Faulty portion specification device, faulty portion specification method, faulty portion specification program, and image forming apparatus

Abstract

To provide a faulty portion specification device that can easily and quickly specify a faulty portion that is the cause of the occurrence of FD streaks without replacing components.SOLUTION: A faulty portion specification device comprises: an image processing unit that executes predetermined image processing on input image data to form image data for printing; an image forming unit that forms and fixes an image that is a toner image onto a sheet on the basis of the image data; a reading unit that reads an output paper conveyed from the image forming unit; and a control unit that forms a plurality of image forming modes different in components from each other, which contribute to image formation. The control unit specifies a faulty component that causes an abnormal image on the basis of images formed in the plurality of set image forming modes and read by the reading unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fault location identification device, a fault location identification method, a fault location identification program, and an image forming apparatus. [Background technology]

[0002] The main abnormal images formed on the printing paper are streaks that occur periodically in the paper transport direction (CD streaks) and streaks that occur continuously in the paper transport direction (FD streaks). Of these, for CD lines, since the rotational periods of individual parts are different, by comparing the rotational periods of each part, it is possible to identify the part with the matching period as the cause of the lines. For example, if the period of the CD streaks that have occurred matches the rotation period of the photosensitive member, it can be determined that the photosensitive member is the cause of the CD streaks. In contrast, FD streaks do not have regular characteristics such as the rotation period of a part, as CD streaks do. For this reason, there is a need to develop a useful method for identifying the cause of FD streaks.

[0003] Therefore, it has been proposed in the past to compare images formed before and after replacing a component constituting an image forming apparatus, and identify the component that caused the abnormal image (see Patent Document 1). As a result, if the FD streaks that occurred before the replacement disappear after the replacement, it becomes possible to identify the replaced and removed component as the cause of the FD streaks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-51133 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional methods for identifying faulty parts require comparing images before and after part replacement, so they are premised on part replacement, and it is not possible to identify the faulty part without replacing it. Therefore, in order to identify the part that is causing the problem, it is necessary to make a guess and replace the part, and then determine the difference in images before and after replacement, which is time-consuming and labor-intensive.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a fault location identification device, a fault location identification method, a fault location identification program, and an image forming device that can easily and quickly identify the fault location that causes FD streaks without replacing parts. [Means for solving the problem]

[0007] In order to achieve the above object, a fault location identification device according to the present invention comprises: an image processing unit that performs predetermined image processing on input image data to form image data for printing; an image forming unit that forms an image, which is a toner image, on a sheet of paper based on image data; a reading unit that reads the output paper conveyed from the image forming unit; a control unit capable of setting a plurality of image formation modes in which components contributing to image formation are different, The control unit identifies a faulty part that causes an abnormal image among the parts based on the image that is read by the reading unit from among the images formed in a plurality of set image forming modes. [Effects of the Invention]

[0008] According to the above configuration, it is possible to easily and quickly identify the fault location that is the cause of the FD streak without replacing any parts. [Brief explanation of the drawings]

[0009] Advantages and features provided by embodiments of the present invention will be more fully understood from the following detailed description and accompanying drawings, which are given by way of example and are not intended to be limiting of the invention. [Figure 1] 1 is a schematic diagram illustrating the configuration of an image forming apparatus equipped with a failure point identifying device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a functional configuration of the image forming apparatus. [Figure 3] 5 is a flowchart showing an example of a control operation by a control unit in the failure point identification device according to the present embodiment. [Figure 4] 10A and 10B are diagrams illustrating a method for determining FD streaks in the first image forming mode (electrostatic printing mode). [Figure 5A] 10A and 10B are diagrams illustrating a method for determining FD streaks in the second image forming mode (exposure printing mode). [Figure 5B] FIG. 10 is a diagram showing an image signal from an image processing unit in a second image formation mode. [Figure 6A] 10A and 10B are diagrams illustrating a method for determining FD streaks in the third image forming mode (image printing mode). [Figure 6B] FIG. 10 is a diagram showing an image signal from an image processing unit in a third image formation mode. [Figure 7] 10A and 10B are diagrams illustrating another method for determining FD streaks. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Features and technical effects of the embodiments will be understood from the following detailed description and drawings. However, the scope of the present invention is not limited to the embodiments disclosed below or the examples shown in the drawings.

