Image forming apparatus

Abstract

To provide an image forming apparatus capable of reducing a work load of adjustment work of an operator when an error of a resist correction function occurs.SOLUTION: An image forming apparatus 1 includes a resist correction part 11 for detecting the formation mode of each color resist pattern formed on an intermediate transfer belt by a resist sensor 180 and correcting a color shift amount of each color based on the detection result, a first storage part 20 for storing measurement data of the color shift amount of each color measured by the resist correction part 11, and an information presentation part 12 for presenting work support information to an operator based on the measurement data stored in the first storage part 20 when the resist correction part 11 indicates an error.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Conventionally, the mainstream of color image forming devices using electrophotographic process technology is the intermediate transfer method using an intermediate transfer body such as an intermediate transfer belt. The intermediate transfer method involves transferring a toner image formed on a photosensitive drum for each color to the intermediate transfer body, overlaying multiple color toner images (for example, four colors of YMCK) on the intermediate transfer body, and then transferring the resulting image to paper.

[0003] In this type of image forming apparatus, the toner images formed on each photosensitive drum must be accurately superimposed on the intermediate transfer belt. However, misalignment of the colors on the paper (hereinafter referred to as "color misalignment") can occur due to deviations in the positional accuracy or diameter of each photosensitive drum, deviations in the positional accuracy of the optical system, and deterioration of components over time.

[0004] FIG. 1 is a diagram showing an example of a color misregistration pattern.

[0005] The color shift modes include, for example, the following six types. (a) Color misalignment due to a shift in the writing position in the main scanning direction (the direction perpendicular to the running direction of the intermediate transfer belt) (see Figure 1a, hereafter referred to as "color misalignment in the main scanning direction") (b) Color misalignment due to misalignment of the writing position in the sub-scanning direction (the direction of travel of the intermediate transfer belt) (see Figure 1b, hereafter referred to as "color misalignment in the sub-scanning direction"). (c) Color shift due to overall magnification error in the main scanning direction (see Figure 1c, hereafter referred to as "overall magnification color shift") (d) Color shift due to partial magnification error in the main scanning direction (see Figure 1d, hereafter referred to as "partial magnification color shift") (e) Color misalignment due to image tilt in the sub-scanning direction (see Figure 1e, hereafter referred to as "image tilt color misalignment (skew)") (f) Color shift due to image curvature in the sub-scanning direction (see Figure 1f, hereafter referred to as "image curvature color shift (bow)")

[0006] 1a to 1f, the solid lines represent the ideal image formation positions, and the dotted lines represent the actual image formation positions. Also, d1, d2, d3, d4, d5, and d6 represent the amount of positional deviation between the ideal image formation positions and the actual image formation positions, i.e., the amount of color deviation.

[0007] To prevent this color misregistration, a registration pattern for correcting color misregistration is formed on the outer surface of the intermediate transfer belt when paper is not being printed, and color misregistration registration correction is performed based on the detection results of this registration pattern. For example, see Patent Document 1. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-217300 Summary of the Invention [Problem to be solved by the invention]

[0009] In this type of image forming apparatus, there are various factors that cause color misregistration, such as the assembly of the photosensitive drum, the assembly of the exposure device, and fluctuations in the belt speed of the intermediate transfer belt. The color misregistration mode varies depending on the state of each of these components. In other words, the six types of color misregistration (main scanning, full horizontal magnification, partial horizontal magnification, sub-scanning, skew, and bow) each involve different related components.

[0010] Normally, when performing registration correction in this type of image forming apparatus, the image forming conditions for each component as described above are corrected for each color misregistration mode, but there is a limit to the range of correction that can be performed. Therefore, in this type of image forming apparatus, if a color misregistration that exceeds the correctable range is detected, an error is output and operation of the apparatus is halted. Also, in this type of image forming apparatus, if the amount of color misregistration fluctuates with each measurement during multiple color misregistration measurements, an error is output and operation of the apparatus is halted, indicating that there is some kind of abnormality in the apparatus.

[0011] In such a case, for example, an operator will have to perform adjustment work to mechanically adjust each part (for example, a photosensitive drum, an exposure device, an intermediate transfer belt, etc.) inside the image forming apparatus.

[0012] In current image forming apparatuses, when an error occurs in the registration correction function, the operator is unable to recognize the target of adjustment work. Therefore, when performing such adjustment work, the operator is forced to comprehensively inspect each section within the image forming apparatus and adjust the components. Furthermore, as a result, necessary adjustments may not be made completely, which can lead to frequent errors.

[0013] In this context, there is a demand for reducing the workload of adjustment work for an image forming apparatus when an error occurs in the registration correction function.

[0014] The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide an image forming apparatus that can reduce the workload of an operator in making adjustments when an error occurs in the registration correction function. [Means for solving the problem]

[0015] The main invention that solves the above-mentioned problems is: An image forming apparatus having a photosensitive drum for each color, and forming a color image by superimposing images formed on the photosensitive drums of each color on an intermediate transfer belt, a registration correction unit that detects the state of the registration patterns of each color formed on the intermediate transfer belt by a registration sensor and corrects the amount of color misregistration of each color based on the detection result; a first storage unit for storing measurement data of the color misregistration amount for each color measured by the registration correction unit; an information presenting unit that presents work support information to a worker based on the measurement data stored in the first storage unit when the registration correction unit indicates an error; The image forming apparatus includes: [Effects of the Invention]

[0016] According to the image forming apparatus of the present invention, it is possible to reduce the workload of the operator in making adjustments when an error occurs in the registration correction function. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 10 is a diagram showing an example of a color shift pattern. [Figure 2] 1 is a diagram showing a schematic configuration of an image forming apparatus; [Figure 3] Block diagram showing the configuration of a control system of an image forming apparatus [Figure 4] FIG. 2 is a diagram showing the functional configuration of a control unit of the image forming apparatus; [Figure 5] FIG. 10 is a diagram showing an example of the position where a resist sensor is disposed and the position where a resist pattern is formed. [Figure 6] FIG. 10 is a diagram showing an example of a method for measuring the amount of color misregistration. [Figure 7] FIG. 10 is a diagram showing an example of measurement data of color misregistration amounts stored in a storage unit; [Figure 8] Figure showing example 1 of the error status list display [Figure 9] Figure showing example 2 of the error status list display [Figure 10] Figure showing example 3 of the error status list display [Figure 11] FIG. 10 is a diagram showing an example of a situation in which the amount of color misregistration is unstable. [Figure 12]FIG. 10 is a diagram showing an example of a situation in which the amount of color misregistration exceeds the correctable range. [Figure 13] FIG. 10 is a diagram illustrating an example of a situation in which a belt speed deviation occurs in an intermediate transfer belt. [Figure 14] A diagram explaining the mechanism by which the belt speed deviation of the intermediate transfer belt occurs [Figure 15] An example of the alert display for the belt speed deviation of the intermediate transfer belt [Figure 16] FIG. 10 is a diagram showing an example of related part data stored in a storage unit; [Figure 17] Figure showing an example of error-related part display [Figure 18] A diagram showing an example of an area that needs adjustment, predicted from an error situation during registration correction. [Figure 19] FIG. 10 is a diagram showing a modified example of the display example of the error-related component display; [Figure 20] FIG. 10 is a diagram showing an example of a flowchart for determining whether a related part of color K is the cause of an error. [Figure 21] FIG. 10 is a diagram showing an example of work history data stored in a storage unit; [Figure 22] A diagram showing an example of the work history display DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0019] [Overall configuration of image forming apparatus 1] An example of the overall configuration of an image forming apparatus according to one embodiment of the present invention (hereinafter referred to as "image forming apparatus 1") will be described below with reference to FIGS.

