JP2018079581A - Image formation apparatus, image abnormality detection apparatus, management apparatus and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable correct detection of abnormality of an image on a transfer medium in additional printing and the like.SOLUTION: An image formation apparatus includes: an image formation unit which forms an image on a transfer medium on the basis of a job; and a control unit which controls the image formation unit. The control unit includes an abnormality detection function of acquiring an image reading result obtained by reading an image of a transfer medium in which the image is formed by the image formation unit, comparing the image in the image reading result with the image by the printing image data of the job, and detecting the presence/absence of abnormality of the transfer medium on the basis of the comparison result, and determines that the image being the difference is different from an abnormal image when the image having the prescribed size or more exists as the difference in an image non-arrangement region on the transfer medium where the image formed by the printing image data does not exist at the abnormality detection.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image forming apparatus, an image abnormality detection apparatus, a management apparatus, and a control program that can detect the presence or absence of abnormality in a transfer medium based on a result of reading an image on the transfer medium.

Paper that has been printed by the image forming apparatus may have abnormalities such as image smudges, streaks, and scratches for various reasons. Since such an abnormality deteriorates the quality of printed matter, there is a method in which a sheet on which an image is printed is read by an image reading unit, and the read image is compared with an image based on image data for printing to determine the abnormality of the image. Are known.
In addition, the image forming apparatus may perform reprint printing that forms another image on the paper on which the image is printed. When reprint printing is performed, the reprint image and the image on the paper after the final output are different. Therefore, even if the image based on the print image data and the image based on the read result are compared, regardless of whether there is an abnormality A difference occurs in the image, and an abnormality cannot be detected.

  In Patent Document 1, read image data acquired by reading an image on a sheet that is stored in a sheet storage unit and used for reprinting, and a first image formed on a sheet that is received from outside and used for reprinting are disclosed. There has been proposed an image forming apparatus that compares one image data with each other to determine whether an image on a sheet stored in a sheet storage unit is correct or not, and to determine whether a sheet before reprint printing is correct.

  Further, in Patent Document 2, the image data of preprinted paper acquired in advance and the image data of postprinted printing paper are calculated, and an inspection target image with reduced preprinted elements in the image data of postprinted printing paper is generated. An image inspection apparatus that inspects the quality of the reprinting result by comparing the image to be inspected with the image data of the reprinting element has been proposed.

JP 2012-108828 A JP 2011-70548 A

  However, in the image forming apparatus described in Patent Document 1, it is determined only whether the image printed before reprinting matches the data. If they do not match, the image data before reprinting is rotated. If they do not match, a warning is displayed and a paper set is detected. If it does not match, it cannot be detected whether there is an abnormality in the reprinted paper.

Further, in Patent Document 2, it is necessary to acquire image data for preprinting in advance, and it is not possible to deal with cases where there is no preprinted image or data for the preprinted image cannot be obtained.
Further, when printing, it is necessary to set that the printing is reprint printing, and if the setting is not made, an appropriate inspection cannot be performed.

  The present invention has been made against the background of the above problems, and an object thereof is to provide an image forming apparatus, an image abnormality detection apparatus, a management apparatus, and a control program capable of detecting the presence or absence of abnormality in a transfer medium. To do.

That is, among the image forming apparatuses of the present invention, the first form is
An image forming unit that forms an image on a transfer medium based on a job;
A control unit for controlling the image forming unit,
The control unit acquires an image reading result obtained by reading an image of a transfer medium on which an image is formed by the image forming unit, and compares the image in the image reading result with an image based on image data for printing a job, Having a function of abnormality detection to detect the presence or absence of abnormality of the transfer medium based on the comparison result,
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on a transfer medium where an image formed by the printing image data does not exist, the difference image is an abnormal image. It is characterized by determining that it is different.

  An invention of an image forming apparatus according to another aspect is characterized in that, in the invention according to another aspect, the control unit performs determination of an image as a difference in the overprint printing.

  In another aspect of the invention of the image forming apparatus, in the aspect of the invention of the other aspect, the control unit obtains a variation in the image in the difference when there is a difference image different from the abnormal image in the image non-arranged region, When the variation is equal to or greater than a predetermined value, the job is determined to be reprint printing.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit obtains a variation in the image in the difference when there is a difference image different from the abnormal image in the image non-arranged region, When the variation is less than a predetermined value, it is determined that the transfer medium is colored.

  According to another aspect of the invention of the image forming apparatus, in the invention of another aspect, the control unit corrects an abnormality detection parameter when determining abnormality when the transfer medium is colored.

  In another aspect of the invention of the image forming apparatus, the abnormality detection parameter to be corrected is a threshold of the gradation value in the difference.

  According to another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit calculates a difference average value of images that are different in the image non-arranged region, and the calculated average value is in a state in which there is no difference. And the difference is corrected to a difference from the changed reference.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit generates an optimal abnormality detection parameter by registering the transfer medium type, and the abnormality detection parameter is set when the abnormality is detected. It is characterized by using.

  An invention of an image forming apparatus according to another aspect is characterized in that, in the invention according to another aspect, the control unit does not detect abnormality in an image non-arranged area when the job is reprint printing.

