JP2011114574A - Inspection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent defects occurring chronically by detecting and eliminating the defects without stopping print processing. <P>SOLUTION: An inspection system stores feature quantity and removes bad pages when the defects occur, and stops the print processing when similar defects occur again. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a processing technique for determining whether or not there is a printing defect in a medium printed on image data in a printing apparatus that prints image data on a predetermined medium.

  Conventionally, inspection of printed materials by the operator's visual inspection has been performed based on the experience of the workers. However, the printed materials output from the image forming apparatus capable of high-speed and high-mix low-volume production are synchronized with printing. It was desired to inspect products in-line.

  Therefore, in recent years, we have inspected whether there are problems such as printing stains, missing prints, and hair roots that have occurred in the printing process, which are required for multi-faceted printed materials and printed materials with small but high added value. The development of the system to be done.

  The image forming apparatus receives PDL data that is page description data from the host computer, interprets this, generates image data, and outputs the image data. The inspection system acquires the image data of the printed matter output from the image forming apparatus and compares it with the image data generated from the image forming apparatus, thereby making it possible to detect the presence or absence of a problem.

  However, in the conventional inspection system, when an image defect occurs, the crisis stops and the operator has to check the error location. Therefore, the following method has been proposed in order to solve the problem that the printing operation stops every time an error occurs and the operator has to come to confirm the error location.

  In the apparatus proposed in Japanese Patent Application Laid-Open No. 2004-338308, the apparatus is stopped when the bookbinding page is included in the subsequent processing, and when not included, the report page of the error content is output after all pages are output.

  The apparatus proposed in Japanese Patent Laid-Open No. 2008-142938 removes misprinted paper by discharging it to another tray or the like without stopping the processing operation in the event of an error.

JP 2004-338308 A JP 2008-142938 A

  However, the conventional proposal as described above has the following problems.

  According to the proposals in Patent Literature 1 and Patent Literature 2, it is possible to reduce the number of times that the operator takes time without stopping the printing process even when an error occurs.

  However, when an error occurs in a printed matter containing personal information such as invoices, which is often used in VDP (Variable Data Print), which can produce a variety of products in small quantities, an error from a third-party operator may occur. There is a problem that the location must be confirmed.

  Further, when the error content is an image defect, there is a problem that the same image defect occurs even after one error page is removed.

  In other words, in this patent, in order to solve the above-mentioned problem, the inspection can be performed while maintaining the security with the minimum number of error confirmation items by the operator without stopping the printing process. In addition, it is necessary to perform image inspection that makes it possible to prevent continuous image defect errors.

Means for receiving first image data to be printed on a predetermined medium (S1001);
Means for receiving the printed second image data (S1002);
Means for comparing and determining whether there is a difference between the two received image data (S1004);
If there is a difference, means for extracting the feature amount of the difference (S1006),
Means (S1007) for retrieving whether or not a similar defect has previously occurred from the feature quantity stored in the storage medium;
Means for transmitting a print processing stop signal when a similar defect has occurred (S1009);
Means for storing and holding the feature amount of the defect in the storage medium when a defect different from the previous one has occurred (S1010);
Means for Instructing Reprinting Process of Page Using First Image Data to be Printed (S1011)
The inspection system is characterized by comprising:

  According to the present invention, by automatically reprinting the page when an error occurs, it is possible to maintain the security of the printed matter because the operator's visual confirmation is unnecessary.

  Even in the case of an error that occurs chronically rather than suddenly, it is possible to prevent errors that occur subsequently by storing the characteristics of the previously generated error.

2 is a diagram illustrating a configuration of an MFP. FIG. 2 is a block diagram of an MFP control unit. FIG. FIG. 3 is a diagram illustrating a 4D color MFP hardware configuration. It is a block diagram of a RIP part. It is a block diagram of an output image processing unit (color system). It is a figure which shows the structure of a post-processing part. It is a figure which shows the structure of the whole printing and inspection environment. It is a block diagram inside an inspection system. It is a figure which shows the example of a defect which generate | occur | produces at the time of printing. FIG. 3 is a diagram illustrating a flow in the first embodiment. FIG. 10 is a diagram showing a flow in Example 2. FIG. 10 is a diagram showing a flow in Example 3.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

<Configuration of MFP>
The configuration of an MFP (Multi Function Peripheral), which is a printing apparatus (an apparatus having a printing function) according to the first embodiment of the present invention, will be described with reference to FIG.

