Image reading device and image forming device

Abstract

To prevent wrong detection in image inspection.SOLUTION: An image reading device comprises: an image reading unit that reads an image of a recording medium; an output unit that inspects the image and outputs a result of the inspection; and a setting unit that, based on the position of the recording medium with respect to a reading position where the image reading unit reads the image or the type of the recording medium, excludes a first area being a predetermined area of the recording medium from an area inspected by the output unit, and sets a second area obtained by excluding the first area. The output unit outputs the result of the inspection based on the second area.SELECTED DRAWING: Figure 19

Description

[Technical Field]

[0001] The present invention relates to an image reading device and an image forming device. [Background technology]

[0002] An image forming apparatus may be unable to form an intended image on a recording medium such as paper due to unexpected factors, etc. To address this issue, a technique is known for reading the formed image and inspecting the quality of the formed image.

[0003] Specifically, the image inspection device first sets the edge of a sheet of paper or the like as an image inspection exclusion area, excluding the edge of the sheet from the inspection target. Once this setting is made, the inspection is performed excluding the edge of the sheet. In this way, the image inspection device performs the inspection excluding the area where false detection is likely to occur, thereby suppressing false detection in the image inspection caused by deformation of the sheet or the like. For example, deformation of the sheet is a bend that occurs at the edge of the sheet of paper (so-called "kink" or the like). In this way, a technique for suppressing false detection in the image inspection is known (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, the user sets the image inspection exclusion area in advance. Therefore, if the paper conveyed to the image inspection device has variations in orientation relative to the conveyance direction or has deformations at the edges as described above, the previously set image inspection exclusion area will no longer be appropriate for the conveyed paper. As a result, there are cases where the area that should be the image inspection exclusion area cannot be properly excluded. In other words, conventional technology has issues in suppressing false detections in image inspection.

[0005] The present invention aims to suppress false positives in image inspections. [Means for solving the problem]

[0006] In order to solve the above problems, an image reading device according to one aspect of the present invention comprises: an image reading unit that reads an image from a recording medium; an output unit that inspects the image and outputs the inspection result; a setting unit that excludes a first area, which is a predetermined area of ​​the recording medium, from an area to be inspected by the output unit and sets a second area excluding the first area, based on the position of the recording medium relative to a reading position where the image reading unit reads the image or the type of the recording medium, The output unit outputting the inspection result based on the second area; It is characterized by: [Effects of the Invention]

[0007] According to the present invention, false detections in image inspections can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus. [Figure 2] FIG. 1 is a diagram showing an overview of an imaging test. [Figure 3] FIG. 10 is a diagram illustrating an example of setting an area. [Figure 4] FIG. 1 is a diagram illustrating a first comparative example. [Figure 5] FIG. 10 is a diagram illustrating a second comparative example. [Figure 6] FIG. 10 is a diagram showing an example in which a third clamping and conveying unit is provided. [Figure 7] FIG. 10 is a diagram illustrating an example of a setting screen. [Figure 8] FIG. 10 is a diagram showing an example in which a fourth clamping and conveying unit is provided. [Figure 9] FIG. 10 is a diagram illustrating an example of double-sided printing. [Figure 10] FIG. 10 is a diagram illustrating an example of acquiring a paper level. [Figure 11] FIG. 10 is a diagram illustrating an example of a change in brightness. [Figure 12] FIG. 10 is a diagram showing an example of a reading result. [Figure 13]FIG. 10 is a diagram illustrating an example of setting a normal range based on a learning result. [Figure 14] FIG. 10 is a diagram illustrating an example of changing the determination criteria based on the learning result. [Figure 15] FIG. 10 is a diagram illustrating a first modified example of an image reading device. [Figure 16] FIG. 10 is a diagram illustrating a second modified example of the image reading device. [Figure 17] FIG. 10 is a diagram illustrating a third modified example of the image reading device. [Figure 18] FIG. 2 is a diagram illustrating an example of a first surface reading device and a second surface reading device. [Figure 19] FIG. 2 is a diagram illustrating an example of a functional configuration. [Figure 20] FIG. 10 is a diagram illustrating an example of overall processing. DETAILED DESCRIPTION OF THE INVENTION

[0009] Specific examples will be described below with reference to the accompanying drawings, but the embodiments are not limited to the specific examples described below.

[0010] [First embodiment] [Overall configuration example] Figure 1 is a diagram showing an example of the overall configuration of an image forming apparatus. Hereinafter, the conveyance direction of a recording medium will be referred to as the "Y direction." The direction perpendicular to the conveyance direction will be referred to as the "X direction." Furthermore, the direction perpendicular to the XY plane will be referred to as the "Z direction."

[0011] For example, as shown in the figure, the image forming apparatus 1 includes an image forming unit 20, a paper feeding device 10, an image reading device 30, and a post-processing device 40.

[0012] The image forming device 20 is a device that forms an image on the paper S based on input image data.

[0013] The paper feeder 10 is a device that supplies paper S to the image forming device 20.

[0014] The image reading device 30 is a device that reads the paper S discharged from the image forming device 20, that is, the image formed on the paper S.

[0015] The post-processing device 40 is a device having a plurality of paper discharge trays, etc. In this embodiment, the post-processing device 40 has a first paper discharge tray 42 and a second paper discharge tray 43.

[0016] In the image forming apparatus 1, a paper feeder 10, an image forming device 20, an image reading device 30, and a post-processing device 40 are physically connected in this order from the upstream side (the right side in the figure) to the downstream side in the transport direction. These multiple devices are connected to each other to form the image forming apparatus 1. Therefore, a transport path P along which the paper S is transported is made up of multiple devices. This transport path P is branched by a sorting device 41 included in the post-processing device 40 into a first path P1 to a first paper output tray 42 located below and a second path P2 to a second paper output tray 43 located above.

