Image forming apparatus

Abstract

To provide an image forming apparatus that can accurately adjust a printing position when returning from a conveyance abnormality, such as paper jam.SOLUTION: An image forming apparatus 101 comprises: a printing device 107 that forms an image on a sheet; an image reading unit 231 that reads an image for adjusting an image forming condition formed on the sheet; a CPU 222 that adjusts the image forming condition based on a result of reading of the image for adjustment performed by the image reading unit 231; and a finisher 109 that is provided on the downstream side of the image reading unit 231 in a sheet conveyance direction and detects an abnormality in the conveyance of a sheet. When the abnormality in the conveyance of the sheet is detected by the finisher 109, and if the sheet on which the image for adjustment is formed is located on the upstream side in the sheet conveyance direction with respect to the sheet for which the conveyance abnormality occurs, the CPU 222 determines that reprinting of the image for adjustment on the sheet is necessary.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunction machine. [Background technology]

[0002] Printed materials produced by commercial printing presses require stable print position accuracy on both sides. Patent Document 1 discloses an image forming apparatus that aims to stabilize print position accuracy. To stabilize print position accuracy, this image forming apparatus creates an adjustment chart by printing markers on a sheet to indicate the print position (image formation position). The markers on the adjustment chart are read by an image reading sensor installed in the sheet transport path. The image forming apparatus adjusts the print position by feeding back the marker reading results to the image formation conditions.

[0003] One of the factors that hinders the stabilization of print position accuracy is fluctuations in the temperature inside the image forming device. Therefore, after printing a predetermined number of sheets, the image forming device creates an adjustment chart to adjust for fluctuations in print position caused by temperature fluctuations. The adjustment chart is discharged to a tray separate from the printed materials so that it does not get mixed in with the printed materials corresponding to the print job.

[0004] If a paper jam occurs during sheet transport, the image forming apparatus discharges any remaining sheets (residual sheets) into a tray upstream of the location where the jam occurred in the transport direction. This reduces the burden on the user who must recover from the paper jam. The residual sheets are discharged to a tray separate from the printed materials, and are reprinted after the paper jam is cleared. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-11285 Summary of the Invention [Problem to be solved by the invention]

[0006] If the remaining paper includes an adjustment chart and is ejected to the tray downstream of the image reading sensor in the transport direction due to a paper jam, the markers on the adjustment chart have already been read by the image reading sensor. Therefore, the reading results are fed back to the image formation conditions. However, depending on the time elapsed between recovery from the paper jam and resumption of printing, the internal environment of the image forming apparatus, such as the internal temperature, may differ between when the adjustment chart was read and when printing resumes. Therefore, if image formation is resumed under image formation conditions that were fed back based on the reading results of the adjustment chart when the paper jam occurred, it may not be possible to correctly adjust the print position upon resumption.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an image forming apparatus that can adjust the printing position with high precision when recovering from a transport abnormality such as a paper jam. [Means for solving the problem]

[0008] The image forming apparatus of the present invention comprises an image forming means for forming an image on a sheet based on image formation conditions, a transport path along which the sheet is transported from the image forming means, a reading means for reading an image for adjusting the image formation conditions formed on the sheet transported along the transport path, an adjustment means for adjusting the image formation conditions based on the reading result of the adjustment image by the reading means, a transport sensor provided downstream of the reading means in the transport direction of the sheet transported along the transport path and for detecting the sheet transported along the transport path, a detection means for detecting a transport jam using the transport sensor, and a control means for causing the image forming means to form the adjustment image while a print job is being executed in which the image forming means forms images on multiple sheets, wherein the control means, when a transport jam of a sheet downstream of the reading means in the transport direction is detected by the detection means during the execution of the print job, causes the image forming means to re-form the adjustment image on the sheet, even if the sheet on which the adjustment image has been formed is located upstream in the transport direction of the sheet that has become jammed. [Effects of the Invention]

[0009] According to the present invention, it is possible to adjust the print position to suit the internal environment of the image forming apparatus when recovering from a paper jam. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image processing system. [Figure 2] system configuration diagram. [Figure 3] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Figure 4] An explanatory diagram of CIS. [Figure 5] FIG. 4 is an explanatory diagram of a sheet information format. [Figure 6] FIG. [Figure 7] 10 is a flowchart showing a process of determining whether to recreate an adjustment chart. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0012] (Image forming system) 1 is a configuration diagram of an image processing system including an image forming apparatus according to this embodiment. The image processing system includes an image forming apparatus 101 and an external controller 102. The image forming apparatus 101 is, for example, a multifunction peripheral (MFP), a multifunction peripheral (MFP), etc. The external controller 102 is, for example, an image processing controller, a digital front end (DFE), a print server, etc.

