Inspection device, method for controlling the same, image forming device, and method for controlling the same

Abstract

To prevent generation of many wasted sheets caused by frequent re-printing when a non-accidental printing failure occurs in recovery printing.SOLUTION: This inspection device comprises: reception means for receiving a scan image obtained by scanning a printed matter having an image formed on a sheet by an image forming device; inspection means for inspecting the printed matter on the basis of the scan image and a correct answer image registered in advance; and instruction means for instructing, when a defective sheet is determined by the inspection means, the image forming device to execute first recovery printing from the image printed on the defective sheet. When the result of inspection executed by the inspection means satisfies a prescribed condition for an in-machine remaining sheet conveyed in the image forming device at the timing of the occurrence of the defective sheet, the instruction means instructs execution of second recovery printing different from the first recovery printing.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an inspection apparatus, a control method for the inspection apparatus, an image forming apparatus, and a control method for the image forming apparatus.

Background Art

[0002] Conventionally, inspection of printed matter has been performed manually. In recent years, however, an apparatus for automatically inspecting printed matter as a post-processing operation of a printing press has been used. In such an inspection apparatus, first, reference image data is registered. Next, input image data is printed on a sheet by an image forming apparatus, and the image printed on the sheet is read by an inspection sensor disposed inside the inspection apparatus. By comparing the image data (scanned image) read by the inspection sensor with the reference image data registered first, a sheet having a printing stain (printing defect) (hereinafter referred to as a "defective sheet") is detected. Some such image forming apparatuses are provided with a purge function for discharging a defective sheet to a separate tray (hereinafter referred to as a "purge tray") from a normal printed matter. Further, some are provided with a recovery printing function for aligning the page order when discharging a defective sheet to the purge tray. Here, the recovery printing function is a function that, when a defective sheet is detected, temporarily stops the printing process, discharges the defective sheet and the sheets remaining in the machine following the defective sheet (hereinafter referred to as "in-machine remaining sheets") to the purge tray, and reprints from the defective sheet. In Patent Document 1, an in-machine remaining sheet, which is a sheet on the conveyance path at the time of defective sheet detection, is discharged to a tray if it satisfies a predetermined quality. When each part is composed of a plurality of sheets, a remaining sheet, which is a sheet on the conveyance path, is discharged to the tray as a normal printed matter if it satisfies a predetermined quality and is the sheet in the next output order after the sheet finally discharged to the tray. As described above, a technique for reducing in-machine remaining sheets that become waste paper generated during recovery printing has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] However, in the method of Patent Document 1, when periodic non-accidental printing stains or continuous non-accidental printing stains occur, defective sheets are generated again even in recovery printing, and in-machine residual sheets are generated, resulting in a large amount of waste paper.

MEANS FOR SOLVING THE PROBLEMS

[0005] The inspection apparatus according to the present invention includes: a receiving unit that receives a scanned image obtained by scanning a printed matter in which an image is formed on a sheet by an image forming apparatus; an inspection unit that inspects the printed matter based on the scanned image and a correct image registered in advance; and an instruction unit that, when the inspection unit determines that a sheet is defective, instructs the image forming apparatus to perform a first recovery print from the image printed on the defective sheet. When the inspection result obtained by the inspection unit performing an inspection on the in-machine residual sheet conveyed inside the image forming apparatus at the timing when the defective sheet occurs satisfies a predetermined condition, the instruction unit instructs to perform a second recovery print different from the first recovery print.

EFFECTS OF THE INVENTION

[0006] According to the present invention, when a printing defect is detected, an inspection is also performed on the in-machine residual sheet, and by optimizing the recovery printing operation according to the inspection result, it is possible to significantly reduce waste paper.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined.

[0009] (First Embodiment) <Configuration of the Entire System> FIG. 1 is an overall configuration diagram of an inspection system for explaining the present embodiment. The inspection system in the present embodiment is configured by communicably connecting an image forming apparatus 100, an inspection PC 110, a network 120, and a communication cable 130.

[0010] The image forming apparatus 100 receives various input data and print job data via the network 120 and performs print output. The image forming apparatus 100 includes an image processing apparatus 101, an inspection apparatus 102, and a finisher 103, and is connected to the image processing apparatus 101, the inspection apparatus 102, the finisher 103, and the inspection PC 110 via a communication cable 130 which is an internal bus.

[0011] The image processing apparatus 101 performs image processing according to print settings on various input data, and outputs the image processed as a printed matter.

[0012] The inspection apparatus 102 receives the printed matter output from the image processing apparatus 101, and acquires image data for inspecting whether there is an abnormal image in the received printed matter. Here, the abnormal image is what degrades the quality of the printed matter. For example, it is a round abnormal image (dot) generated by the adhesion of a coloring material to an unintended location during printing, color bleeding generated by insufficient adhesion of the coloring material to an intended location, or a linear abnormal image (streak). Then, the acquired image data is transferred to an inspection PC 110 described later via a communication cable 130, an inspection is performed on the inspection PC 110 to determine whether there is an abnormal image in the printed matter, and the inspection result is acquired from the inspection PC 110.

[0013] The finisher 103 receives the output paper inspected by the inspection apparatus 102, switches the paper discharge destination based on the inspection result of the inspection PC 110, and performs post-processing (such as bookbinding) as necessary.

[0014] The image forming apparatus 100 is connected to the inspection PC 110 via a communication cable 130, and communicates about image data and inspection results during inspection. In this embodiment, the inspection is performed by the inspection PC 110, but the present invention is not limited to this embodiment, and a configuration such as an in-line inspection machine that consistently performs image formation, inspection, post-processing, and paper discharge may also be used. Note that the detailed configuration of the image forming apparatus 100 in this embodiment will be described later.

[0015] The inspection PC 110 is a PC for inspecting an image read from a printed matter using the inspection apparatus 102, and includes an apparatus control unit 111 and a user interface unit 118 (hereinafter referred to as the "UI unit"). Further, the apparatus control unit 111 is composed of a controller base, and a CPU 112, a RAM 113, a ROM 114, a communication I / F unit 115, a storage unit 116, and an inspection processing unit 117 are mounted on the apparatus control unit. It is assumed that communication between these modules is performed by an internal system bus 119. Also, the inspection PC 110 may be configured to be built in the inspection apparatus 102.