[0020] Fig. 2 is a diagram showing a schematic configuration of the image forming apparatus 1. Fig. 3 is a block diagram showing the configuration of a control system of the image forming apparatus 1. Fig. 4 is a diagram showing the functional configuration of a control unit 10 of the image forming apparatus 1.

[0021] The image forming apparatus 1 is, for example, an intermediate transfer type color image forming apparatus that uses electrophotographic process technology. The image forming apparatus 1 primarily transfers each color toner image formed on a photosensitive drum of each color onto an intermediate transfer belt, then superimposes the toner images of each color on the intermediate transfer belt, and then secondarily transfers them onto paper to form an image. In this example, the image forming apparatus 1 uses four colors: C (cyan), M (magenta), Y (yellow), and K (black).

[0022] The image forming apparatus 1 includes a control unit 10, a memory unit 20, an image reading unit 110, an operation display unit 120, an image processing unit 130, an image forming unit 140, a conveying unit 150, a fixing unit 160, a communication unit 170, and a registration sensor 180.

[0023] The control unit 10 performs overall control of each unit of the image forming apparatus 1. The control unit 10 includes a CPU 10a, a ROM 10b, a RAM 10c, etc. The CPU 10a reads a program corresponding to the processing content from the ROM 10b, loads it into the RAM 10c, and works with the loaded program to centrally control the operation of each block of the image forming apparatus 1. At this time, various data (e.g., print data for the resist patterns 200 of each color, etc.) stored in the storage unit 20 is referenced.

[0024] The control unit 10 functions as a registration correction unit 11 and an information presentation unit 12. The registration correction unit 11 has a function of detecting the formation state of the registration pattern 200 of each color formed on the intermediate transfer belt 1421 using a registration sensor 180, and correcting the amount of color misregistration of each color based on the detection result. Furthermore, the information presentation unit 12 has a function of presenting work support information to the worker based on measurement data D1 stored in the memory unit 20 when the registration correction unit 11 indicates an error.

[0025] The storage unit 20 stores various data referenced by the control unit 10 when implementing the functions of the registration correction unit 11 and the information presentation unit 12. Specifically, the storage unit 20 stores measurement data D1 of the color misregistration amount for each color measured during registration correction. The storage unit 20 also stores related part data D2, which is data on parts related to registration correction of various parts in the image forming apparatus 1. The storage unit 20 also stores work history data D3, which is data on the work history performed on the image forming apparatus 1 by an operator.

[0026] The communication unit 170 transmits and receives various data to and from an external device (e.g., a personal computer) connected to a communication network such as a LAN or a WAN. The control unit 10 is capable of receiving image data transmitted from the external device via the communication unit 170.

[0027] The image reading unit 110 includes an automatic document feeder 111 called an ADF, an image scanning device 112, and the like.

[0028] The automatic document feeder 111 transports the document D placed on the document tray using a transport mechanism and sends it to the image scanning device 112. When a large number of documents D are placed on the document tray, the automatic document feeder 111 can continuously read the images of the documents D.

[0029] The image scanning device 112 optically scans an original document transported onto the contact glass from the automatic document feeder 111 or an original document placed on the contact glass, and forms an image of the light reflected from the original document on the light receiving surface of the CCD sensor 112a, thereby reading the original document image. The image reading unit 110 generates input image data based on the reading result by the image scanning device 112. The image processing unit 130 performs predetermined image processing on this input image data.

[0030] The operation display unit 120 is composed of, for example, a liquid crystal display with a touch panel, and functions as a display unit 121 and an operation unit 122. The display unit 121 displays various operation screens, image status displays, operation statuses of various functions, etc. in accordance with a display control signal input from the control unit 10. The operation unit 122 has various operation keys such as a numeric keypad and a start key, accepts various input operations by the user, and outputs operation signals to the control unit 10.

[0031] The image processing unit 130 includes a circuit for performing digital image processing on input image data according to initial settings or user settings, etc. The image forming unit 140 is controlled based on the image data that has undergone digital image processing.

[0032] The image forming unit 140 includes toner image forming units 141Y, 141M, 141C, and 141K for forming images using color toners of Y, M, C, and K components based on input image data, an intermediate transfer body 142, and the like.

[0033] The image forming unit 140 has a configuration in which photosensitive drums 1413 corresponding to the four colors of toner image forming units 141Y, 141M, 141C, and 141K are arranged in series in the running direction of an intermediate transfer belt 1421. Then, the image forming unit 140 sequentially transfers the toner images of each color onto the intermediate transfer belt 1421 (also called a tandem system).

[0034] The toner image forming units 141Y, 141M, 141C, and 141K for the Y, M, C, and K components have the same configuration. For ease of illustration and explanation, common components are denoted by the same reference numerals, and when distinguishing between them, the reference numerals are suffixed with Y, M, C, or K. In FIG. 2, only the components of the toner image forming unit 141Y for the Y component are denoted by reference numerals, and the components of the other toner image forming units 141M, 141C, and 141K are not denoted by reference numerals.

[0035] The configuration of the toner image forming unit 141 will be described using the toner image forming unit 141Y as an example. The toner image forming unit 141Y includes an exposure device 1411, a developing device 1412, a photosensitive drum 1413, a charging device 1414, a drum cleaning device 1415, and the like.

[0036] The photosensitive drum 1413 is an organic photosensitive body in which an undercoat layer, a charge generating layer, and a charge transport layer are sequentially laminated on the peripheral surface of a conductive cylindrical body made of aluminum, for example.

[0037] The charging device 1414 uniformly charges the surface of the photoconductive photosensitive drum 1413 to a negative polarity. The exposure device 1411 is configured with, for example, a semiconductor laser, and irradiates the photosensitive drum 1413 with laser light corresponding to an image of each color component, forming an electrostatic latent image of each color component on the surface of the photosensitive drum 1413.

[0038] The developing device 1412 contains developers of each color component, and develops the electrostatic latent image on the surface of the photosensitive drum 1413 by attaching toner of each color component, thereby visualizing the electrostatic latent image and forming a toner image.

[0039] The drum cleaning device 1415 has a drum cleaning blade that comes into sliding contact with the surface of the photosensitive drum 1413. Residual toner remaining on the surface of the photosensitive drum 1413 after the primary transfer is scraped off and removed by the drum cleaning blade.

[0040] The intermediate transfer member 142 includes an intermediate transfer belt 1421, a primary transfer roller 1422, a secondary transfer roller 1423, a driving roller 1424, a driven roller 1425, a belt cleaning device 1426, and the like.

