Image forming system

Abstract

To reduce the time and effort for determining the state of an object.SOLUTION: An image forming system 1 comprises: an object that is one element constituting an image forming unit 13 forming an image on a recording medium (sheet), and moves in a main scanning direction during the operation related to formation of an image based on a print job; an acquisition unit (control unit 11) that acquires position information of the object in the main scanning direction during the operation; a reading unit (output image reading unit 14) that reads the image on the recording medium formed through the operation; and a determination unit (control unit 11) that determines the state of the object on the basis of the position information acquired by the acquisition unit and read image data obtained by the reading unit reading the image.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image forming system. [Background technology]

[0002] Conventionally, there is known an image forming apparatus that forms an image on a sheet of paper by an electrophotographic method. The image forming apparatus develops an electrostatic latent image formed on a photoconductor with toner. Next, the image forming apparatus transfers the toner image to the sheet of paper in a transfer section. After that, the image forming apparatus fixes the toner image in a fixing section. If the photoconductor, the transfer unit, or the fixing unit is scratched or has foreign matter attached thereto, this can cause image defects such as streaky density unevenness along the sub-scanning direction of the image to be formed.

[0003] In this regard, Patent Document 1 discloses an image forming apparatus that prevents the occurrence of scratches in the fixing section caused by the edge of a sheet when the sheet passes by by swinging the fixing section in the main scanning direction.

[0004] Patent Document 2 discloses the following image forming apparatus. Specifically, the apparatus moves each of the units constituting the apparatus in the main scanning direction, and identifies the unit that is the cause of density unevenness from the amount of change in position of the density unevenness before and after the movement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-29850 A [Patent Document 2] JP 2014-215591 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the invention described in Patent Document 2, the unit causing the density unevenness is identified in an abnormality location identification mode that is different from the normal image formation mode in which the image formation of the print job is performed. In other words, in the invention described in Patent Document 2, the state of the unit is judged in the abnormality location identification mode. Therefore, in order to judge the state of the target object, which is the unit, the abnormality location identification mode must be executed in addition to the normal image formation mode, which causes a problem of taking time and effort.

[0007] An object of the present invention is to provide an image forming system that can reduce the time and effort required to determine the state of an object. [Means for solving the problem]

[0008] In order to solve the above problem, the image forming system according to claim 1 comprises: an object which is an element constituting an image forming unit that forms an image on a recording medium and moves in a main scanning direction during an operation related to the formation of an image based on a print job; an acquisition unit that acquires position information of the object in a main scanning direction during the operation; a reading unit that reads an image formed on the recording medium by the operation; a determination unit that determines a state of the object based on the position information acquired by the acquisition unit and the read image data read by the reading unit; Equipped with.

[0009] The invention described in claim 2 is the image forming system described in claim 1, The determination unit determines a state of the object based on a movement amount in a main scanning direction of the object during the operation and a movement amount in the main scanning direction of a point of interest in the read image during the operation.

[0010] The invention described in claim 3 is the image forming system described in claim 2, The determination unit determines a state of the object based on a moving direction in a main scanning direction of the object during the operation and a moving direction in the main scanning direction of a point of interest in the read image during the operation.

[0011] The invention described in claim 4 is the image forming system described in claim 2 or 3, A plurality of said objects; A control unit that changes the direction or amount of movement of each object in the main scanning direction; Equipped with.

[0012] The invention described in claim 5 is the image forming system described in claim 4, The control unit differs the movement direction or movement amount of the two or more objects when a correlation coefficient between the movement direction and the movement amount in the main scanning direction of the two or more objects during the operation and the movement direction and movement amount in the main scanning direction of a point of interest in the read image during the operation is a predetermined value or greater.

[0013] The invention described in claim 6 is the image forming system described in claim 5, The control unit controls the moving speeds of the two or more objects to make the moving amounts different from each other.

[0014] The invention described in claim 7 is the image forming system described in claim 5, The control unit determines an object, of the two or more objects, for which the movement direction or the movement amount is to be changed, based on a movable distance in each of the movement directions of the two or more objects.

[0015] The invention described in claim 8 is the image forming system described in claim 2, The judgment unit judges that the object is defective when a correlation coefficient between the amount of movement in the main scanning direction of the object during the operation and the amount of movement in the main scanning direction of a point of interest in the read image during the operation is greater than or equal to a predetermined value.

[0016] The invention described in claim 9 is the image forming system described in claim 8, The determination unit determines that the object is defective when a direction of movement in a main scanning direction of the object during the operation coincides with a direction of movement in the main scanning direction of a point of interest in the read image during the operation.

[0017] The invention described in claim 10 is the image forming system described in claim 9, The device further includes a notification unit that notifies the user that the object has been determined to be defective by the determination unit.

[0018] The invention described in claim 11 is the image forming system described in claim 10, The notification unit prompts replacement of the object determined to be defective.

[0019] The invention described in claim 12 is the image forming system described in claim 1, The target object is at least one of a fixing unit, a fixing member, a secondary transfer unit, a secondary transfer member, an intermediate transfer unit, an intermediate transfer member, and a photoconductor.

[0020] The invention described in claim 13 is the image forming system described in claim 1, The object is moved in the main scanning direction by a swinging or steering motion.

[0021] The invention described in claim 14 is the image forming system described in claim 1, The portion of interest in the read image is a streak-like image defect that extends in the transport direction of the recording medium.

[0022] The invention described in claim 15 is the image forming system described in claim 1, The image forming section and the reading section are integrally configured.