[0016] The CPU 112 reads the main program from the storage unit 116 according to the initial program in the storage unit 116 and stores it in the RAM 113. The RAM 113 is used as a main memory for program storage and work. The ROM 114 is used to temporarily store data created during program processing. The communication I / F unit 115 is used when communicating via the network 120 or the communication cable 130. The storage unit 116 is used to store data such as programs, image data, and large-capacity data such as inspection jobs. The inspection processing unit 117 calculates a difference value between a reference image stored in the RAM 113 as a correct image and a scanned image of the inspection target to inspect whether there are abnormal images such as dirt or color bleeding in the image data acquired by the inspection apparatus 102. Next, the inspection processing unit 117 performs an inspection by comparing the calculated difference value with the inspection thresholds (contrast and size) of each inspection item for each pixel. The result of the inspection is stored in the RAM 113, and stores, for example, information on whether there is an abnormal image in the printed matter, and position information of the abnormal image when displaying the type (dots or streaks) of the detected abnormal image on the UI unit 118. Then, the inspection result is transmitted to the inspection apparatus 102 and the finisher 103 via the communication cable 130.

[0017] The UI unit 118 is a device configured by, for example, a keyboard, a mouse, a display, and other input / output devices, and can receive input of various setting values or specified values.

[0018] The above is the description of the overall system configuration including the inspection device in this embodiment. In this embodiment, communication is performed regarding image data and inspection results during inspection via the communication cable 130. However, any form is acceptable as long as the devices can communicate with each other. For example, communication may be performed regarding image data and inspection results during inspection via the network 120.

[0019] <Internal Configuration of Image Forming Apparatus 100> FIG. 2 is a diagram showing the internal configuration of the image forming apparatus 100 in this embodiment.

[0020] The image forming apparatus 100 includes an image processing apparatus 101, an inspection apparatus 102, and a finisher 103.

[0021] Furthermore, the image processing apparatus 101 includes a device control unit 200, a printer unit 210, a UI unit 230, and a paper feeding unit 250.

[0022] The device control unit 200 receives images and documents from the network 120 and converts them into print data. The device control unit 200 has a CPU 201, a RAM 202, a storage unit 203, a communication I / F unit 204, a ROM 205, an image processing unit 206, and an internal system bus 207 mounted thereon. Note that the roles of each device are the same as those of the inspection PC 110 except for the image processing unit 206, and thus the description thereof is omitted.

[0023] The image processing unit 206 acquires the PDL data stored in the RAM 202 and performs image processing for converting it into print data. The image processing for converting it into print data is, for example, to convert the PDL data into multi-valued bitmap data by performing RIP processing on the PDL data, and to convert it into binary bitmap data by performing known screen processing or the like. The binary bitmap data obtained by the image processing unit 206 is transmitted from the communication I / F unit 204 to the printer unit 210 via the internal system bus 208.

[0024] The printer unit 210 conveys the recording material from the paper feeding unit 250, receives the binary bitmap data generated by the device control unit 200, and forms an image on the recording material using the coloring material. At this time, an instruction is issued to the printer unit 210 based on the printing settings specified by the user. For example, in the case of a printing setting using coated paper, the CPU 211 issues an instruction to print using the paper feed deck in which the coated paper in the paper feeding unit 250 is stored. From the reception of the above-described PDL data to the various processes until printing on the recording material, by being controlled by the device control unit 200 and the printer unit 210, a full-color toner image is formed on the recording material. And the printer unit 210 has the CPU 211, the RAM 212, the communication I / F unit 214, the ROM 215, and the internal system bus 217 mounted thereon. Incidentally, since the roles of the respective devices are the same as those of the device control unit 200, the description thereof is omitted.

[0025] The UI unit 230 is a device configured by, for example, a keyboard, a mouse, a display, and other input / output devices, and can receive the input of various setting values or specified values.

[0026] The paper feeding unit 250 has one or more cassettes for setting the recording material to be printed, feeds the recording material from the cassette corresponding to the size of the recording material specified in the printing settings, and is a device for conveying it to the printer unit 210.

[0027] The inspection device 102 includes a device control unit 260 and an image reading unit 270.

[0028] The image reading unit 270 is a device for reading the printed matter conveyed from the printer unit 210 using a CCD (Charge Coupled Device) sensor or the like and obtaining it as image data composed of multi-value signals of red, green, and blue.

[0029] The device control unit 260 controls the transfer of the image data acquired by the image reading unit 270 to the inspection PC 110 via the communication cable 130. Then, it inspects whether there are abnormal images on the printed matter on the inspection PC 110 from the transferred image data and obtains the inspection result from the inspection PC 110. The device control unit 260 has a CPU 261, a RAM 262, a communication I / F unit 264, a ROM 265, and an internal system bus 267 installed. Since the roles of each device are the same as those of the device control unit 200, the description is omitted.

[0030] The finisher 103 includes a device control unit 280 and a paper discharge unit 290.

[0031] The device control unit 280 determines the paper discharge control to be performed by the paper discharge unit 290 in consideration of the print settings and the inspection results. The device control unit 280 has a CPU 281, a RAM 282, a communication I / F unit 284, a ROM 285, and an internal system bus 287 installed. Since the roles of each device are the same as those of the device control unit 200, the description is omitted.

[0032] The paper discharge unit 290 is a device for switching the paper discharge destination of the printed matter conveyed from the inspection device 102 according to the print settings and based on the inspection results (for example, bookbinding, etc.). For example, it is conceivable to switch the paper discharge destination according to whether there are abnormal images on the printed matter. When switching the paper discharge destination based on the inspection results, the finisher 103 uses the inspection result received from the inspection PC 110 to discharge the printed matter without abnormal images to the normal paper discharge tray and the printed matter with abnormal images to a tray different from the normal paper discharge tray.

[0033] <Hardware Configuration of the Image Forming Apparatus 100> FIG. 3 is a cross-sectional view showing a hardware configuration example of the image forming apparatus 100. Hereinafter, a specific operation example of the image forming apparatus 100 will be described with reference to FIG. 3.