[0017] 1, the transport path P is shown as a single line, but there may be a transport path for double-sided printing, etc. Also, the path for paper discharge may branch into three or more paths depending on the number of paper discharge trays, etc.

[0018] The paper feeder 10 stores various sizes or types of paper sheets S. For example, the paper feeder 10 includes a paper feed roller that feeds the stored paper sheets S one by one, a motor that drives the paper feed roller, and the like.

[0019] The image forming unit 20 includes a forming unit 21 that forms an image by an intermediate transfer method using electrophotographic process technology, for example.

[0020] The former 21 first performs primary transfer of the toner images of each color, such as Y (yellow), M (magenta), C (cyan), and K (black), formed on the photosensitive drum onto the intermediate transfer belt. Next, the former 21 superimposes the four color toner images on the intermediate transfer belt. After that, the former 21 performs secondary transfer onto the paper S. In this way, the former 21 forms a toner image on the paper S.

[0021] The image forming unit 20 also has a fixing unit 22 downstream of the forming unit 21 in the transport direction, which heats and presses the paper S to fix the toner image onto the paper S.

[0022] The image forming method and the configuration of the image forming device 20 may be other than those described above.

[0023] The image forming device 20 has an operation / display device 25. The operation / display device 25 is, for example, a liquid crystal display (LCD) with a touch panel. Specifically, the operation / display device 25 is made up of a display device 26, an operation device 27, etc.

[0024] The display device 26 displays an operation screen, an image state, and the operating status of each function in accordance with a display control signal.

[0025] The operation device 27 is configured with a numeric keypad, a start key, etc. The operation device 27 accepts input operations by the user and outputs operation signals to the control device, etc.

[0026] Furthermore, the display device 26 may display an icon on the screen using a cursor or a pointer, and may also receive an input operation from the user and output an operation signal to a control device or the like.

[0027] The image forming device 20 may include an image processing device that performs corrections such as gradation correction on input image data, a paper conveying device that drives conveying rollers, or a communication device that communicates with an external device via a communication network or the like.

[0028] In addition, the image forming device 20 may have a configuration as a copier that copies an original onto paper S, that is, may have a device such as an auto document feeder (ADF) and a device that scans an original (a so-called scanner).

[0029] The image reading device 30 has an output image reading device 31 that optically reads an image formed on the paper S. Specifically, the output image reading device 31 reads one or both sides of the paper S with a sensor such as a Charge Coupled Device (CCD), and generates read image data based on the reading results.

[0030] The image reading device 30 also has an arithmetic unit, a control unit, a storage device, an input device, an output device, a communication device, etc., and processes images acquired by the sensor, etc. For example, the image reading device 30 has a central processing unit (CPU, hereinafter referred to as "CPU 32"), a read only memory (ROM, hereinafter referred to as "ROM 33"), a random access memory (RAM, hereinafter referred to as "RAM 34"), etc.

[0031] The CPU 32 is an example of a computing device and a control device.

[0032] The ROM 33 and the RAM 34 are examples of storage devices.

[0033] The sorting device 41 includes a switching gate for switching the discharge destination of the paper S, a drive source such as a solenoid for driving the switching gate, an interface for transmitting and receiving data, and the like.

[0034] The post-processing device 40 may include a cutter that cuts the sheets S, a stapler that staples the sheets S, a folding mechanism that folds the sheets S, and the like.

[0035] [Example of inspection] 2 is a diagram showing an outline of image inspection. Hereinafter, an example will be taken in which image data input to an image forming apparatus (hereinafter referred to as "input image data 201") is image-formed on a sheet S.

[0036] As shown in the figure, an image based on input image data 201 is formed on paper S, and then a sensor 203 disposed downstream in the transport direction (referring to the left side in the figure) reads the image formed on paper S. In this way, the image reading device 30 generates image data (hereinafter referred to as "read image data 202") based on the reading result of the sensor 203.

[0037] Image inspection (hereinafter sometimes simply referred to as "inspection") is performed by comparing input image data 201 with read image data 202. Specifically, the image reading device 30 uses the input image data 201 as a reference and inspects whether the read image data 202 contains any images that are not included in the input image data 201.

[0038] More specifically, the inspection checks for the presence or absence of stains due to toner or ink, scratches that occurred during transportation, uneven printing, misalignment (so-called "misregistration" or "plate misalignment"), or a combination of these (hereinafter referred to as "stains, etc."). Note that the inspection standard may be a preset tolerance, and the presence or absence of stains that exceed the tolerance may be determined.

[0039] For example, the image inspection is realized by image recognition, etc. That is, the image inspection is performed based on whether the scanned image data 202 is an image that matches the input image data 201, etc. Therefore, the image inspection may be realized by image recognition processing for removing dust, etc.

[0040] The input image data 201 may be generated before the inspection is performed. For example, the input image data 201 may be generated once and then used for another inspection. In this way, the processing for generating the input image data 201 can be reduced, thereby reducing the processing load.

[0041] If there is any dirt or the like, the image reading device 30 outputs an inspection result informing the user that an abnormality has occurred. On the other hand, if there is no dirt or the like, the image reading device 30 outputs an inspection result informing the user that the device is normal.

[0042] [Area setting example] 3 is a diagram showing an example of setting an area. FIG. 3 is a diagram showing how the conveying state of paper S changes. As shown in the figure, image reading device 30 is provided with a first roller pair 301, which is an example of a first nipping and conveying unit, at a position upstream of sensor 203 (downward in the figure). Furthermore, image reading device 30 is provided with a second roller pair 302, which is an example of a second nipping and conveying unit, at a position downstream of sensor 203 (upward in the figure).

