Method for diagnosing abnormalities in an image forming apparatus

Abstract

To provide a chart that can increase the degree of freedom in selecting the type of reading means.SOLUTION: A chart according to an aspect of the present invention includes a plurality of area images, and each of the plurality of area images includes a diagram indicating positional information on the area image in the chart.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] Method for diagnosing abnormalities in an image forming apparatus Regarding. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in order to diagnose abnormalities in images printed by an image forming apparatus, a technique is known in which the image forming apparatus to be diagnosed uses a chart in which an area image such as a test image is formed on a recording medium.

[0003] In addition, in order to reduce the number of charts, a configuration has been disclosed in which image feature information of image data included in an area designated by a user is obtained from image data obtained by reading an image formed by an image forming means, and the cause of the occurrence of an abnormal image is analyzed using the reading results of a chart selected and formed using the image feature information (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configuration of Patent Document 1 leaves room for improvement in the degree of freedom in selecting the type of reading means for reading the chart.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a chart that allows for greater freedom in selecting the type of reading means. [Means for solving the problem]

[0006] In accordance with one aspect of the present invention, there is provided a method for diagnosing an abnormality in an image forming apparatus, the image forming apparatus diagnosing an abnormality in the image forming apparatus based on a read image of a chart formed by the image forming apparatus, the chart including a plurality of area images, each of the plurality of area images including position information of the area image within the chart, and predetermined concentration information and the region image includes a correction pattern used to correct the density of the region image, and the correction unit Read by the reader Density of the correction pattern in the read image Obtained value of and the correction pattern presented by the figure. The predetermined The density of the read image is corrected based on the density information. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a chart that allows for an improved degree of freedom in selecting the type of reading means. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of an image forming apparatus according to an embodiment. [Figure 3] FIG. 10 is a diagram showing a first example of an abnormal image. [Figure 4] FIG. 10 is a diagram showing a second example of an abnormal image. [Figure 5] FIG. 2 is a diagram illustrating a partial area of ​​a print image. [Figure 6] FIG. 2 is a diagram showing an example of a chart according to the first embodiment. [Figure 7] FIG. 4 is an enlarged view of an example of a region image in a chart according to the first embodiment. [Figure 8] 10A and 10B are diagrams illustrating an example of horizontal streaks. [Figure 9] FIG. 10 is a diagram showing an example of horizontal streaks. [Figure 10] 10A and 10B are diagrams illustrating examples of area images included in a chart according to the second embodiment. [Figure 11] 11A and 11B are diagrams showing examples of changes in density of a region image depending on brightness, where FIG. 11A shows a bright case, FIG. 11B shows an intermediate case, and FIG. 11C shows a dark case. [Figure 12] FIG. 2 is a diagram illustrating an example of the functional configuration of a processing unit included in the smartphone. [Figure 13] 13A and 13B are diagrams showing examples of density correction, with FIG. 13A being a diagram of a first example and FIG. 13B being a diagram of a second example. [Figure 14]10 is a flowchart of an example of processing by a processing unit included in the smartphone. [Figure 15] 13A and 13B are diagrams illustrating examples of area images of a chart according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0010] Furthermore, the embodiments shown below are examples of charts, image forming devices, image processing devices, and programs for embodying the technical concepts of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended as examples and are not intended to limit the scope of the present invention. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity of explanation.

[0011] The chart according to the embodiment is a chart in which the image forming apparatus to be diagnosed forms an area image, such as a test image, on a recording medium in order to diagnose an abnormality in the printed image by the image forming apparatus. Since the type or position of the abnormal image varies depending on the abnormality that occurs in the image forming apparatus, the abnormality in the image forming apparatus can be diagnosed based on the abnormal image included in the chart.

[0012] Here, diagnosing an abnormality in an image forming apparatus means determining whether or not there is an abnormality in the image forming apparatus, and if there is an abnormality, determining the cause of the abnormality in order to take measures. In this embodiment, the abnormality is diagnosed by a person who visually checks the chart. This person includes a user who uses the image forming apparatus, an administrator who manages the image forming apparatus, a serviceman who maintains the image forming apparatus, a printing operator who provides printing services using the image forming apparatus, etc.

