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 copier, a facsimile, or a multifunction peripheral. [Background technology]

[0002] Printed materials produced by commercial printing machines require stable print position accuracy on both sides. Patent Document 1 discloses an image forming device that aims to stabilize print position accuracy. To stabilize the print position accuracy, this image forming device creates an adjustment chart by printing a marker on a sheet to mark the print position (image formation position). The marker on the adjustment chart is read by an image reading sensor provided on the sheet transport path. The image forming device adjusts the print position by feeding back the marker reading result to the image formation conditions.

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

[0004] When a paper jam occurs during sheet transport, the image forming apparatus discharges the sheet (residual paper) remaining in the apparatus to a tray upstream in the transport direction from the position where the paper jam occurred. This reduces the burden on the user who performs recovery from the paper jam. The residual paper is discharged to a tray different from the printed matter, and is reprinted after recovery from the paper jam. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-11285 A Summary of the Invention [Problem to be solved by the invention]

[0006] When the remaining paper includes an adjustment chart and is discharged 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 result is fed back to the image forming conditions. However, depending on the time that elapses from recovery from the paper jam until printing is resumed, the internal environment of the image forming apparatus, such as the internal temperature, may differ between when the adjustment chart is read and when printing is resumed. Therefore, if image formation is resumed under image forming conditions that are fed back based on the reading result of the adjustment chart when the paper jam occurred, there is a possibility that the print position at the time of resumption may not be adjusted correctly.

[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 is characterized by comprising an image forming means for forming an image on a sheet, a reading means for reading an image for adjusting image formation conditions formed on the sheet, an adjustment means for adjusting the image formation conditions based on the reading result of the adjustment image by the reading means, a detection means provided downstream of the reading means in the sheet transport direction for detecting a transport abnormality in the sheet, and a judgment means for determining that reprinting of the adjustment image on the sheet is necessary when a sheet on which the adjustment image has been formed is located upstream in the sheet transport direction from the sheet with the transport abnormality detected by the detection means. Effect 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 description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of an image processing system. [Diagram 2] system configuration diagram. [Diagram 3] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Figure 4] Diagram of CIS. [Diagram 5] FIG. 4 is an explanatory diagram of a format of sheet information. [Figure 6] FIG. [Figure 7] 11 is a flowchart showing a process of determining whether to re-create an adjustment chart. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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), 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 having 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 a plurality of devices having 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 a 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 by 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] In this image processing system, an external controller 102 is connected to an image forming apparatus 101, but the external controller 102 is not necessarily required. For example, the image forming apparatus 101 may be configured to directly receive print instructions 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 performed by the external controller 102. In other words, the image forming apparatus 101 and the external controller 102 may be integrated into one unit.

[0017] (System Configuration) 2 is a system configuration diagram for controlling the operation of the image processing system. Here, controllers for controlling 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, a memory 223, a storage 221, an image reading unit 231, an exposure unit 227, an image creating unit 228, a fixing unit 229, and a paper feed 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 as to be able to 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 work together, information and data are transmitted 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 and the like representing settings at the time of printing from the external controller 102 via the LAN I / F 218. The video I / F 220 is connected to the external controller 102 via a video cable 106 and controls communication with the external controller 102. The printing device 107 receives image data and the like representing an image to be formed 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 polygon mirror. The potential of the photoconductor at the position irradiated with the laser light fluctuates, and an electrostatic latent image is formed on the surface. Four photoconductors are provided corresponding to four colors: yellow (Y), magenta (M), cyan (C), and black (K). Electrostatic latent images of different colors are formed on the four photoconductors.

[0022] The image forming unit 228 transfers the toner image formed on the photoconductor to a sheet. The image forming unit 228 includes a developing unit, a transfer unit, a toner supply unit, and the like. 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 photoconductor. Four developing units are provided corresponding to the four colors of yellow (Y), magenta (M), cyan (C), and black (K). The developing units make the electrostatic latent image on the photoconductor visible with toner of the corresponding color.

[0023] The transfer unit has an intermediate transfer belt and transfers a toner image from the photoconductor to the intermediate transfer belt. A primary transfer roller is provided at a position facing the photoconductor across the intermediate transfer belt. A positive potential is applied to the primary transfer roller, so that the toner images from each of the four photoconductors are transferred to 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. A positive potential is applied to the secondary transfer roller, so that the full-color toner image is transferred from the intermediate transfer belt to the 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 onto the sheet. This forms an image on the sheet. The paper feed unit 230 includes rollers such as a conveying roller and various sensors on the conveying path, and controls the sheet feeding operation.