  According to another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit uses the data of the preceding image for the image non-arranged area when the job is reprint printing. The second anomaly detection is performed by comparing the image in FIG. 5 with the image based on the job printing image data and the reprint image data.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit uses an image obtained by combining an image based on image data for printing a job and a preceding image in the image non-arranged area, The second abnormality detection is performed by comparing with an image in the image reading result.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the data of the preceding image is obtained by reading the data for printing the preceding image or by reading the image of the transfer medium on which the preceding image is printed in advance. It is characterized by being.

  According to another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit, when the job is reprint printing, for the image non-arranged area, from the image reading result, the image of the image non-arranged area And extracting the extracted image as a preceding image in the image non-arranged region.

  The invention of another form of the image forming apparatus is characterized in that, in the invention of the other form, the control unit makes a correct image after confirming or / and correcting an image in the image non-arranged region or a synthesized image. To do.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit presents an image for confirming whether the image is a correct image to the user, and displays the image based on a confirmation process of the user. A correct image is used.

The invention of another form of the image forming apparatus has an operation display unit capable of displaying information and inputting an operation in the invention of another form,
The control unit performs the presentation through the operation display unit.

The invention of another form of the image forming apparatus has a storage unit for storing information in the invention of another form,
The control unit registers a correct image in the storage unit.

  In another aspect of the invention of the image forming apparatus, in the invention of the other aspect, the control unit may determine that when the job is reprint printing, there is a difference image that is different from the abnormal image in the image non-arranged area. When the difference image and the image in the image non-arranged area registered in the storage unit are compared, and there is the same image in the storage unit, the image that is the same image and the print image data for the job And an image obtained by the above-described image reading, and used for the second abnormality detection by comparing with the image in the image reading result.

An invention of an image forming apparatus of another form is the image data in which the image data for printing of the job is RIP processed in the invention of another form,
It has a RIP processing unit that receives RIP image data and converts the received RIP image data into printable image data that can be printed by RIP processing.

  In another aspect of the invention of the image forming apparatus, the job is variable printing.

The first embodiment of the image abnormality detection device of the present invention includes at least an input unit for inputting image data for printing a job and an image reading result obtained by reading an image formed on a transfer medium;
A control unit that acquires image data for printing a job and an image reading result from the input unit,
The control unit acquires the image reading result, compares the image in the image reading result with an image related to the printing image data, and detects abnormality of the transfer medium based on the comparison result Has the function of
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the printing image data does not exist, the difference image is an abnormal image. It is characterized by determining that it is different.

  In another aspect of the invention of the image abnormality detection device according to the aspect of the invention, in the case where the job is reprint printing, the control unit uses the data of the preceding image for the image non-arranged area. The second abnormality detection is performed by comparing the image in the result with the image of the print image data for job and the data of the reprint image.

The first form of the management apparatus according to the present invention controls an image forming unit that forms an image on a transfer medium based on a job, and an image reading unit that reads the image on the transfer medium and obtains a read image. A control unit to
An input unit for acquiring a reading result of the image reading unit,
The control unit acquires the print image data of the job, compares the image in the image reading result acquired by the image reading unit and the image related to the image data for printing, and based on the comparison result on the transfer medium Has an abnormality detection function to detect the presence or absence of image abnormality,
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the printing image data does not exist, the difference image is an abnormal image. It is characterized by determining that it is different from.

  In another aspect of the invention of the management apparatus, in the invention of the other aspect, the control unit uses the data of the preceding image for the image non-arranged area in the image reading result when the job is reprint printing. The second abnormality detection is performed by comparing the image with the image of the printing image data for the job and the data of the reprint image.

A first form of the control program according to the present invention controls an image forming unit that forms an image on a transfer medium based on a job, and an image reading unit that reads the image on the transfer medium and obtains a read image. A control program executed by the control unit
Obtaining an image reading result obtained by reading an image on a transfer medium;
An abnormality detection step of comparing an image in the image reading result with an image related to the printing image data and detecting the presence or absence of an abnormality of the transfer medium based on the comparison result;
In the abnormality detection step, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the print image data does not exist, the difference image is abnormal. It is determined that the image is different from the image.

  The invention of the control program of another form is the invention of the other form.In addition, when the job is reprint printing, the image in the image reading result is used for the image non-arranged area using the data of the preceding image. The image processing apparatus includes a step of performing second abnormality detection by comparing the print image data for the job and the image of the reprint image data.

  According to the present invention, when an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium, the transfer medium is determined by determining that the image that is the difference is different from the abnormal image. An abnormality can be detected in consideration of the image in the upper image non-arranged region.

1 is a diagram showing a mechanical outline of an image forming apparatus according to an embodiment of the present invention. Similarly, it is a block diagram. Similarly, it is a diagram for explaining a method of detecting a stain on a sheet by comparing a correct image and an inspection image. Similarly, it is a figure which shows the difference of the correct image and test | inspection image when additional printing is performed. Similarly, it is a diagram illustrating a procedure for re-creating a correct image by combining a print image and an image before reprinting. Similarly, it is a diagram showing a correct image and an inspection image when an image is formed on a colored sheet. Similarly, it is a figure which shows the profile of the difference at the time of detecting a dirt image. Similarly, it is a figure which shows the profile of the difference at the time of detecting the smudge image on a colored paper. Similarly, it is a flowchart showing a procedure for executing an abnormality detection operation.

