Image forming apparatus

Abstract

To prevent a failure in calibration of an image forming apparatus by promoting optimization of sheet reading conditions for calibration.SOLUTION: An image forming apparatus comprising: an image forming unit; a calibration unit configured to execute calibration of the image forming unit based on a chart image formed by the image forming unit; and a reading unit configured to read a sheet on which the chart image is formed according to at least one reading condition while conveying the sheet along a conveyance path, the image forming apparatus includes a reading unit configured to generate a read image including the chart image, and a control unit configured to determine whether the sheet is normally read by the reading unit based on the read image, wherein the control unit is configured to output a notification for prompting a user to adjust the at least one reading condition when it is determined that the sheet is not normally read by the reading unit.SELECTED DRAWING: Figure 15

Description

[Technical Field]

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

[0002] Conventionally, in order to calibrate parameters such as the position on a sheet where an image is formed by an image forming device, a known chart image is formed on a sheet, and the sheet is read by a scanner to determine image misalignment, etc. For example, Patent Document 1 discloses a technique in which a chart image includes a marker having an edge that is not parallel to any edge of the sheet. By using the chart image of Patent Document 1, it is possible to accurately detect the target marker and perform calibration of the image forming device even if the read image contains streak-like noise.

[0003] The scanner of the image forming apparatus disclosed in Patent Document 1 is equipped with an ADF (Auto Document Feeder). When a user places a sheet on a document tray on which a chart image for calibration is formed, the sheet is automatically transported by the ADF and read by the scanner, and calibration is performed based on the read image. However, this reading process is prone to abnormalities such as sheet misalignment or skew.

[0004] Patent Document 2 discloses a technique in which, when it is determined that an abnormality has occurred during the automatic conveyance of a proofreading sheet, the user is instructed to re-place the sheet on the document tray and retry reading. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-118056 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-329929 Summary of the Invention [Problem to be solved by the invention]

[0006] Components such as the transport rollers and reading sensors of scanners equipped with ADFs have inherent variations in characteristics, including installation tolerances. Typically, adjustments to the reading conditions (for example, physical adjustments using adjustment screws and adjustments to settings such as the reading start position and motor rotation speed) are performed at the factory before the product is shipped to reduce the effects of such variations. However, aging of the components or vibrations, shocks, or excessive loads during device relocation can cause the component characteristics to deviate from their normal ranges. When such deviations occur, even if the user reloads the sheet on the document tray and tries scanning again, the abnormality remains, and the appropriate parameter values ​​for calibration cannot be obtained, resulting in unsuccessful calibration of the image forming device.

[0007] In view of the above, the present invention aims to provide a mechanism that can promote optimization of sheet reading conditions for calibration and prevent failure in calibration of an image forming apparatus. [Means for solving the problem]

[0008] According to one aspect, there is provided an image forming apparatus comprising: an image forming means; a calibration means for calibrating the image forming means based on a chart image formed by the image forming means; a reading means for reading a sheet on which the chart image is formed while transporting the sheet along a transport path in accordance with at least one reading condition, thereby generating a read image including the chart image; and a control means for determining based on the read image whether the sheet has been read normally by the reading means, wherein the control means outputs a notification urging a user to adjust the at least one reading condition if it is determined that the sheet has not been read normally by the reading means. [Effects of the Invention]

[0009] According to the present invention, it is possible to promote optimization of the sheet reading conditions for calibration, and prevent failure in calibration of the image forming apparatus. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a scanner according to an embodiment. [Figure 3A] FIG. 2 is a block diagram showing an example of the configuration of a printer control unit. [Figure 3B] FIG. 2 is a block diagram showing an example of the configuration of a scanner control unit. [Figure 3C] FIG. 2 is a block diagram showing an example of the configuration of a controller. [Figure 4] FIG. 10 is an explanatory diagram showing an example of a chart configuration. [Figure 5] FIG. 6 is an explanatory diagram for measuring an image forming position based on a chart image. [Figure 6] FIG. 10 is an explanatory diagram for determining an abnormality regarding the reading start position. [Figure 7] FIG. 10 is an explanatory diagram for determining an abnormality related to the scanning magnification. [Figure 8] 10A and 10B are further explanatory diagrams for determining whether an abnormality has occurred in a chart image. [Figure 9] FIG. 4 is an explanatory diagram showing an example of the configuration of a first notification screen. [Figure 10] FIG. 4 is an explanatory diagram showing an example of the configuration of an ADF adjustment screen. [Figure 11] 10A and 10B are explanatory diagrams for determining an abnormality in a chart image that cannot be resolved by adjustment according to a user operation. [Figure 12] FIG. 10 is an explanatory diagram showing an example of the configuration of a second notification screen. [Figure 13] 10A and 10B are explanatory diagrams for determining whether an abnormality in a chart image is caused by an operational error. [Figure 14] FIG. 10 is an explanatory diagram showing an example of the configuration of a third notification screen. [Figure 15] 10 is a flowchart showing an example of a schematic flow of a calibration process according to an embodiment. [Figure 16A] 10 is a first half of a flowchart showing an example of a detailed flow of an adjustment determination process according to an embodiment. [Figure 16B]10 is the second half of a flowchart showing an example of a detailed flow of an adjustment determination process according to an embodiment. [Figure 17] 10 is a flowchart showing an example of a detailed flow of a notification process according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] <1. Equipment Overview> This section provides an overview of an image forming apparatus 1 as an example of an apparatus to which the technology of the present disclosure can be applied. FIG. 1 is a configuration diagram showing an example of the configuration of an image forming apparatus 1 according to an embodiment. In the example of FIG. 1, the image forming apparatus 1 is a so-called multifunction peripheral. The image forming apparatus 1 includes an operation unit 10, a communication interface 20, a controller 50, a printer 100, and a scanner 200.

[0013] <1-1. Operation unit> The operation unit 10 is an operation means that provides a user interface (UI) to a user of the image forming apparatus 1. The operation unit 10 includes, for example, input devices such as a touch panel, buttons, and switches, and output devices such as a display, lights, and speakers.

[0014] <1-2. Communication Interface> The communication interface 20 is a communication means for the image forming apparatus 1 to communicate with other devices. The communication interface 20 may be a wired communication interface or a wireless communication interface.

[0015] <1-3. Controller> The controller 50 is a control unit that controls the overall functions of the image forming apparatus 1. The controller 50 controls the execution of various jobs in cooperation with the printer control unit 150 of the printer 100 and the scanner control unit 250 of the scanner 200 in response to instructions input via the operation unit 10 or the communication interface. For example, when a copy job is instructed, the controller 50 controls the printer 100 to have the scanner 200 read an original document and form an image on a sheet based on the read image data generated by the scanner control unit 250. When a print job is instructed, the controller 50 controls the printer 100 to form an image on a sheet based on print image data received via the communication interface. When a scan job is instructed, the controller 50 controls the scanner 200 to read an original document and store the read image data generated by the scanner control unit 250 in internal storage or transmit it to an external device via the communication interface. Specific configurations of the controller 50, printer control unit 150, and scanner control unit 250 will be described in more detail below.

[0016] <1-4. Printer> The printer 100 is an image forming unit that forms an image on a sheet (also referred to as a recording medium). In this embodiment, an example in which the printer 100 forms a monochrome image using an electrophotographic method will be mainly described. However, the technology according to the present disclosure is not limited to this example and can also be applied to an image forming apparatus that forms a color image (for example, using an offset printing method). The technology according to the present disclosure can also be applied to an image forming apparatus that operates using other image forming methods, such as an inkjet method. The printer 100 includes a conveying unit 110, an image forming unit 120, a fixing unit 140, and a printer control unit 150.

