JP2005208264A - Control device, control method, and control program for image forming apparatus or inspecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for an image forming apparatus, with which the cleaning failure in the image forming apparatus can be properly detected. <P>SOLUTION: The control method includes: a step S12 of obtaining print result image data read from the print result of image formed on paper by the image forming apparatus; a step 18 of determining a defect detection target area which is a target for detecting a defect from the print result image data obtained in the step S12; and a step S20 of detecting the defect from the defect detection target area determined in the step S18. By the control method, a reference in determining the defect detection target area in the step S18 can be changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device, a control method, and a control program for detecting a defect in an image formed by an image forming apparatus.

  It is important to determine whether or not a print result image printed on a sheet in an image forming apparatus such as a copying machine, a digital multifunction peripheral, or a printer is defective.

  As shown in FIG. 10, the electrophotographic image forming apparatus includes a static eliminating unit 12 that neutralizes the photosensitive member 10 in order to remove unnecessary toner remaining on the photosensitive member 10 after the toner is transferred to a sheet, and a photosensitive member. A cleaning unit including a cleaning brush 14 and a cleaning blade 16 that mechanically removes toner remaining in the toner 10 and a toner collection container 18 that collects toner removed from the photoreceptor 10 is provided.

  If the surface of the photoconductor 10 is scratched or the cleaning brush 14 or the cleaning blade 16 is worn, unnecessary toner remains on the photoconductor 10 even after cleaning. As a result, the remaining toner is transferred when the toner is transferred to the sheet next time, and a defect occurs on the sheet.

  As described above, the disturbance of the image due to the defect in the cleaning significantly deteriorates the quality of the print result image. Therefore, when a cleaning defect is found, it is necessary to immediately stop the image forming apparatus and replace the photosensitive member and the cleaning member. On the other hand, stopping the image forming apparatus when performing large-scale printing leads to an increase in printing time and an increase in printing cost, so that the defect in the printing result image is caused by defective cleaning. It is necessary to judge with certainty.

  Conventionally, a test pattern for finding a defect (image defect) is printed on a white plain paper or the like, and a printed defect is found by a person visually observing the printed test pattern.

  In addition, a halftone chart having a uniform gray brightness is printed as an inspection chart, and the print result of the inspection chart is read by a line sensor, and low contrast white and black colors appearing in the print result image are displayed. A technique for detecting a streak-like defect is disclosed (Japanese Patent Laid-Open No. 6-148096).

  Also disclosed is a technique for detecting a defect based on a stain distribution density obtained by reading a print result image from paper using a camera, detecting a stain candidate from the print result image data, and counting the number of candidates. (JP-A-6-168316).

Japanese Patent Laid-Open No. 6-148096 JP-A-6-168316

  However, in the above-described conventional technique, it has not been possible to determine whether or not the defect generated in the print result image is due to defective cleaning. Therefore, replacement of members could not be performed in a timely manner. In addition, when a high-quality image is required, it is necessary to stop the image forming apparatus for inspection even when a defect not caused by a cleaning defect occurs, and the printing time and printing cost Was inviting.

  The present invention provides a control device, a control method, and a control program that can appropriately detect a cleaning defect in an image forming apparatus in order to solve at least one of the above-described problems in view of the above-described problems of the related art. For the purpose.

  The present invention is a control device for an image forming apparatus, wherein the image data acquiring unit acquires print result image data read from a print result formed on a sheet in the image forming apparatus, and the image data acquiring unit. A detection target region determining unit that determines a defect detection target region that is a target for detecting a defect from the print result image data acquired in step S; and detecting a defect from the defect detection target region determined by the detection target region determination unit Defect detection means, and the reference for determining the defect detection target area in the detection target area determination means can be changed.

  In the case where the image forming apparatus is an apparatus that includes a component that supplies a coloring material to a sheet at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component, the detection target region determining unit It is preferable that the defect detection target region is determined based on the cycle.

  For example, it includes a high density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the document image data or the print result image data obtained by the image data obtaining means, and the detection target area determination Preferably, the means determines the defect detection target region based on the position of the high concentration region extracted by the high concentration region extraction unit. At this time, it is more preferable that the high density region determining means can change the density threshold. Furthermore, it is more preferable that the high concentration region determination means change the concentration threshold based on the past extraction history of the high concentration region.