[0011] 1 and 2 show an image forming apparatus 10 equipped with a fault location identification device 100 according to the present invention. This image forming apparatus 10 forms a color image on paper by electrophotography based on image data. The image data may be image data obtained by reading an image from an original document, or may be image data received from an external device. The image forming apparatus 10 includes an operation unit 13, a display unit 14, a document reading unit 15, a paper feed unit 20, a first paper reading unit 30, an image forming unit 40, an inverting unit 171, a second paper reading unit 50, a post-processing unit 60, and the like.

[0012] The operation unit 13 includes various operation buttons and a touch screen. The operation unit 13 outputs operation signals based on user operations to the control unit 11 (see FIG. 2). The various operation buttons include numeric buttons, a start button, etc. The touch screen is provided to cover the display screen of the display unit 14.

[0013] The display unit 14 is configured by an LCD (Liquid Crystal Display). The display unit 14 displays various screens in accordance with instructions of a display signal input from the control unit 11.

[0014] The document reading unit 15 includes an ADF (automatic document feeder), a scanner, etc. The document reading unit 15 reads an image of a document and outputs the image data obtained to the control unit 11.

[0015] The paper feed unit 20 includes paper feed trays 21, 22, and 23, and supplies paper to the image forming unit 40. Each of the paper feed trays 21, 22, and 23 stores paper of a predetermined paper type and size.

[0016] The first paper reading unit 30 is located downstream of the paper feed unit 20 and upstream of the image forming unit 40 in the paper transport direction. The first paper reading unit 30 reads the paper and generates a read image. The first paper reading unit 30 receives light emitted from a light source and reflected by the surface of the paper with a light receiving element and outputs a signal according to the intensity of the light. The first paper reading unit 30 is a line sensor in which multiple light receiving elements are arranged at predetermined intervals in a direction perpendicular to the paper transport direction. The first paper reading unit 30 includes a reading sensor 31 that reads the first side of the paper (the top side in FIG. 1) and a reading sensor 32 that reads the second side of the paper (the bottom side in FIG. 1). The first paper reading unit 30 uses the reading sensors 31 and 32 to simultaneously read both sides of the paper as the paper is transported through the first paper reading unit 30. In this embodiment, the reading sensors 31 and 32 are CIS (Contact Image Sensors). The first paper reading unit 30 may be a CCD (Charge Coupled Device) image sensor. The first paper reading unit 30 is not limited to a line sensor, and may be an area sensor. The first paper reading unit 30 is used to measure the size of the paper and, based on the result, to align the positions of images formed on the front and back of the paper.

[0017] The image forming unit 40 forms an image on the paper supplied from the paper supply unit 20 . Image forming unit 40 includes image creating units 41Y, 41M, 41C, 41K, and 41W corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), black (K), and white (W). Image forming unit 40 also includes an intermediate transfer belt 47, a secondary transfer unit 48, a fixing unit 49, and the like. Image creating units 41Y, 41M, 41C, 41K, and 41W are arranged in series (tandem) along the belt surface of intermediate transfer belt 47.

[0018] The image forming unit 41Y includes a photosensitive drum 42Y, a charging unit 43Y, an exposure unit 44Y, a developing unit 45Y, and a primary transfer unit 46Y. The image forming unit 41Y forms a yellow image on the intermediate transfer belt 47. The charging unit 43Y uniformly charges the surface of the photosensitive drum 42Y. The exposure unit 44Y scans and exposes the charged photosensitive drum 42Y with a laser beam based on yellow image data to form an electrostatic latent image. The developing unit 45Y develops the electrostatic latent image on the photosensitive drum 42Y by attaching yellow toner to it. The primary transfer unit 46Y transfers the yellow toner image formed on the photosensitive drum 42Y onto the rotating intermediate transfer belt 47 (primary transfer).

[0019] The image forming units 41M, 41C, 41K, and 41W are similar to the image forming unit 41Y except for the colors they handle, and therefore will not be described further. The image forming unit 41W is an image forming unit for forming a base image (white image).

[0020] A color toner image in which toner images of up to five colors are superimposed is formed on the intermediate transfer belt 47. The toner images are formed on the intermediate transfer belt 47 in the order of yellow, magenta, cyan, black, and white. The secondary transfer unit 48 transfers the color toner images on the intermediate transfer belt 47 onto a sheet of paper all at once (secondary transfer).

[0021] The fixing unit 49 includes a heating roller and a pressure roller, and fixes the color toner image onto the paper by applying heat and pressure.

[0022] The reversing unit 171 reverses the paper when forming images on both sides of the paper. The reversing unit 171 reverses the paper that has been transported downstream from the image forming unit 40 in the paper transport direction, and supplies the reversed paper to the image forming unit 40 again.

