Printing inspection device and printing inspection program

Abstract

To reduce the amount of data to be compared as compared with the case of comparing preceding print data, subsequent print data, and an image printed on a printing medium that has already undergone an additional printing process when detecting a defect in the additional printing process for printing a subsequent image based on the subsequent print data on a printing medium on which the preceding image based on the preceding print data has been printed by a comparison process for comparing the print data with the image printed on the printing medium.SOLUTION: In an additional printing process, a subsequent image is printed in a specific color that is not used in a preceding image. An image detection unit 74 detects a subsequent image from a printing medium 22 after additional printing by using a color sensor 64 for detecting the specific color. A defect detection unit 76 detects a defect in the additional printing process by comparing the detected subsequent image with the subsequent print data.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an overprinting inspection device and an overprinting inspection program. [Background technology]

[0002] Conventionally, a process is performed in which an image is printed on a printing medium on which an image has already been printed. This type of printing process is called "overprinting process." In this specification, the printing medium on which an image has been printed and before the overprinting process is called the "pre-overprinting printing medium," the image printed on the pre-overprinting printing medium is called the "previous image," and the printing medium that has been overprinted is called the "post-overprinting printing medium." In addition, the image printed on the post-overprinting printing medium is called the "post-overprinting image." If the overprinting process is performed appropriately, the post-overprinting image is an image that combines the previous image and the following image.

[0003] Meanwhile, conventionally, after executing a printing process in which print data is printed on a printing medium, the print data is compared with an image obtained by optically reading the print medium after the printing process (i.e., the image printed on the printing medium) to detect defects in the printing process. For example, if the degree of match between the print data and the image is equal to or greater than a predetermined threshold, it can be determined that the printing process is "good," and if the degree of match between the print data and the image is less than the threshold, it can be determined that the printing process is "bad." Defects in the printing process include, for example, defects in the process of converting print data into a raster format (data corruption) and defects in the process of printing the print data on a printing medium (fainting, smudges, etc.).

[0004] Here, as shown in Figure 12, consider a case in which a preceding image forming device prints a preceding image based on preceding print data, and a subsequent image forming device performs an overprinting process to print a subsequent image based on subsequent print data on the pre-overprinting printing medium, and an overprinting inspection device detects defects in the overprinting process.

[0005] In the overprinting process in the subsequent image forming device, the subsequent print data is subsequent print data showing a subsequent image (an image of a batter in the example of FIG. 12), and on the print medium after the overprinting, not only the subsequent image but also the preceding image (the number "1" in the example of FIG. 12) is printed. In other words, even if the overprinting process is performed correctly, the subsequent print data and the overprinted image will be different.

[0006] Therefore, the overprinting inspection device cannot adequately detect defects in the overprinting process by simply comparing the subsequent print data with the overprinted image.

[0007] In light of this, Patent Document 1 discloses an image inspection device that generates an inspection image in which the pre-printed elements printed on the pre-printed paper are reduced based on a pre-printed paper image obtained by imaging the pre-printed paper as the printing medium before the overprinting, and a post-overprinting image obtained by imaging the printing medium after the overprinting, and detects defects in the overprinting process by comparing the generated inspection image with additional recorded data as the subsequent printing data. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-70548 A Summary of the Invention [Problem to be solved by the invention]

[0009] By the way, as an example of the method disclosed in Patent Document 1, when detecting defects in the overprinting process by a comparison process that compares the print data with the image printed on the printing medium, it is possible to make a comparison using three data, namely, the preceding print data, the subsequent print data, and the overprinted image. For example, it is possible to compare the combined data obtained by combining the preceding print data and the subsequent print data with the overprinted image. It is also possible to compare image data obtained by subtracting the preceding print data from the overprinted image with the subsequent print data. Alternatively, it is possible to compare image data obtained by subtracting the subsequent print data from the overprinted image with the preceding print data.

[0010] However, when comparing the preceding print data, the subsequent print data, and the after-print image, a problem may occur in that the amount of data to be compared is larger than when comparing the subsequent image and the subsequent print data. When the amount of data to be compared is larger, problems such as a larger processing volume for the comparison process may occur.

[0011] The object of the present invention is to reduce the amount of data subject to comparison processing when detecting defects in an overprinting process in which a subsequent image based on subsequent print data is printed on a printing medium on which a previous image based on previous print data has already been printed, by a comparison process that compares print data with an image printed on a printing medium, compared to a case in which the previous print data, subsequent print data, and the image printed on the printing medium on which the overprinting process has already been performed are compared. [Means for solving the problem]

[0012] The invention according to claim 1 includes a processor, and the processor detects defects in the overprinting process by comparing the subsequent image detected from the overprinted print medium formed by the overprinting process in which a subsequent image based on subsequent print data is printed on a pre-overprinting print medium on which a previous image based on the previous print data is printed with the subsequent print data. death , When the preceding image and the succeeding image overlap on the overprinted printing medium, a defect in the overprinting process is detected by comparing the preceding print data, the succeeding print data, and the image printed on the overprinted printing medium. The above-mentioned feature of the overprint inspection device is as follows. The invention of claim 2 is the overprinting inspection device described in claim 1, characterized in that in the overprinting process, the subsequent image is printed in a specific color not used in the preceding image, and the subsequent image is detected from the printed medium after the overprinting by a sensor that detects the specific color. The invention according to claim 3 is the overprinting inspection device according to claim 1 or 2, characterized in that the subsequent image is an image detected from a specific area, which is an area on the overprinted print medium where the subsequent image is to be printed, specified based on the subsequent print data. 。 request request 4 In the present invention, image data obtained by optically reading the pre-printed print medium is used as the pre-print data. 1 2 is a printing inspection device according to the first embodiment. Claim 5 In the invention according to the present invention, a plurality of pages of the pre-printing print medium are formed by the pre-printing process based on the subsequent print data for the plurality of pages, and the processor detects a defect in the pre-printing process by comparing the subsequent image detected from the page with the subsequent print data for a page where the preceding image and the subsequent image do not overlap, and detects a defect in the pre-printing process by comparing the subsequent image detected from the page with the subsequent print data for a page where the preceding image and the subsequent image overlap. Pre-print data , the above Subsequent print data and detecting defects in the overprinting process by comparing the image printed on the printing medium after the overprinting. 1 or 4 2 is a printing inspection device according to the first embodiment. Claim 6 The invention relates to a computer that detects defects in an overprinting process by comparing a subsequent image detected from a post-overprinting print medium formed by an overprinting process in which a subsequent image based on subsequent print data is printed on a pre-overprinting print medium on which a previous image based on previous print data has been printed with the subsequent print data. and when the preceding image and the succeeding image overlap on the overprinted printing medium, a defect in the overprinting process is detected by comparing the preceding print data, the succeeding print data, and the image printed on the overprinted printing medium. The above-mentioned feature of the present invention is an overprinting inspection program. Effect of the Invention

