Printer, printer control method, and program

Abstract

To provide a printer which can suppress decrease in productivity due to image diagnosis during printing even if image diagnosis is performed before printing and during printing, a printer control method, and a program.SOLUTION: An image formation device 101, which can perform image diagnosis with use of a test chart before printing and during printing, comprises a CPU 312 of a diagnosis part 108 that sets a diagnostic level of image diagnosis performed during printing to a diagnostic level during printing, and sets a diagnostic level of image diagnosis performed before printing to a diagnostic level before printing that is stricter than the diagnostic level during printing.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a printing device, a control method for a printing device, and a program. [Background technology]

[0002] Techniques for diagnosing failures in a printing device from image data include, for example, image diagnosis in which a test chart printed by a printing unit is read by an image reading unit, image defects or flaws are found from the image data of the read test chart, and the presence or absence of defects in the device is diagnosed. There is also an inspection in which a printed matter printed by a printing unit is read by an image reading unit, and image defects or flaws in the printed matter are found from the image data of the read print. Patent Document 1 describes an inspection system that sets the inspection level of the inspection to a high level when it is determined that the print job uses a base, and sets the inspection level of the inspection to a normal level when it is determined that the print job does not use a base. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-88139 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the inspection system described in Patent Document 1, since the purpose is to perform an inspection suitable for a printed matter in which an original image is printed over a specific base image, the inspection level of the inspection is set, but it is unclear whether the diagnosis level of the image diagnosis is set. Meanwhile, since the image diagnosis is performed using a test chart, unlike the inspection of printed matter, it can be performed before printing. In this regard, if the image diagnosis is performed at a strict diagnosis level, the possibility that image defects or defects can be dealt with before printing can be increased by the image diagnosis performed before printing, but on the other hand, there is a risk that the image diagnosis performed during printing will increase the number of interruptions to printing.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a printing device, a control method for a printing device, and a program that can suppress a decrease in productivity due to image diagnosis during printing, even if image diagnosis is performed before and during printing. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the printing device of the present invention is a printing device capable of performing image diagnosis using a test chart before and during printing, and is characterized in that it is equipped with a first setting means for setting the diagnostic level of the image diagnosis performed during printing to a first level, and a second setting means for setting the diagnostic level of the image diagnosis performed before printing to a second level that is stricter than the first level. Effect of the Invention

[0007] According to the present invention, even if image diagnosis is performed before and during printing, it is possible to suppress a decrease in productivity due to image diagnosis during printing. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an example of a network configuration including a printing system. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of a hardware configuration of an image forming apparatus. [Diagram 3] 2 is a functional block diagram showing the internal configuration of an image forming apparatus, an external controller, and a client PC. [Figure 4] FIG. 13 illustrates an example of a job management screen. [Diagram 5] FIG. 13 is a diagram showing an example of a setting screen for setting a diagnosis level of image diagnosis. [Figure 6] FIG. 13 is a diagram showing an example of a setting screen for setting an inspection level of an inspection. [Figure 7]4 is a flowchart showing a flow of a printing operation executed by a printing unit and an image diagnosis performed by a diagnosis unit in the image forming apparatus. [Figure 8] 13A and 13B are diagrams showing an example of a screen for accepting implementation instructions and an example of a print confirmation screen, which are displayed during image diagnosis. [Figure 9] FIG. 1 is a diagram showing an example of a test chart used in image diagnosis. [Figure 10] 10 is a flowchart showing a flow of image diagnosis before printing. [Figure 11] 13A and 13B are diagrams showing screens displayed during image diagnosis, including an example of a print confirmation screen upon automatic recovery and an example of a response screen for requesting cleaning of dirt on the reading glass surface. [Figure 12] FIG. 13 is a diagram showing an example of a screen displayed during image diagnosis, the screen being for calling a service person; [Figure 13] 1 is a diagram showing an example of the relationship between the image diagnosis level and the detection size corresponding to the width of a round-shaped thing called a "pot" among image defects or defects. FIG. [Figure 14] FIG. 13 illustrates an example of a job management screen. [Figure 15] FIG. 13 is a diagram showing an example of a setting screen for setting a diagnosis level of image diagnosis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. However, the configurations described in each of the following embodiments are merely examples, and the scope of the present invention is not limited by the configurations described in each embodiment. For example, each part constituting the present invention can be replaced with any configuration that can perform the same function. Any configuration may be added. Any two or more configurations (features) of each embodiment can be combined. Note that the same components are given the same reference numbers and descriptions are omitted. Examples of applications of the printing device of the present invention include, for example, a printer, a multifunction peripheral (MFP), or an image forming device that forms an image on paper by an electrophotographic method. In this embodiment, an image forming device will be described as an example of an application of the printing device of the present invention. Note that a multifunction peripheral is a device that has at least two or more functions among multiple types of functions including, for example, a printing function, a scanning function, a copying function, and a facsimile function.

[0010] First Embodiment The first embodiment will be described below with reference to FIGS.

[0011] [System-wide configuration] FIG. 1 is a diagram showing an example of a network configuration including a printing system 100. As shown in FIG. 1, the printing system 100 includes an image forming apparatus 101 (printing apparatus) and an external controller 102. The image forming apparatus 101 and the external controller 102 are communicatively connected via an internal LAN 103 and a video cable 104. The external controller 102 is communicatively connected to a client PC 106 via an external LAN 105. The client PC 106 can issue a print instruction to the external controller 102 via the external LAN 105. A printer driver having a function of converting image data to be printed into a page description language (PDL) that can be processed by the external controller 102 is installed in the client PC 106.

[0012] A user who wishes to print can operate the client PC 106 to issue a print instruction from various applications installed in the client PC 106 via a printer driver. The printer driver of the client PC 106 transmits PDL data, which is print data, to the external controller 102 based on the print instruction from the user. When the external controller 102 receives the PDL data from the client PC 106, it analyzes and interprets the received PDL data. The external controller 102 performs rasterization processing based on the result of the interpretation, generates a bitmap image (print image data) with a resolution matching the image forming apparatus 101, and issues a print instruction by submitting a print job to the image forming apparatus 101.

[0013] Next, the image forming apparatus 101 will be described. In the image forming apparatus 101, a plurality of modules having different functions are connected, and the image forming apparatus 101 is configured to be capable of complex printing processes such as bookbinding. The image forming apparatus 101 has a printing unit 107, a diagnostic unit 108, a stacker 109, and a finisher 110 as the above-mentioned modules. Each module will be described below. The printing unit 107 prints an image in accordance with a print job, and ejects the printed recording material. The printed recording material ejected from the printing unit 107 is conveyed to the inside of each module in the order of the diagnostic unit 108, the stacker 109, and the finisher 110.

[0014] Printing unit 107 is a device that forms (prints) an image using toner on a recording material that is fed and transported from a paper feed unit of printing unit 107. In the following description, the recording material may be referred to as "paper" and the toner may be referred to as "color material." Diagnosis unit 108 is a device that diagnoses the presence or absence of a defect in image forming apparatus 101 based on the printed recording material that has been printed by printing unit 107 and transported through a transport path. Specifically, diagnosis unit 108 reads the image printed on the transported printed recording material, and performs diagnosis from the obtained read image.

[0015] The diagnosis unit 108 diagnoses the presence or absence of defective parts by extracting a diagnosis area from the read image and checking the difference in read signal values ​​within the extracted diagnosis area. In the following description, this type of diagnosis may be referred to as "image diagnosis." Detailed processing by the diagnosis unit 108 will be described later. The diagnosis unit 108 is also used during inspection. Thus, the diagnosis unit 108 is also a device that inspects the presence or absence of image defects or defects on the printed recording material, based on a comparison between the data of the printed recording material on which an image has been printed by the printing unit 107 and which has been transported through a transport path and the print image data.