[0023] The second paper reading unit 50 is provided downstream of the image forming unit 40 and upstream of the post-processing unit 60 in the paper transport direction. The second paper reading unit 50 is an output paper reading unit known as an inline scanner, and reads an image from a paper sheet on which an image is printed. The second paper reading unit 50 is a line sensor similar to the first paper reading unit 30, and therefore a detailed description thereof will be omitted. The second paper reading unit 50 includes a reading sensor 51 that reads the first side of the paper (the top side of the paper in the figure) and a reading sensor 52 that reads the second side of the paper (the bottom side of the paper in the figure). The second paper reading unit 50 can simultaneously read both sides of the paper using the reading sensors 51 and 52 as the paper is transported through the second paper reading unit 50. Here, a CIS is used as the reading sensors 51 and 52. The second paper reading unit 50 may also be a CCD image sensor. The second paper reading unit 50 is not limited to a line sensor, and may also be an area sensor. The second paper reading unit 50 is used to inspect the image formation status and, based on the results, optimize the settings of the image forming unit 40, detect worn paper, and detect whether or not streaks have occurred in the formed image.

[0024] The post-processing unit 60 performs post-processing as necessary on the sheets conveyed from the image forming unit 40. The post-processing includes stapling, cutting, punching, folding, sorting, etc. The post-processing unit 60 is equipped with paper output trays 61 and 62.

[0025] FIG. 2 is a block diagram showing the functional configuration of the image forming apparatus 10. As shown in FIG. 2, the image forming apparatus includes a control unit 11, a storage unit 12, an operation unit 13, a display unit 14, a document reading unit 15, a communication unit 16, a conveying unit 17, an image processing unit 18, a paper feeding unit 20, a first paper reading unit 30, an image forming unit 40, a second paper reading unit 50, and a post-processing unit 60. Note that a description of the functional units that have already been described will be omitted.

[0026] The control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU reads out various processing programs stored in the ROM in response to an operation signal input from the operation unit 13 or an instruction signal received by the communication unit 16. The CPU loads the read program into the RAM and controls the operation of each unit of the image forming apparatus 10 in accordance with the program.

[0027] The storage unit 12 is configured by a storage device such as a hard disk, a flash memory, etc. The storage unit 12 stores various types of data.

[0028] The communication unit 16 transmits and receives data to and from external devices connected to a communication network such as a LAN (Local Area Network). The image processing unit 18 performs predetermined image processing such as tone correction and screen processing on the input image data to form image data for printing.

[0029] The conveying unit 17 includes a conveying roller. The conveying unit 17 conveys paper within the image forming apparatus 10. For example, the conveying unit 17 supplies paper stored in paper feed trays 21, 22, and 23 of the paper feed unit 20 to the image forming unit 40 via the first paper reading unit 30. The conveying unit 17 conveys the paper after image formation to the post-processing unit 60 via the second paper reading unit 50, and discharges the paper onto the paper discharge trays 61 and 62. The conveying unit 17 includes an inverting unit 171.

[0030] Assume that a user has confirmed that FD streaks have appeared on paper on which an image has been printed in the above-described image forming apparatus 10. In this case, in order to identify the part (faulty part) that is causing the FD streaks, the control unit 11 is caused to perform the following diagnostics based on a diagnostic command from the operation unit 13 by the user.

[0031] The normal process for printing an image on paper is to use a laser beam to project the image data pattern onto a charged photoconductor, forming an electric latent image on the surface of the photoconductor, then toner is applied to the latent image on the photoconductor (development), the toner image attached to the latent image is transferred to paper, and the toner image transferred to the paper is then fixed.

[0032] At this time, there are various causes of the occurrence of FD streaks, but possible causes include failure of components in the charging section, failure of components in the exposure section, failure of components used when processing images in the image processing section, etc. Therefore, in order to identify the faulty component without replacing the component, the components that may be faulty are separated by function, and unique images formed by the components used in each function are created. These images are then read and analyzed by the second paper reading section 50 to identify the component that caused the FD streaks. That is, the control unit 11 adjusts the charging units 43Y, 43M, 43C, 43K, and 43W, the exposure units 44Y, 44M, 44C, 44K, and 44W, and the image processing unit 18 to set a plurality of image formation modes in which different components contribute to image formation. That is, a plurality of inspection modes in which images are formed using different components are created. Then, the presence or absence of FD streaks is checked for images formed in each image formation mode to narrow down the components that cause the FD streaks.