[0034] In the image processing apparatus 101, various recording materials are stored in the paper feed decks 301 and 302. Among the recording materials stored in each paper feed deck, the uppermost recording material is separated one by one and fed to the conveyance path 303. The image forming stations 304 to 307 each include a photosensitive drum (photoconductor), and toner images are formed on the photosensitive drum using toners of different colors. Specifically, the image forming stations 304 to 307 form toner images using yellow (Y), magenta (M), cyan (C), and black (K) toners, respectively.

[0035] The toner images of each color formed in the image forming stations 304 to 307 are sequentially superimposed and transferred onto the intermediate transfer belt 308 (primary transfer). The toner image transferred onto the intermediate transfer belt 308 is conveyed to the secondary transfer position 309 as the intermediate transfer belt 308 rotates. At the secondary transfer position 309, the toner image is transferred from the intermediate transfer belt 308 to the recording material conveyed through the conveyance path 303 (secondary transfer). The recording material after secondary transfer is conveyed to the fixing unit 310. The fixing unit 310 includes a pressure roller and a heating roller. A fixing process for fixing the toner image to the recording material is performed by applying heat and pressure to the recording material while it passes between these rollers. The recording material that has passed through the fixing unit 310 is conveyed through the conveyance path 311 to the connection point 314 between the image processing apparatus 101 and the inspection apparatus 102. In this way, a color image is formed (printed) on the recording material.

[0036] When further fixing processing is required according to the type of recording material, the recording material that has passed through the fixing unit 310 is guided to a conveyance path 313 where a fixing unit 312 is provided. The fixing unit 312 performs further fixing processing on the recording material conveyed through the conveyance path 313. The recording material that has passed through the fixing unit 312 is conveyed to a connection point 314. Also, when an operation mode for performing double-sided printing is set, an image is printed on the first side, and the recording material conveyed through the conveyance path 311 or the conveyance path 313 is guided to a reverse path 315. The recording material reversed in the reverse path 315 is guided to a double-sided conveyance path 316 and conveyed to a secondary transfer position 309. Thereby, a toner image is transferred to the second side opposite to the first side of the recording material at the secondary transfer position 309. Thereafter, by passing the recording material through the fixing unit 310 (and the fixing unit 312), the formation of the color image on the second side of the recording material is completed.

[0037] When the formation (printing) of the image in the image processing apparatus 101 is completed, the printed matter conveyed to the connection point 314 is conveyed into the inspection apparatus 102.

[0038] The inspection apparatus 102 includes image reading units 317 and 318 having CISs (Contact Image Sensors) on a conveyance path 319 through which the printed matter from the image processing apparatus 101 is conveyed. The image reading units 317 and 318 are arranged at positions facing each other via the conveyance path 319. The image reading units 317 and 318 are each configured to read the upper surface (first side) and the lower surface (second side) of the printed matter. Note that the image reading unit may be configured by, for example, a CCD (Charge Coupled Device) or a line scan camera instead of the CIS.

[0039] The inspection apparatus 102 performs a reading process of reading the printed matter conveyed through the conveyance path 319 using the image reading units 317 and 318. The printed matter that has passed through the inspection apparatus 102 is sequentially conveyed to a finisher 103.

[0040] The finisher 103 executes the finishing functions specified by the user on the printed matter conveyed from the inspection device 102. In the present embodiment, the finisher 103 has, for example, functions such as switching the paper discharge destination based on the inspection result and finishing functions such as a binding function. When switching the paper discharge destination based on the inspection result, the finisher 103 uses the inspection result received from the inspection PC 110 to discharge the product, which is a printed matter without abnormal images, to the normal tray 321 via the sheet conveyance path 320. The printed matter with abnormal images is discharged to the purge tray 323 (paper discharge tray) via the sheet conveyance path 322. When binding is specified, in the processing unit 324, after stapling the center of the sheet, the sheet is folded in half and output to the binding tray 326 via the sheet conveyance path 325.

[0041] The conveyance path 327 is configured to include the conveyance paths 303, 311, 313 in the image processing apparatus 101 and the conveyance path 319 in the inspection apparatus 102.

[0042] The above is the description of the image forming apparatus 100 in the present embodiment. Not limited to the present embodiment, any configuration may be used as long as it can print print data and read an image for inspecting whether there is an abnormal image on the printed matter.

[0043] <Recovery printing function> When a defective sheet is detected during the inspection of the printed matter, the purge process when performing recovery printing will be described with reference to FIG. 4. Also, the existing recovery printing (hereinafter referred to as "first recovery printing") after the purge process is completed will be described with reference to FIG. 9, and the recovery printing (hereinafter referred to as "second recovery printing") that does not generate in-machine residual sheets after the purge process is completed will be described with reference to FIG. 5. Here, FIGS. 4, 9, and 5 illustrate the case where one copy consists of five or more pages and a job for printing multiple copies is executed. Also, although the case of single-sided printing is taken as an example, the process is the same when double-sided printing is used.

[0044] Fig. 4(a) shows the state of the printed matter when defective sheet 402 is detected during the inspection of the printed matter. The printed matter 401 has completed the inspection and is discharged to the normal tray 321, and the printed matters 402 to 405 are being conveyed on the conveyance path 327 in the order of 402 to 405. After detecting the defective sheet 402, printing is temporarily stopped, and the defective sheet 402 and the printed matters 403 to 405 as the in-machine remaining sheets are discharged to the purge tray 323. The in-machine remaining sheets refer to the printed matters present on the conveyance path in the image forming apparatus at the timing when the defective sheet 402 occurs.

[0045] Fig. 4(b) shows the state of the printed matter when the defective sheet 402 is detected during the inspection of the printed matter and the purge process of the defective sheet 402 and the in-machine remaining sheets 403 to 405 is completed. The defective sheet 402 and the in-machine remaining sheets 403 to 405 are discharged to the purge tray 323 separate from the normal tray 321, and there is no printed matter on the conveyance path 327. After that, reprinting is performed from the image printed on the defective sheet 402.

[0046] The case of performing the first recovery printing after the purge process described in Fig. 4 is explained with reference to Fig. 9.

[0047] Fig. 9(a) shows the first recovery printing after the defective sheet 402 is detected during the inspection of the printed matter and the purge process of the defective sheet 402 and the in-machine remaining sheets 403 to 405 is completed. Normal printing resumes from the page where the defective sheet 402 was detected, and the same pages as the page where the defective sheet 402 was detected and the in-machine remaining sheets 403 to 405 following the defective sheet 402 are reprinted on the printed matters 901 to 904. Then, if no printing defect is detected after inspecting the printed matters 901 to 904, they are discharged to the normal tray 321 as the finished product, making it possible to remove the defective sheet and align the page order.