[0023] The invention described in claim 16 is the image forming system described in claim 1, The image forming unit and the reading unit are configured to be separate and capable of communicating with each other. Effect of the Invention

[0024] According to the present invention, it is possible to reduce the time and effort required to determine the state of an object. [Brief description of the drawings]

[0025] [Figure 1] 1 is a front view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a functional block diagram showing a control structure of the image forming apparatus according to the embodiment. [Diagram 3] 13 is a flowchart showing the flow of a determination process. [Figure 4] 11A and 11B are diagrams illustrating an example of an image difference between an input image and a read image. [Figure 5A] 11A and 11B are diagrams illustrating an example of a density difference between an input image and a read image. [Figure 5B] FIG. 11 is a diagram illustrating an example of a density difference after correction. [Figure 6] 13A and 13B are diagrams illustrating an example of position information of each object in the main scanning direction and position information of each image difference in the main scanning direction. [Figure 7] 13 is a diagram showing an example of a relationship between time and position information of an object in the main scanning direction and position information of each image difference in the main scanning direction; FIG. [Figure 8] 11 is a diagram showing an example of a relationship between position information of an object in the main scanning direction and position information of an image defect in the main scanning direction; FIG. [Figure 9] 13 is a flowchart showing the flow of a determination process according to a modified example. [Figure 10] 13A and 13B are diagrams illustrating an example of a relationship between position information of an object in the main scanning direction and position information of an image defect in the main scanning direction in a modified example. [Figure 11] 11A and 11B are diagrams showing an example of positions to which an object can be moved in a swing or steering operation in the main scanning direction. [Figure 12]11A and 11B are diagrams showing an example of positions to which an object can be moved in a swing or steering operation in the main scanning direction. [Figure 13] 13A and 13B are diagrams illustrating an example of a relationship between position information of an object in the main scanning direction and position information of an image defect in the main scanning direction in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the present embodiment will be described in detail with reference to the drawings, however, the scope of the invention is not limited to the illustrated examples.

[0027] (1. Configuration of Image Forming Apparatus) Fig. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus 10 according to the present embodiment. Fig. 2 is a block diagram showing a functional configuration of the image forming apparatus 10 according to the present embodiment. The image forming system 1 according to the present embodiment includes an image forming apparatus 10.

[0028] The image forming device 10 includes a control unit 11, an operation display unit 12, an image forming unit 13, an output image reading unit 14, a communication unit 15, a paper feeding unit 16, a conveying unit 17, a document reading unit 18, a memory unit 19, and a drive unit 20.

[0029] The control unit 11 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The CPU reads out a program corresponding to the processing contents from the ROM and loads it into the RAM. Next, the CPU cooperates with the loaded program to centrally control the operation of each block of the image forming apparatus 10.

[0030] The operation display unit 12 includes a display unit 12a and an operation unit 12b. The display unit 12 a includes an LCD (Liquid Crystal Display) or the like, and displays various screens according to instructions of a display signal input from the control unit 11 . The operation unit 12b includes various function keys and a touch panel formed to cover the display screen of the display unit 12a, and receives various operations from the user.

[0031] The image forming unit 13 forms an image on the paper being transported by the transport unit 17 by electrophotography. The image forming section 13 includes photoconductor drums 131Y, 131M, 131C, and 131K, an intermediate transfer unit 132, a secondary transfer unit 133, a fixing unit 134, a reversing path 135, a registration section 136, and the like.

[0032] The photoconductor drums 131Y, 131M, 131C, and 131K are photoconductors corresponding to the colors yellow (Y), magenta (M), cyan (C), and black (K), respectively. The photoconductor is held within the image forming apparatus 10 so that it can move from a predetermined position in the main scanning direction of the image. The main scanning direction is a direction perpendicular to the paper transport direction. The image forming unit 13 includes a stepping motor (not shown) for moving the photoconductor in the main scanning direction.

[0033] The image forming unit 13 uniformly charges the photoconductor drum 131Y, and then scans and exposes the photoconductor drum 131Y with a laser beam based on image data of yellow color to form an electrostatic latent image. Next, the image forming unit 13 causes yellow toner to adhere to the electrostatic latent image on the photoconductor drum 131Y, thereby developing the image. The photoconductor drums 131M, 131C, and 131K are similar to the photoconductor drum 131Y except for the colors they handle, and therefore descriptions thereof will be omitted.

[0034] In the image forming section 13, the toner images of the respective colors formed on the photoconductor drums 131Y, 131M, 131C, and 131K are successively transferred by the intermediate transfer unit 132 (primary transfer). The intermediate transfer unit 132 includes an intermediate transfer belt 132a (intermediate transfer member) formed in an endless shape. The intermediate transfer belt 132a is rotated by a drive motor (not shown) in a direction opposite to the direction of rotation of the photoconductor drums 131Y, 131M, 131C, and 131K. The intermediate transfer unit 132 includes a primary transfer section (not shown) at a position on the intermediate transfer belt 132a facing the photoconductor drums 131Y, 131M, 131C, and 131K. The image forming section 13 transfers the toner images formed on the photoconductor drums 131Y, 131M, 131C, and 131K to the intermediate transfer belt 132a by applying a polarity opposite to that of the toner to the intermediate transfer belt 132a. That is, the image forming section 13 forms a color toner image on the intermediate transfer belt 132a by superimposing four color toner images. The intermediate transfer unit 132 and the intermediate transfer belt 132a are held within the image forming apparatus 10 so as to be movable in the main scanning direction of the image from a predetermined position. The image forming section 13 includes an intermediate transfer unit 132, or a stepping motor (not shown) for moving an intermediate transfer belt 132a in the main scanning direction.

[0035] In the image forming section 13, the color toner image on the intermediate transfer belt 132a is transferred onto a sheet of paper at once by the secondary transfer unit 133 (secondary transfer). The secondary transfer unit 133 includes a secondary transfer roller 133a (secondary transfer member) that presses the paper conveyed from the paper feed section 16 against the intermediate transfer belt 132a. The secondary transfer unit 133 and the secondary transfer roller 133a are held within the image forming apparatus 10 so as to be movable in the main scanning direction of the image from a predetermined position. The image forming section 13 includes a stepping motor (not shown) for moving the secondary transfer unit 133 or the secondary transfer roller 133a in the main scanning direction.