[0017] The conveying section 110 includes cassettes 111a to 111d, a manual feed tray 111e, a number of rollers involved in feeding and conveying sheets, conveying paths 115a to 115c, and an output tray 118. The cassettes 111a to 111d are storage units capable of storing stacks of sheets of different sizes. The pickup rollers 112a to 112d pick up sheets from the stacks of sheets stored in the corresponding cassettes 111a to 111d and feed the sheets to the conveying path 115a. The feed roller 112e feeds sheets placed on the manual feed tray 111e to the conveying path 115a. The feed roller 113 and the retard roller 114 separate the fed sheets one by one to prevent double-feeding of sheets. The pair of registration rollers 116 stops the leading edge of the conveyed sheet P, corrects any skew of the sheet P, and sends the sheet P to a transfer position in accordance with the operation of an image forming unit 120, which will be described later.

[0018] The image forming unit 120 includes a photosensitive drum 121, a charger 122, an exposure unit 123, a developing unit 124, a transfer roller 125, and a cleaner 126. The photosensitive drum 121 is an image carrier that can rotate clockwise in the drawing. The charger 122 uniformly charges the surface of the photosensitive drum 121. The exposure unit 123 exposes the surface of the photosensitive drum 121 to laser light in accordance with image data input from the printer control unit 150, forming an electrostatic latent image on the surface of the photosensitive drum 121. The developing unit 124 contains a developer (e.g., a two-component developer containing toner and carrier) and supplies the developer to the surface of the photosensitive drum 121 to develop the electrostatic latent image and form a toner image. A bias voltage is applied to the transfer roller 125, which transfers the toner image on the surface of the photosensitive drum 121 to the sheet P that has reached the transfer position. The sheet P onto which the toner image has been transferred is further transported toward a fixing unit 140 disposed downstream of the transfer position. A cleaner 126 removes toner remaining on the surface of the photosensitive drum 121.

[0019] The fixing section 140 is a fixing means for fixing the toner image onto the sheet P. The toner of the toner image is heated and melted by the heating roller of the fixing section 140, and is then pressed by the pressure roller to be fixed to the sheet. The pair of rollers of the fixing section 140 sandwich the sheet P and transport it further downstream. The pair of discharge rollers 117 discharges the sheet P onto a discharge tray 118 after image formation is completed.

[0020] When double-sided printing is performed, the sheet P with a toner image formed on its first side is conveyed to conveyance path 115b. In conveyance path 115b, the traveling direction of the sheet P is reversed. The sheet P passes through double-sided conveyance path 115c and returns to conveyance path 115a with the front and back sides inverted. When the sheet P reaches the transfer position again, the toner image is transferred to the second side of the sheet P. The fixing unit 140 heats and presses the sheet P again to fix the toner image to the second side. The sheet P is then discharged to the discharge tray 118.

[0021] <1-5.Scanner> The scanner 200 is a reading unit that reads a document and generates a read image. In this embodiment, the scanner 200 is composed of a main body 201 and a cover 202. The cover 202 is hingedly connected to the main body 201 and can be opened and closed. When a user opens the cover 202, a document table 203 on the top surface of the main body 201 is exposed. The cover 202 incorporates an ADF 210, which will be described later. A document to be read by the scanner 200 is placed on the document table 203 by the user or set in a document tray 204. The ADF 210 transports the document set in the document tray 204 along an internal transport path and discharges it to a discharge tray 205. A line sensor 225, which will be described later, optically reads the document placed on the document table 203 or the document being transported by the ADF 210. An example of a more specific configuration of the scanner 200 will be further described in the next section.

[0022] <2. Detailed configuration of the scanner> Fig. 2 is a diagram showing an example of the configuration of a scanner 200 according to an embodiment. Referring to Fig. 2, the main body 201 includes a document table glass 203a, a flow reading glass 206, a motor 207, a timing belt 208, a guide 209, a first reading unit 220, and a scanner control unit 250. The cover 202 includes a document tray 204, an output tray 205, an ADF 210, and a second reading unit 230. The document tray 204 has a pair of regulating plates 204a and a width sensor 204b. The ADF 210 is arranged along the conveying path D2 and includes a number of rollers and sensors involved in conveying the document.

[0023] When scanning a document placed on the document platen glass 203a, the scanner control unit 250 rotates the motor 207. A timing belt 208 transmits the driving force of the motor 207 to the first scanning unit 220, which moves in the sub-scanning direction (direction D1 in the figure) along a guide 209. The first scanning unit 220 includes an illumination unit 221, an optical system 223, and a line sensor 225. The illumination unit 221 may include, for example, one or more light-emitting diodes (LEDs) and emits light toward the document. The optical system 223 includes multiple lenses and mirrors and focuses light reflected from the first surface (front surface) of the document onto the light-receiving surface of the line sensor 225. The line sensor 225 is a collection of image sensors arranged for each pixel along the main scanning direction (depth direction in the figure). The image sensor here may be, for example, a photoelectric conversion element such as a CCD (Charge Coupled Device). Furthermore, a CIS (Contact Image Sensor) may be used instead of a CCD. The line sensor 225 reads light from the first side of the document line by line while the first reading unit 220 is moving in the sub-scanning direction, and generates a read image of the first side.

[0024] When a user places one or more documents on document tray 204, the user adjusts the position of restriction plates 204a so that the spacing between restriction plates 204a matches the width of the documents in the main scanning direction. Width sensor 204b detects the spacing between restriction plates 204a as the width of the documents. When reading a document transported by ADF 210, scanner control unit 250 drives a transport motor (not shown) to rotate the rollers of ADF 210. Pickup roller 211 contacts the top surface of the document stack and feeds the documents one by one to transport path D2. Separation roller 212 separates the fed document from the remaining documents.

[0025] The separation sensor 213 detects the leading and trailing edges of the document conveyed along the conveying path D2. The length of the document can be determined from the time difference between the detection of the leading and trailing edges of the document by the separation sensor 213. The leading edge of the document abuts against the nip position of the registration roller pair 214, thereby correcting any skew of the document. The registration roller pair 214 conveys the document further downstream toward the first reading position R1. A lead sensor 215 is disposed downstream of the registration roller pair 214. The lead sensor 215 detects the leading edge of the document. The scanner control unit 250 determines the timing at which the first reading unit 220 (and the second reading unit 230) should start reading the document based on the timing at which the lead sensor 215 detects the leading edge of the document. A skew sensor 219 is also disposed near the separation sensor 213. The skew sensor 219 detects the degree of skew of the document during conveyance (the angle relative to the conveyance direction).

[0026] The first read roller pair 216 sends the document to the first reading position R1. A flow reading glass 206 is disposed below the first reading position R1, and the first reading unit 220 is located further below the flow reading glass 206. While the document passes through the first reading position R1, the line sensor 225 of the first reading unit 220 reads the light emitted from the illumination 221 and reflected from the first surface of the document, line by line, to generate a read image of the first surface. Next, the second read roller pair 217 sends the document to the second reading position R2.

[0027] The second reading unit 230 is located above the second reading position R2. When double-sided reading is instructed, the second reading unit 230 performs reading in addition to the first reading unit 220. The second reading unit 230 includes an illumination unit 231, an optical system 233, and a line sensor 235. The illumination unit 231 may include, for example, one or more LEDs and emits light toward the original. The optical system 233 includes multiple lenses and mirrors and forms an image of light reflected from the second side (back side) of the original on the light-receiving surface of the line sensor 235. The line sensor 235 is a collection of image sensors arranged for each pixel along the main scanning direction. While the original passes through the second reading position R2, the line sensor 235 reads the light reflected from the second side of the original line by line to generate a read image of the second side. The original that has passed the second reading position R2 is discharged to the discharge tray 205 by a pair of discharge rollers 218.

[0028] The photoelectric conversion elements on the light receiving surfaces of the line sensor 225 of the first reading unit 220 and the line sensor 235 of the second reading unit 230 convert the received light into electrical signals, which become analog image signals representing the read image. The line sensors 225 and 235 are each mounted on a sensor board (not shown). The analog image signals are output from the sensor board to the scanner control unit 250 and converted into digital read image data by an analog-to-digital conversion unit (ADC) 259 (described later).

[0029] <3. Control function configuration> In this section, an example of a configuration related to the control function of the image forming apparatus 1 will be described with reference to FIGS. 3A to 3C.