[0013] Claim 1 or 6 According to the invention, when detecting defects in an overprinting process in which a subsequent image based on subsequent print data is printed on a printing medium on which a previous image based on the previous print data has already been printed, a comparison process that compares print data with an image printed on a printing medium can reduce the amount of data subject to the comparison process compared to when comparing the previous print data, the subsequent print data, and the image printed on the printing medium on which the overprinting process has already been performed. According to the invention as set forth in claim 2, the subsequent image can be detected from the print medium after overprinting by a sensor that detects a specific color. According to the invention of claim 3, the subsequent image can be detected from a specific area of ​​the print medium after overprinting. 。 request request 4 According to the present invention, a pre-printing print medium reading section can acquire a preliminary image. Claim 5 According to the invention, for pages where the preceding image and subsequent image do not overlap, defects in the overprinting process can be detected by comparing the subsequent image with subsequent print data, and for pages where the preceding image and subsequent image overlap, defects in the overprinting process can be detected by comparing the preceding image, the subsequent image, and the image printed on the printing medium after overprinting. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of an overprinting system according to an embodiment of the present invention. [Diagram 2] 1 is a schematic diagram illustrating the configuration of a print control device according to an embodiment of the present invention. [Figure 3A] 6A and 6B are diagrams illustrating an example of the contents of advance print data. [Figure 3B] FIG. 13 is a diagram showing an example of a pre-printed printed medium. [Figure 4A] FIG. 11 is a diagram showing an example of the contents of subsequent print data. [Figure 4B] FIG. 13 is a diagram showing an example of a printed medium after overprinting. [Diagram 5] FIG. 13 is a conceptual diagram showing a specific area where a subsequent image is printed. [Figure 6] FIG. 1 is a schematic diagram illustrating the configuration of an overprinting inspection device according to an embodiment of the present invention. [Figure 7] FIG. 13 is a diagram showing a subsequent image detected from a print medium after overprinting. [Figure 8] 13A and 13B are diagrams illustrating other examples of the contents of subsequent print data. [Figure 9] 13A and 13B are diagrams illustrating other examples of printed media after overprinting. [Figure 10] 5 is a flowchart showing a process flow of the print control device according to the embodiment. [Figure 11] 4 is a flowchart showing a process flow of the overprinting inspection device according to the present embodiment. [Figure 12] FIG. 1 is a diagram showing a conventional overprinting process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] FIG. 1 is a schematic diagram of an overprinting system 10 according to the present embodiment. The overprinting system 10 is a system that performs overprinting processing and detects defects in the overprinting processing. The overprinting system 10 is installed, for example, in a printing company that performs production print processing, although this is not limited thereto. As shown in FIG. 1, the overprinting system 10 includes a print control device 12, a preceding image forming device 14, a subsequent image forming device 16, and an overprinting inspection device 18. The print control device 12 and the preceding image forming device 14, the print control device 12 and the subsequent image forming device 16, and the print control device 12 and the overprinting inspection device 18 are each connected to be able to communicate with each other.

[0016] The print control device 12 is a device that controls the preceding image forming device 14, the subsequent image forming device 16, and the overprinting inspection device 18. In other words, the print control device 12 is a device that controls the overprinting process and the process of detecting defects in the overprinting process. The print control device 12 also serves as an interface with the user of the overprinting system 10 (i.e., the user). Details of the print control device 12 will be described later with reference to FIG. 2 etc.

[0017] Both the preceding image forming device 14 and the subsequent image forming device 16 are printers. Specifically, each of the preceding image forming device 14 and the subsequent image forming device 16 includes a receiving unit that receives a print request (i.e., a print job) from the print control device 12, a transport unit that transports a print medium such as paper, a conversion unit that converts non-raster format print data included in the print job into a raster format (a format that can be recognized by a printing unit described later), and a printing unit that prints an image on the print medium according to the print data.

[0018] Here, the flow of the overprinting process in the overprinting system 10 will be described. First, the print control device 12 transmits a preceding print job including preceding print data indicating a preceding image to the preceding image forming device 14, and transmits a subsequent print job including subsequent print data indicating a subsequent image to the subsequent image forming device 16. The preceding image forming device 14 prints the preceding image on the print medium based on the preceding print job. The print medium on which the preceding image is printed is the pre-overprinting print medium 20. The pre-overprinting print medium 20 is conveyed to the subsequent image forming device 16 by the user or by the conveying unit of the preceding image forming device 14. Next, the subsequent image forming device 16 prints the subsequent image on the pre-overprinting print medium 20 based on the subsequent print job. In other words, the subsequent image forming device 16 executes the overprinting process. The print medium on which the preceding image and the subsequent image are printed is the post-overprinting print medium 22. The post-imprint print medium 22 is transported to the post-imprint inspection device 18 by a user or by a transport section of the subsequent image forming device 16 .

[0019] The overprinting inspection device 18 detects defects in the overprinting process performed by the subsequent image forming device 16. The structure of the overprinting inspection device 18 and the details of the defect detection process by the overprinting inspection device 18 will be described later. The overprinting inspection device 18 may detect defects in the printing process by the preceding image forming device 14 prior to detecting defects in the overprinting process. Specifically, the overprinting inspection device 18 may detect defects in the printing process by the preceding image forming device 14 by comparing the preceding print data with a preceding image obtained by optically reading the pre-overprinting print medium 20 (for example, by scanning with a scanner or photographing with a camera).