[0036] The fixing unit 134 applies heat and pressure to the paper onto which the toner image has been transferred in a fixing nip, thereby fixing the toner image to the paper. The fixing unit 134 includes a heating roller 134a, an upper pressure roller 134b, a fixing belt 134c (fixing member), and a lower pressure roller 134d.

[0037] The heating roller 134a has an internal heating source. The fixing belt 134c is an endless belt that is stretched between the heating roller 134a and the upper pressure roller 134b. The upper pressure roller 134b and the lower pressure roller 134d are rotated by the drive of a motor (not shown). The heating roller 134a and the fixing belt 134c rotate following the rotation of the upper pressure roller 134b. The upper pressure roller 134b and the lower pressure roller 134d are in pressure contact with each other via the fixing belt 134c, thereby forming a fixing nip that sandwiches and transports the paper. The fixing unit 134 passes the paper through a fixing nip formed by the fixing belt 134c heated by a heat source and the lower pressure roller 134d. The fixing unit 134 applies heat and pressure to the paper to fix the toner image on the paper. The fixing unit 134 and the fixing belt 134c are held within the image forming apparatus 10 so as to be movable in the main scanning direction of the image from a predetermined position. The image forming section 13 includes a stepping motor (not shown) for moving the fixing unit 134 or the fixing belt 134c in the main scanning direction.

[0038] Hereinafter, the photoconductor, the intermediate transfer unit 132, the intermediate transfer member, the secondary transfer unit 133, the secondary transfer member, the fixing unit 134, and the fixing member will also be referred to as objects. The target object is one element constituting image forming unit 13 that forms an image on paper (recording medium), and moves in the main scanning direction during an operation related to the formation of an image based on a print job (image forming operation).

[0039] In the case of single-sided printing in which an image is formed on one side of a sheet in the image forming apparatus 10, the control unit 11 conveys the sheet from the fixing unit 134 to the output image reading unit 14. On the other hand, in the case of double-sided printing in which images are formed on both sides of the paper, the control unit 11 transports the paper from the fixing unit 134 to a reversing path 135 and reverses the paper surface. Next, the control unit 11 feeds the paper again upstream of the registration unit 136 in the paper transport direction.

[0040] The registration unit 136 includes registration rollers and transports the paper to the transfer unit. The registration unit 136 corrects the inclination of the paper conveyed from the paper feed unit 16 and adjusts the timing of conveying the paper.

[0041] The output image reading unit 14 is provided downstream of the image forming unit 13 on the paper transport path. The output image reading unit 14 reads the printout on which the image is formed on the paper by the image forming unit 13, and generates read image data. The output image reading unit 14 outputs the read result (read image data) to the control unit 11. The output image reading unit 14 is a color sensor that receives light emitted from a light source and reflected by the surface of the paper with a light receiving element and outputs red, green, or blue signals according to the intensity of the light. The output image reading unit 14 includes, for example, a line sensor in which multiple light receiving elements are arranged at predetermined intervals in the paper width direction perpendicular to the paper transport direction.

[0042] The communication unit 15 transmits and receives data to and from an external device such as a PC (Personal Computer) connected via a communication network such as a LAN (Local Area Network). The communication unit 15 receives, for example, a job including image data for printing from the external device.

[0043] The paper feed unit 16 includes a paper feed tray T1, and feeds paper from the paper feed tray T1 to the image forming unit 13. Each paper feed tray T1 stores paper of a predetermined paper type, size, etc.

[0044] The transport unit 17 is a mechanism for transporting paper. The transport unit 17 includes a plurality of roller pairs, and transports the paper fed from the paper feed unit 16 to the image forming unit 13. The transport unit 17 then transports the paper that has passed through the image forming unit 13 to the output image reading unit 14. The transport unit 17 then ejects the paper that has passed through the output image reading unit 14 onto the paper ejection tray T2.

[0045] The document reading unit 18 includes an automatic document feeder (ADF), a scanner, and the like. The document reading unit 18 reads the image of the document and outputs the image data obtained to the control unit 11 .

[0046] The storage unit 19 includes, for example, a non-volatile semiconductor memory (such as a flash memory), a hard disk drive, and the like. The storage unit 19 stores input document data, various setting information, image data, etc. These data, etc. may be stored in the RAM of the control unit 11.

[0047] The driving unit 20 drives a stepping motor or the like that moves each of the above-mentioned objects in the main scanning direction of the image.

[0048] (2. Vertical stripe image defects) In some cases, vertical stripe-like image defects (uneven density, uneven gloss, etc.) may occur along the sub-scanning direction in an image formed on a sheet by the image forming unit 13 of the image forming apparatus 10. Hereinafter, vertical stripe-like image defects will be referred to as vertical stripes. The above-mentioned defects in the target object may be the cause of the vertical streaks.

[0049] In the image forming unit 13, after the toner image is primarily transferred from the photoconductor to the intermediate transfer belt 132a, the toner remaining on the photoconductor is removed by a cleaning blade (not shown). If the photoconductor is damaged during this process by unintended contact with another member or by a foreign object caught in the cleaning blade, the toner will no longer adhere to the damaged portion of the photoconductor. This causes whitish streaky density unevenness along the sub-scanning direction of the image.

[0050] After the toner image is secondarily transferred from the intermediate transfer belt 132a to the paper, the intermediate transfer unit 132 removes the toner remaining on the intermediate transfer belt 132a with a cleaning blade (not shown). At this time, if the periphery of the intermediate transfer belt 132a is scratched by unintended contact with other members or foreign matter, stripe-like density unevenness will occur along the sub-scanning direction of the image.

[0051] In the secondary transfer unit 133, the toner image is transferred from the intermediate transfer belt 132a to the paper by the secondary transfer roller 133a, and then the toner remaining on the secondary transfer roller 133a is removed by a cleaning blade (not shown). At this time, if foreign matter adheres to the secondary transfer roller 133a, transfer unevenness occurs, and streaky density unevenness occurs along the sub-scanning direction of the image.

