, it is further determined whether or not similar color image data exists in the copy prevention area (step S4), and if present, the image data is stored in the storage means 29. After conversion to the complementary color data (step S5), the image and write data for forming the copy prevention area are transmitted to each of the image forming units Pa to Pd (step S6). On the other hand, if there is no image data of the same color as the copy prevention area in step S4, the image and write data for forming the copy prevention area are transmitted without performing data conversion (step S6).

  Next, based on the transmitted writing data, the toner images of each color and the copy prevention area 31 are formed in the image forming portions Pa to Pd and transferred onto the paper 21 (step S7). The transferred toner image and the copy prevention area 31 are fixed on the paper 21 by the fixing unit 14 (step S8), and are then discharged to the discharge tray 24 via the discharge roller 23 (step S9), and the processing is completed. On the other hand, when the “illegal copy prevention process” is not executed in step S2, only the image data is transmitted to the image forming units Pa to Pd (step S10), and only the toner images of the respective colors are formed in the image forming units Pa to Pd. Then, it is transferred onto the paper 21 (step S11). Thereafter, the transferred toner image is similarly fixed in the fixing unit 14 and discharged to the discharge tray 24 (steps S8 and S9).

  As in the case of FIG. 6, in the case where all the image data existing in the copy prevention area is converted in advance and the image at the time of monochrome copying cannot be identified more reliably, the determination in step S4 is not performed. In step S5, all the image data in the copy prevention area 31 may be converted into complementary color data. In this embodiment, only the tandem type color copying machine has been described as the image forming apparatus. However, this embodiment can be applied to other color image forming apparatuses such as a laser printer and an ink jet printer. .

  The present invention relates to data input means for inputting image data, data conversion means for converting image data input by the data input means into write data, and image forming means for outputting an image on a sheet based on the write data. In the image forming apparatus, an input unit that inputs whether or not to execute unauthorized copy prevention processing on the output image, and color ink on the paper before or after the image output by the image forming unit When the execution of unauthorized copy prevention processing is input from the input unit, the ink application unit can visually recognize the image overlapping the ink layer and cannot be identified during monochrome copying. An anti-copying area consisting of a predetermined color that is output to the image is formed.

  As a result, the user can easily read the images and characters output on the paper superimposed on the copy-prevention area, and the images and characters in the copy-prevention area cannot be read when monochrome copying is performed. Unauthorized copying and unauthorized copying can be reliably prevented. Further, it is not necessary to use special paper or ink, and it is not necessary to provide a special detection function on the copying machine side, so that it is possible to provide an image forming apparatus capable of preventing unauthorized copying at a simple and low cost. .

  In addition, in an electrophotographic image forming apparatus, an ink application unit is disposed on the downstream side of the fixing unit, and the color ink is applied onto the paper on which the image is fixed by the fixing unit, thereby preventing unauthorized copying by applying the color ink. There is no possibility that the image quality of the toner image is deteriorated during the processing. Further, if the ink application means is an ink jet apparatus, a copy prevention region having a uniform ink application thickness can be formed, and there is no possibility of causing a reduction in image visibility and copy prevention effect due to uneven application of ink.

  In addition, a storage means for storing complementary color data is provided, and image data of the same color as the predetermined color existing in the copy prevention area is converted to complementary color data before image output by the data conversion means. There is no possibility of impairing the visibility of the original image even if there are images and characters.

  The present invention also provides a data input means for inputting image data, a data conversion means for converting image data input by the data input means into write data, and a color image is output on a sheet based on the write data. In an image forming apparatus comprising: an image forming unit; an input unit that inputs whether or not to execute an illegal copy prevention process on an output image; and a predetermined color that can be identified, and a predetermined unit for monochrome copying Storage means for storing complementary color data that is output indistinguishably from a color, and when the execution of illegal copy prevention processing is input from the input means, the image forming means copies a predetermined color. In addition to forming the prevention area at the same time as the image output, the data conversion means converts the image data of the same color as the predetermined color existing in the copy prevention area to the complementary color data before the image output. To be converted into.