[0016] The stacker 109 is a device capable of stacking a large number of printed recording materials. The finisher 110 is a device capable of performing finishing processes such as stapling, punching, and saddle stitching on the conveyed printed recording materials. The finisher 110 discharges the recording materials after the finishing process to a predetermined discharge tray. In the configuration example of FIG. 1, the external controller 102 is connected to the image forming apparatus 101, but the first embodiment can also be applied to a different configuration. As such a configuration, for example, the image forming apparatus 101 is connected to an external LAN 105, and print data is sent from the client PC 106 to the image forming apparatus 101 without going through the external controller 102. In this case, data analysis and rasterization of the print data are performed by the image forming apparatus 101.

[0017] [Hardware Configuration of Image Forming Apparatus 101] FIG. 2 is a cross-sectional view showing an example of the hardware configuration of the image forming apparatus 101. A specific operation example of the image forming apparatus 101 will be described below with reference to FIG. 2. The printing unit 107 has a plurality of paper feed decks. Specifically, the printing unit 107 has six types of decks, namely, paper feed decks 201, 202, 203, 204, 205, and 206. Various recording materials are stored in each of the paper feed decks 201 to 206. In each of the paper feed decks 201 to 206, the uppermost recording material among the recording materials stored therein is separated one by one and fed to a conveying path 207.

[0018] Further, each of the image forming stations 208 to 211 includes a photosensitive drum, and forms a toner image on the photosensitive drum using toner of a different color. Specifically, the image forming stations 208 to 211 form a toner image using toner of cyan (C), magenta (M), yellow (Y), and black (K), respectively. The toner images of each color formed in the image forming stations 208 to 211 are transferred onto the intermediate transfer belt 212 in order, superimposed on each other (primary transfer). The toner image transferred onto the intermediate transfer belt 212 is conveyed to a secondary transfer position 213 according to the rotation of the intermediate transfer belt 212. At the secondary transfer position 213, the toner image is transferred from the intermediate transfer belt 212 onto the recording material conveyed through the conveying path 207 (secondary transfer).

[0019] The recording material after the secondary transfer is conveyed to a fixing unit 214. The fixing unit 214 has a pressure roller and a heating roller. In the fixing unit 214, heat and pressure are applied to the recording material while the recording material passes between these rollers, so that a fixing process is performed to fix the toner image on the recording material. The recording material that has passed the fixing unit 214 is conveyed to a connection point 216 between the printing unit 107 and the diagnosis unit 108 through a conveying path 215. In this manner, a color image is printed on the recording material. If further fixing process is required depending on the type of recording material, the recording material that has passed the fixing unit 214 is guided to a conveying path 218 provided with a fixing unit 217. The fixing unit 217 performs further fixing process on the recording material conveyed through the conveying path 218. The recording material that has passed the fixing unit 217 is conveyed to the connecting point 216.

[0020] Also, when an operation mode for double-sided printing is set, an image is printed on the first side, and the recording material conveyed through conveying path 215 or conveying path 218 is guided to reversing path 219. The recording material reversed at reversing path 219 is guided to double-sided conveying path 220 and conveyed to secondary transfer position 213. As a result, at secondary transfer position 213, a toner image is transferred to a second side of the recording material opposite to the first side. Thereafter, the recording material passes through fixing unit 214 (and fixing unit 217), completing the formation of a color image on the second side of the recording material. When printing of the image in printing section 107 is completed, the printed recording material conveyed to connection point 216 is conveyed into diagnosis section 108.

[0021] The diagnosis unit 108 has image reading units 222 and 223 having a CIS (Contact Image Sensor) on a conveying path 221 along which the printed recording material from the printing unit 107 is conveyed. The image reading units 222 and 223 are disposed at positions facing each other across the conveying path 221. The image reading units 222 and 223 are configured to read the upper surface (first surface) and the lower surface (second surface) of the recording material, respectively. Note that the image reading units 222 and 223 may be configured with a CCD (Charge Coupled Device) or a line scan camera, for example, instead of the CIS. The diagnosis unit 108 performs image diagnosis to diagnose the presence or absence of a defective part in the image forming apparatus 101 based on an image printed on the printed recording material conveyed on the conveying path 221. At this time, the diagnosis unit 108 uses the image reading units 222 and 223 to read the image of the printed recording material when the printed recording material being conveyed reaches a predetermined position.

[0022] The diagnosis unit 108 performs image diagnosis based on an instruction to perform image diagnosis from a user. The timing for performing image diagnosis is, for example, before the start of a printing job, or when printing defects (i.e., image defects) continue consecutively during the printing job. In the following description, before the start of a printing job is referred to as "before printing", and during the printing job is referred to as "during printing". Furthermore, image diagnosis before printing may be referred to as "pre-printing diagnosis", and image diagnosis during printing may be referred to as "during printing diagnosis".

[0023] The main purpose of performing image diagnosis before printing is to prevent image defects and defects during printing and to prevent printing from being interrupted. Image diagnosis during printing includes image diagnosis performed periodically and image diagnosis performed when image defects and defects occur. Image diagnosis performed periodically has the main purpose of preventing image defects and defects from occurring. Image diagnosis performed when image defects and defects occur has the main purpose of identifying the cause of the image defects and defects and correcting the defective part that caused the defect. The diagnosis unit 108 also performs an inspection based on an instruction to perform an inspection from a user. The inspection is performed to find image defects and defects on the printed recording material from the start of printing to the end of printing.

[0024] The recording materials that have passed through the diagnosis unit 108 are conveyed to the stacker 109 in order. The stacker 109 has a stack tray 224 as a tray on which the printed recording materials conveyed from the diagnosis unit 108 arranged on the upstream side in the conveying direction of the printed recording materials are stacked. The printed recording materials that have passed through the diagnosis unit 108 are conveyed through a conveying path 225 in the stacker 109. The printed recording materials conveyed through the conveying path 225 are guided to a conveying path 226, and the printed recording materials are stacked on the stack tray 224. The stacker 109 further has an escape tray 227 as a paper discharge tray. In the first embodiment, the escape tray 227 is used to discharge the recording materials on which the test chart used in the image diagnosis by the diagnosis unit 108 is printed. The printed recording materials conveyed through the conveying path 225 are guided to a conveying path 228, and are conveyed to the escape tray 227.

[0025] The printed recording material that is not stacked or discharged in the stacker 109 but is transported to the finisher 110 at the subsequent stage is transported through a transport path 229. The escape tray 227 is also used to discharge the printed recording material that has been found to have an image defect or other defects during the inspection by the diagnosis unit 108. The stacker 109 further includes an inversion unit 230 for inverting the orientation of the printed recording material that is transported. The inversion unit 230 is used, for example, to make the orientation of the printed recording material input to the stacker 109 the same as the orientation of the printed recording material when it is stacked on the stack tray 224 and then output from the stacker 109. Note that the inversion operation by the inversion unit 230 is not performed on the printed recording material that is not stacked in the stacker 109 but is transported to the finisher 110.

[0026] The finisher 110 executes a finishing process designated by a user on the printed recording material conveyed from the stacker 109 arranged upstream in the conveying direction of the printed recording material. In the first embodiment, the finisher 110 executes finishing processes such as stapling (one or two-place binding), punching (two or three holes), and saddle stitching. The finisher 110 has two discharge trays 231 and 232. When the finishing process is not executed by the finisher 110, the printed recording material conveyed to the finisher 110 is discharged to the discharge tray 231 through a conveying path 233.