[0013] Examples of recording media on which area images in the chart according to the embodiment are formed include paper such as recording paper (transfer paper), but are not limited to this, and may be coated paper, cardboard, an overhead projector (OHP) sheet, plastic film, prepreg, copper foil, or the like, as long as the media are capable of forming (recording) an image.

[0014] An embodiment of the chart will now be described in detail.

[0015] [Embodiment] First, a description will be given of the configuration of the image forming apparatus 100 to be diagnosed. The image forming apparatus 100 is an image forming apparatus capable of forming a chart according to the embodiment.

[0016] <Example of Hardware Configuration of Image Forming Apparatus 100> 1 is a block diagram illustrating an example of the hardware configuration of an image forming apparatus 100. As shown in FIG. 1, the image forming apparatus 100 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, a HDD (Hard Disk) / SSD (Solid State Drive) 304, an I / F (Interface) 305, an image forming unit 306, and a reading unit 307.

[0017] Of these, the CPU 301 uses the RAM 303 as a work area and executes programs stored in the ROM 302 to control the overall operation of the image forming apparatus 100 .

[0018] The HDD / SSD 304 is used as a storage unit and stores preset setting values. The information stored in the HDD / SSD 304 may be read by the CPU 301 and used when executing a program.

[0019] The I / F 305 is an interface that enables communication between the image forming apparatus 100 and the client PC 101 .

[0020] The image forming unit 306 is a print engine that forms an image on a recording medium, and the reading unit 307 is a reading device that reads the image formed on the recording medium.

[0021] <Configuration Example of Image Forming Apparatus 100> Next, the configuration of image forming apparatus 100 will be described with reference to Fig. 2. Fig. 2 is a diagram illustrating an example of the configuration of image forming apparatus 100. As shown in Fig. 2, image forming apparatus 100 has tandem electrophotographic photosensitive drums 403K, 403C, 403M, and 403Y, an intermediate transfer belt 402, a secondary transfer roller 404, a paper feed unit 400, a pair of conveying rollers 401, a fixing roller 405, in-line sensors 406a and 406b, a reverse path 407, and a conveying path 408.

[0022] It should be noted that K stands for black, C stands for cyan, M stands for magenta, and Y stands for yellow.

[0023] 1 includes photosensitive drums 403K, 403C, 403M, and 403Y, an intermediate transfer belt 402, a secondary transfer roller 404, and a fixing roller 405. The reading unit 307 in FIG. 1 also includes in-line sensors 406a and 406b.

[0024] Image forming apparatus 100 is a so-called tandem-type image forming apparatus having a configuration in which photosensitive drums 403Y, 403M, 403C, and 403K (hereinafter collectively referred to as photosensitive drums 403) of respective colors are arranged along intermediate transfer belt 402, which is an endless moving means. Photosensitive drums 403Y, 403M, 403C, and 403K are arranged in this order from the upstream side in the conveying direction of intermediate transfer belt 402 along intermediate transfer belt 402, on which an intermediate transfer image to be transferred to a recording medium fed from paper feed unit 400 and conveyed by conveying roller pair 401 is formed.

[0025] The image forming device 100 carries toner images of each color developed with toner on the surface of the photosensitive drum 403 of each color, and transfers the carried toner images in a superimposed manner onto the intermediate transfer belt 402, thereby forming a full-color image on the intermediate transfer belt 402.

[0026] The image forming apparatus 100 transfers the full-color image formed on the intermediate transfer belt 402 onto the recording medium transported on the transport path 408 at the position closest to the recording medium transport path 408 shown by the dashed line in the figure, using the function of the secondary transfer roller 404.

[0027] The recording medium on which the image has been formed is further conveyed, and the image is fixed (image formed) by fixing rollers 405. Fixing rollers 405 are an example of a fixing unit that thermally fixes an image onto a recording medium. Fixing rollers 405 fix the full-color toner image onto the recording medium by applying heat and pressure to the recording medium onto which the full-color toner image has been transferred. Fixing roller 405 generates heat using a built-in heater such as a halogen heater, and can heat the recording medium.