  Another aspect of the present invention is a method for controlling an image forming apparatus, wherein the image data acquiring step acquires print result image data read from a print result formed on a sheet in the image forming apparatus, and A detection target region determining step for determining a defect detection target region as a target for detecting a defect from the print result image data acquired in the image data acquisition step; and the defect detection target region determined by the detection target region determination means A defect detection step of detecting a defect from the detection target region, wherein the reference for determining the defect detection target region in the detection target region determination step can be changed.

  In the detection target region determining step, when the image forming apparatus is an apparatus that includes a component that supplies a coloring material to paper at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component. It is preferable that the defect detection target region is determined based on the cycle.

  For example, the detection target region determination includes a high density region extraction step of extracting a high density region having a density equal to or higher than a predetermined density threshold from the document image data or the print result image data acquired in the image data acquisition step. Preferably, in the step, the defect detection target region is determined based on the position of the high concentration region extracted in the high concentration region extraction step. At this time, it is more preferable that the concentration threshold value can be changed in the high concentration region determination step. Further, in the high concentration region determination step, it is more preferable to change the concentration threshold based on the past extraction history of the high concentration region.

  Another aspect of the present invention is a control program for an image forming apparatus, wherein the computer acquires image data acquisition means for acquiring print result image data read from a print result formed on a sheet in the image forming apparatus. And means for determining a defect detection target area that is a target for detecting a defect from the print result image data acquired by the image data acquisition means, and changes a reference for determining the defect detection target area. And a defect detection means for detecting a defect from the defect detection target area determined by the detection target area determination means.

  In the case where the image forming apparatus is an apparatus that includes a component that supplies a coloring material to a sheet at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component, the detection target region determining unit It is preferable that the defect detection target region is determined based on the cycle.

  For example, the computer includes high density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the document image data or print result image data acquired by the image data acquisition means, and the detection The target area determining means preferably functions as a control device for determining the defect detection target area based on the position of the high density area extracted by the high density area extracting means. At this time, it is more preferable that the high density region determining means can change the density threshold. Further, it is more preferable that the high concentration region determination means change the concentration threshold based on the past extraction history of the high concentration region.

  According to the present invention, it is possible to appropriately detect a cleaning defect in an image forming apparatus.

  As shown in FIG. 1, the image forming system according to the embodiment of the present invention includes a control device 100, an image forming device 200, and an inspection device 300. The control device 100, the image forming device 200, and the inspection device 300 are connected to be able to transmit information to each other according to a predetermined protocol via an information transmission medium such as a network.

  The image forming apparatus 200 employs an electrophotographic system and can be configured to include a control unit 201, document image data acquisition unit 202, paper feeding unit 203, printing unit 204, paper discharge unit 205, and data interface 206.

  In the present embodiment, the document image data acquisition unit 202 includes a platen 222 and a scanner 224, the paper supply unit 203 includes a paper stocker 230 and a paper transport belt 232, and the printing unit 204 includes the photoconductor 10, the charging unit 240, and the exposure. The sheet discharge unit 205 includes a sheet discharge stocker 250. The sheet discharge unit 205 includes a unit 241, a development unit 242, a transfer unit 244, a fixing unit 245, and a cleaning unit 246. The image forming apparatus 200 is intended for color printing, and includes a photoconductor 10 corresponding to each color component in a CMYK color space represented by cyan (C), magenta (M), yellow (Y), and black (K). A charging unit 240, an exposure unit 241, a developing unit 242, a transfer unit 244, and a cleaning unit 246 are provided.

  The document image data acquisition unit 202 reads a document image from a document placed on the platen 222, digitizes the read document image, and sends it to the control unit 201 as document image data. The read document image data is transmitted to the control apparatus 100 via the network as needed using the data interface 206. The document image data may be received from an external computer or the like via the network using the data interface 206. For example, it is preferable that the control device 100 also serves as a computer that is a transmission source of document image data. The received document image data is temporarily stored in a buffer memory included in the control unit 201.