[0052] A case will be described in which scratches are caused on the circumference of the fixing belt 134c in the fixing unit 134 due to contact with the edge of a small size paper (e.g., a postcard). In this case, uneven fixing occurs when a large size paper (e.g., A3 wide paper) subsequently passes through the fixing belt 134c. This uneven fixing causes streaky density unevenness in the sub-scanning direction of the image.

[0053] (3. Operation of Image Forming Apparatus) Next, the operation of the image forming apparatus 10 of this embodiment will be described.

[0054] (3-1. Swing and steering movement) The control unit 11 swings or steers the above-mentioned objects during image formation by the image forming unit 13. Specifically, the control unit 11 swings the photoconductor, the entire intermediate transfer unit 132, the entire secondary transfer unit 133, and / or the entire fixing unit 134 during image formation. The control unit 11 steers the intermediate transfer belt 132a, the secondary transfer roller 133a, and / or the fixing belt 134c during image formation.

[0055] The control unit 11 oscillates the photoconductor to reduce damage to the photoconductor when the cleaning blade removes the residual toner on the photoconductor.

[0056] The control unit 11 swings the entire intermediate transfer unit 132 or steers the intermediate transfer belt 132a, thereby reducing damage to the intermediate transfer belt 132a when the residual toner on the intermediate transfer belt 132a is removed by a cleaning blade.

[0057] The control unit 11 swings the entire secondary transfer unit 133 or steers the secondary transfer roller 133a, thereby reducing adhesion of foreign matter to the secondary transfer roller 133a and damage to the secondary transfer roller 133a when removing residual toner on the secondary transfer roller 133a with a cleaning blade.

[0058] The control unit 11 swings the entire fixing unit 134 or steers the fixing belt 134c, thereby reducing damage to the circumference of the fixing belt 134c caused by contact with the edge of a small-sized paper (e.g., a postcard).

[0059] (3-2. Judgment process) Next, a determination process that the image forming apparatus 10 executes while executing a print job will be described. The control unit 11 cooperates with a program stored in the storage unit 19 to execute the determination process. The control unit 11 executes the determination process, for example, when job information of a print job is received from an external device or the like via the communication unit 15. The external device is, for example, a personal computer. FIG. 3 shows a flowchart of the determination process.

[0060] The control unit 11 executes a print job and starts an image forming operation by the image forming unit 13 (step S1). In step S1, the control unit 11 starts a swinging or steering operation for moving each object in the main scanning direction.

[0061] Next, the control unit 11 obtains position information in the main scanning direction of each object during the image forming operation (step S2). That is, the control unit 11 acquires position information of the object in the main scanning direction during the operation related to the formation of the image. The control unit 11 functions as an acquisition unit. In step S2, for example, the control unit 11 acquires position information of the objects from a position detection sensor that detects the position of each object. Alternatively, the control unit 11 may acquire the position information from a movement command signal that moves each object.

[0062] Next, the control unit 11 causes the output image reading unit 14 to read the paper surface on which the image has been formed by the image forming operation of the image forming unit 13, and acquires the read image data (step S3). That is, the output image reading unit 14 reads an image formed on a sheet (recording medium) through an operation related to image formation. The output image reading unit 14 functions as a reading unit.

[0063] Next, the control unit 11 compares the input image of the print job with the read image acquired in step S3. Next, the control unit 11 determines whether there is an image difference between the input image and the read image, that is, whether an image defect has occurred (step S4). The part where there is an image difference between the input image and the read image is a target part in the read image. A case will be described in which the control unit 11 outputs a predetermined image by the image forming operation of the image forming unit 13. In this case, in step S4, the control unit 11 may determine whether or not an image defect has occurred based on the predetermined image and the read image. In this case, a location where there is an image difference between the predetermined image and the read image is a target location in the read image.

[0064] FIG. 4 shows an example of the image difference between the input image and the read image. As shown in FIG. 4, the control unit 11 subtracts the input image from the read image to obtain the image difference between the input image and the read image. In the example shown in FIG. 4, the image differences are streaks, density differences, and positional deviations. The density difference and positional deviation shown in FIG. 4 may include image differences that are not defects.

[0065] The control unit 11 eliminates density differences that are not defects from among the density differences shown in FIG. Specifically, the control unit 11 divides the image area in the scanned image as shown in Fig. 5A, and calculates the average density of the area R1 where the density difference is detected. Next, the control unit 11 subtracts the calculated average density portion from the area R1 where the density difference is detected. FIG. 5B shows an area R2 obtained by subtracting the calculated average density portion from the area R1 in which the density difference was detected. The control unit 11 determines the region R2 as a region where a density difference that is a defect has been detected.

[0066] 4 occurs in the entire read image, the control unit 11 corrects the positional deviation in the read image. Next, the control unit 11 compares the input image with the corrected read image to eliminate positional deviations that are not defects.

[0067] Returning to FIG. 3, if an image defect occurs (step S4; YES), the control unit 11 acquires position information in the main scanning direction of the image difference between the input image and the read image (step S5).

[0068] FIG. 6 shows an example of the position information in the main scanning direction of each object acquired by the control unit 11 in step S2, and the position information in the main scanning direction of each image difference acquired in step S5. 6, a vertical streak A occurs in the scanned image. Ya1... in the position information of the image difference indicates the position information in the main scanning direction of the vertical streak A. Yb1... in the position information of the image difference indicates the position information in the main scanning direction of an image defect other than the vertical streak A.

[0069] Next, the control unit 11 judges whether or not vertical streaks have occurred in the image defect judged in step S4 (step S6). The vertical streaks are stripe-like density unevenness along the sub-scanning direction in the image on the paper. The vertical streaks are either dark stripe-like density unevenness with a higher toner density than the adjacent parts, or whitish stripe-like density unevenness with a lower toner density than the adjacent parts.