[0027] When the finisher 110 executes a finishing process such as stapling, the printed recording material conveyed to the finisher 110 is guided to a conveying path 234. The finisher 110 executes a finishing process designated by the user on the printed recording material conveyed on the conveying path 234 using a finishing processing unit 235, and discharges the printed recording material on which the finishing process has been executed to a paper discharge tray 232. When the user specifies saddle stitching bookbinding, the finisher 110 executes stapling in the center of the printed recording material using a saddle stitching processing unit 236, and then folds the printed recording material in half to generate a bound product. The finisher 110 discharges the generated bound product to a bookbinding tray 238 through a conveying path 237. The bookbinding tray 238 has a belt conveyor configuration for conveying the bound products loaded on the bookbinding tray 238 to the outside of the finisher 110. Incidentally, 239 and 240 are UI display units which will be described later.

[0028] [Function configuration] 3 is a functional block diagram showing the internal configuration of the image forming apparatus 101, the external controller 102, and the client PC 106. The print unit 107 of the image forming apparatus 101 has a communication I / F (interface) 301, a network I / F 302, a video I / F 303, a CPU 304, a memory 305, an HDD unit 306, an image processing unit 307, a print unit 308, and a UI display unit 239. These devices are connected to each other via a system bus 309 so as to be able to transmit and receive data. The communication I / F 301 is connected to the diagnosis unit 108, the stacker 109, and the finisher 110 via a communication cable 310. The CPU 304 communicates for controlling each module of the image forming apparatus 101 via the communication I / F 301.

[0029] The network I / F 302 is connected to the external controller 102 via the internal LAN 103 and is used for communication of data such as control data. The video I / F 303 is connected to the external controller 102 via a video cable 104 and is used for communication of data such as print image data. If the external controller 102 can control the operation of the image forming apparatus 101, the printing unit 107 (i.e., the image forming apparatus 101) and the external controller 102 may be connected only by the video cable 104. The HDD unit 306 stores various programs and data. The CPU 304 controls the operation of the entire printing unit 107 by executing the programs stored in the HDD unit 306. The memory 305 stores programs and data required for the CPU 304 to perform various processes. The memory 305 operates as a work area for the CPU 304.

[0030] The UI display unit 239 is used to receive inputs of various settings and operation instructions from the user and to display for managing print jobs. The UI display unit 239 displays, for example, a job management screen shown in FIG. 4. The UI display unit 239 allows the user to confirm or change print jobs. FIG. 4(a) is a diagram showing an example of a job management screen when the total number of pages is large. FIG. 4(b) is a diagram showing an example of a job management screen when the total number of pages is small. In the first embodiment, the job management screen shown in FIG. 4 is also displayed on the UI display unit 240 of the diagnosis unit 108 and the display unit 324 of the external controller 102 described later.

[0031] Returning to the description of FIG. 3, the diagnosis unit 108 has a communication I / F 311, a CPU 312, a memory 313, a HDD unit 314, image reading units 222 and 223, and a UI display unit 240. These devices are connected to each other via a system bus 315 so as to be able to transmit and receive data. The communication I / F 311 is connected to the printing unit 107 via a communication cable 310. The CPU 312 performs communication required for controlling the diagnosis unit 108 via the communication I / F 311. The CPU 312 controls the operation of the diagnosis unit 108 by executing a program stored in the HDD unit 314.

[0032] A program for the diagnosis unit 108 is loaded in the memory 313. The memory 313 operates as a work area for the CPU 312. The image reading units 222 and 223 read the image of the recording material conveyed to the diagnosis unit 108 in accordance with an instruction from the CPU 312. In the image diagnosis, the CPU 312 diagnoses the presence or absence of a defective part of the image forming apparatus 101 based on the read image for diagnosis read by the image reading units 222 and 223. In the inspection, the CPU 312 finds an image defect or defect on the printed recording material based on the read image of the printed recording material read by the image reading units 222 and 223. The HDD unit 314 stores various setting information and image data required for image diagnosis and inspection. The various setting information and image data stored in the HDD unit 314 can be reused.

[0033] The UI display unit 240 is used to display the results of image diagnosis and inspection, a setting screen, and the like. The UI display unit 240 is also used as an operation unit operated by the user, and accepts various instructions from the user, such as, for example, a change in the setting of the diagnosis unit 108, and an instruction to perform image diagnosis and inspection. FIG. 5 is a diagram showing an example of a setting screen for setting a diagnosis level of image diagnosis. In the setting screen for setting the diagnosis level of image diagnosis shown in FIG. 5, an image diagnosis level in a pre-printing diagnosis (hereinafter, referred to as a "pre-printing diagnosis level") can be set in 501. In 502, an image diagnosis level in a printing diagnosis (hereinafter, referred to as a "printing diagnosis level") can be set. FIG. 6 is a diagram showing an example of a setting screen for setting an inspection level of inspection. In the setting screen for setting the inspection level of inspection shown in FIG. 6, an inspection level can be set in 601.

[0034] Returning to the explanation of Fig. 3, the stacker 109 controls whether the printed recording material conveyed along the conveying path 225 is discharged to a stack tray 224, to an escape tray 227, or to a finisher 110 connected downstream in the conveying direction of the printed recording material. The finisher 110 controls the conveyance and discharge of the printed recording material, and executes finishing processes such as stapling, punching, and saddle stitching.

[0035] The external controller 102 includes a CPU 321, a memory 322, an HDD unit 323, a display unit 324, a network I / F 325, a keyboard 326, a network I / F 327, and a video I / F 328. These devices are connected to each other via a system bus 329 so as to be able to transmit and receive data to each other. The CPU 321 executes a program stored in the HDD unit 323 to control the overall operation of the external controller 102, such as receiving print data from the client PC 106, RIP processing, and transmitting print image data to the image forming apparatus 101. The memory 322 stores programs and data required for the CPU 321 to perform various processes. The memory 322 operates as a work area for the CPU 321. The HDD unit 323 stores various programs and data.

[0036] The keyboard 326 is used for inputting operation instructions of the external controller 102 from the user. The display unit 324 is, for example, a display, and is used for displaying information of applications being executed in the external controller 102 and an operation screen. The network I / F 325 is connected to the client PC 106 via the external LAN 105 and is used for communication of data such as print instructions. The network I / F 327 is connected to the image forming apparatus 101 via the internal LAN 103 and is used for communication of data such as print instructions. The external controller 102 is configured to be able to communicate with the printing unit 107, the diagnosis unit 108, the stacker 109, and the finisher 110 of the image forming apparatus 101 via the internal LAN 103 and the communication cable 310. The video I / F 328 is connected to the image forming apparatus 101 via the video cable 104 and is used for communication of data such as print image data.

[0037] The client PC 106 includes a CPU 331, a memory 332, an HDD unit 333, a display unit 334, a keyboard 335, and a network I / F 336. These devices are connected to each other via a system bus 337 so as to be able to transmit and receive data to and from each other. The CPU 331 controls the operation of each device via the system bus 337 by executing a program stored in the HDD unit 333. This allows the client PC 106 to perform various processes. For example, the CPU 331 generates print data and issues a print instruction by executing a document processing program stored in the HDD unit 333. The memory 332 loads programs and data required for the CPU 331 to perform various processes. The memory 332 operates as a work area for the CPU 331.

[0038] The HDD unit 333 stores, for example, various applications such as a word processing program, programs such as a printer driver, and various data. The display unit 334 is, for example, a display, and is used to display information about applications running on the client PC 106 and an operation screen. The keyboard 335 is used to input operation instructions for the client PC 106 from a user. The network I / F 336 is communicably connected to the external controller 102 via the external LAN 105. The CPU 331 communicates with the external controller 102 via the network I / F 336.

[0039] [Imaging diagnosis] The image diagnosis of the first embodiment will be described below with reference to Figs. 5 to 9. Fig. 7 is a flowchart showing the flow of the printing operation performed by the printing unit 107 and the image diagnosis performed by the diagnosis unit 108 in the image forming apparatus 101. Note that Fig. 7 shows the overall flow from the work before the image diagnosis to the image diagnosis. The processing of each step in Fig. 7 is realized by being executed by the CPU 304 of the printing unit 107 and the CPU 312 of the diagnosis unit 108. In detail, in the printing unit 107, the CPU 304 reads a program stored in the HDD unit 306 into the memory 305 and executes it, thereby realizing the processing of each step in Fig. 7. Also, in the diagnosis unit 108, the CPU 312 reads a program stored in the HDD unit 314 into the memory 313 and executes it, thereby realizing the processing of each step in Fig. 7.