  Alternatively, the document image data may be stored and stored in the image forming apparatus 200, and the document image data to be printed may be specified by transmitting specific information from the control apparatus 100 using the data interface 260. The specific information refers to information used to specify original image data to be printed in the image forming apparatus 200.

  For example, as shown in FIG. 2, when a unique identification number is assigned to each original image data and stored in the buffer memory of the control unit 201, the specific information is assigned to the original image data to be printed. Identification number. In the example of FIG. 2, if the document image data to be printed is file A, the specific information is an identification number 001.

  The paper feeding unit 203 transports paper necessary for printing from the paper stocker 230 to the printing unit 204 and the paper discharge unit 205 by the paper transport belt 232. The direction along the carrying direction is called a sub-scanning line, and the direction perpendicular to the carrying direction is called a main scanning direction.

  The control unit 201 divides the original image data to be printed specified by the specific information into the planes of the respective color components in the CMYK color space and transmits them to the printing unit 204. The printing unit 204 performs printing on the paper based on the planes of the respective color components received from the control unit 201. The charging unit 240, the exposure unit 241, the developing unit 242, the transfer unit 244, and the cleaning unit 246 are disposed around the cylindrical photoconductor 10. The photoconductor 10 is rotated at a predetermined cycle around its central axis. After charging the photosensitive member 243 by the charging unit 240, the exposure unit 241 forms document image data on the surface of the photosensitive member 243 as a latent image, the developing unit 242 attaches toner to the latent image on the photosensitive member, and the transfer unit 244. By transferring the toner onto the paper, original image data is formed on the paper as an actual image. An image is formed for each color component in the CMYK color space, and color printing is realized by superimposing the image of each color component on the same sheet. The sheet on which the toner is transferred is sent to the fixing unit 245, and the toner is fixed on the sheet by heating. In the paper discharge unit 205, the paper printed by the printing unit 204 is discharged to the paper discharge stocker 250.

  As shown in FIG. 10, the cleaning unit 246 is removed from the neutralization unit 12 that neutralizes the photoconductor 10, the cleaning brush 14 that mechanically removes toner remaining on the photoconductor 10, the cleaning blade 16, and the photoconductor 10. And a toner collecting container 18 for collecting the toner. The neutralization unit 12 neutralizes the potential of the surface of the photoconductor 10 so that the toner electrostatically attached to the surface of the photoconductor 10 is easily removed. The cleaning brush 14 and the cleaning blade 16 mechanically remove the discharged toner from the surface of the photoreceptor 10. The removed toner is collected in the toner collection container 18.

  In this embodiment, the paper means not only general paper but also general objects to be printed including OHP sheets, cardboard, and postcards.

  The inspection apparatus 300 is used in combination with the image forming apparatus 200, and has a function of reading a print result image on a sheet at a later stage than the printing unit 204 of the image forming apparatus 200 and outputting the print result image data to the control apparatus 100 as print result image data. . The inspection apparatus 300 can be configured to include an image reading unit 301 and a data interface 302.

  The image reading unit 301 can include a lamp serving as a light source, a line sensor including a photoelectric conversion element, and an analog / digital converter. A printed image is read from the entire sheet by illuminating the sheet conveyed by the conveyance belt 232 with a lamp and photoelectrically converting light reflected from the sheet by a line sensor. The read print result image is sent to an analog / digital converter and converted into a digital signal. The digitized print result image data is sent to the control device 100 via the network using the data interface 302.

  As shown in FIG. 3, the control device 100 includes a control unit 20, a storage unit 22, a data interface 24, and a user interface 26. The control unit 20 corresponds to a CPU of the computer, and controls the control device 100 in an integrated manner by executing a print control program. The storage unit 22 includes a semiconductor memory, and stores and saves electronic information such as programs processed by the control unit 20, image data, and correction conditions. When a large amount of data is stored and held, it is also preferable to use a mass storage device such as a hard disk device, a magnetic tape device, a magnetic disk device, an optical disk device, or a magneto-optical disk device as an auxiliary storage device. The data interface 24 is connected to the data interface 206 in the image forming apparatus 200 and the data interface 302 in the inspection apparatus 300 via a network so as to be able to transmit information, and is used to transmit / receive specific information, document image data, or print result image data. It is done. The user interface 26 includes an input / output device such as a touch panel, and is used for receiving an instruction from the user to the control device 100 and presenting information to the user from the control device 100.