  The MFP includes a memory such as a hard disk capable of storing a plurality of job data in its own apparatus, and has a copy function that allows the printer unit to print job data output from the scanner via the memory. In addition, a print function for enabling job data output from an external device such as a computer to be printed by the print unit via the memory is provided. In other words, the MFP is an image forming apparatus having a plurality of functions including a printing function (a printing apparatus as an apparatus having a printing function includes an image forming apparatus having a printing function. An example).

  The MFP includes a full-color device and a monochrome device, and the full-color device often includes the configuration of the monochrome device in the basic part except for color processing and internal data. For this reason, full-color devices will be mainly described here, and monochrome devices will be added as needed.

  As for the configuration of the MFP according to the present embodiment, as described above, the MFP has a multi-function type image forming apparatus having a plurality of functions, and an SFP (Single Function Peripheral). But it ’s okay. Note that SFP refers to, for example, a single function type image forming apparatus having only a print function.

  Further, the image forming apparatus may include only one of the MFP and the SFP. Further, any type of image forming apparatus may be used. In any case, any configuration that can realize the information processing method according to the present embodiment may be used.

  In FIG. 1, reference numeral 101 denotes an input image processing unit that reads an image such as a paper document and performs image processing on the read image data. A FAX unit 102 transmits and receives images using a telephone line typified by a facsimile. Reference numeral 103 denotes a NIC (Network Interface Card) unit that exchanges image data and device information using a network. A dedicated interface unit 104 exchanges information such as image data with an external device. A USB interface (USB I / F) unit 105 transmits / receives image data and the like to / from a USB device typified by a USB (Universal Serial Bus) memory (a type of removable media). Reference numeral 106 denotes an MFP control unit, which plays a role of traffic control such as temporarily storing image data and determining a route according to the use of the MFP.

  The document management unit 111 includes a memory such as a hard disk capable of storing a plurality of image data, and is mainly composed of a control unit (for example, a CPU of the MFP control unit 106) included in the MFP, and various image data are stored therein. , Control to be stored in the memory. Examples of the image data include image data from the input image processing unit 101, image data of a facsimile job input via the FAX unit 102, and an external device such as a computer input via the NIC unit 103. Image data. Also included are various image data input via the dedicated I / F unit 104 and the USB I / F unit 105.

  Further, the image data stored in the memory is appropriately read out, transferred to an output unit such as the printer unit 113, and controlled to execute output processing such as print processing by the printer unit 113. Further, the image data read from the memory is controlled to be transferred to an external apparatus such as a computer or another image forming apparatus according to an instruction from the operator.

  When storing the image data in the document management unit 111, the image data is compressed and stored as necessary. Conversely, when the compressed image data is read out, the original image data is decompressed. The storage / read-out process such as returning to / from is performed via the compression / decompression unit 110. In addition, it is generally known that compressed data such as JPEG, JBIG, and ZIP is used when data passes through a network. After the image data enters the MFP, it is decompressed (decompressed) by the compression / decompression unit 110. )

  Further, the resource management unit 112 stores various parameter tables that are commonly handled, such as fonts, color profiles, and gamma tables, and can be called up as necessary. In addition, new parameter tables can be stored, modified and updated.

  Further, in the MFP control unit 106, when PDL data is input, the RIP unit 108 performs RIP (Raster Image Processor) processing. For the image to be printed, the output image processing unit 109 performs image processing for printing as necessary. Further, intermediate data or print ready data (bitmap data for printing or data obtained by compressing the image data) generated at that time can be stored again in the document management unit 111 as necessary.

  A sheet (a medium on which image data is printed) sent to the printer unit 113 that performs image formation and printed out by the printer unit 113 is sent to the post-processing unit 114 to perform sheet sorting processing and sheet finishing processing. Is called.

  Here, the MFP control unit 106 plays a role of smoothly flowing jobs, and path switching is performed as follows according to how the MFP is used. However, although it is generally known that image data is stored as intermediate data as needed, access other than the document management unit 111 serving as a start point and an end point is not described here. Also, processing such as the compression / decompression unit 110 and post-processing unit 114 used as necessary, or the MFP control unit 106 serving as the entire core is omitted, and is described so that an approximate flow can be understood. .

・ Copy function:
Input image processing unit-> output image processing unit-> printer unit-FAX transmission function:
Input image processing unit → FAX unit ・ FAX reception function:
FAX section → output image processing section → printer section ・ Network scan:
Input image processing unit → NIC unit ・ Network print:
NIC unit-> RIP unit-> output image processing unit-> printer unit-Scan to external device:
Input image processing unit → Dedicated I / F unit ・ Printing from an external device:
Dedicated I / F unit → Output image processing unit → Printer unit ・ Scan to external memory:
Input image processing unit → USB I / F unit ・ Printing from external memory:
USB I / F part → RIP part → Output image processing part → Printer part ・ Box scan function:
Input image processing unit → Output image processing unit → Document management unit ・ Box print function:
Document management section → Printer section ・ Box reception function:
NIC unit → RIP unit → output image processing unit → document management unit Box transmission function:
Document Management Department → NIC Department ・ Preview function:
Document Management Unit → Operation Unit In addition to the above, combinations with various functions such as an E-mail service and a Web server function are conceivable, but are omitted here.