[0028] When double-sided printing is performed, the image forming apparatus 100 forms an image on the front side, then transports the recording medium to the reversal path 407 in the transport path 408, where it is inverted and then transported again to the position of the secondary transfer roller 404.

[0029] The paper feed section 400 accommodates a plurality of recording media stacked one on top of the other.

[0030] In-line sensors 406a and 406b (hereinafter collectively referred to as in-line sensor 406) are provided downstream of the fixing roller 405 in the conveying direction of the recording medium.

[0031] Inline sensor 406 reads both sides of the recording medium by fixing roller 405, and obtains a read image of the image fixed on the recording medium. Note that two inline sensors 406 (406a, 406b) are not necessarily required, and only inline sensor 406a may be used. When only sensor 406a is used, reading is performed by inline sensor 406a when an image is formed on the front side, and then image formation on the back side is performed.

[0032] Here, the in-line sensor 406 is a CCD (Charge Coupled Device) line sensor in which pixels that output electrical signals according to the intensity of received light are arranged in a one-dimensional array. The pixel arrangement direction intersects with the conveyance direction of the recording medium. The in-line sensor 406 also includes a pixel array that receives red light (R), a pixel array that receives green light (G), and a pixel array that receives blue light (B). Note that, below, red may be represented as R, green as G, and blue as B, respectively.

[0033] In-line sensor 406 outputs an electrical signal corresponding to the light intensity of light reflected by the image formed on the recording medium using a pixel array for each color. Image forming apparatus 100 uses the light intensity (density) of each color of the image read by in-line sensor 406 as color information for correcting the color of the image.

[0034] Each inline sensor 406 may include a light source that irradiates the recording medium with light. By irradiating the recording medium with light from the light source, it is possible to ensure sufficient brightness for reading by the inline sensor 406.

[0035] <Example of an abnormal image> Next, an abnormal image that occurs in the image forming apparatus 100 and a method for diagnosing the abnormal image will be described with reference to Figures 3 to 5. Figure 3 is a diagram showing a first example of an abnormal image, Figure 4 is a diagram showing a second example of an abnormal image, and Figure 5 is a diagram explaining a partial region of a printed image.

[0036] 3, a printed image 40 is formed on the recording medium 2 by the image forming apparatus 100. The printed image 40 includes a pie chart 41 and a bar graph 42.

[0037] The vertical streaks 11 and 12 are examples of abnormal images in which an area of ​​the printed image 40 that has a different image density compared to the surrounding images extends linearly along the conveying direction 101. The conveying direction 101 is the direction in which the recording medium 2 is conveyed when the image forming apparatus 100 forms an image.

[0038] These vertical streaks 11 and 12 often occur in the charging section, which charges the photosensitive member using a corona discharge generator called a scorotron. Vertical streaks can also occur due to dirt that always appears in the same position due to poor cleaning or other reasons.

[0039] Furthermore, abnormal images such as vertical streaks 11 and 12 may occur for each color. Figure 4 shows a printed image 40K containing only a black rectangular area, a printed image 40C containing only a cyan rectangular area, a printed image 40M containing only a magenta rectangular area, and a printed image 40Y containing only a yellow rectangular area, which are formed on four recording media 2. As shown in Figure 4, a vertical streak 13 occurs only in printed image 40C.

[0040] Vertical streaks occur for all colors in the process after the toner image is transferred to the intermediate transfer belt 402. Vertical streaks of a single color occur in the process before the image is transferred to the intermediate transfer belt 402. Therefore, it can be diagnosed that the streaks occurred in any of the processes of development, charging, cleaning, or exposure.

[0041] Furthermore, since the area of ​​the vertical streak 13 is lighter than the surrounding area, the area of ​​the vertical streak becomes darker due to toner passing through, and is not caused by cleaning of the photosensitive drum 403C.

[0042] Furthermore, vertical stripes also become darker due to insufficient charging caused by contamination of the charging portion. Therefore, it is highly likely that the cause lies in either the development or exposure process, which are processes other than charging and cleaning.