[0013] The image forming apparatus 101 and the external controller 102 are communicatively connected via an internal LAN (Local Area Network) 105 and a video cable 106. The external controller 102 is connected to a client PC (Personal Computer) 103 via an external LAN 104. The external controller 102 obtains a print instruction (print job) from the client PC 103.

[0014] A printer driver that has a function of converting print data into a print description language that can be processed by the external controller 102 is installed in the client PC 103. A user can issue a print instruction from various applications via the printer driver. The printer driver transmits print data to the external controller 102 based on a print instruction from the user. The external controller 102 accepts a print instruction including print data from the client PC 103, performs data analysis and rasterization processing, and instructs the image forming apparatus 101 to print (form an image) based on the print data.

[0015] The image forming apparatus 101 is configured by connecting devices with multiple different functions, including a printing device 107, and is capable of complex printing processes such as bookbinding. The image forming apparatus 101 of this embodiment includes the printing device 107 and a finisher 109. The printing device 107 forms an image on a sheet fed from a paper feed unit provided at the bottom of the main body using a developer (e.g., toner). The printing device 107 forms images in yellow (Y), magenta (M), cyan (C), and black (K). A full-color image in which images of each color are superimposed is formed on the sheet. The sheet on which the image has been formed is transported from the printing device 107 to the finisher 109. The finisher 109 stacks the sheets on which the image has been formed.

[0016] Although this image processing system is configured such that an external controller 102 is connected to an image forming apparatus 101, the external controller 102 is not necessarily required. For example, the image forming apparatus 101 may be configured to directly receive a print instruction including print data from a client PC 103 via an external LAN 104. In this case, the image forming apparatus 101 performs the data analysis and rasterization processes that are performed by the external controller 102. In other words, the image forming apparatus 101 and the external controller 102 may be configured as an integrated unit.

[0017] (System Configuration) 2 is a system configuration diagram for controlling the operation of the image processing system. Here, the controllers that control the operation of the image forming apparatus 101, the external controller 102, and the client PC 103 will be described.

[0018] ·Printing device The printing device 107 includes a communication interface (I / F) 217, a LAN I / F 218, and a video I / F 220 for communicating with other devices. The printing device 107 includes a CPU (Central Processing Unit) 222, memory 223, storage 221, an image reading unit 231, an exposure unit 227, an image creating unit 228, a fixing unit 229, and a paper feeding unit 230 for controlling the operation of the printing device 107. The printing device 107 includes an operation unit 224 and a display 225 as user interfaces. These components are connected to each other via a system bus 232 so that they can communicate with each other.

[0019] The communication I / F 217 is connected to the finisher 109 via a communication cable 249 and controls communication with the finisher 109. When the printing device 107 and the finisher 109 operate in cooperation with each other, information and data are sent and received via the communication I / F 217. The LAN I / F 218 is connected to the external controller 102 via the internal LAN 105 and controls communication with the external controller 102. The printing device 107 receives print data indicating settings for printing and the like from the external controller 102 via the LAN I / F 218. The video I / F 220 is connected to the external controller 102 via the video cable 106 and controls communication with the external controller 102. The printing device 107 receives image data indicating an image to be formed and the like from the external controller 102 via the video I / F 220.

[0020] The CPU 222 comprehensively controls image processing and printing by executing computer programs stored in the storage 221. The memory 223 provides a work area for the CPU 222 to execute various processes. When performing image formation processing, the CPU 222 controls an exposure unit 227, an image forming unit 228, a fixing unit 229, and a paper feed unit 230.