[0033] As described above, the image formation process is as follows: image processing (electrical signal) → exposure (laser light) → latent image formation (charge potential) → development (toner image) → transfer (toner image) → fixing (toner image). Taking this process into consideration, the control unit 11 adjusts the charge potential applied to the charging unit, the amount of exposure light from the exposure unit, and the image processing by the image processing unit, to selectively form the following three image formation modes with different image formation methods (different components contributing to image formation): First image formation mode: An inspection mode in which no output is generated from the exposure unit or image processing unit, and an image is formed only by charging the charging unit. Second image formation mode: An inspection mode in which the output from the image processing unit is fixed and an image is formed using only the light amount from the exposure unit. Third image formation mode: A mode in which the charging unit and the exposure unit are operated to form an image based on image data processed by the image processing unit.

[0034] The first image formation mode is a mode (charged printing mode) in which the charge potential is fixed at a predetermined value, laser light is not irradiated by the exposure unit, and image processing is not performed by the image processing unit (the exposure unit and image processing unit are not functioning), and an image is printed by developing, transferring, and fixing in this state. In this case, if there is no particular abnormality, a solid color image corresponding to the charge potential is printed. However, if the result of reading by the second paper reading unit 50 indicates that FD streaks appear on the printed paper, it can be determined that the FD streaks are caused by a malfunction of the charge unit or one of its subordinate components (developing unit, transfer unit, fixing unit).

[0035] The second image inspection mode is a mode (exposure printing mode) in which the charging unit charges normally, the image processing unit does not perform image processing, and the exposure light amount is fixed at a predetermined value, and then development, transfer, and fixing are performed to print the image. In this case, a solid color image corresponding to the exposure light amount is normally printed. However, if FD streaks appear on the printed paper, and if FD streaks were not detected in the first inspection mode, it can be determined that there is an abnormality in the exposure component.

[0036] The third image formation mode is a normal printing mode (image printing mode) by the image processing unit. If no abnormality is found in the first image formation mode or the second image formation mode, but an abnormality is found in the third image inspection mode, it can be determined that there is an abnormality in the image processing component.

[0037] In this way, the defective part causing the FD streak can be narrowed down to which part is located after the charging section, in the exposure section, or in the image processing section, by reading and analyzing the images formed using different image formation parts with the second paper reading section 50.

[0038] Therefore, the failure point identifying device 100 according to this embodiment is incorporated into the image forming device 10 described above. That is, the fault location identification device 100 is incorporated into an image forming device 10 that includes an image processing unit 18 that performs predetermined image processing on input image data to form image data for printing, an image forming unit 40 that forms and fixes a toner image on paper based on the image data from the image processing unit 18, and an output paper reading unit (second paper reading unit 50 that is an inline scanner) that reads the output paper transported from the image forming unit 40. The fault location identification device 100 creates a plurality of image formation modes in which the components that contribute to image formation differ by adjusting the charging unit, exposure unit, and image processing unit using the control unit 11. Then, the presence or absence of an abnormal image is determined by analyzing the images printed in each image formation mode, and the faulty component is identified.

[0039] Next, a specific description will be given of a fault location identification method performed by the above-described fault location identification device 100. This fault location identification method is a process performed by the control unit 11 based on the fault location identification program of this embodiment. Below, a description will be given of a fault location identification method performed by the control unit 11 for identifying a faulty part based on the flowchart shown in Fig. 3. The example shown here is an example of an operation process for identifying the part (faulty part) that caused the FD streak, assuming that an FD streak has occurred when a color image is printed on paper.

[0040] In color printing, the image processing unit, exposure unit, and charging unit are separated into Y, M, C, and K units, so the following processing is first performed on the image processing unit, exposure unit, and charging unit that prints Y color. That is, the control unit 11 selects printing of Y color (step 100), and then sets the mode to the first image forming mode (step 102), in which the outputs from the image processing unit 18 and the exposure unit 44Y are set to zero, and an image formed only by the potential of the charging unit 43Y is printed.

[0041] Even if the output from the image processing unit 18 and the exposure unit 44Y is set to zero, increasing the charging potential used to charge the photosensitive drum 42Y increases the toner image density. Because there are densities at which FD streaks are more likely to appear, the charging potential is gradually changed, and each time, the presence or absence of FD streaks is checked for the printed image. Specifically, the charging potential is first set to its minimum initial value (step 104), and an image is printed on paper in that state (step 106). The printed image on the paper is then read by the second paper reading unit (inline scanner) 50 (step 108), and the presence or absence of FD streaks is checked (step 110). To check for FD streaks, the second paper reading unit reads the main scan line image, which is perpendicular to the paper transport direction, line by line along the sub-scan direction (paper transport direction), and adds these to calculate the average value.If the average value exceeds a preset threshold, it is determined that FD streaks have occurred.