[0043] Below, an example will be described in which the sheet S is conveyed and its state changes in the order of Figures 3(A), 3(B), 3(C), and 3(D). That is, each figure in Figure 3 shows a different state in which the sheet S is gripped by the first clamping and conveying unit and the second clamping and conveying unit.

[0044] 3(A) or 3(D) is a state in which the sheet S is clamped by either the first roller pair 301 (first clamping and conveying section) or the second roller pair 302 (second clamping and conveying section). When the sheet S is not gripped by the roller pair that constitutes the conveying path P in this way, the conveying state of the sheet S tends to become unstable (it often "flutters").

[0045] Specifically, in the state shown in Fig. 3(A), the second roller pair 302 grips the sheet S, but the first roller pair 301 does not grip the sheet S. In this state, the area that becomes the leading edge of the sheet S (hereinafter referred to as "leading edge area 311") is prone to flapping.

[0046] 3(D), the first roller pair 301 grips the sheet S, but the second roller pair 302 does not grip the sheet S. In this state, the area that becomes the rear end of the sheet S (hereinafter referred to as the "rear end area 312") is prone to flapping.

[0047] In contrast to these states, in the states shown in Figures 3(B) and 3(C), the sheet S is held by both the first roller pair 301 and the second roller pair 302, so the sheet S is stable.

[0048] When image inspection is performed on a sheet S that is flapping, the accuracy of reading by the sensor 203 may be reduced. Therefore, the image reading device 30 performs a process of excluding areas where flapping is likely to occur from the read image data 202 generated from the results of reading by the sensor 203, depending on the position of the sheet S being conveyed. This "exclusion process" is a process of "excluding" a specific area from the results of reading by the sensor 203 as an area to be inspected. In other words, a setting is made to perform a masking process on part of the read image data 202. Note that the "exclusion process" may also be referred to as "excluding from inspection" or "masking."

[0049] Hereinafter, the predetermined area excluded from the area to be inspected will be referred to as a "first area." The area excluding the first area, that is, the area to be inspected (inspection target area), will be referred to as a "second area."

[0050] The first and second regions are preferably set according to the state in which the paper S is being transported. For example, in the state shown in Fig. 3(A), the first region is the leading edge region 311. In the state shown in Fig. 3(D), the first region is the trailing edge region 312.

[0051] In this way, it is desirable to exclude areas that are prone to fluttering and to inspect the remaining second area depending on the state of transport of the paper S. Setting the first area depending on the state in this way can further improve the accuracy of the inspection.

[0052] Alternatively, the first region may be set depending on the presence or absence of an image. That is, there may be a case where an image is not formed in the input image data 201, resulting in an area without an image such as text. In such a case, a process may be executed to set the area without an image such as text as the first region.

[0053] Furthermore, the first area may be set as a margin, etc. In other words, the first area may include an area where no image formation is performed.

[0054] In this way, the image reading device 30 can reduce the area to be inspected and speed up the inspection.

[0055] However, the image reading device 30 may use an area where there is no image such as text to check whether stains of toner, ink, or the like have occurred.

[0056] The extent of the leading edge region 311 and the trailing edge region 312 may vary depending on the type of paper S. For example, the likelihood of flapping varies depending on the hardness of the paper S. Therefore, for types of paper that tend to flap easily, the areas of the leading edge region 311 and the trailing edge region 312 may be set to be large.

[0057] Similarly, if the reading position is far from the position where the paper S is gripped, the reading accuracy is likely to deteriorate due to the influence of fluttering.

[0058] In this way, the range set in the first region may be changed based on the position of the paper S relative to the reading position or the type of the paper S. When such a change is made, it is possible to accurately exclude regions that are difficult to read.

[0059] Note that by using a clamping and conveying unit, the image reading device 30 can stably convey the paper S. Therefore, when the image reading device 30 is provided with a clamping and conveying unit, it can perform inspections with high accuracy. Furthermore, when the image reading device 30 is provided with multiple clamping and conveying units, the paper S is clamped at multiple positions, allowing the paper S to be conveyed more stably. Note that the position, number, and shape of the clamping and conveying units are not limited to those exemplified.

[0060] [Comparative Example] 4 is a diagram showing a first comparative example. For example, the first comparative example is an example in which a setting is made in advance to set an area to be excluded from inspection as a specific image indicated by input image data 201 (hereinafter referred to as a "specific image 401").

[0061] 5 is a diagram showing a second comparative example. For example, the second comparative example is an example in which the area to be excluded from inspection is set in advance to be the edge portion indicated by the input image data 201 (hereinafter simply referred to as "edge portion 402").

[0062] In the first and second comparative examples, if the recording medium flutters or is warped, it may not be possible to perform the inspection with high accuracy.

[0063] [Second embodiment] Fig. 6 is a diagram showing an example in which a third clamping and conveying unit is provided. The following description will be given taking the image reading device 30 and post-processing device 40 shown in Fig. 1 as an example. For example, it is desirable for the image reading device 30 to change the area settings or inspection criteria, etc., taking into account peripheral devices such as the post-processing device 40.

[0064] Specifically, in this example, post-processing device 40 includes a third roller pair 303 that is an example of a third nip-and-convey unit.

[0065] A shock is likely to occur to the sheet S when its leading edge enters the third roller pair 303. That is, when the leading edge is conveyed to the third roller pair 303, deformation of the sheet S is likely to occur when the sensor 203 reads it.

[0066] In particular, if the force for conveying the sheet S differs between the image reading device 30 and the post-processing device 40, the shock is likely to be large. For example, if the roller pairs of the image reading device 30 and the post-processing device 40 have different rotational speeds, the shock is likely to be large. That is, if there is a difference between the conveyance speed of the sheet S when the leading edge of the sheet S enters the third roller pair 303 and the conveyance speed at which the leading edge of the sheet S is nipped and conveyed by the third roller pair 303, there will be a difference in the conveyance speed between the leading edge of the sheet S and the remaining portions. As a result, a shock may occur to the entire sheet S when it enters the third roller pair 303. This shock may easily cause deformation or the like to the sheet S.