An image forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.
An image forming apparatus 1 whose mechanical outline is shown in FIG. 1 includes an apparatus main body 10 and a reading device 20 connected to a paper discharge side of the apparatus main body 10. The apparatus main body 10 and the reading apparatus 20 are electrically and mechanically connected to each other so that paper can be conveyed and communicated between the apparatuses.
Although the image forming apparatus of the present embodiment is configured by the apparatus main body 10 and the reading apparatus 20, the configuration of the image forming apparatus of the present invention is not limited to this, and other apparatuses may be connected. For example, a relay device having a buffer mechanism may be provided between the apparatus main body 10 and the reading device 20, and a post-processing device that performs desired post-processing is provided on the paper discharge side of the reading device 20. Also good.

  The apparatus main body 10 includes an operation display unit 140 on the upper side of the housing. The operation display unit 140 includes an LCD having a touch panel, and can display information and input an operation by an operator. The operation display unit 140 constitutes an operation unit and also serves as a display unit. In the present invention, the operation unit and the display unit can be configured separately.

A plurality of paper feed trays 11 are provided on the lower side of the apparatus body 10. The paper feed tray can store paper. The paper corresponds to the transfer medium of the present invention. In the present invention, the transfer medium is not limited to paper, but may be made of a material such as plastic or cloth. It is also possible to use a continuous transfer medium.
In the apparatus main body 10, a conveyance path 12 that conveys paper fed from the paper feed tray is provided, and the conveyance path 12 is connected to a conveyance path 22 of the reading apparatus 20 at the subsequent stage.

  An image forming unit 110 is provided in the middle of the conveyance path 12, and the image forming unit 110 forms an image on a sheet conveyed on the conveyance path 12 by an electrophotographic method. The image forming unit 110 includes a photoconductor 110A, and a developing device, a charger, and a transfer unit (not shown) are provided on the periphery of the photoconductor 110A. These downstream conveyance paths have a fixing unit 110B, and the photoconductor 110A, developing unit, charging unit, transfer unit, fixing unit 110B, and the like constitute an image forming unit.

  In the conveyance path 12, the reverse conveyance path 15 is branched at a position downstream of the fixing unit 110B. The reverse conveyance path 15 is joined at the downstream end to the conveyance path 12 on the upstream side of the image forming unit 110. In the reversing conveyance path 15, a reversing unit 15A into which a sheet is introduced and carried out from the rear end side of the sheet is branched in the middle, and the reversing unit 15A transfers the introduced sheet to either the downstream side or the upstream side. Can send. When an image is formed on the back side of the sheet, the sheet is sent from the conveyance path 12 to the reverse conveyance path 15 and is reversed by the reversing unit 15A, and then sent to the downstream side of the reverse conveyance path 15 and conveyed to the conveyance path 12. Perfused. The image formed on the back side of the sheet is formed on the back side of the sheet by the image forming unit 110. When the sheet is simply turned upside down and sent to the downstream side of the conveyance path 12, the sheet sent to the reversing unit 15 </ b> A is returned to the upstream side of the reverse conveyance path 15 and sent to the discharge side of the conveyance path 12 as it is.

The reading device 20 has a conveyance path 22 connected to the apparatus main body 10, and the conveyance path 22 discharges the sheet outside the reading device 20.
An image reading unit 25 is provided in the middle of the conveyance path 22, and the image reading unit 25 is configured by a line sensor using a CCD, a CIS sensor, or the like. The image reading unit 25 reads an image on the upper surface of the sheet sent through the conveyance path 22 and transmits the read result to the control unit in the image forming apparatus 1.

Further, in the conveyance path 22, a reverse conveyance path 23 is branched at a position downstream of the image reading unit 25, and a downstream end of the reverse conveyance path 23 joins the conveyance path 22 on the upstream side of the image reading unit 25. . The reversing conveyance path 23 has a reversing unit 23A that is introduced and carried out from the rear end side of the paper in the middle, and the reversing unit 23A sends the introduced paper to either the downstream side or the upstream side. be able to.
When reversing the paper and reading the back side of the image, the paper sent to the conveyance path 22 is once introduced into the reversing unit 23A, and then sent to the downstream side of the conveyance path 22 and the image reading unit 25 reads the image on the back side of the paper. read. When the paper that has passed through the image reading unit 25 is simply reversed, the paper that has been sent to the conveyance path 22 is once introduced into the reversing unit 23A, and then sent to the conveyance path 23B from the upstream side of the conveyance path 23 and passes through the conveyance path 22 as it is. Transport to the paper discharge side.

  In the image forming apparatus 1 of the present embodiment, the image reading unit 25 is provided in the reading device 20, but the image reading unit is provided inside the apparatus main body 10 or an external device different from the image forming apparatus 1. An image reading unit may be provided. The apparatus body 10 and the reading apparatus 20 may not be mechanically connected. In this case, the reading result of the reading apparatus 20 can be acquired by the apparatus body 10 via a network or a removable storage medium. It can be set as a simple structure.