[0020] 2 is a schematic diagram of the configuration of the print control device 12. The print control device 12 may be any device as long as it performs the functions described below. For example, the print control device 12 may be a computer provided in association with the preceding image forming device 14, the subsequent image forming device 16, and the overprinting inspection device 18. Alternatively, the print control device 12 may be a server computer capable of communicating with the preceding image forming device 14, the subsequent image forming device 16, the overprinting inspection device 18, and a user terminal used by a user.

[0021] The communication interface 30 is configured to include, for example, a network adapter, or a dedicated adapter that connects the print control device 12 to other devices (the preceding image forming device 14, the subsequent image forming device 16, and the overprinting inspection device 18). The communication interface 30 performs a function of communicating with other devices. For example, the communication interface 30 receives a print job from a user terminal used by a user of the overprinting system 10. The communication interface 30 also transmits print data to the preceding image forming device 14 and the subsequent image forming device 16. The communication interface 30 also transmits inspection instruction information (described in detail later) related to the inspection of the overprinting process to the overprinting inspection device 18. The communication interface 30 also receives the inspection result of the overprinting process from the overprinting inspection device 18.

[0022] The input interface 32 includes, for example, buttons, a touch panel, etc. The input interface 32 is used to input instructions from a user of the overprinting system 10 to the print control device 12.

[0023] The display 34 includes, for example, a liquid crystal display, etc. The display 34 displays various information related to the overprinting system 10. For example, the display 34 displays the inspection results of the overprinting process by the overprinting inspection device 18, etc.

[0024] The memory 36 includes, for example, a hard disk drive (HHD), a solid state drive (SSD), a read only memory (ROM), or a random access memory (RAM). The memory 36 may be provided separately from a processor 38 described below, or at least a part of the memory 36 may be provided inside the processor 38. A print control program for operating each part of the print control device 12 is stored in the memory 36. In addition, the memory 36 temporarily holds print jobs input by a user.

[0025] The print job according to the present embodiment includes print data indicating an image to be printed. As described above, the data format of the print data included in the print job sent by the print control device 12 is a non-raster format that cannot be recognized by the preceding image forming device 14 and the subsequent image forming device 16. The print data is converted to a raster format by the preceding image forming device 14 or the subsequent image forming device 16, and an image corresponding to the print data is printed on a print medium. The print job includes a preceding print job for the preceding image forming device 14 and a subsequent print job for the subsequent image forming device 16. The preceding print job includes preceding print data indicating a preceding image, and the subsequent print job includes subsequent print data indicating a subsequent image. Examples of the contents of the preceding print data include, but are not limited to, a frame line or a ruled line. Examples of the contents of the subsequent print data include, but are not limited to, letters or numbers within a frame line or along a ruled line. In addition, the content of the preceding print data may be an image of a first color, and the content of the subsequent print data may be an image of a second color different from the first color, i.e., the preceding image and the subsequent image may be printed in different colors. Note that in this specification, when there is no particular distinction between the preceding print data and the subsequent print data, they are collectively referred to as "print data."

[0026] The processor 38 refers to a processing device in a broad sense, and includes at least one of a general-purpose processing device (e.g., a central processing unit (CPU)) and a dedicated processing device (e.g., a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a programmable logic device). The processor 38 may not be a single processing device, but may be configured by the cooperation of multiple processing devices located at physically separate locations. As shown in FIG. 2, the processor 38 performs the functions of a print instruction unit 40, an inspection instruction unit 42, an overlap determination unit 44, and a data combination unit 46 according to a print control program stored in the memory 36.

[0027] The print instruction unit 40 transmits a print job including print data to the preceding image forming device 14 and the subsequent image forming device 16. Specifically, the print instruction unit 40 transmits a preceding job including preceding print data indicating a preceding image to the preceding image forming device 14, and transmits a subsequent job including subsequent print data indicating a subsequent image to the subsequent image forming device 16.

[0028] FIG. 3A is a diagram showing an example of the contents of the preceding print data. In the example of FIG. 3A, the preceding print job is an instruction to print six pages of a print medium, and the preceding print data represents six pages of preceding images. In the example of FIG. 3A, the contents of the preceding print data include the characters "1" to "6" to be printed on the first to sixth pages, respectively. The contents of the preceding print data do not have to represent multiple pages of preceding images, and may represent a single page of preceding images.

[0029] Fig. 3B is a diagram showing a pre-printing print medium 20 on which a preceding image is printed by the preceding image forming device 14 based on a preceding print job including the preceding print data shown in Fig. 3A. In this example, since the preceding print data represents six pages of preceding images, the pre-printing print medium 20 also consists of six pages, and the characters "1" to "6" are printed on the first to sixth pages, respectively, as preceding images. Of course, if the content of the preceding print data represents a preceding image for a single page, the pre-printing print medium 20 will also be a single page.

[0030] In this example, the preceding image is to be printed in black. Specifically, black and white printing may be specified in the print settings of the preceding print job, or the color of the preceding image itself indicated by the preceding print data may be black.

[0031] As can be seen by comparing Figures 3A and 3B, if the preceding image forming device 14 correctly executes the printing process based on the preceding print job, the contents of the preceding print data (the image represented by the preceding print data) will match the preceding image printed on the pre-printing printing medium 20.

[0032] 4A is a diagram showing an example of the contents of subsequent print data. As described above, in this example, since the preceding print job instructs to print six pages, the subsequent print job also instructs to print six pages. Therefore, the subsequent print data represents six pages of subsequent images. If the preceding print job instructs to print a single page, the subsequent print job may also instruct to print a single page.

[0033] In the example of Fig. 4A, the content of the subsequent print data includes an image of a batter to be printed in the upper right corner of pages 1, 3, and 5. No image is included on pages 2, 4, and 6. That is, in the example of Fig. 4A, the subsequent print data indicates that an image of a batter is to be printed only on pages 1, 3, and 5, and that nothing is to be printed on pages 2, 4, and 6.