  The control device 100 has a function of detecting a defect from print result image data received from the inspection device 300 and controlling the image forming device 200 based on the detection result.

  FIG. 4 shows a flowchart of a print control method performed by the control apparatus 100. Each step of the printing control method is converted into a printing control program that can be processed by a computer, and stored and held in the storage unit 22. The control unit 20 reads the print control program held in the storage unit 22 and sequentially executes each process. In the present invention, each step is not an essential requirement, and a combination can be appropriately selected and executed.

  In step S <b> 10, specific information is transmitted from the control apparatus 100 to the image forming apparatus 200. The control unit 20 selects specific information for specifying original image data to be printed based on a user command from the user interface 26 or the like. The specific information is sent to the image forming apparatus 200 via the network using the data interface 24. In the control device 100, this step functions as an image data designation unit.

  In the image forming apparatus 200, this specific information is received using the data interface 206, and an image is formed on the paper based on the original image data to be printed. The inspection apparatus 300 reads the print result image printed from the paper and transmits it to the control apparatus 100 using the data interface 302.

  In step S <b> 12, print result image data is received from the inspection apparatus 300. The control unit 20 receives print result image data via the network using the data interface 24. The received print result image data is temporarily stored and held in the storage unit 22. In the control device 100, this step functions as an image data acquisition unit.

In step S14, a high-density image region is extracted from the print result image data. The control unit 20 reads the print result image data received in step S12 from the storage unit 22, and extracts the position and shape of an image area having a density equal to or higher than a predetermined density threshold C. In the control device 100, this process functions as a high concentration area extracting means. For example, the density threshold C determined as high density is set to 80% or more of the maximum density C _{max that} can be formed by the image forming apparatus 200, and a region having a density equal to or higher than the density threshold C is set as the high density region 30. To detect.

  Further, as shown in FIG. 5, when a rectangular high density region 30 exists in the print result image data, each pixel constituting the print result image data is passed through a differential filter, and the density is steep enough to exceed a predetermined threshold value. From the edge position where the density is increased to the edge position where the density is sharply decreased to a predetermined threshold value or more may be detected as the high density area 30.

  In the case where the image forming apparatus 200 is a color printing machine, it is preferable to detect, as the high density area 30, an area where the color component for which a cleaning defect is to be detected has a high density. For example, when it is desired to detect a defect of the cleaning unit 246 with respect to cyan (C), an area where the density of cyan (C) is high is detected as the high density area 30 from the print result image data.

  Here, processing in the image forming apparatus 200 when the high density region 30 is image-formed will be described. For example, as shown in FIG. 6A, a latent image 32 corresponding to the high density region included in the document image data is formed on the surface of the photoreceptor 10. A high density toner 34 is attached to the latent image 32 in the developing unit 242. Then, as shown in FIG. 6B, the toner 34 is transferred to the paper 40 in the transfer unit 244. At that time, a large amount of the toner 34 that has not been completely transferred remains on the surface of the photoreceptor 10 in the region 36 corresponding to the high density region. Subsequently, the region 36 reaches the cleaning unit 246, and the remaining toner 34 is cleaned. If the cleaning unit 246 has a defect such as wear of the cleaning brush 14 or the cleaning blade 16, a large amount of toner 34 that cannot be removed remains in the region 36 of the photoconductor 10 even after cleaning. As a result, as shown in FIG. 6C, the toner remaining in the region 36 of the photoconductor 10 at the timing when the high density region 30 is transferred by the integral multiple of the rotation period T of the photoconductor 10 after being transferred to the paper 40. 34 is transferred to the paper 40 and causes defects on the paper.

  For example, when the rectangular high density area 30 exists in the print result image data as shown in FIG. 5, the photosensitive member 10 is rotated from the position where the high density area 30 is printed as shown in FIG. In the areas 42a, 42b,... Printed at a timing rotated by an integral multiple of the period T, defects due to cleaning defects occur.