[0041] The intermediate transfer belt 1421 is an endless belt, and is stretched around a drive roller 1424 and a driven roller 1425. The intermediate transfer belt 1421 runs at a constant speed in the direction of arrow A by the rotation of the drive roller 1424. When the primary transfer roller 1422 presses the intermediate transfer belt 1421 against the photosensitive drum 1413, the toner images of each color are primarily transferred onto the intermediate transfer belt 1421 in order to be superimposed on top of each other. Then, when the secondary transfer roller 1423 presses the intermediate transfer belt 1421 against the paper S, the toner images primarily transferred onto the intermediate transfer belt 1421 are secondarily transferred onto the paper S.

[0042] The belt cleaning device 1426 has a belt cleaning blade that slides against the surface of the intermediate transfer belt 1421. Residual toner remaining on the surface of the intermediate transfer belt 1421 after the secondary transfer is scraped off and removed by the belt cleaning blade.

[0043] The fixing unit 160 heats and presses the conveyed paper S in a fixing nip portion, thereby fixing the toner image to the paper S. The fixing unit 160 fixes the toner image to the paper S by passing the paper S through the fixing nip portion formed by pressing a pair of fixing members together, and applying heat from a heat source to the toner image transferred onto the paper S.

[0044] The conveying section 150 includes a paper feed section 151, a conveying mechanism 152, and a paper discharge section 153. The three paper feed trays 151a to 151c that make up the paper feed section 151 store paper S identified based on the basis weight, size, etc. of the paper according to a preset type.

[0045] The sheets S stored in the paper feed trays 151a to 151c are fed one by one from the top, and are transported to the image forming unit 140 by a transport mechanism 152 having a plurality of transport rollers such as a registration roller 152a. Then, in the image forming unit 140, the toner images on the intermediate transfer belt 1421 are secondarily transferred all at once onto one side of the sheets S, and a fixing process is performed in the fixing unit 160. The sheets S with the images formed thereon are discharged outside the image forming apparatus 1 by a paper discharge unit 153 having a paper discharge roller 153a.

[0046] The registration sensor 180 is, for example, a reflective optical sensor incorporating a light-emitting element such as a light-emitting diode and a light-receiving element such as a photodiode. The registration sensor 180 is disposed downstream of the photosensitive drum 1413K in the running direction of the intermediate transfer belt 1421 and upstream of the secondary transfer roller 1423 so as to face the outer circumferential surface of the intermediate transfer belt 1421.

[0047] 5a is a diagram showing an example of the arrangement position of the resist sensor 180 and the formation position of the resist pattern 200. FIG.

[0048] The registration sensor 180 is made up of three registration sensors 180a, 180b, and 180c. The three registration sensors 180a, 180b, and 180c are arranged at predetermined intervals at both ends and the center of the intermediate transfer belt 1421 in the main scanning direction.

[0049] During registration correction, the registration sensor 180 detects the registration pattern 200 for correcting color misregistration formed on the outer peripheral surface of the intermediate transfer belt 1421. Examples of timings for executing registration correction include when the image forming apparatus 1 is powered on, when the number of prints reaches a predetermined number, and when the user selects execution of registration correction via the operation unit 122.

[0050] The resist pattern 200 is made up of a resist pattern 200Y, a resist pattern 200M, a resist pattern 200C, and a resist pattern 200K. Here, the resist pattern 200Y is a resist pattern formed by the toner image forming unit 141Y. The resist pattern 200M is a resist pattern formed by the toner image forming unit 141M. The resist pattern 200C is a resist pattern formed by the toner image forming unit 141C. The resist pattern 200K is a resist pattern formed by the toner image forming unit 141K. When there is no need to distinguish between these, they will be collectively referred to as "resist pattern 200."

[0051] The resist pattern 200 is, for example, five marks M shown in Fig. 5b formed consecutively in the sub-scanning direction of the intermediate transfer belt 1421. Here, the mark M is composed of, for example, a line segment L1 parallel to the main scanning direction of the intermediate transfer belt 1421 and a line segment L2 at a predetermined angle (for example, 45°) with respect to the main scanning direction. Hereinafter, of the marks M, the line segment L1 will be referred to as the "main scanning direction image" and the line segment L2 will be referred to as the "diagonal direction image."

[0052] Here, five marks M are formed for each color registration pattern 200 in order to detect the image formation position of each color registration pattern 200 and correct it with high accuracy. That is, five calculations of color misregistration amounts are performed using the five marks M of each color registration pattern 200. Specifically, the first calculation of color misregistration amount is performed using the top mark M of each color registration pattern 200 as a reference. The second calculation of color misregistration amount is performed using the second mark M of each color registration pattern 200, 201, 202, and 203 as a reference. The third calculation of color misregistration amount is performed using the third mark M of each color registration pattern 200 as a reference. The fourth calculation of color misregistration amount is performed using the fourth mark M of each color registration pattern 200 as a reference. The fifth calculation of color misregistration amount is performed using the fifth mark M of each color registration pattern 200 as a reference.

[0053] The reason why three registration patterns 200 are formed in each of the main scanning directions of the intermediate transfer belt 1421 is to measure the amount of color misregistration in each color misregistration mode, that is, to perform registration correction for all of the main scanning direction color misregistration, sub-scanning direction color misregistration, overall magnification color misregistration, partial magnification color misregistration, skew, and bow color misregistration.

[0054] [Registration correction unit 11] Next, the function of the control unit 10 as the registration correction unit 11 will be described.

[0055] When performing registration correction to correct the image formation conditions of the toner image forming units 141Y, 141M, 141C, and 141K, the control unit 10 (registration correction unit 11) controls the toner image forming units 141Y, 141M, 141C, and 141K to form registration patterns 200 on the outer peripheral surface of the intermediate transfer belt 1421. Then, the control unit 10 calculates the amount of color misregistration of the C, M, and Y colors relative to the K color based on the detection result of the registration pattern 200 by the registration sensor 180. The control unit 10 records the calculated amount of color misregistration in the storage unit 20 (see FIG. 7).

[0056] FIG. 6 is a diagram showing an example of a method for measuring the amount of color misregistration.

[0057] 6, 200Ka represents the left-side resist pattern of the three K-color resist patterns 200K formed on the intermediate transfer belt 1421 along the main scanning direction. 200Kb represents the middle-side resist pattern of the three K-color resist patterns 200K formed on the intermediate transfer belt 1421 along the main scanning direction. 200Kc represents the right-side resist pattern of the three K-color resist patterns 200K formed on the intermediate transfer belt 1421 along the main scanning direction.

[0058] 6, 200Ca represents the left-side resist pattern of the three C-color resist patterns 200C formed on the intermediate transfer belt 1421 along the main scanning direction. 200Cb represents the middle-side resist pattern of the three C-color resist patterns 200K formed on the intermediate transfer belt 1421 along the main scanning direction. 200Cc represents the right-side resist pattern of the three C-color resist patterns 200C formed on the intermediate transfer belt 1421 along the main scanning direction.