  As a result, it is not necessary to separately provide a means for forming the copy prevention area, which contributes to simplification of the structure of the image forming apparatus and cost reduction. Further, when a similar color image exists in the copy prevention area, the similar color image is converted into a complementary color that can be identified in the original image and cannot be distinguished from the copy prevention area in monochrome copying. Further, the visibility of images and characters in the copy prevention area in the original image can be further enhanced.

  Also, by converting all the images in the copy prevention area to complementary colors before image output, even if the copy prevention area is not completely blacked out during monochrome copying, the image in the copy prevention area cannot be identified. While ensuring the visibility of the original image, ensure the effect of preventing unauthorized copying during monochrome copying.

  Further, by forming the copy prevention area in an area of 1/2 or more on the paper, the illegal copy prevention effect is further ensured.

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. These are diagrams showing an image provided with a copy prevention area and a state in which the image is copied in monochrome. FIG. 5 is a diagram illustrating a case where image data of similar colors existing in a copy prevention area is output without being converted and a case where image data is converted and output. These are diagrams showing a case where only image data of similar colors existing in the copy prevention area is converted and a case where all image data are converted. These are the flowcharts which show the image formation procedure by the image forming apparatus of 1st Embodiment. FIG. 5 is a flowchart showing another example of an image forming procedure by the image forming apparatus of the first embodiment. These are the schematic diagrams which show the whole structure of the image forming apparatus which concerns on 2nd Embodiment of this invention. These are block diagrams which show the structure of the image forming apparatus of 2nd Embodiment. These are the flowcharts which show the image formation procedure by the image forming apparatus of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus P, Pa-Pd Image forming part 2a-2d Charging apparatus 3a-3d Developing apparatus 5, 5a-5d Photosensitive drum 7 Exposure apparatus 10 Paper feed mechanism 14 Fixing part 17a-17d LED head 21 Paper 25 Data input Means 26 Data conversion means 27 Control means 28 Operation panel (input means)
29 Storage means 30 Ink application means 31 Copy prevention area

Claims (7)

Data input means for inputting image data, data conversion means for converting image data input by the data input means into writing data, and image forming means for outputting an image on a sheet based on the writing data In the provided image forming apparatus,
Input means for inputting whether or not unauthorized copy prevention processing is executed on an output image, and ink application means for applying color ink onto paper before or after image output by the image forming means are provided. And
When the execution of unauthorized copy prevention processing is input from the input means, the ink application means is capable of visually recognizing an image superimposed on the ink layer, and a copy prevention area composed of a predetermined color that is output indistinguishable during monochrome copying. Forming an image forming apparatus.   The image forming means includes a photoconductor, a charging device for charging the photoconductor, an exposure device for exposing the surface of the photoconductor charged by the charging device to form an electrostatic latent image, and the electrostatic latent image. A developing device that develops the image to form a toner image, an image transfer unit that transfers the toner image formed by the image forming unit onto a sheet, and the image transfer unit 2. The image according to claim 1, further comprising: a fixing unit that fixes the image on the paper, wherein the ink application unit applies color ink onto the paper on which the image is fixed by the fixing unit. Forming equipment.   The image forming apparatus according to claim 1, wherein the ink application unit is an ink jet apparatus.   Storage means is provided for storing complementary color data that can be identified with respect to the predetermined color and that cannot be distinguished from the predetermined color during monochrome copying, and the data conversion means includes the copy prevention area. 4. The image forming apparatus according to claim 1, wherein image data having a color similar to the predetermined color existing therein is converted into the complementary color data before image output. 5. Data input means for inputting image data, data conversion means for converting image data input by the data input means into write data, image forming means for outputting a color image on paper based on the write data, In an image forming apparatus comprising:
Input means for inputting whether or not to execute unauthorized copy prevention processing on the output image, and complementary color data that can be identified for a predetermined color and that cannot be distinguished from the predetermined color during monochrome copying Storage means for storing
When the execution of illegal copy prevention processing is input from the input means, the image forming means forms the copy prevention area of the predetermined color simultaneously with the image output, and the data conversion means An image forming apparatus that converts image data of the same color as the predetermined color existing in the image into the complementary color data before outputting the image.   6. The image forming apparatus according to claim 4, wherein the data conversion unit converts all image data in the copy prevention area into the complementary color data before outputting the image.   The image forming apparatus according to claim 1, wherein the copy prevention area is formed in a half or more area on a sheet.

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