  In step S16, it is determined whether or not the high density region 30 has been detected. If the high density region 30 can be detected in step S14, the process proceeds to step S18. If the high density region 30 cannot be detected, the process returns to step S10 to perform the next printing. In the control device 100, this process functions as a high-concentration area determination unit.

  In step S18, a region for detecting a defect is determined. In the control device 100, this step functions as a detection target region determination unit. The controller 20 performs defect detection on the image area regions 42a, 42b,... Formed at the timing when the photoconductor 10 is rotated by an integral multiple of the rotation period T from the position of the high density area 30 extracted in step S14. Determined as the target area.

  For example, as shown in FIG. 7, when the rectangular high density region 30 is extracted in step S14, if the photoconductor 10 has the peripheral length L, the peripheral length nL (in the sub scanning direction from the high density region 30). The area printed after n is an integer equal to or greater than 1 is set as the defect detection target area 32.

  Here, it is possible to detect the area 42a where printing has been performed at the timing when the photoconductor 10 has made one full rotation from the position where the high density area 30 is printed, and to determine whether or not there is a defect in the area 42a. preferable. This is because defects that occur each time the rotational speed of the photoconductor 10 increases after printing the high density region 30 are weakened, and it becomes difficult to detect defects caused by poor cleaning.

  In step S20, it is determined whether or not a defect exists in the defect detection target area. In the control apparatus 100, this process functions as a defect detection unit and a defect determination unit. The control unit 20 investigates whether or not a defect has occurred in the defect detection target areas 42a, 42b... Determined in step S18. For example, the control unit 20 reads the print result image data received in step S12 from the storage unit 22, calculates the difference between the document image data to be printed and the print result image data, and detects the defect from the difference data. A defect included in the target area 32 is detected. However, the defect detection method in the present embodiment is not limited to this, and other existing image processing methods may be used. If there is a defect, the process proceeds to step S22. If no defect exists, the process returns to step S10.

  When defects exist in the defect detection target areas 42a, 42b,..., It can be said that the defect is very likely caused by the toner remaining on the photosensitive member 10 due to poor cleaning. On the other hand, if no defect exists, there is a high possibility that there is no defective cleaning.

  It is also preferable to determine that the defect is caused by a cleaning defect only when a defect exists in the plurality of image areas 42a, 42b,. By confirming defects in a plurality of areas synchronized with the printing cycle of the printing unit, it is possible to more accurately identify that the defect has occurred due to defective cleaning.

  Defects resulting from poor cleaning often appear as dirt scattered in the defect detection target areas 42a, 42b,. Therefore, it is possible to determine whether or not the defect is highly likely due to defective cleaning by examining the generation cycle of scattered toner stains by frequency conversion or the like.

  Further, when a part of the cleaning brush 14 or the cleaning blade 16 is worn or when the photoconductor 10 is damaged, defective toner remains on the surface of the photoconductor 10 in a streak shape. Such a cleaning defect appears as a streak defect extending in the sub-scanning direction of printing in the defect detection target areas 42a, 42b. Therefore, if there are streak-like defects extending in the sub-scanning direction in the defect detection target areas 42a, 42b,..., It can be determined that there is a high possibility that the defect is caused by defective cleaning.

  When the image forming apparatus 200 is a color printer and the high density region 30 is detected for a color component for which a cleaning defect is desired to be detected in step S14, a defect in the cleaning unit 246 for that color component can be detected.

  In step S22, a control process according to the defect detection result performed in step S20 is performed. In the control device 100, this process functions as a defect handling processing means. For example, if there is a defect due to defective cleaning in step S24, a screen prompting the user to replace or repair the cleaning unit 246 is displayed on the display device of the user interface 26. It is also preferable to send a stop signal for stopping the image forming process to the image forming apparatus 200.

  As described above, the area where the image is formed with high density is obtained from the print result image data, and the stain at the position where the transfer is performed at the timing when the photosensitive member 10 is rotated by an integral multiple of the rotation period from the position of the high density area. By confirming, it is possible to reliably detect defective cleaning. That is, by detecting the occurrence of a defect in a region synchronized with the rotation cycle of the photoconductor 10, it is possible to accurately detect a cleaning failure of the photoconductor 10.