[0034] Fig. 4B is a diagram showing an after-printing print medium 22 in which a subsequent image is printed on the before-after-printing print medium 20 shown in Fig. 3B by an after-printing process by the subsequent image forming device 16 based on a subsequent print job including the subsequent print data shown in Fig. 4A. As shown in Fig. 4B, in the after-printing print medium 22, the characters "1", "3", or "5" which are the preceding images and the image of the batter which is the subsequent image are printed on the first, third, and fifth pages as the after-printing images, and only the characters "2", "4", or "6" which are the preceding images are printed on the second, fourth, and sixth pages as the after-printing images.

[0035] In this embodiment, in the overprinting process, the subsequent image is printed in a color (referred to as a "specific color" in this specification) that is not used in the preceding image. Specifically, color printing is specified in the print settings of the subsequent print job, and the color of the subsequent image itself indicated by the subsequent print data is the specific color. In this example, as described above, the preceding image is printed in black, so the subsequent image is printed in a color other than black. For example, the subsequent image is printed in red. The specific color may also be multiple colors. For example, if the preceding image is printed in black, the subsequent image may be printed in multiple specific colors other than black (e.g., red, blue, yellow, etc.).

[0036] In addition, when the preceding image is printed using multiple colors, the subsequent image is printed in a specific color other than the multiple colors used in the preceding image. For example, when the preceding image is printed in two colors, black and red, the subsequent image is printed in blue as a specific color. Also, when the post-printing print medium 22 is composed of multiple pages as in this example, the subsequent images of each page do not have to be printed in the same color as each other as long as they are specific colors. For example, when the preceding image is printed in black, the subsequent image of the first page may be printed in red, the subsequent image of the third page may be printed in blue, and the subsequent image of the fifth page may be printed in yellow. In this case, the color of the subsequent image of each page may be multiple specific colors.

[0037] As can be seen by comparing Figures 4A and 4B, in the case of the overprinted printing medium 22 on which the preceding image and the subsequent image are printed (pages 1, 3, and 5 in Figure 4B), even if the subsequent image forming device 16 correctly executes the printing process based on the subsequent print job, the contents of the subsequent print data (the image represented by the subsequent print data) and the overprinted image printed on the overprinted printing medium 22 do not match.

[0038] Returning to Figure 2, the inspection instruction unit 42 causes the overprinting inspection device 18 to perform the overprinting process by transmitting inspection information, which is information necessary for inspecting the overprinting process, and an inspection instruction for the overprinting process to the overprinting inspection device 18.

[0039] In this embodiment, the inspection instruction unit 42 transmits, as the inspection information, specific color information indicating the specific color in which the subsequent image is printed to the overprint inspection device 18. The inspection instruction unit 42 can identify the specific color by analyzing the subsequent print data. Alternatively, when the user inputs the specific color from the input interface 32, the inspection instruction unit 42 can identify the specific color based on the user input.

[0040] When the subsequent image is printed in multiple colors, the specific color information indicates multiple specific colors. When the overprinted print medium 22 is composed of multiple pages and the subsequent images of each page have different specific colors, the inspection instruction unit 42 transmits information that associates the page number of the overprinted print medium 22 with the specific color used to print the subsequent image of the page as specific color information to the overprint inspection device 18.

[0041] Furthermore, instead of or in addition to the above-mentioned specific color information, the inspection instruction unit 42 may transmit, as the inspection information, specific area information indicating a specific area, which is an area where a subsequent image is printed on the post-overprinting print medium 22, to the overprinting inspection device 18. The inspection instruction unit 42 can identify the specific area by analyzing the subsequent printing data.

[0042] FIG. 5 is a conceptual diagram showing a specific region 50. The subsequent print data includes information indicating not only the shape and color of the subsequent image, but also the printing position of the subsequent image on the overprinted print medium 22. For example, if the subsequent print data is as shown in FIG. 4A, as described above, the subsequent print data indicates that the subsequent image is printed in the upper right corner regions of the first, third, and fifth pages of the overprinted print medium 22. Therefore, the inspection instruction unit 42 can specify the upper right corner regions of the first, third, and fifth pages of the overprinted print medium 22 as the specific region 50 based on the subsequent print data.

[0043] When multiple subsequent images are printed at a distance from each other within one page of the overprinted print medium 22, the specific area indicated by the specific area information may be multiple areas within one page. When the overprinted print medium 22 is composed of multiple pages and the subsequent images of each page are printed in different areas, the inspection instruction unit 42 transmits information associating the page number of the overprinted print medium 22 with the specific area 50 in which the subsequent image is printed on that page as specific area information to the overprint inspection device 18.

[0044] When the inspection instruction unit 42 transmits specific area information instead of specific color information as inspection information to the overprint inspection device 18, the subsequent image does not need to be printed in the specific color.

[0045] The overlap determination unit 44 and the data combination unit 46 will be described later.

[0046] 6 is a schematic diagram of the configuration of the overprinting inspection device 18. In this embodiment, the overprinting inspection device 18 is provided connected to the subsequent image forming device 16, but the overprinting inspection device 18 and the subsequent image forming device 16 may be provided separately and connected to each other so as to be able to communicate with each other. The overprinting inspection device 18 may be any device as long as it exhibits the functions described below.

[0047] The communication interface 60 is configured to include, for example, a network adapter, or a dedicated adapter that connects the overprinting inspection device 18 to other devices (particularly the subsequent image forming device 16 and the overprinting inspection device 18). The communication interface 60 exhibits a function of communicating with other devices. For example, the communication interface 60 receives the preceding print data and subsequent print data from the print control device 12. The communication interface 60 also receives the above-mentioned inspection information and inspection instructions from the print control device 12. Furthermore, the communication interface 60 receives the inspection results of the overprinting process from the print control device 12.