[0059] For example, the control unit 10 determines the time T1 from when the main scanning direction image 200Kaa of the registration pattern 200Ka is detected by the registration sensor 180a until the main scanning direction image 200Caa of the registration pattern 200Ca is detected by the registration sensor 180a. Then, the control unit 10 calculates the distance between the main scanning direction image 200aa and the main scanning direction image 200Caa (hereinafter referred to as the "measured distance") based on the time T1 and the running speed of the intermediate transfer belt 1421. By calculating the difference between this measured distance and the distance (design value) between the main scanning direction image 200Kaa and the main scanning direction image 200Caa, the amount of color misregistration in the sub-scanning direction between the K image and the C image can be calculated (see FIG. 1b).

[0060] The control unit 10 also determines the time T2 between when the registration sensor 180a detects the diagonal image 200Kab of the K registration pattern 200Ka and when the registration sensor 180a detects the diagonal image 200Cab of the C registration pattern 200Ca. The control unit 10 then determines the positional relationship between the K and C images in the main scanning direction based on the relationship between time T1 and time T2. For example, if T1=T2, there is no color misalignment in the main scanning direction. If T2 is shorter than T1, as indicated by Ta in the figure, it can be seen that the C image is misaligned to the left of the K image, as indicated by the dashed line 214 in the figure. Therefore, the amount of color misalignment in the main scanning direction between the K and C images can be determined from the time difference between T1 and Ta (see FIG. 1a).

[0061] Furthermore, the amount of skew of the K-color image can be detected from the difference (T3) between the time when the registration sensor 180a detects the main scanning direction image 200Kaa and the time when the registration sensor 180c detects the main scanning direction image 200Kca (see FIG. 1e). Furthermore, the amount of skew of the C-color image can be detected from the difference between the time when the registration sensor 180a detects the main scanning direction image 200Caa and the time when the registration sensor 180c detects the main scanning direction image 200Cca. Therefore, the amount of skew between the K-color image and the C-color image can be calculated by calculating the difference between the amount of skew of the K-color image and the amount of skew of the C-color image.

[0062] Furthermore, the bow amount of the K-color image can be calculated from the difference (T4) between the time when the registration sensor 180b detects the main scanning direction image 200Kba and the time at the position of the registration sensor 180b calculated from the skew amount (see FIG. 1f). The bow amount of the C-color image can be calculated from the difference between the time when the registration sensor 180b detects the main scanning direction image 200Cba and the time at the position of the registration sensor 180b calculated from the skew amount. Therefore, the bow amount between the K-color image and the C-color image can be calculated by calculating the difference between the bow amount of the K-color image and the bow amount of the C-color image.

[0063] Furthermore, the main scanning direction color shift of the resist patterns 200Kb and 200Kc compared to the ideal image formation position of the K resist pattern 200K can be used to calculate the overall magnification color shift amount for K (see FIG. 1c). Similarly, the main scanning direction color shift of the resist patterns 200Cb and 200Cc compared to the ideal image formation position of the C resist pattern 200C can be used to calculate the overall magnification color shift amount for C. Therefore, the overall magnification color shift amount between the K image and the C image can be calculated by calculating the difference between the overall magnification color shift amount of the K image and the overall magnification color shift amount of the C image.

[0064] Furthermore, the amount of partial magnification color shift for K can be calculated based on the color shift in the main scanning direction for the resist patterns 200Ka, 200Kb, and 200Kc compared to the ideal image formation position for the K resist pattern 200K (see FIG. 1d). The amount of partial magnification color shift for C can be calculated based on the color shift in the main scanning direction for the resist patterns 200Ca, 200Cb, and 200Cc compared to the ideal image formation position for the C resist pattern 200C. Therefore, the amount of partial magnification color shift between the K image and the C image can be calculated by calculating the difference between the amount of partial magnification color shift for the K image and the amount of partial magnification color shift for the C image.

[0065] The control unit 10 can also calculate the main scanning direction color shift amount, sub-scanning direction color shift amount, overall magnification color shift amount, partial magnification color shift amount, skew amount, and bow amount for M color and Y color other than C color in the same way.

[0066] Fig. 7 is a diagram showing an example of measurement data D1 of the amount of color misregistration stored in storage unit 20. The measurement data D1 shown in Fig. 7 has, for example, the amount of color misregistration calculated for each color misregistration mode (the numerical values ​​in Fig. 7 are in [µm] units). That is, the measurement data D1 shown in Fig. 7 stores the amount of color misregistration in the main scanning direction, the amount of color misregistration in the sub-scanning direction, the amount of total magnification color misregistration, the amount of partial magnification color misregistration, the amount of skew, and the amount of bow for each of C color, M color, and Y color relative to K color.

[0067] In this embodiment, the control unit 10 measures the color misregistration amount five times for each of the Y color, M color, and C color, for example, using five marks M of each of the registration patterns 200. That is, when performing registration correction, the control unit 10 obtains five pieces of measurement data D1 as shown in Fig. 7. Note that Fig. 7 shows only one measurement result, but the memory unit 20 sequentially stores, for example, the measurement data D1 obtained during registration correction in chronological order.

[0068] After measuring the amount of color misregistration, the control unit 10 corrects the image forming conditions of the toner image forming unit 141 for each color in accordance with the measured amount of color misregistration so that the color misregistration of the C, M, and Y colors relative to the K color is eliminated.

[0069] For example, when correcting color misregistration in the main scanning direction, the control unit 10 adjusts the write start timing in the main scanning direction in the toner image forming unit 141 for each color based on the amount of color misregistration in the main scanning direction for C, M, and Y relative to K. This aligns the write positions of K with those of C, M, and Y. Alternatively, the control unit 10 performs correction processing on the image data of C, M, Y, and K in pixel units to align the write positions of K with those of C, M, and Y.

[0070] Furthermore, when correcting color misregistration in the sub-scanning direction, the control unit 10 adjusts the write start timing in the sub-scanning direction in the toner image forming unit 141 for each color based on the amount of color misregistration in the sub-scanning direction for C, M, and Y relative to K, to align the write positions of K with those of C, M, and Y. Alternatively, the control unit 10 performs correction processing in the sub-scanning direction on the image data of C, M, Y, and K, to align the write positions of K with those of C, M, and Y.

[0071] Furthermore, when correcting skew, the control unit 10 adjusts the tilt of the exposure device 1411 of the toner image forming unit 141 for each color based on the amount of skew of the C, M, and Y colors relative to the K color, thereby adjusting the degree of tilt of the scanning direction of the laser light irradiated from the exposure device 1411. Alternatively, the control unit 10 performs correction processing on the image data of the C, M, Y, and K colors on a pixel-by-pixel basis so as to eliminate the amount of skew of the C, M, and Y colors relative to the K color.

[0072] Furthermore, when correcting the bow, the control unit 10 adjusts the curved shape of the mirror (various mirrors such as polygon mirrors) provided in the exposure device 1411 of the toner image forming unit 141 for each color based on the bow amounts of the C, M, and Y colors relative to the K color. Alternatively, the control unit 10 performs correction processing on a pixel-by-pixel basis for the image data of the C, M, Y, and K colors so that the bow amounts of the C, M, and Y colors relative to the K color are eliminated.