[0030] <3-1. Printer control unit> 3A is a block diagram showing an example of the configuration of printer control unit 150. Printer control unit 150 includes a central processing unit (CPU) 151, read-only memory (ROM) 152, random access memory (RAM) 153, image memory 154, image processing unit 155, sensor I / F 156, drive control unit 157, exposure control unit 158, and setting holding unit 159.

[0031] The CPU 151 controls the image forming operation of the printer 100 by executing a control program stored in the ROM 152. The CPU 151 is connected to the controller 50 via a signal line. The RAM 153 provides the CPU 151 with a temporary storage area for calculations. The image memory 154 is a memory for storing input image data. The image processing unit 155 performs image processing such as rasterization, gamma correction, and binarization on the input image data prior to execution of a job.

[0032] The sensor interface (I / F) 156 is an interface for connecting various sensors included in the printer 100 to the CPU 151. For example, the sensor I / F 156 acquires sheet detection signals indicating the presence or absence of a sheet and the sheet size from sheet sensors arranged in the cassettes 111a to 111d, and outputs the acquired sheet detection signals to the CPU 151. The drive control unit 157 controls the driving of various actuators (e.g., motors and clutches) included in the printer 100. The exposure control unit 158 ​​controls the exposure of the photosensitive drum 121 by the exposure unit 123 in accordance with input image data processed by the image processing unit 155.

[0033] The setting storage unit 159 stores various settings for the image forming operation. For example, the setting storage unit 159 stores the following setting values ​​related to calibration of the image forming position: -Offset of the starting position in the main scanning direction (in pixels) - Offset of the writing position in the sub-scanning direction (in pixels) -Magnification rate in the main scanning direction (%) Magnification in the sub-scanning direction (%) These setting values ​​may be stored separately for the image forming operation on the first side of the sheet and the image forming operation on the second side of the sheet. The drive control unit 157 and the exposure control unit 158 ​​adjust the image forming position on the sheet in the main scanning direction and the sub-scanning direction according to the setting values ​​stored in the setting storage unit 159. For example, the exposure start position on the surface of the photosensitive drum 121 may be offset, or the exposure range may be expanded or reduced.

[0034] <3-2.Scanner control unit> 3B is a block diagram showing an example of the configuration of the scanner control unit 250. The scanner control unit 250 includes a CPU 251, a ROM 252, a RAM 253, a lighting control unit 254, a scanning control unit 255, a reading control unit 256, a sensor I / F 257, a timer 258, an ADC 259, an image processing unit 260, a shading circuit 261, and a reading condition holding unit 262.

[0035] The CPU 251 controls the reading operation of the scanner 200 by executing a control program stored in the ROM 252. The CPU 251 is connected to the controller 50 via a signal line. The RAM 253 provides the CPU 251 with a temporary storage area for calculations.

[0036] The lighting control unit 254 controls the lighting of the illumination 221 of the first reading unit 220 and the lighting of the illumination 231 of the second reading unit 230. The scanning control unit 255 controls the movement of the first reading unit 220 in the direction D1 and the transport of the document along the transport path D2 of the ADF 210. The reading control unit 256 controls the reading of the first side of the document by the line sensor 225 of the first reading unit 220 and the reading of the second side of the document by the line sensor 235 of the second reading unit 230.

[0037] For example, when reading a document placed on the document glass 203a, the scanning control unit 255 controls the driving of the motor 207 so that the first reading unit 220 moves in the sub-scanning direction at a predetermined moving speed. The lighting control unit 254 turns on the illumination 221 to irradiate the first side of the document with light while the first reading unit 220 moves under the document glass 203a. The reading control unit 256 causes the line sensor 225 to read each line of the first side of the document at intervals corresponding to the specified reading resolution.

[0038] In addition, in the case of skimming, the scanning control unit 255 controls the driving of motors connected to the rollers of the ADF 210 so that the rollers of the ADF 210 transport the document along the transport path D2 at the appropriate timing. The lighting control unit 254 turns on the light 221 to irradiate the first side of the document with light while the document is passing through the first reading position R1. The reading control unit 256 causes the line sensor 225 to read each line of the first side of the document when the line passes through the first reading position R1. In addition, when double-sided reading is instructed, the lighting control unit 254 turns on the light 231 to irradiate the second side of the document with light while the document is passing through the second reading position R2. The reading control unit 256 causes the line sensor 235 to read each line of the second side of the document when the line passes through the second reading position R2.

[0039] The sensor I / F 257 is an interface for connecting various sensors included in the scanner 200 to the CPU 251. For example, in the case of skimming, the CPU 251 can determine the size of the document, i.e., the width and length of the document, based on sensor signals input from the width sensor 204b and the separation sensor 213. Note that the CPU 251 may determine the size of the document based on a user input acquired via the operation unit 10, instead of determining the size of the document based on the sensor signals.

[0040] Furthermore, the CPU 251 can determine the timing at which the line sensors 225 and 235 should perform reading based on the document detection signal input from the lead sensor 215. The timer 258 is used to measure the time from when the lead sensor 215 detects the leading edge of the document until the leading edge of the document reaches the first reading position R1 and the second reading position R2. The timer 258 may, for example, count pulses of a periodic pulse signal based on the rotation of a motor involved in transporting the document. The CPU 251 can determine the movement distance of the document along the transport path D2 based on the number of pulses counted by the timer 258.

[0041] The ADC 259 performs AD conversion on the analog image signals input from the line sensors 225 and 235 and outputs the digital read image data to the image processing unit 260. The image processing unit 260 performs image processing on the read image data, such as noise removal, resolution conversion, and skew correction. The shading circuit 261 performs shading correction on the read image data processed by the image processing unit 260. Although not shown in FIG. 3B , the shading circuit 261 may have a memory that stores a coefficient set and a target value for shading correction that are determined in advance depending on the characteristics of the first reading unit 220 and the second reading unit 230.

[0042] The reading condition storage unit 262 stores at least one reading condition for when the scanner 200 reads a document. For example, the reading condition stored by the reading condition storage unit 262 may include at least one of the following conditions C1 to C6: C1) Reading start position in the main scanning direction perpendicular to the sheet conveyance direction C2) Reading start position in the sub-scanning direction parallel to the sheet transport direction C3) Scanning magnification in the main scanning direction C4) Scanning magnification in the sub-scanning direction C5) Amount of light irradiated onto the sheet C6) Skew correction amount The values ​​of these reading conditions may be stored separately for the first reading section 220 and the second reading section 230.

[0043] For example, based on reading condition C1, the reading control unit 256 can determine which pixel position of the line sensors 225 and 235 corresponds to the pixel at the left edge of the read image. Based on reading condition C2, the reading control unit 256 can also determine the length of time from when the lead sensor 215 detects the leading edge of the document until the line sensors 225 and 235 start reading the first line. Based on reading conditions C3 and C4, the reading control unit 256 can also determine the reading size in the main scanning direction and the sub-scanning direction, respectively. Based on reading condition C5, the lighting control unit 254 can also determine the amount of light that the illuminators 221 and 231 should irradiate onto the sheet. Based on reading condition C6, the scanning control unit 255 can also determine the amount of skew correction for the document transported by the ADF 210.

[0044] The values ​​of the reading conditions C1 to C6 are typically determined through testing before shipping in order to reduce the influence of variations in the characteristics of individual devices, and are written to the reading condition storage unit 262. In addition, as will be described in detail later, in this embodiment, the image forming device 1 provides an adjustment function that enables the user to adjust at least one of the reading conditions C1 to C6.

[0045] <3-3. Controller> 3C is a block diagram showing an example of the configuration of the controller 50. The controller 50 includes a CPU 51, a ROM 52, a RAM 53, a storage 54, an operation I / F 55, a printer I / F 56, a scanner I / F 57, an image memory 58, and an image processing unit 59.