[0048] The scanner 62 includes, for example, a light source and a CCD image sensor. The scanner 62 optically reads the overprinted print medium 22 on which the overprinted image is printed, and acquires read image data representing the overprinted image (hereinafter, referred to as "overprinted image data"). In order to acquire the overprinted image data from the overprinted print medium 22, a camera that photographs the overprinted print medium 22 may be provided in the overprint inspection device 18 instead of the scanner 62.

[0049] The color sensor 64 is a sensor capable of detecting a predetermined color. A photoelectric sensor can be used as the color sensor 64. The photoelectric sensor may be capable of setting the color to be detected. Alternatively, a plurality of photoelectric sensors capable of detecting one color may be provided, and only the photoelectric sensor that detects the set color may be operated to make it possible to detect the set color. Such a photoelectric sensor may be capable of directly sensing the overprinted print medium 22. In that case, it is not necessary to obtain the overprinted image data by the scanner 62. In addition, the color sensor 64 may be a color identification sensor having a color detection function that detects the color of each pixel of the overprinted image data. With such a color identification sensor, the color of each pixel can be identified, so that if the color to be detected is set, it is possible to detect only the pixels of the set color.

[0050] The memory 66 is configured to include, for example, a ROM or a RAM. The memory 66 may be provided separately from the processor 72 described below, or at least a part of the memory 66 may be provided inside the processor 72. The memory 66 stores an overprinting inspection program for operating each part of the overprinting inspection device 18. The memory 66 also temporarily holds the overprinted image data acquired by the scanner 62.

[0051] The OK tray 68 and the NG tray 70 are trays onto which the overprinted printed medium 22 is discharged after the overprinting process inspection by the processor 72 described below. The overprinted printed medium 22 that is determined to be "good" as a result of the overprinting process inspection is discharged to the OK tray 68, and the overprinted printed medium 22 that is determined to be "defective" as a result of the overprinting process inspection is discharged to the NG tray 70.

[0052] The processor 72 refers to a processing device in a broad sense, and includes at least one of a general-purpose processing device (e.g., a CPU, etc.) and a dedicated processing device (e.g., a GPU, an ASIC, an FPGA, or a programmable logic device, etc.). The processor 72 may not be a single processing device, but may be configured by the cooperation of multiple processing devices located at physically separate locations. As shown in FIG. 6, the processor 72 functions as an image detection unit 74 and a defect detection unit 76 by the overprint inspection program stored in the memory 66.

[0053] The image detection unit 74 performs a process of detecting a subsequent image from the overprinted print medium 22 based on the inspection information received from the print control device 12 .

[0054] First, a case where the above-mentioned specific color information is received from the print control device 12 as the inspection information will be described. As described above, the specific color indicated by the specific color information received from the print control device 12 is the color of the subsequent image. Therefore, the image detection unit 74 sets the color detected by the color sensor 64 to the color indicated by the specific color information, and then detects the specific color from the after-printing image data acquired by the scanner 62 or directly from the after-printing print medium 22 by the color sensor 64. This makes it possible to detect the subsequent image. For example, if the after-printing print medium 22 is as shown in FIG. 4B, the characters "1" to "6" which are the preceding image are printed in a color other than the specific color (e.g., black), and the image of the batter which is the subsequent image is printed in a specific color (e.g., red). By setting the color detected by the color sensor 64 to the specific color, only the subsequent image is detected as shown in FIG. 7.

[0055] When the specific color information indicates a plurality of colors, i.e., when the subsequent image is printed in a plurality of colors, the image detection unit 74 can detect the subsequent image from the overprinted print medium 22 by setting the colors detected by the color sensor 64 to the plurality of colors. Also, when the specific color information is information in which the page number of the overprinted print medium 22 is associated with a specific color, i.e., when the overprinted print medium 22 is composed of a plurality of pages and the subsequent images of each page have different specific colors, the image detection unit 74 can detect the subsequent image from each page of the overprinted print medium 22 by changing the specific color detected by the color sensor 64 for each page of the overprinted print medium 22 (or the overprinted image data) based on the specific color information.

[0056] When the above-mentioned specific area information is received from the print control device 12 as the inspection information, the image detection unit 74 cuts out and extracts the specific area 50 (see FIG. 5) indicated by the specific area information from the overprinted image data acquired by the scanner 62. This makes it possible to detect the subsequent image. Also, when the specific area information is information in which the page number of the overprinted print medium 22 is associated with the specific area 50, that is, when the overprinted print medium 22 is composed of multiple pages and the subsequent images of each page are printed in different areas, the image detection unit 74 can detect the subsequent image from each page of the overprinted print medium 22 by cutting out the different specific areas 50 for each page of the overprinted image data based on the specific area information.

[0057] Furthermore, when the specific color information and the specific area information are received from the print control device 12 as the inspection information, the image detection unit 74 detects the subsequent image by having the color sensor 64 detect the specific color from the specific area 50 of the overprinted print medium 22 or the overprinted image data. This makes it possible to reduce the amount of processing required for the detection of the subsequent image, compared to the case where the entire overprinted print medium 22 or the overprinted image data is sensed by the color sensor 64. In addition, it is possible that the specific area 50 includes at least a part of an image other than the subsequent image (i.e., the preceding image), and by detecting the specific color from the specific area 50 by the color sensor 64, at least a part of the preceding image can be excluded, so that the subsequent image can be detected with higher accuracy, compared to the case where the specific area 50 of the overprinted image data is simply cut out and detected as the subsequent image.

[0058] By the above-mentioned processing by the image detection unit 74, a subsequent image as shown in Fig. 7 is detected from the after-printing print medium 22. As can be seen by comparing Fig. 4A with Fig. 7, as long as the after-printing processing is properly performed in the subsequent image forming device 16, the subsequent print data and the subsequent image detected from the after-printing print medium 22 match.