[0070] If vertical streaks have occurred (step S6; YES), the control unit 11 identifies the object that is the cause of the vertical streaks. Next, the control unit 11 determines that the identified object is defective (step S7). In step S7, the control unit 11 identifies position information that is correlated with the position information of the vertical stripe in the main scanning direction among the position information of each object in the main scanning direction. Next, the control unit 11 identifies the object showing the identified position information as the object that is the cause of the vertical stripe. For example, when the correlation coefficient between the position information of the object in the main scanning direction and the position information of the vertical stripe in the main scanning direction is 97% or more, the control unit 11 determines that there is a correlation. The threshold value for the correlation coefficient is not limited to this, and may be determined for each type of image difference (image defect).

[0071] 7 shows an example of the relationship between time and position information in the main scanning direction of the object Aa during an image forming operation, and position information in the main scanning direction of each image difference. In the example shown in FIG. 7, the image differences are a vertical streak A and image defects B to E. 8 shows an example of the relationship between position information in the main scanning direction of the object Aa during an image forming operation and position information in the main scanning direction of the vertical streak A. In the example shown in FIGS. A case will be described where the correlation coefficient between the position information of the vertical streak A in the main scanning direction during image forming operation and the position information of the object Aa (fixing unit 134) in the main scanning direction is 97% or more. In this case, the control unit 11 determines that there is a correlation between the position information of the vertical streak A in the main scanning direction and the position information of the object Aa (fixing unit 134) in the main scanning direction. In other words, the control unit 11 identifies the object that is the cause of the vertical streak A as the object Aa (fixing unit 134).

[0072] In step S7, the control unit 11 may not specify an object that is the cause of an image defect for an image difference (image defect) in which the acquired position information in the main scanning direction is less than 3 points. The threshold value for the number of points of the position information of the image difference (image defect) is not limited to this, and may be determined for each type of image difference (image defect).

[0073] In step S7, the control unit 11 determines the state of the object based on the position information of the object in the main scanning direction acquired by the acquisition unit and the read image data read by the output image reading unit 14. The control unit 11 functions as a determination unit. The state of the object is judged as to whether or not the object is defective and is causing a defective image.

[0074] The position information in the main scanning direction of each object during the image forming operation acquired by the control unit 11 in step S2 includes the amount of movement in the main scanning direction of the object during the image forming operation. The position information in the main scanning direction of the image difference between the input image and the read image acquired by the control unit 11 in step S5 includes the amount of movement in the main scanning direction of the image difference between the read image and the input image during the image forming operation. That is, the control unit 11 as a judgment unit judges the state of the object based on the amount of movement in the main scanning direction of the object during an operation related to image formation and the amount of movement in the main scanning direction of a point of interest in the read image during the operation.

[0075] The position information in the main scanning direction of each object during the image forming operation acquired by the control unit 11 in step S2 includes the moving direction in the main scanning direction of the object during the image forming operation. The position information in the main scanning direction of the image difference between the input image and the read image acquired by the control unit 11 in step S5 includes the movement direction in the main scanning direction of the image difference between the read image and the input image during the image forming operation. That is, the control unit 11 as a judgment unit judges the state of the object based on the movement direction in the main scanning direction of the object during an operation related to image formation and the movement direction in the main scanning direction of a point of interest in the read image during the operation.

[0076] The control unit 11, which serves as a judgment unit, judges that the object is defective when the correlation coefficient between the amount of movement in the main scanning direction of the object during the image forming operation and the amount of movement in the main scanning direction of a point of interest in the read image during the image forming operation is a predetermined value (e.g., 97%) or more. Furthermore, the control unit 11, which serves as a judgment unit, judges that the object is defective when the direction of movement in the main scanning direction of the object during the image forming operation and the direction of movement in the main scanning direction of the point of interest in the read image during the image forming operation are the same, i.e., either to the right or to the left.

[0077] Next, the control unit 11 notifies the user by causing the display unit 12a to display a message urging the user to replace the object determined to be defective in step S7 (step S8), and ends this process. If the object determined to be defective is the fixing unit 134, in step S8, the control unit 11 displays the following message: "Please replace the fixing unit as the image is defective due to the fixing unit." That is, the control unit 11 notifies the object that is determined as a defective object as the determining unit. The control unit 11 functions as a notifying unit. The control unit 11 as a notification unit prompts replacement of an object determined to be defective.

[0078] If no vertical stripes have occurred (step S6; NO), that is, if an image defect other than vertical stripes has occurred, the control unit 11 causes the display unit 12a to display that an image defect other than vertical stripes has occurred (step S9), and ends this process.

[0079] If no image defect has occurred (step S4; NO), the control unit 11 determines whether or not to end the image forming operation by the image forming unit 13 (step S10). When the image forming operation is not to be ended (step S10; NO), the control unit 11 shifts the process to step S2. When the image forming operation is to be ended (step S10; YES), the control unit 11 ends this process.

[0080] In the above embodiment, a case will be described in which the control unit 11 rocks a plurality of units during image formation. The plurality of units are two or more of a photoconductor, an intermediate transfer unit 132, a secondary transfer unit 133, and a fixing unit 134. In this case, the control unit 11 varies the movement direction and / or movement amount of each unit in the swing before executing the above-mentioned judgment process. This makes it possible to prevent the position information in the main scanning direction of each unit acquired in step S2 of the above-mentioned judgment process from becoming the same. In other words, it is possible to identify one object that is the cause of the image defect. In other words, the control unit 11 causes each object to move in a different direction or by a different amount in the main scanning direction.

[0081] (4. Modifications) Next, a modified example of the image forming apparatus 10 of the above embodiment will be described. The following mainly describes the differences from the above embodiment. The image forming apparatus 10 of this modified example has the same configuration as the image forming apparatus 10 of the above embodiment. FIG. 9 shows a flowchart of the determination process of this modified example.