[0025] The image reading unit 231 reads an image formed on a sheet being conveyed based on an instruction from the CPU 222. The CPU 222 reads an image for adjusting the image forming conditions formed on the sheet by the image reading unit 231, for example, when performing print position adjustment, image density adjustment, color shift adjustment, etc. on the front and back sides of the sheet. In this embodiment, a marker for adjusting the print position formed on both sides of the sheet is read as an image for adjusting the print position. The image forming conditions in this embodiment are a correction amount for correcting a deviation from an ideal print position. The CPU 222 acquires the geometric characteristics of the image from the read marker position, and determines the correction amount based on the acquired geometric characteristics and the ideal geometric characteristics. The CPU 222 adjusts the print position so that the image is formed at an ideal position on the sheet by performing image processing on the image data based on the correction amount. For example, affine transformation is used as the 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, and the like.

[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 with the printing device 107. When the finisher 109 and the printing device 107 operate in cooperation with each other, information and data are transmitted and received via the communication I / F 241. The CPU 242 executes a control program stored in the memory 243 and performs various controls required 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 conveys the conveyed sheet to a stack tray based on an instruction 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 as to be able to 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 and the like at the time of 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 execute various processes. The keyboard 211 is an input device that accepts input of various settings 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 as 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 as to be able to communicate with each other.

[0031] The CPU 201 controls the operation of the client PC 103 by executing a computer program stored in the storage 203. In this embodiment, the CPU 201 creates print data and transmits a print instruction. The memory 202 provides a work area for the CPU 201 to execute various processes. The keyboard 204 and the 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 an application executed by the client PC 103 as a still image or a moving image. 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 a print instruction or the like to the external controller 102 via the LAN I / F 206.

[0032] The external controller 102 and the image forming apparatus 101 are connected by an internal LAN 105 and a video cable 106, but any other configuration is acceptable as long as data necessary for printing can be transmitted and received, and for example, the connection may be made by only a video cable. Each of the memory 202, the memory 209, the memory 223, and the memory 243 may be a storage device for holding data and programs. For example, a volatile RAM (Random Access Memory), a non-volatile ROM (Read Only Memory), a storage, a USB (Universal Serial Bus) memory, etc. may be used as these memories.

[0033] (Configuration of Image Forming Apparatus) 3 is a configuration diagram of the image forming apparatus 101. A display 225 is provided on the top of the printing device 107. The display 225 displays information on the printing status and settings of the image forming apparatus 101. The sheet on which an image has been formed by the printing device 107 is transported to a finisher 109 provided at a subsequent stage.

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

[0035] The printing device 107 includes, as the image creating unit 228, an intermediate transfer belt 308 and a secondary transfer roller 309 onto which toner images are transferred from the image forming units 304, 305, 306, and 307. The intermediate transfer belt 308 rotates clockwise in the figure, and the toner images are transferred and superimposed on each other in the order of the image forming units 307, 306, 305, and 304. 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 by rotating. A sheet is conveyed to the secondary transfer roller 309 in accordance 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 to the conveyed sheet.

[0036] The printing device 107 includes a first fixing device 311 and a second fixing device 318 as the fixing unit 229. The first fixing device 311 and the second fixing device 318 have the same configuration and fix the toner image to the sheet. For this purpose, the first fixing device 311 and the second fixing device 318 each include a pressure roller and a heating roller. The sheet is heated and pressurized by passing between the pressure roller and the heating roller, and the toner image is melted and pressed onto the sheet. The sheet that has passed the second fixing device 318 is conveyed to the conveying path 314. The second fixing device 318 is disposed downstream of the first fixing device 311 in the sheet conveying direction, and is used to add gloss to the image on the sheet that has been fixed by the first fixing device 311 and to ensure fixability. For this purpose, the second fixing device 318 may not be used depending on the type of sheet and the contents of the image forming process. In order to transport the sheet subjected to the fixing process by the first fixing device 311 without passing through the second fixing device 318, a transport path 312 is provided.

[0037] After the conveying path 314 and the conveying path 312 join, a conveying path 315 and an inversion path 316 are provided. When double-sided printing is instructed, the sheet is conveyed to the inversion path 316. The conveying direction of the sheet conveyed to the inversion path 316 is inverted by the inversion path 316, and the sheet is conveyed to a double-sided conveying path 317. The inversion path 316 and the double-sided conveying path 317 invert the side on which the image is 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, whereby 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 facing 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 the 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 the 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 light onto the upper surface of the sheet when the sheet conveyed on the conveying 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, an image formed on the sheet is read. The reading sensor 351 includes a plurality of light receiving elements (photoelectric conversion elements) in a direction perpendicular to the conveying direction of the sheet. Therefore, the direction perpendicular to the conveying direction of the sheet 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 light is irradiated from the LED 350, and the reflected light is received by the reading sensor 351. The CIS 321 is calibrated based on the results of reading the white reference plate 352 .