[0073] Furthermore, when correcting the overall magnification color misregistration, the control unit 10 changes the rotation speed of the polygon mirror provided in the exposure device 1411 of the toner image forming unit 141 for each color based on the overall magnification color misregistration amount of the C color, M color, and Y color relative to the K color. Alternatively, the control unit 10 performs correction processing on a pixel-by-pixel basis on the image data of the C color, M color, Y color, and K color so that the overall magnification color misregistration amount of the C color, M color, and Y color relative to the K color is eliminated.

[0074] Furthermore, when correcting partial magnification color misregistration, the control unit 10 changes the inclination of the mirrors (various mirrors such as polygon mirrors) provided in the exposure devices 1411 of the toner image forming units 141 for each color based on the amount of partial magnification color misregistration of C, M, and Y colors relative to K. Alternatively, the control unit 10 performs correction processing on the image data of C, M, Y, and K colors in units of pixels so that the amount of partial magnification color misregistration of C, M, and Y colors relative to K is eliminated.

[0075] [Information presentation section 12] Next, the function of the information presentation unit 12 of the control unit 10 will be described.

[0076] As described above, in the image forming apparatus 1 according to the conventional technology, when an error occurs in the operation of the registration correction unit 11, the worker is unable to recognize the target of adjustment work. Therefore, when performing such adjustment work, the worker is forced to comprehensively inspect each part in the image forming apparatus and adjust the parts.

[0077] Therefore, in the image forming apparatus 1 according to this embodiment, when an error is detected during registration correction, the control unit 10 uses the function of the information presenting unit 12 to present work support information to the worker.

[0078] At this time, the control unit 10 (information presentation unit 12) creates work support information by referring to measurement data D1 of the amount of color shift for each color stored in the memory unit 20. When an error occurs in the registration correction unit 11, an error flag associated with the cause of the error (described later with reference to FIGS. 11 and 12) is attached to the measurement data D1 to be corrected in the memory unit 20. The control unit 10 is then able to identify the color in which the error occurred, the mode of color shift in which the error occurred, and the cause of the error from the measurement data D1 to which the error flag has been attached.

[0079] The control unit 10 (information presentation unit 12) according to this embodiment (1) Error status list (2) Belt speed deviation suspected (3) Error-related parts (4) Work history It is configured to be able to present the following four types of work support information.

[0080] The control unit 10 according to this embodiment outputs and displays this work support information on the screen of the display unit 120. Here, for example, the work support information is configured to be displayed by appropriately selecting it from a main menu displayed on the screen of the display unit 120.

[0081] However, when presenting the work support information, the control unit 10 may display all of the work support information (1) to (4) on one screen. Furthermore, when presenting the work support information, the control unit 10 may output the information to a printer or display it on an external computer.

[0082] <(1) Error status list display> First, the error status list display function of the control unit 10 will be described.

[0083] The error status list display function is a function that displays a list of the normal / abnormal status of each color in a manner that makes it possible to identify the color in which the error occurred, the color deviation mode in which the error occurred, and the cause of the error.

[0084] Fig. 8 is a diagram showing a display example 1 of the error status list display, Fig. 9 is a diagram showing a display example 2 of the error status list display, and Fig. 10 is a diagram showing a display example 3 of the error status list display.

[0085] There are typically two reasons why the registration correction unit 11 indicates an error: (a) the amount of color misregistration is outside a predetermined correctable range, or (b) the amount of color misregistration fluctuates with each measurement.

[0086] The vertical axis items "Yellow correction range," "Magenta correction range," and "Cyan correction range" in Figures 8 to 10 are items that suggest that an error has occurred because "(a) the amount of color misregistration deviates from the specified correctable range." On the other hand, the vertical axis items "Yellow stable," "Magenta stable," and "Cyan stable" in Figures 8 to 10 are items that suggest that an error has occurred because "(b) the amount of color misregistration shows behavior that fluctuates with each measurement."

[0087] In this embodiment, the color shift amounts of Y, M, and C are calculated based on K, so the normal / abnormal status of each color is displayed as an abnormality for Y, M, and C.

[0088] Fig. 11 shows an example of a situation where the amount of color misregistration is unstable. Fig. 11A shows the state of color misregistration identified in the first measurement. Fig. 11B shows the state of color misregistration identified in the second measurement.

[0089] Figure 11 shows that the colors K and C should appear at the same position in the conveying direction, but in the first measurement, the color C appeared at a position behind the color K in the conveying direction, and in the second measurement, the color C appeared at a position ahead of the color K in the conveying direction.

[0090] Since color misregistration is usually caused by deviations in the positional accuracy of the optical system and deterioration of components over time, changes in the amount of color misregistration in such a short period of time are often caused by mechanical looseness of some part, etc. Therefore, when the control unit 10 (resist correction unit 11) detects the resist patterns 200 for each of the Y, M, and C colors, if the amount of color misregistration shows behavior in which it fluctuates greatly each time a measurement is performed, an error is output.

[0091] In this embodiment, for example, during registration correction, the control unit 10 measures the color misregistration amount five times for each of the Y color, M color, and C color using the five marks M of each of the registration patterns 200. That is, the control unit 10 obtains five sets of measurement data D1 (see FIG. 7) every time registration correction is performed.

[0092] If any one of the five color misregistration measurement results is different from the other four color misregistration measurement results by a predetermined threshold (e.g., 63 μm) or more, the control unit 10 determines that the color misregistration amount is unstable.The control unit 10 then outputs an error, interrupts the registration correction operation, and stops the operation of the image forming apparatus 1.

[0093] Fig. 12 is a diagram showing an example of a situation in which the amount of color misregistration exceeds the correctable range. In Fig. 12, the K color and the C color should appear at the same position in the transport direction, but in the measurement results, the C color appears at a position behind the K color in the transport direction, and the amount of color misregistration exceeds the correctable range.

[0094] The control unit 10 in this embodiment sets the upper limit of the correction range (e.g., 1000 μm) on the delayed position side in the conveying direction based on the K color as the correction range, and the lower limit of the correction range (e.g., 1000 μm) on the advanced position side in the conveying direction based on the K color as the correction range.

[0095] The control unit 10 outputs an error if any of the color misregistration amounts for Y, M, and C exceeds the correctable range. Furthermore, if the color misregistration amount exceeds the correctable range even once among the five color misregistration amount measurement results, the control unit 10 concludes that the color misregistration amount exceeds the correctable range. The control unit 10 then outputs an error, interrupts the registration correction operation, and stops the operation of the image forming apparatus 1.

[0096] The horizontal axis items in FIGS. 8 to 10, "main scanning," "overall horizontal magnification," "partial horizontal magnification," "sub-scanning," "skew," and "bow," are items that suggest the color shift conditions of each of the six types of color shift modes.

[0097] As described above, when the control unit 10 detects the resist pattern 200, it classifies the color misregistration mode into six types: "main scanning," "whole horizontal magnification," "partial horizontal magnification," "sub-scanning," "skew," and "bow," and calculates the amount of color misregistration for each of the six types of color misregistration mode. Then, the control unit 10 corrects the amount of color misregistration for each of the six types of color misregistration mode.