[0048] Figure 9(b) shows the first recovery printing after detecting defective sheet 402 and completing the purge process for defective sheet 402 and in-machine remaining sheets 403 - 405 when printing defects occur periodically every four sheets. Printing resumes at the normal printing speed from the page where defective sheet 402 was detected. On prints 905 - 908, the page where defective sheet 402 was detected and the same pages as in-machine remaining sheets 403 - 405 following defective sheet 402 are reprinted, but there is a printing defect on print 905. Then, at the stage of inspecting print 905, similar to Fig. 3(a), print 905 is discharged as defective sheet 905, prints 906 - 908 are discharged as in-machine remaining sheets 906 - 908 to purge tray 323, and reprinting is performed from the same page as defective sheet 905. Also, the same operation occurs even when consecutive printing defects occur not only on defective sheets 402·905 but also on remaining sheets 403 - 405 and 906 - 908.

[0049] Figure 9(c) shows the first recovery printing after detecting defective sheet 905 and completing the purge process for defective sheet 905 and in-machine remaining sheets 906 - 908 during the first recovery printing shown in Fig. 9(b). Normal printing resumes from the page where defective sheet 905 was detected. On prints 909 - 912, the page where defective sheet 905 was detected and the same pages as in-machine remaining sheets 906 - 908 following defective sheet 905 are reprinted, but there is a printing defect on print 909. Then, at the stage of inspecting print 909, similar to Fig. 3(a), print 909 is discharged as defective sheet 909, prints 910 - 912 are discharged as in-machine remaining sheets 910 - 912 to purge tray 323, and reprinting is performed from the same page as defective sheet 909.

[0050] Thus, when accidental defects occur, recovery processing can be performed in a short time as shown in Fig. 9(a). However, when defects occur periodically every four sheets, the state shown in Fig. 9(c) is repeated until printing stops, resulting in a large amount of paper waste.

[0051] Here, the printing stop may be set to be enabled or disabled as a function that stops printing when defective sheets continue for a predetermined number of times continuously, separately from the recovery printing function. For example, when a function that stops printing when defective sheets continue for 5 consecutive times (excluding in-machine residual sheets from the continuous count) is set to be enabled, the recovery printing will be repeated 4 times, resulting in a large amount of waste paper generation.

[0052] In FIG. 9, the operation of the first recovery printing when a defective sheet is detected during the inspection of the printed matter was described. However, when non-incidental defects occurred, a large amount of waste paper was generated. Therefore, the second recovery printing, which reduces waste paper by performing recovery printing in a way that does not generate in-machine residual sheets during recovery printing, will be described using FIG. 5 starting from the state after the purge process described in FIG. 4.

[0053] FIG. 5(a) shows the recovery process immediately after detecting the defective sheet 402 during the inspection of the printed matter and completing the purge process of the defective sheet 402 and the in-machine residual sheets 403 to 405. The printed matter 501 is reprinted from the image printed on the page where the defective sheet 402 was detected. No image is formed on the conveyance path 327 other than the printed matter 501. After the inspection of the printed matter 501 is completed, the next recording material is conveyed onto the conveyance path 327 and printing is performed.

[0054] FIG. 5(b) shows the operation when the previous inspection result was normal during the second recovery printing. In FIG. 5(a), when the inspection result of the printed matter 501 is normal, the printed matter 501 is discharged to the normal tray 321, and the next page of the printed matter 501 is printed on the printed matter 502. No image is formed on the conveyance path 327 other than the printed matter 502. After the inspection of the printed matter 502 is completed, the next printed matter is conveyed onto the conveyance path 327 and printing is performed.

[0055] Figure 5(c) shows the operation when the previous inspection result during the recovery printing process is abnormal. In Figure 5(b), when the inspection result of the printed matter 502 is abnormal, the printed matter 502 is discharged to the purge tray 323, and the same page as the printed matter 502 is printed on the printed matter 503. No image is formed on the conveyance path 327 except for the printed matter 503. After the inspection of the printed matter 503 is completed, the next printed matter is conveyed onto the conveyance path 327 and printing is performed.

[0056] After the second recovery printing finishes reprinting without defects for the defective sheet 402 and the in-machine residual sheets 403 - 405, the second recovery printing ends, and normal printing resumes from the next page that was last discharged to the normal tray 321. Also, the second recovery printing process may end the process based on predetermined conditions and switch to normal printing. For example, when the recovery printing process for a preset number of pages by the user is completed, it is conceivable to end the recovery printing process. In this case as well, normal printing resumes from the next page that was last discharged to the normal tray 321.

[0057] In this way, by limiting the formation of an image to only one printed matter on the conveyance path 327 during recovery printing, it becomes possible to prevent the occurrence of in-machine residual sheets even if a defective sheet occurs non-accidentally. For example, when a function is effectively set such that printing stops when defective sheets continue for 5 consecutive times, the number of wasted sheets is only the in-machine residual paper when the first defective sheet is detected and the 5 defective sheets, and it is possible to prevent the occurrence of a large amount of wasted paper.

[0058] <Recovery Printing Flow> Figure 6 is a flowchart showing the operation when the CPU 112 of the inspection PC 110 inspects the printed matter, detects a defective sheet, and executes the recovery printing process. By executing this process, it becomes possible to reduce wasted paper when non-accidental printing defects occur.

[0059] Each process in FIG. 6 is realized by the CPU 112 expanding the program code stored in the ROM 114 into the RAM 113, reading and executing the program code expanded in the RAM.

[0060] In step S601, the CPU 112 detects the conveyance of the printed matter, scans the printed matter with the image reading unit 270, and stores the scanned image in the RAM 113. Then, the scanned image of the printed matter is compared with the reference image which is the correct image of the inspection registered and stored in the RAM 113 in advance, and the difference value is calculated. An inspection is performed based on the calculated difference value to check whether there are printing defects in the scanned image.

[0061] In step S602, the CPU 112 determines whether it is a defective sheet as a result of inspecting the printed matter in step S601. If it is a defective sheet (YES in step S602), it proceeds to step S603. If it is not a defective sheet (NO in step S602), the processing of this flowchart ends.