[0021] The exposure unit 227 uniformly charges the surface of the photoconductor and irradiates the charged surface of the photoconductor with laser light based on image data. The exposure unit 227 charges the surface of the photoconductor to a uniform negative potential. The exposure unit 227 outputs laser light using a laser driver and scans the uniformly charged surface of the photoconductor with the laser light while adjusting the reflection angle of the laser light using a rotating polygonal mirror. The potential of the photoconductor changes at the position where the laser light is irradiated, and an electrostatic latent image is formed on the surface. Four photoconductors are provided corresponding to the four colors: yellow (Y), magenta (M), cyan (C), and black (K). An electrostatic latent image of a different color is formed on each of the four photoconductors.

[0022] The image forming unit 228 transfers the toner image formed on the photosensitive member onto a sheet. The image forming unit 228 includes a developing unit, a transfer unit, a toner supply unit, etc. The developing unit forms a toner image by attaching negatively charged toner from a developing cylinder to an electrostatic latent image formed on the surface of the photosensitive member. Four developing units are provided, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). The developing units visualize the electrostatic latent image on the photosensitive member using toner of the corresponding color.

[0023] The transfer unit has an intermediate transfer belt and transfers the toner image from the photosensitive drum to the intermediate transfer belt. A primary transfer roller is provided facing the photosensitive drum across the intermediate transfer belt. When a positive potential is applied to the primary transfer roller, the toner images from each of the four photosensitive drums are transferred onto the intermediate transfer belt in a superimposed state. This forms a full-color toner image on the intermediate transfer belt. The toner image formed on the intermediate transfer belt is transferred to a sheet by a secondary transfer roller. When a positive potential is applied to the secondary transfer roller, the full-color toner image is transferred from the intermediate transfer belt to a sheet.

[0024] The fixing unit 229 fixes the transferred toner image onto the sheet. The fixing unit 229 applies heat and pressure to the toner image on the sheet to melt and fix the toner image to the sheet. This forms an image on the sheet. The paper feed unit 230 is equipped with rollers such as conveyance rollers and various sensors on the conveyance path, and controls the sheet feeding operation.

[0025] The image reading unit 231 reads an image formed on a conveyed sheet based on instructions from the CPU 222. The CPU 222 reads an image for adjusting image formation conditions formed on the sheet by the image reading unit 231, for example, when adjusting the print position on the front and back surfaces of the sheet, adjusting image density, or adjusting color misalignment. In this embodiment, print position adjustment markers formed on both sides of the sheet are read as the image for print position adjustment. The image formation conditions in this embodiment are correction amounts for correcting deviations from the ideal print position. The CPU 222 acquires geometric characteristics of the image from the read marker positions and determines the correction amount based on the acquired geometric characteristics and the ideal geometric characteristics. The CPU 222 performs image processing on the image data based on the correction amount, thereby adjusting the print position so that the image is formed in the ideal position on the sheet. For example, affine transformation is used as image processing for adjusting the print position. The operation unit 224 is an input device that accepts various setting inputs and operation instructions from the user. The operation unit 224 is, for example, various input keys, a touch panel, etc. The display 225 is an output device that displays setting information of the image forming apparatus 101, the processing status of a print job, etc.

[0026] Finisher The finisher 109 is, for example, a large-capacity stacker. The finisher 109 includes a communication I / F 241, a CPU 242, a memory 243, and a paper discharge control unit 244. These components are connected to each other via a system bus 245 so that they can communicate with each other. The communication I / F 241 is connected to the printing device 107 via a communication cable 249 and controls communication between the printing device 107. When the finisher 109 and the printing device 107 operate in cooperation with each other, information and data are sent and received via the communication I / F 241. The CPU 242 executes a control program stored in the memory 243 and performs various controls necessary for paper discharge. The memory 243 stores the control program. The memory 243 also provides a work area when the CPU 242 executes various processes. The paper discharge control unit 244 transports the transported sheet to a stack tray based on instructions from the CPU 242.