[0046] The CPU 51 executes a control program stored in the ROM 52 to provide various functions for controlling the execution of jobs by the printer 100 and the scanner 200. The RAM 53 provides the CPU 51 with a temporary storage area for calculations. In this embodiment, the CPU 51 functions as a job control unit 60, a calibration unit 62, and an adjustment unit 64. As described above, the job control unit 60 controls the execution of copy jobs, print jobs, and scan jobs in the image forming apparatus 1. The calibration unit 62 and the adjustment unit 64 will be described in detail later.

[0047] The storage 54 may be a storage device including a non-volatile storage medium, such as a hard disk drive (HDD). The storage 54 may be used, for example, to store scanned image data generated as a result of a scan job. In addition, in this embodiment, the storage 54 pre-stores image data of a chart used for calibrating the printer 100, which will be described later.

[0048] The operation I / F 55 is an interface for connecting the controller 50 to the operation unit 10. The printer I / F 56 is an interface for connecting the controller 50 to the printer control unit 150. The scanner I / F 57 is an interface for connecting the controller 50 to the scanner control unit 250. The printer I / F 56 may be connected to the printer control unit 150 via a control signal line for communicating control signals and a data signal line for communicating image data. The same applies to the scanner I / F 57.

[0049] The image memory 58 temporarily stores image data that the controller 50 transmits and receives to and from the printer 100, the scanner 200, or an external device. The image processing unit 59 converts the format of the image data to match the device to which the image data is to be output. Furthermore, the image processing unit 59 may provide image processing functions such as edge extraction, corner detection, angle determination, skew correction, extraction of a chart image from a scanned image, detection of known components in a chart image, and character recognition for a calibration unit 62 and an adjustment unit 64, which will be described later.

[0050] In this section, an example has been described in which the controller 50, printer control unit 150, and scanner control unit 250 each include a CPU, but the above-described control functions may be implemented in an integrated manner by a single CPU or a smaller number of CPUs. Furthermore, one of the described control functions may be implemented in a distributed manner by two or more CPUs. The same applies to other components such as ROM and RAM. Furthermore, any function described herein as being implemented by software may be implemented by dedicated hardware.

[0051] <4. Calibration of image formation position> In this embodiment, the CPU 51 functions as a calibration unit 62 that calibrates the position on a sheet where the printer 100 forms an image. When a user instructs calibration via a UI provided by the operation unit 10, the calibration unit 62 causes the printer 100 to form a chart image on a sheet based on image data stored in the storage 54. When the user sets the sheet on which the chart image has been formed in the document tray 204, the calibration unit 62 operates the ADF 210 to transport the sheet along the transport path D2 and causes the scanner 200 to read the sheet. The scanner 200 generates read image data representing a read image including the chart image as a reading result. The calibration unit 62 performs calibration based on the read image data received from the scanner 200.

[0052] <4-1. Chart configuration example> 4 is an explanatory diagram showing an example of the configuration of a chart 71 that can be used by the calibration unit 62. Here, the chart 71 has the same configuration as the adjustment chart disclosed in Patent Document 1.

[0053] In the example of FIG. 4, the chart 71 consists of a front-side chart 71a and a back-side chart 71b to enable front-back registration during double-sided printing. The front-side chart 71a includes four markers 72 and an identification patch 73. The back-side chart 71b includes four markers 72 and an identification patch 74. Each marker 72 has the shape of a right-angled isosceles triangle, with one of the two right-angle sides parallel to the sheet transport direction (sub-scanning direction) and the other perpendicular to the transport direction. The vertex of the hypotenuse closest to the center of the chart serves as the reference point for measuring the image formation position on the sheet. The identification patch 73 is located on the front-side chart 71a inside the four markers 72, but offset to the upper right from the center of the chart (assuming the front side is up in the transport direction). Similarly, the identification patch 74 is located on the back-side chart 71b inside the four markers 72, but offset to the upper right from the center of the chart. The shape of the identification patch 74 on the back chart 71b is the left-right inverse of the shape of the identification patch 73 on the front chart 71a. The identification patches 73 and 74 are used to identify the front / back and orientation of the chart image.

[0054] <4-2. Measuring the image formation position and calculating the calibration parameters> 5 is an explanatory diagram of measurement of the image formation position based on a chart image. In FIG. 5, a scanned image 80 is shown as an example represented by scanned image data received by the calibration unit 62 from the scanner 200. Here, the scanner 200 scans within a scanning range that is slightly larger than the sheet size (for example, 2 mm above, below, left, and right). Therefore, the scanned image 80 has a blank area around the chart image 81.

[0055] The calibration unit 62 extracts a chart image 81 from the scanned image 80 and determines the front / back and orientation of the chart based on the identification patch included in the chart image 81. In the example of Fig. 5, the chart image 81 contains the identification patch 73, so it is known to be an image of the front chart 71a (if it contains the identification patch 74, it is an image of the back chart 71b). In addition, since the identification patch 73 is located in the upper right corner from the center of the chart, it is known that the orientation of the scanned image 80 is the positive direction, the same as the example on the left in Fig. 4 (if the identification patch 73 is located in the lower left corner from the center of the chart, it is the opposite direction).

[0056] The calibration unit 62 extracts the edge of the chart image 81 in the read image 80, and calculates the length (sheet width) X of the chart image 81 in the main scanning direction. A , and the length in the sub-scanning direction (sheet length) Y B The calibration unit 62 also measures the distance X between the reference point of the upper left patch and the left edge. G , the distance Y between the reference point and the upper edge of the upper left patch H , the distance X between the reference point of the upper right patch and the right edge K , the distance Y between the reference point and the upper edge of the upper right patch L , the distance X between the reference point of the bottom left patch and the left edge I , the distance Y between the reference point and the lower edge of the lower left patch J , the distance X between the reference point of the bottom right patch and the right edge M , and the distance Y between the reference point and the lower edge of the lower right patch N Then, based on the measured intervals, the calibration unit 62 calculates the offsets of the writing start positions in the main scanning direction and sub-scanning direction, as well as the enlargement rates in the main scanning direction and sub-scanning direction, as calibration parameters. Similarly, the calibration unit 62 calculates the offsets of the writing start positions in the main scanning direction and sub-scanning direction, as well as the enlargement rates in the main scanning direction and sub-scanning direction, for the read image of the back-side chart 71b.

[0057] The calibration unit 62 may calculate multiple values ​​for each calibration parameter based on the results of reading multiple sheets on which the same chart is formed, and may adopt the average of these values ​​as the calibration parameter value. The calibration parameter values ​​calculated by the calibration unit 62 are output from the controller 50 to the printer control unit 150, and overwrite the setting values ​​stored in the setting storage unit 159. Then, when a job is subsequently executed, any deviation in the image formation position specific to the printer 100 is eliminated, and the image is formed in the appropriate position on the sheet.

[0058] 5. Optimizing chart reading <5-1. Causes of reading errors> As described above, calibration of the image forming position depends on the extraction of the edges of the chart image in the scanned image generated by the scanner 200 and the detection of markers and patches in the chart image. If an abnormality such as a misalignment or skew of the sheet occurs when the scanner 200 reads the sheet on which the chart image is formed, the calibration parameters may not be calculated properly, and the calibration may fail. For example, if the leading edge of the sheet falls outside the range of the scanned image, the interval Y shown in FIG. H and Y L If the left edge of the sheet falls outside the range of the scanned image, the distance X shown in Figure 5 becomes unclear. G and X I becomes unknown.

[0059] Several factors can contribute to sheet reading errors. One factor is when the stack of sheets set in the document tray 204 is not properly aligned (so-called rough set). Another factor is when the regulating plate 204a is not accurately positioned so that it contacts the side of the sheet stack. Rough set or an improper regulating plate 204a can cause the sheet being transported by the ADF 210 to skew, and ultimately cause part of the sheet to be missing from the read image.