  Box scan, box print, box reception, or box transmission is a processing function of the MFP that involves writing and reading of data using the document management unit 111. Then, the memory in the document management unit 111 is divided and stored temporarily for each job and each user, and data is input / output by combining a user ID and a password.

  Further, the operation unit 107 is for selecting the above-described various flows and functions and instructing operations. However, as the resolution of the display device of the operation unit 107 increases, the image in the document management unit 111 is displayed. Data can be previewed and printed after confirmation if it is OK.

<About MFP Control Unit 106>
Next, the MFP control unit 106 will be described with reference to FIG.

  The figure is roughly divided into four parts. That is, an input device management unit 201 that manages input devices, an input job control unit 202 that interprets input jobs, an output job control unit 203 that arranges job setting information, and an output device management unit 204 that allocates output devices It is.

  The input device management unit 201 plays a role of organizing input signals from each input unit and determining a switching order. Here, there is an input device control unit, and examples of input signals sent via each interface include signals input from outside the MFP, such as scanned image signals of paper documents and PDL data from the network. . Also included are signals processed inside the MFP such as reprinting of image data stored in the document management unit 111 and cooperation with the RIP unit 108 and the output image processing unit 109.

  The input job control unit 202 includes a protocol interpretation unit and a job generation unit. A series of operation requests sent from the input device control unit is received by command signals called commands (protocols), and the protocol interpretation unit interprets the outline of the operation requests and converts them into operation procedures that can be understood inside the MFP. Is done. On the other hand, the job generation unit generates various jobs such as a print job, a scan job, a PDL development job, and a fax reception job. The generated job is defined in each scenario such as what kind of processing is performed inside the MFP and where the job is sent, and flows inside the MFP according to the scenario.

  In the output job control unit 203, job setting information (commonly called a job ticket) and image information are created in the job analysis unit, binder analysis unit, document analysis unit, and page analysis unit.

  The job analysis unit analyzes details of setting information related to the entire job, such as the name of the document to be printed, the number of copies to be printed, the designation of the output destination paper discharge tray, and the binder order of the job composed of multiple binders. The binder analysis unit analyzes details of setting information related to the entire binder, such as bookbinding method settings, staple positions, and document order of a binder composed of a plurality of documents.

  The document analysis unit analyzes the details of setting information related to the entire document, such as the page order of a document composed of a plurality of pages, designation of double-sided printing, and addition of a cover or slip sheet.

  The page analysis unit analyzes the details of the setting information regarding the entire setting page such as the image resolution and the image orientation (landscape / portrait), and when the PDL data is input, calls the RIP unit to perform rasterization. Apply processing. In generating image information, the RIP unit is called and page image information is generated by rasterization processing. The page image information is compressed by the compression / decompression unit 110 and then stored in the document management unit 111 in association with the setting information.

  The output device management unit 204 includes a device allocation unit and an output device control unit. The image information stored in the document management unit 111 is decompressed by the compression / decompression unit 110 and read together with the associated setting information, and the setting information and the image information are sent to the output device management unit 204 as a pair. It will come.

  The device allocating unit plays a role of arbitrating device conflicts when a plurality of jobs proceed simultaneously when allocating output devices based on the defined job scenarios. The output device control unit schedules which device to use, such as the printer unit 113 and the post-processing unit 114.

<Hardware configuration of MFP>
Next, a hardware configuration of a 4D color MFP (Multi Function Peripheral) (excluding the post-processing unit 114) will be described with reference to FIG. The 4D color MFP includes a scanner unit 301, a laser exposure unit 302, an image forming unit 303, a fixing unit 305, a paper feed / conveyance unit 304, and a printer control unit (not shown) that controls these units.

  The scanner unit 301 illuminates a document placed on a document table, optically reads a document image, converts the image into an electrical signal, and creates image data.

  The laser exposure unit 302 causes a light beam such as a laser beam modulated according to the image data to enter a rotating polygonal mirror (polygon mirror) that rotates at a constant angular velocity, and irradiates the photosensitive drum as reflected scanning light.