[0062] In step S603, the CPU 112 sets the page which was a defective sheet as the recovery start page as a result of inspecting the printed matter in step S601. Also, via the communication I / F unit 115, information to temporarily stop printing is transmitted to the device control unit 200, and information to discharge the defective sheet to the purge tray 323 is transmitted to the device control unit 280.

[0063] Here, the CPU 201 that has received information via the communication I / F unit 204 instructs the printer unit 210 to temporarily stop printing. The image forming apparatus 100 temporarily stops the printing operation when the printer unit 210 is instructed to temporarily stop printing.

[0064] Also, the CPU 281 that has received information via the communication I / F unit 284 discharges the defective sheet to the purge tray 323.

[0065] In step S604, the CPU 112, in the same manner as in step S601, also inspects the in-machine residual sheets following the defective sheets, and via the communication I / F unit 115, transmits information to the device control unit 280 to discharge the in-machine residual sheets to the purge tray 323.

[0066] Here, the CPU 281 that has received information via the communication I / F unit 284 discharges the in-machine residual sheets to the purge tray 323. Note that whether a printing defect is detected in the in-machine residual sheets or not, the in-machine residual sheets are discharged to the purge tray. This is to align the page order of the printed materials discharged to the normal tray. On the other hand, in the case of a job consisting of one image per sheet, this is not the case. In step S604, control may be performed to discharge to the normal tray and the purge tray according to the inspection result of the in-machine residual sheets.

[0067] In step S605, the CPU 112 determines whether there is a printing defect in the in-machine residual sheets as a result of inspecting the in-machine residual sheets in step S604. If there is no printing defect in the in-machine residual sheets (NO in step S605), the process proceeds to step S606. If there is a printing defect in the in-machine residual sheets (YES in step S605), the process proceeds to step S607.

[0068] In step S606, the CPU 112 transmits, via the communication I / F unit 115, information to the device control unit 200 to resume printing from the recovery start page set in step S603 (first recovery printing), and ends the processing of this flowchart.

[0069] Here, the CPU 201 that has received information via the communication I / F unit 204 instructs the printer unit 210 to resume printing from the recovery start page. The image forming apparatus 100 resumes the printing operation when instructed to reprint from the recovery start page by the printer unit 210.

[0070] In step S607, the CPU 112 transmits, via the communication I / F unit 115, information for the apparatus control unit 200 to perform the second recovery printing, and ends the processing of this flowchart. Details of step S607 in the present embodiment will be described later.

[0071] Next, the second recovery printing flow of step S607 will be described using the flowchart of FIG. 7.

[0072] Each process in FIG. 7 is realized by the CPU 112 expanding the program code stored in the ROM 114 in the RAM 113, and reading and executing the program code expanded in the RAM.

[0073] In step S701, the CPU 112 transmits, via the communication I / F unit 115, information for the apparatus control unit 200 to print one copy of the recovery start page set in step S603 or set in step S707 described later. In this embodiment, the description is made for printing one copy, but it may be a specified number of copies less than the normal printing speed such as two or three copies, and the number does not matter. If there is no recovery start page, information to end the printing is transmitted.

[0074] Here, the CPU 201 that has received the information to print one copy of the recovery start page from the CPU 112 via the communication I / F unit 204 instructs the printer unit 210 to print one copy of the recovery start page. The image forming apparatus 100 is instructed to print one copy of the recovery start page on the printer unit 210, and resumes the printing operation. The CPU 201 that has received the information to end the printing from the CPU 112 via the communication I / F unit 204 instructs the printer unit 210 to end the printing. The image forming apparatus 100 is instructed to end the printing on the printer unit 210, and ends the printing operation.

[0075] In step S702, the CPU 112 inspects the recovery start page printed in step S701 in the same manner as in step S601.

[0076] In step S703, the CPU 112 determines whether there is a printing defect on the recovery start page as a result of inspecting the recovery start page in step S702. If there is no printing defect on the recovery start page (NO in step S703), the process proceeds to step S704. If there is a printing defect on the recovery start page (YES in step S703), the process proceeds to step S708.

[0077] In step S704, the CPU 112 increments the count when there is no printing defect on the recovery start page within the second recovery printing flow. Note that the count may be incremented only when there is no printing defect continuously.

[0078] In step S705, the CPU 112 determines whether the count when there is no printing defect on the recovery start page is equal to or greater than a predetermined number of times. If the count when there is no printing defect on the recovery start page is equal to or greater than the predetermined number of times (YES in step S705), the process proceeds to step S706. If the count when there is no printing defect on the recovery start page is less than the predetermined number of times (NO in step S705), the process proceeds to step S707. Note that the predetermined number of times can be set by the user in advance.

[0079] In step S706, the CPU 112 transmits, via the communication I / F unit 115, to the device control unit 200 information to resume printing at normal speed from the page next to the recovery start page set in step S603 or set in step S707 described later. After transmitting the information, the processing of this flowchart ends. Note that if the recovery start page is the last page of a section, information is transmitted to resume printing from the first page of the next section. Also, if there is no page next to the recovery start page, information to end printing is transmitted.

[0080] Here, the CPU201 that has received information from the CPU112 to resume printing via the communication I / F unit 204 instructs the printer unit 210 to start printing from the page next to the recovery start page. The image forming apparatus 100 is instructed to start printing from the page next to the recovery start page by the printer unit 210, and resumes the printing operation. The CPU201 that has received information from the CPU112 to end printing via the communication I / F unit 204 instructs the printer unit 210 to end the printing. The image forming apparatus 100 is instructed to end the printing by the printer unit 210, and ends the printing operation.

[0081] In step S707, the CPU112 increments the recovery start page and returns to step S701. Incidentally, if the recovery start page before incrementing is the last page of the section, as a result of the increment, the first page of the next section is set as the recovery start page. Also, if there is no page next to the recovery start page, it is set that there is no recovery start page.

[0082] In step S708, the CPU112 increments the count when there is a printing defect on the recovery start page within the second recovery printing flow. Incidentally, the count may be incremented only when there are consecutive printing defects. Also, as a result of inspecting the printed matter in step S702, the CPU112 transmits information via the communication I / F unit 115 to the device control unit 280 to discharge the defective sheet to the purge tray 323.