[0042] As shown in FIG. 4, FD streaks include black streaks and white streaks, and a threshold value is set for each density to determine whether or not an FD streak exists. For example, if an FD streak as shown in FIG. 4 has occurred, and the image is read by the second paper reading unit 50, and the average value of the main scan line is shown as a solid line, the black streak portion will have a curve that is convex on the positive side, where the density of the average value increases. Therefore, if this curve exceeds the threshold value that identifies black streaks (becomes larger than the threshold value), it is determined that an FD streak has occurred. Also, in the white streak portion, the curve is a curve that is convex on the negative side, where the density of the average value decreases. Therefore, if this curve exceeds the threshold value that identifies white streaks (becomes smaller than the threshold value), it is determined that an FD streak has occurred. If FD streaks are detected by the above process, it is determined that there is a faulty part causing FD streaks in any of the parts after the charging part (charging part, developing part, transfer part, fixing part).Then, the determination result is stored in the memory unit 12 (step 112).

[0043] On the other hand, if no FD streaks are detected in step 110, the charge potential is increased by a predetermined amount (α) within a range that does not exceed 100% density (to increase the toner image density) (steps 114, 116). Then, an image is printed in this state, and the presence or absence of FD streaks is determined again (steps 106 to 110). The above process is repeated, and when the charging potential exceeds 100% density (step 114), the first inspection mode ends and the process moves to the second inspection mode (step 118).

[0044] In this second inspection mode, the exposure light intensity is fixed at a predetermined light intensity (no on / off control), and there is no image processing by the image processing unit 18. That is, the mode is set to print an image on paper using only the component that adjusts the exposure light intensity. Increasing the exposure light intensity increases the density of the toner image. Therefore, the exposure amount (laser light amount) is controlled to create a toner image, and the presence or absence of FD streaks in the image printed on paper is confirmed. First, the exposure amount is set to the minimum initial value (step 120), and the image is printed on paper in that state (step 122). The printed image is then read by the second paper reading unit (inline scanner) 50 (step 124), and the presence or absence of FD streaks is detected (step 126). At this time, the image signal from the image processing unit 18 is set to a fixed output (a state in which the gradation is fixed and the image is constantly exposed) as shown in Fig. 5B, so that there is no influence of the control of the image signal. Note that the charging state is the same as that for normal image printing.

[0045] To check for FD streaks, the second paper reading unit reads the main scan line image, which is perpendicular to the paper transport direction, line by line along the sub-scan direction (paper transport direction), and adds these to calculate the average value.If the average value exceeds a preset threshold, it is determined that FD streaks have occurred.

[0046] As shown in FIG. 5A, FD streaks include black streaks and white streaks, and a threshold value is set for each density to determine whether or not an FD streak exists. For example, if an FD streak as shown in FIG. 5A has occurred, and the image is read by the second paper reading unit 50, and the average value of the main scan line is shown as a solid line, the black streak portion will have a curve that is convex on the positive side, where the density of the average value increases. Therefore, if this curve exceeds the threshold value that identifies black streaks (becomes larger than the threshold value), it is determined that an FD streak has occurred. Also, in the white streak portion, the curve is a curve that is convex on the negative side, where the density of the average value decreases. Therefore, if this curve exceeds the threshold value that identifies white streaks (becomes smaller than the threshold value), it is determined that an FD streak has occurred.

[0047] The second image forming mode is executed when FD streaks do not appear in the first image forming mode (electrostatic printing mode). Therefore, if FD streaks are detected in the second image forming mode (exposure printing mode) (step 126), it is determined that the exposure unit 44Y is the cause of the FD streaks. In other words, it is determined that there is a faulty component in the exposure unit 44Y that causes the FD streaks. Then, the determination result is stored in the memory unit 12 (step 128).

[0048] On the other hand, if no FD streaks are detected, the amount of exposure light is increased by a predetermined value (β) within the range where the printed image does not exceed 100% density, thereby increasing the toner image density (steps 130 and 132).Then, in this state, the presence or absence of FD streaks is determined again (the processes of steps 122 to 126 are repeated). If the FD streak is not reproduced in the second image forming mode, the process moves to the third image forming mode (step 134).