[0041] Similarly to CIS 321, CIS 322 includes an LED 353, a reading sensor 354, and a white reference plate 355. CIS 322 operates similarly to CIS 321, and reads an image formed on the lower surface of a sheet when the sheet conveyed along conveyance path 323 reaches a reading position. Note that, in addition to CIS 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 prints the markers on both sides of the sheet to create an adjustment chart, 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. For this purpose, the printing apparatus 107 is provided 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 CIS 321, 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 from the transport path 323 to the downstream transport path 325 by the flapper 324. The sheet transported to the downstream transport path 325 is delivered to the finisher 109. When the printing device 107 receives a notification of the occurrence of a transport jam from the finisher 109, the printing device 107 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 the 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 includes a transport path 331 and a stack tray 332 for stacking sheets. The transport path 331 is provided with transport sensors 333, 334, 335, and 336. 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 end 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) of sheets on which the printing device 107 forms an image. The sheet information is stored 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 to perform reprinting. The adjustment chart information indicates whether or not the sheet is an adjustment chart. The escape information indicates whether or not to discharge the sheet to the discharge tray 328. The CPU 222 controls the sheet transport and the like 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) The adjustment chart is created every time a predetermined number of sheets are printed. In other words, the print position is adjusted every time a predetermined number of sheets are printed. The predetermined number can be set by the user. The adjustment interval for the print position is set by setting the predetermined number of sheets.

[0050] 6 is a view showing an example of a setting screen for setting an 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, and the adjustment mode 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. Selection of "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 softkey "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 softkey "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 softkey "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 softkey "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 is performed on the sheets for the number of sheets for the insertion interval, the external controller 102 instructs the printing device 107 to create an adjustment chart. For example, when "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. When 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 (insertion interval number) which is the timing for creating the adjustment chart 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 to the external controller 102 from the client PC 103.

[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 conveyance sensor 327 detects the leading edge of the sheet, the CPU 222 judges whether the sheet being conveyed is an adjustment chart or not (S1001). The CPU 222 makes this judgment by referring to the adjustment chart information of the sheet information stored in the memory 223. The adjustment chart information is set when the CPU 222, upon receiving an instruction to print the adjustment chart, creates sheet information for creating the adjustment chart. The instruction to print the adjustment chart is notified by the external controller 102 every time printing of the number of sheets corresponding to the insertion interval is performed.

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

[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 result of reading the adjustment chart may not match the internal environment of the printer 107, such as the internal temperature, when the printer 107 is restored from the jam. For this reason, the CPU 222 determines that reprinting is necessary (S1003: Y). The CPU 222 sets reprinting in the reprint setting 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 unnecessary and ends the process (S1003: N).

[0061] A case will be described where 1000 sheets are printed with the insertion interval number of adjustment charts set to 200 sheets. If a jam occurs while the 399th page 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, 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, 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 forming 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 printer 107, such as the internal temperature, when the jam is cleared.

Claims

1. an image forming means for forming an image on a sheet; a reading means for reading an image for adjusting image forming conditions formed on the sheet; an adjustment unit that adjusts an image forming condition based on a result of reading the adjustment image by the reading unit; a detection unit provided downstream of the reading unit in a sheet conveying direction, the detection unit detecting an abnormality in conveyance of the sheet; and a determining means for determining that it is necessary to reprint the adjustment image on the sheet when the detection means detects a sheet transport abnormality and the sheet on which the adjustment image is formed is located upstream of the sheet with the transport abnormality in the sheet transport direction. Image forming device.

2. the image forming means forms the adjustment image on the sheet each time the number of sheets on which the images have been formed reaches a predetermined number, 2. The image forming apparatus according to claim 1.

3. The present invention is characterized in that the device further comprises an 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. The image forming apparatus according to any one of claims 1 to 3.

5. When the detection means detects a transport abnormality of the sheet, a sheet on an upstream side in a sheet transport direction from the sheet having the transport abnormality is discharged to the second tray.

5. The image forming apparatus according to claim 4.

6. The image forming device further includes a storage device for storing information on a sheet on which an image is formed by the image forming device, the determining unit sets information indicating that reprinting is required to sheet information of the sheet for which it has been determined that reprinting of the adjustment image is required, The image forming apparatus according to any one of claims 1 to 5.

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 means 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 adjustment unit adjusts the print position by feeding back the reading result by the first reading sensor and the reading result by the second reading sensor to the image forming conditions. The image forming apparatus according to any one of claims 1 to 6.

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 is characterized in that it includes a transport sensor that detects the passage of the sheet on a transport path along which the sheet is transported, and determines that a transport abnormality has occurred when the transport sensor does not detect the leading or trailing end of the sheet in the transport direction even after a predetermined time has elapsed since the start of transport of the sheet. The image forming apparatus according to any one of claims 1 to 8.

Images