[0083] Here, the CPU281 that has received information via the communication I / F unit 284 discharges the defective sheet to the purge tray 323.

[0084] In step S709, the CPU 112 determines whether the count when there is a printing defect on the recovery start page has reached a predetermined number of times or more. If the count when there is a printing defect on the recovery start page has reached a predetermined number of times or more (YES in step S709), the process proceeds to step S710. If the count when there is no printing defect on the recovery start page is less than the predetermined number of times (NO in step S709), the process returns to step S701. Note that the predetermined number of times can be set by the user in advance.

[0085] In step S710, the CPU 112 transmits information to end printing to the apparatus control unit 200 via the communication I / F unit 115, and ends the processing of this flowchart.

[0086] Here, the CPU 201 that has received information via the communication I / F unit 204 instructs the printer unit 210 to end printing. The image forming apparatus 100 is instructed to end printing on the printer unit 210, and ends the printing operation.

[0087] As described above, it has been proposed to start inspecting printed materials, and when a defective sheet occurs, to inspect the in-machine residual sheets following the defective sheet, and to change the operation of recovery printing according to the inspection results of the in-machine residual sheets. This is because when there is no printing defect in the in-machine residual sheets, the probability that the printing defect occurred accidentally is high, and when there is a printing defect in the in-machine residual sheets, the probability that the printing defect occurred non-accidentally is high. Thereby, when there is no printing defect in the in-machine residual sheets, recovery printing can be performed in a short time by performing the first recovery printing. When there is a printing defect in the in-machine residual sheets, the second recovery printing is performed, and by performing the recovery printing one by one, even if a defective sheet occurs during the recovery printing, no subsequent in-machine residual sheets will occur, and it is possible to reduce waste paper. In addition, in this embodiment, the second recovery printing is performed one by one, but printing may be performed in predetermined specified numbers. For example, consider the case where the specified number is set to 2 sheets. In step S703, if no printing defect is detected in both of the 2 sheets printed, the process proceeds to step S704, and the OK count is incremented, or the count for 2 sheets of the specified number is increased. In step S706, the recovery start page can be switched to normal printing from the page where the count for 2 sheets of the specified number has been increased. Also, in step S707, the recovery start page is incremented by the count for 2 sheets of the specified number. If a printing defect is detected in either or both of the 2 sheets printed in step S703, the process proceeds to step S708, and the NG count is incremented, or increased by the number of sheets in which a printing defect is detected. Also, in step S708, the printed materials until the first printing defect is detected among the 2 sheets of the specified number may be discharged to the normal tray 321, and the printed materials after the printing defect is detected may be discharged to the purge tray 323. When the process of discharging the printed materials until the first printing defect is detected among the specified number to the normal tray 321 is performed in step S708, a step S711 for setting the recovery start page is added while proceeding from step S709 to step S701. When step S711 is added and a printing defect is detected in the first sheet out of the 2 sheets of the specified number, the first sheet is set as the recovery start page.Also, when the first sheet is normal and a printing defect is detected in the second sheet, the second sheet is set as the recovery start page. That is, the page where the printing defect is first detected among the printed specified number of sheets is set as the recovery start page. In this way, by performing printing in specified numbers of sheets, it becomes possible to improve the time efficiency compared to the case of performing printing one by one sheet.

[0088] (Second Embodiment) <Recovery Printing Flow> In the first embodiment, when a defective sheet occurs, an inspection of the in-machine remaining sheets following the defective sheet is performed, and the operation of recovery printing is changed according to the inspection result of the in-machine remaining sheets, and a method for reducing waste paper in the case of non-incidental printing defects has been described. Subsequently, in this embodiment, a method for shortening the time required for recovery printing and reducing waste paper by more accurately determining whether the occurred printing defect is incidental will be described with reference to FIG. 6.

[0089] Hereinafter, for this embodiment, the parts different from the above-described first embodiment will be described. Note that parts without detailed description are the same as those in the first embodiment.

[0090] In step S601, the CPU 112 detects the conveyance of the printed matter, scans the printed matter with the image reading unit 270, and stores the scanned image in the RAM 113 of the inspection PC 110. Then, the image of the printed matter scanned is compared with the reference image that is the correct image of the inspection previously stored in the RAM 113, and the difference value is calculated. An inspection is performed to determine whether there is a printing defect in the scanned image based on the calculated difference value. Here, for the in-machine residual sheet in which a printing defect is detected, feature extraction of the difference is performed. Examples of the feature information of the difference obtained by this extraction process include colorant information, contrast information, size information, shape information, coordinate information, periodic information, and the like. Here, the colorant information is information on which color among yellow, magenta, cyan, and black the defect occurs in. The contrast information is information representing whether the defect density contrast of the defective part of the printing defect is a difference in the dark direction (positive direction), a difference in the light direction (negative direction), or a numerical value of positive and negative. The size information is information such as the width of the defect (size in the main scanning direction) and the height (size in the sub-scanning direction). The shape information is information such as dot shape, vertical streak shape, and horizontal streak shape. The coordinate information is information indicating the position in a direction perpendicular to the conveyance direction of the printed matter in the image processing apparatus 101. The periodic information is information indicating that defects with similar characteristics occur periodically in the conveyance direction of the printed matter in the image processing apparatus 101.

[0091] Steps S602 to S604 shown in FIG. 6 are the same as those in the present embodiment, and thus the description thereof is omitted.

[0092] In step S605, the CPU 112 determines whether there is a printing defect in the in-machine residual sheet as a result of inspecting the in-machine residual sheet in step S604. If there is no printing defect in the in-machine residual sheet (YES in step S605), the process proceeds to step S606. If there is a printing defect in the in-machine residual sheet (NO in step S605), the process proceeds to step S608 (not shown) added between step S605 and step S607 in the present embodiment.

[0093] In step S608, the CPU 112 determines whether the inspection result of the in-machine remaining sheets in step S604 satisfies a predetermined condition. If the predetermined condition is satisfied (YES in step S608), the process proceeds to step S607. If the predetermined condition is not satisfied (NO in step S608), the process proceeds to step S606.