  The image forming unit 302 rotates the photosensitive drum, charges it with a charger, develops the latent image formed on the photosensitive drum by the laser exposure unit with toner, and transfers the toner image to a sheet. In this case, a series of development units (development stations) for a series of electrophotographic processes for collecting minute toner remaining on the photosensitive drum without being transferred are provided.

  Four series of development units arranged in the order of cyan (C), magenta (M), yellow (Y), and black (K) can produce magenta, yellow, and black after a predetermined time has elapsed since the start of cyan station image formation. Image operations are executed sequentially. By this timing control, a full color toner image without color misregistration is transferred onto the sheet.

  The fixing unit 305 includes a combination of a roller and a belt, and includes a heat source such as a halogen heater, and melts and fixes the toner on the sheet onto which the toner image has been transferred by the image forming unit using heat and pressure.

  The sheet feeding / conveying unit 304 has one or more sheet storages represented by sheet cassettes and paper decks, and a plurality of sheets stored in the sheet storages according to instructions from the printer control unit. One sheet is separated and conveyed to the image forming unit 303 and the fixing unit 305. The sheet is conveyed, and each color toner image is transferred by the above-described developing station, and finally a full-color toner image is formed on the sheet. Further, when forming an image on both sides of the sheet, control is performed so that the sheet that has passed through the fixing unit 305 passes through a conveyance path for conveying the sheet to the image forming unit 303 again.

  The printer control unit communicates with the MFP control unit 106 that controls the entire MFP, and executes control according to the instruction. In addition, while managing the states of the scanner unit 301, the laser exposure unit 302, the image forming unit 303, the fixing unit 305, and the paper feeding / conveying unit 304, an instruction is given so that the whole can operate smoothly in harmony. Do.

  The sheet that has passed through the fixing unit 305 passes through the image reading sensor 306 on the conveyance path, and the printed image data is read by the image reading sensor 306. The read image data is used for density measurement of the output image and detection of whether there is an abnormality in the output image.

<Configuration of RIP unit 108>
Next, the configuration of the RIP unit 108 will be described with reference to FIG.

  A RIP (Raster Image Processor) is a processor that develops a bitmap (raster image) on a memory in order to simultaneously reproduce each object information on a page. Examples of the object information include vector information such as characters, line drawings, and figures described in PDL (Page Description Language), or image scanning line information such as colors, patterns, and photographs. Originally, it was mounted on the output device side as hardware, but now it is realized by software by increasing the CPU speed.

  The RIP unit 108 generally comprises two parts, an interpreter unit 401 and a rendering unit 402. The interpreter unit 401 includes a PDL interpretation unit that translates PDL and a DL (Display List) generation unit that generates an intermediate file called a display list from the interpreted PDL data. On the other hand, the rendering unit 402 includes a CMM (Color Matching Module) unit that performs color matching on a display list, and a DL development unit that develops the display list into a bitmap (raster image).

  The PDL interpretation unit is a part that analyzes various types of input PDL data. As the input format, the PostScript (registered trademark) language of Adobe, the PCL (Printer Control Language) language of HP (Hewlett-Packard), and the like are well known.

  These are described as printer control codes for creating an image in units of pages, and include not only simple character codes but also graphic drawing codes and photographic image codes. A document display file format developed by Adobe called PDF (Portable Document Format) is also widely used in various industries, and this format directly thrown into the MFP without using a driver is also targeted.

  In addition, it also supports a format for VDP (Variable Data Print) called PPML (Personalized Print Markup Language). In addition, it also supports color image compression formats such as JPEG (Joint Photographic Experts Group) and TIFF (Tagged Image File Format).

  In the CMM section, various image data such as gray scale, RGB, and CMYK can be input. In the case of other color spaces, color matching is performed after conversion into CMYK space by CRD (Color Rendering Dictionary). In the CMM unit, color adjustment is performed based on the ICC profile.

  The ICC profile includes a source profile and a printer profile. The source profile converts RGB (or CMYK) data into a standardized L * a * b * space. Further, the L * a * b * data is converted again into a CMYK space suitable for the target printer. At this time, the source profile includes an RGB profile and a CMYK profile. When the input image is an RGB image (Microsoft application software, JPEG, TIFF image, or the like), the RGB profile is selected. On the other hand, a CMYK profile is selected in the case of a CMYK image (such as Photoshop or partial data of Illustrator).

  The printer profile is created in accordance with the color characteristics of each printer. In the case of an RGB image, it is preferable to select Perceptual (color priority) or Saturation (brightness priority). In the case of a CMYK system image, Colorimetric (minimum color difference) is often selected to output an optimal image.