Next, a control block of the image forming apparatus according to the present embodiment will be described.
FIG. 2 shows an electrical block diagram of the image forming apparatus 1.
The image forming apparatus 1 includes a CPU 100, a storage unit (memory) 101, a storage unit (HDD) 102, a data input / output unit 103, an image forming unit 110, a RIP processing unit 120, an image reading unit 25, and an operation display unit 140. ing. Each unit is connected to a common bus, and can communicate with each other via the common bus.

  The control unit 105 includes a CPU 100, a storage unit (memory) 101 such as a ROM or a RAM, a program that operates on the CPU 100, and the like. The program can be stored in a ROM or the like. The CPU 100 reads a system program and various processing programs stored in the storage unit (memory) 101, the storage unit (HDD) 102, and the like, expands them in a RAM, executes various processes according to the expanded programs, and an image forming apparatus Control the operation of each part.

In addition, the control unit 105 has an abnormal image detection function that acquires a reading result from the image reading unit 25, compares the reading result, detects whether there is a difference, and determines whether there is an abnormality based on the comparison result. Can be executed. In abnormal image detection, it is possible to determine whether the difference is not abnormal. In this case, it is also possible to determine whether the difference is an image before reprinting or is colored.
A program for performing the operation is stored in the ROM, the storage unit (memory) 101, the storage unit (HDD) 102, or the like of the control unit 105, and further, the storage unit (memory) 101 or the storage unit (HDD) 102. Stores a parameter for detecting an abnormality, a predetermined value areaTH for determining whether the difference is abnormal, a predetermined value errTH of variation for determining whether the difference is an image before reprinting or coloring, and the like. ing. The programs and parameters may be stored in a removable storage medium and distributed.

  The storage unit (memory) 101 and the storage unit (HDD) 102 can store information, and in addition to programs and various setting values, image data for printing and job data, and read images acquired by the image reading unit 25 The correct image data of the preceding image before reprinting, the correct image data obtained by synthesizing the reprint image and the preceding image, sheet setting information, and desired data such as an abnormality detection result are stored. The storage unit (memory) 101 may include a volatile memory and a nonvolatile memory.

  The data input / output unit 103 is a device that performs data input / output, and performs data input / output to / from the storage unit (memory) 101 and the storage unit (HDD) 102 and data communication with the external device 3.

The image forming unit 110 forms an image on a sheet. In the image forming unit 110, the LD of the image forming unit 110 forms a latent image on the photoreceptor 110A based on the image data. Thereafter, the latent image is developed by the developing device to become a toner image, and the toner image is transferred to the paper. The fixing unit 110B applies heat and pressure to the image transferred to the paper, and the image is fixed on the paper. The Note that the image forming unit 110 can perform reprint printing on a sheet on which an image is formed in advance.
In this embodiment, an image forming unit for a single color is displayed. However, the present invention may be an image forming apparatus having an image forming unit capable of color printing.

  The RIP processing unit 120 performs RIP processing for converting image information described in page description terms into a raster image. The image data subjected to the RIP process is transmitted as image data for printing to the image forming unit 110, and the image forming unit 110 performs image formation based on the image data after the RIP process. Note that the image data may be obtained from outside image data read by a scanner (not shown) or image data of a raster image.

  The image reading unit 25 optically reads an image on a sheet and acquires read image data. The read image data is transferred to the storage unit (memory) 101, the storage unit (HDD) 102, and the like, and the control unit 105 acquires the read image data. The read image data corresponds to the image reading result of the present invention.

  The operation display unit 140 is controlled by the control unit 105 and displays information and accepts operation inputs.

An external device 3 is connected to the image forming apparatus 1 via a network, a serial cable, or the like. The external device 3 has an external control unit 30 and a storage unit 31. The external control unit 30 is constituted by a CPU and a program that operates on the CPU, and can control the image forming apparatus 1 in addition to controlling the external apparatus 3. When the external control unit 30 controls the image forming apparatus 1, the external device 3 corresponds to the management device of the present invention, and the external control unit 30 corresponds to the control unit of the present invention.
The external device 3 may be configured by a PC, and an HDD, a server, or an arbitrary device may be used as the external device 3. The external device 3 may have only the storage unit 31. The storage unit 31 stores image data for the preceding image in follow-up printing, the correct image of the preceding image data obtained by reading the preceding image in advance, and the correct image data obtained by combining the image data for follow-up printing and the preceding image data. Can be stored.

Next, the basic operation of the image forming apparatus 1 will be described.
When an image is formed by the image forming apparatus 1, image data input from the external apparatus 3 or the like is converted into print image data by the RIP processing unit 120. As the image data, image data for printing read by a scanner or image data of raster data acquired from the outside can be used. The image data for printing is subjected to image processing as necessary, and then image formation on the paper is performed by the image forming unit 110. Specifically, in the image forming unit 110, the charger uniformly charges the surface of the photoreceptor 110A, and irradiates the semiconductor 110A having the surface charged uniformly with a semiconductor laser based on the image data. As a result, an electrostatic latent image is formed on the photoconductor 110A. The electrostatic latent image formed on the photoconductor 110A is developed with a toner material of a developing device to form a toner image. The transfer unit transfers the toner image on the photoconductor 110 </ b> A to the paper conveyed from the paper feed tray 11. The sheet on which the toner image has been transferred is separated from the photoreceptor 110A, conveyed to the fixing device 110B, and is fixed on the sheet as an output image by applying heat and pressure. When image formation is performed on the back surface, the image is formed on the back surface side through the reverse conveyance path 15 and fixing processing is performed. The paper to be discharged after the fixing process is conveyed to the reading device 20. The reading device 20 reads an image on one side or both sides of a sheet. The print image data is also stored in the storage unit as a correct image of the printed matter.