[0040] In step S701, the CPU 312 of the diagnosis unit 108 accepts an instruction to perform image diagnosis from a user and checks the diagnosis level setting of the image diagnosis in FIG. 5 and various settings for image diagnosis. Here, the explanation is given for an instruction to perform image diagnosis from a user, but an instruction to perform image diagnosis from a serviceman in a service mode may be used. In addition, in the first embodiment, the timing for prompting the user to instruct the execution of image diagnosis before printing is, for example, after the image forming apparatus 101 is turned on, that is, after startup. After startup, the CPU 312 of the diagnosis unit 108 prompts the user to instruct the execution of image diagnosis before printing by displaying a notification on one or more of the UI display unit 240 of the diagnosis unit 108, the display unit 324 of the external controller 102, and the UI display unit 239 of the printing unit 107.

[0041] When the total number of pages of the print job registered in the external controller 102 is large, it is possible to reduce the user's effort by determining that image diagnosis before printing is performed before printing is started. In the first embodiment, the print job can also be registered by the UI display unit 239 of the printing unit 107 or the UI display unit 240 of the diagnosis unit 108. An example of prompting the user to instruct the implementation of image diagnosis before printing will be described in detail in the section [Procedure for image diagnosis before printing] described later.

[0042] The above-mentioned prompting of the instruction to perform image diagnosis and the timing of performing image diagnosis are merely examples and are not limited thereto. For example, when the diagnosis unit 108 also has a function of inspection to find image defects or defects on printed recording materials, when image defects or defects are continuously found in the inspection, the diagnosis unit 108 may perform image diagnosis during printing by prompting the user to give an instruction to perform image diagnosis during printing. Furthermore, the diagnosis unit 108 may perform image diagnosis during printing by setting a timer for the time to display a notice to prompt the user to give an instruction to perform image diagnosis during printing, and displaying the notice according to the time set by the timer, other than when image defects or defects are continuously found. Furthermore, the diagnosis unit 108 may perform image diagnosis during printing by setting a counter for the number of printed sheets, instead of setting a timer for the time, and displaying a notice to prompt the user to give an instruction to perform image diagnosis during printing according to the number of printed sheets set by the counter.

[0043] When the user is prompted to instruct to perform image diagnosis, the user selects either a pre-printing diagnosis level 501 or an in-printing diagnosis level 502 in accordance with the timing of performing image diagnosis on the diagnosis level setting screen for image diagnosis shown in Fig. 5. For example, when the timing of performing image diagnosis is after startup of the image forming apparatus 101 and before printing, the pre-printing diagnosis level 501 is set by the user. Also, when image diagnosis is performed during printing in response to the continuous discovery of image defects or defects by inspection, or a timer, counter, etc., the in-printing diagnosis level 502 is set by the user.

[0044] The in-print diagnostic level 502 in Fig. 5 shows an example in which the same "normal" as the inspection level is automatically set in conjunction with the inspection for the purpose of investigating the cause of image defects or faults discovered at the "normal" inspection level 601 in Fig. 6. Such automatic setting is performed by the user pressing and selecting the "linked with inspection" button 504. Therefore, the "linked with inspection" button 503 (second setting means) has a function of maintaining the state in which the in-print diagnostic level is set to the same level as the inspection level even if the inspection level is changed.

[0045] In the example shown, the pre-printing diagnostic level 501 in FIG. 5 is automatically set to "strict" so as to be stricter than the inspection level 601 in FIG. 6 "normal" in order to prevent printing from being interrupted when an image defect or defect is found in the inspection during printing after the start of printing. This is also true for the in-printing diagnostic level 502 in FIG. 5, which is automatically set to "normal" the same as the inspection level 601 in FIG. 6. Such automatic setting is performed by the user pressing and selecting the "automatic" button 503. Therefore, the "automatic" button 503 (first setting means) has a function of maintaining the state in which the pre-printing diagnostic level is set to a stricter level than the in-printing diagnostic level (or inspection level) even if the in-printing diagnostic level (or inspection level) is changed. The diagnostic level of the image diagnosis that is automatically set as described above is confirmed by the user pressing the OK button 505. However, the user can manually set the diagnostic level of the image diagnosis to suit the user's purpose by pressing the cancel button 506 and deselecting the "Automatic" button 503 or the "Linked with Inspection" button 504.

[0046] The CPU 312 of the diagnosis unit 108 displays a screen for accepting an instruction to perform image diagnosis after displaying a notice to prompt the user to give an instruction to perform image diagnosis. In the following, a case where the screen for accepting an instruction to perform image diagnosis is displayed on the UI display unit 240 of the diagnosis unit 108 will be described, but the same applies to the case where it is displayed on the display unit 324 of the external controller 102 or the UI display unit 239 of the printing unit 107. FIG. 8(a) is a diagram showing an example of a screen for accepting an instruction to perform image diagnosis. The explanation of FIG. 8(a) will be given later. When the CPU 312 of the diagnosis unit 108 accepts an instruction to perform image diagnosis from the user via the UI display unit 240 of the diagnosis unit 108, the CPU 312 selects, as a setting for image diagnosis, a paper feed deck in which paper for printing a test chart for image diagnosis is stored from among the paper feed decks 201 to 206.

[0047] Returning to the description of FIG. 7, when the setting confirmation of the image diagnosis is completed as described above, the process proceeds to step S702. In step S702, the CPU 304 of the printing unit 107 first causes the external controller 102 to create a bitmap image of the test chart. At this time, the CPU 321 of the external controller 102 reads out the test chart stored in advance, rasterizes it into a bitmap image, and creates the bitmap image of the rasterized test chart as a reference image. The test chart is an image for image diagnosis of the image forming apparatus 101.

[0048] FIG. 9 is a diagram showing an example of a test chart 900 used in image diagnosis. The test chart 900 has a non-image portion 901 and an image portion 902. The non-image portion 901 is an area located at the leading end of the test chart 900 in the transport direction, and indicates an area where an image is not printed. The image portion 902 is an area located other than the leading end of the chart in the transport direction, and indicates an area where an image using color materials is printed. For example, a monochromatic image with an area ratio of 50% is printed in the image portion 902. Cyan (C), magenta (M), yellow (Y), and black (K) are used as the monochromatic color materials of the image portion 902, respectively. Therefore, four test charts 900, that is, test charts 900 in which the monochromatic color materials of the image portion 902 are cyan (C), magenta (M), yellow (Y), and black (K) are different from each other, are printed.

[0049] For this purpose, in the external controller 102, the CPU 321 transmits the rasterized bitmap image data of the test chart 900 from the video I / F 328 to the video I / F 303 of the printing unit 107 through the video cable 104. In the printing unit 107, the CPU 304 performs halftone processing on the bitmap image data of the test chart 900 received by the video I / F 303, and the printing unit 308 prints the test chart 900 based on the image data obtained by the halftone processing. Note that the above-mentioned configuration of the test chart 900 is an example, and is not limited thereto. For example, as long as the condition is such that a defective part of the printing unit 107 is made apparent by a difference image described later, the ratio of the image portion 902 to the non-image portion 901, the area ratio of the image in the image portion 902, or the image portion 902 using two or more color materials may be different.