  The ICC profile is generally created in a look-up table format. When RGB (or CMYK) data is input, the ICC profile is uniquely converted to L * a * b * data. On the other hand, in the printer profile, the L * a * b * data is converted into CMYK data that matches the printer. Note that RGB data that does not require color matching is converted to CMYK data by default color conversion and output, and is output as it is to CMYK data that does not require color matching. The image data expanded by the RIP unit 108 is held in the document management unit 111 via the compression / decompression unit 110.

<Configuration of Output Image Processing Unit 109>
Next, the output image processing unit 109 will be described with reference to FIG.

  Image data input to the output image processing unit 109 (color system) includes RGB data that handles output data from the input image processing unit 101 such as a copying operation, and CMYK that handles output data from the RIP unit 108 such as a network print operation. It can be roughly divided into system data. In the former case, it is input to the background removal unit, and in the latter case, it is input to the output gamma correction unit.

  First, the background removal unit performs non-linear conversion for removing the background part on the RGB image data read by the scanner unit 301 based on the result of the printer unit 113.

  Next, the output direct mapping unit converts the RGB image data into CMYK image data. In the conversion, RGB values are input to a lookup table, and a C (Cyan) component is created from the sum of the output values. Similarly, each component of M (Magenta), Y (Yellow), and K (breakK) is also formed by a lookup table and its addition operation. At this time, a three-dimensional lookup table is used based on the image area data detected by the input image processing unit 101, and different types of lookup tables are applied to the character area and the photograph area. .

  The output gamma correction unit corrects the density of the output image corresponding to the printer. Each CMYK uses a one-dimensional look-up table to maintain the linearity of output image data that differs for each image formation, and the result of color calibration is generally reflected in this look-up table.

  The halftone processing unit can alternatively apply different types of screening according to the MFP function. In general, the copying operation uses an error diffusion screening that is less likely to cause moire, and the printing operation often uses a multi-value screen screening that uses a dither matrix in consideration of the reproducibility of characters and fine lines. . The former is a method in which the pixel of interest and its surrounding pixels are weighted with an error filter, and multilevel errors are distributed and corrected while maintaining the number of gradations. On the other hand, the latter is a method in which the threshold value of the dither matrix is set to multiple values, and a pseudo halftone is expressed, converted to CMYK independently, and reproduced by switching between a low line number and a high line number according to input image data. .

  Further, the smoothing processing unit is a method for reducing jaggies by detecting edge portions of each of CMYK by pattern matching and converting them into patterns that are reproduced more smoothly.

<Configuration of inline finisher unit (post-processing unit) 114>
Next, the configuration of the inline finisher unit (post-processing unit) 114 will be described with reference to FIG. FIG. 6 is a cross-sectional view of the inline finisher portion 114.

  The sheet discharged from the fixing unit 305 of the printer unit 113 enters the inline finisher unit 114 when an inline finisher is connected. The inline finisher unit 114 includes a sample tray and a stack tray, which are switched and discharged according to the type of job and the number of discharged sheets.

  There are two sort methods: a bin sort method that has multiple bins and sorts each bin, and a shift sort that sorts output sheets for each job by shifting the electronic sort function and bin (or tray) toward the back. Sorting by the method can be performed.

  The electronic sort function is called collate. If you have a large-capacity memory in the core part, you can use this buffer memory to change the buffered page order and discharge order by using the so-called collate function. It can also support sorting functions.

  The group function is a function for sorting by page, whereas sorting is sorted by job.

  Further, when the staple mode is set for the job to be output, control is performed so that the sheet is discharged onto the stack tray. In that case, before the sheets are discharged to the stack tray, the sheets are sequentially stored in the processing tray inside the finisher for each job, bound on the processing tray by the stapler, and then stacked. The sheet bundle is discharged to a tray.

  In addition to the above two trays, there are a Z-folder for folding paper into a Z-shape and a puncher for punching two (or three) holes for files, depending on the type of job. Perform the process. For example, when the user sets the Z-folding process via the operation unit 107 as the setting related to the sheet process for the job to be output, the sheet is folded by the Z-folder. Then, control is performed so that the paper is passed through the apparatus and discharged onto a discharge tray such as a stack tray or a sample tray.

  Further, for example, when the user sets punch processing via the operation unit 107 as the setting related to sheet processing for a job to be output, punch processing by puncher is executed on the sheet of the job. Then, control is performed so that the paper is passed through the apparatus and discharged onto a discharge tray such as a stack tray or a sample tray.

  Further, the saddle stitcher binds the central portion of the sheet at two places, and then performs a process (bookbinding process) for half-folding the sheet by biting the central portion of the sheet with a roller to create a booklet like a pamphlet. . Sheets bound by the saddle stitcher are discharged to a booklet tray. Whether or not a sheet processing operation such as bookbinding processing by saddle stitching can be performed is also based on the sheet processing setting set by the user for the job to be output as described above.