  In addition, it is possible to detect a defect caused by a cleaning defect from a printing result formed with an image based on document image data that is flowed in a normal image forming process. Therefore, it is not necessary to prepare document image data including a test pattern suitable for detecting a defect caused by a cleaning defect. Further, it is not necessary to interrupt the image formation of the original image data including the test pattern during the normal image forming process in order to detect the defect due to the cleaning defect. Therefore, the image forming process can be performed quickly.

  In this embodiment, the electrophotographic image forming apparatus 200 having the drum-shaped photoconductor 10 has been described. However, the scope of application of the present invention is not limited to this. An image forming apparatus having a component that supplies a coloring material such as toner or ink to a sheet at a predetermined period and a cleaning unit that cleans the component can be targeted. That is, an image that requires a large amount of cleaning, for example, an image area that consumes a large amount of ink in an ink jet printer, is detected from the print result image data, and an integral multiple of the period in which the printing unit supplies the coloring material from the position of the image area By determining whether or not there is a defect in a region where an image is formed later, it is possible to determine whether or not a defect has occurred in cleaning.

  For example, the image forming apparatus may be an electrophotographic system using a rotating intermediate transfer belt. In this case, a latent image is formed on the surface of the intermediate transfer body belt, the latent image is developed with a high density toner, and the high density area is transferred from the intermediate transfer body belt to the sheet. After the high density area is cleaned by the cleaning unit, the defect is applied to the area where the transfer is performed at the position (timing) where the intermediate transfer belt is rotated by an integral multiple of the rotation period from the position (timing) where the high density area is transferred. By determining whether or not there is a defect, it is possible to check whether or not a defect has occurred in the cleaning unit. At this time, the sheet on which the test pattern is transferred may be different from the sheet having a defect detection area.

  In the present embodiment, a high density region is detected from print result image data obtained by reading a print result image printed on paper, and a defect detection target region corresponding to the position is determined. However, a high density area may be detected from the original image data, and the defect detection area may be obtained from the print result image data read from the print result image based on the original image data. In this case, a region where an image is formed after an integral multiple of the period in which the printing means supplies the coloring material from the position of the high density region may be determined as the defect detection target region.

<Modification 1>
In the above embodiment, the density threshold C is fixed. Therefore, if the print result image data does not include the high density region 30 having the density threshold value C or higher, the process proceeds to the next print process without checking for the occurrence of a defect. However, when a situation in which the high density region does not exist in the print result image data continues, there arises a problem that it becomes impossible to detect whether or not a defect due to a cleaning defect occurs.

  Therefore, in this modified example, it is assumed that even when document image data including only an image having a low density is formed, a defect caused by a cleaning defect can be detected more reliably.

  FIG. 8 shows a flowchart in Modification 1 of the above embodiment. Steps for performing the same processing as in the above embodiment are denoted by the same reference numerals as those in the flowchart shown in FIG. 4, and will be described briefly below.

  In step S8, the counter N is initialized. In the control device 100, this process functions as an initial setting means. Counter N is set to zero. The counter N is used to count the number of sheets of paper on which a high density area equal to or higher than the density threshold C cannot be extracted in step S14.

  In steps S10 and S12, document image data is specified in the same manner as in the above-described embodiment, image formation is performed on a sheet in the image forming apparatus 200 based on the document image data, and a print result image printed on the sheet is used. The read printing result image data is acquired by the control device 100.

In step S13, a density threshold C is set based on the value of the counter N. In the control device 100, this step functions as a density threshold setting means. A threshold table in which the value of the counter N and the density threshold C are associated with each other is registered in the storage unit 22 in advance, and the density threshold C is set with reference to the threshold table. At this time, it is preferable to set the threshold value table so that the corresponding density threshold value C decreases as the value of the counter N increases. For example, in the example of the threshold table shown in FIG. 9, when the value of the counter N is 0 or more and less than 20, the density threshold C is set to 80% of the maximum density C _{max that} can be formed by the image forming apparatus 200. If the value of the counter N is 20 or more and less than 50, the density threshold C is set to 70% of the maximum density C _max . Similarly, when the value of the counter N is 50 or more and less than 100, 100 or less and less than 200, or 200 or more, the density threshold C is set to 60%, 50%, and 40% of the maximum density C _max , respectively. .