[0050] Returning to the description of FIG. 7, in step S703, the CPU 312 of the diagnosis unit 108 executes a process of reading the printed test chart 900 by the image reading units 222 and 223 in order to create area determination data. The CPU 312 of the diagnosis unit 108 stores the read image of the test chart 900 as a diagnosis image in the HDD unit 314 of the diagnosis unit 108. In step S704, the CPU 312 of the diagnosis unit 108 detects a pixel position indicating a paper corner of the recording material from the read image of the test chart 900. There is no particular limitation on the method of detecting the paper corner (a pixel position indicating the paper corner), and an example of the method includes a method of extracting a pixel area similar to a paper corner image stored in advance by template matching and calculating the center of gravity of the pixel area. In addition, any method may be used as long as it detects the paper corner (a pixel position indicating the paper corner), and the intersection of the edges of the outermost corner extracted by the Hough transform may be used as the paper corner (a pixel position indicating the paper corner). The CPU 312 of the diagnosis unit 108 stores the four pixel positions detected as the paper corners in the HDD unit 314 of the diagnosis unit 108 .

[0051] In step S705, the CPU 312 of the diagnosis unit 108 first determines whether the target pixel position is a non-image portion 901 or an image portion 902 for each pixel position included in the read image of the test chart 900. The non-image portion 901 is a non-printed area inside the recording material where no color material is recorded. The image portion 902 is a printed area inside the recording material where color material is recorded. The CPU 312 of the diagnosis unit 108 then creates area determination data corresponding to the result of the determination. The area determination data is composed of the same number of pixels as the read image of the test chart 900, and is created as 1-bit data capable of expressing the two states of the non-image portion 901 and the image portion 902.

[0052] The determination of whether the target pixel position is in the non-image portion 901 or the image portion 902 is made based on whether the target pixel position is included in the rectangle of the image portion 902 of the recording material. In the first embodiment, the relative positional relationship between (a pixel position indicating) the paper corner and the rectangle of the image portion 902 of the recording material is stored in advance in the HDD unit 314 of the diagnosis unit 108. Then, the pixel position indicating the rectangle of the image portion 902 is calculated from the relative positional relationship stored in advance and (a pixel position indicating) the paper corner detected in step S704. As a method of determining whether the target pixel position is included in the rectangle of the image portion 902 of the recording material, for example, a known Crossing Number Algorithm is used.

[0053] The CPU 312 of the diagnosis unit 108 judges whether the target pixel position is included in the rectangle of the image portion 902 of the recording material based on the number of intersections between a line drawn from the target pixel position toward the image edge and the lines that form the rectangle of the image portion 902 of the recording material. If the number of intersections is an even number, the CPU 312 of the diagnosis unit 108 judges that the target pixel position is not included in the rectangle of the image portion 902 of the recording material, and sets the data of the target pixel position in the area judgment data to "0", which indicates the non-image portion 901. If the number of intersections is not an even number, the CPU 312 of the diagnosis unit 108 judges that the target pixel position is included in the rectangle of the image portion 902 of the recording material, and sets the data of the target pixel position in the area judgment data to "1", which indicates the image portion 902.

[0054] In the first embodiment, an example has been described in which the relative positional relationship between (a pixel position indicating) the paper corner and the rectangle of the image portion 902 of the recording material is stored in advance, but the present invention is not limited to this example. For example, the CPU 312 of the diagnosis unit 108 may calculate a rectangular area inside the recording material of the read image of the test chart 900, where density information that can be calculated from the read signal value changes by a certain amount or more, and determine that the calculated rectangular area is the print area (image portion 902). The CPU 312 of the diagnosis unit 108 stores the area determination data created as described above in the HDD unit 314 of the diagnosis unit 108.

[0055] In step S706, the CPU 312 of the diagnosis unit 108 calculates an average value that serves as a reference signal in order to create differential image data for identifying defective parts in the printing unit 107. The CPU 312 of the diagnosis unit 108 calculates an average value Ave_w in the non-image portion 901 and an average value Ave_image in the image portion 902 as average values ​​that serve as a reference signal, using the area determination data created in step S705 and the read image of the test chart 900. In detail, the CPU 312 of the diagnosis unit 108 calculates an average value Ave_w in the non-image portion 901 by averaging the signal values ​​of the read image of the test chart 900 corresponding to the pixel positions determined to be the non-image portion 901 based on the area determination data. The CPU 312 of the diagnosis unit 108 also calculates an average value Ave_image in the image portion 902 by averaging the signal values ​​of the read image of the test chart 900 corresponding to the pixel positions determined to be the image portion 902 based on the area determination data.

[0056] In calculating the average value Ave_w in the non-image portion 901 and the average value Ave_image in the image portion 902, the RGB signal values ​​of the scanned image of the test chart 900 are converted to luminance values, and the average of the converted luminance values ​​is calculated. The CPU 312 of the diagnosis unit 108 stores the average value calculated as above in the HDD unit 314 of the diagnosis unit 108. The conversion from the RGB signal values ​​to the luminance value Y is performed using the following formula (1) defined in ITU-T BT.709. Y = 0.2126×R+0.7152×G+0.0722×B Equation (1)

[0057] In step S707, the CPU 312 of the diagnosis unit 108 creates differential image data for identifying defective parts in the printing unit 107. More specifically, the CPU 312 of the diagnosis unit 108 creates differential image data between each average value calculated in step S706 and the read image of the test chart 900. At this time, if the area determination data corresponding to the target pixel position of the read image of the test chart 900 is "0 (non-image portion)" or "1 (image portion)", it is determined to be a pixel within the recording material, and a difference value is calculated by comparing the corresponding average value with the read image of the test chart 900. If the calculated difference value exceeds a predetermined threshold, the CPU 312 of the diagnosis unit 108 sets "1" to the differential image data as a difference. Conversely, if the calculated difference value is below the above threshold, the CPU 312 of the diagnosis unit 108 sets "0" to the differential image data as a difference. The CPU 312 of the diagnosis unit 108 stores in the HDD unit 314 the difference image data, which is binary data indicating the presence or absence of a difference.

[0058] The method of calculating the differential image data is not limited to the above example. In the first embodiment, an example has been described in which the average value calculated from the read image of the test chart 900 is used as the reference signal, but a value assumed as the reference signal may be stored in advance in the HDD unit 314. In addition, the diagnosis unit 108 may have a correction unit that corrects nonlinearity between the signal value and brightness of the read image of the test chart 900 acquired by the image reading units 222 and 223, and calculate the differential image data after correcting the signal value of the read image of the test chart 900 by the correction unit.

[0059] When the creation of the differential image data is completed, the CPU 312 of the diagnosis unit 108 judges whether the image forming apparatus 101 is normal in step S708. This judgment is made based on whether data including "1" exists in the differential image data. If the CPU 312 of the diagnosis unit 108 obtains a judgment result that the image forming apparatus 101 is normal (the differential image data does not include "1"), the process proceeds to step S709. On the other hand, if the CPU 312 of the diagnosis unit 108 obtains a judgment result that the image forming apparatus 101 is not normal (the differential image data includes "1"), the process proceeds to step S710. In step S709, the CPU 312 of the diagnosis unit 108 displays "No problem" on the UI display unit 240 of the diagnosis unit 108, indicating that the diagnosis result is normal.

[0060] In steps S710 to S713, CPU 312 of diagnosis unit 108 identifies a defective part in printing unit 107 based on the read image data and differential image data of test chart 900, and instructs how to deal with it. In step S710, CPU 312 of diagnosis unit 108 extracts feature amounts for identifying the defective part in printing unit 107 from the read image data and differential image data of test chart 900. At this time, CPU 312 of diagnosis unit 108 extracts features of the difference region from the read image of test chart 900 that corresponds to the difference region determined to have "a difference" in the calculation of the differential image data in step S707.