  The inserter is for sending a sheet set on the insert tray to either a stack tray or a sample tray without passing through the printer. As a result, the sheet set on the inserter can be inserted (inserted) between the sheets sent to the inline finisher unit 114 (sheets printed by the printer unit 113) and the sheets. It is assumed that the insert tray of the inserter is set face up by the user, and is fed in order from the uppermost sheet by a pickup roller.

  Therefore, the sheet from the inserter is discharged to the stack tray or the sample tray as it is, and is discharged face down. When sending to the saddle stitcher, the face is aligned by sending it back to the puncher side and then switching back. Whether or not a sheet processing operation such as a sheet insertion process by the inserter can be executed is also based on the sheet processing setting set by the user for the job to be output as described above.

  Next, a trimmer (cutting machine) will be described. The output made into a booklet by the saddle stitcher enters this trimmer. At that time, the output of the booklet is first fed by a predetermined length by a roller, cut by a predetermined length by a cutter unit, and dispersed among a plurality of pages in the booklet. The edges will be neatly aligned. Then, it is stored in the booklet hold unit. Note that whether or not to perform sheet processing operations such as cutting processing by the trimmer is also based on the sheet processing setting set by the user for the job to be output as described above.

<Outline of inspection system>
In FIG. 7, an MFP 702 is connected via a network 704 to host computers 701a and 701b (hereinafter referred to as host computers 701. However, the present invention is not limited to this, and there are many host computers). A network 704 enables data transmission from the host computer 701 to the MFP 702 and exchange of commands.

  The MFP 702 performs printing on a print document. The image reading sensor 306 acquires the image data printed on the print original by the MFP 702, and transmits the image data acquired by the reading sensor 306 and the raster data in the print format to the inspection system 703.

  The inspection system 703 compares the transmitted image data and raster data, and the finisher unit 114 outputs an inspected document.

The inspection system 703 will be described with reference to FIG.
The image acquisition unit 801 acquires two pieces of image data, that is, image data acquired by the image reading sensor 306 from the printed document transmitted from the MFP 702 and raster data that is print data.

  Here, the raster data is data obtained by interpreting the PDL data given by PS, PDF, PPML, or the like by the interpreter unit 401 and converting the bitmap data to a format in which the rendering unit 402 actually performs printing. is there.

  The image processing unit 802 performs tone comparison, color correction, brightness, contrast correction, and print position correction in order to perform image comparison on the image data acquired by the image acquisition unit 801. The image comparison unit 803 compares the two data subjected to image processing, determines whether there is a difference, and transmits the determination result to the MFP 702.

  If there is no difference, the MFP 702 performs normal processing. If there is a difference, the MFP 702 removes the page by discharging the defective page to a discharge tray that does not use it.

  If there is a difference, the image comparison unit 803 accesses the defect DB 804 and inquires whether a similar defect has occurred before. Here, the defect DB 804 may be in the inspection system 703 or in a server on the network 704.

  The defect DB 804 stores and holds defect characteristics. The feature is a feature in which, for example, color information such as cyan appears weaker than raster data, character missing, etc. occur and the shape is strange.

  As a result of the inquiry from the image comparison unit 803 to the defect DB 804, if the same defect still occurs, the MFP 702 is instructed to stop the printing process because there may be a defect that continues to occur in subsequent printing. .

  When a defect other than the defect that has occurred before has occurred, the image comparison unit 803 detects the feature of the defect and performs a writing process on the defect DB 804. The MFP 702 does not stop the printing process, removes the defective page, and reprints the defective page.

  Here, the feature of the defect will be described using some examples with reference to FIG.

  Comparing the difference between the raster data before printing and the image data after printing, in 901, a line that did not appear in the raster data before printing appears after printing. Such a defect is called a white streak of an image, and there are various causes for the occurrence of the white streak, but the rotating part of the MFP 702 is often related.

  For example, when dust adheres to the fixing roller in the fixing unit 305, such an image white streak occurs. The dust adhering to the fixing roller causes the same defect in the subsequent page printing. For this reason, the defect DB 804 describes the characteristics of where the defect is occurring from where on the page, and prevents subsequent defects.

  At 902, a change in the color of the character printed with “A” occurs. The color change is caused by the remaining amount of toner in the developing unit in the image forming unit 303, a change in toner charging potential, or the like. For this reason, the color changes during printing, and the same defect may occur in subsequent pages unless calibration is performed.