[0067] The post-processing device 40 can be changed to various models. Therefore, the distance from the reading position 601 to the gripping position of the third roller pair 303 (hereinafter referred to as the "downstream gripping position 602") may change depending on the model of the peripheral device.

[0068] For example, the distance from the entrance of the post-processing device 40 to the downstream gripping position 602 (hereinafter referred to as the "first distance 611") and the distance from the reading position 601 to the exit of the image reading device 30 (hereinafter referred to as the "second distance 612") have the combinations shown below (Table 1).

[0069] [Table 1]

[0070] In the example above (Table 1), there are three types of post-processing devices 40: a "first peripheral device," a "second peripheral device," and a "third peripheral device."

[0071] The following description will be given taking an example in which the timing for conveying the sheet S to the third nip-and-convey unit is set by distance, but the timing may also be set by time or the like.

[0072] The "invalid area" is an example of an area where inspection is invalid. The "invalid area" is, for example, the total distance of the first distance and the second distance, that is, the calculated value of the distance from the reading position 601 to the downstream gripping position 602. Specifically, in the case of the "first peripheral device," the "invalid area" is calculated as "40 mm + 100 mm = 140 mm."

[0073] The "invalid area" also includes a certain area in front of and behind the center distance. In the example above (Table 1), the "invalid area" is "±10 mm." Therefore, in the case of the "first peripheral device," the "invalid area" is "140 mm ±10 mm."

[0074] The "invalid area" is set as an area to be inspected at a time when a shock is likely to occur to the paper S by a peripheral device. Therefore, at times when a shock is likely to occur, abnormalities are likely to occur in the paper S, so the inspection is invalidated. In other words, in the "invalid area," the image reading device 30 stops the inspection, or ignores any abnormalities detected during the inspection.

[0075] The criteria for determining whether an inspection is invalid may be changed. For example, the inspection for the "invalid area" may be set to be performed using criteria different from those for other areas. Specifically, when inspecting color, the inspection is performed so that the "invalid area" is determined to be normal even if the difference between the ideal color and the color to be inspected is larger than that for other areas.

[0076] When inspecting the shape of the paper S, the sub-scanning magnification of the image to be inspected may change depending on whether the paper S is transported slowly or quickly. This makes it easier for the inspection to determine an abnormality. Therefore, it is desirable to set the image reading device 30 to have looser criteria for determining an abnormality than for other areas.

[0077] In this way, by disabling the inspection in consideration of the third pinching and conveying unit, it is possible to reduce false detections.

[0078] In the example above (Table 1), the "invalid area" is set based on the position of the third roller pair 303, but the "invalid area" may also be set based on the entrance of the post-processing device 40, etc.

[0079] The inspection criteria are set, for example, using a Graphical User Interface (GUI) such as the one below.

[0080] 7 is a diagram showing an example of a setting screen. For example, the criteria for an examination are set by a user's operation on a setting screen 701. The setting screen 701 is configured with an examination setting button 702, a reference image setting button 703, and a criteria setting button 704.

[0081] The test setting button 702 is a GUI that accepts an operation to switch whether or not to perform a test.

[0082] The reference image setting button 703 is a GUI for setting an image that serves as a reference for the inspection, that is, the input image data 201 .

[0083] The judgment criteria setting button 704 is a GUI for setting the inspection criteria. In the illustrated example, the inspection criteria are selected from three levels: "loose," "normal," and "strict." Note that the inspection criteria are not limited to three levels. In this way, if the inspection criteria can be set, it is possible to set standards that will not erroneously detect fibers, etc. in the paper S.

[0084] Furthermore, if it is possible to set areas where images are formed differently for each sheet S, such as addressees (so-called "variable areas"), to be excluded from inspection, convenience can be improved.

[0085] Based on the items set as described above, the sheet S is inspected for defects such as stains or missing images. The inspected sheet S is then discharged to a predetermined tray or the like. If the inspection determines that an abnormality has occurred, the image forming device 20 may perform image formation or the like on a sheet S that replaces the sheet S on which the defective image has been formed (this is known as recovery printing or the like).

[0086] The screen for making the settings is not limited to the configuration of the setting screen 701. In other words, the test criteria may be set by a setting method other than the setting screen 701.

[0087] [Third embodiment] Fig. 8 is a diagram showing an example in which a fourth clamping and conveying unit is provided. The following description will be given taking the image reading device 30 and the image forming device 20 shown in Fig. 1 as examples. For example, it is desirable for the image reading device 30 to change the area settings or inspection criteria, etc., taking into consideration peripheral devices such as the image forming device 20.

[0088] The image reading device 30 may inspect paper S on which an image has been formed by a device other than the image forming device 20. Furthermore, the device located upstream of the image reading device 30 may be a type other than an image forming device.

[0089] Specifically, this is an example in which the image forming device 20 includes a fourth roller pair 304 that is an example of a fourth nip-and-convey unit.

[0090] As in the second embodiment, a shock is likely to occur in the sheet S when the trailing edge thereof passes through the fourth roller pair 304. That is, when the trailing edge thereof is conveyed from the fourth roller pair 304, deformation of the sheet S is likely to occur when the sensor 203 reads it.

[0091] In particular, the shock is likely to be large if the force for conveying the paper S differs between the image reading device 30 and the image forming device 20. For example, if the roller pairs of the image reading device 30 and the image forming device 20 rotate at different speeds, the shock is likely to be large.