[0061] The feature information of the difference region obtained by this feature extraction includes, for example, color material information indicating which color (cyan (C), magenta (M), yellow (Y), or black (K)) the defect occurs in, contrast information indicating the density of the defect, and shape information such as size and vertical length.Furthermore, the feature information includes coordinate information indicating the position in a direction perpendicular to the transport direction of the test chart 900 in the printing unit 107, and periodic information indicating that defects with similar characteristics occur periodically in the transport direction of the test chart 900 in the printing unit 107.

[0062] In step S711, based on the characteristic information of the differential region obtained in step S710, CPU 312 of diagnosis unit 108 identifies parts that are causing the image failure or defect in printing unit 107 and image reading units 222, 223. At this time, CPU 312 of diagnosis unit 108 selects a combination of the same color with high similarity from the differential region, and identifies which part is defective based on the period information of the selected combination.

[0063] In step S712, the CPU 312 of the diagnosis unit 108 determines how to deal with the image failure or defect (i.e., how to repair the image forming apparatus 101) based on the part that is the cause identified in step S711. There are two types of measures to deal with the image failure or defect: those that can be automatically restored and those that cannot be automatically restored. The automatically restored measures include measures that can be automatically restored by the printing unit 107, such as cleaning the wires and grids of the corona chargers that are charging means for the photosensitive drums of the image forming stations 208 to 211 of the printing unit 107. There are two types of measures that cannot be automatically restored. The first example is a measure that requires a user's work, such as cleaning dirt from the reading glass surfaces of the image reading units 222 and 223 of the diagnosis unit 108 or adjusting the recording material to be used, or a measure that requires a serviceman's work, such as replacing parts. The second example is a measure that requires a reading abnormality of the image reading units 222 and 223, or a measure against fibers or foreign matter that are in the recording material before image formation.

[0064] In step S713, the CPU 312 of the diagnosis unit 108 determines whether the action determined in step S712 is an automatically recoverable action. If the CPU 312 of the diagnosis unit 108 determines that the action determined in step S712 is an automatically recoverable action, the process proceeds to step S714. On the other hand, if the CPU 312 of the diagnosis unit 108 determines that the action determined in step S712 is not an automatically recoverable action, the process proceeds to step S715. In step S714, the CPU 312 (response means) of the diagnosis unit 108 executes automatic recovery control to respond to the cause of the image failure or defect. In step S715, the CPU 312 (response means) of the diagnosis unit 108 displays the image diagnosis result and the method of response on the UI display unit 240 of the diagnosis unit 108. When any one of the above-mentioned steps S709, S714, and S715 is completed, the flowchart shown in FIG. 7 ends.

[0065] [Procedure for image diagnosis before printing] FIG. 10 is a flowchart showing the flow of image diagnosis before printing. FIG. 10 shows the flow from when a user instructs the start of printing, to setting image diagnosis before printing, performing image diagnosis before printing, handling after image diagnosis before printing, and printing. An instruction to perform image diagnosis before printing is accepted, for example, by selecting print in the hold / print column 401 on the job management screen of FIG. 4 displayed on the UI display unit 240 of the diagnosis unit 108. The processing of each step of FIG. 10 is executed by the CPU 312 of the diagnosis unit 108. In detail, in the diagnosis unit 108, the CPU 312 (computer) reads a program stored in the HDD unit 314 into the memory 313 and executes it, thereby realizing the processing of each step of FIG. 10 (control method of the printing device).

[0066] In step S1001, the CPU 312 performs a pre-printing diagnosis execution determination. In the pre-printing diagnosis execution determination, a determination is made as to whether or not to perform image diagnosis before printing. Meanwhile, for example, small toner clumps due to toner stains that are the source of image defects and defects gradually grow larger as printing is repeated. As a result, the toner clumps may be found as image defects and defects during inspection from the start of printing to the end of printing of the print job. Therefore, in order to prevent printing from being interrupted midway, the pre-printing diagnosis level 501 in FIG. 5 is set stricter than the inspection level 601 in FIG. 6, and image defects and defects are found by image diagnosis before printing. This point is also true for the printing diagnosis level. The details of the pre-printing diagnosis execution determination will be described later.

[0067] In step S1002, the CPU 312 judges whether the result of the pre-printing diagnosis execution judgment in step S1001 is to execute image diagnosis before printing. If the CPU 312 judges that the result of the pre-printing diagnosis execution judgment in step S1001 is to execute image diagnosis before printing, the process proceeds to step S1003. On the other hand, if the CPU 312 judges that the result of the pre-printing diagnosis execution judgment in step S1001 is not to execute image diagnosis before printing, the process proceeds to step S1010. In step S1003, the CPU 312 (second setting means) sets the pre-printing diagnosis level (second level) to the image diagnosis level used in the image diagnosis (second setting process). For example, when the diagnosis level setting shown in FIG. 5 is performed, the pre-printing diagnosis level 501 "strict" is set to the image diagnosis level. In step S1004, the CPU 312 pops up an image diagnosis execution confirmation screen 801 shown in FIG. 8(a) on the UI display unit 240 of the diagnosis unit 108.

[0068] In step S1005, the CPU 312 confirms with the user whether or not to perform a pre-printing diagnosis. When the "Perform" button 802 on the image diagnosis implementation confirmation screen 801 shown in FIG. 8(a) is instructed by the user, the CPU 312 confirms that the pre-printing diagnosis will be performed. In that case, the process proceeds to step S1006. On the other hand, when the "Cancel" button 803 on the image diagnosis implementation confirmation screen 801 shown in FIG. 8(a) is instructed by the user, the CPU 312 confirms that the pre-printing diagnosis will not be performed. In that case, the process proceeds to step S1010. In step S1006, the CPU 312 performs image diagnosis processing. In the image diagnosis processing, image diagnosis is performed. As a result, image diagnosis before printing is performed. Note that the image diagnosis processing has been described in the description of FIG. 7 above, and will not be described here.

[0069] In step S1007, the CPU 312 judges whether the result of the image diagnosis processing is satisfactory. If the CPU 312 judges that the result of the image diagnosis processing is satisfactory, the process proceeds to step S1008. On the other hand, if the CPU 312 judges that the result of the image diagnosis processing is satisfactory, the process proceeds to step S1012. In step S1008, the CPU 312 pops up a print confirmation screen 804 of FIG. 8(b) on the UI display unit 240 of the diagnosis unit 108. In step S1009, the CPU 312 judges whether printing has been instructed. If the "Print" button 805 on the print confirmation screen 804 shown in FIG. 8(b) is instructed by the user, the CPU 312 judges that printing has been instructed. In that case, the process proceeds to step S1010. On the other hand, if the "Cancel" button 806 on the print confirmation screen 804 shown in FIG. 8(b) is instructed by the user, the CPU 312 judges that printing has not been instructed. In that case, the process proceeds to step S1015.

[0070] In step S1010, the CPU 312 (first setting means) sets the image diagnosis level used in the image diagnosis to the printing diagnosis level (first level) (first setting process). For example, when the diagnosis level setting shown in FIG. 5 is performed, the printing diagnosis level 502 "normal" is set as the image diagnosis level. As a result, the image diagnosis level is changed from the pre-printing diagnosis level 501 "strict" to the printing diagnosis level 502 "normal" which is the same as the inspection level 601. Such a change in the image diagnosis level is performed so that when image diagnosis is performed during printing, even image defects and defects that are not found at the inspection level are found and printing is not interrupted. In step S1011, the CPU 312 instructs the CPU 304 of the printing unit 107 to print. As a result, printing is performed in the print unit 308 of the printing unit 107.

[0071] In step S1012, the CPU 312 determines whether the result of the image diagnosis processing is automatically recoverable. If the CPU 312 determines that the result of the image diagnosis processing is automatically recoverable, the process proceeds to step S1013. On the other hand, if the CPU 312 determines that the result of the image diagnosis processing is not automatically recoverable, the process proceeds to step S1014. In step S1013, the CPU 312 pops up a print confirmation screen 1101 for automatic recovery in FIG. 11(a) on the UI display unit 240 of the diagnosis unit 108.