  For this reason, the defect DB 804 describes the characteristics of which color of CMYK changes compared to the raster data before printing by how much difference, and prevents defects occurring thereafter.

  In 903, black dots that did not appear in the raster data before printing appear in the image data after printing. Such a defect is called a dropout, and toner that has not been used due to a non-image portion is scattered and accumulated on the upstream side in the image forming unit 303.

  This toner pool is peeled off from the transfer material and occurs as a dropout when transferred to the photosensitive drum. The toner is also generated when the toner remaining on the cleaning drum of the photosensitive drum falls on the photosensitive drum.

  Such a dropout is not continuous but a failure that occurs suddenly. However, in this case as well, in order to prevent the occurrence of frequent but non-continuous cases, the feature of what kind of defect is occurring at which position on the defect DB 804 page is described, and subsequent defects are prevented. .

  Subsequently, the processing flow of the inspection system will be described with reference to FIG.

In step S1001, RIP raster data transmitted from the MFP 702 is received, and in step S1002, image data printed on the original obtained from the image reading sensor 306 is received. In step S1003, correction processing is performed on the two image data received by the image processing unit 802, and in step S1004, the image comparison unit 803 determines whether there is a difference between the two data.

  If there is a difference, that is, if a defect has occurred, the feature amount of the defect is detected in step S1006, and a search is performed in step S1007 to determine whether a similar defect has occurred before. The feature of the defect here represents the position, color, shape, etc. where the defect occurs.

  If a similar failure has occurred as a result of the search, a similar failure may occur in subsequent printing, and a print processing stop signal is sent to the MFP 702 in step S1009.

  If a new defect that differs from the previously generated defect feature occurs, the feature amount extracted in step S1010 is stored and retained in the defect DB, and the defective page is reprinted to the MFP 702 in step S1011. Instruct.

  Here, the inspection system 703 sends an instruction to the MFP 702 to remove the page, for example, by discarding the defective printed matter on another tray.

  If no defect has occurred as a result of the inspection, the inspection system 703 sends a print instruction for the next page to the MFP 702 in step S1012.

  Here, the defect DB 804 includes information such as the feature amount of the defect that has occurred, the date and time of occurrence, the paper document size, the number of pages that have occurred, the remaining amount of toner that is device information, and the total number of printed pages.

  Therefore, according to the present invention, it is possible to realize an inspection system capable of automatically removing defective pages for security maintenance without stopping printing processing and capable of preventing defects that occur chronically. Is possible.

  In the first embodiment, a method of performing a page reprinting process when a defect occurs is shown. However, it is difficult to always synchronize the printing speed and the inspection speed. In general, there is no problem when the inspection speed is high, but when the printing speed is higher, the inspection speed is lowered when the inspection is performed. Therefore, Example 2 shows a method for performing inspection without reducing the printing speed as much as possible.

  The flow of Example 2 is shown using FIG.

  In the second embodiment, unlike the first embodiment, reprinting is performed in finishing units, that is, in record units, instead of reprinting pages.

In step S1101, RIP raster data transmitted from the MFP 702 is received, and in step S1102, image data printed on the original obtained from the image reading sensor 306 is received. In step S1103, the two image data received by the image processing unit 802 are corrected. In step S1104, the image comparison unit 803 determines whether there is a difference between the two data.

  If a difference has occurred, that is, a defect has occurred, the feature amount of the defect is detected in step S1106, and a search is performed in step S1107 to determine whether a similar defect has previously occurred. The feature of the defect here represents the position, color, shape, etc. where the defect occurs.

  If a similar failure has occurred as a result of the search, a similar failure may occur in subsequent printing, so a print processing stop signal is sent to the MFP 702 in step S1109.

  If a new defect is generated that is different from the previously generated defect feature, the feature amount extracted in step S1110 is stored in the defect DB 804, and a defect record reprint process is performed on the MFP 702 in step S1111. Instruct.

  Here, the inspection system 703 sends an instruction to the MFP 702 to remove a page that has already been printed, for example, by discarding the record including the defective printed matter in another tray.

  If no defect has occurred as a result of the inspection, the inspection system 703 sends a print instruction for the next page to the MFP 702 in step S1112.

  Therefore, according to the present invention, inspection is performed in units of records instead of inspecting in units of pages. Therefore, it is possible to automatically remove records including defective pages in order to maintain security without reducing the printing speed as much as possible. Is possible.

  In addition, it is possible to realize an inspection system that can prevent defects that occur chronically.

  In the first and second embodiments, the printing process is stopped when the same defect as before occurs. However, depending on the type of defect, there is a defect that can be corrected by adjusting software instead of the hardware of the MFP 702.