[0059] The defect detection unit 76 detects defects in the overprinting process in the subsequent image forming device 16 by comparing the subsequent image detected by the image detection unit 74 with the subsequent print data. The subsequent print data can be acquired from the print control device 12 or the subsequent image forming device 16. The defect detection unit 76 converts the subsequent print data acquired from the print control device 12 or the subsequent image forming device 16 into a raster format, and compares the subsequent print data in the raster format with the subsequent image detected by the image detection unit 74. Alternatively, the defect detection unit 76 may acquire the subsequent print data converted into the raster format from the subsequent image forming device 16.

[0060] A known method can be used as a specific method for comparing the subsequent image with the subsequent print data. For example, pattern matching may be performed between the subsequent image and the subsequent print data to detect the difference. Alternatively, features (such as edges) may be detected from each of the subsequent image and the subsequent print data, and the detected features may be compared. Alternatively, pixel values ​​(such as brightness values ​​and color values) of pixels in the subsequent image may be compared with pixel values ​​of corresponding pixels in the subsequent print data.

[0061] As described above, if the overprinting process is performed appropriately in the subsequent image forming device 16, the subsequent print data should match the subsequent image detected from the overprinted print medium 22. Therefore, if the similarity between the detected subsequent image and the subsequent print data is equal to or greater than a predetermined threshold, the defect detection unit 76 can determine that the overprinting process for the overprinted print medium 22 is "good." On the other hand, if the similarity between the detected subsequent image and the subsequent print data is less than a predetermined threshold, the defect detection unit 76 can determine that the overprinting process for the overprinted print medium 22 is "bad."

[0062] When the overprinted print medium 22 is composed of multiple pages, the defect detection unit 76 compares the subsequent image detected by the image detection unit 74 with the subsequent print data for each page. Specifically, the defect detection unit 76 compares the subsequent image detected from a certain page of the overprinted print medium 22 with the subsequent print data corresponding to that page. This allows the defect detection unit 76 to detect defects in the overprint process for each page.

[0063] The overprinted printed medium 22 (or a page of the overprinted printed medium 22) that is determined to be “good” by the defect detection unit 76 is discharged to the OK tray 68. The overprinted printed medium 22 (or a page of the overprinted printed medium 22) that is determined to be “bad” by the defect detection unit 76 is discharged to the NG tray 70.

[0064] Furthermore, the defect detection unit 76 transmits information indicating the inspection result of the overprinting process to the print control device 12. The processor 38 of the print control device 12 notifies the user of the inspection result by, for example, displaying it on the display 34.

[0065] According to the present embodiment described above, the data to be subjected to the comparison process for detecting defects in the overprinting process is only the subsequent image and subsequent print data detected from the overprinted print medium 22. Therefore, compared to the conventional case where three pieces of data, the preceding print data, the subsequent print data, and the overprinted image, are compared, the amount of data to be subjected to the comparison process can be reduced. By reducing the data to be subjected to the comparison process, the amount of processing and the processing time of the comparison process are reduced, i.e., the amount of processing and the processing time of the overprinting process are reduced.

[0066] The overlap determination unit 44 and the data combining unit 46 (see FIG. 2) of the print control device 12 will be described below.

[0067] The overlap determination unit 44 determines whether or not the preceding image and the succeeding image overlap on the post-printing printing medium 22 when the overprinting process is performed using the preceding print data and the succeeding print data, based on the preceding print data and the succeeding print data. In other words, the overlap determination unit 44 determines whether or not the succeeding image is printed overlapping on the preceding image in the overprinting process. The preceding print data has information indicating the shape and printing position of the preceding image on the pre-overprinting printing medium 20, and the succeeding print data has information indicating the shape and printing position of the succeeding image on the post-overprinting printing medium 22. Therefore, the overlap determination unit 44 can determine whether or not the preceding image and the succeeding image overlap on the post-overprinting printing medium 22, based on the preceding print data and the succeeding print data.

[0068] When the overprinted print medium 22 is composed of multiple pages, the overlap determination unit 44 determines whether the preceding image and the subsequent image overlap for each page. For example, when the preceding print data and the pre-overprinted print medium 20 are as shown in Fig. 3A and Fig. 3B, respectively, and the subsequent print data is as shown in Fig. 8, the overprinted print medium 22 will be as shown in Fig. 9. In this case, the overlap determination unit 44 determines that the preceding image and the subsequent image do not overlap on pages 1, 2, 5, and 6 of the overprinted print medium 22, but that the preceding image and the subsequent image overlap on pages 3 and 6 of the overprinted print medium 22.

[0069] When the overlap determination unit 44 determines that the preceding image and the subsequent image overlap on the overprinted printing medium 22, the data combining unit 46 combines the preceding print data with the subsequent print data to generate combined data. Combining the preceding print data with the subsequent print data means that the combined data represents an overprinted image in which the preceding image indicated by the preceding print data and the subsequent image indicated by the subsequent print data are aligned and overlapped. When the overprinted printing medium 22 is composed of multiple pages, the data combining unit 46 generates combined data only for pages where the preceding image and the subsequent image overlap, and does not need to generate combined data for pages where the preceding image and the subsequent image do not overlap. For example, when the after-printing printing medium 22 is as shown in FIG. 9, the data combination unit 46 does not generate combined data for pages 1, 2, 5, and 6 of the after-printing printing medium 22, but combines the third page of the preceding print data with the third page of the subsequent print data to generate combined data for the third page, and combines the fourth page of the preceding print data with the fourth page of the subsequent print data to generate combined data for the fourth page.

[0070] The data combining unit 46 transmits the generated combined data as inspection information to the overprinting inspection device 18. Furthermore, when the overprinted printed medium 22 is composed of a plurality of pages, the data combining unit 46 transmits the page number of the overprinted printed medium 22 in association with the combined data of the page to the overprinting inspection device 18. In this case, the inspection information for pages where the preceding image and the succeeding image do not overlap (pages 1, 2, 5, and 6 in FIG. 9) is at least one of the specific color information and specific area information described above, and the inspection information for pages where the preceding image and the succeeding image overlap (pages 3 and 4 in FIG. 9) is the combined data.