[0027] External Controller The external controller 102 includes a LAN I / F 213, a LAN I / F 214, and a video I / F 215 for communicating with other devices. The external controller 102 includes a CPU 208, a memory 209, and a storage 210 for controlling the operation of the external controller 102. The external controller 102 includes a keyboard 211 and a display 212 as user interfaces. These components are connected to each other via a system bus 216 so that they can communicate with each other.

[0028] The LAN I / F 213 is connected to the client PC 103 via the external LAN 104 and controls communication with the client PC 103. The external controller 102 acquires print instructions and the like from the client PC 103 via the LAN I / F 213. The LAN I / F 214 is connected to the printing device 107 via the internal LAN 105 and controls communication with the printing device 107. The external controller 102 transmits print data and the like indicating settings for printing to the printing device 107 via the LAN I / F 214. The video I / F 215 is connected to the printing device 107 via the video cable 106 and controls communication with the printing device 107. The external controller 102 transmits image data and the like to the printing device 107 via the video I / F 215.

[0029] The CPU 208 executes computer programs stored in the storage 210 to comprehensively perform processes such as receiving print data acquired from the client PC 103, RIP processing, and transmitting the print data to the image forming apparatus 101. The memory 209 provides a work area for the CPU 208 to perform various processes. The keyboard 211 is an input device that accepts various setting inputs and operation instructions from the user. The display 212 is an output device that displays information such as applications executed by the external controller 102 using still images and moving images.

[0030] Client PC The client PC 103 includes a CPU 201, a memory 202, a storage 203, a keyboard 204, a display 205, and a LAN I / F 206. These components are connected via a system bus 207 so that they can communicate with each other.

[0031] The CPU 201 controls the operation of the client PC 103 by executing computer programs stored in the storage 203. In this embodiment, the CPU 201 creates print data and transmits print instructions. The memory 202 provides a work area for the CPU 201 to execute various processes. The keyboard 204 and display 205 are user interfaces. The keyboard 204 is an input device that accepts instructions from a user. The display 205 is an output device that displays information such as applications executed by the client PC 103 as still images or moving images. The LAN I / F 206 is connected to the external controller 102 via the external LAN 104 and controls communication with the external controller 102. The client PC 103 transmits print instructions and the like to the external controller 102 via the LAN I / F 206.

[0032] The external controller 102 and image forming apparatus 101 are connected via an internal LAN 105 and a video cable 106, but any other configuration is acceptable as long as they are capable of transmitting and receiving the data necessary for printing, and for example, they may be connected via only a video cable.Memory 202, memory 209, memory 223, and memory 243 may each be a storage device for holding data and programs.These memories may be, for example, volatile random access memory (RAM), non-volatile read only memory (ROM), storage, universal serial bus (USB) memory, etc.

[0033] (Configuration of image forming device) 3 is a configuration diagram of the image forming apparatus 101. A display 225 is provided on top of the printing device 107. The display 225 displays information on the printing status and settings of the image forming apparatus 101. Sheets on which images have been formed by the printing device 107 are transported to a finisher 109 provided downstream.

[0034] The printing device 107 includes, as the paper feed unit 230, paper feed decks 301 and 302 and a transport path 303. Each paper feed deck 301 and 302 can accommodate different types of sheets. The top sheet of each paper feed deck 301 and 302 is separated and fed to the transport path 303. The printing device 107 includes, as the exposure unit 227, image forming units 304, 305, 306, and 307 for forming images. The printing device 107 forms color images. To this end, the image forming unit 304 forms a black (K) image (toner image). The image forming unit 305 forms a cyan (C) image (toner image). The image forming unit 306 forms a magenta (M) image (toner image). The image forming unit 307 forms a yellow (Y) image (toner image).

[0035] The printing device 107 includes, as the image creation unit 228, an intermediate transfer belt 308 onto which toner images are transferred from the image forming units 304, 305, 306, and 307, and a secondary transfer roller 309. The intermediate transfer belt 308 rotates clockwise in the figure, and toner images are transferred and superimposed on each other from the image forming units 307, 306, 305, and 304 in this order. As a result, a full-color toner image is formed on the intermediate transfer belt 308. The intermediate transfer belt 308 conveys the toner image to the secondary transfer roller 309 as it rotates. A sheet is conveyed to the secondary transfer roller 309 in synchronization with the timing at which the toner image is conveyed to the secondary transfer roller 309. The secondary transfer roller 309 transfers the toner image on the intermediate transfer belt 308 onto the conveyed sheet.