[0094] Here, the predetermined condition includes, for example, the following conditions. (1) The ratio of defective sheets in the in-machine remaining sheets is equal to or greater than a predetermined ratio (the first condition). (2) Including the sheets that were defective in the inspection of the printed matter in step S601, the defective sheets in the in-machine remaining sheets have occurred continuously for a predetermined number of times or more (the second condition). (3) Including the sheets that were defective in the inspection of the printed matter in step S601, similar color printing defects have occurred in the in-machine remaining sheets for a predetermined number of times or more (the third condition). (4) Including the sheets that were defective in the inspection of the printed matter in step S601, similar shape printing defects have occurred in the in-machine remaining sheets for a predetermined number of times or more (the fourth condition). (5) Including the sheets that were defective in the inspection of the printed matter in step S601, similar size printing defects have occurred in the in-machine remaining sheets for a predetermined number of times or more (the fifth condition). (6) Including the sheets that were defective in the inspection of the printed matter in step S601, similar density printing defects have occurred in the in-machine remaining sheets for a predetermined number of times or more (the sixth condition). (7) Including the sheets that were defective in the inspection of the printed matter in step S601, printing defects have occurred in the in-machine remaining sheets at substantially the same position in the main scanning direction for a predetermined number of times or more (the seventh condition). (8) Including the sheets that were defective in the inspection of the printed matter in step S601, periodic printing defects have occurred in the in-machine remaining sheets (the eighth condition).

[0095] The predetermined conditions may be any one condition selected by the user from the above first to eighth conditions, or an AND condition or an OR condition of a plurality of conditions. Also, a predetermined ratio and number of times of the above first to seventh conditions can be set by the user. In this embodiment, the main body of the determination in S608 is the CPU 112, but it is not limited thereto. For example, the CPU 112 may notify the inspection result to the device control unit 200 via the communication I / F unit 115, and the CPU 201 of the device control unit 200 may make the determination.

[0096] Steps S606 to S607 shown in FIG. 6 are the same as those in this embodiment, so the description thereof is omitted.

[0097] In addition, for the color of the printing defect exemplified in (3) of the predetermined conditions, it may be determined using a read image that has a complementary color relationship with the printer printing color. Also, for the shape of the printing defect exemplified in (4) of the predetermined conditions, it may be determined using known centroid, circumscribed rectangle (bounding box), major axis, perimeter, circularity, etc. Further, for the periodic defect exemplified in (8) of the predetermined conditions, it may be determined using known fast Fourier transform, Euclidean distance, 4-neighborhood distance (city block distance), etc. In addition, it may also be determined using an 8-neighborhood distance (chess board distance), a distance obtained by vectorizing the defect centroids, etc.

[0098] In this way, by more accurately determining whether the generated printing defect is accidental, it is possible to shorten the time required for recovery printing and reduce waste paper.

[0099] (Third Embodiment) <Recovery Printing Flow> In the second embodiment, a method for shortening the time required for recovery printing and reducing waste paper by more accurately determining whether the generated printing defect is accidental was described. Subsequently, in this embodiment, a method for reducing waste paper will be described with reference to FIG. 8 when the possibility that the generated printing defect is non-accidental is very high.

[0100] Hereinafter, for this embodiment, the parts different from the aforementioned first embodiment will be described. For the parts without detailed description, they are the same as those in the first embodiment.

[0101] Step S801 is the same as step S601 described in the second embodiment, so the description is omitted.

[0102] Steps S802 to S804 are the same as steps S602 to S604 shown in FIG. 4, so the description is omitted.

[0103] In step S805, the CPU 112 determines whether there is a printing defect in the in-machine residual sheet as a result of inspecting the in-machine residual sheet in step S804. If there is no printing defect in the in-machine residual sheet (NO in step S805), the process proceeds to step S806. If there is a printing defect in the in-machine residual sheet (YES in step S805), the process proceeds to step S807.

[0104] Step S806 is the same as step S606 shown in FIG. 6, so the description is omitted.

[0105] In step S807, the CPU 112 determines whether there is a periodic printing defect in the in-machine residual sheet as a result of inspecting the in-machine residual sheet in step S804. If there is no periodic printing defect in the in-machine residual sheet (YES in step S807), the process proceeds to step S808. If there is a periodic printing defect in the in-machine residual sheet (NO in step S807), the process proceeds to step S809.

[0106] Step S808 is the same as step S607 shown in FIG. 6, so the description is omitted.

[0107] In step S809, the CPU 112 transmits information to end printing to the device control unit 200 via the communication I / F unit 115, and ends the processing of this flowchart.

[0108] Here, the CPU 201 that has received information via the communication I / F unit 204 instructs the printer unit 210 to finish printing. The image forming apparatus 100 is instructed to finish printing by the printer unit 210, and ends the printing operation.

[0109] In this way, when there is a very high possibility that the resulting printing defect is non-incidental, it is possible to prevent waste paper in advance by ending the printing without performing recovery printing. This is because when there is a very high possibility that the resulting printing defect is non-incidental, there is a very high possibility that a printing defect will occur and waste paper will be generated when recovery printing is performed.

[0110] Note that in this embodiment, second recovery printing is performed when the defect is an aperiodic defect in step S807. However, second recovery printing may be performed when the defect is an aperiodic defect and satisfies the predetermined conditions of step S605 of the second embodiment. In that case, first recovery printing may be performed when the defect is an aperiodic defect and does not satisfy the predetermined conditions of step S605 of the second embodiment. In this embodiment, when there are periodic printing defects on the in-machine residual sheets, the printing is ended. However, any method may be used as long as it can be determined that the probability of non-incidental occurrence is high.

[0111] As described above, according to this embodiment, it has been proposed to inspect the in-machine residual sheets following the defective sheets and change the operation of the recovery printing according to the inspection results of the in-machine residual sheets. Thereby, when a non-incidental printing defect occurs, it is possible to provide an automatic recovery printing function corresponding to variable printing while reducing waste paper. Furthermore, as a result of inspecting the in-machine residual sheets, when it is determined that the probability of a defective sheet occurring during recovery printing is very high, it is possible to prevent waste paper in advance by ending the printing.

Claims

1. Receiving means for receiving a scanned image obtained by scanning a printed matter having an image formed on a sheet by an image forming apparatus; Inspection means for inspecting the printed matter based on the scanned image and a correct image registered in advance; Instruction means for instructing the image forming apparatus to perform a first recovery print from the image printed on the defective sheet when the inspection means determines that the sheet is a defective sheet; characterized in that it has When the inspection result obtained by the inspection means for inspecting the in-machine residual sheet conveyed inside the image forming apparatus at the timing when the defective sheet occurs satisfies a predetermined condition, the instruction means instructs to perform a second recovery print different from the first recovery print An inspection apparatus characterized by the above.