[0060] Another cause of sheet reading abnormalities is changes in the mechanical or optical characteristics of the scanner 200 after product shipment. Typically, variations in characteristics specific to individual devices are measured at the factory before product shipment, and based on the measurement results, reading conditions are adjusted to reduce the effects of such variations (values ​​for adjustment are written to the reading condition storage unit 262). However, aging of components or vibrations, shocks, or excessive loads during device relocation can cause deviations from the normal range of characteristics. For example, when a user attempts to lift the scanner 200 by grasping the cover 202 during relocation of the image forming apparatus 1, excessive load is applied to the hinges, mechanically distorting the components and causing deviations in the conveying speed or conveying angle. Long-term use of the apparatus can also cause changes in characteristics due to aging of the ADF 210 and reading units 220 and 230 (e.g., wear of the conveying rollers or misalignment of optical system components). Furthermore, sudden changes in temperature and humidity in the installation environment of the image forming apparatus 1 can cause physical expansion and contraction of the components. Such changes in characteristics after product shipment can no longer be compensated for by adjusting the reading conditions before shipment.

[0061] If the abnormality in sheet reading is due to rough setting or a defect in the regulating plate 204a, it may be possible to resolve the abnormality by instructing the user to re-place the sheet on the document tray 204 and retry reading, as in the technology described in Patent Document 2. On the other hand, if the abnormality is due to a change in characteristics after product shipment, the abnormality will not be resolved even if the user re-places the sheet on the document tray 204 and re-try reading.

[0062] <5-2. Readjustment of reading conditions> Therefore, the CPU 51 of the controller 50 functions as an adjustment unit 64 that adjusts at least one reading condition. The adjustment unit 64 provides the user with a UI for calling up a function for adjusting the reading conditions, and adjusts the reading conditions in response to a user operation.

[0063] In this embodiment, the adjustment unit 64 determines the need for adjustment of the reading conditions when the calibration unit 62 calibrates the image forming position. Specifically, when a sheet on which a chart image is formed is read by the scanner 200, the adjustment unit 64 determines whether the sheet has been read normally based on the read image in accordance with at least one determination condition. If the adjustment unit 64 determines that the sheet on which the chart image is formed has not been read normally by the scanner 200, it outputs a notification urging the user to adjust at least one reading condition. The notification may be displayed on the display of the operation unit 10 or may be transmitted to an external device via the communication interface 20. The notification output here may be a notification (first notification) for urging the user to perform a user operation related to the adjustment function.

[0064] Typically, the adjustment unit 64 may be able to adjust two or more of the above-mentioned reading conditions C1 to C6. In this case, the adjustment unit 64 determines the reading condition that corresponds to the cause of the sheet not being read normally among the two or more reading conditions.

[0065] FIG. 6 is an explanatory diagram for determining abnormalities related to reading conditions C1 and C2. Scanned image 80a shown in FIG. 6(A) includes a chart image 81a. The upper edge of chart image 81a (which may correspond to the leading edge in the transport direction) is outside the range of scanned image 80a. This is an abnormality caused by reading in the sub-scanning direction starting too late, and this abnormality can be resolved by advancing the scanning start position in the sub-scanning direction. Scanned image 80b shown in FIG. 6(B) includes a chart image 81b. The lower edge of chart image 81b (which may correspond to the trailing edge in the transport direction) is outside the range of scanned image 80b. This is an abnormality caused by reading in the sub-scanning direction starting too early, and this abnormality can be resolved by advancing the scanning start position in the sub-scanning direction. Scanned image 80c shown in FIG. 6(C) includes a chart image 81c. The left edge of chart image 81c is outside the range of scanned image 80c. This is an anomaly caused by the reading start position in the main scanning direction being too far to the right, and can be resolved by offsetting the reading start position in the main scanning direction to the left. The scanned image 80d shown in FIG. 6(D) includes a chart image 81d. The right edge of the chart image 81d is outside the range of the scanned image 80d. This is an anomaly caused by the reading start position in the main scanning direction being too far to the left, and can be resolved by offsetting the reading start position in the main scanning direction to the right.

[0066] FIG. 7 is an explanatory diagram for determining abnormalities for reading conditions C3 and C4. Comparing the examples of FIG. 6 and FIG. 7, in the four examples of FIG. 6, the aspect ratio (the ratio of the length of the horizontal side to the length of the vertical side of a right triangle) of the identification patch, which is a component of the chart image, is equal to 1.0. In contrast, in the two examples of FIG. 7(A) and FIG. 7(B), the aspect ratio is smaller than 1.0, i.e., the identification patch is vertically long. In the two examples of FIG. 7(C) and FIG. 7(D), the aspect ratio is larger than 1.0, i.e., the identification patch is horizontally long.

[0067] The scanned image 80e shown in FIG. 7(A) includes a chart image 81e. The identification patch of the chart image 81e is vertically long, and the upper edge of the chart image 81e is outside the range of the scanned image 80e. The scanned image 80f shown in FIG. 7(B) includes a chart image 81f. The identification patch of the chart image 81f is vertically long, and the lower edge of the chart image 81f is outside the range of the scanned image 80f. These are abnormalities caused by an excessively large scanning magnification in the sub-scanning direction, and these abnormalities can be resolved by reducing the scanning magnification in the sub-scanning direction. The scanned image 80g shown in FIG. 7(C) includes a chart image 81g. The identification patch of the chart image 81g is horizontally long, and the left edge of the chart image 81g is outside the range of the scanned image 80g. The scanned image 80h shown in FIG. 7(D) includes a chart image 81h. The identification patch of the chart image 81h is horizontally long, and the right edge of the chart image 81h is outside the range of the scanned image 80h. These are abnormalities caused by the scanning magnification in the main scanning direction being too large, and can be resolved by reducing the scanning magnification in the main scanning direction.

[0068] FIG. 8 is an explanatory diagram for determining abnormalities related to reading conditions C5 and C6. A read image 80i shown in FIG. 8(A) includes a chart image 81i. The chart image 81i includes markers and identification patches as components, but these components are unclear due to their low density. This is an abnormality caused by an inappropriate amount of light irradiated onto the sheet (for example, blown-out highlights caused by excessive light intensity), and can be resolved by adjusting the amount of light irradiated onto the sheet. A read image 80j shown in FIG. 8(B) includes a chart image 81j. The chart image 81j is skewed, and a portion of its lower left corner is outside the range of the read image 80j. This is an abnormality caused by an excessively large skew angle, and can be resolved by adjusting the skew correction amount.

[0069] As can be understood from the above explanation, by determining whether the read image satisfies the determination conditions corresponding to two or more reading conditions, it is possible to identify reading conditions that may hinder (and therefore require adjustment of) the calibration of the printer 100. The causes of an abnormality in the read image may be complex, and it may be necessary to adjust multiple reading conditions (for example, there may be an abnormality in both the reading start position and the scanning magnification).

[0070] In the first notification, the adjustment unit 64 may prompt the user to perform a user operation to adjust the reading conditions (i.e., the reading conditions that require adjustment) that correspond to the cause of the sheet not being read normally. For example, the first notification is made on a first notification screen displayed by the operation unit 10 or the display of an external device. The first notification screen indicates to the user which reading conditions require adjustment. Furthermore, the first notification screen may include a display area (preview area) that displays at least a portion of the read image. In the preview area, a portion of the read image in which an abnormality is detected may be displayed in an enlarged or highlighted form. The first notification screen may include a button for calling up an adjustment screen for adjusting the reading conditions that correspond to the cause of the sheet not being read normally.

[0071] 9 is an explanatory diagram showing an example of the configuration of a first notification screen 300. The first notification screen 300 can be displayed on the display when it is determined that there is an abnormality in the reading start position (also called the leading edge position) in the sub-scanning direction. The first notification screen 300 includes a message area 301, a preview area 302 within the message area 301, a cancel button 303, an adjustment button 304, and a retry button 305.

[0072] A message prompting the user to adjust the leading edge position is displayed in the message area 301. A preview of the scanned image is displayed in the preview area 302, and an object 306 warning of the occurrence of an abnormality is added to the upper edge of the scanned image and chart image corresponding to the leading edge position. The user can learn which scanning conditions should be adjusted from the message displayed in the message area 301. The user can also visually determine how the identified scanning conditions should be adjusted from the display contents of the preview area 302.