[0036] The printing apparatus 107 includes a first fuser 311 and a second fuser 318 as the fuser unit 229. The first fuser 311 and the second fuser 318 have the same configuration and fuse a toner image onto a sheet. To this end, the first fuser 311 and the second fuser 318 each include a pressure roller and a heating roller. The sheet is heated and pressurized as it passes between the pressure roller and the heating roller, melting and bonding the toner image to the sheet. After passing through the second fuser 318, the sheet is transported to a transport path 314. The second fuser 318 is located downstream of the first fuser 311 in the sheet transport direction and is used to add gloss to the image on the sheet that has been fused by the first fuser 311 and to ensure fixation. For this reason, the second fuser 318 may not be used depending on the type of sheet and the content of the image formation process. A conveying path 312 is provided to convey the sheet that has undergone the fixing process in the first fixing device 311 without passing through the second fixing device 318.

[0037] A conveying path 315 and a reversing path 316 are provided after the conveying path 314 and the conveying path 312 join together. When double-sided printing is instructed, the sheet is conveyed to the reversing path 316. The conveying direction of the sheet conveyed to the reversing path 316 is reversed by the reversing path 316, and the sheet is conveyed to a double-sided conveying path 317. The reversing path 316 and the double-sided conveying path 317 reverse the side on which the image has been formed (first side). The sheet is conveyed to the conveying path 303 by the double-sided conveying path 317, and passes through a secondary transfer roller 309 and a fixing unit 229, where an image is formed on the second side.

[0038] In the case of single-sided printing, or in the case of double-sided printing in which images are formed on both sides, the sheet is conveyed to a conveying path 315. A conveying path 323 is disposed downstream of the conveying path 315 in the sheet conveying direction.

[0039] On the conveying path 323, CISs (Contact Image Sensors) 321 and 322 are arranged opposite each other across the conveying path 323 as the image reading unit 231. FIG. 4 is an explanatory diagram of the CISs 321 and 322. The CIS 321 is an optical sensor that reads an image of the upper surface (second surface) of a sheet conveyed on the conveying path 323. The CIS 322 is an optical sensor that reads an image of the lower surface (first surface) of a sheet conveyed on the conveying path 323.

[0040] The CIS 321 includes an LED (Light Emitting Diode) 350 as a light source, a reading sensor 351 as a light receiving unit, and a white reference plate 352. The LED 350 irradiates the upper surface of the sheet when the sheet conveyed along the conveyance path 323 reaches the reading position. The reading sensor 351 receives the light reflected by the sheet, performs photoelectric conversion of the received reflected light, and transmits the reading result, which is an electrical signal, to the CPU 222. In this manner, the image formed on the sheet is read. The reading sensor 351 includes multiple light receiving elements (photoelectric conversion elements) in a direction perpendicular to the sheet conveyance direction. Therefore, the direction perpendicular to the sheet conveyance direction is the main scanning direction of the CIS 321. The white reference plate 352 is used during calibration of the CIS 321. During calibration, the white reference plate 352 moves to a position where it is irradiated with light from the LED 350, and the reflected light is received by the reading sensor 351. The CIS 321 is calibrated based on the reading result of the white reference plate 352 .

[0041] Like CIS 321, CIS 322 includes an LED 353, a reading sensor 354, and a white reference plate 355. CIS 322 operates in the same manner as CIS 321, and reads an image formed on the lower surface of a sheet when the sheet conveyed along conveyance path 323 reaches the reading position. Note that, in addition to CISs 321 and 322, image reading unit 231 can also be realized by a CCD sensor or a CMOS sensor.

[0042] In this embodiment, markers are formed on the sheet to adjust the position of the image formed on both sides. The sheet on which the markers are formed is called an adjustment chart. The printing device 107 creates an adjustment chart by printing markers on both sides of the sheet, and the CIS 321 and CIS 322 read the markers on both sides. The results of reading the adjustment chart by the CIS 321 and CIS 322 are stored in the memory 223. The CPU 222 refers to the memory 223 and feeds back the results of reading by the CIS 321 and CIS 322 to the image formation conditions to adjust the print position.