[0098] During registration correction, the control unit 10 outputs an error if, in any of the six types of color misregistration modes, a situation occurs in which "(a) the amount of color misregistration is outside a predetermined correctable range" or "(b) the amount of color misregistration shows a behavior that fluctuates with each measurement." Note that, for each of the six types of color misregistration modes, the threshold value of the amount of color misregistration at which an error is output may be set to the same value or may be set to a different value as appropriate.

[0099] In this way, when an error occurs during registration correction, the control unit 10 can see that the situation is quite complicated. In particular, since multiple of these elements may simultaneously output an error (see FIG. 18), it is essential that the operator be able to grasp the overall situation in which the error occurred in order to enable the operator to efficiently perform adjustment work on the image forming apparatus 1.

[0100] 8, 9 and 10 are designed from this perspective.

[0101] Figure 8 shows the normal / abnormal status of error causes (a) and (b) for each of the six types of color shift conditions, indicated by OK / NG information when the amount of color shift is judged based on a threshold value. Here, "OK" indicates that the amount of color shift is below the threshold value and is in a normal state. "NG" indicates that the amount of color shift exceeds the threshold value and is in an abnormal state.

[0102] FIG. 9 also shows how the level information for the amount of color misregistration for each of the six types of color misregistration indicates whether the error causes (a) and (b) are normal or abnormal, using level information when the amount of color misregistration is classified into levels. Here, "Area 1" indicates a normal state where the amount of color misregistration is equal to or less than the first threshold. "Area 2" indicates a state where the amount of color misregistration is equal to or greater than the first threshold and equal to or less than the second threshold (where the second threshold is greater than the first threshold), indicating a state where an abnormality may have occurred. "Area 3" indicates a state where the amount of color misregistration is equal to or greater than the second threshold and equal to or less than the third threshold (where the third threshold is greater than the second threshold), indicating a state where an abnormality has clearly occurred. In this case, multiple thresholds are appropriately set according to the level of the abnormal state.

[0103] 10 shows how the error causes (a) and (b) are indicated as normal or abnormal by numerical information on the amount of color misalignment for each of the six types of color misalignment. Here, items indicating an abnormal state are indicated by numerical information on the amount of color misalignment, and items indicating a normal state are indicated by the display of "OK."

[0104] The control unit 10 may display the normal / abnormal status of each color in combination with OK / NG information, level information, and numerical information as shown in FIGS.

[0105] <(2) Belt speed deviation suspected> Next, the function of the control unit 10 to display a suspected belt speed deviation will be described.

[0106] The belt speed deviation suspected display function by the control unit 10 is a function that indicates whether or not there is a belt speed deviation suspected of the intermediate transfer belt 1421 when an error occurs during registration correction.

[0107] The control unit 10 determines whether the amount of color misregistration in the sub-scanning direction for each color (C, M, Y) tends to be proportional to the inter-drum distance between the photosensitive drum 1413 for the reference color (K) and the photosensitive drum 1413 for each color (C, M, Y). If there is such a tendency, the control unit 10 displays a message indicating that there is a possibility of a belt speed deviation of the intermediate transfer belt 1421.

[0108] Fig. 13 is a diagram showing an example of a situation in which a belt speed deviation occurs in the intermediate transfer belt 1421. Fig. 14 is a diagram for explaining the mechanism by which the belt speed deviation occurs in the intermediate transfer belt 1421. Fig. 15 is a diagram showing an example of an alert display for the belt speed deviation of the intermediate transfer belt 1421.

[0109] As mentioned above, the reasons why the registration correction unit 11 indicates an error are the occurrence of the following situations: "(a) the amount of color misregistration is outside the predetermined correctable range" or "(b) the amount of color misregistration shows a behavior that fluctuates with each measurement." Belt speed deviation of the intermediate transfer belt 1421 is closely related to "(a) the amount of color misregistration is outside the predetermined correctable range." This is because when there is a belt speed deviation of the intermediate transfer belt 1421, the amount of color misregistration in C, M, or Y (especially Y) tends to become significantly large.

[0110] Therefore, the control unit 10 determines whether or not such a belt speed deviation has occurred based on the amount of color deviation in the sub-scanning direction for each color.

[0111] The mechanism by which belt speed deviation occurs is as shown in Figure 14. When the belt speed is slow, for example, if exposure is performed in the order of YMCK with a theoretical difference of 0.27 seconds, the Y image has not yet reached the transfer position for the M image by the time the M image is transferred to the intermediate transfer belt 1421. Similarly, the C image is transferred to the intermediate transfer belt 1421 before the M image also reaches the transfer position for the C image. As a result, color deviation occurs at equal intervals on the intermediate transfer belt 1421 in the order of K → C → M → Y.

[0112] Therefore, it is possible to determine whether a belt speed deviation is occurring by checking whether the amount of color deviation in the sub-scanning direction for each color tends to be proportional to the inter-drum distance between the photosensitive drum 1413 for the reference color (K color) and the photosensitive drum 1413 for each color.

[0113] However, because the actual amount of color misregistration is composed of a belt speed deviation component and a component caused by mechanical assembly errors, the amount of color misregistration in the sub-scanning direction for each color is not completely proportional to the inter-drum distance. However, the proportion of the actual amount of color misregistration caused by belt speed deviation is generally quite large; for example, the ratio of the belt speed deviation component to the component caused by mechanical assembly errors is about 10:1. Therefore, the above method makes it possible to determine with sufficient accuracy whether or not belt speed deviation has occurred.

[0114] Furthermore, when displaying the fact that there is a suspected belt speed deviation, the control unit 10 preferably estimates the amount of belt speed deviation of the intermediate transfer belt 1421 and also displays the amount of belt speed deviation (see FIG. 15). This allows the worker to modify the control parameters of the drive motor that drives the intermediate transfer belt 1421 and adjust the assembly state of the intermediate transfer belt 1421 when performing adjustment work on the intermediate transfer belt 1421.

[0115] As described above, it is possible to estimate the amount of belt speed deviation based on the amount of color misregistration proportional to the inter-drum delay. Specifically, in this embodiment, the amounts of color misregistration for Y, M, and C are calculated based on K, so the proportion of the actual color misregistration attributable to belt speed deviation is Y > M > C. For example, if the inter-drum distance is 180 mm and the color misregistration amounts are 1.4 mm for Y, 1.1 mm for M, and 0.5 mm for C, it can be estimated from the inter-drum color misregistration amounts that a color misregistration of (1.4 - 0.5) / 2 = 0.45 mm has occurred per drum. In other words, in this case, it can be estimated that a belt speed deviation of 0.45 / 180 * 100 = 0.25% has occurred.

[0116] When estimating the amount of belt speed deviation, attention may be paid to the difference in the amount of color deviation between Y and M, and the difference in the amount of color deviation between M and C. That is, considering that the distance between each drum is LL [mm], the amount of color deviation resulting from belt speed deviation can be expressed as 3 × LL [mm] for Y, 2 × LL [mm] for M, and 1 × LL [mm] for C. Therefore, the difference between the amount of color deviation detected for Y and the amount of color deviation detected for M is theoretically LL [mm]. Furthermore, the difference between the amount of color deviation detected for M and the amount of color deviation detected for C is theoretically LL [mm]. Therefore, the average of these differences may be used to estimate the amount of color deviation resulting from belt speed deviation.