  Next, an abnormality determination operation for reading a print image by the image reading unit 25 of the image forming apparatus 1 and detecting an abnormality of the image on the paper will be described.

  The sheet on which the image is formed by the image forming unit 110 is conveyed to the reading device 20, and the image on the front surface is read by the image reading unit 25 of the reading device 20. The read image data obtained by the reading is transmitted to the control unit 105 as an image reading result. The control unit 105 can compare the read image with the inspection image based on the print image data to detect the difference and determine the presence or absence of an abnormal image on the paper.

The schematic diagram in FIG. 3 shows a correct image I1 based on print image data, an inspection image I2 obtained by reading an image on a sheet, and a difference image I3 that is a difference between the correct image I1 and the inspection image I2. Yes.
In this example, the correct image I1 includes only the image IM1, but since the inspection image I2 includes the image IM1 and the dirt portion G, the stain portion G is detected as a difference in the difference image I3. . Therefore, it is determined that an abnormal image exists on the paper. The dirty part G corresponds to the abnormal image of the present invention. In the present invention, the abnormal image is not limited to dirt, and can be an abnormal portion such as a streak or a scratch. If it is determined that an abnormal image exists on the paper, the image forming operation may be stopped, and the paper having the abnormal image is discharged from the normal paper discharge destination without stopping the image forming operation. The sheet may be discharged.

  However, if the printing is reprint printing, comparing the correct image with the inspection image, the image before reprinting is also detected as a difference, so even if an abnormal image exists on the paper, the pre-printing image Cannot be distinguished from abnormal images, and abnormal images cannot be detected accurately.

FIG. 4 shows the correct image I1 which is image data for printing, the inspection image I4 acquired by reading the image on the paper, and the difference which is the difference between the correct image I1 and the inspection image I4 when the additional printing is performed. It is a figure which shows the image I5.
In this example, the image IM2 is pre-printed on the sheet before printing, and the image IM1 is additionally printed on the sheet. Therefore, the inspection image I4 is additionally printed in addition to the image IM1 that is the print image. The previous image IM2 and the dirty part G exist. For this reason, if the difference is taken, the smudged portion G and the image IM2 before reprinting are detected as a difference, and there arises a problem that the stain and the image before reprinting cannot be distinguished as they are.

  On the other hand, in the present embodiment, whether the difference is an abnormal image depends on whether an image having a predetermined size or larger exists as a difference in an image non-arranged area where no image formed by the print image data exists. judge. Specifically, as shown in FIG. 5, it is detected whether an image difference has occurred in the image non-arranged area NA. If there is a difference, the area of the area is calculated. If the calculated area is equal to or larger than a predetermined value (areaTH), it is determined that the area is different from the abnormal image. When there are a plurality of difference areas, the calculation is performed for each area.

In FIG. 5, for example, an image IM2 and an image G are extracted from the correct image I1 that is a print image by using the non-placed area as a follow-up correct image area. In this state, since it cannot be confirmed that the image is a pre-reprint image, for example, an image is provided to the user and the image G which is the NG portion is deleted, and the correct image I6 is set. The pre-printing image can be created by detecting the difference between the read image acquired by scanning and the image data for printing.
The image based on the printing image data and the follow-up correct image can be combined to form the entire correct image I7. The whole correct image I7 can detect the presence or absence of abnormality by comparing with the inspection image. The abnormality detection at this time corresponds to the second abnormality detection in the present invention.

On the other hand, even if a region having a difference has a certain size, it may not be appropriate to determine that all are not abnormal images. One of them is a case where the paper is colored paper and the background color is printed. Colored paper includes specially processed paper such as lame and foil. In this case, the color of the paper appears as a difference, and since the difference area is large, the image does not become an abnormal image, and even if dirt or the like exists in the image, it is overlooked.
Therefore, variation in a region with a difference is measured. For example, the pixel value is seen as the variation. If the paper is colored, the variation in pixel values will be small, so if the variation is less than a certain value (errTH), it will be judged as colored paper, and if the variation is more than a certain value, there will be an image before reprinting Judge that you are doing. The target of the variation is not limited to the image value, and may be determined based on appropriate characteristics. The method for calculating the variation is not particularly limited, and a standard deviation of the pixel value may be used.

  When the variation in pixel values is equal to or greater than a certain value (errTH), that is, when it is determined that an image before reprinting is formed on the paper, an area where the image before reprinting is present is an area that is not subject to abnormal image inspection. It is good. In that case, even if a difference occurs in an area where an image formed by print image data does not exist, it is possible not to perform abnormality determination that does not take this into account. However, since an abnormality may occur even in a region where the reprint printing is not performed, it is desirable that the region of the pre-reprint image is also the inspection target.