[0043] When the internal temperature of the printing device 107 rises, the position of the image formed on the sheet fluctuates compared to when the internal temperature of the printing device 107 is low. In this case, the printing device 107 creates an adjustment chart, obtains the amount of fluctuation based on the reading results of the CISs 321 and 322, and adjusts the print position based on the amount of fluctuation so that the print position is the same as when the internal temperature is low. In this way, the printing device 107 stabilizes the print position accuracy.

[0044] The adjustment chart is removed so as not to be mixed in with the printed matter corresponding to the print job. To this end, the printing apparatus 107 is equipped with a flapper 324, a discharge path 326, a transport sensor 327, and a discharge tray 328. The adjustment chart, whose image (marker) has been read by the CISs 321 and 322, is transported to the discharge path 326 by the flapper 324. The sheet transported to the discharge path 326 is discharged to the discharge tray 328.

[0045] If the sheet is not an adjustment chart, the sheet is transported by a flapper 324 from a transport path 323 to a downstream transport path 325. The sheet transported to the downstream transport path 325 is delivered to the finisher 109. When the printing device 107 receives a notification of a transport jam from the finisher 109, it switches the flapper 324 to the discharge path 326 side, regardless of whether the sheet is an adjustment chart or not, and discharges all sheets (residual sheets) in the machine to a discharge tray 328. Discharging the residual sheets to the discharge tray 328 reduces the burden on the user of clearing the jam.

[0046] The finisher 109 can stack a large number of sheets delivered from the printing device 107. The finisher 109 has a transport path 331 and a stack tray 332 on which sheets are stacked. Transport sensors 333, 334, 335, and 336 are provided on the transport path 331. Sheets transported from the printing device 107 are stacked on the stack tray 332 via the transport path 331. The transport sensors 333, 334, 335, and 336 detect the passage of a sheet transported along the transport path 331. If the transport sensors 333, 334, 335, and 336 do not detect the leading or trailing edge of the sheet in the transport direction even after a predetermined time has elapsed since the start of sheet transport, the CPU 242 determines that a transport jam (transport abnormality) has occurred in the finisher 109. In this case, the CPU 242 notifies the printing device 107 that a transport jam has occurred. The finisher 109 detects abnormality in sheet transport downstream of the CISs 321 and 322 in the sheet transport direction.

[0047] FIG. 5 is an explanatory diagram of the format of information (sheet information) for sheets on which the printing device 107 forms images. The sheet information is saved as a queue in the memory 223. Therefore, the sheet information clarifies the chronological relationship of each sheet. The sheet information includes the sheet size, basis weight, discharge destination, reprint setting, adjustment chart information, escape information, etc. The reprint setting indicates whether or not reprinting is to be performed. The adjustment chart information indicates whether or not the sheet is an adjustment chart. The escape information indicates whether or not the sheet is to be discharged to the discharge tray 328. The CPU 222 controls the sheet transport, etc., based on the sheet information.

[0048] For example, when a transport jam occurs in the finisher 109, the CPU 222 sets the escape information of the sheet information of all sheets located upstream of the jammed paper in the transport direction to "escape." If the escape information of a sheet transported upstream of the transport path 323 is set to "escape," the CPU 222 switches the flapper 324 to the discharge path 326 side and discharges the sheet to the discharge tray 328 via the discharge path 326.

[0049] (Adjustment chart insertion mode) An adjustment chart is created each time a predetermined number of sheets are printed. In other words, the print position is adjusted each time a predetermined number of sheets are printed. The predetermined number of sheets can be set by the user. The setting of the predetermined number of sheets sets the interval at which the print position is adjusted.

[0050] 6 is a view showing an example of a setting screen for setting the interval for creating an adjustment chart. The setting screen is displayed on the display 225 by the CPU 222. The adjustment chart is created in an adjustment mode, which is set by the user using the operation unit 224.