[0073] When the user operates the cancel button 303, the adjustment unit 64 closes the first notification screen 300 and cancels the process. The adjustment button 304 is a button for calling up the ADF adjustment screen 310, which will be described next. When the user operates the adjustment button 304, the adjustment unit 64 displays the ADF adjustment screen 310 on the display. The user can also retry reading by properly re-placing the sheet on which the chart image has been formed in the document tray 204 and operating the retry button 305, without adjusting the reading conditions.

[0074] FIG. 10 is an explanatory diagram showing an example of the configuration of the ADF adjustment screen 310. The ADF adjustment screen 310 includes an adjustment input area 311, a reset button 316, and an OK button 317. The adjustment input area 311 lists the reading conditions that can be adjusted by the adjustment unit 64, and a UI for receiving input of an adjustment value for each reading condition is provided. The user can display the UI for the desired reading condition on the screen by scrolling the adjustment input area 311 up or down. In the example of FIG. 10, an object 312 warning of the occurrence of an abnormality is added to the "tip position" corresponding to reading condition C2. The input field 313 is a field for receiving input of the adjustment value for the "tip position." The minus button 314 is a button for decreasing the adjustment value for the "tip position." The plus button 315 is a button for increasing the adjustment value for the "tip position." The user can adjust the reading start position in the sub-scanning direction so that the leading edge of the chart image falls within the range of the read image by operating the input field 313, minus button 314, or plus button 315. Adjustments for other reading conditions may also be made in a similar manner.

[0075] When the user operates the reset button 316, the adjustment unit 64 cancels any unsaved changes to the adjustment values ​​on the ADF adjustment screen 310 and displays the original adjustment values ​​in the respective input fields. When the user operates the OK button 317, the adjustment unit 64 acquires the adjustment values ​​changed by the user and updates the reading conditions held by the reading condition holding unit 262 of the scanner 200 based on the acquired adjustment values.

[0076] As in the illustrated embodiment, a UI is provided for easy access to the ADF adjustment screen 310 from the first notification screen 300, allowing the user to adjust the reading conditions of the scanner 200 in a timely manner while working on calibrating the image formation position.

[0077] In one embodiment, the judgment conditions for determining an abnormality in sheet reading may include a first type of judgment condition for determining an abnormality in a reading condition that can be adjusted in response to a user operation, and a second type of judgment condition different from the first type of judgment condition. The second type of judgment condition may be a condition for determining an abnormality that cannot be resolved by adjustment in response to a user operation. If the first type of judgment condition is satisfied, the adjustment unit 64 outputs the above-mentioned first notification. On the other hand, if the second type of judgment condition is satisfied, the adjustment unit 64 outputs a second notification urging the user to request a third party (e.g., a service technician) to adjust the scanner 200.

[0078] FIG. 11 is an explanatory diagram for determining an abnormality in a chart image that cannot be resolved by adjusting the reading conditions in response to user operations. Scanned image 80k shown in FIG. 11(A) includes chart image 81k. Chart image 81k is a parallelogram, with two long sides tilted relative to the sheet conveyance direction. Scanned image 80l shown in FIG. 11(B) includes chart image 81l. Chart image 81l is a curved strip, with two long sides forming an arc. This irregular shape is mainly due to physical distortion of a component (e.g., a hinge) of the ADF 210, suggesting that the document is not conveyed straight along conveyance path D2. In this case, the abnormality cannot be resolved by adjusting the reading conditions in response to user operations, so it is recommended that a service technician be consulted for more specialized adjustments.

[0079] The second notification may be made, for example, on a second notification screen displayed on the display of the operation unit 10 or an external device. FIG. 12 is an explanatory diagram showing an example of the configuration of the second notification screen 320. The second notification screen 320 may be displayed on the display when it is determined that the second type of determination condition is satisfied. The second notification screen 320 includes a message area 321 and an end button 322. The message area 321 displays a message indicating that maintenance of the ADF 210 is required and urging the user to contact a service technician. After confirming this message, the user contacts the service technician by appropriate means and operates the end button 322 to close the second notification screen 320. Although not shown in FIG. 12, a code identifying the cause of the abnormality (for notification to a service technician) may also be displayed on the second notification screen 320.

[0080] The first type of determination condition may include, for example, the following conditions: (1) First judgment condition: - Conditions related to abnormal sheet position in the scanned image (see Figure 6) If the first determination condition is met, the user is prompted to adjust the reading start position in the main scanning direction or the sub-scanning direction of the scanner 200. (2) Second judgment condition: -Conditions related to the aspect ratio of the chart image components (see Figure 7) If the second determination condition is met, the user is prompted to adjust the scanning magnification in the main scanning direction or the sub-scanning direction of the scanner 200. (3)Third judgment condition: -Conditions related to the density of the components of the chart image (see Figure 8(A)) - If the third determination condition is met, the user is prompted to adjust the amount of light irradiated onto the sheet. (4) Fourth judgment condition: -Conditions related to the sheet inclination in the scanned image (see Figure 8(B)) If the fourth determination condition is satisfied, the user is prompted to adjust the amount of skew correction in the ADF 210.

[0081] The second type of determination condition may include, for example, the following conditions: (5) Fifth judgment condition: -Conditions related to the shape of the sheet in the scanned image (see Figure 11) If the fifth determination condition is met, the user is prompted to ask a third party to adjust the scanner 200.

[0082] In one embodiment, the adjustment unit 64 may further determine the possibility of an operational error. FIG. 13 is an explanatory diagram illustrating the determination of an abnormality in a chart image due to an operational error. The scanned image 80m shown in FIG. 13(A) includes a sheet image 81m. The sheet image 81m does not include markers or identification patches, which are components of a chart. Therefore, it is presumed that the scanned image 80m is the result of scanning an incorrect sheet that was not intended to be scanned. The scanned image 80n shown in FIG. 13(B) includes a chart image 81n. The chart image 81n is pentagonal rather than rectangular, and a portion of the lower right corner of the sheet is missing. Therefore, it is presumed that the scanned image 80n is the result of scanning a folded sheet. If it is determined that such an operational error has occurred, the adjustment unit 64 outputs a third notification urging the user to properly re-place the sheet on which the chart image is formed in the document tray 204 and retry scanning.

[0083] The third notification may be made, for example, on a third notification screen displayed on the display of the operation unit 10 or an external device. FIG. 14 is an explanatory diagram showing an example of the configuration of the third notification screen 330. The third notification screen 330 includes a message area 331, a stop button 332, and a retry button 333. The message area 331 displays a message urging the user to retry reading the sheet. When the user operates the stop button 332, the adjustment unit 64 closes the third notification screen 330 and stops the process. The user may stop the process and start again from printing the chart. When the user properly re-places the sheet on which the chart image has been formed in the document tray 204 and operates the retry button 333, the ADF 210 transports the sheet again, and a read image including the chart image is generated.

[0084] If none of the above-mentioned judgment conditions are met and it is determined that the sheet has been read normally by the scanner 200, the adjustment unit 64 causes the calibration unit 62 to perform calibration of the printer 100 based on the chart image contained in the read image.

[0085] <6. Processing flow> In this section, examples of the flow of several processes that can be executed by the image forming apparatus 1 in relation to the adjustment of reading conditions will be described using the flowcharts in Figures 15 to 17. In the following description, processing steps will be abbreviated as 'S'.

[0086] <6-1. Calibration process> Fig. 15 is a flowchart showing an example of a schematic flow of a calibration process according to an embodiment. The calibration process in Fig. 15 is realized, for example, by the CPU 51 of the controller 50 executing a computer program loaded from the ROM 52 to the RAM 53.

[0087] First, in S11, the proofreading unit 62 commands the printer control unit 150 via the printer I / F 56 to print a chart. Here, the user may be able to specify how many sheets, supplied from which cassette, the chart should be printed on. The printer control unit 150 controls the printer 100 to print the chart on a specified number of sheets supplied from the specified cassette. Next, in S12, the proofreading unit 62 waits until the printer 100 has completed printing the chart. Once the printing of the chart is complete, the process proceeds to S13.