Therefore, the image in the image non-arrangement area is synthesized with the image data for printing, the synthesized image is used as a correct image, and the correct image is compared with the inspection image. Thereby, the second abnormality detection for inspecting the image before reprinting can be performed.
However, if the image in the image non-arranged area is extracted from the read image, it may contain dirt. Therefore, when it is determined that it is reprint printing, an area determined to be an image before reprinting is presented to the user, and whether or not this image can be combined with the correct image is confirmed or / and corrected. To. As a result, it is possible to generate a correct image from which the contaminated portion is excluded. Presentation to the user can be performed by display on the operation display unit 140 or display on the external device 3, and confirmation by the user can also be performed through the operation display unit 140 or the external device 3.

  In this embodiment, the pre-reprint image is extracted from the read image of the paper after the reprint printing, and the extracted pre-reprint image is used for abnormality determination. The image reading result may be acquired and used for abnormality determination in an area where no image based on print image data exists, or print data used for a preceding image before reprinting may be used.

  On the other hand, if the variation of the pixel value in the difference area is less than a certain value (errTH), it is determined that the paper is colored. Although it is conceivable to synthesize correct images, it is assumed that the target area becomes considerably wide and it takes time and effort to confirm the presence or absence of dirt. Therefore, when the color paper is determined, the abnormal image detection parameter is corrected. An example of the parameter to be changed is a threshold of gradation values in the difference.

When printing is performed on colored paper and the read image is compared with the printed image, both the smudged portion and the color are detected as differences.
FIG. 6 is a diagram illustrating a correct image I1 that is print image data and an inspection image I8 that is read image data when an image is formed on a colored sheet. In this example, when the correct image I1 and the inspection image I8 are compared, the color B is detected as a difference together with the dirty portion G.
FIG. 7 is a graph for detecting dirt detected when the difference between images is taken. In a region where there is a dirt image, the gradation value becomes high and exceeds the threshold value TH1, indicating that there is a dirt image, and the gradation value is low in the surrounding area where there is no dirt. .

However, in the case of colored paper, the gradation value rises by a certain value together with the area where there is no stain. As shown in FIG. 8, when an abnormality is determined using the normal stain detection threshold value TH1, a difference between the gradation values equal to or greater than the threshold value TH1 is detected even in a non-stained color region and determined as NG. Both the dirty image and the entire color are determined to be abnormal.
Therefore, a value obtained by adding a certain amount to the normal threshold value is set as a new threshold value. As a result, the difference value in the region where only the background color exists becomes a reference for no difference, so that the background color is not detected as abnormal, and appropriate stain detection can be performed.

  The amount of addition to the threshold value can be obtained by calculating the average value X of the areas where there is a difference in the image non-arranged area where there is nothing on the print image data. The average value X is added to the stain detection threshold value TH1 to obtain a stain detection threshold value TH2 for colored paper. After that, by determining the abnormality using the stain detection threshold value TH2 for colored paper, the background color is not determined to be abnormal, but only the dirty portion is determined to be abnormal. By dynamically shifting the threshold value in this way, the difference exceeds the threshold only in the area where the dirty image exists, and only the dirty part can be detected.

  Since this value is more accurate when executed under conditions with a larger scan area, it is possible to perform pre-registration by scanning in the blank page mode when registering the paper type. With respect to the registered paper type, it is possible to set parameters with higher accuracy, and by using the parameters registered at the time of abnormality determination, it is possible to perform abnormality determination appropriately. The added amount is stored in the storage unit in association with the paper type. An optimum threshold value may be generated by setting the density of a sheet by registering the sheet type.

  Further, since the pre-print image can be used repeatedly, it is possible to register the pre-print image that is the correct image. This eliminates the trouble of re-checking whether the same image is dirty by searching for and using the same image from the registered images when it is determined that the next reprinting is to be performed. The image before reprinting can be stored in the storage unit (memory) 101, the storage unit (HDD) 102, the storage unit (HDD) 31 of the external device 3, and the like.

  In the present embodiment, the print image data and the pre-print image data are combined and the combined image is used for abnormality determination. However, the print image data area is printed without combining the images. The second abnormality determination may be performed by comparing with the image data and comparing with the image before reprinting in an area where the image based on the print image data is not formed.

  A detailed procedure of the above operation will be described with reference to the flowchart of FIG. The following procedure is performed by the control unit.

When the image on the paper is read by the scanner and the abnormal image detection process is started, it is confirmed whether there is a dedicated parameter for paper registration (step s1). The dedicated parameter can be registered in step s20 described later, but can be arbitrarily set by the user.
If there is no dedicated parameter (step s2, Yes), the abnormal image detection parameter is set to a default value (step s3). On the other hand, if there is a dedicated parameter (No in step s2), the abnormal image detection parameter is set to a paper dedicated value (step s4). As the default value, one set in advance for general use or one prepared for a specific sheet can be used.