[0092] The image forming device 20 can be changed to various models. Therefore, depending on the model of the peripheral device, the distance from the gripping position of the fourth roller pair 304 (hereinafter referred to as "upstream gripping position 801") to the exit of the image forming device 20 may change.

[0093] For example, the distance from the upstream gripping position 801 to the exit of the image forming device 20 (hereinafter referred to as the "third distance 811") and the distance from the entrance of the image reading device 30 to the reading position 601 (hereinafter referred to as the "fourth distance 812") have the combinations shown below (Table 2).

[0094] [Table 2]

[0095] In the example above (Table 2), there are three types of image forming devices 20 or other types of devices: a "fourth peripheral device," a "fifth peripheral device," and a "sixth peripheral device."

[0096] The following describes an example in which the timing at which the sheet S is conveyed from the fourth nip-and-convey unit is set by distance, but the timing may also be set by time or the like.

[0097] The "invalid area" is an example of an area where inspection is invalid. The "invalid area" is, for example, the total distance of the third distance and the fourth distance, that is, the calculated value of the distance from the upstream gripping position 801 to the reading position 601. Specifically, in the case of the "fourth peripheral device," the "invalid area" is calculated as "40 mm + 90 mm = 130 mm."

[0098] The "invalid area" also includes a certain area in front of and behind the center distance. In the example above (Table 2), the "invalid area" is "±10 mm." Therefore, in the case of the "fourth peripheral device," the "invalid area" is "130 mm ±10 mm."

[0099] The "invalid area" is a timing when shocks are likely to occur to the paper S due to peripheral devices. Therefore, at times when shocks are likely to occur, abnormalities are likely to occur in the paper S, so the inspection is invalidated. In other words, in the "invalid area," the image reading device 30 stops the inspection, ignores any abnormalities detected during the inspection, or changes the criteria for determining an abnormality.

[0100] In this way, by disabling the inspection in consideration of the fourth pinch conveying unit and the like, it is possible to reduce false detections.

[0101] [Fourth embodiment] 9 is a diagram showing an example of double-sided printing. When forming images on both sides of a sheet of paper S, after forming an image on one side, the sensor 203 and the like inspect the side on which the image has been formed (hereinafter referred to as the "front side") as shown in the figure. After the inspection is complete, the sheet of paper S is turned over so that an image can be formed on and inspected on the side different from the front side (hereinafter referred to as the "back side"). Hereinafter, the conveying path that turns over the front and back sides is referred to as the "reverse path."

[0102] In double-sided printing, that is, when the paper S is turned over, the conveying direction is as follows.

[0103] In terms of the conveying direction, the direction in which the sheet S is conveyed at a position upstream of the first clamping and conveying unit is referred to as the "first direction S1." On the other hand, the direction in which the first clamping and conveying unit conveys the sheet S from the first clamping and conveying unit is referred to as the "second direction S2."

[0104] In the case of double-sided printing, the first direction S1 and the second direction S2 are different. Specifically, in the illustrated example, the first direction S1 is the direction in which the paper S is transported from right to left in the figure. On the other hand, the second direction S2 is the direction in which the paper S is transported from top to bottom in the figure. In this way, when double-sided printing is performed, the first direction S1 and the second direction S2 are different directions.

[0105] In terms of the conveying direction, the direction in which the sheet S is conveyed at a position downstream of the second clamping and conveying unit is referred to as the "third direction S3." On the other hand, the direction in which the second clamping and conveying unit conveys the sheet S from the second clamping and conveying unit is referred to as the "fourth direction S4."

[0106] In the case of double-sided printing, the third direction S3 and the fourth direction S4 are different. Specifically, in the illustrated example, the third direction S3 is the direction in which the paper S is transported from left to right in the figure. In other words, the third direction S3 is the direction toward a device that performs processing such as image formation in order to form an image on the back side. On the other hand, the fourth direction S4 is the direction in which the paper S is transported from top to bottom in the figure. In this way, the third direction S3 and the fourth direction S4 are different directions when double-sided printing is performed.

[0107] To turn over the sheet S from the front side to the back side, the image forming apparatus 1 transports the sheet S using, for example, a curved transport path as shown in the figure. The curved transport path is a transport path that turns over the sheet S. Note that the curvature and shape of the transport path are not limited to the example shown in the figure. For example, the curved transport path may be a transport path that is used when the height of the transport position between the image forming apparatus and a peripheral device is different.

[0108] In the reverse path, the sheet S is transported in the third direction S3. When this happens, a portion of the sheet S often bounces up near the sensor 203 (i.e., it is lifted up in the figure). Therefore, the distance between the sheet S and the sensor 203 becomes shorter. In particular, the sheet S is likely to bounce up once it passes through the first roller pair 301.

[0109] In this way, when the distance between the paper S and the sensor 203 changes, the brightness and the like change, and the appearance of the image may change. If there is such a change in color, the image reading device 30 may erroneously detect an abnormality.

[0110] Therefore, if the first direction S1 and the second direction S2 are different directions, or if the third direction S3 and the third direction S3 are different directions, the image reading device 30 will stop the inspection, ignore any abnormalities detected during the inspection, or change the criteria for determining an abnormality.

[0111] In this way, by taking the reverse path into consideration, the image reading device 30 can reduce false detections.

[0112] The degree to which the paper S bounces up differs depending on the type of paper S. Specifically, if the paper S is hard or thick, the paper S is more likely to bounce up. Therefore, the impact is likely to be greater. On the other hand, if the paper S is soft or thin, the paper S is more likely to deform along the reverse path.

[0113] Therefore, it is desirable for the image reading device 30 to change the criteria for determining an abnormality, taking into account the thickness, weight, or type of paper S (for example, whether it is a film medium such as an overhead projector (OHP) sheet, or metallic paper, etc.).