[0088] In S13, the proofreading unit 62 instructs the user to set the sheet on which the chart is printed in the document tray 204 and start reading. When the user performs an operation to start reading, the ADF 210 transports the sheets one by one from the document tray 204, and the sheets are read by the scanner 200 to generate read image data. The proofreading unit 62 receives the read image data from the scanner control unit 250.

[0089] In S14, the calibration unit 62 extracts a chart image from the scanned image. Next, in S15, the calibration unit 62 searches for an identification patch in the chart image and determines the front / back and orientation of the chart image based on the position of the detected identification patch and the direction of the oblique side. Next, in S16, the calibration unit 62 searches for markers in the chart image and detects four markers present on each side.

[0090] Next, in S20, the calibration unit 62 calls the adjustment unit 64, which executes an adjustment determination process for determining the need to adjust the reading conditions based on the results of the analysis of the read image in S14 to S16. An example of the flow of the adjustment determination process executed by the adjustment unit 64 will be described in detail later. The subsequent process branches depending on the result of the adjustment determination process. If the result of the adjustment determination process indicates that the sheet has been read normally, the process proceeds to S30. On the other hand, if it indicates that there is an abnormality in the reading of the sheet, the process proceeds to S22.

[0091] In S22, the adjustment unit 64 executes a notification process according to the type of abnormality determined in the adjustment determination process. An example of the flow of the notification process executed by the adjustment unit 64 will be described in detail later. The subsequent process branches depending on the option selected by the user who received the notification.

[0092] If the user operates the retry button 305 on the first notification screen 300 or the retry button 333 on the third notification screen 330 (S23-YES), the process returns to S13, and the scanner 200 reads the sheet again.

[0093] If the user operates the adjustment button 304 on the first notification screen 300 (S23-NO, S24-YES), the process proceeds to S25. In S25, the adjustment unit 64 displays the ADF adjustment screen 310 on the display. Next, when the user completes the adjustment of the reading conditions, in S26 the adjustment unit 64 updates the reading conditions held by the reading condition holding unit 262 of the scanner 200 based on the adjustment results. The adjustment unit 64 closes the ADF adjustment screen 310 and displays the first notification screen 300 on the display again. Then, if the user operates the retry button 305 on the first notification screen 300 (S27-YES), the process returns to S13, and the scanner 200 reads the sheet according to the updated reading conditions.

[0094] If it is determined in the adjustment determination process in S20 that the sheet has been read normally, in S30 the calibration unit 62 calibrates the image formation position of the printer 100 based on the edge of the chart image extracted in S14 and the position of the reference point of the marker detected in S16.

[0095] <6-2. Adjustment Judgment Process> Figures 16A and 16B are flowcharts showing an example of a detailed flow of the adjustment determination process executed in S20 of Figure 15. The adjustment determination process of Figures 16A and 16B is realized, for example, by the CPU 51 of the controller 50 executing a computer program loaded from the ROM 52 to the RAM 53.

[0096] First, in S101, the adjustment unit 64 acquires the sheet size. The sheet size may be determined based on, for example, sensor signals from the width sensor 204b and the separation sensor 213, may be acquired from the sheet information of the cassette designated in S11 of FIG. 15, or may be determined based on the chart image extracted in S14.

[0097] Next, in S102, the adjustment unit 64 determines whether the density of the component detected in the chart image exceeds a predetermined density threshold. If the density of the component is below the density threshold, in S103, the adjustment unit 64 further determines whether the edge of the chart image corresponding to the sheet size has been detected at an appropriate position. On the other hand, if the density of the component exceeds the density threshold, in S104, the adjustment unit 64 determines whether an identification patch has been detected in the chart image.

[0098] If the density of the chart component is below the density threshold and the edge of the chart image is not detected at an appropriate position, in S106, the adjustment unit 64 determines that there is an abnormality in the amount of light irradiated onto the sheet (third determination condition).

[0099] Furthermore, if the density of the chart component is below the density threshold and the edge of the chart image is detected at the appropriate position, the adjustment unit 64 determines in S107 that an operational error has occurred (for example, reading a blank sheet). Also, if the density of the chart component is above the density threshold and no identification patch is detected in the chart image, the adjustment unit 64 determines in S107 that an operational error has occurred (for example, reading the wrong sheet).

[0100] On the other hand, if the density is appropriate and an identification patch is detected, in S108 the adjustment unit 64 determines whether the chart image extracted from the scanned image is rectangular. If the chart image is not rectangular, in S109 the adjustment unit 64 further determines whether the shape of the chart image is a special shape described with reference to FIG. 11. For example, if the shape of the chart image is a parallelogram or a curved band, in S110 the adjustment unit 64 determines that the user needs to contact a service technician (fifth determination condition). On the other hand, if the shape of the chart image is not rectangular and does not correspond to any of the special shapes described above, in S111 the adjustment unit 64 determines that the sheet is folded or torn.

[0101] If it is determined in S108 that the chart image is rectangular, the adjustment unit 64 compares the inclination of the chart image with a predetermined angle threshold in S112. If the inclination of the chart image is greater than the angle threshold, the adjustment unit 64 determines in S113 that there is a skew abnormality (fourth determination condition).

[0102] If the tilt of the chart image is smaller than the angle threshold, the adjustment unit 64 determines in S114 whether the aspect ratio of the identification patch detected in the chart image is approximately equal to 1.0. If the aspect ratio of the identification patch is not approximately equal to 1.0, it is determined that there is an abnormality in the scanning magnification in one or both of the main scanning direction and the sub-scanning direction (second determination condition). For example, if the aspect ratio of the identification patch is less than 1.0 (NO in S115) and the lower edge of the chart image is missing (YES in S116), the adjustment unit 64 determines in S117 that there is an abnormality in the scanning magnification in the sub-scanning direction. Also, if the aspect ratio of the identification patch is less than 1.0 (NO in S115) and the lower edge of the chart image is not missing (NO in S116), the adjustment unit 64 determines in S118 that there is an abnormality in the scanning magnification in the main scanning direction. If the aspect ratio of the identification patch exceeds 1.0 (YES in S115) and the right edge of the chart image is missing (YES in S117), the adjustment unit 64 determines in S120 that there is an abnormality in the scanning magnification in the main scanning direction. If the aspect ratio of the identification patch exceeds 1.0 (YES in S115) and the right edge of the chart image is not missing (NO in S117), the adjustment unit 64 determines in S121 that there is an abnormality in the scanning magnification in the sub-scanning direction.

[0103] If the aspect ratio of the identification patch is approximately equal to 1.0, the adjustment unit 64 determines in S122 whether the right or left edge of the chart image is missing. Furthermore, in S123, the adjustment unit 64 determines whether the upper or lower edge of the chart image is missing. If either edge is missing, it is determined that there is an abnormality in the reading start position in the corresponding direction of the main scanning direction or the sub-scanning direction (first determination condition). For example, if the right or left edge of the chart image is missing (YES in S122), the adjustment unit 64 determines in S124 that there is an abnormality in the reading start position in the main scanning direction. Furthermore, if the upper or lower edge of the chart image is missing (YES in S123), the adjustment unit 64 determines in S125 that there is an abnormality in the reading start position in the sub-scanning direction.

[0104] If none of the four edges of the chart image is missing in the read image (NO in S122, NO in S123), the adjustment unit 64 determines in S126 that there is no abnormality in reading the sheet.

[0105] The adjustment unit 64 records in memory what type of abnormality it has determined to be present (or absent) in each determination step, and then the adjustment determination process of Figures 16A and 16B ends.

[0106] <6-3. Notification Processing> Fig. 17 is a flowchart showing an example of a detailed flow of the notification process executed in S22 of Fig. 15. The notification process of Fig. 17 is realized, for example, by the CPU 51 of the controller 50 executing a computer program loaded from the ROM 52 to the RAM 53.

[0107] First, in S131, the adjustment unit 64 determines whether the abnormality can be resolved by the user correctly re-placing the sheet based on the result of the adjustment determination process. If it is determined that the abnormality can be resolved by re-placing the sheet, the process proceeds to S132. On the other hand, if it is determined that the abnormality cannot be resolved by re-placing the sheet, the process proceeds to S133.