[0043] Therefore, the cover glass included in the exposure unit is checked for dirt at a position corresponding to the vertical streak 13, or for any areas in the development unit where developer is partially stagnating due to dust or foreign matter. In this way, abnormalities can be diagnosed. When diagnosing abnormalities, it is important to have an image that shows the characteristics of the abnormality and the location where the abnormality occurs in the printed image.

[0044] On the other hand, when diagnosing an abnormality, there is a demand for transmitting and receiving images obtained by scanning the print image of the image forming apparatus to be diagnosed between users, administrators, service personnel, printing operators, etc. For example, there are cases where a user of image forming apparatus 100 transmits a print image formed by image forming apparatus 100 to a service personnel in a remote location via a network, etc., and the service personnel visually checks the received print image and performs a diagnosis.

[0045] In this case, if various reading means such as a scanner such as the reading unit 307, or a digital camera or a smartphone camera included in a smartphone can be used to read the printed image, the freedom to select the reading means increases, which is more preferable.

[0046] However, compared to scanners, digital cameras or smartphone cameras have different image capture ranges for charts that can be read at the same resolution. If a digital camera or smartphone camera is used to capture the same image range as a scanner, the resolution will be lower, making the characteristics of abnormalities unclear and making it impossible to make an accurate diagnosis.

[0047] In order to ensure resolution, if only a portion 14 of the printed image 40C is photographed as shown in Figure 5, the location of the abnormality in the printed image may become unclear, making it impossible to make an accurate diagnosis.

[0048] As a result, the degree of freedom in selecting the reading means is limited.

[0049] [First embodiment] Therefore, in this embodiment, a chart including a plurality of area images, each of which includes a graphic indicating the position information of the area image within the chart, is used to perform diagnosis. Chart 1 according to this embodiment will be described below.

[0050] <Chart 1 configuration example> The configuration of the chart 1 will be described with reference to Figures 6 and 7. Figure 6 is a diagram for explaining an example of the configuration of the chart 1.

[0051] 6, the chart 1 includes a recording medium 2 and a plurality of area images 3. The chart 1 is formed by the image forming apparatus 100, which is the target of diagnosis, forming the plurality of area images 3 on the recording medium 2, in order to diagnose an abnormality in the printed image by the image forming apparatus 100.

[0052] Each of the multiple area images 3 is an image formed by an image forming device on a recording medium 2 in a predetermined area based on image data. As shown in FIG. 1, the area image 3 includes a mark 31, a two-dimensional code 32, and a pattern 33.

[0053] The mark 31 is an L-shaped mark formed at the end of the area image 3, and indicates the range of the area image 3 within the chart 1. However, the shape of the mark may be any shape as long as it can indicate the range of the area image 3, and the position where the mark is placed may also be any position.

[0054] The two-dimensional code 32 is an example of a graphic that indicates the position information of the area image 3 within the chart 1. The two-dimensional code 32 is, for example, a QR code (registered trademark), but other identification codes such as a barcode can also be used as long as they are a graphic that indicates the position information of the area image 3. There are no particular restrictions on the position and orientation of the two-dimensional code 32 within the area image 3, and it can be placed at any position and in any orientation.

[0055] The pattern 33 is a rectangular pattern of a single color with a substantially uniform density formed over the entire area image 3. However, the pattern 33 is not limited to a rectangular shape and can be appropriately selected depending on the type of abnormal image to be diagnosed.

[0056] For example, if the abnormal image contains linearly extending streaks, a rectangular pattern with a single color and substantially uniform density is preferred, such as pattern 33. If the abnormal image contains streaks that are darker than the surrounding area, a rectangular pattern with a single color and substantially uniform density is preferred. If the abnormal image contains streaks that are darker than the surrounding area, a rectangular pattern with a single color and substantially uniform density is preferred.

[0057] The vertical streak 10 occurs when a region image 3 is formed on a recording medium 2 by the image forming apparatus 100 to be diagnosed.