[0071] The defect detection unit 76 of the overprinting inspection device 18 detects defects in the overprinting process by comparing the subsequent image detected by the image detection unit 74 with the subsequent print data as described above when the preceding image and the subsequent image do not overlap on the overprinted printing medium 22, but detects defects in the overprinting process by comparing the preceding print data, subsequent print data, and the overprinted image when the preceding image and the subsequent image overlap on the overprinted printing medium 22. In this embodiment, the defect detection unit 76 detects defects in the overprinting process by comparing the combined data received from the print control device 12 with the overprinted image data acquired by the scanner 62 by optically reading the overprinted printing medium 22.

[0072] The comparison between the combined data and the post-printing image data can be performed in the same manner as the comparison between the subsequent image and the subsequent print data.

[0073] The defect detection unit 76 can determine that the overprinting process for the overprinted print medium 22 is "good" when the similarity between the combined data and the overprinted image data is equal to or greater than a predetermined threshold. On the other hand, the defect detection unit 76 can determine that the overprinting process for the overprinted print medium 22 is "bad" when the similarity between the combined data and the overprinted image data is less than a predetermined threshold.

[0074] Also, regarding the inspection information received from the print control device 12, a case will be considered in which the inspection information of some of the multiple pages of the overprinted print medium 22 is specific color information or specific area information, and the inspection information of the other pages is combined data, that is, a case in which the overprinted print medium 22 is composed of multiple pages, and the preceding image and the following image overlap only on some of the multiple pages. In this case, the defect detection unit 76 detects defects in the overprinting process by comparing the following image detected by the image detection unit 74 based on the specific color information or specific area information as inspection information with the following print data for pages in which the preceding image and the following image do not overlap. On the other hand, the defect detection unit 76 detects defects in the overprinting process by comparing the combined data as inspection information with the overprinted image data acquired by the scanner 62 for pages in which the preceding image and the following image overlap.

[0075] For example, if the post-overprinting printing medium 22 is as shown in Figure 9, the defect detection unit 76 detects defects in the overprinting process by comparing the subsequent image detected by the image detection unit 74 with the subsequent print data on the first, second, fifth, and sixth pages, since the preceding and subsequent images do not overlap, and by comparing the combined data with the post-overprinting image data on the third and fourth pages, since the preceding and subsequent images overlap.

[0076] In this embodiment, the method of comparing the preceding print data, the subsequent print data, and the after-print image is to compare the combined data of the preceding print data and the subsequent print data generated by the data combining unit 46 of the print control device 12 with the after-print image data, but this is not limited to this method. For example, the defect detection unit 76 may obtain the preceding print data and the subsequent print data from the print control device 12, and compare the difference image data obtained by subtracting the preceding print data from the after-print image data with the subsequent print data, or compare the difference image data obtained by subtracting the subsequent print data from the after-print image data with the preceding print data.

[0077] As described above, the image detection unit 74 of the overprinting inspection device 18 detects the subsequent image by detecting a specific color from the overprinted image data or the overprinted print medium 22. However, when the preceding image and the subsequent image overlap on the overprinted print medium 22, the color of the overlapping portion is not necessarily the specific color designated as the color for printing the subsequent image in the overprinting process. Therefore, when the preceding image and the subsequent image overlap on the overprinted print medium 22, the image detection unit 74 may not be able to appropriately detect the subsequent image by detecting a specific color from the overprinted print medium 22.

[0078] Furthermore, even when the image detection unit 74 detects the subsequent image by cutting out a specific region 50 (see FIG. 5) from the after-printing image data, if the preceding image and the subsequent image overlap in the after-printing print medium 22, not only the subsequent image but at least a part of the preceding image will be included in the specific region 50. Therefore, if the preceding image and the subsequent image overlap in the after-printing print medium 22, the image detection unit 74 may not be able to suitably detect the subsequent image even by cutting out the specific region 50 from the after-printing image data.

[0079] Therefore, in this embodiment, when the preceding image and the succeeding image overlap on the after-printing printing medium 22, defects in the after-printing process are detected by comparing the preceding print data, the succeeding print data, and the after-printing image.

[0080] Hereinafter, the flow of processing of the print control device 12 according to this embodiment will be described with reference to the flowchart shown in Fig. 10. Note that the preceding print data and subsequent print data in this flowchart indicate preceding images and subsequent images for multiple pages.

[0081] In step S10, the processor 38 of the print control device 12 selects the first page of the multiple pages indicated by the preceding print data and the subsequent print data.

[0082] In step S12, the overlap determination unit 44 determines whether or not the preceding image and the succeeding image overlap on the selected page based on the preceding print data and the succeeding print data.

[0083] If the preceding image and the succeeding image do not overlap, the process proceeds to step S14, where the inspection instruction unit 42 acquires, as inspection information, specific color information indicating a specific color in which the succeeding image will be printed, based on the succeeding print data. Alternatively or in addition to this, the inspection instruction unit 42 may acquire, as inspection information, specific area information indicating a specific area in which the succeeding image will be printed, based on the succeeding print data. The inspection instruction unit 42 associates the acquired inspection information (at least one of the specific color information and the specific area information) with the page number and stores it.

[0084] If the preceding image and the succeeding image overlap, the process proceeds to step S16, where the data combining unit 46 combines the preceding print data of the page with the succeeding print data of the page to obtain the combined data of the page as inspection information. The inspection instruction unit 42 associates the obtained inspection information (combined data) with the page number and holds it.

[0085] In step S18, the processor 38 determines whether or not the process of acquiring the inspection information for all pages has been completed.

[0086] If the processing has not been completed for all pages, the process proceeds to step S20, where the processor 38 selects the next page, and then executes the processing of steps S12 to S16 for the next page.

[0087] If the processing for all pages has been completed, the process proceeds to step S22, where the inspection instruction unit 42 transmits to the overprinting inspection device 18 inspection information associated with each page and an inspection instruction for the overprinting processing.

[0088] Hereinafter, the flow of processing by the overprint inspection device 18 according to this embodiment will be described with reference to the flowchart shown in FIG.

[0089] In step S30, the processor 72 of the overprinting inspection device 18 selects the first page of the overprinted print medium 22 to be inspected.