[0082] The control unit 11 executes the determination process of this modified example, for example, when the intermediate transfer belt 132a, the secondary transfer roller 133a, and / or the fixing belt 134c are caused to perform a steering operation during image formation.

[0083] In this modification, the control unit 11 performs steps S11 to S16 similar to the determination process steps S1 to S6 of the above embodiment. The case where vertical streaks occur (step S16; YES) will be described. In this case, the control unit 11 judges whether there are two or more pieces of position information in the main scanning direction of the object that are correlated with the position information in the main scanning direction of the vertical streaks. In other words, the control unit 11 judges whether there are two or more objects that are candidates for the cause of the vertical streaks (step S17). In step S17, for example, the control unit 11 determines whether there are two or more pieces of position information in the main scanning direction of the object having a correlation coefficient of 97% or more with the position information of the vertical streak in the main scanning direction.

[0084] FIG. 10 shows a case where there are two pieces of position information in the main scanning direction of an object that are correlated with the position information in the main scanning direction of a vertical streak. 10, the position information Ya1-Ya3 of the vertical streak A in the main scanning direction correlates with the position information Xa1-Xa3 of the fixing unit 134 in the main scanning direction. The position information Ya1-Ya3 of the vertical streak A in the main scanning direction correlates with the position information Xc1-Xc3 of the intermediate transfer belt 132a in the main scanning direction.

[0085] A case where there are two or more objects that are candidates for the cause of vertical stripes (step S17; YES) will be described. In this case, the control unit 11 changes the moving direction or moving speed in the swing or steering operation of any one of the objects that are candidates for the cause of vertical stripes (step S18).

[0086] A case will be described where, in step S18, the control unit 11 changes the moving direction in the swinging or steering operation of one of the objects that are candidates for the cause of the vertical stripes. In step S18, the control unit 11 determines an object whose movement direction is to be changed based on the margin of a movable position in a swing or steering operation of the object, which is a candidate for the cause of the vertical streak.

[0087] Fig. 11 shows the relationship XaT between time and position information in the main scanning direction of the fixing unit 134. Fig. 11 shows the relationship XcT between time and position information in the main scanning direction of the intermediate transfer belt 132a. Fig. 11 shows the relationship YaT between time and position information in the main scanning direction of the vertical streak. The control unit 11 changes the moving direction in the swinging or steering operation of any one of the objects that are candidates for the cause of the vertical stripe at the position F1 in the main scanning direction. A position F2 in the main scanning direction indicates a movement limit position in the steering operation of the intermediate transfer belt 132a. A position F3 in the main scanning direction indicates a movement limit position of the fixing unit 134 in its swinging motion. The maximum amount of movement in the swinging or steering operation of the object is within the paper passing range. The control unit 11 changes the moving direction of the object that is closer to the movement limit position in the swing or steering operation from the position F1. In this case, the distance from the position F2 to the position F1 is shorter than that of the position F3, that is, the margin from the position F2 to the position F1 is smaller than that of the position F3. Therefore, the control unit 11 changes the moving direction in the steering operation of the intermediate transfer belt 132a.

[0088] Next, a case will be described in which the control unit 11 changes the moving speed in the swinging or steering operation of any one of the objects that are candidates for the cause of the vertical stripes in step S18. In step S18, the control unit 11 determines an object whose moving speed is to be changed based on the margin of a movable position in a swing or steering operation of the object, which is a candidate for the cause of the vertical streak.

[0089] Fig. 12 shows the relationship XaT between time and position information in the main scanning direction of the fixing unit 134. Fig. 12 shows the relationship XcT between time and position information in the main scanning direction of the intermediate transfer belt 132a. Fig. 12 shows the relationship YaT between time and position information in the main scanning direction of the vertical streak. The control unit 11 changes the moving speed in the swinging or steering operation of any one of the objects that are candidates for the cause of the vertical stripe at the position F1 in the main scanning direction. The control unit 11 increases the moving speed of the object that is farther from the position F1 to the movement limit position in the swing or steering operation from the current speed. In this case, the position F3 is farther from the position F1 than the position F2, that is, the position F3 has a larger margin from the position F1 than the position F2. Therefore, the control unit 11 increases the moving speed of the swing of the fixing unit 134 from the current speed. When changing the moving speed in rocking the object, the control unit 11 changes the speed of a motor or the like that drives the rocking of the object.

[0090] Alternatively, the control unit 11 may slow down the moving speed of the object that is closer to the movement limit position in the swing or steering operation from the position F1 from the current speed. In this case, the control unit 11 may slow down the moving speed of the intermediate transfer belt 132a in the steering operation from the current speed. When changing the moving speed in the steering operation of the object, the control unit 11 changes the inclination angle of the steering roller.

[0091] In step S18, the control unit 11 makes the movement direction or movement amount of two or more objects different in the following cases. Specifically, this is the case when the correlation coefficient between the movement direction and movement amount in the main scanning direction of the two or more objects during the image forming operation and the movement direction and movement amount in the main scanning direction of the image difference between the read image and the input image during the image forming operation is a predetermined value (e.g., 97%) or more. This is the case when there are two or more pieces of position information in the main scanning direction of the object that are correlated with the position information in the main scanning direction of the image difference between the read image and the input image. In other words, this is the case when there are two or more objects that are candidates for the cause of the image difference (image defect) between the read image and the input image.

[0092] In step S18, the control unit 11 controls the moving speeds of the two or more objects to make the moving amounts of the two or more objects different. In step S18, the control unit 11 determines which of the two or more objects, the movement direction or movement amount of which is to be changed, based on the moveable distance in the movement direction of each of the two or more objects.

[0093] Next, the control unit 11 performs steps S19 and S20 which are similar to steps S12 and S13. Next, the control unit 11 obtains position information in the main scanning direction of the vertical streak in the image difference between the input image and the read image (step S21).