[0058] 7 is an enlarged view illustrating the configuration of the area image 3 in the chart 1. The area image 3 shown in FIG. 7 corresponds to an image of a part of the chart 1 photographed with a camera attached to a smartphone or the like.

[0059] 7, the area image 3 includes a mark 31, a two-dimensional code 32, and a pattern 33. The mark 31 includes marks 31a and 31b provided at two of the four corners included in the area image 3.

[0060] The two-dimensional code 32 includes position information of the area image 3 on the chart 1. For example, when a predetermined reference position on the chart 1 is defined as coordinates (0.0, 0.0), the two-dimensional code 32 indicates the coordinates (250.0, 110.3) of the corner where the mark 31a is provided and the coordinates (280.0, 140.3) of the corner where the mark 31b is provided.

[0061] When the data of the area image 3 is transmitted to a remote location, the remote location can read the two-dimensional code 32 to obtain information indicating the width W of the area image 3 based on the position information indicated by the two-dimensional code 32. Furthermore, based on the position information indicated by the two-dimensional code 32 and the position P in the area image 3, information indicating the position of the vertical streak 10 on the chart 1 can be obtained.

[0062] The photographer decides which area to photograph on the chart 1. At this time, the area that will give the area image 3 that shows the characteristics of the abnormality is photographed.

[0063] <Chart 1 Actions and Effects> As described above, the chart 1 according to this embodiment includes a plurality of area images 3, and the area images 3 include two-dimensional codes 32 (graphics) that indicate the position information of the area images 3 within the chart 1. The area images 3 may also include barcodes.

[0064] This means that even when an area image 3 that captures a portion of the chart 1 is received, the characteristics of the abnormality and the location where the abnormality occurs in the printed image can be recognized from the area image 3, and the abnormality can be accurately diagnosed based on the area image 3.

[0065] In this embodiment, the area image 3 includes a mark 31 that indicates the range of the area image 3 within the chart 1. The position of the mark 31 can be used to indicate the position of the area image 3 within the chart 1, making it possible to more accurately determine the location of an abnormality in the printed image.

[0066] Here, horizontal streaks as an example of an abnormal image other than vertical streaks will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram for explaining an example of the mechanism by which horizontal streaks occur, and Fig. 9 is a diagram showing an example of horizontal streaks.

[0067] As shown in Figure 8, when the recording medium 2 enters the transfer roller 81 included in the image forming apparatus 100, vibrations called shock jitter may occur due to factors such as the thickness of the recording medium 2. Such vibrations may cause the distance between the transfer roller 81 and the recording medium 2 to fluctuate, resulting in horizontal streaks extending in a direction perpendicular to the conveyance direction 101. Horizontal streaks are areas with a different density from the surrounding areas. The amount of vibration increases as the thickness of the recording medium 2 increases.

[0068] When the recording medium 2 enters the transfer roller 81, the image vibrates, and a horizontal streak 15 appears at a position on the recording medium 2 that corresponds to the distance between the transfer roller 81 and the image forming unit. As shown in Figure 9, a horizontal streak 15 extending in a direction perpendicular to the conveying direction 101 appears at a position a distance q away from the leading edge (downstream side) of the recording medium in the conveying direction 101. The distance q corresponds to the distance between the transfer roller 81 and the image forming unit on the recording medium 2.

[0069] Since the horizontal streaks 15 occur due to the thickness of the recording medium 2, it is preferable that the two-dimensional code 32 also indicates thickness information of the recording medium 2, since this allows for more accurate diagnosis of the horizontal streaks 15. The thickness information of the recording medium 2 is an example of image formation condition information by the image forming apparatus.

[0070] The image forming condition information also includes image screen conditions, color mode information such as whether to form a full-color image or a monochrome image, and the like.

[0071] [Second embodiment] Next, a chart 1a according to the second embodiment will be described. Note that the same components as those described in the first embodiment will be assigned the same part numbers, and duplicated descriptions will be omitted as appropriate. This also applies to the following embodiments.