[0114] [Example of setting judgment criteria based on learning results] In order to set the criteria for determining whether something is normal or abnormal, the image reading device 30 is set in advance as follows.

[0115] 10 is a diagram showing an example of acquiring the paper level. Below, an example will be explained in which reading two types of paper S results in a first reading result 1001 and a second reading result 1002. Note that the reading is performed by transporting the paper S before image formation.

[0116] A first average value 1003 is the result of averaging the first reading result 1001 in the main scanning direction.

[0117] A second average value 1004 is the result of averaging the second reading result 1002 in the main scanning direction.

[0118] As shown by the first read result 1001 and the second read result 1002, the brightness differs for each type of paper S. Therefore, it is desirable to set the normal paper level separately for each type of paper S, such as the first average value 1003 and the second average value 1004.

[0119] For example, the image reading device 30 calculates average values ​​such as a first average value 1003 and a second average value 1004 to obtain reference values. In this way, since values ​​such as brightness differ for each sheet S, the brightness of characters and the like formed on the image also differs for each sheet S. Therefore, it is desirable that the criteria for determining whether something is abnormal or normal be set based on values ​​for each sheet S obtained in advance.

[0120] Fig. 11 is a diagram showing an example of changes in brightness. Below, an example will be described in which reading the brightness of paper S results in the reading result shown in the figure. Specifically, when reading paper S, it is assumed that there are relatively dark areas (hereinafter referred to as "dark areas 1101") and relatively bright areas (hereinafter referred to as "bright areas 1102").

[0121] The dark area 1101 and the bright area 1102 are caused by, for example, a change in the distance between the paper S and the sensor 203. Specifically, the dark area 1101 is an area where the brightness is lower than the average value. On the other hand, the bright area 1102 is an area where the brightness is higher than the average value.

[0122] Fig. 12 is a diagram showing an example of the reading result. The reading values ​​are averaged in the main scanning direction in the state where there are changes shown in Fig. 11. The reading result will have the following distribution, for example.

[0123] The read value obtained by reading the dark region 1101 (hereinafter referred to as the "first read value 1202") is lower than the average value or the like.

[0124] The read value obtained by reading the bright region 1102 (hereinafter referred to as "second read value 1203") is higher than the average value or the like.

[0125] For such reading results, an example will be described in which a range determined to be normal is set in advance as a "normal range 1201." For example, the normal range 1201 is determined by a tolerance value or the like that is set in advance for an average value or the like.

[0126] Since the normal range 1201 is determined by an average value or the like, it is possible to reduce the effect of changes in brightness for each sheet S. On the other hand, if there is a sudden change such as the first read value 1202 and the second read value 1203, the read value may fall outside the normal range 1201. If such a read value occurs, the image reading device 30 may determine that there is an abnormality even if there is no dirt or the like, that is, may make a false detection.

[0127] Therefore, it is desirable to set the criteria for determining whether something is normal or abnormal by learning the reading results in advance. Note that learning may be performed separately for the type, size, thickness, etc. of the paper S. For example, learning may be achieved by artificial intelligence (AI) or the like.

[0128] Fig. 13 is a diagram showing an example of setting a normal range based on the learning results. Compared to Fig. 12, Fig. 13 differs in that the normal range 1201 is set differently near the first read value 1202 and the second read value 1203.

[0129] For example, assume that the background is black. The brightness shown in FIG. 11 is acquired by a line sensor or the like. The boundary between the paper S and the background is determined by the difference in the brightness of the reflected light, etc. Therefore, the area of ​​the paper S is identified.

[0130] Learning is performed so that a read value that changes suddenly, such as the first read value 1202 and the second read value 1203, is not determined to be abnormal. Specifically, the image reading device 30 scans the paper S in advance to acquire a profile. Once such a profile is acquired, the image reading device 30 can learn changes in brightness, etc. Once learning is performed, the image reading device 30 can set a wider normal range based on the learning results, as shown in FIG. 13. Therefore, the image reading device 30 can reduce false detections.

[0131] Furthermore, based on the learning results, the image reading device 30 may change the determination criteria as follows.

[0132] 14 is a diagram showing an example of changing the judgment criteria based on the learning results. Below, an example will be described in which the same results as in FIG. 12 are obtained.

[0133] The area around where the first read value 1202 is obtained is called the "first read area 1401." The area around where the second read value 1203 is obtained is called the "second read area 1402." The area that is neither the first read area 1401 nor the second read area 1402 is called the "third read area 1403."

[0134] Based on the learning result, the image reading device 30 judges the first reading area 1401 and the second reading area 1402 using different criteria than the third reading area 1403. Specifically, the image reading device 30 inspects the first reading area 1401 and the second reading area 1402 at an inspection level different from that of the third reading area 1403.

[0135] There are cases where a specific region has a higher number of false positives than the overall average. Hereinafter, the region with a higher number of false positives will be referred to as the "specific region." In other words, the specific region is a region where the test is more likely to produce poor results than regions other than the specific region.

[0136] For example, the specific area may be determined or estimated based on a mechanical layout or the like. That is, the specific area can often be identified at the design stage or the like. Therefore, the specific area is identified during the design stage, and the image reading device 30 stores the specific area in advance. For example, the image reading device 30 stores the specific area in the form of table data or the like.

[0137] The image reading device 30 may change the standard depending on the specific area. Specifically, the image reading device 30 sets the inspection level to "99%" for 40 mm from the leading edge of the paper S. On the other hand, the image reading device 30 sets the inspection level to "100%" for other areas. In this way, the image reading device 30 sets the standard for the specific area to be lower than the standard for areas other than the specific area.

[0138] Furthermore, when calculating the average value, the image reading device 30 may perform the calculation by excluding the specific region.