[0072] In step S1014, the CPU 312 pops up a response screen on the UI display unit 240 of the diagnosis unit 108. The response screen includes, for example, a response screen 1102 in FIG. 11(b) for requesting cleaning of dirt on the reading glass surface, and a response screen 1201 in FIG. 12 for calling a service technician. In step S1015, the CPU 312 cancels printing. When the process of step S1011 or step S1015 described above is completed, the flowchart shown in FIG. 10 ends.

[0073] [Image diagnostic level and detection size] The image diagnosis level indicates the detection size of image defects and defects on the image data. For example, a strict image diagnosis level means that the detection size is reduced to find small image defects and defects. On the other hand, a loose image diagnosis level means that the detection size is increased to find large image defects and defects. FIG. 13 is a diagram showing an example of the relationship between the image diagnosis level and the detection size corresponding to the width of a round-shaped dot among image defects and defects. For example, when the image diagnosis level is "strict", dots with a detection size of 150 μm or more and less than 200 μm are found by image diagnosis. Also, when the image diagnosis level is "normal", dots with a detection size of 250 μm or more and less than 300 μm are found by image diagnosis. As mentioned above, toner lumps due to toner stains, which are the source of image defects and defects, may start out as small as 150 μm in size, but gradually grow with repeated printing and may grow to 300 μm, double in size, in one day. Note that these are just examples and are not limited to these. The same applies to the inspection level and the detection size.

[0074] [Details of pre-printing diagnosis execution judgment] 4 and 14 are diagrams showing an example of a job management screen displayed on the UI display unit 239 of the printing unit 107. The job management screen shown in FIG. 14 is also displayed on the UI display unit 240 of the diagnosis unit 108 and the display unit 324 of the external controller 102 in the same manner as the job management screen shown in FIG. 4. In the pre-printing diagnosis execution determination (step S1001), the CPU 312 of the diagnosis unit 108 determines that the pre-printing diagnosis is to be executed if the number of pages to be printed exceeds a predetermined number of pages. When such a determination is made, the pre-printing diagnosis level is set as the image diagnosis level used in the image diagnosis (steps S1002 and S1003). For example, in the case shown in FIG. 4(a), the number of pages to be printed is 4000 pages, which is the total number of pages of one print job, and exceeds the specified number of pages. Therefore, in this case, the CPU 312 of the diagnosis unit 108 determines that the pre-printing diagnosis is to be executed, and further sets the image diagnosis level used in the image diagnosis to the pre-printing diagnosis level.

[0075] As described above, a small dot that is not considered to be an image defect or defect at the start of printing grows larger as printing is repeated, and if it is found to be an image defect or defect in the inspection during printing, printing will be interrupted. This also applies to the case where it is found to be an image defect or defect in the image diagnosis during printing. Therefore, in order to find a small dot that is not considered to be an image defect or defect at the start of printing before printing, a pre-printing diagnosis is performed at a pre-printing diagnosis level that is stricter than the inspection level (i.e., the printing diagnosis level that is the same as the inspection level). On the other hand, in the case shown in FIG. 4(b), the number of pages to be printed is 60 pages, which is the total number of pages in one print job, and is relatively small, and does not exceed the specified number of pages. In this case, the CPU 312 of the diagnosis unit 108 determines not to perform a pre-printing diagnosis.

[0076] Note that the case where the number of pages to be printed exceeds the specified number of pages is not limited to the case where the total number of pages of one print job is 4000 pages as shown in FIG. 4(a) above. For example, the number of pages to be printed may be the total number of pages obtained by adding up the total number of pages of each of multiple print jobs to be printed, rather than the total number of pages of one print job. In the case shown in FIG. 14, the number of pages to be printed is 4000 pages, which is the total number of pages obtained by adding up the total number of pages of each of the four print jobs, and exceeds the specified number of pages. Therefore, in this case, the CPU 312 of the diagnosis unit 108 determines to perform pre-printing diagnosis, and further sets the pre-printing diagnosis level to the image diagnosis level used in the image diagnosis.

[0077] The CPU 312 of the diagnosis unit 108 may determine whether to perform a pre-printing diagnosis based on the result of the previous image diagnosis. This determination is made based on the size of the image defects or defects found in the previous image diagnosis, in order to find in the current image diagnosis small image defects or defects that were present at the start of printing and that grow larger as printing is repeated. Here, when the CPU 312 of the diagnosis unit 108 determines to perform a pre-printing diagnosis, it further sets the pre-printing diagnosis level to the image diagnosis level used in the image diagnosis.

[0078] Also, the CPU 312 of the diagnosis unit 108 may determine whether to perform a pre-print diagnosis depending on the state of the image forming apparatus 101. For example, the CPU 312 (increase / decrease means) of the diagnosis unit 108 decreases the specified number of pages when the image forming apparatus 101 has a fast growth speed of the dots, and increases the specified number of pages when the image forming apparatus 101 has a slow growth speed of the dots. In this way, the specified number of pages is increased or decreased, so that the determination of whether to perform a pre-print diagnosis is appropriate for the state of the image forming apparatus 101. Here, when the CPU 312 of the diagnosis unit 108 determines to perform a pre-print diagnosis, it further sets the pre-print diagnosis level to the image diagnosis level used in the image diagnosis. Note that, in the first embodiment, an example has been described in which it is determined to perform a pre-print diagnosis based on information on the job management screen, but it goes without saying that the same effect can be obtained even if the pre-print diagnosis level of the present invention is applied to a pre-print diagnosis manually performed by a user.

[0079] [summary] As described above, in the image forming apparatus 101, the diagnosis level of the image diagnosis performed before printing is set to be stricter than the diagnosis level of the image diagnosis performed during printing, thereby reducing the possibility of increasing interruptions of printing due to the diagnosis level of the image diagnosis during printing. As a result, even if the image forming apparatus 101 performs image diagnosis before and during printing, it is possible to suppress a decrease in productivity due to the image diagnosis during printing. Furthermore, when a measure determined by the image diagnosis is executed during printing, printing is interrupted and the image forming apparatus 101 is repaired. At this time, depending on the repair content of the image forming apparatus 101, the interruption of printing may last for a long time, so it is significant to reduce the possibility of increasing interruptions of printing due to the diagnosis level of the image diagnosis during printing. Note that, when a measure determined by the image diagnosis is executed before printing and the image forming apparatus 101 is repaired, it is expected that the growth period of image defects and defects in subsequent printing will be extended, so that the possibility of interrupting printing due to the image diagnosis during printing can be reduced.

[0080] Furthermore, in the image forming apparatus 101, the pre-printing diagnosis level is set to a level stricter than the inspection level, so that even if image defects or defects grow during printing, there is little chance that they will be discovered by inspection. As a result, the opportunities for repairs to be made by image diagnosis during printing are reduced, and the possibility of printing being interrupted is also reduced, making it possible to suppress a decrease in productivity. Furthermore, in the image forming apparatus 101, the during-printing diagnosis level is set to the same as the inspection level, which is lenient than the pre-printing diagnosis level. As a result, while maintaining the same inspection performance, there are fewer opportunities for repairs to be made by image diagnosis during printing, and the possibility of printing being interrupted is also reduced, making it possible to suppress a decrease in productivity.