  In step S14, a high-density image region is extracted from the print result image data. At this time, an image area having a density equal to or higher than the density threshold C set in step S13 is extracted from the print result image data.

  In step S16, it is determined whether or not the high density region 30 has been detected. If the high density region 30 can be detected in step S14, the process proceeds to step S18. If the high density region 30 cannot be detected, the process proceeds to step S17.

  In step S17, the value of counter N is incremented by 1, and the process returns to step S10. In the control device 100, this process functions as history information setting means. The control unit 10 increases the value of the counter N when an area having a density equal to or higher than the current density threshold C cannot be detected in step S14. As a result, the density threshold C is set lower as the number of times that the area equal to or higher than the density threshold C cannot be detected in step S14, that is, the value of the counter N increases.

  On the other hand, if a region equal to or higher than the density threshold C can be detected in step S14, a defect detection target region is obtained in step S18, and it is determined in step S20 whether or not a defect exists in the defect detection target region. . If there is no defect, the process proceeds to step S21. If there is a defect, the process proceeds to step S22.

  In step S21, the value of the counter N is reset to 0, and the process returns to step S10. In the control device 100, this process functions as history information initialization means. As a result, even if the density threshold C is set low in step S14, the defect is detected by the density threshold C, and if there is no defect, the density threshold C is returned to the highest density threshold C again. It becomes. On the other hand, when a defect exists, a control process according to the defect detection result is performed.

  As described above, according to the present modification, when document image data including only an image having a low density continues, the density threshold C serving as a reference for detection of the high density area is gradually set low to perform cleaning. Defects resulting from defects can be detected more reliably.

1 is a diagram showing a configuration of an image forming system in an embodiment of the present invention. It is a figure which shows the database with which the specific information which specifies original image data was registered. It is a block diagram which shows the structure of the control apparatus in embodiment of this invention. It is a figure which shows the flowchart of the printing control method in embodiment of this invention. It is a figure which shows the example of the high concentration area | region detected in embodiment of this invention. It is a figure explaining the mode of generation | occurrence | production of the defect by the high concentration area | region in embodiment of this invention. It is a figure explaining generation | occurrence | production of the defect by the defect of the cleaning in embodiment of this invention. It is a figure which shows the flowchart of the printing control method in the modification with respect to embodiment of this invention. It is a figure which shows the registration example of the threshold value table in the modification with respect to embodiment of this invention. FIG. 2 is a diagram illustrating a configuration of a cleaning unit in an electrophotographic image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Photoconductor, 12 Static elimination part, 14 Cleaning brush, 16 Cleaning blade, 18 Toner collection container, 20 Control part, 22 Storage part, 24 Data interface, 26 User interface, 30 High density area, 32 Latent image, 34 Toner, 36 High density toner area, 40 sheets, 42a, 42b Image area, 100 control device, 200 image forming apparatus, 201 control unit, 202 original image data acquisition means, 203 paper feed means, 204 printing means, 205 paper discharge means, 206 Data interface, 222 platen, 224 scanner, 230 paper stocker, 232 transport belt, 232 paper transport belt, 240 charging section, 241 exposure section, 242 development section, 243 photoconductor, 244 transfer section, 245 fixing section, 246 cleaning , 250 sheet discharge stocker, 260 data interface, 300 inspection device, 301 image reading means, 302 data interface.