[0139] In this way, by performing an inspection based on a specific region, the image reading device 30 can reduce false detections.

[0140] [Example of guide installation] It is desirable that the image reading device 30 is provided with a guide 2001. For example, the guide 2001 is installed at a position shown in Fig. 6, Fig. 8, Fig. 9, etc. The presence of the guide 2001 can prevent the paper S from flapping. Therefore, the presence of the guide 2001 allows the paper S to be transported stably, allowing the image reading device 30 to perform inspection with high accuracy.

[0141] [Variations] Fig. 15 is a diagram showing a first modified example of the image reading device. Fig. 15 is a side view. The image reading device 30 may have the following configuration.

[0142] The image reading device 30 includes a plurality of image pickup elements 11a, an irradiation device 11b, and a contact glass 12. The image reading device 30 also includes a first conveyor roller 14 and a second conveyor roller 15.

[0143] The irradiation device 11b irradiates light onto the sheet material passing through the reading position.

[0144] The image pickup element 11a performs photoelectric conversion for each pixel to generate image data. The image pickup elements 11a are arranged one-dimensionally in a direction perpendicular to the transport direction to form a line image sensor.

[0145] The revolver 13 is disposed at a position opposite to the image pickup element 11a across the conveyance path, and reflects the light irradiated onto the sheet material when reading the image.

[0146] The contact glass 12 is disposed at a position facing the revolver 13. The contact glass 12 is a transparent member. The contact glass 12 transmits the irradiated light, the light reflected by the revolver 13, and the light reflected by the sheet material.

[0147] The first conveyor roller 14 and the second conveyor roller 15 are rotated by a drive motor. Note that, for cleaning and the like, the first conveyor roller 14 and the second conveyor roller 15 may have different conveying speeds.

[0148] 16 is a diagram showing a second modified example of the image reading device. The image forming device and the image reading device may have the following configuration.

[0149] The control device 150 controls the overall operation of the image forming apparatus 1 and controls the process of forming an image on the paper S. The control device 150 may also include a cleaning control device and the like.

[0150] The photosensitive drums 112 are arranged to correspond to the image forming process using yellow (Y), magenta (M), cyan (C), and black (K) toners, which are image forming materials (for example, toners) of each color. For example, the photosensitive drums 112 are arranged along the intermediate transfer belt 111.

[0151] The intermediate transfer belt 111 is wound around a drive roller and multiple driven rollers. An image (toner image) developed on the photosensitive drum 112 is transferred onto the intermediate transfer belt 111. The intermediate transfer belt 111 also moves between a primary transfer position and a secondary transfer position where the toner image is transferred onto the paper S.

[0152] At the secondary transfer position, a transfer roller 113a and an opposing roller 113b are disposed. At the secondary transfer position, a toner image is transferred from the intermediate transfer belt 111 to the paper S. Between the transfer roller 113a and the opposing roller 113b, the intermediate transfer belt 111 and the paper S are sandwiched, and a gap is formed large enough to allow the paper S to pass through. The paper S is sandwiched in this gap, and the image is transferred onto the paper S while it is transported in the transport direction (i.e., the sub-scanning direction).

[0153] The sheets S are supplied from the first supply tray 121A or the second supply tray 121B.

[0154] The sheet S, on whose front surface an image has been formed, has the image fixed by a fixing roller 123. After fixing, the sheet S is transported to a transport path switching device 124. The sheet S then reverses its traveling direction and is transported to a reversing path 125. Next, an image is formed on the back surface of the sheet S. In addition, fixing, inspection, etc. are also performed on the back surface in the same manner as on the front surface.

[0155] 17 is a diagram showing a third modified example of an image reading device, in which the configuration of the image reading device 30 is different from that shown in FIG.

[0156] FIG. 18 is a diagram showing an example of a first-side reading device and a second-side reading device. Hereinafter, the reading device placed upstream will be referred to as "second-side reading device 130b." On the other hand, the reading device placed downstream will be referred to as "first-side reading device 130a." Hereinafter, an example will be described in which the first-side reading device 130a and the second-side reading device 130b are the same hardware.

[0157] The first surface reading device 130a includes an image pickup element 11a, an irradiation device 11b, a revolver 13, a first conveying roller 14, a second conveying roller 15, and the like.

[0158] The first-side reading device 130a reads the image in accordance with the movement of the paper S passing through the reading position. In the illustrated example, the first-side reading device 130a reads the image formed on the front side, and the second-side reading device 130b reads the image formed on the back side.

[0159] The revolver 13 reflects the light that is irradiated onto the paper S when the image is read.

[0160] The first transport roller 14 transports the paper S by rotating the first drive roller 14a.

[0161] The second transport roller 15 transports the paper S by rotating the second drive roller 15a.

[0162] The first side reader 130a preferably includes a guide 2001.

[0163] The image reading device 30 includes a first side reading device 130a and a second side reading device 130b. With the first side reading device 130a and the second side reading device 130b, the front and back sides can be read almost simultaneously.

[0164] The first side reading device 130a and the second side reading device 130b may be arranged in the reverse order.

[0165] [Example of functional configuration] 19 is a diagram showing an example of a functional configuration. For example, the image reading device 30 includes an image reading unit 30F1, an output unit 30F2, and a setting unit 30F3. The image reading device 30 may further include a transmission unit 30F4, an operation unit 30F5, and a learning unit 30F6.

[0166] The image reading unit 30F1 performs an image reading procedure for reading an image from a recording medium. For example, the image reading unit 30F1 is realized by the sensor 203 or the like.

[0167] The output unit 30F2 performs an output procedure of inspecting the image based on the second region and outputting the inspection result. For example, the output unit 30F2 is realized by the CPU 32 or the like.