[0081] <Second embodiment> The second embodiment will be described below with reference to FIG. 5, FIG. 6, and FIG. 15. Here, the difference from the first embodiment will be mainly described. In the first embodiment, as shown in the diagnosis level setting in FIG. 5 and the inspection level setting in FIG. 6, the case where "pre-printing diagnosis level < printing diagnosis level = inspection level" was described. That is, in the first embodiment, the case where the pre-printing diagnosis level is stricter than the printing diagnosis level, and the printing diagnosis level is the same as the inspection level was described. This is because the printing diagnosis level and the inspection level are set to be the same, assuming a case where the cause of the image failure or defect found in the inspection during printing is identified by the image diagnosis performed following the inspection during printing. This avoids the occurrence of a situation where the image failure or defect found in the inspection during printing is not found by the image diagnosis performed following the inspection. Note that, as a specific default detection size, taking FIG. 5 and FIG. 6 as an example, the pre-printing diagnosis level "strict" is 150 μm or more and less than 200 μm, and the printing diagnosis level and the inspection level "normal" are 250 μm or more and less than 300 μm. Such a default detection size is merely an example and is not limiting.

[0082] In the second embodiment, a case will be described where "pre-printing diagnosis level < during-printing diagnosis level < inspection level" as shown in the diagnosis level settings in Fig. 15 and the inspection level settings in Fig. 6. That is, in the second embodiment, a case will be described where the pre-printing diagnosis level is stricter than the during-printing diagnosis level, and the during-printing diagnosis level is stricter than the inspection level.

[0083] In addition to the level settings described above, the second embodiment assumes that the image diagnosis during printing is performed when the counter-set number of printed sheets or the elapsed printing time is reached (time set by a timer). Therefore, in the second embodiment, the image diagnosis performed during printing is different from the image diagnosis performed during inspection, so the during-printing diagnosis level is not set to the same as the inspection level.

[0084] This is to prevent image defects or defects from being immediately found in the inspection carried out thereafter when image diagnosis is carried out during printing and no image defects or defects are found. As a result, the in-printing diagnosis level is set stricter than the inspection level. Such a setting is automatically performed when the user presses and selects the "Auto" button 1501 in FIG. 15. Therefore, the "Auto" button 1501 (third setting means) has a function of maintaining the state in which the in-printing diagnosis level is set to a level stricter than the inspection level even if the inspection level is changed. Note that the "Auto" button 501 in the second embodiment has a function of maintaining the state in which the pre-printing diagnosis level is set to a level stricter than the in-printing diagnosis level even if the in-printing diagnosis level is changed.

[0085] As described above, in the image forming apparatus 101, image defects and other defects are found by image diagnosis during printing, and the opportunities for repairs are increased, making it possible to reduce the rate of defects during printing. Furthermore, if the rate of defects during printing is reduced, the number of image defects and other defects found during inspection is reduced, and the time and effort required by users to reprint is reduced. As a result, it is possible to suppress a decrease in productivity.

[0086] <Other> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. The present invention can also be realized by supplying a program that realizes one or more functions of the above-mentioned embodiments to a system or device via a network or storage medium, and having one or more processors of a computer in the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0087] 5 may also be displayed on the UI display unit 239 of the printing unit 107 and the display unit 324 of the external controller 102, so that the diagnostic level setting may also be performed by the printing unit 107 or the external controller 102. This also applies to the setting screen for setting the diagnostic level of the image diagnosis shown in Fig. 15. Furthermore, the setting screen for setting the examination level of the examination shown in Fig. 6 may also be displayed on the UI display unit 239 of the printing unit 107 and the display unit 324 of the external controller 102, so that the examination level setting may also be performed by the printing unit 107 or the external controller 102.

[0088] The disclosure of each embodiment includes the following configurations, methods, and programs. (Configuration 1) A printing device capable of performing image diagnosis using a test chart before and during printing, a first setting means for setting a diagnostic level of the image diagnostic performed during printing to a first level; and a second setting means for setting a diagnostic level of the image diagnosis performed before printing to a second level stricter than the first level. (Configuration 2) The printing device according to configuration 1, further comprising a first setting means for automatically setting the second level to a level stricter than the first level in response to a user operation. (Configuration 3) The printing device is capable of performing image diagnosis following inspection of the printed matter during printing; 3. The printing device according to configuration 1 or 2, further comprising a second setting means for automatically setting the first level to the same level as an inspection level of an inspection in response to a user's operation. (Configuration 4) The printing device is capable of performing an inspection of the printed matter following the performance of image diagnosis during printing; 3. The printing device according to configuration 1 or 2, further comprising a third setting means for automatically setting the first level to a level stricter than an inspection level of the inspection in response to a user operation. (Configuration 5) The printing device according to any one of configurations 1 to 4, wherein the second setting means is executed when the number of pages to be printed exceeds a specified number of pages. (Configuration 6) The printing device according to configuration 5, wherein the number of pages to be printed is the total number of pages in one print job. (Configuration 7) The printing device according to configuration 5, wherein the number of pages to be printed is a total number of pages obtained by adding up the total number of pages of a plurality of print jobs. (Configuration 8) The printing device according to any one of configurations 5 to 7, further comprising an increment / decrement unit for incrementing / decrementing the specified number of pages based on the state of the printing device. (Configuration 9) The printing device according to any one of configurations 1 to 4, wherein the second setting means is executed based on a result of a previous image diagnosis. (Configuration 10) A printing device described in any one of configurations 1 to 9, characterized in that it is provided with a response means for carrying out, before printing, a response determined by image diagnosis before printing in order to repair the printing device, and for interrupting printing and carrying out a response determined by image diagnosis during printing. (Method 1) A method for controlling a printing device capable of performing image diagnosis using a test chart before and during printing, comprising the steps of: a first setting step of setting a diagnostic level of image diagnostics performed during printing to a first level; A control method for a printing device, comprising: a second setting step of setting a diagnostic level of the image diagnosis performed before printing to a second level stricter than the first level. (Program 1) A program for causing a computer to execute each of the means of the image forming apparatus according to any one of configurations 1 to 10. [Explanation of symbols]

[0089] 101 Image forming device (printing device) 108 Diagnostic Department 312 CPU (first set means) (second set means)

Claims

1. A printing device capable of performing image diagnosis using a test chart before and during printing, a first setting means for setting a diagnostic level of the image diagnostic performed during printing to a first level; and second setting means for setting a diagnostic level of the image diagnosis performed before printing to a second level stricter than the first level.

2. 2. The printing apparatus according to claim 1, further comprising a first setting unit that automatically sets the second level to a level stricter than the first level in response to a user operation.

3. The printing device is capable of performing image diagnosis following inspection of the printed matter during printing; 2. The printing apparatus according to claim 1, further comprising a second setting unit which automatically sets the first level to the same level as an inspection level of an inspection in response to a user's operation.

4. The printing device is capable of performing an inspection of the printed matter following the performance of image diagnosis during printing; 2. The printing apparatus according to claim 1, further comprising a third setting unit that automatically sets the first level to a level stricter than an inspection level of the inspection in response to a user's operation.

5. 2. The printing apparatus according to claim 1, wherein the second setting step is executed when the number of pages to be printed exceeds a specified number of pages.

6. 6. The printing apparatus according to claim 5, wherein the number of pages to be printed is a total number of pages in one print job.

7. 6. The printing apparatus according to claim 5, wherein the number of pages to be printed is a total number of pages obtained by adding up the total number of pages of a plurality of print jobs.

8. 6. The printing apparatus according to claim 5, further comprising an increase / decrease unit for increasing / decreasing the specified number of pages based on a state of the printing apparatus.

9. 2. The printing apparatus according to claim 1, wherein the second setting step is performed based on a result of a previous image diagnosis.

10. 2. The printing device according to claim 1, further comprising a response unit which, with regard to repair of the printing device, executes a response determined by image diagnosis before printing before printing, and executes a response determined by image diagnosis during printing by interrupting printing.

11. A method for controlling a printing device capable of performing image diagnosis using a test chart before and during printing, comprising the steps of: a first setting step of setting a diagnostic level of image diagnostics performed during printing to a first level; a second setting step of setting a diagnostic level of the image diagnosis performed before printing to a second level stricter than the first level.

12. A program for causing a computer to execute each of the means of the printing device according to claim 1.

Images