[0049] This third inspection mode is set to a normal printing mode in which an image is formed by exposure control of the image processing unit (step 136). That is, image data that has been image processed on a pixel-by-pixel basis in the image processing unit is output to create a toner image, which is then printed (step 138). The image signal from image processing unit 18 outputs a pattern whose gradation has been controlled on a pixel-by-pixel basis, as shown in FIG. 6B. Then, the image printed on the paper is read by second paper reading unit (inline scanner) 50 (step 140), and the presence or absence of FD streaks is detected (step 142).

[0050] As with the electrostatic printing mode, FD streaks are detected by adding up the main scan line images across the sub-scanning direction to calculate the average value, and if the average value exceeds a preset threshold, it is determined that FD streaks have occurred. In this case, too, FD streaks include black streaks and white streaks, as shown in FIG. 6A, and a threshold value is set for each density to determine whether or not FD streaks exist. For example, when the image in which FD streaks have occurred, as shown in FIG. 6A, is read by the second paper reading unit 50, and the average value of the main scan line is shown as a solid line, the black streaks form a curve that is convex on the positive side, where the density of the average value increases. Therefore, when this curve exceeds the threshold value that identifies black streaks (when it becomes larger than the threshold value), it is determined that FD streaks have occurred. Furthermore, in the white streaks, it forms a curve that is convex on the negative side, where the density of the average value decreases. Therefore, when this polarity exceeds the threshold value that identifies white streaks (when it becomes smaller than the threshold value), it is determined that FD streaks have occurred.

[0051] The third image forming mode is executed when FD streaks do not appear in the first image forming mode (electrostatic printing mode) or the second image forming mode (exposure printing mode). Therefore, when FD streaks are detected in the third image forming mode (image printing mode) (step 142), it is determined that the cause of the FD streaks is in the image processing unit 18. In other words, it is determined that there is a faulty component in the image processing unit 18 that causes the FD streaks. Then, the determination result is stored in the memory unit 12 (step 144).

[0052] If no FD streaks are detected in the third image forming mode either, it is determined that there is no reproduction (step 146), and then the print color is changed sequentially to M, C, and K, and the above-mentioned inspection is repeated (steps 148, 150). Also, if it is determined in step 112 that the cause lies in the components after the charging unit, if it is determined in step 128 that the cause lies in the exposure unit, or if it is determined in step 144 that the cause lies in the image processing unit, the print color is changed sequentially to M, C, and K, and the above-mentioned inspection is repeated (steps 148, 150). After the inspection of all colors is completed, the inspection results, such as displaying the faulty parts, are displayed for the operator (user) to recognize (step 152).

[0053] Therefore, with the above-described fault location identification device 100, an image formation mode is set for each component that may be the cause of a fault (multiple inspection modes are prepared for different components that form images), and the fault location can be identified by identifying the component that was used when the FD streak occurred. This makes it possible to easily and quickly identify the fault location that caused the FD streak. Furthermore, since there is no need to physically replace components and check for the presence or absence of FD streaks, it is possible to reduce the amount of work required.

[0054] In the above, the average value of the image of the main scan line is calculated, and if the density of the average value exceeds a preset threshold, it is determined that FD streaks have occurred. As another determination method, as shown in Figure 7, an FD streak detection image (streak profile) may be registered in advance, and compared with images read in each image formation mode, and if they match or are similar, it may be determined that FD streaks have occurred.

[0055] As described above, the fault location identification device 100 according to this embodiment includes an image processing unit 18 that performs predetermined image processing on input image data to form image data for printing, an image forming unit 40 that forms an image, which is a toner image, on paper based on the image data, a reading unit (second paper reading unit 50 that is an inline scanner) that reads the output paper conveyed from the image forming unit 40, and a control unit 11 that can set multiple image formation modes in which different components contribute to image formation. Then, the control unit 11 identifies a faulty component that generates an abnormal image among the components, based on the images formed in the multiple set image formation modes read by the reading unit (second paper reading unit 50).

[0056] Therefore, the control unit 11 sets a plurality of image formation modes in which different components contribute to image formation. That is, the control unit 11 sets a plurality of image formation modes that can determine whether or not there is a failure in the components that serve as the charging unit, exposure unit, or image processing unit. Then, if an abnormal image is detected in any of the image formation modes, it is determined that there is a faulty component that is causing the abnormal image among the components that contribute to that image formation mode.