Claims (18)

A control device for an image forming apparatus,
Image data acquisition means for acquiring document image data to be subjected to image formation in the image forming apparatus, or print result image data read from a print result formed on a paper in the image forming apparatus;
A detection target region determination unit that determines a defect detection target region that is a target for detecting a defect from the print result image data acquired by the image data acquisition unit;
Defect detection means for detecting a defect from the defect detection target area determined by the detection target area determination means,
A control apparatus characterized in that a reference for determining the defect detection target region can be changed in the detection target region determination means. The control device according to claim 1,
In the case where the image forming apparatus is an apparatus that includes a component that supplies a coloring material to a sheet at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component.
The control device according to claim 1, wherein the detection target region determination means determines the defect detection target region based on the cycle. The control device according to claim 1 or 2,
High density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the print result image data acquired in the image data acquisition means;
The control device, wherein the detection target region determining means determines the defect detection target region based on the position of the high concentration region extracted by the high concentration region extraction means. The control device according to claim 1 or 2,
High density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the document image data acquired by the image data acquisition means;
The control device, wherein the detection target region determination means determines the defect detection target region based on the position of the high concentration region extracted by the high concentration region extraction means. The control device according to claim 3 or 4,
The control device characterized in that the high concentration region determining means can change the concentration threshold. The control device according to claim 5,
The control apparatus according to claim 1, wherein the high concentration region determining means changes the concentration threshold based on a past extraction history of the high concentration region. An image forming apparatus control method comprising:
An image data acquisition step of acquiring original image data to be image-formed in the image forming apparatus, or print result image data read from a print result formed on the paper in the image forming apparatus;
A detection target region determination step for determining a defect detection target region that is a target for detecting a defect from the print result image data acquired in the image data acquisition step;
A defect detection step of detecting a defect from the defect detection target region determined by the detection target region determination means,
A control method characterized in that it is possible to change a reference for determining the defect detection target region in the detection target region determination step. The control method according to claim 7,
In the case where the image forming apparatus is an apparatus that includes a component that supplies a coloring material to a sheet at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component.
In the detection target region determination step, the defect detection target region is determined based on the cycle. The control method according to claim 7 or 8,
A high density region extraction step of extracting a high density region having a density equal to or higher than a predetermined density threshold from the print result image data acquired in the image data acquisition step;
In the detection target region determination step, the defect detection target region is determined based on the position of the high concentration region extracted in the high concentration region extraction step. The control method according to claim 7 or 8,
A high density region extraction step of extracting a high density region having a density equal to or higher than a predetermined density threshold from the document image data acquired in the image data acquisition step;
In the detection target region determination step, the defect detection target region is determined based on the position of the high concentration region extracted in the high concentration region extraction step. The control method according to claim 9 or 10,
The control method characterized in that, in the high concentration region determination step, the concentration threshold value can be changed. The control method according to claim 11, wherein
In the high density region determination step, the density threshold value is changed based on a past extraction history of the high density region. A control program for an image forming apparatus,
Computer
Image data acquisition means for acquiring document image data to be subjected to image formation in the image forming apparatus, or print result image data read from a print result formed on a paper in the image forming apparatus;
A means for determining a defect detection target area as a target for detecting a defect from the print result image data acquired by the image data acquisition means, wherein a reference for determining the defect detection target area is changed; Possible detection target area determination means;
Defect detection means for detecting a defect from the defect detection target area determined by the detection target area determination means;
A control program that functions as a control device including The control program according to claim 13,
In the case where the image forming apparatus is an apparatus that includes a component that supplies a coloring material to a sheet at a predetermined cycle and a cleaning unit that removes the coloring material remaining in the component.
The control program according to claim 1, wherein the detection target region determining means determines the defect detection target region based on the cycle. The control program according to claim 13 or 14,
The computer,
High density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the print result image data acquired in the image data acquisition means;
A control program that causes the detection target region determination unit to function as a control device that determines the defect detection target region based on the position of the high concentration region extracted by the high concentration region extraction unit. The control program according to claim 13 or 14,
The computer,
High density area extraction means for extracting a high density area having a density equal to or higher than a predetermined density threshold from the document image data acquired by the image data acquisition means;
A control program that causes the detection target region determination unit to function as a control device that determines the defect detection target region based on the position of the high concentration region extracted by the high concentration region extraction unit. The control program according to claim 15 or 16,
The control program, characterized in that the high concentration area determination means can change the concentration threshold. The control program according to claim 17,
The control program characterized in that the high concentration area determination means changes the density threshold based on a past extraction history of the high density area.

Images