After step s3 or step s4, the difference between the RIP image (print image) and the scanned image (read image) is calculated (step s5), and it is determined whether there is a difference (step s6). If there is no difference (No in step s6), it is determined that there is no abnormal image (step s8), and the procedure is terminated.
On the other hand, if there is a difference (step s6, Yes), the area of the region in which the difference has occurred is calculated (step s7), and it is determined whether the area of the region in which the difference has occurred is greater than or equal to a predetermined threshold areaTH ( Step s9). areaTH is used in the present invention to indicate the magnitude of the difference. In the present invention, the magnitude of the difference is not limited to the area, and the magnitude of the difference may be determined using the length or ratio in the main scanning direction or the sub-scanning direction.

When the area of the difference is less than areaTH (step s9, No), it is determined that there is an abnormal image (step s11), and the procedure is terminated.
On the other hand, in step s9, when the area of the region in which the difference has occurred is equal to or larger than areaTH (step s9, Yes), it is determined that the image is not an abnormal image (step s10), and the difference pixel value in the region in which the difference has occurred is determined. The variation is calculated (step s12). Next, it is determined whether the variation in the difference pixel value is equal to or greater than errTH (step s13).

If the variation in the difference pixel value is less than errTH (step s13, No), it is determined that the paper is colored paper (step s19), and optimum parameters are calculated and registered (step s20). The optimum parameter can be calculated from normal parameters and variations. The optimum parameter can be registered in association with the paper, and the parameter registered at the time of paper registration can be used.
Further, the abnormal image is redetected (second abnormality detection) using the optimum parameter (step s21), and the procedure is terminated.

  If the difference in the difference pixel value is equal to or greater than errTH (step s13, Yes), it is determined that the difference is an image before reprinting (step s14). Thereafter, the image is compared with the registered image before reprinting (step s15), and it is determined whether the registered image before reprinting includes the same image (step s16). If there is the same image (step s16, Yes), the RIP image (print image) and the registered pre-print image are combined to recreate the entire correct image (step s17). The created correct image and the read image are compared to detect the second abnormal image (step s18).

  On the other hand, when there is no identical image in step s16 (step s16, No), an image before reprinting in the image non-arrangement area is extracted from the read image and presented to the user (step s22). Examples of the presentation method include display on the operation display unit 140 and display on the display unit of the external device 3 as examples. The user corrects (confirms / corrects) the presented image, and determines whether the image is the correct pre-printing image. If the user correction shows that the answer is correct, the RIP image (image before printing) and the image before reprinting are combined to recreate the correct image (step s23), and the recreated correct image is compared with the scanned image. Then, an abnormal image is detected (step s18).

  As the pre-printing image, a reading result obtained by reading the pre-printing image or an image for printing the pre-printing image can be used.

In this embodiment, abnormality detection or the like is performed by a control unit provided in the apparatus main body 1. However, a control unit may be provided in the reading device 25, and abnormality detection or the like may be performed by the control unit. The apparatus may be outside the image forming apparatus. The control unit may be prepared as an image abnormality detection device as one that receives an image reading result or the like at the input unit to detect abnormality, and the abnormality detection device is provided in the image forming apparatus, It may be prepared as a reading device inside or outside the image forming apparatus or an external device outside the image forming apparatus.
Furthermore, abnormality detection or the like may be performed by a control unit in a management apparatus that manages the image forming apparatus.

  According to the present embodiment, it is possible to detect abnormal images such as dirt in an image without requiring print data of an image before reprinting.

  Although the present invention has been described based on the above embodiment, the scope of the present invention is not limited to the content of the above description, and appropriate modifications to the above embodiment can be made without departing from the scope of the present invention. Is possible.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Network 3 External apparatus 11 Paper feed tray 12 Conveyance path 15 Reverse conveyance path 20 Reading apparatus 22 Conveyance path 25 Image reading part 105 Control part 110 Image formation part 140 Operation display part I1 Correct image I2 Inspection image I3 Difference image I4 Inspection image I5 Difference image I6 Correct image for composition I7 Composite correct image I8 Inspection image IM1 Print image IM2 Image before reprinting NA Unallocated region G Dirt

Claims (26)