[0057] The process flow for forming an image is as follows: image processing (electrical signal) → exposure (laser light) → latent image formation (charge potential) → development (toner image) → transfer (toner image) → fixing (toner image). Therefore, a first image formation mode (charge printing mode) is established in which the functions of the exposure unit and image processing unit are stopped and an image is formed using only charging by the charging unit. If an abnormality is found in the image obtained in this first image formation mode, it is determined that there is an abnormality in the charging unit or components downstream of it (components of the development unit, transfer unit, and fixing unit).

[0058] Also, a second image forming mode (exposure printing mode) is established in which the function of the image processing unit 18 is stopped and an image is formed using only the amount of exposure light from the exposure units 44Y, 44M, 44C, 44K, and 44W. If an abnormality is found in the image obtained in this second image forming mode, and if no abnormal image is found in the first image forming mode, it is determined that there is an abnormality in the components of the exposure units 44Y, 44M, 44C, 44K, and 44W.

[0059] Furthermore, a third image forming mode (image printing mode) is established in which the charging unit and the exposure unit are operated to form an image based on an image processed by the image processing unit 18. If an abnormality is found in the image obtained in this third image forming mode, and if no abnormal images are found in the first image forming mode and the second image forming mode, it is determined that there is an abnormality in the components of the image processing unit 18. In this way, the control unit 11 sets the image formation mode in the order of the first image formation mode, the second image formation mode, and the third image formation mode, and determines whether or not there is an abnormal image.

[0060] Therefore, by preparing multiple image formation modes that vary the components that contribute to image formation by adjusting the charging potential applied to the charging unit, the exposure light amount of the exposure unit, and the image processing by the image processing unit, it is possible to narrow down the components that cause abnormal images.This makes it possible to easily and quickly identify the faulty part that is causing the FD streak without replacing the components.

[0061] In the first image formation mode, the charging potential is set to an upper limit equivalent to 100% density. In the second image formation mode, the exposure light amount is set to an upper limit equivalent to 100% density. In the third image formation mode, the charging potential and exposure light amount are set to values ​​used during normal printing, and the input image data is processed pixel by pixel to form an image.

[0062] The presence or absence of an abnormal image may be detected by setting a threshold value for detecting an abnormality in an image for each image forming mode, and the control unit 11 may detect the presence or absence of an abnormal image by comparing with this threshold value. As another example of detecting whether or not an abnormal image exists, an image of the output paper on which the abnormal image occurred may be registered as a reference image, and the control unit 11 may detect whether or not an abnormal image exists by comparing the image output in the image formation mode with the reference image. The above-described failure point identifying device 100 may be provided as part of the image forming device 10.

[0063] The fault location identification method according to this embodiment is a method for identifying a fault location in an image forming apparatus that includes an image processing unit that performs predetermined image processing on input image data to form image data for printing, an image forming unit that forms an image, which is a toner image, on paper based on the image data, and a reading unit that reads output paper transported from the image forming unit. The fault location identification method sets multiple image formation modes that differ in the components that contribute to image formation, and identifies a faulty component that generates an abnormal image based on images formed in the multiple image formation modes that are read by the reading unit.

[0064] Therefore, by adjusting the charging unit, exposure unit, and image processing unit to set multiple image formation modes that vary the components that contribute to image formation and determining whether or not an abnormal image is produced, it is possible to narrow down the defective component that is causing the abnormal image. This makes it possible to easily and quickly identify the faulty part that is causing the FD streak without replacing the defective component.

[0065] Furthermore, the fault location identification program according to this embodiment is a fault location identification program for identifying a fault location in an image forming apparatus that includes an image processing unit that performs predetermined image processing on input image data to form image data for printing, an image forming unit that forms an image, which is a toner image, on paper based on the image data, and a reading unit that reads output paper conveyed from the image forming unit. The fault location identification program sets multiple image formation modes that differ in the components that contribute to image formation, then causes the reading unit to read images formed in the multiple image formation modes that have been set, and identifies a faulty component that generates an abnormal image based on the images read by the reading unit.

[0066] Therefore, by adjusting the charging unit, exposure unit, and image processing unit to set multiple image formation modes that vary the components that contribute to image formation and determining whether or not an abnormal image is produced, it becomes possible to narrow down the faulty component that is causing the abnormal image. As a result, it becomes possible to easily and quickly identify the faulty part that is causing the FD streak without replacing the faulty component.