[0090] In step S32, the defect detection unit 76 determines the type of inspection information for the page received from the print control device 12.

[0091] If the inspection information for the page is specific color information or specific area information, proceed to step S34, in which the image detection unit 74 detects a subsequent image based on the inspection information from the post-printing image data acquired by the scanner 62, or directly from the post-printing printing medium 22.

[0092] Next, in step S36, the defect detection unit 76 compares the subsequent image detected in step S34 with the subsequent print data received from the print control device 12.

[0093] If the inspection information of the page is combined data, the process proceeds to step S38, where the image detection unit 74 compares the combined data with the post-printing image data acquired by the scanner 62.

[0094] In step S40, the defect detection unit 76 judges the inspection result of the overprinting process for the page. Specifically, if the similarity between the subsequent image and the subsequent print data, or the similarity between the combined data and the overprinted image data, is equal to or greater than a predetermined threshold, the defect detection unit 76 judges the inspection result of the overprinting process as "good". On the other hand, if the similarity between the subsequent image and the subsequent print data, or the similarity between the combined data and the overprinted image data, is less than a predetermined threshold, the defect detection unit 76 judges the inspection result of the overprinting process as "bad".

[0095] If the inspection result is "good", the process proceeds to step S42, where the processor 72 ejects the page of the post-printing print medium 22 onto the OK tray 68.

[0096] If the inspection result is "bad", the process proceeds to step S44, where the processor 72 ejects the page of the post-printing print medium 22 onto the NG tray 70.

[0097] In step S46, the processor 72 determines whether or not the inspection process for the overprinting process has been completed for all pages.

[0098] If the inspection process has not been completed for all pages, the process proceeds to step S48, where the processor 72 selects the next page, and then executes the processes of steps S32 to S44 for the next page.

[0099] If the inspection process has been completed for all pages, the process proceeds to step S50, where the defect detection unit 76 transmits the results of the overprinting process for each page to the print control device 12.

[0100] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0101] For example, in this embodiment, the print control device 12 controls the inspection of the overprinting process, but the process related to the inspection of the overprinting process may be performed within the overprinting inspection device 18. That is, the overprinting inspection device 18 may have the functions of the inspection instruction unit 42, overlap determination unit 44, and data combination unit 46 that the print control device 12 has. In that case, the overprinting inspection device 18 appropriately receives the preceding print data from the print control device 12 or the preceding image forming device 14, and receives the subsequent print data from the print control device 12 or the subsequent image forming device 16, and then performs the process.

[0102] If the overprinting inspection device 18 has each of the above functions, there may be a case where the overprinting inspection device 18 cannot obtain the preceding print data from the print control device 12 and the preceding image forming device 14. In that case, the processor 72 of the overprinting inspection device 18 may use image data obtained by optically reading the pre-overprinting print medium 20 as the preceding print data. The pre-overprinting print medium 20 may be read by the scanner 62 of the overprinting inspection device 18, or may be read by another optical reading device provided between the preceding image forming device 14 and the subsequent image forming device 16, and the overprinting inspection device 18 may obtain the image data from the optical reading device.

[0103] In addition, in this embodiment, the scanner 62, the color sensor 64, and the image detection unit 74 are provided in the overprint inspection device 18, but these may be provided in other devices. For example, they may be provided in the subsequent image forming device 16. [Explanation of symbols]

[0104] 10 overprinting system, 12 print control device, 14 preceding image forming device, 16 subsequent image forming device, 18 overprinting inspection device, 20 pre-overprinting print medium, 22 post-overprinting print medium, 30, 60 communication interface, 32 input interface, 34 display, 36, 66 memory, 38, 72 processor, 40 print instruction unit, 42 inspection instruction unit, 44 overlap determination unit, 46 data combination unit, 50 specific area, 62 scanner, 64 color sensor, 68 OK tray, 70 NG tray, 74 image detection unit, 76 defect detection unit.

Claims

1. A processor is provided. The processor, A subsequent image based on subsequent print data is printed on a pre-printing pre-printing medium on which a previous image based on the previous print data is printed. A subsequent image is detected from the pre-printing post-printing medium formed by the pre-printing process, and the subsequent print data is compared to detect a defect in the pre-printing process. When the preceding image and the succeeding image overlap on the overprinted printing medium, a defect in the overprinting process is detected by comparing the preceding print data, the succeeding print data, and the image printed on the overprinted printing medium. An overprint inspection device characterized by:

2. In the overprinting process, the subsequent image is printed in a specific color not used in the previous image, The subsequent image is detected from the overprinted print medium by a sensor that detects a specific color.

2. The overprinting inspection device according to claim 1 .

3. The subsequent image is an image detected from a specific area, which is an area on the printing medium after the overprinting, that is identified based on the subsequent print data and is where the subsequent image is to be printed.

3. The overprinting inspection device according to claim 1 or 2.

4. The image data obtained by optically reading the pre-printing print medium is used as the pre-printing data.

2. The overprinting inspection device according to claim 1 .

5. For the plurality of pages of the pre-printed print medium, the plurality of pages of the pre-printed print medium are formed by the pre-printing process based on the plurality of pages of the subsequent print data, The processor, For a page where the preceding image and the succeeding image do not overlap, a defect in the overprinting process is detected by comparing the succeeding image detected from the page with the succeeding print data; In a page where the preceding image and the succeeding image overlap, a defect in the overprinting process is detected by comparing the preceding print data, the succeeding print data, and the image printed on the printing medium after the overprinting.

5. The overprinting inspection device according to claim 1 or 4.

6. On the computer, A subsequent image is printed on a pre-printing medium on which a previous image based on the previous print data is printed. The subsequent image is detected from the pre-printing medium formed by the pre-printing process, and the subsequent print data is compared to detect a defect in the pre-printing process. When the preceding image and the succeeding image overlap on the overprinted printing medium, a defect in the overprinting process is detected by comparing the preceding print data, the succeeding print data, and the image printed on the overprinted printing medium. The overprinting inspection program is characterized by:

Images