[0072] In this diagnosis, it is preferable to be able to determine how the density of the region image 3a differs from that of other region images in order to determine not only the presence or absence of an abnormality but also the degree of the abnormality. However, when capturing the region image 3a, the brightness of the region image may differ even when the same chart 1a is scanned, depending on the ambient light and the capture conditions (e.g., shutter speed, gain, etc.) of the reading means, such as a smartphone camera. When the brightness of the region image 3a differs, the contrast also changes. As a result, it may be difficult to determine how the density of the region image differs from that of other region images.

[0073] In this embodiment, the area image included in the chart 1a includes a correction patch that serves as a density reference, thereby correcting the density of the area image and more accurately diagnosing an abnormal image such as a vertical streak 10.

[0074] 10 is a diagram showing an example of a region image 3a included in a chart 1a. In the chart 1a, the region image 3 in the configuration of FIG. 6 is replaced with the region image 3a.

[0075] 10, the region image 3a includes a correction patch 34. The correction patch 34 is formed with a predetermined density and is an example of a correction pattern for correcting the density of the region image 3a. The correction patch 34 includes a low-density portion 34a and a high-density portion 34b. The low-density portion 34a is a region with low density (light region), and the high-density portion 34b is a region with high density (dark region).

[0076] Fig. 11 is a diagram showing an example of the change in density of the region image 3a depending on the brightness. Fig. 11(a) shows a bright case, Fig. 11(b) shows an intermediate case, and Fig. 11(c) shows a dark case. As shown in Fig. 11, the density of the pattern 33 of the region image 3a varies depending on the brightness.

[0077] The density correction process is performed by an image processing device including a reading unit that captures the region image 3a. In this embodiment, the smartphone 200 is used as an example of the image processing device, and a smartphone camera is used as the reading unit. The image captured by the smartphone camera is an example of a read image.

[0078] FIG. 12 is a block diagram showing an example of the functional configuration of a processing unit 250 included in a smartphone 200 that captures the area image 3a with a smartphone-attached camera.

[0079] 12, the processing unit 250 has a luminance acquisition unit 251, a correction unit 252, and an output unit 253. These functions are realized by an electric circuit included in the smartphone 200, and some or all of these functions can also be realized by software included in the smartphone 200 (CPU: Central Processing Unit).

[0080] The luminance acquisition unit 251 acquires an image of the region image 3a captured by the smartphone camera by inputting it from the smartphone camera, and acquires input luminance values ​​for each of the low-density portion 34a and the high-density portion 34b of the correction patch 34. The luminance acquisition unit 251 can acquire the average value of the luminance values ​​of the pixels that make up the low-density portion 34a as the input luminance value of the low-density portion 34a, and can acquire the average value of the luminance values ​​of the pixels that make up the high-density portion 34b as the input luminance value of the high-density portion 34b.

[0081] The correction unit 252 corrects the density of the region image 3a by adjusting output characteristics that convert the input luminance value into an output luminance value so that the luminance values ​​of the low-density portion 34a and the high-density portion 34b in the region image 3a fall within a predetermined reference range, based on the input luminance value acquired by the luminance acquisition unit 251. The reference range is determined, for example, with the input luminance value of the low-density portion 34a as the upper limit and the input luminance value of the high-density portion 34b as the lower limit when the region image 3a is captured under reference brightness conditions.

[0082] The output unit 253 outputs the captured image processed by the processing unit 250 to an external device, a display of the smartphone 200, or the like.

[0083] 12A and 12B are diagrams illustrating an example of density correction processing, with Fig. 12A showing a case where the brightness is high as a first example, and Fig. 12B showing a case where the brightness is low as a second example. The horizontal axis of Fig. 12 indicates the input brightness value of the region image 3a, and the vertical axis indicates the output brightness value of the region image 3a after brightness correction. An upper limit 121 indicates the upper limit of the reference range of brightness values, and a lower limit 122 indicates the lower limit of the reference range of brightness values.

[0084] 12(a), a low-density luminance value 120a indicates the luminance value of the low-density portion 34a in the correction patch 34 acquired by the luminance acquisition unit 251. A high-density luminance value 120b indicates the luminance value of the high-density portion 34b in the correction patch 34 acquired by the luminance acquisition unit 251. A line connecting the low-density luminance value 120a and the high-density luminance value 120b represents the output characteristics.