[0094] Next, the control unit 11 identifies position information that is correlated with the position information of the vertical stripe in the main scanning direction among the position information of each object in the main scanning direction. Next, the control unit 11 identifies the object showing the identified position information as the object that is the cause of the vertical stripe. Next, the control unit 11 determines that the identified object is defective (step S22).

[0095] FIG. 13 shows an example in which the movement direction of the intermediate transfer belt 132a is changed in the steering operation. In the example shown in FIG. 13, the correlation coefficient between the position information Xcn to Xcn+1 in the main scanning direction of the intermediate transfer belt 132a after changing the moving direction and the position information Yan to Yan+1 in the main scanning direction of the vertical streak A is less than 97%. The correlation coefficient between the position information Xan to Xan+1 in the main scanning direction of the fixing unit 134 whose movement direction has not been changed and the position information Yan to Yan+1 in the main scanning direction of the vertical streak A is 97% or more. In the example shown in FIG. 13, the control unit 11 identifies the fixing unit 134 as the object causing the vertical stripes.

[0096] Next, the control unit 11 performs step S23 similar to the determination process step S8 in the above embodiment, and ends this process.

[0097] If no vertical streaks have occurred (step S16; NO), the control unit 11 performs step S24 similar to the determination process step S9 in the above embodiment, and ends this process.

[0098] If no image defect has occurred (step S14; NO), the control unit 11 performs step S25 similar to the determination process step S10 in the above embodiment, and ends this process.

[0099] In the above embodiment and modified example, the image forming apparatus 10 is provided with the output image reading unit 14, but this is not limited to the above. The control unit 11 of the image forming apparatus 10 may obtain read image data obtained by reading an image formed on a sheet (recording medium) by an image forming operation from an external reading device that can communicate with the image forming apparatus 10. In this case, the image forming apparatus 10 and the external reading device are included in the image forming system 1.

[0100] (5. Effects) As described above, the image forming system 1 according to this embodiment is an element constituting the image forming unit 13 that forms an image on a recording medium (paper), and includes an object that moves in the main scanning direction during operations related to the formation of an image based on a print job. The image forming system 1 includes an acquisition unit (control unit 11) that acquires position information of the object in the main scanning direction during the operation. The image forming system 1 includes a reading section (output image reading section 14) that reads the image formed on the recording medium by the above-mentioned operation. The image forming system 1 includes a determination unit (control unit 11) that determines a state of the object based on the position information acquired by the acquisition unit and the read image data read by the reading unit. This makes it possible to determine the state of the object during the image forming operation of the print job, thereby reducing the time and effort required to determine the state of the object.

[0101] In the image forming system 1 of this embodiment, the judgment unit (control unit 11) judges the state of the object based on the amount of movement of the object in the main scanning direction during the operation and the amount of movement of a point of interest in the main scanning direction in the read image during the operation. This makes it possible to easily determine the state of the object during the image forming operation of the print job.

[0102] In the image forming system 1 of this embodiment, the judgment unit (control unit 11) judges the state of the object based on the movement direction in the main scanning direction of the object during the operation and the movement direction in the main scanning direction of a point of interest in the read image during the operation. This makes it possible to easily determine the state of the object during the image forming operation of the print job.

[0103] The image forming system 1 according to this embodiment includes a plurality of objects, and a control unit 11 that changes the direction or amount of movement of each object in the main scanning direction. This makes it possible to prevent the position information in the main scanning direction of each object obtained in step S2 of the determination process from becoming the same, which means that the object causing the image defect can be identified as one object.

[0104] In the image forming system 1 of this embodiment, the control unit 11 differs the movement direction or movement amount of the two or more objects when a correlation coefficient between the movement direction and the movement amount in the main scanning direction of the two or more objects during the operation and the movement direction and movement amount in the main scanning direction of a point of interest in the read image during the operation is a predetermined value or greater. The control unit 11 controls the moving speeds of the two or more objects to make the moving amounts different from each other. This makes it possible to prevent the correlation coefficient between the movement direction and movement amount in the main scanning direction of two or more objects during image formation operation and the movement direction and movement amount in the main scanning direction of a point of interest in a read image during image formation operation from exceeding a predetermined value. In other words, it is possible to identify one object that is the cause of an image defect.

[0105] In the image forming system 1 according to this embodiment, the control unit 11 determines which of the two or more objects the movement direction or the movement amount of which is to be changed, based on the moveable distance in each of the movement directions of the two or more objects. This makes it possible to determine an object more suitable for changing the movement direction or amount of movement based on the distance from the position F1 where the movement direction or amount of movement is changed to the movement limit position.

[0106] In the image forming system 1 according to this embodiment, the determination unit (control unit 11) determines that the object is defective in the following cases: Specifically, when a correlation coefficient between the amount of movement of the object in the main scanning direction during the operation and the amount of movement of a point of interest in the main scanning direction in the read image during the operation is equal to or greater than a predetermined value. This makes it possible to easily determine the state of the object during the image forming operation of the print job.

[0107] In the image forming system 1 according to this embodiment, the determination unit (control unit 11) determines that the object is defective in the following cases: Specifically, when the moving direction of the object in the main scanning direction during the operation and the moving direction of the target location in the read image during the operation in the main scanning direction are the same, that is, they match in the rightward or leftward direction. This makes it possible to easily determine the state of the object during the image forming operation of the print job.

[0108] The image forming system 1 according to the present embodiment includes a notification unit (control unit 11) that notifies the user of the object that has been determined to be defective by the determination unit (control unit 11). This allows the user to easily recognize that the object is defective.

[0109] In the image forming system 1 according to this embodiment, the notification unit (control unit 11) prompts replacement of the object determined to be defective. This allows the user to easily recognize that a defective object needs to be replaced.