[0168] The setting unit 30F3 performs a setting procedure to exclude the first area from the area to be inspected and set the second area based on the position of the recording medium relative to the reading position or the type of the recording medium. For example, the setting unit 30F3 is realized by the CPU 32 or the like.

[0169] The transmission unit 30F4 performs a transmission procedure for transmitting the test results to the operation unit 30F5 or the display terminal 50. For example, the transmission unit 30F4 is realized by a communication device or the like.

[0170] The operation unit 30F5 performs an operation procedure for inputting an operation by the user or outputting a screen to the user. For example, the operation unit 30F5 is realized by the operation display device 25 or the like.

[0171] The learning unit 30F6 performs a learning procedure for learning the read result. For example, the learning unit 30F6 is realized by the CPU 32 or the like.

[0172] The display terminal 50 is an information processing device such as a personal computer (PC) or a tablet connected via a network or a cable.

[0173] The image reading device 30 excludes the first area from the area to be inspected and sets the second area. When inspection is performed based on the second area set in this manner, the image reading device 30 can reduce false positives in the image inspection.

[0174] [Overall processing example] FIG. 20 is a diagram illustrating an example of the overall processing.

[0175] In step S2001, the image reading device 30 excludes the first area from the area to be inspected and sets the second area.

[0176] In step S2002, the image reading device 30 reads the image formed on the recording medium.

[0177] In step S2003, the image reading device 30 inspects the image based on the second region and outputs the inspection result.

[0178] [Other embodiments] The image forming apparatus is not limited to the configuration described above. For example, the image forming apparatus may include devices other than those shown above. Furthermore, the arrangement of each device may be different from that shown in the drawings.

[0179] The recording medium may be, for example, other than paper S (also referred to as "plain paper"). For example, the recording medium may be coated paper, label paper, an overhead projector sheet, film, a flexible thin plate, or the like. That is, the recording medium may be made of any material to which ink droplets can adhere, be temporarily adhered, adhere and fix, or adhere and penetrate. Specifically, the recording medium may be a recording medium such as paper, film, or cloth, an electronic circuit board, an electronic component such as a piezoelectric element (also referred to as a "piezoelectric member"), a powder layer (also referred to as a "powder layer"), an organ model, or a test cell. Thus, the recording medium may be made of any material to which a liquid can adhere, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or a combination thereof.

[0180] The device may be a plurality of devices. That is, each device may be configured to perform distributed, redundant, or parallel processing using a plurality of devices. On the other hand, each device may be integrated. That is, the plurality of devices described above may be realized by a single device.

[0181] The image reading method as described above may be realized by an image reading program. That is, the image reading program causes devices such as an arithmetic unit, a control unit, and a storage unit provided in a computer to cooperate with each other to realize the image reading method. The image reading program may also be distributed via a computer-readable recording medium or a telecommunications line.

[0182] The above-described embodiment shows a preferred example, but a person skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0183] 1: Image forming device 25:Operation display device 30: Image reader 30F1: Image reading unit 30F2: Output section 30F3: Setting section 30F4: Transmitter 30F5 :Operation unit 30F6: Learning Department 31: Output image reader 40: Post-processing device 50: Display terminal 201: Input image data 202: Read image data 203: Sensor S: Paper [Prior art documents] [Patent documents]

[0184] [Patent Document 1] Japanese Patent Publication No. 2020-053761

Claims

1. an image reading unit that reads an image from a recording medium; an output unit that inspects the image and outputs the inspection result; a setting unit that excludes a first area, which is a predetermined area of ​​the recording medium, from an area to be inspected by the output unit, and sets a second area excluding the first area, based on the position of the recording medium relative to a reading position where the image reading unit reads the image, or the type of the recording medium; a first nipping and conveying unit that nip and conveys the recording medium at a position upstream of the image reading unit in a recording medium conveying direction; a second nipping and conveying unit that nip and conveys the recording medium at a position downstream of the image reading unit in a recording medium conveying direction; Equipped with The output unit When the recording medium is being clamped by either the first clamping and conveying unit or the second clamping and conveying unit, the inspection result is output based on the second area. An image reading device characterized by:

2. a first direction in which the recording medium is conveyed to the first nip-and-convey unit and a second direction in which the recording medium is conveyed from the first nip-and-convey unit are different from each other; Or, a third direction in which the recording medium is conveyed to the second nip-and-convey unit and a fourth direction in which the recording medium is conveyed from the second nip-and-convey unit are different from each other; 2. The image reading device according to claim 1.

3. a third nipping and conveying unit that nip and conveys the recording medium at a position downstream of the second nipping and conveying unit in a recording medium conveying direction, The output unit Invalidating the inspection at the timing when the recording medium is conveyed to the third nip-and-convey section.

3. The image reading device according to claim 1 or 2.

4. a fourth nipping and conveying unit that nip and conveys the recording medium at a position upstream of the first nipping and conveying unit in a recording medium conveying direction, The output unit Invalidating the inspection at the timing when the recording medium is conveyed from the fourth pinch conveyance unit The image reading device according to any one of claims 1 to 3.

5. a learning unit that learns the reading result by the image reading unit, The output unit Based on the learning result by the learning unit, a criterion is set for determining whether the test result is abnormal or normal.

5. The image reading device according to claim 1.

6. The image reading unit reading images from a plurality of said recording media; The learning unit Learning for each of the recording media, The criteria are changed for each recording medium.

6. The image reading device according to claim 5.

7. storing the specific area where the test results are poor; The output unit The criteria for determining whether the test result for the specific region is abnormal or normal are set differently from those for regions other than the specific region.

7. The image reading device according to claim 1.

8. An image forming apparatus comprising the image reading device according to any one of claims 1 to 7.

Images