[0108] In S132, the adjustment unit 64 displays the above-described third notification screen 330 on the display, and instructs the user to properly re-place the sheet on which the chart is printed on the document tray 204 and retry reading.

[0109] In S133, the adjustment unit 64 determines whether the abnormality can be resolved by adjusting the reading conditions in response to a user operation. If it is determined that the abnormality can be resolved by adjusting the reading conditions in response to a user operation (for example, if the read image satisfies the first type of judgment condition), the process proceeds to S134. On the other hand, if it is determined that the abnormality cannot be resolved by adjusting the reading conditions in response to a user operation (for example, if the read image satisfies the second type of judgment condition), the process proceeds to S139.

[0110] In S134, the adjustment unit 64 outputs a first notification to prompt the user to adjust at least one reading condition. The output of the first notification here may include, in S135, displaying the reading condition requiring adjustment on the screen to the user. The output of the first notification may also include, in S136, displaying a button for calling an adjustment function on the screen. The output of the first notification may also include, in S137, displaying a preview of the read image on the screen.

[0111] In S139, the adjustment unit 64 outputs a second notification to prompt the user to contact a service person to request adjustment of the scanner 200.

[0112] This section describes specific examples of the judgment conditions for determining an abnormality in sheet reading and the order of judgment and notification, but the technology disclosed herein is not limited to the described examples. For example, the method of determining whether the aspect ratio of the identification patch is approximately equal to a single reference value of 1.0 in relation to the second judgment condition has been described above. As another example, however, it may be determined whether the aspect ratio of the identification patch falls within a range defined by predetermined upper and lower limits. Furthermore, for example, when it is determined that an abnormality has occurred in sheet reading, the adjustment unit 64 may instruct the user to retry reading the sheet at least once before prompting the user to adjust the reading conditions.

[0113] <7. Summary> Various embodiments and examples of the technology according to the present disclosure have been described above using FIGS. 1 to 17. In the above-described embodiments, the control unit of the image forming apparatus outputs a notification urging the user to adjust at least one reading condition of the reading unit when it is determined that the sheet on which a chart image for calibrating the image forming unit is formed has not been read normally. This promotes the optimization of the reading conditions of the sheet used for calibrating the image forming unit. Therefore, even if the characteristics of the reading unit deviate from the normal range after the product is shipped, calibration parameter values ​​are acquired under appropriate reading conditions, thereby preventing failure in the calibration of the image forming unit.

[0114] In the above-described embodiment, the image forming apparatus can adjust at least one reading condition in response to a user operation, and the notification includes a first notification that prompts the user to perform a user operation to adjust the reading condition. In this case, when an attempt is made to read a sheet on which a chart image is formed, the user can be prompted to perform a user operation to adjust the reading condition in a timely manner.

[0115] In the above-described embodiment, the first notification is output when the scanned image satisfies a first type of judgment condition for determining an abnormality in a scanning condition that can be adjusted according to a user operation. On the other hand, when the scanned image satisfies a second type of judgment condition for determining an abnormality that cannot be resolved by adjustment according to a user operation, a second notification is output, urging the user to request a third party to adjust the scanning means. With this configuration, the user can be prompted to take appropriate action depending on the type of abnormality detected, shortening the time it takes to resolve the abnormality and improving the user's work productivity.

[0116] In one modified example, the technology according to the present disclosure may be applied to adjusting the reading conditions for reading a sheet (on which a chart image is formed) placed on a platen, instead of adjusting the reading conditions for flow reading using an ADF. Also, in another modified example, the technology according to the present disclosure may be applied to adjusting the reading conditions for reading a chart for another purpose, such as calibrating the color of a color printer, instead of reading a chart for calibrating the image formation position of a printer.

[0117] <8. Other embodiments> The above-described embodiment can also be realized in the form of a process in which a program for realizing one or more functions is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program, or by a circuit (e.g., ASIC) that realizes one or more functions.

[0118] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0119] 1: image forming apparatus, 10: operation unit, 20: communication interface, 50: controller, 62: calibration unit, 64: adjustment unit, 71: chart, 72: marker, 73, 74: identification patch, 80: read image, 81: chart image, 100: printer (image forming means), 110: conveyance unit, 120: image forming unit, 140: fixing unit, 150: printer control unit, 200: scanner (reading means), 201: main body, 202: cover, 203: document table, 204: document tray, 205: paper output tray, 210: ADF, 250: scanner control unit, 300: first notification screen, 302: preview area, 304: adjustment button, 310: ADF adjustment screen, 320: second notification screen, 330: third notification screen

Claims

1. an image forming means; a calibration unit that calibrates the image forming unit based on a chart image formed by the image forming unit; a reading unit that reads the sheet on which the chart image is formed while conveying the sheet along a conveying path in accordance with at least one reading condition, thereby generating a read image including the chart image; a control means for determining whether the sheet has been normally read by the reading means based on the read image; Equipped with the control unit outputs a notification prompting a user to adjust the at least one reading condition when it is determined that the sheet has not been read normally by the reading unit. Image forming device.

2. the control means is capable of adjusting the at least one reading condition in response to a user operation; the notification includes a first notification prompting the user to perform the user operation; The image forming apparatus according to claim 1 .

3. the control means is capable of adjusting two or more reading conditions; the first notification includes indicating to the user a reading condition, among the two or more reading conditions, that corresponds to a cause why the sheet was not read normally; The image forming apparatus according to claim 2 .

4. The two or more reading conditions are: A reading start position in the main scanning direction perpendicular to the sheet conveyance direction, a reading start position in a sub-scanning direction parallel to the transport direction; a scanning magnification in the main scanning direction; a scanning magnification in the sub-scanning direction; The amount of light irradiated onto the sheet, and Skew correction amount, 4. The image forming apparatus according to claim 3, wherein the first and second electrodes are two or more of the above.

5. The first notification is displayed on a first notification screen; the first notification screen includes a display area for at least partially displaying the scanned image; The image forming apparatus according to claim 2 .

6. The first notification is displayed on a first notification screen; The image forming apparatus according to claim 2 , wherein the first notification screen includes a button for calling an adjustment screen for adjusting the at least one reading condition.

7. The control means outputting the first notification when the read image satisfies a first type of determination condition for determining an abnormality in a reading condition that is adjustable in response to a user operation; and outputting a second notification urging the user to request a third party to adjust the reading means when the read image satisfies a second type of determination condition for determining an abnormality that cannot be resolved by adjustment according to a user operation. The image forming apparatus according to claim 2 .

8. the first type of determination condition includes a first determination condition related to an abnormality in the position of the sheet in the read image, the first notification output when it is determined that the sheet has not been read normally according to the first determination condition prompts the user to adjust a reading start position of the reading unit; The image forming apparatus according to claim 7 .

9. the first type of determination condition includes a second determination condition related to an aspect ratio of a component of the chart image included in the scanned image, the first notification that is output when it is determined that the sheet has not been read normally according to the second determination condition prompts the user to adjust a scanning magnification of the reading unit; The image forming apparatus according to claim 7 .

10. the first type of determination condition includes a third determination condition related to the density of the read image, the first notification output when it is determined that the sheet has not been read normally according to the third determination condition prompts the user to adjust the amount of light irradiated onto the sheet by the reading unit; The image forming apparatus according to claim 7 .

11. the first type of determination condition includes a fourth determination condition related to a skew of the sheet in the read image, the first notification output when it is determined that the sheet has not been read normally according to the fourth determination condition prompts the user to adjust a skew correction amount in the reading unit; The image forming apparatus according to claim 7 .

12. The image forming apparatus according to claim 7 , wherein the second type of determination condition includes a fifth determination condition related to a shape of the sheet in the read image.

13. The image forming apparatus according to any one of claims 1 to 12, wherein the control means, when it is determined that the sheet has been read normally by the reading means, causes the calibration means to perform the calibration of the image forming means based on the chart image included in the read image.

Images