[0051] Fig. 6(a) shows the initial screen. When the user selects the softkey "Advanced Mode" from the initial screen, the CPU 222 displays the advanced mode selection screen of Fig. 6(b) on the display 225. When the user selects the softkey "Adjust" from the advanced mode selection screen, the CPU 222 displays the adjustment mode selection screen of Fig. 6(c) on the display 225. Selecting "Adjust" puts the printing device 107 into adjustment mode. When the user selects the softkey "Close" from the advanced mode selection screen, the CPU 222 displays the initial screen on the display 225.

[0052] When the user selects the soft key "Predetermined Interval" on the adjustment mode selection screen, the CPU 222 displays the insertion interval setting screen of Fig. 6(d) on the display 225. When the user selects the soft key "Back" on the adjustment mode selection screen, the CPU 222 displays the application mode selection screen on the display 225.

[0053] When the user inputs the number of sheets for the insertion interval using the numeric keypad on the insertion interval setting screen and selects the soft key "OK," the CPU 222 sets the number of sheets for the insertion interval of the adjustment chart. When "OK" is selected, the CPU 222 stores the number of sheets for the insertion interval input on the insertion interval setting screen in the memory 223. When the user selects the soft key "Cancel setting" on the insertion interval setting screen, the CPU 222 displays an adjustment mode selection screen on the display 225.

[0054] The CPU 222 notifies the external controller 102 of the number of sheets for the insertion interval stored in the memory 223. The external controller 102 stores the notified number of sheets for the insertion interval in the memory 209. When printing has been performed on the number of sheets for the insertion interval, the external controller 102 instructs the printing device 107 to create an adjustment chart. For example, if "200" is entered on the insertion interval setting screen and "OK" is selected, the printing device 107 is instructed by the external controller 102 to print an adjustment chart every time 200 sheets are printed. If a print job instructs printing 1000 sheets, the printing device 107 creates adjustment charts between pages 200 and 201, between pages 400 and 401, between pages 600 and 601, and between pages 800 and 801.

[0055] As described above, the predetermined number of sheets (insertion interval number of sheets) that indicates the timing at which an adjustment chart is created is set. Here, an example has been described in which the insertion interval number is set by the printing device 107, but the insertion interval number may also be set by the external controller 102 or the client PC 103. When the external controller 102 is used, each screen in FIG. 6 is displayed on the display 212. When the client PC 103 is used, each screen in FIG. 6 is displayed on the display 205. The set insertion interval number is notified from the client PC 103 to the external controller 102.

[0056] (Reprint decision process) 7 is a flowchart showing the process of determining whether to recreate the adjustment chart. This process starts when the transport sensor 327 detects the leading edge of the sheet in the transport direction. The transport sensor 327 detects the sheet when a transport jam occurs in the finisher 109 and the sheet is transported to the discharge path 326.

[0057] When the transport sensor 327 detects the leading edge of the sheet, the CPU 222 determines whether the sheet being transported is an adjustment chart (S1001). The CPU 222 makes this determination by referring to the adjustment chart information in the sheet information stored in the memory 223. The adjustment chart information is set when the CPU 222, upon receiving an instruction to print an adjustment chart, creates sheet information for creating an adjustment chart. The instruction to print an adjustment chart is notified from the external controller 102 each time printing is performed on the number of sheets corresponding to the insertion interval.

[0058] If it is not an adjustment chart (S1001: N), the CPU 222 sets reprinting in the reprint settings of the sheet information so that reprinting according to the print job is performed on the sheet, and ends the process (S1002). Because reprinting is set, the CPU 222 prints an image according to the print job on the sheet when printing resumes.

[0059] If it is an adjustment chart (S1001: Y), the CPU 222 determines whether or not reprinting of the adjustment chart is necessary (S1003). The CPU 222 determines whether or not reprinting is necessary based on the escape information of the sheet information stored in the memory 223.