[0117] <(3) Error related parts display> Next, the error-related component display function of the control unit 10 will be described.

[0118] The error-related component display function by the control unit 10 is a function that, when the registration correction unit 11 indicates an error, identifies the component in the image forming apparatus 1 that is related to the cause of the error and displays information about that component. When dealing with an error, it is useful for an operator to be able to easily identify the component in the image forming apparatus 1 that is related to the error. The error-related component display function is a function that meets this need.

[0119] For example, the control unit 10 first identifies the color in which the error occurred, the mode of color shift in which the error occurred, and the cause of the error from the measurement data D1 stored in the storage unit 20. Then, the control unit 10 identifies the related parts corresponding to the color in which the error occurred, the mode of color shift in which the error occurred, and the cause of the error from the related parts data D2 stored in the storage unit 20.

[0120] Fig. 16 is a diagram showing an example of the related part data D2 stored in the storage unit 20. Fig. 17 is a diagram showing a display example of the error-related part display.

[0121] In the related parts data D2 according to this embodiment, for example, each part related to registration correction is stored in advance in association with the color in which an error occurs when a registration correction error occurs, the type of color shift that caused the error, and the cause of the error. Here, the color shift type that caused the error is, for example, of six types, as described above: "main scan," "overall horizontal magnification," "partial horizontal magnification," "sub scan," "skew," and "bow." Also, the cause of the error is, for example, of two types, as described above: "the amount of color shift deviates from the predetermined correctable range," or "the amount of color shift shows a behavior that fluctuates with each measurement."

[0122] 17, the control unit 10 displays, for example, component information related to an error in the image forming apparatus 1. This allows the worker to easily identify the component related to the error in the image forming apparatus 1 when dealing with the error.

[0123] However, in reality, when the registration correction unit 11 indicates an error, it is not possible to identify the cause only in the part related to the color in which the error occurred. This is because, for example, even if all of the Y, M, and C color parts are normal, if there is an abnormality in the K color, which is the reference color, the registration correction unit 11 will recognize the abnormality as being in the Y, M, or C color.

[0124] From this perspective, it is desirable that the control unit 10, in some cases, present all of the parts that require adjustment that are predicted based on the error situation.

[0125] Fig. 18 is a diagram showing an example of a location that is expected to require adjustment based on an error state during registration correction, and Fig. 19 is a diagram showing a modified example of a display example of an error-related component display.

[0126] 18 shows an example of five patterns of parts that require adjustment, which are predicted based on the error state of the registration correction unit 11. Specifically, they are as follows. (1) The error occurs in only one color, and the error occurs due to unstable color misregistration. ⇒It is necessary to consider the assembly defect of the relevant color. (2) The number of colors for which an error occurs is two or more, and the cause of the error is unstable color misregistration. ⇒It is necessary to examine assembly defects of the relevant color, parts common to all colors, and K color. (3) The error occurs in only one color, and the cause of the error is a deviation from the color misregistration correction range. ⇒It is necessary to consider the assembly defect of the relevant color. (4) The number of colors for which an error has occurred is two or more, and the cause of the error is a deviation from the color misregistration correction range. ⇒It is necessary to examine assembly defects of the relevant color, parts common to all colors, and K color. (5) The error occurs for one or more colors, and the cause of the error is a deviation from the color misregistration correction range, and the color misregistration amount is proportional to the drum distance from the K color. ⇒ Belt speed deviation must be considered

[0127] In FIG. 19, the control unit 10 identifies the areas requiring adjustment based on the error situation, and displays all of the areas requiring adjustment (the relevant color, or the common parts for all colors, or the defective assembly of the K color) in addition to the related parts identified from the related parts data D2.

[0128] At this time, it is desirable for the control unit 10 to determine whether or not the K-colored related parts are the cause of the error so that the operator can further narrow down the location of the error. This allows the control unit 10 to switch whether or not to display the K-colored related parts as error-related parts based on the determination result.

[0129] FIG. 20 is a diagram showing an example of a flowchart for determining whether or not a related part of color K is the cause of the error.

[0130] In step S11, the control unit 10 determines whether the number of error occurrence colors is two or more. If the number of error occurrence colors is two or more (step S11: YES), the control unit 10 proceeds to step S12. On the other hand, if the number of error occurrence colors is not two or more (step S11: NO), the control unit 10 proceeds to step S15.

[0131] In step S12, the control unit 10 determines whether the error color shift patterns of the two or more error colors are the same. If the error color shift patterns of the two or more error colors are the same (step S12: YES), the control unit 10 proceeds to step S13. On the other hand, if the error color shift patterns of the two or more error colors are not the same (step S12: NO), the control unit 10 proceeds to step S15.

[0132] In step S13, the control unit 10 calculates the difference in the amount of color shift between two or more error-causing colors and determines whether the amount of color shift between them is stable. If the amount of color shift between them is stable (step S13: YES), the control unit 10 proceeds to step S14. On the other hand, if the amount of color shift between them is not stable (step S13: NO), the control unit 10 proceeds to step S15.

[0133] In step S14, the control unit 10 determines that there is a possibility of an abnormality in the part related to color K, and displays the information. In this case, as shown in Fig. 19, the control unit 10 displays both the part related to color K and the part related to the color where the error occurred as parts requiring adjustment.

[0134] In step S15, the control unit 10 determines that the components related to the color K are unrelated and displays this information. That is, in this case, the control unit 10 treats only the components related to the color in which the error occurred as components related to the error occurrence.

[0135] <(4) Work history display> Next, the work history display function of the control unit 10 will be described.

[0136] The work history display function of the control unit 10 is a function that, when the resist correction unit 11 indicates an error, identifies the work history related to the cause of the error from the work history performed in the past by the worker, and displays and outputs information about the work history.

[0137] Errors often occur due to work that an operator performs on the image forming apparatus 1. Examples of such work include hardware-related measures (e.g., replacing parts, replacing a control board, or plugging / unplugging a control board connector) and software-related measures (e.g., changing correction values: particularly belt speed correction, or updating control firmware).

[0138] From this perspective, it would be useful for the worker if, when an error is detected by the registration correction unit 11, the worker could identify the work history related to the cause of the error from among the work histories. The work history display function is a function that meets this need.

[0139] Specifically, the control unit 10 first identifies the color in which the error occurred, the mode of color shift in which the error occurred, and the cause of the error from the measurement data D1 stored in the storage unit 20. Then, the control unit 10 identifies the work history related to the color in which the error occurred, the mode of color shift in which the error occurred, and the cause of the error from the work history data D3 stored in the storage unit 20, and displays the results.

[0140] Fig. 21 is a diagram showing an example of work history data D3 stored in the storage unit 20. Fig. 22 is a diagram showing a display example of the work history display.