[0085] Because the image was taken under bright conditions, the low density luminance value 120a is brighter (lighter) than the upper limit 121, and the high density luminance value 120b is brighter (lighter) than the lower limit 122. The correction unit 252 corrects the output characteristics so that the low density luminance value 120a approximately matches the upper limit 121, and so that the high density luminance value 120b approximately matches the lower limit 122. Note that approximately matching means that a difference that is generally recognized as an error is allowed.

[0086] 12(b), a low-density luminance value 120c indicates the luminance value of the low-density portion 34a in the correction patch 34 acquired by the luminance acquisition unit 251. A high-density luminance value 120d indicates the luminance value of the high-density portion 34b in the correction patch 34 acquired by the luminance acquisition unit 251. The line connecting the low-density luminance value 120c and the high-density luminance value 120d represents the output characteristics.

[0087] Because the image was captured under dark conditions, the low density luminance value 120c is darker (higher) than the upper limit 121, and the high density luminance value 120d is darker (higher) than the lower limit 122. The correction unit 252 corrects the output characteristics so that the low density luminance value 120c approximately matches the upper limit 121, and so that the high density luminance value 120d approximately matches the lower limit 122.

[0088] Next, Fig. 14 is a flowchart showing an example of processing by the processing unit 250. Fig. 14 shows processing that is triggered when the photographer presses the shooting button provided on the smartphone 200 and starts shooting with the smartphone camera.

[0089] First, in step S141, the luminance acquisition unit 251 acquires a captured image of the area image 3a captured by the smartphone camera of the smartphone 200 by inputting it from the smartphone camera.

[0090] Subsequently, in step S142, the luminance acquisition unit 251 acquires the input luminance values ​​of the low density portion 34a and the high density portion 34b of the correction patch 34.

[0091] Next, in step S143, the correction unit 252 corrects the density of the region image 3a by adjusting the output characteristics based on the input brightness value acquired by the brightness acquisition unit 251 so that the brightness values ​​of the low density portion 34a and the high density portion 34b in the region image 3a fall within a predetermined reference range.

[0092] Subsequently, in step S144, the output unit 253 outputs the captured image processed by the processing unit 250 to an external device or a display of the smartphone 200 or the like.

[0093] In this way, the processing unit 250 can correct the density of the captured image of the region image 3a.

[0094] As described above, in this embodiment, the region image 3a included in the chart 1a includes the correction patch 34. The processing unit 250 can correct the density of the region image 3a in a captured image obtained by capturing the region image 3a using the correction patch 34. This makes it possible to accurately determine how the density in the region image 3a differs from the density of other region images in diagnosing an abnormality, thereby enabling accurate diagnosis.

[0095] Here, if the chart 1a includes the correction patches 34, the density of the correction patches 34 may vary depending on the state of the image forming apparatus 100 that forms the area images 3a on the chart 1a.

[0096] Therefore, the two-dimensional code 32 may indicate information on the density detected by an image density sensor such as a toner density sensor that is provided in the image forming apparatus 100 and detects the density of the toner image formed on the intermediate transfer belt 402.

[0097] The processing unit 250 can correct the density of the region image 3a after correcting the density of the correction patch 34 in the captured image of the region image 3a using information on the density detection value indicated by the two-dimensional code 32. This enables more accurate density correction.

[0098] 15, the area image 3a included in the chart 1a can also include an attached correction patch 35 instead of the correction patch 34. The attached correction patch 35 is a correction patch, which is a medium printed by an offset printing device separate from the image forming device 100, attached to the surface of the chart 1b.

[0099] The offset printing apparatus has a more stable density of printed images than the electrophotographic image forming apparatus 100. Therefore, by performing correction using the attached correction patch 35 included in the area image 3b, the density can be corrected more accurately.

[0100] In this embodiment, the correction patch 34 has a white low-density portion 34a and a black high-density portion 34b, but the present invention is not limited to this. The correction patch 34 can also have a plurality of intermediate density portions, such as gray. Furthermore, when the image forming apparatus handles color, the density can be corrected for each color by including a correction patch for each color in the region image 3a.