[0060] If "Escape" is set in the escape information, the CPU 222 determines that the adjustment chart is a sheet located upstream in the transport direction from the sheet that caused the jam. In other words, the print position adjusted based on the results of reading the adjustment chart may not match the internal environment of the printing device 107, such as the internal temperature, when the printing device 107 recovers from the jam. Therefore, the CPU 222 determines that reprinting is necessary (S1003: Y). The CPU 222 sets "Reprint" in the reprint settings of the sheet information so that the marker is reprinted on the sheet, and ends the process (S1002). If "Escape" is not set in the escape information, the CPU 222 determines that reprinting is not necessary and ends the process (S1003: N).

[0061] The following describes a case where 1,000 sheets are printed with the adjustment chart insertion interval set to 200 sheets. If a jam occurs while the 399th page of the sheet is being transported by the finisher 109, the adjustment chart printed between the printed 400th and 401st pages can be read by the CIS 321 and 322, but it is determined that reprinting is necessary. After the jam is cleared, the adjustment chart is reprinted and read by the CIS 321 and 322. The read result is fed back to the image formation conditions and used to adjust the print position.

[0062] In this way, the image formation conditions are adjusted based on the results of reading the adjustment chart after the jam is cleared, not when the jam occurs, which makes it possible to adjust the print position to suit the internal environment of the printing device 107, such as the internal temperature, when the jam is cleared.

Claims

1. an image forming means for forming an image on a sheet based on image forming conditions; a conveying path along which the sheet is conveyed from the image forming means; a reading unit for reading an image for adjusting the image forming conditions formed on the sheet conveyed along the conveying path; an adjusting unit that adjusts the image forming conditions based on the result of reading the image for adjustment by the reading unit; a conveyance sensor provided downstream of the reading means in a conveyance direction of the sheet conveyed on the conveyance path, the conveyance sensor detecting the sheet conveyed on the conveyance path; a detection unit for detecting a transport jam using the transport sensor; a control unit that causes the image forming unit to form the adjustment image while the image forming unit is executing a print job that forms images on a plurality of sheets, When the detection means detects a transport jam of a sheet downstream of the reading means in the transport direction during execution of the print job, the control means causes the image forming means to re-form the adjustment image on the sheet even if the sheet on which the adjustment image is formed is located upstream of the jammed sheet in the transport direction. Image forming device.

2. the control means causes the image forming means to form the adjustment image on the sheet every time the number of sheets on which the image has been formed by the image forming means reaches a predetermined number.

2. The image forming apparatus according to claim 1.

3. The method further comprises input means for setting the predetermined number of sheets.

3. The image forming apparatus according to claim 2.

4. a first tray onto which a sheet on which an image corresponding to a print job is formed is discharged; and a second tray to which the sheet on which the adjustment image is formed is discharged.

2. The image forming apparatus according to claim 1.

5. When the detection means detects a jam of a sheet downstream of the reading means in the conveying direction, a sheet upstream of the jammed sheet in the conveying direction is discharged to the second tray.

5. The image forming apparatus according to claim 4.

6. Further, a storage unit is provided for storing information on a sheet on which an image is formed by the image forming unit, The control unit sets information indicating that the image needs to be reformed in sheet information of the sheet on which the adjustment image is reformed.

2. The image forming apparatus according to claim 1.

7. the image forming means forms an image for adjusting the print position on both sides of the sheet to create an adjustment chart; the reading unit includes a first reading sensor that reads the adjustment image formed on a first side of the adjustment chart, and a second reading sensor that reads the adjustment image formed on a second side of the adjustment chart, the adjusting means adjusts the print position by feeding back the reading results by the first reading sensor and the reading results by the second reading sensor to the image forming conditions.

2. The image forming apparatus according to claim 1.

8. The first reading sensor and the second reading sensor are optical sensors.

8. The image forming apparatus according to claim 7.

9. The detection means determines that a transport jam has occurred when the transport sensor does not detect the leading edge or trailing edge of the sheet in the transport direction even after a predetermined time has elapsed since the start of transport of the sheet.

2. The image forming apparatus according to claim 1.

10. the adjusting unit adjusts the image forming conditions based on a reading result by the reading unit of the image for adjustment re-formed by the image forming unit when the detecting unit detects a transport jam of a sheet downstream of the reading unit in the transport direction during execution of the print job.

2. The image forming apparatus according to claim 1.

Images