[0141] The work history data D3 is data that stores, for example, the details of work performed by an operator on the image forming apparatus 1 together with the date and time of the work. Such data is created, for example, by the operator leaving a history for each work. In addition, work history data may be created automatically for software work (for example, correction value changes, particularly belt speed correction, or control firmware updates). Alternatively, the work history data may be created by referring to data recorded outside the apparatus (for example, work reports).

[0142] The work history data D3 stores the history of work related to at least one of, for example, disassembling the image forming device 1, replacing parts, updating the control software, changing the control parameter settings related to color misalignment correction, replacing the control board, inserting and removing the control board connector, and replacing the cable bundle.

[0143] Such work is basically predetermined, and therefore, for example, it is possible to associate it with the influence on the resist correction in advance.

[0144] Therefore, the control unit 10 can refer to the error color, the error color shift pattern, and the cause of the error in the measurement data D1 currently marked with an error flag, and identify the work history corresponding to these from the work history data D3.

[0145] 22 shows an example in which work history data D3 is used to identify work history that is highly relevant to the error and display it preferentially in the work list. The control unit 10 may, for example, highlight the work history that is highly relevant to the error or display it at the top of the work list.

[0146] In this case, it is desirable to list the work histories stored in the work history data D3 in order of the date and time closest to the error occurrence date and time, because basically, the most recent work is likely to have caused the registration correction error.

[0147] However, if the registration correction has been completed successfully, the control unit 10 may delete the work history data D3.

[0148] Since errors caused by assembly errors can occur multiple times on a single unit, errors that have been resolved in the past are not related to errors that are occurring now. Therefore, it is not desirable to display estimated causes that have already been resolved when referencing past history.

[0149] Therefore, it is desirable that the control unit 10, for example, after interrupting the correction process due to an error, re-executes the correction process based on a user command, and if the error has been resolved, deletes the work history data D3 stored in the memory unit 20.

[0150] [effect] As described above, the image forming apparatus according to this embodiment a registration correction unit that detects the state of the registration pattern of each color formed on the intermediate transfer belt by a registration sensor and corrects the amount of color misregistration of each color based on the detection result; a first storage unit for storing measurement data of the color misregistration amount for each color measured by the registration correction unit; an information presenting unit that presents work support information to a worker based on the measurement data stored in the first storage unit when the registration correction unit indicates an error; Equipped with.

[0151] This allows the operator to narrow down the location of the error within the image forming device when adjusting the image forming device to address a registration correction error. In other words, this allows the operator to efficiently adjust the image forming device. This also makes it possible to prevent the operator from overlooking a part of the image forming device that should be adjusted when an error occurs.

[0152] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Industrial Applicability]

[0153] According to the image forming apparatus of the present invention, it is possible to reduce the workload of the operator in making adjustments when an error occurs in the registration correction function. [Explanation of symbols]

[0154] 1. Image forming device 10 Control Unit 11. Registration Correction Unit 12 Information presentation section 20 Memory section 110 Receiving part 111 Automatic document feeder 112 Image scanning device 120 Operation display section 130 Image processing section 140 Image forming unit 142 Intermediate transfer body 150 Conveyor 151 Paper feed section 152 Transport mechanism 153 Paper output section 160 Fixing unit 170 Communications Department 180 Resist Sensor 200 Resist Pattern D1 Measurement data D2 Related parts data D3 Work history data

Claims

1. An image forming apparatus having a photosensitive drum for each color, and forming a color image by superimposing images formed on the photosensitive drums of each color on an intermediate transfer belt, a registration correction unit that detects the state of the registration patterns of each color formed on the intermediate transfer belt by a registration sensor and corrects the amount of color misregistration of each color based on the detection result; a first storage unit for storing measurement data of the color misregistration amount for each color measured by the registration correction unit; an information presenting unit that presents work support information to a worker based on the measurement data stored in the first storage unit when the registration correction unit indicates an error; An image forming apparatus comprising:

2. The information presenting unit displays, as the work support information, a list of the normal / abnormal status of each color, the color in which the error occurred, the color deviation state in which the error occurred, and the cause of the error in an identifiable manner. The image forming apparatus according to claim 1 .

3. The error-causing color shift mode includes at least one of color shift in the main scanning direction, color shift in the sub-scanning direction, color shift due to an overall magnification error, color shift due to a partial magnification error, color shift due to an image tilt, and color shift due to an image curvature. The image forming apparatus according to claim 2 .

4. The cause of the error includes either a state in which the amount of color misregistration is outside a predetermined correctable range, or a state in which the amount of color misregistration exhibits a behavior that fluctuates every time measurement is performed. The image forming apparatus according to claim 2 .

5. The information presentation unit displays the normal / abnormal status of each color as OK / NG information when the amount of color misregistration is judged based on a threshold value, level information when the amount of color misregistration is classified into levels, and / or numerical information of the amount of color misregistration. The image forming apparatus according to claim 2 .

6. The information presenting unit determines whether or not the amount of color misregistration in the sub-scanning direction for each color specified from the measurement data tends to be proportional to the inter-drum distance between the photosensitive drum for a reference color and the photosensitive drum for each color, and if the tendency is found, displays, as the work support information, that there is a suspicion of a belt speed misregistration of the intermediate transfer belt. The image forming apparatus according to claim 1 .

7. When the belt speed deviation is suspected, the information presenting unit estimates the belt speed deviation amount of the intermediate transfer belt based on the color deviation amount in the sub-scanning direction of each color, and displays the estimated amount as the work support information. The image forming apparatus according to claim 6 .

8. a second storage unit that stores information about each component in the image forming apparatus; The information presenting unit identifies a part in the image forming apparatus related to the error from the second storage unit based on the error-occurring color, the error-occurring color shift mode, and the cause of the error identified from the measurement data, and displays information about the part as the work support information. The image forming apparatus according to claim 1 .

9. When there are two or more error-occurring colors and the two or more error-occurring colors show the same error-occurring color shift mode, the information presenting unit displays, as the work support information, a message that an abnormality may have occurred in a component related to a reference color that is used as a reference when calculating the color shift amount of each color. The image forming apparatus according to claim 8 .

10. When there are two or more error-occurring colors, the two or more error-occurring colors show the same error-occurring color shift mode, and the color shift amount between the two or more error-occurring colors is stable, the information presenting unit displays, as the work support information, that there is a possibility that an abnormality has occurred in a component related to a reference color that is used as a reference when calculating the color shift amount of each color. The image forming apparatus according to claim 8 .

11. a third storage unit that stores a history of work performed on the image forming apparatus; The information presenting unit extracts the work history for the part related to the error from the work histories stored in the third storage unit based on the error-occurring color, the error-occurring color shift mode, and the cause of the error identified from the measurement data, and displays the work support information. The image forming apparatus according to claim 1 .

12. The work history includes at least one of work related to disassembly of the image forming apparatus, part replacement, control software update, control parameter setting change related to color misregistration correction, control board replacement, control board connector insertion / removal, and cable replacement. The image forming apparatus according to claim 11.

13. After the registration correction unit has interrupted the correction process due to the error, the registration correction unit re-executes the correction process based on a user command, and if the error has been resolved, deletes the work history stored in the third storage unit. The image forming apparatus according to claim 11.

Images