An image forming unit that forms an image on a transfer medium based on a job;
A control unit for controlling the image forming unit,
The control unit acquires an image reading result obtained by reading an image of a transfer medium on which an image is formed by the image forming unit, and compares the image in the image reading result with an image based on image data for printing a job, Having a function of abnormality detection to detect the presence or absence of abnormality of the transfer medium based on the comparison result,
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on a transfer medium where an image formed by the printing image data does not exist, the difference image is an abnormal image. An image forming apparatus characterized in that it is determined to be different.   The image forming apparatus according to claim 1, wherein the control unit performs determination of an image serving as a difference in follow-up printing.   When there is an image with a difference different from an abnormal image in the image non-arranged area, the control unit obtains image variation in the difference, and when the variation is equal to or greater than a predetermined value, the job is reprint printing. The image forming apparatus according to claim 1, wherein:   The control unit obtains a variation in the image in the difference when there is an image with a difference different from the abnormal image in the image non-arranged region, and the transfer medium is colored when the variation is less than a predetermined value. The image forming apparatus according to any one of claims 1 to 3, wherein the image forming apparatus is determined.   The image forming apparatus according to claim 1, wherein when the transfer medium is colored, the control unit corrects an abnormality detection parameter when determining abnormality.   6. The image forming apparatus according to claim 5, wherein the abnormality detection parameter to be corrected is a threshold value of a gradation value in the difference.   The control unit calculates a difference average value of images that are different in the image non-arranged region, changes the calculated average value to a reference in a no-difference state, and changes the difference to a difference from the changed reference. The image forming apparatus according to claim 5, wherein the image forming apparatus is corrected.   The said control part produces | generates the parameter for optimal abnormality detection by registration of a transfer medium classification, and uses the said parameter for abnormality detection at the time of abnormality detection, The said any one of Claims 5-7 characterized by the above-mentioned. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit does not detect abnormality in an image non-arranged area when the job is reprint printing.   When the job is reprint printing, the control unit uses the data of the preceding image for the image non-arranged area, the image in the image reading result, the image data for printing for the job, and the data of the reprint image. The image forming apparatus according to claim 1, wherein the second abnormality detection is performed by comparing with an image.   The control unit performs the second abnormality detection by using an image obtained by combining an image based on print image data of a job and a preceding image in the image non-arranged region and comparing the image with the image in the image reading result. The image forming apparatus according to claim 10.   The image formation according to claim 10 or 11, wherein the data of the preceding image is data for printing the preceding image or obtained in advance by image reading of a transfer medium on which the preceding image is printed. apparatus.   When the job is reprint printing, the control unit extracts an image of the image non-arranged area from the image reading result for the image non-arranged area, and sets the extracted image as a preceding image in the image non-arranged area. The image forming apparatus according to claim 10, wherein the image forming apparatus is an image forming apparatus.   14. The image forming apparatus according to claim 10, wherein the control unit sets a correct image after confirming and / or correcting an image in the image non-arranged region or a combined image.   The image forming apparatus according to claim 14, wherein the control unit presents an image for confirming whether the image is a correct image to the user, and sets the image as a correct image based on a user confirmation process. It has an operation display unit that can display information and input operations,
The image forming apparatus according to claim 15, wherein the control unit performs the presentation via the operation display unit. A storage unit for storing information;
The image forming apparatus according to claim 14, wherein the control unit registers a correct image in the storage unit.   In the case where the job is reprint printing, when the difference image different from the abnormal image exists in the image non-arranged area, the control unit and the image not registered registered in the storage unit Compare the images in the area, and if there is the same image in the storage unit, the image that is the same image and the image by the print image data of the job are combined and compared with the image in the image reading result The image forming apparatus according to claim 17, wherein the image forming apparatus is used for the second abnormality detection. The print image data of the job is image data that has undergone RIP processing;
19. The image according to claim 1, further comprising a RIP processing unit that receives RIP image data and converts the received RIP image data into printable image data that can be printed by RIP processing. Forming equipment.   The image forming apparatus according to claim 1, wherein the job is variable printing. At least an input unit for inputting image data for printing of a job and an image reading result obtained by reading an image formed on a transfer medium;
A control unit that acquires image data for printing a job and an image reading result from the input unit,
The control unit acquires the image reading result, compares the image in the image reading result with an image related to the printing image data, and detects abnormality of the transfer medium based on the comparison result Has the function of
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the printing image data does not exist, the difference image is an abnormal image. An image abnormality detection device that determines that the image is different from the above.   When the job is reprint printing, the control unit uses the data of the preceding image for the image non-arranged area, the image in the image reading result, the image data for printing for the job, and the data of the reprint image. The image abnormality detection device according to claim 21, wherein the second abnormality detection is performed by comparing with an image. A control unit that controls an image forming unit that forms an image on a transfer medium based on a job, and an image reading unit that reads an image on the transfer medium and obtains a read image;
An input unit for acquiring a reading result of the image reading unit,
The control unit acquires the print image data of the job, compares the image in the image reading result acquired by the image reading unit and the image related to the image data for printing, and based on the comparison result on the transfer medium Has an abnormality detection function to detect the presence or absence of image abnormality,
When the abnormality is detected, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the printing image data does not exist, the difference image is an abnormal image. A management device characterized in that it is determined that it is different from the management device.   When the job is reprint printing, the control unit uses the data of the preceding image for the image non-arranged area, the image in the image reading result, the image data for printing for the job, and the data of the reprint image. 24. The management apparatus according to claim 23, wherein the second abnormality detection is performed by comparing with an image. A control program executed by a control unit that controls an image forming unit that forms an image on a transfer medium based on a job, and an image reading unit that reads an image on the transfer medium and acquires a read image,
Obtaining an image reading result obtained by reading an image on a transfer medium;
An abnormality detection step of comparing an image in the image reading result with an image related to the printing image data and detecting the presence or absence of an abnormality of the transfer medium based on the comparison result;
In the abnormality detection step, if an image having a predetermined size or more exists as a difference in an image non-arranged area on the transfer medium in which an image formed by the print image data does not exist, the difference image is abnormal. A control program for determining that the image is different from the image.   Further, when the job is reprint printing, for the image non-arranged area, the image in the image reading result and the image by the print image data for the job and the reprint image data are used by using the data of the preceding image. The control program according to claim 25, further comprising a step of performing a second abnormality detection by comparison.

Images