2. The predetermined condition is a first condition that the ratio of the sheets determined to be defective as a result of the inspection of the in-machine residual sheets is equal to or greater than a predetermined ratio. The inspection apparatus according to claim 1, characterized by the above.

3. The predetermined condition is a second condition that the defective sheet and the in-machine residual sheet are continuously determined to be defective a predetermined number of times or more as a result of the inspection of the in-machine residual sheet. The inspection apparatus according to claim 1, characterized by the above.

4. The predetermined condition is a third condition that a predetermined number of similar predetermined printing defects have occurred in the defective sheet and the in-machine residual sheet as a result of the inspection of the in-machine residual sheet. The inspection apparatus according to claim 1, characterized by the above.

5. The predetermined condition is a fourth condition that periodic printing defects have occurred in the defective sheet and the in-machine residual sheet as a result of the inspection of the in-machine residual sheet. The inspection apparatus according to claim 1, characterized by the above.

6. When the inspection means determines that the sheet is a defective sheet, information for temporarily stopping printing is transmitted to the image forming apparatus. The inspection apparatus according to claim 1, characterized by the above.

7. The image forming apparatus has a plurality of paper discharge trays, Transmission means for transmitting information for switching the paper discharge destination of the printed matter to the image forming apparatus based on the result of the inspection by the inspection means, The transmission means transmits information for discharging the defective sheet and the in-machine residual sheet to a paper discharge tray different from the product. The inspection apparatus according to claim 1, characterized by the above.

8. The sending means transmits information for discharging the printed matter to a discharge tray different from the product, without switching the discharge destination of the printed matter based on the result of the inspection on the remaining sheets in the machine. The inspection apparatus according to claim 7, characterized in that.

9. When the predetermined conditions are not satisfied, the instructing means instructs the first recovery printing, and when the predetermined conditions are satisfied, the instructing means instructs the second recovery printing. The inspection apparatus according to claim 1, characterized in that.

10. The first recovery printing is a printing method controlled to perform recovery printing by a normal printing method in the image forming apparatus. The inspection apparatus according to claim 1, characterized in that.

11. The second recovery printing is a printing method controlled to perform image formation in the image forming apparatus and inspection in the inspection means for each specified number of sheets from the image printed on the defective sheet. The inspection apparatus according to claim 1, characterized in that.

12. During the second recovery printing, when the instructing means does not determine a defect a predetermined number of times or more, the instructing means instructs to switch to the first recovery printing. The inspection apparatus according to claim 1, characterized in that.

13. During the second recovery printing, when the instructing means determines a defect a predetermined number of times or more, the instructing means instructs to stop image formation in the image forming apparatus. The inspection apparatus according to claim 1, characterized in that.

14. Based on the result of the inspection on the remaining sheets in the machine, when the instructing means determines that periodic printing defects have occurred in the defective sheet and the remaining sheets in the machine, the instructing means instructs to stop image formation in the image forming apparatus. The inspection apparatus according to claim 1, characterized in that.

15. A control method for an inspection apparatus, comprising: a receiving step of receiving a scanned image obtained by scanning a printed matter having an image formed on a sheet by an image forming apparatus; an inspection step of inspecting the printed matter based on the scanned image and a correct image registered in advance; an instructing step of, when the printed matter is determined to be a defective sheet in the inspection, instructing the image forming apparatus to perform first recovery printing from the image printed on the defective sheet; having When the inspection result of performing an inspection on the remaining sheets in the machine that are conveyed inside the image forming apparatus at the timing when the defective sheet occurred satisfies a predetermined condition, an instruction is given to execute a second recovery printing different from the first recovery printing. A control method for an inspection apparatus, characterized in that.

16. An image forming apparatus communicably connected to an inspection apparatus that inspects printed matter, comprising: image forming means for forming an image on a sheet on a conveyance path; receiving means for receiving an inspection result from the inspection apparatus; control means for, when receiving the occurrence of a defective sheet from the inspection apparatus, stopping image formation by the image forming means and controlling to perform first recovery printing from the image formed on the defective sheet; and when an inspection result obtained by inspecting an in-machine residual sheet conveyed inside the image forming apparatus at the timing when the defective sheet occurred satisfies a predetermined condition, the control means controls to perform second recovery printing different from the first recovery printing An image forming apparatus characterized by the above.

17. The predetermined condition is that the ratio determined to be defective as a result of the inspection of the in-machine residual sheet is equal to or greater than a predetermined ratio. The image forming apparatus according to claim 16, characterized by the above.

18. The first recovery printing is a printing method controlled to perform recovery printing by a normal printing method in the image forming apparatus. The image forming apparatus according to claim 16, characterized by the above.

19. The second recovery printing controls the image forming means to perform printing in prescribed numbers of sheets from the image formed on the defective sheet, and when receiving that all inspections of the printed matter printed in the prescribed numbers of sheets from the inspection apparatus are completed, performs printing of the next prescribed number of sheets. The image forming apparatus according to claim 16, characterized by the above.

20. The image forming apparatus includes a plurality of paper discharge trays and paper discharge control means for switching the paper discharge destination of the printed matter based on the received inspection result from the inspection apparatus. and the paper discharge control means controls to discharge the defective sheet and the in-machine residual sheet to a paper discharge tray different from the product. The image forming apparatus according to claim 16, characterized by the above.

21. A control method for an image forming apparatus communicably connected to an inspection apparatus that inspects printed matter, comprising: an image forming step of forming an image on a sheet on a conveyance path; a receiving step of receiving an inspection result from the inspection apparatus; a control step of, when receiving the occurrence of a defective sheet from the inspection apparatus, stopping image formation by the image forming means and controlling to perform first recovery printing from the image formed on the defective sheet; and When the inspection result of performing an inspection on the in-machine residual sheet that is conveyed inside the image forming apparatus at the timing when the defective sheet occurred satisfies a predetermined condition, control is performed to perform a second recovery printing different from the first recovery printing. A control method for an image forming apparatus, characterized by the above.

Images