  For example, in the case of color variation, information on how much each CMYK color used for printing has changed can be acquired from the image comparison unit 803 of the inspection system 703.

  By adjusting the amount of toner used in the output device control unit according to the increase / decrease in the color variation, it is possible to prevent a defect that occurs chronically without stopping the printing process.

  The flow of Example 3 is shown using FIG.

In step S1201, the RIP raster data transmitted from the MFP 702 is received. In step S1202, the image data printed on the original obtained from the image reading sensor 306 is received.

  In step S1203, the two image data received by the image processing unit 802 are corrected. In step S1204, the image comparison unit 803 determines whether there is a difference between the two data.

  If there is a difference, that is, if a defect has occurred, the feature amount of the defect is detected in step S1206, and a search is performed in step S1207 to determine whether a similar defect has previously occurred. The feature of the defect here represents the position, color, shape, etc. where the defect occurs.

  If a similar defect has occurred as a result of the search, it is determined in step S1209 whether or not the defect can be corrected by adjusting the software of the MFP 702. If the defect can be corrected, the software is adjusted in step S1212. If the correction is impossible, a print processing stop signal is sent to the MFP 702 in step S1210.

  If a new defect is generated that is different from the previously generated defect feature, the feature amount extracted in step S1212 is stored and retained in the defect DB, and the defective page is reprinted to the MFP 702 in step S1213. Instruct.

  Here, the inspection system 703 sends an instruction to the MFP 702 to remove the page, for example, by discarding the defective printed matter on another tray.

  If no defect has occurred as a result of the inspection, the inspection system 703 sends a print instruction for the next page to the MFP 702 in step S1214.

  Therefore, according to the present invention, it is possible to automatically remove a defective page for security maintenance without stopping the printing process, and to correct a defect that can be corrected among chronically occurring defects. In addition, an inspection system that can be prevented chronically can be realized.

Claims (7)

Means for receiving first image data to be printed on a predetermined medium (S1001);
Means for receiving the printed second image data (S1002);
Means for comparing and determining whether there is a difference between the two received image data (S1004);
If there is a difference, means for extracting the feature amount of the difference (S1006),
Means (S1007) for retrieving whether or not a similar defect has previously occurred from the feature quantity stored in the storage medium;
Means for transmitting a print processing stop signal when a similar defect has occurred (S1009);
Means for storing and holding the feature amount of the defect in the storage medium when a defect different from the previous one has occurred (S1010);
Means for Instructing Reprinting Process of Page Using First Image Data to be Printed (S1011)
An inspection system characterized by comprising: Means (S1003) for performing image processing on the received first and second image data according to claim 1;
2. The inspection system according to claim 1, wherein the image processing includes means including gradation correction, lightness correction, and angle deviation correction of the printing position.   2. The inspection system according to claim 1, wherein the feature amount extraction means in claim 1 has a position, a color, and a shape where a difference is generated on the image data.   The inspection system according to claim 1, wherein the information stored in the storage medium according to claim 1 includes feature amounts, printed data information, and device information. Means for receiving first image data to be printed on a predetermined medium (S1101);
Means for receiving the printed second image data (S1102);
Means for comparing and determining whether there is a difference between the two received image data (S1104);
If there is a difference, means for extracting the feature amount of the difference (S1106),
Means (S1107) for retrieving whether or not a similar defect has occurred before from the feature quantity held in the storage medium;
Means for transmitting a print processing stop signal when a similar defect has occurred (S1109);
Means for storing and holding the feature amount of the defect in the storage medium if a defect different from the previous one has occurred (S1110);
Means for instructing reprinting process of record using first image data to be printed (S1111)
An inspection system characterized by comprising: Means for receiving first image data to be printed on a predetermined medium (S1201);
Means for receiving the printed second image data (S1202);
Means for comparing and determining whether there is a difference between the two received image data (S1204);
If there is a difference, means for extracting the feature amount of the difference (S1206),
Means (S1207) for retrieving whether or not a similar defect has previously occurred from the feature quantity stored in the storage medium;
Means for determining whether or not the detected defect can be corrected (S1208);
If correction is possible, means for correcting (S1212),
Means for transmitting a print processing stop signal when a similar defect has occurred when correction is impossible (S1210);
Means for storing and holding the feature amount of the defect in the storage medium when a defect different from the previous one has occurred (S1211);
Means for instructing reprinting process of record using first image data to be printed (S1213)
An inspection system characterized by comprising:   7. The inspection system according to claim 6, wherein the defect that can be corrected in the image forming apparatus is not a defect caused by a hardware factor in the image forming apparatus but a defect caused by a software factor.