[0110] In the image forming system 1 according to this embodiment, the target object is at least one of the fixing unit 134, the fixing member (fixing belt 134c), the secondary transfer unit 133, the secondary transfer member (secondary transfer roller 133a), the intermediate transfer unit 132, the intermediate transfer member (intermediate transfer belt 132a), and the photosensitive member (photosensitive drums 131Y, 131M, 131C, 131K). This makes it possible to determine the state of at least one of the fixing unit, fixing member, secondary transfer unit, secondary transfer member, intermediate transfer unit, intermediate transfer member, and photoconductor during the image forming operation of the print job.

[0111] In the image forming system 1 according to this embodiment, the object is moved in the main scanning direction by a swinging or steering operation. This makes it possible to easily determine the state of the object based on the amount and direction of movement in the main scanning direction caused by the swinging or steering operation of the object during the image forming operation of the print job.

[0112] In the image forming system 1 according to this embodiment, the portion of interest in the read image is a streak-like image defect that extends in the transport direction of the recording medium. This makes it possible to reduce the time and effort required to identify the cause of image defects such as vertical stripes of uneven density during the image forming operation of a print job.

[0113] In the image forming system 1 according to this embodiment, the image forming section 13 and the reading section (output image reading section 14) are integrally configured. Alternatively, in the image forming system 1 according to the present embodiment, the image forming unit 13 and the reading unit (output image reading unit 14) are configured to be separate entities and to be capable of communicating with each other. As a result, in either of the image forming systems having the above configurations, the state of the object can be determined during the image forming operation of the print job, which reduces the time and effort required to determine the state of the object.

[0114] Although the present invention has been specifically described above based on an embodiment thereof, the present invention is not limited to the above embodiment and can be modified without departing from the spirit of the present invention.

[0115] For example, the control unit 11 has been described as causing the photoconductor, the intermediate transfer unit 132, the secondary transfer unit 133, and / or the fixing unit 134 to oscillate in the main scanning direction during image formation, but this is not limiting. The control unit 11 has been described as causing the intermediate transfer member, the secondary transfer member, and / or the fixing member to steer in the main scanning direction during image formation, but this is not limiting. During image formation, the control unit 11 may perform a swing or steering operation in the main scanning direction on a member that is one of the elements constituting the image forming unit 13 and is other than the above-mentioned members.

[0116] In addition, the detailed configuration and operation of each device constituting the image forming apparatus 10 may be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0117] 1. Image forming system 10 Image forming device 11 Control unit (acquisition unit, determination unit, notification unit) 12 Operation display section 12a Display section 12b Operation section 13 Image forming section 131Y, 131M, 131C, 131K Photoconductor drum (photoconductor) 132 Intermediate transfer unit 132a Intermediate transfer belt (intermediate transfer member) 133 Secondary transfer unit 133a Secondary transfer roller (secondary transfer member) 134 Fixing unit 134a Heating roller 134b Upper pressure roller 134c Fixing belt (fixing member) 134d Lower pressure roller 135 Reverse Route 136 Resist section 14 Output image reading section 15 Communications Department 16 Paper feed section 17 Conveyor section 18 Document reading section 19 Memory section 20 Drive unit T1 Paper Tray T2 Output Tray

Claims

1. an object which is an element constituting an image forming unit that forms an image on a recording medium and moves in a main scanning direction during an operation related to the formation of an image based on a print job; an acquisition unit that acquires position information of the object in a main scanning direction during the operation; a reading unit that reads an image formed on the recording medium by the operation; a determination unit that determines a state of the object based on the position information acquired by the acquisition unit and the read image data read by the reading unit; An image forming system comprising:

2. The image forming system according to claim 1 , wherein the determination unit determines the state of the object based on a movement amount in the main scanning direction of the object during the operation and a movement amount in the main scanning direction of a point of interest in the read image during the operation.

3. The image forming system according to claim 2 , wherein the determination unit determines the state of the object based on a moving direction in the main scanning direction of the object during the operation and a moving direction in the main scanning direction of a point of interest in the read image during the operation.

4. A plurality of said objects; A control unit that changes the direction or amount of movement of each object in the main scanning direction; The image forming system according to claim 2 or 3, further comprising:

5. The image forming system of claim 4, wherein the control unit differs the movement direction or movement amount of the two or more objects when a correlation coefficient between the movement direction and the movement amount in the main scanning direction of the two or more objects during the operation and the movement direction and movement amount in the main scanning direction of a point of interest in the read image during the operation is a predetermined value or greater.

6. The image forming system according to claim 5 , wherein the control unit controls the moving speeds of the two or more objects to make the moving amounts different from each other.

7. The image forming system according to claim 5 , wherein the control unit determines which of the two or more objects should have its movement direction or movement amount changed based on the distance that the two or more objects can move in each of the movement directions.

8. The image forming system according to claim 2, wherein the judgment unit judges that the object is defective when a correlation coefficient between an amount of movement in the main scanning direction of the object during the operation and an amount of movement in the main scanning direction of a point of interest in the read image during the operation is greater than or equal to a predetermined value.

9. The image forming system according to claim 8 , wherein the determination unit determines that the object is defective when the direction of movement of the object in the main scanning direction during the operation coincides with the direction of movement of a point of interest in the main scanning direction in the read image during the operation.

10. The image forming system according to claim 8 , further comprising a notification unit that notifies the object that has been determined to be defective by the determination unit.

11. The image forming system according to claim 10 , wherein the notification unit prompts the user to replace the object determined to be defective.

12. 2. The image forming system according to claim 1, wherein the target object is at least one of a fixing unit, a fixing member, a secondary transfer unit, a secondary transfer member, an intermediate transfer unit, an intermediate transfer member, and a photoconductor.

13. The image forming system according to claim 1 , wherein the object is moved in the main scanning direction by a swinging or steering motion.

14. 2. The image forming system according to claim 1, wherein the portion of interest in the read image is a streak-like image defect extending in a transport direction of the recording medium.

15. 2. The image forming system according to claim 1, wherein the image forming section and the reading section are integrally configured.

16. 2. The image forming system according to claim 1, wherein the image forming unit and the reading unit are separate and communicable with each other.

Images