[0101] Furthermore, if the two-dimensional code 32 indicates density information of the correction patch 34, the upper limit 121 and lower limit 122 can be set using this density information, and the target density to be corrected can be determined.

[0102] Although the present embodiment has been described with reference to a configuration in which a smartphone camera is used as the reading unit, the present invention is not limited to this. The correction process according to the present embodiment can also be applied when a scanner or a digital camera is used as the reading unit.

[0103] Although the embodiments have been described above, the present invention is not limited to the specifically disclosed above embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0104] Furthermore, in the above-described embodiment, an electrophotographic image forming apparatus has been described, but the present invention is also applicable to other image forming apparatuses such as an inkjet type.

[0105] Furthermore, all ordinal numbers, quantitative numbers, and other figures used in the description of the embodiments are merely examples for specifically explaining the technology of the present invention, and the present invention is not limited to the exemplified figures. Furthermore, the connection relationships between the components are merely examples for specifically explaining the technology of the present invention, and the connection relationships for realizing the functions of the present invention are not limited to these.

[0106] The embodiments also include a program. For example, the program may be a program that runs on an image processing device capable of processing a scanned image of a chart, the chart including a plurality of area images, each of the area images including a graphic indicating position information of the area image within the chart, and the area images including a correction pattern used to correct at least one of the color or density of the area image, and the program causes a computer to execute a process of correcting the luminance of the pattern in the scanned image based on the luminance of an area other than an area corresponding to the correction pattern. Such a program may provide the same effects as the image processing device described above.

[0107] Furthermore, each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or a conventional circuit module designed to perform each function described above. [Explanation of symbols]

[0108] 1 chart 2. Recording media 3 Region images 10, 11, 12, 13 Vertical stripes 31 marks 32 2D code 33 patterns 34 Correction Patch 35 Adhesive Correction Patch 40 Printed Images 100 Image forming device 200 smartphones 250 Processing Section 251 Luminance acquisition unit 252 Correction Unit 253 Output Section [Prior art documents] [Patent documents]

[0109] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-119269

Claims

1. A method for diagnosing an abnormality in an image forming apparatus, comprising: the image forming apparatus, Diagnosing an abnormality in the image forming apparatus based on an image read by an external reading device of a chart formed by the image forming apparatus; the chart includes a plurality of area images; each of the plurality of area images includes a graphic indicating position information of the area image within the chart and predetermined density information; the region image includes a correction pattern used to correct the density of the region image; An abnormality diagnosis method for an image forming device in which a correction unit corrects the density of the read image based on the acquired value of the density of the correction pattern in the read image read by the reading device and the specified density information regarding the correction pattern presented by the figure.

2. A method for diagnosing an abnormality in an image forming apparatus having an image density sensor, comprising: the image forming apparatus, Diagnosing an abnormality in the image forming apparatus based on an image read by an external reading device of a chart formed by the image forming apparatus; the chart includes a plurality of area images; each of the plurality of area images includes a graphic indicating position information of the area image within the chart and detection value information of the image density sensor relating to the area image; the region image includes a correction pattern used to correct the density of the region image; The method for diagnosing an abnormality in an image forming apparatus includes correcting the density of the read image by a correction unit based on the acquired value of the density of the correction pattern in the read image read by the reading device and the detected value information.

3. 3. The method for diagnosing an abnormality in an image forming apparatus according to claim 1, wherein the graphic is at least one of a bar code and a two-dimensional code.

4. 4. The method for diagnosing an abnormality in an image forming apparatus according to claim 1, wherein the area image includes a mark indicating a range of the area image within the chart.

5. 5. The method for diagnosing an abnormality in an image forming apparatus according to claim 1, wherein the graphic further indicates information on image forming conditions for the image forming apparatus.

6. 6. The method for diagnosing an abnormality in an image forming apparatus according to claim 1, wherein the correction pattern is provided by attaching a medium on which the correction pattern having a predetermined density is formed to the chart.

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