[0067] <Supplementary information> Although the embodiments and modifications of the fault location identification device, fault location identification method, fault location identification program, and image forming apparatus according to the present invention have been described, the present invention is not limited to the above-described embodiments and modifications. The present invention also includes forms obtained by applying various modifications to the above-described embodiments and modifications that would occur to those skilled in the art, as well as forms realized by arbitrarily combining the components and functions of the embodiments and modifications within the scope of the present invention. The scope of the present invention should be interpreted by the appended claims. [Explanation of symbols]

[0068] 10 Image forming device 18 Image processing section 43Y, 43M, 43C, 43K, 43W charging unit 44Y, 44M, 44C, 44K, 44W Exposure section 45Y, 45M, 45C, 45K, 45W Development Unit 46Y, 46M, 46C, 46K, 46W Primary transfer unit 48 Secondary transfer unit 49 Fixing section 100 Fault location identification device

Claims

1. an image processing unit that performs predetermined image processing on input image data to form image data for printing; an image forming unit that forms an image, which is a toner image, on a sheet of paper based on image data; a reading unit that reads the output paper conveyed from the image forming unit; a control unit capable of setting a plurality of image formation modes in which components contributing to image formation are different, The control unit is a fault location identification device that identifies a faulty part that generates an abnormal image among the parts based on an image formed by a plurality of set image formation modes and read by the reading unit.

2. the plurality of image forming modes include three image forming modes, the image forming unit has a charging unit and an exposure unit, the first image forming mode is a mode in which the functions of the exposure unit and the image processing unit are stopped, and the charging potential of the charging unit is fixed to form the image; the second image forming mode is a mode in which the function of the image processing unit is stopped and the amount of exposure light by the exposure unit is fixed to form the image; The third image forming mode is a mode in which the charging unit and the exposure unit are operated to form the image based on image data that has been image-processed by the image processing unit. The fault location device according to claim 1 .

3. 3. The failure point identifying device according to claim 2, wherein the control unit sets the plurality of image formation modes in the order of the first image formation mode, the second image formation mode, and the third image formation mode, and determines whether or not an abnormal image is present.

4. When an abnormal image is detected in the first image forming mode, it is determined that the cause of the failure is one of the components of the charging unit, the developing unit, the transfer unit, and the fixing unit, When an abnormal image is detected in the second image forming mode, if an abnormal image is not generated in the first image forming mode, it is determined that a component of the exposure unit is the cause of the failure; 3. The fault location identification device according to claim 2, wherein when an abnormal image is detected in the third image formation mode, if no abnormal images are generated in the first image formation mode and the second image formation mode, it is determined that a component in the image processing unit is the cause of the fault.

5. 3. The fault location device according to claim 2, wherein the first image forming mode is set such that the upper limit of the charging potential is set to a potential corresponding to 100% density.

6. 3. The fault location device according to claim 2, wherein the second image forming mode is set such that the upper limit of the exposure light amount is set to an exposure light amount corresponding to 100% density.

7. 3. The fault location device according to claim 2, wherein the third image forming mode sets the charging potential and the exposure light amount to values ​​used during normal printing, and forms an image by processing the input image data pixel by pixel.

8. 3. The failure point identifying device according to claim 2, wherein a threshold value for detecting an abnormality in an image is set for each of said image forming modes, and said control unit detects the presence or absence of an abnormal image by comparing with said threshold value.

9. 2. The fault location identification device according to claim 1, wherein an image of an output sheet on which an abnormal image has occurred is registered as a reference image, and the control unit detects the presence or absence of an abnormal image by comparing the image output in the image formation mode with the reference image.

10. an image processing unit that performs predetermined image processing on input image data to form image data for printing; an image forming unit that forms an image, which is a toner image, on a sheet of paper based on image data; a reading unit that reads the output paper conveyed from the image forming unit; A fault location identification method for identifying a fault location in an image forming apparatus comprising: A plurality of image formation modes are set in which the components that contribute to image formation are different, A defective part that generates an abnormal image is identified from among the parts based on the image read by the reading unit from among the images formed by the set plurality of image forming modes. How to identify the fault location.

11. an image processing unit that performs predetermined image processing on input image data to form image data for printing; an image forming unit that forms an image, which is a toner image, on a sheet of paper based on image data; a reading unit that reads the output paper conveyed from the image forming unit; A fault location identification program for identifying a fault location in an image forming apparatus comprising: A plurality of image formation modes are set in which components that contribute to image formation are different, reading images formed in a plurality of set image forming modes by the reading unit; Based on the image read by the reading unit, a defective part that generates an abnormal image is identified among the parts. Fault location program.

12. An image forming apparatus comprising the fault location identifying device according to any one of claims 1 to 9.

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